[PATCH] Add support for TZ names with <> in tzset

[Corinna Vinschen]

Hi Earle,

On Dec 12 17:56, Earle F. Philhower, III via Newlib wrote:
> 
> > On 2020-11-16 18:43, C Howland via Newlib wrote:>> On Monday, November 16, 2020 5:30 PM, Brian Inglis wrote:
> >>> On 2020-11-16 08:13, Corinna Vinschen via Newlib wrote:
> >>>> On Nov 14 15:03, Earle F. Philhower, III via Newlib wrote:
> >>>>> Attached is a patch which extends the tzset() function to support a 
> >>>>> format for "unnamed" TZ environment timezones which use "<+/-nn>" as
> >>>>> the timezone name instead of an alphabetic name.  These are supported
> >>>>> in glibc and are present in several major TZ databases that we use on
> >>>>> the ESP8266 Arduino core.  For example,
> ...>>>> Basically this looks ok.  I have two nits, though.>>>> - Now that the scanning got more complicated than a single sscanf call,
> >>>>    this crys out for a helper function doing the actual scanning for
> >>>>    both, std and dst strings.  This could be an inline function which is
> >>>>    only inlined
> >>>>    #if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__)>>>> - The strcat call seems a bit heavy.  What about sth like this instead:
> 
> Thanks Corinna.  I've factored out the common name scanner to its own
> static function, removed the strcat in favor of your suggestion, and
> added documentation in the code about its function.
> 
> However, I'm not sure it makes sense to worry about size/speed
> optimizations here.  This is tzset_r and the normal case is to call
> it ~1 time per application startup to set the localtime offsets
> using the TZ environment variable, and never again.

The size optimization would be the point here in the first place,
the speed optimization by inlining secondary.  However, adding the
aforementioned #if is really not much of a problem to handle both
preferences alike.

Other than that, the patch looks ok.  Can you please send it in `git
format-patch' format when you're ready?


Thanks,
Corinna