rt/aio_cancel.c

   1 /* Cancel requests associated with given file descriptor.
   2    Copyright (C) 1997, 1998 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 int
  38 aio_cancel (fildes, aiocbp)
  39      int fildes;
  40      struct aiocb *aiocbp;
  41 {
  42   struct requestlist *req = NULL;
  43   int result = AIO_ALLDONE;
  44
  45   /* Request the mutex.  */
  46   pthread_mutex_lock (&__aio_requests_mutex);
  47
  48   /* We are asked to cancel a specific AIO request.  */
  49   if (aiocbp != NULL)
  50     {
  51       /* If the AIO request is not for this descriptor it has no value
  52          to look for the request block.  */
  53       if (aiocbp->aio_fildes == fildes)
  54         {
  55           struct requestlist *last = NULL;
  56
  57           req = __aio_find_req_fd (fildes);
  58
  59           while (req->aiocbp != (aiocb_union *) aiocbp)
  60             {
  61               last = req;
  62               req = req->next_prio;
  63             }
  64
  65           /* Don't remove the entry if a thread is already working on it.  */
  66           if (req->running == allocated)
  67             result = AIO_NOTCANCELED;
  68           else
  69             {
  70               /* We can remove the entry.  */
  71               if (last != NULL)
  72                 last->next_prio = req->next_prio;
  73               else
  74                 if (req->next_prio == NULL)
  75                   {
  76                     if (req->last_fd != NULL)
  77                       req->last_fd->next_fd = req->next_fd;
  78                     if (req->next_fd != NULL)
  79                       req->next_fd->last_fd = req->last_fd;
  80                   }
  81                 else
  82                   {
  83                     if (req->last_fd != NULL)
  84                       req->last_fd->next_fd = req->next_prio;
  85                     if (req->next_fd != NULL)
  86                       req->next_fd->last_fd = req->next_prio;
  87                     req->next_prio->last_fd = req->last_fd;
  88                     req->next_prio->next_fd = req->next_fd;
  89
  90                     /* Mark this entry as runnable.  */
  91                     req->next_prio->running = yes;
  92                   }
  93
  94               result = AIO_CANCELED;
  95             }
  96
  97           req->next_prio = NULL;
  98         }
  99     }
 100   else
 101     {
 102       /* Find the beginning of the list of all requests for this
 103          desriptor.  */
 104       req = __aio_find_req_fd (fildes);
 105
 106       /* If any request is worked on by a thread it must be the first.
 107          So either we can delete all requests or all but the first.  */
 108       if (req != NULL)
 109         {
 110           if (req->running == allocated)
 111             {
 112               struct requestlist *old = req;
 113               req = req->next_prio;
 114               old->next_prio = NULL;
 115
 116               result = AIO_NOTCANCELED;
 117             }
 118           else
 119             {
 120               /* Remove entry from the file descriptor list.  */
 121               if (req->last_fd != NULL)
 122                 req->last_fd->next_fd = req->next_fd;
 123               if (req->next_fd != NULL)
 124                 req->next_fd->last_fd = req->last_fd;
 125
 126               result = AIO_CANCELED;
 127             }
 128         }
 129     }
 130
 131   /* Mark requests as canceled and send signal.  */
 132   while (req != NULL)
 133     {
 134       struct requestlist *old = req;
 135       req->aiocbp->aiocb.__error_code = ECANCELED;
 136       req->aiocbp->aiocb.__return_value = -1;
 137       __aio_notify (req);
 138       req = req->next_prio;
 139       __aio_free_request (old);
 140     }
 141
 142   /* Release the mutex.  */
 143   pthread_mutex_unlock (&__aio_requests_mutex);
 144
 145   return result;
 146 }
 147
 148 weak_alias (aio_cancel, aio_cancel64)