1 /* Copyright (C) 2002-2023 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 <pthread.h>
20 #include <stdio.h>
21 #include <stdlib.h>
22 #include <unistd.h>
23 #include <sys/file.h>
24 #include <sys/mman.h>
25 #include <sys/wait.h>
26
27 #include <support/xunistd.h>
28
29 static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
30 static pthread_mutex_t lock2 = PTHREAD_MUTEX_INITIALIZER;
31 static int fd;
32
33
34 static void *
35 tf (void *arg)
36 {
37 struct flock fl =
38 {
39 .l_type = F_WRLCK,
40 .l_start = 0,
41 .l_whence = SEEK_SET,
42 .l_len = 10
43 };
44 if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
45 {
46 puts ("fourth fcntl failed");
47 exit (1);
48 }
49
50 pthread_mutex_unlock (&lock);
51
52 pthread_mutex_lock (&lock2);
53
54 return NULL;
55 }
56
57
58 static int
59 do_test (void)
60 {
61 char tmp[] = "/tmp/tst-flock2-XXXXXX";
62
63 fd = mkstemp (tmp);
64 if (fd == -1)
65 {
66 puts ("mkstemp failed");
67 return 1;
68 }
69
70 unlink (tmp);
71
72 int i;
73 for (i = 0; i < 20; ++i)
74 xwrite (fd, "foobar xyzzy", 12);
75
76 pthread_barrier_t *b;
77 b = mmap (NULL, sizeof (pthread_barrier_t), PROT_READ | PROT_WRITE,
78 MAP_SHARED, fd, 0);
79 if (b == MAP_FAILED)
80 {
81 puts ("mmap failed");
82 return 1;
83 }
84
85 pthread_barrierattr_t ba;
86 if (pthread_barrierattr_init (&ba) != 0)
87 {
88 puts ("barrierattr_init failed");
89 return 1;
90 }
91
92 if (pthread_barrierattr_setpshared (&ba, PTHREAD_PROCESS_SHARED) != 0)
93 {
94 puts ("barrierattr_setpshared failed");
95 return 1;
96 }
97
98 if (pthread_barrier_init (b, &ba, 2) != 0)
99 {
100 puts ("barrier_init failed");
101 return 1;
102 }
103
104 if (pthread_barrierattr_destroy (&ba) != 0)
105 {
106 puts ("barrierattr_destroy failed");
107 return 1;
108 }
109
110 struct flock fl =
111 {
112 .l_type = F_WRLCK,
113 .l_start = 0,
114 .l_whence = SEEK_SET,
115 .l_len = 10
116 };
117 if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
118 {
119 puts ("first fcntl failed");
120 return 1;
121 }
122
123 pid_t pid = fork ();
124 if (pid == -1)
125 {
126 puts ("fork failed");
127 return 1;
128 }
129
130 if (pid == 0)
131 {
132 /* Make sure the child does not stay around indefinitely. */
133 alarm (10);
134
135 /* Try to get the lock. */
136 if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
137 {
138 puts ("child: second flock succeeded");
139 return 1;
140 }
141 }
142
143 pthread_barrier_wait (b);
144
145 if (pid != 0)
146 {
147 fl.l_type = F_UNLCK;
148 if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
149 {
150 puts ("third fcntl failed");
151 return 1;
152 }
153 }
154
155 pthread_barrier_wait (b);
156
157 pthread_t th;
158 if (pid == 0)
159 {
160 if (pthread_mutex_lock (&lock) != 0)
161 {
162 puts ("1st locking of lock failed");
163 return 1;
164 }
165
166 if (pthread_mutex_lock (&lock2) != 0)
167 {
168 puts ("1st locking of lock2 failed");
169 return 1;
170 }
171
172 if (pthread_create (&th, NULL, tf, NULL) != 0)
173 {
174 puts ("pthread_create failed");
175 return 1;
176 }
177
178 if (pthread_mutex_lock (&lock) != 0)
179 {
180 puts ("2nd locking of lock failed");
181 return 1;
182 }
183
184 puts ("child locked file");
185 }
186
187 pthread_barrier_wait (b);
188
189 if (pid != 0)
190 {
191 fl.l_type = F_WRLCK;
192 if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
193 {
194 puts ("fifth fcntl succeeded");
195 return 1;
196 }
197
198 puts ("file locked by child");
199 }
200
201 pthread_barrier_wait (b);
202
203 if (pid == 0)
204 {
205 if (pthread_mutex_unlock (&lock2) != 0)
206 {
207 puts ("unlock of lock2 failed");
208 return 1;
209 }
210
211 if (pthread_join (th, NULL) != 0)
212 {
213 puts ("join failed");
214 return 1;
215 }
216
217 puts ("child's thread terminated");
218 }
219
220 pthread_barrier_wait (b);
221
222 if (pid != 0)
223 {
224 fl.l_type = F_WRLCK;
225 if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLK, &fl)) == 0)
226 {
227 puts ("fifth fcntl succeeded");
228 return 1;
229 }
230
231 puts ("file still locked");
232 }
233
234 pthread_barrier_wait (b);
235
236 if (pid == 0)
237 {
238 _exit (0);
239 }
240
241 int status;
242 if (TEMP_FAILURE_RETRY (waitpid (pid, &status, 0)) != pid)
243 {
244 puts ("waitpid failed");
245 return 1;
246 }
247 puts ("child terminated");
248
249 if (TEMP_FAILURE_RETRY (fcntl (fd, F_SETLKW, &fl)) != 0)
250 {
251 puts ("sixth fcntl failed");
252 return 1;
253 }
254
255 return status;
256 }
257
258 #define TEST_FUNCTION do_test ()
259 #include "../test-skeleton.c"