[PATCH 0/1] newlib/libc/time/tzset_r.c(_tzset_unlocked_r): add POSIX <> quoted abbrs

[Brian Inglis]

On 2022-02-15 15:04, Brian Inglis wrote:
> Submitted a newlib patch which builds okay, but cannot test, as I don't 
> have a newlib platform to run on, and Cygwin uses it's own TZ DB code base.
> It should accept up to 10 character abbreviations for STD and DST 
> matching POSIX specs including anything within < > quoted content.
> If someone needing this could build, test, and send feedback, I'd 
> appreciate it.
> ---
>    newlib/libc/time/tzset_r.c | 68 ++++++++++++++++++++++++++++++++------
>    1 file changed, 58 insertions(+), 10 deletions(-)

Regarding the 10 character limit above, reviewing the POSIX and tzset.c 
documentation, the size limit should be TZNAME_MAX, so some changes may 
need to be made to the values or the code, as _POSIX_TZNAME_MAX is the 
minimum acceptable value:

https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/limits.h.html

and the value used should be that configured:

https://pubs.opengroup.org/onlinepubs/9699919799/functions/sysconf.html

also:

https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xbd_chap08.html#tag_21_08_03_05

newlib/libc/include/sys/unistd.h:#define _SC_TZNAME_MAX			20
newlib/libc/sys/rtems/include/limits.h:#define _POSIX_TZNAME_MAX	3
newlib/libc/sys/rtems/include/limits.h:#define TZNAME_MAX		3
winsup/cygwin/include/limits.h:#define _POSIX_TZNAME_MAX		6

Discussion of whether and how to define and align TZNAME_MAX values are 
welcome: Cygwin punts and leaves it undefined, so developers have a 
choice of using the alternatives unistd.h sysconf(_SC_TZNAME_MAX) or 
_POSIX_TZNAME_MAX.

I am inclined to use if defined in order:
*	limits.h TZNAME_MAX
*	unistd.h sysconf(_SC_TZNAME_MAX) if available
*	limits.h _POSIX_TZNAME_MAX
*	6!

Quoting and limits were changed in The Open Group Technical Standard 
Base Specifications, Issue 6, April 2004; IEEE POSIX 1003.1-2004.

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

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