--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hggit/verify.py	Wed Feb 26 14:19:24 2014 -0800
@@ -0,0 +1,103 @@
+# verify.py - verify Mercurial revisions
+#
+# Copyright 2014 Facebook.
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+
+import stat
+
+from mercurial import command
+from mercurial import error
+from mercurial import util as hgutil
+from mercurial.node import hex, bin, nullid
+from mercurial.i18n import _
+from mercurial import scmutil
+
+from dulwich import diff_tree
+from dulwich.objects import Commit, S_IFGITLINK
+
+def verify(ui, repo, **opts):
+    '''verify that a Mercurial rev matches the corresponding Git rev
+
+    Given a Mercurial revision that has a corresponding Git revision in the map,
+    this attempts to answer whether that revision has the same contents as the
+    corresponding Git revision.
+
+    '''
+    hgctx = scmutil.revsingle(repo, opts.get('rev'), '.')
+
+    handler = repo.githandler
+
+    gitsha = handler.map_git_get(hgctx.hex())
+    if not gitsha:
+        # TODO deal better with commits in the middle of octopus merges
+        raise hgutil.Abort(_('no git commit found for rev %s') % hgctx,
+                           hint=_('if this is an octopus merge, verify against the last rev'))
+
+    try:
+        gitcommit = handler.git.get_object(gitsha)
+    except KeyError:
+        raise hgutil.Abort(_('git equivalent %s for rev %s not found!') %
+                           (gitsha, hgctx))
+    if not isinstance(gitcommit, Commit):
+        raise hgutil.Abort(_('git equivalent %s for rev %s is not a commit!') %
+                           (gitsha, hgctx))
+
+    ui.status(_('verifying rev %s against git commit %s\n') % (hgctx, gitsha))
+    failed = False
+
+    # TODO check commit message and other metadata
+
+    dirkind = stat.S_IFDIR
+
+    hgfiles = set(hgctx)
+    # TODO deal with submodules
+    hgfiles.discard('.hgsubstate')
+    hgfiles.discard('.hgsub')
+    gitfiles = set()
+
+    i = 0
+    for gitfile, dummy in diff_tree.walk_trees(handler.git.object_store,
+                                               gitcommit.tree, None):
+        if gitfile.mode == dirkind:
+            continue
+        # TODO deal with submodules
+        if (gitfile.mode == S_IFGITLINK or gitfile.path == '.hgsubstate'
+            or gitfile.path == '.hgsub'):
+            continue
+        ui.progress('verify', i, total=len(hgfiles))
+        i += 1
+        gitfiles.add(gitfile.path)
+
+        try:
+            fctx = hgctx[gitfile.path]
+        except error.LookupError:
+            # we'll deal with this at the end
+            continue
+
+        hgflags = fctx.flags()
+        gitflags = handler.convert_git_int_mode(gitfile.mode)
+        if hgflags != gitflags:
+            ui.write(_("file has different flags: %s (hg '%s', git '%s')\n") %
+                     (gitfile.path, hgflags, gitflags))
+            failed = True
+        if fctx.data() != handler.git[gitfile.sha].data:
+            ui.write(_('difference in: %s\n') % gitfile.path)
+            failed = True
+
+    ui.progress('verify', None, total=len(hgfiles))
+
+    if hgfiles != gitfiles:
+        failed = True
+        missing = gitfiles - hgfiles
+        for f in sorted(missing):
+            ui.write(_('file found in git but not hg: %s\n') % f)
+        unexpected = hgfiles - gitfiles
+        for f in sorted(unexpected):
+            ui.write(_('file found in hg but not git: %s\n') % f)
+
+    if failed:
+        return 1
+    else:
+        return 0