sysdeps/pthread/aio_cancel.c

   1 /* Cancel requests associated with given file descriptor.
   2    Copyright (C) 1997, 1998, 2000, 2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21
  22 /* We use an UGLY hack to prevent gcc from finding us cheating.  The
  23    implementation of aio_cancel and aio_cancel64 are identical and so
  24    we want to avoid code duplication by using aliases.  But gcc sees
  25    the different parameter lists and prints a warning.  We define here
  26    a function so that aio_cancel64 has no prototype.  */
  27 #ifndef aio_cancel
  28 #define aio_cancel64 XXX
  29 #include <aio.h>
  30 /* And undo the hack.  */
  31 #undef aio_cancel64
  32 #endif
  33
  34 #include <assert.h>
  35 #include <errno.h>
  36
  37 #include "aio_misc.h"
  38
  39
  40 int
  41 aio_cancel (fildes, aiocbp)
  42      int fildes;
  43      struct aiocb *aiocbp;
  44 {
  45   struct requestlist *req = NULL;
  46   int result = AIO_ALLDONE;
  47
  48   /* If fildes is invalid, error. */
  49   if (fcntl (fildes, F_GETFL) < 0)
  50     {
  51       __set_errno (EBADF);
  52       return -1;
  53     }
  54
  55   /* Request the mutex.  */
  56   pthread_mutex_lock (&__aio_requests_mutex);
  57
  58   /* We are asked to cancel a specific AIO request.  */
  59   if (aiocbp != NULL)
  60     {
  61       /* If the AIO request is not for this descriptor it has no value
  62          to look for the request block.  */
  63       if (aiocbp->aio_fildes == fildes)
  64         {
  65           struct requestlist *last = NULL;
  66
  67           req = __aio_find_req_fd (fildes);
  68
  69           if (req == NULL)
  70             {
  71             not_found:
  72               pthread_mutex_unlock (&__aio_requests_mutex);
  73               __set_errno (EINVAL);
  74               return -1;
  75             }
  76
  77           while (req->aiocbp != (aiocb_union *) aiocbp)
  78             {
  79               last = req;
  80               req = req->next_prio;
  81               if (req == NULL)
  82                 goto not_found;
  83             }
  84
  85           /* Don't remove the entry if a thread is already working on it.  */
  86           if (req->running == allocated)
  87             {
  88               result = AIO_NOTCANCELED;
  89               req = NULL;
  90             }
  91           else
  92             {
  93               /* We can remove the entry.  */
  94               __aio_remove_request (last, req, 0);
  95
  96               result = AIO_CANCELED;
  97
  98               req->next_prio = NULL;
  99             }
 100         }
 101     }
 102   else
 103     {
 104       /* Find the beginning of the list of all requests for this
 105          desriptor.  */
 106       req = __aio_find_req_fd (fildes);
 107
 108       /* If any request is worked on by a thread it must be the first.
 109          So either we can delete all requests or all but the first.  */
 110       if (req != NULL)
 111         {
 112           if (req->running == allocated)
 113             {
 114               struct requestlist *old = req;
 115               req = req->next_prio;
 116               old->next_prio = NULL;
 117
 118               result = AIO_NOTCANCELED;
 119
 120               if (req != NULL)
 121                 __aio_remove_request (old, req, 1);
 122             }
 123           else
 124             {
 125               result = AIO_CANCELED;
 126
 127               /* We can remove the entry.  */
 128               __aio_remove_request (NULL, req, 1);
 129             }
 130         }
 131     }
 132
 133   /* Mark requests as canceled and send signal.  */
 134   while (req != NULL)
 135     {
 136       struct requestlist *old = req;
 137       assert (req->running == yes || req->running == queued);
 138       req->aiocbp->aiocb.__error_code = ECANCELED;
 139       req->aiocbp->aiocb.__return_value = -1;
 140       __aio_notify (req);
 141       req = req->next_prio;
 142       __aio_free_request (old);
 143     }
 144
 145   /* Release the mutex.  */
 146   pthread_mutex_unlock (&__aio_requests_mutex);
 147
 148   return result;
 149 }
 150
 151 #ifndef aio_cancel
 152 weak_alias (aio_cancel, aio_cancel64)
 153 #endif