rt/aio_cancel.c

   1 /* Cancel requests associated with given file descriptor.
   2    Copyright (C) 1997, 1998, 2000 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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 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 #define aio_cancel64 XXX
  28 #include <aio.h>
  29 /* And undo the hack.  */
  30 #undef aio_cancel64
  31
  32 #include <assert.h>
  33 #include <errno.h>
  34
  35 #include "aio_misc.h"
  36
  37
  38 int
  39 aio_cancel (fildes, aiocbp)
  40      int fildes;
  41      struct aiocb *aiocbp;
  42 {
  43   struct requestlist *req = NULL;
  44   int result = AIO_ALLDONE;
  45
  46   /* Request the mutex.  */
  47   pthread_mutex_lock (&__aio_requests_mutex);
  48
  49   /* We are asked to cancel a specific AIO request.  */
  50   if (aiocbp != NULL)
  51     {
  52       /* If the AIO request is not for this descriptor it has no value
  53          to look for the request block.  */
  54       if (aiocbp->aio_fildes == fildes)
  55         {
  56           struct requestlist *last = NULL;
  57
  58           req = __aio_find_req_fd (fildes);
  59
  60           if (req == NULL)
  61             {
  62             not_found:
  63               pthread_mutex_unlock (&__aio_requests_mutex);
  64               __set_errno (EINVAL);
  65               return -1;
  66             }
  67
  68           while (req->aiocbp != (aiocb_union *) aiocbp)
  69             {
  70               last = req;
  71               req = req->next_prio;
  72               if (req == NULL)
  73                 goto not_found;
  74             }
  75
  76           /* Don't remove the entry if a thread is already working on it.  */
  77           if (req->running == allocated)
  78             {
  79               result = AIO_NOTCANCELED;
  80               req = NULL;
  81             }
  82           else
  83             {
  84               /* We can remove the entry.  */
  85               __aio_remove_request (last, req, 0);
  86
  87               result = AIO_CANCELED;
  88
  89               req->next_prio = NULL;
  90             }
  91         }
  92     }
  93   else
  94     {
  95       /* Find the beginning of the list of all requests for this
  96          desriptor.  */
  97       req = __aio_find_req_fd (fildes);
  98
  99       /* If any request is worked on by a thread it must be the first.
 100          So either we can delete all requests or all but the first.  */
 101       if (req != NULL)
 102         {
 103           if (req->running == allocated)
 104             {
 105               struct requestlist *old = req;
 106               req = req->next_prio;
 107               old->next_prio = NULL;
 108
 109               result = AIO_NOTCANCELED;
 110
 111               if (req != NULL)
 112                 __aio_remove_request (old, req, 1);
 113             }
 114           else
 115             {
 116               result = AIO_CANCELED;
 117
 118               /* We can remove the entry.  */
 119               __aio_remove_request (NULL, req, 1);
 120             }
 121         }
 122     }
 123
 124   /* Mark requests as canceled and send signal.  */
 125   while (req != NULL)
 126     {
 127       struct requestlist *old = req;
 128       assert (req->running == yes || req->running == queued);
 129       req->aiocbp->aiocb.__error_code = ECANCELED;
 130       req->aiocbp->aiocb.__return_value = -1;
 131       __aio_notify (req);
 132       req = req->next_prio;
 133       __aio_free_request (old);
 134     }
 135
 136   /* Release the mutex.  */
 137   pthread_mutex_unlock (&__aio_requests_mutex);
 138
 139   return result;
 140 }
 141
 142 weak_alias (aio_cancel, aio_cancel64)