Re: [patch] tzset.3: Clarify "daylight" and remove erroneous note.

["Michael Kerrisk (man-pages)" <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 12/10/2015 11:05 PM, Carlos O'Donell wrote:
> When tzset is run the value of daylight is computed
> by looking at all available rules for the application
> of daylight savings. This includes reading the tzdata
> files to determine if there is a transition or not for
> the current timezone. It also includes parsing TZ env
> to see if it specifies custom rules which are used in
> precedence to any tzdata rules. Therefore daylight is
> going to be set if there is a daylight saving rule past,
> present, or future that indicates a transition. We clarify
> that in the man page.
> 
> Lastly, the note about tz_dsttime is not correct and is
> removed. The earlier paragraph about daylight makes it
> clear that it doesn't mean "daylight saving rule applies
> now", and the interaction with tz_dsttime is not correct
> for glibc on Linux (as outlined in my gettimeofday.3 patch
> sent here: http://marc.info/?l=linux-man&m=144977768703615&w=2).

Thanks, Carlos. Applied.

Cheers,

Michael


> Signed-off-by: Carlos O'Donell <carlos-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
> Cheers,
> Carlos.
> 
> diff --git a/man3/tzset.3 b/man3/tzset.3
> index 545bd9c..4786dd9 100644
> --- a/man3/tzset.3
> +++ b/man3/tzset.3
> @@ -70,8 +70,8 @@ This function is automatically called by the
>  other time conversion functions that depend on the timezone.
>  In a System-V-like environment, it will also set the variables \fItimezone\fP
>  (seconds West of UTC) and \fIdaylight\fP (to 0 if this timezone does not
> -have any daylight saving time rules, or to nonzero if there is a time during
> -the year when daylight saving time applies).
> +have any daylight saving time rules, or to nonzero if there is a time,
> +past, present or future when daylight saving time applies).
>  .PP
>  If the
>  .B TZ
> @@ -223,12 +223,6 @@ T}	Thread safety	MT-Safe env locale
>  .SH CONFORMING TO
>  POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
>  .SH NOTES
> -Note that the variable \fIdaylight\fP does not indicate that daylight
> -saving time applies right now.
> -It used to give the number of some
> -algorithm (see the variable \fItz_dsttime\fP in
> -.BR gettimeofday (2)).
> -It has been obsolete for many years but is required by SUSv2.
>  .LP
>  4.3BSD had a function
>  .BI "char *timezone(" zone ", " dst )
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html