[PATCH] tst: Provide Y2038 tests for mktime (tst-mktime4.c)

[Lukasz Majewski]

Hi Joseph,

> On Mon, 25 Jan 2021, Lukasz Majewski wrote:
> 
> > +  /* Check that mktime(1970-01-01 00:00:00) returns 0.  */
> > +  test_mktime_helper (&tm0, 0);
> > +
> > +  /* Check that mktime(2038-01-19 03:14:07) returns 0x7FFFFFFF.  */
> > +  test_mktime_helper (&tmY2038, 0x7fffffff);
> > +
> > +  /* Check that mktime(2038-01-19 03:14:08) returns 0x80000000
> > +     (time_t overflow).  */
> > +  if (sizeof (time_t) > 4)
> > +    {
> > +      tmY2038.tm_sec++;
> > +      test_mktime_helper (&tmY2038, 0x80000000);
> > +    }
> > +  else
> > +    FAIL_UNSUPPORTED ("32-bit time_t");  
> 
> FAIL_UNSUPPORTED causes the whole test to report an UNSUPPORTED
> status. If a test has a mixture of assertions that work with 32-bit
> time and assertions that only work for 64-bit time, I think those
> should be split into separate tests so that those tests that make
> sense with 32-bit time still produce results in that case.
> 

The idea behind this FAIL_UNSUPPORTED when sizeof(time_t) <= 4 is to:

1. On 32 bit ports - check correct operation of mktime for 32 bit
time_t. If those checks fail, then we fail the test. Tests which require
64 bit size of time_t will not be supported until -D_TIME_BITS=64 is
supported in glibc.

2. On 64 bit ports - the test will either end without errors or fail.

3. I do have corresponding test - tst-mktime4-y2038.c [1] which only has
following lines:

#define _TIME_BITS 64
#define _FILE_OFFSET_BITS 64

#include "tst-mktime4.c"

Which will either pass or fail when 64 bit time_t support is added on
ports with __WORDSIZE=32 && __TIMESIZE != 64.

However, there is no point to send tst-mktime4-y2038.c until the
above feature is supported.


Links:
[1] - https://github.com/lmajewski/y2038_glibc/commits/y2038_edge


Best regards,

Lukasz Majewski

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