From 3ef86918a20cb682bbc48b8f6e0848772d88f94c Mon Sep 17 00:00:00 2001
From: Sergey Glukhov <Sergey.Glukhov@sun.com>
Date: Thu, 5 Mar 2009 15:34:02 +0400
Subject: [PATCH] Bug#41030 Wrong meta data (incorrect fieldlen) set user
 variable max length on fix_length_and_dec() stage using real value length.

mysql-test/r/variables.result:
  test result
mysql-test/t/variables.test:
  test case
sql/item_func.cc:
  set user variable max length on
  fix_length_and_dec() stage
  using real value length.
---
 mysql-test/r/variables.result |  5 +++++
 mysql-test/t/variables.test   |  7 +++++++
 sql/item_func.cc              | 11 ++++++++++-
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/variables.result b/mysql-test/r/variables.result
index 0b56e3c1d52..b7ca918c38c 100644
--- a/mysql-test/r/variables.result
+++ b/mysql-test/r/variables.result
@@ -1389,3 +1389,8 @@ SET @@session.thread_stack= 7;
 ERROR HY000: Variable 'thread_stack' is a read only variable
 SET @@global.thread_stack= 7;
 ERROR HY000: Variable 'thread_stack' is a read only variable
+select @@storage_engine;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def					@@storage_engine	253	6	6	N	1	31	8
+@@storage_engine
+MyISAM
diff --git a/mysql-test/t/variables.test b/mysql-test/t/variables.test
index 6cd5abc3ea2..2797bb3c801 100644
--- a/mysql-test/t/variables.test
+++ b/mysql-test/t/variables.test
@@ -1121,3 +1121,10 @@ SET @@session.thread_stack= 7;
 --error ER_INCORRECT_GLOBAL_LOCAL_VAR
 SET @@global.thread_stack= 7;
 #
+
+#
+# Bug#41030 Wrong meta data (incorrect fieldlen)
+#
+--enable_metadata
+select @@storage_engine;
+--disable_metadata
diff --git a/sql/item_func.cc b/sql/item_func.cc
index ec95254baaa..67bf9b3319f 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -4837,7 +4837,10 @@ bool Item_func_get_system_var::is_written_to_binlog()
 
 void Item_func_get_system_var::fix_length_and_dec()
 {
+  char *cptr;
+  int well_formed_error;
   maybe_null=0;
+  max_length= 0;
 
   if (var->check_type(var_type))
   {
@@ -4867,8 +4870,14 @@ void Item_func_get_system_var::fix_length_and_dec()
       break;
     case SHOW_CHAR:
     case SHOW_CHAR_PTR:
+      pthread_mutex_lock(&LOCK_global_system_variables);
+      cptr= var->show_type() == SHOW_CHAR_PTR ? 
+        *(char**) var->value_ptr(current_thd, var_type, &component) :
+        (char*) var->value_ptr(current_thd, var_type, &component);
+      if (cptr)
+        max_length= strlen(cptr) * system_charset_info->mbmaxlen;
+      pthread_mutex_unlock(&LOCK_global_system_variables);
       collation.set(system_charset_info, DERIVATION_SYSCONST);
-      max_length= MAX_BLOB_WIDTH;
       decimals=NOT_FIXED_DEC;
       break;
     case SHOW_BOOL: