Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

41 files changed, 12267 insertions, 0 deletions

diff --git a/python/mozbuild/mozpack/__init__.py b/python/mozbuild/mozpack/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/python/mozbuild/mozpack/__init__.py
diff --git a/python/mozbuild/mozpack/apple_pkg/Distribution.template b/python/mozbuild/mozpack/apple_pkg/Distribution.template
new file mode 100644
index 0000000000..2f4b9484d9
--- /dev/null
+++ b/python/mozbuild/mozpack/apple_pkg/Distribution.template
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<installer-gui-script minSpecVersion="1">
+    <pkg-ref id="${CFBundleIdentifier}">
+        <bundle-version>
+            <bundle CFBundleShortVersionString="${CFBundleShortVersionString}" CFBundleVersion="${CFBundleVersion}" id="${CFBundleIdentifier}" path="${app_name}.app"/>
+        </bundle-version>
+    </pkg-ref>
+    <options customize="never" require-scripts="false" hostArchitectures="x86_64,arm64"/>
+    <choices-outline>
+        <line choice="default">
+            <line choice="${CFBundleIdentifier}"/>
+        </line>
+    </choices-outline>
+    <choice id="default"/>
+    <choice id="${CFBundleIdentifier}" visible="false">
+        <pkg-ref id="${CFBundleIdentifier}"/>
+    </choice>
+    <pkg-ref id="${CFBundleIdentifier}" version="${simple_version}" installKBytes="${installKBytes}">#${app_name_url_encoded}.pkg</pkg-ref>
+</installer-gui-script>
\ No newline at end of file
diff --git a/python/mozbuild/mozpack/apple_pkg/PackageInfo.template b/python/mozbuild/mozpack/apple_pkg/PackageInfo.template
new file mode 100644
index 0000000000..74d47e396c
--- /dev/null
+++ b/python/mozbuild/mozpack/apple_pkg/PackageInfo.template
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<pkg-info overwrite-permissions="true" relocatable="false" identifier="${CFBundleIdentifier}" postinstall-action="none" version="${simple_version}" format-version="2" generator-version="InstallCmds-681 (18F132)" install-location="/Applications" auth="root">
+    <payload numberOfFiles="${numberOfFiles}" installKBytes="${installKBytes}"/>
+    <bundle path="./${app_name}.app" id="${CFBundleIdentifier}" CFBundleShortVersionString="${CFBundleShortVersionString}" CFBundleVersion="${CFBundleVersion}"/>
+    <bundle-version>
+        <bundle id="${CFBundleIdentifier}"/>
+    </bundle-version>
+    <upgrade-bundle>
+        <bundle id="${CFBundleIdentifier}"/>
+    </upgrade-bundle>
+    <update-bundle/>
+    <atomic-update-bundle/>
+    <strict-identifier>
+        <bundle id="${CFBundleIdentifier}"/>
+    </strict-identifier>
+    <relocate>
+        <bundle id="${CFBundleIdentifier}"/>
+    </relocate>
+</pkg-info>
\ No newline at end of file
diff --git a/python/mozbuild/mozpack/archive.py b/python/mozbuild/mozpack/archive.py
new file mode 100644
index 0000000000..89bf14b179
--- /dev/null
+++ b/python/mozbuild/mozpack/archive.py
@@ -0,0 +1,153 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import bz2
+import gzip
+import stat
+import tarfile
+
+from .files import BaseFile, File
+
+# 2016-01-01T00:00:00+0000
+DEFAULT_MTIME = 1451606400
+
+
+# Python 3.9 contains this change:
+#  https://github.com/python/cpython/commit/674935b8caf33e47c78f1b8e197b1b77a04992d2
+# which changes the output of tar creation compared to earlier versions.
+# As this code is used to generate tar files that are meant to be deterministic
+# across versions of python (specifically, it's used as part of computing the hash
+# of docker images, which needs to be identical between CI (which uses python 3.8),
+# and developer environments (using arbitrary versions of python, at this point,
+# most probably more recent than 3.9)).
+# What we do is subblass TarInfo so that if used on python >= 3.9, it reproduces the
+# behavior from python < 3.9.
+# Here's how it goes:
+# - the behavior in python >= 3.9 is the same as python < 3.9 when the type encoded
+# in the tarinfo is CHRTYPE or BLKTYPE.
+# - the value of the type is only compared in the context of choosing which behavior
+# to take
+# - we replace the type with the same value (so that using the value has no changes)
+# but that pretends to be the same as CHRTYPE so that the condition that enables the
+# old behavior is taken.
+class HackedType(bytes):
+    def __eq__(self, other):
+        if other == tarfile.CHRTYPE:
+            return True
+        return self == other
+
+
+class TarInfo(tarfile.TarInfo):
+    @staticmethod
+    def _create_header(info, format, encoding, errors):
+        info["type"] = HackedType(info["type"])
+        return tarfile.TarInfo._create_header(info, format, encoding, errors)
+
+
+def create_tar_from_files(fp, files):
+    """Create a tar file deterministically.
+
+    Receives a dict mapping names of files in the archive to local filesystem
+    paths or ``mozpack.files.BaseFile`` instances.
+
+    The files will be archived and written to the passed file handle opened
+    for writing.
+
+    Only regular files can be written.
+
+    FUTURE accept a filename argument (or create APIs to write files)
+    """
+    # The format is explicitly set to tarfile.GNU_FORMAT, because this default format
+    # has been changed in Python 3.8.
+    with tarfile.open(
+        name="", mode="w", fileobj=fp, dereference=True, format=tarfile.GNU_FORMAT
+    ) as tf:
+        for archive_path, f in sorted(files.items()):
+            if not isinstance(f, BaseFile):
+                f = File(f)
+
+            ti = TarInfo(archive_path)
+            ti.mode = f.mode or 0o0644
+            ti.type = tarfile.REGTYPE
+
+            if not ti.isreg():
+                raise ValueError("not a regular file: %s" % f)
+
+            # Disallow setuid and setgid bits. This is an arbitrary restriction.
+            # However, since we set uid/gid to root:root, setuid and setgid
+            # would be a glaring security hole if the archive were
+            # uncompressed as root.
+            if ti.mode & (stat.S_ISUID | stat.S_ISGID):
+                raise ValueError("cannot add file with setuid or setgid set: " "%s" % f)
+
+            # Set uid, gid, username, and group as deterministic values.
+            ti.uid = 0
+            ti.gid = 0
+            ti.uname = ""
+            ti.gname = ""
+
+            # Set mtime to a constant value.
+            ti.mtime = DEFAULT_MTIME
+
+            ti.size = f.size()
+            # tarfile wants to pass a size argument to read(). So just
+            # wrap/buffer in a proper file object interface.
+            tf.addfile(ti, f.open())
+
+
+def create_tar_gz_from_files(fp, files, filename=None, compresslevel=9):
+    """Create a tar.gz file deterministically from files.
+
+    This is a glorified wrapper around ``create_tar_from_files`` that
+    adds gzip compression.
+
+    The passed file handle should be opened for writing in binary mode.
+    When the function returns, all data has been written to the handle.
+    """
+    # Offset 3-7 in the gzip header contains an mtime. Pin it to a known
+    # value so output is deterministic.
+    gf = gzip.GzipFile(
+        filename=filename or "",
+        mode="wb",
+        fileobj=fp,
+        compresslevel=compresslevel,
+        mtime=DEFAULT_MTIME,
+    )
+    with gf:
+        create_tar_from_files(gf, files)
+
+
+class _BZ2Proxy(object):
+    """File object that proxies writes to a bz2 compressor."""
+
+    def __init__(self, fp, compresslevel=9):
+        self.fp = fp
+        self.compressor = bz2.BZ2Compressor(compresslevel)
+        self.pos = 0
+
+    def tell(self):
+        return self.pos
+
+    def write(self, data):
+        data = self.compressor.compress(data)
+        self.pos += len(data)
+        self.fp.write(data)
+
+    def close(self):
+        data = self.compressor.flush()
+        self.pos += len(data)
+        self.fp.write(data)
+
+
+def create_tar_bz2_from_files(fp, files, compresslevel=9):
+    """Create a tar.bz2 file deterministically from files.
+
+    This is a glorified wrapper around ``create_tar_from_files`` that
+    adds bzip2 compression.
+
+    This function is similar to ``create_tar_gzip_from_files()``.
+    """
+    proxy = _BZ2Proxy(fp, compresslevel=compresslevel)
+    create_tar_from_files(proxy, files)
+    proxy.close()
diff --git a/python/mozbuild/mozpack/chrome/__init__.py b/python/mozbuild/mozpack/chrome/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/python/mozbuild/mozpack/chrome/__init__.py
diff --git a/python/mozbuild/mozpack/chrome/flags.py b/python/mozbuild/mozpack/chrome/flags.py
new file mode 100644
index 0000000000..6b096c862a
--- /dev/null
+++ b/python/mozbuild/mozpack/chrome/flags.py
@@ -0,0 +1,278 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import re
+from collections import OrderedDict
+
+import six
+from packaging.version import Version
+
+from mozpack.errors import errors
+
+
+class Flag(object):
+    """
+    Class for flags in manifest entries in the form:
+        "flag"   (same as "flag=true")
+        "flag=yes|true|1"
+        "flag=no|false|0"
+    """
+
+    def __init__(self, name):
+        """
+        Initialize a Flag with the given name.
+        """
+        self.name = name
+        self.value = None
+
+    def add_definition(self, definition):
+        """
+        Add a flag value definition. Replaces any previously set value.
+        """
+        if definition == self.name:
+            self.value = True
+            return
+        assert definition.startswith(self.name)
+        if definition[len(self.name)] != "=":
+            return errors.fatal("Malformed flag: %s" % definition)
+        value = definition[len(self.name) + 1 :]
+        if value in ("yes", "true", "1", "no", "false", "0"):
+            self.value = value
+        else:
+            return errors.fatal("Unknown value in: %s" % definition)
+
+    def matches(self, value):
+        """
+        Return whether the flag value matches the given value. The values
+        are canonicalized for comparison.
+        """
+        if value in ("yes", "true", "1", True):
+            return self.value in ("yes", "true", "1", True)
+        if value in ("no", "false", "0", False):
+            return self.value in ("no", "false", "0", False, None)
+        raise RuntimeError("Invalid value: %s" % value)
+
+    def __str__(self):
+        """
+        Serialize the flag value in the same form given to the last
+        add_definition() call.
+        """
+        if self.value is None:
+            return ""
+        if self.value is True:
+            return self.name
+        return "%s=%s" % (self.name, self.value)
+
+    def __eq__(self, other):
+        return str(self) == other
+
+
+class StringFlag(object):
+    """
+    Class for string flags in manifest entries in the form:
+        "flag=string"
+        "flag!=string"
+    """
+
+    def __init__(self, name):
+        """
+        Initialize a StringFlag with the given name.
+        """
+        self.name = name
+        self.values = []
+
+    def add_definition(self, definition):
+        """
+        Add a string flag definition.
+        """
+        assert definition.startswith(self.name)
+        value = definition[len(self.name) :]
+        if value.startswith("="):
+            self.values.append(("==", value[1:]))
+        elif value.startswith("!="):
+            self.values.append(("!=", value[2:]))
+        else:
+            return errors.fatal("Malformed flag: %s" % definition)
+
+    def matches(self, value):
+        """
+        Return whether one of the string flag definitions matches the given
+        value.
+        For example,
+
+            flag = StringFlag('foo')
+            flag.add_definition('foo!=bar')
+            flag.matches('bar') returns False
+            flag.matches('qux') returns True
+            flag = StringFlag('foo')
+            flag.add_definition('foo=bar')
+            flag.add_definition('foo=baz')
+            flag.matches('bar') returns True
+            flag.matches('baz') returns True
+            flag.matches('qux') returns False
+        """
+        if not self.values:
+            return True
+        for comparison, val in self.values:
+            if eval("value %s val" % comparison):
+                return True
+        return False
+
+    def __str__(self):
+        """
+        Serialize the flag definitions in the same form given to each
+        add_definition() call.
+        """
+        res = []
+        for comparison, val in self.values:
+            if comparison == "==":
+                res.append("%s=%s" % (self.name, val))
+            else:
+                res.append("%s!=%s" % (self.name, val))
+        return " ".join(res)
+
+    def __eq__(self, other):
+        return str(self) == other
+
+
+class VersionFlag(object):
+    """
+    Class for version flags in manifest entries in the form:
+        "flag=version"
+        "flag<=version"
+        "flag<version"
+        "flag>=version"
+        "flag>version"
+    """
+
+    def __init__(self, name):
+        """
+        Initialize a VersionFlag with the given name.
+        """
+        self.name = name
+        self.values = []
+
+    def add_definition(self, definition):
+        """
+        Add a version flag definition.
+        """
+        assert definition.startswith(self.name)
+        value = definition[len(self.name) :]
+        if value.startswith("="):
+            self.values.append(("==", Version(value[1:])))
+        elif len(value) > 1 and value[0] in ["<", ">"]:
+            if value[1] == "=":
+                if len(value) < 3:
+                    return errors.fatal("Malformed flag: %s" % definition)
+                self.values.append((value[0:2], Version(value[2:])))
+            else:
+                self.values.append((value[0], Version(value[1:])))
+        else:
+            return errors.fatal("Malformed flag: %s" % definition)
+
+    def matches(self, value):
+        """
+        Return whether one of the version flag definitions matches the given
+        value.
+        For example,
+
+            flag = VersionFlag('foo')
+            flag.add_definition('foo>=1.0')
+            flag.matches('1.0') returns True
+            flag.matches('1.1') returns True
+            flag.matches('0.9') returns False
+            flag = VersionFlag('foo')
+            flag.add_definition('foo>=1.0')
+            flag.add_definition('foo<0.5')
+            flag.matches('0.4') returns True
+            flag.matches('1.0') returns True
+            flag.matches('0.6') returns False
+        """
+        value = Version(value)
+        if not self.values:
+            return True
+        for comparison, val in self.values:
+            if eval("value %s val" % comparison):
+                return True
+        return False
+
+    def __str__(self):
+        """
+        Serialize the flag definitions in the same form given to each
+        add_definition() call.
+        """
+        res = []
+        for comparison, val in self.values:
+            if comparison == "==":
+                res.append("%s=%s" % (self.name, val))
+            else:
+                res.append("%s%s%s" % (self.name, comparison, val))
+        return " ".join(res)
+
+    def __eq__(self, other):
+        return str(self) == other
+
+
+class Flags(OrderedDict):
+    """
+    Class to handle a set of flags definitions given on a single manifest
+    entry.
+
+    """
+
+    FLAGS = {
+        "application": StringFlag,
+        "appversion": VersionFlag,
+        "platformversion": VersionFlag,
+        "contentaccessible": Flag,
+        "os": StringFlag,
+        "osversion": VersionFlag,
+        "abi": StringFlag,
+        "platform": Flag,
+        "xpcnativewrappers": Flag,
+        "tablet": Flag,
+        "process": StringFlag,
+        "backgroundtask": StringFlag,
+    }
+    RE = re.compile(r"([!<>=]+)")
+
+    def __init__(self, *flags):
+        """
+        Initialize a set of flags given in string form.
+           flags = Flags('contentaccessible=yes', 'appversion>=3.5')
+        """
+        OrderedDict.__init__(self)
+        for f in flags:
+            name = self.RE.split(f)
+            name = name[0]
+            if name not in self.FLAGS:
+                errors.fatal("Unknown flag: %s" % name)
+                continue
+            if name not in self:
+                self[name] = self.FLAGS[name](name)
+            self[name].add_definition(f)
+
+    def __str__(self):
+        """
+        Serialize the set of flags.
+        """
+        return " ".join(str(self[k]) for k in self)
+
+    def match(self, **filter):
+        """
+        Return whether the set of flags match the set of given filters.
+            flags = Flags('contentaccessible=yes', 'appversion>=3.5',
+                          'application=foo')
+
+            flags.match(application='foo') returns True
+            flags.match(application='foo', appversion='3.5') returns True
+            flags.match(application='foo', appversion='3.0') returns False
+
+        """
+        for name, value in six.iteritems(filter):
+            if name not in self:
+                continue
+            if not self[name].matches(value):
+                return False
+        return True
diff --git a/python/mozbuild/mozpack/chrome/manifest.py b/python/mozbuild/mozpack/chrome/manifest.py
new file mode 100644
index 0000000000..14c11d4c1d
--- /dev/null
+++ b/python/mozbuild/mozpack/chrome/manifest.py
@@ -0,0 +1,400 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import re
+
+import six
+from six.moves.urllib.parse import urlparse
+
+import mozpack.path as mozpath
+from mozpack.chrome.flags import Flags
+from mozpack.errors import errors
+
+
+class ManifestEntry(object):
+    """
+    Base class for all manifest entry types.
+    Subclasses may define the following class or member variables:
+
+        - localized: indicates whether the manifest entry is used for localized
+          data.
+        - type: the manifest entry type (e.g. 'content' in
+          'content global content/global/')
+        - allowed_flags: a set of flags allowed to be defined for the given
+          manifest entry type.
+
+    A manifest entry is attached to a base path, defining where the manifest
+    entry is bound to, and that is used to find relative paths defined in
+    entries.
+    """
+
+    localized = False
+    type = None
+    allowed_flags = [
+        "application",
+        "platformversion",
+        "os",
+        "osversion",
+        "abi",
+        "xpcnativewrappers",
+        "tablet",
+        "process",
+        "contentaccessible",
+        "backgroundtask",
+    ]
+
+    def __init__(self, base, *flags):
+        """
+        Initialize a manifest entry with the given base path and flags.
+        """
+        self.base = base
+        self.flags = Flags(*flags)
+        if not all(f in self.allowed_flags for f in self.flags):
+            errors.fatal(
+                "%s unsupported for %s manifest entries"
+                % (
+                    ",".join(f for f in self.flags if f not in self.allowed_flags),
+                    self.type,
+                )
+            )
+
+    def serialize(self, *args):
+        """
+        Serialize the manifest entry.
+        """
+        entry = [self.type] + list(args)
+        flags = str(self.flags)
+        if flags:
+            entry.append(flags)
+        return " ".join(entry)
+
+    def __eq__(self, other):
+        return self.base == other.base and str(self) == str(other)
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __repr__(self):
+        return "<%s@%s>" % (str(self), self.base)
+
+    def move(self, base):
+        """
+        Return a new manifest entry with a different base path.
+        """
+        return parse_manifest_line(base, str(self))
+
+    def rebase(self, base):
+        """
+        Return a new manifest entry with all relative paths defined in the
+        entry relative to a new base directory.
+        The base class doesn't define relative paths, so it is equivalent to
+        move().
+        """
+        return self.move(base)
+
+
+class ManifestEntryWithRelPath(ManifestEntry):
+    """
+    Abstract manifest entry type with a relative path definition.
+    """
+
+    def __init__(self, base, relpath, *flags):
+        ManifestEntry.__init__(self, base, *flags)
+        self.relpath = relpath
+
+    def __str__(self):
+        return self.serialize(self.relpath)
+
+    def rebase(self, base):
+        """
+        Return a new manifest entry with all relative paths defined in the
+        entry relative to a new base directory.
+        """
+        clone = ManifestEntry.rebase(self, base)
+        clone.relpath = mozpath.rebase(self.base, base, self.relpath)
+        return clone
+
+    @property
+    def path(self):
+        return mozpath.normpath(mozpath.join(self.base, self.relpath))
+
+
+class Manifest(ManifestEntryWithRelPath):
+    """
+    Class for 'manifest' entries.
+        manifest some/path/to/another.manifest
+    """
+
+    type = "manifest"
+
+
+class ManifestChrome(ManifestEntryWithRelPath):
+    """
+    Abstract class for chrome entries.
+    """
+
+    def __init__(self, base, name, relpath, *flags):
+        ManifestEntryWithRelPath.__init__(self, base, relpath, *flags)
+        self.name = name
+
+    @property
+    def location(self):
+        return mozpath.join(self.base, self.relpath)
+
+
+class ManifestContent(ManifestChrome):
+    """
+    Class for 'content' entries.
+        content global content/global/
+    """
+
+    type = "content"
+    allowed_flags = ManifestChrome.allowed_flags + [
+        "contentaccessible",
+        "platform",
+    ]
+
+    def __str__(self):
+        return self.serialize(self.name, self.relpath)
+
+
+class ManifestMultiContent(ManifestChrome):
+    """
+    Abstract class for chrome entries with multiple definitions.
+    Used for locale and skin entries.
+    """
+
+    type = None
+
+    def __init__(self, base, name, id, relpath, *flags):
+        ManifestChrome.__init__(self, base, name, relpath, *flags)
+        self.id = id
+
+    def __str__(self):
+        return self.serialize(self.name, self.id, self.relpath)
+
+
+class ManifestLocale(ManifestMultiContent):
+    """
+    Class for 'locale' entries.
+        locale global en-US content/en-US/
+        locale global fr content/fr/
+    """
+
+    localized = True
+    type = "locale"
+
+
+class ManifestSkin(ManifestMultiContent):
+    """
+    Class for 'skin' entries.
+        skin global classic/1.0 content/skin/classic/
+    """
+
+    type = "skin"
+
+
+class ManifestOverload(ManifestEntry):
+    """
+    Abstract class for chrome entries defining some kind of overloading.
+    Used for overlay, override or style entries.
+    """
+
+    type = None
+
+    def __init__(self, base, overloaded, overload, *flags):
+        ManifestEntry.__init__(self, base, *flags)
+        self.overloaded = overloaded
+        self.overload = overload
+
+    def __str__(self):
+        return self.serialize(self.overloaded, self.overload)
+
+
+class ManifestOverlay(ManifestOverload):
+    """
+    Class for 'overlay' entries.
+        overlay chrome://global/content/viewSource.xul \
+            chrome://browser/content/viewSourceOverlay.xul
+    """
+
+    type = "overlay"
+
+
+class ManifestStyle(ManifestOverload):
+    """
+    Class for 'style' entries.
+        style chrome://global/content/viewSource.xul \
+            chrome://browser/skin/
+    """
+
+    type = "style"
+
+
+class ManifestOverride(ManifestOverload):
+    """
+    Class for 'override' entries.
+        override chrome://global/locale/netError.dtd \
+            chrome://browser/locale/netError.dtd
+    """
+
+    type = "override"
+
+
+class ManifestResource(ManifestEntry):
+    """
+    Class for 'resource' entries.
+        resource gre-resources toolkit/res/
+        resource services-sync resource://gre/modules/services-sync/
+
+    The target may be a relative path or a resource or chrome url.
+    """
+
+    type = "resource"
+
+    def __init__(self, base, name, target, *flags):
+        ManifestEntry.__init__(self, base, *flags)
+        self.name = name
+        self.target = target
+
+    def __str__(self):
+        return self.serialize(self.name, self.target)
+
+    def rebase(self, base):
+        u = urlparse(self.target)
+        if u.scheme and u.scheme != "jar":
+            return ManifestEntry.rebase(self, base)
+        clone = ManifestEntry.rebase(self, base)
+        clone.target = mozpath.rebase(self.base, base, self.target)
+        return clone
+
+
+class ManifestBinaryComponent(ManifestEntryWithRelPath):
+    """
+    Class for 'binary-component' entries.
+        binary-component some/path/to/a/component.dll
+    """
+
+    type = "binary-component"
+
+
+class ManifestComponent(ManifestEntryWithRelPath):
+    """
+    Class for 'component' entries.
+        component {b2bba4df-057d-41ea-b6b1-94a10a8ede68} foo.js
+    """
+
+    type = "component"
+
+    def __init__(self, base, cid, file, *flags):
+        ManifestEntryWithRelPath.__init__(self, base, file, *flags)
+        self.cid = cid
+
+    def __str__(self):
+        return self.serialize(self.cid, self.relpath)
+
+
+class ManifestInterfaces(ManifestEntryWithRelPath):
+    """
+    Class for 'interfaces' entries.
+        interfaces foo.xpt
+    """
+
+    type = "interfaces"
+
+
+class ManifestCategory(ManifestEntry):
+    """
+    Class for 'category' entries.
+        category command-line-handler m-browser @mozilla.org/browser/clh;
+    """
+
+    type = "category"
+
+    def __init__(self, base, category, name, value, *flags):
+        ManifestEntry.__init__(self, base, *flags)
+        self.category = category
+        self.name = name
+        self.value = value
+
+    def __str__(self):
+        return self.serialize(self.category, self.name, self.value)
+
+
+class ManifestContract(ManifestEntry):
+    """
+    Class for 'contract' entries.
+        contract @mozilla.org/foo;1 {b2bba4df-057d-41ea-b6b1-94a10a8ede68}
+    """
+
+    type = "contract"
+
+    def __init__(self, base, contractID, cid, *flags):
+        ManifestEntry.__init__(self, base, *flags)
+        self.contractID = contractID
+        self.cid = cid
+
+    def __str__(self):
+        return self.serialize(self.contractID, self.cid)
+
+
+# All manifest classes by their type name.
+MANIFESTS_TYPES = dict(
+    [
+        (c.type, c)
+        for c in globals().values()
+        if type(c) == type
+        and issubclass(c, ManifestEntry)
+        and hasattr(c, "type")
+        and c.type
+    ]
+)
+
+MANIFEST_RE = re.compile(r"^#.*$")
+
+
+def parse_manifest_line(base, line):
+    """
+    Parse a line from a manifest file with the given base directory and
+    return the corresponding ManifestEntry instance.
+    """
+    # Remove comments
+    cmd = MANIFEST_RE.sub("", line).strip().split()
+    if not cmd:
+        return None
+    if not cmd[0] in MANIFESTS_TYPES:
+        return errors.fatal("Unknown manifest directive: %s" % cmd[0])
+    return MANIFESTS_TYPES[cmd[0]](base, *cmd[1:])
+
+
+def parse_manifest(root, path, fileobj=None):
+    """
+    Parse a manifest file.
+    """
+    base = mozpath.dirname(path)
+    if root:
+        path = os.path.normpath(os.path.abspath(os.path.join(root, path)))
+    if not fileobj:
+        fileobj = open(path)
+    linenum = 0
+    for line in fileobj:
+        line = six.ensure_text(line)
+        linenum += 1
+        with errors.context(path, linenum):
+            e = parse_manifest_line(base, line)
+            if e:
+                yield e
+
+
+def is_manifest(path):
+    """
+    Return whether the given path is that of a manifest file.
+    """
+    return (
+        path.endswith(".manifest")
+        and not path.endswith(".CRT.manifest")
+        and not path.endswith(".exe.manifest")
+        and os.path.basename(path) != "cose.manifest"
+    )
diff --git a/python/mozbuild/mozpack/copier.py b/python/mozbuild/mozpack/copier.py
new file mode 100644
index 0000000000..c042e5432f
--- /dev/null
+++ b/python/mozbuild/mozpack/copier.py
@@ -0,0 +1,605 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import concurrent.futures as futures
+import errno
+import os
+import stat
+import sys
+from collections import Counter, OrderedDict, defaultdict
+
+import six
+
+import mozpack.path as mozpath
+from mozpack.errors import errors
+from mozpack.files import BaseFile, Dest
+
+
+class FileRegistry(object):
+    """
+    Generic container to keep track of a set of BaseFile instances. It
+    preserves the order under which the files are added, but doesn't keep
+    track of empty directories (directories are not stored at all).
+    The paths associated with the BaseFile instances are relative to an
+    unspecified (virtual) root directory.
+
+        registry = FileRegistry()
+        registry.add('foo/bar', file_instance)
+    """
+
+    def __init__(self):
+        self._files = OrderedDict()
+        self._required_directories = Counter()
+        self._partial_paths_cache = {}
+
+    def _partial_paths(self, path):
+        """
+        Turn "foo/bar/baz/zot" into ["foo/bar/baz", "foo/bar", "foo"].
+        """
+        dir_name = path.rpartition("/")[0]
+        if not dir_name:
+            return []
+
+        partial_paths = self._partial_paths_cache.get(dir_name)
+        if partial_paths:
+            return partial_paths
+
+        partial_paths = [dir_name] + self._partial_paths(dir_name)
+
+        self._partial_paths_cache[dir_name] = partial_paths
+        return partial_paths
+
+    def add(self, path, content):
+        """
+        Add a BaseFile instance to the container, under the given path.
+        """
+        assert isinstance(content, BaseFile)
+        if path in self._files:
+            return errors.error("%s already added" % path)
+        if self._required_directories[path] > 0:
+            return errors.error("Can't add %s: it is a required directory" % path)
+        # Check whether any parent of the given path is already stored
+        partial_paths = self._partial_paths(path)
+        for partial_path in partial_paths:
+            if partial_path in self._files:
+                return errors.error("Can't add %s: %s is a file" % (path, partial_path))
+        self._files[path] = content
+        self._required_directories.update(partial_paths)
+
+    def match(self, pattern):
+        """
+        Return the list of paths, stored in the container, matching the
+        given pattern. See the mozpack.path.match documentation for a
+        description of the handled patterns.
+        """
+        if "*" in pattern:
+            return [p for p in self.paths() if mozpath.match(p, pattern)]
+        if pattern == "":
+            return self.paths()
+        if pattern in self._files:
+            return [pattern]
+        return [p for p in self.paths() if mozpath.basedir(p, [pattern]) == pattern]
+
+    def remove(self, pattern):
+        """
+        Remove paths matching the given pattern from the container. See the
+        mozpack.path.match documentation for a description of the handled
+        patterns.
+        """
+        items = self.match(pattern)
+        if not items:
+            return errors.error(
+                "Can't remove %s: %s"
+                % (pattern, "not matching anything previously added")
+            )
+        for i in items:
+            del self._files[i]
+            self._required_directories.subtract(self._partial_paths(i))
+
+    def paths(self):
+        """
+        Return all paths stored in the container, in the order they were added.
+        """
+        return list(self._files)
+
+    def __len__(self):
+        """
+        Return number of paths stored in the container.
+        """
+        return len(self._files)
+
+    def __contains__(self, pattern):
+        raise RuntimeError(
+            "'in' operator forbidden for %s. Use contains()." % self.__class__.__name__
+        )
+
+    def contains(self, pattern):
+        """
+        Return whether the container contains paths matching the given
+        pattern. See the mozpack.path.match documentation for a description of
+        the handled patterns.
+        """
+        return len(self.match(pattern)) > 0
+
+    def __getitem__(self, path):
+        """
+        Return the BaseFile instance stored in the container for the given
+        path.
+        """
+        return self._files[path]
+
+    def __iter__(self):
+        """
+        Iterate over all (path, BaseFile instance) pairs from the container.
+            for path, file in registry:
+                (...)
+        """
+        return six.iteritems(self._files)
+
+    def required_directories(self):
+        """
+        Return the set of directories required by the paths in the container,
+        in no particular order.  The returned directories are relative to an
+        unspecified (virtual) root directory (and do not include said root
+        directory).
+        """
+        return set(k for k, v in self._required_directories.items() if v > 0)
+
+    def output_to_inputs_tree(self):
+        """
+        Return a dictionary mapping each output path to the set of its
+        required input paths.
+
+        All paths are normalized.
+        """
+        tree = {}
+        for output, file in self:
+            output = mozpath.normpath(output)
+            tree[output] = set(mozpath.normpath(f) for f in file.inputs())
+        return tree
+
+    def input_to_outputs_tree(self):
+        """
+        Return a dictionary mapping each input path to the set of
+        impacted output paths.
+
+        All paths are normalized.
+        """
+        tree = defaultdict(set)
+        for output, file in self:
+            output = mozpath.normpath(output)
+            for input in file.inputs():
+                input = mozpath.normpath(input)
+                tree[input].add(output)
+        return dict(tree)
+
+
+class FileRegistrySubtree(object):
+    """A proxy class to give access to a subtree of an existing FileRegistry.
+
+    Note this doesn't implement the whole FileRegistry interface."""
+
+    def __new__(cls, base, registry):
+        if not base:
+            return registry
+        return object.__new__(cls)
+
+    def __init__(self, base, registry):
+        self._base = base
+        self._registry = registry
+
+    def _get_path(self, path):
+        # mozpath.join will return a trailing slash if path is empty, and we
+        # don't want that.
+        return mozpath.join(self._base, path) if path else self._base
+
+    def add(self, path, content):
+        return self._registry.add(self._get_path(path), content)
+
+    def match(self, pattern):
+        return [
+            mozpath.relpath(p, self._base)
+            for p in self._registry.match(self._get_path(pattern))
+        ]
+
+    def remove(self, pattern):
+        return self._registry.remove(self._get_path(pattern))
+
+    def paths(self):
+        return [p for p, f in self]
+
+    def __len__(self):
+        return len(self.paths())
+
+    def contains(self, pattern):
+        return self._registry.contains(self._get_path(pattern))
+
+    def __getitem__(self, path):
+        return self._registry[self._get_path(path)]
+
+    def __iter__(self):
+        for p, f in self._registry:
+            if mozpath.basedir(p, [self._base]):
+                yield mozpath.relpath(p, self._base), f
+
+
+class FileCopyResult(object):
+    """Represents results of a FileCopier.copy operation."""
+
+    def __init__(self):
+        self.updated_files = set()
+        self.existing_files = set()
+        self.removed_files = set()
+        self.removed_directories = set()
+
+    @property
+    def updated_files_count(self):
+        return len(self.updated_files)
+
+    @property
+    def existing_files_count(self):
+        return len(self.existing_files)
+
+    @property
+    def removed_files_count(self):
+        return len(self.removed_files)
+
+    @property
+    def removed_directories_count(self):
+        return len(self.removed_directories)
+
+
+class FileCopier(FileRegistry):
+    """
+    FileRegistry with the ability to copy the registered files to a separate
+    directory.
+    """
+
+    def copy(
+        self,
+        destination,
+        skip_if_older=True,
+        remove_unaccounted=True,
+        remove_all_directory_symlinks=True,
+        remove_empty_directories=True,
+    ):
+        """
+        Copy all registered files to the given destination path. The given
+        destination can be an existing directory, or not exist at all. It
+        can't be e.g. a file.
+        The copy process acts a bit like rsync: files are not copied when they
+        don't need to (see mozpack.files for details on file.copy).
+
+        By default, files in the destination directory that aren't
+        registered are removed and empty directories are deleted. In
+        addition, all directory symlinks in the destination directory
+        are deleted: this is a conservative approach to ensure that we
+        never accidently write files into a directory that is not the
+        destination directory. In the worst case, we might have a
+        directory symlink in the object directory to the source
+        directory.
+
+        To disable removing of unregistered files, pass
+        remove_unaccounted=False. To disable removing empty
+        directories, pass remove_empty_directories=False. In rare
+        cases, you might want to maintain directory symlinks in the
+        destination directory (at least those that are not required to
+        be regular directories): pass
+        remove_all_directory_symlinks=False. Exercise caution with
+        this flag: you almost certainly do not want to preserve
+        directory symlinks.
+
+        Returns a FileCopyResult that details what changed.
+        """
+        assert isinstance(destination, six.string_types)
+        assert not os.path.exists(destination) or os.path.isdir(destination)
+
+        result = FileCopyResult()
+        have_symlinks = hasattr(os, "symlink")
+        destination = os.path.normpath(destination)
+
+        # We create the destination directory specially. We can't do this as
+        # part of the loop doing mkdir() below because that loop munges
+        # symlinks and permissions and parent directories of the destination
+        # directory may have their own weird schema. The contract is we only
+        # manage children of destination, not its parents.
+        try:
+            os.makedirs(destination)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+        # Because we could be handling thousands of files, code in this
+        # function is optimized to minimize system calls. We prefer CPU time
+        # in Python over possibly I/O bound filesystem calls to stat() and
+        # friends.
+
+        required_dirs = set([destination])
+        required_dirs |= set(
+            os.path.normpath(os.path.join(destination, d))
+            for d in self.required_directories()
+        )
+
+        # Ensure destination directories are in place and proper.
+        #
+        # The "proper" bit is important. We need to ensure that directories
+        # have appropriate permissions or we will be unable to discover
+        # and write files. Furthermore, we need to verify directories aren't
+        # symlinks.
+        #
+        # Symlinked directories (a symlink whose target is a directory) are
+        # incompatible with us because our manifest talks in terms of files,
+        # not directories. If we leave symlinked directories unchecked, we
+        # would blindly follow symlinks and this might confuse file
+        # installation. For example, if an existing directory is a symlink
+        # to directory X and we attempt to install a symlink in this directory
+        # to a file in directory X, we may create a recursive symlink!
+        for d in sorted(required_dirs, key=len):
+            try:
+                os.mkdir(d)
+            except OSError as error:
+                if error.errno != errno.EEXIST:
+                    raise
+
+            # We allow the destination to be a symlink because the caller
+            # is responsible for managing the destination and we assume
+            # they know what they are doing.
+            if have_symlinks and d != destination:
+                st = os.lstat(d)
+                if stat.S_ISLNK(st.st_mode):
+                    # While we have remove_unaccounted, it doesn't apply
+                    # to directory symlinks because if it did, our behavior
+                    # could be very wrong.
+                    os.remove(d)
+                    os.mkdir(d)
+
+            if not os.access(d, os.W_OK):
+                umask = os.umask(0o077)
+                os.umask(umask)
+                os.chmod(d, 0o777 & ~umask)
+
+        if isinstance(remove_unaccounted, FileRegistry):
+            existing_files = set(
+                os.path.normpath(os.path.join(destination, p))
+                for p in remove_unaccounted.paths()
+            )
+            existing_dirs = set(
+                os.path.normpath(os.path.join(destination, p))
+                for p in remove_unaccounted.required_directories()
+            )
+            existing_dirs |= {os.path.normpath(destination)}
+        else:
+            # While we have remove_unaccounted, it doesn't apply to empty
+            # directories because it wouldn't make sense: an empty directory
+            # is empty, so removing it should have no effect.
+            existing_dirs = set()
+            existing_files = set()
+            for root, dirs, files in os.walk(destination):
+                # We need to perform the same symlink detection as above.
+                # os.walk() doesn't follow symlinks into directories by
+                # default, so we need to check dirs (we can't wait for root).
+                if have_symlinks:
+                    filtered = []
+                    for d in dirs:
+                        full = os.path.join(root, d)
+                        st = os.lstat(full)
+                        if stat.S_ISLNK(st.st_mode):
+                            # This directory symlink is not a required
+                            # directory: any such symlink would have been
+                            # removed and a directory created above.
+                            if remove_all_directory_symlinks:
+                                os.remove(full)
+                                result.removed_files.add(os.path.normpath(full))
+                            else:
+                                existing_files.add(os.path.normpath(full))
+                        else:
+                            filtered.append(d)
+
+                    dirs[:] = filtered
+
+                existing_dirs.add(os.path.normpath(root))
+
+                for d in dirs:
+                    existing_dirs.add(os.path.normpath(os.path.join(root, d)))
+
+                for f in files:
+                    existing_files.add(os.path.normpath(os.path.join(root, f)))
+
+        # Now we reconcile the state of the world against what we want.
+        dest_files = set()
+
+        # Install files.
+        #
+        # Creating/appending new files on Windows/NTFS is slow. So we use a
+        # thread pool to speed it up significantly. The performance of this
+        # loop is so critical to common build operations on Linux that the
+        # overhead of the thread pool is worth avoiding, so we have 2 code
+        # paths. We also employ a low water mark to prevent thread pool
+        # creation if number of files is too small to benefit.
+        copy_results = []
+        if sys.platform == "win32" and len(self) > 100:
+            with futures.ThreadPoolExecutor(4) as e:
+                fs = []
+                for p, f in self:
+                    destfile = os.path.normpath(os.path.join(destination, p))
+                    fs.append((destfile, e.submit(f.copy, destfile, skip_if_older)))
+
+            copy_results = [(path, f.result) for path, f in fs]
+        else:
+            for p, f in self:
+                destfile = os.path.normpath(os.path.join(destination, p))
+                copy_results.append((destfile, f.copy(destfile, skip_if_older)))
+
+        for destfile, copy_result in copy_results:
+            dest_files.add(destfile)
+            if copy_result:
+                result.updated_files.add(destfile)
+            else:
+                result.existing_files.add(destfile)
+
+        # Remove files no longer accounted for.
+        if remove_unaccounted:
+            for f in existing_files - dest_files:
+                # Windows requires write access to remove files.
+                if os.name == "nt" and not os.access(f, os.W_OK):
+                    # It doesn't matter what we set permissions to since we
+                    # will remove this file shortly.
+                    os.chmod(f, 0o600)
+
+                os.remove(f)
+                result.removed_files.add(f)
+
+        if not remove_empty_directories:
+            return result
+
+        # Figure out which directories can be removed. This is complicated
+        # by the fact we optionally remove existing files. This would be easy
+        # if we walked the directory tree after installing files. But, we're
+        # trying to minimize system calls.
+
+        # Start with the ideal set.
+        remove_dirs = existing_dirs - required_dirs
+
+        # Then don't remove directories if we didn't remove unaccounted files
+        # and one of those files exists.
+        if not remove_unaccounted:
+            parents = set()
+            pathsep = os.path.sep
+            for f in existing_files:
+                path = f
+                while True:
+                    # All the paths are normalized and relative by this point,
+                    # so os.path.dirname would only do extra work.
+                    dirname = path.rpartition(pathsep)[0]
+                    if dirname in parents:
+                        break
+                    parents.add(dirname)
+                    path = dirname
+            remove_dirs -= parents
+
+        # Remove empty directories that aren't required.
+        for d in sorted(remove_dirs, key=len, reverse=True):
+            try:
+                try:
+                    os.rmdir(d)
+                except OSError as e:
+                    if e.errno in (errno.EPERM, errno.EACCES):
+                        # Permissions may not allow deletion. So ensure write
+                        # access is in place before attempting to rmdir again.
+                        os.chmod(d, 0o700)
+                        os.rmdir(d)
+                    else:
+                        raise
+            except OSError as e:
+                # If remove_unaccounted is a # FileRegistry, then we have a
+                # list of directories that may not be empty, so ignore rmdir
+                # ENOTEMPTY errors for them.
+                if (
+                    isinstance(remove_unaccounted, FileRegistry)
+                    and e.errno == errno.ENOTEMPTY
+                ):
+                    continue
+                raise
+            result.removed_directories.add(d)
+
+        return result
+
+
+class Jarrer(FileRegistry, BaseFile):
+    """
+    FileRegistry with the ability to copy and pack the registered files as a
+    jar file. Also acts as a BaseFile instance, to be copied with a FileCopier.
+    """
+
+    def __init__(self, compress=True):
+        """
+        Create a Jarrer instance. See mozpack.mozjar.JarWriter documentation
+        for details on the compress argument.
+        """
+        self.compress = compress
+        self._preload = []
+        self._compress_options = {}  # Map path to compress boolean option.
+        FileRegistry.__init__(self)
+
+    def add(self, path, content, compress=None):
+        FileRegistry.add(self, path, content)
+        if compress is not None:
+            self._compress_options[path] = compress
+
+    def copy(self, dest, skip_if_older=True):
+        """
+        Pack all registered files in the given destination jar. The given
+        destination jar may be a path to jar file, or a Dest instance for
+        a jar file.
+        If the destination jar file exists, its (compressed) contents are used
+        instead of the registered BaseFile instances when appropriate.
+        """
+
+        class DeflaterDest(Dest):
+            """
+            Dest-like class, reading from a file-like object initially, but
+            switching to a Deflater object if written to.
+
+                dest = DeflaterDest(original_file)
+                dest.read()      # Reads original_file
+                dest.write(data) # Creates a Deflater and write data there
+                dest.read()      # Re-opens the Deflater and reads from it
+            """
+
+            def __init__(self, orig=None, compress=True):
+                self.mode = None
+                self.deflater = orig
+                self.compress = compress
+
+            def read(self, length=-1):
+                if self.mode != "r":
+                    assert self.mode is None
+                    self.mode = "r"
+                return self.deflater.read(length)
+
+            def write(self, data):
+                if self.mode != "w":
+                    from mozpack.mozjar import Deflater
+
+                    self.deflater = Deflater(self.compress)
+                    self.mode = "w"
+                self.deflater.write(data)
+
+            def exists(self):
+                return self.deflater is not None
+
+        if isinstance(dest, six.string_types):
+            dest = Dest(dest)
+        assert isinstance(dest, Dest)
+
+        from mozpack.mozjar import JarReader, JarWriter
+
+        try:
+            old_jar = JarReader(fileobj=dest)
+        except Exception:
+            old_jar = []
+
+        old_contents = dict([(f.filename, f) for f in old_jar])
+
+        with JarWriter(fileobj=dest, compress=self.compress) as jar:
+            for path, file in self:
+                compress = self._compress_options.get(path, self.compress)
+                if path in old_contents:
+                    deflater = DeflaterDest(old_contents[path], compress)
+                else:
+                    deflater = DeflaterDest(compress=compress)
+                file.copy(deflater, skip_if_older)
+                jar.add(path, deflater.deflater, mode=file.mode, compress=compress)
+            if self._preload:
+                jar.preload(self._preload)
+
+    def open(self):
+        raise RuntimeError("unsupported")
+
+    def preload(self, paths):
+        """
+        Add the given set of paths to the list of preloaded files. See
+        mozpack.mozjar.JarWriter documentation for details on jar preloading.
+        """
+        self._preload.extend(paths)
diff --git a/python/mozbuild/mozpack/dmg.py b/python/mozbuild/mozpack/dmg.py
new file mode 100644
index 0000000000..4e094648fe
--- /dev/null
+++ b/python/mozbuild/mozpack/dmg.py
@@ -0,0 +1,258 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import platform
+import shutil
+import subprocess
+from pathlib import Path
+from typing import List
+
+import mozfile
+
+from mozbuild.util import ensureParentDir
+
+is_linux = platform.system() == "Linux"
+is_osx = platform.system() == "Darwin"
+
+
+def chmod(dir):
+    "Set permissions of DMG contents correctly"
+    subprocess.check_call(["chmod", "-R", "a+rX,a-st,u+w,go-w", dir])
+
+
+def rsync(source: Path, dest: Path):
+    "rsync the contents of directory source into directory dest"
+    # Ensure a trailing slash on directories so rsync copies the *contents* of source.
+    raw_source = str(source)
+    if source.is_dir():
+        raw_source = str(source) + "/"
+    subprocess.check_call(["rsync", "-a", "--copy-unsafe-links", raw_source, dest])
+
+
+def set_folder_icon(dir: Path, tmpdir: Path, hfs_tool: Path = None):
+    "Set HFS attributes of dir to use a custom icon"
+    if is_linux:
+        hfs = tmpdir / "staged.hfs"
+        subprocess.check_call([hfs_tool, hfs, "attr", "/", "C"])
+    elif is_osx:
+        subprocess.check_call(["SetFile", "-a", "C", dir])
+
+
+def generate_hfs_file(
+    stagedir: Path, tmpdir: Path, volume_name: str, mkfshfs_tool: Path
+):
+    """
+    When cross compiling, we zero fill an hfs file, that we will turn into
+    a DMG. To do so we test the size of the staged dir, and add some slight
+    padding to that.
+    """
+    hfs = tmpdir / "staged.hfs"
+    output = subprocess.check_output(["du", "-s", stagedir])
+    size = int(output.split()[0]) / 1000  # Get in MB
+    size = int(size * 1.02)  # Bump the used size slightly larger.
+    # Setup a proper file sized out with zero's
+    subprocess.check_call(
+        [
+            "dd",
+            "if=/dev/zero",
+            "of={}".format(hfs),
+            "bs=1M",
+            "count={}".format(size),
+        ]
+    )
+    subprocess.check_call([mkfshfs_tool, "-v", volume_name, hfs])
+
+
+def create_app_symlink(stagedir: Path, tmpdir: Path, hfs_tool: Path = None):
+    """
+    Make a symlink to /Applications. The symlink name is a space
+    so we don't have to localize it. The Applications folder icon
+    will be shown in Finder, which should be clear enough for users.
+    """
+    if is_linux:
+        hfs = os.path.join(tmpdir, "staged.hfs")
+        subprocess.check_call([hfs_tool, hfs, "symlink", "/ ", "/Applications"])
+    elif is_osx:
+        os.symlink("/Applications", stagedir / " ")
+
+
+def create_dmg_from_staged(
+    stagedir: Path,
+    output_dmg: Path,
+    tmpdir: Path,
+    volume_name: str,
+    hfs_tool: Path = None,
+    dmg_tool: Path = None,
+    mkfshfs_tool: Path = None,
+    attribution_sentinel: str = None,
+):
+    "Given a prepared directory stagedir, produce a DMG at output_dmg."
+
+    if is_linux:
+        # The dmg tool doesn't create the destination directories, and silently
+        # returns success if the parent directory doesn't exist.
+        ensureParentDir(output_dmg)
+        hfs = os.path.join(tmpdir, "staged.hfs")
+        subprocess.check_call([hfs_tool, hfs, "addall", stagedir])
+
+        dmg_cmd = [dmg_tool, "build", hfs, output_dmg]
+        if attribution_sentinel:
+            while len(attribution_sentinel) < 1024:
+                attribution_sentinel += "\t"
+            subprocess.check_call(
+                [
+                    hfs_tool,
+                    hfs,
+                    "setattr",
+                    f"{volume_name}.app",
+                    "com.apple.application-instance",
+                    attribution_sentinel,
+                ]
+            )
+            subprocess.check_call(["cp", hfs, str(Path(output_dmg).parent)])
+            dmg_cmd.append(attribution_sentinel)
+
+        subprocess.check_call(
+            dmg_cmd,
+            # dmg is seriously chatty
+            stdout=subprocess.DEVNULL,
+        )
+    elif is_osx:
+        hybrid = tmpdir / "hybrid.dmg"
+        subprocess.check_call(
+            [
+                "hdiutil",
+                "makehybrid",
+                "-hfs",
+                "-hfs-volume-name",
+                volume_name,
+                "-hfs-openfolder",
+                stagedir,
+                "-ov",
+                stagedir,
+                "-o",
+                hybrid,
+            ]
+        )
+        subprocess.check_call(
+            [
+                "hdiutil",
+                "convert",
+                "-format",
+                "UDBZ",
+                "-imagekey",
+                "bzip2-level=9",
+                "-ov",
+                hybrid,
+                "-o",
+                output_dmg,
+            ]
+        )
+
+
+def create_dmg(
+    source_directory: Path,
+    output_dmg: Path,
+    volume_name: str,
+    extra_files: List[tuple],
+    dmg_tool: Path,
+    hfs_tool: Path,
+    mkfshfs_tool: Path,
+    attribution_sentinel: str = None,
+):
+    """
+    Create a DMG disk image at the path output_dmg from source_directory.
+
+    Use volume_name as the disk image volume name, and
+    use extra_files as a list of tuples of (filename, relative path) to copy
+    into the disk image.
+    """
+    if platform.system() not in ("Darwin", "Linux"):
+        raise Exception("Don't know how to build a DMG on '%s'" % platform.system())
+
+    with mozfile.TemporaryDirectory() as tmp:
+        tmpdir = Path(tmp)
+        stagedir = tmpdir / "stage"
+        stagedir.mkdir()
+
+        # Copy the app bundle over using rsync
+        rsync(source_directory, stagedir)
+        # Copy extra files
+        for source, target in extra_files:
+            full_target = stagedir / target
+            full_target.parent.mkdir(parents=True, exist_ok=True)
+            shutil.copyfile(source, full_target)
+        if is_linux:
+            # Not needed in osx
+            generate_hfs_file(stagedir, tmpdir, volume_name, mkfshfs_tool)
+        create_app_symlink(stagedir, tmpdir, hfs_tool)
+        # Set the folder attributes to use a custom icon
+        set_folder_icon(stagedir, tmpdir, hfs_tool)
+        chmod(stagedir)
+        create_dmg_from_staged(
+            stagedir,
+            output_dmg,
+            tmpdir,
+            volume_name,
+            hfs_tool,
+            dmg_tool,
+            mkfshfs_tool,
+            attribution_sentinel,
+        )
+
+
+def extract_dmg_contents(
+    dmgfile: Path,
+    destdir: Path,
+    dmg_tool: Path = None,
+    hfs_tool: Path = None,
+):
+    if is_linux:
+        with mozfile.TemporaryDirectory() as tmpdir:
+            hfs_file = os.path.join(tmpdir, "firefox.hfs")
+            subprocess.check_call(
+                [dmg_tool, "extract", dmgfile, hfs_file],
+                # dmg is seriously chatty
+                stdout=subprocess.DEVNULL,
+            )
+            subprocess.check_call([hfs_tool, hfs_file, "extractall", "/", destdir])
+    else:
+        # TODO: find better way to resolve topsrcdir (checkout directory)
+        topsrcdir = Path(__file__).parent.parent.parent.parent.resolve()
+        unpack_diskimage = topsrcdir / "build/package/mac_osx/unpack-diskimage"
+        unpack_mountpoint = Path("/tmp/app-unpack")
+        subprocess.check_call([unpack_diskimage, dmgfile, unpack_mountpoint, destdir])
+
+
+def extract_dmg(
+    dmgfile: Path,
+    output: Path,
+    dmg_tool: Path = None,
+    hfs_tool: Path = None,
+    dsstore: Path = None,
+    icon: Path = None,
+    background: Path = None,
+):
+    if platform.system() not in ("Darwin", "Linux"):
+        raise Exception("Don't know how to extract a DMG on '%s'" % platform.system())
+
+    with mozfile.TemporaryDirectory() as tmp:
+        tmpdir = Path(tmp)
+        extract_dmg_contents(dmgfile, tmpdir, dmg_tool, hfs_tool)
+        applications_symlink = tmpdir / " "
+        if applications_symlink.is_symlink():
+            # Rsync will fail on the presence of this symlink
+            applications_symlink.unlink()
+        rsync(tmpdir, output)
+
+        if dsstore:
+            dsstore.parent.mkdir(parents=True, exist_ok=True)
+            rsync(tmpdir / ".DS_Store", dsstore)
+        if background:
+            background.parent.mkdir(parents=True, exist_ok=True)
+            rsync(tmpdir / ".background" / background.name, background)
+        if icon:
+            icon.parent.mkdir(parents=True, exist_ok=True)
+            rsync(tmpdir / ".VolumeIcon.icns", icon)
diff --git a/python/mozbuild/mozpack/errors.py b/python/mozbuild/mozpack/errors.py
new file mode 100644
index 0000000000..25c0e8549c
--- /dev/null
+++ b/python/mozbuild/mozpack/errors.py
@@ -0,0 +1,151 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import sys
+from contextlib import contextmanager
+
+
+class ErrorMessage(Exception):
+    """Exception type raised from errors.error() and errors.fatal()"""
+
+
+class AccumulatedErrors(Exception):
+    """Exception type raised from errors.accumulate()"""
+
+
+class ErrorCollector(object):
+    """
+    Error handling/logging class. A global instance, errors, is provided for
+    convenience.
+
+    Warnings, errors and fatal errors may be logged by calls to the following
+    functions:
+      - errors.warn(message)
+      - errors.error(message)
+      - errors.fatal(message)
+
+    Warnings only send the message on the logging output, while errors and
+    fatal errors send the message and throw an ErrorMessage exception. The
+    exception, however, may be deferred. See further below.
+
+    Errors may be ignored by calling:
+      - errors.ignore_errors()
+
+    After calling that function, only fatal errors throw an exception.
+
+    The warnings, errors or fatal errors messages may be augmented with context
+    information when a context is provided. Context is defined by a pair
+    (filename, linenumber), and may be set with errors.context() used as a
+
+    context manager:
+
+    .. code-block:: python
+
+        with errors.context(filename, linenumber):
+            errors.warn(message)
+
+    Arbitrary nesting is supported, both for errors.context calls:
+
+    .. code-block:: python
+
+        with errors.context(filename1, linenumber1):
+            errors.warn(message)
+            with errors.context(filename2, linenumber2):
+                errors.warn(message)
+
+    as well as for function calls:
+
+    .. code-block:: python
+
+        def func():
+            errors.warn(message)
+            with errors.context(filename, linenumber):
+                func()
+
+    Errors and fatal errors can have their exception thrown at a later time,
+    allowing for several different errors to be reported at once before
+    throwing. This is achieved with errors.accumulate() as a context manager:
+
+    .. code-block:: python
+
+        with errors.accumulate():
+            if test1:
+                errors.error(message1)
+            if test2:
+                errors.error(message2)
+
+    In such cases, a single AccumulatedErrors exception is thrown, but doesn't
+    contain information about the exceptions. The logged messages do.
+    """
+
+    out = sys.stderr
+    WARN = 1
+    ERROR = 2
+    FATAL = 3
+    _level = ERROR
+    _context = []
+    _count = None
+
+    def ignore_errors(self, ignore=True):
+        if ignore:
+            self._level = self.FATAL
+        else:
+            self._level = self.ERROR
+
+    def _full_message(self, level, msg):
+        if level >= self._level:
+            level = "error"
+        else:
+            level = "warning"
+        if self._context:
+            file, line = self._context[-1]
+            return "%s: %s:%d: %s" % (level, file, line, msg)
+        return "%s: %s" % (level, msg)
+
+    def _handle(self, level, msg):
+        msg = self._full_message(level, msg)
+        if level >= self._level:
+            if self._count is None:
+                raise ErrorMessage(msg)
+            self._count += 1
+        print(msg, file=self.out)
+
+    def fatal(self, msg):
+        self._handle(self.FATAL, msg)
+
+    def error(self, msg):
+        self._handle(self.ERROR, msg)
+
+    def warn(self, msg):
+        self._handle(self.WARN, msg)
+
+    def get_context(self):
+        if self._context:
+            return self._context[-1]
+
+    @contextmanager
+    def context(self, file, line):
+        if file and line:
+            self._context.append((file, line))
+        yield
+        if file and line:
+            self._context.pop()
+
+    @contextmanager
+    def accumulate(self):
+        assert self._count is None
+        self._count = 0
+        yield
+        count = self._count
+        self._count = None
+        if count:
+            raise AccumulatedErrors()
+
+    @property
+    def count(self):
+        # _count can be None.
+        return self._count if self._count else 0
+
+
+errors = ErrorCollector()
diff --git a/python/mozbuild/mozpack/executables.py b/python/mozbuild/mozpack/executables.py
new file mode 100644
index 0000000000..38f0902826
--- /dev/null
+++ b/python/mozbuild/mozpack/executables.py
@@ -0,0 +1,135 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import struct
+import subprocess
+from io import BytesIO
+
+from mozpack.errors import errors
+
+MACHO_SIGNATURES = [
+    0xFEEDFACE,  # mach-o 32-bits big endian
+    0xCEFAEDFE,  # mach-o 32-bits little endian
+    0xFEEDFACF,  # mach-o 64-bits big endian
+    0xCFFAEDFE,  # mach-o 64-bits little endian
+]
+
+FAT_SIGNATURE = 0xCAFEBABE  # mach-o FAT binary
+
+ELF_SIGNATURE = 0x7F454C46  # Elf binary
+
+UNKNOWN = 0
+MACHO = 1
+ELF = 2
+
+
+def get_type(path_or_fileobj):
+    """
+    Check the signature of the give file and returns what kind of executable
+    matches.
+    """
+    if hasattr(path_or_fileobj, "peek"):
+        f = BytesIO(path_or_fileobj.peek(8))
+    elif hasattr(path_or_fileobj, "read"):
+        f = path_or_fileobj
+    else:
+        f = open(path_or_fileobj, "rb")
+    signature = f.read(4)
+    if len(signature) < 4:
+        return UNKNOWN
+    signature = struct.unpack(">L", signature)[0]
+    if signature == ELF_SIGNATURE:
+        return ELF
+    if signature in MACHO_SIGNATURES:
+        return MACHO
+    if signature != FAT_SIGNATURE:
+        return UNKNOWN
+    # We have to sanity check the second four bytes, because Java class
+    # files use the same magic number as Mach-O fat binaries.
+    # This logic is adapted from file(1), which says that Mach-O uses
+    # these bytes to count the number of architectures within, while
+    # Java uses it for a version number. Conveniently, there are only
+    # 18 labelled Mach-O architectures, and Java's first released
+    # class format used the version 43.0.
+    num = f.read(4)
+    if len(num) < 4:
+        return UNKNOWN
+    num = struct.unpack(">L", num)[0]
+    if num < 20:
+        return MACHO
+    return UNKNOWN
+
+
+def is_executable(path):
+    """
+    Return whether a given file path points to an executable or a library,
+    where an executable or library is identified by:
+    - the file extension on OS/2 and WINNT
+    - the file signature on OS/X and ELF systems (GNU/Linux, Android, BSD, Solaris)
+
+    As this function is intended for use to choose between the ExecutableFile
+    and File classes in FileFinder, and choosing ExecutableFile only matters
+    on OS/2, OS/X, ELF and WINNT (in GCC build) systems, we don't bother
+    detecting other kind of executables.
+    """
+    from buildconfig import substs
+
+    if not os.path.exists(path):
+        return False
+
+    if substs["OS_ARCH"] == "WINNT":
+        return path.lower().endswith((substs["DLL_SUFFIX"], substs["BIN_SUFFIX"]))
+
+    return get_type(path) != UNKNOWN
+
+
+def may_strip(path):
+    """
+    Return whether strip() should be called
+    """
+    from buildconfig import substs
+
+    return bool(substs.get("PKG_STRIP"))
+
+
+def strip(path):
+    """
+    Execute the STRIP command with STRIP_FLAGS on the given path.
+    """
+    from buildconfig import substs
+
+    strip = substs["STRIP"]
+    flags = substs.get("STRIP_FLAGS", [])
+    cmd = [strip] + flags + [path]
+    if subprocess.call(cmd) != 0:
+        errors.fatal("Error executing " + " ".join(cmd))
+
+
+def may_elfhack(path):
+    """
+    Return whether elfhack() should be called
+    """
+    # elfhack only supports libraries. We should check the ELF header for
+    # the right flag, but checking the file extension works too.
+    from buildconfig import substs
+
+    return (
+        "USE_ELF_HACK" in substs
+        and substs["USE_ELF_HACK"]
+        and path.endswith(substs["DLL_SUFFIX"])
+        and "COMPILE_ENVIRONMENT" in substs
+        and substs["COMPILE_ENVIRONMENT"]
+    )
+
+
+def elfhack(path):
+    """
+    Execute the elfhack command on the given path.
+    """
+    from buildconfig import topobjdir
+
+    cmd = [os.path.join(topobjdir, "build/unix/elfhack/elfhack"), path]
+    if subprocess.call(cmd) != 0:
+        errors.fatal("Error executing " + " ".join(cmd))
diff --git a/python/mozbuild/mozpack/files.py b/python/mozbuild/mozpack/files.py
new file mode 100644
index 0000000000..a320e1f4b4
--- /dev/null
+++ b/python/mozbuild/mozpack/files.py
@@ -0,0 +1,1271 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import bisect
+import codecs
+import errno
+import inspect
+import os
+import platform
+import shutil
+import stat
+import subprocess
+import uuid
+from collections import OrderedDict
+from io import BytesIO
+from itertools import chain, takewhile
+from tarfile import TarFile, TarInfo
+from tempfile import NamedTemporaryFile, mkstemp
+
+import six
+from jsmin import JavascriptMinify
+
+import mozbuild.makeutil as makeutil
+import mozpack.path as mozpath
+from mozbuild.preprocessor import Preprocessor
+from mozbuild.util import FileAvoidWrite, ensure_unicode, memoize
+from mozpack.chrome.manifest import ManifestEntry, ManifestInterfaces
+from mozpack.errors import ErrorMessage, errors
+from mozpack.executables import elfhack, is_executable, may_elfhack, may_strip, strip
+from mozpack.mozjar import JarReader
+
+try:
+    import hglib
+except ImportError:
+    hglib = None
+
+
+# For clean builds, copying files on win32 using CopyFile through ctypes is
+# ~2x as fast as using shutil.copyfile.
+if platform.system() != "Windows":
+    _copyfile = shutil.copyfile
+else:
+    import ctypes
+
+    _kernel32 = ctypes.windll.kernel32
+    _CopyFileA = _kernel32.CopyFileA
+    _CopyFileW = _kernel32.CopyFileW
+
+    def _copyfile(src, dest):
+        # False indicates `dest` should be overwritten if it exists already.
+        if isinstance(src, six.text_type) and isinstance(dest, six.text_type):
+            _CopyFileW(src, dest, False)
+        elif isinstance(src, str) and isinstance(dest, str):
+            _CopyFileA(src, dest, False)
+        else:
+            raise TypeError("mismatched path types!")
+
+
+# Helper function; ensures we always open files with the correct encoding when
+# opening them in text mode.
+def _open(path, mode="r"):
+    if six.PY3 and "b" not in mode:
+        return open(path, mode, encoding="utf-8")
+    return open(path, mode)
+
+
+class Dest(object):
+    """
+    Helper interface for BaseFile.copy. The interface works as follows:
+      - read() and write() can be used to sequentially read/write from the underlying file.
+      - a call to read() after a write() will re-open the underlying file and read from it.
+      - a call to write() after a read() will re-open the underlying file, emptying it, and write to it.
+    """
+
+    def __init__(self, path):
+        self.file = None
+        self.mode = None
+        self.path = ensure_unicode(path)
+
+    @property
+    def name(self):
+        return self.path
+
+    def read(self, length=-1):
+        if self.mode != "r":
+            self.file = _open(self.path, mode="rb")
+            self.mode = "r"
+        return self.file.read(length)
+
+    def write(self, data):
+        if self.mode != "w":
+            self.file = _open(self.path, mode="wb")
+            self.mode = "w"
+        to_write = six.ensure_binary(data)
+        return self.file.write(to_write)
+
+    def exists(self):
+        return os.path.exists(self.path)
+
+    def close(self):
+        if self.mode:
+            self.mode = None
+            self.file.close()
+            self.file = None
+
+
+class BaseFile(object):
+    """
+    Base interface and helper for file copying. Derived class may implement
+    their own copy function, or rely on BaseFile.copy using the open() member
+    function and/or the path property.
+    """
+
+    @staticmethod
+    def is_older(first, second):
+        """
+        Compares the modification time of two files, and returns whether the
+        ``first`` file is older than the ``second`` file.
+        """
+        # os.path.getmtime returns a result in seconds with precision up to
+        # the microsecond. But microsecond is too precise because
+        # shutil.copystat only copies milliseconds, and seconds is not
+        # enough precision.
+        return int(os.path.getmtime(first) * 1000) <= int(
+            os.path.getmtime(second) * 1000
+        )
+
+    @staticmethod
+    def any_newer(dest, inputs):
+        """
+        Compares the modification time of ``dest`` to multiple input files, and
+        returns whether any of the ``inputs`` is newer (has a later mtime) than
+        ``dest``.
+        """
+        # os.path.getmtime returns a result in seconds with precision up to
+        # the microsecond. But microsecond is too precise because
+        # shutil.copystat only copies milliseconds, and seconds is not
+        # enough precision.
+        dest_mtime = int(os.path.getmtime(dest) * 1000)
+        for input in inputs:
+            try:
+                src_mtime = int(os.path.getmtime(input) * 1000)
+            except OSError as e:
+                if e.errno == errno.ENOENT:
+                    # If an input file was removed, we should update.
+                    return True
+                raise
+            if dest_mtime < src_mtime:
+                return True
+        return False
+
+    @staticmethod
+    def normalize_mode(mode):
+        # Normalize file mode:
+        # - keep file type (e.g. S_IFREG)
+        ret = stat.S_IFMT(mode)
+        # - expand user read and execute permissions to everyone
+        if mode & 0o0400:
+            ret |= 0o0444
+        if mode & 0o0100:
+            ret |= 0o0111
+        # - keep user write permissions
+        if mode & 0o0200:
+            ret |= 0o0200
+        # - leave away sticky bit, setuid, setgid
+        return ret
+
+    def copy(self, dest, skip_if_older=True):
+        """
+        Copy the BaseFile content to the destination given as a string or a
+        Dest instance. Avoids replacing existing files if the BaseFile content
+        matches that of the destination, or in case of plain files, if the
+        destination is newer than the original file. This latter behaviour is
+        disabled when skip_if_older is False.
+        Returns whether a copy was actually performed (True) or not (False).
+        """
+        if isinstance(dest, six.string_types):
+            dest = Dest(dest)
+        else:
+            assert isinstance(dest, Dest)
+
+        can_skip_content_check = False
+        if not dest.exists():
+            can_skip_content_check = True
+        elif getattr(self, "path", None) and getattr(dest, "path", None):
+            if skip_if_older and BaseFile.is_older(self.path, dest.path):
+                return False
+            elif os.path.getsize(self.path) != os.path.getsize(dest.path):
+                can_skip_content_check = True
+
+        if can_skip_content_check:
+            if getattr(self, "path", None) and getattr(dest, "path", None):
+                # The destination directory must exist, or CopyFile will fail.
+                destdir = os.path.dirname(dest.path)
+                try:
+                    os.makedirs(destdir)
+                except OSError as e:
+                    if e.errno != errno.EEXIST:
+                        raise
+                _copyfile(self.path, dest.path)
+                shutil.copystat(self.path, dest.path)
+            else:
+                # Ensure the file is always created
+                if not dest.exists():
+                    dest.write(b"")
+                shutil.copyfileobj(self.open(), dest)
+            return True
+
+        src = self.open()
+        accumulated_src_content = []
+        while True:
+            dest_content = dest.read(32768)
+            src_content = src.read(32768)
+            accumulated_src_content.append(src_content)
+            if len(dest_content) == len(src_content) == 0:
+                break
+            # If the read content differs between origin and destination,
+            # write what was read up to now, and copy the remainder.
+            if six.ensure_binary(dest_content) != six.ensure_binary(src_content):
+                dest.write(b"".join(accumulated_src_content))
+                shutil.copyfileobj(src, dest)
+                break
+        if hasattr(self, "path") and hasattr(dest, "path"):
+            shutil.copystat(self.path, dest.path)
+        return True
+
+    def open(self):
+        """
+        Return a file-like object allowing to read() the content of the
+        associated file. This is meant to be overloaded in subclasses to return
+        a custom file-like object.
+        """
+        assert self.path is not None
+        return open(self.path, "rb")
+
+    def read(self):
+        raise NotImplementedError("BaseFile.read() not implemented. Bug 1170329.")
+
+    def size(self):
+        """Returns size of the entry.
+
+        Derived classes are highly encouraged to override this with a more
+        optimal implementation.
+        """
+        return len(self.read())
+
+    @property
+    def mode(self):
+        """
+        Return the file's unix mode, or None if it has no meaning.
+        """
+        return None
+
+    def inputs(self):
+        """
+        Return an iterable of the input file paths that impact this output file.
+        """
+        raise NotImplementedError("BaseFile.inputs() not implemented.")
+
+
+class File(BaseFile):
+    """
+    File class for plain files.
+    """
+
+    def __init__(self, path):
+        self.path = ensure_unicode(path)
+
+    @property
+    def mode(self):
+        """
+        Return the file's unix mode, as returned by os.stat().st_mode.
+        """
+        if platform.system() == "Windows":
+            return None
+        assert self.path is not None
+        mode = os.stat(self.path).st_mode
+        return self.normalize_mode(mode)
+
+    def read(self):
+        """Return the contents of the file."""
+        with open(self.path, "rb") as fh:
+            return fh.read()
+
+    def size(self):
+        return os.stat(self.path).st_size
+
+    def inputs(self):
+        return (self.path,)
+
+
+class ExecutableFile(File):
+    """
+    File class for executable and library files on OS/2, OS/X and ELF systems.
+    (see mozpack.executables.is_executable documentation).
+    """
+
+    def __init__(self, path):
+        File.__init__(self, path)
+
+    def copy(self, dest, skip_if_older=True):
+        real_dest = dest
+        if not isinstance(dest, six.string_types):
+            fd, dest = mkstemp()
+            os.close(fd)
+            os.remove(dest)
+        assert isinstance(dest, six.string_types)
+        # If File.copy didn't actually copy because dest is newer, check the
+        # file sizes. If dest is smaller, it means it is already stripped and
+        # elfhacked, so we can skip.
+        if not File.copy(self, dest, skip_if_older) and os.path.getsize(
+            self.path
+        ) > os.path.getsize(dest):
+            return False
+        try:
+            if may_strip(dest):
+                strip(dest)
+            if may_elfhack(dest):
+                elfhack(dest)
+        except ErrorMessage:
+            os.remove(dest)
+            raise
+
+        if real_dest != dest:
+            f = File(dest)
+            ret = f.copy(real_dest, skip_if_older)
+            os.remove(dest)
+            return ret
+        return True
+
+
+class AbsoluteSymlinkFile(File):
+    """File class that is copied by symlinking (if available).
+
+    This class only works if the target path is absolute.
+    """
+
+    def __init__(self, path):
+        if not os.path.isabs(path):
+            raise ValueError("Symlink target not absolute: %s" % path)
+
+        File.__init__(self, path)
+
+    def copy(self, dest, skip_if_older=True):
+        assert isinstance(dest, six.string_types)
+
+        # The logic in this function is complicated by the fact that symlinks
+        # aren't universally supported. So, where symlinks aren't supported, we
+        # fall back to file copying. Keep in mind that symlink support is
+        # per-filesystem, not per-OS.
+
+        # Handle the simple case where symlinks are definitely not supported by
+        # falling back to file copy.
+        if not hasattr(os, "symlink"):
+            return File.copy(self, dest, skip_if_older=skip_if_older)
+
+        # Always verify the symlink target path exists.
+        if not os.path.exists(self.path):
+            errors.fatal("Symlink target path does not exist: %s" % self.path)
+
+        st = None
+
+        try:
+            st = os.lstat(dest)
+        except OSError as ose:
+            if ose.errno != errno.ENOENT:
+                raise
+
+        # If the dest is a symlink pointing to us, we have nothing to do.
+        # If it's the wrong symlink, the filesystem must support symlinks,
+        # so we replace with a proper symlink.
+        if st and stat.S_ISLNK(st.st_mode):
+            link = os.readlink(dest)
+            if link == self.path:
+                return False
+
+            os.remove(dest)
+            os.symlink(self.path, dest)
+            return True
+
+        # If the destination doesn't exist, we try to create a symlink. If that
+        # fails, we fall back to copy code.
+        if not st:
+            try:
+                os.symlink(self.path, dest)
+                return True
+            except OSError:
+                return File.copy(self, dest, skip_if_older=skip_if_older)
+
+        # Now the complicated part. If the destination exists, we could be
+        # replacing a file with a symlink. Or, the filesystem may not support
+        # symlinks. We want to minimize I/O overhead for performance reasons,
+        # so we keep the existing destination file around as long as possible.
+        # A lot of the system calls would be eliminated if we cached whether
+        # symlinks are supported. However, even if we performed a single
+        # up-front test of whether the root of the destination directory
+        # supports symlinks, there's no guarantee that all operations for that
+        # dest (or source) would be on the same filesystem and would support
+        # symlinks.
+        #
+        # Our strategy is to attempt to create a new symlink with a random
+        # name. If that fails, we fall back to copy mode. If that works, we
+        # remove the old destination and move the newly-created symlink into
+        # its place.
+
+        temp_dest = os.path.join(os.path.dirname(dest), str(uuid.uuid4()))
+        try:
+            os.symlink(self.path, temp_dest)
+        # TODO Figure out exactly how symlink creation fails and only trap
+        # that.
+        except EnvironmentError:
+            return File.copy(self, dest, skip_if_older=skip_if_older)
+
+        # If removing the original file fails, don't forget to clean up the
+        # temporary symlink.
+        try:
+            os.remove(dest)
+        except EnvironmentError:
+            os.remove(temp_dest)
+            raise
+
+        os.rename(temp_dest, dest)
+        return True
+
+
+class HardlinkFile(File):
+    """File class that is copied by hard linking (if available)
+
+    This is similar to the AbsoluteSymlinkFile, but with hard links. The symlink
+    implementation requires paths to be absolute, because they are resolved at
+    read time, which makes relative paths messy. Hard links resolve paths at
+    link-creation time, so relative paths are fine.
+    """
+
+    def copy(self, dest, skip_if_older=True):
+        assert isinstance(dest, six.string_types)
+
+        if not hasattr(os, "link"):
+            return super(HardlinkFile, self).copy(dest, skip_if_older=skip_if_older)
+
+        try:
+            path_st = os.stat(self.path)
+        except OSError as e:
+            if e.errno == errno.ENOENT:
+                errors.fatal("Hard link target path does not exist: %s" % self.path)
+            else:
+                raise
+
+        st = None
+        try:
+            st = os.lstat(dest)
+        except OSError as e:
+            if e.errno != errno.ENOENT:
+                raise
+
+        if st:
+            # The dest already points to the right place.
+            if st.st_dev == path_st.st_dev and st.st_ino == path_st.st_ino:
+                return False
+            # The dest exists and it points to the wrong place
+            os.remove(dest)
+
+        # At this point, either the dest used to exist and we just deleted it,
+        # or it never existed. We can now safely create the hard link.
+        try:
+            os.link(self.path, dest)
+        except OSError:
+            # If we can't hard link, fall back to copying
+            return super(HardlinkFile, self).copy(dest, skip_if_older=skip_if_older)
+        return True
+
+
+class ExistingFile(BaseFile):
+    """
+    File class that represents a file that may exist but whose content comes
+    from elsewhere.
+
+    This purpose of this class is to account for files that are installed via
+    external means. It is typically only used in manifests or in registries to
+    account for files.
+
+    When asked to copy, this class does nothing because nothing is known about
+    the source file/data.
+
+    Instances of this class come in two flavors: required and optional. If an
+    existing file is required, it must exist during copy() or an error is
+    raised.
+    """
+
+    def __init__(self, required):
+        self.required = required
+
+    def copy(self, dest, skip_if_older=True):
+        if isinstance(dest, six.string_types):
+            dest = Dest(dest)
+        else:
+            assert isinstance(dest, Dest)
+
+        if not self.required:
+            return
+
+        if not dest.exists():
+            errors.fatal("Required existing file doesn't exist: %s" % dest.path)
+
+    def inputs(self):
+        return ()
+
+
+class PreprocessedFile(BaseFile):
+    """
+    File class for a file that is preprocessed. PreprocessedFile.copy() runs
+    the preprocessor on the file to create the output.
+    """
+
+    def __init__(
+        self,
+        path,
+        depfile_path,
+        marker,
+        defines,
+        extra_depends=None,
+        silence_missing_directive_warnings=False,
+    ):
+        self.path = ensure_unicode(path)
+        self.depfile = ensure_unicode(depfile_path)
+        self.marker = marker
+        self.defines = defines
+        self.extra_depends = list(extra_depends or [])
+        self.silence_missing_directive_warnings = silence_missing_directive_warnings
+
+    def inputs(self):
+        pp = Preprocessor(defines=self.defines, marker=self.marker)
+        pp.setSilenceDirectiveWarnings(self.silence_missing_directive_warnings)
+
+        with _open(self.path, "r") as input:
+            with _open(os.devnull, "w") as output:
+                pp.processFile(input=input, output=output)
+
+        # This always yields at least self.path.
+        return pp.includes
+
+    def copy(self, dest, skip_if_older=True):
+        """
+        Invokes the preprocessor to create the destination file.
+        """
+        if isinstance(dest, six.string_types):
+            dest = Dest(dest)
+        else:
+            assert isinstance(dest, Dest)
+
+        # We have to account for the case where the destination exists and is a
+        # symlink to something. Since we know the preprocessor is certainly not
+        # going to create a symlink, we can just remove the existing one. If the
+        # destination is not a symlink, we leave it alone, since we're going to
+        # overwrite its contents anyway.
+        # If symlinks aren't supported at all, we can skip this step.
+        # See comment in AbsoluteSymlinkFile about Windows.
+        if hasattr(os, "symlink") and platform.system() != "Windows":
+            if os.path.islink(dest.path):
+                os.remove(dest.path)
+
+        pp_deps = set(self.extra_depends)
+
+        # If a dependency file was specified, and it exists, add any
+        # dependencies from that file to our list.
+        if self.depfile and os.path.exists(self.depfile):
+            target = mozpath.normpath(dest.name)
+            with _open(self.depfile, "rt") as fileobj:
+                for rule in makeutil.read_dep_makefile(fileobj):
+                    if target in rule.targets():
+                        pp_deps.update(rule.dependencies())
+
+        skip = False
+        if dest.exists() and skip_if_older:
+            # If a dependency file was specified, and it doesn't exist,
+            # assume that the preprocessor needs to be rerun. That will
+            # regenerate the dependency file.
+            if self.depfile and not os.path.exists(self.depfile):
+                skip = False
+            else:
+                skip = not BaseFile.any_newer(dest.path, pp_deps)
+
+        if skip:
+            return False
+
+        deps_out = None
+        if self.depfile:
+            deps_out = FileAvoidWrite(self.depfile)
+        pp = Preprocessor(defines=self.defines, marker=self.marker)
+        pp.setSilenceDirectiveWarnings(self.silence_missing_directive_warnings)
+
+        with _open(self.path, "r") as input:
+            pp.processFile(input=input, output=dest, depfile=deps_out)
+
+        dest.close()
+        if self.depfile:
+            deps_out.close()
+
+        return True
+
+
+class GeneratedFile(BaseFile):
+    """
+    File class for content with no previous existence on the filesystem.
+    """
+
+    def __init__(self, content):
+        self._content = content
+
+    @property
+    def content(self):
+        if inspect.isfunction(self._content):
+            self._content = self._content()
+        return six.ensure_binary(self._content)
+
+    @content.setter
+    def content(self, content):
+        self._content = content
+
+    def open(self):
+        return BytesIO(self.content)
+
+    def read(self):
+        return self.content
+
+    def size(self):
+        return len(self.content)
+
+    def inputs(self):
+        return ()
+
+
+class DeflatedFile(BaseFile):
+    """
+    File class for members of a jar archive. DeflatedFile.copy() effectively
+    extracts the file from the jar archive.
+    """
+
+    def __init__(self, file):
+        from mozpack.mozjar import JarFileReader
+
+        assert isinstance(file, JarFileReader)
+        self.file = file
+
+    def open(self):
+        self.file.seek(0)
+        return self.file
+
+
+class ExtractedTarFile(GeneratedFile):
+    """
+    File class for members of a tar archive. Contents of the underlying file
+    are extracted immediately and stored in memory.
+    """
+
+    def __init__(self, tar, info):
+        assert isinstance(info, TarInfo)
+        assert isinstance(tar, TarFile)
+        GeneratedFile.__init__(self, tar.extractfile(info).read())
+        self._unix_mode = self.normalize_mode(info.mode)
+
+    @property
+    def mode(self):
+        return self._unix_mode
+
+    def read(self):
+        return self.content
+
+
+class ManifestFile(BaseFile):
+    """
+    File class for a manifest file. It takes individual manifest entries (using
+    the add() and remove() member functions), and adjusts them to be relative
+    to the base path for the manifest, given at creation.
+    Example:
+        There is a manifest entry "content foobar foobar/content/" relative
+        to "foobar/chrome". When packaging, the entry will be stored in
+        jar:foobar/omni.ja!/chrome/chrome.manifest, which means the entry
+        will have to be relative to "chrome" instead of "foobar/chrome". This
+        doesn't really matter when serializing the entry, since this base path
+        is not written out, but it matters when moving the entry at the same
+        time, e.g. to jar:foobar/omni.ja!/chrome.manifest, which we don't do
+        currently but could in the future.
+    """
+
+    def __init__(self, base, entries=None):
+        self._base = base
+        self._entries = []
+        self._interfaces = []
+        for e in entries or []:
+            self.add(e)
+
+    def add(self, entry):
+        """
+        Add the given entry to the manifest. Entries are rebased at open() time
+        instead of add() time so that they can be more easily remove()d.
+        """
+        assert isinstance(entry, ManifestEntry)
+        if isinstance(entry, ManifestInterfaces):
+            self._interfaces.append(entry)
+        else:
+            self._entries.append(entry)
+
+    def remove(self, entry):
+        """
+        Remove the given entry from the manifest.
+        """
+        assert isinstance(entry, ManifestEntry)
+        if isinstance(entry, ManifestInterfaces):
+            self._interfaces.remove(entry)
+        else:
+            self._entries.remove(entry)
+
+    def open(self):
+        """
+        Return a file-like object allowing to read() the serialized content of
+        the manifest.
+        """
+        content = "".join(
+            "%s\n" % e.rebase(self._base)
+            for e in chain(self._entries, self._interfaces)
+        )
+        return BytesIO(six.ensure_binary(content))
+
+    def __iter__(self):
+        """
+        Iterate over entries in the manifest file.
+        """
+        return chain(self._entries, self._interfaces)
+
+    def isempty(self):
+        """
+        Return whether there are manifest entries to write
+        """
+        return len(self._entries) + len(self._interfaces) == 0
+
+
+class MinifiedCommentStripped(BaseFile):
+    """
+    File class for content minified by stripping comments. This wraps around a
+    BaseFile instance, and removes lines starting with a # from its content.
+    """
+
+    def __init__(self, file):
+        assert isinstance(file, BaseFile)
+        self._file = file
+
+    def open(self):
+        """
+        Return a file-like object allowing to read() the minified content of
+        the underlying file.
+        """
+        content = "".join(
+            l
+            for l in [six.ensure_text(s) for s in self._file.open().readlines()]
+            if not l.startswith("#")
+        )
+        return BytesIO(six.ensure_binary(content))
+
+
+class MinifiedJavaScript(BaseFile):
+    """
+    File class for minifying JavaScript files.
+    """
+
+    def __init__(self, file, verify_command=None):
+        assert isinstance(file, BaseFile)
+        self._file = file
+        self._verify_command = verify_command
+
+    def open(self):
+        output = six.StringIO()
+        minify = JavascriptMinify(
+            codecs.getreader("utf-8")(self._file.open()), output, quote_chars="'\"`"
+        )
+        minify.minify()
+        output.seek(0)
+        output_source = six.ensure_binary(output.getvalue())
+        output = BytesIO(output_source)
+
+        if not self._verify_command:
+            return output
+
+        input_source = self._file.open().read()
+
+        with NamedTemporaryFile("wb+") as fh1, NamedTemporaryFile("wb+") as fh2:
+            fh1.write(input_source)
+            fh2.write(output_source)
+            fh1.flush()
+            fh2.flush()
+
+            try:
+                args = list(self._verify_command)
+                args.extend([fh1.name, fh2.name])
+                subprocess.check_output(
+                    args, stderr=subprocess.STDOUT, universal_newlines=True
+                )
+            except subprocess.CalledProcessError as e:
+                errors.warn(
+                    "JS minification verification failed for %s:"
+                    % (getattr(self._file, "path", "<unknown>"))
+                )
+                # Prefix each line with "Warning:" so mozharness doesn't
+                # think these error messages are real errors.
+                for line in e.output.splitlines():
+                    errors.warn(line)
+
+                return self._file.open()
+
+        return output
+
+
+class BaseFinder(object):
+    def __init__(
+        self, base, minify=False, minify_js=False, minify_js_verify_command=None
+    ):
+        """
+        Initializes the instance with a reference base directory.
+
+        The optional minify argument specifies whether minification of code
+        should occur. minify_js is an additional option to control minification
+        of JavaScript. It requires minify to be True.
+
+        minify_js_verify_command can be used to optionally verify the results
+        of JavaScript minification. If defined, it is expected to be an iterable
+        that will constitute the first arguments to a called process which will
+        receive the filenames of the original and minified JavaScript files.
+        The invoked process can then verify the results. If minification is
+        rejected, the process exits with a non-0 exit code and the original
+        JavaScript source is used. An example value for this argument is
+        ('/path/to/js', '/path/to/verify/script.js').
+        """
+        if minify_js and not minify:
+            raise ValueError("minify_js requires minify.")
+
+        self.base = mozpath.normsep(base)
+        self._minify = minify
+        self._minify_js = minify_js
+        self._minify_js_verify_command = minify_js_verify_command
+
+    def find(self, pattern):
+        """
+        Yield path, BaseFile_instance pairs for all files under the base
+        directory and its subdirectories that match the given pattern. See the
+        mozpack.path.match documentation for a description of the handled
+        patterns.
+        """
+        while pattern.startswith("/"):
+            pattern = pattern[1:]
+        for p, f in self._find(pattern):
+            yield p, self._minify_file(p, f)
+
+    def get(self, path):
+        """Obtain a single file.
+
+        Where ``find`` is tailored towards matching multiple files, this method
+        is used for retrieving a single file. Use this method when performance
+        is critical.
+
+        Returns a ``BaseFile`` if at most one file exists or ``None`` otherwise.
+        """
+        files = list(self.find(path))
+        if len(files) != 1:
+            return None
+        return files[0][1]
+
+    def __iter__(self):
+        """
+        Iterates over all files under the base directory (excluding files
+        starting with a '.' and files at any level under a directory starting
+        with a '.').
+            for path, file in finder:
+                ...
+        """
+        return self.find("")
+
+    def __contains__(self, pattern):
+        raise RuntimeError(
+            "'in' operator forbidden for %s. Use contains()." % self.__class__.__name__
+        )
+
+    def contains(self, pattern):
+        """
+        Return whether some files under the base directory match the given
+        pattern. See the mozpack.path.match documentation for a description of
+        the handled patterns.
+        """
+        return any(self.find(pattern))
+
+    def _minify_file(self, path, file):
+        """
+        Return an appropriate MinifiedSomething wrapper for the given BaseFile
+        instance (file), according to the file type (determined by the given
+        path), if the FileFinder was created with minification enabled.
+        Otherwise, just return the given BaseFile instance.
+        """
+        if not self._minify or isinstance(file, ExecutableFile):
+            return file
+
+        if path.endswith((".ftl", ".properties")):
+            return MinifiedCommentStripped(file)
+
+        if self._minify_js and path.endswith((".js", ".jsm")):
+            return MinifiedJavaScript(file, self._minify_js_verify_command)
+
+        return file
+
+    def _find_helper(self, pattern, files, file_getter):
+        """Generic implementation of _find.
+
+        A few *Finder implementations share logic for returning results.
+        This function implements the custom logic.
+
+        The ``file_getter`` argument is a callable that receives a path
+        that is known to exist. The callable should return a ``BaseFile``
+        instance.
+        """
+        if "*" in pattern:
+            for p in files:
+                if mozpath.match(p, pattern):
+                    yield p, file_getter(p)
+        elif pattern == "":
+            for p in files:
+                yield p, file_getter(p)
+        elif pattern in files:
+            yield pattern, file_getter(pattern)
+        else:
+            for p in files:
+                if mozpath.basedir(p, [pattern]) == pattern:
+                    yield p, file_getter(p)
+
+
+class FileFinder(BaseFinder):
+    """
+    Helper to get appropriate BaseFile instances from the file system.
+    """
+
+    def __init__(
+        self,
+        base,
+        find_executables=False,
+        ignore=(),
+        ignore_broken_symlinks=False,
+        find_dotfiles=False,
+        **kargs
+    ):
+        """
+        Create a FileFinder for files under the given base directory.
+
+        The find_executables argument determines whether the finder needs to
+        try to guess whether files are executables. Disabling this guessing
+        when not necessary can speed up the finder significantly.
+
+        ``ignore`` accepts an iterable of patterns to ignore. Entries are
+        strings that match paths relative to ``base`` using
+        ``mozpath.match()``. This means if an entry corresponds
+        to a directory, all files under that directory will be ignored. If
+        an entry corresponds to a file, that particular file will be ignored.
+        ``ignore_broken_symlinks`` is passed by the packager to work around an
+        issue with the build system not cleaning up stale files in some common
+        cases. See bug 1297381.
+        """
+        BaseFinder.__init__(self, base, **kargs)
+        self.find_dotfiles = find_dotfiles
+        self.find_executables = find_executables
+        self.ignore = tuple(mozpath.normsep(path) for path in ignore)
+        self.ignore_broken_symlinks = ignore_broken_symlinks
+
+    def _find(self, pattern):
+        """
+        Actual implementation of FileFinder.find(), dispatching to specialized
+        member functions depending on what kind of pattern was given.
+        Note all files with a name starting with a '.' are ignored when
+        scanning directories, but are not ignored when explicitely requested.
+        """
+        if "*" in pattern:
+            return self._find_glob("", mozpath.split(pattern))
+        elif os.path.isdir(os.path.join(self.base, pattern)):
+            return self._find_dir(pattern)
+        else:
+            f = self.get(pattern)
+            return ((pattern, f),) if f else ()
+
+    def _find_dir(self, path):
+        """
+        Actual implementation of FileFinder.find() when the given pattern
+        corresponds to an existing directory under the base directory.
+        Ignores file names starting with a '.' under the given path. If the
+        path itself has leafs starting with a '.', they are not ignored.
+        """
+        for p in self.ignore:
+            if mozpath.match(path, p):
+                return
+
+        # The sorted makes the output idempotent. Otherwise, we are
+        # likely dependent on filesystem implementation details, such as
+        # inode ordering.
+        for p in sorted(os.listdir(os.path.join(self.base, path))):
+            if p.startswith("."):
+                if p in (".", ".."):
+                    continue
+                if not self.find_dotfiles:
+                    continue
+            for p_, f in self._find(mozpath.join(path, p)):
+                yield p_, f
+
+    def get(self, path):
+        srcpath = os.path.join(self.base, path)
+        if not os.path.lexists(srcpath):
+            return None
+
+        if self.ignore_broken_symlinks and not os.path.exists(srcpath):
+            return None
+
+        for p in self.ignore:
+            if mozpath.match(path, p):
+                return None
+
+        if self.find_executables and is_executable(srcpath):
+            return ExecutableFile(srcpath)
+        else:
+            return File(srcpath)
+
+    def _find_glob(self, base, pattern):
+        """
+        Actual implementation of FileFinder.find() when the given pattern
+        contains globbing patterns ('*' or '**'). This is meant to be an
+        equivalent of:
+            for p, f in self:
+                if mozpath.match(p, pattern):
+                    yield p, f
+        but avoids scanning the entire tree.
+        """
+        if not pattern:
+            for p, f in self._find(base):
+                yield p, f
+        elif pattern[0] == "**":
+            for p, f in self._find(base):
+                if mozpath.match(p, mozpath.join(*pattern)):
+                    yield p, f
+        elif "*" in pattern[0]:
+            if not os.path.exists(os.path.join(self.base, base)):
+                return
+
+            for p in self.ignore:
+                if mozpath.match(base, p):
+                    return
+
+            # See above comment w.r.t. sorted() and idempotent behavior.
+            for p in sorted(os.listdir(os.path.join(self.base, base))):
+                if p.startswith(".") and not pattern[0].startswith("."):
+                    continue
+                if mozpath.match(p, pattern[0]):
+                    for p_, f in self._find_glob(mozpath.join(base, p), pattern[1:]):
+                        yield p_, f
+        else:
+            for p, f in self._find_glob(mozpath.join(base, pattern[0]), pattern[1:]):
+                yield p, f
+
+
+class JarFinder(BaseFinder):
+    """
+    Helper to get appropriate DeflatedFile instances from a JarReader.
+    """
+
+    def __init__(self, base, reader, **kargs):
+        """
+        Create a JarFinder for files in the given JarReader. The base argument
+        is used as an indication of the Jar file location.
+        """
+        assert isinstance(reader, JarReader)
+        BaseFinder.__init__(self, base, **kargs)
+        self._files = OrderedDict((f.filename, f) for f in reader)
+
+    def _find(self, pattern):
+        """
+        Actual implementation of JarFinder.find(), dispatching to specialized
+        member functions depending on what kind of pattern was given.
+        """
+        return self._find_helper(
+            pattern, self._files, lambda x: DeflatedFile(self._files[x])
+        )
+
+
+class TarFinder(BaseFinder):
+    """
+    Helper to get files from a TarFile.
+    """
+
+    def __init__(self, base, tar, **kargs):
+        """
+        Create a TarFinder for files in the given TarFile. The base argument
+        is used as an indication of the Tar file location.
+        """
+        assert isinstance(tar, TarFile)
+        self._tar = tar
+        BaseFinder.__init__(self, base, **kargs)
+        self._files = OrderedDict((f.name, f) for f in tar if f.isfile())
+
+    def _find(self, pattern):
+        """
+        Actual implementation of TarFinder.find(), dispatching to specialized
+        member functions depending on what kind of pattern was given.
+        """
+        return self._find_helper(
+            pattern, self._files, lambda x: ExtractedTarFile(self._tar, self._files[x])
+        )
+
+
+class ComposedFinder(BaseFinder):
+    """
+    Composes multiple File Finders in some sort of virtual file system.
+
+    A ComposedFinder is initialized from a dictionary associating paths
+    to `*Finder instances.`
+
+    Note this could be optimized to be smarter than getting all the files
+    in advance.
+    """
+
+    def __init__(self, finders):
+        # Can't import globally, because of the dependency of mozpack.copier
+        # on this module.
+        from mozpack.copier import FileRegistry
+
+        self.files = FileRegistry()
+
+        for base, finder in sorted(six.iteritems(finders)):
+            if self.files.contains(base):
+                self.files.remove(base)
+            for p, f in finder.find(""):
+                self.files.add(mozpath.join(base, p), f)
+
+    def find(self, pattern):
+        for p in self.files.match(pattern):
+            yield p, self.files[p]
+
+
+class MercurialFile(BaseFile):
+    """File class for holding data from Mercurial."""
+
+    def __init__(self, client, rev, path):
+        self._content = client.cat(
+            [six.ensure_binary(path)], rev=six.ensure_binary(rev)
+        )
+
+    def open(self):
+        return BytesIO(six.ensure_binary(self._content))
+
+    def read(self):
+        return self._content
+
+
+class MercurialRevisionFinder(BaseFinder):
+    """A finder that operates on a specific Mercurial revision."""
+
+    def __init__(self, repo, rev=".", recognize_repo_paths=False, **kwargs):
+        """Create a finder attached to a specific revision in a repository.
+
+        If no revision is given, open the parent of the working directory.
+
+        ``recognize_repo_paths`` will enable a mode where ``.get()`` will
+        recognize full paths that include the repo's path. Typically Finder
+        instances are "bound" to a base directory and paths are relative to
+        that directory. This mode changes that. When this mode is activated,
+        ``.find()`` will not work! This mode exists to support the moz.build
+        reader, which uses absolute paths instead of relative paths. The reader
+        should eventually be rewritten to use relative paths and this hack
+        should be removed (TODO bug 1171069).
+        """
+        if not hglib:
+            raise Exception("hglib package not found")
+
+        super(MercurialRevisionFinder, self).__init__(base=repo, **kwargs)
+
+        self._root = mozpath.normpath(repo).rstrip("/")
+        self._recognize_repo_paths = recognize_repo_paths
+
+        # We change directories here otherwise we have to deal with relative
+        # paths.
+        oldcwd = os.getcwd()
+        os.chdir(self._root)
+        try:
+            self._client = hglib.open(path=repo, encoding=b"utf-8")
+        finally:
+            os.chdir(oldcwd)
+        self._rev = rev if rev is not None else "."
+        self._files = OrderedDict()
+
+        # Immediately populate the list of files in the repo since nearly every
+        # operation requires this list.
+        out = self._client.rawcommand(
+            [
+                b"files",
+                b"--rev",
+                six.ensure_binary(self._rev),
+            ]
+        )
+        for relpath in out.splitlines():
+            # Mercurial may use \ as path separator on Windows. So use
+            # normpath().
+            self._files[six.ensure_text(mozpath.normpath(relpath))] = None
+
+    def _find(self, pattern):
+        if self._recognize_repo_paths:
+            raise NotImplementedError("cannot use find with recognize_repo_path")
+
+        return self._find_helper(pattern, self._files, self._get)
+
+    def get(self, path):
+        path = mozpath.normpath(path)
+        if self._recognize_repo_paths:
+            if not path.startswith(self._root):
+                raise ValueError(
+                    "lookups in recognize_repo_paths mode must be "
+                    "prefixed with repo path: %s" % path
+                )
+            path = path[len(self._root) + 1 :]
+
+        try:
+            return self._get(path)
+        except KeyError:
+            return None
+
+    def _get(self, path):
+        # We lazy populate self._files because potentially creating tens of
+        # thousands of MercurialFile instances for every file in the repo is
+        # inefficient.
+        f = self._files[path]
+        if not f:
+            f = MercurialFile(self._client, self._rev, path)
+            self._files[path] = f
+
+        return f
+
+
+class FileListFinder(BaseFinder):
+    """Finder for a literal list of file names."""
+
+    def __init__(self, files):
+        """files must be a sorted list."""
+        self._files = files
+
+    @memoize
+    def _match(self, pattern):
+        """Return a sorted list of all files matching the given pattern."""
+        # We don't use the utility _find_helper method because it's not tuned
+        # for performance in the way that we would like this class to be. That's
+        # a possible avenue for refactoring here.
+        ret = []
+        # We do this as an optimization to figure out where in the sorted list
+        # to search and where to stop searching.
+        components = pattern.split("/")
+        prefix = "/".join(takewhile(lambda s: "*" not in s, components))
+        start = bisect.bisect_left(self._files, prefix)
+        for i in six.moves.range(start, len(self._files)):
+            f = self._files[i]
+            if not f.startswith(prefix):
+                break
+            # Skip hidden files while scanning.
+            if "/." in f[len(prefix) :]:
+                continue
+            if mozpath.match(f, pattern):
+                ret.append(f)
+        return ret
+
+    def find(self, pattern):
+        pattern = pattern.strip("/")
+        for path in self._match(pattern):
+            yield path, File(path)
diff --git a/python/mozbuild/mozpack/macpkg.py b/python/mozbuild/mozpack/macpkg.py
new file mode 100644
index 0000000000..367f38fd05
--- /dev/null
+++ b/python/mozbuild/mozpack/macpkg.py
@@ -0,0 +1,222 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# TODO: Eventually consolidate with mozpack.pkg module. This is kept separate
+# for now because of the vast difference in API, and to avoid churn for the
+# users of this module (docker images, macos SDK artifacts) when changes are
+# necessary in mozpack.pkg
+import bz2
+import concurrent.futures
+import io
+import lzma
+import os
+import struct
+import zlib
+from collections import deque, namedtuple
+from xml.etree.ElementTree import XML
+
+
+class ZlibFile(object):
+    def __init__(self, fileobj):
+        self.fileobj = fileobj
+        self.decompressor = zlib.decompressobj()
+        self.buf = b""
+
+    def read(self, length):
+        cutoff = min(length, len(self.buf))
+        result = self.buf[:cutoff]
+        self.buf = self.buf[cutoff:]
+        while len(result) < length:
+            buf = self.fileobj.read(io.DEFAULT_BUFFER_SIZE)
+            if not buf:
+                break
+            buf = self.decompressor.decompress(buf)
+            cutoff = min(length - len(result), len(buf))
+            result += buf[:cutoff]
+            self.buf += buf[cutoff:]
+        return result
+
+
+def unxar(fileobj):
+    magic = fileobj.read(4)
+    if magic != b"xar!":
+        raise Exception("Not a XAR?")
+
+    header_size = fileobj.read(2)
+    header_size = struct.unpack(">H", header_size)[0]
+    if header_size > 64:
+        raise Exception(
+            f"Don't know how to handle a {header_size} bytes XAR header size"
+        )
+    header_size -= 6  # what we've read so far.
+    header = fileobj.read(header_size)
+    if len(header) != header_size:
+        raise Exception("Failed to read XAR header")
+    (
+        version,
+        compressed_toc_len,
+        uncompressed_toc_len,
+        checksum_type,
+    ) = struct.unpack(">HQQL", header[:22])
+    if version != 1:
+        raise Exception(f"XAR version {version} not supported")
+    toc = fileobj.read(compressed_toc_len)
+    base = fileobj.tell()
+    if len(toc) != compressed_toc_len:
+        raise Exception("Failed to read XAR TOC")
+    toc = zlib.decompress(toc)
+    if len(toc) != uncompressed_toc_len:
+        raise Exception("Corrupted XAR?")
+    toc = XML(toc).find("toc")
+    queue = deque(toc.findall("file"))
+    while queue:
+        f = queue.pop()
+        queue.extend(f.iterfind("file"))
+        if f.find("type").text != "file":
+            continue
+        filename = f.find("name").text
+        data = f.find("data")
+        length = int(data.find("length").text)
+        size = int(data.find("size").text)
+        offset = int(data.find("offset").text)
+        encoding = data.find("encoding").get("style")
+        fileobj.seek(base + offset, os.SEEK_SET)
+        content = Take(fileobj, length)
+        if encoding == "application/octet-stream":
+            if length != size:
+                raise Exception(f"{length} != {size}")
+        elif encoding == "application/x-bzip2":
+            content = bz2.BZ2File(content)
+        elif encoding == "application/x-gzip":
+            # Despite the encoding saying gzip, it is in fact, a raw zlib stream.
+            content = ZlibFile(content)
+        else:
+            raise Exception(f"XAR encoding {encoding} not supported")
+
+        yield filename, content
+
+
+class Pbzx(object):
+    def __init__(self, fileobj):
+        magic = fileobj.read(4)
+        if magic != b"pbzx":
+            raise Exception("Not a PBZX payload?")
+        # The first thing in the file looks like the size of each
+        # decompressed chunk except the last one. It should match
+        # decompressed_size in all cases except last, but we don't
+        # check.
+        chunk_size = fileobj.read(8)
+        chunk_size = struct.unpack(">Q", chunk_size)[0]
+        executor = concurrent.futures.ThreadPoolExecutor(max_workers=os.cpu_count())
+        self.chunk_getter = executor.map(self._uncompress_chunk, self._chunker(fileobj))
+        self._init_one_chunk()
+
+    @staticmethod
+    def _chunker(fileobj):
+        while True:
+            header = fileobj.read(16)
+            if header == b"":
+                break
+            if len(header) != 16:
+                raise Exception("Corrupted PBZX payload?")
+            decompressed_size, compressed_size = struct.unpack(">QQ", header)
+            chunk = fileobj.read(compressed_size)
+            yield decompressed_size, compressed_size, chunk
+
+    @staticmethod
+    def _uncompress_chunk(data):
+        decompressed_size, compressed_size, chunk = data
+        if compressed_size != decompressed_size:
+            chunk = lzma.decompress(chunk)
+            if len(chunk) != decompressed_size:
+                raise Exception("Corrupted PBZX payload?")
+        return chunk
+
+    def _init_one_chunk(self):
+        self.offset = 0
+        self.chunk = next(self.chunk_getter, "")
+
+    def read(self, length=None):
+        if length == 0:
+            return b""
+        if length and len(self.chunk) >= self.offset + length:
+            start = self.offset
+            self.offset += length
+            return self.chunk[start : self.offset]
+        else:
+            result = self.chunk[self.offset :]
+            self._init_one_chunk()
+            if self.chunk:
+                # XXX: suboptimal if length is larger than the chunk size
+                result += self.read(None if length is None else length - len(result))
+            return result
+
+
+class Take(object):
+    """
+    File object wrapper that allows to read at most a certain length.
+    """
+
+    def __init__(self, fileobj, limit):
+        self.fileobj = fileobj
+        self.limit = limit
+
+    def read(self, length=None):
+        if length is None:
+            length = self.limit
+        else:
+            length = min(length, self.limit)
+        result = self.fileobj.read(length)
+        self.limit -= len(result)
+        return result
+
+
+CpioInfo = namedtuple("CpioInfo", ["mode", "nlink", "dev", "ino"])
+
+
+def uncpio(fileobj):
+    while True:
+        magic = fileobj.read(6)
+        # CPIO payloads in mac pkg files are using the portable ASCII format.
+        if magic != b"070707":
+            if magic.startswith(b"0707"):
+                raise Exception("Unsupported CPIO format")
+            raise Exception("Not a CPIO header")
+        header = fileobj.read(70)
+        (
+            dev,
+            ino,
+            mode,
+            uid,
+            gid,
+            nlink,
+            rdev,
+            mtime,
+            namesize,
+            filesize,
+        ) = struct.unpack(">6s6s6s6s6s6s6s11s6s11s", header)
+        dev = int(dev, 8)
+        ino = int(ino, 8)
+        mode = int(mode, 8)
+        nlink = int(nlink, 8)
+        namesize = int(namesize, 8)
+        filesize = int(filesize, 8)
+        name = fileobj.read(namesize)
+        if name[-1] != 0:
+            raise Exception("File name is not NUL terminated")
+        name = name[:-1]
+        if name == b"TRAILER!!!":
+            break
+
+        if b"/../" in name or name.startswith(b"../") or name == b"..":
+            raise Exception(".. is forbidden in file name")
+        if name.startswith(b"."):
+            name = name[1:]
+        if name.startswith(b"/"):
+            name = name[1:]
+        content = Take(fileobj, filesize)
+        yield name, CpioInfo(mode=mode, nlink=nlink, dev=dev, ino=ino), content
+        # Ensure the content is totally consumed
+        while content.read(4096):
+            pass
diff --git a/python/mozbuild/mozpack/manifests.py b/python/mozbuild/mozpack/manifests.py
new file mode 100644
index 0000000000..2df6c729ea
--- /dev/null
+++ b/python/mozbuild/mozpack/manifests.py
@@ -0,0 +1,483 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import json
+from contextlib import contextmanager
+
+import six
+
+import mozpack.path as mozpath
+
+from .files import (
+    AbsoluteSymlinkFile,
+    ExistingFile,
+    File,
+    FileFinder,
+    GeneratedFile,
+    HardlinkFile,
+    PreprocessedFile,
+)
+
+
+# This probably belongs in a more generic module. Where?
+@contextmanager
+def _auto_fileobj(path, fileobj, mode="r"):
+    if path and fileobj:
+        raise AssertionError("Only 1 of path or fileobj may be defined.")
+
+    if not path and not fileobj:
+        raise AssertionError("Must specified 1 of path or fileobj.")
+
+    if path:
+        fileobj = open(path, mode)
+
+    try:
+        yield fileobj
+    finally:
+        if path:
+            fileobj.close()
+
+
+class UnreadableInstallManifest(Exception):
+    """Raised when an invalid install manifest is parsed."""
+
+
+class InstallManifest(object):
+    """Describes actions to be used with a copier.FileCopier instance.
+
+    This class facilitates serialization and deserialization of data used to
+    construct a copier.FileCopier and to perform copy operations.
+
+    The manifest defines source paths, destination paths, and a mechanism by
+    which the destination file should come into existence.
+
+    Entries in the manifest correspond to the following types:
+
+      copy -- The file specified as the source path will be copied to the
+          destination path.
+
+      link -- The destination path will be a symlink or hardlink to the source
+          path. If symlinks are not supported, a copy will be performed.
+
+      exists -- The destination path is accounted for and won't be deleted by
+          the FileCopier. If the destination path doesn't exist, an error is
+          raised.
+
+      optional -- The destination path is accounted for and won't be deleted by
+          the FileCopier. No error is raised if the destination path does not
+          exist.
+
+      patternlink -- Paths matched by the expression in the source path
+          will be symlinked or hardlinked to the destination directory.
+
+      patterncopy -- Similar to patternlink except files are copied, not
+          symlinked/hardlinked.
+
+      preprocess -- The file specified at the source path will be run through
+          the preprocessor, and the output will be written to the destination
+          path.
+
+      content -- The destination file will be created with the given content.
+
+    Version 1 of the manifest was the initial version.
+    Version 2 added optional path support
+    Version 3 added support for pattern entries.
+    Version 4 added preprocessed file support.
+    Version 5 added content support.
+    """
+
+    CURRENT_VERSION = 5
+
+    FIELD_SEPARATOR = "\x1f"
+
+    # Negative values are reserved for non-actionable items, that is, metadata
+    # that doesn't describe files in the destination.
+    LINK = 1
+    COPY = 2
+    REQUIRED_EXISTS = 3
+    OPTIONAL_EXISTS = 4
+    PATTERN_LINK = 5
+    PATTERN_COPY = 6
+    PREPROCESS = 7
+    CONTENT = 8
+
+    def __init__(self, path=None, fileobj=None):
+        """Create a new InstallManifest entry.
+
+        If path is defined, the manifest will be populated with data from the
+        file path.
+
+        If fileobj is defined, the manifest will be populated with data read
+        from the specified file object.
+
+        Both path and fileobj cannot be defined.
+        """
+        self._dests = {}
+        self._source_files = set()
+
+        if path or fileobj:
+            with _auto_fileobj(path, fileobj, "r") as fh:
+                self._source_files.add(fh.name)
+                self._load_from_fileobj(fh)
+
+    def _load_from_fileobj(self, fileobj):
+        version = fileobj.readline().rstrip()
+        if version not in ("1", "2", "3", "4", "5"):
+            raise UnreadableInstallManifest("Unknown manifest version: %s" % version)
+
+        for line in fileobj:
+            # Explicitly strip on \n so we don't strip out the FIELD_SEPARATOR
+            # as well.
+            line = line.rstrip("\n")
+
+            fields = line.split(self.FIELD_SEPARATOR)
+
+            record_type = int(fields[0])
+
+            if record_type == self.LINK:
+                dest, source = fields[1:]
+                self.add_link(source, dest)
+                continue
+
+            if record_type == self.COPY:
+                dest, source = fields[1:]
+                self.add_copy(source, dest)
+                continue
+
+            if record_type == self.REQUIRED_EXISTS:
+                _, path = fields
+                self.add_required_exists(path)
+                continue
+
+            if record_type == self.OPTIONAL_EXISTS:
+                _, path = fields
+                self.add_optional_exists(path)
+                continue
+
+            if record_type == self.PATTERN_LINK:
+                _, base, pattern, dest = fields[1:]
+                self.add_pattern_link(base, pattern, dest)
+                continue
+
+            if record_type == self.PATTERN_COPY:
+                _, base, pattern, dest = fields[1:]
+                self.add_pattern_copy(base, pattern, dest)
+                continue
+
+            if record_type == self.PREPROCESS:
+                dest, source, deps, marker, defines, warnings = fields[1:]
+
+                self.add_preprocess(
+                    source,
+                    dest,
+                    deps,
+                    marker,
+                    self._decode_field_entry(defines),
+                    silence_missing_directive_warnings=bool(int(warnings)),
+                )
+                continue
+
+            if record_type == self.CONTENT:
+                dest, content = fields[1:]
+
+                self.add_content(
+                    six.ensure_text(self._decode_field_entry(content)), dest
+                )
+                continue
+
+            # Don't fail for non-actionable items, allowing
+            # forward-compatibility with those we will add in the future.
+            if record_type >= 0:
+                raise UnreadableInstallManifest("Unknown record type: %d" % record_type)
+
+    def __len__(self):
+        return len(self._dests)
+
+    def __contains__(self, item):
+        return item in self._dests
+
+    def __eq__(self, other):
+        return isinstance(other, InstallManifest) and self._dests == other._dests
+
+    def __neq__(self, other):
+        return not self.__eq__(other)
+
+    def __ior__(self, other):
+        if not isinstance(other, InstallManifest):
+            raise ValueError("Can only | with another instance of InstallManifest.")
+
+        self.add_entries_from(other)
+
+        return self
+
+    def _encode_field_entry(self, data):
+        """Converts an object into a format that can be stored in the manifest file.
+
+        Complex data types, such as ``dict``, need to be converted into a text
+        representation before they can be written to a file.
+        """
+        return json.dumps(data, sort_keys=True)
+
+    def _decode_field_entry(self, data):
+        """Restores an object from a format that can be stored in the manifest file.
+
+        Complex data types, such as ``dict``, need to be converted into a text
+        representation before they can be written to a file.
+        """
+        return json.loads(data)
+
+    def write(self, path=None, fileobj=None, expand_pattern=False):
+        """Serialize this manifest to a file or file object.
+
+        If path is specified, that file will be written to. If fileobj is specified,
+        the serialized content will be written to that file object.
+
+        It is an error if both are specified.
+        """
+        with _auto_fileobj(path, fileobj, "wt") as fh:
+            fh.write("%d\n" % self.CURRENT_VERSION)
+
+            for dest in sorted(self._dests):
+                entry = self._dests[dest]
+
+                if expand_pattern and entry[0] in (
+                    self.PATTERN_LINK,
+                    self.PATTERN_COPY,
+                ):
+                    type, base, pattern, dest = entry
+                    type = self.LINK if type == self.PATTERN_LINK else self.COPY
+                    finder = FileFinder(base)
+                    paths = [f[0] for f in finder.find(pattern)]
+                    for path in paths:
+                        source = mozpath.join(base, path)
+                        parts = ["%d" % type, mozpath.join(dest, path), source]
+                        fh.write(
+                            "%s\n"
+                            % self.FIELD_SEPARATOR.join(
+                                six.ensure_text(p) for p in parts
+                            )
+                        )
+                else:
+                    parts = ["%d" % entry[0], dest]
+                    parts.extend(entry[1:])
+                    fh.write(
+                        "%s\n"
+                        % self.FIELD_SEPARATOR.join(six.ensure_text(p) for p in parts)
+                    )
+
+    def add_link(self, source, dest):
+        """Add a link to this manifest.
+
+        dest will be either a symlink or hardlink to source.
+        """
+        self._add_entry(dest, (self.LINK, source))
+
+    def add_copy(self, source, dest):
+        """Add a copy to this manifest.
+
+        source will be copied to dest.
+        """
+        self._add_entry(dest, (self.COPY, source))
+
+    def add_required_exists(self, dest):
+        """Record that a destination file must exist.
+
+        This effectively prevents the listed file from being deleted.
+        """
+        self._add_entry(dest, (self.REQUIRED_EXISTS,))
+
+    def add_optional_exists(self, dest):
+        """Record that a destination file may exist.
+
+        This effectively prevents the listed file from being deleted. Unlike a
+        "required exists" file, files of this type do not raise errors if the
+        destination file does not exist.
+        """
+        self._add_entry(dest, (self.OPTIONAL_EXISTS,))
+
+    def add_pattern_link(self, base, pattern, dest):
+        """Add a pattern match that results in links being created.
+
+        A ``FileFinder`` will be created with its base set to ``base``
+        and ``FileFinder.find()`` will be called with ``pattern`` to discover
+        source files. Each source file will be either symlinked or hardlinked
+        under ``dest``.
+
+        Filenames under ``dest`` are constructed by taking the path fragment
+        after ``base`` and concatenating it with ``dest``. e.g.
+
+           <base>/foo/bar.h -> <dest>/foo/bar.h
+        """
+        self._add_entry(
+            mozpath.join(dest, pattern), (self.PATTERN_LINK, base, pattern, dest)
+        )
+
+    def add_pattern_copy(self, base, pattern, dest):
+        """Add a pattern match that results in copies.
+
+        See ``add_pattern_link()`` for usage.
+        """
+        self._add_entry(
+            mozpath.join(dest, pattern), (self.PATTERN_COPY, base, pattern, dest)
+        )
+
+    def add_preprocess(
+        self,
+        source,
+        dest,
+        deps,
+        marker="#",
+        defines={},
+        silence_missing_directive_warnings=False,
+    ):
+        """Add a preprocessed file to this manifest.
+
+        ``source`` will be passed through preprocessor.py, and the output will be
+        written to ``dest``.
+        """
+        self._add_entry(
+            dest,
+            (
+                self.PREPROCESS,
+                source,
+                deps,
+                marker,
+                self._encode_field_entry(defines),
+                "1" if silence_missing_directive_warnings else "0",
+            ),
+        )
+
+    def add_content(self, content, dest):
+        """Add a file with the given content."""
+        self._add_entry(
+            dest,
+            (
+                self.CONTENT,
+                self._encode_field_entry(content),
+            ),
+        )
+
+    def _add_entry(self, dest, entry):
+        if dest in self._dests:
+            raise ValueError("Item already in manifest: %s" % dest)
+
+        self._dests[dest] = entry
+
+    def add_entries_from(self, other, base=""):
+        """
+        Copy data from another mozpack.copier.InstallManifest
+        instance, adding an optional base prefix to the destination.
+
+        This allows to merge two manifests into a single manifest, or
+        two take the tagged union of two manifests.
+        """
+        # We must copy source files to ourselves so extra dependencies from
+        # the preprocessor are taken into account. Ideally, we would track
+        # which source file each entry came from. However, this is more
+        # complicated and not yet implemented. The current implementation
+        # will result in over invalidation, possibly leading to performance
+        # loss.
+        self._source_files |= other._source_files
+
+        for dest in sorted(other._dests):
+            new_dest = mozpath.join(base, dest) if base else dest
+            entry = other._dests[dest]
+            if entry[0] in (self.PATTERN_LINK, self.PATTERN_COPY):
+                entry_type, entry_base, entry_pattern, entry_dest = entry
+                new_entry_dest = mozpath.join(base, entry_dest) if base else entry_dest
+                new_entry = (entry_type, entry_base, entry_pattern, new_entry_dest)
+            else:
+                new_entry = tuple(entry)
+
+            self._add_entry(new_dest, new_entry)
+
+    def populate_registry(self, registry, defines_override={}, link_policy="symlink"):
+        """Populate a mozpack.copier.FileRegistry instance with data from us.
+
+        The caller supplied a FileRegistry instance (or at least something that
+        conforms to its interface) and that instance is populated with data
+        from this manifest.
+
+        Defines can be given to override the ones in the manifest for
+        preprocessing.
+
+        The caller can set a link policy. This determines whether symlinks,
+        hardlinks, or copies are used for LINK and PATTERN_LINK.
+        """
+        assert link_policy in ("symlink", "hardlink", "copy")
+        for dest in sorted(self._dests):
+            entry = self._dests[dest]
+            install_type = entry[0]
+
+            if install_type == self.LINK:
+                if link_policy == "symlink":
+                    cls = AbsoluteSymlinkFile
+                elif link_policy == "hardlink":
+                    cls = HardlinkFile
+                else:
+                    cls = File
+                registry.add(dest, cls(entry[1]))
+                continue
+
+            if install_type == self.COPY:
+                registry.add(dest, File(entry[1]))
+                continue
+
+            if install_type == self.REQUIRED_EXISTS:
+                registry.add(dest, ExistingFile(required=True))
+                continue
+
+            if install_type == self.OPTIONAL_EXISTS:
+                registry.add(dest, ExistingFile(required=False))
+                continue
+
+            if install_type in (self.PATTERN_LINK, self.PATTERN_COPY):
+                _, base, pattern, dest = entry
+                finder = FileFinder(base)
+                paths = [f[0] for f in finder.find(pattern)]
+
+                if install_type == self.PATTERN_LINK:
+                    if link_policy == "symlink":
+                        cls = AbsoluteSymlinkFile
+                    elif link_policy == "hardlink":
+                        cls = HardlinkFile
+                    else:
+                        cls = File
+                else:
+                    cls = File
+
+                for path in paths:
+                    source = mozpath.join(base, path)
+                    registry.add(mozpath.join(dest, path), cls(source))
+
+                continue
+
+            if install_type == self.PREPROCESS:
+                defines = self._decode_field_entry(entry[4])
+                if defines_override:
+                    defines.update(defines_override)
+                registry.add(
+                    dest,
+                    PreprocessedFile(
+                        entry[1],
+                        depfile_path=entry[2],
+                        marker=entry[3],
+                        defines=defines,
+                        extra_depends=self._source_files,
+                        silence_missing_directive_warnings=bool(int(entry[5])),
+                    ),
+                )
+
+                continue
+
+            if install_type == self.CONTENT:
+                # GeneratedFile expect the buffer interface, which the unicode
+                # type doesn't have, so encode to a str.
+                content = self._decode_field_entry(entry[1]).encode("utf-8")
+                registry.add(dest, GeneratedFile(content))
+                continue
+
+            raise Exception(
+                "Unknown install type defined in manifest: %d" % install_type
+            )
diff --git a/python/mozbuild/mozpack/mozjar.py b/python/mozbuild/mozpack/mozjar.py
new file mode 100644
index 0000000000..6500ebfcec
--- /dev/null
+++ b/python/mozbuild/mozpack/mozjar.py
@@ -0,0 +1,842 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import struct
+import zlib
+from collections import OrderedDict
+from io import BytesIO, UnsupportedOperation
+from zipfile import ZIP_DEFLATED, ZIP_STORED
+
+import six
+
+import mozpack.path as mozpath
+from mozbuild.util import ensure_bytes
+
+JAR_STORED = ZIP_STORED
+JAR_DEFLATED = ZIP_DEFLATED
+MAX_WBITS = 15
+
+
+class JarReaderError(Exception):
+    """Error type for Jar reader errors."""
+
+
+class JarWriterError(Exception):
+    """Error type for Jar writer errors."""
+
+
+class JarStruct(object):
+    """
+    Helper used to define ZIP archive raw data structures. Data structures
+    handled by this helper all start with a magic number, defined in
+    subclasses MAGIC field as a 32-bits unsigned integer, followed by data
+    structured as described in subclasses STRUCT field.
+
+    The STRUCT field contains a list of (name, type) pairs where name is a
+    field name, and the type can be one of 'uint32', 'uint16' or one of the
+    field names. In the latter case, the field is considered to be a string
+    buffer with a length given in that field.
+    For example,
+
+    .. code-block:: python
+
+        STRUCT = [
+            ('version', 'uint32'),
+            ('filename_size', 'uint16'),
+            ('filename', 'filename_size')
+        ]
+
+    describes a structure with a 'version' 32-bits unsigned integer field,
+    followed by a 'filename_size' 16-bits unsigned integer field, followed by a
+    filename_size-long string buffer 'filename'.
+
+    Fields that are used as other fields size are not stored in objects. In the
+    above example, an instance of such subclass would only have two attributes:
+      - obj['version']
+      - obj['filename']
+
+    filename_size would be obtained with len(obj['filename']).
+
+    JarStruct subclasses instances can be either initialized from existing data
+    (deserialized), or with empty fields.
+    """
+
+    TYPE_MAPPING = {"uint32": (b"I", 4), "uint16": (b"H", 2)}
+
+    def __init__(self, data=None):
+        """
+        Create an instance from the given data. Data may be omitted to create
+        an instance with empty fields.
+        """
+        assert self.MAGIC and isinstance(self.STRUCT, OrderedDict)
+        self.size_fields = set(
+            t for t in six.itervalues(self.STRUCT) if t not in JarStruct.TYPE_MAPPING
+        )
+        self._values = {}
+        if data:
+            self._init_data(data)
+        else:
+            self._init_empty()
+
+    def _init_data(self, data):
+        """
+        Initialize an instance from data, following the data structure
+        described in self.STRUCT. The self.MAGIC signature is expected at
+        data[:4].
+        """
+        assert data is not None
+        self.signature, size = JarStruct.get_data("uint32", data)
+        if self.signature != self.MAGIC:
+            raise JarReaderError("Bad magic")
+        offset = size
+        # For all fields used as other fields sizes, keep track of their value
+        # separately.
+        sizes = dict((t, 0) for t in self.size_fields)
+        for name, t in six.iteritems(self.STRUCT):
+            if t in JarStruct.TYPE_MAPPING:
+                value, size = JarStruct.get_data(t, data[offset:])
+            else:
+                size = sizes[t]
+                value = data[offset : offset + size]
+                if isinstance(value, memoryview):
+                    value = value.tobytes()
+            if name not in sizes:
+                self._values[name] = value
+            else:
+                sizes[name] = value
+            offset += size
+
+    def _init_empty(self):
+        """
+        Initialize an instance with empty fields.
+        """
+        self.signature = self.MAGIC
+        for name, t in six.iteritems(self.STRUCT):
+            if name in self.size_fields:
+                continue
+            self._values[name] = 0 if t in JarStruct.TYPE_MAPPING else ""
+
+    @staticmethod
+    def get_data(type, data):
+        """
+        Deserialize a single field of given type (must be one of
+        JarStruct.TYPE_MAPPING) at the given offset in the given data.
+        """
+        assert type in JarStruct.TYPE_MAPPING
+        assert data is not None
+        format, size = JarStruct.TYPE_MAPPING[type]
+        data = data[:size]
+        if isinstance(data, memoryview):
+            data = data.tobytes()
+        return struct.unpack(b"<" + format, data)[0], size
+
+    def serialize(self):
+        """
+        Serialize the data structure according to the data structure definition
+        from self.STRUCT.
+        """
+        serialized = struct.pack(b"<I", self.signature)
+        sizes = dict(
+            (t, name)
+            for name, t in six.iteritems(self.STRUCT)
+            if t not in JarStruct.TYPE_MAPPING
+        )
+        for name, t in six.iteritems(self.STRUCT):
+            if t in JarStruct.TYPE_MAPPING:
+                format, size = JarStruct.TYPE_MAPPING[t]
+                if name in sizes:
+                    value = len(self[sizes[name]])
+                else:
+                    value = self[name]
+                serialized += struct.pack(b"<" + format, value)
+            else:
+                serialized += ensure_bytes(self[name])
+        return serialized
+
+    @property
+    def size(self):
+        """
+        Return the size of the data structure, given the current values of all
+        variable length fields.
+        """
+        size = JarStruct.TYPE_MAPPING["uint32"][1]
+        for name, type in six.iteritems(self.STRUCT):
+            if type in JarStruct.TYPE_MAPPING:
+                size += JarStruct.TYPE_MAPPING[type][1]
+            else:
+                size += len(self[name])
+        return size
+
+    def __getitem__(self, key):
+        return self._values[key]
+
+    def __setitem__(self, key, value):
+        if key not in self.STRUCT:
+            raise KeyError(key)
+        if key in self.size_fields:
+            raise AttributeError("can't set attribute")
+        self._values[key] = value
+
+    def __contains__(self, key):
+        return key in self._values
+
+    def __iter__(self):
+        return six.iteritems(self._values)
+
+    def __repr__(self):
+        return "<%s %s>" % (
+            self.__class__.__name__,
+            " ".join("%s=%s" % (n, v) for n, v in self),
+        )
+
+
+class JarCdirEnd(JarStruct):
+    """
+    End of central directory record.
+    """
+
+    MAGIC = 0x06054B50
+    STRUCT = OrderedDict(
+        [
+            ("disk_num", "uint16"),
+            ("cdir_disk", "uint16"),
+            ("disk_entries", "uint16"),
+            ("cdir_entries", "uint16"),
+            ("cdir_size", "uint32"),
+            ("cdir_offset", "uint32"),
+            ("comment_size", "uint16"),
+            ("comment", "comment_size"),
+        ]
+    )
+
+
+CDIR_END_SIZE = JarCdirEnd().size
+
+
+class JarCdirEntry(JarStruct):
+    """
+    Central directory file header
+    """
+
+    MAGIC = 0x02014B50
+    STRUCT = OrderedDict(
+        [
+            ("creator_version", "uint16"),
+            ("min_version", "uint16"),
+            ("general_flag", "uint16"),
+            ("compression", "uint16"),
+            ("lastmod_time", "uint16"),
+            ("lastmod_date", "uint16"),
+            ("crc32", "uint32"),
+            ("compressed_size", "uint32"),
+            ("uncompressed_size", "uint32"),
+            ("filename_size", "uint16"),
+            ("extrafield_size", "uint16"),
+            ("filecomment_size", "uint16"),
+            ("disknum", "uint16"),
+            ("internal_attr", "uint16"),
+            ("external_attr", "uint32"),
+            ("offset", "uint32"),
+            ("filename", "filename_size"),
+            ("extrafield", "extrafield_size"),
+            ("filecomment", "filecomment_size"),
+        ]
+    )
+
+
+class JarLocalFileHeader(JarStruct):
+    """
+    Local file header
+    """
+
+    MAGIC = 0x04034B50
+    STRUCT = OrderedDict(
+        [
+            ("min_version", "uint16"),
+            ("general_flag", "uint16"),
+            ("compression", "uint16"),
+            ("lastmod_time", "uint16"),
+            ("lastmod_date", "uint16"),
+            ("crc32", "uint32"),
+            ("compressed_size", "uint32"),
+            ("uncompressed_size", "uint32"),
+            ("filename_size", "uint16"),
+            ("extra_field_size", "uint16"),
+            ("filename", "filename_size"),
+            ("extra_field", "extra_field_size"),
+        ]
+    )
+
+
+class JarFileReader(object):
+    """
+    File-like class for use by JarReader to give access to individual files
+    within a Jar archive.
+    """
+
+    def __init__(self, header, data):
+        """
+        Initialize a JarFileReader. header is the local file header
+        corresponding to the file in the jar archive, data a buffer containing
+        the file data.
+        """
+        assert header["compression"] in [JAR_DEFLATED, JAR_STORED]
+        self._data = data
+        # Copy some local file header fields.
+        for name in ["compressed_size", "uncompressed_size", "crc32"]:
+            setattr(self, name, header[name])
+        self.filename = six.ensure_text(header["filename"])
+        self.compressed = header["compression"] != JAR_STORED
+        self.compress = header["compression"]
+
+    def readable(self):
+        return True
+
+    def read(self, length=-1):
+        """
+        Read some amount of uncompressed data.
+        """
+        return self.uncompressed_data.read(length)
+
+    def readinto(self, b):
+        """
+        Read bytes into a pre-allocated, writable bytes-like object `b` and return
+        the number of bytes read.
+        """
+        return self.uncompressed_data.readinto(b)
+
+    def readlines(self):
+        """
+        Return a list containing all the lines of data in the uncompressed
+        data.
+        """
+        return self.read().splitlines(True)
+
+    def __iter__(self):
+        """
+        Iterator, to support the "for line in fileobj" constructs.
+        """
+        return iter(self.readlines())
+
+    def seek(self, pos, whence=os.SEEK_SET):
+        """
+        Change the current position in the uncompressed data. Subsequent reads
+        will start from there.
+        """
+        return self.uncompressed_data.seek(pos, whence)
+
+    def close(self):
+        """
+        Free the uncompressed data buffer.
+        """
+        self.uncompressed_data.close()
+
+    @property
+    def closed(self):
+        return self.uncompressed_data.closed
+
+    @property
+    def compressed_data(self):
+        """
+        Return the raw compressed data.
+        """
+        return self._data[: self.compressed_size]
+
+    @property
+    def uncompressed_data(self):
+        """
+        Return the uncompressed data.
+        """
+        if hasattr(self, "_uncompressed_data"):
+            return self._uncompressed_data
+        data = self.compressed_data
+        if self.compress == JAR_STORED:
+            data = data.tobytes()
+        elif self.compress == JAR_DEFLATED:
+            data = zlib.decompress(data.tobytes(), -MAX_WBITS)
+        else:
+            assert False  # Can't be another value per __init__
+        if len(data) != self.uncompressed_size:
+            raise JarReaderError("Corrupted file? %s" % self.filename)
+        self._uncompressed_data = BytesIO(data)
+        return self._uncompressed_data
+
+
+class JarReader(object):
+    """
+    Class with methods to read Jar files. Can open standard jar files as well
+    as Mozilla jar files (see further details in the JarWriter documentation).
+    """
+
+    def __init__(self, file=None, fileobj=None, data=None):
+        """
+        Opens the given file as a Jar archive. Use the given file-like object
+        if one is given instead of opening the given file name.
+        """
+        if fileobj:
+            data = fileobj.read()
+        elif file:
+            data = open(file, "rb").read()
+        self._data = memoryview(data)
+        # The End of Central Directory Record has a variable size because of
+        # comments it may contain, so scan for it from the end of the file.
+        offset = -CDIR_END_SIZE
+        while True:
+            signature = JarStruct.get_data("uint32", self._data[offset:])[0]
+            if signature == JarCdirEnd.MAGIC:
+                break
+            if offset == -len(self._data):
+                raise JarReaderError("Not a jar?")
+            offset -= 1
+        self._cdir_end = JarCdirEnd(self._data[offset:])
+
+    def close(self):
+        """
+        Free some resources associated with the Jar.
+        """
+        del self._data
+
+    @property
+    def compression(self):
+        entries = self.entries
+        if not entries:
+            return JAR_STORED
+        return max(f["compression"] for f in six.itervalues(entries))
+
+    @property
+    def entries(self):
+        """
+        Return an ordered dict of central directory entries, indexed by
+        filename, in the order they appear in the Jar archive central
+        directory. Directory entries are skipped.
+        """
+        if hasattr(self, "_entries"):
+            return self._entries
+        preload = 0
+        if self.is_optimized:
+            preload = JarStruct.get_data("uint32", self._data)[0]
+        entries = OrderedDict()
+        offset = self._cdir_end["cdir_offset"]
+        for e in six.moves.xrange(self._cdir_end["cdir_entries"]):
+            entry = JarCdirEntry(self._data[offset:])
+            offset += entry.size
+            # Creator host system. 0 is MSDOS, 3 is Unix
+            host = entry["creator_version"] >> 8
+            # External attributes values depend on host above. On Unix the
+            # higher bits are the stat.st_mode value. On MSDOS, the lower bits
+            # are the FAT attributes.
+            xattr = entry["external_attr"]
+            # Skip directories
+            if (host == 0 and xattr & 0x10) or (host == 3 and xattr & (0o040000 << 16)):
+                continue
+            entries[six.ensure_text(entry["filename"])] = entry
+            if entry["offset"] < preload:
+                self._last_preloaded = six.ensure_text(entry["filename"])
+        self._entries = entries
+        return entries
+
+    @property
+    def is_optimized(self):
+        """
+        Return whether the jar archive is optimized.
+        """
+        # In optimized jars, the central directory is at the beginning of the
+        # file, after a single 32-bits value, which is the length of data
+        # preloaded.
+        return self._cdir_end["cdir_offset"] == JarStruct.TYPE_MAPPING["uint32"][1]
+
+    @property
+    def last_preloaded(self):
+        """
+        Return the name of the last file that is set to be preloaded.
+        See JarWriter documentation for more details on preloading.
+        """
+        if hasattr(self, "_last_preloaded"):
+            return self._last_preloaded
+        self._last_preloaded = None
+        self.entries
+        return self._last_preloaded
+
+    def _getreader(self, entry):
+        """
+        Helper to create a JarFileReader corresponding to the given central
+        directory entry.
+        """
+        header = JarLocalFileHeader(self._data[entry["offset"] :])
+        for key, value in entry:
+            if key in header and header[key] != value:
+                raise JarReaderError(
+                    "Central directory and file header "
+                    + "mismatch. Corrupted archive?"
+                )
+        return JarFileReader(header, self._data[entry["offset"] + header.size :])
+
+    def __iter__(self):
+        """
+        Iterate over all files in the Jar archive, in the form of
+        JarFileReaders.
+            for file in jarReader:
+                ...
+        """
+        for entry in six.itervalues(self.entries):
+            yield self._getreader(entry)
+
+    def __getitem__(self, name):
+        """
+        Get a JarFileReader for the given file name.
+        """
+        return self._getreader(self.entries[name])
+
+    def __contains__(self, name):
+        """
+        Return whether the given file name appears in the Jar archive.
+        """
+        return name in self.entries
+
+
+class JarWriter(object):
+    """
+    Class with methods to write Jar files. Can write more-or-less standard jar
+    archives as well as jar archives optimized for Gecko. See the documentation
+    for the close() member function for a description of both layouts.
+    """
+
+    def __init__(self, file=None, fileobj=None, compress=True, compress_level=9):
+        """
+        Initialize a Jar archive in the given file. Use the given file-like
+        object if one is given instead of opening the given file name.
+        The compress option determines the default behavior for storing data
+        in the jar archive. The optimize options determines whether the jar
+        archive should be optimized for Gecko or not. ``compress_level``
+        defines the zlib compression level. It must be a value between 0 and 9
+        and defaults to 9, the highest and slowest level of compression.
+        """
+        if fileobj:
+            self._data = fileobj
+        else:
+            self._data = open(file, "wb")
+        if compress is True:
+            compress = JAR_DEFLATED
+        self._compress = compress
+        self._compress_level = compress_level
+        self._contents = OrderedDict()
+        self._last_preloaded = None
+
+    def __enter__(self):
+        """
+        Context manager __enter__ method for JarWriter.
+        """
+        return self
+
+    def __exit__(self, type, value, tb):
+        """
+        Context manager __exit__ method for JarWriter.
+        """
+        self.finish()
+
+    def finish(self):
+        """
+        Flush and close the Jar archive.
+
+        Standard jar archives are laid out like the following:
+            - Local file header 1
+            - File data 1
+            - Local file header 2
+            - File data 2
+            - (...)
+            - Central directory entry pointing at Local file header 1
+            - Central directory entry pointing at Local file header 2
+            - (...)
+            - End of central directory, pointing at first central directory
+              entry.
+
+        Jar archives optimized for Gecko are laid out like the following:
+            - 32-bits unsigned integer giving the amount of data to preload.
+            - Central directory entry pointing at Local file header 1
+            - Central directory entry pointing at Local file header 2
+            - (...)
+            - End of central directory, pointing at first central directory
+              entry.
+            - Local file header 1
+            - File data 1
+            - Local file header 2
+            - File data 2
+            - (...)
+            - End of central directory, pointing at first central directory
+              entry.
+
+        The duplication of the End of central directory is to accomodate some
+        Zip reading tools that want an end of central directory structure to
+        follow the central directory entries.
+        """
+        offset = 0
+        headers = {}
+        preload_size = 0
+        # Prepare central directory entries
+        for entry, content in six.itervalues(self._contents):
+            header = JarLocalFileHeader()
+            for name in entry.STRUCT:
+                if name in header:
+                    header[name] = entry[name]
+            entry["offset"] = offset
+            offset += len(content) + header.size
+            if six.ensure_text(entry["filename"]) == self._last_preloaded:
+                preload_size = offset
+            headers[entry] = header
+        # Prepare end of central directory
+        end = JarCdirEnd()
+        end["disk_entries"] = len(self._contents)
+        end["cdir_entries"] = end["disk_entries"]
+        end["cdir_size"] = six.moves.reduce(
+            lambda x, y: x + y[0].size, self._contents.values(), 0
+        )
+        # On optimized archives, store the preloaded size and the central
+        # directory entries, followed by the first end of central directory.
+        if preload_size:
+            end["cdir_offset"] = 4
+            offset = end["cdir_size"] + end["cdir_offset"] + end.size
+            preload_size += offset
+            self._data.write(struct.pack("<I", preload_size))
+            for entry, _ in six.itervalues(self._contents):
+                entry["offset"] += offset
+                self._data.write(entry.serialize())
+            self._data.write(end.serialize())
+        # Store local file entries followed by compressed data
+        for entry, content in six.itervalues(self._contents):
+            self._data.write(headers[entry].serialize())
+            if isinstance(content, memoryview):
+                self._data.write(content.tobytes())
+            else:
+                self._data.write(content)
+        # On non optimized archives, store the central directory entries.
+        if not preload_size:
+            end["cdir_offset"] = offset
+            for entry, _ in six.itervalues(self._contents):
+                self._data.write(entry.serialize())
+        # Store the end of central directory.
+        self._data.write(end.serialize())
+        self._data.close()
+
+    def add(self, name, data, compress=None, mode=None, skip_duplicates=False):
+        """
+        Add a new member to the jar archive, with the given name and the given
+        data.
+        The compress option indicates how the given data should be compressed
+        (one of JAR_STORED or JAR_DEFLATE), or compressed according
+        to the default defined when creating the JarWriter (None). True and
+        False are allowed values for backwards compatibility, mapping,
+        respectively, to JAR_DEFLATE and JAR_STORED.
+        When the data should be compressed, it is only really compressed if
+        the compressed size is smaller than the uncompressed size.
+        The mode option gives the unix permissions that should be stored for the
+        jar entry, which defaults to 0o100644 (regular file, u+rw, g+r, o+r) if
+        not specified.
+        If a duplicated member is found skip_duplicates will prevent raising
+        an exception if set to True.
+        The given data may be a buffer, a file-like instance, a Deflater or a
+        JarFileReader instance. The latter two allow to avoid uncompressing
+        data to recompress it.
+        """
+        name = mozpath.normsep(six.ensure_text(name))
+
+        if name in self._contents and not skip_duplicates:
+            raise JarWriterError("File %s already in JarWriter" % name)
+        if compress is None:
+            compress = self._compress
+        if compress is True:
+            compress = JAR_DEFLATED
+        if compress is False:
+            compress = JAR_STORED
+        if isinstance(data, (JarFileReader, Deflater)) and data.compress == compress:
+            deflater = data
+        else:
+            deflater = Deflater(compress, compress_level=self._compress_level)
+            if isinstance(data, (six.binary_type, six.string_types)):
+                deflater.write(data)
+            elif hasattr(data, "read"):
+                try:
+                    data.seek(0)
+                except (UnsupportedOperation, AttributeError):
+                    pass
+                deflater.write(data.read())
+            else:
+                raise JarWriterError("Don't know how to handle %s" % type(data))
+        # Fill a central directory entry for this new member.
+        entry = JarCdirEntry()
+        entry["creator_version"] = 20
+        if mode is None:
+            # If no mode is given, default to u+rw, g+r, o+r.
+            mode = 0o000644
+        if not mode & 0o777000:
+            # If no file type is given, default to regular file.
+            mode |= 0o100000
+        # Set creator host system (upper byte of creator_version) to 3 (Unix) so
+        # mode is honored when there is one.
+        entry["creator_version"] |= 3 << 8
+        entry["external_attr"] = (mode & 0xFFFF) << 16
+        if deflater.compressed:
+            entry["min_version"] = 20  # Version 2.0 supports deflated streams
+            entry["general_flag"] = 2  # Max compression
+            entry["compression"] = deflater.compress
+        else:
+            entry["min_version"] = 10  # Version 1.0 for stored streams
+            entry["general_flag"] = 0
+            entry["compression"] = JAR_STORED
+        # January 1st, 2010. See bug 592369.
+        entry["lastmod_date"] = ((2010 - 1980) << 9) | (1 << 5) | 1
+        entry["lastmod_time"] = 0
+        entry["crc32"] = deflater.crc32
+        entry["compressed_size"] = deflater.compressed_size
+        entry["uncompressed_size"] = deflater.uncompressed_size
+        entry["filename"] = six.ensure_binary(name)
+        self._contents[name] = entry, deflater.compressed_data
+
+    def preload(self, files):
+        """
+        Set which members of the jar archive should be preloaded when opening
+        the archive in Gecko. This reorders the members according to the order
+        of given list.
+        """
+        new_contents = OrderedDict()
+        for f in files:
+            if f not in self._contents:
+                continue
+            new_contents[f] = self._contents[f]
+            self._last_preloaded = f
+        for f in self._contents:
+            if f not in new_contents:
+                new_contents[f] = self._contents[f]
+        self._contents = new_contents
+
+
+class Deflater(object):
+    """
+    File-like interface to zlib compression. The data is actually not
+    compressed unless the compressed form is smaller than the uncompressed
+    data.
+    """
+
+    def __init__(self, compress=True, compress_level=9):
+        """
+        Initialize a Deflater. The compress argument determines how to
+        compress.
+        """
+        self._data = BytesIO()
+        if compress is True:
+            compress = JAR_DEFLATED
+        elif compress is False:
+            compress = JAR_STORED
+        self.compress = compress
+        if compress == JAR_DEFLATED:
+            self._deflater = zlib.compressobj(compress_level, zlib.DEFLATED, -MAX_WBITS)
+            self._deflated = BytesIO()
+        else:
+            assert compress == JAR_STORED
+            self._deflater = None
+        self.crc32 = 0
+
+    def write(self, data):
+        """
+        Append a buffer to the Deflater.
+        """
+        if isinstance(data, memoryview):
+            data = data.tobytes()
+        data = six.ensure_binary(data)
+        self._data.write(data)
+
+        if self.compress:
+            if self._deflater:
+                self._deflated.write(self._deflater.compress(data))
+            else:
+                raise JarWriterError("Can't write after flush")
+
+        self.crc32 = zlib.crc32(data, self.crc32) & 0xFFFFFFFF
+
+    def close(self):
+        """
+        Close the Deflater.
+        """
+        self._data.close()
+        if self.compress:
+            self._deflated.close()
+
+    def _flush(self):
+        """
+        Flush the underlying zlib compression object.
+        """
+        if self.compress and self._deflater:
+            self._deflated.write(self._deflater.flush())
+            self._deflater = None
+
+    @property
+    def compressed(self):
+        """
+        Return whether the data should be compressed.
+        """
+        return self._compressed_size < self.uncompressed_size
+
+    @property
+    def _compressed_size(self):
+        """
+        Return the real compressed size of the data written to the Deflater. If
+        the Deflater is set not to compress, the uncompressed size is returned.
+        Otherwise, the actual compressed size is returned, whether or not it is
+        a win over the uncompressed size.
+        """
+        if self.compress:
+            self._flush()
+            return self._deflated.tell()
+        return self.uncompressed_size
+
+    @property
+    def compressed_size(self):
+        """
+        Return the compressed size of the data written to the Deflater. If the
+        Deflater is set not to compress, the uncompressed size is returned.
+        Otherwise, if the data should not be compressed (the real compressed
+        size is bigger than the uncompressed size), return the uncompressed
+        size.
+        """
+        if self.compressed:
+            return self._compressed_size
+        return self.uncompressed_size
+
+    @property
+    def uncompressed_size(self):
+        """
+        Return the size of the data written to the Deflater.
+        """
+        return self._data.tell()
+
+    @property
+    def compressed_data(self):
+        """
+        Return the compressed data, if the data should be compressed (real
+        compressed size smaller than the uncompressed size), or the
+        uncompressed data otherwise.
+        """
+        if self.compressed:
+            return self._deflated.getvalue()
+        return self._data.getvalue()
+
+
+class JarLog(dict):
+    """
+    Helper to read the file Gecko generates when setting MOZ_JAR_LOG_FILE.
+    The jar log is then available as a dict with the jar path as key, and
+    the corresponding access log as a list value. Only the first access to
+    a given member of a jar is stored.
+    """
+
+    def __init__(self, file=None, fileobj=None):
+        if not fileobj:
+            fileobj = open(file, "r")
+        for line in fileobj:
+            jar, path = line.strip().split(None, 1)
+            if not jar or not path:
+                continue
+            entry = self.setdefault(jar, [])
+            if path not in entry:
+                entry.append(path)
diff --git a/python/mozbuild/mozpack/packager/__init__.py b/python/mozbuild/mozpack/packager/__init__.py
new file mode 100644
index 0000000000..a2f763c855
--- /dev/null
+++ b/python/mozbuild/mozpack/packager/__init__.py
@@ -0,0 +1,445 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import codecs
+import json
+import os
+import re
+from collections import deque
+
+import six
+
+import mozpack.path as mozpath
+from mozbuild.preprocessor import Preprocessor
+from mozpack.chrome.manifest import (
+    Manifest,
+    ManifestBinaryComponent,
+    ManifestChrome,
+    ManifestInterfaces,
+    is_manifest,
+    parse_manifest,
+)
+from mozpack.errors import errors
+
+
+class Component(object):
+    """
+    Class that represents a component in a package manifest.
+    """
+
+    def __init__(self, name, destdir=""):
+        if name.find(" ") > 0:
+            errors.fatal('Malformed manifest: space in component name "%s"' % name)
+        self._name = name
+        self._destdir = destdir
+
+    def __repr__(self):
+        s = self.name
+        if self.destdir:
+            s += ' destdir="%s"' % self.destdir
+        return s
+
+    @property
+    def name(self):
+        return self._name
+
+    @property
+    def destdir(self):
+        return self._destdir
+
+    @staticmethod
+    def _triples(lst):
+        """
+        Split [1, 2, 3, 4, 5, 6, 7] into [(1, 2, 3), (4, 5, 6)].
+        """
+        return zip(*[iter(lst)] * 3)
+
+    KEY_VALUE_RE = re.compile(
+        r"""
+        \s*                 # optional whitespace.
+        ([a-zA-Z0-9_]+)     # key.
+        \s*=\s*             # optional space around =.
+        "([^"]*)"           # value without surrounding quotes.
+        (?:\s+|$)
+        """,
+        re.VERBOSE,
+    )
+
+    @staticmethod
+    def _split_options(string):
+        """
+        Split 'key1="value1" key2="value2"' into
+        {'key1':'value1', 'key2':'value2'}.
+
+        Returned keys and values are all strings.
+
+        Throws ValueError if the input is malformed.
+        """
+        options = {}
+        splits = Component.KEY_VALUE_RE.split(string)
+        if len(splits) % 3 != 1:
+            # This should never happen -- we expect to always split
+            # into ['', ('key', 'val', '')*].
+            raise ValueError("Bad input")
+        if splits[0]:
+            raise ValueError("Unrecognized input " + splits[0])
+        for key, val, no_match in Component._triples(splits[1:]):
+            if no_match:
+                raise ValueError("Unrecognized input " + no_match)
+            options[key] = val
+        return options
+
+    @staticmethod
+    def _split_component_and_options(string):
+        """
+        Split 'name key1="value1" key2="value2"' into
+        ('name', {'key1':'value1', 'key2':'value2'}).
+
+        Returned name, keys and values are all strings.
+
+        Raises ValueError if the input is malformed.
+        """
+        splits = string.strip().split(None, 1)
+        if not splits:
+            raise ValueError("No component found")
+        component = splits[0].strip()
+        if not component:
+            raise ValueError("No component found")
+        if not re.match("[a-zA-Z0-9_-]+$", component):
+            raise ValueError("Bad component name " + component)
+        options = Component._split_options(splits[1]) if len(splits) > 1 else {}
+        return component, options
+
+    @staticmethod
+    def from_string(string):
+        """
+        Create a component from a string.
+        """
+        try:
+            name, options = Component._split_component_and_options(string)
+        except ValueError as e:
+            errors.fatal("Malformed manifest: %s" % e)
+            return
+        destdir = options.pop("destdir", "")
+        if options:
+            errors.fatal(
+                "Malformed manifest: options %s not recognized" % options.keys()
+            )
+        return Component(name, destdir=destdir)
+
+
+class PackageManifestParser(object):
+    """
+    Class for parsing of a package manifest, after preprocessing.
+
+    A package manifest is a list of file paths, with some syntaxic sugar:
+        [] designates a toplevel component. Example: [xpcom]
+        - in front of a file specifies it to be removed
+        * wildcard support
+        ** expands to all files and zero or more directories
+        ; file comment
+
+    The parser takes input from the preprocessor line by line, and pushes
+    parsed information to a sink object.
+
+    The add and remove methods of the sink object are called with the
+    current Component instance and a path.
+    """
+
+    def __init__(self, sink):
+        """
+        Initialize the package manifest parser with the given sink.
+        """
+        self._component = Component("")
+        self._sink = sink
+
+    def handle_line(self, str):
+        """
+        Handle a line of input and push the parsed information to the sink
+        object.
+        """
+        # Remove comments.
+        str = str.strip()
+        if not str or str.startswith(";"):
+            return
+        if str.startswith("[") and str.endswith("]"):
+            self._component = Component.from_string(str[1:-1])
+        elif str.startswith("-"):
+            str = str[1:]
+            self._sink.remove(self._component, str)
+        elif "," in str:
+            errors.fatal("Incompatible syntax")
+        else:
+            self._sink.add(self._component, str)
+
+
+class PreprocessorOutputWrapper(object):
+    """
+    File-like helper to handle the preprocessor output and send it to a parser.
+    The parser's handle_line method is called in the relevant errors.context.
+    """
+
+    def __init__(self, preprocessor, parser):
+        self._parser = parser
+        self._pp = preprocessor
+
+    def write(self, str):
+        with errors.context(self._pp.context["FILE"], self._pp.context["LINE"]):
+            self._parser.handle_line(str)
+
+
+def preprocess(input, parser, defines={}):
+    """
+    Preprocess the file-like input with the given defines, and send the
+    preprocessed output line by line to the given parser.
+    """
+    pp = Preprocessor()
+    pp.context.update(defines)
+    pp.do_filter("substitution")
+    pp.out = PreprocessorOutputWrapper(pp, parser)
+    pp.do_include(input)
+
+
+def preprocess_manifest(sink, manifest, defines={}):
+    """
+    Preprocess the given file-like manifest with the given defines, and push
+    the parsed information to a sink. See PackageManifestParser documentation
+    for more details on the sink.
+    """
+    preprocess(manifest, PackageManifestParser(sink), defines)
+
+
+class CallDeque(deque):
+    """
+    Queue of function calls to make.
+    """
+
+    def append(self, function, *args):
+        deque.append(self, (errors.get_context(), function, args))
+
+    def execute(self):
+        while True:
+            try:
+                context, function, args = self.popleft()
+            except IndexError:
+                return
+            if context:
+                with errors.context(context[0], context[1]):
+                    function(*args)
+            else:
+                function(*args)
+
+
+class SimplePackager(object):
+    """
+    Helper used to translate and buffer instructions from the
+    SimpleManifestSink to a formatter. Formatters expect some information to be
+    given first that the simple manifest contents can't guarantee before the
+    end of the input.
+    """
+
+    def __init__(self, formatter):
+        self.formatter = formatter
+        # Queue for formatter.add_interfaces()/add_manifest() calls.
+        self._queue = CallDeque()
+        # Queue for formatter.add_manifest() calls for ManifestChrome.
+        self._chrome_queue = CallDeque()
+        # Queue for formatter.add() calls.
+        self._file_queue = CallDeque()
+        # All paths containing addons. (key is path, value is whether it
+        # should be packed or unpacked)
+        self._addons = {}
+        # All manifest paths imported.
+        self._manifests = set()
+        # All manifest paths included from some other manifest.
+        self._included_manifests = {}
+        self._closed = False
+
+    # Parsing RDF is complex, and would require an external library to do
+    # properly. Just go with some hackish but probably sufficient regexp
+    UNPACK_ADDON_RE = re.compile(
+        r"""(?:
+        <em:unpack>true</em:unpack>
+        |em:unpack=(?P<quote>["']?)true(?P=quote)
+    )""",
+        re.VERBOSE,
+    )
+
+    def add(self, path, file):
+        """
+        Add the given BaseFile instance with the given path.
+        """
+        assert not self._closed
+        if is_manifest(path):
+            self._add_manifest_file(path, file)
+        elif path.endswith(".xpt"):
+            self._queue.append(self.formatter.add_interfaces, path, file)
+        else:
+            self._file_queue.append(self.formatter.add, path, file)
+            if mozpath.basename(path) == "install.rdf":
+                addon = True
+                install_rdf = six.ensure_text(file.open().read())
+                if self.UNPACK_ADDON_RE.search(install_rdf):
+                    addon = "unpacked"
+                self._add_addon(mozpath.dirname(path), addon)
+            elif mozpath.basename(path) == "manifest.json":
+                manifest = six.ensure_text(file.open().read())
+                try:
+                    parsed = json.loads(manifest)
+                except ValueError:
+                    pass
+                if isinstance(parsed, dict) and "manifest_version" in parsed:
+                    self._add_addon(mozpath.dirname(path), True)
+
+    def _add_addon(self, path, addon_type):
+        """
+        Add the given BaseFile to the collection of addons if a parent
+        directory is not already in the collection.
+        """
+        if mozpath.basedir(path, self._addons) is not None:
+            return
+
+        for dir in self._addons:
+            if mozpath.basedir(dir, [path]) is not None:
+                del self._addons[dir]
+                break
+
+        self._addons[path] = addon_type
+
+    def _add_manifest_file(self, path, file):
+        """
+        Add the given BaseFile with manifest file contents with the given path.
+        """
+        self._manifests.add(path)
+        base = ""
+        if hasattr(file, "path"):
+            # Find the directory the given path is relative to.
+            b = mozpath.normsep(file.path)
+            if b.endswith("/" + path) or b == path:
+                base = os.path.normpath(b[: -len(path)])
+        for e in parse_manifest(base, path, codecs.getreader("utf-8")(file.open())):
+            # ManifestResources need to be given after ManifestChrome, so just
+            # put all ManifestChrome in a separate queue to make them first.
+            if isinstance(e, ManifestChrome):
+                # e.move(e.base) just returns a clone of the entry.
+                self._chrome_queue.append(self.formatter.add_manifest, e.move(e.base))
+            elif not isinstance(e, (Manifest, ManifestInterfaces)):
+                self._queue.append(self.formatter.add_manifest, e.move(e.base))
+            # If a binary component is added to an addon, prevent the addon
+            # from being packed.
+            if isinstance(e, ManifestBinaryComponent):
+                addon = mozpath.basedir(e.base, self._addons)
+                if addon:
+                    self._addons[addon] = "unpacked"
+            if isinstance(e, Manifest):
+                if e.flags:
+                    errors.fatal("Flags are not supported on " + '"manifest" entries')
+                self._included_manifests[e.path] = path
+
+    def get_bases(self, addons=True):
+        """
+        Return all paths under which root manifests have been found. Root
+        manifests are manifests that are included in no other manifest.
+        `addons` indicates whether to include addon bases as well.
+        """
+        all_bases = set(
+            mozpath.dirname(m) for m in self._manifests - set(self._included_manifests)
+        )
+        if not addons:
+            all_bases -= set(self._addons)
+        else:
+            # If for some reason some detected addon doesn't have a
+            # non-included manifest.
+            all_bases |= set(self._addons)
+        return all_bases
+
+    def close(self):
+        """
+        Push all instructions to the formatter.
+        """
+        self._closed = True
+
+        bases = self.get_bases()
+        broken_bases = sorted(
+            m
+            for m, includer in six.iteritems(self._included_manifests)
+            if mozpath.basedir(m, bases) != mozpath.basedir(includer, bases)
+        )
+        for m in broken_bases:
+            errors.fatal(
+                '"%s" is included from "%s", which is outside "%s"'
+                % (m, self._included_manifests[m], mozpath.basedir(m, bases))
+            )
+        for base in sorted(bases):
+            self.formatter.add_base(base, self._addons.get(base, False))
+        self._chrome_queue.execute()
+        self._queue.execute()
+        self._file_queue.execute()
+
+
+class SimpleManifestSink(object):
+    """
+    Parser sink for "simple" package manifests. Simple package manifests use
+    the format described in the PackageManifestParser documentation, but don't
+    support file removals, and require manifests, interfaces and chrome data to
+    be explicitely listed.
+    Entries starting with bin/ are searched under bin/ in the FileFinder, but
+    are packaged without the bin/ prefix.
+    """
+
+    def __init__(self, finder, formatter):
+        """
+        Initialize the SimpleManifestSink. The given FileFinder is used to
+        get files matching the patterns given in the manifest. The given
+        formatter does the packaging job.
+        """
+        self._finder = finder
+        self.packager = SimplePackager(formatter)
+        self._closed = False
+        self._manifests = set()
+
+    @staticmethod
+    def normalize_path(path):
+        """
+        Remove any bin/ prefix.
+        """
+        if mozpath.basedir(path, ["bin"]) == "bin":
+            return mozpath.relpath(path, "bin")
+        return path
+
+    def add(self, component, pattern):
+        """
+        Add files with the given pattern in the given component.
+        """
+        assert not self._closed
+        added = False
+        for p, f in self._finder.find(pattern):
+            added = True
+            if is_manifest(p):
+                self._manifests.add(p)
+            dest = mozpath.join(component.destdir, SimpleManifestSink.normalize_path(p))
+            self.packager.add(dest, f)
+        if not added:
+            errors.error("Missing file(s): %s" % pattern)
+
+    def remove(self, component, pattern):
+        """
+        Remove files with the given pattern in the given component.
+        """
+        assert not self._closed
+        errors.fatal("Removal is unsupported")
+
+    def close(self, auto_root_manifest=True):
+        """
+        Add possibly missing bits and push all instructions to the formatter.
+        """
+        if auto_root_manifest:
+            # Simple package manifests don't contain the root manifests, so
+            # find and add them.
+            paths = [mozpath.dirname(m) for m in self._manifests]
+            path = mozpath.dirname(mozpath.commonprefix(paths))
+            for p, f in self._finder.find(mozpath.join(path, "chrome.manifest")):
+                if p not in self._manifests:
+                    self.packager.add(SimpleManifestSink.normalize_path(p), f)
+        self.packager.close()
diff --git a/python/mozbuild/mozpack/packager/formats.py b/python/mozbuild/mozpack/packager/formats.py
new file mode 100644
index 0000000000..95a6dee2f6
--- /dev/null
+++ b/python/mozbuild/mozpack/packager/formats.py
@@ -0,0 +1,354 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from six.moves.urllib.parse import urlparse
+
+import mozpack.path as mozpath
+from mozpack.chrome.manifest import (
+    Manifest,
+    ManifestBinaryComponent,
+    ManifestChrome,
+    ManifestInterfaces,
+    ManifestMultiContent,
+    ManifestResource,
+)
+from mozpack.copier import FileRegistry, FileRegistrySubtree, Jarrer
+from mozpack.errors import errors
+from mozpack.files import ManifestFile
+
+"""
+Formatters are classes receiving packaging instructions and creating the
+appropriate package layout.
+
+There are three distinct formatters, each handling one of the different chrome
+formats:
+    - flat: essentially, copies files from the source with the same file system
+      layout. Manifests entries are grouped in a single manifest per directory,
+      as well as XPT interfaces.
+    - jar: chrome content is packaged in jar files.
+    - omni: chrome content, modules, non-binary components, and many other
+      elements are packaged in an omnijar file for each base directory.
+
+The base interface provides the following methods:
+    - add_base(path [, addon])
+        Register a base directory for an application or GRE, or an addon.
+        Base directories usually contain a root manifest (manifests not
+        included in any other manifest) named chrome.manifest.
+        The optional addon argument tells whether the base directory
+        is that of a packed addon (True), unpacked addon ('unpacked') or
+        otherwise (False).
+        The method may only be called in sorted order of `path` (alphanumeric
+        order, parents before children).
+    - add(path, content)
+        Add the given content (BaseFile instance) at the given virtual path
+    - add_interfaces(path, content)
+        Add the given content (BaseFile instance) as an interface. Equivalent
+        to add(path, content) with the right add_manifest().
+    - add_manifest(entry)
+        Add a ManifestEntry.
+    - contains(path)
+        Returns whether the given virtual path is known of the formatter.
+
+The virtual paths mentioned above are paths as they would be with a flat
+chrome.
+
+Formatters all take a FileCopier instance they will fill with the packaged
+data.
+"""
+
+
+class PiecemealFormatter(object):
+    """
+    Generic formatter that dispatches across different sub-formatters
+    according to paths.
+    """
+
+    def __init__(self, copier):
+        assert isinstance(copier, (FileRegistry, FileRegistrySubtree))
+        self.copier = copier
+        self._sub_formatter = {}
+        self._frozen_bases = False
+
+    def add_base(self, base, addon=False):
+        # Only allow to add a base directory before calls to _get_base()
+        assert not self._frozen_bases
+        assert base not in self._sub_formatter
+        assert all(base > b for b in self._sub_formatter)
+        self._add_base(base, addon)
+
+    def _get_base(self, path):
+        """
+        Return the deepest base directory containing the given path.
+        """
+        self._frozen_bases = True
+        base = mozpath.basedir(path, self._sub_formatter.keys())
+        relpath = mozpath.relpath(path, base) if base else path
+        return base, relpath
+
+    def add(self, path, content):
+        base, relpath = self._get_base(path)
+        if base is None:
+            return self.copier.add(relpath, content)
+        return self._sub_formatter[base].add(relpath, content)
+
+    def add_manifest(self, entry):
+        base, relpath = self._get_base(entry.base)
+        assert base is not None
+        return self._sub_formatter[base].add_manifest(entry.move(relpath))
+
+    def add_interfaces(self, path, content):
+        base, relpath = self._get_base(path)
+        assert base is not None
+        return self._sub_formatter[base].add_interfaces(relpath, content)
+
+    def contains(self, path):
+        assert "*" not in path
+        base, relpath = self._get_base(path)
+        if base is None:
+            return self.copier.contains(relpath)
+        return self._sub_formatter[base].contains(relpath)
+
+
+class FlatFormatter(PiecemealFormatter):
+    """
+    Formatter for the flat package format.
+    """
+
+    def _add_base(self, base, addon=False):
+        self._sub_formatter[base] = FlatSubFormatter(
+            FileRegistrySubtree(base, self.copier)
+        )
+
+
+class FlatSubFormatter(object):
+    """
+    Sub-formatter for the flat package format.
+    """
+
+    def __init__(self, copier):
+        assert isinstance(copier, (FileRegistry, FileRegistrySubtree))
+        self.copier = copier
+        self._chrome_db = {}
+
+    def add(self, path, content):
+        self.copier.add(path, content)
+
+    def add_manifest(self, entry):
+        # Store manifest entries in a single manifest per directory, named
+        # after their parent directory, except for root manifests, all named
+        # chrome.manifest.
+        if entry.base:
+            name = mozpath.basename(entry.base)
+        else:
+            name = "chrome"
+        path = mozpath.normpath(mozpath.join(entry.base, "%s.manifest" % name))
+        if not self.copier.contains(path):
+            # Add a reference to the manifest file in the parent manifest, if
+            # the manifest file is not a root manifest.
+            if entry.base:
+                parent = mozpath.dirname(entry.base)
+                relbase = mozpath.basename(entry.base)
+                relpath = mozpath.join(relbase, mozpath.basename(path))
+                self.add_manifest(Manifest(parent, relpath))
+            self.copier.add(path, ManifestFile(entry.base))
+
+        if isinstance(entry, ManifestChrome):
+            data = self._chrome_db.setdefault(entry.name, {})
+            if isinstance(entry, ManifestMultiContent):
+                entries = data.setdefault(entry.type, {}).setdefault(entry.id, [])
+            else:
+                entries = data.setdefault(entry.type, [])
+            for e in entries:
+                # Ideally, we'd actually check whether entry.flags are more
+                # specific than e.flags, but in practice the following test
+                # is enough for now.
+                if entry == e:
+                    errors.warn('"%s" is duplicated. Skipping.' % entry)
+                    return
+                if not entry.flags or e.flags and entry.flags == e.flags:
+                    errors.fatal('"%s" overrides "%s"' % (entry, e))
+            entries.append(entry)
+
+        self.copier[path].add(entry)
+
+    def add_interfaces(self, path, content):
+        self.copier.add(path, content)
+        self.add_manifest(
+            ManifestInterfaces(mozpath.dirname(path), mozpath.basename(path))
+        )
+
+    def contains(self, path):
+        assert "*" not in path
+        return self.copier.contains(path)
+
+
+class JarFormatter(PiecemealFormatter):
+    """
+    Formatter for the jar package format. Assumes manifest entries related to
+    chrome are registered before the chrome data files are added. Also assumes
+    manifest entries for resources are registered after chrome manifest
+    entries.
+    """
+
+    def __init__(self, copier, compress=True):
+        PiecemealFormatter.__init__(self, copier)
+        self._compress = compress
+
+    def _add_base(self, base, addon=False):
+        if addon is True:
+            jarrer = Jarrer(self._compress)
+            self.copier.add(base + ".xpi", jarrer)
+            self._sub_formatter[base] = FlatSubFormatter(jarrer)
+        else:
+            self._sub_formatter[base] = JarSubFormatter(
+                FileRegistrySubtree(base, self.copier), self._compress
+            )
+
+
+class JarSubFormatter(PiecemealFormatter):
+    """
+    Sub-formatter for the jar package format. It is a PiecemealFormatter that
+    dispatches between further sub-formatter for each of the jar files it
+    dispatches the chrome data to, and a FlatSubFormatter for the non-chrome
+    files.
+    """
+
+    def __init__(self, copier, compress=True):
+        PiecemealFormatter.__init__(self, copier)
+        self._frozen_chrome = False
+        self._compress = compress
+        self._sub_formatter[""] = FlatSubFormatter(copier)
+
+    def _jarize(self, entry, relpath):
+        """
+        Transform a manifest entry in one pointing to chrome data in a jar.
+        Return the corresponding chrome path and the new entry.
+        """
+        base = entry.base
+        basepath = mozpath.split(relpath)[0]
+        chromepath = mozpath.join(base, basepath)
+        entry = (
+            entry.rebase(chromepath)
+            .move(mozpath.join(base, "jar:%s.jar!" % basepath))
+            .rebase(base)
+        )
+        return chromepath, entry
+
+    def add_manifest(self, entry):
+        if isinstance(entry, ManifestChrome) and not urlparse(entry.relpath).scheme:
+            chromepath, entry = self._jarize(entry, entry.relpath)
+            assert not self._frozen_chrome
+            if chromepath not in self._sub_formatter:
+                jarrer = Jarrer(self._compress)
+                self.copier.add(chromepath + ".jar", jarrer)
+                self._sub_formatter[chromepath] = FlatSubFormatter(jarrer)
+        elif isinstance(entry, ManifestResource) and not urlparse(entry.target).scheme:
+            chromepath, new_entry = self._jarize(entry, entry.target)
+            if chromepath in self._sub_formatter:
+                entry = new_entry
+        PiecemealFormatter.add_manifest(self, entry)
+
+
+class OmniJarFormatter(JarFormatter):
+    """
+    Formatter for the omnijar package format.
+    """
+
+    def __init__(self, copier, omnijar_name, compress=True, non_resources=()):
+        JarFormatter.__init__(self, copier, compress)
+        self._omnijar_name = omnijar_name
+        self._non_resources = non_resources
+
+    def _add_base(self, base, addon=False):
+        if addon:
+            # Because add_base is always called with parents before children,
+            # all the possible ancestry of `base` is already present in
+            # `_sub_formatter`.
+            parent_base = mozpath.basedir(base, self._sub_formatter.keys())
+            rel_base = mozpath.relpath(base, parent_base)
+            # If the addon is under a resource directory, package it in the
+            # omnijar.
+            parent_sub_formatter = self._sub_formatter[parent_base]
+            if parent_sub_formatter.is_resource(rel_base):
+                omnijar_sub_formatter = parent_sub_formatter._sub_formatter[
+                    self._omnijar_name
+                ]
+                self._sub_formatter[base] = FlatSubFormatter(
+                    FileRegistrySubtree(rel_base, omnijar_sub_formatter.copier)
+                )
+                return
+            JarFormatter._add_base(self, base, addon)
+        else:
+            self._sub_formatter[base] = OmniJarSubFormatter(
+                FileRegistrySubtree(base, self.copier),
+                self._omnijar_name,
+                self._compress,
+                self._non_resources,
+            )
+
+
+class OmniJarSubFormatter(PiecemealFormatter):
+    """
+    Sub-formatter for the omnijar package format. It is a PiecemealFormatter
+    that dispatches between a FlatSubFormatter for the resources data and
+    another FlatSubFormatter for the other files.
+    """
+
+    def __init__(self, copier, omnijar_name, compress=True, non_resources=()):
+        PiecemealFormatter.__init__(self, copier)
+        self._omnijar_name = omnijar_name
+        self._compress = compress
+        self._non_resources = non_resources
+        self._sub_formatter[""] = FlatSubFormatter(copier)
+        jarrer = Jarrer(self._compress)
+        self._sub_formatter[omnijar_name] = FlatSubFormatter(jarrer)
+
+    def _get_base(self, path):
+        base = self._omnijar_name if self.is_resource(path) else ""
+        # Only add the omnijar file if something ends up in it.
+        if base and not self.copier.contains(base):
+            self.copier.add(base, self._sub_formatter[base].copier)
+        return base, path
+
+    def add_manifest(self, entry):
+        base = ""
+        if not isinstance(entry, ManifestBinaryComponent):
+            base = self._omnijar_name
+        formatter = self._sub_formatter[base]
+        return formatter.add_manifest(entry)
+
+    def is_resource(self, path):
+        """
+        Return whether the given path corresponds to a resource to be put in an
+        omnijar archive.
+        """
+        if any(mozpath.match(path, p.replace("*", "**")) for p in self._non_resources):
+            return False
+        path = mozpath.split(path)
+        if path[0] == "chrome":
+            return len(path) == 1 or path[1] != "icons"
+        if path[0] == "components":
+            return path[-1].endswith((".js", ".xpt"))
+        if path[0] == "res":
+            return len(path) == 1 or (
+                path[1] != "cursors"
+                and path[1] != "touchbar"
+                and path[1] != "MainMenu.nib"
+            )
+        if path[0] == "defaults":
+            return len(path) != 3 or not (
+                path[2] == "channel-prefs.js" and path[1] in ["pref", "preferences"]
+            )
+        if len(path) <= 2 and path[-1] == "greprefs.js":
+            # Accommodate `greprefs.js` and `$ANDROID_CPU_ARCH/greprefs.js`.
+            return True
+        return path[0] in [
+            "modules",
+            "actors",
+            "dictionaries",
+            "hyphenation",
+            "localization",
+            "update.locale",
+            "contentaccessible",
+        ]
diff --git a/python/mozbuild/mozpack/packager/l10n.py b/python/mozbuild/mozpack/packager/l10n.py
new file mode 100644
index 0000000000..76871e15cd
--- /dev/null
+++ b/python/mozbuild/mozpack/packager/l10n.py
@@ -0,0 +1,304 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""
+Replace localized parts of a packaged directory with data from a langpack
+directory.
+"""
+
+import json
+import os
+
+import six
+from createprecomplete import generate_precomplete
+
+import mozpack.path as mozpath
+from mozpack.chrome.manifest import (
+    Manifest,
+    ManifestChrome,
+    ManifestEntryWithRelPath,
+    ManifestLocale,
+    is_manifest,
+)
+from mozpack.copier import FileCopier, Jarrer
+from mozpack.errors import errors
+from mozpack.files import ComposedFinder, GeneratedFile, ManifestFile
+from mozpack.mozjar import JAR_DEFLATED
+from mozpack.packager import Component, SimpleManifestSink, SimplePackager
+from mozpack.packager.formats import FlatFormatter, JarFormatter, OmniJarFormatter
+from mozpack.packager.unpack import UnpackFinder
+
+
+class LocaleManifestFinder(object):
+    def __init__(self, finder):
+        entries = self.entries = []
+        bases = self.bases = []
+
+        class MockFormatter(object):
+            def add_interfaces(self, path, content):
+                pass
+
+            def add(self, path, content):
+                pass
+
+            def add_manifest(self, entry):
+                if entry.localized:
+                    entries.append(entry)
+
+            def add_base(self, base, addon=False):
+                bases.append(base)
+
+        # SimplePackager rejects "manifest foo.manifest" entries with
+        # additional flags (such as "manifest foo.manifest application=bar").
+        # Those type of entries are used by language packs to work as addons,
+        # but are not necessary for the purpose of l10n repacking. So we wrap
+        # the finder in order to remove those entries.
+        class WrapFinder(object):
+            def __init__(self, finder):
+                self._finder = finder
+
+            def find(self, pattern):
+                for p, f in self._finder.find(pattern):
+                    if isinstance(f, ManifestFile):
+                        unwanted = [
+                            e for e in f._entries if isinstance(e, Manifest) and e.flags
+                        ]
+                        if unwanted:
+                            f = ManifestFile(
+                                f._base, [e for e in f._entries if e not in unwanted]
+                            )
+                    yield p, f
+
+        sink = SimpleManifestSink(WrapFinder(finder), MockFormatter())
+        sink.add(Component(""), "*")
+        sink.close(False)
+
+        # Find unique locales used in these manifest entries.
+        self.locales = list(
+            set(e.id for e in self.entries if isinstance(e, ManifestLocale))
+        )
+
+
+class L10NRepackFormatterMixin(object):
+    def __init__(self, *args, **kwargs):
+        super(L10NRepackFormatterMixin, self).__init__(*args, **kwargs)
+        self._dictionaries = {}
+
+    def add(self, path, file):
+        base, relpath = self._get_base(path)
+        if path.endswith(".dic"):
+            if relpath.startswith("dictionaries/"):
+                root, ext = mozpath.splitext(mozpath.basename(path))
+                self._dictionaries[root] = path
+        elif path.endswith("/built_in_addons.json"):
+            data = json.loads(six.ensure_text(file.open().read()))
+            data["dictionaries"] = self._dictionaries
+            # The GeneratedFile content is only really generated after
+            # all calls to formatter.add.
+            file = GeneratedFile(lambda: json.dumps(data))
+        elif relpath.startswith("META-INF/"):
+            # Ignore signatures inside omnijars.  We drop these items: if we
+            # don't treat them as omnijar resources, they will be included in
+            # the top-level package, and that's not how omnijars are signed (Bug
+            # 1750676).  If we treat them as omnijar resources, they will stay
+            # in the omnijar, as expected -- but the signatures won't be valid
+            # after repacking.  Therefore, drop them.
+            return
+        super(L10NRepackFormatterMixin, self).add(path, file)
+
+
+def L10NRepackFormatter(klass):
+    class L10NRepackFormatter(L10NRepackFormatterMixin, klass):
+        pass
+
+    return L10NRepackFormatter
+
+
+FlatFormatter = L10NRepackFormatter(FlatFormatter)
+JarFormatter = L10NRepackFormatter(JarFormatter)
+OmniJarFormatter = L10NRepackFormatter(OmniJarFormatter)
+
+
+def _repack(app_finder, l10n_finder, copier, formatter, non_chrome=set()):
+    app = LocaleManifestFinder(app_finder)
+    l10n = LocaleManifestFinder(l10n_finder)
+
+    # The code further below assumes there's only one locale replaced with
+    # another one.
+    if len(app.locales) > 1:
+        errors.fatal("Multiple app locales aren't supported: " + ",".join(app.locales))
+    if len(l10n.locales) > 1:
+        errors.fatal(
+            "Multiple l10n locales aren't supported: " + ",".join(l10n.locales)
+        )
+    locale = app.locales[0]
+    l10n_locale = l10n.locales[0]
+
+    # For each base directory, store what path a locale chrome package name
+    # corresponds to.
+    # e.g., for the following entry under app/chrome:
+    #     locale foo en-US path/to/files
+    # keep track that the locale path for foo in app is
+    # app/chrome/path/to/files.
+    # As there may be multiple locale entries with the same base, but with
+    # different flags, that tracking takes the flags into account when there
+    # are some. Example:
+    #     locale foo en-US path/to/files/win os=Win
+    #     locale foo en-US path/to/files/mac os=Darwin
+    def key(entry):
+        if entry.flags:
+            return "%s %s" % (entry.name, entry.flags)
+        return entry.name
+
+    l10n_paths = {}
+    for e in l10n.entries:
+        if isinstance(e, ManifestChrome):
+            base = mozpath.basedir(e.path, app.bases)
+            l10n_paths.setdefault(base, {})
+            l10n_paths[base][key(e)] = e.path
+
+    # For chrome and non chrome files or directories, store what langpack path
+    # corresponds to a package path.
+    paths = {}
+    for e in app.entries:
+        if isinstance(e, ManifestEntryWithRelPath):
+            base = mozpath.basedir(e.path, app.bases)
+            if base not in l10n_paths:
+                errors.fatal("Locale doesn't contain %s/" % base)
+                # Allow errors to accumulate
+                continue
+            if key(e) not in l10n_paths[base]:
+                errors.fatal("Locale doesn't have a manifest entry for '%s'" % e.name)
+                # Allow errors to accumulate
+                continue
+            paths[e.path] = l10n_paths[base][key(e)]
+
+    for pattern in non_chrome:
+        for base in app.bases:
+            path = mozpath.join(base, pattern)
+            left = set(p for p, f in app_finder.find(path))
+            right = set(p for p, f in l10n_finder.find(path))
+            for p in right:
+                paths[p] = p
+            for p in left - right:
+                paths[p] = None
+
+    # Create a new package, with non localized bits coming from the original
+    # package, and localized bits coming from the langpack.
+    packager = SimplePackager(formatter)
+    for p, f in app_finder:
+        if is_manifest(p):
+            # Remove localized manifest entries.
+            for e in [e for e in f if e.localized]:
+                f.remove(e)
+        # If the path is one that needs a locale replacement, use the
+        # corresponding file from the langpack.
+        path = None
+        if p in paths:
+            path = paths[p]
+            if not path:
+                continue
+        else:
+            base = mozpath.basedir(p, paths.keys())
+            if base:
+                subpath = mozpath.relpath(p, base)
+                path = mozpath.normpath(mozpath.join(paths[base], subpath))
+
+        if path:
+            files = [f for p, f in l10n_finder.find(path)]
+            if not len(files):
+                if base not in non_chrome:
+                    finderBase = ""
+                    if hasattr(l10n_finder, "base"):
+                        finderBase = l10n_finder.base
+                    errors.error("Missing file: %s" % os.path.join(finderBase, path))
+            else:
+                packager.add(path, files[0])
+        else:
+            packager.add(p, f)
+
+    # Add localized manifest entries from the langpack.
+    l10n_manifests = []
+    for base in set(e.base for e in l10n.entries):
+        m = ManifestFile(base, [e for e in l10n.entries if e.base == base])
+        path = mozpath.join(base, "chrome.%s.manifest" % l10n_locale)
+        l10n_manifests.append((path, m))
+    bases = packager.get_bases()
+    for path, m in l10n_manifests:
+        base = mozpath.basedir(path, bases)
+        packager.add(path, m)
+        # Add a "manifest $path" entry in the top manifest under that base.
+        m = ManifestFile(base)
+        m.add(Manifest(base, mozpath.relpath(path, base)))
+        packager.add(mozpath.join(base, "chrome.manifest"), m)
+
+    packager.close()
+
+    # Add any remaining non chrome files.
+    for pattern in non_chrome:
+        for base in bases:
+            for p, f in l10n_finder.find(mozpath.join(base, pattern)):
+                if not formatter.contains(p):
+                    formatter.add(p, f)
+
+    # Resources in `localization` directories are packaged from the source and then
+    # if localized versions are present in the l10n dir, we package them as well
+    # keeping the source dir resources as a runtime fallback.
+    for p, f in l10n_finder.find("**/localization"):
+        if not formatter.contains(p):
+            formatter.add(p, f)
+
+    # Transplant jar preloading information.
+    for path, log in six.iteritems(app_finder.jarlogs):
+        assert isinstance(copier[path], Jarrer)
+        copier[path].preload([l.replace(locale, l10n_locale) for l in log])
+
+
+def repack(
+    source, l10n, extra_l10n={}, non_resources=[], non_chrome=set(), minify=False
+):
+    """
+    Replace localized data from the `source` directory with localized data
+    from `l10n` and `extra_l10n`.
+
+    The `source` argument points to a directory containing a packaged
+    application (in omnijar, jar or flat form).
+    The `l10n` argument points to a directory containing the main localized
+    data (usually in the form of a language pack addon) to use to replace
+    in the packaged application.
+    The `extra_l10n` argument contains a dict associating relative paths in
+    the source to separate directories containing localized data for them.
+    This can be used to point at different language pack addons for different
+    parts of the package application.
+    The `non_resources` argument gives a list of relative paths in the source
+    that should not be added in an omnijar in case the packaged application
+    is in that format.
+    The `non_chrome` argument gives a list of file/directory patterns for
+    localized files that are not listed in a chrome.manifest.
+    If `minify`, `.properties` files are minified.
+    """
+    app_finder = UnpackFinder(source, minify=minify)
+    l10n_finder = UnpackFinder(l10n, minify=minify)
+    if extra_l10n:
+        finders = {
+            "": l10n_finder,
+        }
+        for base, path in six.iteritems(extra_l10n):
+            finders[base] = UnpackFinder(path, minify=minify)
+        l10n_finder = ComposedFinder(finders)
+    copier = FileCopier()
+    compress = min(app_finder.compressed, JAR_DEFLATED)
+    if app_finder.kind == "flat":
+        formatter = FlatFormatter(copier)
+    elif app_finder.kind == "jar":
+        formatter = JarFormatter(copier, compress=compress)
+    elif app_finder.kind == "omni":
+        formatter = OmniJarFormatter(
+            copier, app_finder.omnijar, compress=compress, non_resources=non_resources
+        )
+
+    with errors.accumulate():
+        _repack(app_finder, l10n_finder, copier, formatter, non_chrome)
+    copier.copy(source, skip_if_older=False)
+    generate_precomplete(source)
diff --git a/python/mozbuild/mozpack/packager/unpack.py b/python/mozbuild/mozpack/packager/unpack.py
new file mode 100644
index 0000000000..dff295eb9b
--- /dev/null
+++ b/python/mozbuild/mozpack/packager/unpack.py
@@ -0,0 +1,200 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import codecs
+
+from six.moves.urllib.parse import urlparse
+
+import mozpack.path as mozpath
+from mozpack.chrome.manifest import (
+    ManifestEntryWithRelPath,
+    ManifestResource,
+    is_manifest,
+    parse_manifest,
+)
+from mozpack.copier import FileCopier, FileRegistry
+from mozpack.files import BaseFinder, DeflatedFile, FileFinder, ManifestFile
+from mozpack.mozjar import JarReader
+from mozpack.packager import SimplePackager
+from mozpack.packager.formats import FlatFormatter
+
+
+class UnpackFinder(BaseFinder):
+    """
+    Special Finder object that treats the source package directory as if it
+    were in the flat chrome format, whatever chrome format it actually is in.
+
+    This means that for example, paths like chrome/browser/content/... match
+    files under jar:chrome/browser.jar!/content/... in case of jar chrome
+    format.
+
+    The only argument to the constructor is a Finder instance or a path.
+    The UnpackFinder is populated with files from this Finder instance,
+    or with files from a FileFinder using the given path as its root.
+    """
+
+    def __init__(self, source, omnijar_name=None, unpack_xpi=True, **kwargs):
+        if isinstance(source, BaseFinder):
+            assert not kwargs
+            self._finder = source
+        else:
+            self._finder = FileFinder(source, **kwargs)
+        self.base = self._finder.base
+        self.files = FileRegistry()
+        self.kind = "flat"
+        if omnijar_name:
+            self.omnijar = omnijar_name
+        else:
+            # Can't include globally because of bootstrapping issues.
+            from buildconfig import substs
+
+            self.omnijar = substs.get("OMNIJAR_NAME", "omni.ja")
+        self.jarlogs = {}
+        self.compressed = False
+        self._unpack_xpi = unpack_xpi
+
+        jars = set()
+
+        for p, f in self._finder.find("*"):
+            # Skip the precomplete file, which is generated at packaging time.
+            if p == "precomplete":
+                continue
+            base = mozpath.dirname(p)
+            # If the file matches the omnijar pattern, it is an omnijar.
+            # All the files it contains go in the directory containing the full
+            # pattern. Manifests are merged if there is a corresponding manifest
+            # in the directory.
+            if self._maybe_zip(f) and mozpath.match(p, "**/%s" % self.omnijar):
+                jar = self._open_jar(p, f)
+                if "chrome.manifest" in jar:
+                    self.kind = "omni"
+                    self._fill_with_jar(p[: -len(self.omnijar) - 1], jar)
+                    continue
+            # If the file is a manifest, scan its entries for some referencing
+            # jar: urls. If there are some, the files contained in the jar they
+            # point to, go under a directory named after the jar.
+            if is_manifest(p):
+                m = self.files[p] if self.files.contains(p) else ManifestFile(base)
+                for e in parse_manifest(
+                    self.base, p, codecs.getreader("utf-8")(f.open())
+                ):
+                    m.add(self._handle_manifest_entry(e, jars))
+                if self.files.contains(p):
+                    continue
+                f = m
+            # If we're unpacking packed addons and the file is a packed addon,
+            # unpack it under a directory named after the xpi.
+            if self._unpack_xpi and p.endswith(".xpi") and self._maybe_zip(f):
+                self._fill_with_jar(p[:-4], self._open_jar(p, f))
+                continue
+            if p not in jars:
+                self.files.add(p, f)
+
+    def _fill_with_jar(self, base, jar):
+        for j in jar:
+            path = mozpath.join(base, j.filename)
+            if is_manifest(j.filename):
+                m = (
+                    self.files[path]
+                    if self.files.contains(path)
+                    else ManifestFile(mozpath.dirname(path))
+                )
+                for e in parse_manifest(None, path, j):
+                    m.add(e)
+                if not self.files.contains(path):
+                    self.files.add(path, m)
+                continue
+            else:
+                self.files.add(path, DeflatedFile(j))
+
+    def _handle_manifest_entry(self, entry, jars):
+        jarpath = None
+        if (
+            isinstance(entry, ManifestEntryWithRelPath)
+            and urlparse(entry.relpath).scheme == "jar"
+        ):
+            jarpath, entry = self._unjarize(entry, entry.relpath)
+        elif (
+            isinstance(entry, ManifestResource)
+            and urlparse(entry.target).scheme == "jar"
+        ):
+            jarpath, entry = self._unjarize(entry, entry.target)
+        if jarpath:
+            # Don't defer unpacking the jar file. If we already saw
+            # it, take (and remove) it from the registry. If we
+            # haven't, try to find it now.
+            if self.files.contains(jarpath):
+                jar = self.files[jarpath]
+                self.files.remove(jarpath)
+            else:
+                jar = [f for p, f in self._finder.find(jarpath)]
+                assert len(jar) == 1
+                jar = jar[0]
+            if jarpath not in jars:
+                base = mozpath.splitext(jarpath)[0]
+                for j in self._open_jar(jarpath, jar):
+                    self.files.add(mozpath.join(base, j.filename), DeflatedFile(j))
+            jars.add(jarpath)
+            self.kind = "jar"
+        return entry
+
+    def _open_jar(self, path, file):
+        """
+        Return a JarReader for the given BaseFile instance, keeping a log of
+        the preloaded entries it has.
+        """
+        jar = JarReader(fileobj=file.open())
+        self.compressed = max(self.compressed, jar.compression)
+        if jar.last_preloaded:
+            jarlog = list(jar.entries.keys())
+            self.jarlogs[path] = jarlog[: jarlog.index(jar.last_preloaded) + 1]
+        return jar
+
+    def find(self, path):
+        for p in self.files.match(path):
+            yield p, self.files[p]
+
+    def _maybe_zip(self, file):
+        """
+        Return whether the given BaseFile looks like a ZIP/Jar.
+        """
+        header = file.open().read(8)
+        return len(header) == 8 and (header[0:2] == b"PK" or header[4:6] == b"PK")
+
+    def _unjarize(self, entry, relpath):
+        """
+        Transform a manifest entry pointing to chrome data in a jar in one
+        pointing to the corresponding unpacked path. Return the jar path and
+        the new entry.
+        """
+        base = entry.base
+        jar, relpath = urlparse(relpath).path.split("!", 1)
+        entry = (
+            entry.rebase(mozpath.join(base, "jar:%s!" % jar))
+            .move(mozpath.join(base, mozpath.splitext(jar)[0]))
+            .rebase(base)
+        )
+        return mozpath.join(base, jar), entry
+
+
+def unpack_to_registry(source, registry, omnijar_name=None):
+    """
+    Transform a jar chrome or omnijar packaged directory into a flat package.
+
+    The given registry is filled with the flat package.
+    """
+    finder = UnpackFinder(source, omnijar_name)
+    packager = SimplePackager(FlatFormatter(registry))
+    for p, f in finder.find("*"):
+        packager.add(p, f)
+    packager.close()
+
+
+def unpack(source, omnijar_name=None):
+    """
+    Transform a jar chrome or omnijar packaged directory into a flat package.
+    """
+    copier = FileCopier()
+    unpack_to_registry(source, copier, omnijar_name)
+    copier.copy(source, skip_if_older=False)
diff --git a/python/mozbuild/mozpack/path.py b/python/mozbuild/mozpack/path.py
new file mode 100644
index 0000000000..3e5af0a06b
--- /dev/null
+++ b/python/mozbuild/mozpack/path.py
@@ -0,0 +1,246 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""
+Like :py:mod:`os.path`, with a reduced set of functions, and with normalized path
+separators (always use forward slashes).
+Also contains a few additional utilities not found in :py:mod:`os.path`.
+"""
+
+import ctypes
+import os
+import posixpath
+import re
+import sys
+
+
+def normsep(path):
+    """
+    Normalize path separators, by using forward slashes instead of whatever
+    :py:const:`os.sep` is.
+    """
+    if os.sep != "/":
+        # Python 2 is happy to do things like byte_string.replace(u'foo',
+        # u'bar'), but not Python 3.
+        if isinstance(path, bytes):
+            path = path.replace(os.sep.encode("ascii"), b"/")
+        else:
+            path = path.replace(os.sep, "/")
+    if os.altsep and os.altsep != "/":
+        if isinstance(path, bytes):
+            path = path.replace(os.altsep.encode("ascii"), b"/")
+        else:
+            path = path.replace(os.altsep, "/")
+    return path
+
+
+def cargo_workaround(path):
+    unc = "//?/"
+    if path.startswith(unc):
+        return path[len(unc) :]
+    return path
+
+
+def relpath(path, start):
+    path = normsep(path)
+    start = normsep(start)
+    if sys.platform == "win32":
+        # os.path.relpath can't handle relative paths between UNC and non-UNC
+        # paths, so strip a //?/ prefix if present (bug 1581248)
+        path = cargo_workaround(path)
+        start = cargo_workaround(start)
+    try:
+        rel = os.path.relpath(path, start)
+    except ValueError:
+        # On Windows this can throw a ValueError if the two paths are on
+        # different drives. In that case, just return the path.
+        return abspath(path)
+    rel = normsep(rel)
+    return "" if rel == "." else rel
+
+
+def realpath(path):
+    return normsep(os.path.realpath(path))
+
+
+def abspath(path):
+    return normsep(os.path.abspath(path))
+
+
+def join(*paths):
+    return normsep(os.path.join(*paths))
+
+
+def normpath(path):
+    return posixpath.normpath(normsep(path))
+
+
+def dirname(path):
+    return posixpath.dirname(normsep(path))
+
+
+def commonprefix(paths):
+    return posixpath.commonprefix([normsep(path) for path in paths])
+
+
+def basename(path):
+    return os.path.basename(path)
+
+
+def splitext(path):
+    return posixpath.splitext(normsep(path))
+
+
+def split(path):
+    """
+    Return the normalized path as a list of its components.
+
+        ``split('foo/bar/baz')`` returns ``['foo', 'bar', 'baz']``
+    """
+    return normsep(path).split("/")
+
+
+def basedir(path, bases):
+    """
+    Given a list of directories (`bases`), return which one contains the given
+    path. If several matches are found, the deepest base directory is returned.
+
+        ``basedir('foo/bar/baz', ['foo', 'baz', 'foo/bar'])`` returns ``'foo/bar'``
+        (`'foo'` and `'foo/bar'` both match, but `'foo/bar'` is the deepest match)
+    """
+    path = normsep(path)
+    bases = [normsep(b) for b in bases]
+    if path in bases:
+        return path
+    for b in sorted(bases, reverse=True):
+        if b == "" or path.startswith(b + "/"):
+            return b
+
+
+re_cache = {}
+# Python versions < 3.7 return r'\/' for re.escape('/').
+if re.escape("/") == "/":
+    MATCH_STAR_STAR_RE = re.compile(r"(^|/)\\\*\\\*/")
+    MATCH_STAR_STAR_END_RE = re.compile(r"(^|/)\\\*\\\*$")
+else:
+    MATCH_STAR_STAR_RE = re.compile(r"(^|\\\/)\\\*\\\*\\\/")
+    MATCH_STAR_STAR_END_RE = re.compile(r"(^|\\\/)\\\*\\\*$")
+
+
+def match(path, pattern):
+    """
+    Return whether the given path matches the given pattern.
+    An asterisk can be used to match any string, including the null string, in
+    one part of the path:
+
+        ``foo`` matches ``*``, ``f*`` or ``fo*o``
+
+    However, an asterisk matching a subdirectory may not match the null string:
+
+        ``foo/bar`` does *not* match ``foo/*/bar``
+
+    If the pattern matches one of the ancestor directories of the path, the
+    patch is considered matching:
+
+        ``foo/bar`` matches ``foo``
+
+    Two adjacent asterisks can be used to match files and zero or more
+    directories and subdirectories.
+
+        ``foo/bar`` matches ``foo/**/bar``, or ``**/bar``
+    """
+    if not pattern:
+        return True
+    if pattern not in re_cache:
+        p = re.escape(pattern)
+        p = MATCH_STAR_STAR_RE.sub(r"\1(?:.+/)?", p)
+        p = MATCH_STAR_STAR_END_RE.sub(r"(?:\1.+)?", p)
+        p = p.replace(r"\*", "[^/]*") + "(?:/.*)?$"
+        re_cache[pattern] = re.compile(p)
+    return re_cache[pattern].match(path) is not None
+
+
+def rebase(oldbase, base, relativepath):
+    """
+    Return `relativepath` relative to `base` instead of `oldbase`.
+    """
+    if base == oldbase:
+        return relativepath
+    if len(base) < len(oldbase):
+        assert basedir(oldbase, [base]) == base
+        relbase = relpath(oldbase, base)
+        result = join(relbase, relativepath)
+    else:
+        assert basedir(base, [oldbase]) == oldbase
+        relbase = relpath(base, oldbase)
+        result = relpath(relativepath, relbase)
+    result = normpath(result)
+    if relativepath.endswith("/") and not result.endswith("/"):
+        result += "/"
+    return result
+
+
+def readlink(path):
+    if hasattr(os, "readlink"):
+        return normsep(os.readlink(path))
+
+    # Unfortunately os.path.realpath doesn't support symlinks on Windows, and os.readlink
+    # is only available on Windows with Python 3.2+. We have to resort to ctypes...
+
+    assert sys.platform == "win32"
+
+    CreateFileW = ctypes.windll.kernel32.CreateFileW
+    CreateFileW.argtypes = [
+        ctypes.wintypes.LPCWSTR,
+        ctypes.wintypes.DWORD,
+        ctypes.wintypes.DWORD,
+        ctypes.wintypes.LPVOID,
+        ctypes.wintypes.DWORD,
+        ctypes.wintypes.DWORD,
+        ctypes.wintypes.HANDLE,
+    ]
+    CreateFileW.restype = ctypes.wintypes.HANDLE
+
+    GENERIC_READ = 0x80000000
+    FILE_SHARE_READ = 0x00000001
+    OPEN_EXISTING = 3
+    FILE_FLAG_BACKUP_SEMANTICS = 0x02000000
+
+    handle = CreateFileW(
+        path,
+        GENERIC_READ,
+        FILE_SHARE_READ,
+        0,
+        OPEN_EXISTING,
+        FILE_FLAG_BACKUP_SEMANTICS,
+        0,
+    )
+    assert handle != 1, "Failed getting a handle to: {}".format(path)
+
+    MAX_PATH = 260
+
+    buf = ctypes.create_unicode_buffer(MAX_PATH)
+    GetFinalPathNameByHandleW = ctypes.windll.kernel32.GetFinalPathNameByHandleW
+    GetFinalPathNameByHandleW.argtypes = [
+        ctypes.wintypes.HANDLE,
+        ctypes.wintypes.LPWSTR,
+        ctypes.wintypes.DWORD,
+        ctypes.wintypes.DWORD,
+    ]
+    GetFinalPathNameByHandleW.restype = ctypes.wintypes.DWORD
+
+    FILE_NAME_NORMALIZED = 0x0
+
+    rv = GetFinalPathNameByHandleW(handle, buf, MAX_PATH, FILE_NAME_NORMALIZED)
+    assert rv != 0 and rv <= MAX_PATH, "Failed getting final path for: {}".format(path)
+
+    CloseHandle = ctypes.windll.kernel32.CloseHandle
+    CloseHandle.argtypes = [ctypes.wintypes.HANDLE]
+    CloseHandle.restype = ctypes.wintypes.BOOL
+
+    rv = CloseHandle(handle)
+    assert rv != 0, "Failed closing handle"
+
+    # Remove leading '\\?\' from the result.
+    return normsep(buf.value[4:])
diff --git a/python/mozbuild/mozpack/pkg.py b/python/mozbuild/mozpack/pkg.py
new file mode 100644
index 0000000000..75a63b9746
--- /dev/null
+++ b/python/mozbuild/mozpack/pkg.py
@@ -0,0 +1,299 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import concurrent.futures
+import lzma
+import os
+import plistlib
+import struct
+import subprocess
+from pathlib import Path
+from string import Template
+from typing import List
+from urllib.parse import quote
+
+import mozfile
+
+TEMPLATE_DIRECTORY = Path(__file__).parent / "apple_pkg"
+PBZX_CHUNK_SIZE = 16 * 1024 * 1024  # 16MB chunks
+
+
+def get_apple_template(name: str) -> Template:
+    """
+    Given <name>, open file at <TEMPLATE_DIRECTORY>/<name>, read contents and
+        return as a Template
+
+    Args:
+        name: str, Filename for the template
+
+    Returns:
+        Template, loaded from file
+    """
+    tmpl_path = TEMPLATE_DIRECTORY / name
+    if not tmpl_path.is_file():
+        raise Exception(f"Could not find template: {tmpl_path}")
+    with tmpl_path.open("r") as tmpl:
+        contents = tmpl.read()
+    return Template(contents)
+
+
+def save_text_file(content: str, destination: Path):
+    """
+    Saves a text file to <destination> with provided <content>
+    Note: Overwrites contents
+
+    Args:
+        content: str, The desired contents of the file
+        destination: Path, The file path
+    """
+    with destination.open("w") as out_fd:
+        out_fd.write(content)
+    print(f"Created text file at {destination}")
+    print(f"Created text file size: {destination.stat().st_size} bytes")
+
+
+def get_app_info_plist(app_path: Path) -> dict:
+    """
+    Retrieve most information from Info.plist file of an app.
+    The Info.plist file should be located in ?.app/Contents/Info.plist
+
+    Note: Ignores properties that are not <string> type
+
+    Args:
+        app_path: Path, the .app file/directory path
+
+    Returns:
+        dict, the dictionary of properties found in Info.plist
+    """
+    info_plist = app_path / "Contents/Info.plist"
+    if not info_plist.is_file():
+        raise Exception(f"Could not find Info.plist in {info_plist}")
+
+    print(f"Reading app Info.plist from: {info_plist}")
+
+    with info_plist.open("rb") as plist_fd:
+        data = plistlib.load(plist_fd)
+
+    return data
+
+
+def create_payload(destination: Path, root_path: Path, cpio_tool: str):
+    """
+    Creates a payload at <destination> based on <root_path>
+
+    Args:
+        destination: Path, the destination Path
+        root_path: Path, the root directory Path
+        cpio_tool: str,
+    """
+    # Files to be cpio'd are root folder + contents
+    file_list = ["./"] + get_relative_glob_list(root_path, "**/*")
+
+    with mozfile.TemporaryDirectory() as tmp_dir:
+        tmp_payload_path = Path(tmp_dir) / "Payload"
+        print(f"Creating Payload with cpio from {root_path} to {tmp_payload_path}")
+        print(f"Found {len(file_list)} files")
+        with tmp_payload_path.open("wb") as tmp_payload:
+            process = subprocess.run(
+                [
+                    cpio_tool,
+                    "-o",  # copy-out mode
+                    "--format",
+                    "odc",  # old POSIX .1 portable format
+                    "--owner",
+                    "0:80",  # clean ownership
+                ],
+                stdout=tmp_payload,
+                stderr=subprocess.PIPE,
+                input="\n".join(file_list) + "\n",
+                encoding="ascii",
+                cwd=root_path,
+            )
+        # cpio outputs number of blocks to stderr
+        print(f"[CPIO]: {process.stderr}")
+        if process.returncode:
+            raise Exception(f"CPIO error {process.returncode}")
+
+        tmp_payload_size = tmp_payload_path.stat().st_size
+        print(f"Uncompressed Payload size: {tmp_payload_size // 1024}kb")
+
+        def compress_chunk(chunk):
+            compressed_chunk = lzma.compress(chunk)
+            return len(chunk), compressed_chunk
+
+        def chunker(fileobj, chunk_size):
+            while True:
+                chunk = fileobj.read(chunk_size)
+                if not chunk:
+                    break
+                yield chunk
+
+        with tmp_payload_path.open("rb") as f_in, destination.open(
+            "wb"
+        ) as f_out, concurrent.futures.ThreadPoolExecutor(
+            max_workers=os.cpu_count()
+        ) as executor:
+            f_out.write(b"pbzx")
+            f_out.write(struct.pack(">Q", PBZX_CHUNK_SIZE))
+            chunks = chunker(f_in, PBZX_CHUNK_SIZE)
+            for uncompressed_size, compressed_chunk in executor.map(
+                compress_chunk, chunks
+            ):
+                f_out.write(struct.pack(">Q", uncompressed_size))
+                if len(compressed_chunk) < uncompressed_size:
+                    f_out.write(struct.pack(">Q", len(compressed_chunk)))
+                    f_out.write(compressed_chunk)
+                else:
+                    # Considering how unlikely this is, we prefer to just decompress
+                    # here than to keep the original uncompressed chunk around
+                    f_out.write(struct.pack(">Q", uncompressed_size))
+                    f_out.write(lzma.decompress(compressed_chunk))
+
+        print(f"Compressed Payload file to {destination}")
+        print(f"Compressed Payload size: {destination.stat().st_size // 1024}kb")
+
+
+def create_bom(bom_path: Path, root_path: Path, mkbom_tool: Path):
+    """
+    Creates a Bill Of Materials file at <bom_path> based on <root_path>
+
+    Args:
+        bom_path: Path, destination Path for the BOM file
+        root_path: Path, root directory Path
+        mkbom_tool: Path, mkbom tool Path
+    """
+    print(f"Creating BOM file from {root_path} to {bom_path}")
+    subprocess.check_call(
+        [
+            mkbom_tool,
+            "-u",
+            "0",
+            "-g",
+            "80",
+            str(root_path),
+            str(bom_path),
+        ]
+    )
+    print(f"Created BOM File size: {bom_path.stat().st_size // 1024}kb")
+
+
+def get_relative_glob_list(source: Path, glob: str) -> List[str]:
+    """
+    Given a source path, return a list of relative path based on glob
+
+    Args:
+        source: Path, source directory Path
+        glob: str, unix style glob
+
+    Returns:
+        list[str], paths found in source directory
+    """
+    return [f"./{c.relative_to(source)}" for c in source.glob(glob)]
+
+
+def xar_package_folder(source_path: Path, destination: Path, xar_tool: Path):
+    """
+    Create a pkg from <source_path> to <destination>
+    The command is issued with <source_path> as cwd
+
+    Args:
+        source_path: Path, source absolute Path
+        destination: Path, destination absolute Path
+        xar_tool: Path, xar tool Path
+    """
+    if not source_path.is_absolute() or not destination.is_absolute():
+        raise Exception("Source and destination should be absolute.")
+
+    print(f"Creating pkg from {source_path} to {destination}")
+    # Create a list of ./<file> - noting xar takes care of <file>/**
+    file_list = get_relative_glob_list(source_path, "*")
+
+    subprocess.check_call(
+        [
+            xar_tool,
+            "--compression",
+            "none",
+            "-vcf",
+            destination,
+            *file_list,
+        ],
+        cwd=source_path,
+    )
+    print(f"Created PKG file to {destination}")
+    print(f"Created PKG size: {destination.stat().st_size // 1024}kb")
+
+
+def create_pkg(
+    source_app: Path,
+    output_pkg: Path,
+    mkbom_tool: Path,
+    xar_tool: Path,
+    cpio_tool: Path,
+):
+    """
+    Create a mac PKG installer from <source_app> to <output_pkg>
+
+    Args:
+        source_app: Path, source .app file/directory Path
+        output_pkg: Path, destination .pkg file
+        mkbom_tool: Path, mkbom tool Path
+        xar_tool: Path, xar tool Path
+        cpio: Path, cpio tool Path
+    """
+
+    app_name = source_app.name.rsplit(".", maxsplit=1)[0]
+
+    with mozfile.TemporaryDirectory() as tmpdir:
+        root_path = Path(tmpdir) / "darwin/root"
+        flat_path = Path(tmpdir) / "darwin/flat"
+
+        # Create required directories
+        # TODO: Investigate Resources folder contents for other lproj?
+        (flat_path / "Resources/en.lproj").mkdir(parents=True, exist_ok=True)
+        (flat_path / f"{app_name}.pkg").mkdir(parents=True, exist_ok=True)
+        root_path.mkdir(parents=True, exist_ok=True)
+
+        # Copy files over
+        subprocess.check_call(
+            [
+                "cp",
+                "-R",
+                str(source_app),
+                str(root_path),
+            ]
+        )
+
+        # Count all files (innards + itself)
+        file_count = len(list(source_app.glob("**/*"))) + 1
+        print(f"Calculated source files count: {file_count}")
+        # Get package contents size
+        package_size = sum(f.stat().st_size for f in source_app.glob("**/*")) // 1024
+        print(f"Calculated source package size: {package_size}kb")
+
+        app_info = get_app_info_plist(source_app)
+        app_info["numberOfFiles"] = file_count
+        app_info["installKBytes"] = package_size
+        app_info["app_name"] = app_name
+        app_info["app_name_url_encoded"] = quote(app_name)
+
+        # This seems arbitrary, there might be another way of doing it,
+        #   but Info.plist doesn't provide the simple version we need
+        major_version = app_info["CFBundleShortVersionString"].split(".")[0]
+        app_info["simple_version"] = f"{major_version}.0.0"
+
+        pkg_info_tmpl = get_apple_template("PackageInfo.template")
+        pkg_info = pkg_info_tmpl.substitute(app_info)
+        save_text_file(pkg_info, flat_path / f"{app_name}.pkg/PackageInfo")
+
+        distribution_tmp = get_apple_template("Distribution.template")
+        distribution = distribution_tmp.substitute(app_info)
+        save_text_file(distribution, flat_path / "Distribution")
+
+        payload_path = flat_path / f"{app_name}.pkg/Payload"
+        create_payload(payload_path, root_path, cpio_tool)
+
+        bom_path = flat_path / f"{app_name}.pkg/Bom"
+        create_bom(bom_path, root_path, mkbom_tool)
+
+        xar_package_folder(flat_path, output_pkg, xar_tool)
diff --git a/python/mozbuild/mozpack/test/__init__.py b/python/mozbuild/mozpack/test/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/python/mozbuild/mozpack/test/__init__.py
diff --git a/python/mozbuild/mozpack/test/data/test_data b/python/mozbuild/mozpack/test/data/test_data
new file mode 100644
index 0000000000..fb7f0c4fc2
--- /dev/null
+++ b/python/mozbuild/mozpack/test/data/test_data
@@ -0,0 +1 @@
+test_data
\ No newline at end of file
diff --git a/python/mozbuild/mozpack/test/python.toml b/python/mozbuild/mozpack/test/python.toml
new file mode 100644
index 0000000000..c886e78cf1
--- /dev/null
+++ b/python/mozbuild/mozpack/test/python.toml
@@ -0,0 +1,32 @@
+[DEFAULT]
+subsuite = "mozbuild"
+
+["test_archive.py"]
+
+["test_chrome_flags.py"]
+
+["test_chrome_manifest.py"]
+
+["test_copier.py"]
+
+["test_errors.py"]
+
+["test_files.py"]
+
+["test_manifests.py"]
+
+["test_mozjar.py"]
+
+["test_packager.py"]
+
+["test_packager_formats.py"]
+
+["test_packager_l10n.py"]
+
+["test_packager_unpack.py"]
+
+["test_path.py"]
+
+["test_pkg.py"]
+
+["test_unify.py"]
diff --git a/python/mozbuild/mozpack/test/support/minify_js_verify.py b/python/mozbuild/mozpack/test/support/minify_js_verify.py
new file mode 100644
index 0000000000..88cc0ece0c
--- /dev/null
+++ b/python/mozbuild/mozpack/test/support/minify_js_verify.py
@@ -0,0 +1,15 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import sys
+
+if len(sys.argv) != 4:
+    raise Exception("Usage: minify_js_verify <exitcode> <orig> <minified>")
+
+retcode = int(sys.argv[1])
+
+if retcode:
+    print("Error message", file=sys.stderr)
+
+sys.exit(retcode)
diff --git a/python/mozbuild/mozpack/test/test_archive.py b/python/mozbuild/mozpack/test/test_archive.py
new file mode 100644
index 0000000000..3417f279df
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_archive.py
@@ -0,0 +1,197 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import hashlib
+import os
+import shutil
+import stat
+import tarfile
+import tempfile
+import unittest
+
+import pytest
+from mozunit import main
+
+from mozpack.archive import (
+    DEFAULT_MTIME,
+    create_tar_bz2_from_files,
+    create_tar_from_files,
+    create_tar_gz_from_files,
+)
+from mozpack.files import GeneratedFile
+
+MODE_STANDARD = stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH
+
+
+def file_hash(path):
+    h = hashlib.sha1()
+    with open(path, "rb") as fh:
+        while True:
+            data = fh.read(8192)
+            if not data:
+                break
+            h.update(data)
+
+    return h.hexdigest()
+
+
+class TestArchive(unittest.TestCase):
+    def _create_files(self, root):
+        files = {}
+        for i in range(10):
+            p = os.path.join(root, "file%02d" % i)
+            with open(p, "wb") as fh:
+                fh.write(b"file%02d" % i)
+            # Need to set permissions or umask may influence testing.
+            os.chmod(p, MODE_STANDARD)
+            files["file%02d" % i] = p
+
+        for i in range(10):
+            files["file%02d" % (i + 10)] = GeneratedFile(b"file%02d" % (i + 10))
+
+        return files
+
+    def _verify_basic_tarfile(self, tf):
+        self.assertEqual(len(tf.getmembers()), 20)
+
+        names = ["file%02d" % i for i in range(20)]
+        self.assertEqual(tf.getnames(), names)
+
+        for ti in tf.getmembers():
+            self.assertEqual(ti.uid, 0)
+            self.assertEqual(ti.gid, 0)
+            self.assertEqual(ti.uname, "")
+            self.assertEqual(ti.gname, "")
+            self.assertEqual(ti.mode, MODE_STANDARD)
+            self.assertEqual(ti.mtime, DEFAULT_MTIME)
+
+    @pytest.mark.xfail(
+        reason="ValueError is not thrown despite being provided directory."
+    )
+    def test_dirs_refused(self):
+        d = tempfile.mkdtemp()
+        try:
+            tp = os.path.join(d, "test.tar")
+            with open(tp, "wb") as fh:
+                with self.assertRaisesRegexp(ValueError, "not a regular"):
+                    create_tar_from_files(fh, {"test": d})
+        finally:
+            shutil.rmtree(d)
+
+    @pytest.mark.xfail(reason="ValueError is not thrown despite uid/gid being set.")
+    def test_setuid_setgid_refused(self):
+        d = tempfile.mkdtemp()
+        try:
+            uid = os.path.join(d, "setuid")
+            gid = os.path.join(d, "setgid")
+            with open(uid, "a"):
+                pass
+            with open(gid, "a"):
+                pass
+
+            os.chmod(uid, MODE_STANDARD | stat.S_ISUID)
+            os.chmod(gid, MODE_STANDARD | stat.S_ISGID)
+
+            tp = os.path.join(d, "test.tar")
+            with open(tp, "wb") as fh:
+                with self.assertRaisesRegexp(ValueError, "cannot add file with setuid"):
+                    create_tar_from_files(fh, {"test": uid})
+                with self.assertRaisesRegexp(ValueError, "cannot add file with setuid"):
+                    create_tar_from_files(fh, {"test": gid})
+        finally:
+            shutil.rmtree(d)
+
+    def test_create_tar_basic(self):
+        d = tempfile.mkdtemp()
+        try:
+            files = self._create_files(d)
+
+            tp = os.path.join(d, "test.tar")
+            with open(tp, "wb") as fh:
+                create_tar_from_files(fh, files)
+
+            # Output should be deterministic.
+            self.assertEqual(file_hash(tp), "01cd314e277f060e98c7de6c8ea57f96b3a2065c")
+
+            with tarfile.open(tp, "r") as tf:
+                self._verify_basic_tarfile(tf)
+
+        finally:
+            shutil.rmtree(d)
+
+    @pytest.mark.xfail(reason="hash mismatch")
+    def test_executable_preserved(self):
+        d = tempfile.mkdtemp()
+        try:
+            p = os.path.join(d, "exec")
+            with open(p, "wb") as fh:
+                fh.write("#!/bin/bash\n")
+            os.chmod(p, MODE_STANDARD | stat.S_IXUSR)
+
+            tp = os.path.join(d, "test.tar")
+            with open(tp, "wb") as fh:
+                create_tar_from_files(fh, {"exec": p})
+
+            self.assertEqual(file_hash(tp), "357e1b81c0b6cfdfa5d2d118d420025c3c76ee93")
+
+            with tarfile.open(tp, "r") as tf:
+                m = tf.getmember("exec")
+                self.assertEqual(m.mode, MODE_STANDARD | stat.S_IXUSR)
+
+        finally:
+            shutil.rmtree(d)
+
+    def test_create_tar_gz_basic(self):
+        d = tempfile.mkdtemp()
+        try:
+            files = self._create_files(d)
+
+            gp = os.path.join(d, "test.tar.gz")
+            with open(gp, "wb") as fh:
+                create_tar_gz_from_files(fh, files)
+
+            self.assertEqual(file_hash(gp), "7c4da5adc5088cdf00911d5daf9a67b15de714b7")
+
+            with tarfile.open(gp, "r:gz") as tf:
+                self._verify_basic_tarfile(tf)
+
+        finally:
+            shutil.rmtree(d)
+
+    def test_tar_gz_name(self):
+        d = tempfile.mkdtemp()
+        try:
+            files = self._create_files(d)
+
+            gp = os.path.join(d, "test.tar.gz")
+            with open(gp, "wb") as fh:
+                create_tar_gz_from_files(fh, files, filename="foobar")
+
+            self.assertEqual(file_hash(gp), "721e00083c17d16df2edbddf40136298c06d0c49")
+
+            with tarfile.open(gp, "r:gz") as tf:
+                self._verify_basic_tarfile(tf)
+
+        finally:
+            shutil.rmtree(d)
+
+    def test_create_tar_bz2_basic(self):
+        d = tempfile.mkdtemp()
+        try:
+            files = self._create_files(d)
+
+            bp = os.path.join(d, "test.tar.bz2")
+            with open(bp, "wb") as fh:
+                create_tar_bz2_from_files(fh, files)
+
+            self.assertEqual(file_hash(bp), "eb5096d2fbb71df7b3d690001a6f2e82a5aad6a7")
+
+            with tarfile.open(bp, "r:bz2") as tf:
+                self._verify_basic_tarfile(tf)
+        finally:
+            shutil.rmtree(d)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/python/mozbuild/mozpack/test/test_chrome_flags.py b/python/mozbuild/mozpack/test/test_chrome_flags.py
new file mode 100644
index 0000000000..4f1a968dc2
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_chrome_flags.py
@@ -0,0 +1,150 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import unittest
+
+import mozunit
+
+from mozpack.chrome.flags import Flag, Flags, StringFlag, VersionFlag
+from mozpack.errors import ErrorMessage
+
+
+class TestFlag(unittest.TestCase):
+    def test_flag(self):
+        flag = Flag("flag")
+        self.assertEqual(str(flag), "")
+        self.assertTrue(flag.matches(False))
+        self.assertTrue(flag.matches("false"))
+        self.assertFalse(flag.matches("true"))
+        self.assertRaises(ErrorMessage, flag.add_definition, "flag=")
+        self.assertRaises(ErrorMessage, flag.add_definition, "flag=42")
+        self.assertRaises(ErrorMessage, flag.add_definition, "flag!=false")
+
+        flag.add_definition("flag=1")
+        self.assertEqual(str(flag), "flag=1")
+        self.assertTrue(flag.matches(True))
+        self.assertTrue(flag.matches("1"))
+        self.assertFalse(flag.matches("no"))
+
+        flag.add_definition("flag=true")
+        self.assertEqual(str(flag), "flag=true")
+        self.assertTrue(flag.matches(True))
+        self.assertTrue(flag.matches("true"))
+        self.assertFalse(flag.matches("0"))
+
+        flag.add_definition("flag=no")
+        self.assertEqual(str(flag), "flag=no")
+        self.assertTrue(flag.matches("false"))
+        self.assertFalse(flag.matches("1"))
+
+        flag.add_definition("flag")
+        self.assertEqual(str(flag), "flag")
+        self.assertFalse(flag.matches("false"))
+        self.assertTrue(flag.matches("true"))
+        self.assertFalse(flag.matches(False))
+
+    def test_string_flag(self):
+        flag = StringFlag("flag")
+        self.assertEqual(str(flag), "")
+        self.assertTrue(flag.matches("foo"))
+        self.assertRaises(ErrorMessage, flag.add_definition, "flag>=2")
+
+        flag.add_definition("flag=foo")
+        self.assertEqual(str(flag), "flag=foo")
+        self.assertTrue(flag.matches("foo"))
+        self.assertFalse(flag.matches("bar"))
+
+        flag.add_definition("flag=bar")
+        self.assertEqual(str(flag), "flag=foo flag=bar")
+        self.assertTrue(flag.matches("foo"))
+        self.assertTrue(flag.matches("bar"))
+        self.assertFalse(flag.matches("baz"))
+
+        flag = StringFlag("flag")
+        flag.add_definition("flag!=bar")
+        self.assertEqual(str(flag), "flag!=bar")
+        self.assertTrue(flag.matches("foo"))
+        self.assertFalse(flag.matches("bar"))
+
+    def test_version_flag(self):
+        flag = VersionFlag("flag")
+        self.assertEqual(str(flag), "")
+        self.assertTrue(flag.matches("1.0"))
+        self.assertRaises(ErrorMessage, flag.add_definition, "flag!=2")
+
+        flag.add_definition("flag=1.0")
+        self.assertEqual(str(flag), "flag=1.0")
+        self.assertTrue(flag.matches("1.0"))
+        self.assertFalse(flag.matches("2.0"))
+
+        flag.add_definition("flag=2.0")
+        self.assertEqual(str(flag), "flag=1.0 flag=2.0")
+        self.assertTrue(flag.matches("1.0"))
+        self.assertTrue(flag.matches("2.0"))
+        self.assertFalse(flag.matches("3.0"))
+
+        flag = VersionFlag("flag")
+        flag.add_definition("flag>=2.0")
+        self.assertEqual(str(flag), "flag>=2.0")
+        self.assertFalse(flag.matches("1.0"))
+        self.assertTrue(flag.matches("2.0"))
+        self.assertTrue(flag.matches("3.0"))
+
+        flag.add_definition("flag<1.10")
+        self.assertEqual(str(flag), "flag>=2.0 flag<1.10")
+        self.assertTrue(flag.matches("1.0"))
+        self.assertTrue(flag.matches("1.9"))
+        self.assertFalse(flag.matches("1.10"))
+        self.assertFalse(flag.matches("1.20"))
+        self.assertTrue(flag.matches("2.0"))
+        self.assertTrue(flag.matches("3.0"))
+        self.assertRaises(Exception, flag.add_definition, "flag<")
+        self.assertRaises(Exception, flag.add_definition, "flag>")
+        self.assertRaises(Exception, flag.add_definition, "flag>=")
+        self.assertRaises(Exception, flag.add_definition, "flag<=")
+        self.assertRaises(Exception, flag.add_definition, "flag!=1.0")
+
+
+class TestFlags(unittest.TestCase):
+    def setUp(self):
+        self.flags = Flags(
+            "contentaccessible=yes",
+            "appversion>=3.5",
+            "application=foo",
+            "application=bar",
+            "appversion<2.0",
+            "platform",
+            "abi!=Linux_x86-gcc3",
+        )
+
+    def test_flags_str(self):
+        self.assertEqual(
+            str(self.flags),
+            "contentaccessible=yes "
+            + "appversion>=3.5 appversion<2.0 application=foo "
+            + "application=bar platform abi!=Linux_x86-gcc3",
+        )
+
+    def test_flags_match_unset(self):
+        self.assertTrue(self.flags.match(os="WINNT"))
+
+    def test_flags_match(self):
+        self.assertTrue(self.flags.match(application="foo"))
+        self.assertFalse(self.flags.match(application="qux"))
+
+    def test_flags_match_different(self):
+        self.assertTrue(self.flags.match(abi="WINNT_x86-MSVC"))
+        self.assertFalse(self.flags.match(abi="Linux_x86-gcc3"))
+
+    def test_flags_match_version(self):
+        self.assertTrue(self.flags.match(appversion="1.0"))
+        self.assertTrue(self.flags.match(appversion="1.5"))
+        self.assertFalse(self.flags.match(appversion="2.0"))
+        self.assertFalse(self.flags.match(appversion="3.0"))
+        self.assertTrue(self.flags.match(appversion="3.5"))
+        self.assertTrue(self.flags.match(appversion="3.10"))
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_chrome_manifest.py b/python/mozbuild/mozpack/test/test_chrome_manifest.py
new file mode 100644
index 0000000000..c1d5826bbc
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_chrome_manifest.py
@@ -0,0 +1,176 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import unittest
+
+import mozunit
+
+from mozpack.chrome.manifest import (
+    MANIFESTS_TYPES,
+    Manifest,
+    ManifestBinaryComponent,
+    ManifestCategory,
+    ManifestComponent,
+    ManifestContent,
+    ManifestContract,
+    ManifestInterfaces,
+    ManifestLocale,
+    ManifestOverlay,
+    ManifestOverride,
+    ManifestResource,
+    ManifestSkin,
+    ManifestStyle,
+    parse_manifest,
+    parse_manifest_line,
+)
+from mozpack.errors import AccumulatedErrors, errors
+from test_errors import TestErrors
+
+
+class TestManifest(unittest.TestCase):
+    def test_parse_manifest(self):
+        manifest = [
+            "content global content/global/",
+            "content global content/global/ application=foo application=bar"
+            + " platform",
+            "locale global en-US content/en-US/",
+            "locale global en-US content/en-US/ application=foo",
+            "skin global classic/1.0 content/skin/classic/",
+            "skin global classic/1.0 content/skin/classic/ application=foo"
+            + " os=WINNT",
+            "",
+            "manifest pdfjs/chrome.manifest",
+            "resource gre-resources toolkit/res/",
+            "override chrome://global/locale/netError.dtd"
+            + " chrome://browser/locale/netError.dtd",
+            "# Comment",
+            "component {b2bba4df-057d-41ea-b6b1-94a10a8ede68} foo.js",
+            "contract @mozilla.org/foo;1" + " {b2bba4df-057d-41ea-b6b1-94a10a8ede68}",
+            "interfaces foo.xpt",
+            "binary-component bar.so",
+            "category command-line-handler m-browser"
+            + " @mozilla.org/browser/clh;1"
+            + " application={ec8030f7-c20a-464f-9b0e-13a3a9e97384}",
+            "style chrome://global/content/viewSource.xul" + " chrome://browser/skin/",
+            "overlay chrome://global/content/viewSource.xul"
+            + " chrome://browser/content/viewSourceOverlay.xul",
+        ]
+        other_manifest = ["content global content/global/"]
+        expected_result = [
+            ManifestContent("", "global", "content/global/"),
+            ManifestContent(
+                "",
+                "global",
+                "content/global/",
+                "application=foo",
+                "application=bar",
+                "platform",
+            ),
+            ManifestLocale("", "global", "en-US", "content/en-US/"),
+            ManifestLocale("", "global", "en-US", "content/en-US/", "application=foo"),
+            ManifestSkin("", "global", "classic/1.0", "content/skin/classic/"),
+            ManifestSkin(
+                "",
+                "global",
+                "classic/1.0",
+                "content/skin/classic/",
+                "application=foo",
+                "os=WINNT",
+            ),
+            Manifest("", "pdfjs/chrome.manifest"),
+            ManifestResource("", "gre-resources", "toolkit/res/"),
+            ManifestOverride(
+                "",
+                "chrome://global/locale/netError.dtd",
+                "chrome://browser/locale/netError.dtd",
+            ),
+            ManifestComponent("", "{b2bba4df-057d-41ea-b6b1-94a10a8ede68}", "foo.js"),
+            ManifestContract(
+                "", "@mozilla.org/foo;1", "{b2bba4df-057d-41ea-b6b1-94a10a8ede68}"
+            ),
+            ManifestInterfaces("", "foo.xpt"),
+            ManifestBinaryComponent("", "bar.so"),
+            ManifestCategory(
+                "",
+                "command-line-handler",
+                "m-browser",
+                "@mozilla.org/browser/clh;1",
+                "application=" + "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}",
+            ),
+            ManifestStyle(
+                "", "chrome://global/content/viewSource.xul", "chrome://browser/skin/"
+            ),
+            ManifestOverlay(
+                "",
+                "chrome://global/content/viewSource.xul",
+                "chrome://browser/content/viewSourceOverlay.xul",
+            ),
+        ]
+        with mozunit.MockedOpen(
+            {
+                "manifest": "\n".join(manifest),
+                "other/manifest": "\n".join(other_manifest),
+            }
+        ):
+            # Ensure we have tests for all types of manifests.
+            self.assertEqual(
+                set(type(e) for e in expected_result), set(MANIFESTS_TYPES.values())
+            )
+            self.assertEqual(
+                list(parse_manifest(os.curdir, "manifest")), expected_result
+            )
+            self.assertEqual(
+                list(parse_manifest(os.curdir, "other/manifest")),
+                [ManifestContent("other", "global", "content/global/")],
+            )
+
+    def test_manifest_rebase(self):
+        m = parse_manifest_line("chrome", "content global content/global/")
+        m = m.rebase("")
+        self.assertEqual(str(m), "content global chrome/content/global/")
+        m = m.rebase("chrome")
+        self.assertEqual(str(m), "content global content/global/")
+
+        m = parse_manifest_line("chrome/foo", "content global content/global/")
+        m = m.rebase("chrome")
+        self.assertEqual(str(m), "content global foo/content/global/")
+        m = m.rebase("chrome/foo")
+        self.assertEqual(str(m), "content global content/global/")
+
+        m = parse_manifest_line("modules/foo", "resource foo ./")
+        m = m.rebase("modules")
+        self.assertEqual(str(m), "resource foo foo/")
+        m = m.rebase("modules/foo")
+        self.assertEqual(str(m), "resource foo ./")
+
+        m = parse_manifest_line("chrome", "content browser browser/content/")
+        m = m.rebase("chrome/browser").move("jar:browser.jar!").rebase("")
+        self.assertEqual(str(m), "content browser jar:browser.jar!/content/")
+
+
+class TestManifestErrors(TestErrors, unittest.TestCase):
+    def test_parse_manifest_errors(self):
+        manifest = [
+            "skin global classic/1.0 content/skin/classic/ platform",
+            "",
+            "binary-component bar.so",
+            "unsupported foo",
+        ]
+        with mozunit.MockedOpen({"manifest": "\n".join(manifest)}):
+            with self.assertRaises(AccumulatedErrors):
+                with errors.accumulate():
+                    list(parse_manifest(os.curdir, "manifest"))
+            out = self.get_output()
+            # Expecting 2 errors
+            self.assertEqual(len(out), 2)
+            path = os.path.abspath("manifest")
+            # First on line 1
+            self.assertTrue(out[0].startswith("error: %s:1: " % path))
+            # Second on line 4
+            self.assertTrue(out[1].startswith("error: %s:4: " % path))
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_copier.py b/python/mozbuild/mozpack/test/test_copier.py
new file mode 100644
index 0000000000..60ebd2c1e9
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_copier.py
@@ -0,0 +1,548 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import stat
+import unittest
+
+import mozunit
+import six
+
+import mozpack.path as mozpath
+from mozpack.copier import FileCopier, FileRegistry, FileRegistrySubtree, Jarrer
+from mozpack.errors import ErrorMessage
+from mozpack.files import ExistingFile, GeneratedFile
+from mozpack.mozjar import JarReader
+from mozpack.test.test_files import MatchTestTemplate, MockDest, TestWithTmpDir
+
+
+class BaseTestFileRegistry(MatchTestTemplate):
+    def add(self, path):
+        self.registry.add(path, GeneratedFile(path))
+
+    def do_check(self, pattern, result):
+        self.checked = True
+        if result:
+            self.assertTrue(self.registry.contains(pattern))
+        else:
+            self.assertFalse(self.registry.contains(pattern))
+        self.assertEqual(self.registry.match(pattern), result)
+
+    def do_test_file_registry(self, registry):
+        self.registry = registry
+        self.registry.add("foo", GeneratedFile(b"foo"))
+        bar = GeneratedFile(b"bar")
+        self.registry.add("bar", bar)
+        self.assertEqual(self.registry.paths(), ["foo", "bar"])
+        self.assertEqual(self.registry["bar"], bar)
+
+        self.assertRaises(
+            ErrorMessage, self.registry.add, "foo", GeneratedFile(b"foo2")
+        )
+
+        self.assertRaises(ErrorMessage, self.registry.remove, "qux")
+
+        self.assertRaises(
+            ErrorMessage, self.registry.add, "foo/bar", GeneratedFile(b"foobar")
+        )
+        self.assertRaises(
+            ErrorMessage, self.registry.add, "foo/bar/baz", GeneratedFile(b"foobar")
+        )
+
+        self.assertEqual(self.registry.paths(), ["foo", "bar"])
+
+        self.registry.remove("foo")
+        self.assertEqual(self.registry.paths(), ["bar"])
+        self.registry.remove("bar")
+        self.assertEqual(self.registry.paths(), [])
+
+        self.prepare_match_test()
+        self.do_match_test()
+        self.assertTrue(self.checked)
+        self.assertEqual(
+            self.registry.paths(),
+            [
+                "bar",
+                "foo/bar",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/bar",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+            ],
+        )
+
+        self.registry.remove("foo/qux")
+        self.assertEqual(self.registry.paths(), ["bar", "foo/bar", "foo/baz"])
+
+        self.registry.add("foo/qux", GeneratedFile(b"fooqux"))
+        self.assertEqual(
+            self.registry.paths(), ["bar", "foo/bar", "foo/baz", "foo/qux"]
+        )
+        self.registry.remove("foo/b*")
+        self.assertEqual(self.registry.paths(), ["bar", "foo/qux"])
+
+        self.assertEqual([f for f, c in self.registry], ["bar", "foo/qux"])
+        self.assertEqual(len(self.registry), 2)
+
+        self.add("foo/.foo")
+        self.assertTrue(self.registry.contains("foo/.foo"))
+
+    def do_test_registry_paths(self, registry):
+        self.registry = registry
+
+        # Can't add a file if it requires a directory in place of a
+        # file we also require.
+        self.registry.add("foo", GeneratedFile(b"foo"))
+        self.assertRaises(
+            ErrorMessage, self.registry.add, "foo/bar", GeneratedFile(b"foobar")
+        )
+
+        # Can't add a file if we already have a directory there.
+        self.registry.add("bar/baz", GeneratedFile(b"barbaz"))
+        self.assertRaises(ErrorMessage, self.registry.add, "bar", GeneratedFile(b"bar"))
+
+        # Bump the count of things that require bar/ to 2.
+        self.registry.add("bar/zot", GeneratedFile(b"barzot"))
+        self.assertRaises(ErrorMessage, self.registry.add, "bar", GeneratedFile(b"bar"))
+
+        # Drop the count of things that require bar/ to 1.
+        self.registry.remove("bar/baz")
+        self.assertRaises(ErrorMessage, self.registry.add, "bar", GeneratedFile(b"bar"))
+
+        # Drop the count of things that require bar/ to 0.
+        self.registry.remove("bar/zot")
+        self.registry.add("bar/zot", GeneratedFile(b"barzot"))
+
+
+class TestFileRegistry(BaseTestFileRegistry, unittest.TestCase):
+    def test_partial_paths(self):
+        cases = {
+            "foo/bar/baz/zot": ["foo/bar/baz", "foo/bar", "foo"],
+            "foo/bar": ["foo"],
+            "bar": [],
+        }
+        reg = FileRegistry()
+        for path, parts in six.iteritems(cases):
+            self.assertEqual(reg._partial_paths(path), parts)
+
+    def test_file_registry(self):
+        self.do_test_file_registry(FileRegistry())
+
+    def test_registry_paths(self):
+        self.do_test_registry_paths(FileRegistry())
+
+    def test_required_directories(self):
+        self.registry = FileRegistry()
+
+        self.registry.add("foo", GeneratedFile(b"foo"))
+        self.assertEqual(self.registry.required_directories(), set())
+
+        self.registry.add("bar/baz", GeneratedFile(b"barbaz"))
+        self.assertEqual(self.registry.required_directories(), {"bar"})
+
+        self.registry.add("bar/zot", GeneratedFile(b"barzot"))
+        self.assertEqual(self.registry.required_directories(), {"bar"})
+
+        self.registry.add("bar/zap/zot", GeneratedFile(b"barzapzot"))
+        self.assertEqual(self.registry.required_directories(), {"bar", "bar/zap"})
+
+        self.registry.remove("bar/zap/zot")
+        self.assertEqual(self.registry.required_directories(), {"bar"})
+
+        self.registry.remove("bar/baz")
+        self.assertEqual(self.registry.required_directories(), {"bar"})
+
+        self.registry.remove("bar/zot")
+        self.assertEqual(self.registry.required_directories(), set())
+
+        self.registry.add("x/y/z", GeneratedFile(b"xyz"))
+        self.assertEqual(self.registry.required_directories(), {"x", "x/y"})
+
+
+class TestFileRegistrySubtree(BaseTestFileRegistry, unittest.TestCase):
+    def test_file_registry_subtree_base(self):
+        registry = FileRegistry()
+        self.assertEqual(registry, FileRegistrySubtree("", registry))
+        self.assertNotEqual(registry, FileRegistrySubtree("base", registry))
+
+    def create_registry(self):
+        registry = FileRegistry()
+        registry.add("foo/bar", GeneratedFile(b"foo/bar"))
+        registry.add("baz/qux", GeneratedFile(b"baz/qux"))
+        return FileRegistrySubtree("base/root", registry)
+
+    def test_file_registry_subtree(self):
+        self.do_test_file_registry(self.create_registry())
+
+    def test_registry_paths_subtree(self):
+        FileRegistry()
+        self.do_test_registry_paths(self.create_registry())
+
+
+class TestFileCopier(TestWithTmpDir):
+    def all_dirs(self, base):
+        all_dirs = set()
+        for root, dirs, files in os.walk(base):
+            if not dirs:
+                all_dirs.add(mozpath.relpath(root, base))
+        return all_dirs
+
+    def all_files(self, base):
+        all_files = set()
+        for root, dirs, files in os.walk(base):
+            for f in files:
+                all_files.add(mozpath.join(mozpath.relpath(root, base), f))
+        return all_files
+
+    def test_file_copier(self):
+        copier = FileCopier()
+        copier.add("foo/bar", GeneratedFile(b"foobar"))
+        copier.add("foo/qux", GeneratedFile(b"fooqux"))
+        copier.add("foo/deep/nested/directory/file", GeneratedFile(b"fooz"))
+        copier.add("bar", GeneratedFile(b"bar"))
+        copier.add("qux/foo", GeneratedFile(b"quxfoo"))
+        copier.add("qux/bar", GeneratedFile(b""))
+
+        result = copier.copy(self.tmpdir)
+        self.assertEqual(self.all_files(self.tmpdir), set(copier.paths()))
+        self.assertEqual(
+            self.all_dirs(self.tmpdir), set(["foo/deep/nested/directory", "qux"])
+        )
+
+        self.assertEqual(
+            result.updated_files,
+            set(self.tmppath(p) for p in self.all_files(self.tmpdir)),
+        )
+        self.assertEqual(result.existing_files, set())
+        self.assertEqual(result.removed_files, set())
+        self.assertEqual(result.removed_directories, set())
+
+        copier.remove("foo")
+        copier.add("test", GeneratedFile(b"test"))
+        result = copier.copy(self.tmpdir)
+        self.assertEqual(self.all_files(self.tmpdir), set(copier.paths()))
+        self.assertEqual(self.all_dirs(self.tmpdir), set(["qux"]))
+        self.assertEqual(
+            result.removed_files,
+            set(
+                self.tmppath(p)
+                for p in ("foo/bar", "foo/qux", "foo/deep/nested/directory/file")
+            ),
+        )
+
+    def test_symlink_directory_replaced(self):
+        """Directory symlinks in destination are replaced if they need to be
+        real directories."""
+        if not self.symlink_supported:
+            return
+
+        dest = self.tmppath("dest")
+
+        copier = FileCopier()
+        copier.add("foo/bar/baz", GeneratedFile(b"foobarbaz"))
+
+        os.makedirs(self.tmppath("dest/foo"))
+        dummy = self.tmppath("dummy")
+        os.mkdir(dummy)
+        link = self.tmppath("dest/foo/bar")
+        os.symlink(dummy, link)
+
+        result = copier.copy(dest)
+
+        st = os.lstat(link)
+        self.assertFalse(stat.S_ISLNK(st.st_mode))
+        self.assertTrue(stat.S_ISDIR(st.st_mode))
+
+        self.assertEqual(self.all_files(dest), set(copier.paths()))
+
+        self.assertEqual(result.removed_directories, set())
+        self.assertEqual(len(result.updated_files), 1)
+
+    def test_remove_unaccounted_directory_symlinks(self):
+        """Directory symlinks in destination that are not in the way are
+        deleted according to remove_unaccounted and
+        remove_all_directory_symlinks.
+        """
+        if not self.symlink_supported:
+            return
+
+        dest = self.tmppath("dest")
+
+        copier = FileCopier()
+        copier.add("foo/bar/baz", GeneratedFile(b"foobarbaz"))
+
+        os.makedirs(self.tmppath("dest/foo"))
+        dummy = self.tmppath("dummy")
+        os.mkdir(dummy)
+
+        os.mkdir(self.tmppath("dest/zot"))
+        link = self.tmppath("dest/zot/zap")
+        os.symlink(dummy, link)
+
+        # If not remove_unaccounted but remove_empty_directories, then
+        # the symlinked directory remains (as does its containing
+        # directory).
+        result = copier.copy(
+            dest,
+            remove_unaccounted=False,
+            remove_empty_directories=True,
+            remove_all_directory_symlinks=False,
+        )
+
+        st = os.lstat(link)
+        self.assertTrue(stat.S_ISLNK(st.st_mode))
+        self.assertFalse(stat.S_ISDIR(st.st_mode))
+
+        self.assertEqual(self.all_files(dest), set(copier.paths()))
+        self.assertEqual(self.all_dirs(dest), set(["foo/bar"]))
+
+        self.assertEqual(result.removed_directories, set())
+        self.assertEqual(len(result.updated_files), 1)
+
+        # If remove_unaccounted but not remove_empty_directories, then
+        # only the symlinked directory is removed.
+        result = copier.copy(
+            dest,
+            remove_unaccounted=True,
+            remove_empty_directories=False,
+            remove_all_directory_symlinks=False,
+        )
+
+        st = os.lstat(self.tmppath("dest/zot"))
+        self.assertFalse(stat.S_ISLNK(st.st_mode))
+        self.assertTrue(stat.S_ISDIR(st.st_mode))
+
+        self.assertEqual(result.removed_files, set([link]))
+        self.assertEqual(result.removed_directories, set())
+
+        self.assertEqual(self.all_files(dest), set(copier.paths()))
+        self.assertEqual(self.all_dirs(dest), set(["foo/bar", "zot"]))
+
+        # If remove_unaccounted and remove_empty_directories, then
+        # both the symlink and its containing directory are removed.
+        link = self.tmppath("dest/zot/zap")
+        os.symlink(dummy, link)
+
+        result = copier.copy(
+            dest,
+            remove_unaccounted=True,
+            remove_empty_directories=True,
+            remove_all_directory_symlinks=False,
+        )
+
+        self.assertEqual(result.removed_files, set([link]))
+        self.assertEqual(result.removed_directories, set([self.tmppath("dest/zot")]))
+
+        self.assertEqual(self.all_files(dest), set(copier.paths()))
+        self.assertEqual(self.all_dirs(dest), set(["foo/bar"]))
+
+    def test_permissions(self):
+        """Ensure files without write permission can be deleted."""
+        with open(self.tmppath("dummy"), "a"):
+            pass
+
+        p = self.tmppath("no_perms")
+        with open(p, "a"):
+            pass
+
+        # Make file and directory unwritable. Reminder: making a directory
+        # unwritable prevents modifications (including deletes) from the list
+        # of files in that directory.
+        os.chmod(p, 0o400)
+        os.chmod(self.tmpdir, 0o400)
+
+        copier = FileCopier()
+        copier.add("dummy", GeneratedFile(b"content"))
+        result = copier.copy(self.tmpdir)
+        self.assertEqual(result.removed_files_count, 1)
+        self.assertFalse(os.path.exists(p))
+
+    def test_no_remove(self):
+        copier = FileCopier()
+        copier.add("foo", GeneratedFile(b"foo"))
+
+        with open(self.tmppath("bar"), "a"):
+            pass
+
+        os.mkdir(self.tmppath("emptydir"))
+        d = self.tmppath("populateddir")
+        os.mkdir(d)
+
+        with open(self.tmppath("populateddir/foo"), "a"):
+            pass
+
+        result = copier.copy(self.tmpdir, remove_unaccounted=False)
+
+        self.assertEqual(
+            self.all_files(self.tmpdir), set(["foo", "bar", "populateddir/foo"])
+        )
+        self.assertEqual(self.all_dirs(self.tmpdir), set(["populateddir"]))
+        self.assertEqual(result.removed_files, set())
+        self.assertEqual(result.removed_directories, set([self.tmppath("emptydir")]))
+
+    def test_no_remove_empty_directories(self):
+        copier = FileCopier()
+        copier.add("foo", GeneratedFile(b"foo"))
+
+        with open(self.tmppath("bar"), "a"):
+            pass
+
+        os.mkdir(self.tmppath("emptydir"))
+        d = self.tmppath("populateddir")
+        os.mkdir(d)
+
+        with open(self.tmppath("populateddir/foo"), "a"):
+            pass
+
+        result = copier.copy(
+            self.tmpdir, remove_unaccounted=False, remove_empty_directories=False
+        )
+
+        self.assertEqual(
+            self.all_files(self.tmpdir), set(["foo", "bar", "populateddir/foo"])
+        )
+        self.assertEqual(self.all_dirs(self.tmpdir), set(["emptydir", "populateddir"]))
+        self.assertEqual(result.removed_files, set())
+        self.assertEqual(result.removed_directories, set())
+
+    def test_optional_exists_creates_unneeded_directory(self):
+        """Demonstrate that a directory not strictly required, but specified
+        as the path to an optional file, will be unnecessarily created.
+
+        This behaviour is wrong; fixing it is tracked by Bug 972432;
+        and this test exists to guard against unexpected changes in
+        behaviour.
+        """
+
+        dest = self.tmppath("dest")
+
+        copier = FileCopier()
+        copier.add("foo/bar", ExistingFile(required=False))
+
+        result = copier.copy(dest)
+
+        st = os.lstat(self.tmppath("dest/foo"))
+        self.assertFalse(stat.S_ISLNK(st.st_mode))
+        self.assertTrue(stat.S_ISDIR(st.st_mode))
+
+        # What's worse, we have no record that dest was created.
+        self.assertEqual(len(result.updated_files), 0)
+
+        # But we do have an erroneous record of an optional file
+        # existing when it does not.
+        self.assertIn(self.tmppath("dest/foo/bar"), result.existing_files)
+
+    def test_remove_unaccounted_file_registry(self):
+        """Test FileCopier.copy(remove_unaccounted=FileRegistry())"""
+
+        dest = self.tmppath("dest")
+
+        copier = FileCopier()
+        copier.add("foo/bar/baz", GeneratedFile(b"foobarbaz"))
+        copier.add("foo/bar/qux", GeneratedFile(b"foobarqux"))
+        copier.add("foo/hoge/fuga", GeneratedFile(b"foohogefuga"))
+        copier.add("foo/toto/tata", GeneratedFile(b"footototata"))
+
+        os.makedirs(os.path.join(dest, "bar"))
+        with open(os.path.join(dest, "bar", "bar"), "w") as fh:
+            fh.write("barbar")
+        os.makedirs(os.path.join(dest, "foo", "toto"))
+        with open(os.path.join(dest, "foo", "toto", "toto"), "w") as fh:
+            fh.write("foototototo")
+
+        result = copier.copy(dest, remove_unaccounted=False)
+
+        self.assertEqual(
+            self.all_files(dest), set(copier.paths()) | {"foo/toto/toto", "bar/bar"}
+        )
+        self.assertEqual(
+            self.all_dirs(dest), {"foo/bar", "foo/hoge", "foo/toto", "bar"}
+        )
+
+        copier2 = FileCopier()
+        copier2.add("foo/hoge/fuga", GeneratedFile(b"foohogefuga"))
+
+        # We expect only files copied from the first copier to be removed,
+        # not the extra file that was there beforehand.
+        result = copier2.copy(dest, remove_unaccounted=copier)
+
+        self.assertEqual(
+            self.all_files(dest), set(copier2.paths()) | {"foo/toto/toto", "bar/bar"}
+        )
+        self.assertEqual(self.all_dirs(dest), {"foo/hoge", "foo/toto", "bar"})
+        self.assertEqual(result.updated_files, {self.tmppath("dest/foo/hoge/fuga")})
+        self.assertEqual(result.existing_files, set())
+        self.assertEqual(
+            result.removed_files,
+            {
+                self.tmppath(p)
+                for p in ("dest/foo/bar/baz", "dest/foo/bar/qux", "dest/foo/toto/tata")
+            },
+        )
+        self.assertEqual(result.removed_directories, {self.tmppath("dest/foo/bar")})
+
+
+class TestJarrer(unittest.TestCase):
+    def check_jar(self, dest, copier):
+        jar = JarReader(fileobj=dest)
+        self.assertEqual([f.filename for f in jar], copier.paths())
+        for f in jar:
+            self.assertEqual(f.uncompressed_data.read(), copier[f.filename].content)
+
+    def test_jarrer(self):
+        copier = Jarrer()
+        copier.add("foo/bar", GeneratedFile(b"foobar"))
+        copier.add("foo/qux", GeneratedFile(b"fooqux"))
+        copier.add("foo/deep/nested/directory/file", GeneratedFile(b"fooz"))
+        copier.add("bar", GeneratedFile(b"bar"))
+        copier.add("qux/foo", GeneratedFile(b"quxfoo"))
+        copier.add("qux/bar", GeneratedFile(b""))
+
+        dest = MockDest()
+        copier.copy(dest)
+        self.check_jar(dest, copier)
+
+        copier.remove("foo")
+        copier.add("test", GeneratedFile(b"test"))
+        copier.copy(dest)
+        self.check_jar(dest, copier)
+
+        copier.remove("test")
+        copier.add("test", GeneratedFile(b"replaced-content"))
+        copier.copy(dest)
+        self.check_jar(dest, copier)
+
+        copier.copy(dest)
+        self.check_jar(dest, copier)
+
+        preloaded = ["qux/bar", "bar"]
+        copier.preload(preloaded)
+        copier.copy(dest)
+
+        dest.seek(0)
+        jar = JarReader(fileobj=dest)
+        self.assertEqual(
+            [f.filename for f in jar],
+            preloaded + [p for p in copier.paths() if p not in preloaded],
+        )
+        self.assertEqual(jar.last_preloaded, preloaded[-1])
+
+    def test_jarrer_compress(self):
+        copier = Jarrer()
+        copier.add("foo/bar", GeneratedFile(b"ffffff"))
+        copier.add("foo/qux", GeneratedFile(b"ffffff"), compress=False)
+
+        dest = MockDest()
+        copier.copy(dest)
+        self.check_jar(dest, copier)
+
+        dest.seek(0)
+        jar = JarReader(fileobj=dest)
+        self.assertTrue(jar["foo/bar"].compressed)
+        self.assertFalse(jar["foo/qux"].compressed)
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_errors.py b/python/mozbuild/mozpack/test/test_errors.py
new file mode 100644
index 0000000000..411b1b54c3
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_errors.py
@@ -0,0 +1,95 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import sys
+import unittest
+
+import mozunit
+import six
+
+from mozpack.errors import AccumulatedErrors, ErrorMessage, errors
+
+
+class TestErrors(object):
+    def setUp(self):
+        errors.out = six.moves.cStringIO()
+        errors.ignore_errors(False)
+
+    def tearDown(self):
+        errors.out = sys.stderr
+
+    def get_output(self):
+        return [l.strip() for l in errors.out.getvalue().splitlines()]
+
+
+class TestErrorsImpl(TestErrors, unittest.TestCase):
+    def test_plain_error(self):
+        errors.warn("foo")
+        self.assertRaises(ErrorMessage, errors.error, "foo")
+        self.assertRaises(ErrorMessage, errors.fatal, "foo")
+        self.assertEqual(self.get_output(), ["warning: foo"])
+
+    def test_ignore_errors(self):
+        errors.ignore_errors()
+        errors.warn("foo")
+        errors.error("bar")
+        self.assertRaises(ErrorMessage, errors.fatal, "foo")
+        self.assertEqual(self.get_output(), ["warning: foo", "warning: bar"])
+
+    def test_no_error(self):
+        with errors.accumulate():
+            errors.warn("1")
+
+    def test_simple_error(self):
+        with self.assertRaises(AccumulatedErrors):
+            with errors.accumulate():
+                errors.error("1")
+        self.assertEqual(self.get_output(), ["error: 1"])
+
+    def test_error_loop(self):
+        with self.assertRaises(AccumulatedErrors):
+            with errors.accumulate():
+                for i in range(3):
+                    errors.error("%d" % i)
+        self.assertEqual(self.get_output(), ["error: 0", "error: 1", "error: 2"])
+
+    def test_multiple_errors(self):
+        with self.assertRaises(AccumulatedErrors):
+            with errors.accumulate():
+                errors.error("foo")
+                for i in range(3):
+                    if i == 2:
+                        errors.warn("%d" % i)
+                    else:
+                        errors.error("%d" % i)
+                errors.error("bar")
+        self.assertEqual(
+            self.get_output(),
+            ["error: foo", "error: 0", "error: 1", "warning: 2", "error: bar"],
+        )
+
+    def test_errors_context(self):
+        with self.assertRaises(AccumulatedErrors):
+            with errors.accumulate():
+                self.assertEqual(errors.get_context(), None)
+                with errors.context("foo", 1):
+                    self.assertEqual(errors.get_context(), ("foo", 1))
+                    errors.error("a")
+                    with errors.context("bar", 2):
+                        self.assertEqual(errors.get_context(), ("bar", 2))
+                        errors.error("b")
+                    self.assertEqual(errors.get_context(), ("foo", 1))
+                    errors.error("c")
+        self.assertEqual(
+            self.get_output(),
+            [
+                "error: foo:1: a",
+                "error: bar:2: b",
+                "error: foo:1: c",
+            ],
+        )
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_files.py b/python/mozbuild/mozpack/test/test_files.py
new file mode 100644
index 0000000000..1c86f2e0cc
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_files.py
@@ -0,0 +1,1362 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from mozbuild.util import ensure_bytes, ensureParentDir
+from mozpack.errors import ErrorMessage, errors
+from mozpack.files import (
+    AbsoluteSymlinkFile,
+    ComposedFinder,
+    DeflatedFile,
+    Dest,
+    ExistingFile,
+    ExtractedTarFile,
+    File,
+    FileFinder,
+    GeneratedFile,
+    HardlinkFile,
+    JarFinder,
+    ManifestFile,
+    MercurialFile,
+    MercurialRevisionFinder,
+    MinifiedCommentStripped,
+    MinifiedJavaScript,
+    PreprocessedFile,
+    TarFinder,
+)
+
+# We don't have hglib installed everywhere.
+try:
+    import hglib
+except ImportError:
+    hglib = None
+
+import os
+import platform
+import random
+import sys
+import tarfile
+import unittest
+from io import BytesIO
+from tempfile import mkdtemp
+
+import mozfile
+import mozunit
+import six
+
+import mozpack.path as mozpath
+from mozpack.chrome.manifest import (
+    ManifestContent,
+    ManifestLocale,
+    ManifestOverride,
+    ManifestResource,
+)
+from mozpack.mozjar import JarReader, JarWriter
+
+
+class TestWithTmpDir(unittest.TestCase):
+    def setUp(self):
+        self.tmpdir = mkdtemp()
+
+        self.symlink_supported = False
+        self.hardlink_supported = False
+
+        # See comment in mozpack.files.AbsoluteSymlinkFile
+        if hasattr(os, "symlink") and platform.system() != "Windows":
+            dummy_path = self.tmppath("dummy_file")
+            with open(dummy_path, "a"):
+                pass
+
+            try:
+                os.symlink(dummy_path, self.tmppath("dummy_symlink"))
+                os.remove(self.tmppath("dummy_symlink"))
+            except EnvironmentError:
+                pass
+            finally:
+                os.remove(dummy_path)
+
+            self.symlink_supported = True
+
+        if hasattr(os, "link"):
+            dummy_path = self.tmppath("dummy_file")
+            with open(dummy_path, "a"):
+                pass
+
+            try:
+                os.link(dummy_path, self.tmppath("dummy_hardlink"))
+                os.remove(self.tmppath("dummy_hardlink"))
+            except EnvironmentError:
+                pass
+            finally:
+                os.remove(dummy_path)
+
+            self.hardlink_supported = True
+
+    def tearDown(self):
+        mozfile.rmtree(self.tmpdir)
+
+    def tmppath(self, relpath):
+        return os.path.normpath(os.path.join(self.tmpdir, relpath))
+
+
+class MockDest(BytesIO, Dest):
+    def __init__(self):
+        BytesIO.__init__(self)
+        self.mode = None
+
+    def read(self, length=-1):
+        if self.mode != "r":
+            self.seek(0)
+            self.mode = "r"
+        return BytesIO.read(self, length)
+
+    def write(self, data):
+        if self.mode != "w":
+            self.seek(0)
+            self.truncate(0)
+            self.mode = "w"
+        return BytesIO.write(self, data)
+
+    def exists(self):
+        return True
+
+    def close(self):
+        if self.mode:
+            self.mode = None
+
+
+class DestNoWrite(Dest):
+    def write(self, data):
+        raise RuntimeError
+
+
+class TestDest(TestWithTmpDir):
+    def test_dest(self):
+        dest = Dest(self.tmppath("dest"))
+        self.assertFalse(dest.exists())
+        dest.write(b"foo")
+        self.assertTrue(dest.exists())
+        dest.write(b"foo")
+        self.assertEqual(dest.read(4), b"foof")
+        self.assertEqual(dest.read(), b"oo")
+        self.assertEqual(dest.read(), b"")
+        dest.write(b"bar")
+        self.assertEqual(dest.read(4), b"bar")
+        dest.close()
+        self.assertEqual(dest.read(), b"bar")
+        dest.write(b"foo")
+        dest.close()
+        dest.write(b"qux")
+        self.assertEqual(dest.read(), b"qux")
+
+
+rand = bytes(
+    random.choice(b"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+    for i in six.moves.xrange(131597)
+)
+samples = [
+    b"",
+    b"test",
+    b"fooo",
+    b"same",
+    b"same",
+    b"Different and longer",
+    rand,
+    rand,
+    rand[:-1] + b"_",
+    b"test",
+]
+
+
+class TestFile(TestWithTmpDir):
+    def test_file(self):
+        """
+        Check that File.copy yields the proper content in the destination file
+        in all situations that trigger different code paths:
+        - different content
+        - different content of the same size
+        - same content
+        - long content
+        """
+        src = self.tmppath("src")
+        dest = self.tmppath("dest")
+
+        for content in samples:
+            with open(src, "wb") as tmp:
+                tmp.write(content)
+            # Ensure the destination file, when it exists, is older than the
+            # source
+            if os.path.exists(dest):
+                time = os.path.getmtime(src) - 1
+                os.utime(dest, (time, time))
+            f = File(src)
+            f.copy(dest)
+            self.assertEqual(content, open(dest, "rb").read())
+            self.assertEqual(content, f.open().read())
+            self.assertEqual(content, f.open().read())
+
+    def test_file_dest(self):
+        """
+        Similar to test_file, but for a destination object instead of
+        a destination file. This ensures the destination object is being
+        used properly by File.copy, ensuring that other subclasses of Dest
+        will work.
+        """
+        src = self.tmppath("src")
+        dest = MockDest()
+
+        for content in samples:
+            with open(src, "wb") as tmp:
+                tmp.write(content)
+            f = File(src)
+            f.copy(dest)
+            self.assertEqual(content, dest.getvalue())
+
+    def test_file_open(self):
+        """
+        Test whether File.open returns an appropriately reset file object.
+        """
+        src = self.tmppath("src")
+        content = b"".join(samples)
+        with open(src, "wb") as tmp:
+            tmp.write(content)
+
+        f = File(src)
+        self.assertEqual(content[:42], f.open().read(42))
+        self.assertEqual(content, f.open().read())
+
+    def test_file_no_write(self):
+        """
+        Test various conditions where File.copy is expected not to write
+        in the destination file.
+        """
+        src = self.tmppath("src")
+        dest = self.tmppath("dest")
+
+        with open(src, "wb") as tmp:
+            tmp.write(b"test")
+
+        # Initial copy
+        f = File(src)
+        f.copy(dest)
+
+        # Ensure subsequent copies won't trigger writes
+        f.copy(DestNoWrite(dest))
+        self.assertEqual(b"test", open(dest, "rb").read())
+
+        # When the source file is newer, but with the same content, no copy
+        # should occur
+        time = os.path.getmtime(src) - 1
+        os.utime(dest, (time, time))
+        f.copy(DestNoWrite(dest))
+        self.assertEqual(b"test", open(dest, "rb").read())
+
+        # When the source file is older than the destination file, even with
+        # different content, no copy should occur.
+        with open(src, "wb") as tmp:
+            tmp.write(b"fooo")
+        time = os.path.getmtime(dest) - 1
+        os.utime(src, (time, time))
+        f.copy(DestNoWrite(dest))
+        self.assertEqual(b"test", open(dest, "rb").read())
+
+        # Double check that under conditions where a copy occurs, we would get
+        # an exception.
+        time = os.path.getmtime(src) - 1
+        os.utime(dest, (time, time))
+        self.assertRaises(RuntimeError, f.copy, DestNoWrite(dest))
+
+        # skip_if_older=False is expected to force a copy in this situation.
+        f.copy(dest, skip_if_older=False)
+        self.assertEqual(b"fooo", open(dest, "rb").read())
+
+
+class TestAbsoluteSymlinkFile(TestWithTmpDir):
+    def test_absolute_relative(self):
+        AbsoluteSymlinkFile("/foo")
+
+        with self.assertRaisesRegexp(ValueError, "Symlink target not absolute"):
+            AbsoluteSymlinkFile("./foo")
+
+    def test_symlink_file(self):
+        source = self.tmppath("test_path")
+        with open(source, "wt") as fh:
+            fh.write("Hello world")
+
+        s = AbsoluteSymlinkFile(source)
+        dest = self.tmppath("symlink")
+        self.assertTrue(s.copy(dest))
+
+        if self.symlink_supported:
+            self.assertTrue(os.path.islink(dest))
+            link = os.readlink(dest)
+            self.assertEqual(link, source)
+        else:
+            self.assertTrue(os.path.isfile(dest))
+            content = open(dest).read()
+            self.assertEqual(content, "Hello world")
+
+    def test_replace_file_with_symlink(self):
+        # If symlinks are supported, an existing file should be replaced by a
+        # symlink.
+        source = self.tmppath("test_path")
+        with open(source, "wt") as fh:
+            fh.write("source")
+
+        dest = self.tmppath("dest")
+        with open(dest, "a"):
+            pass
+
+        s = AbsoluteSymlinkFile(source)
+        s.copy(dest, skip_if_older=False)
+
+        if self.symlink_supported:
+            self.assertTrue(os.path.islink(dest))
+            link = os.readlink(dest)
+            self.assertEqual(link, source)
+        else:
+            self.assertTrue(os.path.isfile(dest))
+            content = open(dest).read()
+            self.assertEqual(content, "source")
+
+    def test_replace_symlink(self):
+        if not self.symlink_supported:
+            return
+
+        source = self.tmppath("source")
+        with open(source, "a"):
+            pass
+
+        dest = self.tmppath("dest")
+
+        os.symlink(self.tmppath("bad"), dest)
+        self.assertTrue(os.path.islink(dest))
+
+        s = AbsoluteSymlinkFile(source)
+        self.assertTrue(s.copy(dest))
+
+        self.assertTrue(os.path.islink(dest))
+        link = os.readlink(dest)
+        self.assertEqual(link, source)
+
+    def test_noop(self):
+        if not hasattr(os, "symlink") or sys.platform == "win32":
+            return
+
+        source = self.tmppath("source")
+        dest = self.tmppath("dest")
+
+        with open(source, "a"):
+            pass
+
+        os.symlink(source, dest)
+        link = os.readlink(dest)
+        self.assertEqual(link, source)
+
+        s = AbsoluteSymlinkFile(source)
+        self.assertFalse(s.copy(dest))
+
+        link = os.readlink(dest)
+        self.assertEqual(link, source)
+
+
+class TestHardlinkFile(TestWithTmpDir):
+    def test_absolute_relative(self):
+        HardlinkFile("/foo")
+        HardlinkFile("./foo")
+
+    def test_hardlink_file(self):
+        source = self.tmppath("test_path")
+        with open(source, "wt") as fh:
+            fh.write("Hello world")
+
+        s = HardlinkFile(source)
+        dest = self.tmppath("hardlink")
+        self.assertTrue(s.copy(dest))
+
+        if self.hardlink_supported:
+            source_stat = os.stat(source)
+            dest_stat = os.stat(dest)
+            self.assertEqual(source_stat.st_dev, dest_stat.st_dev)
+            self.assertEqual(source_stat.st_ino, dest_stat.st_ino)
+        else:
+            self.assertTrue(os.path.isfile(dest))
+            with open(dest) as f:
+                content = f.read()
+            self.assertEqual(content, "Hello world")
+
+    def test_replace_file_with_hardlink(self):
+        # If hardlink are supported, an existing file should be replaced by a
+        # symlink.
+        source = self.tmppath("test_path")
+        with open(source, "wt") as fh:
+            fh.write("source")
+
+        dest = self.tmppath("dest")
+        with open(dest, "a"):
+            pass
+
+        s = HardlinkFile(source)
+        s.copy(dest, skip_if_older=False)
+
+        if self.hardlink_supported:
+            source_stat = os.stat(source)
+            dest_stat = os.stat(dest)
+            self.assertEqual(source_stat.st_dev, dest_stat.st_dev)
+            self.assertEqual(source_stat.st_ino, dest_stat.st_ino)
+        else:
+            self.assertTrue(os.path.isfile(dest))
+            with open(dest) as f:
+                content = f.read()
+            self.assertEqual(content, "source")
+
+    def test_replace_hardlink(self):
+        if not self.hardlink_supported:
+            raise unittest.SkipTest("hardlink not supported")
+
+        source = self.tmppath("source")
+        with open(source, "a"):
+            pass
+
+        dest = self.tmppath("dest")
+
+        os.link(source, dest)
+
+        s = HardlinkFile(source)
+        self.assertFalse(s.copy(dest))
+
+        source_stat = os.lstat(source)
+        dest_stat = os.lstat(dest)
+        self.assertEqual(source_stat.st_dev, dest_stat.st_dev)
+        self.assertEqual(source_stat.st_ino, dest_stat.st_ino)
+
+    def test_noop(self):
+        if not self.hardlink_supported:
+            raise unittest.SkipTest("hardlink not supported")
+
+        source = self.tmppath("source")
+        dest = self.tmppath("dest")
+
+        with open(source, "a"):
+            pass
+
+        os.link(source, dest)
+
+        s = HardlinkFile(source)
+        self.assertFalse(s.copy(dest))
+
+        source_stat = os.lstat(source)
+        dest_stat = os.lstat(dest)
+        self.assertEqual(source_stat.st_dev, dest_stat.st_dev)
+        self.assertEqual(source_stat.st_ino, dest_stat.st_ino)
+
+
+class TestPreprocessedFile(TestWithTmpDir):
+    def test_preprocess(self):
+        """
+        Test that copying the file invokes the preprocessor
+        """
+        src = self.tmppath("src")
+        dest = self.tmppath("dest")
+
+        with open(src, "wb") as tmp:
+            tmp.write(b"#ifdef FOO\ntest\n#endif")
+
+        f = PreprocessedFile(src, depfile_path=None, marker="#", defines={"FOO": True})
+        self.assertTrue(f.copy(dest))
+
+        self.assertEqual(b"test\n", open(dest, "rb").read())
+
+    def test_preprocess_file_no_write(self):
+        """
+        Test various conditions where PreprocessedFile.copy is expected not to
+        write in the destination file.
+        """
+        src = self.tmppath("src")
+        dest = self.tmppath("dest")
+        depfile = self.tmppath("depfile")
+
+        with open(src, "wb") as tmp:
+            tmp.write(b"#ifdef FOO\ntest\n#endif")
+
+        # Initial copy
+        f = PreprocessedFile(
+            src, depfile_path=depfile, marker="#", defines={"FOO": True}
+        )
+        self.assertTrue(f.copy(dest))
+
+        # Ensure subsequent copies won't trigger writes
+        self.assertFalse(f.copy(DestNoWrite(dest)))
+        self.assertEqual(b"test\n", open(dest, "rb").read())
+
+        # When the source file is older than the destination file, even with
+        # different content, no copy should occur.
+        with open(src, "wb") as tmp:
+            tmp.write(b"#ifdef FOO\nfooo\n#endif")
+        time = os.path.getmtime(dest) - 1
+        os.utime(src, (time, time))
+        self.assertFalse(f.copy(DestNoWrite(dest)))
+        self.assertEqual(b"test\n", open(dest, "rb").read())
+
+        # skip_if_older=False is expected to force a copy in this situation.
+        self.assertTrue(f.copy(dest, skip_if_older=False))
+        self.assertEqual(b"fooo\n", open(dest, "rb").read())
+
+    def test_preprocess_file_dependencies(self):
+        """
+        Test that the preprocess runs if the dependencies of the source change
+        """
+        src = self.tmppath("src")
+        dest = self.tmppath("dest")
+        incl = self.tmppath("incl")
+        deps = self.tmppath("src.pp")
+
+        with open(src, "wb") as tmp:
+            tmp.write(b"#ifdef FOO\ntest\n#endif")
+
+        with open(incl, "wb") as tmp:
+            tmp.write(b"foo bar")
+
+        # Initial copy
+        f = PreprocessedFile(src, depfile_path=deps, marker="#", defines={"FOO": True})
+        self.assertTrue(f.copy(dest))
+
+        # Update the source so it #includes the include file.
+        with open(src, "wb") as tmp:
+            tmp.write(b"#include incl\n")
+        time = os.path.getmtime(dest) + 1
+        os.utime(src, (time, time))
+        self.assertTrue(f.copy(dest))
+        self.assertEqual(b"foo bar", open(dest, "rb").read())
+
+        # If one of the dependencies changes, the file should be updated. The
+        # mtime of the dependency is set after the destination file, to avoid
+        # both files having the same time.
+        with open(incl, "wb") as tmp:
+            tmp.write(b"quux")
+        time = os.path.getmtime(dest) + 1
+        os.utime(incl, (time, time))
+        self.assertTrue(f.copy(dest))
+        self.assertEqual(b"quux", open(dest, "rb").read())
+
+        # Perform one final copy to confirm that we don't run the preprocessor
+        # again. We update the mtime of the destination so it's newer than the
+        # input files. This would "just work" if we weren't changing
+        time = os.path.getmtime(incl) + 1
+        os.utime(dest, (time, time))
+        self.assertFalse(f.copy(DestNoWrite(dest)))
+
+    def test_replace_symlink(self):
+        """
+        Test that if the destination exists, and is a symlink, the target of
+        the symlink is not overwritten by the preprocessor output.
+        """
+        if not self.symlink_supported:
+            return
+
+        source = self.tmppath("source")
+        dest = self.tmppath("dest")
+        pp_source = self.tmppath("pp_in")
+        deps = self.tmppath("deps")
+
+        with open(source, "a"):
+            pass
+
+        os.symlink(source, dest)
+        self.assertTrue(os.path.islink(dest))
+
+        with open(pp_source, "wb") as tmp:
+            tmp.write(b"#define FOO\nPREPROCESSED")
+
+        f = PreprocessedFile(
+            pp_source, depfile_path=deps, marker="#", defines={"FOO": True}
+        )
+        self.assertTrue(f.copy(dest))
+
+        self.assertEqual(b"PREPROCESSED", open(dest, "rb").read())
+        self.assertFalse(os.path.islink(dest))
+        self.assertEqual(b"", open(source, "rb").read())
+
+
+class TestExistingFile(TestWithTmpDir):
+    def test_required_missing_dest(self):
+        with self.assertRaisesRegexp(ErrorMessage, "Required existing file"):
+            f = ExistingFile(required=True)
+            f.copy(self.tmppath("dest"))
+
+    def test_required_existing_dest(self):
+        p = self.tmppath("dest")
+        with open(p, "a"):
+            pass
+
+        f = ExistingFile(required=True)
+        f.copy(p)
+
+    def test_optional_missing_dest(self):
+        f = ExistingFile(required=False)
+        f.copy(self.tmppath("dest"))
+
+    def test_optional_existing_dest(self):
+        p = self.tmppath("dest")
+        with open(p, "a"):
+            pass
+
+        f = ExistingFile(required=False)
+        f.copy(p)
+
+
+class TestGeneratedFile(TestWithTmpDir):
+    def test_generated_file(self):
+        """
+        Check that GeneratedFile.copy yields the proper content in the
+        destination file in all situations that trigger different code paths
+        (see TestFile.test_file)
+        """
+        dest = self.tmppath("dest")
+
+        for content in samples:
+            f = GeneratedFile(content)
+            f.copy(dest)
+            self.assertEqual(content, open(dest, "rb").read())
+
+    def test_generated_file_open(self):
+        """
+        Test whether GeneratedFile.open returns an appropriately reset file
+        object.
+        """
+        content = b"".join(samples)
+        f = GeneratedFile(content)
+        self.assertEqual(content[:42], f.open().read(42))
+        self.assertEqual(content, f.open().read())
+
+    def test_generated_file_no_write(self):
+        """
+        Test various conditions where GeneratedFile.copy is expected not to
+        write in the destination file.
+        """
+        dest = self.tmppath("dest")
+
+        # Initial copy
+        f = GeneratedFile(b"test")
+        f.copy(dest)
+
+        # Ensure subsequent copies won't trigger writes
+        f.copy(DestNoWrite(dest))
+        self.assertEqual(b"test", open(dest, "rb").read())
+
+        # When using a new instance with the same content, no copy should occur
+        f = GeneratedFile(b"test")
+        f.copy(DestNoWrite(dest))
+        self.assertEqual(b"test", open(dest, "rb").read())
+
+        # Double check that under conditions where a copy occurs, we would get
+        # an exception.
+        f = GeneratedFile(b"fooo")
+        self.assertRaises(RuntimeError, f.copy, DestNoWrite(dest))
+
+    def test_generated_file_function(self):
+        """
+        Test GeneratedFile behavior with functions.
+        """
+        dest = self.tmppath("dest")
+        data = {
+            "num_calls": 0,
+        }
+
+        def content():
+            data["num_calls"] += 1
+            return b"content"
+
+        f = GeneratedFile(content)
+        self.assertEqual(data["num_calls"], 0)
+        f.copy(dest)
+        self.assertEqual(data["num_calls"], 1)
+        self.assertEqual(b"content", open(dest, "rb").read())
+        self.assertEqual(b"content", f.open().read())
+        self.assertEqual(b"content", f.read())
+        self.assertEqual(len(b"content"), f.size())
+        self.assertEqual(data["num_calls"], 1)
+
+        f.content = b"modified"
+        f.copy(dest)
+        self.assertEqual(data["num_calls"], 1)
+        self.assertEqual(b"modified", open(dest, "rb").read())
+        self.assertEqual(b"modified", f.open().read())
+        self.assertEqual(b"modified", f.read())
+        self.assertEqual(len(b"modified"), f.size())
+
+        f.content = content
+        self.assertEqual(data["num_calls"], 1)
+        self.assertEqual(b"content", f.read())
+        self.assertEqual(data["num_calls"], 2)
+
+
+class TestDeflatedFile(TestWithTmpDir):
+    def test_deflated_file(self):
+        """
+        Check that DeflatedFile.copy yields the proper content in the
+        destination file in all situations that trigger different code paths
+        (see TestFile.test_file)
+        """
+        src = self.tmppath("src.jar")
+        dest = self.tmppath("dest")
+
+        contents = {}
+        with JarWriter(src) as jar:
+            for content in samples:
+                name = "".join(
+                    random.choice(
+                        "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                    )
+                    for i in range(8)
+                )
+                jar.add(name, content, compress=True)
+                contents[name] = content
+
+        for j in JarReader(src):
+            f = DeflatedFile(j)
+            f.copy(dest)
+            self.assertEqual(contents[j.filename], open(dest, "rb").read())
+
+    def test_deflated_file_open(self):
+        """
+        Test whether DeflatedFile.open returns an appropriately reset file
+        object.
+        """
+        src = self.tmppath("src.jar")
+        content = b"".join(samples)
+        with JarWriter(src) as jar:
+            jar.add("content", content)
+
+        f = DeflatedFile(JarReader(src)["content"])
+        self.assertEqual(content[:42], f.open().read(42))
+        self.assertEqual(content, f.open().read())
+
+    def test_deflated_file_no_write(self):
+        """
+        Test various conditions where DeflatedFile.copy is expected not to
+        write in the destination file.
+        """
+        src = self.tmppath("src.jar")
+        dest = self.tmppath("dest")
+
+        with JarWriter(src) as jar:
+            jar.add("test", b"test")
+            jar.add("test2", b"test")
+            jar.add("fooo", b"fooo")
+
+        jar = JarReader(src)
+        # Initial copy
+        f = DeflatedFile(jar["test"])
+        f.copy(dest)
+
+        # Ensure subsequent copies won't trigger writes
+        f.copy(DestNoWrite(dest))
+        self.assertEqual(b"test", open(dest, "rb").read())
+
+        # When using a different file with the same content, no copy should
+        # occur
+        f = DeflatedFile(jar["test2"])
+        f.copy(DestNoWrite(dest))
+        self.assertEqual(b"test", open(dest, "rb").read())
+
+        # Double check that under conditions where a copy occurs, we would get
+        # an exception.
+        f = DeflatedFile(jar["fooo"])
+        self.assertRaises(RuntimeError, f.copy, DestNoWrite(dest))
+
+
+class TestManifestFile(TestWithTmpDir):
+    def test_manifest_file(self):
+        f = ManifestFile("chrome")
+        f.add(ManifestContent("chrome", "global", "toolkit/content/global/"))
+        f.add(ManifestResource("chrome", "gre-resources", "toolkit/res/"))
+        f.add(ManifestResource("chrome/pdfjs", "pdfjs", "./"))
+        f.add(ManifestContent("chrome/pdfjs", "pdfjs", "pdfjs"))
+        f.add(ManifestLocale("chrome", "browser", "en-US", "en-US/locale/browser/"))
+
+        f.copy(self.tmppath("chrome.manifest"))
+        self.assertEqual(
+            open(self.tmppath("chrome.manifest")).readlines(),
+            [
+                "content global toolkit/content/global/\n",
+                "resource gre-resources toolkit/res/\n",
+                "resource pdfjs pdfjs/\n",
+                "content pdfjs pdfjs/pdfjs\n",
+                "locale browser en-US en-US/locale/browser/\n",
+            ],
+        )
+
+        self.assertRaises(
+            ValueError,
+            f.remove,
+            ManifestContent("", "global", "toolkit/content/global/"),
+        )
+        self.assertRaises(
+            ValueError,
+            f.remove,
+            ManifestOverride(
+                "chrome",
+                "chrome://global/locale/netError.dtd",
+                "chrome://browser/locale/netError.dtd",
+            ),
+        )
+
+        f.remove(ManifestContent("chrome", "global", "toolkit/content/global/"))
+        self.assertRaises(
+            ValueError,
+            f.remove,
+            ManifestContent("chrome", "global", "toolkit/content/global/"),
+        )
+
+        f.copy(self.tmppath("chrome.manifest"))
+        content = open(self.tmppath("chrome.manifest"), "rb").read()
+        self.assertEqual(content[:42], f.open().read(42))
+        self.assertEqual(content, f.open().read())
+
+
+# Compiled typelib for the following IDL:
+#     interface foo;
+#     [scriptable, uuid(5f70da76-519c-4858-b71e-e3c92333e2d6)]
+#     interface bar {
+#         void bar(in foo f);
+#     };
+# We need to make this [scriptable] so it doesn't get deleted from the
+# typelib.  We don't need to make the foo interfaces below [scriptable],
+# because they will be automatically included by virtue of being an
+# argument to a method of |bar|.
+bar_xpt = GeneratedFile(
+    b"\x58\x50\x43\x4F\x4D\x0A\x54\x79\x70\x65\x4C\x69\x62\x0D\x0A\x1A"
+    + b"\x01\x02\x00\x02\x00\x00\x00\x7B\x00\x00\x00\x24\x00\x00\x00\x5C"
+    + b"\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+    + b"\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x5F"
+    + b"\x70\xDA\x76\x51\x9C\x48\x58\xB7\x1E\xE3\xC9\x23\x33\xE2\xD6\x00"
+    + b"\x00\x00\x05\x00\x00\x00\x00\x00\x00\x00\x0D\x00\x66\x6F\x6F\x00"
+    + b"\x62\x61\x72\x00\x62\x61\x72\x00\x00\x00\x00\x01\x00\x00\x00\x00"
+    + b"\x09\x01\x80\x92\x00\x01\x80\x06\x00\x00\x80"
+)
+
+# Compiled typelib for the following IDL:
+#     [uuid(3271bebc-927e-4bef-935e-44e0aaf3c1e5)]
+#     interface foo {
+#         void foo();
+#     };
+foo_xpt = GeneratedFile(
+    b"\x58\x50\x43\x4F\x4D\x0A\x54\x79\x70\x65\x4C\x69\x62\x0D\x0A\x1A"
+    + b"\x01\x02\x00\x01\x00\x00\x00\x57\x00\x00\x00\x24\x00\x00\x00\x40"
+    + b"\x80\x00\x00\x32\x71\xBE\xBC\x92\x7E\x4B\xEF\x93\x5E\x44\xE0\xAA"
+    + b"\xF3\xC1\xE5\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x09\x00"
+    + b"\x66\x6F\x6F\x00\x66\x6F\x6F\x00\x00\x00\x00\x01\x00\x00\x00\x00"
+    + b"\x05\x00\x80\x06\x00\x00\x00"
+)
+
+# Compiled typelib for the following IDL:
+#     [uuid(7057f2aa-fdc2-4559-abde-08d939f7e80d)]
+#     interface foo {
+#         void foo();
+#     };
+foo2_xpt = GeneratedFile(
+    b"\x58\x50\x43\x4F\x4D\x0A\x54\x79\x70\x65\x4C\x69\x62\x0D\x0A\x1A"
+    + b"\x01\x02\x00\x01\x00\x00\x00\x57\x00\x00\x00\x24\x00\x00\x00\x40"
+    + b"\x80\x00\x00\x70\x57\xF2\xAA\xFD\xC2\x45\x59\xAB\xDE\x08\xD9\x39"
+    + b"\xF7\xE8\x0D\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x09\x00"
+    + b"\x66\x6F\x6F\x00\x66\x6F\x6F\x00\x00\x00\x00\x01\x00\x00\x00\x00"
+    + b"\x05\x00\x80\x06\x00\x00\x00"
+)
+
+
+class TestMinifiedCommentStripped(TestWithTmpDir):
+    def test_minified_comment_stripped(self):
+        propLines = [
+            "# Comments are removed",
+            "foo = bar",
+            "",
+            "# Another comment",
+        ]
+        prop = GeneratedFile("\n".join(propLines))
+        self.assertEqual(
+            MinifiedCommentStripped(prop).open().readlines(), [b"foo = bar\n", b"\n"]
+        )
+        open(self.tmppath("prop"), "w").write("\n".join(propLines))
+        MinifiedCommentStripped(File(self.tmppath("prop"))).copy(self.tmppath("prop2"))
+        self.assertEqual(open(self.tmppath("prop2")).readlines(), ["foo = bar\n", "\n"])
+
+
+class TestMinifiedJavaScript(TestWithTmpDir):
+    orig_lines = [
+        "// Comment line",
+        'let foo = "bar";',
+        "var bar = true;",
+        "",
+        "// Another comment",
+    ]
+
+    def test_minified_javascript(self):
+        orig_f = GeneratedFile("\n".join(self.orig_lines))
+        min_f = MinifiedJavaScript(orig_f)
+
+        mini_lines = min_f.open().readlines()
+        self.assertTrue(mini_lines)
+        self.assertTrue(len(mini_lines) < len(self.orig_lines))
+
+    def _verify_command(self, code):
+        our_dir = os.path.abspath(os.path.dirname(__file__))
+        return [
+            sys.executable,
+            os.path.join(our_dir, "support", "minify_js_verify.py"),
+            code,
+        ]
+
+    def test_minified_verify_success(self):
+        orig_f = GeneratedFile("\n".join(self.orig_lines))
+        min_f = MinifiedJavaScript(orig_f, verify_command=self._verify_command("0"))
+
+        mini_lines = [six.ensure_text(s) for s in min_f.open().readlines()]
+        self.assertTrue(mini_lines)
+        self.assertTrue(len(mini_lines) < len(self.orig_lines))
+
+    def test_minified_verify_failure(self):
+        orig_f = GeneratedFile("\n".join(self.orig_lines))
+        errors.out = six.StringIO()
+        min_f = MinifiedJavaScript(orig_f, verify_command=self._verify_command("1"))
+
+        mini_lines = min_f.open().readlines()
+        output = errors.out.getvalue()
+        errors.out = sys.stderr
+        self.assertEqual(
+            output,
+            "warning: JS minification verification failed for <unknown>:\n"
+            "warning: Error message\n",
+        )
+        self.assertEqual(mini_lines, orig_f.open().readlines())
+
+
+class MatchTestTemplate(object):
+    def prepare_match_test(self, with_dotfiles=False):
+        self.add("bar")
+        self.add("foo/bar")
+        self.add("foo/baz")
+        self.add("foo/qux/1")
+        self.add("foo/qux/bar")
+        self.add("foo/qux/2/test")
+        self.add("foo/qux/2/test2")
+        if with_dotfiles:
+            self.add("foo/.foo")
+            self.add("foo/.bar/foo")
+
+    def do_match_test(self):
+        self.do_check(
+            "",
+            [
+                "bar",
+                "foo/bar",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/bar",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+            ],
+        )
+        self.do_check(
+            "*",
+            [
+                "bar",
+                "foo/bar",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/bar",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+            ],
+        )
+        self.do_check(
+            "foo/qux", ["foo/qux/1", "foo/qux/bar", "foo/qux/2/test", "foo/qux/2/test2"]
+        )
+        self.do_check("foo/b*", ["foo/bar", "foo/baz"])
+        self.do_check("baz", [])
+        self.do_check("foo/foo", [])
+        self.do_check("foo/*ar", ["foo/bar"])
+        self.do_check("*ar", ["bar"])
+        self.do_check("*/bar", ["foo/bar"])
+        self.do_check(
+            "foo/*ux", ["foo/qux/1", "foo/qux/bar", "foo/qux/2/test", "foo/qux/2/test2"]
+        )
+        self.do_check(
+            "foo/q*ux",
+            ["foo/qux/1", "foo/qux/bar", "foo/qux/2/test", "foo/qux/2/test2"],
+        )
+        self.do_check("foo/*/2/test*", ["foo/qux/2/test", "foo/qux/2/test2"])
+        self.do_check("**/bar", ["bar", "foo/bar", "foo/qux/bar"])
+        self.do_check("foo/**/test", ["foo/qux/2/test"])
+        self.do_check(
+            "foo",
+            [
+                "foo/bar",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/bar",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+            ],
+        )
+        self.do_check(
+            "foo/**",
+            [
+                "foo/bar",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/bar",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+            ],
+        )
+        self.do_check("**/2/test*", ["foo/qux/2/test", "foo/qux/2/test2"])
+        self.do_check(
+            "**/foo",
+            [
+                "foo/bar",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/bar",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+            ],
+        )
+        self.do_check("**/barbaz", [])
+        self.do_check("f**/bar", ["foo/bar"])
+
+    def do_finder_test(self, finder):
+        self.assertTrue(finder.contains("foo/.foo"))
+        self.assertTrue(finder.contains("foo/.bar"))
+        self.assertTrue("foo/.foo" in [f for f, c in finder.find("foo/.foo")])
+        self.assertTrue("foo/.bar/foo" in [f for f, c in finder.find("foo/.bar")])
+        self.assertEqual(
+            sorted([f for f, c in finder.find("foo/.*")]), ["foo/.bar/foo", "foo/.foo"]
+        )
+        for pattern in ["foo", "**", "**/*", "**/foo", "foo/*"]:
+            self.assertFalse("foo/.foo" in [f for f, c in finder.find(pattern)])
+            self.assertFalse("foo/.bar/foo" in [f for f, c in finder.find(pattern)])
+            self.assertEqual(
+                sorted([f for f, c in finder.find(pattern)]),
+                sorted([f for f, c in finder if mozpath.match(f, pattern)]),
+            )
+
+
+def do_check(test, finder, pattern, result):
+    if result:
+        test.assertTrue(finder.contains(pattern))
+    else:
+        test.assertFalse(finder.contains(pattern))
+    test.assertEqual(sorted(list(f for f, c in finder.find(pattern))), sorted(result))
+
+
+class TestFileFinder(MatchTestTemplate, TestWithTmpDir):
+    def add(self, path):
+        ensureParentDir(self.tmppath(path))
+        open(self.tmppath(path), "wb").write(six.ensure_binary(path))
+
+    def do_check(self, pattern, result):
+        do_check(self, self.finder, pattern, result)
+
+    def test_file_finder(self):
+        self.prepare_match_test(with_dotfiles=True)
+        self.finder = FileFinder(self.tmpdir)
+        self.do_match_test()
+        self.do_finder_test(self.finder)
+
+    def test_get(self):
+        self.prepare_match_test()
+        finder = FileFinder(self.tmpdir)
+
+        self.assertIsNone(finder.get("does-not-exist"))
+        res = finder.get("bar")
+        self.assertIsInstance(res, File)
+        self.assertEqual(mozpath.normpath(res.path), mozpath.join(self.tmpdir, "bar"))
+
+    def test_ignored_dirs(self):
+        """Ignored directories should not have results returned."""
+        self.prepare_match_test()
+        self.add("fooz")
+
+        # Present to ensure prefix matching doesn't exclude.
+        self.add("foo/quxz")
+
+        self.finder = FileFinder(self.tmpdir, ignore=["foo/qux"])
+
+        self.do_check("**", ["bar", "foo/bar", "foo/baz", "foo/quxz", "fooz"])
+        self.do_check("foo/*", ["foo/bar", "foo/baz", "foo/quxz"])
+        self.do_check("foo/**", ["foo/bar", "foo/baz", "foo/quxz"])
+        self.do_check("foo/qux/**", [])
+        self.do_check("foo/qux/*", [])
+        self.do_check("foo/qux/bar", [])
+        self.do_check("foo/quxz", ["foo/quxz"])
+        self.do_check("fooz", ["fooz"])
+
+    def test_ignored_files(self):
+        """Ignored files should not have results returned."""
+        self.prepare_match_test()
+
+        # Be sure prefix match doesn't get ignored.
+        self.add("barz")
+
+        self.finder = FileFinder(self.tmpdir, ignore=["foo/bar", "bar"])
+        self.do_check(
+            "**",
+            [
+                "barz",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+                "foo/qux/bar",
+            ],
+        )
+        self.do_check(
+            "foo/**",
+            [
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+                "foo/qux/bar",
+            ],
+        )
+
+    def test_ignored_patterns(self):
+        """Ignore entries with patterns should be honored."""
+        self.prepare_match_test()
+
+        self.add("foo/quxz")
+
+        self.finder = FileFinder(self.tmpdir, ignore=["foo/qux/*"])
+        self.do_check("**", ["foo/bar", "foo/baz", "foo/quxz", "bar"])
+        self.do_check("foo/**", ["foo/bar", "foo/baz", "foo/quxz"])
+
+    def test_dotfiles(self):
+        """Finder can find files beginning with . is configured."""
+        self.prepare_match_test(with_dotfiles=True)
+        self.finder = FileFinder(self.tmpdir, find_dotfiles=True)
+        self.do_check(
+            "**",
+            [
+                "bar",
+                "foo/.foo",
+                "foo/.bar/foo",
+                "foo/bar",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/bar",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+            ],
+        )
+
+    def test_dotfiles_plus_ignore(self):
+        self.prepare_match_test(with_dotfiles=True)
+        self.finder = FileFinder(
+            self.tmpdir, find_dotfiles=True, ignore=["foo/.bar/**"]
+        )
+        self.do_check(
+            "foo/**",
+            [
+                "foo/.foo",
+                "foo/bar",
+                "foo/baz",
+                "foo/qux/1",
+                "foo/qux/bar",
+                "foo/qux/2/test",
+                "foo/qux/2/test2",
+            ],
+        )
+
+
+class TestJarFinder(MatchTestTemplate, TestWithTmpDir):
+    def add(self, path):
+        self.jar.add(path, ensure_bytes(path), compress=True)
+
+    def do_check(self, pattern, result):
+        do_check(self, self.finder, pattern, result)
+
+    def test_jar_finder(self):
+        self.jar = JarWriter(file=self.tmppath("test.jar"))
+        self.prepare_match_test()
+        self.jar.finish()
+        reader = JarReader(file=self.tmppath("test.jar"))
+        self.finder = JarFinder(self.tmppath("test.jar"), reader)
+        self.do_match_test()
+
+        self.assertIsNone(self.finder.get("does-not-exist"))
+        self.assertIsInstance(self.finder.get("bar"), DeflatedFile)
+
+
+class TestTarFinder(MatchTestTemplate, TestWithTmpDir):
+    def add(self, path):
+        self.tar.addfile(tarfile.TarInfo(name=path))
+
+    def do_check(self, pattern, result):
+        do_check(self, self.finder, pattern, result)
+
+    def test_tar_finder(self):
+        self.tar = tarfile.open(name=self.tmppath("test.tar.bz2"), mode="w:bz2")
+        self.prepare_match_test()
+        self.tar.close()
+        with tarfile.open(name=self.tmppath("test.tar.bz2"), mode="r:bz2") as tarreader:
+            self.finder = TarFinder(self.tmppath("test.tar.bz2"), tarreader)
+            self.do_match_test()
+
+            self.assertIsNone(self.finder.get("does-not-exist"))
+            self.assertIsInstance(self.finder.get("bar"), ExtractedTarFile)
+
+
+class TestComposedFinder(MatchTestTemplate, TestWithTmpDir):
+    def add(self, path, content=None):
+        # Put foo/qux files under $tmp/b.
+        if path.startswith("foo/qux/"):
+            real_path = mozpath.join("b", path[8:])
+        else:
+            real_path = mozpath.join("a", path)
+        ensureParentDir(self.tmppath(real_path))
+        if not content:
+            content = six.ensure_binary(path)
+        open(self.tmppath(real_path), "wb").write(content)
+
+    def do_check(self, pattern, result):
+        if "*" in pattern:
+            return
+        do_check(self, self.finder, pattern, result)
+
+    def test_composed_finder(self):
+        self.prepare_match_test()
+        # Also add files in $tmp/a/foo/qux because ComposedFinder is
+        # expected to mask foo/qux entirely with content from $tmp/b.
+        ensureParentDir(self.tmppath("a/foo/qux/hoge"))
+        open(self.tmppath("a/foo/qux/hoge"), "wb").write(b"hoge")
+        open(self.tmppath("a/foo/qux/bar"), "wb").write(b"not the right content")
+        self.finder = ComposedFinder(
+            {
+                "": FileFinder(self.tmppath("a")),
+                "foo/qux": FileFinder(self.tmppath("b")),
+            }
+        )
+        self.do_match_test()
+
+        self.assertIsNone(self.finder.get("does-not-exist"))
+        self.assertIsInstance(self.finder.get("bar"), File)
+
+
+@unittest.skipUnless(hglib, "hglib not available")
+@unittest.skipIf(
+    six.PY3 and os.name == "nt", "Does not currently work in Python3 on Windows"
+)
+class TestMercurialRevisionFinder(MatchTestTemplate, TestWithTmpDir):
+    def setUp(self):
+        super(TestMercurialRevisionFinder, self).setUp()
+        hglib.init(self.tmpdir)
+        self._clients = []
+
+    def tearDown(self):
+        # Ensure the hg client process is closed. Otherwise, Windows
+        # may have trouble removing the repo directory because the process
+        # has an open handle on it.
+        for client in getattr(self, "_clients", []):
+            if client.server:
+                client.close()
+
+        self._clients[:] = []
+
+        super(TestMercurialRevisionFinder, self).tearDown()
+
+    def _client(self):
+        configs = (
+            # b'' because py2 needs !unicode
+            b'ui.username="Dummy User <dummy@example.com>"',
+        )
+        client = hglib.open(
+            six.ensure_binary(self.tmpdir),
+            encoding=b"UTF-8",  # b'' because py2 needs !unicode
+            configs=configs,
+        )
+        self._clients.append(client)
+        return client
+
+    def add(self, path):
+        with self._client() as c:
+            ensureParentDir(self.tmppath(path))
+            with open(self.tmppath(path), "wb") as fh:
+                fh.write(six.ensure_binary(path))
+            c.add(six.ensure_binary(self.tmppath(path)))
+
+    def do_check(self, pattern, result):
+        do_check(self, self.finder, pattern, result)
+
+    def _get_finder(self, *args, **kwargs):
+        f = MercurialRevisionFinder(*args, **kwargs)
+        self._clients.append(f._client)
+        return f
+
+    def test_default_revision(self):
+        self.prepare_match_test()
+        with self._client() as c:
+            c.commit("initial commit")
+
+        self.finder = self._get_finder(self.tmpdir)
+        self.do_match_test()
+
+        self.assertIsNone(self.finder.get("does-not-exist"))
+        self.assertIsInstance(self.finder.get("bar"), MercurialFile)
+
+    def test_old_revision(self):
+        with self._client() as c:
+            with open(self.tmppath("foo"), "wb") as fh:
+                fh.write(b"foo initial")
+            c.add(six.ensure_binary(self.tmppath("foo")))
+            c.commit("initial")
+
+            with open(self.tmppath("foo"), "wb") as fh:
+                fh.write(b"foo second")
+            with open(self.tmppath("bar"), "wb") as fh:
+                fh.write(b"bar second")
+            c.add(six.ensure_binary(self.tmppath("bar")))
+            c.commit("second")
+            # This wipes out the working directory, ensuring the finder isn't
+            # finding anything from the filesystem.
+            c.rawcommand([b"update", b"null"])
+
+        finder = self._get_finder(self.tmpdir, "0")
+        f = finder.get("foo")
+        self.assertEqual(f.read(), b"foo initial")
+        self.assertEqual(f.read(), b"foo initial", "read again for good measure")
+        self.assertIsNone(finder.get("bar"))
+
+        finder = self._get_finder(self.tmpdir, rev="1")
+        f = finder.get("foo")
+        self.assertEqual(f.read(), b"foo second")
+        f = finder.get("bar")
+        self.assertEqual(f.read(), b"bar second")
+        f = None
+
+    def test_recognize_repo_paths(self):
+        with self._client() as c:
+            with open(self.tmppath("foo"), "wb") as fh:
+                fh.write(b"initial")
+            c.add(six.ensure_binary(self.tmppath("foo")))
+            c.commit("initial")
+            c.rawcommand([b"update", b"null"])
+
+        finder = self._get_finder(self.tmpdir, "0", recognize_repo_paths=True)
+        with self.assertRaises(NotImplementedError):
+            list(finder.find(""))
+
+        with self.assertRaises(ValueError):
+            finder.get("foo")
+        with self.assertRaises(ValueError):
+            finder.get("")
+
+        f = finder.get(self.tmppath("foo"))
+        self.assertIsInstance(f, MercurialFile)
+        self.assertEqual(f.read(), b"initial")
+        f = None
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_manifests.py b/python/mozbuild/mozpack/test/test_manifests.py
new file mode 100644
index 0000000000..a5db53b58c
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_manifests.py
@@ -0,0 +1,465 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+
+import mozunit
+
+from mozpack.copier import FileCopier, FileRegistry
+from mozpack.manifests import InstallManifest, UnreadableInstallManifest
+from mozpack.test.test_files import TestWithTmpDir
+
+
+class TestInstallManifest(TestWithTmpDir):
+    def test_construct(self):
+        m = InstallManifest()
+        self.assertEqual(len(m), 0)
+
+    def test_malformed(self):
+        f = self.tmppath("manifest")
+        open(f, "wt").write("junk\n")
+        with self.assertRaises(UnreadableInstallManifest):
+            InstallManifest(f)
+
+    def test_adds(self):
+        m = InstallManifest()
+        m.add_link("s_source", "s_dest")
+        m.add_copy("c_source", "c_dest")
+        m.add_required_exists("e_dest")
+        m.add_optional_exists("o_dest")
+        m.add_pattern_link("ps_base", "ps/*", "ps_dest")
+        m.add_pattern_copy("pc_base", "pc/**", "pc_dest")
+        m.add_preprocess("p_source", "p_dest", "p_source.pp")
+        m.add_content("content", "content")
+
+        self.assertEqual(len(m), 8)
+        self.assertIn("s_dest", m)
+        self.assertIn("c_dest", m)
+        self.assertIn("p_dest", m)
+        self.assertIn("e_dest", m)
+        self.assertIn("o_dest", m)
+        self.assertIn("content", m)
+
+        with self.assertRaises(ValueError):
+            m.add_link("s_other", "s_dest")
+
+        with self.assertRaises(ValueError):
+            m.add_copy("c_other", "c_dest")
+
+        with self.assertRaises(ValueError):
+            m.add_preprocess("p_other", "p_dest", "p_other.pp")
+
+        with self.assertRaises(ValueError):
+            m.add_required_exists("e_dest")
+
+        with self.assertRaises(ValueError):
+            m.add_optional_exists("o_dest")
+
+        with self.assertRaises(ValueError):
+            m.add_pattern_link("ps_base", "ps/*", "ps_dest")
+
+        with self.assertRaises(ValueError):
+            m.add_pattern_copy("pc_base", "pc/**", "pc_dest")
+
+        with self.assertRaises(ValueError):
+            m.add_content("content", "content")
+
+    def _get_test_manifest(self):
+        m = InstallManifest()
+        m.add_link(self.tmppath("s_source"), "s_dest")
+        m.add_copy(self.tmppath("c_source"), "c_dest")
+        m.add_preprocess(
+            self.tmppath("p_source"),
+            "p_dest",
+            self.tmppath("p_source.pp"),
+            "#",
+            {"FOO": "BAR", "BAZ": "QUX"},
+        )
+        m.add_required_exists("e_dest")
+        m.add_optional_exists("o_dest")
+        m.add_pattern_link("ps_base", "*", "ps_dest")
+        m.add_pattern_copy("pc_base", "**", "pc_dest")
+        m.add_content("the content\non\nmultiple lines", "content")
+
+        return m
+
+    def test_serialization(self):
+        m = self._get_test_manifest()
+
+        p = self.tmppath("m")
+        m.write(path=p)
+        self.assertTrue(os.path.isfile(p))
+
+        with open(p, "r") as fh:
+            c = fh.read()
+
+        self.assertEqual(c.count("\n"), 9)
+
+        lines = c.splitlines()
+        self.assertEqual(len(lines), 9)
+
+        self.assertEqual(lines[0], "5")
+
+        m2 = InstallManifest(path=p)
+        self.assertEqual(m, m2)
+        p2 = self.tmppath("m2")
+        m2.write(path=p2)
+
+        with open(p2, "r") as fh:
+            c2 = fh.read()
+
+        self.assertEqual(c, c2)
+
+    def test_populate_registry(self):
+        m = self._get_test_manifest()
+        r = FileRegistry()
+        m.populate_registry(r)
+
+        self.assertEqual(len(r), 6)
+        self.assertEqual(
+            r.paths(), ["c_dest", "content", "e_dest", "o_dest", "p_dest", "s_dest"]
+        )
+
+    def test_pattern_expansion(self):
+        source = self.tmppath("source")
+        os.mkdir(source)
+        os.mkdir("%s/base" % source)
+        os.mkdir("%s/base/foo" % source)
+
+        with open("%s/base/foo/file1" % source, "a"):
+            pass
+
+        with open("%s/base/foo/file2" % source, "a"):
+            pass
+
+        m = InstallManifest()
+        m.add_pattern_link("%s/base" % source, "**", "dest")
+
+        c = FileCopier()
+        m.populate_registry(c)
+        self.assertEqual(c.paths(), ["dest/foo/file1", "dest/foo/file2"])
+
+    def test_write_expand_pattern(self):
+        source = self.tmppath("source")
+        os.mkdir(source)
+        os.mkdir("%s/base" % source)
+        os.mkdir("%s/base/foo" % source)
+
+        with open("%s/base/foo/file1" % source, "a"):
+            pass
+
+        with open("%s/base/foo/file2" % source, "a"):
+            pass
+
+        m = InstallManifest()
+        m.add_pattern_link("%s/base" % source, "**", "dest")
+
+        track = self.tmppath("track")
+        m.write(path=track, expand_pattern=True)
+
+        m = InstallManifest(path=track)
+        self.assertEqual(
+            sorted(dest for dest in m._dests), ["dest/foo/file1", "dest/foo/file2"]
+        )
+
+    def test_or(self):
+        m1 = self._get_test_manifest()
+        orig_length = len(m1)
+        m2 = InstallManifest()
+        m2.add_link("s_source2", "s_dest2")
+        m2.add_copy("c_source2", "c_dest2")
+
+        m1 |= m2
+
+        self.assertEqual(len(m2), 2)
+        self.assertEqual(len(m1), orig_length + 2)
+
+        self.assertIn("s_dest2", m1)
+        self.assertIn("c_dest2", m1)
+
+    def test_copier_application(self):
+        dest = self.tmppath("dest")
+        os.mkdir(dest)
+
+        to_delete = self.tmppath("dest/to_delete")
+        with open(to_delete, "a"):
+            pass
+
+        with open(self.tmppath("s_source"), "wt") as fh:
+            fh.write("symlink!")
+
+        with open(self.tmppath("c_source"), "wt") as fh:
+            fh.write("copy!")
+
+        with open(self.tmppath("p_source"), "wt") as fh:
+            fh.write("#define FOO 1\npreprocess!")
+
+        with open(self.tmppath("dest/e_dest"), "a"):
+            pass
+
+        with open(self.tmppath("dest/o_dest"), "a"):
+            pass
+
+        m = self._get_test_manifest()
+        c = FileCopier()
+        m.populate_registry(c)
+        result = c.copy(dest)
+
+        self.assertTrue(os.path.exists(self.tmppath("dest/s_dest")))
+        self.assertTrue(os.path.exists(self.tmppath("dest/c_dest")))
+        self.assertTrue(os.path.exists(self.tmppath("dest/p_dest")))
+        self.assertTrue(os.path.exists(self.tmppath("dest/e_dest")))
+        self.assertTrue(os.path.exists(self.tmppath("dest/o_dest")))
+        self.assertTrue(os.path.exists(self.tmppath("dest/content")))
+        self.assertFalse(os.path.exists(to_delete))
+
+        with open(self.tmppath("dest/s_dest"), "rt") as fh:
+            self.assertEqual(fh.read(), "symlink!")
+
+        with open(self.tmppath("dest/c_dest"), "rt") as fh:
+            self.assertEqual(fh.read(), "copy!")
+
+        with open(self.tmppath("dest/p_dest"), "rt") as fh:
+            self.assertEqual(fh.read(), "preprocess!")
+
+        self.assertEqual(
+            result.updated_files,
+            set(
+                self.tmppath(p)
+                for p in ("dest/s_dest", "dest/c_dest", "dest/p_dest", "dest/content")
+            ),
+        )
+        self.assertEqual(
+            result.existing_files,
+            set([self.tmppath("dest/e_dest"), self.tmppath("dest/o_dest")]),
+        )
+        self.assertEqual(result.removed_files, {to_delete})
+        self.assertEqual(result.removed_directories, set())
+
+    def test_preprocessor(self):
+        manifest = self.tmppath("m")
+        deps = self.tmppath("m.pp")
+        dest = self.tmppath("dest")
+        include = self.tmppath("p_incl")
+
+        with open(include, "wt") as fh:
+            fh.write("#define INCL\n")
+        time = os.path.getmtime(include) - 3
+        os.utime(include, (time, time))
+
+        with open(self.tmppath("p_source"), "wt") as fh:
+            fh.write("#ifdef FOO\n#if BAZ == QUX\nPASS1\n#endif\n#endif\n")
+            fh.write("#ifdef DEPTEST\nPASS2\n#endif\n")
+            fh.write("#include p_incl\n#ifdef INCLTEST\nPASS3\n#endif\n")
+        time = os.path.getmtime(self.tmppath("p_source")) - 3
+        os.utime(self.tmppath("p_source"), (time, time))
+
+        # Create and write a manifest with the preprocessed file, then apply it.
+        # This should write out our preprocessed file.
+        m = InstallManifest()
+        m.add_preprocess(
+            self.tmppath("p_source"), "p_dest", deps, "#", {"FOO": "BAR", "BAZ": "QUX"}
+        )
+        m.write(path=manifest)
+
+        m = InstallManifest(path=manifest)
+        c = FileCopier()
+        m.populate_registry(c)
+        c.copy(dest)
+
+        self.assertTrue(os.path.exists(self.tmppath("dest/p_dest")))
+
+        with open(self.tmppath("dest/p_dest"), "rt") as fh:
+            self.assertEqual(fh.read(), "PASS1\n")
+
+        # Create a second manifest with the preprocessed file, then apply it.
+        # Since this manifest does not exist on the disk, there should not be a
+        # dependency on it, and the preprocessed file should not be modified.
+        m2 = InstallManifest()
+        m2.add_preprocess(
+            self.tmppath("p_source"), "p_dest", deps, "#", {"DEPTEST": True}
+        )
+        c = FileCopier()
+        m2.populate_registry(c)
+        result = c.copy(dest)
+
+        self.assertFalse(self.tmppath("dest/p_dest") in result.updated_files)
+        self.assertTrue(self.tmppath("dest/p_dest") in result.existing_files)
+
+        # Write out the second manifest, then load it back in from the disk.
+        # This should add the dependency on the manifest file, so our
+        # preprocessed file should be regenerated with the new defines.
+        # We also set the mtime on the destination file back, so it will be
+        # older than the manifest file.
+        m2.write(path=manifest)
+        time = os.path.getmtime(manifest) - 1
+        os.utime(self.tmppath("dest/p_dest"), (time, time))
+        m2 = InstallManifest(path=manifest)
+        c = FileCopier()
+        m2.populate_registry(c)
+        self.assertTrue(c.copy(dest))
+
+        with open(self.tmppath("dest/p_dest"), "rt") as fh:
+            self.assertEqual(fh.read(), "PASS2\n")
+
+        # Set the time on the manifest back, so it won't be picked up as
+        # modified in the next test
+        time = os.path.getmtime(manifest) - 1
+        os.utime(manifest, (time, time))
+
+        # Update the contents of a file included by the source file. This should
+        # cause the destination to be regenerated.
+        with open(include, "wt") as fh:
+            fh.write("#define INCLTEST\n")
+
+        time = os.path.getmtime(include) - 1
+        os.utime(self.tmppath("dest/p_dest"), (time, time))
+        c = FileCopier()
+        m2.populate_registry(c)
+        self.assertTrue(c.copy(dest))
+
+        with open(self.tmppath("dest/p_dest"), "rt") as fh:
+            self.assertEqual(fh.read(), "PASS2\nPASS3\n")
+
+    def test_preprocessor_dependencies(self):
+        manifest = self.tmppath("m")
+        deps = self.tmppath("m.pp")
+        dest = self.tmppath("dest")
+        source = self.tmppath("p_source")
+        destfile = self.tmppath("dest/p_dest")
+        include = self.tmppath("p_incl")
+        os.mkdir(dest)
+
+        with open(source, "wt") as fh:
+            fh.write("#define SRC\nSOURCE\n")
+        time = os.path.getmtime(source) - 3
+        os.utime(source, (time, time))
+
+        with open(include, "wt") as fh:
+            fh.write("INCLUDE\n")
+        time = os.path.getmtime(source) - 3
+        os.utime(include, (time, time))
+
+        # Create and write a manifest with the preprocessed file.
+        m = InstallManifest()
+        m.add_preprocess(source, "p_dest", deps, "#", {"FOO": "BAR", "BAZ": "QUX"})
+        m.write(path=manifest)
+
+        time = os.path.getmtime(source) - 5
+        os.utime(manifest, (time, time))
+
+        # Now read the manifest back in, and apply it. This should write out
+        # our preprocessed file.
+        m = InstallManifest(path=manifest)
+        c = FileCopier()
+        m.populate_registry(c)
+        self.assertTrue(c.copy(dest))
+
+        with open(destfile, "rt") as fh:
+            self.assertEqual(fh.read(), "SOURCE\n")
+
+        # Next, modify the source to #INCLUDE another file.
+        with open(source, "wt") as fh:
+            fh.write("SOURCE\n#include p_incl\n")
+        time = os.path.getmtime(source) - 1
+        os.utime(destfile, (time, time))
+
+        # Apply the manifest, and confirm that it also reads the newly included
+        # file.
+        m = InstallManifest(path=manifest)
+        c = FileCopier()
+        m.populate_registry(c)
+        c.copy(dest)
+
+        with open(destfile, "rt") as fh:
+            self.assertEqual(fh.read(), "SOURCE\nINCLUDE\n")
+
+        # Set the time on the source file back, so it won't be picked up as
+        # modified in the next test.
+        time = os.path.getmtime(source) - 1
+        os.utime(source, (time, time))
+
+        # Now, modify the include file (but not the original source).
+        with open(include, "wt") as fh:
+            fh.write("INCLUDE MODIFIED\n")
+        time = os.path.getmtime(include) - 1
+        os.utime(destfile, (time, time))
+
+        # Apply the manifest, and confirm that the change to the include file
+        # is detected. That should cause the preprocessor to run again.
+        m = InstallManifest(path=manifest)
+        c = FileCopier()
+        m.populate_registry(c)
+        c.copy(dest)
+
+        with open(destfile, "rt") as fh:
+            self.assertEqual(fh.read(), "SOURCE\nINCLUDE MODIFIED\n")
+
+        # ORing an InstallManifest should copy file dependencies
+        m = InstallManifest()
+        m |= InstallManifest(path=manifest)
+        c = FileCopier()
+        m.populate_registry(c)
+        e = c._files["p_dest"]
+        self.assertEqual(e.extra_depends, [manifest])
+
+    def test_add_entries_from(self):
+        source = self.tmppath("source")
+        os.mkdir(source)
+        os.mkdir("%s/base" % source)
+        os.mkdir("%s/base/foo" % source)
+
+        with open("%s/base/foo/file1" % source, "a"):
+            pass
+
+        with open("%s/base/foo/file2" % source, "a"):
+            pass
+
+        m = InstallManifest()
+        m.add_pattern_link("%s/base" % source, "**", "dest")
+
+        p = InstallManifest()
+        p.add_entries_from(m)
+        self.assertEqual(len(p), 1)
+
+        c = FileCopier()
+        p.populate_registry(c)
+        self.assertEqual(c.paths(), ["dest/foo/file1", "dest/foo/file2"])
+
+        q = InstallManifest()
+        q.add_entries_from(m, base="target")
+        self.assertEqual(len(q), 1)
+
+        d = FileCopier()
+        q.populate_registry(d)
+        self.assertEqual(d.paths(), ["target/dest/foo/file1", "target/dest/foo/file2"])
+
+        # Some of the values in an InstallManifest include destination
+        # information that is present in the keys.  Verify that we can
+        # round-trip serialization.
+        r = InstallManifest()
+        r.add_entries_from(m)
+        r.add_entries_from(m, base="target")
+        self.assertEqual(len(r), 2)
+
+        temp_path = self.tmppath("temp_path")
+        r.write(path=temp_path)
+
+        s = InstallManifest(path=temp_path)
+        e = FileCopier()
+        s.populate_registry(e)
+
+        self.assertEqual(
+            e.paths(),
+            [
+                "dest/foo/file1",
+                "dest/foo/file2",
+                "target/dest/foo/file1",
+                "target/dest/foo/file2",
+            ],
+        )
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_mozjar.py b/python/mozbuild/mozpack/test/test_mozjar.py
new file mode 100644
index 0000000000..e96c59238f
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_mozjar.py
@@ -0,0 +1,350 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import unittest
+from collections import OrderedDict
+
+import mozunit
+import six
+
+import mozpack.path as mozpath
+from mozpack.files import FileFinder
+from mozpack.mozjar import (
+    Deflater,
+    JarLog,
+    JarReader,
+    JarReaderError,
+    JarStruct,
+    JarWriter,
+    JarWriterError,
+)
+from mozpack.test.test_files import MockDest
+
+test_data_path = mozpath.abspath(mozpath.dirname(__file__))
+test_data_path = mozpath.join(test_data_path, "data")
+
+
+class TestJarStruct(unittest.TestCase):
+    class Foo(JarStruct):
+        MAGIC = 0x01020304
+        STRUCT = OrderedDict(
+            [
+                ("foo", "uint32"),
+                ("bar", "uint16"),
+                ("qux", "uint16"),
+                ("length", "uint16"),
+                ("length2", "uint16"),
+                ("string", "length"),
+                ("string2", "length2"),
+            ]
+        )
+
+    def test_jar_struct(self):
+        foo = TestJarStruct.Foo()
+        self.assertEqual(foo.signature, TestJarStruct.Foo.MAGIC)
+        self.assertEqual(foo["foo"], 0)
+        self.assertEqual(foo["bar"], 0)
+        self.assertEqual(foo["qux"], 0)
+        self.assertFalse("length" in foo)
+        self.assertFalse("length2" in foo)
+        self.assertEqual(foo["string"], "")
+        self.assertEqual(foo["string2"], "")
+
+        self.assertEqual(foo.size, 16)
+
+        foo["foo"] = 0x42434445
+        foo["bar"] = 0xABCD
+        foo["qux"] = 0xEF01
+        foo["string"] = "abcde"
+        foo["string2"] = "Arbitrarily long string"
+
+        serialized = (
+            b"\x04\x03\x02\x01\x45\x44\x43\x42\xcd\xab\x01\xef"
+            + b"\x05\x00\x17\x00abcdeArbitrarily long string"
+        )
+        self.assertEqual(foo.size, len(serialized))
+        foo_serialized = foo.serialize()
+        self.assertEqual(foo_serialized, serialized)
+
+    def do_test_read_jar_struct(self, data):
+        self.assertRaises(JarReaderError, TestJarStruct.Foo, data)
+        self.assertRaises(JarReaderError, TestJarStruct.Foo, data[2:])
+
+        foo = TestJarStruct.Foo(data[1:])
+        self.assertEqual(foo["foo"], 0x45444342)
+        self.assertEqual(foo["bar"], 0xCDAB)
+        self.assertEqual(foo["qux"], 0x01EF)
+        self.assertFalse("length" in foo)
+        self.assertFalse("length2" in foo)
+        self.assertEqual(foo["string"], b"012345")
+        self.assertEqual(foo["string2"], b"67")
+
+    def test_read_jar_struct(self):
+        data = (
+            b"\x00\x04\x03\x02\x01\x42\x43\x44\x45\xab\xcd\xef"
+            + b"\x01\x06\x00\x02\x0001234567890"
+        )
+        self.do_test_read_jar_struct(data)
+
+    def test_read_jar_struct_memoryview(self):
+        data = (
+            b"\x00\x04\x03\x02\x01\x42\x43\x44\x45\xab\xcd\xef"
+            + b"\x01\x06\x00\x02\x0001234567890"
+        )
+        self.do_test_read_jar_struct(memoryview(data))
+
+
+class TestDeflater(unittest.TestCase):
+    def wrap(self, data):
+        return data
+
+    def test_deflater_no_compress(self):
+        deflater = Deflater(False)
+        deflater.write(self.wrap(b"abc"))
+        self.assertFalse(deflater.compressed)
+        self.assertEqual(deflater.uncompressed_size, 3)
+        self.assertEqual(deflater.compressed_size, deflater.uncompressed_size)
+        self.assertEqual(deflater.compressed_data, b"abc")
+        self.assertEqual(deflater.crc32, 0x352441C2)
+
+    def test_deflater_compress_no_gain(self):
+        deflater = Deflater(True)
+        deflater.write(self.wrap(b"abc"))
+        self.assertFalse(deflater.compressed)
+        self.assertEqual(deflater.uncompressed_size, 3)
+        self.assertEqual(deflater.compressed_size, deflater.uncompressed_size)
+        self.assertEqual(deflater.compressed_data, b"abc")
+        self.assertEqual(deflater.crc32, 0x352441C2)
+
+    def test_deflater_compress(self):
+        deflater = Deflater(True)
+        deflater.write(self.wrap(b"aaaaaaaaaaaaanopqrstuvwxyz"))
+        self.assertTrue(deflater.compressed)
+        self.assertEqual(deflater.uncompressed_size, 26)
+        self.assertNotEqual(deflater.compressed_size, deflater.uncompressed_size)
+        self.assertEqual(deflater.crc32, 0xD46B97ED)
+        # The CRC is the same as when not compressed
+        deflater = Deflater(False)
+        self.assertFalse(deflater.compressed)
+        deflater.write(self.wrap(b"aaaaaaaaaaaaanopqrstuvwxyz"))
+        self.assertEqual(deflater.crc32, 0xD46B97ED)
+
+    def test_deflater_empty(self):
+        deflater = Deflater(False)
+        self.assertFalse(deflater.compressed)
+        self.assertEqual(deflater.uncompressed_size, 0)
+        self.assertEqual(deflater.compressed_size, deflater.uncompressed_size)
+        self.assertEqual(deflater.compressed_data, b"")
+        self.assertEqual(deflater.crc32, 0)
+
+
+class TestDeflaterMemoryView(TestDeflater):
+    def wrap(self, data):
+        return memoryview(data)
+
+
+class TestJar(unittest.TestCase):
+    def test_jar(self):
+        s = MockDest()
+        with JarWriter(fileobj=s) as jar:
+            jar.add("foo", b"foo")
+            self.assertRaises(JarWriterError, jar.add, "foo", b"bar")
+            jar.add("bar", b"aaaaaaaaaaaaanopqrstuvwxyz")
+            jar.add("baz/qux", b"aaaaaaaaaaaaanopqrstuvwxyz", False)
+            jar.add("baz\\backslash", b"aaaaaaaaaaaaaaa")
+
+        files = [j for j in JarReader(fileobj=s)]
+
+        self.assertEqual(files[0].filename, "foo")
+        self.assertFalse(files[0].compressed)
+        self.assertEqual(files[0].read(), b"foo")
+
+        self.assertEqual(files[1].filename, "bar")
+        self.assertTrue(files[1].compressed)
+        self.assertEqual(files[1].read(), b"aaaaaaaaaaaaanopqrstuvwxyz")
+
+        self.assertEqual(files[2].filename, "baz/qux")
+        self.assertFalse(files[2].compressed)
+        self.assertEqual(files[2].read(), b"aaaaaaaaaaaaanopqrstuvwxyz")
+
+        if os.sep == "\\":
+            self.assertEqual(
+                files[3].filename,
+                "baz/backslash",
+                "backslashes in filenames on Windows should get normalized",
+            )
+        else:
+            self.assertEqual(
+                files[3].filename,
+                "baz\\backslash",
+                "backslashes in filenames on POSIX platform are untouched",
+            )
+
+        s = MockDest()
+        with JarWriter(fileobj=s, compress=False) as jar:
+            jar.add("bar", b"aaaaaaaaaaaaanopqrstuvwxyz")
+            jar.add("foo", b"foo")
+            jar.add("baz/qux", b"aaaaaaaaaaaaanopqrstuvwxyz", True)
+
+        jar = JarReader(fileobj=s)
+        files = [j for j in jar]
+
+        self.assertEqual(files[0].filename, "bar")
+        self.assertFalse(files[0].compressed)
+        self.assertEqual(files[0].read(), b"aaaaaaaaaaaaanopqrstuvwxyz")
+
+        self.assertEqual(files[1].filename, "foo")
+        self.assertFalse(files[1].compressed)
+        self.assertEqual(files[1].read(), b"foo")
+
+        self.assertEqual(files[2].filename, "baz/qux")
+        self.assertTrue(files[2].compressed)
+        self.assertEqual(files[2].read(), b"aaaaaaaaaaaaanopqrstuvwxyz")
+
+        self.assertTrue("bar" in jar)
+        self.assertTrue("foo" in jar)
+        self.assertFalse("baz" in jar)
+        self.assertTrue("baz/qux" in jar)
+        self.assertTrue(jar["bar"], files[1])
+        self.assertTrue(jar["foo"], files[0])
+        self.assertTrue(jar["baz/qux"], files[2])
+
+        s.seek(0)
+        jar = JarReader(fileobj=s)
+        self.assertTrue("bar" in jar)
+        self.assertTrue("foo" in jar)
+        self.assertFalse("baz" in jar)
+        self.assertTrue("baz/qux" in jar)
+
+        files[0].seek(0)
+        self.assertEqual(jar["bar"].filename, files[0].filename)
+        self.assertEqual(jar["bar"].compressed, files[0].compressed)
+        self.assertEqual(jar["bar"].read(), files[0].read())
+
+        files[1].seek(0)
+        self.assertEqual(jar["foo"].filename, files[1].filename)
+        self.assertEqual(jar["foo"].compressed, files[1].compressed)
+        self.assertEqual(jar["foo"].read(), files[1].read())
+
+        files[2].seek(0)
+        self.assertEqual(jar["baz/qux"].filename, files[2].filename)
+        self.assertEqual(jar["baz/qux"].compressed, files[2].compressed)
+        self.assertEqual(jar["baz/qux"].read(), files[2].read())
+
+    def test_rejar(self):
+        s = MockDest()
+        with JarWriter(fileobj=s) as jar:
+            jar.add("foo", b"foo")
+            jar.add("bar", b"aaaaaaaaaaaaanopqrstuvwxyz")
+            jar.add("baz/qux", b"aaaaaaaaaaaaanopqrstuvwxyz", False)
+
+        new = MockDest()
+        with JarWriter(fileobj=new) as jar:
+            for j in JarReader(fileobj=s):
+                jar.add(j.filename, j)
+
+        jar = JarReader(fileobj=new)
+        files = [j for j in jar]
+
+        self.assertEqual(files[0].filename, "foo")
+        self.assertFalse(files[0].compressed)
+        self.assertEqual(files[0].read(), b"foo")
+
+        self.assertEqual(files[1].filename, "bar")
+        self.assertTrue(files[1].compressed)
+        self.assertEqual(files[1].read(), b"aaaaaaaaaaaaanopqrstuvwxyz")
+
+        self.assertEqual(files[2].filename, "baz/qux")
+        self.assertTrue(files[2].compressed)
+        self.assertEqual(files[2].read(), b"aaaaaaaaaaaaanopqrstuvwxyz")
+
+    def test_add_from_finder(self):
+        s = MockDest()
+        with JarWriter(fileobj=s) as jar:
+            finder = FileFinder(test_data_path)
+            for p, f in finder.find("test_data"):
+                jar.add("test_data", f)
+
+        jar = JarReader(fileobj=s)
+        files = [j for j in jar]
+
+        self.assertEqual(files[0].filename, "test_data")
+        self.assertFalse(files[0].compressed)
+        self.assertEqual(files[0].read(), b"test_data")
+
+
+class TestPreload(unittest.TestCase):
+    def test_preload(self):
+        s = MockDest()
+        with JarWriter(fileobj=s) as jar:
+            jar.add("foo", b"foo")
+            jar.add("bar", b"abcdefghijklmnopqrstuvwxyz")
+            jar.add("baz/qux", b"aaaaaaaaaaaaanopqrstuvwxyz")
+
+        jar = JarReader(fileobj=s)
+        self.assertEqual(jar.last_preloaded, None)
+
+        with JarWriter(fileobj=s) as jar:
+            jar.add("foo", b"foo")
+            jar.add("bar", b"abcdefghijklmnopqrstuvwxyz")
+            jar.add("baz/qux", b"aaaaaaaaaaaaanopqrstuvwxyz")
+            jar.preload(["baz/qux", "bar"])
+
+        jar = JarReader(fileobj=s)
+        self.assertEqual(jar.last_preloaded, "bar")
+        files = [j for j in jar]
+
+        self.assertEqual(files[0].filename, "baz/qux")
+        self.assertEqual(files[1].filename, "bar")
+        self.assertEqual(files[2].filename, "foo")
+
+
+class TestJarLog(unittest.TestCase):
+    def test_jarlog(self):
+        s = six.moves.cStringIO(
+            "\n".join(
+                [
+                    "bar/baz.jar first",
+                    "bar/baz.jar second",
+                    "bar/baz.jar third",
+                    "bar/baz.jar second",
+                    "bar/baz.jar second",
+                    "omni.ja stuff",
+                    "bar/baz.jar first",
+                    "omni.ja other/stuff",
+                    "omni.ja stuff",
+                    "bar/baz.jar third",
+                ]
+            )
+        )
+        log = JarLog(fileobj=s)
+        self.assertEqual(
+            set(log.keys()),
+            set(
+                [
+                    "bar/baz.jar",
+                    "omni.ja",
+                ]
+            ),
+        )
+        self.assertEqual(
+            log["bar/baz.jar"],
+            [
+                "first",
+                "second",
+                "third",
+            ],
+        )
+        self.assertEqual(
+            log["omni.ja"],
+            [
+                "stuff",
+                "other/stuff",
+            ],
+        )
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_packager.py b/python/mozbuild/mozpack/test/test_packager.py
new file mode 100644
index 0000000000..266902ebb2
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_packager.py
@@ -0,0 +1,630 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import unittest
+
+import mozunit
+from buildconfig import topobjdir
+from mozunit import MockedOpen
+
+import mozpack.path as mozpath
+from mozbuild.preprocessor import Preprocessor
+from mozpack.chrome.manifest import (
+    ManifestBinaryComponent,
+    ManifestContent,
+    ManifestResource,
+)
+from mozpack.errors import ErrorMessage, errors
+from mozpack.files import GeneratedFile
+from mozpack.packager import (
+    CallDeque,
+    Component,
+    SimpleManifestSink,
+    SimplePackager,
+    preprocess_manifest,
+)
+
+MANIFEST = """
+bar/*
+[foo]
+foo/*
+-foo/bar
+chrome.manifest
+[zot destdir="destdir"]
+foo/zot
+; comment
+#ifdef baz
+[baz]
+baz@SUFFIX@
+#endif
+"""
+
+
+class TestPreprocessManifest(unittest.TestCase):
+    MANIFEST_PATH = mozpath.join("$OBJDIR", "manifest")
+
+    EXPECTED_LOG = [
+        ((MANIFEST_PATH, 2), "add", "", "bar/*"),
+        ((MANIFEST_PATH, 4), "add", "foo", "foo/*"),
+        ((MANIFEST_PATH, 5), "remove", "foo", "foo/bar"),
+        ((MANIFEST_PATH, 6), "add", "foo", "chrome.manifest"),
+        ((MANIFEST_PATH, 8), "add", 'zot destdir="destdir"', "foo/zot"),
+    ]
+
+    def setUp(self):
+        class MockSink(object):
+            def __init__(self):
+                self.log = []
+
+            def add(self, component, path):
+                self._log(errors.get_context(), "add", repr(component), path)
+
+            def remove(self, component, path):
+                self._log(errors.get_context(), "remove", repr(component), path)
+
+            def _log(self, *args):
+                self.log.append(args)
+
+        self.sink = MockSink()
+        self.cwd = os.getcwd()
+        os.chdir(topobjdir)
+
+    def tearDown(self):
+        os.chdir(self.cwd)
+
+    def test_preprocess_manifest(self):
+        with MockedOpen({"manifest": MANIFEST}):
+            preprocess_manifest(self.sink, "manifest")
+        self.assertEqual(self.sink.log, self.EXPECTED_LOG)
+
+    def test_preprocess_manifest_missing_define(self):
+        with MockedOpen({"manifest": MANIFEST}):
+            self.assertRaises(
+                Preprocessor.Error,
+                preprocess_manifest,
+                self.sink,
+                "manifest",
+                {"baz": 1},
+            )
+
+    def test_preprocess_manifest_defines(self):
+        with MockedOpen({"manifest": MANIFEST}):
+            preprocess_manifest(self.sink, "manifest", {"baz": 1, "SUFFIX": ".exe"})
+        self.assertEqual(
+            self.sink.log,
+            self.EXPECTED_LOG + [((self.MANIFEST_PATH, 12), "add", "baz", "baz.exe")],
+        )
+
+
+class MockFinder(object):
+    def __init__(self, files):
+        self.files = files
+        self.log = []
+
+    def find(self, path):
+        self.log.append(path)
+        for f in sorted(self.files):
+            if mozpath.match(f, path):
+                yield f, self.files[f]
+
+    def __iter__(self):
+        return self.find("")
+
+
+class MockFormatter(object):
+    def __init__(self):
+        self.log = []
+
+    def add_base(self, *args):
+        self._log(errors.get_context(), "add_base", *args)
+
+    def add_manifest(self, *args):
+        self._log(errors.get_context(), "add_manifest", *args)
+
+    def add_interfaces(self, *args):
+        self._log(errors.get_context(), "add_interfaces", *args)
+
+    def add(self, *args):
+        self._log(errors.get_context(), "add", *args)
+
+    def _log(self, *args):
+        self.log.append(args)
+
+
+class TestSimplePackager(unittest.TestCase):
+    def test_simple_packager(self):
+        class GeneratedFileWithPath(GeneratedFile):
+            def __init__(self, path, content):
+                GeneratedFile.__init__(self, content)
+                self.path = path
+
+        formatter = MockFormatter()
+        packager = SimplePackager(formatter)
+        curdir = os.path.abspath(os.curdir)
+        file = GeneratedFileWithPath(
+            os.path.join(curdir, "foo", "bar.manifest"),
+            b"resource bar bar/\ncontent bar bar/",
+        )
+        with errors.context("manifest", 1):
+            packager.add("foo/bar.manifest", file)
+
+        file = GeneratedFileWithPath(
+            os.path.join(curdir, "foo", "baz.manifest"), b"resource baz baz/"
+        )
+        with errors.context("manifest", 2):
+            packager.add("bar/baz.manifest", file)
+
+        with errors.context("manifest", 3):
+            packager.add(
+                "qux/qux.manifest",
+                GeneratedFile(
+                    b"".join(
+                        [
+                            b"resource qux qux/\n",
+                            b"binary-component qux.so\n",
+                        ]
+                    )
+                ),
+            )
+        bar_xpt = GeneratedFile(b"bar.xpt")
+        qux_xpt = GeneratedFile(b"qux.xpt")
+        foo_html = GeneratedFile(b"foo_html")
+        bar_html = GeneratedFile(b"bar_html")
+        with errors.context("manifest", 4):
+            packager.add("foo/bar.xpt", bar_xpt)
+        with errors.context("manifest", 5):
+            packager.add("foo/bar/foo.html", foo_html)
+            packager.add("foo/bar/bar.html", bar_html)
+
+        file = GeneratedFileWithPath(
+            os.path.join(curdir, "foo.manifest"),
+            b"".join(
+                [
+                    b"manifest foo/bar.manifest\n",
+                    b"manifest bar/baz.manifest\n",
+                ]
+            ),
+        )
+        with errors.context("manifest", 6):
+            packager.add("foo.manifest", file)
+        with errors.context("manifest", 7):
+            packager.add("foo/qux.xpt", qux_xpt)
+
+        file = GeneratedFileWithPath(
+            os.path.join(curdir, "addon", "chrome.manifest"), b"resource hoge hoge/"
+        )
+        with errors.context("manifest", 8):
+            packager.add("addon/chrome.manifest", file)
+
+        install_rdf = GeneratedFile(b"<RDF></RDF>")
+        with errors.context("manifest", 9):
+            packager.add("addon/install.rdf", install_rdf)
+
+        with errors.context("manifest", 10):
+            packager.add("addon2/install.rdf", install_rdf)
+            packager.add(
+                "addon2/chrome.manifest", GeneratedFile(b"binary-component addon2.so")
+            )
+
+        with errors.context("manifest", 11):
+            packager.add("addon3/install.rdf", install_rdf)
+            packager.add(
+                "addon3/chrome.manifest",
+                GeneratedFile(b"manifest components/components.manifest"),
+            )
+            packager.add(
+                "addon3/components/components.manifest",
+                GeneratedFile(b"binary-component addon3.so"),
+            )
+
+        with errors.context("manifest", 12):
+            install_rdf_addon4 = GeneratedFile(
+                b"<RDF>\n<...>\n<em:unpack>true</em:unpack>\n<...>\n</RDF>"
+            )
+            packager.add("addon4/install.rdf", install_rdf_addon4)
+
+        with errors.context("manifest", 13):
+            install_rdf_addon5 = GeneratedFile(
+                b"<RDF>\n<...>\n<em:unpack>false</em:unpack>\n<...>\n</RDF>"
+            )
+            packager.add("addon5/install.rdf", install_rdf_addon5)
+
+        with errors.context("manifest", 14):
+            install_rdf_addon6 = GeneratedFile(
+                b"<RDF>\n<... em:unpack=true>\n<...>\n</RDF>"
+            )
+            packager.add("addon6/install.rdf", install_rdf_addon6)
+
+        with errors.context("manifest", 15):
+            install_rdf_addon7 = GeneratedFile(
+                b"<RDF>\n<... em:unpack=false>\n<...>\n</RDF>"
+            )
+            packager.add("addon7/install.rdf", install_rdf_addon7)
+
+        with errors.context("manifest", 16):
+            install_rdf_addon8 = GeneratedFile(
+                b'<RDF>\n<... em:unpack="true">\n<...>\n</RDF>'
+            )
+            packager.add("addon8/install.rdf", install_rdf_addon8)
+
+        with errors.context("manifest", 17):
+            install_rdf_addon9 = GeneratedFile(
+                b'<RDF>\n<... em:unpack="false">\n<...>\n</RDF>'
+            )
+            packager.add("addon9/install.rdf", install_rdf_addon9)
+
+        with errors.context("manifest", 18):
+            install_rdf_addon10 = GeneratedFile(
+                b"<RDF>\n<... em:unpack='true'>\n<...>\n</RDF>"
+            )
+            packager.add("addon10/install.rdf", install_rdf_addon10)
+
+        with errors.context("manifest", 19):
+            install_rdf_addon11 = GeneratedFile(
+                b"<RDF>\n<... em:unpack='false'>\n<...>\n</RDF>"
+            )
+            packager.add("addon11/install.rdf", install_rdf_addon11)
+
+        we_manifest = GeneratedFile(
+            b'{"manifest_version": 2, "name": "Test WebExtension", "version": "1.0"}'
+        )
+        # hybrid and hybrid2 are both bootstrapped extensions with
+        # embedded webextensions, they differ in the order in which
+        # the manifests are added to the packager.
+        with errors.context("manifest", 20):
+            packager.add("hybrid/install.rdf", install_rdf)
+
+        with errors.context("manifest", 21):
+            packager.add("hybrid/webextension/manifest.json", we_manifest)
+
+        with errors.context("manifest", 22):
+            packager.add("hybrid2/webextension/manifest.json", we_manifest)
+
+        with errors.context("manifest", 23):
+            packager.add("hybrid2/install.rdf", install_rdf)
+
+        with errors.context("manifest", 24):
+            packager.add("webextension/manifest.json", we_manifest)
+
+        non_we_manifest = GeneratedFile(b'{"not a webextension": true}')
+        with errors.context("manifest", 25):
+            packager.add("nonwebextension/manifest.json", non_we_manifest)
+
+        self.assertEqual(formatter.log, [])
+
+        with errors.context("dummy", 1):
+            packager.close()
+        self.maxDiff = None
+        # The formatter is expected to reorder the manifest entries so that
+        # chrome entries appear before the others.
+        self.assertEqual(
+            formatter.log,
+            [
+                (("dummy", 1), "add_base", "", False),
+                (("dummy", 1), "add_base", "addon", True),
+                (("dummy", 1), "add_base", "addon10", "unpacked"),
+                (("dummy", 1), "add_base", "addon11", True),
+                (("dummy", 1), "add_base", "addon2", "unpacked"),
+                (("dummy", 1), "add_base", "addon3", "unpacked"),
+                (("dummy", 1), "add_base", "addon4", "unpacked"),
+                (("dummy", 1), "add_base", "addon5", True),
+                (("dummy", 1), "add_base", "addon6", "unpacked"),
+                (("dummy", 1), "add_base", "addon7", True),
+                (("dummy", 1), "add_base", "addon8", "unpacked"),
+                (("dummy", 1), "add_base", "addon9", True),
+                (("dummy", 1), "add_base", "hybrid", True),
+                (("dummy", 1), "add_base", "hybrid2", True),
+                (("dummy", 1), "add_base", "qux", False),
+                (("dummy", 1), "add_base", "webextension", True),
+                (
+                    (os.path.join(curdir, "foo", "bar.manifest"), 2),
+                    "add_manifest",
+                    ManifestContent("foo", "bar", "bar/"),
+                ),
+                (
+                    (os.path.join(curdir, "foo", "bar.manifest"), 1),
+                    "add_manifest",
+                    ManifestResource("foo", "bar", "bar/"),
+                ),
+                (
+                    ("bar/baz.manifest", 1),
+                    "add_manifest",
+                    ManifestResource("bar", "baz", "baz/"),
+                ),
+                (
+                    ("qux/qux.manifest", 1),
+                    "add_manifest",
+                    ManifestResource("qux", "qux", "qux/"),
+                ),
+                (
+                    ("qux/qux.manifest", 2),
+                    "add_manifest",
+                    ManifestBinaryComponent("qux", "qux.so"),
+                ),
+                (("manifest", 4), "add_interfaces", "foo/bar.xpt", bar_xpt),
+                (("manifest", 7), "add_interfaces", "foo/qux.xpt", qux_xpt),
+                (
+                    (os.path.join(curdir, "addon", "chrome.manifest"), 1),
+                    "add_manifest",
+                    ManifestResource("addon", "hoge", "hoge/"),
+                ),
+                (
+                    ("addon2/chrome.manifest", 1),
+                    "add_manifest",
+                    ManifestBinaryComponent("addon2", "addon2.so"),
+                ),
+                (
+                    ("addon3/components/components.manifest", 1),
+                    "add_manifest",
+                    ManifestBinaryComponent("addon3/components", "addon3.so"),
+                ),
+                (("manifest", 5), "add", "foo/bar/foo.html", foo_html),
+                (("manifest", 5), "add", "foo/bar/bar.html", bar_html),
+                (("manifest", 9), "add", "addon/install.rdf", install_rdf),
+                (("manifest", 10), "add", "addon2/install.rdf", install_rdf),
+                (("manifest", 11), "add", "addon3/install.rdf", install_rdf),
+                (("manifest", 12), "add", "addon4/install.rdf", install_rdf_addon4),
+                (("manifest", 13), "add", "addon5/install.rdf", install_rdf_addon5),
+                (("manifest", 14), "add", "addon6/install.rdf", install_rdf_addon6),
+                (("manifest", 15), "add", "addon7/install.rdf", install_rdf_addon7),
+                (("manifest", 16), "add", "addon8/install.rdf", install_rdf_addon8),
+                (("manifest", 17), "add", "addon9/install.rdf", install_rdf_addon9),
+                (("manifest", 18), "add", "addon10/install.rdf", install_rdf_addon10),
+                (("manifest", 19), "add", "addon11/install.rdf", install_rdf_addon11),
+                (("manifest", 20), "add", "hybrid/install.rdf", install_rdf),
+                (
+                    ("manifest", 21),
+                    "add",
+                    "hybrid/webextension/manifest.json",
+                    we_manifest,
+                ),
+                (
+                    ("manifest", 22),
+                    "add",
+                    "hybrid2/webextension/manifest.json",
+                    we_manifest,
+                ),
+                (("manifest", 23), "add", "hybrid2/install.rdf", install_rdf),
+                (("manifest", 24), "add", "webextension/manifest.json", we_manifest),
+                (
+                    ("manifest", 25),
+                    "add",
+                    "nonwebextension/manifest.json",
+                    non_we_manifest,
+                ),
+            ],
+        )
+
+        self.assertEqual(
+            packager.get_bases(),
+            set(
+                [
+                    "",
+                    "addon",
+                    "addon2",
+                    "addon3",
+                    "addon4",
+                    "addon5",
+                    "addon6",
+                    "addon7",
+                    "addon8",
+                    "addon9",
+                    "addon10",
+                    "addon11",
+                    "qux",
+                    "hybrid",
+                    "hybrid2",
+                    "webextension",
+                ]
+            ),
+        )
+        self.assertEqual(packager.get_bases(addons=False), set(["", "qux"]))
+
+    def test_simple_packager_manifest_consistency(self):
+        formatter = MockFormatter()
+        # bar/ is detected as an addon because of install.rdf, but top-level
+        # includes a manifest inside bar/.
+        packager = SimplePackager(formatter)
+        packager.add(
+            "base.manifest",
+            GeneratedFile(
+                b"manifest foo/bar.manifest\n" b"manifest bar/baz.manifest\n"
+            ),
+        )
+        packager.add("foo/bar.manifest", GeneratedFile(b"resource bar bar"))
+        packager.add("bar/baz.manifest", GeneratedFile(b"resource baz baz"))
+        packager.add("bar/install.rdf", GeneratedFile(b""))
+
+        with self.assertRaises(ErrorMessage) as e:
+            packager.close()
+
+        self.assertEqual(
+            str(e.exception),
+            'error: "bar/baz.manifest" is included from "base.manifest", '
+            'which is outside "bar"',
+        )
+
+        # bar/ is detected as a separate base because of chrome.manifest that
+        # is included nowhere, but top-level includes another manifest inside
+        # bar/.
+        packager = SimplePackager(formatter)
+        packager.add(
+            "base.manifest",
+            GeneratedFile(
+                b"manifest foo/bar.manifest\n" b"manifest bar/baz.manifest\n"
+            ),
+        )
+        packager.add("foo/bar.manifest", GeneratedFile(b"resource bar bar"))
+        packager.add("bar/baz.manifest", GeneratedFile(b"resource baz baz"))
+        packager.add("bar/chrome.manifest", GeneratedFile(b"resource baz baz"))
+
+        with self.assertRaises(ErrorMessage) as e:
+            packager.close()
+
+        self.assertEqual(
+            str(e.exception),
+            'error: "bar/baz.manifest" is included from "base.manifest", '
+            'which is outside "bar"',
+        )
+
+        # bar/ is detected as a separate base because of chrome.manifest that
+        # is included nowhere, but chrome.manifest includes baz.manifest from
+        # the same directory. This shouldn't error out.
+        packager = SimplePackager(formatter)
+        packager.add("base.manifest", GeneratedFile(b"manifest foo/bar.manifest\n"))
+        packager.add("foo/bar.manifest", GeneratedFile(b"resource bar bar"))
+        packager.add("bar/baz.manifest", GeneratedFile(b"resource baz baz"))
+        packager.add("bar/chrome.manifest", GeneratedFile(b"manifest baz.manifest"))
+        packager.close()
+
+
+class TestSimpleManifestSink(unittest.TestCase):
+    def test_simple_manifest_parser(self):
+        formatter = MockFormatter()
+        foobar = GeneratedFile(b"foobar")
+        foobaz = GeneratedFile(b"foobaz")
+        fooqux = GeneratedFile(b"fooqux")
+        foozot = GeneratedFile(b"foozot")
+        finder = MockFinder(
+            {
+                "bin/foo/bar": foobar,
+                "bin/foo/baz": foobaz,
+                "bin/foo/qux": fooqux,
+                "bin/foo/zot": foozot,
+                "bin/foo/chrome.manifest": GeneratedFile(b"resource foo foo/"),
+                "bin/chrome.manifest": GeneratedFile(b"manifest foo/chrome.manifest"),
+            }
+        )
+        parser = SimpleManifestSink(finder, formatter)
+        component0 = Component("component0")
+        component1 = Component("component1")
+        component2 = Component("component2", destdir="destdir")
+        parser.add(component0, "bin/foo/b*")
+        parser.add(component1, "bin/foo/qux")
+        parser.add(component1, "bin/foo/chrome.manifest")
+        parser.add(component2, "bin/foo/zot")
+        self.assertRaises(ErrorMessage, parser.add, "component1", "bin/bar")
+
+        self.assertEqual(formatter.log, [])
+        parser.close()
+        self.assertEqual(
+            formatter.log,
+            [
+                (None, "add_base", "", False),
+                (
+                    ("foo/chrome.manifest", 1),
+                    "add_manifest",
+                    ManifestResource("foo", "foo", "foo/"),
+                ),
+                (None, "add", "foo/bar", foobar),
+                (None, "add", "foo/baz", foobaz),
+                (None, "add", "foo/qux", fooqux),
+                (None, "add", "destdir/foo/zot", foozot),
+            ],
+        )
+
+        self.assertEqual(
+            finder.log,
+            [
+                "bin/foo/b*",
+                "bin/foo/qux",
+                "bin/foo/chrome.manifest",
+                "bin/foo/zot",
+                "bin/bar",
+                "bin/chrome.manifest",
+            ],
+        )
+
+
+class TestCallDeque(unittest.TestCase):
+    def test_call_deque(self):
+        class Logger(object):
+            def __init__(self):
+                self._log = []
+
+            def log(self, str):
+                self._log.append(str)
+
+            @staticmethod
+            def staticlog(logger, str):
+                logger.log(str)
+
+        def do_log(logger, str):
+            logger.log(str)
+
+        logger = Logger()
+        d = CallDeque()
+        d.append(logger.log, "foo")
+        d.append(logger.log, "bar")
+        d.append(logger.staticlog, logger, "baz")
+        d.append(do_log, logger, "qux")
+        self.assertEqual(logger._log, [])
+        d.execute()
+        self.assertEqual(logger._log, ["foo", "bar", "baz", "qux"])
+
+
+class TestComponent(unittest.TestCase):
+    def do_split(self, string, name, options):
+        n, o = Component._split_component_and_options(string)
+        self.assertEqual(name, n)
+        self.assertEqual(options, o)
+
+    def test_component_split_component_and_options(self):
+        self.do_split("component", "component", {})
+        self.do_split("trailingspace ", "trailingspace", {})
+        self.do_split(" leadingspace", "leadingspace", {})
+        self.do_split(" trim ", "trim", {})
+        self.do_split(' trim key="value"', "trim", {"key": "value"})
+        self.do_split(' trim empty=""', "trim", {"empty": ""})
+        self.do_split(' trim space=" "', "trim", {"space": " "})
+        self.do_split(
+            'component key="value"  key2="second" ',
+            "component",
+            {"key": "value", "key2": "second"},
+        )
+        self.do_split(
+            'trim key="  value with spaces   "  key2="spaces again"',
+            "trim",
+            {"key": "  value with spaces   ", "key2": "spaces again"},
+        )
+
+    def do_split_error(self, string):
+        self.assertRaises(ValueError, Component._split_component_and_options, string)
+
+    def test_component_split_component_and_options_errors(self):
+        self.do_split_error('"component')
+        self.do_split_error('comp"onent')
+        self.do_split_error('component"')
+        self.do_split_error('"component"')
+        self.do_split_error("=component")
+        self.do_split_error("comp=onent")
+        self.do_split_error("component=")
+        self.do_split_error('key="val"')
+        self.do_split_error("component key=")
+        self.do_split_error('component key="val')
+        self.do_split_error('component key=val"')
+        self.do_split_error('component key="val" x')
+        self.do_split_error('component x key="val"')
+        self.do_split_error('component key1="val" x key2="val"')
+
+    def do_from_string(self, string, name, destdir=""):
+        component = Component.from_string(string)
+        self.assertEqual(name, component.name)
+        self.assertEqual(destdir, component.destdir)
+
+    def test_component_from_string(self):
+        self.do_from_string("component", "component")
+        self.do_from_string("component-with-hyphen", "component-with-hyphen")
+        self.do_from_string('component destdir="foo/bar"', "component", "foo/bar")
+        self.do_from_string('component destdir="bar spc"', "component", "bar spc")
+        self.assertRaises(ErrorMessage, Component.from_string, "")
+        self.assertRaises(ErrorMessage, Component.from_string, "component novalue=")
+        self.assertRaises(
+            ErrorMessage, Component.from_string, "component badoption=badvalue"
+        )
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_packager_formats.py b/python/mozbuild/mozpack/test/test_packager_formats.py
new file mode 100644
index 0000000000..b09971a102
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_packager_formats.py
@@ -0,0 +1,537 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import unittest
+from itertools import chain
+
+import mozunit
+import six
+
+import mozpack.path as mozpath
+from mozpack.chrome.manifest import (
+    ManifestBinaryComponent,
+    ManifestComponent,
+    ManifestContent,
+    ManifestLocale,
+    ManifestResource,
+    ManifestSkin,
+)
+from mozpack.copier import FileRegistry
+from mozpack.errors import ErrorMessage
+from mozpack.files import GeneratedFile, ManifestFile
+from mozpack.packager.formats import FlatFormatter, JarFormatter, OmniJarFormatter
+from mozpack.test.test_files import bar_xpt, foo2_xpt, foo_xpt
+from test_errors import TestErrors
+
+CONTENTS = {
+    "bases": {
+        # base_path: is_addon?
+        "": False,
+        "app": False,
+        "addon0": "unpacked",
+        "addon1": True,
+        "app/chrome/addons/addon2": True,
+    },
+    "manifests": [
+        ManifestContent("chrome/f", "oo", "oo/"),
+        ManifestContent("chrome/f", "bar", "oo/bar/"),
+        ManifestResource("chrome/f", "foo", "resource://bar/"),
+        ManifestBinaryComponent("components", "foo.so"),
+        ManifestContent("app/chrome", "content", "foo/"),
+        ManifestComponent("app/components", "{foo-id}", "foo.js"),
+        ManifestContent("addon0/chrome", "addon0", "foo/bar/"),
+        ManifestContent("addon1/chrome", "addon1", "foo/bar/"),
+        ManifestContent("app/chrome/addons/addon2/chrome", "addon2", "foo/bar/"),
+    ],
+    "files": {
+        "chrome/f/oo/bar/baz": GeneratedFile(b"foobarbaz"),
+        "chrome/f/oo/baz": GeneratedFile(b"foobaz"),
+        "chrome/f/oo/qux": GeneratedFile(b"fooqux"),
+        "components/foo.so": GeneratedFile(b"foo.so"),
+        "components/foo.xpt": foo_xpt,
+        "components/bar.xpt": bar_xpt,
+        "foo": GeneratedFile(b"foo"),
+        "app/chrome/foo/foo": GeneratedFile(b"appfoo"),
+        "app/components/foo.js": GeneratedFile(b"foo.js"),
+        "addon0/chrome/foo/bar/baz": GeneratedFile(b"foobarbaz"),
+        "addon0/components/foo.xpt": foo2_xpt,
+        "addon0/components/bar.xpt": bar_xpt,
+        "addon1/chrome/foo/bar/baz": GeneratedFile(b"foobarbaz"),
+        "addon1/components/foo.xpt": foo2_xpt,
+        "addon1/components/bar.xpt": bar_xpt,
+        "app/chrome/addons/addon2/chrome/foo/bar/baz": GeneratedFile(b"foobarbaz"),
+        "app/chrome/addons/addon2/components/foo.xpt": foo2_xpt,
+        "app/chrome/addons/addon2/components/bar.xpt": bar_xpt,
+    },
+}
+
+FILES = CONTENTS["files"]
+
+RESULT_FLAT = {
+    "chrome.manifest": [
+        "manifest chrome/chrome.manifest",
+        "manifest components/components.manifest",
+    ],
+    "chrome/chrome.manifest": [
+        "manifest f/f.manifest",
+    ],
+    "chrome/f/f.manifest": [
+        "content oo oo/",
+        "content bar oo/bar/",
+        "resource foo resource://bar/",
+    ],
+    "chrome/f/oo/bar/baz": FILES["chrome/f/oo/bar/baz"],
+    "chrome/f/oo/baz": FILES["chrome/f/oo/baz"],
+    "chrome/f/oo/qux": FILES["chrome/f/oo/qux"],
+    "components/components.manifest": [
+        "binary-component foo.so",
+        "interfaces bar.xpt",
+        "interfaces foo.xpt",
+    ],
+    "components/foo.so": FILES["components/foo.so"],
+    "components/foo.xpt": foo_xpt,
+    "components/bar.xpt": bar_xpt,
+    "foo": FILES["foo"],
+    "app/chrome.manifest": [
+        "manifest chrome/chrome.manifest",
+        "manifest components/components.manifest",
+    ],
+    "app/chrome/chrome.manifest": [
+        "content content foo/",
+    ],
+    "app/chrome/foo/foo": FILES["app/chrome/foo/foo"],
+    "app/components/components.manifest": [
+        "component {foo-id} foo.js",
+    ],
+    "app/components/foo.js": FILES["app/components/foo.js"],
+}
+
+for addon in ("addon0", "addon1", "app/chrome/addons/addon2"):
+    RESULT_FLAT.update(
+        {
+            mozpath.join(addon, p): f
+            for p, f in six.iteritems(
+                {
+                    "chrome.manifest": [
+                        "manifest chrome/chrome.manifest",
+                        "manifest components/components.manifest",
+                    ],
+                    "chrome/chrome.manifest": [
+                        "content %s foo/bar/" % mozpath.basename(addon),
+                    ],
+                    "chrome/foo/bar/baz": FILES[
+                        mozpath.join(addon, "chrome/foo/bar/baz")
+                    ],
+                    "components/components.manifest": [
+                        "interfaces bar.xpt",
+                        "interfaces foo.xpt",
+                    ],
+                    "components/bar.xpt": bar_xpt,
+                    "components/foo.xpt": foo2_xpt,
+                }
+            )
+        }
+    )
+
+RESULT_JAR = {
+    p: RESULT_FLAT[p]
+    for p in (
+        "chrome.manifest",
+        "chrome/chrome.manifest",
+        "components/components.manifest",
+        "components/foo.so",
+        "components/foo.xpt",
+        "components/bar.xpt",
+        "foo",
+        "app/chrome.manifest",
+        "app/components/components.manifest",
+        "app/components/foo.js",
+        "addon0/chrome.manifest",
+        "addon0/components/components.manifest",
+        "addon0/components/foo.xpt",
+        "addon0/components/bar.xpt",
+    )
+}
+
+RESULT_JAR.update(
+    {
+        "chrome/f/f.manifest": [
+            "content oo jar:oo.jar!/",
+            "content bar jar:oo.jar!/bar/",
+            "resource foo resource://bar/",
+        ],
+        "chrome/f/oo.jar": {
+            "bar/baz": FILES["chrome/f/oo/bar/baz"],
+            "baz": FILES["chrome/f/oo/baz"],
+            "qux": FILES["chrome/f/oo/qux"],
+        },
+        "app/chrome/chrome.manifest": [
+            "content content jar:foo.jar!/",
+        ],
+        "app/chrome/foo.jar": {
+            "foo": FILES["app/chrome/foo/foo"],
+        },
+        "addon0/chrome/chrome.manifest": [
+            "content addon0 jar:foo.jar!/bar/",
+        ],
+        "addon0/chrome/foo.jar": {
+            "bar/baz": FILES["addon0/chrome/foo/bar/baz"],
+        },
+        "addon1.xpi": {
+            mozpath.relpath(p, "addon1"): f
+            for p, f in six.iteritems(RESULT_FLAT)
+            if p.startswith("addon1/")
+        },
+        "app/chrome/addons/addon2.xpi": {
+            mozpath.relpath(p, "app/chrome/addons/addon2"): f
+            for p, f in six.iteritems(RESULT_FLAT)
+            if p.startswith("app/chrome/addons/addon2/")
+        },
+    }
+)
+
+RESULT_OMNIJAR = {
+    p: RESULT_FLAT[p]
+    for p in (
+        "components/foo.so",
+        "foo",
+    )
+}
+
+RESULT_OMNIJAR.update({p: RESULT_JAR[p] for p in RESULT_JAR if p.startswith("addon")})
+
+RESULT_OMNIJAR.update(
+    {
+        "omni.foo": {
+            "components/components.manifest": [
+                "interfaces bar.xpt",
+                "interfaces foo.xpt",
+            ],
+        },
+        "chrome.manifest": [
+            "manifest components/components.manifest",
+        ],
+        "components/components.manifest": [
+            "binary-component foo.so",
+        ],
+        "app/omni.foo": {
+            p: RESULT_FLAT["app/" + p]
+            for p in chain(
+                (
+                    "chrome.manifest",
+                    "chrome/chrome.manifest",
+                    "chrome/foo/foo",
+                    "components/components.manifest",
+                    "components/foo.js",
+                ),
+                (
+                    mozpath.relpath(p, "app")
+                    for p in six.iterkeys(RESULT_FLAT)
+                    if p.startswith("app/chrome/addons/addon2/")
+                ),
+            )
+        },
+    }
+)
+
+RESULT_OMNIJAR["omni.foo"].update(
+    {
+        p: RESULT_FLAT[p]
+        for p in (
+            "chrome.manifest",
+            "chrome/chrome.manifest",
+            "chrome/f/f.manifest",
+            "chrome/f/oo/bar/baz",
+            "chrome/f/oo/baz",
+            "chrome/f/oo/qux",
+            "components/foo.xpt",
+            "components/bar.xpt",
+        )
+    }
+)
+
+RESULT_OMNIJAR_WITH_SUBPATH = {
+    k.replace("omni.foo", "bar/omni.foo"): v for k, v in RESULT_OMNIJAR.items()
+}
+
+CONTENTS_WITH_BASE = {
+    "bases": {
+        mozpath.join("base/root", b) if b else "base/root": a
+        for b, a in six.iteritems(CONTENTS["bases"])
+    },
+    "manifests": [
+        m.move(mozpath.join("base/root", m.base)) for m in CONTENTS["manifests"]
+    ],
+    "files": {
+        mozpath.join("base/root", p): f for p, f in six.iteritems(CONTENTS["files"])
+    },
+}
+
+EXTRA_CONTENTS = {
+    "extra/file": GeneratedFile(b"extra file"),
+}
+
+CONTENTS_WITH_BASE["files"].update(EXTRA_CONTENTS)
+
+
+def result_with_base(results):
+    result = {mozpath.join("base/root", p): v for p, v in six.iteritems(results)}
+    result.update(EXTRA_CONTENTS)
+    return result
+
+
+RESULT_FLAT_WITH_BASE = result_with_base(RESULT_FLAT)
+RESULT_JAR_WITH_BASE = result_with_base(RESULT_JAR)
+RESULT_OMNIJAR_WITH_BASE = result_with_base(RESULT_OMNIJAR)
+
+
+def fill_formatter(formatter, contents):
+    for base, is_addon in sorted(contents["bases"].items()):
+        formatter.add_base(base, is_addon)
+
+    for manifest in contents["manifests"]:
+        formatter.add_manifest(manifest)
+
+    for k, v in sorted(six.iteritems(contents["files"])):
+        if k.endswith(".xpt"):
+            formatter.add_interfaces(k, v)
+        else:
+            formatter.add(k, v)
+
+
+def get_contents(registry, read_all=False, mode="rt"):
+    result = {}
+    for k, v in registry:
+        if isinstance(v, FileRegistry):
+            result[k] = get_contents(v)
+        elif isinstance(v, ManifestFile) or read_all:
+            if "b" in mode:
+                result[k] = v.open().read()
+            else:
+                result[k] = six.ensure_text(v.open().read()).splitlines()
+        else:
+            result[k] = v
+    return result
+
+
+class TestFormatters(TestErrors, unittest.TestCase):
+    maxDiff = None
+
+    def test_bases(self):
+        formatter = FlatFormatter(FileRegistry())
+        formatter.add_base("")
+        formatter.add_base("addon0", addon=True)
+        formatter.add_base("browser")
+        self.assertEqual(formatter._get_base("platform.ini"), ("", "platform.ini"))
+        self.assertEqual(
+            formatter._get_base("browser/application.ini"),
+            ("browser", "application.ini"),
+        )
+        self.assertEqual(
+            formatter._get_base("addon0/install.rdf"), ("addon0", "install.rdf")
+        )
+
+    def do_test_contents(self, formatter, contents):
+        for f in contents["files"]:
+            # .xpt files are merged, so skip them.
+            if not f.endswith(".xpt"):
+                self.assertTrue(formatter.contains(f))
+
+    def test_flat_formatter(self):
+        registry = FileRegistry()
+        formatter = FlatFormatter(registry)
+
+        fill_formatter(formatter, CONTENTS)
+        self.assertEqual(get_contents(registry), RESULT_FLAT)
+        self.do_test_contents(formatter, CONTENTS)
+
+    def test_jar_formatter(self):
+        registry = FileRegistry()
+        formatter = JarFormatter(registry)
+
+        fill_formatter(formatter, CONTENTS)
+        self.assertEqual(get_contents(registry), RESULT_JAR)
+        self.do_test_contents(formatter, CONTENTS)
+
+    def test_omnijar_formatter(self):
+        registry = FileRegistry()
+        formatter = OmniJarFormatter(registry, "omni.foo")
+
+        fill_formatter(formatter, CONTENTS)
+        self.assertEqual(get_contents(registry), RESULT_OMNIJAR)
+        self.do_test_contents(formatter, CONTENTS)
+
+    def test_flat_formatter_with_base(self):
+        registry = FileRegistry()
+        formatter = FlatFormatter(registry)
+
+        fill_formatter(formatter, CONTENTS_WITH_BASE)
+        self.assertEqual(get_contents(registry), RESULT_FLAT_WITH_BASE)
+        self.do_test_contents(formatter, CONTENTS_WITH_BASE)
+
+    def test_jar_formatter_with_base(self):
+        registry = FileRegistry()
+        formatter = JarFormatter(registry)
+
+        fill_formatter(formatter, CONTENTS_WITH_BASE)
+        self.assertEqual(get_contents(registry), RESULT_JAR_WITH_BASE)
+        self.do_test_contents(formatter, CONTENTS_WITH_BASE)
+
+    def test_omnijar_formatter_with_base(self):
+        registry = FileRegistry()
+        formatter = OmniJarFormatter(registry, "omni.foo")
+
+        fill_formatter(formatter, CONTENTS_WITH_BASE)
+        self.assertEqual(get_contents(registry), RESULT_OMNIJAR_WITH_BASE)
+        self.do_test_contents(formatter, CONTENTS_WITH_BASE)
+
+    def test_omnijar_formatter_with_subpath(self):
+        registry = FileRegistry()
+        formatter = OmniJarFormatter(registry, "bar/omni.foo")
+
+        fill_formatter(formatter, CONTENTS)
+        self.assertEqual(get_contents(registry), RESULT_OMNIJAR_WITH_SUBPATH)
+        self.do_test_contents(formatter, CONTENTS)
+
+    def test_omnijar_is_resource(self):
+        def is_resource(base, path):
+            registry = FileRegistry()
+            f = OmniJarFormatter(
+                registry,
+                "omni.foo",
+                non_resources=[
+                    "defaults/messenger/mailViews.dat",
+                    "defaults/foo/*",
+                    "*/dummy",
+                ],
+            )
+            f.add_base("")
+            f.add_base("app")
+            f.add(mozpath.join(base, path), GeneratedFile(b""))
+            if f.copier.contains(mozpath.join(base, path)):
+                return False
+            self.assertTrue(f.copier.contains(mozpath.join(base, "omni.foo")))
+            self.assertTrue(f.copier[mozpath.join(base, "omni.foo")].contains(path))
+            return True
+
+        for base in ["", "app/"]:
+            self.assertTrue(is_resource(base, "chrome"))
+            self.assertTrue(is_resource(base, "chrome/foo/bar/baz.properties"))
+            self.assertFalse(is_resource(base, "chrome/icons/foo.png"))
+            self.assertTrue(is_resource(base, "components/foo.js"))
+            self.assertFalse(is_resource(base, "components/foo.so"))
+            self.assertTrue(is_resource(base, "res/foo.css"))
+            self.assertFalse(is_resource(base, "res/cursors/foo.png"))
+            self.assertFalse(is_resource(base, "res/MainMenu.nib/foo"))
+            self.assertTrue(is_resource(base, "defaults/pref/foo.js"))
+            self.assertFalse(is_resource(base, "defaults/pref/channel-prefs.js"))
+            self.assertTrue(is_resource(base, "defaults/preferences/foo.js"))
+            self.assertFalse(is_resource(base, "defaults/preferences/channel-prefs.js"))
+            self.assertTrue(is_resource(base, "modules/foo.jsm"))
+            self.assertTrue(is_resource(base, "greprefs.js"))
+            self.assertTrue(is_resource(base, "hyphenation/foo"))
+            self.assertTrue(is_resource(base, "update.locale"))
+            self.assertFalse(is_resource(base, "foo"))
+            self.assertFalse(is_resource(base, "foo/bar/greprefs.js"))
+            self.assertTrue(is_resource(base, "defaults/messenger/foo.dat"))
+            self.assertFalse(is_resource(base, "defaults/messenger/mailViews.dat"))
+            self.assertTrue(is_resource(base, "defaults/pref/foo.js"))
+            self.assertFalse(is_resource(base, "defaults/foo/bar.dat"))
+            self.assertFalse(is_resource(base, "defaults/foo/bar/baz.dat"))
+            self.assertTrue(is_resource(base, "chrome/foo/bar/baz/dummy_"))
+            self.assertFalse(is_resource(base, "chrome/foo/bar/baz/dummy"))
+            self.assertTrue(is_resource(base, "chrome/foo/bar/dummy_"))
+            self.assertFalse(is_resource(base, "chrome/foo/bar/dummy"))
+
+    def test_chrome_override(self):
+        registry = FileRegistry()
+        f = FlatFormatter(registry)
+        f.add_base("")
+        f.add_manifest(ManifestContent("chrome", "foo", "foo/unix"))
+        # A more specific entry for a given chrome name can override a more
+        # generic one.
+        f.add_manifest(ManifestContent("chrome", "foo", "foo/win", "os=WINNT"))
+        f.add_manifest(ManifestContent("chrome", "foo", "foo/osx", "os=Darwin"))
+
+        # Chrome with the same name overrides the previous registration.
+        with self.assertRaises(ErrorMessage) as e:
+            f.add_manifest(ManifestContent("chrome", "foo", "foo/"))
+
+        self.assertEqual(
+            str(e.exception),
+            'error: "content foo foo/" overrides ' '"content foo foo/unix"',
+        )
+
+        # Chrome with the same name and same flags overrides the previous
+        # registration.
+        with self.assertRaises(ErrorMessage) as e:
+            f.add_manifest(ManifestContent("chrome", "foo", "foo/", "os=WINNT"))
+
+        self.assertEqual(
+            str(e.exception),
+            'error: "content foo foo/ os=WINNT" overrides '
+            '"content foo foo/win os=WINNT"',
+        )
+
+        # We may start with the more specific entry first
+        f.add_manifest(ManifestContent("chrome", "bar", "bar/win", "os=WINNT"))
+        # Then adding a more generic one overrides it.
+        with self.assertRaises(ErrorMessage) as e:
+            f.add_manifest(ManifestContent("chrome", "bar", "bar/unix"))
+
+        self.assertEqual(
+            str(e.exception),
+            'error: "content bar bar/unix" overrides ' '"content bar bar/win os=WINNT"',
+        )
+
+        # Adding something more specific still works.
+        f.add_manifest(
+            ManifestContent("chrome", "bar", "bar/win", "os=WINNT osversion>=7.0")
+        )
+
+        # Variations of skin/locales are allowed.
+        f.add_manifest(
+            ManifestSkin("chrome", "foo", "classic/1.0", "foo/skin/classic/")
+        )
+        f.add_manifest(ManifestSkin("chrome", "foo", "modern/1.0", "foo/skin/modern/"))
+
+        f.add_manifest(ManifestLocale("chrome", "foo", "en-US", "foo/locale/en-US/"))
+        f.add_manifest(ManifestLocale("chrome", "foo", "ja-JP", "foo/locale/ja-JP/"))
+
+        # But same-skin/locale still error out.
+        with self.assertRaises(ErrorMessage) as e:
+            f.add_manifest(
+                ManifestSkin("chrome", "foo", "classic/1.0", "foo/skin/classic/foo")
+            )
+
+        self.assertEqual(
+            str(e.exception),
+            'error: "skin foo classic/1.0 foo/skin/classic/foo" overrides '
+            '"skin foo classic/1.0 foo/skin/classic/"',
+        )
+
+        with self.assertRaises(ErrorMessage) as e:
+            f.add_manifest(
+                ManifestLocale("chrome", "foo", "en-US", "foo/locale/en-US/foo")
+            )
+
+        self.assertEqual(
+            str(e.exception),
+            'error: "locale foo en-US foo/locale/en-US/foo" overrides '
+            '"locale foo en-US foo/locale/en-US/"',
+        )
+
+        # Duplicating existing manifest entries is not an error.
+        f.add_manifest(ManifestContent("chrome", "foo", "foo/unix"))
+
+        self.assertEqual(
+            self.get_output(),
+            [
+                'warning: "content foo foo/unix" is duplicated. Skipping.',
+            ],
+        )
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_packager_l10n.py b/python/mozbuild/mozpack/test/test_packager_l10n.py
new file mode 100644
index 0000000000..0714ae3252
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_packager_l10n.py
@@ -0,0 +1,153 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import unittest
+
+import mozunit
+import six
+
+from mozpack.chrome.manifest import Manifest, ManifestContent, ManifestLocale
+from mozpack.copier import FileRegistry
+from mozpack.files import GeneratedFile, ManifestFile
+from mozpack.packager import l10n
+from test_packager import MockFinder
+
+
+class TestL10NRepack(unittest.TestCase):
+    def test_l10n_repack(self):
+        foo = GeneratedFile(b"foo")
+        foobar = GeneratedFile(b"foobar")
+        qux = GeneratedFile(b"qux")
+        bar = GeneratedFile(b"bar")
+        baz = GeneratedFile(b"baz")
+        dict_aa = GeneratedFile(b"dict_aa")
+        dict_bb = GeneratedFile(b"dict_bb")
+        dict_cc = GeneratedFile(b"dict_cc")
+        barbaz = GeneratedFile(b"barbaz")
+        lst = GeneratedFile(b"foo\nbar")
+        app_finder = MockFinder(
+            {
+                "bar/foo": foo,
+                "chrome/foo/foobar": foobar,
+                "chrome/qux/qux.properties": qux,
+                "chrome/qux/baz/baz.properties": baz,
+                "chrome/chrome.manifest": ManifestFile(
+                    "chrome",
+                    [
+                        ManifestContent("chrome", "foo", "foo/"),
+                        ManifestLocale("chrome", "qux", "en-US", "qux/"),
+                    ],
+                ),
+                "chrome.manifest": ManifestFile(
+                    "", [Manifest("", "chrome/chrome.manifest")]
+                ),
+                "dict/aa": dict_aa,
+                "app/chrome/bar/barbaz.dtd": barbaz,
+                "app/chrome/chrome.manifest": ManifestFile(
+                    "app/chrome", [ManifestLocale("app/chrome", "bar", "en-US", "bar/")]
+                ),
+                "app/chrome.manifest": ManifestFile(
+                    "app", [Manifest("app", "chrome/chrome.manifest")]
+                ),
+                "app/dict/bb": dict_bb,
+                "app/dict/cc": dict_cc,
+                "app/chrome/bar/search/foo.xml": foo,
+                "app/chrome/bar/search/bar.xml": bar,
+                "app/chrome/bar/search/lst.txt": lst,
+                "META-INF/foo": foo,  # Stripped.
+                "inner/META-INF/foo": foo,  # Not stripped.
+                "app/META-INF/foo": foo,  # Stripped.
+                "app/inner/META-INF/foo": foo,  # Not stripped.
+            }
+        )
+        app_finder.jarlogs = {}
+        app_finder.base = "app"
+        foo_l10n = GeneratedFile(b"foo_l10n")
+        qux_l10n = GeneratedFile(b"qux_l10n")
+        baz_l10n = GeneratedFile(b"baz_l10n")
+        barbaz_l10n = GeneratedFile(b"barbaz_l10n")
+        lst_l10n = GeneratedFile(b"foo\nqux")
+        l10n_finder = MockFinder(
+            {
+                "chrome/qux-l10n/qux.properties": qux_l10n,
+                "chrome/qux-l10n/baz/baz.properties": baz_l10n,
+                "chrome/chrome.manifest": ManifestFile(
+                    "chrome",
+                    [
+                        ManifestLocale("chrome", "qux", "x-test", "qux-l10n/"),
+                    ],
+                ),
+                "chrome.manifest": ManifestFile(
+                    "", [Manifest("", "chrome/chrome.manifest")]
+                ),
+                "dict/bb": dict_bb,
+                "dict/cc": dict_cc,
+                "app/chrome/bar-l10n/barbaz.dtd": barbaz_l10n,
+                "app/chrome/chrome.manifest": ManifestFile(
+                    "app/chrome",
+                    [ManifestLocale("app/chrome", "bar", "x-test", "bar-l10n/")],
+                ),
+                "app/chrome.manifest": ManifestFile(
+                    "app", [Manifest("app", "chrome/chrome.manifest")]
+                ),
+                "app/dict/aa": dict_aa,
+                "app/chrome/bar-l10n/search/foo.xml": foo_l10n,
+                "app/chrome/bar-l10n/search/qux.xml": qux_l10n,
+                "app/chrome/bar-l10n/search/lst.txt": lst_l10n,
+            }
+        )
+        l10n_finder.base = "l10n"
+        copier = FileRegistry()
+        formatter = l10n.FlatFormatter(copier)
+
+        l10n._repack(
+            app_finder,
+            l10n_finder,
+            copier,
+            formatter,
+            ["dict", "chrome/**/search/*.xml"],
+        )
+        self.maxDiff = None
+
+        repacked = {
+            "bar/foo": foo,
+            "chrome/foo/foobar": foobar,
+            "chrome/qux-l10n/qux.properties": qux_l10n,
+            "chrome/qux-l10n/baz/baz.properties": baz_l10n,
+            "chrome/chrome.manifest": ManifestFile(
+                "chrome",
+                [
+                    ManifestContent("chrome", "foo", "foo/"),
+                    ManifestLocale("chrome", "qux", "x-test", "qux-l10n/"),
+                ],
+            ),
+            "chrome.manifest": ManifestFile(
+                "", [Manifest("", "chrome/chrome.manifest")]
+            ),
+            "dict/bb": dict_bb,
+            "dict/cc": dict_cc,
+            "app/chrome/bar-l10n/barbaz.dtd": barbaz_l10n,
+            "app/chrome/chrome.manifest": ManifestFile(
+                "app/chrome",
+                [ManifestLocale("app/chrome", "bar", "x-test", "bar-l10n/")],
+            ),
+            "app/chrome.manifest": ManifestFile(
+                "app", [Manifest("app", "chrome/chrome.manifest")]
+            ),
+            "app/dict/aa": dict_aa,
+            "app/chrome/bar-l10n/search/foo.xml": foo_l10n,
+            "app/chrome/bar-l10n/search/qux.xml": qux_l10n,
+            "app/chrome/bar-l10n/search/lst.txt": lst_l10n,
+            "inner/META-INF/foo": foo,
+            "app/inner/META-INF/foo": foo,
+        }
+
+        self.assertEqual(
+            dict((p, f.open().read()) for p, f in copier),
+            dict((p, f.open().read()) for p, f in six.iteritems(repacked)),
+        )
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_packager_unpack.py b/python/mozbuild/mozpack/test/test_packager_unpack.py
new file mode 100644
index 0000000000..57a2d71eda
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_packager_unpack.py
@@ -0,0 +1,67 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import mozunit
+
+from mozpack.copier import FileCopier, FileRegistry
+from mozpack.packager.formats import FlatFormatter, JarFormatter, OmniJarFormatter
+from mozpack.packager.unpack import unpack_to_registry
+from mozpack.test.test_files import TestWithTmpDir
+from mozpack.test.test_packager_formats import CONTENTS, fill_formatter, get_contents
+
+
+class TestUnpack(TestWithTmpDir):
+    maxDiff = None
+
+    @staticmethod
+    def _get_copier(cls):
+        copier = FileCopier()
+        formatter = cls(copier)
+        fill_formatter(formatter, CONTENTS)
+        return copier
+
+    @classmethod
+    def setUpClass(cls):
+        cls.contents = get_contents(
+            cls._get_copier(FlatFormatter), read_all=True, mode="rb"
+        )
+
+    def _unpack_test(self, cls):
+        # Format a package with the given formatter class
+        copier = self._get_copier(cls)
+        copier.copy(self.tmpdir)
+
+        # Unpack that package. Its content is expected to match that of a Flat
+        # formatted package.
+        registry = FileRegistry()
+        unpack_to_registry(self.tmpdir, registry, getattr(cls, "OMNIJAR_NAME", None))
+        self.assertEqual(
+            get_contents(registry, read_all=True, mode="rb"), self.contents
+        )
+
+    def test_flat_unpack(self):
+        self._unpack_test(FlatFormatter)
+
+    def test_jar_unpack(self):
+        self._unpack_test(JarFormatter)
+
+    @staticmethod
+    def _omni_foo_formatter(name):
+        class OmniFooFormatter(OmniJarFormatter):
+            OMNIJAR_NAME = name
+
+            def __init__(self, registry):
+                super(OmniFooFormatter, self).__init__(registry, name)
+
+        return OmniFooFormatter
+
+    def test_omnijar_unpack(self):
+        self._unpack_test(self._omni_foo_formatter("omni.foo"))
+
+    def test_omnijar_subpath_unpack(self):
+        self._unpack_test(self._omni_foo_formatter("bar/omni.foo"))
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_path.py b/python/mozbuild/mozpack/test/test_path.py
new file mode 100644
index 0000000000..6c7aeb5400
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_path.py
@@ -0,0 +1,152 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import unittest
+
+import mozunit
+
+from mozpack.path import (
+    basedir,
+    basename,
+    commonprefix,
+    dirname,
+    join,
+    match,
+    normpath,
+    rebase,
+    relpath,
+    split,
+    splitext,
+)
+
+
+class TestPath(unittest.TestCase):
+    SEP = os.sep
+
+    def test_relpath(self):
+        self.assertEqual(relpath("foo", "foo"), "")
+        self.assertEqual(relpath(self.SEP.join(("foo", "bar")), "foo/bar"), "")
+        self.assertEqual(relpath(self.SEP.join(("foo", "bar")), "foo"), "bar")
+        self.assertEqual(
+            relpath(self.SEP.join(("foo", "bar", "baz")), "foo"), "bar/baz"
+        )
+        self.assertEqual(relpath(self.SEP.join(("foo", "bar")), "foo/bar/baz"), "..")
+        self.assertEqual(relpath(self.SEP.join(("foo", "bar")), "foo/baz"), "../bar")
+        self.assertEqual(relpath("foo/", "foo"), "")
+        self.assertEqual(relpath("foo/bar/", "foo"), "bar")
+
+    def test_join(self):
+        self.assertEqual(join("foo", "bar", "baz"), "foo/bar/baz")
+        self.assertEqual(join("foo", "", "bar"), "foo/bar")
+        self.assertEqual(join("", "foo", "bar"), "foo/bar")
+        self.assertEqual(join("", "foo", "/bar"), "/bar")
+
+    def test_normpath(self):
+        self.assertEqual(
+            normpath(self.SEP.join(("foo", "bar", "baz", "..", "qux"))), "foo/bar/qux"
+        )
+
+    def test_dirname(self):
+        self.assertEqual(dirname("foo/bar/baz"), "foo/bar")
+        self.assertEqual(dirname("foo/bar"), "foo")
+        self.assertEqual(dirname("foo"), "")
+        self.assertEqual(dirname("foo/bar/"), "foo/bar")
+
+    def test_commonprefix(self):
+        self.assertEqual(
+            commonprefix(
+                [self.SEP.join(("foo", "bar", "baz")), "foo/qux", "foo/baz/qux"]
+            ),
+            "foo/",
+        )
+        self.assertEqual(
+            commonprefix([self.SEP.join(("foo", "bar", "baz")), "foo/qux", "baz/qux"]),
+            "",
+        )
+
+    def test_basename(self):
+        self.assertEqual(basename("foo/bar/baz"), "baz")
+        self.assertEqual(basename("foo/bar"), "bar")
+        self.assertEqual(basename("foo"), "foo")
+        self.assertEqual(basename("foo/bar/"), "")
+
+    def test_split(self):
+        self.assertEqual(
+            split(self.SEP.join(("foo", "bar", "baz"))), ["foo", "bar", "baz"]
+        )
+
+    def test_splitext(self):
+        self.assertEqual(
+            splitext(self.SEP.join(("foo", "bar", "baz.qux"))), ("foo/bar/baz", ".qux")
+        )
+
+    def test_basedir(self):
+        foobarbaz = self.SEP.join(("foo", "bar", "baz"))
+        self.assertEqual(basedir(foobarbaz, ["foo", "bar", "baz"]), "foo")
+        self.assertEqual(basedir(foobarbaz, ["foo", "foo/bar", "baz"]), "foo/bar")
+        self.assertEqual(basedir(foobarbaz, ["foo/bar", "foo", "baz"]), "foo/bar")
+        self.assertEqual(basedir(foobarbaz, ["foo", "bar", ""]), "foo")
+        self.assertEqual(basedir(foobarbaz, ["bar", "baz", ""]), "")
+
+    def test_match(self):
+        self.assertTrue(match("foo", ""))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/bar"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo"))
+        self.assertTrue(match("foo", "*"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/bar/*"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/bar/*"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/bar/*"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/bar/*"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/*/baz.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "*/bar/baz.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "*/*/baz.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "*/*/*"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/*/*"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/*/*.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/b*/*z.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/b*r/ba*z.qux"))
+        self.assertFalse(match("foo/bar/baz.qux", "foo/b*z/ba*r.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "**"))
+        self.assertTrue(match("foo/bar/baz.qux", "**/baz.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "**/bar/baz.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/**/baz.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/**/*.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "**/foo/bar/baz.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/**/bar/baz.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/**/bar/*.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/**/*.qux"))
+        self.assertTrue(match("foo/bar/baz.qux", "**/*.qux"))
+        self.assertFalse(match("foo/bar/baz.qux", "**.qux"))
+        self.assertFalse(match("foo/bar", "foo/*/bar"))
+        self.assertTrue(match("foo/bar/baz.qux", "foo/**/bar/**"))
+        self.assertFalse(match("foo/nobar/baz.qux", "foo/**/bar/**"))
+        self.assertTrue(match("foo/bar", "foo/**/bar/**"))
+
+    def test_rebase(self):
+        self.assertEqual(rebase("foo", "foo/bar", "bar/baz"), "baz")
+        self.assertEqual(rebase("foo", "foo", "bar/baz"), "bar/baz")
+        self.assertEqual(rebase("foo/bar", "foo", "baz"), "bar/baz")
+
+
+if os.altsep:
+
+    class TestAltPath(TestPath):
+        SEP = os.altsep
+
+    class TestReverseAltPath(TestPath):
+        def setUp(self):
+            sep = os.sep
+            os.sep = os.altsep
+            os.altsep = sep
+
+        def tearDown(self):
+            self.setUp()
+
+    class TestAltReverseAltPath(TestReverseAltPath):
+        SEP = os.altsep
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_pkg.py b/python/mozbuild/mozpack/test/test_pkg.py
new file mode 100644
index 0000000000..f1febbbae0
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_pkg.py
@@ -0,0 +1,138 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from pathlib import Path
+from string import Template
+from unittest.mock import patch
+
+import mozunit
+
+import mozpack.pkg
+from mozpack.pkg import (
+    create_bom,
+    create_payload,
+    create_pkg,
+    get_app_info_plist,
+    get_apple_template,
+    get_relative_glob_list,
+    save_text_file,
+    xar_package_folder,
+)
+from mozpack.test.test_files import TestWithTmpDir
+
+
+class TestPkg(TestWithTmpDir):
+    maxDiff = None
+
+    class MockSubprocessRun:
+        stderr = ""
+        stdout = ""
+        returncode = 0
+
+        def __init__(self, returncode=0):
+            self.returncode = returncode
+
+    def _mk_test_file(self, name, mode=0o777):
+        tool = Path(self.tmpdir) / f"{name}"
+        tool.touch()
+        tool.chmod(mode)
+        return tool
+
+    def test_get_apple_template(self):
+        tmpl = get_apple_template("Distribution.template")
+        assert type(tmpl) == Template
+
+    def test_get_apple_template_not_file(self):
+        with self.assertRaises(Exception):
+            get_apple_template("tmpl-should-not-exist")
+
+    def test_save_text_file(self):
+        content = "Hello"
+        destination = Path(self.tmpdir) / "test_save_text_file"
+        save_text_file(content, destination)
+        with destination.open("r") as file:
+            assert content == file.read()
+
+    def test_get_app_info_plist(self):
+        app_path = Path(self.tmpdir) / "app"
+        (app_path / "Contents").mkdir(parents=True)
+        (app_path / "Contents/Info.plist").touch()
+        data = {"foo": "bar"}
+        with patch.object(mozpack.pkg.plistlib, "load", lambda x: data):
+            assert data == get_app_info_plist(app_path)
+
+    def test_get_app_info_plist_not_file(self):
+        app_path = Path(self.tmpdir) / "app-does-not-exist"
+        with self.assertRaises(Exception):
+            get_app_info_plist(app_path)
+
+    def _mock_payload(self, returncode):
+        def _mock_run(*args, **kwargs):
+            return self.MockSubprocessRun(returncode)
+
+        return _mock_run
+
+    def test_create_payload(self):
+        destination = Path(self.tmpdir) / "mockPayload"
+        with patch.object(mozpack.pkg.subprocess, "run", self._mock_payload(0)):
+            create_payload(destination, Path(self.tmpdir), "cpio")
+
+    def test_create_bom(self):
+        bom_path = Path(self.tmpdir) / "Bom"
+        bom_path.touch()
+        root_path = Path(self.tmpdir)
+        tool_path = Path(self.tmpdir) / "not-really-used-during-test"
+        with patch.object(mozpack.pkg.subprocess, "check_call", lambda *x: None):
+            create_bom(bom_path, root_path, tool_path)
+
+    def get_relative_glob_list(self):
+        source = Path(self.tmpdir)
+        (source / "testfile").touch()
+        glob = "*"
+        assert len(get_relative_glob_list(source, glob)) == 1
+
+    def test_xar_package_folder(self):
+        source = Path(self.tmpdir)
+        dest = source / "fakedestination"
+        dest.touch()
+        tool = source / "faketool"
+        with patch.object(mozpack.pkg.subprocess, "check_call", lambda *x, **y: None):
+            xar_package_folder(source, dest, tool)
+
+    def test_xar_package_folder_not_absolute(self):
+        source = Path("./some/relative/path")
+        dest = Path("./some/other/relative/path")
+        tool = source / "faketool"
+        with patch.object(mozpack.pkg.subprocess, "check_call", lambda: None):
+            with self.assertRaises(Exception):
+                xar_package_folder(source, dest, tool)
+
+    def test_create_pkg(self):
+        def noop(*x, **y):
+            pass
+
+        def mock_get_app_info_plist(*args):
+            return {"CFBundleShortVersionString": "1.0.0"}
+
+        def mock_get_apple_template(*args):
+            return Template("fake template")
+
+        source = Path(self.tmpdir) / "FakeApp.app"
+        source.mkdir()
+        output = Path(self.tmpdir) / "output.pkg"
+        fake_tool = Path(self.tmpdir) / "faketool"
+        with patch.multiple(
+            mozpack.pkg,
+            get_app_info_plist=mock_get_app_info_plist,
+            get_apple_template=mock_get_apple_template,
+            save_text_file=noop,
+            create_payload=noop,
+            create_bom=noop,
+            xar_package_folder=noop,
+        ):
+            create_pkg(source, output, fake_tool, fake_tool, fake_tool)
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/test/test_unify.py b/python/mozbuild/mozpack/test/test_unify.py
new file mode 100644
index 0000000000..15de50dccc
--- /dev/null
+++ b/python/mozbuild/mozpack/test/test_unify.py
@@ -0,0 +1,250 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import sys
+from io import StringIO
+
+import mozunit
+
+from mozbuild.util import ensureParentDir
+from mozpack.errors import AccumulatedErrors, ErrorMessage, errors
+from mozpack.files import FileFinder
+from mozpack.mozjar import JarWriter
+from mozpack.test.test_files import MockDest, TestWithTmpDir
+from mozpack.unify import UnifiedBuildFinder, UnifiedFinder
+
+
+class TestUnified(TestWithTmpDir):
+    def create_one(self, which, path, content):
+        file = self.tmppath(os.path.join(which, path))
+        ensureParentDir(file)
+        if isinstance(content, str):
+            content = content.encode("utf-8")
+        open(file, "wb").write(content)
+
+    def create_both(self, path, content):
+        for p in ["a", "b"]:
+            self.create_one(p, path, content)
+
+
+class TestUnifiedFinder(TestUnified):
+    def test_unified_finder(self):
+        self.create_both("foo/bar", "foobar")
+        self.create_both("foo/baz", "foobaz")
+        self.create_one("a", "bar", "bar")
+        self.create_one("b", "baz", "baz")
+        self.create_one("a", "qux", "foobar")
+        self.create_one("b", "qux", "baz")
+        self.create_one("a", "test/foo", "a\nb\nc\n")
+        self.create_one("b", "test/foo", "b\nc\na\n")
+        self.create_both("test/bar", "a\nb\nc\n")
+
+        finder = UnifiedFinder(
+            FileFinder(self.tmppath("a")),
+            FileFinder(self.tmppath("b")),
+            sorted=["test"],
+        )
+        self.assertEqual(
+            sorted(
+                [(f, c.open().read().decode("utf-8")) for f, c in finder.find("foo")]
+            ),
+            [("foo/bar", "foobar"), ("foo/baz", "foobaz")],
+        )
+        self.assertRaises(ErrorMessage, any, finder.find("bar"))
+        self.assertRaises(ErrorMessage, any, finder.find("baz"))
+        self.assertRaises(ErrorMessage, any, finder.find("qux"))
+        self.assertEqual(
+            sorted(
+                [(f, c.open().read().decode("utf-8")) for f, c in finder.find("test")]
+            ),
+            [("test/bar", "a\nb\nc\n"), ("test/foo", "a\nb\nc\n")],
+        )
+
+
+class TestUnifiedBuildFinder(TestUnified):
+    def test_unified_build_finder(self):
+        finder = UnifiedBuildFinder(
+            FileFinder(self.tmppath("a")), FileFinder(self.tmppath("b"))
+        )
+
+        # Test chrome.manifest unification
+        self.create_both("chrome.manifest", "a\nb\nc\n")
+        self.create_one("a", "chrome/chrome.manifest", "a\nb\nc\n")
+        self.create_one("b", "chrome/chrome.manifest", "b\nc\na\n")
+        self.assertEqual(
+            sorted(
+                [
+                    (f, c.open().read().decode("utf-8"))
+                    for f, c in finder.find("**/chrome.manifest")
+                ]
+            ),
+            [("chrome.manifest", "a\nb\nc\n"), ("chrome/chrome.manifest", "a\nb\nc\n")],
+        )
+
+        # Test buildconfig.html unification
+        self.create_one(
+            "a",
+            "chrome/browser/foo/buildconfig.html",
+            "\n".join(
+                [
+                    "<html>",
+                    "  <body>",
+                    "    <div>",
+                    "      <h1>Build Configuration</h1>",
+                    "      <div>foo</div>",
+                    "    </div>",
+                    "  </body>",
+                    "</html>",
+                ]
+            ),
+        )
+        self.create_one(
+            "b",
+            "chrome/browser/foo/buildconfig.html",
+            "\n".join(
+                [
+                    "<html>",
+                    "  <body>",
+                    "    <div>",
+                    "      <h1>Build Configuration</h1>",
+                    "      <div>bar</div>",
+                    "    </div>",
+                    "  </body>",
+                    "</html>",
+                ]
+            ),
+        )
+        self.assertEqual(
+            sorted(
+                [
+                    (f, c.open().read().decode("utf-8"))
+                    for f, c in finder.find("**/buildconfig.html")
+                ]
+            ),
+            [
+                (
+                    "chrome/browser/foo/buildconfig.html",
+                    "\n".join(
+                        [
+                            "<html>",
+                            "  <body>",
+                            "    <div>",
+                            "      <h1>Build Configuration</h1>",
+                            "      <div>foo</div>",
+                            "      <hr> </hr>",
+                            "      <div>bar</div>",
+                            "    </div>",
+                            "  </body>",
+                            "</html>",
+                        ]
+                    ),
+                )
+            ],
+        )
+
+        # Test xpi file unification
+        xpi = MockDest()
+        with JarWriter(fileobj=xpi, compress=True) as jar:
+            jar.add("foo", "foo")
+            jar.add("bar", "bar")
+        foo_xpi = xpi.read()
+        self.create_both("foo.xpi", foo_xpi)
+
+        with JarWriter(fileobj=xpi, compress=True) as jar:
+            jar.add("foo", "bar")
+        self.create_one("a", "bar.xpi", foo_xpi)
+        self.create_one("b", "bar.xpi", xpi.read())
+
+        errors.out = StringIO()
+        with self.assertRaises(AccumulatedErrors), errors.accumulate():
+            self.assertEqual(
+                [(f, c.open().read()) for f, c in finder.find("*.xpi")],
+                [("foo.xpi", foo_xpi)],
+            )
+        errors.out = sys.stderr
+
+        # Test install.rdf unification
+        x86_64 = "Darwin_x86_64-gcc3"
+        x86 = "Darwin_x86-gcc3"
+        target_tag = "<{em}targetPlatform>{platform}</{em}targetPlatform>"
+        target_attr = '{em}targetPlatform="{platform}" '
+
+        rdf_tag = "".join(
+            [
+                '<{RDF}Description {em}bar="bar" {em}qux="qux">',
+                "<{em}foo>foo</{em}foo>",
+                "{targets}",
+                "<{em}baz>baz</{em}baz>",
+                "</{RDF}Description>",
+            ]
+        )
+        rdf_attr = "".join(
+            [
+                '<{RDF}Description {em}bar="bar" {attr}{em}qux="qux">',
+                "{targets}",
+                "<{em}foo>foo</{em}foo><{em}baz>baz</{em}baz>",
+                "</{RDF}Description>",
+            ]
+        )
+
+        for descr_ns, target_ns in (("RDF:", ""), ("", "em:"), ("RDF:", "em:")):
+            # First we need to infuse the above strings with our namespaces and
+            # platform values.
+            ns = {"RDF": descr_ns, "em": target_ns}
+            target_tag_x86_64 = target_tag.format(platform=x86_64, **ns)
+            target_tag_x86 = target_tag.format(platform=x86, **ns)
+            target_attr_x86_64 = target_attr.format(platform=x86_64, **ns)
+            target_attr_x86 = target_attr.format(platform=x86, **ns)
+
+            tag_x86_64 = rdf_tag.format(targets=target_tag_x86_64, **ns)
+            tag_x86 = rdf_tag.format(targets=target_tag_x86, **ns)
+            tag_merged = rdf_tag.format(
+                targets=target_tag_x86_64 + target_tag_x86, **ns
+            )
+            tag_empty = rdf_tag.format(targets="", **ns)
+
+            attr_x86_64 = rdf_attr.format(attr=target_attr_x86_64, targets="", **ns)
+            attr_x86 = rdf_attr.format(attr=target_attr_x86, targets="", **ns)
+            attr_merged = rdf_attr.format(
+                attr="", targets=target_tag_x86_64 + target_tag_x86, **ns
+            )
+
+            # This table defines the test cases, columns "a" and "b" being the
+            # contents of the install.rdf of the respective platform and
+            # "result" the exepected merged content after unification.
+            testcases = (
+                # _____a_____  _____b_____  ___result___#
+                (tag_x86_64, tag_x86, tag_merged),
+                (tag_x86_64, tag_empty, tag_empty),
+                (tag_empty, tag_x86, tag_empty),
+                (tag_empty, tag_empty, tag_empty),
+                (attr_x86_64, attr_x86, attr_merged),
+                (tag_x86_64, attr_x86, tag_merged),
+                (attr_x86_64, tag_x86, attr_merged),
+                (attr_x86_64, tag_empty, tag_empty),
+                (tag_empty, attr_x86, tag_empty),
+            )
+
+            # Now create the files from the above table and compare
+            results = []
+            for emid, (rdf_a, rdf_b, result) in enumerate(testcases):
+                filename = "ext/id{0}/install.rdf".format(emid)
+                self.create_one("a", filename, rdf_a)
+                self.create_one("b", filename, rdf_b)
+                results.append((filename, result))
+
+            self.assertEqual(
+                sorted(
+                    [
+                        (f, c.open().read().decode("utf-8"))
+                        for f, c in finder.find("**/install.rdf")
+                    ]
+                ),
+                results,
+            )
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozbuild/mozpack/unify.py b/python/mozbuild/mozpack/unify.py
new file mode 100644
index 0000000000..ca4d0017a9
--- /dev/null
+++ b/python/mozbuild/mozpack/unify.py
@@ -0,0 +1,265 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import re
+import struct
+import subprocess
+from collections import OrderedDict
+from tempfile import mkstemp
+
+import buildconfig
+
+import mozpack.path as mozpath
+from mozbuild.util import hexdump
+from mozpack.errors import errors
+from mozpack.executables import MACHO_SIGNATURES
+from mozpack.files import BaseFile, BaseFinder, ExecutableFile, GeneratedFile
+
+# Regular expressions for unifying install.rdf
+FIND_TARGET_PLATFORM = re.compile(
+    r"""
+    <(?P<ns>[-._0-9A-Za-z]+:)?targetPlatform>  # The targetPlatform tag, with any namespace
+    (?P<platform>[^<]*)                        # The actual platform value
+    </(?P=ns)?targetPlatform>                  # The closing tag
+    """,
+    re.X,
+)
+FIND_TARGET_PLATFORM_ATTR = re.compile(
+    r"""
+    (?P<tag><(?:[-._0-9A-Za-z]+:)?Description) # The opening part of the <Description> tag
+    (?P<attrs>[^>]*?)\s+                       # The initial attributes
+    (?P<ns>[-._0-9A-Za-z]+:)?targetPlatform=   # The targetPlatform attribute, with any namespace
+    [\'"](?P<platform>[^\'"]+)[\'"]            # The actual platform value
+    (?P<otherattrs>[^>]*?>)                    # The remaining attributes and closing angle bracket
+    """,
+    re.X,
+)
+
+
+def may_unify_binary(file):
+    """
+    Return whether the given BaseFile instance is an ExecutableFile that
+    may be unified. Only non-fat Mach-O binaries are to be unified.
+    """
+    if isinstance(file, ExecutableFile):
+        signature = file.open().read(4)
+        if len(signature) < 4:
+            return False
+        signature = struct.unpack(">L", signature)[0]
+        if signature in MACHO_SIGNATURES:
+            return True
+    return False
+
+
+class UnifiedExecutableFile(BaseFile):
+    """
+    File class for executable and library files that to be unified with 'lipo'.
+    """
+
+    def __init__(self, executable1, executable2):
+        """
+        Initialize a UnifiedExecutableFile with a pair of ExecutableFiles to
+        be unified. They are expected to be non-fat Mach-O executables.
+        """
+        assert isinstance(executable1, ExecutableFile)
+        assert isinstance(executable2, ExecutableFile)
+        self._executables = (executable1, executable2)
+
+    def copy(self, dest, skip_if_older=True):
+        """
+        Create a fat executable from the two Mach-O executable given when
+        creating the instance.
+        skip_if_older is ignored.
+        """
+        assert isinstance(dest, str)
+        tmpfiles = []
+        try:
+            for e in self._executables:
+                fd, f = mkstemp()
+                os.close(fd)
+                tmpfiles.append(f)
+                e.copy(f, skip_if_older=False)
+            lipo = buildconfig.substs.get("LIPO") or "lipo"
+            subprocess.check_call([lipo, "-create"] + tmpfiles + ["-output", dest])
+        except Exception as e:
+            errors.error(
+                "Failed to unify %s and %s: %s"
+                % (self._executables[0].path, self._executables[1].path, str(e))
+            )
+        finally:
+            for f in tmpfiles:
+                os.unlink(f)
+
+
+class UnifiedFinder(BaseFinder):
+    """
+    Helper to get unified BaseFile instances from two distinct trees on the
+    file system.
+    """
+
+    def __init__(self, finder1, finder2, sorted=[], **kargs):
+        """
+        Initialize a UnifiedFinder. finder1 and finder2 are BaseFinder
+        instances from which files are picked. UnifiedFinder.find() will act as
+        FileFinder.find() but will error out when matches can only be found in
+        one of the two trees and not the other. It will also error out if
+        matches can be found on both ends but their contents are not identical.
+
+        The sorted argument gives a list of mozpath.match patterns. File
+        paths matching one of these patterns will have their contents compared
+        with their lines sorted.
+        """
+        assert isinstance(finder1, BaseFinder)
+        assert isinstance(finder2, BaseFinder)
+        self._finder1 = finder1
+        self._finder2 = finder2
+        self._sorted = sorted
+        BaseFinder.__init__(self, finder1.base, **kargs)
+
+    def _find(self, path):
+        """
+        UnifiedFinder.find() implementation.
+        """
+        # There is no `OrderedSet`.  Operator `|` was added only in
+        # Python 3.9, so we merge by hand.
+        all_paths = OrderedDict()
+
+        files1 = OrderedDict()
+        for p, f in self._finder1.find(path):
+            files1[p] = f
+            all_paths[p] = True
+        files2 = OrderedDict()
+        for p, f in self._finder2.find(path):
+            files2[p] = f
+            all_paths[p] = True
+
+        for p in all_paths:
+            err = errors.count
+            unified = self.unify_file(p, files1.get(p), files2.get(p))
+            if unified:
+                yield p, unified
+            elif err == errors.count:  # No errors have already been reported.
+                self._report_difference(p, files1.get(p), files2.get(p))
+
+    def _report_difference(self, path, file1, file2):
+        """
+        Report differences between files in both trees.
+        """
+        if not file1:
+            errors.error("File missing in %s: %s" % (self._finder1.base, path))
+            return
+        if not file2:
+            errors.error("File missing in %s: %s" % (self._finder2.base, path))
+            return
+
+        errors.error(
+            "Can't unify %s: file differs between %s and %s"
+            % (path, self._finder1.base, self._finder2.base)
+        )
+        if not isinstance(file1, ExecutableFile) and not isinstance(
+            file2, ExecutableFile
+        ):
+            from difflib import unified_diff
+
+            try:
+                lines1 = [l.decode("utf-8") for l in file1.open().readlines()]
+                lines2 = [l.decode("utf-8") for l in file2.open().readlines()]
+            except UnicodeDecodeError:
+                lines1 = hexdump(file1.open().read())
+                lines2 = hexdump(file2.open().read())
+
+            for line in unified_diff(
+                lines1,
+                lines2,
+                os.path.join(self._finder1.base, path),
+                os.path.join(self._finder2.base, path),
+            ):
+                errors.out.write(line)
+
+    def unify_file(self, path, file1, file2):
+        """
+        Given two BaseFiles and the path they were found at, return a
+        unified version of the files. If the files match, the first BaseFile
+        may be returned.
+        If the files don't match or one of them is `None`, the method returns
+        `None`.
+        Subclasses may decide to unify by using one of the files in that case.
+        """
+        if not file1 or not file2:
+            return None
+
+        if may_unify_binary(file1) and may_unify_binary(file2):
+            return UnifiedExecutableFile(file1, file2)
+
+        content1 = file1.open().readlines()
+        content2 = file2.open().readlines()
+        if content1 == content2:
+            return file1
+        for pattern in self._sorted:
+            if mozpath.match(path, pattern):
+                if sorted(content1) == sorted(content2):
+                    return file1
+                break
+        return None
+
+
+class UnifiedBuildFinder(UnifiedFinder):
+    """
+    Specialized UnifiedFinder for Mozilla applications packaging. It allows
+    ``*.manifest`` files to differ in their order, and unifies ``buildconfig.html``
+    files by merging their content.
+    """
+
+    def __init__(self, finder1, finder2, **kargs):
+        UnifiedFinder.__init__(
+            self, finder1, finder2, sorted=["**/*.manifest"], **kargs
+        )
+
+    def unify_file(self, path, file1, file2):
+        """
+        Unify files taking Mozilla application special cases into account.
+        Otherwise defer to UnifiedFinder.unify_file.
+        """
+        basename = mozpath.basename(path)
+        if file1 and file2 and basename == "buildconfig.html":
+            content1 = file1.open().readlines()
+            content2 = file2.open().readlines()
+            # Copy everything from the first file up to the end of its <div>,
+            # insert a <hr> between the two files and copy the second file's
+            # content beginning after its leading <h1>.
+            return GeneratedFile(
+                b"".join(
+                    content1[: content1.index(b"    </div>\n")]
+                    + [b"      <hr> </hr>\n"]
+                    + content2[
+                        content2.index(b"      <h1>Build Configuration</h1>\n") + 1 :
+                    ]
+                )
+            )
+        elif file1 and file2 and basename == "install.rdf":
+            # install.rdf files often have em:targetPlatform (either as
+            # attribute or as tag) that will differ between platforms. The
+            # unified install.rdf should contain both em:targetPlatforms if
+            # they exist, or strip them if only one file has a target platform.
+            content1, content2 = (
+                FIND_TARGET_PLATFORM_ATTR.sub(
+                    lambda m: m.group("tag")
+                    + m.group("attrs")
+                    + m.group("otherattrs")
+                    + "<%stargetPlatform>%s</%stargetPlatform>"
+                    % (m.group("ns") or "", m.group("platform"), m.group("ns") or ""),
+                    f.open().read().decode("utf-8"),
+                )
+                for f in (file1, file2)
+            )
+
+            platform2 = FIND_TARGET_PLATFORM.search(content2)
+            return GeneratedFile(
+                FIND_TARGET_PLATFORM.sub(
+                    lambda m: m.group(0) + platform2.group(0) if platform2 else "",
+                    content1,
+                )
+            )
+        return UnifiedFinder.unify_file(self, path, file1, file2)