resolv/getaddrinfo_a.c

   1 /* Copyright (C) 2001-2023 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 <unistd.h>
  23
  24 #include <gai_misc.h>
  25
  26
  27 /* We need this special structure to handle asynchronous I/O.  */
  28 struct async_waitlist
  29   {
  30     unsigned int counter;
  31     struct sigevent sigev;
  32     struct waitlist list[0];
  33   };
  34
  35
  36 int
  37 __getaddrinfo_a (int mode, struct gaicb *list[], int ent, struct sigevent *sig)
  38 {
  39   struct sigevent defsigev;
  40   struct requestlist *requests[ent];
  41   int cnt;
  42   volatile unsigned int total = 0;
  43   int result = 0;
  44
  45   /* Check arguments.  */
  46   if (mode != GAI_WAIT && mode != GAI_NOWAIT)
  47     {
  48       __set_errno (EINVAL);
  49       return EAI_SYSTEM;
  50     }
  51
  52   if (sig == NULL)
  53     {
  54       defsigev.sigev_notify = SIGEV_NONE;
  55       sig = &defsigev;
  56     }
  57
  58   /* Request the mutex.  */
  59   __pthread_mutex_lock (&__gai_requests_mutex);
  60
  61   /* Now we can enqueue all requests.  Since we already acquired the
  62      mutex the enqueue function need not do this.  */
  63   for (cnt = 0; cnt < ent; ++cnt)
  64     if (list[cnt] != NULL)
  65       {
  66         requests[cnt] = __gai_enqueue_request (list[cnt]);
  67
  68         if (requests[cnt] != NULL)
  69           /* Successfully enqueued.  */
  70           ++total;
  71         else
  72           /* Signal that we've seen an error.  `errno' and the error code
  73              of the gaicb will tell more.  */
  74           result = EAI_SYSTEM;
  75       }
  76     else
  77       requests[cnt] = NULL;
  78
  79   if (total == 0)
  80     {
  81       /* We don't have anything to do except signalling if we work
  82          asynchronously.  */
  83
  84       /* Release the mutex.  We do this before raising a signal since the
  85          signal handler might do a `siglongjmp' and then the mutex is
  86          locked forever.  */
  87       __pthread_mutex_unlock (&__gai_requests_mutex);
  88
  89       if (mode == GAI_NOWAIT)
  90         __gai_notify_only (sig,
  91                            sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0);
  92
  93       return result;
  94     }
  95   else if (mode == GAI_WAIT)
  96     {
  97 #ifndef DONT_NEED_GAI_MISC_COND
  98       pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
  99 #endif
 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 #ifndef DONT_NEED_GAI_MISC_COND
 108             waitlist[cnt].cond = &cond;
 109 #endif
 110             waitlist[cnt].next = requests[cnt]->waiting;
 111             waitlist[cnt].counterp = &total;
 112             waitlist[cnt].sigevp = NULL;
 113             waitlist[cnt].caller_pid = 0;       /* Not needed.  */
 114             requests[cnt]->waiting = &waitlist[cnt];
 115             ++total;
 116           }
 117
 118       /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancelation
 119          points we must be careful.  We added entries to the waiting lists
 120          which we must remove.  So defer cancelation for now.  */
 121       __pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
 122
 123       while (total > 0)
 124         {
 125 #ifdef DONT_NEED_GAI_MISC_COND
 126           int not_used __attribute__ ((unused));
 127           GAI_MISC_WAIT (not_used, total, NULL, 1);
 128 #else
 129           pthread_cond_wait (&cond, &__gai_requests_mutex);
 130 #endif
 131         }
 132
 133       /* Now it's time to restore the cancelation state.  */
 134       __pthread_setcancelstate (oldstate, NULL);
 135
 136 #ifndef DONT_NEED_GAI_MISC_COND
 137       /* Release the conditional variable.  */
 138       if (pthread_cond_destroy (&cond) != 0)
 139         /* This must never happen.  */
 140         abort ();
 141 #endif
 142     }
 143   else
 144     {
 145       struct async_waitlist *waitlist;
 146
 147       waitlist = (struct async_waitlist *)
 148         malloc (sizeof (struct async_waitlist)
 149                 + (ent * sizeof (struct waitlist)));
 150
 151       if (waitlist == NULL)
 152         result = EAI_AGAIN;
 153       else
 154         {
 155           pid_t caller_pid = sig->sigev_notify == SIGEV_SIGNAL ? getpid () : 0;
 156           total = 0;
 157
 158           for (cnt = 0; cnt < ent; ++cnt)
 159             if (requests[cnt] != NULL)
 160               {
 161 #ifndef DONT_NEED_GAI_MISC_COND
 162                 waitlist->list[cnt].cond = NULL;
 163 #endif
 164                 waitlist->list[cnt].next = requests[cnt]->waiting;
 165                 waitlist->list[cnt].counterp = &waitlist->counter;
 166                 waitlist->list[cnt].sigevp = &waitlist->sigev;
 167                 waitlist->list[cnt].caller_pid = caller_pid;
 168                 requests[cnt]->waiting = &waitlist->list[cnt];
 169                 ++total;
 170               }
 171
 172           waitlist->counter = total;
 173           waitlist->sigev = *sig;
 174         }
 175     }
 176
 177   /* Release the mutex.  */
 178   __pthread_mutex_unlock (&__gai_requests_mutex);
 179
 180   return result;
 181 }
 182 #if PTHREAD_IN_LIBC
 183 versioned_symbol (libc, __getaddrinfo_a, getaddrinfo_a, GLIBC_2_34);
 184
 185 # if OTHER_SHLIB_COMPAT (libanl, GLIBC_2_2_3, GLIBC_2_34)
 186 compat_symbol (libanl, __getaddrinfo_a, getaddrinfo_a, GLIBC_2_2_3);
 187 # endif
 188 #else /* !PTHREAD_IN_LIBC */
 189 strong_alias (__getaddrinfo_a, getaddrinfo_a)
 190 #endif /* !PTHREAD_IN_LIBC */