enhanced mysql_close() and other related parts to prevent memory leaks when terminating an initiated but unestablished connection

include/ma_context.h

@@ -223,6 +223,14 @@ struct mysql_async_context {
   struct st_ma_pvio *pvio;
   void (*suspend_resume_hook)(my_bool suspend, void *user_data);
   void *suspend_resume_hook_user_data;
+
+  /* If non-NULL,  this is a poitner to the result of getaddrinfo() currently
+   * under traversal in pvio_socket_connect(). It gets reset to NULL when a
+   * connection has been established to a server. The main objective is to
+   * free this memory resource in mysql_close() while an initiated connection
+   * has not been established. */
+  struct addrinfo* pending_gai_res;
+
   /*
     This is used to save the execution contexts so that we can suspend an
     operation and switch back to the application context, to resume the

libmariadb/mariadb_lib.c

@@ -1737,7 +1737,18 @@ restart:
   }
 
   if (ma_net_init(net, pvio))
+  {
+    ma_pvio_close(pvio);
     goto error;
+  }
+
+  if (mysql->options.extension && mysql->options.extension->async_context && mysql->options.extension->async_context->pvio)
+  {
+    /* pvio delegated to mysql->net.pvio by ma_net_init().
+     * invalidate the pvio pointer in the async context */
+    mysql->options.extension->async_context->pvio = NULL;
+  }
+
 
   if (mysql->options.max_allowed_packet)
     net->max_packet_size= mysql->options.max_allowed_packet;
@@ -2343,6 +2354,20 @@ void mysql_close_slow_part(MYSQL *mysql)
       ma_simple_command(mysql, COM_QUIT,NullS,0,1,0);
     end_server(mysql);
   }
+  /* there is an ongoing async operation */
+  else if (mysql->options.extension && mysql->options.extension->async_context)
+  {
+    if (mysql->options.extension->async_context->pending_gai_res)
+    {
+        freeaddrinfo(mysql->options.extension->async_context->pending_gai_res);
+        mysql->options.extension->async_context->pending_gai_res = 0;
+    }
+    if (mysql->options.extension->async_context->pvio)
+    {
+      ma_pvio_close(mysql->options.extension->async_context->pvio);
+      mysql->options.extension->async_context->pvio = 0;
+    }
+  }
 }
 
 static void ma_clear_session_state(MYSQL *mysql)

plugins/pvio/pvio_socket.c

@@ -732,6 +732,16 @@ int pvio_socket_fast_send(MARIADB_PVIO *pvio)
   return r;
 }
 
+static int
+pvio_socket_connect_async(MARIADB_PVIO *pvio,
+                          const struct sockaddr *name, uint namelen)
+{
+  MYSQL *mysql= pvio->mysql;
+  mysql->options.extension->async_context->pvio= pvio;
+  pvio_socket_blocking(pvio, 0, 0);
+  return my_connect_async(pvio, name, namelen, pvio->timeout[PVIO_CONNECT_TIMEOUT]);
+}
+
 static int
 pvio_socket_connect_sync_or_async(MARIADB_PVIO *pvio,
                           const struct sockaddr *name, uint namelen)
@@ -742,9 +752,7 @@ pvio_socket_connect_sync_or_async(MARIADB_PVIO *pvio,
   {
     /* even if we are not connected yet, application needs to check socket
      * via mysql_get_socket api call, so we need to assign pvio */
-    mysql->options.extension->async_context->pvio= pvio;
+    return pvio_socket_connect_async(pvio, name, namelen);
-    pvio_socket_blocking(pvio, 0, 0);
-    return my_connect_async(pvio, name, namelen, pvio->timeout[PVIO_CONNECT_TIMEOUT]);
   }
 
   return pvio_socket_internal_connect(pvio, name, namelen);
@@ -916,7 +924,18 @@ my_bool pvio_socket_connect(MARIADB_PVIO *pvio, MA_PVIO_CINFO *cinfo)
         }
       }
 
+      if (mysql->options.extension && mysql->options.extension->async_context &&
+          mysql->options.extension->async_context->active)
+      {
+        mysql->options.extension->async_context->pending_gai_res = res;
+        rc= pvio_socket_connect_async(pvio, save_res->ai_addr, (uint)save_res->ai_addrlen);
+        mysql->options.extension->async_context->pending_gai_res = NULL;
+      }
+      else
+      {
         rc= pvio_socket_connect_sync_or_async(pvio, save_res->ai_addr, (uint)save_res->ai_addrlen);
+      }
+
       if (!rc)
       {
         MYSQL *mysql= pvio->mysql;