Re: [PATCH 2/2] newlib/libc/time/tzset_r.c(_tzset_unlocked_r): POSIX angle bracket <> support

Hi,

On 2/25/2022 5:39 PM, Brian Inglis wrote:
> 
> define POSIX specified minimum TZ abbr size 3 TZNAME_MIN
> use limits.h TZNAME_MAX, _POSIX_TZNAME_MAX, unistd.h sysconf(_SC_TZNAME_MAX)
> issue error if no symbols defined (document fallback value in case required)
> allow POSIX angle bracket < > quoted signed alphanumeric tz abbr e.g. <MESZ+0330>
> allow POSIX unquoted alphabetic tz abbr e.g. MESZ
> apply same changes for DST tz abbr
> ---
>   newlib/libc/time/tzset_r.c | 74 ++++++++++++++++++++++++++++++++------
>   1 file changed, 64 insertions(+), 10 deletions(-)
> 

> +      /* 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])
> +        return;

Is it safe to use the minus (-) as first char in the sscanf format set: 
"%10[-+0-9A-Za-z]%n"?

Newlib's sscanf docs states 
(https://sourceware.org/newlib/libc.html#sscanf):
> There is also a range facility which you can use as a shortcut. %[0-9] matches all decimal digits. The hyphen must not be the first or last character in the set.

Cheers
---
🙎🏻‍♂️ jdoubleu