gecko-dev/build/unix/rewrite_asan_dylib.py

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

import re
import sys
import os
import subprocess
import shutil
from buildconfig import substs

'''
Scans the given directories for binaries referencing the AddressSanitizer
runtime library, copies it to the main directory and rewrites binaries to not
reference it with absolute paths but with @executable_path instead.
'''

# This is the dylib we're looking for
DYLIB_NAME='libclang_rt.asan_osx_dynamic.dylib'

def resolve_rpath(filename):
    otoolOut = subprocess.check_output([substs['OTOOL'], '-l', filename])
    currentCmd = None

    # The lines we need to find look like this:
    # ...
    # Load command 22
    #           cmd LC_RPATH
    #       cmdsize 80
    #          path /home/build/src/clang/bin/../lib/clang/3.8.0/lib/darwin (offset 12)
    # Load command 23
    # ...
    # Other load command types have a varying number of fields.
    for line in otoolOut.splitlines():
        cmdMatch = re.match(r'^\s+cmd ([A-Z_]+)', line)
        if cmdMatch is not None:
            currentCmd = cmdMatch.group(1)
            continue

        if currentCmd == 'LC_RPATH':
            pathMatch = re.match(r'^\s+path (.*) \(offset \d+\)', line)
            if pathMatch is not None:
                path = pathMatch.group(1)
                if os.path.isdir(path):
                    return path

    sys.stderr.write('@rpath could not be resolved from %s\n' % filename)
    exit(1)

def scan_directory(path):
    dylibCopied = False

    for root, subdirs, files in os.walk(path):
        for filename in files:
            filename = os.path.join(root, filename)

            # Skip all files that aren't either dylibs or executable
            if not (filename.endswith('.dylib') or os.access(filename, os.X_OK)):
                continue

            try:
                otoolOut = subprocess.check_output([substs['OTOOL'], '-L', filename])
            except:
                # Errors are expected on non-mach executables, ignore them and continue
                continue

            for line in otoolOut.splitlines():
                if line.find(DYLIB_NAME) != -1:
                    absDylibPath = line.split()[0]

                    # Don't try to rewrite binaries twice
                    if absDylibPath.find('@executable_path/') == 0:
                        continue

                    if not dylibCopied:
                        if absDylibPath.find('@rpath/') == 0:
                            rpath = resolve_rpath(filename)
                            copyDylibPath = absDylibPath.replace('@rpath', rpath)
                        else:
                            copyDylibPath = absDylibPath

                        # Copy the runtime once to the main directory, which is passed
                        # as the argument to this function.
                        shutil.copy(copyDylibPath, path)

                        # Now rewrite the library itself
                        subprocess.check_call([substs['INSTALL_NAME_TOOL'], '-id', '@executable_path/' + DYLIB_NAME, os.path.join(path, DYLIB_NAME)])
                        dylibCopied = True

                    # Now use install_name_tool to rewrite the path in our binary
                    subprocess.check_call([substs['INSTALL_NAME_TOOL'], '-change', absDylibPath, '@executable_path/' + DYLIB_NAME, filename])
                    break

if __name__ == '__main__':
    for d in sys.argv[1:]:
        scan_directory(d)