build/android/gyp/util/md5_check.py

   1 # Copyright 2013 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import difflib
   6 import hashlib
   7 import os
   8 import re
   9 import sys
  10
  11 from util import build_utils
  12
  13 if build_utils.COLORAMA_ROOT not in sys.path:
  14   sys.path.append(build_utils.COLORAMA_ROOT)
  15 import colorama
  16
  17
  18 # When set and a difference is detected, a diff of what changed is printed.
  19 _PRINT_MD5_DIFFS = int(os.environ.get('PRINT_MD5_DIFFS', 0))
  20
  21 # Used to strip off temp dir prefix.
  22 _TEMP_DIR_PATTERN = re.compile(r'^/tmp/.*?/')
  23
  24
  25 def CallAndRecordIfStale(
  26     function, record_path=None, input_paths=None, input_strings=None,
  27     force=False):
  28   """Calls function if the md5sum of the input paths/strings has changed.
  29
  30   The md5sum of the inputs is compared with the one stored in record_path. If
  31   this has changed (or the record doesn't exist), function will be called and
  32   the new md5sum will be recorded.
  33
  34   If force is True, the function will be called regardless of whether the
  35   md5sum is out of date.
  36   """
  37   if not input_paths:
  38     input_paths = []
  39   if not input_strings:
  40     input_strings = []
  41   md5_checker = _Md5Checker(
  42       record_path=record_path,
  43       input_paths=input_paths,
  44       input_strings=input_strings)
  45
  46   is_stale = md5_checker.old_digest != md5_checker.new_digest
  47   if force or is_stale:
  48     if is_stale and _PRINT_MD5_DIFFS:
  49       print '%sDifference found in %s:%s' % (
  50           colorama.Fore.YELLOW, record_path, colorama.Fore.RESET)
  51       print md5_checker.DescribeDifference()
  52     function()
  53     md5_checker.Write()
  54
  55
  56 def _UpdateMd5ForFile(md5, path, block_size=2**16):
  57   with open(path, 'rb') as infile:
  58     while True:
  59       data = infile.read(block_size)
  60       if not data:
  61         break
  62       md5.update(data)
  63
  64
  65 def _UpdateMd5ForDirectory(md5, dir_path):
  66   for root, _, files in os.walk(dir_path):
  67     for f in files:
  68       _UpdateMd5ForFile(md5, os.path.join(root, f))
  69
  70
  71 def _UpdateMd5ForPath(md5, path):
  72   if os.path.isdir(path):
  73     _UpdateMd5ForDirectory(md5, path)
  74   else:
  75     _UpdateMd5ForFile(md5, path)
  76
  77
  78 def _TrimPathPrefix(path):
  79   """Attempts to remove temp dir prefix from the path.
  80
  81   Use this only for extended_info (not for the actual md5).
  82   """
  83   return _TEMP_DIR_PATTERN.sub('{TMP}', path)
  84
  85
  86 class _Md5Checker(object):
  87   def __init__(self, record_path=None, input_paths=None, input_strings=None):
  88     if not input_paths:
  89       input_paths = []
  90     if not input_strings:
  91       input_strings = []
  92
  93     assert record_path.endswith('.stamp'), (
  94         'record paths must end in \'.stamp\' so that they are easy to find '
  95         'and delete')
  96
  97     self.record_path = record_path
  98
  99     extended_info = []
 100     outer_md5 = hashlib.md5()
 101     for i in sorted(input_paths):
 102       inner_md5 = hashlib.md5()
 103       _UpdateMd5ForPath(inner_md5, i)
 104       i = _TrimPathPrefix(i)
 105       extended_info.append(i + '=' + inner_md5.hexdigest())
 106       # Include the digest in the overall diff, but not the path
 107       outer_md5.update(inner_md5.hexdigest())
 108
 109     for s in input_strings:
 110       outer_md5.update(s)
 111       extended_info.append(s)
 112
 113     self.new_digest = outer_md5.hexdigest()
 114     self.new_extended_info = extended_info
 115
 116     self.old_digest = ''
 117     self.old_extended_info = []
 118     if os.path.exists(self.record_path):
 119       with open(self.record_path, 'r') as old_record:
 120         self.old_extended_info = [line.strip() for line in old_record]
 121         self.old_digest = self.old_extended_info.pop(0)
 122
 123   def Write(self):
 124     with open(self.record_path, 'w') as new_record:
 125       new_record.write(self.new_digest)
 126       new_record.write('\n' + '\n'.join(self.new_extended_info) + '\n')
 127
 128   def DescribeDifference(self):
 129     if self.old_digest == self.new_digest:
 130       return "There's no difference."
 131     if not self.old_digest:
 132       return 'Previous stamp file not found.'
 133     if not self.old_extended_info:
 134       return 'Previous stamp file lacks extended info.'
 135     diff = difflib.unified_diff(self.old_extended_info, self.new_extended_info)
 136     return '\n'.join(diff)