git notes merge: --commit should fail if underlying notes ref has moved

When manually resolving a notes merge, if the merging ref has moved since
the merge started, we should fail to complete the merge, and alert the user
to what's going on.

This situation may arise if you start a 'git notes merge' which results in
conflicts, and you then update the current notes ref (using for example
'git notes add/copy/amend/edit/remove/prune', 'git update-ref', etc.),
before you get around to resolving the notes conflicts and calling
'git notes merge --commit'.

We detect this situation by comparing the first parent of the partial merge
commit (which was created when the merge started) to the current value of the
merging notes ref (pointed to by the .git/NOTES_MERGE_REF symref).

If we don't fail in this situation, the notes merge commit would overwrite
the updated notes ref, thus losing the changes that happened in the meantime.

The patch includes a testcase verifying that we fail correctly in this
situation.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johan Herland 2010-11-09 22:49:54 +01:00 committed by Junio C Hamano
parent 443259cf92
commit 6cfd6a9dea
2 changed files with 85 additions and 2 deletions

View file

@ -786,7 +786,7 @@ static int merge_abort(struct notes_merge_options *o)
static int merge_commit(struct notes_merge_options *o)
{
struct strbuf msg = STRBUF_INIT;
unsigned char sha1[20];
unsigned char sha1[20], parent_sha1[20];
struct notes_tree *t;
struct commit *partial;
struct pretty_print_context pretty_ctx;
@ -803,6 +803,11 @@ static int merge_commit(struct notes_merge_options *o)
else if (parse_commit(partial))
die("Could not parse commit from NOTES_MERGE_PARTIAL.");
if (partial->parents)
hashcpy(parent_sha1, partial->parents->item->object.sha1);
else
hashclr(parent_sha1);
t = xcalloc(1, sizeof(struct notes_tree));
init_notes(t, "NOTES_MERGE_PARTIAL", combine_notes_overwrite, 0);
@ -818,7 +823,9 @@ static int merge_commit(struct notes_merge_options *o)
format_commit_message(partial, "%s", &msg, &pretty_ctx);
strbuf_trim(&msg);
strbuf_insert(&msg, 0, "notes: ", 7);
update_ref(msg.buf, o->local_ref, sha1, NULL, 0, DIE_ON_ERR);
update_ref(msg.buf, o->local_ref, sha1,
is_null_sha1(parent_sha1) ? NULL : parent_sha1,
0, DIE_ON_ERR);
free_notes(t);
strbuf_release(&msg);

View file

@ -477,4 +477,80 @@ EOF
verify_notes z
'
cp expect_notes_y expect_notes_m
cp expect_log_y expect_log_m
test_expect_success 'redo merge of z into m (== y) with default ("manual") resolver => Conflicting 3-way merge' '
git update-ref refs/notes/m refs/notes/y &&
test_must_fail git notes merge z >output &&
# Output should point to where to resolve conflicts
grep -q "\\.git/NOTES_MERGE_WORKTREE" output &&
# Inspect merge conflicts
ls .git/NOTES_MERGE_WORKTREE >output_conflicts &&
test_cmp expect_conflicts output_conflicts &&
( for f in $(cat expect_conflicts); do
test_cmp "expect_conflict_$f" ".git/NOTES_MERGE_WORKTREE/$f" ||
exit 1
done ) &&
# Verify that current notes tree (pre-merge) has not changed (m == y)
verify_notes y &&
verify_notes m &&
test "$(git rev-parse refs/notes/m)" = "$(cat pre_merge_y)"
'
cp expect_notes_w expect_notes_m
cp expect_log_w expect_log_m
test_expect_success 'reset notes ref m to somewhere else (w)' '
git update-ref refs/notes/m refs/notes/w &&
verify_notes m &&
test "$(git rev-parse refs/notes/m)" = "$(git rev-parse refs/notes/w)"
'
test_expect_success 'fail to finalize conflicting merge if underlying ref has moved in the meantime (m != NOTES_MERGE_PARTIAL^1)' '
# Resolve conflicts
cat >.git/NOTES_MERGE_WORKTREE/$commit_sha1 <<EOF &&
y and z notes on 1st commit
EOF
cat >.git/NOTES_MERGE_WORKTREE/$commit_sha4 <<EOF &&
y and z notes on 4th commit
EOF
# Fail to finalize merge
test_must_fail git notes merge --commit >output 2>&1 &&
# .git/NOTES_MERGE_* must remain
test -f .git/NOTES_MERGE_PARTIAL &&
test -f .git/NOTES_MERGE_REF &&
test -f .git/NOTES_MERGE_WORKTREE/$commit_sha1 &&
test -f .git/NOTES_MERGE_WORKTREE/$commit_sha2 &&
test -f .git/NOTES_MERGE_WORKTREE/$commit_sha3 &&
test -f .git/NOTES_MERGE_WORKTREE/$commit_sha4 &&
# Refs are unchanged
test "$(git rev-parse refs/notes/m)" = "$(git rev-parse refs/notes/w)"
test "$(git rev-parse refs/notes/y)" = "$(git rev-parse NOTES_MERGE_PARTIAL^1)"
test "$(git rev-parse refs/notes/m)" != "$(git rev-parse NOTES_MERGE_PARTIAL^1)"
# Mention refs/notes/m, and its current and expected value in output
grep -q "refs/notes/m" output &&
grep -q "$(git rev-parse refs/notes/m)" output &&
grep -q "$(git rev-parse NOTES_MERGE_PARTIAL^1)" output &&
# Verify that other notes refs has not changed (w, x, y and z)
verify_notes w &&
verify_notes x &&
verify_notes y &&
verify_notes z
'
test_expect_success 'resolve situation by aborting the notes merge' '
git notes merge --abort &&
# No .git/NOTES_MERGE_* files left
test_must_fail ls .git/NOTES_MERGE_* >output 2>/dev/null &&
test_cmp /dev/null output &&
# m has not moved (still == w)
test "$(git rev-parse refs/notes/m)" = "$(git rev-parse refs/notes/w)"
# Verify that other notes refs has not changed (w, x, y and z)
verify_notes w &&
verify_notes x &&
verify_notes y &&
verify_notes z
'
test_done