sysdeps/pthread/aio_cancel.c

   1 /* Cancel requests associated with given file descriptor.
   2    Copyright (C) 1997, 1998, 2000, 2002, 2005 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20
  21 /* We use an UGLY hack to prevent gcc from finding us cheating.  The
  22    implementation of aio_cancel and aio_cancel64 are identical and so
  23    we want to avoid code duplication by using aliases.  But gcc sees
  24    the different parameter lists and prints a warning.  We define here
  25    a function so that aio_cancel64 has no prototype.  */
  26 #ifndef aio_cancel
  27 #define aio_cancel64 XXX
  28 #include <aio.h>
  29 /* And undo the hack.  */
  30 #undef aio_cancel64
  31 #endif
  32
  33 #include <assert.h>
  34 #include <errno.h>
  35
  36 #include <aio_misc.h>
  37
  38
  39 int
  40 aio_cancel (fildes, aiocbp)
  41      int fildes;
  42      struct aiocb *aiocbp;
  43 {
  44   struct requestlist *req = NULL;
  45   int result = AIO_ALLDONE;
  46
  47   /* If fildes is invalid, error. */
  48   if (fcntl (fildes, F_GETFL) < 0)
  49     {
  50       __set_errno (EBADF);
  51       return -1;
  52     }
  53
  54   /* Request the mutex.  */
  55   pthread_mutex_lock (&__aio_requests_mutex);
  56
  57   /* We are asked to cancel a specific AIO request.  */
  58   if (aiocbp != NULL)
  59     {
  60       /* If the AIO request is not for this descriptor it has no value
  61          to look for the request block.  */
  62       if (aiocbp->aio_fildes != fildes)
  63         {
  64           pthread_mutex_unlock (&__aio_requests_mutex);
  65           __set_errno (EINVAL);
  66           return -1;
  67         }
  68       else if (aiocbp->__error_code == EINPROGRESS)
  69         {
  70           struct requestlist *last = NULL;
  71
  72           req = __aio_find_req_fd (fildes);
  73
  74           if (req == NULL)
  75             {
  76             not_found:
  77               pthread_mutex_unlock (&__aio_requests_mutex);
  78               __set_errno (EINVAL);
  79               return -1;
  80             }
  81
  82           while (req->aiocbp != (aiocb_union *) aiocbp)
  83             {
  84               last = req;
  85               req = req->next_prio;
  86               if (req == NULL)
  87                 goto not_found;
  88             }
  89
  90           /* Don't remove the entry if a thread is already working on it.  */
  91           if (req->running == allocated)
  92             {
  93               result = AIO_NOTCANCELED;
  94               req = NULL;
  95             }
  96           else
  97             {
  98               /* We can remove the entry.  */
  99               __aio_remove_request (last, req, 0);
 100
 101               result = AIO_CANCELED;
 102
 103               req->next_prio = NULL;
 104             }
 105         }
 106     }
 107   else
 108     {
 109       /* Find the beginning of the list of all requests for this
 110          desriptor.  */
 111       req = __aio_find_req_fd (fildes);
 112
 113       /* If any request is worked on by a thread it must be the first.
 114          So either we can delete all requests or all but the first.  */
 115       if (req != NULL)
 116         {
 117           if (req->running == allocated)
 118             {
 119               struct requestlist *old = req;
 120               req = req->next_prio;
 121               old->next_prio = NULL;
 122
 123               result = AIO_NOTCANCELED;
 124
 125               if (req != NULL)
 126                 __aio_remove_request (old, req, 1);
 127             }
 128           else
 129             {
 130               result = AIO_CANCELED;
 131
 132               /* We can remove the entry.  */
 133               __aio_remove_request (NULL, req, 1);
 134             }
 135         }
 136     }
 137
 138   /* Mark requests as canceled and send signal.  */
 139   while (req != NULL)
 140     {
 141       struct requestlist *old = req;
 142       assert (req->running == yes || req->running == queued);
 143       req->aiocbp->aiocb.__error_code = ECANCELED;
 144       req->aiocbp->aiocb.__return_value = -1;
 145       __aio_notify (req);
 146       req = req->next_prio;
 147       __aio_free_request (old);
 148     }
 149
 150   /* Release the mutex.  */
 151   pthread_mutex_unlock (&__aio_requests_mutex);
 152
 153   return result;
 154 }
 155
 156 #ifndef aio_cancel
 157 weak_alias (aio_cancel, aio_cancel64)
 158 #endif