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#!/usr/bin/env python
# Copyright 2017 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
################################################################################
from __future__ import print_function
import argparse
import os
import re
import shutil
import subprocess
import sys
INSTRUMENTED_LIBRARIES_DIRNAME = 'instrumented_libraries'
MSAN_LIBS_PATH = os.getenv('MSAN_LIBS_PATH', '/msan')
def IsElf(file_path):
"""Whether if the file is an elf file."""
with open(file_path) as f:
return f.read(4) == '\x7fELF'
def Ldd(binary_path):
"""Run ldd on a file."""
try:
output = subprocess.check_output(['ldd', binary_path], stderr=subprocess.STDOUT)
except subprocess.CalledProcessError:
print('Failed to call ldd on', binary_path, file=sys.stderr)
return []
libs = []
OUTPUT_PATTERN = re.compile(r'\s*([^\s]+)\s*=>\s*([^\s]+)')
for line in output.splitlines():
match = OUTPUT_PATTERN.match(line)
if not match:
continue
libs.append((match.group(1), match.group(2)))
return libs
def FindLib(path):
"""Find instrumented version of lib."""
candidate_path = os.path.join(MSAN_LIBS_PATH, path[1:])
if os.path.exists(candidate_path):
return candidate_path
for lib_dir in os.listdir(MSAN_LIBS_PATH):
candidate_path = os.path.join(MSAN_LIBS_PATH, lib_dir, path[1:])
if os.path.exists(candidate_path):
return candidate_path
return None
def PatchBinary(binary_path, instrumented_dir):
"""Patch binary to link to instrumented libs."""
extra_rpaths = set()
for name, path in Ldd(binary_path):
if not os.path.isabs(path):
continue
instrumented_path = FindLib(path)
if not instrumented_path:
print('WARNING: Instrumented library not found for', path,
file=sys.stderr)
continue
target_path = os.path.join(instrumented_dir, path[1:])
if not os.path.exists(target_path):
print('Copying instrumented lib to', target_path)
target_dir = os.path.dirname(target_path)
if not os.path.exists(target_dir):
os.makedirs(target_dir)
shutil.copy2(instrumented_path, target_path)
extra_rpaths.add(
os.path.join('$ORIGIN', INSTRUMENTED_LIBRARIES_DIRNAME,
os.path.dirname(path[1:])))
if not extra_rpaths:
return
existing_rpaths = subprocess.check_output(
['patchelf', '--print-rpath', binary_path]).strip()
processed_rpaths = ':'.join(extra_rpaths)
if existing_rpaths:
processed_rpaths += ':' + existing_rpaths
print('Patching rpath for', binary_path, 'from', existing_rpaths, 'to',
processed_rpaths)
subprocess.check_call(
['patchelf', '--force-rpath', '--set-rpath',
processed_rpaths, binary_path])
def PatchBuild(output_directory):
"""Patch build to use msan libs."""
instrumented_dir = os.path.join(output_directory,
INSTRUMENTED_LIBRARIES_DIRNAME)
if not os.path.exists(instrumented_dir):
os.mkdir(instrumented_dir)
for root_dir, _, filenames in os.walk(output_directory):
for filename in filenames:
file_path = os.path.join(root_dir, filename)
if os.path.islink(file_path):
continue
if not IsElf(file_path):
continue
PatchBinary(file_path, instrumented_dir)
def main():
parser = argparse.ArgumentParser('patch_build.py', description='MSan build patcher.')
parser.add_argument('output_dir', help='Output directory.')
args = parser.parse_args()
PatchBuild(os.path.abspath(args.output_dir))
if __name__ == '__main__':
main()
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