[PATCH v3 2/2] selftests: tty: add selftest for tty timestamp updates

Michal Sekletar
2023-06-13T17:26:46Z

Add new test case which checks that timestamp updates on actual terminal
character device (e.g. /dev/pts/0) happen even if the terminal is
accessed via magic /dev/tty file.

Signed-off-by: Michal Sekletar <msekleta@redhat.com>
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/tty/.gitignore | 2 +
tools/testing/selftests/tty/Makefile | 5 ++
.../testing/selftests/tty/tty_tstamp_update.c | 88 +++++++++++++++++++
4 files changed, 96 insertions(+)
create mode 100644 tools/testing/selftests/tty/.gitignore
create mode 100644 tools/testing/selftests/tty/Makefile
create mode 100644 tools/testing/selftests/tty/tty_tstamp_update.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 90a62cf75008..862f5f9a76a0 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -86,6 +86,7 @@ TARGETS += timers
endif
TARGETS += tmpfs
TARGETS += tpm2
+TARGETS += tty
TARGETS += user
TARGETS += vDSO
TARGETS += mm
diff --git a/tools/testing/selftests/tty/.gitignore b/tools/testing/selftests/tty/.gitignore
new file mode 100644
index 000000000000..fe70462a4aad
--- /dev/null
+++ b/tools/testing/selftests/tty/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+tty_tstamp_update
diff --git a/tools/testing/selftests/tty/Makefile b/tools/testing/selftests/tty/Makefile
new file mode 100644
index 000000000000..50d7027b2ae3
--- /dev/null
+++ b/tools/testing/selftests/tty/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+CFLAGS = -O2 -Wall
+TEST_GEN_PROGS := tty_tstamp_update
+
+include ../lib.mk
diff --git a/tools/testing/selftests/tty/tty_tstamp_update.c b/tools/testing/selftests/tty/tty_tstamp_update.c
new file mode 100644
index 000000000000..0ee97943dccc
--- /dev/null
+++ b/tools/testing/selftests/tty/tty_tstamp_update.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <linux/limits.h>
+
+#include "../kselftest.h"
+
+#define MIN_TTY_PATH_LEN 8
+
+static bool tty_valid(char *tty)
+{
+ if (strlen(tty) < MIN_TTY_PATH_LEN)
+ return false;
+
+ if (strncmp(tty, "/dev/tty", MIN_TTY_PATH_LEN) == 0 ||
+ strncmp(tty, "/dev/pts", MIN_TTY_PATH_LEN) == 0)
+ return true;
+
+ return false;
+}
+
+static int write_dev_tty(void)
+{
+ FILE *f;
+ int r = 0;
+
+ f = fopen("/dev/tty", "r+");
+ if (!f)
+ return -errno;
+
+ r = fprintf(f, "hello, world!\n");
+ if (r != strlen("hello, world!\n"))
+ r = -EIO;
+
+ fclose(f);
+ return r;
+}
+
+int main(int argc, char **argv)
+{
+ int r;
+ char tty[PATH_MAX] = {};
+ struct stat st1, st2;
+
+ ksft_print_header();
+ ksft_set_plan(1);
+
+ r = readlink("/proc/self/fd/0", tty, PATH_MAX);
+ if (r < 0)
+ ksft_exit_fail_msg("readlink on /proc/self/fd/0 failed: %m\n");
+
+ if (!tty_valid(tty))
+ ksft_exit_skip("invalid tty path '%s'\n", tty);
+
+ r = stat(tty, &st1);
+ if (r < 0)
+ ksft_exit_fail_msg("stat failed on tty path '%s': %m\n", tty);
+
+ /* We need to wait at least 8 seconds in order to observe timestamp change */
+ /* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fbf47635315ab308c9b58a1ea0906e711a9228de */
+ sleep(10);
+
+ r = write_dev_tty();
+ if (r < 0)
+ ksft_exit_fail_msg("failed to write to /dev/tty: %s\n",
+ strerror(-r));
+
+ r = stat(tty, &st2);
+ if (r < 0)
+ ksft_exit_fail_msg("stat failed on tty path '%s': %m\n", tty);
+
+ /* We wrote to the terminal so timestamps should have been updated */
+ if (st1.st_atim.tv_sec == st2.st_atim.tv_sec &&
+ st1.st_mtim.tv_sec == st2.st_mtim.tv_sec) {
+ ksft_test_result_fail("tty timestamps not updated\n");
+ ksft_exit_fail();
+ }
+
+ ksft_test_result_pass(
+ "timestamps of terminal '%s' updated after write to /dev/tty\n", tty);
+ return EXIT_SUCCESS;
+}
--
2.40.0