Harden the page renderers

1 file changed, 13 insertions, 2 deletions

diff --git a/source/ui-tag.c b/source/ui-tag.c
index 56862bb..6811e0c 100644
--- a/source/ui-tag.c
+++ b/source/ui-tag.c
@@ -131,6 +131,16 @@ static void print_lightweight_tag(const char *revname, struct object *obj)
 	cgit_print_layout_end();
 }
 
+/*
+ * A tag pointing at another tag links the inner one by object id, since no ref
+ * names it.
+ */
+static int tag_by_id(const char *name, struct object_id *oid)
+{
+	return !get_oid_hex(name, oid) &&
+		odb_read_object_info(the_repository->objects, oid, NULL) == OBJ_TAG;
+}
+
 void cgit_print_tag(char *revname)
 {
 	struct strbuf fullref = STRBUF_INIT;
@@ -141,13 +151,14 @@ void cgit_print_tag(char *revname)
 		revname = ctx.qry.head;
 
 	strbuf_addf(&fullref, "refs/tags/%s", revname);
-	if (repo_get_oid(the_repository, fullref.buf, &oid)) {
+	if (repo_get_oid(the_repository, fullref.buf, &oid) && !tag_by_id(revname, &oid)) {
 		cgit_print_error_page(404, "Not Found", "Bad tag reference: %s", revname);
 		goto cleanup;
 	}
 	obj = parse_object(the_repository, &oid);
 	if (!obj) {
-		cgit_print_error_page(500, "Internal Server Error", "Bad object id: %s", oid_to_hex(&oid));
+		cgit_print_error_page(500, "Internal Server Error", "Unable to read object %s",
+			oid_to_hex(&oid));
 		goto cleanup;
 	}
 	if (obj->type == OBJ_TAG)