git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: Jeff King <peff@peff.net>
To: git@vger.kernel.org
Cc: Jonathan Tan <jonathantanmy@google.com>
Subject: [PATCH 11/16] refs: omit dangling symrefs when using GIT_REF_PARANOIA
Date: Fri, 24 Sep 2021 14:42:38 -0400	[thread overview]
Message-ID: <YU4cHlGaEwBzTJ0k@coredump.intra.peff.net> (raw)
In-Reply-To: <YU4ZOF9+ubmoItmK@coredump.intra.peff.net>

Dangling symrefs aren't actually a corruption problem. It's perfectly
fine for refs/remotes/origin/HEAD to point to an unborn branch. And in
particular, if you are trying to establish reachability, a symref that
points nowhere doesn't matter either way. Any ref it could point to will
be examined during the rest of the traversal.

It's possible that a symref pointing nowhere _could_ be a sign that the
ref it was meant to point to was deleted accidentally (e.g., via
corruption). But there is no particular reason to think that is true for
any given case, and in the meantime, GIT_REF_PARANOIA kicking in
automatically for some operations means they'll fail unnecessarily.

So let's loosen it just a bit. The new test in t5312 shows off an
example that is safe, but currently fails (and no longer does after this
patch).

Note that we don't do anything if the caller explicitly asked for
DO_FOR_EACH_INCLUDE_BROKEN. In that case they may be looking for
dangling symrefs themselves, and setting GIT_REF_PARANOIA should not
_loosen_ things from what the caller asked for.

Signed-off-by: Jeff King <peff@peff.net>
---
 refs.c                      | 12 ++++++++----
 t/t5312-prune-corruption.sh |  7 +++++++
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/refs.c b/refs.c
index c28bd6a818..e72510813e 100644
--- a/refs.c
+++ b/refs.c
@@ -1418,10 +1418,14 @@ struct ref_iterator *refs_ref_iterator_begin(
 {
 	struct ref_iterator *iter;
 
-	if (ref_paranoia < 0)
-		ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
-	if (ref_paranoia)
-		flags |= DO_FOR_EACH_INCLUDE_BROKEN;
+	if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
+		if (ref_paranoia < 0)
+			ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
+		if (ref_paranoia) {
+			flags |= DO_FOR_EACH_INCLUDE_BROKEN;
+			flags |= DO_FOR_EACH_OMIT_DANGLING_SYMREFS;
+		}
+	}
 
 	iter = refs->be->iterator_begin(refs, prefix, flags);
 
diff --git a/t/t5312-prune-corruption.sh b/t/t5312-prune-corruption.sh
index 1522a4ba8e..d8ec5a7462 100755
--- a/t/t5312-prune-corruption.sh
+++ b/t/t5312-prune-corruption.sh
@@ -62,6 +62,13 @@ test_expect_success 'destructive repack keeps packed object' '
 	git cat-file -e $bogus
 '
 
+test_expect_success 'destructive repack not confused by dangling symref' '
+	test_when_finished "git symbolic-ref -d refs/heads/dangling" &&
+	git symbolic-ref refs/heads/dangling refs/heads/does-not-exist &&
+	git repack -ad &&
+	test_must_fail git cat-file -e $bogus
+'
+
 # We create two new objects here, "one" and "two". Our
 # main branch points to "two", which is deleted,
 # corrupting the repository. But we'd like to make sure
-- 
2.33.0.1071.gb37e412355


  parent reply	other threads:[~2021-09-24 18:42 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-24 18:30 [PATCH 0/16] enabling GIT_REF_PARANOIA by default Jeff King
2021-09-24 18:32 ` [PATCH 01/16] t7900: clean up some more broken refs Jeff King
2021-09-27 17:38   ` Jonathan Tan
2021-09-27 19:49     ` Jeff King
2021-09-24 18:33 ` [PATCH 02/16] t5516: don't use HEAD ref for invalid ref-deletion tests Jeff King
2021-09-24 18:34 ` [PATCH 03/16] t5600: provide detached HEAD for corruption failures Jeff King
2021-09-24 18:35 ` [PATCH 04/16] t5312: drop "verbose" helper Jeff King
2021-09-24 18:36 ` [PATCH 05/16] t5312: create bogus ref as necessary Jeff King
2021-09-24 18:36 ` [PATCH 06/16] t5312: test non-destructive repack Jeff King
2021-09-24 18:37 ` [PATCH 07/16] t5312: be more assertive about command failure Jeff King
2021-09-24 18:37 ` [PATCH 08/16] refs-internal.h: move DO_FOR_EACH_* flags next to each other Jeff King
2021-09-24 18:39 ` [PATCH 09/16] refs-internal.h: reorganize DO_FOR_EACH_* flag documentation Jeff King
2021-09-24 18:41 ` [PATCH 10/16] refs: add DO_FOR_EACH_OMIT_DANGLING_SYMREFS flag Jeff King
2021-09-24 18:42 ` Jeff King [this message]
2021-09-24 18:46 ` [PATCH 12/16] refs: turn on GIT_REF_PARANOIA by default Jeff King
2021-09-27 17:42   ` Jonathan Tan
2021-09-24 18:46 ` [PATCH 13/16] repack, prune: drop GIT_REF_PARANOIA settings Jeff King
2021-09-24 18:48 ` [PATCH 14/16] ref-filter: stop setting FILTER_REFS_INCLUDE_BROKEN Jeff King
2021-09-24 18:48 ` [PATCH 15/16] ref-filter: drop broken-ref code entirely Jeff King
2021-09-24 18:48 ` [PATCH 16/16] refs: drop "broken" flag from for_each_fullref_in() Jeff King
2021-09-27 17:47   ` Jonathan Tan
2021-09-24 20:22 ` [PATCH 0/16] enabling GIT_REF_PARANOIA by default Junio C Hamano

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YU4cHlGaEwBzTJ0k@coredump.intra.peff.net \
    --to=peff@peff.net \
    --cc=git@vger.kernel.org \
    --cc=jonathantanmy@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).