1 /*
2 * Copyright (c) 2014 Fujitsu Ltd.
3 * Author: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
13 * the GNU General Public License for more details.
14 */
15
16 /*
17 * Note: this test has already been in xfstests generic/028 test case,
18 * I just port it to LTP.
19 *
20 * Kernel commit '232d2d60aa5469bb097f55728f65146bd49c1d25' introduced a race
21 * condition that causes getcwd(2) to return "/" instead of correct path.
22 * 232d2d6 dcache: Translating dentry into pathname without
23 * taking rename_lock
24 *
25 * And these two kernel commits fixed the bug:
26 * ede4cebce16f5643c61aedd6d88d9070a1d23a68
27 * prepend_path() needs to reinitialize dentry/vfsmount/mnt on restarts
28 * f6500801522c61782d4990fa1ad96154cb397cd4
29 * f650080 __dentry_path() fixes
30 *
31 * This test is to check whether this bug exists in the running kernel,
32 * or whether this bug has been fixed.
33 */
34
35 #include <stdio.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <sys/types.h>
39 #include <unistd.h>
40 #include "tst_test.h"
41
42 #define TIMEOUT 5
43
44 static void do_child(void);
45 static void sigproc(int sig);
46 static volatile sig_atomic_t end;
47 static char init_cwd[PATH_MAX];
48
verify_getcwd(void)49 static void verify_getcwd(void)
50 {
51 int status;
52 char cur_cwd[PATH_MAX];
53 pid_t child;
54
55 child = SAFE_FORK();
56 if (child == 0)
57 do_child();
58
59 while (1) {
60 SAFE_GETCWD(cur_cwd, PATH_MAX);
61 if (strncmp(init_cwd, cur_cwd, PATH_MAX)) {
62 tst_res(TFAIL, "initial current work directory is "
63 "%s, now is %s. Bug is reproduced!",
64 init_cwd, cur_cwd);
65 break;
66 }
67
68 if (end) {
69 tst_res(TPASS, "Bug is not reproduced!");
70 break;
71 }
72 }
73
74 SAFE_KILL(child, SIGKILL);
75 SAFE_WAITPID(child, &status, 0);
76 }
77
setup(void)78 static void setup(void)
79 {
80 if (tst_ncpus() == 1)
81 tst_brk(TCONF, "This test needs two cpus at least");
82
83 SAFE_SIGNAL(SIGALRM, sigproc);
84
85 alarm(TIMEOUT);
86
87 SAFE_GETCWD(init_cwd, PATH_MAX);
88 }
89
sigproc(int sig)90 static void sigproc(int sig)
91 {
92 end = sig;
93 }
94
do_child(void)95 static void do_child(void)
96 {
97 unsigned int i = 0;
98 char c_name[PATH_MAX] = "testfile", n_name[PATH_MAX];
99
100 SAFE_TOUCH(c_name, 0644, NULL);
101
102 while (1) {
103 snprintf(n_name, PATH_MAX, "testfile%u", i++);
104 SAFE_RENAME(c_name, n_name);
105 strncpy(c_name, n_name, PATH_MAX);
106 }
107 }
108
109 static struct tst_test test = {
110 .setup = setup,
111 .test_all = verify_getcwd,
112 .needs_tmpdir = 1,
113 .forks_child = 1
114 };
115