client/goma-make

#!/usr/bin/python
#
# Copyright 2012 The Goma Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""A thin wrapper of make command for Chromium OS build.

Unfortunately, there are several packages with which we cannot specify
-j option. For such packages, we modify PATH environment variable not
to use goma.
"""

import os
import sys


_DEFAULT_BLACKLIST = [
    '/dev-libs/nss',  # make -j fails
    '/app-crypt/nss',  # make -j fails
    '/dev-libs/m17n-lib',  # make -j fails
    '/sys-fs/mtools',  # make -j fails
    '/dev-java/icedtea',  # make -j fails
    '/dev-libs/openssl',  # Makefile force -j1
    ]


def ParseBlacklistContents(contents):
  """Parses blacklist file contents and returns a blacklised directories.

  Args:
    contents: contents in a blacklist file.

  Returns:
    a list of blacklisted directories.
  """
  blacklist = [x.strip() for x in contents.splitlines()]
  return [x for x in blacklist if x]


def GetBlacklist():
  """Returns list of portage package names to blacklist.

  If non-empty $GOMACC_BLACKLIST is set, we use its file contents in the file
  specified by $GOMACC_BLACKLIST instead of the default one.
  If $GOMACC_BLACKLIST is an empty string, we use _DEFAULT_BLACKLIST.
  The blacklist contents should be list of directories like:
  /dev-libs/nss
  /sys-fs/mtools

  Note that empty line is just ignored.

  Returns:
    a list of blacklisted directories.
  """
  blacklist_file = os.getenv('GOMACC_BLACKLIST')
  if not blacklist_file:
    return _DEFAULT_BLACKLIST
  return ParseBlacklistContents(open(blacklist_file).read())


def IsBlacklisted(path, blacklist):
  """Determine whether a path belongs to some backlisted package.

  Args:
    path: path of a portage package

  Returns:
    True if the portage package has been blacklisted.
  """
  for exemption_path in blacklist:
    if path.find(exemption_path) != -1:
      return True
  return False


def RemoveGomaFromPath():
  """Remove the goma directory from the search path.

  This will force a non-goma build, as needed for blacklisted packages.
  """
  if not os.environ.get('GOMA_DIR'):
    return
  goma_dir = os.getenv('GOMA_DIR')
  paths = os.getenv('PATH').split(os.pathsep)
  paths = [path for path in paths if not path.startswith(goma_dir)]
  os.putenv('PATH', os.pathsep.join(paths))


def RemoveParallelBuildArguments(args):
  """Remove parallel-build related arguments.
  This avoids passing unreasonably-high values into non-goma builds.

  Args:
    args: the arguments list to modify.
  """

  # This processing assumes simple '-j ###' or '-j###' formatted arguments.
  # More complex combinations (e.g. '-vj10') will be ignored entirely.
  parallel_args = ['-j']

  for idx, arg in enumerate(args):
    if arg == None:
      pass  # Already marked this element for removal
    elif arg in parallel_args:  # '-j ###' format
      args[idx + 0] = None
      if idx + 1 < len(args):
        args[idx + 1] = None
    elif arg[0:2] in parallel_args:  # '-j###' format
      args[idx + 0] = None

  args[:] = filter(lambda x: x != None, args)
  return args


def main():
  args = ['/usr/bin/make']
  args.extend(sys.argv[1:])
  blacklist = GetBlacklist()
  # Regardless of with/without goma, make is limited to under certain
  # load average.
  args[1:1] = ['-l10']
  if os.getenv('MAKELEVEL'):
    # In a sub-make, do not modify the flags.
    pass
  elif IsBlacklisted(os.getcwd(), blacklist) or os.getuid() == 0:
    # A root user cannot talk to goma.
    RemoveGomaFromPath()
    RemoveParallelBuildArguments(args)
    if os.environ.get('GOMA_DIR'):
      del os.environ['GOMA_DIR']
    if os.environ.get('GOMACC_PATH'):
      del os.environ['GOMACC_PATH']
  else:
    # Insert default flags at the beginning of the argument list.
    # These will be overridden by any user-supplied options.
    RemoveGomaFromPath()
    if os.environ.get('GOMA_DIR'):
      os.environ['GOMACC_PATH'] = os.path.join(os.environ['GOMA_DIR'], 'gomacc')
      args[1:1] = ['-j100']

  os.execv(args[0], args)


if __name__ == '__main__':
  main()