Merge branch 'es/worktree-duplicate-paths'

The same worktree directory must be registered only once, but
"git worktree move" allowed this invariant to be violated, which
has been corrected.

* es/worktree-duplicate-paths:
  worktree: make "move" refuse to move atop missing registered worktree
  worktree: generalize candidate worktree path validation
  worktree: prune linked worktree referencing main worktree path
  worktree: prune duplicate entries referencing same worktree path
  worktree: make high-level pruning re-usable
  worktree: give "should be pruned?" function more meaningful name
  worktree: factor out repeated string literal

4 files changed, 141 insertions, 36 deletions

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 85d92c9761..4796c3c05e 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -126,7 +126,9 @@ OPTIONS
 	locked working tree path, specify `--force` twice.
 +
 `move` refuses to move a locked working tree unless `--force` is specified
-twice.
+twice. If the destination is already assigned to some other working tree but is
+missing (for instance, if `<new-path>` was deleted manually), then `--force`
+allows the move to proceed; use --force twice if the destination is locked.
 +
 `remove` refuses to remove an unclean working tree unless `--force` is used.
 To remove a locked working tree, specify `--force` twice.
diff --git a/builtin/worktree.c b/builtin/worktree.c
index d99db35668..1238b6bab1 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -67,7 +67,12 @@ static void delete_worktrees_dir_if_empty(void)
 	rmdir(git_path("worktrees")); /* ignore failed removal */
 }
 
-static int prune_worktree(const char *id, struct strbuf *reason)
+/*
+ * Return true if worktree entry should be pruned, along with the reason for
+ * pruning. Otherwise, return false and the worktree's path, or NULL if it
+ * cannot be determined. Caller is responsible for freeing returned path.
+ */
+static int should_prune_worktree(const char *id, struct strbuf *reason, char **wtpath)
 {
 	struct stat st;
 	char *path;
@@ -75,20 +80,21 @@ static int prune_worktree(const char *id, struct strbuf *reason)
 	size_t len;
 	ssize_t read_result;
 
+	*wtpath = NULL;
 	if (!is_directory(git_path("worktrees/%s", id))) {
-		strbuf_addf(reason, _("Removing worktrees/%s: not a valid directory"), id);
+		strbuf_addstr(reason, _("not a valid directory"));
 		return 1;
 	}
 	if (file_exists(git_path("worktrees/%s/locked", id)))
 		return 0;
 	if (stat(git_path("worktrees/%s/gitdir", id), &st)) {
-		strbuf_addf(reason, _("Removing worktrees/%s: gitdir file does not exist"), id);
+		strbuf_addstr(reason, _("gitdir file does not exist"));
 		return 1;
 	}
 	fd = open(git_path("worktrees/%s/gitdir", id), O_RDONLY);
 	if (fd < 0) {
-		strbuf_addf(reason, _("Removing worktrees/%s: unable to read gitdir file (%s)"),
-			    id, strerror(errno));
+		strbuf_addf(reason, _("unable to read gitdir file (%s)"),
+			    strerror(errno));
 		return 1;
 	}
 	len = xsize_t(st.st_size);
@@ -96,8 +102,8 @@ static int prune_worktree(const char *id, struct strbuf *reason)
 
 	read_result = read_in_full(fd, path, len);
 	if (read_result < 0) {
-		strbuf_addf(reason, _("Removing worktrees/%s: unable to read gitdir file (%s)"),
-			    id, strerror(errno));
+		strbuf_addf(reason, _("unable to read gitdir file (%s)"),
+			    strerror(errno));
 		close(fd);
 		free(path);
 		return 1;
@@ -106,53 +112,103 @@ static int prune_worktree(const char *id, struct strbuf *reason)
 
 	if (read_result != len) {
 		strbuf_addf(reason,
-			    _("Removing worktrees/%s: short read (expected %"PRIuMAX" bytes, read %"PRIuMAX")"),
-			    id, (uintmax_t)len, (uintmax_t)read_result);
+			    _("short read (expected %"PRIuMAX" bytes, read %"PRIuMAX")"),
+			    (uintmax_t)len, (uintmax_t)read_result);
 		free(path);
 		return 1;
 	}
 	while (len && (path[len - 1] == '\n' || path[len - 1] == '\r'))
 		len--;
 	if (!len) {
-		strbuf_addf(reason, _("Removing worktrees/%s: invalid gitdir file"), id);
+		strbuf_addstr(reason, _("invalid gitdir file"));
 		free(path);
 		return 1;
 	}
 	path[len] = '\0';
 	if (!file_exists(path)) {
-		free(path);
 		if (stat(git_path("worktrees/%s/index", id), &st) ||
 		    st.st_mtime <= expire) {
-			strbuf_addf(reason, _("Removing worktrees/%s: gitdir file points to non-existent location"), id);
+			strbuf_addstr(reason, _("gitdir file points to non-existent location"));
+			free(path);
 			return 1;
 		} else {
+			*wtpath = path;
 			return 0;
 		}
 	}
-	free(path);
+	*wtpath = path;
 	return 0;
 }
 
+static void prune_worktree(const char *id, const char *reason)
+{
+	if (show_only || verbose)
+		printf_ln(_("Removing %s/%s: %s"), "worktrees", id, reason);
+	if (!show_only)
+		delete_git_dir(id);
+}
+
+static int prune_cmp(const void *a, const void *b)
+{
+	const struct string_list_item *x = a;
+	const struct string_list_item *y = b;
+	int c;
+
+	if ((c = fspathcmp(x->string, y->string)))
+	    return c;
+	/*
+	 * paths same; prune_dupes() removes all but the first worktree entry
+	 * having the same path, so sort main worktree ('util' is NULL) above
+	 * linked worktrees ('util' not NULL) since main worktree can't be
+	 * removed
+	 */
+	if (!x->util)
+		return -1;
+	if (!y->util)
+		return 1;
+	/* paths same; sort by .git/worktrees/<id> */
+	return strcmp(x->util, y->util);
+}
+
+static void prune_dups(struct string_list *l)
+{
+	int i;
+
+	QSORT(l->items, l->nr, prune_cmp);
+	for (i = 1; i < l->nr; i++) {
+		if (!fspathcmp(l->items[i].string, l->items[i - 1].string))
+			prune_worktree(l->items[i].util, "duplicate entry");
+	}
+}
+
 static void prune_worktrees(void)
 {
 	struct strbuf reason = STRBUF_INIT;
+	struct strbuf main_path = STRBUF_INIT;
+	struct string_list kept = STRING_LIST_INIT_NODUP;
 	DIR *dir = opendir(git_path("worktrees"));
 	struct dirent *d;
 	if (!dir)
 		return;
 	while ((d = readdir(dir)) != NULL) {
+		char *path;
 		if (is_dot_or_dotdot(d->d_name))
 			continue;
 		strbuf_reset(&reason);
-		if (!prune_worktree(d->d_name, &reason))
-			continue;
-		if (show_only || verbose)
-			printf("%s\n", reason.buf);
-		if (show_only)
-			continue;
-		delete_git_dir(d->d_name);
+		if (should_prune_worktree(d->d_name, &reason, &path))
+			prune_worktree(d->d_name, reason.buf);
+		else if (path)
+			string_list_append(&kept, path)->util = xstrdup(d->d_name);
 	}
 	closedir(dir);
+
+	strbuf_add_absolute_path(&main_path, get_git_common_dir());
+	/* massage main worktree absolute path to match 'gitdir' content */
+	strbuf_strip_suffix(&main_path, "/.");
+	string_list_append(&kept, strbuf_detach(&main_path, NULL));
+	prune_dups(&kept);
+	string_list_clear(&kept, 1);
+
 	if (!show_only)
 		delete_worktrees_dir_if_empty();
 	strbuf_release(&reason);
@@ -224,34 +280,33 @@ static const char *worktree_basename(const char *path, int *olen)
 	return name;
 }
 
-static void validate_worktree_add(const char *path, const struct add_opts *opts)
+/* check that path is viable location for worktree */
+static void check_candidate_path(const char *path,
+				 int force,
+				 struct worktree **worktrees,
+				 const char *cmd)
 {
-	struct worktree **worktrees;
 	struct worktree *wt;
 	int locked;
 
 	if (file_exists(path) && !is_empty_dir(path))
 		die(_("'%s' already exists"), path);
 
-	worktrees = get_worktrees(0);
 	wt = find_worktree_by_path(worktrees, path);
 	if (!wt)
-		goto done;
+		return;
 
 	locked = !!worktree_lock_reason(wt);
-	if ((!locked && opts->force) || (locked && opts->force > 1)) {
+	if ((!locked && force) || (locked && force > 1)) {
 		if (delete_git_dir(wt->id))
-		    die(_("unable to re-add worktree '%s'"), path);
-		goto done;
+		    die(_("unusable worktree destination '%s'"), path);
+		return;
 	}
 
 	if (locked)
-		die(_("'%s' is a missing but locked worktree;\nuse 'add -f -f' to override, or 'unlock' and 'prune' or 'remove' to clear"), path);
+		die(_("'%s' is a missing but locked worktree;\nuse '%s -f -f' to override, or 'unlock' and 'prune' or 'remove' to clear"), cmd, path);
 	else
-		die(_("'%s' is a missing but already registered worktree;\nuse 'add -f' to override, or 'prune' or 'remove' to clear"), path);
-
-done:
-	free_worktrees(worktrees);
+		die(_("'%s' is a missing but already registered worktree;\nuse '%s -f' to override, or 'prune' or 'remove' to clear"), cmd, path);
 }
 
 static int add_worktree(const char *path, const char *refname,
@@ -268,8 +323,12 @@ static int add_worktree(const char *path, const char *refname,
 	struct commit *commit = NULL;
 	int is_branch = 0;
 	struct strbuf sb_name = STRBUF_INIT;
+	struct worktree **worktrees;
 
-	validate_worktree_add(path, opts);
+	worktrees = get_worktrees(0);
+	check_candidate_path(path, opts->force, worktrees, "add");
+	free_worktrees(worktrees);
+	worktrees = NULL;
 
 	/* is 'refname' a branch or commit? */
 	if (!opts->detach && !strbuf_check_branch_ref(&symref, refname) &&
@@ -804,8 +863,7 @@ static int move_worktree(int ac, const char **av, const char *prefix)
 		strbuf_trim_trailing_dir_sep(&dst);
 		strbuf_addstr(&dst, sep);
 	}
-	if (file_exists(dst.buf))
-		die(_("target '%s' already exists"), dst.buf);
+	check_candidate_path(dst.buf, force, worktrees, "move");
 
 	validate_no_submodules(wt);
 
diff --git a/t/t2401-worktree-prune.sh b/t/t2401-worktree-prune.sh
index b7d6d5d45a..a6ce7f590b 100755
--- a/t/t2401-worktree-prune.sh
+++ b/t/t2401-worktree-prune.sh
@@ -92,4 +92,28 @@ test_expect_success 'not prune proper checkouts' '
 	test -d .git/worktrees/nop
 '
 
+test_expect_success 'prune duplicate (linked/linked)' '
+	test_when_finished rm -fr .git/worktrees w1 w2 &&
+	git worktree add --detach w1 &&
+	git worktree add --detach w2 &&
+	sed "s/w2/w1/" .git/worktrees/w2/gitdir >.git/worktrees/w2/gitdir.new &&
+	mv .git/worktrees/w2/gitdir.new .git/worktrees/w2/gitdir &&
+	git worktree prune --verbose >actual &&
+	test_i18ngrep "duplicate entry" actual &&
+	test -d .git/worktrees/w1 &&
+	! test -d .git/worktrees/w2
+'
+
+test_expect_success 'prune duplicate (main/linked)' '
+	test_when_finished rm -fr repo wt &&
+	test_create_repo repo &&
+	test_commit -C repo x &&
+	git -C repo worktree add --detach ../wt &&
+	rm -fr wt &&
+	mv repo wt &&
+	git -C wt worktree prune --verbose >actual &&
+	test_i18ngrep "duplicate entry" actual &&
+	! test -d .git/worktrees/wt
+'
+
 test_done
diff --git a/t/t2403-worktree-move.sh b/t/t2403-worktree-move.sh
index 939d18d728..a4e1a178e0 100755
--- a/t/t2403-worktree-move.sh
+++ b/t/t2403-worktree-move.sh
@@ -112,6 +112,27 @@ test_expect_success 'move locked worktree (force)' '
 	git worktree move --force --force flump ploof
 '
 
+test_expect_success 'refuse to move worktree atop existing path' '
+	>bobble &&
+	git worktree add --detach beeble &&
+	test_must_fail git worktree move beeble bobble
+'
+
+test_expect_success 'move atop existing but missing worktree' '
+	git worktree add --detach gnoo &&
+	git worktree add --detach pneu &&
+	rm -fr pneu &&
+	test_must_fail git worktree move gnoo pneu &&
+	git worktree move --force gnoo pneu &&
+
+	git worktree add --detach nu &&
+	git worktree lock nu &&
+	rm -fr nu &&
+	test_must_fail git worktree move pneu nu &&
+	test_must_fail git worktree --force move pneu nu &&
+	git worktree move --force --force pneu nu
+'
+
 test_expect_success 'move a repo with uninitialized submodule' '
 	git init withsub &&
 	(