1 /* Helper for exit/dlclose race test (Bug 22180).
2 Copyright (C) 2017-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <stdio.h>
20 #include <stdbool.h>
21 #include <stdlib.h>
22 #include <semaphore.h>
23 #include <unistd.h>
24 #include <support/check.h>
25 #include <support/xthread.h>
26
27 /* Semaphore defined in executable to ensure we have a happens-before
28 between the first function starting and exit being called. */
29 extern sem_t order1;
30
31 /* Semaphore defined in executable to ensure we have a happens-before
32 between the second function starting and the first function returning. */
33 extern sem_t order2;
34
35 /* glibc function for registering DSO-specific exit functions. */
36 extern int __cxa_atexit (void (*func) (void *), void *arg, void *dso_handle);
37
38 /* Hidden compiler handle to this shared object. */
39 extern void *__dso_handle __attribute__ ((__weak__));
40
41 static void
first(void * start)42 first (void *start)
43 {
44 /* Let the exiting thread run. */
45 sem_post (&order1);
46
47 /* Wait for exiting thread to finish. */
48 sem_wait (&order2);
49
50 printf ("first\n");
51 }
52
53 static void
second(void * start)54 second (void *start)
55 {
56 /* We may be called from different threads.
57 This lock protects called. */
58 static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
59 static bool called = false;
60
61 xpthread_mutex_lock (&mtx);
62 if (called)
63 FAIL_EXIT1 ("second called twice!");
64
65 called = true;
66 xpthread_mutex_unlock (&mtx);
67
68 printf ("second\n");
69 }
70
71
72 __attribute__ ((constructor)) static void
constructor(void)73 constructor (void)
74 {
75 sem_init (&order1, 0, 0);
76 sem_init (&order2, 0, 0);
77 __cxa_atexit (second, NULL, __dso_handle);
78 __cxa_atexit (first, NULL, __dso_handle);
79 }
80