MDEV-34958: after Trigger doesn't work correctly with bulk insert

This bug has the same nature as the issues
  MDEV-34718: Trigger doesn't work correctly with bulk update
  MDEV-24411: Trigger doesn't work correctly with bulk insert

To fix the issue covering all use cases, resetting the thd->bulk_param
temporary to the value nullptr before invoking triggers and restoring
its original value on finishing execution of a trigger is moved to the method
  Table_triggers_list::process_triggers
that be invoked ultimately for any kind of triggers.

sql/sql_base.cc

@@ -8784,22 +8784,13 @@ fill_record_n_invoke_before_triggers(THD *thd, TABLE *table,
 
   if (!result && triggers)
   {
-    void *save_bulk_param= thd->bulk_param;
-    /*
-      Reset the sentinel thd->bulk_param in order not to consume the next
-      values of a bound array in case one of statement executed by
-      the trigger's body is INSERT statement.
-    */
-    thd->bulk_param= nullptr;
 
     if (triggers->process_triggers(thd, event, TRG_ACTION_BEFORE,
                                     TRUE) ||
         not_null_fields_have_null_values(table))
     {
-      thd->bulk_param= save_bulk_param;
       return TRUE;
     }
-    thd->bulk_param= save_bulk_param;
 
     /*
       Re-calculate virtual fields to cater for cases when base columns are

sql/sql_delete.cc

@@ -812,17 +812,13 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
                                               delete_history);
     if (delete_record)
     {
-      void *save_bulk_param= thd->bulk_param;
-      thd->bulk_param= nullptr;
       if (!delete_history && table->triggers &&
           table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
                                             TRG_ACTION_BEFORE, FALSE))
       {
         error= 1;
-        thd->bulk_param= save_bulk_param;
         break;
       }
-      thd->bulk_param= save_bulk_param;
 
       // no LIMIT / OFFSET
       if (returning && result->send_data(returning->item_list) < 0)
@@ -853,16 +849,13 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
       if (likely(!error))
       {
 	deleted++;
-	thd->bulk_param= nullptr;
         if (!delete_history && table->triggers &&
             table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
                                               TRG_ACTION_AFTER, FALSE))
         {
           error= 1;
-          thd->bulk_param= save_bulk_param;
           break;
         }
-        thd->bulk_param= save_bulk_param;
 	if (!--limit && using_limit)
 	{
 	  error= -1;

sql/sql_insert.cc

@@ -1069,21 +1069,12 @@ bool mysql_insert(THD *thd, TABLE_LIST *table_list,
         }
         table->reset_default_fields();
 
-        /*
-          Reset the sentinel thd->bulk_param in order not to consume the next
-          values of a bound array in case one of statement executed by
-          the trigger's body is INSERT statement.
-        */
-        void *save_bulk_param= thd->bulk_param;
-        thd->bulk_param= nullptr;
-
         if (unlikely(fill_record_n_invoke_before_triggers(thd, table,
                                                           table->
                                                           field_to_fill(),
                                                           *values, 0,
                                                           TRG_EVENT_INSERT)))
         {
-          thd->bulk_param= save_bulk_param;
           if (values_list.elements != 1 && ! thd->is_error())
 	  {
 	    info.records++;
@@ -1092,7 +1083,6 @@ bool mysql_insert(THD *thd, TABLE_LIST *table_list,
 	  error=1;
 	  break;
         }
-        thd->bulk_param= save_bulk_param;
       }
 
       /*

sql/sql_trigger.cc

@@ -2288,6 +2288,14 @@ bool Table_triggers_list::process_triggers(THD *thd,
   */
   save_current_select= thd->lex->current_select;
 
+  /*
+    Reset the sentinel thd->bulk_param in order not to consume the next
+    values of a bound array in case one of statement executed by
+    the trigger's body is a DML statement.
+  */
+  void *save_bulk_param= thd->bulk_param;
+  thd->bulk_param= nullptr;
+
   do {
     thd->lex->current_select= NULL;
     err_status=
@@ -2297,6 +2305,7 @@ bool Table_triggers_list::process_triggers(THD *thd,
                                      &trigger->subject_table_grants);
     status_var_increment(thd->status_var.executed_triggers);
   } while (!err_status && (trigger= trigger->next));
+  thd->bulk_param= save_bulk_param;
   thd->lex->current_select= save_current_select;
 
   thd->restore_sub_statement_state(&statement_state);

sql/sql_update.cc

@@ -1161,19 +1161,14 @@ error:
         rows_inserted++;
       }
 
-      void *save_bulk_param= thd->bulk_param;
-      thd->bulk_param= nullptr;
-
       if (table->triggers &&
           unlikely(table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
                                                      TRG_ACTION_AFTER, TRUE)))
       {
         error= 1;
-        thd->bulk_param= save_bulk_param;
 
         break;
       }
-      thd->bulk_param= save_bulk_param;
 
       if (!--limit && using_limit)
       {

tests/mysql_client_test.c

@@ -22503,6 +22503,129 @@ static void  test_mdev_34718_ad()
   rc= mysql_query(mysql, "DROP TABLE t1, t2");
   myquery(rc);
 }
+
+/* Test case for bulk INSERT in presence of AFTER INSERT trigger */
+static void test_mdev_34958()
+{
+  int        rc;
+  MYSQL_STMT *stmt_insert;
+  MYSQL_BIND bind[2];
+  MYSQL_RES *result;
+  MYSQL_ROW row;
+  my_ulonglong row_count;
+  unsigned int vals[] = { 1, 2, 3};
+  unsigned int vals_array_len = 3;
+  const char *insert_stmt= "INSERT INTO t1 VALUES (?)";
+
+  /* Set up test's environment */
+  rc= mysql_query(mysql, "CREATE TABLE t1 (a INT)");
+  myquery(rc);
+
+  rc= mysql_query(mysql, "CREATE TABLE t2 (a INT)");
+  myquery(rc);
+
+  rc= mysql_query(mysql, "CREATE TRIGGER t1_ai AFTER INSERT ON t1 "
+                  "FOR EACH ROW INSERT INTO t2 VALUES (NEW.a);");
+
+  stmt_insert = mysql_stmt_init(mysql);
+  if (!stmt_insert)
+  {
+    fprintf(stderr, "mysql_stmt_init failed: Error: %s\n",
+            mysql_error(mysql));
+    exit(1);
+  }
+
+  rc= mysql_stmt_prepare(stmt_insert, insert_stmt, strlen(insert_stmt));
+  if (rc)
+  {
+    fprintf(stderr, "mysql_stmt_prepare failed: %s\n",
+            mysql_stmt_error(stmt_insert));
+    exit(1);
+  }
+
+  memset(&bind[0], 0, sizeof(MYSQL_BIND));
+
+  bind[0].buffer_type= MYSQL_TYPE_LONG;
+  bind[0].buffer= vals;
+
+  rc= mysql_stmt_attr_set(stmt_insert, STMT_ATTR_ARRAY_SIZE, &vals_array_len);
+  if (rc)
+  {
+    fprintf(stderr, "mysql_stmt_prepare failed: %s\n",
+            mysql_stmt_error(stmt_insert));
+    exit(1);
+  }
+
+  rc= mysql_stmt_bind_param(stmt_insert, bind);
+  if (rc)
+  {
+    fprintf(stderr, "mysql_stmt_bind_param failed: %s\n",
+            mysql_stmt_error(stmt_insert));
+    exit(1);
+  }
+
+  rc= mysql_stmt_execute(stmt_insert);
+  if (rc)
+  {
+    fprintf(stderr, "mysql_stmt_execute failed: %s\n",
+            mysql_stmt_error(stmt_insert));
+    exit(1);
+  }
+
+  /*
+    It's expected that the INSERT statement adds three rows into
+    the table t1
+  */
+  row_count = mysql_stmt_affected_rows(stmt_insert);
+  if (row_count != 3)
+  {
+    fprintf(stderr, "Wrong number of affected rows (%llu), expected 3\n",
+            row_count);
+    exit(1);
+  }
+
+  /*
+   * Check that the AFTER INSERT trigger of the table t1 does work correct
+   * and inserted the rows (1), (2), (3) into the table t2.
+   */
+  rc= mysql_query(mysql, "SELECT 't1' tname, a FROM t1 "
+                  "UNION SELECT 't2' tname, a FROM t2 ORDER BY tname, a");
+  if (rc)
+  {
+    fprintf(stderr, "Query failed: %s\n", mysql_error(mysql));
+  }
+
+  result= mysql_store_result(mysql);
+
+  row= mysql_fetch_row(result);
+  DIE_UNLESS(strcmp(row[0], "t1") == 0 && atoi(row[1]) == 1);
+
+  row= mysql_fetch_row(result);
+  DIE_UNLESS(strcmp(row[0], "t1") == 0 && atoi(row[1]) == 2);
+
+  row= mysql_fetch_row(result);
+  DIE_UNLESS(strcmp(row[0], "t1") == 0 && atoi(row[1]) == 3);
+
+  row= mysql_fetch_row(result);
+  DIE_UNLESS(strcmp(row[0], "t2") == 0 && atoi(row[1]) == 1);
+
+  row= mysql_fetch_row(result);
+  DIE_UNLESS(strcmp(row[0], "t2") == 0 && atoi(row[1]) == 2);
+
+  row= mysql_fetch_row(result);
+  DIE_UNLESS(strcmp(row[0], "t2") == 0 && atoi(row[1]) == 3);
+
+  row= mysql_fetch_row(result);
+  DIE_UNLESS(row == NULL);
+
+  mysql_free_result(result);
+
+  mysql_stmt_close(stmt_insert);
+
+  /* Clean up */
+  rc= mysql_query(mysql, "DROP TABLE t1, t2");
+  myquery(rc);
+}
 #endif // EMBEDDED_LIBRARY
 
 /*
@@ -22856,6 +22979,7 @@ static struct my_tests_st my_tests[]= {
   { "test_mdev_34718_au", test_mdev_34718_au },
   { "test_mdev_34718_bd", test_mdev_34718_bd },
   { "test_mdev_34718_ad", test_mdev_34718_ad },
+  { "test_mdev_34958", test_mdev_34958 },
 #endif
   { 0, 0 }
 };