Merge branch 'es/worktree-avoid-duplication-fix'

In rare cases "git worktree add <path>" could think that <path>
was already a registered worktree even when it wasn't and refuse
to add the new worktree. This has been corrected.

* es/worktree-avoid-duplication-fix:
  worktree: don't allow "add" validation to be fooled by suffix matching
  worktree: add utility to find worktree by pathname
  worktree: improve find_worktree() documentation

4 files changed, 38 insertions, 16 deletions

diff --git a/builtin/worktree.c b/builtin/worktree.c
index d6bc5263f1..24f22800f3 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -234,14 +234,7 @@ static void validate_worktree_add(const char *path, const struct add_opts *opts)
 		die(_("'%s' already exists"), path);
 
 	worktrees = get_worktrees(0);
-	/*
-	 * find_worktree()'s suffix matching may undesirably find the main
-	 * rather than a linked worktree (for instance, when the basenames
-	 * of the main worktree and the one being created are the same).
-	 * We're only interested in linked worktrees, so skip the main
-	 * worktree with +1.
-	 */
-	wt = find_worktree(worktrees + 1, NULL, path);
+	wt = find_worktree_by_path(worktrees, path);
 	if (!wt)
 		goto done;
 
diff --git a/t/t2400-worktree-add.sh b/t/t2400-worktree-add.sh
index b5ece19460..5a7495474a 100755
--- a/t/t2400-worktree-add.sh
+++ b/t/t2400-worktree-add.sh
@@ -570,6 +570,15 @@ test_expect_success '"add" an existing locked but missing worktree' '
 	git worktree add --force --force --detach gnoo
 '
 
+test_expect_success '"add" not tripped up by magic worktree matching"' '
+	# if worktree "sub1/bar" exists, "git worktree add bar" in distinct
+	# directory `sub2` should not mistakenly complain that `bar` is an
+	# already-registered worktree
+	mkdir sub1 sub2 &&
+	git -C sub1 --git-dir=../.git worktree add --detach bozo &&
+	git -C sub2 --git-dir=../.git worktree add --detach bozo
+'
+
 test_expect_success FUNNYNAMES 'sanitize generated worktree name' '
 	git worktree add --detach ".  weird*..?.lock.lock" &&
 	test -d .git/worktrees/---weird-.-
diff --git a/worktree.c b/worktree.c
index 33c2655534..52971f7082 100644
--- a/worktree.c
+++ b/worktree.c
@@ -211,7 +211,6 @@ struct worktree *find_worktree(struct worktree **list,
 			       const char *arg)
 {
 	struct worktree *wt;
-	char *path;
 	char *to_free = NULL;
 
 	if ((wt = find_worktree_by_suffix(list, arg)))
@@ -219,11 +218,17 @@ struct worktree *find_worktree(struct worktree **list,
 
 	if (prefix)
 		arg = to_free = prefix_filename(prefix, arg);
-	path = real_pathdup(arg, 0);
-	if (!path) {
-		free(to_free);
+	wt = find_worktree_by_path(list, arg);
+	free(to_free);
+	return wt;
+}
+
+struct worktree *find_worktree_by_path(struct worktree **list, const char *p)
+{
+	char *path = real_pathdup(p, 0);
+
+	if (!path)
 		return NULL;
-	}
 	for (; *list; list++) {
 		const char *wt_path = real_path_if_valid((*list)->path);
 
@@ -231,7 +236,6 @@ struct worktree *find_worktree(struct worktree **list,
 			break;
 	}
 	free(path);
-	free(to_free);
 	return *list;
 }
 
diff --git a/worktree.h b/worktree.h
index caecc7a281..d242a6e71c 100644
--- a/worktree.h
+++ b/worktree.h
@@ -44,14 +44,30 @@ int submodule_uses_worktrees(const char *path);
 const char *get_worktree_git_dir(const struct worktree *wt);
 
 /*
- * Search a worktree that can be unambiguously identified by
- * "arg". "prefix" must not be NULL.
+ * Search for the worktree identified unambiguously by `arg` -- typically
+ * supplied by the user via the command-line -- which may be a pathname or some
+ * shorthand uniquely identifying a worktree, thus making it convenient for the
+ * user to specify a worktree with minimal typing. For instance, if the last
+ * component (say, "foo") of a worktree's pathname is unique among worktrees
+ * (say, "work/foo" and "work/bar"), it can be used to identify the worktree
+ * unambiguously.
+ *
+ * `prefix` should be the `prefix` handed to top-level Git commands along with
+ * `argc` and `argv`.
+ *
+ * Return the worktree identified by `arg`, or NULL if not found.
  */
 struct worktree *find_worktree(struct worktree **list,
 			       const char *prefix,
 			       const char *arg);
 
 /*
+ * Return the worktree corresponding to `path`, or NULL if no such worktree
+ * exists.
+ */
+struct worktree *find_worktree_by_path(struct worktree **, const char *path);
+
+/*
  * Return true if the given worktree is the main one.
  */
 int is_main_worktree(const struct worktree *wt);