Adding upstream version 115.7.0esr.upstream/115.7.0esr

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

1 files changed, 1005 insertions, 0 deletions

diff --git a/taskcluster/scripts/run-task b/taskcluster/scripts/run-task
new file mode 100755
index 0000000000..fb0d32f8f5
--- /dev/null
+++ b/taskcluster/scripts/run-task
@@ -0,0 +1,1005 @@
+#!/usr/bin/python3 -u
+# 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/.
+
+"""Run a task after performing common actions.
+
+This script is meant to be the "driver" for TaskCluster based tasks.
+It receives some common arguments to control the run-time environment.
+
+It performs actions as requested from the arguments. Then it executes
+the requested process and prints its output, prefixing it with the
+current time to improve log usefulness.
+"""
+
+import sys
+
+
+if sys.version_info[0:2] < (3, 5):
+    print('run-task requires Python 3.5+')
+    sys.exit(1)
+
+
+import argparse
+import datetime
+import errno
+import io
+import json
+import os
+import random
+import re
+import shutil
+import signal
+import socket
+import stat
+import subprocess
+
+import urllib.error
+import urllib.request
+
+from threading import Thread
+
+FINGERPRINT_URL = 'http://taskcluster/secrets/v1/secret/project/taskcluster/gecko/hgfingerprint'
+FALLBACK_FINGERPRINT = {
+    'fingerprints':
+        "sha256:4D:EB:21:6E:35:2F:99:C6:8F:C3:47:9B:57:B8:6C:17:15:8F:86:09:D4:6C:17:1D:87:B0:DE:F9:0E:51:70:FC,"
+        "sha256:90:85:39:A8:4F:47:20:58:98:0D:48:4D:8A:AC:71:DB:5C:AF:76:44:F1:B1:3E:56:92:FF:21:8C:C9:A9:F7:11"
+}
+
+HGMOINTERNAL_CONFIG_URL = 'http://taskcluster/secrets/v1/secret/project/taskcluster/gecko/hgmointernal'
+
+CACHE_UID_GID_MISMATCH = '''
+There is a UID/GID mismatch on the cache. This likely means:
+
+a) different tasks are running as a different user/group
+b) different Docker images have different UID/GID for the same user/group
+
+Our cache policy is that the UID/GID for ALL tasks must be consistent
+for the lifetime of the cache. This eliminates permissions problems due
+to file/directory user/group ownership.
+
+To make this error go away, ensure that all Docker images are use
+a consistent UID/GID and that all tasks using this cache are running as
+the same user/group.
+'''
+
+
+NON_EMPTY_VOLUME = '''
+error: volume %s is not empty
+
+Our Docker image policy requires volumes to be empty.
+
+The volume was likely populated as part of building the Docker image.
+Change the Dockerfile and anything run from it to not create files in
+any VOLUME.
+
+A lesser possibility is that you stumbled upon a TaskCluster platform bug
+where it fails to use new volumes for tasks.
+'''
+
+
+FETCH_CONTENT_NOT_FOUND = '''
+error: fetch-content script not found
+
+The script at `taskcluster/scripts/misc/fetch-content` could not be
+detected in the current environment.
+
+If this task clones gecko, make sure the GECKO_PATH environment variable
+is set to proper location. Otherwise, the script may need to be mounted
+or added to the task's docker image then added to the PATH.
+'''
+
+# The exit code to use when caches should be purged and the task retried.
+# This is EX_OSFILE (from sysexits.h):
+#     Some system file  does not exist, cannot be opened, or has some
+#     sort of error (e.g., syntax error).
+EXIT_PURGE_CACHE = 72
+
+
+IS_MACOSX = sys.platform == 'darwin'
+IS_POSIX = os.name == 'posix'
+IS_WINDOWS = os.name == 'nt'
+
+
+def print_line(prefix, m):
+    now = datetime.datetime.utcnow().isoformat().encode('utf-8')
+    # slice microseconds to 3 decimals.
+    now = now[:-3] if now[-7:-6] == b'.' else now
+    bytes = b'[%s %sZ] %s' % (prefix, now, m)
+    written = 0
+    while written < len(bytes):
+        written += (sys.stdout.buffer.write(bytes[written:]) or 0)
+    sys.stdout.buffer.flush()
+
+
+def run_and_prefix_output(prefix, args, *, extra_env=None, cwd=None):
+    """Runs a process and prefixes its output with the time.
+
+    Returns the process exit code.
+    """
+    print_line(
+        prefix,
+        b"executing %r%s\n" % (args, b"in %s" % (cwd.encode("utf-8"),) if cwd else b""),
+    )
+
+    env = dict(os.environ)
+    env.update(extra_env or {})
+
+    # Note: TaskCluster's stdin is a TTY. This attribute is lost
+    # when we pass sys.stdin to the invoked process. If we cared
+    # to preserve stdin as a TTY, we could make this work. But until
+    # someone needs it, don't bother.
+
+    # We want stdout to be bytes on Python 3. That means we can't use
+    # universal_newlines=True (because it implies text mode). But
+    # p.stdout.readline() won't work for bytes text streams. So, on Python 3,
+    # we manually install a latin1 stream wrapper. This allows us to readline()
+    # and preserves bytes, without losing any data.
+
+    p = subprocess.Popen(args,
+                         # Disable buffering because we want to receive output
+                         # as it is generated so timestamps in logs are
+                         # accurate.
+                         bufsize=0,
+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.STDOUT,
+                         stdin=sys.stdin.fileno(),
+                         env=env,
+                         cwd=cwd)
+
+    stdout = io.TextIOWrapper(p.stdout, encoding='latin1')
+
+    while True:
+        data = stdout.readline().encode('latin1')
+
+        if data == b'':
+            break
+
+        print_line(prefix, data)
+
+    return p.wait()
+
+
+def get_posix_user_group(user, group):
+    import grp
+    import pwd
+
+    try:
+        user_record = pwd.getpwnam(user)
+    except KeyError:
+        print('could not find user %s; specify a valid user with --user' % user)
+        sys.exit(1)
+
+    try:
+        group_record = grp.getgrnam(group)
+    except KeyError:
+        print('could not find group %s; specify a valid group with --group' %
+              group)
+        sys.exit(1)
+
+    # Most tasks use worker:worker. We require they have a specific numeric ID
+    # because otherwise it is too easy for files written to caches to have
+    # mismatched numeric IDs, which results in permissions errors.
+    if user_record.pw_name == 'worker' and user_record.pw_uid != 1000:
+        print('user `worker` must have uid=1000; got %d' % user_record.pw_uid)
+        sys.exit(1)
+
+    if group_record.gr_name == 'worker' and group_record.gr_gid != 1000:
+        print('group `worker` must have gid=1000; got %d' % group_record.gr_gid)
+        sys.exit(1)
+
+    # Find all groups to which this user is a member.
+    gids = [g.gr_gid for g in grp.getgrall() if group in g.gr_mem]
+
+    return user_record, group_record, gids
+
+
+def write_audit_entry(path, msg):
+    now = datetime.datetime.utcnow().isoformat().encode('utf-8')
+    with open(path, 'ab') as fh:
+        fh.write(b'[%sZ %s] %s\n' % (
+                 now, os.environb.get(b'TASK_ID', b'UNKNOWN'), msg))
+
+
+WANTED_DIR_MODE = stat.S_IXUSR | stat.S_IRUSR | stat.S_IWUSR
+
+
+def set_dir_permissions(path, uid, gid):
+    st = os.lstat(path)
+
+    if st.st_uid != uid or st.st_gid != gid:
+        os.chown(path, uid, gid)
+
+    # Also make sure dirs are writable in case we need to delete
+    # them.
+    if st.st_mode & WANTED_DIR_MODE != WANTED_DIR_MODE:
+        os.chmod(path, st.st_mode | WANTED_DIR_MODE)
+
+
+def chown_recursive(path, user, group, uid, gid):
+    print_line(b'chown',
+               b'recursively changing ownership of %s to %s:%s\n' %
+               (path.encode('utf-8'), user.encode('utf-8'), group.encode(
+                   'utf-8')))
+
+    set_dir_permissions(path, uid, gid)
+
+    for root, dirs, files in os.walk(path):
+        for d in dirs:
+            set_dir_permissions(os.path.join(root, d), uid, gid)
+
+        for f in files:
+            # File may be a symlink that points to nowhere. In which case
+            # os.chown() would fail because it attempts to follow the
+            # symlink. We only care about directory entries, not what
+            # they point to. So setting the owner of the symlink should
+            # be sufficient.
+            os.lchown(os.path.join(root, f), uid, gid)
+
+
+def configure_cache_posix(cache, user, group,
+                          untrusted_caches, running_as_root):
+    """Configure a cache path on POSIX platforms.
+
+    For each cache, we write out a special file denoting attributes and
+    capabilities of run-task and the task being executed. These attributes
+    are used by subsequent run-task invocations to validate that use of
+    the cache is acceptable.
+
+    We /could/ blow away the cache data on requirements mismatch.
+    While this would be convenient, this could result in "competing" tasks
+    effectively undoing the other's work. This would slow down task
+    execution in aggregate. Without monitoring for this, people may not notice
+    the problem and tasks would be slower than they could be. We follow the
+    principle of "fail fast" to ensure optimal task execution.
+
+    We also write an audit log of who used the caches. This log is printed
+    during failures to help aid debugging.
+    """
+
+    our_requirements = {
+        # Include a version string that we can bump whenever to trigger
+        # fresh caches. The actual value is not relevant and doesn't need
+        # to follow any explicit order. Since taskgraph bakes this file's
+        # hash into cache names, any change to this file/version is sufficient
+        # to force the use of a new cache.
+        b'version=1',
+        # Include the UID and GID the task will run as to ensure that tasks
+        # with different UID and GID don't share the same cache.
+        b'uid=%d' % user.pw_uid,
+        b'gid=%d' % group.gr_gid,
+    }
+
+    requires_path = os.path.join(cache, '.cacherequires')
+    audit_path = os.path.join(cache, '.cachelog')
+
+    # The cache is empty. Configure it.
+    if not os.listdir(cache):
+        print_line(b'cache', b'cache %s is empty; writing requirements: '
+                             b'%s\n' % (
+                                 cache.encode('utf-8'), b' '.join(sorted(our_requirements))))
+
+        # We write a requirements file so future invocations know what the
+        # requirements are.
+        with open(requires_path, 'wb') as fh:
+            fh.write(b'\n'.join(sorted(our_requirements)))
+
+        # And make it read-only as a precaution against deletion.
+        os.chmod(requires_path, stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)
+
+        write_audit_entry(audit_path,
+                          b'created; requirements: %s' %
+                          b', '.join(sorted(our_requirements)))
+
+        set_dir_permissions(cache, user.pw_uid, group.gr_gid)
+        return
+
+    # The cache has content and we have a requirements file. Validate
+    # requirements alignment.
+    if os.path.exists(requires_path):
+        with open(requires_path, 'rb') as fh:
+            wanted_requirements = set(fh.read().splitlines())
+
+        print_line(b'cache', b'cache %s exists; requirements: %s\n' % (
+            cache.encode('utf-8'), b' '.join(sorted(wanted_requirements))))
+
+        missing = wanted_requirements - our_requirements
+
+        # Allow requirements mismatch for uid/gid if and only if caches
+        # are untrusted. This allows cache behavior on Try to be
+        # reasonable. Otherwise, random tasks could "poison" cache
+        # usability by introducing uid/gid mismatches. For untrusted
+        # environments like Try, this is a perfectly reasonable thing to
+        # allow.
+        if missing and untrusted_caches and running_as_root and \
+                all(s.startswith((b'uid=', b'gid=')) for s in missing):
+            print_line(b'cache',
+                       b'cache %s uid/gid mismatch; this is acceptable '
+                       b'because caches for this task are untrusted; '
+                       b'changing ownership to facilitate cache use\n' %
+                       cache.encode('utf-8'))
+            chown_recursive(cache, user.pw_name, group.gr_name, user.pw_uid,
+                            group.gr_gid)
+
+            # And write out the updated reality.
+            with open(requires_path, 'wb') as fh:
+                fh.write(b'\n'.join(sorted(our_requirements)))
+
+            write_audit_entry(audit_path,
+                              b'chown; requirements: %s' %
+                              b', '.join(sorted(our_requirements)))
+
+        elif missing:
+            print('error: requirements for populated cache %s differ from '
+                  'this task' % cache)
+            print('cache requirements: %s' % ' '.join(sorted(
+                s.decode('utf-8') for s in wanted_requirements)))
+            print('our requirements:   %s' % ' '.join(sorted(
+                s.decode('utf-8') for s in our_requirements)))
+            if any(s.startswith((b'uid=', b'gid=')) for s in missing):
+                print(CACHE_UID_GID_MISMATCH)
+
+            write_audit_entry(audit_path,
+                              b'requirements mismatch; wanted: %s' %
+                              b', '.join(sorted(our_requirements)))
+
+            print('')
+            print('audit log:')
+            with open(audit_path, 'r') as fh:
+                print(fh.read())
+
+            return True
+        else:
+            write_audit_entry(audit_path, b'used')
+
+        # We don't need to adjust permissions here because the cache is
+        # associated with a uid/gid and the first task should have set
+        # a proper owner/group.
+
+        return
+
+    # The cache has content and no requirements file. This shouldn't
+    # happen because run-task should be the first thing that touches a
+    # cache.
+    print('error: cache %s is not empty and is missing a '
+          '.cacherequires file; the cache names for this task are '
+          'likely mis-configured or TASKCLUSTER_CACHES is not set '
+          'properly' % cache)
+
+    write_audit_entry(audit_path, b'missing .cacherequires')
+    return True
+
+
+def configure_volume_posix(volume, user, group, running_as_root):
+    # The only time we should see files in the volume is if the Docker
+    # image build put files there.
+    #
+    # For the sake of simplicity, our policy is that volumes should be
+    # empty. This also has the advantage that an empty volume looks
+    # a lot like an empty cache. Tasks can rely on caches being
+    # swapped in and out on any volume without any noticeable change
+    # of behavior.
+    volume_files = os.listdir(volume)
+    if volume_files:
+        print(NON_EMPTY_VOLUME % volume)
+        print('entries in root directory: %s' %
+              ' '.join(sorted(volume_files)))
+        sys.exit(1)
+
+    # The volume is almost certainly owned by root:root. Chown it so it
+    # is writable.
+
+    if running_as_root:
+        print_line(b'volume', b'changing ownership of volume %s '
+                              b'to %d:%d\n' % (volume.encode('utf-8'),
+                                               user.pw_uid,
+                                               group.gr_gid))
+        set_dir_permissions(volume, user.pw_uid, group.gr_gid)
+
+
+def vcs_checkout(source_repo, dest, store_path,
+                 base_repo=None, revision=None, branch=None,
+                 fetch_hgfingerprint=False, sparse_profile=None):
+    # Specify method to checkout a revision. This defaults to revisions as
+    # SHA-1 strings, but also supports symbolic revisions like `tip` via the
+    # branch flag.
+    if revision:
+        revision_flag = '--revision'
+        revision_value = revision
+    elif branch:
+        revision_flag = '--branch'
+        revision_value = branch
+    else:
+        print('revision is not specified for checkout')
+        sys.exit(1)
+
+    if IS_MACOSX or IS_POSIX:
+        hg_bin = 'hg'
+    elif IS_WINDOWS:
+        # This is where OCC installs it in the AMIs.
+        hg_bin = r'C:\Program Files\Mercurial\hg.exe'
+        if not os.path.exists(hg_bin):
+            print('could not find Mercurial executable: %s' % hg_bin)
+            sys.exit(1)
+
+    store_path = os.path.abspath(store_path)
+    args = [
+        hg_bin,
+        'robustcheckout',
+        '--sharebase', store_path,
+        '--purge',
+    ]
+
+    # Obtain certificate fingerprints.  Without this, the checkout will use the fingerprint
+    # on the system, which is managed some other way (such as puppet)
+    if fetch_hgfingerprint:
+        try:
+            print_line(b'vcs', b'fetching hg.mozilla.org fingerprint from %s\n' %
+                       FINGERPRINT_URL.encode('utf-8'))
+            res = urllib.request.urlopen(FINGERPRINT_URL, timeout=10)
+            secret = res.read()
+            try:
+                secret = json.loads(secret.decode('utf-8'))
+            except ValueError:
+                print_line(b'vcs', b'invalid JSON in hg fingerprint secret')
+                sys.exit(1)
+        except (urllib.error.URLError, socket.timeout):
+            print_line(b'vcs', b'Unable to retrieve current hg.mozilla.org fingerprint'
+                               b'using the secret service, using fallback instead.')
+            # XXX This fingerprint will not be accurate if running on an old
+            #     revision after the server fingerprint has changed.
+            secret = {'secret': FALLBACK_FINGERPRINT}
+
+        hgmo_fingerprint = secret['secret']['fingerprints']
+        args.extend([
+            '--config', 'hostsecurity.hg.mozilla.org:fingerprints=%s' % hgmo_fingerprint,
+        ])
+
+    if base_repo:
+        args.extend(['--upstream', base_repo])
+    if sparse_profile:
+        args.extend(['--sparseprofile', sparse_profile])
+
+    dest = os.path.abspath(dest)
+    args.extend([
+        revision_flag, revision_value,
+        source_repo, dest,
+    ])
+
+    res = run_and_prefix_output(b'vcs', args,
+                                extra_env={'PYTHONUNBUFFERED': '1'})
+    if res:
+        sys.exit(res)
+
+    # Update the current revision hash and ensure that it is well formed.
+    revision = subprocess.check_output(
+        [hg_bin, 'log',
+         '--rev', '.',
+         '--template', '{node}'],
+        cwd=dest,
+        # Triggers text mode on Python 3.
+        universal_newlines=True)
+
+    assert re.match('^[a-f0-9]{40}$', revision)
+
+    msg = ("TinderboxPrint:<a href={source_repo}/rev/{revision} "
+           "title='Built from {repo_name} revision {revision}'>"
+           "{revision}</a>\n".format(revision=revision,
+                                     source_repo=source_repo,
+                                     repo_name=source_repo.split('/')[-1]))
+
+    print_line(b'vcs', msg.encode('utf-8'))
+
+    return revision
+
+
+def fetch_artifacts():
+    print_line(b'fetches', b'fetching artifacts\n')
+
+    fetch_content = shutil.which('fetch-content')
+    if not fetch_content and os.environ.get('GECKO_PATH'):
+        fetch_content = os.path.join(os.environ['GECKO_PATH'], 'taskcluster',
+                                     'scripts', 'misc', 'fetch-content')
+
+    if not fetch_content or not os.path.isfile(fetch_content):
+        fetch_content = os.path.join(os.path.dirname(__file__),
+                                     'fetch-content')
+
+    if not os.path.isfile(fetch_content):
+        print(FETCH_CONTENT_NOT_FOUND)
+        sys.exit(1)
+
+    cmd = [sys.executable, '-u', fetch_content, 'task-artifacts']
+    res = run_and_prefix_output(b'fetches', cmd)
+    if res:
+        sys.exit(res)
+
+    print_line(b'fetches', b'finished fetching artifacts\n')
+
+
+def add_vcs_arguments(parser, project, name):
+    """Adds arguments to ArgumentParser to control VCS options for a project."""
+
+    parser.add_argument('--%s-checkout' % project,
+                        help='Directory where %s checkout should be created' %
+                             name)
+    parser.add_argument('--%s-sparse-profile' % project,
+                        help='Path to sparse profile for %s checkout' % name)
+
+
+def resolve_checkout_url(base_repo, head_repo):
+    """Resolve the Mercurial URL to perform a checkout against, either the
+    public hg.mozilla.org service or a CI-only regional mirror.
+
+    The config will be of the form:
+        {
+            "aws/us-west-2": {  # key built from `TASKCLUSTER_WORKER_LOCATION` variable
+                "rate": 0.5,
+                "domain": "us-west-2.hgmointernal.net"
+            },
+            "google/us-central1": {...}
+        }
+    """
+    worker_location = os.getenv('TASKCLUSTER_WORKER_LOCATION')
+    if not worker_location:
+        print_line(b'vcs', b'TASKCLUSTER_WORKER_LOCATION environment variable not set; '
+                           b'using public hg.mozilla.org service\n')
+        return base_repo, head_repo
+
+    try:
+        worker_location = json.loads(worker_location)
+    except json.JSONDecodeError:
+        print_line(b'vcs', b'Could not decode TASKCLUSTER_WORKER_LOCATION environment variable '
+                           b'as JSON. Content: %s\n' % worker_location.encode('utf-8'))
+        print_line(b'vcs', b'using public hg.mozilla.org service\n')
+        return base_repo, head_repo
+
+    if 'cloud' not in worker_location or 'region' not in worker_location:
+        print_line(b'vcs', b'TASKCLUSTER_WORKER_LOCATION missing required keys; '
+                           b'using public hg.mozilla.org service\n')
+        return base_repo, head_repo
+
+    config_key = '%(cloud)s/%(region)s' % worker_location
+
+    try:
+        print_line(b'vcs', b'fetching hgmointernal config from %s\n' %
+                   HGMOINTERNAL_CONFIG_URL.encode('utf-8'))
+
+        # Get the hgmointernal config Taskcluster secret
+        res = urllib.request.urlopen(HGMOINTERNAL_CONFIG_URL, timeout=10)
+        hgmointernal_config = json.loads(res.read().decode('utf-8'))['secret']
+
+        # Use public hg service if region not yet supported
+        if config_key not in hgmointernal_config:
+            print_line(b'vcs', b'region %s not yet supported; using public '
+                               b'hg.mozilla.org service\n' % config_key.encode('utf-8'))
+
+            return base_repo, head_repo
+
+        # Only send a percentage of traffic to the internal mirror
+        rate = float(hgmointernal_config[config_key]['rate'])
+
+        if random.random() > rate:
+            print_line(b'vcs', b'hgmointernal rate miss; using '
+                               b'public hg.mozilla.org service\n')
+            return base_repo, head_repo
+
+        print_line(b'vcs', b'hgmointernal rate hit; cloning from '
+                           b'private hgweb mirror\n')
+
+        mirror_domain = hgmointernal_config[config_key]['domain']
+
+        if base_repo and base_repo.startswith('https://hg.mozilla.org'):
+            base_repo = base_repo.replace('hg.mozilla.org', mirror_domain, 1)
+
+        if head_repo and head_repo.startswith('https://hg.mozilla.org'):
+            head_repo = head_repo.replace('hg.mozilla.org', mirror_domain, 1)
+
+        return base_repo, head_repo
+
+    except (KeyError, ValueError):
+        print_line(b'vcs', b'invalid JSON in hgmointernal config; '
+                           b'falling back to public hg.mozilla.org service\n')
+
+    except (urllib.error.URLError, socket.timeout):
+        print_line(b'vcs', b'Unable to retrieve hgmointernal config using '
+                           b'the secret service; falling back to public hg.mozilla.org '
+                           b'service\n')
+
+    return base_repo, head_repo
+
+
+def collect_vcs_options(args, project):
+    checkout = getattr(args, '%s_checkout' % project)
+    sparse_profile = getattr(args, '%s_sparse_profile' % project)
+
+    env_prefix = project.upper()
+
+    base_repo = os.environ.get('%s_BASE_REPOSITORY' % env_prefix)
+    head_repo = os.environ.get('%s_HEAD_REPOSITORY' % env_prefix)
+    revision = os.environ.get('%s_HEAD_REV' % env_prefix)
+    branch = os.environ.get('%s_HEAD_REF' % env_prefix)
+
+    store_path = os.environ.get('HG_STORE_PATH')
+
+    # Expand ~ in some paths.
+    if checkout:
+        checkout = os.path.expanduser(checkout)
+    if store_path:
+        store_path = os.path.expanduser(store_path)
+
+    # Some callers set the base repository to mozilla-central for historical
+    # reasons. Switch to mozilla-unified because robustcheckout works best
+    # with it.
+    if base_repo == 'https://hg.mozilla.org/mozilla-central':
+        base_repo = 'https://hg.mozilla.org/mozilla-unified'
+
+    # No need to check the hgmointernal config if we aren't performing
+    # a checkout.
+    if checkout:
+        base_repo, head_repo = resolve_checkout_url(base_repo, head_repo)
+
+    return {
+        'store-path': store_path,
+        'project': project,
+        'env-prefix': env_prefix,
+        'checkout': checkout,
+        'sparse-profile': sparse_profile,
+        'base-repo': base_repo,
+        'head-repo': head_repo,
+        'revision': revision,
+        'branch': branch,
+    }
+
+
+def vcs_checkout_from_args(args, project):
+    options = collect_vcs_options(args, project)
+
+    if not options['checkout']:
+        if options['branch'] and not options['revision']:
+            print('task should be defined in terms of non-symbolic revision')
+            sys.exit(1)
+        return
+
+    os.environ['%s_HEAD_REV' % options['env-prefix']] = vcs_checkout(
+        options['head-repo'],
+        options['checkout'],
+        options['store-path'],
+        base_repo=options['base-repo'],
+        revision=options['revision'],
+        fetch_hgfingerprint=args.fetch_hgfingerprint,
+        branch=options['branch'],
+        sparse_profile=options['sparse-profile'])
+
+
+def maybe_run_resource_monitoring():
+    """Run the resource monitor if available.
+
+    Discussion in https://github.com/taskcluster/taskcluster-rfcs/pull/160
+    and https://bugzil.la/1648051
+    """
+    if 'MOZ_FETCHES' not in os.environ:
+        return
+    if 'RESOURCE_MONITOR_OUTPUT' not in os.environ:
+        return
+
+    prefix = b'resource_monitor'
+
+    executable = '{}/resource-monitor/resource-monitor{}'.format(
+        os.environ.get('MOZ_FETCHES_DIR'), '.exe' if IS_WINDOWS else '')
+
+    if not os.path.exists(executable) or not os.access(executable, os.X_OK):
+        print_line(prefix, b"%s not executable\n" % executable.encode('utf-8'))
+        return
+    args = [
+        executable,
+        '-process',
+        str(os.getpid()),
+        '-output',
+        os.environ["RESOURCE_MONITOR_OUTPUT"],
+    ]
+    print_line(prefix, b"Resource monitor starting: %s\n" % str(args).encode('utf-8'))
+    # Avoid environment variables the payload doesn't need.
+    del os.environ['RESOURCE_MONITOR_OUTPUT']
+
+    # Without CREATE_NEW_PROCESS_GROUP Windows signals will attempt to kill run-task, too.
+    process = subprocess.Popen(args,
+                               bufsize=0,
+                               stdout=subprocess.PIPE,
+                               stderr=subprocess.STDOUT,
+                               creationflags=subprocess.CREATE_NEW_PROCESS_GROUP if IS_WINDOWS else 0,
+                               cwd=os.getcwd())
+
+    def capture_output():
+        fh = io.TextIOWrapper(process.stdout, encoding='latin1')
+        while True:
+            data = fh.readline().encode('latin1')
+            if data == b'':
+                break
+            print_line(prefix, data)
+
+    monitor_process = Thread(target=capture_output)
+    monitor_process.start()
+    return process
+
+
+def main(args):
+    print_line(b'setup', b'run-task started in %s\n' % os.getcwd().encode('utf-8'))
+    running_as_root = IS_POSIX and os.getuid() == 0
+
+    # Set a reasonable limit to the number of open files.
+    # Running under docker inherits the system defaults, which are not subject
+    # to the "standard" limits set by pam_limits.so, and while they work well
+    # for servers that may receive a lot of connections, they cause performance
+    # problems for things that close file descriptors before forking (for good
+    # reasons), like python's `subprocess.Popen(..., close_fds=True)` (and while
+    # the default was close_fds=False in python2, that changed in python3).
+    # In some cases, Firefox does the same thing when spawning subprocesses.
+    # Processes spawned by this one will inherit the limit set here.
+    try:
+        import resource
+        # Keep the hard limit the same, though, allowing processes to change their
+        # soft limit if they need to (Firefox does, for instance).
+        (soft, hard) = resource.getrlimit(resource.RLIMIT_NOFILE)
+        limit = os.environ.get('MOZ_LIMIT_NOFILE')
+        if limit:
+            limit = int(limit)
+        else:
+            # If no explicit limit is given, use 1024 if it's less than the current
+            # soft limit. For instance, the default on macOS is 256, so we'd pick
+            # that rather than 1024.
+            limit = min(soft, 1024)
+        # Now apply the limit, if it's different from the original one.
+        if limit != soft:
+            resource.setrlimit(resource.RLIMIT_NOFILE, (limit, hard))
+    except ImportError:
+        # The resource module is UNIX only.
+        pass
+
+    # Arguments up to '--' are ours. After are for the main task
+    # to be executed.
+    try:
+        i = args.index('--')
+        our_args = args[0:i]
+        task_args = args[i + 1:]
+    except ValueError:
+        our_args = args
+        task_args = []
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--user', default='worker', help='user to run as')
+    parser.add_argument('--group', default='worker', help='group to run as')
+    parser.add_argument('--task-cwd', help='directory to run the provided command in')
+
+    add_vcs_arguments(parser, 'gecko', 'Firefox')
+    add_vcs_arguments(parser, 'comm', 'Comm')
+
+    parser.add_argument('--fetch-hgfingerprint', action='store_true',
+                        help='Fetch the latest hgfingerprint from the secrets store, '
+                        'using the taskclsuerProxy')
+
+    args = parser.parse_args(our_args)
+
+    uid = gid = gids = None
+    if IS_POSIX and running_as_root:
+        user, group, gids = get_posix_user_group(args.user, args.group)
+        uid = user.pw_uid
+        gid = group.gr_gid
+
+    if running_as_root and os.path.exists("/dev/kvm"):
+        # Ensure kvm permissions for worker, required for Android x86
+        st = os.stat("/dev/kvm")
+        os.chmod("/dev/kvm", st.st_mode | 0o666)
+
+    # Validate caches.
+    #
+    # Taskgraph should pass in a list of paths that are caches via an
+    # environment variable (which we don't want to pass down to child
+    # processes).
+
+    if 'TASKCLUSTER_CACHES' in os.environ:
+        caches = os.environ['TASKCLUSTER_CACHES'].split(';')
+        del os.environ['TASKCLUSTER_CACHES']
+    else:
+        caches = []
+
+    if 'TASKCLUSTER_UNTRUSTED_CACHES' in os.environ:
+        untrusted_caches = True
+        del os.environ['TASKCLUSTER_UNTRUSTED_CACHES']
+    else:
+        untrusted_caches = False
+
+    for cache in caches:
+        if not os.path.isdir(cache):
+            print('error: cache %s is not a directory; this should never '
+                  'happen' % cache)
+            return 1
+
+        if running_as_root:
+        	purge = configure_cache_posix(cache, user, group, untrusted_caches,
+                                          running_as_root)
+
+	        if purge:
+                    return EXIT_PURGE_CACHE
+
+    if 'TASKCLUSTER_VOLUMES' in os.environ:
+        volumes = os.environ['TASKCLUSTER_VOLUMES'].split(';')
+        del os.environ['TASKCLUSTER_VOLUMES']
+    else:
+        volumes = []
+
+    if volumes and not IS_POSIX:
+        print('assertion failed: volumes not expected on Windows')
+        return 1
+
+    # Sanitize volumes.
+    for volume in volumes:
+        # If a volume is a cache, it was dealt with above.
+        if volume in caches:
+            print_line(b'volume', b'volume %s is a cache\n' %
+                       volume.encode('utf-8'))
+            continue
+
+        if running_as_root:
+            configure_volume_posix(volume, user, group, running_as_root)
+
+    all_caches_and_volumes = set(map(os.path.normpath, caches))
+    all_caches_and_volumes |= set(map(os.path.normpath, volumes))
+
+    def path_in_cache_or_volume(path):
+        path = os.path.normpath(path)
+
+        while path:
+            if path in all_caches_and_volumes:
+                return True
+
+            path, child = os.path.split(path)
+            if not child:
+                break
+
+        return False
+
+    def prepare_checkout_dir(checkout):
+        if not checkout:
+            return
+
+        # The checkout path becomes the working directory. Since there are
+        # special cache files in the cache's root directory and working
+        # directory purging could blow them away, disallow this scenario.
+        if os.path.exists(os.path.join(checkout, '.cacherequires')):
+            print('error: cannot perform vcs checkout into cache root: %s' %
+                  checkout)
+            sys.exit(1)
+
+        # TODO given the performance implications, consider making this a fatal
+        # error.
+        if not path_in_cache_or_volume(checkout):
+            print_line(b'vcs', b'WARNING: vcs checkout path (%s) not in cache '
+                               b'or volume; performance will likely suffer\n' %
+                               checkout.encode('utf-8'))
+
+        # Ensure the directory for the source checkout exists.
+        try:
+            os.makedirs(os.path.dirname(checkout))
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+        # And that it is owned by the appropriate user/group.
+        if running_as_root:
+            os.chown(os.path.dirname(checkout), uid, gid)
+
+    def prepare_hg_store_path():
+        # And ensure the shared store path exists and has proper permissions.
+        if 'HG_STORE_PATH' not in os.environ:
+            print('error: HG_STORE_PATH environment variable not set')
+            sys.exit(1)
+
+        store_path = os.environ['HG_STORE_PATH']
+
+        if not path_in_cache_or_volume(store_path):
+            print_line(b'vcs', b'WARNING: HG_STORE_PATH (%s) not in cache or '
+                               b'volume; performance will likely suffer\n' %
+                               store_path.encode('utf-8'))
+
+        try:
+            os.makedirs(store_path)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+        if running_as_root:
+            os.chown(store_path, uid, gid)
+
+    prepare_checkout_dir(args.gecko_checkout)
+    if args.gecko_checkout or args.comm_checkout:
+        prepare_hg_store_path()
+
+    if IS_POSIX and running_as_root:
+        # Drop permissions to requested user.
+        # This code is modeled after what `sudo` was observed to do in a Docker
+        # container. We do not bother calling setrlimit() because containers have
+        # their own limits.
+        print_line(b'setup', b'running as %s:%s\n' % (
+            args.user.encode('utf-8'), args.group.encode('utf-8')))
+
+        os.setgroups(gids)
+        os.umask(0o22)
+        os.setresgid(gid, gid, gid)
+        os.setresuid(uid, uid, uid)
+
+    vcs_checkout_from_args(args, 'gecko')
+    vcs_checkout_from_args(args, 'comm')
+
+    resource_process = None
+
+    try:
+        for k in ('GECKO_PATH', 'MOZ_FETCHES_DIR', 'UPLOAD_DIR', 'MOZ_PYTHON_HOME'):
+            if k in os.environ:
+                # Normalize paths to use forward slashes. Some shell scripts
+                # tolerate that better on Windows.
+                os.environ[k] = os.path.abspath(os.environ[k]).replace(os.sep, '/')
+                print_line(b'setup', b'%s is %s\n' % (
+                    k.encode('utf-8'),
+                    os.environ[k].encode('utf-8')))
+
+        if 'MOZ_FETCHES' in os.environ:
+            fetch_artifacts()
+
+            # If Python is a fetch dependency, add it to the PATH and setting
+            # the mozilla-specific MOZ_PYTHON_HOME to relocate binaries.
+            if 'MOZ_PYTHON_HOME' in os.environ:
+
+                print_line(b'setup',
+                           b'Setting up local python environment\n')
+                prev = [os.environ['PATH']] if 'PATH' in os.environ else []
+
+                moz_python_home = os.environ['MOZ_PYTHON_HOME']
+                if IS_WINDOWS:
+                    ext = '.exe'
+                    moz_python_bindir = moz_python_home
+                else:
+                    ext = ''
+                    moz_python_bindir = moz_python_home + '/bin'
+
+
+                # just a sanity check
+                candidate = os.path.join(moz_python_bindir, f'python3{ext}')
+                if not os.path.exists(candidate):
+                    raise RuntimeError("Inconsistent Python installation: "
+                                       "archive found, but no python3 binary "
+                                       "detected")
+
+                new = os.environ['PATH'] = os.pathsep.join([moz_python_bindir]
+                                                           + prev)
+
+                # Relocate the python binary. Standard way uses PYTHONHOME, but
+                # this conflicts with system python (e.g. used by hg) so we
+                # maintain a small patch to use MOZPYTHONHOME instead.
+                os.environ['MOZPYTHONHOME'] = moz_python_home
+
+                print_line(b'setup',
+                           b'updated PATH with python artifact: '
+                           + new.encode() + b'\n')
+
+
+        resource_process = maybe_run_resource_monitoring()
+
+        return run_and_prefix_output(b'task', task_args, cwd=args.task_cwd)
+    finally:
+        if resource_process:
+            print_line(b'resource_monitor', b'terminating\n')
+            if IS_WINDOWS:
+                # .terminate() on Windows is not a graceful shutdown, due to
+                # differences in signals. CTRL_BREAK_EVENT will work provided
+                # the subprocess is in a different process group, so this script
+                # isn't also killed.
+                os.kill(resource_process.pid, signal.CTRL_BREAK_EVENT)
+            else:
+                resource_process.terminate()
+            resource_process.wait()
+
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv[1:]))