tools/testing/selftests/tty/tty_tstamp_update.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <errno.h>
   4 #include <stdbool.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <sys/stat.h>
   9 #include <unistd.h>
  10 #include <linux/limits.h>
  11
  12 #include "../kselftest.h"
  13
  14 #define MIN_TTY_PATH_LEN 8
  15
  16 static bool tty_valid(char *tty)
  17 {
  18         if (strlen(tty) < MIN_TTY_PATH_LEN)
  19                 return false;
  20
  21         if (strncmp(tty, "/dev/tty", MIN_TTY_PATH_LEN) == 0 ||
  22             strncmp(tty, "/dev/pts", MIN_TTY_PATH_LEN) == 0)
  23                 return true;
  24
  25         return false;
  26 }
  27
  28 static int write_dev_tty(void)
  29 {
  30         FILE *f;
  31         int r = 0;
  32
  33         f = fopen("/dev/tty", "r+");
  34         if (!f)
  35                 return -errno;
  36
  37         r = fprintf(f, "hello, world!\n");
  38         if (r != strlen("hello, world!\n"))
  39                 r = -EIO;
  40
  41         fclose(f);
  42         return r;
  43 }
  44
  45 int main(int argc, char **argv)
  46 {
  47         int r;
  48         char tty[PATH_MAX] = {};
  49         struct stat st1, st2;
  50         int result = KSFT_FAIL;
  51
  52         ksft_print_header();
  53         ksft_set_plan(1);
  54
  55         r = readlink("/proc/self/fd/0", tty, PATH_MAX);
  56         if (r < 0) {
  57                 ksft_print_msg("readlink on /proc/self/fd/0 failed: %m\n");
  58                 goto out;
  59         }
  60
  61         if (!tty_valid(tty)) {
  62                 ksft_print_msg("invalid tty path '%s'\n", tty);
  63                 result = KSFT_SKIP;
  64                 goto out;
  65
  66         }
  67
  68         r = stat(tty, &st1);
  69         if (r < 0) {
  70                 ksft_print_msg("stat failed on tty path '%s': %m\n", tty);
  71                 goto out;
  72         }
  73
  74         /* We need to wait at least 8 seconds in order to observe timestamp change */
  75         /* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fbf47635315ab308c9b58a1ea0906e711a9228de */
  76         sleep(10);
  77
  78         r = write_dev_tty();
  79         if (r < 0) {
  80                 ksft_print_msg("failed to write to /dev/tty: %s\n",
  81                                strerror(-r));
  82                 goto out;
  83         }
  84
  85         r = stat(tty, &st2);
  86         if (r < 0) {
  87                 ksft_print_msg("stat failed on tty path '%s': %m\n", tty);
  88                 goto out;
  89         }
  90
  91         /* We wrote to the terminal so timestamps should have been updated */
  92         if (st1.st_atim.tv_sec == st2.st_atim.tv_sec &&
  93             st1.st_mtim.tv_sec == st2.st_mtim.tv_sec) {
  94                 ksft_print_msg("tty timestamps not updated\n");
  95                 goto out;
  96         }
  97
  98         ksft_print_msg(
  99                 "timestamps of terminal '%s' updated after write to /dev/tty\n", tty);
 100         result = KSFT_PASS;
 101
 102 out:
 103         ksft_test_result_report(result, "tty_tstamp_update\n");
 104
 105         ksft_finished();
 106 }