[PATCH] worktree repair: detect relative path in .git file correctly

@@ -210,7 +210,7 @@ int cmd_init_db(int argc,
 		const char *p;
 		struct strbuf sb = STRBUF_INIT;
 
-		p = read_gitfile_gently(git_dir, &err);
+		p = read_gitfile_gently(git_dir, NULL, &err);
 		if (p && get_common_dir(&sb, p)) {
 			struct strbuf mainwt = STRBUF_INIT;
 

@@ -458,7 +458,7 @@ int is_nonbare_repository_dir(struct strbuf *path)
 	assert(orig_path_len != 0);
 	strbuf_complete(path, '/');
 	strbuf_addstr(path, ".git");
-	if (read_gitfile_gently(path->buf, &gitfile_error) || is_git_directory(path->buf))
+	if (read_gitfile_gently(path->buf, NULL, &gitfile_error) || is_git_directory(path->buf))
 		ret = 1;
 	if (gitfile_error == READ_GITFILE_ERR_OPEN_FAILED ||
 	    gitfile_error == READ_GITFILE_ERR_READ_FAILED)

@@ -956,12 +956,15 @@ void read_gitfile_error_die(int error_code, const char *path)
  * return path to git directory if found. The return value comes from
  * a shared buffer.
  *
+ * On success, if absolute is not NULL, it will be set to whether the
+ * path in .git file is an absolute path.
+ *
  * On failure, if return_error_code is not NULL, return_error_code
  * will be set to an error code and NULL will be returned. If
  * return_error_code is NULL the function will die instead (for most
  * cases).
  */
-const char *read_gitfile_gently(const char *path, int *return_error_code)
+const char *read_gitfile_gently(const char *path, bool *absolute, int *return_error_code)
 {
 	const int max_file_size = 1 << 20;  /* 1MB */
 	int error_code = 0;

@@ -1016,6 +1019,8 @@ const char *read_gitfile_gently(const char *path, int *return_error_code)
 	}
 	buf[len] = '\0';
 	dir = buf + 8;
+	if (absolute)
+		*absolute = is_absolute_path(dir);
 
 	if (!is_absolute_path(dir) && (slash = strrchr(path, '/'))) {
 		size_t pathlen = slash+1 - path;

@@ -1615,7 +1620,7 @@ static enum discovery_result repo_discovery_find_dir(struct strbuf *dir,
 		if (offset > min_offset)
 			strbuf_addch(dir, '/');
 		strbuf_addstr(dir, DEFAULT_GIT_DIR_ENVIRONMENT);
-		gitdirenv = read_gitfile_gently(dir->buf, &error_code);
+		gitdirenv = read_gitfile_gently(dir->buf, NULL, &error_code);
 		if (!gitdirenv) {
 			switch (error_code) {
 			case READ_GITFILE_ERR_MISSING:

@@ -2185,7 +2190,7 @@ const char *resolve_gitdir_gently(const char *suspect, int *return_error_code)
 {
 	if (is_git_directory(suspect))
 		return suspect;
-	return read_gitfile_gently(suspect, return_error_code);
+	return read_gitfile_gently(suspect, NULL, return_error_code);
 }
 
 /* if any standard file descriptor is missing open it to /dev/null */

@@ -39,8 +39,8 @@ int is_nonbare_repository_dir(struct strbuf *path);
 #define READ_GITFILE_ERR_MISSING 9
 #define READ_GITFILE_ERR_IS_A_DIR 10
 void read_gitfile_error_die(int error_code, const char *path);
-const char *read_gitfile_gently(const char *path, int *return_error_code);
-#define read_gitfile(path) read_gitfile_gently((path), NULL)
+const char *read_gitfile_gently(const char *path, bool *absolute, int *return_error_code);
+#define read_gitfile(path) read_gitfile_gently((path), NULL, NULL)
 const char *resolve_gitdir_gently(const char *suspect, int *return_error_code);
 #define resolve_gitdir(path) resolve_gitdir_gently((path), NULL)
 

@@ -228,30 +228,60 @@ test_expect_success 'repair worktree with relative path with missing gitfile' '
 	test_cmp expect wt/.git
 '
 
-test_expect_success 'repair absolute worktree to use relative paths' '
-	test_when_finished "rm -rf main side sidemoved" &&
+test_expect_success 'repair absolute to relative in side worktree' '
+	test_when_finished "rm -rf main side" &&
 	test_create_repo main &&
 	test_commit -C main init &&
 	git -C main worktree add --detach ../side &&
-	echo "../../../../sidemoved/.git" >expect-gitdir &&
+	echo "../../../../side/.git" >expect-gitdir &&
 	echo "gitdir: ../main/.git/worktrees/side" >expect-gitfile &&
-	mv side sidemoved &&
-	git -C main worktree repair --relative-paths ../sidemoved &&
+	git -C side worktree repair --relative-paths 2>main/err &&
+	test_grep "gitdir absolute/relative path mismatch" main/err &&
 	test_cmp expect-gitdir main/.git/worktrees/side/gitdir &&
-	test_cmp expect-gitfile sidemoved/.git
+	test_cmp expect-gitfile side/.git
 '
 
-test_expect_success 'repair relative worktree to use absolute paths' '
-	test_when_finished "rm -rf main side sidemoved" &&
+test_expect_success 'repair relative to absolute in side worktree' '
+	test_when_finished "rm -rf main side" &&
 	test_create_repo main &&
 	test_commit -C main init &&
 	git -C main worktree add --relative-paths --detach ../side &&
-	echo "$(pwd)/sidemoved/.git" >expect-gitdir &&
+	echo "$(pwd)/side/.git" >expect-gitdir &&
 	echo "gitdir: $(pwd)/main/.git/worktrees/side" >expect-gitfile &&
-	mv side sidemoved &&
-	git -C main worktree repair ../sidemoved &&
+	git -C side worktree repair 2>main/err &&
+	test_grep "gitdir absolute/relative path mismatch" main/err &&
 	test_cmp expect-gitdir main/.git/worktrees/side/gitdir &&
-	test_cmp expect-gitfile sidemoved/.git
+	test_cmp expect-gitfile side/.git
+'
+
+test_expect_success 'repair absolute to relative in main worktree' '
+	test_when_finished "rm -rf main side" &&
+	test_create_repo main &&
+	git -C main config worktree.useRelativePaths false &&
+	test_commit -C main init &&
+	git -C main worktree add --detach ../side &&
+	echo "../../../../side/.git" >expect-gitdir &&
+	echo "gitdir: ../main/.git/worktrees/side" >expect-gitfile &&
+	git -C main config worktree.useRelativePaths true &&
+	git -C main worktree repair 2>main/err &&
+	test_grep ".git file absolute/relative path mismatch" main/err &&
+	test_cmp expect-gitdir main/.git/worktrees/side/gitdir &&
+	test_cmp expect-gitfile side/.git
+'
+
+test_expect_success 'repair relative to absolute in main worktree' '
+	test_when_finished "rm -rf main side" &&
+	test_create_repo main &&
+	git -C main config worktree.useRelativePaths true &&
+	test_commit -C main init &&
+	git -C main worktree add --detach ../side &&
+	echo "$(pwd)/side/.git" >expect-gitdir &&
+	echo "gitdir: $(pwd)/main/.git/worktrees/side" >expect-gitfile &&
+	git -C main config worktree.useRelativePaths false &&
+	git -C main worktree repair 2>main/err &&
+	test_grep ".git file absolute/relative path mismatch" main/err &&
+	test_cmp expect-gitdir main/.git/worktrees/side/gitdir &&
+	test_cmp expect-gitfile side/.git
 '
 
 test_done

@@ -409,7 +409,7 @@ int validate_worktree(const struct worktree *wt, struct strbuf *errmsg,
 		goto done;
 	}
 
-	path = xstrdup_or_null(read_gitfile_gently(wt_path.buf, &err));
+	path = xstrdup_or_null(read_gitfile_gently(wt_path.buf, NULL, &err));
 	if (!path) {
 		strbuf_addf_gently(errmsg, _("'%s' is not a .git file, error code %d"),
 				   wt_path.buf, err);

@@ -650,6 +650,7 @@ static void repair_gitfile(struct worktree *wt,
 	struct strbuf repo = STRBUF_INIT;
 	struct strbuf backlink = STRBUF_INIT;
 	char *dotgit_contents = NULL;
+	bool absolute;
 	const char *repair = NULL;
 	char *path = NULL;
 	int err;

@@ -667,16 +668,10 @@ static void repair_gitfile(struct worktree *wt,
 	strbuf_realpath(&repo, path, 1);
 	strbuf_addf(&dotgit, "%s/.git", wt->path);
 	strbuf_addf(&gitdir, "%s/gitdir", repo.buf);
-	dotgit_contents = xstrdup_or_null(read_gitfile_gently(dotgit.buf, &err));
+	dotgit_contents = xstrdup_or_null(read_gitfile_gently(dotgit.buf, &absolute, &err));
 
-	if (dotgit_contents) {
-		if (is_absolute_path(dotgit_contents)) {
-			strbuf_addstr(&backlink, dotgit_contents);
-		} else {
-			strbuf_addf(&backlink, "%s/%s", wt->path, dotgit_contents);
-			strbuf_realpath_forgiving(&backlink, backlink.buf, 0);
-		}
-	}
+	if (dotgit_contents)
+		strbuf_addstr(&backlink, dotgit_contents);
 
 	if (err == READ_GITFILE_ERR_NOT_A_FILE ||
 		err == READ_GITFILE_ERR_IS_A_DIR)

@@ -685,7 +680,7 @@ static void repair_gitfile(struct worktree *wt,
 		repair = _(".git file broken");
 	else if (fspathcmp(backlink.buf, repo.buf))
 		repair = _(".git file incorrect");
-	else if (use_relative_paths == is_absolute_path(dotgit_contents))
+	else if (use_relative_paths == absolute)
 		repair = _(".git file absolute/relative path mismatch");
 
 	if (repair) {

@@ -855,16 +850,9 @@ void repair_worktree_at_path(struct repository *repo,
 
 	infer_backlink(repo, dotgit.buf, &inferred_backlink);
 	strbuf_realpath_forgiving(&inferred_backlink, inferred_backlink.buf, 0);
-	dotgit_contents = xstrdup_or_null(read_gitfile_gently(dotgit.buf, &err));
+	dotgit_contents = xstrdup_or_null(read_gitfile_gently(dotgit.buf, NULL, &err));
 	if (dotgit_contents) {
-		if (is_absolute_path(dotgit_contents)) {
-			strbuf_addstr(&backlink, dotgit_contents);
-		} else {
-			strbuf_addbuf(&backlink, &dotgit);
-			strbuf_strip_suffix(&backlink, ".git");
-			strbuf_addstr(&backlink, dotgit_contents);
-			strbuf_realpath_forgiving(&backlink, backlink.buf, 0);
-		}
+		strbuf_addstr(&backlink, dotgit_contents);
 	} else if (err == READ_GITFILE_ERR_NOT_A_FILE ||
 			err == READ_GITFILE_ERR_IS_A_DIR) {
 		fn(1, dotgit.buf, _("unable to locate repository; .git is not a file"), cb_data);