#!/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())