#!/usr/bin/env python3
# Copyright 2015 The Chromium Authors
# 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 shlex
import subprocess
import sys
import wrapper_utils
def CollectSONAME(args):
"""Replaces: readelf -d $sofile | grep SONAME"""
# TODO(crbug.com/40797404): Come up with a way to get this info without having
# to bundle readelf in the toolchain package.
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 -p $sofile | cut -f1-2 -d' '"""
toc = ''
nm = subprocess.Popen(wrapper_utils.CommandToRun(
[args.nm, '--format=posix', '-g', '-D', '-p', 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 CollectInputs(out, args):
for x in args:
if x.startswith('@'):
with open(x[1:]) as rsp:
CollectInputs(out, shlex.split(rsp.read()))
elif not x.startswith('-') and (x.endswith('.o') or x.endswith('.a')):
out.write(x)
out.write('\n')
def InterceptFlag(flag, command):
ret = flag in command
if ret:
command.remove(flag)
return ret
def SafeDelete(path):
try:
os.unlink(path)
except OSError:
pass
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('--dwp', help='The dwp 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('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'
# Extract flags passed through ldflags but meant for this script.
# https://crbug.com/954311 tracks finding a better way to plumb these.
partitioned_library = InterceptFlag('--partitioned-library', args.command)
collect_inputs_only = InterceptFlag('--collect-inputs-only', args.command)
# Partitioned .so libraries are used only for splitting apart in a subsequent
# step.
#
# - The TOC file optimization isn't useful, because the partition libraries
# must always be re-extracted if the combined library changes (and nothing
# should be depending on the combined library's dynamic symbol table).
# - Stripping isn't necessary, because the combined library is not used in
# production or published.
#
# Both of these operations could still be done, they're needless work, and
# tools would need to be updated to handle and/or not complain about
# partitioned libraries. Instead, to keep Ninja happy, simply create dummy
# files for the TOC and stripped lib.
if collect_inputs_only or partitioned_library:
open(args.output, 'w').close()
open(args.tocfile, 'w').close()
# Instead of linking, records all inputs to a file. This is used by
# enable_resource_allowlist_generation in order to avoid needing to
# link (which is slow) to build the resources allowlist.
if collect_inputs_only:
if args.map_file:
open(args.map_file, 'w').close()
if args.dwp:
open(args.sofile + '.dwp', 'w').close()
with open(args.sofile, 'w') as f:
CollectInputs(f, args.command)
return 0
# 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
# If dwp is set, then package debug info for this SO.
dwp_proc = None
if args.dwp:
# Explicit delete to account for symlinks (when toggling between
# debug/release).
SafeDelete(args.sofile + '.dwp')
# Suppress warnings about duplicate CU entries (https://crbug.com/1264130)
dwp_proc = subprocess.Popen(wrapper_utils.CommandToRun(
[args.dwp, '-e', args.sofile, '-o', args.sofile + '.dwp']),
stderr=subprocess.DEVNULL)
if not partitioned_library:
# 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, '-o', args.output, args.sofile]))
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())
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