ui-shared: fix broken sizeof in title setting and rewrite

The old algorithm was totally incorrect. While we're at it, use «
instead of \, since it makes more sense.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui-shared.c

@@ -1192,35 +1192,17 @@ void cgit_print_snapshot_links(const struct cgit_repo *repo, const char *ref,
 
 void cgit_set_title_from_path(const char *path)
 {
-	size_t path_len, path_index, path_last_end, line_len;
-	char *new_title;
+	struct strbuf sb = STRBUF_INIT;
+	const char *slash, *last_slash;
 
 	if (!path)
 		return;
 
-	path_len = strlen(path);
-	new_title = xmalloc(path_len + 3 + strlen(ctx.page.title) + 1);
-	new_title[0] = '\0';
-
-	for (path_index = path_len, path_last_end = path_len; path_index-- > 0;) {
-		if (path[path_index] == '/') {
-			if (path_index == path_len - 1) {
-				path_last_end = path_index - 1;
-				continue;
-			}
-			strncat(new_title, &path[path_index + 1], path_last_end - path_index - 1);
-			line_len = strlen(new_title);
-			new_title[line_len++] = '\\';
-			new_title[line_len] = '\0';
-			path_last_end = path_index;
-		}
+	for (last_slash = path + strlen(path); (slash = memrchr(path, '/', last_slash - path)) != NULL; last_slash = slash) {
+		strbuf_add(&sb, slash + 1, last_slash - slash - 1);
+		strbuf_addstr(&sb, " \xc2\xab ");
 	}
-	if (path_last_end)
-		strncat(new_title, path, path_last_end);
-
-	line_len = strlen(new_title);
-	memcpy(&new_title[line_len], " - ", 3);
-	new_title[line_len + 3] = '\0';
-	strncat(new_title, ctx.page.title, sizeof(new_title) - strlen(new_title) - 1);
-	ctx.page.title = new_title;
+	strbuf_add(&sb, path, last_slash - path);
+	strbuf_addf(&sb, " - %s", ctx.page.title);
+	ctx.page.title = strbuf_detach(&sb, NULL);
 }