[PATCH v2] tst: Provide test for getrusage

[Lukasz Majewski <lukma@denx.de>]

This commit adds test to check if getrusage works correctly. As the
first check - if the wrong 'who' parameter causes errno set to EINVAL.

Next for the ru_{us}time.tv_usec fields it is checked if they are in
microseconds range.

The last check is to perform busy wait loop for 10ms and afterwards
assess if ru_{us}time.tv_sec are not smaller than values read on the
test start.

Changes for v2:
- Add check for EINVAL return value
- Check if getrusage ru_{su}time.tv_usec are in correct microseconds range
- Busy wait for 10ms and then compare getrusage system and user times
  (in seconds) if they are equal or larger than previous ones
---
 resource/Makefile        |  2 +-
 resource/tst-getrusage.c | 67 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 resource/tst-getrusage.c

diff --git a/resource/Makefile b/resource/Makefile
index bd9e716749..e236df3d7c 100644
--- a/resource/Makefile
+++ b/resource/Makefile
@@ -25,6 +25,6 @@ headers	  := sys/resource.h bits/resource.h sys/vlimit.h	\
 routines := getrlimit setrlimit getrlimit64 setrlimit64 getrusage ulimit      \
 	    vlimit vtimes getpriority setpriority nice
 
-tests = tst-getrlimit bug-ulimit1
+tests = tst-getrlimit bug-ulimit1 tst-getrusage
 
 include ../Rules
diff --git a/resource/tst-getrusage.c b/resource/tst-getrusage.c
new file mode 100644
index 0000000000..da721b0613
--- /dev/null
+++ b/resource/tst-getrusage.c
@@ -0,0 +1,67 @@
+/* Test for getrusage.
+   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 <sys/resource.h>
+#include <support/check.h>
+#include <support/timespec.h>
+
+static int
+do_test (void)
+{
+  struct timespec tv_then, tv_now, r;
+  struct rusage ru, ru_then;
+  int ret;
+
+  /* Check for invalid 'who' parameter.  */
+  ret = getrusage (-100, &ru);
+  if (! (ret == -1 && errno == EINVAL))
+    FAIL_EXIT1 ("getrusage failed - EINVAL expected\n");
+
+  /* Check if ru_stime.tv_usec and ru_utime.tv_usec are correct.  */
+  ret = getrusage (RUSAGE_SELF, &ru_then);
+  if (ret == -1)
+    FAIL_EXIT1 ("getrusage failed: %m\n");
+
+  TEST_VERIFY (ru_then.ru_utime.tv_usec >= 0);
+  TEST_VERIFY (ru_then.ru_utime.tv_usec < 1000000);
+
+  TEST_VERIFY (ru_then.ru_stime.tv_usec >= 0);
+  TEST_VERIFY (ru_then.ru_stime.tv_usec < 1000000);
+
+  tv_then = xclock_now (CLOCK_REALTIME);
+  /* Busy wait for 10 miliseconds.  */
+  do
+    {
+      tv_now = xclock_now (CLOCK_REALTIME);
+      r = timespec_sub (tv_now, tv_then);
+    }
+  while (r.tv_nsec <= 10000000);
+
+  ret = getrusage (RUSAGE_SELF, &ru);
+  if (ret == -1)
+    FAIL_EXIT1 ("getrusage failed: %m\n");
+
+  TEST_VERIFY (ru.ru_utime.tv_sec >= ru_then.ru_utime.tv_sec);
+  TEST_VERIFY (ru.ru_stime.tv_sec >= ru_then.ru_stime.tv_sec);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
2.20.1