Merge branch 'PHP-7.3' into PHP-7.4

* PHP-7.3:
  Fixed bug #77599 (Unbuffered queries; native prepared statements memory leak)

Author: dstogov

ext/mysqlnd/mysqlnd_ps.c

@@ -797,6 +797,7 @@ mysqlnd_stmt_fetch_row_unbuffered(MYSQLND_RES * result, void * param, const unsi
 	MYSQLND_PACKET_ROW * row_packet;
 	MYSQLND_CONN_DATA * conn = result->conn;
 	const MYSQLND_RES_METADATA * const meta = result->meta;
+	void *checkpoint;
 
 	DBG_ENTER("mysqlnd_stmt_fetch_row_unbuffered");
 
@@ -819,6 +820,9 @@ mysqlnd_stmt_fetch_row_unbuffered(MYSQLND_RES * result, void * param, const unsi
 	/* Let the row packet fill our buffer and skip additional malloc + memcpy */
 	row_packet->skip_extraction = stmt && stmt->result_bind? FALSE:TRUE;
 
+	checkpoint = result->memory_pool->checkpoint;
+	mysqlnd_mempool_save_state(result->memory_pool);
+
 	/*
 	  If we skip rows (stmt == NULL || stmt->result_bind == NULL) we have to
 	  result->unbuf->m.free_last_data() before it. The function returns always true.
@@ -841,6 +845,8 @@ mysqlnd_stmt_fetch_row_unbuffered(MYSQLND_RES * result, void * param, const unsi
 									conn->options->int_and_float_native,
 									conn->stats))
 			{
+				mysqlnd_mempool_restore_state(result->memory_pool);
+				result->memory_pool->checkpoint = checkpoint;
 				DBG_RETURN(FAIL);
 			}
 
@@ -900,6 +906,9 @@ mysqlnd_stmt_fetch_row_unbuffered(MYSQLND_RES * result, void * param, const unsi
 		}
 	}
 
+	mysqlnd_mempool_restore_state(result->memory_pool);
+	result->memory_pool->checkpoint = checkpoint;
+
 	DBG_INF_FMT("ret=%s fetched_anything=%u", ret == PASS? "PASS":"FAIL", *fetched_anything);
 	DBG_RETURN(ret);
 }