worktree: refactor repair_worktree_after_gitdir_move()

This refactors `repair_worktree_after_gitdir_move()` to use the new
`write_worktree_linking_files` function. It also preserves the
relativity of the linking files; e.g., if an existing worktree used
absolute paths then the repaired paths will be absolute (and visa-versa).

This also adds a test case for reinitializing a repository that has
relative worktrees.

Signed-off-by: Caleb White <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>

Author: calebdw

t/t0001-init.sh

@@ -434,6 +434,12 @@ test_expect_success SYMLINKS 're-init to move gitdir symlink' '
 sep_git_dir_worktree ()  {
 	test_when_finished "rm -rf mainwt linkwt seprepo" &&
 	git init mainwt &&
+	if test "relative" = $2
+	then
+		git -C mainwt config worktree.useRelativePaths true
+	else
+		git -C mainwt config worktree.useRelativePaths false
+	fi
 	test_commit -C mainwt gumby &&
 	git -C mainwt worktree add --detach ../linkwt &&
 	git -C "$1" init --separate-git-dir ../seprepo &&
@@ -442,12 +448,20 @@ sep_git_dir_worktree ()  {
 	test_cmp expect actual
 }
 
-test_expect_success 're-init to move gitdir with linked worktrees' '
-	sep_git_dir_worktree mainwt
+test_expect_success 're-init to move gitdir with linked worktrees (absolute)' '
+	sep_git_dir_worktree mainwt absolute
+'
+
+test_expect_success 're-init to move gitdir within linked worktree (absolute)' '
+	sep_git_dir_worktree linkwt absolute
+'
+
+test_expect_success 're-init to move gitdir with linked worktrees (relative)' '
+	sep_git_dir_worktree mainwt relative
 '
 
-test_expect_success 're-init to move gitdir within linked worktree' '
-	sep_git_dir_worktree linkwt
+test_expect_success 're-init to move gitdir within linked worktree (relative)' '
+	sep_git_dir_worktree linkwt relative
 '
 
 test_expect_success MINGW '.git hidden' '

worktree.c

@@ -653,45 +653,32 @@ void repair_worktrees(worktree_repair_fn fn, void *cb_data, int use_relative_pat
 
 void repair_worktree_after_gitdir_move(struct worktree *wt, const char *old_path)
 {
-	struct strbuf path = STRBUF_INIT;
-	struct strbuf repo = STRBUF_INIT;
 	struct strbuf gitdir = STRBUF_INIT;
 	struct strbuf dotgit = STRBUF_INIT;
-	struct strbuf olddotgit = STRBUF_INIT;
-	struct strbuf tmp = STRBUF_INIT;
+	int is_relative_path;
 
 	if (is_main_worktree(wt))
 		goto done;
 
-	strbuf_realpath(&repo, git_common_path("worktrees/%s", wt->id), 1);
-	strbuf_addf(&gitdir, "%s/gitdir", repo.buf);
+	strbuf_realpath(&gitdir, git_common_path("worktrees/%s/gitdir", wt->id), 1);
 
-	if (strbuf_read_file(&olddotgit, gitdir.buf, 0) < 0)
+	if (strbuf_read_file(&dotgit, gitdir.buf, 0) < 0)
 		goto done;
 
-	strbuf_rtrim(&olddotgit);
-	if (is_absolute_path(olddotgit.buf)) {
-		strbuf_addbuf(&dotgit, &olddotgit);
-	} else {
-		strbuf_addf(&dotgit, "%s/worktrees/%s/%s", old_path, wt->id, olddotgit.buf);
+	strbuf_rtrim(&dotgit);
+	is_relative_path = ! is_absolute_path(dotgit.buf);
+	if (is_relative_path) {
+		strbuf_insertf(&dotgit, 0, "%s/worktrees/%s/", old_path, wt->id);
 		strbuf_realpath_forgiving(&dotgit, dotgit.buf, 0);
 	}
 
 	if (!file_exists(dotgit.buf))
 		goto done;
 
-	strbuf_addbuf(&path, &dotgit);
-	strbuf_strip_suffix(&path, "/.git");
-
-	write_file(dotgit.buf, "gitdir: %s", relative_path(repo.buf, path.buf, &tmp));
-	write_file(gitdir.buf, "%s", relative_path(dotgit.buf, repo.buf, &tmp));
+	write_worktree_linking_files(dotgit, gitdir, is_relative_path);
 done:
-	strbuf_release(&path);
-	strbuf_release(&repo);
 	strbuf_release(&gitdir);
 	strbuf_release(&dotgit);
-	strbuf_release(&olddotgit);
-	strbuf_release(&tmp);
 }
 
 void repair_worktrees_after_gitdir_move(const char *old_path)