Check MMDB_get_metadata_as_entry_data_list return value

Author: oschwald

CHANGELOG.md

@@ -7,6 +7,8 @@ CHANGELOG
 * Improve the error handling when the user tries to open a directory
   with the pure PHP reader.
 * Improve the typehints on arrays in the PHPDocs.
+* The C extension now checks that the database metadata lookup was
+  successful.
 
 1.11.1 (2023-12-01)
 -------------------

ext/maxminddb.c

@@ -336,7 +336,15 @@ PHP_METHOD(MaxMind_Db_Reader, metadata) {
     object_init_ex(return_value, metadata_ce);
 
     MMDB_entry_data_list_s *entry_data_list;
-    MMDB_get_metadata_as_entry_data_list(mmdb_obj->mmdb, &entry_data_list);
+    int status =
+        MMDB_get_metadata_as_entry_data_list(mmdb_obj->mmdb, &entry_data_list);
+    if (status != MMDB_SUCCESS) {
+        zend_throw_exception_ex(maxminddb_exception_ce,
+                                0 TSRMLS_CC,
+                                "Error while decoding metadata. %s",
+                                MMDB_strerror(status));
+        return;
+    }
 
     zval metadata_array;
     const MMDB_entry_data_list_s *rv =