1/* Copyright (C) 2002-2024 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#include <errno.h>
19#include <fcntl.h>
20#include <semaphore.h>
21#include <stdio.h>
22#include <stdlib.h>
23#include <unistd.h>
24
25
26static void
27remove_sem (int status, void *arg)
28{
29 sem_unlink (name: arg);
30}
31
32
33int
34do_test (void)
35{
36 sem_t *s;
37 sem_t *s2;
38 pid_t pid;
39 int val;
40
41 /* Start with a clean slate and register a clean-up action. No need to
42 act if sem_unlink fails because we will catch the same problem during the
43 sem_open below. */
44 sem_unlink (name: "/glibc-tst-sem4");
45 on_exit (func: remove_sem, arg: (void *) "/glibc-tst-sem4");
46
47 s = sem_open (name: "/glibc-tst-sem4", O_CREAT, 0600, 1);
48 if (s == SEM_FAILED)
49 {
50 if (errno == ENOSYS)
51 {
52 puts (s: "sem_open not supported. Oh well.");
53 return 0;
54 }
55
56 /* Maybe the shm filesystem has strict permissions. */
57 if (errno == EACCES)
58 {
59 puts (s: "sem_open not allowed. Oh well.");
60 return 0;
61 }
62
63 printf (format: "sem_open: %m\n");
64 return 1;
65 }
66
67 /* We have the semaphore object. Now try again with O_EXCL, this
68 should fail. */
69 s2 = sem_open (name: "/glibc-tst-sem4", O_CREAT | O_EXCL, 0600, 1);
70 if (s2 != SEM_FAILED)
71 {
72 puts (s: "2nd sem_open didn't fail");
73 return 1;
74 }
75 if (errno != EEXIST)
76 {
77 puts (s: "2nd sem_open returned wrong error");
78 return 1;
79 }
80
81 /* Check the value. */
82 if (sem_getvalue (sem: s, sval: &val) == -1)
83 {
84 puts (s: "getvalue failed");
85 return 1;
86 }
87 if (val != 1)
88 {
89 printf (format: "initial value wrong: got %d, expected 1\n", val);
90 return 1;
91 }
92
93 if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
94 {
95 puts (s: "1st sem_wait failed");
96 return 1;
97 }
98
99 pid = fork ();
100 if (pid == -1)
101 {
102 printf (format: "fork failed: %m\n");
103 return 1;
104 }
105
106 if (pid == 0)
107 {
108 /* Child. */
109
110 /* Check the value. */
111 if (sem_getvalue (sem: s, sval: &val) == -1)
112 {
113 puts (s: "child: getvalue failed");
114 return 1;
115 }
116 if (val != 0)
117 {
118 printf (format: "child: value wrong: got %d, expect 0\n", val);
119 return 1;
120 }
121
122 if (sem_post (sem: s) == -1)
123 {
124 puts (s: "child: post failed");
125 return 1;
126 }
127 }
128 else
129 {
130 if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
131 {
132 puts (s: "2nd sem_wait failed");
133 return 1;
134 }
135
136 if (sem_getvalue (sem: s, sval: &val) == -1)
137 {
138 puts (s: "parent: 2nd getvalue failed");
139 return 1;
140 }
141 if (val != 0)
142 {
143 printf (format: "parent: value wrong: got %d, expected 0\n", val);
144 return 1;
145 }
146 }
147
148 return 0;
149}
150
151#define TEST_FUNCTION do_test ()
152#include "../test-skeleton.c"
153

source code of glibc/sysdeps/pthread/tst-sem4.c