image: fix pull image error

Signed-off-by: NLiFeng <lifeng68@huawei.com>

src/cutils/utils_string.c

@@ -828,6 +828,10 @@ int util_string_array_unique(const char **elements, size_t length, char ***uniqu
     char **tmp_elements = NULL;
     size_t tmp_elements_len = 0;
 
+    if (elements == NULL || length == 0) {
+        return 0;
+    }
+
     map = map_new(MAP_STR_BOOL, MAP_DEFAULT_CMP_FUNC, MAP_DEFAULT_FREE_FUNC);
     if (map == NULL) {
         ERROR("Out of memory");

src/image/oci/storage/image_store/image_store.c

@@ -891,6 +891,7 @@ char *image_store_create(const char *id, const char **names, size_t names_len, c
 out:
     if (ret != 0) {
         free(dst_id);
+        dst_id = NULL;
         free_image_t(image);
         image = NULL;
     }

src/image/oci/storage/storage.c

@@ -197,7 +197,7 @@ int storage_img_create(const char *id, const char *parent_id, const char *metada
     int ret = 0;
     char *image_id = NULL;
 
-    if (id == NULL || metadata == NULL || opts == NULL) {
+    if (id == NULL || opts == NULL) {
         ERROR("Invalid arguments for image create");
         ret = -1;
         goto out;