[PATCH] tst: Provide test for getrusage

[Lukasz Majewski <lukma@denx.de>]

This commit adds test to check if getrusage provides correct time
accounting for some busy wait loop.

To be more specific - the time is measured in a loop by wrappers
from glibc's libsupport and checked if timeout has passed.

Afterwards, the data from struct rusage, namely ru_stime and ru_utime
is summed up and compared with time from busy waiting.
---
 sysdeps/unix/sysv/linux/Makefile        |  2 +-
 sysdeps/unix/sysv/linux/tst-getrusage.c | 55 +++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 sysdeps/unix/sysv/linux/tst-getrusage.c

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 6a45ac820a..a93fa4ca50 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -113,7 +113,7 @@ 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-lutimes tst-ntp_gettime tst-ntp_gettimex tst-getrusage
 tests-internal += tst-ofdlocks-compat tst-sigcontext-get_pc
 tests-time64 += \
   tst-futimes-time64\
diff --git a/sysdeps/unix/sysv/linux/tst-getrusage.c b/sysdeps/unix/sysv/linux/tst-getrusage.c
new file mode 100644
index 0000000000..068becdadb
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-getrusage.c
@@ -0,0 +1,55 @@
+/* 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 <sys/resource.h>
+#include <support/check.h>
+#include <support/timespec.h>
+
+#define TST_GETRUSAGE_TIMEOUT 1
+
+static int
+do_test (void)
+{
+  struct timespec tv_then, tv_now, gru_u, gru_s, s, r;
+  struct rusage ru;
+  int ret;
+
+  tv_then = xclock_now (CLOCK_REALTIME);
+  /* Busy wait for 1 second.  */
+  do
+  {
+    tv_now = xclock_now (CLOCK_REALTIME);
+    r = timespec_sub (tv_now, tv_then);
+  } while ( r.tv_sec != TST_GETRUSAGE_TIMEOUT );
+
+  ret = getrusage (RUSAGE_SELF, &ru);
+  if (ret == -1)
+    FAIL_EXIT1 ("getrusage failed: %m\n");
+
+  gru_u = make_timespec (ru.ru_utime.tv_sec, ru.ru_utime.tv_usec * 1000);
+  gru_s = make_timespec (ru.ru_stime.tv_sec, ru.ru_stime.tv_usec * 1000);
+  s = timespec_add (gru_u, gru_s);
+
+  TEST_COMPARE (support_timespec_check_in_range
+                ((struct timespec) { 1, 0 }, s, 0.8, 1.2), 1);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
2.20.1