build/subconfigure.py

   1 # This Source Code Form is subject to the terms of the Mozilla Public
   2 # License, v. 2.0. If a copy of the MPL was not distributed with this
   3 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
   4
   5 # This script is used to capture the content of config.status-generated
   6 # files and subsequently restore their timestamp if they haven't changed.
   7
   8 import os
   9 import re
  10 import subprocess
  11 import sys
  12 import pickle
  13
  14 class File(object):
  15     def __init__(self, path):
  16         self._path = path
  17         self._content = open(path, 'rb').read()
  18         stat = os.stat(path)
  19         self._times = (stat.st_atime, stat.st_mtime)
  20
  21     def update_time(self):
  22         '''If the file hasn't changed since the instance was created,
  23            restore its old modification time.'''
  24         if not os.path.exists(self._path):
  25             return
  26         if open(self._path, 'rb').read() == self._content:
  27             os.utime(self._path, self._times)
  28
  29
  30 # As defined in the various sub-configures in the tree
  31 PRECIOUS_VARS = set([
  32     'build_alias',
  33     'host_alias',
  34     'target_alias',
  35     'CC',
  36     'CFLAGS',
  37     'LDFLAGS',
  38     'LIBS',
  39     'CPPFLAGS',
  40     'CPP',
  41     'CCC',
  42     'CXXFLAGS',
  43     'CXX',
  44     'CCASFLAGS',
  45     'CCAS',
  46 ])
  47
  48
  49 # Autoconf, in some of the sub-configures used in the tree, likes to error
  50 # out when "precious" variables change in value. The solution it gives to
  51 # straighten things is to either run make distclean or remove config.cache.
  52 # There's no reason not to do the latter automatically instead of failing,
  53 # doing the cleanup (which, on buildbots means a full clobber), and
  54 # restarting from scratch.
  55 def maybe_clear_cache():
  56     comment = re.compile(r'^\s+#')
  57     cache = {}
  58     with open('config.cache') as f:
  59         for line in f.readlines():
  60             if not comment.match(line) and '=' in line:
  61                 key, value = line.split('=', 1)
  62                 cache[key] = value
  63     for precious in PRECIOUS_VARS:
  64         entry = 'ac_cv_env_%s_value' % precious
  65         if entry in cache and (not precious in os.environ or os.environ[precious] != cache[entry]):
  66             os.remove('config.cache')
  67             return
  68
  69
  70 def dump(dump_file, shell):
  71     if os.path.exists('config.cache'):
  72         maybe_clear_cache()
  73     if not os.path.exists('config.status'):
  74         if os.path.exists(dump_file):
  75             os.remove(dump_file)
  76         return
  77
  78     config_files = [File('config.status')]
  79
  80     # Scan the config.status output for information about configuration files
  81     # it generates.
  82     config_status_output = subprocess.check_output(
  83         [shell, '-c', './config.status --help'],
  84         stderr=subprocess.STDOUT).splitlines()
  85     state = None
  86     for line in config_status_output:
  87         if line.startswith('Configuration') and line.endswith(':'):
  88             state = 'config'
  89         elif not line.startswith(' '):
  90             state = None
  91         elif state == 'config':
  92             for f in (couple.split(':')[0] for couple in line.split()):
  93                 if os.path.isfile(f):
  94                     config_files.append(File(f))
  95
  96     with open(dump_file, 'wb') as f:
  97         pickle.dump(config_files, f)
  98
  99
 100 def adjust(dump_file):
 101     if not os.path.exists(dump_file):
 102         return
 103
 104     config_files = []
 105
 106     try:
 107         with open(dump_file, 'rb') as f:
 108             config_files = pickle.load(f)
 109     except Exception:
 110         pass
 111
 112     for f in config_files:
 113         f.update_time()
 114
 115     os.remove(dump_file)
 116
 117
 118 CONFIG_DUMP = 'config_files.pkl'
 119
 120 if __name__ == '__main__':
 121     if sys.argv[1] == 'dump':
 122         dump(CONFIG_DUMP, sys.argv[2])
 123     elif sys.argv[1] == 'adjust':
 124         adjust(CONFIG_DUMP)