A patch for Bug#11763166 (55847: SHOW WARNINGS returns empty

result set when SQLEXCEPTION is active.

The problem was in a hackish THD::no_warnings_for_error attribute.
When it was set, an error was not written to Warning_info -- only
Diagnostics_area state was changed. That means, Diagnostics_area
might contain error state, which is not present in Warning_info.

The user-visible problem was that in some cases SHOW WARNINGS
returned empty result set (i.e. there were no warnings) while
the previous SQL statement failed. According to the MySQL
protocol errors must be presented in warning list.

The main idea of this patch is to remove THD::no_warnings_for_error.
There were few places where it was used:
  - sql_admin.cc, handling of REPAIR TABLE USE_FRM.
  - sql_show.cc, when calling fill_schema_table_from_frm().
  - sql_show.cc, when calling fill_table().
The fix is to either use internal-error-handlers, or to use
temporary Warning_info storing warnings, which might be ignored.

This patch is needed to fix Bug 11763162 (55843).

1 files changed, 19 insertions, 4 deletions

diff --git a/sql/sql_error.cc b/sql/sql_error.cc
index d0982b879e7..24516f03bee 100644
--- a/sql/sql_error.cc
+++ b/sql/sql_error.cc
@@ -1,5 +1,4 @@
-/* Copyright (C) 1995-2002 MySQL AB,
-   Copyright (C) 2008-2009 Sun Microsystems, Inc
+/* Copyright (c) 1995, 2011, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -458,10 +457,11 @@ Diagnostics_area::disable_status()
   m_status= DA_DISABLED;
 }
 
-Warning_info::Warning_info(ulonglong warn_id_arg)
+Warning_info::Warning_info(ulonglong warn_id_arg, bool allow_unlimited_warnings)
   :m_statement_warn_count(0),
   m_current_row_for_warning(1),
   m_warn_id(warn_id_arg),
+  m_allow_unlimited_warnings(allow_unlimited_warnings),
   m_read_only(FALSE)
 {
   /* Initialize sub structures */
@@ -543,7 +543,8 @@ MYSQL_ERROR *Warning_info::push_warning(THD *thd,
 
   if (! m_read_only)
   {
-    if (m_warn_list.elements < thd->variables.max_error_count)
+    if (m_allow_unlimited_warnings ||
+        m_warn_list.elements < thd->variables.max_error_count)
     {
       cond= new (& m_warn_root) MYSQL_ERROR(& m_warn_root);
       if (cond)
@@ -559,6 +560,20 @@ MYSQL_ERROR *Warning_info::push_warning(THD *thd,
   return cond;
 }
 
+MYSQL_ERROR *Warning_info::push_warning(THD *thd, const MYSQL_ERROR *sql_condition)
+{
+  MYSQL_ERROR *new_condition= push_warning(thd,
+                                           sql_condition->get_sql_errno(),
+                                           sql_condition->get_sqlstate(),
+                                           sql_condition->get_level(),
+                                           sql_condition->get_message_text());
+
+  if (new_condition)
+    new_condition->copy_opt_attributes(sql_condition);
+
+  return new_condition;
+}
+
 /*
   Push the warning to error list if there is still room in the list