rt/aio_cancel.c

   1 /* Cancel requests associated with given file descriptor.
   2    Copyright (C) 1997 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 <errno.h>
  33
  34 #include "aio_misc.h"
  35
  36
  37 /* Argh, so far there is no ECANCELED.  */
  38 #define ECANCELED 125
  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   /* Request the mutex.  */
  49   pthread_mutex_lock (&__aio_requests_mutex);
  50
  51   /* We are asked to cancel a specific AIO request.  */
  52   if (aiocbp != NULL)
  53     {
  54       /* If the AIO request is not for this descriptor it has no value
  55          to look for the request block.  */
  56       if (aiocbp->aio_fildes == fildes)
  57         {
  58           struct requestlist *last = NULL;
  59
  60           req = __aio_find_req_fd (fildes);
  61
  62           while (req->aiocbp != (aiocb_union *) aiocbp)
  63             {
  64               last = req;
  65               req = req->next_prio;
  66             }
  67
  68           /* Don't remove the entry if a thread is already working on it.  */
  69           if (req->running == allocated)
  70             result = AIO_NOTCANCELED;
  71           else
  72             {
  73               /* We can remove the entry.  */
  74               if (last != NULL)
  75                 last->next_prio = req->next_prio;
  76               else
  77                 if (req->next_prio == NULL)
  78                   {
  79                     if (req->last_fd != NULL)
  80                       req->last_fd->next_fd = req->next_fd;
  81                     if (req->next_fd != NULL)
  82                       req->next_fd->last_fd = req->last_fd;
  83                   }
  84                 else
  85                   {
  86                     if (req->last_fd != NULL)
  87                       req->last_fd->next_fd = req->next_prio;
  88                     if (req->next_fd != NULL)
  89                       req->next_fd->last_fd = req->next_prio;
  90                     req->next_prio->last_fd = req->last_fd;
  91                     req->next_prio->next_fd = req->next_fd;
  92
  93                     /* Mark this entry as runnable.  */
  94                     req->next_prio->running = yes;
  95                   }
  96
  97               result = AIO_CANCELED;
  98             }
  99
 100           req->next_prio = NULL;
 101         }
 102     }
 103   else
 104     {
 105       /* Find the beginning of the list of all requests for this
 106          desriptor.  */
 107       req = __aio_find_req_fd (fildes);
 108
 109       /* If any request is worked on by a thread it must be the first.
 110          So either we can delete all requests or all but the first.  */
 111       if (req != NULL)
 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         else
 121           {
 122             /* Remove entry from the file descriptor list.  */
 123             if (req->last_fd != NULL)
 124               req->last_fd->next_fd = req->next_fd;
 125             if (req->next_fd != NULL)
 126               req->next_fd->last_fd = req->last_fd;
 127
 128             result = AIO_CANCELED;
 129           }
 130     }
 131
 132   /* Mark requests as canceled and send signal.  */
 133   while (req != NULL)
 134     {
 135       struct requestlist *old = req;
 136       req->aiocbp->aiocb.__error_code = ECANCELED;
 137       req->aiocbp->aiocb.__return_value = -1;
 138       __aio_notify (req);
 139       req = req->next_prio;
 140       __aio_free_request (old);
 141     }
 142
 143   /* Release the mutex.  */
 144   pthread_mutex_unlock (&__aio_requests_mutex);
 145
 146   return result;
 147 }
 148
 149 weak_alias (aio_cancel, aio_cancel64)