Support non-POSIX TZ strings

[Brian Inglis]

On 2022-02-14 12:58, jdoubleu wrote:
> On 22-02-14 10:10-0700, Brian Inglis wrote:

>> [..] but we should start with the actual POSIX spec under TZ

> Yes, that is exactly what I meant: Newlib supporting the <> (angle 
> brackets) syntax.
> I didn't know that it was actually part of POSIX spec, since so many 
> libs actually don't implement it.

Most should have by now if maintained: we should be a laggard! ;^>

>> The BSD or TZcode implementations could probably be adapted [..]

> It looks like the TZcode implementation by Paul Eggert uses a different 
> approach to parsing the strings, than the current implementation in 
> newlib 
> (https://sourceware.org/git/?p=newlib-cygwin.git;a=blob;f=newlib/libc/time/tzset_r.c). 
> I'm not sure, if you want to copy the code over or use changes by e.g. 
> Earle F. Philhower from 
> https://github.com/earlephilhower/newlib-xtensa/pull/14.
> Because of the above question, I'm not sure how to continue on this. I 
> would like to contribute myself and submit an implementation, but I'll 
> wait for feedback by other maintainers, first.

Upstream sources like BSDs or TZcode official reference implementations 
are normally preferred because they are feature complete, regularly 
maintained, feature test and standards compliant, vulnerabilities 
checked, issues reported, and promptly fixed.

I checked the BSDs and they seem to have adopted or adapted the TZcode 
official reference implementation, so I am not sure from where it may 
have been adopted, or whether it is original: the maintainer Jeff 
Johnson may remember.

I also wonder if the GMT defaults should be updated to UTC.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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