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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
|
/* Copyright (C) 2002-2020 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
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/file.h>
#include <sys/mman.h>
#include <sys/wait.h>
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t lock2 = PTHREAD_MUTEX_INITIALIZER;
static int fd;
static void *
tf (void *arg)
{
struct flock fl =
{
.l_type = F_WRLCK,
.l_start = 0,
.l_whence = SEEK_SET,
.l_len = 10
};
if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
{
puts ("fourth fcntl failed");
exit (1);
}
pthread_mutex_unlock (&lock);
pthread_mutex_lock (&lock2);
return NULL;
}
static int
do_test (void)
{
char tmp[] = "/tmp/tst-flock2-XXXXXX";
fd = mkstemp (tmp);
if (fd == -1)
{
puts ("mkstemp failed");
return 1;
}
unlink (tmp);
int i;
for (i = 0; i < 20; ++i)
write (fd, "foobar xyzzy", 12);
pthread_barrier_t *b;
b = mmap (NULL, sizeof (pthread_barrier_t), PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
if (b == MAP_FAILED)
{
puts ("mmap failed");
return 1;
}
pthread_barrierattr_t ba;
if (pthread_barrierattr_init (&ba) != 0)
{
puts ("barrierattr_init failed");
return 1;
}
if (pthread_barrierattr_setpshared (&ba, PTHREAD_PROCESS_SHARED) != 0)
{
puts ("barrierattr_setpshared failed");
return 1;
}
if (pthread_barrier_init (b, &ba, 2) != 0)
{
puts ("barrier_init failed");
return 1;
}
if (pthread_barrierattr_destroy (&ba) != 0)
{
puts ("barrierattr_destroy failed");
return 1;
}
struct flock fl =
{
.l_type = F_WRLCK,
.l_start = 0,
.l_whence = SEEK_SET,
.l_len = 10
};
if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
{
puts ("first fcntl failed");
return 1;
}
pid_t pid = fork ();
if (pid == -1)
{
puts ("fork failed");
return 1;
}
if (pid == 0)
{
/* Make sure the child does not stay around indefinitely. */
alarm (10);
/* Try to get the lock. */
if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
{
puts ("child: second flock succeeded");
return 1;
}
}
pthread_barrier_wait (b);
if (pid != 0)
{
fl.l_type = F_UNLCK;
if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
{
puts ("third fcntl failed");
return 1;
}
}
pthread_barrier_wait (b);
pthread_t th;
if (pid == 0)
{
if (pthread_mutex_lock (&lock) != 0)
{
puts ("1st locking of lock failed");
return 1;
}
if (pthread_mutex_lock (&lock2) != 0)
{
puts ("1st locking of lock2 failed");
return 1;
}
if (pthread_create (&th, NULL, tf, NULL) != 0)
{
puts ("pthread_create failed");
return 1;
}
if (pthread_mutex_lock (&lock) != 0)
{
puts ("2nd locking of lock failed");
return 1;
}
puts ("child locked file");
}
pthread_barrier_wait (b);
if (pid != 0)
{
fl.l_type = F_WRLCK;
if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
{
puts ("fifth fcntl succeeded");
return 1;
}
puts ("file locked by child");
}
pthread_barrier_wait (b);
if (pid == 0)
{
if (pthread_mutex_unlock (&lock2) != 0)
{
puts ("unlock of lock2 failed");
return 1;
}
if (pthread_join (th, NULL) != 0)
{
puts ("join failed");
return 1;
}
puts ("child's thread terminated");
}
pthread_barrier_wait (b);
if (pid != 0)
{
fl.l_type = F_WRLCK;
if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
{
puts ("fifth fcntl succeeded");
return 1;
}
puts ("file still locked");
}
pthread_barrier_wait (b);
if (pid == 0)
{
_exit (0);
}
int status;
if (TEMP_FAILURE_RETRY (waitpid (pid, &status, 0)) != pid)
{
puts ("waitpid failed");
return 1;
}
puts ("child terminated");
if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
{
puts ("sixth fcntl failed");
return 1;
}
return status;
}
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"
|
GitWeb