LXR linux/tools/testing/selftests/proc/proc-loadavg-001.c

   1/*
   2 * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
   3 *
   4 * Permission to use, copy, modify, and distribute this software for any
   5 * purpose with or without fee is hereby granted, provided that the above
   6 * copyright notice and this permission notice appear in all copies.
   7 *
   8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15 */
  16/* Test that /proc/loadavg correctly reports last pid in pid namespace. */
  17#include <errno.h>
  18#include <sched.h>
  19#include <sys/types.h>
  20#include <sys/stat.h>
  21#include <fcntl.h>
  22#include <unistd.h>
  23#include <sys/wait.h>
  24
  25int main(void)
  26{
  27        pid_t pid;
  28        int wstatus;
  29
  30        if (unshare(CLONE_NEWPID) == -1) {
  31                if (errno == ENOSYS || errno == EPERM)
  32                        return 4;
  33                return 1;
  34        }
  35
  36        pid = fork();
  37        if (pid == -1)
  38                return 1;
  39        if (pid == 0) {
  40                char buf[128], *p;
  41                int fd;
  42                ssize_t rv;
  43
  44                fd = open("/proc/loadavg" , O_RDONLY);
  45                if (fd == -1)
  46                        return 1;
  47                rv = read(fd, buf, sizeof(buf));
  48                if (rv < 3)
  49                        return 1;
  50                p = buf + rv;
  51
  52                /* pid 1 */
  53                if (!(p[-3] == ' ' && p[-2] == '1' && p[-1] == '\n'))
  54                        return 1;
  55
  56                pid = fork();
  57                if (pid == -1)
  58                        return 1;
  59                if (pid == 0)
  60                        return 0;
  61                if (waitpid(pid, NULL, 0) == -1)
  62                        return 1;
  63
  64                lseek(fd, 0, SEEK_SET);
  65                rv = read(fd, buf, sizeof(buf));
  66                if (rv < 3)
  67                        return 1;
  68                p = buf + rv;
  69
  70                /* pid 2 */
  71                if (!(p[-3] == ' ' && p[-2] == '2' && p[-1] == '\n'))
  72                        return 1;
  73
  74                return 0;
  75        }
  76
  77        if (waitpid(pid, &wstatus, 0) == -1)
  78                return 1;
  79        if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0)
  80                return 0;
  81        return 1;
  82}
  83