resolv/tst-res_hconf_reorder.c

   1 /* BZ #17977 _res_hconf_reorder_addrs test.
   2
   3    Copyright (C) 2015 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    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <time.h>
  24 #include <dlfcn.h>
  25 #include <pthread.h>
  26 #include <netdb.h>
  27 #include <netinet/in.h>
  28 #include <sys/socket.h>
  29
  30 static struct timespec ts;
  31
  32 /* The first thread that gets a lock in _res_hconf_reorder_addrs()
  33    should hold the lock long enough to make two other threads blocked.
  34    This is achieved by slowing down realloc(3) that is called several times
  35    by _res_hconf_reorder_addrs().  */
  36
  37 void *
  38 realloc (void *ptr, size_t len)
  39 {
  40   static void *(*fun) (void *, size_t);
  41
  42   if (!fun)
  43     fun = dlsym (RTLD_NEXT, "realloc");
  44
  45   if (ts.tv_nsec)
  46     nanosleep (&ts, NULL);
  47
  48   return (*fun) (ptr, len);
  49 }
  50
  51 static void *
  52 resolve (void *arg)
  53 {
  54   struct in_addr addr;
  55   struct hostent ent;
  56   struct hostent *result;
  57   int err;
  58   char buf[1024];
  59
  60   addr.s_addr = htonl (INADDR_LOOPBACK);
  61   (void) gethostbyaddr_r ((void *) &addr, sizeof (addr), AF_INET,
  62                           &ent, buf, sizeof (buf), &result, &err);
  63   return arg;
  64 }
  65
  66 static int
  67 do_test (void)
  68 {
  69   #define N 3
  70   pthread_t thr[N];
  71   unsigned int i;
  72   int result = 0;
  73
  74   /* turn on realloc slowdown */
  75   ts.tv_nsec = 100000000;
  76
  77   for (i = 0; i < N; ++i)
  78     {
  79       int rc = pthread_create (&thr[i], NULL, resolve, NULL);
  80
  81       if (rc)
  82         {
  83           printf ("pthread_create: %s\n", strerror(rc));
  84           exit (1);
  85         }
  86     }
  87
  88   for (i = 0; i < N; ++i)
  89     {
  90       void *retval;
  91       int rc = pthread_join (thr[i], &retval);
  92
  93       if (rc)
  94         {
  95           printf ("pthread_join: %s\n", strerror(rc));
  96           exit (1);
  97         }
  98       if (retval)
  99         {
 100           printf ("thread %u exit status %p\n", i, retval);
 101           result = 1;
 102         }
 103     }
 104
 105   /* turn off realloc slowdown, no longer needed */
 106   ts.tv_nsec = 0;
 107
 108   return result;
 109 }
 110
 111 #define TEST_FUNCTION do_test ()
 112 #include "../test-skeleton.c"