gcc_link_wrapper.py

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#!/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())