"merge $itself" may be used to create commits with previous branch tip
being repeated as n-th parent or even moved from being 1-st to be just
n-th. This is not a documented use case and doesn't look like a common
one.
In presence of "from $some" command "merge $itself" acts the same as
"merge $some" would. Which is completely undocumented and looks like
a bug (caused by parse_from() temporarily rewriting b->sha1 with $some).
Just deny "merge $itself" for now. It was a bit broken and btw "from
$itself" was and is a forbidden command too.
Signed-off-by: Dmitry Ivankov <divanorama@xxxxxxxxx>
---
fast-import.c | 12 +++++++++---
t/t9300-fast-import.sh | 13 +++++++++++++
2 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/fast-import.c b/fast-import.c
index f03da1e..781c614 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -2611,7 +2611,7 @@ static int parse_from(struct branch *b)
return 1;
}
-static struct hash_list *parse_merge(unsigned int *count)
+static struct hash_list *parse_merge(unsigned int *count, struct branch *b)
{
struct hash_list *list = NULL, *n, *e = e;
const char *from;
@@ -2622,7 +2622,13 @@ static struct hash_list *parse_merge(unsigned int *count)
from = strchr(command_buf.buf, ' ') + 1;
n = xmalloc(sizeof(*n));
s = lookup_branch(from);
- if (s)
+ if (b == s)
+ /*
+ * Also if there were a 'from' command, b will point to
+ * 'from' commit, because parse_from stores it there.
+ */
+ die("Can't merge a branch with itself: %s", b->name);
+ else if (s)
hashcpy(n->sha1, s->sha1);
else if (*from == ':') {
uintmax_t idnum = parse_mark_ref_eol(from);
@@ -2686,7 +2692,7 @@ static void parse_new_commit(void)
parse_data(&msg, 0, NULL);
read_next_command();
parse_from(b);
- merge_list = parse_merge(&merge_count);
+ merge_list = parse_merge(&merge_count, b);
/* ensure the branch is active/loaded */
if (!b->branch_tree.tree || !max_active_branches) {
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 6f4c988..79cb72a 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -872,6 +872,19 @@ test_expect_success \
'git fast-import <input &&
git rev-parse --verify J5 &&
test_must_fail git rev-parse --verify J5^'
+
+cat >input <<INPUT_END
+commit refs/heads/J5
+committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+data <<COMMIT
+Merge J5 with itself.
+COMMIT
+merge refs/heads/J5
+
+INPUT_END
+test_expect_success \
+ 'J: disallow merge with itself' \
+ 'test_must_fail git fast-import <input'
###
### series K
###
--
1.7.3.4
--
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