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 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 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 90 static void sigproc(int sig) 91 { 92 end = sig; 93 } 94 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