Fix for BUG#25082: default database change on trigger

execution breaks replication.

When a stored routine is executed, we switch current
database to the database, in which the routine
has been created. When the stored routine finishes,
we switch back to the original database.

The problem was that if the original database does not
exist (anymore) after routine execution, we raised an error.

The fix is to report a warning, and switch to the NULL database.

1 files changed, 15 insertions, 9 deletions

diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 486942a8bb9..cbf9e374dac 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -290,7 +290,8 @@ int check_user(THD *thd, enum enum_server_command command,
 	       bool check_count)
 {
   DBUG_ENTER("check_user");
-  
+  LEX_STRING db_str= { (char *) db, db ? strlen(db) : 0 };
+
 #ifdef NO_EMBEDDED_ACCESS_CHECKS
   thd->main_security_ctx.master_access= GLOBAL_ACLS;       // Full rights
   /* Change database if necessary */
@@ -301,7 +302,7 @@ int check_user(THD *thd, enum enum_server_command command,
       function returns 0
     */
     thd->reset_db(NULL, 0);
-    if (mysql_change_db(thd, db, FALSE))
+    if (mysql_change_db(thd, &db_str, FALSE))
     {
       /* Send the error to the client */
       net_send_error(thd);
@@ -443,7 +444,7 @@ int check_user(THD *thd, enum enum_server_command command,
       /* Change database if necessary */
       if (db && db[0])
       {
-        if (mysql_change_db(thd, db, FALSE))
+        if (mysql_change_db(thd, &db_str, FALSE))
         {
           /* Send error to the client */
           net_send_error(thd);
@@ -1638,7 +1639,7 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
 			&LOCK_status);
     thd->convert_string(&tmp, system_charset_info,
 			packet, strlen(packet), thd->charset());
-    if (!mysql_change_db(thd, tmp.str, FALSE))
+    if (!mysql_change_db(thd, &tmp, FALSE))
     {
       mysql_log.write(thd,command,"%s",thd->db);
       send_ok(thd);
@@ -1862,7 +1863,7 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
     packet= pend+1;
 
     if (!my_strcasecmp(system_charset_info, table_list.db,
-                       information_schema_name.str))
+                       INFORMATION_SCHEMA_NAME.str))
     {
       ST_SCHEMA_TABLE *schema_table= find_schema_table(thd, table_list.alias);
       if (schema_table)
@@ -3753,9 +3754,14 @@ end_with_restore_list:
     }
 #endif
   case SQLCOM_CHANGE_DB:
-    if (!mysql_change_db(thd,select_lex->db,FALSE))
+  {
+    LEX_STRING db_str= { (char *) select_lex->db, strlen(select_lex->db) };
+
+    if (!mysql_change_db(thd, &db_str, FALSE))
       send_ok(thd);
+
     break;
+  }
 
   case SQLCOM_LOAD:
   {
@@ -5436,7 +5442,7 @@ check_table_access(THD *thd, ulong want_access,TABLE_LIST *tables,
       if (!no_errors)
         my_error(ER_DBACCESS_DENIED_ERROR, MYF(0),
                  sctx->priv_user, sctx->priv_host,
-                 information_schema_name.str);
+                 INFORMATION_SCHEMA_NAME.str);
       return TRUE;
     }
     /*
@@ -6256,7 +6262,7 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd,
   ptr->ignore_leaves= test(table_options & TL_OPTION_IGNORE_LEAVES);
   ptr->derived=	    table->sel;
   if (!ptr->derived && !my_strcasecmp(system_charset_info, ptr->db,
-                                      information_schema_name.str))
+                                      INFORMATION_SCHEMA_NAME.str))
   {
     ST_SCHEMA_TABLE *schema_table= find_schema_table(thd, ptr->table_name);
     if (!schema_table ||
@@ -6264,7 +6270,7 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd,
          lex->orig_sql_command == SQLCOM_END))  // not a 'show' command
     {
       my_error(ER_UNKNOWN_TABLE, MYF(0),
-               ptr->table_name, information_schema_name.str);
+               ptr->table_name, INFORMATION_SCHEMA_NAME.str);
       DBUG_RETURN(0);
     }
     ptr->schema_table_name= ptr->table_name;