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 51 ksft_print_header(); 52 ksft_set_plan(1); 53 54 r = readlink("/proc/self/fd/0", tty, PATH_MAX); 55 if (r < 0) 56 ksft_exit_fail_msg("readlink on /proc/self/fd/0 failed: %m\n"); 57 58 if (!tty_valid(tty)) 59 ksft_exit_skip("invalid tty path '%s'\n", tty); 60 61 r = stat(tty, &st1); 62 if (r < 0) 63 ksft_exit_fail_msg("stat failed on tty path '%s': %m\n", tty); 64 65 /* We need to wait at least 8 seconds in order to observe timestamp change */ 66 /* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fbf47635315ab308c9b58a1ea0906e711a9228de */ 67 sleep(10); 68 69 r = write_dev_tty(); 70 if (r < 0) 71 ksft_exit_fail_msg("failed to write to /dev/tty: %s\n", 72 strerror(-r)); 73 74 r = stat(tty, &st2); 75 if (r < 0) 76 ksft_exit_fail_msg("stat failed on tty path '%s': %m\n", tty); 77 78 /* We wrote to the terminal so timestamps should have been updated */ 79 if (st1.st_atim.tv_sec == st2.st_atim.tv_sec && 80 st1.st_mtim.tv_sec == st2.st_mtim.tv_sec) { 81 ksft_test_result_fail("tty timestamps not updated\n"); 82 ksft_exit_fail(); 83 } 84 85 ksft_test_result_pass( 86 "timestamps of terminal '%s' updated after write to /dev/tty\n", tty); 87 return EXIT_SUCCESS; 88 } 89