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1/*2 * Copyright (c) 2021 Alexey Dobriyan <adobriyan@gmail.com>3 *4 * Permission to use, copy, modify, and distribute this software for any5 * purpose with or without fee is hereby granted, provided that the above6 * copyright notice and this permission notice appear in all copies.7 *8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.15 */16// Test that /proc/*/task never contains "0".17#include <sys/types.h>18#include <dirent.h>19#include <signal.h>20#include <stdio.h>21#include <stdlib.h>22#include <string.h>23#include <unistd.h>24#include <pthread.h>25 26static pid_t pid = -1;27 28static void atexit_hook(void)29{30 if (pid > 0) {31 kill(pid, SIGKILL);32 }33}34 35static void *f(void *_)36{37 return NULL;38}39 40static void sigalrm(int _)41{42 exit(0);43}44 45int main(void)46{47 pid = fork();48 if (pid == 0) {49 /* child */50 while (1) {51 pthread_t pth;52 pthread_create(&pth, NULL, f, NULL);53 pthread_join(pth, NULL);54 }55 } else if (pid > 0) {56 /* parent */57 atexit(atexit_hook);58 59 char buf[64];60 snprintf(buf, sizeof(buf), "/proc/%u/task", pid);61 62 signal(SIGALRM, sigalrm);63 alarm(1);64 65 while (1) {66 DIR *d = opendir(buf);67 struct dirent *de;68 while ((de = readdir(d))) {69 if (strcmp(de->d_name, "0") == 0) {70 exit(1);71 }72 }73 closedir(d);74 }75 76 return 0;77 } else {78 perror("fork");79 return 1;80 }81}82