patch.py

   1 import re
   2 import sys
   3 import os.path
   4
   5 import db
   6 import dbcache
   7 from git import git
   8
   9 _boundary_line_regex = re.compile(r'^---')
  10 _diff_head_regex = re.compile(r'^diff --git a/(.*) b/(.*)$')
  11 _index_line_regex = re.compile(r'^index ([a-f0-9]{7,})\.\.([a-f0-9]{7,}) ')
  12 _all_zeros_regex = re.compile(r'^0+$')
  13
  14 class PatchError(Exception):
  15     pass
  16
  17 class Patch(object):
  18
  19     file_cache = dbcache.Cache(db.Filename, db.Filename.name, db.Session())
  20
  21     def __init__(self, data):
  22         self.blobs_pre = set()
  23         self.blobs_post = set()
  24         self.missing_files = False
  25         self.data = data
  26         self.notes = None
  27         self._parse(data)
  28
  29     def _parse(self, data):
  30         boundary_seen = False
  31         diff_seen = False
  32         filename = None
  33         notes = []
  34         for line in data.splitlines(True):
  35             if _boundary_line_regex.match(line):
  36                 boundary_seen = True
  37                 continue
  38             m = _diff_head_regex.match(line)
  39             if m:
  40                 diff_seen = True
  41                 # at least the 'pre' filename should exist
  42                 filename = m.group(1)
  43                 continue
  44             if diff_seen:
  45                 m = _index_line_regex.match(line)
  46                 if m:
  47                     if not _all_zeros_regex.match(m.group(1)):
  48                         self.blobs_pre.add(m.group(1))
  49                         self._check_file(filename)
  50                     self.blobs_post.add(m.group(2))
  51                 continue
  52             if boundary_seen:
  53                 notes.append(line)
  54         if diff_seen:
  55             self.notes = ''.join(notes)
  56
  57     def _check_file(self, name):
  58         if (not self.missing_files
  59             and os.path.basename(name) not in self.file_cache):
  60             self.missing_files = True
  61             print 'patch for missing file "%s"' % name
  62
  63     def apply(self):
  64         print 'trying to apply patch-%x' % id(self)
  65         output, ret = git('am', input=self.data)
  66         if ret != 0:
  67             # clean up
  68             git('am', '--abort')
  69             git('reset', '--hard')
  70             raise PatchError()
  71         return output