# Copyright 2014 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Helper script to close over all transitive dependencies of a given .nexe
executable.
e.g. Given
A -> B
B -> C
B -> D
C -> E
where "A -> B" means A depends on B, then GetNeeded(A) will return A, B, C, D
and E.
"""
import os
import re
import subprocess
import elf
SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
SDK_DIR = os.path.dirname(os.path.dirname(SCRIPT_DIR))
NeededMatcher = re.compile('^ *NEEDED *([^ ]+)\n$')
FormatMatcher = re.compile('^(.+):\\s*file format (.+)\n$')
LOADER_X86 = 'runnable-ld.so' # Name of the dynamic loader
LOADER_ARM = 'elf_loader_arm.nexe' # Name of the ARM dynamic loader
OBJDUMP_ARCH_MAP = {
# Names returned by Linux's objdump:
'elf64-x86-64': 'x86-64',
'elf32-i386': 'x86-32',
'elf32-little': 'arm',
'elf32-littlearm': 'arm',
# Names returned by old x86_64-nacl-objdump:
'elf64-nacl': 'x86-64',
'elf32-nacl': 'x86-32',
# Names returned by new x86_64-nacl-objdump:
'elf64-x86-64-nacl': 'x86-64',
'elf32-x86-64-nacl': 'x86-64',
'elf32-i386-nacl': 'x86-32',
'elf32-littlearm-nacl': 'arm',
}
# The proper name of the dynamic linker, as kept in the IRT. This is
# excluded from the nmf file by convention.
LD_NACL_MAP = {
'x86-32': 'ld-nacl-x86-32.so.1',
'x86-64': 'ld-nacl-x86-64.so.1',
'arm': None,
}
class Error(Exception):
'''Local Error class for this file.'''
pass
class NoObjdumpError(Error):
'''Error raised when objdump is needed but not found'''
pass
def GetNeeded(main_files, objdump, lib_path):
'''Collect the list of dependencies for the main_files
Args:
main_files: A list of files to find dependencies of.
objdump: Path to the objdump executable.
lib_path: A list of paths to search for shared libraries.
Returns:
A dict with key=filename and value=architecture. The architecture will be
one of ('x86_32', 'x86_64', 'arm').
'''
dynamic = any(elf.ParseElfHeader(f)[1] for f in main_files)
if dynamic:
return _GetNeededDynamic(main_files, objdump, lib_path)
else:
return _GetNeededStatic(main_files)
def _GetNeededDynamic(main_files, objdump, lib_path):
examined = set()
all_files, unexamined = GleanFromObjdump(main_files, None, objdump, lib_path)
for arch in all_files.values():
if unexamined:
if arch == 'arm':
unexamined.add((LOADER_ARM, arch))
else:
unexamined.add((LOADER_X86, arch))
while unexamined:
files_to_examine = {}
# Take all the currently unexamined files and group them
# by architecture.
for name, arch in unexamined:
files_to_examine.setdefault(arch, []).append(name)
# Call GleanFromObjdump() for each architecture.
needed = set()
for arch, files in files_to_examine.items():
new_files, new_needed = GleanFromObjdump(files, arch, objdump, lib_path)
all_files.update(new_files)
needed |= new_needed
examined |= unexamined
unexamined = needed - examined
# With the runnable-ld.so scheme we have today, the proper name of
# the dynamic linker should be excluded from the list of files.
ldso = [LD_NACL_MAP[arch] for arch in set(OBJDUMP_ARCH_MAP.values())]
for filename, arch in list(all_files.items()):
name = os.path.basename(filename)
if name in ldso:
del all_files[filename]
return all_files
def GleanFromObjdump(files, arch, objdump, lib_path):
'''Get architecture and dependency information for given files
Args:
files: A list of files to examine.
[ '/path/to/my.nexe',
'/path/to/lib64/libmy.so',
'/path/to/mydata.so',
'/path/to/my.data' ]
arch: The architecure we are looking for, or None to accept any
architecture.
objdump: Path to the objdump executable.
lib_path: A list of paths to search for shared libraries.
Returns: A tuple with the following members:
input_info: A dict with key=filename and value=architecture. The
architecture will be one of ('x86_32', 'x86_64', 'arm').
needed: A set of strings formatted as "arch/name". Example:
set(['x86-32/libc.so', 'x86-64/libgcc.so'])
'''
if not objdump:
raise NoObjdumpError('No objdump executable found!')
full_paths = set()
for filename in files:
if os.path.exists(filename):
full_paths.add(filename)
else:
for path in _FindLibsInPath(filename, lib_path):
full_paths.add(path)
cmd = [objdump, '-p'] + list(sorted(full_paths))
env = {'LANG': 'en_US.UTF-8'}
proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
stderr=subprocess.PIPE, bufsize=-1,
universal_newlines=True,
env=env)
input_info = {}
found_basenames = set()
needed = set()
output, err_output = proc.communicate()
if proc.returncode:
raise Error('%s\nStdError=%s\nobjdump failed with error code: %d' %
(output, err_output, proc.returncode))
file_arch = None
for line in output.splitlines(True):
# Objdump should display the architecture first and then the dependencies
# second for each file in the list.
matched = FormatMatcher.match(line)
if matched:
filename = matched.group(1)
file_arch = OBJDUMP_ARCH_MAP[matched.group(2)]
if arch and file_arch != arch:
continue
name = os.path.basename(filename)
found_basenames.add(name)
input_info[filename] = file_arch
matched = NeededMatcher.match(line)
if matched:
if arch and file_arch != arch:
continue
filename = matched.group(1)
new_needed = (filename, file_arch)
needed.add(new_needed)
for filename in files:
if os.path.basename(filename) not in found_basenames:
raise Error('Library not found [%s]: %s' % (arch, filename))
return input_info, needed
def _FindLibsInPath(name, lib_path):
'''Finds the set of libraries matching |name| within lib_path
Args:
name: name of library to find
lib_path: A list of paths to search for shared libraries.
Returns:
A list of system paths that match the given name within the lib_path'''
files = []
for dirname in lib_path:
# The libc.so files in the the glibc toolchain is actually a linker
# script which references libc.so.<SHA1>. This means the libc.so itself
# does not end up in the NEEDED section for glibc.
if name == 'libc.so':
continue
filename = os.path.join(dirname, name)
if os.path.exists(filename):
files.append(filename)
if not files:
raise Error('cannot find library %s' % name)
return files
def _GetNeededStatic(main_files):
needed = {}
for filename in main_files:
arch = elf.ParseElfHeader(filename)[0]
needed[filename] = arch
return needed
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