sysdeps/pthread/lio_listio.c

   1 /* Enqueue and list of read or write requests.
   2    Copyright (C) 1997,1998,1999,2000,2001,2003,2005
   3         Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 #ifndef lio_listio
  23 #include <aio.h>
  24 #include <assert.h>
  25 #include <errno.h>
  26 #include <stdlib.h>
  27 #include <unistd.h>
  28
  29 #include <aio_misc.h>
  30
  31 #define LIO_OPCODE_BASE 0
  32 #endif
  33
  34 /* We need this special structure to handle asynchronous I/O.  */
  35 struct async_waitlist
  36   {
  37     int counter;
  38     struct sigevent sigev;
  39     struct waitlist list[0];
  40   };
  41
  42
  43 int
  44 lio_listio (mode, list, nent, sig)
  45      int mode;
  46      struct aiocb *const list[];
  47      int nent;
  48      struct sigevent *sig;
  49 {
  50   struct sigevent defsigev;
  51   struct requestlist *requests[nent];
  52   int cnt;
  53   volatile int total = 0;
  54   int result = 0;
  55
  56   /* Check arguments.  */
  57   if (mode != LIO_WAIT && mode != LIO_NOWAIT)
  58     {
  59       __set_errno (EINVAL);
  60       return -1;
  61     }
  62
  63   if (sig == NULL)
  64     {
  65       defsigev.sigev_notify = SIGEV_NONE;
  66       sig = &defsigev;
  67     }
  68
  69   /* Request the mutex.  */
  70   pthread_mutex_lock (&__aio_requests_mutex);
  71
  72   /* Now we can enqueue all requests.  Since we already acquired the
  73      mutex the enqueue function need not do this.  */
  74   for (cnt = 0; cnt < nent; ++cnt)
  75     if (list[cnt] != NULL && list[cnt]->aio_lio_opcode != LIO_NOP)
  76       {
  77         list[cnt]->aio_sigevent.sigev_notify = SIGEV_NONE;
  78         requests[cnt] = __aio_enqueue_request ((aiocb_union *) list[cnt],
  79                                                (list[cnt]->aio_lio_opcode
  80                                                 | LIO_OPCODE_BASE));
  81
  82         if (requests[cnt] != NULL)
  83           /* Successfully enqueued.  */
  84           ++total;
  85         else
  86           /* Signal that we've seen an error.  `errno' and the error code
  87              of the aiocb will tell more.  */
  88           result = -1;
  89       }
  90     else
  91       requests[cnt] = NULL;
  92
  93   if (total == 0)
  94     {
  95       /* We don't have anything to do except signalling if we work
  96          asynchronously.  */
  97
  98       /* Release the mutex.  We do this before raising a signal since the
  99          signal handler might do a `siglongjmp' and then the mutex is
 100          locked forever.  */
 101       pthread_mutex_unlock (&__aio_requests_mutex);
 102
 103       if (mode == LIO_NOWAIT)
 104         {
 105 #ifdef BROKEN_THREAD_SIGNALS
 106         __aio_notify_only (sig,
 107                            sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0);
 108 #else
 109         __aio_notify_only (sig);
 110 #endif
 111         }
 112
 113       return result;
 114     }
 115   else if (mode == LIO_WAIT)
 116     {
 117       pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 118       struct waitlist waitlist[nent];
 119       int oldstate;
 120
 121       total = 0;
 122       for (cnt = 0; cnt < nent; ++cnt)
 123         {
 124           assert (requests[cnt] == NULL || list[cnt] != NULL);
 125
 126           if (requests[cnt] != NULL && list[cnt]->aio_lio_opcode != LIO_NOP)
 127             {
 128               waitlist[cnt].cond = &cond;
 129               waitlist[cnt].next = requests[cnt]->waiting;
 130               waitlist[cnt].counterp = &total;
 131               waitlist[cnt].sigevp = NULL;
 132 #ifdef BROKEN_THREAD_SIGNALS
 133               waitlist[cnt].caller_pid = 0;     /* Not needed.  */
 134 #endif
 135               requests[cnt]->waiting = &waitlist[cnt];
 136               ++total;
 137             }
 138         }
 139
 140       /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancelation
 141          points we must be careful.  We added entries to the waiting lists
 142          which we must remove.  So defer cancelation for now.  */
 143       pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
 144
 145       while (total > 0)
 146         pthread_cond_wait (&cond, &__aio_requests_mutex);
 147
 148       /* Now it's time to restore the cancelation state.  */
 149       pthread_setcancelstate (oldstate, NULL);
 150
 151       /* Release the conditional variable.  */
 152       if (pthread_cond_destroy (&cond) != 0)
 153         /* This must never happen.  */
 154         abort ();
 155     }
 156   else
 157     {
 158       struct async_waitlist *waitlist;
 159
 160       waitlist = (struct async_waitlist *)
 161         malloc (sizeof (struct async_waitlist)
 162                 + (nent * sizeof (struct waitlist)));
 163
 164       if (waitlist == NULL)
 165         {
 166           __set_errno (EAGAIN);
 167           result = -1;
 168         }
 169       else
 170         {
 171 #ifdef BROKEN_THREAD_SIGNALS
 172           pid_t caller_pid = sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0;
 173 #endif
 174           total = 0;
 175
 176           for (cnt = 0; cnt < nent; ++cnt)
 177             {
 178               assert (requests[cnt] == NULL || list[cnt] != NULL);
 179
 180               if (requests[cnt] != NULL
 181                   && list[cnt]->aio_lio_opcode != LIO_NOP)
 182                 {
 183                   waitlist->list[cnt].cond = NULL;
 184                   waitlist->list[cnt].next = requests[cnt]->waiting;
 185                   waitlist->list[cnt].counterp = &waitlist->counter;
 186                   waitlist->list[cnt].sigevp = &waitlist->sigev;
 187 #ifdef BROKEN_THREAD_SIGNALS
 188                   waitlist->list[cnt].caller_pid = caller_pid;
 189 #endif
 190                   requests[cnt]->waiting = &waitlist->list[cnt];
 191                   ++total;
 192                 }
 193             }
 194
 195           waitlist->counter = total;
 196           waitlist->sigev = *sig;
 197         }
 198     }
 199
 200   /* Release the mutex.  */
 201   pthread_mutex_unlock (&__aio_requests_mutex);
 202
 203   return result;
 204 }