submodule absorbing: fix worktree/gitdir pointers recursively for non-moves

Consider having a submodule 'sub' and a nested submodule at 'sub/nested'.
When nested is already absorbed into sub, but sub is not absorbed into
its superproject, then we need to fixup the gitfile and core.worktree
setting for 'nested' when absorbing 'sub', but we do not need to move
its git dir around.

Previously 'nested's gitfile contained "gitdir: ../.git/modules/nested";
it has to be corrected to "gitdir: ../../.git/modules/sub1/modules/nested".

An alternative I considered to do this work lazily, i.e. when resolving
"../.git/modules/nested", we would notice the ".git" being a gitfile
linking to another path.  That seemed to be robuster by design, but harder
to get the implementation right.  Maybe we have to do that anyway once we
try to have submodules and worktrees working nicely together, but for now
just produce 'correct' (i.e. direct) pointers.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 46 insertions, 16 deletions

diff --git a/submodule.c b/submodule.c
index 4c4f033e8..3b98766a6 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1437,22 +1437,57 @@ void absorb_git_dir_into_superproject(const char *prefix,
 				      const char *path,
 				      unsigned flags)
 {
-	const char *sub_git_dir, *v;
-	char *real_sub_git_dir = NULL, *real_common_git_dir = NULL;
+	int err_code;
+	const char *sub_git_dir;
 	struct strbuf gitdir = STRBUF_INIT;
-
 	strbuf_addf(&gitdir, "%s/.git", path);
-	sub_git_dir = resolve_gitdir(gitdir.buf);
+	sub_git_dir = resolve_gitdir_gently(gitdir.buf, &err_code);
 
 	/* Not populated? */
-	if (!sub_git_dir)
-		goto out;
+	if (!sub_git_dir) {
+		char *real_new_git_dir;
+		const char *new_git_dir;
+		const struct submodule *sub;
+
+		if (err_code == READ_GITFILE_ERR_STAT_FAILED) {
+			/* unpopulated as expected */
+			strbuf_release(&gitdir);
+			return;
+		}
+
+		if (err_code != READ_GITFILE_ERR_NOT_A_REPO)
+			/* We don't know what broke here. */
+			read_gitfile_error_die(err_code, path, NULL);
+
+		/*
+		* Maybe populated, but no git directory was found?
+		* This can happen if the superproject is a submodule
+		* itself and was just absorbed. The absorption of the
+		* superproject did not rewrite the git file links yet,
+		* fix it now.
+		*/
+		sub = submodule_from_path(null_sha1, path);
+		if (!sub)
+			die(_("could not lookup name for submodule '%s'"), path);
+		new_git_dir = git_path("modules/%s", sub->name);
+		if (safe_create_leading_directories_const(new_git_dir) < 0)
+			die(_("could not create directory '%s'"), new_git_dir);
+		real_new_git_dir = real_pathdup(new_git_dir);
+		connect_work_tree_and_git_dir(path, real_new_git_dir);
+
+		free(real_new_git_dir);
+	} else {
+		/* Is it already absorbed into the superprojects git dir? */
+		char *real_sub_git_dir = real_pathdup(sub_git_dir);
+		char *real_common_git_dir = real_pathdup(get_git_common_dir());
 
-	/* Is it already absorbed into the superprojects git dir? */
-	real_sub_git_dir = real_pathdup(sub_git_dir);
-	real_common_git_dir = real_pathdup(get_git_common_dir());
-	if (!skip_prefix(real_sub_git_dir, real_common_git_dir, &v))
-		relocate_single_git_dir_into_superproject(prefix, path);
+		if (!starts_with(real_sub_git_dir, real_common_git_dir))
+			relocate_single_git_dir_into_superproject(prefix, path);
+
+		free(real_sub_git_dir);
+		free(real_common_git_dir);
+	}
+	strbuf_release(&gitdir);
 
 	if (flags & ABSORB_GITDIR_RECURSE_SUBMODULES) {
 		struct child_process cp = CHILD_PROCESS_INIT;
@@ -1478,9 +1513,4 @@ void absorb_git_dir_into_superproject(const char *prefix,
 
 		strbuf_release(&sb);
 	}
-
-out:
-	strbuf_release(&gitdir);
-	free(real_sub_git_dir);
-	free(real_common_git_dir);
 }