[RFC/PATCH] ignoring a fetch that overwrites local symref
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Dec 11, 2012, 19:46 UTC
- Message-ID
- <7v62488j8a.fsf_-_@alter.siamese.dyndns.org>
- In-Reply-To
- <1271714912-56659-1-git-send-email-jaysoffian@gmail.com>
This is a companion to an ancient thread
http://thread.gmane.org/gmane.comp.version-control.git/145311/focus=145337
in which an error was dealt with while pushing into a "mirror" repository that has a symbolic reference refs/remotes/origin/HEAD pointing at refs/remotes/origin/master with "git push --mirror". The issue was that the receiving end was told to update origin/HEAD and origin/master separately; if origin/HEAD is updated, that would update origin/master at the same time, and then when attempting to update origin/master, it would notice that it no longer has the expected old value and barf. After the series, we started ignoring such pushes to HEAD on the receiving end.
But you can suffer from a similar issue transferring objects in the opposite direction. If you run "fetch --mirror" in to such a "mirror" repository, the other side would advertise both 'master' and 'HEAD' under refs/remotes/origin/ hierarchy, and refs/*:refs/* wildcard would try to grab both of them.
Work it around by noticing a wildcard match that attempts to update a local symbolic ref and ignoring it.
Signed-off-by: Junio C Hamano <gitster@pobox.com> ---
* While I do not think it is sane to have symbolic refs in the receiving ref hierarchy (e.g. refs/remotes/origin/) that has a matching ref in the corresponding ref hierarchy in the sending side (e.g. the same, or refs/heads/ if you are doing a mirror) in the first place, we addressed the issue brought by such a setting on the push side, so it is probably a good idea to do it on the fetch side.
This is marked RFC as it cheats by ignoring symrefs that were not explicitly asked, instead of doing the "is the underlying thing going to be updated with the same operation?" logic the old patch did in da3efdb (receive-pack: detect aliased updates which can occur with symrefs, 2010-04-19). I think this simpler logic is sufficient but there may be corner cases that merit the more elaborate one, hence RFC.
remote.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git i/remote.c w/remote.c index 6aa49c0..ca1f8f2 100644 --- i/remote.c +++ w/remote.c @@ -1370,6 +1370,16 @@ int branch_merge_matches(struct branch *branch, return refname_match(branch->merge[i]->src, refname, ref_fetch_rules); } +static int ignore_symref_update(const char *refname) +{ + unsigned char sha1[20]; + int flag; + + if (!resolve_ref_unsafe(refname, sha1, 0, &flag)) + return 0; /* non-existing refs are OK */ + return (flag & REF_ISSYMREF); +} + static struct ref *get_expanded_map(const struct ref *remote_refs, const struct refspec *refspec) { @@ -1383,7 +1393,8 @@ static struct ref *get_expanded_map(const struct ref *remote_refs, if (strchr(ref->name, '^')) continue; /* a dereference item */ if (match_name_with_pattern(refspec->src, ref->name, - refspec->dst, &expn_name)) { + refspec->dst, &expn_name) && + !ignore_symref_update(expn_name)) { struct ref *cpy = copy_ref(ref); cpy->peer_ref = alloc_ref(expn_name);