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