resolv/gai_suspend.c

   1 /* Copyright (C) 2001, 2006 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 <sys/time.h>
  25
  26 #include <gai_misc.h>
  27
  28
  29 int
  30 gai_suspend (const struct gaicb *const list[], int ent,
  31              const struct timespec *timeout)
  32 {
  33   struct waitlist waitlist[ent];
  34   struct requestlist *requestlist[ent];
  35 #ifndef DONT_NEED_GAI_MISC_COND
  36   pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
  37 #endif
  38   int cnt;
  39   int cntr = 1;
  40   int none = 1;
  41   int result;
  42
  43   /* Request the mutex.  */
  44   pthread_mutex_lock (&__gai_requests_mutex);
  45
  46   /* There is not yet a finished request.  Signal the request that
  47      we are working for it.  */
  48   for (cnt = 0; cnt < ent; ++cnt)
  49     if (list[cnt] != NULL && list[cnt]->__return == EAI_INPROGRESS)
  50       {
  51         requestlist[cnt] = __gai_find_request (list[cnt]);
  52
  53         if (requestlist[cnt] != NULL)
  54           {
  55 #ifndef DONT_NEED_GAI_MISC_COND
  56             waitlist[cnt].cond = &cond;
  57 #endif
  58             waitlist[cnt].next = requestlist[cnt]->waiting;
  59             waitlist[cnt].counterp = &cntr;
  60             waitlist[cnt].sigevp = NULL;
  61             waitlist[cnt].caller_pid = 0;       /* Not needed.  */
  62             requestlist[cnt]->waiting = &waitlist[cnt];
  63             none = 0;
  64           }
  65       }
  66
  67   if (none)
  68     {
  69       if (cnt < ent)
  70         /* There is an entry which is finished.  */
  71         result = 0;
  72       else
  73         result = EAI_ALLDONE;
  74     }
  75   else
  76     {
  77       /* There is no request done but some are still being worked on.  */
  78       int oldstate;
  79
  80       /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancelation
  81          points we must be careful.  We added entries to the waiting lists
  82          which we must remove.  So defer cancelation for now.  */
  83       pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
  84
  85 #ifdef DONT_NEED_GAI_MISC_COND
  86       result = 0;
  87       GAI_MISC_WAIT (result, cntr, timeout, 1);
  88 #else
  89       if (timeout == NULL)
  90         result = pthread_cond_wait (&cond, &__gai_requests_mutex);
  91       else
  92         {
  93           /* We have to convert the relative timeout value into an
  94              absolute time value with pthread_cond_timedwait expects.  */
  95           struct timeval now;
  96           struct timespec abstime;
  97
  98           __gettimeofday (&now, NULL);
  99           abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
 100           abstime.tv_sec = timeout->tv_sec + now.tv_sec;
 101           if (abstime.tv_nsec >= 1000000000)
 102             {
 103               abstime.tv_nsec -= 1000000000;
 104               abstime.tv_sec += 1;
 105             }
 106
 107           result = pthread_cond_timedwait (&cond, &__gai_requests_mutex,
 108                                            &abstime);
 109         }
 110 #endif
 111
 112       /* Now remove the entry in the waiting list for all requests
 113          which didn't terminate.  */
 114       for (cnt = 0; cnt < ent; ++cnt)
 115         if (list[cnt] != NULL && list[cnt]->__return == EAI_INPROGRESS
 116             && requestlist[cnt] != NULL)
 117           {
 118             struct waitlist **listp = &requestlist[cnt]->waiting;
 119
 120             /* There is the chance that we cannot find our entry anymore.
 121                This could happen if the request terminated and restarted
 122                again.  */
 123             while (*listp != NULL && *listp != &waitlist[cnt])
 124               listp = &(*listp)->next;
 125
 126             if (*listp != NULL)
 127               *listp = (*listp)->next;
 128           }
 129
 130       /* Now it's time to restore the cancelation state.  */
 131       pthread_setcancelstate (oldstate, NULL);
 132
 133 #ifndef DONT_NEED_GAI_MISC_COND
 134       /* Release the conditional variable.  */
 135       if (pthread_cond_destroy (&cond) != 0)
 136         /* This must never happen.  */
 137         abort ();
 138 #endif
 139
 140       if (result != 0)
 141         {
 142           /* An error occurred.  Possibly it's EINTR.  We have to translate
 143              the timeout error report of `pthread_cond_timedwait' to the
 144              form expected from `gai_suspend'.  */
 145           if (__builtin_expect (result, ETIMEDOUT) == ETIMEDOUT)
 146             result = EAI_AGAIN;
 147           else if (result == EINTR)
 148             result = EAI_INTR;
 149           else
 150             result = EAI_SYSTEM;
 151         }
 152     }
 153
 154   /* Release the mutex.  */
 155   pthread_mutex_unlock (&__gai_requests_mutex);
 156
 157   return result;
 158 }