[PATCH v2] stash: fix incorrect branch name in stash message

[K Jayatheerth <jayatheerthkulkarni2005@gmail.com>]

When creating a stash, Git uses the current branch name
of the superproject to construct the stash commit message.
However, in repositories with submodules,
the message may mistakenly display the submodule branch name instead.

This is because `refs_resolve_ref_unsafe()` returns a pointer to a static buffer.
Subsequent calls to the same function overwrite the buffer,
corrupting the originally fetched `branch_name` used for the stash message.

Use `xstrdup()` to duplicate the branch name immediately after resolving it,
so that later buffer overwrites do not affect the stash message.

Signed-off-by: K Jayatheerth <jayatheerthkulkarni2005@gmail.com>
---

All good points,
Removed multiple if else blocks and kept them 
within a single if/else block.

Removed the white space at the branch_ref = refs_r... line

removed the spaces in the test case.
Thank you for the feedback.

 builtin/stash.c  | 13 ++++++++++---
 t/t3903-stash.sh | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/builtin/stash.c b/builtin/stash.c
index cfbd92852a..c71e20a8cd 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -1372,6 +1372,7 @@ static int do_create_stash(const struct pathspec *ps, struct strbuf *stash_msg_b
 	const char *head_short_sha1 = NULL;
 	const char *branch_ref = NULL;
 	const char *branch_name = "(no branch)";
+	char *branch_name_buf = NULL;
 	struct commit *head_commit = NULL;
 	struct commit_list *parents = NULL;
 	struct strbuf msg = STRBUF_INIT;
@@ -1401,11 +1402,16 @@ static int do_create_stash(const struct pathspec *ps, struct strbuf *stash_msg_b
 		ret = 1;
 		goto done;
 	}
-
+	
 	branch_ref = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
 					     "HEAD", 0, NULL, &flags);
-	if (flags & REF_ISSYMREF)
-		skip_prefix(branch_ref, "refs/heads/", &branch_name);
+
+	if (flags & REF_ISSYMREF) {
+		if (skip_prefix(branch_ref, "refs/heads/", &branch_name))
+			branch_name = branch_name_buf = xstrdup(branch_name);
+	} else
+		branch_name = "(no branch)";
+					    
 	head_short_sha1 = repo_find_unique_abbrev(the_repository,
 						  &head_commit->object.oid,
 						  DEFAULT_ABBREV);
@@ -1495,6 +1501,7 @@ static int do_create_stash(const struct pathspec *ps, struct strbuf *stash_msg_b
 	strbuf_release(&msg);
 	strbuf_release(&untracked_files);
 	free_commit_list(parents);
+	free(branch_name_buf);
 	return ret;
 }
 
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 74666ff3e4..b606827a73 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1592,4 +1592,38 @@ test_expect_success 'stash apply reports a locked index' '
 	)
 '
 
+test_expect_success 'stash reflog message uses superproject branch, not submodule branch' '
+	git init sub_project &&
+	(
+		cd sub_project &&
+		echo "Initial content in sub_project" >sub_file.txt &&
+		git add sub_file.txt &&
+		git commit -q -m "Initial commit in sub_project"
+	) &&
+
+	git init main_project &&
+	(
+		cd main_project &&
+		echo "Initial content in main_project" >main_file.txt &&
+		git add main_file.txt &&
+		git commit -q -m "Initial commit in main_project" &&
+
+		git -c protocol.file.allow=always submodule add --quiet ../sub_project sub &&
+		git commit -q -m "Added submodule sub_project" &&
+
+		git checkout -q -b feature_main &&
+		cd sub &&
+		git checkout -q -b feature_sub &&
+		cd .. &&
+
+		git checkout -q -b work_branch &&
+		echo "Important work to be stashed" >work_item.txt &&
+		git add work_item.txt &&
+		git stash push -q -m "custom stash for work_branch" &&
+
+		git stash list >../actual_stash_list.txt &&
+		grep "On work_branch: custom stash for work_branch" ../actual_stash_list.txt
+	)
+'
+
 test_done
-- 
2.49.GIT