Hello Paul,
On 06/19/2018 03:30 AM, Paul Eggert wrote:
> Make tzfile.5 a copy of the upstream tzdb version, except that
> the tzdb version's first line is replaced by man-pages
> boilerplate.
Thanks for sending these patches. I have a question and an observation.
The pages in "man-pages" document the glibc provided versions of
tzfile/zdump/zic, AFAIK. Do those programs in turn come from the
upstream tzdb project? If so, what's the rationale for that?
I ask, because it's kind of an odd situation to be running two
versions of these manual pages, and I wonder if there is anyway
of rationalizing this situation (which also relates to my
observation below). For example, one thing I ask myself is:
should man-pages be carrying copies of these pages, or should
they be best carried in a single location (tzdb?).
(By the way, where is the upstream home of tzdb?)
> This has the following effect:
>
> Do some minor spec fixes, notably about time type 0
> and empty TZ strings. Omit some changes that were made on the
> man-pages side, notably by changing "timezone" back to the
> preferred-upstream "time zone", and by omitting formatting
> glitches.
So, here we have a "conflict of standards". Over the years, I've
put considerable effort into bringing uniformity to the pages
in "man-pages". I inherited an almighty hodge-podge of formatting
and spelling inconsistencies, which I've worked fairly hard to
repair. So, my natural inclination is to keep the consistency
that I've worked to create.
You introduce some (from my point of view) special-case formatting
(which, I assume comes from the upstream project). Leaving that
aside, I'll just focus on the spelling example. When I inherited the
project, the pages used a mixture of "time zone" and "timezone",
with the former predominant. I nevertheless standardized on the
latter, and although I don't recall for sure, I suspect it was
because that is the spelling used in POSIX. (As an aside,
there's an argument that--because POSIX--tzdb might want to consider
switching spellings.) I'm not religious about the particular choice
(although I have naturally now got used to the particular
choice I made some years ago), but I did make that choice because I
want consistency within the project, and I'm reluctant to introduce
inconsistency.
Thanks,
Michael
> ---
> man5/tzfile.5 | 62 +++++++++++++++++++++++++++++----------------------
> 1 file changed, 35 insertions(+), 27 deletions(-)
>
> diff --git a/man5/tzfile.5 b/man5/tzfile.5
> index 46e083930..1d3b30b23 100644
> --- a/man5/tzfile.5
> +++ b/man5/tzfile.5
> @@ -7,7 +7,7 @@
> .\"
> .TH TZFILE 5 2017-08-04 "" "Linux Programmer's Manual"
> .SH NAME
> -tzfile \- timezone information
> +tzfile \- time zone information
> .SH DESCRIPTION
> .ie '\(lq'' .ds lq \&"\"
> .el .ds lq \(lq\"
> @@ -16,7 +16,7 @@ tzfile \- timezone information
> .de q
> \\$3\*(lq\\$1\*(rq\\$2
> ..
> -The timezone information files used by
> +The time zone information files used by
> .BR tzset (3)
> are typically found under a directory with a name like
> .IR /usr/share/zoneinfo .
> @@ -24,7 +24,7 @@ These files begin with a 44-byte header containing the following fields:
> .IP * 2
> The magic four-byte ASCII sequence
> .q "TZif"
> -identifies the file as a timezone information file.
> +identifies the file as a time zone information file.
> .IP *
> A byte identifying the version of the file's format
> (as of 2017, either an ASCII NUL, or
> @@ -59,12 +59,12 @@ The number of local time types for which data entries are stored
> in the file (must not be zero).
> .TP
> .I tzh_charcnt
> -The number of bytes of timezone abbreviation strings
> +The number of bytes of time zone abbreviation strings
> stored in the file.
> .RE
> .PP
> The above header is followed by the following fields, whose lengths
> -vary depend on the contents of the header:
> +depend on the contents of the header:
> .IP * 2
> .I tzh_timecnt
> four-byte signed integer values sorted in ascending order.
> @@ -77,23 +77,26 @@ at which the rules for computing local time change.
> one-byte unsigned integer values;
> each one tells which of the different types of local time types
> described in the file is associated with the time period
> -starting with the same-indexed transition time.
> +starting with the same-indexed transition time
> +and continuing up to but not including the next transition time
> +(or continuing for one second, if this is the last transition).
> These values serve as indices into the next field.
> .IP *
> .I tzh_typecnt
> .I ttinfo
> entries, each defined as follows:
> -.PP
> -.in +4n
> -.EX
> +.in +.5i
> +.sp
> +.nf
> +.ta .5i +\w'unsigned char\0\0'u
> struct ttinfo {
> - int32_t tt_gmtoff;
> - unsigned char tt_isdst;
> - unsigned char tt_abbrind;
> + int32_t tt_gmtoff;
> + unsigned char tt_isdst;
> + unsigned char tt_abbrind;
> };
> -.EE
> -.in
> -.PP
> +.in -.5i
> +.fi
> +.sp
> Each structure is written as a four-byte signed integer value for
> .IR tt_gmtoff ,
> in a standard byte order, followed by a one-byte value for
> @@ -110,7 +113,7 @@ should be set by
> .BR localtime (3)
> and
> .I tt_abbrind
> -serves as an index into the array of timezone abbreviation bytes
> +serves as an index into the array of time zone abbreviation bytes
> that follow the
> .I ttinfo
> structure(s) in the file.
> @@ -133,15 +136,15 @@ transitions always separated by at least 28 days minus 1 second.
> standard/wall indicators, each stored as a one-byte value;
> they tell whether the transition times associated with local time types
> were specified as standard time or wall clock time,
> -and are used when a timezone file is used in handling POSIX-style
> -timezone environment variables.
> +and are used when a time zone file is used in handling POSIX-style
> +time zone environment variables.
> .IP *
> .I tzh_ttisgmtcnt
> UT/local indicators, each stored as a one-byte value;
> they tell whether the transition times associated with local time types
> were specified as UT or local time,
> -and are used when a timezone file is used in handling POSIX-style
> -timezone environment variables.
> +and are used when a time zone file is used in handling POSIX-style
> +time zone environment variables.
> .PP
> The
> .BR localtime (3)
> @@ -157,7 +160,7 @@ if either
> is zero or the time argument is less than the first transition time recorded
> in the file.
> .SS Version 2 format
> -For version-2-format timezone files,
> +For version-2-format time zone files,
> the above header and data are followed by a second header and data,
> identical in format except that
> eight bytes are used for each transition time or leap second time.
> @@ -165,21 +168,26 @@ eight bytes are used for each transition time or leap second time.
> After the second header and data comes a newline-enclosed,
> POSIX-TZ-environment-variable-style string for use in handling instants
> after the last transition time stored in the file
> -(with nothing between the newlines if there is no POSIX representation for
> -such instants).
> -The POSIX-style string must agree with the local time type after
> -both data's last transition times; for example, given the string
> +or for all instants if the file has no transitions.
> +The POSIX-style TZ string is empty (i.e., nothing between the newlines)
> +if there is no POSIX representation for such instants.
> +If nonempty, the POSIX-style TZ string must agree with the local time
> +type after both data's last transition times if present;
> +for example, given the string
> .q "WET0WEST,M3.5.0,M10.5.0/3"
> then if a last transition time is in July, the transition's local time
> type must specify a daylight-saving time abbreviated
> .q "WEST"
> that is one hour east of UT.
> +Also, if there is at least one transition, time type 0 is associated
> +with the time period from the indefinite past up to but not including
> +the earliest transition time.
> .SS Version 3 format
> -For version-3-format timezone files, the POSIX-TZ-style string may
> +For version-3-format time zone files, the POSIX-TZ-style string may
> use two minor extensions to the POSIX TZ format, as described in
> .BR newtzset (3).
> First, the hours part of its transition times may be signed and range from
> -\-167 through 167 instead of the POSIX-required unsigned values
> +\*-167 through 167 instead of the POSIX-required unsigned values
> from 0 through 24.
> Second, DST is in effect all year if it starts
> January 1 at 00:00 and ends December 31 at 24:00 plus the difference
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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