Re: [PATCH] add tests for tzset(3)

[Dimitar Dimitrov <dimitar@dinux.eu>]

On Mon, Apr 11, 2022 at 01:17:16PM +0200, jdoubleu wrote:
> Hi,
> 
> looks like I'm running the testsuite against glibc and not newlib (for
> target x86_64-pc-linux-gnu). I'm not even sure whether there's a backend for
> linux.
> 
> I'm currently trying to run only the tzset code against the test vectors
> (like Brian Inglis did[1]).
> 
> At least it show, that the newlib implementation differs from glibc. Maybe
> the test case is flawed and it should indeed fail.
> 
> > 6:20:12 is the timezone string of the previous test case, whose tzset
> > call was successful. Looking at the current code, this is expected
> > behaviour.
> 
> Okay. Looks like the condition[2] fails. The question is, which part of it
> does?

I believe it is the ('>' != tzenv[n]) check that fails, because the
maximum parsed string limit of 10 has been reached and n=10.

> 
> I've appended a patch, which prints all variables when the condition fails.
> Could you please apply the patch and then recompile and re-run the tests
> again?

Here is the result for arm-none-eabi:
parsing name: tzenv="+0123456789ABCDEF>3:33:33", res=1, n=10, tzenv[n] = 9
Assertion failed! Expected 1647906533 to equal 1647916532. winter time, timezone = "<+0123456789ABCDEF>3:33:33"

I assume you no longer need assembly output from compiler?
> 
> I've previously noticed something with the sscanf format[3].
> 
> > Perhaps TZ should be reset to UTC before the bail out?
> 
> I don't think the implementation should fall back to UTC whenever parsing
> failed. It apparently doesn't in glibc. I'm not sure if the behavior is
> specified somewhere.

The tzset manual page says that UTC is used if TZ cannot be parsed:
https://man7.org/linux/man-pages/man3/tzset.3.html

> 
> Maybe resetting it before each test case is a good idea, though. That makes
> it clearer, why the test case failed.
> 
> > With that chunk removed, as shown below:
> >     {"3:33:33",               IN_SECONDS(3, 33, 33),   NO_TIME},                 // truncates the name (17 + 1)
> > I still get:
> >   Assertion failed! Expected 1647906533 to equal 1647916532. winter time, timezone = "3:33:33"
> 
> My bad; "3:33:33" isn't a valid timezone string. It has to be prefixed by a
> name e.g. "MESZ" or "<+00>", as you tried. That explains why it is also
> failing.
> 
> 
> Thanks for your effort so far!
> 
> 
> [1]: https://sourceware.org/pipermail/newlib/2022/019529.html
> [2]: https://sourceware.org/git/?p=newlib-cygwin.git;a=blob;f=newlib/libc/time/tzset_r.c;h=9cb30b188f989f65ec9eb6417f5d74020f8c72e9;hb=HEAD#l57
> [3]: https://sourceware.org/pipermail/newlib/2022/019535.html
> 
> 
> Cheers
> ---
> 🙎🏻‍♂️ jdoubleu

> From 8c698dc63f765d4a5b3a49a25850c1738279d68d Mon Sep 17 00:00:00 2001
> From: jdoubleu <hi@jdoubleu.de>
> Date: Mon, 11 Apr 2022 13:10:38 +0200
> Subject: [PATCH] debug print condition values of tz string name parsing
> 
> ---
>  newlib/libc/time/tzset_r.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/newlib/libc/time/tzset_r.c b/newlib/libc/time/tzset_r.c
> index 9cb30b188..e20a32a62 100644
> --- a/newlib/libc/time/tzset_r.c
> +++ b/newlib/libc/time/tzset_r.c
> @@ -54,9 +54,11 @@ _tzset_unlocked_r (struct _reent *reent_ptr)
>        ++tzenv;
>  
>        /* quit if no items, too few or too many chars, or no close quote '>' */
> -      if (sscanf (tzenv, "%10[-+0-9A-Za-z]%n", __tzname_std, &n) <= 0
> -		|| n < TZNAME_MIN || TZNAME_MAX < n || '>' != tzenv[n])
> +      int res = sscanf (tzenv, "%10[-+0-9A-Za-z]%n", __tzname_std, &n);
> +      if (res <= 0 || n < TZNAME_MIN || TZNAME_MAX < n || '>' != tzenv[n]) {
> +        printf("parsing name: tzenv=\"%s\", res=%d, n=%d, tzenv[n] = %c\n", tzenv, res, n, tzenv[n]);
>          return;
> +      }
>  
>        ++tzenv;	/* bump for close quote '>' */
>      }
> -- 
> 2.35.1
>