text: #!/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 'ld -shared' and generates a .TOC file that's untouched when unchanged.
  
  This script exists to avoid using complex shell commands in
  gcc_toolchain.gni's tool("solink"), 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
  
  
  def CollectSONAME(args):
    """Replaces: readelf -d $sofile | grep SONAME"""
    toc = ''
    readelf = subprocess.Popen(wrapper_utils.CommandToRun(
        [args.readelf, '-d', args.sofile]), stdout=subprocess.PIPE,
        bufsize=-1, universal_newlines=True)
    for line in readelf.stdout:
      if 'SONAME' in line:
        toc += line
    return readelf.wait(), toc
  
  
  def CollectDynSym(args):
    """Replaces: nm --format=posix -g -D $sofile | cut -f1-2 -d' '"""
    toc = ''
    nm = subprocess.Popen(wrapper_utils.CommandToRun([
        args.nm, '--format=posix', '-g', '-D', args.sofile]),
        stdout=subprocess.PIPE, bufsize=-1, universal_newlines=True)
    for line in nm.stdout:
      toc += ' '.join(line.split(' ', 2)[:2]) + '\n'
    return nm.wait(), toc
  
  
  def CollectTOC(args):
    result, toc = CollectSONAME(args)
    if result == 0:
      result, dynsym = CollectDynSym(args)
      toc += dynsym
    return result, toc
  
  
  def UpdateTOC(tocfile, toc):
    if os.path.exists(tocfile):
      old_toc = open(tocfile, 'r').read()
    else:
      old_toc = None
    if toc != old_toc:
      open(tocfile, 'w').write(toc)
  
  
  def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--readelf',
                        required=True,
                        help='The readelf binary to run',
                        metavar='PATH')
    parser.add_argument('--nm',
                        required=True,
                        help='The nm binary to run',
                        metavar='PATH')
    parser.add_argument('--strip',
                        help='The strip binary to run',
                        metavar='PATH')
    parser.add_argument('--sofile',
                        required=True,
                        help='Shared object file produced by linking command',
                        metavar='FILE')
    parser.add_argument('--tocfile',
                        required=True,
                        help='Output table-of-contents file',
                        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('--output',
                        required=True,
                        help='Final output shared object file',
                        metavar='FILE')
    parser.add_argument('--resource-whitelist',
                        help='Merge all resource whitelists into a single file.',
                        metavar='PATH')
    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'
  
    if args.resource_whitelist:
      whitelist_candidates = wrapper_utils.ResolveRspLinks(args.command)
      wrapper_utils.CombineResourceWhitelists(
          whitelist_candidates, args.resource_whitelist)
  
    # First, run the actual link.
    command = wrapper_utils.CommandToRun(args.command)
    result = wrapper_utils.RunLinkWithOptionalMapFile(command, env=fast_env,
                                                      map_file=args.map_file)
  
    if result != 0:
      return result
  
    # Next, generate the contents of the TOC file.
    result, toc = CollectTOC(args)
    if result != 0:
      return result
  
    # If there is an existing TOC file with identical contents, leave it alone.
    # Otherwise, write out the TOC file.
    UpdateTOC(args.tocfile, toc)
  
    # Finally, strip the linked shared object file (if desired).
    if args.strip:
      result = subprocess.call(wrapper_utils.CommandToRun(
          [args.strip, '--strip-unneeded', '-o', args.output, args.sofile]))
  
    return result
  
  
  if __name__ == "__main__":
    sys.exit(main())
  