1 files changed, 141 insertions, 0 deletions
diff --git a/python/mozbuild/mozpack/executables.py b/python/mozbuild/mozpack/executables.py
new file mode 100644
index 0000000000..96bcd40fae
--- /dev/null
+++ b/python/mozbuild/mozpack/executables.py
@@ -0,0 +1,141 @@
+# 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
+
+    # Bug 1658632: clang-11-based strip complains about d3dcompiler_47.dll.
+    # It's not clear why this happens, but as a quick fix just avoid stripping
+    # this DLL. It's not from our build anyway.
+    if "d3dcompiler" in path:
+        return False
+    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))