[tz] [PROPOSED PATCH] Support %z in Zone formats
Jon Skeet
skeet at pobox.com
Wed Jul 29 14:55:32 UTC 2015
I've implemented support for this in Noda Time (but it's easily removed if
we decide not to go ahead with it). What's the normal lead time for a
change like this? The commit message states:
> This is a change only to zic; it does not affect the data, which can
still be compiled with older zic versions.
... but presumably that's just saying that you haven't changed the data
*yet*. At some point, we're expecting the data to take advantage of this
functionality, I assume? If so, do we have an expectation of when we'd
first do so?
Jon
On 20 July 2015 at 04:23, Paul Eggert <eggert at cs.ucla.edu> wrote:
> This extends the zic input format to add support for %z, which
> expands to a UTC offset in as-short-as-possible ISO 8601 format.
> It's intended to better support zones that do not have an
> established abbreviation already. This is a change only to zic;
> it does not affect the data, which can still be compiled with
> older zic versions.
> * NEWS, zic.8: Document this.
> * zic.c (struct zone): New member z_format_specifier.
> (PERCENT_Z_LEN_BOUND): New constant.
> (max_abbrvar_len): Initialize to it, rather than to 0.
> (associate, inzsub, doabbr): Add support for %z.
> (abbroffset): New function.
> (doabbr): 2nd arg is now struct zone *, not a char *.
> All callers changed.
> ---
> NEWS | 5 +++++
> zic.8 | 13 +++++++++++
> zic.c | 82
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------
> 3 files changed, 85 insertions(+), 15 deletions(-)
>
> diff --git a/NEWS b/NEWS
> index b7593e7..9eff28c 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -25,6 +25,11 @@ Unreleased, experimental changes
> (Thanks to Jon Skeet and Arthur David Olson.) Constraints on
> simultaneity are now documented.
>
> + The two characters '%z' in a zone format now stand for the UTC
> + offset, e.g., '-07' for seven hours behind UTC and '+0530' for
> + five hours and thirty minutes ahead. This better supports time
> + zone abbreviations conforming to POSIX.1-2001 and later.
> +
> Changes affecting installed data files
>
> Data entries have been simplified for Atlantic/Canary,
> Europe/Simferopol,
> diff --git a/zic.8 b/zic.8
> index dfb01db..94b6753 100644
> --- a/zic.8
> +++ b/zic.8
> @@ -350,6 +350,19 @@ The pair of characters
> is used to show where the
> .q "variable part"
> of the time zone abbreviation goes.
> +Alternately, a format can use the pair of characters
> +.B %z
> +to stand for the UTC offset in the form
> +.RI \(+- hh ,
> +.RI \(+- hhmm ,
> +or
> +.RI \(+- hhmmss ,
> +using the shortest form that does not lose information, where
> +.IR hh ,
> +.IR mm ,
> +and
> +.I ss
> +are the hours, minutes, and seconds east (+) or west (\(mi) of UTC.
> Alternately,
> a slash (/)
> separates standard and daylight abbreviations.
> diff --git a/zic.c b/zic.c
> index 6854033..3c4ae93 100644
> --- a/zic.c
> +++ b/zic.c
> @@ -76,6 +76,7 @@ struct zone {
> zic_t z_gmtoff;
> const char * z_rule;
> const char * z_format;
> + char z_format_specifier;
>
> zic_t z_stdoff;
>
> @@ -130,6 +131,9 @@ static void rulesub(struct rule * rp,
> static zic_t tadd(zic_t t1, zic_t t2);
> static bool yearistype(int year, const char * type);
>
> +/* Bound on length of what %z can expand to. */
> +enum { PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1 };
> +
> static int charcnt;
> static bool errors;
> static bool warnings;
> @@ -139,7 +143,7 @@ static bool leapseen;
> static zic_t leapminyear;
> static zic_t leapmaxyear;
> static int linenum;
> -static int max_abbrvar_len;
> +static int max_abbrvar_len = PERCENT_Z_LEN_BOUND;
> static int max_format_len;
> static zic_t max_year;
> static zic_t min_year;
> @@ -955,7 +959,7 @@ associate(void)
> ** Note, though, that if there's no rule,
> ** a '%s' in the format is a bad thing.
> */
> - if (strchr(zp->z_format, '%') != 0)
> + if (zp->z_format_specifier == 's')
> error("%s", _("%s in ruleless zone"));
> }
> }
> @@ -1170,6 +1174,7 @@ static bool
> inzsub(char **fields, int nfields, bool iscont)
> {
> register char * cp;
> + char * cp1;
> static struct zone z;
> register int i_gmtoff, i_rule, i_format;
> register int i_untilyear, i_untilmonth;
> @@ -1201,13 +1206,21 @@ inzsub(char **fields, int nfields, bool iscont)
> z.z_linenum = linenum;
> z.z_gmtoff = gethms(fields[i_gmtoff], _("invalid UT offset"),
> true);
> if ((cp = strchr(fields[i_format], '%')) != 0) {
> - if (*++cp != 's' || strchr(cp, '%') != 0) {
> + if ((*++cp != 's' && *cp != 'z') || strchr(cp, '%')
> + || strchr(fields[i_format], '/')) {
> error(_("invalid abbreviation format"));
> return false;
> }
> }
> z.z_rule = ecpyalloc(fields[i_rule]);
> - z.z_format = ecpyalloc(fields[i_format]);
> + z.z_format = cp1 = ecpyalloc(fields[i_format]);
> + z.z_format_specifier = cp ? *cp : '\0';
> + if (z.z_format_specifier == 'z') {
> + if (noise)
> + warning(_("format '%s' not handled by pre-2015 versions of
> zic"),
> + z.z_format);
> + cp1[cp - fields[i_format]] = 's';
> + }
> if (max_format_len < strlen(z.z_format))
> max_format_len = strlen(z.z_format);
> hasuntil = nfields > i_untilyear;
> @@ -1890,19 +1903,59 @@ writezone(const char *const name, const char
> *const string, char version)
> free(fullname);
> }
>
> +static char const *
> +abbroffset(char *buf, zic_t offset)
> +{
> + char sign = '+';
> + int seconds, minutes;
> +
> + if (offset < 0) {
> + offset = -offset;
> + sign = '-';
> + }
> +
> + seconds = offset % SECSPERMIN;
> + offset /= SECSPERMIN;
> + minutes = offset % MINSPERHOUR;
> + offset /= MINSPERHOUR;
> + if (100 <= offset) {
> + error(_("%%z UTC offset magnitude exceeds 99:59:59"));
> + return "%z";
> + } else {
> + char *p = buf;
> + *p++ = sign;
> + *p++ = '0' + offset / 10;
> + *p++ = '0' + offset % 10;
> + if (minutes | seconds) {
> + *p++ = '0' + minutes / 10;
> + *p++ = '0' + minutes % 10;
> + if (seconds) {
> + *p++ = '0' + seconds / 10;
> + *p++ = '0' + seconds % 10;
> + }
> + }
> + *p = '\0';
> + return buf;
> + }
> +}
> +
> static size_t
> -doabbr(char *const abbr, const char *const format, const char *const
> letters,
> +doabbr(char *abbr, struct zone const *zp, char const *letters,
> bool isdst, bool doquotes)
> {
> register char * cp;
> register char * slashp;
> register size_t len;
> + char const *format = zp->z_format;
>
> slashp = strchr(format, '/');
> if (slashp == NULL) {
> - if (letters == NULL)
> - strcpy(abbr, format);
> - else sprintf(abbr, format, letters);
> + char letterbuf[PERCENT_Z_LEN_BOUND + 1];
> + if (zp->z_format_specifier == 'z')
> + letters = abbroffset(letterbuf, -zp->z_gmtoff);
> + else if (!letters)
> + letters = "%s";
> + sprintf(abbr, format, letters);
> } else if (isdst) {
> strcpy(abbr, slashp + 1);
> } else {
> @@ -2127,7 +2180,7 @@ stringzone(char *result, const struct zone *const
> zpfirst, const int zonecount)
> if (stdrp == NULL && (zp->z_nrules != 0 || zp->z_stdoff != 0))
> return -1;
> abbrvar = (stdrp == NULL) ? "" : stdrp->r_abbrvar;
> - len = doabbr(result, zp->z_format, abbrvar, false, true);
> + len = doabbr(result, zp, abbrvar, false, true);
> offsetlen = stringoffset(result + len, -zp->z_gmtoff);
> if (! offsetlen) {
> result[0] = '\0';
> @@ -2136,7 +2189,7 @@ stringzone(char *result, const struct zone *const
> zpfirst, const int zonecount)
> len += offsetlen;
> if (dstrp == NULL)
> return compat;
> - len += doabbr(result + len, zp->z_format, dstrp->r_abbrvar, true,
> true);
> + len += doabbr(result + len, zp, dstrp->r_abbrvar, true, true);
> if (dstrp->r_stdoff != SECSPERMIN * MINSPERHOUR) {
> offsetlen = stringoffset(result + len,
> -(zp->z_gmtoff + dstrp->r_stdoff));
> @@ -2307,8 +2360,7 @@ outzone(const struct zone * const zpfirst, const int
> zonecount)
> startoff = zp->z_gmtoff;
> if (zp->z_nrules == 0) {
> stdoff = zp->z_stdoff;
> - doabbr(startbuf, zp->z_format,
> - NULL, stdoff != 0, false);
> + doabbr(startbuf, zp, NULL, stdoff != 0, false);
> type = addtype(oadd(zp->z_gmtoff, stdoff),
> startbuf, stdoff != 0, startttisstd,
> startttisgmt);
> @@ -2400,7 +2452,7 @@ outzone(const struct zone * const zpfirst, const int
> zonecount)
> if (ktime < starttime) {
> startoff =
> oadd(zp->z_gmtoff,
> stdoff);
> - doabbr(startbuf,
> zp->z_format,
> + doabbr(startbuf, zp,
> rp->r_abbrvar,
> rp->r_stdoff != 0,
> false);
> @@ -2410,7 +2462,7 @@ outzone(const struct zone * const zpfirst, const int
> zonecount)
> startoff ==
> oadd(zp->z_gmtoff,
> stdoff)) {
> doabbr(startbuf,
> -
> zp->z_format,
> + zp,
>
> rp->r_abbrvar,
>
> rp->r_stdoff !=
> false,
> @@ -2419,7 +2471,7 @@ outzone(const struct zone * const zpfirst, const int
> zonecount)
> }
> eats(zp->z_filename, zp->z_linenum,
> rp->r_filename, rp->r_linenum);
> - doabbr(ab, zp->z_format, rp->r_abbrvar,
> + doabbr(ab, zp, rp->r_abbrvar,
> rp->r_stdoff != 0, false);
> offset = oadd(zp->z_gmtoff, rp->r_stdoff);
> type = addtype(offset, ab, rp->r_stdoff !=
> 0,
> --
> 2.1.4
>
>
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