resolv/getaddrinfo_a.c

   1 /* Copyright (C) 2001 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <netdb.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <unistd.h>
  25
  26 #include "gai_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 getaddrinfo_a (int mode, struct gaicb *list[], int ent, struct sigevent *sig)
  40 {
  41   struct sigevent defsigev;
  42   struct requestlist *requests[ent];
  43   int cnt;
  44   volatile int total = 0;
  45   int result = 0;
  46
  47   /* Check arguments.  */
  48   if (mode != GAI_WAIT && mode != GAI_NOWAIT)
  49     {
  50       __set_errno (EINVAL);
  51       return EAI_SYSTEM;
  52     }
  53
  54   if (sig == NULL)
  55     {
  56       defsigev.sigev_notify = SIGEV_NONE;
  57       sig = &defsigev;
  58     }
  59
  60   /* Request the mutex.  */
  61   pthread_mutex_lock (&__gai_requests_mutex);
  62
  63   /* Now we can enqueue all requests.  Since we already acquired the
  64      mutex the enqueue function need not do this.  */
  65   for (cnt = 0; cnt < ent; ++cnt)
  66     if (list[cnt] != NULL)
  67       {
  68         requests[cnt] = __gai_enqueue_request (list[cnt]);
  69
  70         if (requests[cnt] != NULL)
  71           /* Successfully enqueued.  */
  72           ++total;
  73         else
  74           /* Signal that we've seen an error.  `errno' and the error code
  75              of the gaicb will tell more.  */
  76           result = EAI_SYSTEM;
  77       }
  78     else
  79       requests[cnt] = NULL;
  80
  81   if (total == 0)
  82     {
  83       /* We don't have anything to do except signalling if we work
  84          asynchronously.  */
  85
  86       /* Release the mutex.  We do this before raising a signal since the
  87          signal handler might do a `siglongjmp' and then the mutex is
  88          locked forever.  */
  89       pthread_mutex_unlock (&__gai_requests_mutex);
  90
  91       if (mode == GAI_NOWAIT)
  92         __gai_notify_only (sig,
  93                            sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0);
  94
  95       return result;
  96     }
  97   else if (mode == GAI_WAIT)
  98     {
  99       pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 100       struct waitlist waitlist[ent];
 101       int oldstate;
 102
 103       total = 0;
 104       for (cnt = 0; cnt < ent; ++cnt)
 105         if (requests[cnt] != NULL)
 106           {
 107             waitlist[cnt].cond = &cond;
 108             waitlist[cnt].next = requests[cnt]->waiting;
 109             waitlist[cnt].counterp = &total;
 110             waitlist[cnt].sigevp = NULL;
 111             waitlist[cnt].caller_pid = 0;       /* Not needed.  */
 112             requests[cnt]->waiting = &waitlist[cnt];
 113             ++total;
 114           }
 115
 116       /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancelation
 117          points we must be careful.  We added entries to the waiting lists
 118          which we must remove.  So defer cancelation for now.  */
 119       pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
 120
 121       while (total > 0)
 122         pthread_cond_wait (&cond, &__gai_requests_mutex);
 123
 124       /* Now it's time to restore the cancelation state.  */
 125       pthread_setcancelstate (oldstate, NULL);
 126
 127       /* Release the conditional variable.  */
 128       if (pthread_cond_destroy (&cond) != 0)
 129         /* This must never happen.  */
 130         abort ();
 131     }
 132   else
 133     {
 134       struct async_waitlist *waitlist;
 135
 136       waitlist = (struct async_waitlist *)
 137         malloc (sizeof (struct async_waitlist)
 138                 + (ent * sizeof (struct waitlist)));
 139
 140       if (waitlist == NULL)
 141         result = EAI_AGAIN;
 142       else
 143         {
 144           pid_t caller_pid = sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0;
 145           total = 0;
 146
 147           for (cnt = 0; cnt < ent; ++cnt)
 148             if (requests[cnt] != NULL)
 149               {
 150                 waitlist->list[cnt].cond = NULL;
 151                 waitlist->list[cnt].next = requests[cnt]->waiting;
 152                 waitlist->list[cnt].counterp = &waitlist->counter;
 153                 waitlist->list[cnt].sigevp = &waitlist->sigev;
 154                 waitlist->list[cnt].caller_pid = caller_pid;
 155                 requests[cnt]->waiting = &waitlist->list[cnt];
 156                 ++total;
 157               }
 158
 159           waitlist->counter = total;
 160           waitlist->sigev = *sig;
 161         }
 162     }
 163
 164   /* Release the mutex.  */
 165   pthread_mutex_unlock (&__gai_requests_mutex);
 166
 167   return result;
 168 }