1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Copyright (c) Wipro Technologies Ltd, 2002. All Rights Reserved.
3 * Copyright (c) Linux Test Project, 2003-2021
4 * Author: Vatsal Avasthi
5 */
6
7 /*\
8 * [Description]
9 *
10 * Test verifies that flock() behavior with different locking combinations along
11 * with LOCK_SH and LOCK_EX:
12 *
13 * - flock() succeeded in acquiring shared lock on shared lock file.
14 * - flock() failed to acquire exclusive lock on shared lock file.
15 * - flock() failed to acquire shared lock on exclusive lock file.
16 * - flock() failed to acquire exclusive lock on exclusive lock file.
17 */
18
19 #include <errno.h>
20 #include <sys/file.h>
21 #include <stdlib.h>
22
23 #include "tst_test.h"
24
25 static struct tcase {
26 int operation;
27 char *f_lock;
28 } tcases[] = {
29 {LOCK_SH, "shared lock"},
30 {LOCK_EX, "exclusive lock"},
31 };
32
child(int opt,int should_pass,char * lock)33 static void child(int opt, int should_pass, char *lock)
34 {
35 int retval, fd1;
36
37 fd1 = SAFE_OPEN("testfile", O_RDWR);
38 retval = flock(fd1, opt);
39 if (should_pass) {
40 tst_res(retval == -1 ? TFAIL : TPASS,
41 " Child acquiring %s got %d", lock, retval);
42 } else {
43 tst_res(retval == -1 ? TPASS : TFAIL,
44 " Child acquiring %s got %d", lock, retval);
45 }
46
47 SAFE_CLOSE(fd1);
48 exit(0);
49 }
50
verify_flock(unsigned n)51 static void verify_flock(unsigned n)
52 {
53 int fd2;
54 pid_t pid;
55 struct tcase *tc = &tcases[n];
56
57 fd2 = SAFE_OPEN("testfile", O_RDWR);
58 TEST(flock(fd2, tc->operation));
59 if (TST_RET != 0) {
60 tst_res(TFAIL | TTERRNO, "flock() failed to acquire %s",
61 tc->f_lock);
62 SAFE_CLOSE(fd2);
63 return;
64 }
65
66 tst_res(TPASS, "Parent had %s", tc->f_lock);
67
68 pid = SAFE_FORK();
69 if (pid == 0)
70 child(LOCK_SH | LOCK_NB, tc->operation & LOCK_SH, "shared lock");
71 else
72 tst_reap_children();
73
74 pid = SAFE_FORK();
75 if (pid == 0)
76 child(LOCK_EX | LOCK_NB, 0, "exclusive lock");
77 else
78 tst_reap_children();
79
80 SAFE_CLOSE(fd2);
81 }
82
setup(void)83 static void setup(void)
84 {
85 int fd;
86
87 fd = SAFE_OPEN("testfile", O_CREAT | O_TRUNC | O_RDWR, 0644);
88 SAFE_CLOSE(fd);
89 }
90
91 static struct tst_test test = {
92 .tcnt = ARRAY_SIZE(tcases),
93 .test = verify_flock,
94 .needs_tmpdir = 1,
95 .setup = setup,
96 .forks_child = 1,
97 };
98