sysdeps/pthread/aio_cancel.c

   1 /* Cancel requests associated with given file descriptor.
   2    Copyright (C) 1997-2015 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 #include <fcntl.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           pthread_mutex_unlock (&__aio_requests_mutex);
  66           __set_errno (EINVAL);
  67           return -1;
  68         }
  69       else if (aiocbp->__error_code == EINPROGRESS)
  70         {
  71           struct requestlist *last = NULL;
  72
  73           req = __aio_find_req_fd (fildes);
  74
  75           if (req == NULL)
  76             {
  77             not_found:
  78               pthread_mutex_unlock (&__aio_requests_mutex);
  79               __set_errno (EINVAL);
  80               return -1;
  81             }
  82
  83           while (req->aiocbp != (aiocb_union *) aiocbp)
  84             {
  85               last = req;
  86               req = req->next_prio;
  87               if (req == NULL)
  88                 goto not_found;
  89             }
  90
  91           /* Don't remove the entry if a thread is already working on it.  */
  92           if (req->running == allocated)
  93             {
  94               result = AIO_NOTCANCELED;
  95               req = NULL;
  96             }
  97           else
  98             {
  99               /* We can remove the entry.  */
 100               __aio_remove_request (last, req, 0);
 101
 102               result = AIO_CANCELED;
 103
 104               req->next_prio = NULL;
 105             }
 106         }
 107     }
 108   else
 109     {
 110       /* Find the beginning of the list of all requests for this
 111          desriptor.  */
 112       req = __aio_find_req_fd (fildes);
 113
 114       /* If any request is worked on by a thread it must be the first.
 115          So either we can delete all requests or all but the first.  */
 116       if (req != NULL)
 117         {
 118           if (req->running == allocated)
 119             {
 120               struct requestlist *old = req;
 121               req = req->next_prio;
 122               old->next_prio = NULL;
 123
 124               result = AIO_NOTCANCELED;
 125
 126               if (req != NULL)
 127                 __aio_remove_request (old, req, 1);
 128             }
 129           else
 130             {
 131               result = AIO_CANCELED;
 132
 133               /* We can remove the entry.  */
 134               __aio_remove_request (NULL, req, 1);
 135             }
 136         }
 137     }
 138
 139   /* Mark requests as canceled and send signal.  */
 140   while (req != NULL)
 141     {
 142       struct requestlist *old = req;
 143       assert (req->running == yes || req->running == queued);
 144       req->aiocbp->aiocb.__error_code = ECANCELED;
 145       req->aiocbp->aiocb.__return_value = -1;
 146       __aio_notify (req);
 147       req = req->next_prio;
 148       __aio_free_request (old);
 149     }
 150
 151   /* Release the mutex.  */
 152   pthread_mutex_unlock (&__aio_requests_mutex);
 153
 154   return result;
 155 }
 156
 157 #ifndef aio_cancel
 158 weak_alias (aio_cancel, aio_cancel64)
 159 #endif