From 06164d5dd5d0f2e47850d6823d37645c21f892e8 Mon Sep 17 00:00:00 2001
From: unknown <bar@mysql.com>
Date: Thu, 20 Oct 2005 11:56:27 +0500
Subject: [PATCH]    Bug#12371: executing prepared statement fails (illegal mix
 of collations) ctype_utf8.test, ctype_utf8.result:   Adding test case.
 item.h: item.cc:   Adding Item_param::safe_charset_converter

sql/item.cc:
   Bug#12371: executing prepared statement fails (illegal mix of collations)
  Adding Item_param::safe_charset_converter
sql/item.h:
  Adding Item_param::safe_charset_converter
mysql-test/r/ctype_utf8.result:
  Adding test case.
mysql-test/t/ctype_utf8.test:
  Adding test case.
---
 mysql-test/r/ctype_utf8.result | 17 +++++++++++++++++
 mysql-test/t/ctype_utf8.test   | 17 +++++++++++++++++
 sql/item.cc                    | 28 +++++++++++++++++++++++++++-
 sql/item.h                     |  1 +
 4 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/ctype_utf8.result b/mysql-test/r/ctype_utf8.result
index 29133c53cf9..405eff25746 100644
--- a/mysql-test/r/ctype_utf8.result
+++ b/mysql-test/r/ctype_utf8.result
@@ -1131,3 +1131,20 @@ a
 i
 い
 drop table t1,t2;
+set names utf8;
+create table t1 (a char(10), b varchar(10));
+insert into t1 values ('bar','kostja');
+insert into t1 values ('kostja','bar');
+prepare my_stmt from "select * from t1 where a=?";
+set @a:='bar';
+execute my_stmt using @a;
+a	b
+bar	kostja
+set @a:='kostja';
+execute my_stmt using @a;
+a	b
+kostja	bar
+set @a:=null;
+execute my_stmt using @a;
+a	b
+drop table if exists t1;
diff --git a/mysql-test/t/ctype_utf8.test b/mysql-test/t/ctype_utf8.test
index 6628175198c..fb6f2f58e35 100644
--- a/mysql-test/t/ctype_utf8.test
+++ b/mysql-test/t/ctype_utf8.test
@@ -916,3 +916,20 @@ insert into t1 values('a'),('a'),(0xE38182),(0xE38182);
 insert into t1 values('i'),('i'),(0xE38184),(0xE38184);
 select * from t1 union distinct select * from t2;
 drop table t1,t2;
+
+
+#
+# Bug#12371: executing prepared statement fails (illegal mix of collations)
+#
+set names utf8;
+create table t1 (a char(10), b varchar(10));
+insert into t1 values ('bar','kostja');
+insert into t1 values ('kostja','bar');
+prepare my_stmt from "select * from t1 where a=?";
+set @a:='bar';
+execute my_stmt using @a;
+set @a:='kostja';
+execute my_stmt using @a;
+set @a:=null;
+execute my_stmt using @a;
+drop table if exists t1;
diff --git a/sql/item.cc b/sql/item.cc
index 3d05cc19c08..b2aca750475 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -696,6 +696,32 @@ Item *Item_string::safe_charset_converter(CHARSET_INFO *tocs)
 }
 
 
+Item *Item_param::safe_charset_converter(CHARSET_INFO *tocs)
+{
+  if (const_item())
+  {
+    Item_string *conv;
+    uint cnv_errors;
+    char buf[MAX_FIELD_WIDTH];
+    String tmp(buf, sizeof(buf), &my_charset_bin);
+    String cstr, *ostr= val_str(&tmp);
+    /*
+      As safe_charset_converter is not executed for
+      a parameter bound to NULL, ostr should never be 0.
+    */
+    cstr.copy(ostr->ptr(), ostr->length(), ostr->charset(), tocs, &cnv_errors);
+    if (cnv_errors || !(conv= new Item_string(cstr.ptr(), cstr.length(),
+                                              cstr.charset(),
+                                              collation.derivation)))
+      return NULL;
+    conv->str_value.copy();
+    conv->str_value.mark_as_const();
+    return conv;
+  }
+  return NULL;
+}
+
+
 Item *Item_static_string_func::safe_charset_converter(CHARSET_INFO *tocs)
 {
   Item_string *conv;
@@ -1351,7 +1377,7 @@ bool agg_item_charsets(DTCollation &coll, const char *fname,
       been created in prepare. In this case register the change for
       rollback.
     */
-    if (arena)
+    if (arena && arena->is_conventional())
       *arg= conv;
     else
       thd->change_item_tree(arg, conv);
diff --git a/sql/item.h b/sql/item.h
index 7a7e080db02..3e52cbe5fd7 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -1194,6 +1194,7 @@ public:
     constant, assert otherwise. This method is called only if
     basic_const_item returned TRUE.
   */
+  Item *safe_charset_converter(CHARSET_INFO *tocs);
   Item *new_item();
   /*
     Implement by-value equality evaluation if parameter value