[PATCH] tst: Add test for sigtimedwait

[Lukasz Majewski <lukma@denx.de>]

This change adds new test to assess sigtimedwait's timeout related
functionality - the sigset_t is configured for SIGUSR1, which will
not be triggered, so sigtimedwait just waits for timeout.

To be more specific - two use cases are checked:
- if sigtimedwait times out immediately when passed struct timespec has
  zero values of tv_nsec and tv_sec.
- if sigtimedwait times out after timeout specified in passed argument
---
 sysdeps/unix/sysv/linux/Makefile           |  5 +-
 sysdeps/unix/sysv/linux/tst-sigtimedwait.c | 61 ++++++++++++++++++++++
 2 files changed, 64 insertions(+), 2 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/tst-sigtimedwait.c

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 41798feb35..a3eba0db01 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -113,8 +113,9 @@ tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
 	 tst-tgkill tst-sysvsem-linux tst-sysvmsg-linux tst-sysvshm-linux \
 	 tst-timerfd tst-ppoll tst-futimens tst-utime tst-utimes \
 	 tst-clock_adjtime tst-adjtimex tst-ntp_adjtime tst-futimes \
-	 tst-lutimes tst-ntp_gettime tst-ntp_gettimex tst-getrusage
-
+	 tst-lutimes tst-ntp_gettime tst-ntp_gettimex tst-getrusage \
+	 tst-sigtimedwait
+	
 # Test for the symbol version of fcntl that was replaced in glibc 2.28.
 ifeq ($(have-GLIBC_2.27)$(build-shared),yesyes)
 tests += tst-ofdlocks-compat
diff --git a/sysdeps/unix/sysv/linux/tst-sigtimedwait.c b/sysdeps/unix/sysv/linux/tst-sigtimedwait.c
new file mode 100644
index 0000000000..95a1b59592
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-sigtimedwait.c
@@ -0,0 +1,61 @@
+/* Test for sigtimedwait timeout
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <time.h>
+#include <errno.h>
+#include <signal.h>
+#include <support/check.h>
+#include <support/xtime.h>
+#include <support/timespec.h>
+#include <stdbool.h>
+
+static int test_sigtimedwait_timeout (bool zero_tmo)
+{
+  /* We wait for half a second.  */
+  struct timespec ts;
+  xclock_gettime (CLOCK_REALTIME, &ts);
+  struct timespec timeout = make_timespec (0, zero_tmo ? 0 : TIMESPEC_HZ/2);
+  ts = timespec_add (ts, timeout);
+
+  /* Set sigset to just wait for timeout.  */
+  sigset_t ss_usr1;
+  sigemptyset (&ss_usr1);
+  sigaddset (&ss_usr1, SIGUSR1);
+
+  int ret = sigtimedwait (&ss_usr1, NULL, &timeout);
+  if (ret != -1)
+    FAIL_EXIT1 ("sigtimedwait failed: %m\n");
+
+  TEST_TIMESPEC_NOW_OR_AFTER (CLOCK_REALTIME, ts);
+
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  /* Check if sigtimedwait exits immediately.  */
+  test_sigtimedwait_timeout (true);
+
+  /* Check if sigtimedwait exits after specified timeout.  */
+  test_sigtimedwait_timeout (false);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
2.20.1