Commit 18edc55b authored by unknown's avatar unknown
Browse files

Bug#20789 Merge Subtable Rename Causes Crash 

- When a MyISAM table which belongs to a merge table union and is 
  renamed the associated file descriptors are closed on windows.
  This causes a server crash next time an insert or update is 
  performed on the merge table.
- This patch prevents the system from crashing on windows by
  checking for bad file descriptors every time the MyISAM table
  is locked by associated the merge table.


myisam/mi_locking.c:
  - Added check for bad file descriptors when table is part of merge union.
  - This patch prevents the server from crash on windows.
myisam/myisamdef.h:
  Added boolean value to indicate that this myisam table is part of
  a merge union.
myisammrg/myrg_locking.c:
  Added paramter owned_by_merge=TRUE for mi_lock_database through MYRG_TABLE struct.
parent 2247a2ab

myisam/mi_locking.c

+15 −0
Original line number Diff line number Diff line
@@ -224,6 +224,21 @@ int mi_lock_database(MI_INFO *info, int lock_type) 
      break;				/* Impossible */

    }

  }

#ifdef __WIN__

  else

  {

    /*

       Check for bad file descriptors if this table is part

       of a merge union. Failing to capture this may cause

       a crash on windows if the table is renamed and 

       later on referenced by the merge table.

     */

    if( info->owned_by_merge && (info->s)->kfile < 0 )

    {

      error = HA_ERR_NO_SUCH_TABLE;

    }

  }

#endif

  pthread_mutex_unlock(&share->intern_lock);

#if defined(FULL_LOG) || defined(_lint)

  lock_type|=(int) (flag << 8);		/* Set bit to set if real lock */

myisam/myisamdef.h

+3 −0
Original line number Diff line number Diff line
@@ -278,6 +278,9 @@ struct st_myisam_info { 
  my_bool page_changed;		/* If info->buff can't be used for rnext */

  my_bool buff_used;		/* If info->buff has to be reread for rnext */

  my_bool once_flags;           /* For MYISAMMRG */

#ifdef __WIN__

  my_bool owned_by_merge;                       /* This MyISAM table is part of a merge union */

#endif

#ifdef THREAD

  THR_LOCK_DATA lock;

#endif

myisammrg/myrg_locking.c

+12 −1
Original line number Diff line number Diff line
@@ -27,7 +27,18 @@ int myrg_lock_database(MYRG_INFO *info, int lock_type) 


  error=0;

  for (file=info->open_tables ; file != info->end_table ; file++) 

  {

#ifdef __WIN__

    /*

      Make sure this table is marked as owned by a merge table.

      The semaphore is never released as long as table remains

      in memory. This should be refactored into a more generic

      approach (observer pattern)

     */

    (file->table)->owned_by_merge = TRUE;

#endif

    if ((new_error=mi_lock_database(file->table,lock_type)))

      error=new_error;

  }

  return(error);

}