Re: [Check-devel] Failures in check_check and check_check_export

[Ken M. <zar...@nt...>]

On Sun, May 24, 2020 at 11:21:34AM -0700, Branden Archer wrote:
> Hi Ken.
> 

Hi Branden,

it's taken me a little while to get back to this, but here we go:

> Thanks for taking a look at the logs, Chris.
> 
> I'd like to give another look over the logs to see what may be amiss.
> 
[...]
> 
> and all those should report "Passed". I notice that there are two tests
> which are not reporting the expected result:
> 
> check_check_master.c:746:F:Core Tests:test_check_all_msgs:179: For
> test 179:Signal Tests:test_fpe expected 'Received signal 8 (Floating
> point exception)', got 'Passed'
> check_check_master.c:746:F:Core Tests:test_check_all_msgs:180: For
> test 180:Signal Tests:test_mark_point expected 'Received signal 8
> (Floating point exception)', got 'Shouldn't reach here'
> 
> 
> Both of these failures are related to raising SIGFPE. Looking at the first
> test, test_fpe:
> 
> 
> START_TEST(test_fpe)
> 
> {
> 
>   record_test_name(tcase_name());
> 
>   record_failure_line_num(__LINE__-4); /* -4 as the failure is reported at
> START_TEST() */
> 
>   raise (SIGFPE);
> 
> }
> 
> 
> Apparently on the system under test raise(SIGFPE) is either not causing a
> signal or Check is not able to detect the signal. Other signals being
> tested (such as SIGSEGV in test_segv) are being correctly detected.
> 

While going through the details of my other package tests in this
build, I noticed that bash seemed to be failing because it didn't
SIGFPE. ...

> The signal tests are only enabled with fork() is enabled. If fork() is
> disabled the test will not be run, as it will not be relevant (e.g. Check
> cannot detect signals unless the test are run from within their own
> processes).
> 
> I suggest looking into an example program that raises a SIGFPE and
> determining if it does cause a failure or not. For example. on my OSX
> system:
> 
> Brandens-MBP:raise brarcher$ cat test.c
> 
> #include <stdio.h>
> 
> #include <signal.h>
> 
> 
> int main() {
> 
>   printf("Before\n");
> 
>   raise(SIGFPE);
> 
>   printf("After\n");
> 
>   return 0;
> 
> }
> 
> Brandens-MBP:raise brarcher$ gcc test.c
> 
> Brandens-MBP:raise brarcher$ ./a.out
> 
> Before
> 
> Floating point exception: 8
> 
> Brandens-MBP:raise brarcher$
> 
> 
> Hope it helps.
> 
> - Branden
> 

Using that program:

ken@plexi ~/check-debug $vim test.c
ken@plexi ~/check-debug $gcc test.c
ken@plexi ~/check-debug $./a.out 
Before
After

So I am indeed not getting that signal.

However, if I change the program to do a division by zero

ken@plexi ~/check-debug $diff -u test.c divbyzero.c 
--- test.c	2020-05-26 17:48:11.655277178 +0100
+++ divbyzero.c	2020-05-26 17:59:22.661766358 +0100
@@ -5,13 +5,18 @@
 
 int main() {
 
+ int a = 1000;
+ int z = 0;
+ int result;
+
   printf("Before\n");
 
-  raise(SIGFPE);
+  //raise(SIGFPE);
+  result = a / z;
 
   printf("After\n");
 
-  return 0;
+  return result;
 
 }


I get the exception -

ken@plexi ~/check-debug $./divbyzero 
Before
Floating point exception

So, raise on its own apparently doesn't generate the exception.

ĸen
-- 
Do you not know that, what you belittle by the name tree is but the
mere four-dimensional analogue of a whole multidimensional universe
which - no, I can see you do not.  -- Druellae (a Dryad)