sysdeps/pthread/lio_listio.c

   1 /* Enqueue and list of read or write requests.
   2    Copyright (C) 1997,1998,1999,2000,2001,2003 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 Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #ifndef lio_listio
  22 #include <aio.h>
  23 #include <assert.h>
  24 #include <errno.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27
  28 #include "aio_misc.h"
  29
  30 #define LIO_OPCODE_BASE 0
  31 #endif
  32
  33 /* We need this special structure to handle asynchronous I/O.  */
  34 struct async_waitlist
  35   {
  36     int counter;
  37     struct sigevent sigev;
  38     struct waitlist list[0];
  39   };
  40
  41
  42 int
  43 lio_listio (mode, list, nent, sig)
  44      int mode;
  45      struct aiocb *const list[];
  46      int nent;
  47      struct sigevent *sig;
  48 {
  49   struct sigevent defsigev;
  50   struct requestlist *requests[nent];
  51   int cnt;
  52   volatile int total = 0;
  53   int result = 0;
  54
  55   /* Check arguments.  */
  56   if (mode != LIO_WAIT && mode != LIO_NOWAIT)
  57     {
  58       __set_errno (EINVAL);
  59       return -1;
  60     }
  61
  62   if (sig == NULL)
  63     {
  64       defsigev.sigev_notify = SIGEV_NONE;
  65       sig = &defsigev;
  66     }
  67
  68   /* Request the mutex.  */
  69   pthread_mutex_lock (&__aio_requests_mutex);
  70
  71   /* Now we can enqueue all requests.  Since we already acquired the
  72      mutex the enqueue function need not do this.  */
  73   for (cnt = 0; cnt < nent; ++cnt)
  74     if (list[cnt] != NULL && list[cnt]->aio_lio_opcode != LIO_NOP)
  75       {
  76         list[cnt]->aio_sigevent.sigev_notify = SIGEV_NONE;
  77         requests[cnt] = __aio_enqueue_request ((aiocb_union *) list[cnt],
  78                                                (list[cnt]->aio_lio_opcode
  79                                                 | LIO_OPCODE_BASE));
  80
  81         if (requests[cnt] != NULL)
  82           /* Successfully enqueued.  */
  83           ++total;
  84         else
  85           /* Signal that we've seen an error.  `errno' and the error code
  86              of the aiocb will tell more.  */
  87           result = -1;
  88       }
  89     else
  90       requests[cnt] = NULL;
  91
  92   if (total == 0)
  93     {
  94       /* We don't have anything to do except signalling if we work
  95          asynchronously.  */
  96
  97       /* Release the mutex.  We do this before raising a signal since the
  98          signal handler might do a `siglongjmp' and then the mutex is
  99          locked forever.  */
 100       pthread_mutex_unlock (&__aio_requests_mutex);
 101
 102       if (mode == LIO_NOWAIT)
 103         {
 104 #ifdef BROKEN_THREAD_SIGNALS
 105         __aio_notify_only (sig,
 106                            sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0);
 107 #else
 108         __aio_notify_only (sig);
 109 #endif
 110         }
 111
 112       return result;
 113     }
 114   else if (mode == LIO_WAIT)
 115     {
 116       pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 117       struct waitlist waitlist[nent];
 118       int oldstate;
 119
 120       total = 0;
 121       for (cnt = 0; cnt < nent; ++cnt)
 122         {
 123           assert (requests[cnt] == NULL || list[cnt] != NULL);
 124
 125           if (requests[cnt] != NULL && list[cnt]->aio_lio_opcode != LIO_NOP)
 126             {
 127               waitlist[cnt].cond = &cond;
 128               waitlist[cnt].next = requests[cnt]->waiting;
 129               waitlist[cnt].counterp = &total;
 130               waitlist[cnt].sigevp = NULL;
 131 #ifdef BROKEN_THREAD_SIGNALS
 132               waitlist[cnt].caller_pid = 0;     /* Not needed.  */
 133 #endif
 134               requests[cnt]->waiting = &waitlist[cnt];
 135               ++total;
 136             }
 137         }
 138
 139       /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancelation
 140          points we must be careful.  We added entries to the waiting lists
 141          which we must remove.  So defer cancelation for now.  */
 142       pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
 143
 144       while (total > 0)
 145         pthread_cond_wait (&cond, &__aio_requests_mutex);
 146
 147       /* Now it's time to restore the cancelation state.  */
 148       pthread_setcancelstate (oldstate, NULL);
 149
 150       /* Release the conditional variable.  */
 151       if (pthread_cond_destroy (&cond) != 0)
 152         /* This must never happen.  */
 153         abort ();
 154     }
 155   else
 156     {
 157       struct async_waitlist *waitlist;
 158
 159       waitlist = (struct async_waitlist *)
 160         malloc (sizeof (struct async_waitlist)
 161                 + (nent * sizeof (struct waitlist)));
 162
 163       if (waitlist == NULL)
 164         {
 165           __set_errno (EAGAIN);
 166           result = -1;
 167         }
 168       else
 169         {
 170 #ifdef BROKEN_THREAD_SIGNALS
 171           pid_t caller_pid = sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0;
 172 #endif
 173           total = 0;
 174
 175           for (cnt = 0; cnt < nent; ++cnt)
 176             {
 177               assert (requests[cnt] == NULL || list[cnt] != NULL);
 178
 179               if (requests[cnt] != NULL
 180                   && list[cnt]->aio_lio_opcode != LIO_NOP)
 181                 {
 182                   waitlist->list[cnt].cond = NULL;
 183                   waitlist->list[cnt].next = requests[cnt]->waiting;
 184                   waitlist->list[cnt].counterp = &waitlist->counter;
 185                   waitlist->list[cnt].sigevp = &waitlist->sigev;
 186 #ifdef BROKEN_THREAD_SIGNALS
 187                   waitlist->list[cnt].caller_pid = caller_pid;
 188 #endif
 189                   requests[cnt]->waiting = &waitlist->list[cnt];
 190                   ++total;
 191                 }
 192             }
 193
 194           waitlist->counter = total;
 195           waitlist->sigev = *sig;
 196         }
 197     }
 198
 199   /* Release the mutex.  */
 200   pthread_mutex_unlock (&__aio_requests_mutex);
 201
 202   return result;
 203 }