resolv/gai_suspend.c

   1 /* Copyright (C) 2001-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <netdb.h>
  20 #include <pthread.h>
  21 #include <stdlib.h>
  22 #include <sys/time.h>
  23
  24 #include <gai_misc.h>
  25
  26 int
  27 ___gai_suspend_time64 (const struct gaicb *const list[], int ent,
  28                        const struct __timespec64 *timeout)
  29 {
  30   struct waitlist waitlist[ent];
  31   struct requestlist *requestlist[ent];
  32 #ifndef DONT_NEED_GAI_MISC_COND
  33   pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
  34 #endif
  35   int cnt;
  36   unsigned int cntr = 1;
  37   int none = 1;
  38   int result;
  39
  40   /* Request the mutex.  */
  41   __pthread_mutex_lock (&__gai_requests_mutex);
  42
  43   /* There is not yet a finished request.  Signal the request that
  44      we are working for it.  */
  45   for (cnt = 0; cnt < ent; ++cnt)
  46     if (list[cnt] != NULL && list[cnt]->__return == EAI_INPROGRESS)
  47       {
  48         requestlist[cnt] = __gai_find_request (list[cnt]);
  49
  50         if (requestlist[cnt] != NULL)
  51           {
  52 #ifndef DONT_NEED_GAI_MISC_COND
  53             waitlist[cnt].cond = &cond;
  54 #endif
  55             waitlist[cnt].next = requestlist[cnt]->waiting;
  56             waitlist[cnt].counterp = &cntr;
  57             waitlist[cnt].sigevp = NULL;
  58             waitlist[cnt].caller_pid = 0;       /* Not needed.  */
  59             requestlist[cnt]->waiting = &waitlist[cnt];
  60             none = 0;
  61           }
  62       }
  63
  64   struct __timespec64 ts;
  65   if (timeout != NULL)
  66     {
  67       __clock_gettime64 (CLOCK_MONOTONIC, &ts);
  68       ts.tv_sec += timeout->tv_sec;
  69       ts.tv_nsec += timeout->tv_nsec;
  70       if (ts.tv_nsec >= 1000000000)
  71         {
  72           ts.tv_nsec -= 1000000000;
  73           ts.tv_sec++;
  74         }
  75     }
  76
  77   if (none)
  78     {
  79       if (cnt < ent)
  80         /* There is an entry which is finished.  */
  81         result = 0;
  82       else
  83         result = EAI_ALLDONE;
  84     }
  85   else
  86     {
  87       /* There is no request done but some are still being worked on.  */
  88       int oldstate;
  89
  90       /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancelation
  91          points we must be careful.  We added entries to the waiting lists
  92          which we must remove.  So defer cancelation for now.  */
  93       __pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
  94
  95 #ifdef DONT_NEED_GAI_MISC_COND
  96       result = 0;
  97       GAI_MISC_WAIT (result, cntr, timeout == NULL ? NULL : &ts, 1);
  98 #else
  99       struct timespec ts32 = valid_timespec64_to_timespec (ts);
 100       result = pthread_cond_timedwait (&cond, &__gai_requests_mutex,
 101                                        timeout == NULL ? NULL : &ts32);
 102 #endif
 103
 104       /* Now remove the entry in the waiting list for all requests
 105          which didn't terminate.  */
 106       for (cnt = 0; cnt < ent; ++cnt)
 107         if (list[cnt] != NULL && list[cnt]->__return == EAI_INPROGRESS
 108             && requestlist[cnt] != NULL)
 109           {
 110             struct waitlist **listp = &requestlist[cnt]->waiting;
 111
 112             /* There is the chance that we cannot find our entry anymore.
 113                This could happen if the request terminated and restarted
 114                again.  */
 115             while (*listp != NULL && *listp != &waitlist[cnt])
 116               listp = &(*listp)->next;
 117
 118             if (*listp != NULL)
 119               *listp = (*listp)->next;
 120           }
 121
 122       /* Now it's time to restore the cancelation state.  */
 123       __pthread_setcancelstate (oldstate, NULL);
 124
 125 #ifndef DONT_NEED_GAI_MISC_COND
 126       /* Release the conditional variable.  */
 127       if (pthread_cond_destroy (&cond) != 0)
 128         /* This must never happen.  */
 129         abort ();
 130 #endif
 131
 132       if (result != 0)
 133         {
 134           /* An error occurred.  Possibly it's EINTR.  We have to translate
 135              the timeout error report of `pthread_cond_timedwait' to the
 136              form expected from `gai_suspend'.  */
 137           if (__glibc_likely (result == ETIMEDOUT))
 138             result = EAI_AGAIN;
 139           else if (result == EINTR)
 140             result = EAI_INTR;
 141           else
 142             result = EAI_SYSTEM;
 143         }
 144     }
 145
 146   /* Release the mutex.  */
 147   __pthread_mutex_unlock (&__gai_requests_mutex);
 148
 149   return result;
 150 }
 151
 152 #if __TIMESIZE == 64
 153 # if PTHREAD_IN_LIBC
 154 versioned_symbol (libc, ___gai_suspend_time64, gai_suspend, GLIBC_2_34);
 155 #  if OTHER_SHLIB_COMPAT (libanl, GLIBC_2_2_3, GLIBC_2_34)
 156 compat_symbol (libanl, ___gai_suspend_time64, gai_suspend, GLIBC_2_2_3);
 157 #  endif
 158 # endif /* PTHREAD_IN_LIBC */
 159
 160 #else /* __TIMESIZE != 64 */
 161 # if PTHREAD_IN_LIBC
 162 libc_hidden_ver (___gai_suspend_time64, __gai_suspend_time64)
 163 versioned_symbol (libc, ___gai_suspend_time64, __gai_suspend_time64,
 164                   GLIBC_2_34);
 165 # else /* !PTHREAD_IN_LIBC */
 166 # if IS_IN (libanl)
 167 hidden_ver (___gai_suspend_time64, __gai_suspend_time64)
 168 # endif
 169 #endif /* !PTHREAD_IN_LIBC */
 170
 171 int
 172 ___gai_suspend (const struct gaicb *const list[], int ent,
 173                 const struct timespec *timeout)
 174 {
 175   struct __timespec64 ts64;
 176
 177   if (timeout != NULL)
 178     ts64 = valid_timespec_to_timespec64 (*timeout);
 179
 180   return __gai_suspend_time64 (list, ent, timeout != NULL ? &ts64 : NULL);
 181 }
 182 #if PTHREAD_IN_LIBC
 183 versioned_symbol (libc, ___gai_suspend, gai_suspend, GLIBC_2_34);
 184 # if OTHER_SHLIB_COMPAT (libanl, GLIBC_2_2_3, GLIBC_2_34)
 185 compat_symbol (libanl, ___gai_suspend, gai_suspend, GLIBC_2_2_3);
 186 # endif
 187 # else
 188 weak_alias (___gai_suspend, gai_suspend)
 189 # endif /* !PTHREAD_IN_LIBC */
 190 #endif /* __TIMESIZE != 64 */