improve the check, avoid strlen on NULL

diff --git a/ext/exif/exif.c b/ext/exif/exif.c
index 94652e909b35f3d9ea3b2c1bdebee7278aaeb6e7..f95de3a14f199068ed7b83c424019f9a6ea7c581 100644 (file)
--- a/ext/exif/exif.c
+++ b/ext/exif/exif.c
@@ -1708,11 +1708,11 @@ static void exif_iif_add_value(image_info_type *image_info, int section_index, c
                        if (!length)
                                break;
                case TAG_FMT_UNDEFINED:
-                       if (tag == TAG_MAKER_NOTE) {
-                               length = MIN(length, strlen(value));
-                       }
-
                        if (value) {
+                               if (tag == TAG_MAKER_NOTE) {
+                                       length = MIN(length, strlen(value));
+                               }
+
                                /* do not recompute length here */
                                info_value->s = estrndup(value, length);
                                info_data->length = length;