Fork runtest.py and everything it needs src-side for easier hacking

infra/scripts/legacy/scripts/common/chromium_utils.py

Index: infra/scripts/legacy/scripts/common/chromium_utils.py
diff --git a/infra/scripts/legacy/scripts/common/chromium_utils.py b/infra/scripts/legacy/scripts/common/chromium_utils.py
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+# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+""" Set of basic operations/utilities that are used by the build. """
+
+from contextlib import contextmanager
+import ast
+import base64
+import cStringIO
+import copy
+import errno
+import fnmatch
+import glob
+import math
+import multiprocessing
+import os
+import re
+import shutil
+import socket
+import stat
+import string  # pylint: disable=W0402
+import subprocess
+import sys
+import threading
+import time
+import traceback
+import urllib
+import zipfile
+import zlib
+
+try:
+  import json  # pylint: disable=F0401
+except ImportError:
+  import simplejson as json
+
+from common import env
+
+
+BUILD_DIR = os.path.realpath(os.path.join(
+    os.path.dirname(__file__), os.pardir, os.pardir))
+
+
+WIN_LINK_FUNC = None
+try:
+  if sys.platform.startswith('win'):
+    import ctypes
+    # There's 4 possibilities on Windows for links:
+    # 1. Symbolic file links;
+    # 2. Symbolic directory links;
+    # 3. Hardlinked files;
+    # 4. Junctioned directories.
+    # (Hardlinked directories don't really exist.)
+    #
+    # 7-Zip does not handle symbolic file links as we want (it puts the
+    # content of the link, not what it refers to, and reports "CRC Error" on
+    # extraction). It does work as expected for symbolic directory links.
+    # Because the majority of the large files are in the root of the staging
+    # directory, we do however need to handle file links, so we do this with
+    # hardlinking. Junctioning requires a huge whack of code, so we take the
+    # slightly odd tactic of using #2 and #3, but not #1 and #4. That is,
+    # hardlinks for files, but symbolic links for directories.
+    def _WIN_LINK_FUNC(src, dst):
+      print 'linking %s -> %s' % (src, dst)
+      if os.path.isdir(src):
+        if not ctypes.windll.kernel32.CreateSymbolicLinkA(
+            str(dst), str(os.path.abspath(src)), 1):
+          raise ctypes.WinError()
+      else:
+        if not ctypes.windll.kernel32.CreateHardLinkA(str(dst), str(src), 0):
+          raise ctypes.WinError()
+    WIN_LINK_FUNC = _WIN_LINK_FUNC
+except ImportError:
+  # If we don't have ctypes or aren't on Windows, leave WIN_LINK_FUNC as None.
+  pass
+
+
+# Wrapper around git that enforces a timeout.
+GIT_BIN = os.path.join(BUILD_DIR, 'scripts', 'tools', 'git-with-timeout')
+
+# Wrapper around svn that enforces a timeout.
+SVN_BIN = os.path.join(BUILD_DIR, 'scripts', 'tools', 'svn-with-timeout')
+
+# The Google Storage metadata key for the full commit position
+GS_COMMIT_POSITION_KEY = 'Cr-Commit-Position'
+# The Google Storage metadata key for the commit position number
+GS_COMMIT_POSITION_NUMBER_KEY = 'Cr-Commit-Position-Number'
+# The Google Storage metadata key for the Git commit hash
+GS_GIT_COMMIT_KEY = 'Cr-Git-Commit'
+
+# Regular expression to identify a Git hash
+GIT_COMMIT_HASH_RE = re.compile(r'[a-zA-Z0-9]{40}')
+#
+# Regular expression to parse a commit position
+COMMIT_POSITION_RE = re.compile(r'([^@]+)@{#(\d+)}')
+
+# Local errors.
+class MissingArgument(Exception):
+  pass
+class PathNotFound(Exception):
+  pass
+class ExternalError(Exception):
+  pass
+class NoIdentifiedRevision(Exception):
+  pass
+
+def IsWindows():
+  return sys.platform == 'cygwin' or sys.platform.startswith('win')
+
+def IsLinux():
+  return sys.platform.startswith('linux')
+
+def IsMac():
+  return sys.platform.startswith('darwin')
+
+# For chromeos we need to end up with a different platform name, but the
+# scripts use the values like sys.platform for both the build target and
+# and the running OS, so this gives us a back door that can be hit to
+# force different naming then the default for some of the chromeos build
+# steps.
+override_platform_name = None
+
+
+def OverridePlatformName(name):
+  """Sets the override for PlatformName()"""
+  global override_platform_name
+  override_platform_name = name
+
+
+def PlatformName():
+  """Return a string to be used in paths for the platform."""
+  if override_platform_name:
+    return override_platform_name
+  if IsWindows():
+    return 'win32'
+  if IsLinux():
+    return 'linux'
+  if IsMac():
+    return 'mac'
+  raise NotImplementedError('Unknown platform "%s".' % sys.platform)
+
+
+# Name of the file (inside the packaged build) containing revision number
+# of that build. Also used for determining the latest packaged build.
+FULL_BUILD_REVISION_FILENAME = 'FULL_BUILD_REVISION'
+
+def IsGitCommit(value):
+  """Returns: If a value is a Git commit hash.
+
+  This only works on full Git commit hashes. A value qualifies as a Git commit
+  hash if it only contains hexadecimal numbers and is forty characters long.
+  """
+  if value is None:
+    return False
+  return GIT_COMMIT_HASH_RE.match(str(value)) is not None
+
+
+# GetParentClass allows a class instance to find its parent class using Python's
+# inspect module.  This allows a class instantiated from a module to access
+# their parent class's methods even after the containing module has been
+# re-imported and reloaded.
+#
+# Also see:
+#   http://code.google.com/p/chromium/issues/detail?id=34089
+#   http://atlee.ca/blog/2008/11/21/python-reload-danger-here-be-dragons/
+#
+def GetParentClass(obj, n=1):
+  import inspect
+  if inspect.isclass(obj):
+    return inspect.getmro(obj)[n]
+  else:
+    return inspect.getmro(obj.__class__)[n]
+
+
+def MeanAndStandardDeviation(data):
+  """Calculates mean and standard deviation for the values in the list.
+
+    Args:
+      data: list of numbers
+
+    Returns:
+      Mean and standard deviation for the numbers in the list.
+  """
+  n = len(data)
+  if n == 0:
+    return 0.0, 0.0
+  mean = float(sum(data)) / n
+  variance = sum([(element - mean)**2 for element in data]) / n
+  return mean, math.sqrt(variance)
+
+
+def FilteredMeanAndStandardDeviation(data):
+  """Calculates mean and standard deviation for the values in the list
+  ignoring first occurence of max value (unless there was only one sample).
+
+    Args:
+      data: list of numbers
+
+    Returns:
+      Mean and standard deviation for the numbers in the list ignoring
+      first occurence of max value.
+  """
+
+  def _FilterMax(array):
+    new_array = copy.copy(array)  # making sure we are not creating side-effects
+    if len(new_array) != 1:
+      new_array.remove(max(new_array))
+    return new_array
+  return MeanAndStandardDeviation(_FilterMax(data))
+
+def HistogramPercentiles(histogram, percentiles):
+  if not 'buckets' in histogram or not 'count' in histogram:
+    return []
+  computed_percentiles = _ComputePercentiles(histogram['buckets'],
+                                             histogram['count'],
+                                             percentiles)
+  output = []
+  for p in computed_percentiles:
+    output.append({'percentile': p, 'value': computed_percentiles[p]})
+  return output
+
+def GeomMeanAndStdDevFromHistogram(histogram):
+  if not 'buckets' in histogram:
+    return 0.0, 0.0
+  count = 0
+  sum_of_logs = 0
+  for bucket in histogram['buckets']:
+    if 'high' in bucket:
+      bucket['mean'] = (bucket['low'] + bucket['high']) / 2.0
+    else:
+      bucket['mean'] = bucket['low']
+    if bucket['mean'] > 0:
+      sum_of_logs += math.log(bucket['mean']) * bucket['count']
+      count += bucket['count']
+
+  if count == 0:
+    return 0.0, 0.0
+
+  sum_of_squares = 0
+  geom_mean = math.exp(sum_of_logs / count)
+  for bucket in histogram['buckets']:
+    if bucket['mean'] > 0:
+      sum_of_squares += (bucket['mean'] - geom_mean) ** 2 * bucket['count']
+  return geom_mean, math.sqrt(sum_of_squares / count)
+
+def _LinearInterpolate(x0, target, x1, y0, y1):
+  """Perform linear interpolation to estimate an intermediate value.
+
+  We assume for some F, F(x0) == y0, and F(x1) == z1.
+
+  We return an estimate for what F(target) should be, using linear
+  interpolation.
+
+  Args:
+    x0: (Float) A location at which some function F() is known.
+    target: (Float) A location at which we need to estimate F().
+    x1: (Float) A second location at which F() is known.
+    y0: (Float) The value of F(x0).
+    y1: (Float) The value of F(x1).
+
+  Returns:
+    (Float) The estimated value of F(target).
+  """
+  if x0 == x1:
+    return (y0 + y1) / 2
+  return  (y1 - y0) * (target - x0) / (x1 - x0) + y0
+
+def _BucketInterpolate(last_percentage, target, next_percentage, bucket_min,
+                       bucket_max):
+  """Estimate a minimum which should have the target % of samples below it.
+
+  We do linear interpolation only if last_percentage and next_percentage are
+  adjacent, and hence we are in a linear section of a histogram. Once they
+  spread further apart we generally get exponentially broader buckets, and we
+  need to interpolate in the log domain (and exponentiate our result).
+
+  Args:
+    last_percentage: (Float) This is the percentage of samples below bucket_min.
+    target: (Float) A percentage for which we need an estimated bucket.
+    next_percentage: (Float) This is the percentage of samples below bucket_max.
+    bucket_min: (Float) This is the lower value for samples in a bucket.
+    bucket_max: (Float) This exceeds the upper value for samples.
+
+  Returns:
+    (Float) An estimate of what bucket cutoff would have probably had the target
+        percentage.
+  """
+  log_domain = False
+  if bucket_min + 1.5 < bucket_max and bucket_min > 0:
+    log_domain = True
+    bucket_min = math.log(bucket_min)
+    bucket_max = math.log(bucket_max)
+  result = _LinearInterpolate(
+      last_percentage, target, next_percentage, bucket_min, bucket_max)
+  if log_domain:
+    result = math.exp(result)
+  return result
+
+def _ComputePercentiles(buckets, total, percentiles):
+  """Compute percentiles for the given histogram.
+
+  Returns estimates for the bucket cutoffs that would probably have the taret
+  percentiles.
+
+  Args:
+    buckets: (List) A list of buckets representing the histogram to analyze.
+    total: (Float) The total number of samples in the histogram.
+    percentiles: (Tuple) The percentiles we are interested in.
+
+  Returns:
+    (Dictionary) Map from percentiles to bucket cutoffs.
+  """
+  if not percentiles:
+    return {}
+  current_count = 0
+  current_percentage = 0
+  next_percentile_index = 0
+  result = {}
+  for bucket in buckets:
+    if bucket['count'] > 0:
+      current_count += bucket['count']
+      old_percentage = current_percentage
+      current_percentage = float(current_count) / total
+
+      # Check whether we passed one of the percentiles we're interested in.
+      while (next_percentile_index < len(percentiles) and
+             current_percentage > percentiles[next_percentile_index]):
+        if not 'high' in bucket:
+          result[percentiles[next_percentile_index]] = bucket['low']
+        else:
+          result[percentiles[next_percentile_index]] = float(_BucketInterpolate(
+              old_percentage, percentiles[next_percentile_index],
+              current_percentage, bucket['low'], bucket['high']))
+        next_percentile_index += 1
+  return result
+
+class InitializePartiallyWithArguments:
+  # pylint: disable=old-style-class
+  """Function currying implementation.
+
+  Works for constructors too. Primary use is to be able to construct a class
+  with some constructor arguments beings set ahead of actual initialization.
+  Copy of an ASPN cookbook (#52549).
+  """
+
+  def __init__(self, clazz, *args, **kwargs):
+    self.clazz = clazz
+    self.pending = args[:]
+    self.kwargs = kwargs.copy()
+
+  def __call__(self, *args, **kwargs):
+    if kwargs and self.kwargs:
+      kw = self.kwargs.copy()
+      kw.update(kwargs)
+    else:
+      kw = kwargs or self.kwargs
+
+    return self.clazz(*(self.pending + args), **kw)
+
+
+def Prepend(filepath, text):
+  """ Prepends text to the file.
+
+  Creates the file if it does not exist.
+  """
+  file_data = text
+  if os.path.exists(filepath):
+    file_data += open(filepath).read()
+  f = open(filepath, 'w')
+  f.write(file_data)
+  f.close()
+
+
+def MakeWorldReadable(path):
+  """Change the permissions of the given path to make it world-readable.
+  This is often needed for archived files, so they can be served by web servers
+  or accessed by unprivileged network users."""
+
+  # No need to do anything special on Windows.
+  if IsWindows():
+    return
+
+  perms = stat.S_IMODE(os.stat(path)[stat.ST_MODE])
+  if os.path.isdir(path):
+    # Directories need read and exec.
+    os.chmod(path, perms | 0555)
+  else:
+    os.chmod(path, perms | 0444)
+
+
+def MakeParentDirectoriesWorldReadable(path):
+  """Changes the permissions of the given path and its parent directories
+  to make them world-readable. Stops on first directory which is
+  world-readable. This is often needed for archive staging directories,
+  so that they can be served by web servers or accessed by unprivileged
+  network users."""
+
+  # No need to do anything special on Windows.
+  if IsWindows():
+    return
+
+  while path != os.path.dirname(path):
+    current_permissions = stat.S_IMODE(os.stat(path)[stat.ST_MODE])
+    if current_permissions & 0555 == 0555:
+      break
+    os.chmod(path, current_permissions | 0555)
+    path = os.path.dirname(path)
+
+
+def MaybeMakeDirectory(*path):
+  """Creates an entire path, if it doesn't already exist."""
+  file_path = os.path.join(*path)
+  try:
+    os.makedirs(file_path)
+  except OSError, e:
+    if e.errno != errno.EEXIST:
+      raise
+
+
+def RemovePath(*path):
+  """Removes the file or directory at 'path', if it exists."""
+  file_path = os.path.join(*path)
+  if os.path.exists(file_path):
+    if os.path.isdir(file_path):
+      RemoveDirectory(file_path)
+    else:
+      RemoveFile(file_path)
+
+
+def RemoveFile(*path):
+  """Removes the file located at 'path', if it exists."""
+  file_path = os.path.join(*path)
+  try:
+    os.remove(file_path)
+  except OSError, e:
+    if e.errno != errno.ENOENT:
+      raise
+
+
+def MoveFile(path, new_path):
+  """Moves the file located at 'path' to 'new_path', if it exists."""
+  try:
+    RemoveFile(new_path)
+    os.rename(path, new_path)
+  except OSError, e:
+    if e.errno != errno.ENOENT:
+      raise
+
+
+def LocateFiles(pattern, root=os.curdir):
+  """Yeilds files matching pattern found in root and its subdirectories.
+
+  An exception is thrown if root doesn't exist."""
+  for path, _, files in os.walk(os.path.abspath(root)):
+    for filename in fnmatch.filter(files, pattern):
+      yield os.path.join(path, filename)
+
+
+def RemoveFilesWildcards(file_wildcard, root=os.curdir):
+  """Removes files matching 'file_wildcard' in root and its subdirectories, if
+  any exists.
+
+  An exception is thrown if root doesn't exist."""
+  for item in LocateFiles(file_wildcard, root):
+    try:
+      os.remove(item)
+    except OSError, e:
+      if e.errno != errno.ENOENT:
+        raise
+
+
+def RemoveGlobbedPaths(path_wildcard, root=os.curdir):
+  """Removes all paths matching 'path_wildcard' beneath root.
+
+  Returns the list of paths removed.
+
+  An exception is thrown if root doesn't exist."""
+  if not os.path.exists(root):
+    raise OSError(2, 'No such file or directory', root)
+
+  full_path_wildcard = os.path.join(path_wildcard, root)
+  paths = glob.glob(full_path_wildcard)
+  for path in paths:
+    # When glob returns directories they end in "/."
+    if path.endswith(os.sep + '.'):
+      path = path[:-2]
+    RemovePath(path)
+  return paths
+
+
+def RemoveDirectory(*path):
+  """Recursively removes a directory, even if it's marked read-only.
+
+  Remove the directory located at *path, if it exists.
+
+  shutil.rmtree() doesn't work on Windows if any of the files or directories
+  are read-only, which svn repositories and some .svn files are.  We need to
+  be able to force the files to be writable (i.e., deletable) as we traverse
+  the tree.
+
+  Even with all this, Windows still sometimes fails to delete a file, citing
+  a permission error (maybe something to do with antivirus scans or disk
+  indexing).  The best suggestion any of the user forums had was to wait a
+  bit and try again, so we do that too.  It's hand-waving, but sometimes it
+  works. :/
+  """
+  file_path = os.path.join(*path)
+  if not os.path.exists(file_path):
+    return
+
+  if sys.platform == 'win32':
+    # Give up and use cmd.exe's rd command.
+    file_path = os.path.normcase(file_path)
+    for _ in xrange(3):
+      print 'RemoveDirectory running %s' % (' '.join(
+          ['cmd.exe', '/c', 'rd', '/q', '/s', file_path]))
+      if not subprocess.call(['cmd.exe', '/c', 'rd', '/q', '/s', file_path]):
+        break
+      print '  Failed'
+      time.sleep(3)
+    return
+
+  def RemoveWithRetry_non_win(rmfunc, path):
+    if os.path.islink(path):
+      return os.remove(path)
+    else:
+      return rmfunc(path)
+
+  remove_with_retry = RemoveWithRetry_non_win
+
+  def RmTreeOnError(function, path, excinfo):
+    r"""This works around a problem whereby python 2.x on Windows has no ability
+    to check for symbolic links.  os.path.islink always returns False.  But
+    shutil.rmtree will fail if invoked on a symbolic link whose target was
+    deleted before the link.  E.g., reproduce like this:
+    > mkdir test
+    > mkdir test\1
+    > mklink /D test\current test\1
+    > python -c "import chromium_utils; chromium_utils.RemoveDirectory('test')"
+    To avoid this issue, we pass this error-handling function to rmtree.  If
+    we see the exact sort of failure, we ignore it.  All other failures we re-
+    raise.
+    """
+
+    exception_type = excinfo[0]
+    exception_value = excinfo[1]
+    # If shutil.rmtree encounters a symbolic link on Windows, os.listdir will
+    # fail with a WindowsError exception with an ENOENT errno (i.e., file not
+    # found).  We'll ignore that error.  Note that WindowsError is not defined
+    # for non-Windows platforms, so we use OSError (of which it is a subclass)
+    # to avoid lint complaints about an undefined global on non-Windows
+    # platforms.
+    if (function is os.listdir) and issubclass(exception_type, OSError):
+      if exception_value.errno == errno.ENOENT:
+        # File does not exist, and we're trying to delete, so we can ignore the
+        # failure.
+        print 'WARNING:  Failed to list %s during rmtree.  Ignoring.\n' % path
+      else:
+        raise
+    else:
+      raise
+
+  for root, dirs, files in os.walk(file_path, topdown=False):
+    # For POSIX:  making the directory writable guarantees removability.
+    # Windows will ignore the non-read-only bits in the chmod value.
+    os.chmod(root, 0770)
+    for name in files:
+      remove_with_retry(os.remove, os.path.join(root, name))
+    for name in dirs:
+      remove_with_retry(lambda p: shutil.rmtree(p, onerror=RmTreeOnError),
+                        os.path.join(root, name))
+
+  remove_with_retry(os.rmdir, file_path)
+
+
+def CopyFileToDir(src_path, dest_dir, dest_fn=None, link_ok=False):
+  """Copies the file found at src_path to the dest_dir directory, with metadata.
+
+  If dest_fn is specified, the src_path is copied to that name in dest_dir,
+  otherwise it is copied to a file of the same name.
+
+  Raises PathNotFound if either the file or the directory is not found.
+  """
+  # Verify the file and directory separately so we can tell them apart and
+  # raise PathNotFound rather than shutil.copyfile's IOError.
+  if not os.path.isfile(src_path):
+    raise PathNotFound('Unable to find file %s' % src_path)
+  if not os.path.isdir(dest_dir):
+    raise PathNotFound('Unable to find dir %s' % dest_dir)
+  src_file = os.path.basename(src_path)
+  if dest_fn:
+    # If we have ctypes and the caller doesn't mind links, use that to
+    # try to make the copy faster on Windows. http://crbug.com/418702.
+    if link_ok and WIN_LINK_FUNC:
+      WIN_LINK_FUNC(src_path, os.path.join(dest_dir, dest_fn))
+    else:
+      shutil.copy2(src_path, os.path.join(dest_dir, dest_fn))
+  else:
+    shutil.copy2(src_path, os.path.join(dest_dir, src_file))
+
+
+def MakeZip(output_dir, archive_name, file_list, file_relative_dir,
+            raise_error=True, remove_archive_directory=True):
+  """Packs files into a new zip archive.
+
+  Files are first copied into a directory within the output_dir named for
+  the archive_name, which will be created if necessary and emptied if it
+  already exists.  The files are then then packed using archive names
+  relative to the output_dir.  That is, if the zipfile is unpacked in place,
+  it will create a directory identical to the new archive_name directory, in
+  the output_dir.  The zip file will be named as the archive_name, plus
+  '.zip'.
+
+  Args:
+    output_dir: Absolute path to the directory in which the archive is to
+      be created.
+    archive_dir: Subdirectory of output_dir holding files to be added to
+      the new zipfile.
+    file_list: List of paths to files or subdirectories, relative to the
+      file_relative_dir.
+    file_relative_dir: Absolute path to the directory containing the files
+      and subdirectories in the file_list.
+    raise_error: Whether to raise a PathNotFound error if one of the files in
+      the list is not found.
+    remove_archive_directory: Whether to remove the archive staging directory
+      before copying files over to it.
+
+  Returns:
+    A tuple consisting of (archive_dir, zip_file_path), where archive_dir
+    is the full path to the newly created archive_name subdirectory.
+
+  Raises:
+    PathNotFound if any of the files in the list is not found, unless
+    raise_error is False, in which case the error will be ignored.
+  """
+
+  start_time = time.clock()
+  # Collect files into the archive directory.
+  archive_dir = os.path.join(output_dir, archive_name)
+  print 'output_dir: %s, archive_name: %s' % (output_dir, archive_name)
+  print 'archive_dir: %s, remove_archive_directory: %s, exists: %s' % (
+      archive_dir, remove_archive_directory, os.path.exists(archive_dir))
+  if remove_archive_directory and os.path.exists(archive_dir):
+    # Move it even if it's not a directory as expected. This can happen with
+    # FILES.cfg archive creation where we create an archive staging directory
+    # that is the same name as the ultimate archive name.
+    if not os.path.isdir(archive_dir):
+      print 'Moving old "%s" file to create same name directory.' % archive_dir
+      previous_archive_file = '%s.old' % archive_dir
+      MoveFile(archive_dir, previous_archive_file)
+    else:
+      print 'Removing %s' % archive_dir
+      RemoveDirectory(archive_dir)
+      print 'Now, os.path.exists(%s): %s' % (
+          archive_dir, os.path.exists(archive_dir))
+  MaybeMakeDirectory(archive_dir)
+  for needed_file in file_list:
+    needed_file = needed_file.rstrip()
+    # These paths are relative to the file_relative_dir.  We need to copy
+    # them over maintaining the relative directories, where applicable.
+    src_path = os.path.join(file_relative_dir, needed_file)
+    dirname, basename = os.path.split(needed_file)
+    try:
+      if os.path.isdir(src_path):
+        if WIN_LINK_FUNC:
+          WIN_LINK_FUNC(src_path, os.path.join(archive_dir, needed_file))
+        else:
+          shutil.copytree(src_path, os.path.join(archive_dir, needed_file),
+                          symlinks=True)
+      elif dirname != '' and basename != '':
+        dest_dir = os.path.join(archive_dir, dirname)
+        MaybeMakeDirectory(dest_dir)
+        CopyFileToDir(src_path, dest_dir, basename, link_ok=True)
+      else:
+        CopyFileToDir(src_path, archive_dir, basename, link_ok=True)
+    except PathNotFound:
+      if raise_error:
+        raise
+  end_time = time.clock()
+  print 'Took %f seconds to create archive directory.' % (end_time - start_time)
+
+  # Pack the zip file.
+  output_file = '%s.zip' % archive_dir
+  previous_file = '%s_old.zip' % archive_dir
+  MoveFile(output_file, previous_file)
+
+  # If we have 7z, use that as it's much faster. See http://crbug.com/418702.
+  windows_zip_cmd = None
+  if os.path.exists('C:\\Program Files\\7-Zip\\7z.exe'):
+    windows_zip_cmd = ['C:\\Program Files\\7-Zip\\7z.exe', 'a', '-y', '-mx1']
+
+  # On Windows we use the python zip module; on Linux and Mac, we use the zip
+  # command as it will handle links and file bits (executable).  Which is much
+  # easier then trying to do that with ZipInfo options.
+  start_time = time.clock()
+  if IsWindows() and not windows_zip_cmd:
+    print 'Creating %s' % output_file
+
+    def _Addfiles(to_zip_file, dirname, files_to_add):
+      for this_file in files_to_add:
+        archive_name = this_file
+        this_path = os.path.join(dirname, this_file)
+        if os.path.isfile(this_path):
+          # Store files named relative to the outer output_dir.
+          archive_name = this_path.replace(output_dir + os.sep, '')
+          if os.path.getsize(this_path) == 0:
+            compress_method = zipfile.ZIP_STORED
+          else:
+            compress_method = zipfile.ZIP_DEFLATED
+          to_zip_file.write(this_path, archive_name, compress_method)
+          print 'Adding %s' % archive_name
+    zip_file = zipfile.ZipFile(output_file, 'w', zipfile.ZIP_DEFLATED,
+                               allowZip64=True)
+    try:
+      os.path.walk(archive_dir, _Addfiles, zip_file)
+    finally:
+      zip_file.close()
+  else:
+    if IsMac() or IsLinux():
+      zip_cmd = ['zip', '-yr1']
+    else:
+      zip_cmd = windows_zip_cmd
+    saved_dir = os.getcwd()
+    os.chdir(os.path.dirname(archive_dir))
+    command = zip_cmd + [output_file, os.path.basename(archive_dir)]
+    result = RunCommand(command)
+    os.chdir(saved_dir)
+    if result and raise_error:
+      raise ExternalError('zip failed: %s => %s' %
+                          (str(command), result))
+  end_time = time.clock()
+  print 'Took %f seconds to create zip.' % (end_time - start_time)
+  return (archive_dir, output_file)
+
+
+def ExtractZip(filename, output_dir, verbose=True):
+  """ Extract the zip archive in the output directory.
+  """
+  MaybeMakeDirectory(output_dir)
+
+  # On Linux and Mac, we use the unzip command as it will
+  # handle links and file bits (executable), which is much
+  # easier then trying to do that with ZipInfo options.
+  #
+  # The Mac Version of unzip unfortunately does not support Zip64, whereas
+  # the python module does, so we have to fallback to the python zip module
+  # on Mac if the filesize is greater than 4GB.
+  #
+  # On Windows, try to use 7z if it is installed, otherwise fall back to python
+  # zip module and pray we don't have files larger than 512MB to unzip.
+  unzip_cmd = None
+  if ((IsMac() and os.path.getsize(filename) < 4 * 1024 * 1024 * 1024)
+      or IsLinux()):
+    unzip_cmd = ['unzip', '-o']
+  elif IsWindows() and os.path.exists('C:\\Program Files\\7-Zip\\7z.exe'):
+    unzip_cmd = ['C:\\Program Files\\7-Zip\\7z.exe', 'x', '-y']
+
+  if unzip_cmd:
+    # Make sure path is absolute before changing directories.
+    filepath = os.path.abspath(filename)
+    saved_dir = os.getcwd()
+    os.chdir(output_dir)
+    command = unzip_cmd + [filepath]
+    result = RunCommand(command)
+    os.chdir(saved_dir)
+    if result:
+      raise ExternalError('unzip failed: %s => %s' % (str(command), result))
+  else:
+    assert IsWindows() or IsMac()
+    zf = zipfile.ZipFile(filename)
+    # TODO(hinoka): This can be multiprocessed.
+    for name in zf.namelist():
+      if verbose:
+        print 'Extracting %s' % name
+      zf.extract(name, output_dir)
+      if IsMac():
+        # Restore permission bits.
+        os.chmod(os.path.join(output_dir, name),
+                 zf.getinfo(name).external_attr >> 16L)
+
+
+def WindowsPath(path):
+  """Returns a Windows mixed-style absolute path, given a Cygwin absolute path.
+
+  The version of Python in the Chromium tree uses posixpath for os.path even
+  on Windows, so we convert to a mixed Windows path (that is, a Windows path
+  that uses forward slashes instead of backslashes) manually.
+  """
+  # TODO(pamg): make this work for other drives too.
+  if path.startswith('/cygdrive/c/'):
+    return path.replace('/cygdrive/c/', 'C:/')
+  return path
+
+
+def FindUpwardParent(start_dir, *desired_list):
+  """Finds the desired object's parent, searching upward from the start_dir.
+
+  Searches within start_dir and within all its parents looking for the desired
+  directory or file, which may be given in one or more path components. Returns
+  the first directory in which the top desired path component was found, or
+  raises PathNotFound if it wasn't.
+  """
+  desired_path = os.path.join(*desired_list)
+  last_dir = ''
+  cur_dir = start_dir
+  found_path = os.path.join(cur_dir, desired_path)
+  while not os.path.exists(found_path):
+    last_dir = cur_dir
+    cur_dir = os.path.dirname(cur_dir)
+    if last_dir == cur_dir:
+      raise PathNotFound('Unable to find %s above %s' %
+                         (desired_path, start_dir))
+    found_path = os.path.join(cur_dir, desired_path)
+  # Strip the entire original desired path from the end of the one found
+  # and remove a trailing path separator, if present.
+  found_path = found_path[:len(found_path) - len(desired_path)]
+  if found_path.endswith(os.sep):
+    found_path = found_path[:len(found_path) - 1]
+  return found_path
+
+
+def FindUpward(start_dir, *desired_list):
+  """Returns a path to the desired directory or file, searching upward.
+
+  Searches within start_dir and within all its parents looking for the desired
+  directory or file, which may be given in one or more path components. Returns
+  the full path to the desired object, or raises PathNotFound if it wasn't
+  found.
+  """
+  parent = FindUpwardParent(start_dir, *desired_list)
+  return os.path.join(parent, *desired_list)
+
+
+def RunAndPrintDots(function):
+  """Starts a background thread that prints dots while the function runs."""
+
+  def Hook(*args, **kwargs):
+    event = threading.Event()
+
+    def PrintDots():
+      counter = 0
+      while not event.isSet():
+        event.wait(5)
+        sys.stdout.write('.')
+        counter = (counter + 1) % 80
+        if not counter:
+          sys.stdout.write('\n')
+        sys.stdout.flush()
+    t = threading.Thread(target=PrintDots)
+    t.start()
+    try:
+      return function(*args, **kwargs)
+    finally:
+      event.set()
+      t.join()
+  return Hook
+
+
+class RunCommandFilter(object):
+  """Class that should be subclassed to provide a filter for RunCommand."""
+  # Method could be a function
+  # pylint: disable=R0201
+
+  def FilterLine(self, a_line):
+    """Called for each line of input.  The \n is included on a_line.  Should
+    return what is to be recorded as the output for this line.  A result of
+    None suppresses the line."""
+    return a_line
+
+  def FilterDone(self, last_bits):
+    """Acts just like FilterLine, but is called with any data collected after
+    the last newline of the command."""
+    return last_bits
+
+
+class FilterCapture(RunCommandFilter):
+  """Captures the text and places it into an array."""
+  def __init__(self):
+    RunCommandFilter.__init__(self)
+    self.text = []
+
+  def FilterLine(self, line):
+    self.text.append(line.rstrip())
+
+  def FilterDone(self, text):
+    self.text.append(text)
+
+
+def RunCommand(command, parser_func=None, filter_obj=None, pipes=None,
+               print_cmd=True, timeout=None, max_time=None, **kwargs):
+  """Runs the command list, printing its output and returning its exit status.
+
+  Prints the given command (which should be a list of one or more strings),
+  then runs it and writes its stdout and stderr to the appropriate file handles.
+
+  If timeout is set, the process will be killed if output is stopped after
+  timeout seconds. If max_time is set, the process will be killed if it runs for
+  more than max_time.
+
+  If parser_func is not given, the subprocess's output is passed to stdout
+  and stderr directly.  If the func is given, each line of the subprocess's
+  stdout/stderr is passed to the func and then written to stdout.
+
+  If filter_obj is given, all output is run through the filter a line
+  at a time before it is written to stdout.
+
+  We do not currently support parsing stdout and stderr independent of
+  each other.  In previous attempts, this led to output ordering issues.
+  By merging them when either needs to be parsed, we avoid those ordering
+  issues completely.
+
+  pipes is a list of commands (also a list) that will receive the output of
+  the intial command. For example, if you want to run "python a | python b | c",
+  the "command" will be set to ['python', 'a'], while pipes will be set to
+  [['python', 'b'],['c']]
+  """
+
+  def TimedFlush(timeout, fh, kill_event):
+    """Flush fh every timeout seconds until kill_event is true."""
+    while True:
+      try:
+        fh.flush()
+      # File handle is closed, exit.
+      except ValueError:
+        break
+      # Wait for kill signal or timeout.
+      if kill_event.wait(timeout):
+        break
+
+  # TODO(all): nsylvain's CommandRunner in buildbot_slave is based on this
+  # method.  Update it when changes are introduced here.
+  def ProcessRead(readfh, writefh, parser_func=None, filter_obj=None,
+                  log_event=None):
+    writefh.flush()
+
+    # Python on Windows writes the buffer only when it reaches 4k.  Ideally
+    # we would flush a minimum of 10 seconds.  However, we only write and
+    # flush no more often than 20 seconds to avoid flooding the master with
+    # network traffic from unbuffered output.
+    kill_event = threading.Event()
+    flush_thread = threading.Thread(
+        target=TimedFlush, args=(20, writefh, kill_event))
+    flush_thread.daemon = True
+    flush_thread.start()
+
+    try:
+      in_byte = readfh.read(1)
+      in_line = cStringIO.StringIO()
+      while in_byte:
+        # Capture all characters except \r.
+        if in_byte != '\r':
+          in_line.write(in_byte)
+
+        # Write and flush on newline.
+        if in_byte == '\n':
+          if log_event:
+            log_event.set()
+          if parser_func:
+            parser_func(in_line.getvalue().strip())
+
+          if filter_obj:
+            filtered_line = filter_obj.FilterLine(in_line.getvalue())
+            if filtered_line is not None:
+              writefh.write(filtered_line)
+          else:
+            writefh.write(in_line.getvalue())
+          in_line = cStringIO.StringIO()
+        in_byte = readfh.read(1)
+
+      if log_event and in_line.getvalue():
+        log_event.set()
+
+      # Write remaining data and flush on EOF.
+      if parser_func:
+        parser_func(in_line.getvalue().strip())
+
+      if filter_obj:
+        if in_line.getvalue():
+          filtered_line = filter_obj.FilterDone(in_line.getvalue())
+          if filtered_line is not None:
+            writefh.write(filtered_line)
+      else:
+        if in_line.getvalue():
+          writefh.write(in_line.getvalue())
+    finally:
+      kill_event.set()
+      flush_thread.join()
+      writefh.flush()
+
+  pipes = pipes or []
+
+  # Print the given command (which should be a list of one or more strings).
+  if print_cmd:
+    print '\n' + subprocess.list2cmdline(command) + '\n',
+    for pipe in pipes:
+      print '     | ' + subprocess.list2cmdline(pipe) + '\n',
+
+  sys.stdout.flush()
+  sys.stderr.flush()
+
+  if not (parser_func or filter_obj or pipes or timeout or max_time):
+    # Run the command.  The stdout and stderr file handles are passed to the
+    # subprocess directly for writing.  No processing happens on the output of
+    # the subprocess.
+    proc = subprocess.Popen(command, stdout=sys.stdout, stderr=sys.stderr,
+                            bufsize=0, **kwargs)
+
+  else:
+    if not (parser_func or filter_obj):
+      filter_obj = RunCommandFilter()
+
+    # Start the initial process.
+    proc = subprocess.Popen(command, stdout=subprocess.PIPE,
+                            stderr=subprocess.STDOUT, bufsize=0, **kwargs)
+    proc_handles = [proc]
+
+    if pipes:
+      pipe_number = 0
+      for pipe in pipes:
+        pipe_number = pipe_number + 1
+        if pipe_number == len(pipes) and not (parser_func or filter_obj):
+          # The last pipe process needs to output to sys.stdout or filter
+          stdout = sys.stdout
+        else:
+          # Output to a pipe, since another pipe is on top of us.
+          stdout = subprocess.PIPE
+        pipe_proc = subprocess.Popen(pipe, stdin=proc_handles[0].stdout,
+                                     stdout=stdout, stderr=subprocess.STDOUT)
+        proc_handles.insert(0, pipe_proc)
+
+      # Allow proc to receive a SIGPIPE if the piped process exits.
+      for handle in proc_handles[1:]:
+        handle.stdout.close()
+
+    log_event = threading.Event()
+
+    # Launch and start the reader thread.
+    thread = threading.Thread(target=ProcessRead,
+                              args=(proc_handles[0].stdout, sys.stdout),
+                              kwargs={'parser_func': parser_func,
+                                      'filter_obj': filter_obj,
+                                      'log_event': log_event})
+
+    kill_lock = threading.Lock()
+
+
+    def term_then_kill(handle, initial_timeout, numtimeouts, interval):
+      def timed_check():
+        for _ in range(numtimeouts):
+          if handle.poll() is not None:
+            return True
+          time.sleep(interval)
+
+      handle.terminate()
+      time.sleep(initial_timeout)
+      timed_check()
+      if handle.poll() is None:
+        handle.kill()
+      timed_check()
+      return handle.poll() is not None
+
+
+    def kill_proc(proc_handles, message=None):
+      with kill_lock:
+        if proc_handles:
+          killed = term_then_kill(proc_handles[0], 0.1, 5, 1)
+
+          if message:
+            print >> sys.stderr, message
+
+          if not killed:
+            print >> sys.stderr, 'could not kill pid %d!' % proc_handles[0].pid
+          else:
+            print >> sys.stderr, 'program finished with exit code %d' % (
+                proc_handles[0].returncode)
+
+          # Prevent other timeouts from double-killing.
+          del proc_handles[:]
+
+    def timeout_func(timeout, proc_handles, log_event, finished_event):
+      while log_event.wait(timeout):
+        log_event.clear()
+        if finished_event.is_set():
+          return
+
+      message = ('command timed out: %d seconds without output, attempting to '
+                 'kill' % timeout)
+      kill_proc(proc_handles, message)
+
+    def maxtimeout_func(timeout, proc_handles, finished_event):
+      if not finished_event.wait(timeout):
+        message = ('command timed out: %d seconds elapsed' % timeout)
+        kill_proc(proc_handles, message)
+
+    timeout_thread = None
+    maxtimeout_thread = None
+    finished_event = threading.Event()
+
+    if timeout:
+      timeout_thread = threading.Thread(target=timeout_func,
+                                        args=(timeout, proc_handles, log_event,
+                                              finished_event))
+      timeout_thread.daemon = True
+    if max_time:
+      maxtimeout_thread = threading.Thread(target=maxtimeout_func,
+                                           args=(max_time, proc_handles,
+                                                 finished_event))
+      maxtimeout_thread.daemon = True
+
+    thread.start()
+    if timeout_thread:
+      timeout_thread.start()
+    if maxtimeout_thread:
+      maxtimeout_thread.start()
+
+    # Wait for the commands to terminate.
+    for handle in proc_handles:
+      handle.wait()
+
+    # Wake up timeout threads.
+    finished_event.set()
+    log_event.set()
+
+    # Wait for the reader thread to complete (implies EOF reached on stdout/
+    # stderr pipes).
+    thread.join()
+
+    # Check whether any of the sub commands has failed.
+    for handle in proc_handles:
+      if handle.returncode:
+        return handle.returncode
+
+  # Wait for the command to terminate.
+  proc.wait()
+  return proc.returncode
+
+
+def GetStatusOutput(command, **kwargs):
+  """Runs the command list, returning its result and output."""
+  proc = subprocess.Popen(command, stdout=subprocess.PIPE,
+                          stderr=subprocess.STDOUT, bufsize=1,
+                          **kwargs)
+  output = proc.communicate()[0]
+  result = proc.returncode
+
+  return (result, output)
+
+
+def GetCommandOutput(command):
+  """Runs the command list, returning its output.
+
+  Run the command and returns its output (stdout and stderr) as a string.
+
+  If the command exits with an error, raises ExternalError.
+  """
+  (result, output) = GetStatusOutput(command)
+  if result:
+    raise ExternalError('%s: %s' % (subprocess.list2cmdline(command), output))
+  return output
+
+
+def GetGClientCommand(platform=None):
+  """Returns the executable command name, depending on the platform.
+  """
+  if not platform:
+    platform = sys.platform
+  if platform.startswith('win'):
+    # Windows doesn't want to depend on bash.
+    return 'gclient.bat'
+  else:
+    return 'gclient'
+
+
+# Linux scripts use ssh to to move files to the archive host.
+def SshMakeDirectory(host, dest_path):
+  """Creates the entire dest_path on the remote ssh host.
+  """
+  command = ['ssh', host, 'mkdir', '-p', dest_path]
+  result = RunCommand(command)
+  if result:
+    raise ExternalError('Failed to ssh mkdir "%s" on "%s" (%s)' %
+                        (dest_path, host, result))
+
+
+def SshMoveFile(host, src_path, dest_path):
+  """Moves src_path (if it exists) to dest_path on the remote host.
+  """
+  command = ['ssh', host, 'test', '-e', src_path]
+  result = RunCommand(command)
+  if result:
+    # Nothing to do if src_path doesn't exist.
+    return result
+
+  command = ['ssh', host, 'mv', src_path, dest_path]
+  result = RunCommand(command)
+  if result:
+    raise ExternalError('Failed to ssh mv "%s" -> "%s" on "%s" (%s)' %
+                        (src_path, dest_path, host, result))
+
+
+def SshCopyFiles(srcs, host, dst):
+  """Copies the srcs file(s) to dst on the remote ssh host.
+  dst is expected to exist.
+  """
+  command = ['scp', srcs, host + ':' + dst]
+  result = RunCommand(command)
+  if result:
+    raise ExternalError('Failed to scp "%s" to "%s" (%s)' %
+                        (srcs, host + ':' + dst, result))
+
+
+def SshExtractZip(host, zipname, dst):
+  """extract the remote zip file to dst on the remote ssh host.
+  """
+  command = ['ssh', host, 'unzip', '-o', '-d', dst, zipname]
+  result = RunCommand(command)
+  if result:
+    raise ExternalError('Failed to ssh unzip -o -d "%s" "%s" on "%s" (%s)' %
+                        (dst, zipname, host, result))
+
+  # unzip will create directories with access 700, which is not often what we
+  # need. Fix the permissions for the whole archive.
+  command = ['ssh', host, 'chmod', '-R', '755', dst]
+  result = RunCommand(command)
+  if result:
+    raise ExternalError('Failed to ssh chmod -R 755 "%s" on "%s" (%s)' %
+                        (dst, host, result))
+
+
+def SshCopyTree(srctree, host, dst):
+  """Recursively copies the srctree to dst on the remote ssh host.
+  For consistency with shutil, dst is expected to not exist.
+  """
+  command = ['ssh', host, '[ -d "%s" ]' % dst]
+  result = RunCommand(command)
+  if result:
+    raise ExternalError('SshCopyTree destination directory "%s" already exists.'
+                        % host + ':' + dst)
+
+  SshMakeDirectory(host, os.path.dirname(dst))
+  command = ['scp', '-r', '-p', srctree, host + ':' + dst]
+  result = RunCommand(command)
+  if result:
+    raise ExternalError('Failed to scp "%s" to "%s" (%s)' %
+                        (srctree, host + ':' + dst, result))
+
+
+def ListMasters(cue='master.cfg', include_public=True, include_internal=True):
+  """Returns all the masters found."""
+  # Look for "internal" masters first.
+  path_internal = os.path.join(
+      BUILD_DIR, os.pardir, 'build_internal', 'masters/*/' + cue)
+  path = os.path.join(BUILD_DIR, 'masters/*/' + cue)
+  filenames = []
+  if include_public:
+    filenames += glob.glob(path)
+  if include_internal:
+    filenames += glob.glob(path_internal)
+  return [os.path.abspath(os.path.dirname(f)) for f in filenames]
+
+
+def MasterPath(mastername, include_public=True, include_internal=True):
+  path = os.path.join(BUILD_DIR, 'masters', 'master.%s' % mastername)
+  path_internal = os.path.join(
+      BUILD_DIR, os.pardir, 'build_internal', 'masters',
+      'master.%s' % mastername)
+  if include_public and os.path.isdir(path):
+    return path
+  if include_internal and os.path.isdir(path_internal):
+    return path_internal
+  raise LookupError('Path for master %s not found' % mastername)
+
+
+def ListMastersWithSlaves(include_public=True, include_internal=True):
+  masters_path = ListMasters('builders.pyl', include_public, include_internal)
+  masters_path.extend(ListMasters('slaves.cfg', include_public,
+                                  include_internal))
+  return masters_path
+
+
+def GetSlavesFromMasterPath(path, fail_hard=False):
+  builders_path = os.path.join(path, 'builders.pyl')
+  if os.path.exists(builders_path):
+    return GetSlavesFromBuildersFile(builders_path)
+  return RunSlavesCfg(os.path.join(path, 'slaves.cfg'), fail_hard=fail_hard)
+
+
+def GetAllSlaves(fail_hard=False, include_public=True, include_internal=True):
+  """Return all slave objects from masters."""
+  slaves = []
+  for master in ListMastersWithSlaves(include_public, include_internal):
+    cur_slaves = GetSlavesFromMasterPath(master, fail_hard)
+    for slave in cur_slaves:
+      slave['mastername'] = os.path.basename(master)
+    slaves.extend(cur_slaves)
+  return slaves
+
+
+def GetSlavesForHost():
+  """Get slaves for a host, defaulting to current host."""
+  hostname = os.getenv('TESTING_SLAVENAME')
+  if not hostname:
+    hostname = socket.getfqdn().split('.', 1)[0].lower()
+  return [s for s in GetAllSlaves() if s.get('hostname') == hostname]
+
+
+def GetActiveSubdir():
+  """Get current checkout's subdir, if checkout uses subdir layout."""
+  rootdir, subdir = os.path.split(os.path.dirname(BUILD_DIR))
+  if subdir != 'b' and os.path.basename(rootdir) == 'c':
+    return subdir
+
+
+def GetActiveSlavename():
+  slavename = os.getenv('TESTING_SLAVENAME')
+  if not slavename:
+    slavename = socket.getfqdn().split('.', 1)[0].lower()
+  subdir = GetActiveSubdir()
+  if subdir:
+    return '%s#%s' % (slavename, subdir)
+  return slavename
+
+
+def EntryToSlaveName(entry):
+  """Produces slave name from the slaves config dict."""
+  name = entry.get('slavename') or entry.get('hostname')
+  if 'subdir' in entry:
+    return '%s#%s' % (name, entry['subdir'])
+  return name
+
+
+def GetActiveMaster(slavename=None, default=None):
+  """Returns the name of the Active master serving the current host.
+
+  Parse all of the active masters with slaves matching the current hostname
+  and optional slavename. Returns |default| if no match found.
+  """
+  slavename = slavename or GetActiveSlavename()
+  for slave in GetAllSlaves():
+    if slavename == EntryToSlaveName(slave):
+      return slave['master']
+  return default
+
+
+@contextmanager
+def MasterEnvironment(master_dir):
+  """Context manager that enters an enviornment similar to a master's.
+
+  This involves:
+    - Modifying 'sys.path' to include paths available to the master.
+    - Changing directory (via os.chdir()) to the master's base directory.
+
+  These changes will be reverted after the context manager completes.
+
+  Args:
+    master_dir: (str) The master's base directory.
+  """
+  master_dir = os.path.abspath(master_dir)
+
+  # Setup a 'sys.path' that is adequate for loading 'slaves.cfg'.
+  old_cwd = os.getcwd()
+
+  with env.GetInfraPythonPath(master_dir=master_dir).Enter():
+    try:
+      os.chdir(master_dir)
+      yield
+    finally:
+      os.chdir(old_cwd)
+
+
+def ParsePythonCfg(cfg_filepath, fail_hard=False):
+  """Retrieves data from a python config file."""
+  if not os.path.exists(cfg_filepath):
+    return None
+
+  # Execute 'slaves.sfg' in the master path environment.
+  with MasterEnvironment(os.path.dirname(os.path.abspath(cfg_filepath))):
+    try:
+      local_vars = {}
+      execfile(os.path.join(cfg_filepath), local_vars)
+      del local_vars['__builtins__']
+      return local_vars
+    except Exception as e:
+      # pylint: disable=C0323
+      print >>sys.stderr, 'An error occurred while parsing %s: %s' % (
+          cfg_filepath, e)
+      print >>sys.stderr, traceback.format_exc()  # pylint: disable=C0323
+      if fail_hard:
+        raise
+      return {}
+
+
+def RunSlavesCfg(slaves_cfg, fail_hard=False):
+  """Runs slaves.cfg in a consistent way."""
+  slave_config = ParsePythonCfg(slaves_cfg, fail_hard=fail_hard) or {}
+  return slave_config.get('slaves', [])
+
+
+def convert_json(option, _, value, parser):
+  """Provide an OptionParser callback to unmarshal a JSON string."""
+  setattr(parser.values, option.dest, json.loads(value))
+
+
+def b64_gz_json_encode(obj):
+  """Serialize a python object into base64."""
+  # The |separators| argument is to densify the command line.
+  return base64.b64encode(zlib.compress(
+      json.dumps(obj or {}, sort_keys=True, separators=(',', ':')), 9))
+
+
+def convert_gz_json(option, _, value, parser):
+  """Provide an OptionParser callback to unmarshal a b64 gz JSON string."""
+  setattr(
+      parser.values, option.dest,
+      json.loads(zlib.decompress(base64.b64decode(value))))
+
+
+def SafeTranslate(inputstr):
+  """Convert a free form string to one that can be used in a path.
+
+  This is similar to the safeTranslate function in buildbot.
+  """
+
+  badchars_map = string.maketrans('\t !#$%&\'()*+,./:;<=>?@[\\]^{|}~',
+                                  '______________________________')
+  if isinstance(inputstr, unicode):
+    inputstr = inputstr.encode('utf8')
+  return inputstr.translate(badchars_map)
+
+
+def GetPrimaryProject(options):
+  """Returns: (str) the key of the primary project, or 'None' if none exists.
+  """
+  # The preferred way is to reference the 'primary_project' parameter.
+  result = options.build_properties.get('primary_project')
+  if result:
+    return result
+
+  # TODO(dnj): The 'primary_repo' parameter is used by some scripts to indictate
+  #     the primary project name. This is not consistently used and will be
+  #     deprecated in favor of 'primary_project' once that is rolled out.
+  result = options.build_properties.get('primary_repo')
+  if not result:
+    # The 'primary_repo' property currently contains a trailing underscore.
+    # However, this isn't an obvious thing given its name, so we'll strip it
+    # here and remove that expectation.
+    return result.strip('_')
+  return None
+
+
+def GetBuildSortKey(options, project=None):
+  """Reads a variety of sources to determine the current build revision.
+
+  NOTE: Currently, the return value does not qualify branch name. This can
+  present a problem with git numbering scheme, where numbers are only unique
+  in the context of their respective branches. When this happens, this
+  function will return a branch name as part of the sort key and its callers
+  will need to adapt their naming/querying schemes to accommodate this. Until
+  then, we will return 'None' as the branch name.
+  (e.g., refs/foo/bar@{#12345} => ("refs/foo/bar", 12345)
+
+  Args:
+    options: Command-line options structure
+    project: (str/None) If not None, the project to get the build sort key
+        for. Otherwise, the build-wide sort key will be used.
+  Returns: (branch, value) The qualified sortkey value
+    branch: (str/None) The name of the branch, or 'None' if there is no branch
+        context. Currently this always returns 'None'.
+    value: (int) The iteration value within the specified branch
+  Raises: (NoIdentifiedRevision) if no revision could be identified from the
+      supplied options.
+  """
+  # Is there a commit position for this build key?
+  try:
+    return GetCommitPosition(options, project=project)
+  except NoIdentifiedRevision:
+    pass
+
+  # Nope; derive the sort key from the 'got_[*_]revision' build properties. Note
+  # that this could be a Git commit (post flag day).
+  if project:
+    revision_key = 'got_%s_revision' % (project,)
+  else:
+    revision_key = 'got_revision'
+  revision = options.build_properties.get(revision_key)
+  if revision and not IsGitCommit(revision):
+    return None, int(revision)
+  raise NoIdentifiedRevision("Unable to identify revision for revision key "
+                             "[%s]" % (revision_key,))
+
+
+def GetGitCommit(options, project=None):
+  """Returns the 'git' commit hash for the specified repository
+
+  This function uses environmental options to identify the 'git' commit hash
+  for the specified repository.
+
+  Args:
+    options: Command-line options structure
+    project: (str/None) The project key to use. If None, use the topmost
+        repository identification properties.
+  Raises: (NoIdentifiedRevision) if no git commit could be identified from the
+      supplied options.
+  """
+  if project:
+    git_commit_key = 'got_%s_revision_git' % (project,)
+  else:
+    git_commit_key = 'got_revision_git'
+  commit = options.build_properties.get(git_commit_key)
+  if commit:
+    return commit
+
+  # Is 'got_[_*]revision' itself is the Git commit?
+  if project:
+    commit_key = 'got_%s_revision' % (project,)
+  else:
+    commit_key = 'got_revision'
+  commit = options.build_properties.get(commit_key)
+  if commit and IsGitCommit(commit):
+    return commit
+  raise NoIdentifiedRevision("Unable to identify commit for commit key: %s" % (
+                           (git_commit_key, commit_key),))
+
+
+def GetSortableUploadPathForSortKey(branch, value, delimiter=None):
+  """Returns: (str) the canonical sort key path constructed from a sort key.
+
+  Returns a canonical sort key path for a sort key. The result will be one of
+  the following forms:
+  - (Without Branch or With Branch=='refs/heads/master'): <value> (e.g., 12345)
+  - (With non-Master Branch): <branch-path>-<value> (e.g.,
+        "refs_my-branch-12345")
+
+  When a 'branch' is supplied, it is converted to a path-suitable form. This
+  conversion replaces undesirable characters ('/') with underscores.
+
+  Note that when parsing the upload path, 'rsplit' should be used to isolate the
+  commit position value, as the branch path may have instances of the delimiter
+  in it.
+
+  See 'GetBuildSortKey' for more information about sort keys.
+
+  Args:
+    branch: (str/None) The sort key branch, or 'None' if there is no associated
+        branch.
+    value: (int) The sort key value.
+    delimiter: (str) The delimiter to insert in between <branch-path> and
+        <value> when constructing the branch-inclusive form. If omitted
+        (default), a hyphen ('-') will be used.
+  """
+  if branch and branch != 'refs/heads/master':
+    delimiter = delimiter or '-'
+    branch = branch.replace('/', '_')
+    return '%s%s%s' % (branch, delimiter, value)
+  return str(value)
+
+
+def ParseCommitPosition(value):
+  """Returns: The (branch, value) parsed from a commit position string.
+
+  Args:
+    value: (str) The value to parse.
+  Raises:
+    ValueError: If a commit position could not be parsed from 'value'.
+  """
+  match = COMMIT_POSITION_RE.match(value)
+  if not match:
+    raise ValueError("Failed to parse commit position from '%s'" % (value,))
+  return match.group(1), int(match.group(2))
+
+
+def BuildCommitPosition(branch, value):
+  """Returns: A constructed commit position.
+
+  An example commit position for branch 'refs/heads/master' value '12345' is:
+  refs/heads/master@{#12345}
+
+  This value can be parsed via 'ParseCommitPosition'.
+
+  Args:
+    branch: (str) The name of the commit position branch
+    value: (int): The commit position number.
+  """
+  return '%s@{#%s}' % (branch, value)
+
+
+def GetCommitPosition(options, project=None):
+  """Returns: (branch, value) The parsed commit position from build options.
+
+  Returns the parsed commit position from the build options. This is identified
+  by examining the 'got_revision_cp' (or 'got_REPO_revision_cp', if 'project' is
+  specified) keys.
+
+  Args:
+    options: Command-line options structure
+    project: (str/None) If not None, the project to get the build sort key
+        for. Otherwise, the build-wide sort key will be used.
+  Returns: (branch, value) The qualified commit position value
+  Raises:
+    NoIdentifiedRevision: if no revision could be identified from the
+        supplied options.
+    ValueError: If the supplied commit position failed to parse successfully.
+  """
+  if project:
+    key = 'got_%s_revision_cp' % (project,)
+  else:
+    key = 'got_revision_cp'
+  cp = options.build_properties.get(key)
+  if not cp:
+    raise NoIdentifiedRevision("Unable to identify the commit position; the "
+                               "build property is missing: %s" % (key,))
+  return ParseCommitPosition(cp)
+
+
+def AddPropertiesOptions(option_parser):
+  """Registers command line options for parsing build and factory properties.
+
+  After parsing, the options object will have the 'build_properties' and
+  'factory_properties' attributes. The corresponding values will be python
+  dictionaries containing the properties. If the options are not given on
+  the command line, the dictionaries will be empty.
+
+  Args:
+    option_parser: An optparse.OptionParser to register command line options
+                   for build and factory properties.
+  """
+  option_parser.add_option('--build-properties', action='callback',
+                           callback=convert_json, type='string',
+                           nargs=1, default={},
+                           help='build properties in JSON format')
+  option_parser.add_option('--factory-properties', action='callback',
+                           callback=convert_json, type='string',
+                           nargs=1, default={},
+                           help='factory properties in JSON format')
+
+
+def AddThirdPartyLibToPath(lib, override=False):
+  """Adds the specified dir in build/third_party to sys.path.
+
+  Setting 'override' to true will place the directory in the beginning of
+  sys.path, useful for overriding previously set packages.
+
+  NOTE: We would like to deprecate this method, as it allows (encourages?)
+      scripts to define their own one-off Python path sequences, creating a
+      difficult-to-manage state where different scripts and libraries have
+      different path expectations. Please don't use this method if possible;
+      it preferred to augment 'common.env' instead.
+  """
+  libpath = os.path.abspath(os.path.join(BUILD_DIR, 'third_party', lib))
+  if override:
+    sys.path.insert(0, libpath)
+  else:
+    sys.path.append(libpath)
+
+
+def GetLKGR():
+  """Connect to chromium LKGR server and get LKGR revision.
+
+  On success, returns the LKGR and 'ok'. On error, returns None and the text of
+  the error message.
+  """
+
+  try:
+    conn = urllib.urlopen('https://chromium-status.appspot.com/lkgr')
+  except IOError:
+    return (None, 'Error connecting to LKGR server! Is your internet '
+            'connection working properly?')
+  try:
+    rev = int('\n'.join(conn.readlines()))
+  except IOError:
+    return (None, 'Error connecting to LKGR server! Is your internet '
+            'connection working properly?')
+  except ValueError:
+    return None, 'LKGR server returned malformed data! Aborting...'
+  finally:
+    conn.close()
+
+  return rev, 'ok'
+
+
+def AbsoluteCanonicalPath(*path):
+  """Return the most canonical path Python can provide."""
+
+  file_path = os.path.join(*path)
+  return os.path.realpath(os.path.abspath(os.path.expanduser(file_path)))
+
+
+def IsolatedImportFromPath(path, extra_paths=None):
+  dir_path, module_file = os.path.split(path)
+  module_file = os.path.splitext(module_file)[0]
+
+  saved = sys.path
+  sys.path = [dir_path] + (extra_paths or [])
+  try:
+    return __import__(module_file)
+  except ImportError:
+    pass
+  finally:
+    sys.path = saved
+
+
+@contextmanager
+def MultiPool(processes):
+  """Manages a multiprocessing.Pool making sure to close the pool when done.
+
+  This will also call pool.terminate() when an exception is raised (and
+  re-raised the exception to the calling procedure can handle it).
+  """
+  try:
+    pool = multiprocessing.Pool(processes=processes)
+    yield pool
+    pool.close()
+  except:
+    pool.terminate()
+    raise
+  finally:
+    pool.join()
+
+
+def ReadJsonAsUtf8(filename=None, text=None):
+  """Read a json file or string and output a dict.
+
+  This function is different from json.load and json.loads in that it
+  returns utf8-encoded string for keys and values instead of unicode.
+
+  Args:
+  filename: path of a file to parse
+  text: json string to parse
+
+  If both 'filename' and 'text' are provided, 'filename' is used.
+  """
+  def _decode_list(data):
+    rv = []
+    for item in data:
+      if isinstance(item, unicode):
+        item = item.encode('utf-8')
+      elif isinstance(item, list):
+        item = _decode_list(item)
+      elif isinstance(item, dict):
+        item = _decode_dict(item)
+      rv.append(item)
+    return rv
+
+  def _decode_dict(data):
+    rv = {}
+    for key, value in data.iteritems():
+      if isinstance(key, unicode):
+        key = key.encode('utf-8')
+      if isinstance(value, unicode):
+        value = value.encode('utf-8')
+      elif isinstance(value, list):
+        value = _decode_list(value)
+      elif isinstance(value, dict):
+        value = _decode_dict(value)
+      rv[key] = value
+    return rv
+
+  if filename:
+    with open(filename, 'rb') as f:
+      return json.load(f, object_hook=_decode_dict)
+  if text:
+    return json.loads(text, object_hook=_decode_dict)
+
+
+def GetMasterDevParameters(filename='master_cfg_params.json'):
+  """Look for master development parameter files in the master directory.
+
+  Return the parsed content if the file exists, as a dictionary.
+  Every string value in the dictionary is utf8-encoded str.
+
+  If the file is not found, returns an empty dict. This is on purpose, to
+  make the file optional.
+  """
+  if os.path.isfile(filename):
+    return ReadJsonAsUtf8(filename=filename)
+  return {}
+
+
+def FileExclusions():
+  all_platforms = ['.landmines', 'obj', 'gen', '.ninja_deps', '.ninja_log']
+  # Skip files that the testers don't care about. Mostly directories.
+  if IsWindows():
+    # Remove obj or lib dir entries
+    return all_platforms + ['cfinstaller_archive', 'lib', 'installer_archive']
+  if IsMac():
+    return all_platforms + [
+      # We don't need the arm bits v8 builds.
+      'd8_arm', 'v8_shell_arm',
+      # pdfsqueeze is a build helper, no need to copy it to testers.
+      'pdfsqueeze',
+      # We copy the framework into the app bundle, we don't need the second
+      # copy outside the app.
+      # TODO(mark): Since r28431, the copy in the build directory is actually
+      # used by tests.  Putting two copies in the .zip isn't great, so maybe
+      # we can find another workaround.
+      # 'Chromium Framework.framework',
+      # 'Google Chrome Framework.framework',
+      # We copy the Helper into the app bundle, we don't need the second
+      # copy outside the app.
+      'Chromium Helper.app',
+      'Google Chrome Helper.app',
+      'App Shim Socket',
+      '.deps', 'obj.host', 'obj.target', 'lib'
+    ]
+  if IsLinux():
+    return all_platforms + [
+      # intermediate build directories (full of .o, .d, etc.).
+      'appcache', 'glue', 'lib.host', 'obj.host',
+      'obj.target', 'src', '.deps',
+      # scons build cruft
+      '.sconsign.dblite',
+      # build helper, not needed on testers
+      'mksnapshot',
+    ]
+
+  return all_platforms
+
+
+def DatabaseSetup(buildmaster_config, require_dbconfig=False):
+  """Read database credentials in the master directory."""
+  if os.path.isfile('.dbconfig'):
+    values = {}
+    execfile('.dbconfig', values)
+    if 'password' not in values:
+      raise Exception('could not get db password')
+
+    buildmaster_config['db_url'] = 'postgresql://%s:%s@%s/%s' % (
+        values['username'], values['password'],
+        values.get('hostname', 'localhost'), values['dbname'])
+  else:
+    assert not require_dbconfig
+
+
+def ReadBuildersFile(builders_path):
+  with open(builders_path) as fp:
+    contents = fp.read()
+  return ParseBuildersFileContents(builders_path, contents)
+
+
+def ParseBuildersFileContents(path, contents):
+  builders = ast.literal_eval(contents)
+
+  # Set some additional derived fields that are derived from the
+  # file's location in the filesystem.
+  basedir = os.path.dirname(os.path.abspath(path))
+  master_dirname = os.path.basename(basedir)
+  master_name_comps = master_dirname.split('.')[1:]
+  buildbot_path =  '.'.join(master_name_comps)
+  master_classname =  ''.join(c[0].upper() + c[1:] for c in master_name_comps)
+  builders['master_dirname'] = master_dirname
+  builders.setdefault('master_classname', master_classname)
+  builders.setdefault('buildbot_url',
+                      'https://build.chromium.org/p/%s/' % buildbot_path)
+
+  builders.setdefault('buildbucket_bucket', None)
+  builders.setdefault('service_account_file', None)
+
+  # The _str fields are printable representations of Python values:
+  # if builders['foo'] == "hello", then builders['foo_str'] == "'hello'".
+  # This allows them to be read back in by Python scripts properly.
+  builders['buildbucket_bucket_str'] = repr(builders['buildbucket_bucket'])
+  builders['service_account_file_str'] = repr(builders['service_account_file'])
+
+  return builders
+
+
+def GetSlavesFromBuildersFile(builders_path):
+  """Read builders_path and return a list of slave dicts."""
+  builders = ReadBuildersFile(builders_path)
+  return GetSlavesFromBuilders(builders)
+
+
+def GetSlavesFromBuilders(builders):
+  """Returns a list of slave dicts derived from the builders dict."""
+  builders_in_pool = {}
+
+  # builders.pyl contains a list of builders -> slave_pools
+  # and a list of slave_pools -> slaves.
+  # We require that each slave is in a single pool, but each slave
+  # may have multiple builders, so we need to build up the list of
+  # builders each slave pool supports.
+  for builder_name, builder_vals in builders['builders'].items():
+    pool_names = builder_vals['slave_pools']
+    for pool_name in pool_names:
+     if pool_name not in builders_in_pool:
+       builders_in_pool[pool_name] = set()
+     pool_data = builders['slave_pools'][pool_name]
+     for slave in pool_data['slaves']:
+       builders_in_pool[pool_name].add(builder_name)
+
+  # Now we can generate the list of slaves using the above lookup table.
+  slaves = []
+  for pool_name, pool_data in builders['slave_pools'].items():
+    slave_data = pool_data['slave_data']
+    builder_names = sorted(builders_in_pool[pool_name])
+    for slave in pool_data['slaves']:
+      slaves.append({
+          'hostname': slave,
+          'builder_name': builder_names,
+          'master': builders['master_classname'],
+          'os': slave_data['os'],
+          'version': slave_data['version'],
+          'bits': slave_data['bits'],
+      })
+
+  return slaves
+
+def GetSlaveNamesForBuilder(builders, builder_name):
+  """Returns a list of slave hostnames for the given builder name."""
+  slaves = []
+  pool_names = builders['builders'][builder_name]['slave_pools']
+  for pool_name in pool_names:
+    slaves.extend(builders['slave_pools'][pool_name]['slaves'])
+  return slaves