xref: /aosp_15_r20/external/cronet/build/toolchain/gcc_solink_wrapper.py (revision 6777b5387eb2ff775bb5750e3f5d96f37fb7352b) 
1#!/usr/bin/env python3
2# Copyright 2015 The Chromium Authors
3# Use of this source code is governed by a BSD-style license that can be
4# found in the LICENSE file.
5
6"""Runs 'ld -shared' and generates a .TOC file that's untouched when unchanged.
7
8This script exists to avoid using complex shell commands in
9gcc_toolchain.gni's tool("solink"), in case the host running the compiler
10does not have a POSIX-like shell (e.g. Windows).
11"""
12
13import argparse
14import os
15import shlex
16import subprocess
17import sys
18
19import wrapper_utils
20
21
22def CollectSONAME(args):
23  """Replaces: readelf -d $sofile | grep SONAME"""
24  # TODO(crbug.com/1259067): Come up with a way to get this info without having
25  # to bundle readelf in the toolchain package.
26  toc = ''
27  readelf = subprocess.Popen(wrapper_utils.CommandToRun(
28      [args.readelf, '-d', args.sofile]),
29                             stdout=subprocess.PIPE,
30                             bufsize=-1,
31                             universal_newlines=True)
32  for line in readelf.stdout:
33    if 'SONAME' in line:
34      toc += line
35  return readelf.wait(), toc
36
37
38def CollectDynSym(args):
39  """Replaces: nm --format=posix -g -D -p $sofile | cut -f1-2 -d' '"""
40  toc = ''
41  nm = subprocess.Popen(wrapper_utils.CommandToRun(
42      [args.nm, '--format=posix', '-g', '-D', '-p', args.sofile]),
43                        stdout=subprocess.PIPE,
44                        bufsize=-1,
45                        universal_newlines=True)
46  for line in nm.stdout:
47    toc += ' '.join(line.split(' ', 2)[:2]) + '\n'
48  return nm.wait(), toc
49
50
51def CollectTOC(args):
52  result, toc = CollectSONAME(args)
53  if result == 0:
54    result, dynsym = CollectDynSym(args)
55    toc += dynsym
56  return result, toc
57
58
59def UpdateTOC(tocfile, toc):
60  if os.path.exists(tocfile):
61    old_toc = open(tocfile, 'r').read()
62  else:
63    old_toc = None
64  if toc != old_toc:
65    open(tocfile, 'w').write(toc)
66
67
68def CollectInputs(out, args):
69  for x in args:
70    if x.startswith('@'):
71      with open(x[1:]) as rsp:
72        CollectInputs(out, shlex.split(rsp.read()))
73    elif not x.startswith('-') and (x.endswith('.o') or x.endswith('.a')):
74      out.write(x)
75      out.write('\n')
76
77
78def InterceptFlag(flag, command):
79  ret = flag in command
80  if ret:
81    command.remove(flag)
82  return ret
83
84
85def SafeDelete(path):
86  try:
87    os.unlink(path)
88  except OSError:
89    pass
90
91
92def main():
93  parser = argparse.ArgumentParser(description=__doc__)
94  parser.add_argument('--readelf',
95                      required=True,
96                      help='The readelf binary to run',
97                      metavar='PATH')
98  parser.add_argument('--nm',
99                      required=True,
100                      help='The nm binary to run',
101                      metavar='PATH')
102  parser.add_argument('--strip',
103                      help='The strip binary to run',
104                      metavar='PATH')
105  parser.add_argument('--dwp', help='The dwp binary to run', metavar='PATH')
106  parser.add_argument('--sofile',
107                      required=True,
108                      help='Shared object file produced by linking command',
109                      metavar='FILE')
110  parser.add_argument('--tocfile',
111                      required=True,
112                      help='Output table-of-contents file',
113                      metavar='FILE')
114  parser.add_argument('--map-file',
115                      help=('Use --Wl,-Map to generate a map file. Will be '
116                            'gzipped if extension ends with .gz'),
117                      metavar='FILE')
118  parser.add_argument('--output',
119                      required=True,
120                      help='Final output shared object file',
121                      metavar='FILE')
122  parser.add_argument('command', nargs='+',
123                      help='Linking command')
124  args = parser.parse_args()
125
126  # Work-around for gold being slow-by-default. http://crbug.com/632230
127  fast_env = dict(os.environ)
128  fast_env['LC_ALL'] = 'C'
129
130  # Extract flags passed through ldflags but meant for this script.
131  # https://crbug.com/954311 tracks finding a better way to plumb these.
132  partitioned_library = InterceptFlag('--partitioned-library', args.command)
133  collect_inputs_only = InterceptFlag('--collect-inputs-only', args.command)
134
135  # Partitioned .so libraries are used only for splitting apart in a subsequent
136  # step.
137  #
138  # - The TOC file optimization isn't useful, because the partition libraries
139  #   must always be re-extracted if the combined library changes (and nothing
140  #   should be depending on the combined library's dynamic symbol table).
141  # - Stripping isn't necessary, because the combined library is not used in
142  #   production or published.
143  #
144  # Both of these operations could still be done, they're needless work, and
145  # tools would need to be updated to handle and/or not complain about
146  # partitioned libraries. Instead, to keep Ninja happy, simply create dummy
147  # files for the TOC and stripped lib.
148  if collect_inputs_only or partitioned_library:
149    open(args.output, 'w').close()
150    open(args.tocfile, 'w').close()
151
152  # Instead of linking, records all inputs to a file. This is used by
153  # enable_resource_allowlist_generation in order to avoid needing to
154  # link (which is slow) to build the resources allowlist.
155  if collect_inputs_only:
156    if args.map_file:
157      open(args.map_file, 'w').close()
158    if args.dwp:
159      open(args.sofile + '.dwp', 'w').close()
160
161    with open(args.sofile, 'w') as f:
162      CollectInputs(f, args.command)
163    return 0
164
165  # First, run the actual link.
166  command = wrapper_utils.CommandToRun(args.command)
167  result = wrapper_utils.RunLinkWithOptionalMapFile(command,
168                                                    env=fast_env,
169                                                    map_file=args.map_file)
170
171  if result != 0:
172    return result
173
174  # If dwp is set, then package debug info for this SO.
175  dwp_proc = None
176  if args.dwp:
177    # Explicit delete to account for symlinks (when toggling between
178    # debug/release).
179    SafeDelete(args.sofile + '.dwp')
180    # Suppress warnings about duplicate CU entries (https://crbug.com/1264130)
181    dwp_proc = subprocess.Popen(wrapper_utils.CommandToRun(
182        [args.dwp, '-e', args.sofile, '-o', args.sofile + '.dwp']),
183                                stderr=subprocess.DEVNULL)
184
185  if not partitioned_library:
186    # Next, generate the contents of the TOC file.
187    result, toc = CollectTOC(args)
188    if result != 0:
189      return result
190
191    # If there is an existing TOC file with identical contents, leave it alone.
192    # Otherwise, write out the TOC file.
193    UpdateTOC(args.tocfile, toc)
194
195    # Finally, strip the linked shared object file (if desired).
196    if args.strip:
197      result = subprocess.call(
198          wrapper_utils.CommandToRun(
199              [args.strip, '-o', args.output, args.sofile]))
200
201  if dwp_proc:
202    dwp_result = dwp_proc.wait()
203    if dwp_result != 0:
204      sys.stderr.write('dwp failed with error code {}\n'.format(dwp_result))
205      return dwp_result
206
207  return result
208
209
210if __name__ == "__main__":
211  sys.exit(main())
212