[PATCH v3 1/1] worktree add: sanitize worktree names

[Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>]

Worktree names are based on $(basename $GIT_WORK_TREE). They aren't
significant until 3a3b9d8cde (refs: new ref types to make per-worktree
refs visible to all worktrees - 2018-10-21), where worktree name could
be part of a refname and must follow refname rules.

Update 'worktree add' code to remove special characters to follow
these rules. The code could replace chars with '-' more than
necessary, but it keeps the code simple. In the future the user will
be able to specify the worktree name by themselves if they're not
happy with this dumb character substitution.

Reported-by: Konstantin Kharlamov <hi-angel@xxxxxxxxx>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
 builtin/worktree.c      | 37 ++++++++++++++++++++++++++++++++++++-
 refs.c                  |  6 ++++++
 refs.h                  |  1 +
 t/t2025-worktree-add.sh |  7 +++++++
 4 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/builtin/worktree.c b/builtin/worktree.c
index 3f9907fcc9..21469eb52c 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -262,6 +262,36 @@ static void validate_worktree_add(const char *path, const struct add_opts *opts)
 	free_worktrees(worktrees);
 }
 
+static void sanitize_worktree_name(struct strbuf *name)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int i;
+
+	for (i = 0; i < name->len; i++) {
+		int ch = name->buf[i];
+
+		if (char_allowed_in_refname(ch))
+			strbuf_addch(&sb, ch);
+		else if (sb.len > 0 && sb.buf[sb.len - 1] != '-')
+			strbuf_addch(&sb, '-');
+	}
+	if (sb.len > 0 && sb.buf[sb.len - 1] == '-')
+		strbuf_setlen(&sb, sb.len - 1);
+	/*
+	 * a worktree name of only special chars would be reduced to
+	 * an empty string
+	 */
+	if (sb.len == 0)
+		strbuf_addstr(&sb, "worktree");
+
+	if (check_refname_format(sb.buf, REFNAME_ALLOW_ONELEVEL))
+		BUG("worktree name '%s' (from '%s') is not a valid refname",
+		    sb.buf, name->buf);
+
+	strbuf_swap(&sb, name);
+	strbuf_release(&sb);
+}
+
 static int add_worktree(const char *path, const char *refname,
 			const struct add_opts *opts)
 {
@@ -275,6 +305,7 @@ static int add_worktree(const char *path, const char *refname,
 	struct strbuf symref = STRBUF_INIT;
 	struct commit *commit = NULL;
 	int is_branch = 0;
+	struct strbuf sb_name = STRBUF_INIT;
 
 	validate_worktree_add(path, opts);
 
@@ -290,7 +321,10 @@ static int add_worktree(const char *path, const char *refname,
 		die(_("invalid reference: %s"), refname);
 
 	name = worktree_basename(path, &len);
-	git_path_buf(&sb_repo, "worktrees/%.*s", (int)(path + len - name), name);
+	strbuf_add(&sb_name, name, path + len - name);
+	sanitize_worktree_name(&sb_name);
+	name = sb_name.buf;
+	git_path_buf(&sb_repo, "worktrees/%s", name);
 	len = sb_repo.len;
 	if (safe_create_leading_directories_const(sb_repo.buf))
 		die_errno(_("could not create leading directories of '%s'"),
@@ -415,6 +449,7 @@ static int add_worktree(const char *path, const char *refname,
 	strbuf_release(&symref);
 	strbuf_release(&sb_repo);
 	strbuf_release(&sb_git);
+	strbuf_release(&sb_name);
 	return ret;
 }
 
diff --git a/refs.c b/refs.c
index 142888a40a..f23f583db1 100644
--- a/refs.c
+++ b/refs.c
@@ -57,6 +57,12 @@ static unsigned char refname_disposition[256] = {
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
 };
 
+int char_allowed_in_refname(int ch)
+{
+	return 0 <= ch && ch < ARRAY_SIZE(refname_disposition) &&
+		refname_disposition[ch] == 0;
+}
+
 /*
  * Try to read one refname component from the front of refname.
  * Return the length of the component found, or -1 if the component is
diff --git a/refs.h b/refs.h
index 308fa1f03b..61b4073f76 100644
--- a/refs.h
+++ b/refs.h
@@ -459,6 +459,7 @@ int for_each_reflog(each_ref_fn fn, void *cb_data);
  * repeated slashes are accepted.
  */
 int check_refname_format(const char *refname, int flags);
+int char_allowed_in_refname(int ch);
 
 const char *prettify_refname(const char *refname);
 
diff --git a/t/t2025-worktree-add.sh b/t/t2025-worktree-add.sh
index 286bba35d8..ea22207361 100755
--- a/t/t2025-worktree-add.sh
+++ b/t/t2025-worktree-add.sh
@@ -570,4 +570,11 @@ test_expect_success '"add" an existing locked but missing worktree' '
 	git worktree add --force --force --detach gnoo
 '
 
+test_expect_success 'sanitize generated worktree name' '
+	git worktree add --detach ".  weird*..?.lock.lock." &&
+	test -d .git/worktrees/weird-lock-lock &&
+	git worktree add --detach .... &&
+	test -d .git/worktrees/worktree
+'
+
 test_done
-- 
2.21.0.rc1.337.gdf7f8d0522