strptime.c missing timezone z case

strptime.c missing timezone z case

[Steve Coffman]

I noticed that musl does not support timezone formats that include %z or %Z for timezone, unlike glibc.
Both %d/%b/%Y:%H:%M:%S %z and %d/%b/%Y:%H:%M:%S %Z for instance. 

When I change the timeformat to %d/%b/%Y:%H:%M:%S +0000 it works fine. Since we always use UTC, this works around the problem for us, but will affect any Alpine linux (docker) users that don't.
Looking through the musl source code to strptime.c <http://git.musl-libc.org/cgit/musl/tree/src/time/strptime.c> and strftime.c <https://github.com/BlankOn/musl/blob/master/src/time/strftime.c> I see that while strftime.c has a z case, strptime.c does not. My C is weak so that's about all I can suss out. Not sure if that's at all helpful.

More details of my investigation are here:

https://github.com/fluent/fluent-bit/issues/231


For comparison, glibc handles it this way: https://github.com/bminor/glibc/blob/master/time/strptime_l.c#L741

Re: strptime.c missing timezone z case

[Szabolcs Nagy]

* Steve Coffman <Steve.Coffman@ithaka.org> [2017-04-19 14:03:18 +0000]:
> I noticed that musl does not support timezone formats that include %z or %Z for timezone, unlike glibc.
> Both %d/%b/%Y:%H:%M:%S %z and %d/%b/%Y:%H:%M:%S %Z for instance. 
> 

code using %z or %Z in strptime is nonconforming and thus
nonportable so it should be fixed (it will break not just
on musl).

that said it's a commonly requested feature, but the exact
requirements are not known, different implementations
handle %z differently (some support iso 8601 format only,
others support rfc822 style zone specifiers too) %Z i think
is even more inconsistent across implementations.

> When I change the timeformat to %d/%b/%Y:%H:%M:%S +0000 it works fine. Since we always use UTC, this works around the problem for us, but will affect any Alpine linux (docker) users that don't.
> Looking through the musl source code to strptime.c <http://git.musl-libc.org/cgit/musl/tree/src/time/strptime.c> and strftime.c <https://github.com/BlankOn/musl/blob/master/src/time/strftime.c> I see that while strftime.c has a z case, strptime.c does not. My C is weak so that's about all I can suss out. Not sure if that's at all helpful.
> 
> More details of my investigation are here:
> 
> https://github.com/fluent/fluent-bit/issues/231
> 
> 
> For comparison, glibc handles it this way: https://github.com/bminor/glibc/blob/master/time/strptime_l.c#L741