1/* Copyright (C) 2003-2024 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/* Test whether _res in glibc 2.1.x and earlier (before __res_state()
19 was introduced) works. Portable programs should never do the
20 dirty things below. */
21
22#include <pthread.h>
23#include <resolv.h>
24#include <stdlib.h>
25#include <stdio.h>
26
27void *tf (void *resp)
28{
29 if (resp == &_res || resp == __res_state ())
30 abort ();
31 _res.retry = 24;
32 return NULL;
33}
34
35void do_test (struct __res_state *resp)
36{
37 if (resp != &_res || resp != __res_state ())
38 abort ();
39 if (_res.retry != 12)
40 abort ();
41}
42
43int main (void)
44{
45#undef _res
46 extern struct __res_state _res;
47 pthread_t th;
48
49 _res.retry = 12;
50 if (pthread_create (newthread: &th, NULL, start_routine: tf, arg: &_res) != 0)
51 {
52 puts (s: "create failed");
53 exit (1);
54 }
55
56 do_test (resp: &_res);
57
58 if (pthread_join (th: th, NULL) != 0)
59 {
60 puts (s: "join failed");
61 exit (1);
62 }
63
64 do_test (resp: &_res);
65
66 exit (0);
67}
68

source code of glibc/sysdeps/pthread/tst-_res1.c