rt/lio_listio.c

   1 /* Enqueue and list of read or write requests.
   2    Copyright (C) 1997, 1998, 1999, 2000, 2001 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 #include <aio.h>
  22 #include <assert.h>
  23 #include <errno.h>
  24 #include <stdlib.h>
  25 #include <unistd.h>
  26
  27 #include "aio_misc.h"
  28
  29
  30 /* We need this special structure to handle asynchronous I/O.  */
  31 struct async_waitlist
  32   {
  33     int counter;
  34     struct sigevent sigev;
  35     struct waitlist list[0];
  36   };
  37
  38
  39 int
  40 lio_listio (mode, list, nent, sig)
  41      int mode;
  42      struct aiocb *const list[];
  43      int nent;
  44      struct sigevent *sig;
  45 {
  46   struct sigevent defsigev;
  47   struct requestlist *requests[nent];
  48   int cnt;
  49   volatile int total = 0;
  50   int result = 0;
  51
  52   /* Check arguments.  */
  53   if (mode != LIO_WAIT && mode != LIO_NOWAIT)
  54     {
  55       __set_errno (EINVAL);
  56       return -1;
  57     }
  58
  59   if (sig == NULL)
  60     {
  61       defsigev.sigev_notify = SIGEV_NONE;
  62       sig = &defsigev;
  63     }
  64
  65   /* Request the mutex.  */
  66   pthread_mutex_lock (&__aio_requests_mutex);
  67
  68   /* Now we can enqueue all requests.  Since we already acquired the
  69      mutex the enqueue function need not do this.  */
  70   for (cnt = 0; cnt < nent; ++cnt)
  71     if (list[cnt] != NULL && list[cnt]->aio_lio_opcode != LIO_NOP)
  72       {
  73         list[cnt]->aio_sigevent.sigev_notify = SIGEV_NONE;
  74         requests[cnt] = __aio_enqueue_request ((aiocb_union *) list[cnt],
  75                                                list[cnt]->aio_lio_opcode);
  76
  77         if (requests[cnt] != NULL)
  78           /* Successfully enqueued.  */
  79           ++total;
  80         else
  81           /* Signal that we've seen an error.  `errno' and the error code
  82              of the aiocb will tell more.  */
  83           result = -1;
  84       }
  85     else
  86       requests[cnt] = NULL;
  87
  88   if (total == 0)
  89     {
  90       /* We don't have anything to do except signalling if we work
  91          asynchronously.  */
  92
  93       /* Release the mutex.  We do this before raising a signal since the
  94          signal handler might do a `siglongjmp' and then the mutex is
  95          locked forever.  */
  96       pthread_mutex_unlock (&__aio_requests_mutex);
  97
  98       if (mode == LIO_NOWAIT)
  99         __aio_notify_only (sig,
 100                            sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0);
 101
 102       return result;
 103     }
 104   else if (mode == LIO_WAIT)
 105     {
 106       pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 107       struct waitlist waitlist[nent];
 108       int oldstate;
 109
 110       total = 0;
 111       for (cnt = 0; cnt < nent; ++cnt)
 112         {
 113           assert (requests[cnt] == NULL || list[cnt] != NULL);
 114
 115           if (requests[cnt] != NULL && list[cnt]->aio_lio_opcode != LIO_NOP)
 116             {
 117               waitlist[cnt].cond = &cond;
 118               waitlist[cnt].next = requests[cnt]->waiting;
 119               waitlist[cnt].counterp = &total;
 120               waitlist[cnt].sigevp = NULL;
 121               waitlist[cnt].caller_pid = 0;     /* Not needed.  */
 122               requests[cnt]->waiting = &waitlist[cnt];
 123               ++total;
 124             }
 125         }
 126
 127       /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancelation
 128          points we must be careful.  We added entries to the waiting lists
 129          which we must remove.  So defer cancelation for now.  */
 130       pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
 131
 132       while (total > 0)
 133         pthread_cond_wait (&cond, &__aio_requests_mutex);
 134
 135       /* Now it's time to restore the cancelation state.  */
 136       pthread_setcancelstate (oldstate, NULL);
 137
 138       /* Release the conditional variable.  */
 139       if (pthread_cond_destroy (&cond) != 0)
 140         /* This must never happen.  */
 141         abort ();
 142     }
 143   else
 144     {
 145       struct async_waitlist *waitlist;
 146
 147       waitlist = (struct async_waitlist *)
 148         malloc (sizeof (struct async_waitlist)
 149                 + (nent * sizeof (struct waitlist)));
 150
 151       if (waitlist == NULL)
 152         {
 153           __set_errno (EAGAIN);
 154           result = -1;
 155         }
 156       else
 157         {
 158           pid_t caller_pid = sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0;
 159           total = 0;
 160
 161           for (cnt = 0; cnt < nent; ++cnt)
 162             {
 163               assert (requests[cnt] == NULL || list[cnt] != NULL);
 164
 165               if (requests[cnt] != NULL
 166                   && list[cnt]->aio_lio_opcode != LIO_NOP)
 167                 {
 168                   waitlist->list[cnt].cond = NULL;
 169                   waitlist->list[cnt].next = requests[cnt]->waiting;
 170                   waitlist->list[cnt].counterp = &waitlist->counter;
 171                   waitlist->list[cnt].sigevp = &waitlist->sigev;
 172                   waitlist->list[cnt].caller_pid = caller_pid;
 173                   requests[cnt]->waiting = &waitlist->list[cnt];
 174                   ++total;
 175                 }
 176             }
 177
 178           waitlist->counter = total;
 179           waitlist->sigev = *sig;
 180         }
 181     }
 182
 183   /* Release the mutex.  */
 184   pthread_mutex_unlock (&__aio_requests_mutex);
 185
 186   return result;
 187 }