git-migrate

   1 #!/usr/bin/python
   2
   3 import os
   4 import sys
   5 import subprocess
   6 import shutil
   7
   8 def tagBase(pkg):
   9     p = subprocess.Popen(['git', 'tag',
  10                           '-l',
  11                           'base'],
  12                          cwd='%s.git' % pkg,
  13                          stdout=subprocess.PIPE)
  14     p.wait()
  15     if p.stdout.read().strip() != '':
  16         return
  17
  18     p = subprocess.Popen(['git', 'rev-list',
  19                           '--reverse',
  20                           'master'],
  21                          cwd='%s.git' % pkg,
  22                          stdout=subprocess.PIPE)
  23     p.wait()
  24     base = p.stdout.read().split()[0]
  25
  26     subprocess.check_call(['git', 'tag',
  27                            'base',
  28                            base],
  29                           cwd='%s.git' % pkg)
  30
  31 def clonePackage(base, pkg):
  32     path = '%s/%s' % (base, pkg)
  33     pkg = os.path.basename(pkg)
  34
  35     if not os.path.isdir('%s.git' % pkg):
  36         if os.path.isdir(pkg):
  37             shutil.rmtree(pkg)
  38         # Use --no-follow-parent because we're going to handle that with
  39         # grafts.
  40         subprocess.check_call(['git', 'svn', 'clone',
  41                                '--no-follow-parent',
  42                                '-Aauthors',
  43                                '-q',
  44                                '--no-metadata',
  45                                '%s' % path],
  46                               stdout=subprocess.PIPE)
  47
  48         # Then make the repository bare, because git-svn can't do this
  49         shutil.move('%s/.git' % pkg, '%s.git' % pkg)
  50         shutil.rmtree(pkg)
  51         subprocess.check_call(['git', 'config', 'core.bare', 'true'],
  52                               cwd='%s.git' % pkg)
  53
  54     # Some of these repos have a rev where everything was deleted
  55     # as a result of the move. We don't want that rev to exist.
  56     p = subprocess.Popen(['git', 'ls-tree', 'HEAD'],
  57                          cwd='%s.git' % pkg,
  58                          stdout=subprocess.PIPE)
  59     p.wait()
  60     if len(p.stdout.read()) == 0:
  61         subprocess.check_call(['git', 'reset', '--soft', 'HEAD^'],
  62                               cwd='%s.git' % pkg)
  63
  64     tagBase(pkg)
  65
  66 def cloneAllPackages(base):
  67     for pkg in open('package-list'):
  68         clonePackage(base, pkg.strip())
  69
  70 def mergeHistory(old_pkg, new_pkg, n):
  71     n = int(n)
  72
  73     subprocess.check_call(['git', 'push',
  74                            '../%s.git' % new_pkg,
  75                            'master:refs/heads/%s' % old_pkg],
  76                           cwd='%s.git' % old_pkg)
  77
  78     # Find the merge commit
  79     if n == 0:
  80         p = subprocess.Popen(['git', 'rev-parse',
  81                               'base'],
  82                              cwd='%s.git' % new_pkg,
  83                              stdout=subprocess.PIPE)
  84     else:
  85         p = subprocess.Popen(['git', 'rev-list',
  86                               '--reverse',
  87                               '--boundary',
  88                               '--skip=%s' % (n - 1),
  89                               'base..master'],
  90                              cwd='%s.git' % new_pkg,
  91                              stdout=subprocess.PIPE)
  92     p.wait()
  93     new_rev = p.stdout.read().split()[0].strip('-')
  94
  95     # Find any other parents of the merge commit
  96     p = subprocess.Popen(['git', 'log',
  97                           '-1',
  98                           '--pretty=format:%P',
  99                           new_rev],
 100                          cwd='%s.git' % new_pkg,
 101                          stdout=subprocess.PIPE)
 102     p.wait()
 103     parents = p.stdout.read().split()
 104
 105     # Find the additional parent we're adding
 106     p = subprocess.Popen(['git', 'rev-parse',
 107                           old_pkg],
 108                          cwd='%s.git' % new_pkg,
 109                          stdout=subprocess.PIPE)
 110     p.wait()
 111     parents.append(p.stdout.read().strip())
 112
 113     # Write out the grafts file
 114     f = open('%s.git/info/grafts' % new_pkg, 'a')
 115     print >>f, '%s %s' % (new_rev, ' '.join(parents))
 116     f.close()
 117
 118     # Run filter-branch
 119     subprocess.call(['git', 'filter-branch',
 120                      '--tag-name-filter', 'cat',
 121                      '--',
 122                      '--all'],
 123                     cwd='%s.git' % new_pkg)
 124
 125     subprocess.call(['git', 'branch',
 126                      '-D',
 127                      old_pkg],
 128                     cwd='%s.git' % new_pkg)
 129     shutil.rmtree('%s.git/refs/original' % new_pkg, True)
 130
 131 def mergeHistories():
 132     merges = []
 133     for line in open('merges'):
 134         line = line.strip()
 135         if line == '' or line[0] == '#':
 136             continue
 137
 138         merges.append(line.split())
 139
 140     for merge in merges:
 141         mergeHistory(*merge)
 142
 143     for merge in merges:
 144         shutil.rmtree('%s.git' % merge[0])
 145
 146 if __name__ == '__main__':
 147     try:
 148         base = sys.argv[1]
 149     except:
 150         base = 'svn://invirt.mit.edu/trunk'
 151
 152     cloneAllPackages(base)
 153     mergeHistories()