Dennis Kaarsemaker <dennis@xxxxxxxxxxxxxxx> writes:
> diff --git a/reflog-walk.c b/reflog-walk.c
> index 85b8a54..b85c8e8 100644
> --- a/reflog-walk.c
> +++ b/reflog-walk.c
> @@ -236,8 +236,8 @@ void fake_reflog_parent(struct reflog_walk_info *info, struct commit *commit)
> 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) {
> + commit_info->commit = lookup_commit(reflog->osha1);
> + if (!commit_info->commit || parse_commit(commit_info->commit)) {
> commit->parents = NULL;
> return;
This looks somewhat roundabout and illogical. The original was bad
because it blindly assumed reflgo->osha1 refers to a commit without
making sure that assumption holds. Calling lookup_commit() blindly
is not much better, even though you are helped that the function
happens not to barf if the given object is not a commit.
Also this changes semantics, no? Trace the original flow and think
what happens, when we see a commit object that cannot be parsed in
parse_commit_buffer(). parse_object() calls parse_object_buffer()
which in turn calls parse_commit_buffer() and the entire callchain
returns NULL. commit_info->commit will become NULL in such a case.
With your code, lookup_commit() will store a non NULL in
commit_info->commit, and parse_commit() calls parse_commit_buffer()
and that would fail, so you clear commit->parents to NULL but fail
to set commit_info->commit to NULL.
Why not keep the parse_object() as-is and make sure we error out
unless the result is a commit with a more explicit check, perhaps
like this, instead?
reflog-walk.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/reflog-walk.c b/reflog-walk.c
index 85b8a54..861d7c4 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;
@@ -236,11 +237,13 @@ void fake_reflog_parent(struct reflog_walk_info *info, struct commit *commit)
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) {
+ logobj = parse_object(reflog->osha1);
+ 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;
> +test_expect_success 'reflog containing non-commit sha1s' '
> + git checkout -b broken-reflog &&
> + echo "$(git rev-parse HEAD^{tree}) $(git rev-parse HEAD) abc <xyz> 0000000001 +0000" >> .git/logs/refs/heads/broken-reflog &&
> + git reflog broken-reflog
> +'
> +
This will negatively affect the ongoing effort to abstract out the
on-disk implementation of the reflog. In some future installation
of Git, the reflog may not even be in .git/logs/refs/whatever file.
Use a non-branch ref, so that you can store any valid object not
just commits, and use a Git command (e.g. "git update-ref" or "git
tag") instead of the raw filesystem access to update it, perhaps
like this?
git tag --create-reflog test-logs HEAD^ &&
git tag -f test-logs HEAD^{tree} &&
git tag -f test-logs HEAD &&
git reflog test-logs
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