1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
/* Copyright (C) 2002 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
static void
remove_sem (int status, void *arg)
{
sem_unlink (arg);
}
int
main (void)
{
sem_t *s;
sem_t *s2;
pid_t pid;
int val;
s = sem_open ("/glibc-tst-sem4", O_CREAT, 0600, 1);
if (s == SEM_FAILED)
{
if (errno == ENOSYS)
{
puts ("sem_open not supported. Oh well.");
return 0;
}
/* Maybe the shm filesystem has strict permissions. */
if (errno == EACCES)
{
puts ("sem_open not allowed. Oh well.");
return 0;
}
printf ("sem_open: %m\n");
return 1;
}
on_exit (remove_sem, (void *) "/glibc-tst-sem4");
/* We have the semaphore object. Now try again with O_EXCL, this
should fail. */
s2 = sem_open ("/glibc-tst-sem4", O_CREAT | O_EXCL, 0600, 1);
if (s2 != SEM_FAILED)
{
puts ("2nd sem_open didn't fail");
return 1;
}
if (errno != EEXIST)
{
puts ("2nd sem_open returned wrong error");
return 1;
}
/* Check the value. */
if (sem_getvalue (s, &val) == -1)
{
puts ("getvalue failed");
return 1;
}
if (val != 1)
{
printf ("initial value wrong: got %d, expected 1\n", val);
return 1;
}
if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
{
puts ("1st sem_wait failed");
return 1;
}
pid = fork ();
if (pid == -1)
{
printf ("fork failed: %m\n");
return 1;
}
if (pid == 0)
{
/* Child. */
/* Check the value. */
if (sem_getvalue (s, &val) == -1)
{
puts ("child: getvalue failed");
return 1;
}
if (val != 0)
{
printf ("child: value wrong: got %d, expect 0\n", val);
return 1;
}
if (sem_post (s) == -1)
{
puts ("child: post failed");
return 1;
}
}
else
{
if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
{
puts ("2nd sem_wait failed");
return 1;
}
if (sem_getvalue (s, &val) == -1)
{
puts ("parent: 2nd getvalue failed");
return 1;
}
if (val != 0)
{
printf ("parent: value wrong: got %d, expected 0\n", val);
return 1;
}
}
return 0;
}
|
