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
16static 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
28static 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
45int 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
102out:
103	ksft_test_result_report(result, "tty_tstamp_update\n");
104
105	ksft_finished();
106}
107