build/toolchain/gcc_link_wrapper.py

#!/usr/bin/env python
# Copyright 2015 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.

"""Runs a linking command and optionally a strip command.

This script exists to avoid using complex shell commands in
gcc_toolchain.gni's tool("link"), in case the host running the compiler
does not have a POSIX-like shell (e.g. Windows).
"""

import argparse
import os
import subprocess
import sys

import wrapper_utils


# When running on a Windows host and using a toolchain whose tools are
# actually wrapper scripts (i.e. .bat files on Windows) rather than binary
# executables, the "command" to run has to be prefixed with this magic.
# The GN toolchain definitions take care of that for when GN/Ninja is
# running the tool directly.  When that command is passed in to this
# script, it appears as a unitary string but needs to be split up so that
# just 'cmd' is the actual command given to Python's subprocess module.
BAT_PREFIX = 'cmd /c call '

def CommandToRun(command):
  if command[0].startswith(BAT_PREFIX):
    command = command[0].split(None, 3) + command[1:]
  return command


def main():
  parser = argparse.ArgumentParser(description=__doc__)
  parser.add_argument('--strip',
                      help='The strip binary to run',
                      metavar='PATH')
  parser.add_argument('--unstripped-file',
                      help='Executable file produced by linking command',
                      metavar='FILE')
  parser.add_argument('--map-file',
                      help=('Use --Wl,-Map to generate a map file. Will be '
                            'gzipped if extension ends with .gz'),
                      metavar='FILE')
  parser.add_argument('--dwp', help=('The dwp binary to run'), metavar='FILE')
  parser.add_argument('--output',
                      required=True,
                      help='Final output executable file',
                      metavar='FILE')
  parser.add_argument('command', nargs='+',
                      help='Linking command')
  args = parser.parse_args()

  # Work-around for gold being slow-by-default. http://crbug.com/632230
  fast_env = dict(os.environ)
  fast_env['LC_ALL'] = 'C'
  result = wrapper_utils.RunLinkWithOptionalMapFile(args.command, env=fast_env,
                                                    map_file=args.map_file)
  if result != 0:
    return result

  # If dwp is set, then package debug info for this exe.
  dwp_proc = None
  if args.dwp:
    exe_file = args.output
    if args.unstripped_file:
      exe_file = args.unstripped_file
    # Suppress output here because it doesn't seem to be useful. The most
    # common error is a segfault, which will happen if files are missing.
    with open(os.devnull, "w") as devnull:
      dwp_proc = subprocess.Popen(wrapper_utils.CommandToRun(
          [args.dwp, '-e', exe_file, '-o', exe_file + '.dwp']),
                                  stdout=devnull,
                                  stderr=subprocess.STDOUT)

  # Finally, strip the linked executable (if desired).
  if args.strip:
    result = subprocess.call(
        CommandToRun([args.strip, '-o', args.output, args.unstripped_file]))

  if dwp_proc:
    dwp_result = dwp_proc.wait()
    if dwp_result != 0:
      sys.stderr.write('dwp failed with error code {}\n'.format(dwp_result))
      return dwp_result

  return result


if __name__ == "__main__":
  sys.exit(main())