[LTP] [POSIX][PATCH] sem_wait: Setting a range for time checking.

[tangchen <tangchen@cn.fujitsu.com>]

Hi,

According to POSIX, many historical implementations (including Version 7 
and System V) allow an alarm to occur up to a second early. Other 
implementations allow alarms up to half a second or one clock tick early 
or do not allow them to occur early at all. That means, the SIGALRM sent 
by alarm() could arrive a little earlier. So, even if sem_wait() is 
blocked, test could still fail.
Setting a range for time checking would be better. When sem_wait() is 
block and then be interrupted by SIGALRM, if the time is in this range, 
test is passed.

Signed-off-by: tangchen <tangchen@cn.fujitsu.com>
---
  .../conformance/interfaces/sem_wait/13-1.c         |    6 ++++--
  1 files changed, 4 insertions(+), 2 deletions(-)

diff --git 
a/testcases/open_posix_testsuite/conformance/interfaces/sem_wait/13-1.c 
b/testcases/open_posix_testsuite/conformance/interfaces/sem_wait/13-1.c
index 7bf547c..f30bba5 100644
--- a/testcases/open_posix_testsuite/conformance/interfaces/sem_wait/13-1.c
+++ b/testcases/open_posix_testsuite/conformance/interfaces/sem_wait/13-1.c
@@ -83,6 +83,8 @@
  /******************************************************************************/
  /***************************    Test case   
***********************************/
  /******************************************************************************/
+#define RANGE 1000000    /* 1000000 nsec */
+
  sem_t sem;

  void handler(int sig)
@@ -163,7 +165,7 @@ int main(int argc, char * argv[])
      }

      if (((ts_fin.tv_sec - ts_ref.tv_sec) * 1000000000) +
-        (ts_fin.tv_nsec - ts_ref.tv_nsec) < 1000000000)
+        (ts_fin.tv_nsec - ts_ref.tv_nsec) < (1000000000 - RANGE))
      {
          output("Ts: %d.%9.9d  ->  %d.%9.9d\n", ts_ref.tv_sec, 
ts_ref.tv_nsec, ts_fin.tv_sec, ts_fin.tv_nsec);
          FAILED("The sem_wait call did not block");
@@ -185,4 +187,4 @@ int main(int argc, char * argv[])
  #endif

      PASSED;
-}
\ No newline at end of file
+}
-- 
1.7.1

-- 
Best Regards,
Tang chen
--------------------------------------------------



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