git-migrate

   1 #!/usr/bin/python
   2
   3 import glob
   4 import os
   5 import sys
   6 import subprocess
   7 import shutil
   8
   9 def tagBase(pkg):
  10     p = subprocess.Popen(['git', 'tag',
  11                           '-l',
  12                           'base'],
  13                          cwd='%s.git' % pkg,
  14                          stdout=subprocess.PIPE)
  15     p.wait()
  16     if p.stdout.read().strip() != '':
  17         return
  18
  19     p = subprocess.Popen(['git', 'rev-list',
  20                           '--reverse',
  21                           'master'],
  22                          cwd='%s.git' % pkg,
  23                          stdout=subprocess.PIPE)
  24     p.wait()
  25     base = p.stdout.read().split()[0]
  26
  27     subprocess.check_call(['git', 'tag',
  28                            'base',
  29                            base],
  30                           cwd='%s.git' % pkg)
  31
  32 def clonePackage(base, pkg):
  33     path = '%s/%s' % (base, pkg)
  34     pkg = os.path.basename(pkg)
  35
  36     if not os.path.isdir('%s.git' % pkg):
  37         if os.path.isdir(pkg):
  38             shutil.rmtree(pkg)
  39         # Use --no-follow-parent because we're going to handle that with
  40         # grafts.
  41         subprocess.check_call(['git', 'svn', 'clone',
  42                                '--no-follow-parent',
  43                                '-Aauthors',
  44                                '-q',
  45                                '--no-metadata',
  46                                '%s' % path],
  47                               stdout=subprocess.PIPE)
  48
  49         # Then make the repository bare, because git-svn can't do this
  50         shutil.move('%s/.git' % pkg, '%s.git' % pkg)
  51         shutil.rmtree(pkg)
  52         subprocess.check_call(['git', 'config', 'core.bare', 'true'],
  53                               cwd='%s.git' % pkg)
  54
  55     # Some of these repos have a rev where everything was deleted
  56     # as a result of the move. We don't want that rev to exist.
  57     p = subprocess.Popen(['git', 'ls-tree', 'HEAD'],
  58                          cwd='%s.git' % pkg,
  59                          stdout=subprocess.PIPE)
  60     p.wait()
  61     if len(p.stdout.read()) == 0:
  62         subprocess.check_call(['git', 'reset', '--soft', 'HEAD^'],
  63                               cwd='%s.git' % pkg)
  64
  65     tagBase(pkg)
  66
  67 def cloneAllPackages(base):
  68     for pkg in open('package-list'):
  69         clonePackage(base, pkg.strip())
  70
  71 def mergeHistory(old_pkg, new_pkg, n):
  72     n = int(n)
  73
  74     subprocess.check_call(['git', 'push',
  75                            '../%s.git' % new_pkg,
  76                            'master:refs/heads/%s' % old_pkg],
  77                           cwd='%s.git' % old_pkg)
  78
  79     # Find the merge commit
  80     if n == 0:
  81         p = subprocess.Popen(['git', 'rev-parse',
  82                               'base'],
  83                              cwd='%s.git' % new_pkg,
  84                              stdout=subprocess.PIPE)
  85     else:
  86         p = subprocess.Popen(['git', 'rev-list',
  87                               '--reverse',
  88                               '--boundary',
  89                               '--skip=%s' % (n - 1),
  90                               'base..master'],
  91                              cwd='%s.git' % new_pkg,
  92                              stdout=subprocess.PIPE)
  93     p.wait()
  94     new_rev = p.stdout.read().split()[0].strip('-')
  95
  96     # Find any other parents of the merge commit
  97     p = subprocess.Popen(['git', 'log',
  98                           '-1',
  99                           '--pretty=format:%P',
 100                           new_rev],
 101                          cwd='%s.git' % new_pkg,
 102                          stdout=subprocess.PIPE)
 103     p.wait()
 104     parents = p.stdout.read().split()
 105
 106     # Find the additional parent we're adding
 107     p = subprocess.Popen(['git', 'rev-parse',
 108                           old_pkg],
 109                          cwd='%s.git' % new_pkg,
 110                          stdout=subprocess.PIPE)
 111     p.wait()
 112     parents.append(p.stdout.read().strip())
 113
 114     # Write out the grafts file
 115     f = open('%s.git/info/grafts' % new_pkg, 'a')
 116     print >>f, '%s %s' % (new_rev, ' '.join(parents))
 117     f.close()
 118
 119     # Run filter-branch
 120     subprocess.call(['git', 'filter-branch',
 121                      '--tag-name-filter', 'cat',
 122                      '--',
 123                      '--all'],
 124                     cwd='%s.git' % new_pkg)
 125
 126     subprocess.call(['git', 'branch',
 127                      '-D',
 128                      old_pkg],
 129                     cwd='%s.git' % new_pkg)
 130     shutil.rmtree('%s.git/refs/original' % new_pkg, True)
 131
 132 def mergeHistories():
 133     merges = []
 134     for line in open('merges'):
 135         line = line.strip()
 136         if line == '' or line[0] == '#':
 137             continue
 138
 139         merges.append(line.split())
 140
 141     for merge in merges:
 142         mergeHistory(*merge)
 143
 144     for merge in merges:
 145         shutil.rmtree('%s.git' % merge[0])
 146
 147 def cleanupRepos():
 148     for pkg in glob.glob('*.git'):
 149         subprocess.check_call(['git', 'tag', '-d', 'base'],
 150                               cwd='%s' % pkg)
 151
 152         subprocess.check_call(['git', 'gc'],
 153                               cwd='%s' % pkg)
 154
 155 if __name__ == '__main__':
 156     try:
 157         base = sys.argv[1]
 158     except:
 159         base = 'svn://invirt.mit.edu/trunk'
 160
 161     cloneAllPackages(base)
 162     mergeHistories()
 163     cleanupRepos()