michael@0: # This Source Code Form is subject to the terms of the Mozilla Public
michael@0: # License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0: # file, You can obtain one at http://mozilla.org/MPL/2.0/.
michael@0: 
michael@0: # This script is used to capture the content of config.status-generated
michael@0: # files and subsequently restore their timestamp if they haven't changed.
michael@0: 
michael@0: import os
michael@0: import re
michael@0: import subprocess
michael@0: import sys
michael@0: import pickle
michael@0: 
michael@0: class File(object):
michael@0:     def __init__(self, path):
michael@0:         self._path = path
michael@0:         self._content = open(path, 'rb').read()
michael@0:         stat = os.stat(path)
michael@0:         self._times = (stat.st_atime, stat.st_mtime)
michael@0: 
michael@0:     @property
michael@0:     def path(self):
michael@0:         return self._path
michael@0: 
michael@0:     @property
michael@0:     def mtime(self):
michael@0:         return self._times[1]
michael@0: 
michael@0:     def update_time(self):
michael@0:         '''If the file hasn't changed since the instance was created,
michael@0:            restore its old modification time.'''
michael@0:         if not os.path.exists(self._path):
michael@0:             return
michael@0:         if open(self._path, 'rb').read() == self._content:
michael@0:             os.utime(self._path, self._times)
michael@0: 
michael@0: 
michael@0: # As defined in the various sub-configures in the tree
michael@0: PRECIOUS_VARS = set([
michael@0:     'build_alias',
michael@0:     'host_alias',
michael@0:     'target_alias',
michael@0:     'CC',
michael@0:     'CFLAGS',
michael@0:     'LDFLAGS',
michael@0:     'LIBS',
michael@0:     'CPPFLAGS',
michael@0:     'CPP',
michael@0:     'CCC',
michael@0:     'CXXFLAGS',
michael@0:     'CXX',
michael@0:     'CCASFLAGS',
michael@0:     'CCAS',
michael@0: ])
michael@0: 
michael@0: 
michael@0: # Autoconf, in some of the sub-configures used in the tree, likes to error
michael@0: # out when "precious" variables change in value. The solution it gives to
michael@0: # straighten things is to either run make distclean or remove config.cache.
michael@0: # There's no reason not to do the latter automatically instead of failing,
michael@0: # doing the cleanup (which, on buildbots means a full clobber), and
michael@0: # restarting from scratch.
michael@0: def maybe_clear_cache():
michael@0:     comment = re.compile(r'^\s+#')
michael@0:     cache = {}
michael@0:     with open('config.cache') as f:
michael@0:         for line in f.readlines():
michael@0:             if not comment.match(line) and '=' in line:
michael@0:                 key, value = line.split('=', 1)
michael@0:                 cache[key] = value
michael@0:     for precious in PRECIOUS_VARS:
michael@0:         entry = 'ac_cv_env_%s_value' % precious
michael@0:         if entry in cache and (not precious in os.environ or os.environ[precious] != cache[entry]):
michael@0:             os.remove('config.cache')
michael@0:             return
michael@0: 
michael@0: 
michael@0: def dump(dump_file, shell):
michael@0:     if os.path.exists('config.cache'):
michael@0:         maybe_clear_cache()
michael@0:     if not os.path.exists('config.status'):
michael@0:         if os.path.exists(dump_file):
michael@0:             os.remove(dump_file)
michael@0:         return
michael@0: 
michael@0:     config_files = [File('config.status')]
michael@0: 
michael@0:     # Scan the config.status output for information about configuration files
michael@0:     # it generates.
michael@0:     config_status_output = subprocess.check_output(
michael@0:         [shell, '-c', './config.status --help'],
michael@0:         stderr=subprocess.STDOUT).splitlines()
michael@0:     state = None
michael@0:     for line in config_status_output:
michael@0:         if line.startswith('Configuration') and line.endswith(':'):
michael@0:             state = 'config'
michael@0:         elif not line.startswith(' '):
michael@0:             state = None
michael@0:         elif state == 'config':
michael@0:             for f in (couple.split(':')[0] for couple in line.split()):
michael@0:                 if os.path.isfile(f):
michael@0:                     config_files.append(File(f))
michael@0: 
michael@0:     with open(dump_file, 'wb') as f:
michael@0:         pickle.dump(config_files, f)
michael@0: 
michael@0: 
michael@0: def adjust(dump_file, configure):
michael@0:     if not os.path.exists(dump_file):
michael@0:         return
michael@0: 
michael@0:     config_files = []
michael@0: 
michael@0:     try:
michael@0:         with open(dump_file, 'rb') as f:
michael@0:             config_files = pickle.load(f)
michael@0:     except Exception:
michael@0:         pass
michael@0: 
michael@0:     for f in config_files:
michael@0:         # Still touch config.status if configure is newer than its original
michael@0:         # mtime.
michael@0:         if configure and os.path.basename(f.path) == 'config.status' and \
michael@0:                 os.path.getmtime(configure) > f.mtime:
michael@0:             continue
michael@0:         f.update_time()
michael@0: 
michael@0:     os.remove(dump_file)
michael@0: 
michael@0: 
michael@0: CONFIG_DUMP = 'config_files.pkl'
michael@0: 
michael@0: if __name__ == '__main__':
michael@0:     if sys.argv[1] == 'dump':
michael@0:         dump(CONFIG_DUMP, sys.argv[2])
michael@0:     elif sys.argv[1] == 'adjust':
michael@0:         adjust(CONFIG_DUMP, sys.argv[2] if len(sys.argv) > 2 else None)