zic: cherrypick support for %z in time zone formats

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.  tzdata2024b and higher require a version of
zic that supports the %z format.  From upstream tzcode.  OK beck@

diff --git a/usr.sbin/zic/zic.8 b/usr.sbin/zic/zic.8
index 0ed93b5..4b0ebdf 100644 (file)
--- a/usr.sbin/zic/zic.8
+++ b/usr.sbin/zic/zic.8
@@ -1,5 +1,5 @@
-.\"    $OpenBSD: zic.8,v 1.5 2022/03/31 17:27:32 naddy Exp $
-.Dd $Mdocdate: March 31 2022 $
+.\"    $OpenBSD: zic.8,v 1.6 2024/09/18 17:05:50 millert Exp $
+.Dd $Mdocdate: September 18 2024 $
 .Dt ZIC 8
 .Os
 .Sh NAME
@@ -240,6 +240,19 @@ The pair of characters
 is used to show where the
 .Dq variable part
 of the time zone abbreviation goes.
+Alternately, a format can use the pair of characters
+.Em %z
+to stand for the UTC offset in the form
+.No \(+- Ns Em hh ,
+.No \(+- Ns Em hhmm ,
+or
+.No \(+- Ns Em hhmmss ,
+using the shortest form that does not lose information, where
+.Em hh ,
+.Em mm ,
+and
+.Em ss
+are the hours, minutes, and seconds east (+) or west (\(mi) of UTC.
 Alternately,
 a slash
 .Pq \&/

diff --git a/usr.sbin/zic/zic.c b/usr.sbin/zic/zic.c
index 420b75f..2f94cd7 100644 (file)
--- a/usr.sbin/zic/zic.c
+++ b/usr.sbin/zic/zic.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: zic.c,v 1.26 2020/10/13 00:18:46 deraadt Exp $        */
+/*     $OpenBSD: zic.c,v 1.27 2024/09/18 17:05:50 millert Exp $        */
 /*
 ** This file is in the public domain, so clarified as of
 ** 2006-07-17 by Arthur David Olson.
@@ -88,6 +88,7 @@ struct zone {
        long            z_gmtoff;
        const char      *z_rule;
        const char      *z_format;
+       char            z_format_specifier;
 
        long            z_stdoff;
 
@@ -107,7 +108,7 @@ static void associate(void);
 static void    convert(long val, char *buf);
 static void    convert64(zic_t val, char *buf);
 static void    dolink(const char *fromfield, const char *tofield);
-static void    doabbr(char *abbr, size_t size, const char *format,
+static void    doabbr(char *abbr, size_t size, struct zone const *zp,
            const char *letters, int isdst, int doquotes);
 static void    eat(const char *name, int num);
 static void    eats(const char *name, int num, const char *rname, int rnum);
@@ -148,6 +149,9 @@ static void writezone(const char *name, const char *string);
 
 extern char    *__progname;
 
+/* Bound on length of what %z can expand to.  */
+enum { PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1 };
+
 static int             charcnt;
 static int             errors;
 static const char      *filename;
@@ -156,7 +160,7 @@ static int          leapseen;
 static int             leapminyear;
 static int             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_time;
 static int             max_year;
@@ -739,7 +743,7 @@ 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 in ruleless zone");
                }
        }
@@ -957,6 +961,7 @@ static int
 inzsub(char **fields, int nfields, int iscont)
 {
        char            *cp;
+       char            *cp1;
        static struct zone      z;
        int             i_gmtoff, i_rule, i_format;
        int             i_untilyear, i_untilmonth;
@@ -986,13 +991,22 @@ inzsub(char **fields, int nfields, int iscont)
        z.z_linenum = linenum;
        z.z_gmtoff = gethms(fields[i_gmtoff], "invalid UTC 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 '%%z' not handled by pre-2015 versions "
+                           "of zic");
+               }
+               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;
@@ -1635,19 +1649,58 @@ writezone(const char *name, const char *string)
                errx(1, "Error writing %s", 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 void
-doabbr(char *abbr, size_t size, const char *format, const char *letters,
+doabbr(char *abbr, size_t size, struct zone const *zp, const char *letters,
     int isdst, int doquotes)
 {
        char    *cp, *slashp;
-       int     len;
+       size_t  len;
+       char const *format = zp->z_format;
 
        slashp = strchr(format, '/');
        if (slashp == NULL) {
-               if (letters == NULL)
-                       strlcpy(abbr, format, size);
-               else
-                       snprintf(abbr, size, format, letters);
+               char letterbuf[PERCENT_Z_LEN_BOUND + 1];
+               if (zp->z_format_specifier == 'z')
+                       letters = abbroffset(letterbuf, -zp->z_gmtoff);
+               else if (letters == NULL)
+                       letters = "%s";
+               snprintf(abbr, size, format, letters);
        } else if (isdst) {
                strlcpy(abbr, slashp + 1, size);
        } else {
@@ -1822,7 +1875,7 @@ stringzone(char *result, size_t size, const struct zone *zpfirst, int zonecount)
        if (stdrp == NULL && (zp->z_nrules != 0 || zp->z_stdoff != 0))
                return;
        abbrvar = (stdrp == NULL) ? "" : stdrp->r_abbrvar;
-       doabbr(result, size, zp->z_format, abbrvar, FALSE, TRUE);
+       doabbr(result, size, zp, abbrvar, FALSE, TRUE);
        ep = end(result, size);
        if (stringoffset(ep, size - (ep - result), -zp->z_gmtoff) != 0) {
                result[0] = '\0';
@@ -1831,7 +1884,7 @@ stringzone(char *result, size_t size, const struct zone *zpfirst, int zonecount)
        if (dstrp == NULL)
                return;
        ep = end(result, size);
-       doabbr(ep, size - (ep - result), zp->z_format, dstrp->r_abbrvar, TRUE, TRUE);
+       doabbr(ep, size - (ep - result), zp, dstrp->r_abbrvar, TRUE, TRUE);
        if (dstrp->r_stdoff != SECSPERMIN * MINSPERHOUR) {
                ep = end(result, size);
                if (stringoffset(ep, size - (ep - result),
@@ -1957,8 +2010,8 @@ outzone(const struct zone *zpfirst, int zonecount)
                startoff = zp->z_gmtoff;
                if (zp->z_nrules == 0) {
                        stdoff = zp->z_stdoff;
-                       doabbr(startbuf, max_abbr_len + 1, zp->z_format,
-                               NULL, stdoff != 0, FALSE);
+                       doabbr(startbuf, max_abbr_len + 1, zp, NULL,
+                           stdoff != 0, FALSE);
                        type = addtype(oadd(zp->z_gmtoff, stdoff),
                                startbuf, stdoff != 0, startttisstd,
                                startttisgmt);
@@ -2041,7 +2094,7 @@ outzone(const struct zone *zpfirst, int zonecount)
                                                    stdoff);
                                                doabbr(startbuf,
                                                    max_abbr_len + 1,
-                                                   zp->z_format,
+                                                   zp,
                                                    rp->r_abbrvar,
                                                    rp->r_stdoff != 0,
                                                    FALSE);
@@ -2052,7 +2105,7 @@ outzone(const struct zone *zpfirst, int zonecount)
                                            stdoff)) {
                                                doabbr(startbuf,
                                                    max_abbr_len + 1,
-                                                   zp->z_format,
+                                                   zp,
                                                    rp->r_abbrvar,
                                                    rp->r_stdoff != 0,
                                                    FALSE);
@@ -2060,7 +2113,7 @@ outzone(const struct zone *zpfirst, int zonecount)
                                }
                                eats(zp->z_filename, zp->z_linenum,
                                    rp->r_filename, rp->r_linenum);
-                               doabbr(ab, max_abbr_len + 1, zp->z_format,
+                               doabbr(ab, max_abbr_len + 1, 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,