| # Copyright 2014 The Chromium OS Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| """Script to remove unused gconv charset modules from a build.""" |
| |
| import functools |
| import glob |
| import logging |
| import operator |
| import os |
| import stat |
| |
| from chromite.third_party import lddtree |
| |
| from chromite.lib import commandline |
| from chromite.lib import cros_build_lib |
| from chromite.lib import osutils |
| |
| |
| try: |
| import pytest # pylint: disable=import-error |
| ahocorasick = pytest.importorskip('ahocorasick') |
| except ImportError: |
| import ahocorasick |
| |
| |
| # Path pattern to search for the gconv-modules file. |
| GCONV_MODULES_PATH = 'usr/*/gconv/gconv-modules' |
| |
| # Sticky modules. These charsets modules are always included even if they |
| # aren't used. You can specify any charset name as supported by 'iconv_open', |
| # for example, 'LATIN1' or 'ISO-8859-1'. |
| STICKY_MODULES = ('UTF-16', 'UTF-32', 'UNICODE') |
| |
| # List of function names (symbols) known to use a charset as a parameter. |
| GCONV_SYMBOLS = ( |
| # glibc |
| 'iconv_open', |
| 'iconv', |
| # glib |
| 'g_convert', |
| 'g_convert_with_fallback', |
| 'g_iconv', |
| 'g_locale_to_utf8', |
| 'g_get_charset', |
| ) |
| |
| |
| class GconvModules(object): |
| """Class to manipulate the gconv/gconv-modules file and referenced modules. |
| |
| This class parses the contents of the gconv-modules file installed by glibc |
| which provides the definition of the charsets supported by iconv_open(3). It |
| allows to load the current gconv-modules file and rewrite it to include only |
| a subset of the supported modules, removing the other modules. |
| |
| Each charset is involved on some transformation between that charset and an |
| internal representation. This transformation is defined on a .so file loaded |
| dynamically with dlopen(3) when the charset defined in this file is requested |
| to iconv_open(3). |
| |
| See the comments on gconv-modules file for syntax details. |
| """ |
| |
| def __init__(self, gconv_modules_file): |
| """Initialize the class. |
| |
| Args: |
| gconv_modules_file: Path to gconv/gconv-modules file. |
| """ |
| self._filename = gconv_modules_file |
| |
| # An alias map of charsets. The key (fromcharset) is the alias name and |
| # the value (tocharset) is the real charset name. We also support a value |
| # that is an alias for another charset. |
| self._alias = {} |
| |
| # The modules dict goes from charset to module names (the filenames without |
| # the .so extension). Since several transformations involving the same |
| # charset could be defined in different files, the values of this dict are |
| # a set of module names. |
| self._modules = {} |
| |
| def Load(self): |
| """Load the charsets from gconv-modules.""" |
| with open(self._filename) as fp: |
| for line in fp: |
| line = line.split('#', 1)[0].strip() |
| if not line: |
| # Ignore blank lines & comments. |
| continue |
| |
| lst = line.split() |
| if lst[0] == 'module': |
| _, fromset, toset, filename = lst[:4] |
| for charset in (fromset, toset): |
| charset = charset.rstrip('/') |
| mods = self._modules.get(charset, set()) |
| mods.add(filename) |
| self._modules[charset] = mods |
| elif lst[0] == 'alias': |
| _, fromset, toset = lst |
| fromset = fromset.rstrip('/') |
| toset = toset.rstrip('/') |
| # Warn if the same charset is defined as two different aliases. |
| if self._alias.get(fromset, toset) != toset: |
| logging.error('charset "%s" already defined as "%s".', fromset, |
| self._alias[fromset]) |
| self._alias[fromset] = toset |
| else: |
| cros_build_lib.Die('Unknown line: %s', line) |
| |
| logging.debug('Found %d modules and %d alias in %s', len(self._modules), |
| len(self._alias), self._filename) |
| charsets = sorted(list(self._alias) + list(self._modules)) |
| # Remove the 'INTERNAL' charset from the list, since it is not a charset |
| # but an internal representation used to convert to and from other charsets. |
| if 'INTERNAL' in charsets: |
| charsets.remove('INTERNAL') |
| return charsets |
| |
| def Rewrite(self, used_charsets, dry_run=False): |
| """Rewrite gconv-modules file with only the used charsets. |
| |
| Args: |
| used_charsets: A list of used charsets. This should be a subset of the |
| list returned by Load(). |
| dry_run: Whether this function should not change any file. |
| """ |
| |
| # Compute the used modules. |
| used_modules = set() |
| for charset in used_charsets: |
| while charset in self._alias: |
| charset = self._alias[charset] |
| used_modules.update(self._modules[charset]) |
| unused_modules = (functools.reduce(set.union, list(self._modules.values())) |
| - used_modules) |
| |
| modules_dir = os.path.dirname(self._filename) |
| |
| all_modules = set.union(used_modules, unused_modules) |
| # The list of charsets that depend on a given library. For example, |
| # libdeps['libCNS.so'] is the set of all the modules that require that |
| # library. These libraries live in the same directory as the modules. |
| libdeps = {} |
| for module in all_modules: |
| deps = lddtree.ParseELF(os.path.join(modules_dir, '%s.so' % module), |
| modules_dir, []) |
| if 'needed' not in deps: |
| continue |
| for lib in deps['needed']: |
| # Ignore the libs without a path defined (outside the modules_dir). |
| if deps['libs'][lib]['path']: |
| libdeps[lib] = libdeps.get(lib, set()).union([module]) |
| |
| used_libdeps = set(lib for lib, deps in libdeps.items() |
| if deps.intersection(used_modules)) |
| unused_libdeps = set(libdeps).difference(used_libdeps) |
| |
| logging.debug('Used modules: %s', ', '.join(sorted(used_modules))) |
| logging.debug('Used dependency libs: %s, '.join(sorted(used_libdeps))) |
| |
| unused_size = 0 |
| for module in sorted(unused_modules): |
| module_path = os.path.join(modules_dir, '%s.so' % module) |
| unused_size += os.lstat(module_path).st_size |
| logging.debug('rm %s', module_path) |
| if not dry_run: |
| os.unlink(module_path) |
| |
| unused_libdeps_size = 0 |
| for lib in sorted(unused_libdeps): |
| lib_path = os.path.join(modules_dir, lib) |
| unused_libdeps_size += os.lstat(lib_path).st_size |
| logging.debug('rm %s', lib_path) |
| if not dry_run: |
| os.unlink(lib_path) |
| |
| logging.info('Done. Using %d gconv modules. Removed %d unused modules' |
| ' (%.1f KiB) and %d unused dependencies (%.1f KiB)', |
| len(used_modules), len(unused_modules), unused_size / 1024., |
| len(unused_libdeps), unused_libdeps_size / 1024.) |
| |
| # Recompute the gconv-modules file with only the included gconv modules. |
| result = [] |
| with open(self._filename) as fp: |
| for line in fp: |
| lst = line.split('#', 1)[0].strip().split() |
| |
| if not lst: |
| # Keep comments and copyright headers. |
| result.append(line) |
| elif lst[0] == 'module': |
| _, _, _, filename = lst[:4] |
| if filename in used_modules: |
| # Used module |
| result.append(line) |
| elif lst[0] == 'alias': |
| _, charset, _ = lst |
| charset = charset.rstrip('/') |
| while charset in self._alias: |
| charset = self._alias[charset] |
| if used_modules.intersection(self._modules[charset]): |
| # Alias to an used module |
| result.append(line) |
| else: |
| cros_build_lib.Die('Unknown line: %s', line) |
| |
| if not dry_run: |
| osutils.WriteFile(self._filename, ''.join(result)) |
| |
| |
| def MultipleStringMatch(patterns, corpus): |
| """Search a list of strings in a corpus string. |
| |
| Args: |
| patterns: A list of strings. |
| corpus: The text where to search for the strings. |
| |
| Returns: |
| A list of Booleans stating whether each pattern string was found in the |
| corpus or not. |
| """ |
| result = [False] * len(patterns) |
| |
| tree = ahocorasick.Automaton() |
| for i, word in enumerate(patterns): |
| tree.add_word(word, i) |
| tree.make_automaton() |
| |
| for _, i in tree.iter(corpus): |
| result[i] = True |
| |
| return result |
| |
| |
| def GconvStrip(opts): |
| """Process gconv-modules and remove unused modules. |
| |
| Args: |
| opts: The command-line args passed to the script. |
| |
| Returns: |
| The exit code number indicating whether the process succeeded. |
| """ |
| root_st = os.lstat(opts.root) |
| if not stat.S_ISDIR(root_st.st_mode): |
| cros_build_lib.Die('root (%s) must be a directory.' % opts.root) |
| |
| # Detect the possible locations of the gconv-modules file. |
| gconv_modules_files = glob.glob(os.path.join(opts.root, GCONV_MODULES_PATH)) |
| |
| if not gconv_modules_files: |
| logging.warning('gconv-modules file not found.') |
| return 1 |
| |
| # Only one gconv-modules files should be present, either on /usr/lib or |
| # /usr/lib64, but not both. |
| if len(gconv_modules_files) > 1: |
| cros_build_lib.Die('Found several gconv-modules files.') |
| |
| gconv_modules_file = gconv_modules_files[0] |
| logging.info('Searching for unused gconv files defined in %s', |
| gconv_modules_file) |
| |
| gmods = GconvModules(gconv_modules_file) |
| charsets = gmods.Load() |
| |
| # Use scanelf to search for all the binary files on the rootfs that require |
| # or define the symbol iconv_open. We also include the binaries that define |
| # it since there could be internal calls to it from other functions. |
| symbols = ','.join(GCONV_SYMBOLS) |
| cmd = ['scanelf', '--mount', '--quiet', '--recursive', '--format', '#s%F', |
| '--symbol', symbols, opts.root] |
| result = cros_build_lib.run(cmd, stdout=True, print_cmd=False, |
| encoding='utf-8') |
| files = set(result.stdout.splitlines()) |
| logging.debug('Symbols %s found on %d files.', symbols, len(files)) |
| |
| # The charsets are represented as nul-terminated strings in the binary files, |
| # so we append the '\0' to each string. This prevents some false positives |
| # when the name of the charset is a substring of some other string. It doesn't |
| # prevent false positives when the charset name is the suffix of another |
| # string, for example a binary with the string "DON'T DO IT\0" will match the |
| # 'IT' charset. Empirical test on ChromeOS images suggests that only 4 |
| # charsets could fall in category. |
| strings = [s.encode('utf-8') + b'x\00' for s in charsets] |
| logging.info('Will search for %d strings in %d files', len(strings), |
| len(files)) |
| |
| # Charsets listed in STICKY_MOUDLES are initialized as used. Note that those |
| # strings should be listed in the gconv-modules file. |
| unknown_sticky_modules = set(STICKY_MODULES) - set(charsets) |
| if unknown_sticky_modules: |
| logging.warning( |
| 'The following charsets were explicitly requested in STICKY_MODULES ' |
| "even though they don't exist: %s", |
| ', '.join(unknown_sticky_modules)) |
| global_used = [charset in STICKY_MODULES for charset in charsets] |
| |
| for filename in files: |
| used_filenames = MultipleStringMatch(strings, |
| osutils.ReadFile(filename, mode='rb')) |
| |
| global_used = [operator.or_(*x) for x in zip(global_used, used_filenames)] |
| # Check the debug flag to avoid running an useless loop. |
| if opts.debug and any(used_filenames): |
| logging.debug('File %s:', filename) |
| for i, used_filename in enumerate(used_filenames): |
| if used_filename: |
| logging.debug(' - %s', strings[i]) |
| |
| used_charsets = [cs for cs, used in zip(charsets, global_used) if used] |
| gmods.Rewrite(used_charsets, opts.dry_run) |
| return 0 |
| |
| |
| def ParseArgs(argv): |
| """Return parsed commandline arguments.""" |
| |
| parser = commandline.ArgumentParser() |
| parser.add_argument( |
| '--dry-run', action='store_true', default=False, |
| help="process but don't modify any file.") |
| parser.add_argument( |
| 'root', type='path', |
| help='path to the directory where the rootfs is mounted.') |
| |
| opts = parser.parse_args(argv) |
| opts.Freeze() |
| return opts |
| |
| |
| def main(argv): |
| """Main function to start the script.""" |
| opts = ParseArgs(argv) |
| logging.debug('Options are %s', opts) |
| |
| return GconvStrip(opts) |
