1/* BZ #17977 _res_hconf_reorder_addrs test.
2
3 Copyright (C) 2015-2022 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
31static 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
38void *
39realloc (void *ptr, size_t len)
40{
41 static void *(*fun) (void *, size_t);
42
43 if (!fun)
44 fun = dlsym (RTLD_NEXT, name: "realloc");
45
46 if (ts.tv_nsec)
47 nanosleep (requested_time: &ts, NULL);
48
49 return (*fun) (ptr, len);
50}
51
52static void *
53resolve (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 (addr: (void *) &addr, len: sizeof (addr), AF_INET,
63 result_buf: &ent, buf: buf, buflen: sizeof (buf), result: &result, h_errnop: &err);
64 return arg;
65}
66
67static int
68do_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 (newthread: &thr[i], NULL, start_routine: resolve, NULL);
81
82 if (rc)
83 {
84 printf (format: "pthread_create: %s\n", strerror(errnum: rc));
85 exit (status: 1);
86 }
87 }
88
89 for (i = 0; i < N; ++i)
90 {
91 void *retval;
92 int rc = pthread_join (th: thr[i], thread_return: &retval);
93
94 if (rc)
95 {
96 printf (format: "pthread_join: %s\n", strerror(errnum: rc));
97 exit (status: 1);
98 }
99 if (retval)
100 {
101 printf (format: "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"
114

source code of glibc/resolv/tst-res_hconf_reorder.c