rt/lio_listio.c

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