bug with mysql_change_db() fixed

BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted

BitKeeper/etc/logging_ok

@@ -2,3 +2,4 @@ jani@hynda.mysql.fi
 heikki@donna.mysql.fi
 monty@donna.mysql.fi
 paul@central.snake.net
+serg@serg.mysql.com

Docs/manual.texi

@@ -13726,7 +13726,7 @@ in ANSI mode. @xref{ANSI mode}.
 
 @multitable @columnfractions .15 .15 .70
 @item @strong{Identifier} @tab @strong{Max length} @tab @strong{Allowed characters}
-@item Database @tab 64 @tab Any character that is allowed in a directory name except @samp{/}.
+@item Database @tab 64 @tab Any character that is allowed in a directory name except @samp{/} or @samp{.}.
 @item Table @tab 64 @tab Any character that is allowed in a file name, except @samp{/} or @samp{.}.
 @item Column @tab 64 @tab All characters.
 @item Alias @tab 255 @tab All characters.

sql/sql_db.cc

@@ -264,9 +264,10 @@ bool mysql_change_db(THD *thd,const char *name)
     send_error(&thd->net,ER_NO_DB_ERROR);	/* purecov: inspected */
     DBUG_RETURN(1);				/* purecov: inspected */
   }
-  if (length > NAME_LEN)
+  if ((length > NAME_LEN) || check_db_name(dbname))
   {
     net_printf(&thd->net,ER_WRONG_DB_NAME, dbname);
+    x_free(dbname);
     DBUG_RETURN(1);
   }
   DBUG_PRINT("general",("Use database: %s", dbname));

sql/table.cc

@@ -1052,7 +1052,7 @@ bool check_db_name(const char *name)
       }
     }
 #endif
-    if (*name == '/' || *name == FN_LIBCHAR)
+    if (*name == '/' || *name == FN_LIBCHAR || *name == FN_EXTCHAR)
       return 1;
     name++;
   }