1 files changed, 13 insertions, 7 deletions

diff --git a/mysys/charset.c b/mysys/charset.c
index 167d6b8ff6e..c2c46ba3fb4 100644
--- a/mysys/charset.c
+++ b/mysys/charset.c
@@ -419,6 +419,7 @@ CHARSET_INFO *default_charset_info = &my_charset_latin1;
 
 void add_compiled_collation(CHARSET_INFO *cs)
 {
+  DBUG_ASSERT(cs->number < array_elements(all_charsets));
   all_charsets[cs->number]= cs;
   cs->state|= MY_CS_AVAILABLE;
 }
@@ -529,14 +530,17 @@ uint get_charset_number(const char *charset_name, uint cs_flags)
 
 const char *get_charset_name(uint charset_number)
 {
-  CHARSET_INFO *cs;
   my_pthread_once(&charsets_initialized, init_available_charsets);
 
-  cs=all_charsets[charset_number];
-  if (cs && (cs->number == charset_number) && cs->name )
-    return (char*) cs->name;
+  if (charset_number < array_elements(all_charsets))
+  {
+    CHARSET_INFO *cs= all_charsets[charset_number];
+
+    if (cs && (cs->number == charset_number) && cs->name)
+      return (char*) cs->name;
+  }
   
-  return (char*) "?";   /* this mimics find_type() */
+  return "?";   /* this mimics find_type() */
 }
 
 
@@ -545,6 +549,8 @@ static CHARSET_INFO *get_internal_charset(uint cs_number, myf flags)
   char  buf[FN_REFLEN];
   CHARSET_INFO *cs;
 
+  DBUG_ASSERT(cs_number < array_elements(all_charsets));
+
   if ((cs= all_charsets[cs_number]))
   {
     if (cs->state & MY_CS_READY)  /* if CS is already initialized */
@@ -589,8 +595,8 @@ CHARSET_INFO *get_charset(uint cs_number, myf flags)
     return default_charset_info;
 
   my_pthread_once(&charsets_initialized, init_available_charsets);
-  
-  if (!cs_number || cs_number > array_elements(all_charsets))
+ 
+  if (cs_number >= array_elements(all_charsets)) 
     return NULL;
   
   cs=get_internal_charset(cs_number, flags);