rt/lio_listio.c

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