resolv/tst-res_hconf_reorder.c

   1 /* BZ #17977 _res_hconf_reorder_addrs test.
   2
   3    Copyright (C) 2015-2023 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <time.h>
  25 #include <dlfcn.h>
  26 #include <pthread.h>
  27 #include <netdb.h>
  28 #include <netinet/in.h>
  29 #include <sys/socket.h>
  30
  31 static struct timespec ts;
  32
  33 /* The first thread that gets a lock in _res_hconf_reorder_addrs()
  34    should hold the lock long enough to make two other threads blocked.
  35    This is achieved by slowing down realloc(3) that is called several times
  36    by _res_hconf_reorder_addrs().  */
  37
  38 void *
  39 realloc (void *ptr, size_t len)
  40 {
  41   static void *(*fun) (void *, size_t);
  42
  43   if (!fun)
  44     fun = dlsym (RTLD_NEXT, "realloc");
  45
  46   if (ts.tv_nsec)
  47     nanosleep (&ts, NULL);
  48
  49   return (*fun) (ptr, len);
  50 }
  51
  52 static void *
  53 resolve (void *arg)
  54 {
  55   struct in_addr addr;
  56   struct hostent ent;
  57   struct hostent *result;
  58   int err;
  59   char buf[1024];
  60
  61   addr.s_addr = htonl (INADDR_LOOPBACK);
  62   (void) gethostbyaddr_r ((void *) &addr, sizeof (addr), AF_INET,
  63                           &ent, buf, sizeof (buf), &result, &err);
  64   return arg;
  65 }
  66
  67 static int
  68 do_test (void)
  69 {
  70   #define N 3
  71   pthread_t thr[N];
  72   unsigned int i;
  73   int result = 0;
  74
  75   /* turn on realloc slowdown */
  76   ts.tv_nsec = 100000000;
  77
  78   for (i = 0; i < N; ++i)
  79     {
  80       int rc = pthread_create (&thr[i], NULL, resolve, NULL);
  81
  82       if (rc)
  83         {
  84           printf ("pthread_create: %s\n", strerror(rc));
  85           exit (1);
  86         }
  87     }
  88
  89   for (i = 0; i < N; ++i)
  90     {
  91       void *retval;
  92       int rc = pthread_join (thr[i], &retval);
  93
  94       if (rc)
  95         {
  96           printf ("pthread_join: %s\n", strerror(rc));
  97           exit (1);
  98         }
  99       if (retval)
 100         {
 101           printf ("thread %u exit status %p\n", i, retval);
 102           result = 1;
 103         }
 104     }
 105
 106   /* turn off realloc slowdown, no longer needed */
 107   ts.tv_nsec = 0;
 108
 109   return result;
 110 }
 111
 112 #define TEST_FUNCTION do_test ()
 113 #include "../test-skeleton.c"