git reflog (ab)uses the log machinery to display its list of log
entries. To do so it must fake commit parent information for the log
walker.
For refs in refs/heads this is no problem, as they should only ever
point to commits. Tags and other refs however can point to anything,
thus their reflog may contain non-commit objects.
To avoid segfaulting, we check whether reflog entries are commits before
feeding them to the log walker and skip any non-commits. This means that
git reflog output will be incomplete for such refs, but that's one step
up from segfaulting. A more complete solution would be to decouple git
reflog from the log walker machinery.
Signed-off-by: Dennis Kaarsemaker <dennis@xxxxxxxxxxxxxxx>
Helped-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
Helped-by: Junio C Hamano <gitster@xxxxxxxxx>
---
reflog-walk.c | 16 +++++++++++-----
t/t1410-reflog.sh | 13 +++++++++++++
2 files changed, 24 insertions(+), 5 deletions(-)
Junio C Hamano wrote:
> However, I see that there are one of two things that you could do to
> make this part of code do slightly better than stopping at the first
> non-commit object:
>
> - pretend that the non-commit entry never existed in the first
> place and return the commit that appears in the reflog next.
This turned out to be doable in the same code segment: just keep on
processing reflog entries until you hit a commit or run out of entries.
That (and the updated foremerly-failing test) are the only changes
between v2 and v3.
I'll try to actually implement the proper solution, but that'll take a
while. Until then, this at least stops a segfault :)
diff --git a/reflog-walk.c b/reflog-walk.c
index 85b8a54..0ebd1da 100644
--- a/reflog-walk.c
+++ b/reflog-walk.c
@@ -221,6 +221,7 @@ void fake_reflog_parent(struct reflog_walk_info *info, struct commit *commit)
struct commit_info *commit_info =
get_commit_info(commit, &info->reflogs, 0);
struct commit_reflog *commit_reflog;
+ struct object *logobj;
struct reflog_info *reflog;
info->last_commit_reflog = NULL;
@@ -232,15 +233,20 @@ void fake_reflog_parent(struct reflog_walk_info *info, struct commit *commit)
commit->parents = NULL;
return;
}
-
- reflog = &commit_reflog->reflogs->items[commit_reflog->recno];
info->last_commit_reflog = commit_reflog;
- commit_reflog->recno--;
- commit_info->commit = (struct commit *)parse_object(reflog->osha1);
- if (!commit_info->commit) {
+
+ do {
+ reflog = &commit_reflog->reflogs->items[commit_reflog->recno];
+ commit_reflog->recno--;
+ logobj = parse_object(reflog->osha1);
+ } while (commit_reflog->recno && (logobj && logobj->type != OBJ_COMMIT));
+
+ if (!logobj || logobj->type != OBJ_COMMIT) {
+ commit_info->commit = NULL;
commit->parents = NULL;
return;
}
+ commit_info->commit = (struct commit *)logobj;
commit->parents = xcalloc(1, sizeof(struct commit_list));
commit->parents->item = commit_info->commit;
diff --git a/t/t1410-reflog.sh b/t/t1410-reflog.sh
index b79049f..f97513c 100755
--- a/t/t1410-reflog.sh
+++ b/t/t1410-reflog.sh
@@ -325,4 +325,17 @@ test_expect_success 'parsing reverse reflogs at BUFSIZ boundaries' '
test_cmp expect actual
'
+test_expect_success 'no segfaults for reflog containing non-commit sha1s' '
+ git update-ref --create-reflog -m "Creating ref" \
+ refs/tests/tree-in-reflog HEAD &&
+ git update-ref -m "Forcing tree" refs/tests/tree-in-reflog HEAD^{tree} &&
+ git update-ref -m "Restoring to commit" refs/tests/tree-in-reflog HEAD &&
+ git reflog refs/tests/tree-in-reflog
+'
+
+test_expect_success 'reflog containing non-commit sha1s displays properly' '
+ git reflog refs/tests/tree-in-reflog >actual &&
+ test_line_count = 2 actual
+'
+
test_done
--
2.7.0-rc1-207-ga35084c
--
Dennis Kaarsemaker <dennis@xxxxxxxxxxxxxxx>
http://twitter.com/seveas
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