Grafts is a poor name for the list of merges. Let's call it merges

[invirt/scripts/git-migration.git] / git-migrate

diff --git a/git-migrate b/git-migrate
index f3ef98e..796f937 100755 (executable)
--- a/git-migrate
+++ b/git-migrate
@@ -24,11 +24,84 @@ def clonePackage(base, pkg):
         shutil.rmtree(pkg)
         subprocess.check_call(['git', 'config', 'core.bare', 'true'],
                               cwd='%s.git' % pkg)
+        
+    # Some of these repos have a rev where everything was deleted
+    # as a result of the move. We don't want that rev to exist.
+    p = subprocess.Popen(['git', 'ls-files'],
+                         cwd='%s.git' % pkg,
+                         stdout=subprocess.PIPE)
+    p.wait()
+    if len(p.stdout.read()) == 0:
+        subprocess.check_call(['git', 'reset', 'HEAD^'],
+                              cwd='%s.git' % pkg)
 
 def cloneAllPackages(base):
     for pkg in open('package-list'):
         clonePackage(base, pkg.strip())
 
+def mergeHistory(old_pkg, new_pkg, n):
+    cwd = os.getcwd()
+    subprocess.check_call(['git', 'push',
+                           'file:///%s/%s.git' % (cwd, new_pkg),
+                           'master:refs/heads/%s' % old_pkg],
+                          cwd='%s.git' % new_pkg)
+    
+    graft = []
+    p = subprocess.Popen(['git', 'rev-list',
+                          '--reverse',
+                          '--skip=%s' % n,
+                          'master'],
+                         cwd='%s.git' % new_pkg,
+                         stdout=subprocess.PIPE)
+    p.wait()
+    new_rev = p.stdout.read().split()[0]
+    graft.append(new_rev)
+    
+    # If n isn't 0, then n has a parent commit already that we
+    # shouldn't forget about.
+    if n != 0:
+        p = subprocess.Popen(['git', 'rev-parse',
+                              '%s^' % new_rev],
+                             cwd='%s.git' % new_pkg,
+                             stdout=subprocess.PIPE)
+        p.wait()
+        graft.append(p.stdout.read().strip())
+    
+    # And regardless, the HEAD of old_pkg should be a parent of
+    # new_pkg
+    p = subprocess.Popen(['git', 'rev-parse',
+                          'master'],
+                         cwd='%s.git' % old_pkg,
+                         stdout=subprocess.PIPE)
+    p.wait()
+    graft.append(p.stdout.read().strip())
+    
+    f = open('%s.git/info/grafts' % new_pkg, 'a')
+    
+    print >>f, ' '.join(graft)
+
+def mergeHistories():
+    merges = []
+    for line in open('merges'):
+        line = line.strip()
+        if line[0] == '#' or line == '':
+            continue
+        
+        merges.append(line.split())
+    
+    for merge in merges:
+        mergeHistory(*merge)
+    
+    for line in open('package-list'):
+        line = line.strip()
+        subprocess.check_call(['git', 'filter-branch',
+                               '--',
+                               '--all'],
+                              cwd='%s.git' % line)
+    
+    for merge in merges:
+        shutil.rmtree('%s.git' % merge[0])
+
 if __name__ == '__main__':
     try:
         base = sys.argv[1]
@@ -36,3 +109,4 @@ if __name__ == '__main__':
         base = 'svn://invirt.mit.edu/trunk'
     
     cloneAllPackages(base)
+    mergeHistories()