The Big Bang hack introduced in 2013d should no longer be needed, now that type 0 is the default type and types are reordered to make this happen. I.e., since we now have a better fix for the Macquarie Island problem reported by Alan Gutierrez in <https://mm.icann.org/pipermail/tz/2013-May/019368.html>, we can revert much of the 2013-05-23 12:19:13 -0700 change “Rework to avoid problem with Australia/Macquarie on 32-bit hosts” and the 2014-05-01 16:32:16 -0700 followup change “zic: improve handling of low-valued time stamps” which caused zic to insert a dummy transition. As a result, zic now generates TZif files that are typically a few bytes shorter, as they were in 2013c and earlier. * Makefile, zic.8: Remove mention of Big Bang. * NEWS: Mention. * zic.c (BIG_BANG, WORK_AROUND_CLIENT_OVERFLOW_BUGS, early_time): Remove. All uses removed. (writezone): New arg DEFAULTTYPE. All callers changed. Simplify by not inserting a dummy transition before the Big Bang. (outzone): Compute default type for use by writezone. (addtt): Don’t second-guess type 0. --- Makefile | 1 - NEWS | 6 +++ zic.8 | 6 --- zic.c | 151 ++++++++++++++++----------------------------------------------- 4 files changed, 44 insertions(+), 120 deletions(-) diff --git a/Makefile b/Makefile index 3705fc0..2289dff 100644 --- a/Makefile +++ b/Makefile @@ -173,7 +173,6 @@ LDLIBS= # Add the following to the end of the "CFLAGS=" line as needed to override # defaults specified in the source code. "-DFOO" is equivalent to "-DFOO=1". -# -DBIG_BANG=-9999999LL if the Big Bang occurred at time -9999999 (see zic.c) # -DDEPRECATE_TWO_DIGIT_YEARS for optional runtime warnings about strftime # formats that generate only the last two digits of year numbers # -DEPOCH_LOCAL if the 'time' function returns local time not UT diff --git a/NEWS b/NEWS index b90e68c..87f675e 100644 --- a/NEWS +++ b/NEWS @@ -27,6 +27,12 @@ Unreleased, experimental changes legacy zones EST5EDT, CST6CDT, MST7MDT, PST8PDT, CET, MET, and EET, which previously used nonzero types for these timestamps. + Because of the type 0 change, zic no longer outputs a dummy + transition at time -2**59 (before the Big Bang), as clients should + no longer need this to handle historical timestamps correctly. + This reverts a change introduced in 2013d and shrinks most TZif + files by a few bytes. + localtime.c no longer requires at least one time type in TZif files that lack transitions or have a POSIX-style TZ string. This future-proofs the code against possible future extensions to the diff --git a/zic.8 b/zic.8 index ba4796e..00d4267 100644 --- a/zic.8 +++ b/zic.8 @@ -591,12 +591,6 @@ produces a single transition to daylight saving at the new UT offset To get separate transitions use multiple zone continuation lines specifying transition instants using universal time. -.PP -timestamps well before the Big Bang are silently omitted from the output. -This works around bugs in software that mishandles large negative time -stamps. Call it sour grapes, but pre-Big-Bang timestamps are -physically suspect anyway. The pre-Big-Bang cutoff time is -approximate and may change in future versions. .SH FILES .ta \w'/usr/share/zoneinfo\0\0'u /etc/localtime default local time zone file diff --git a/zic.c b/zic.c index fd73f66..88153db 100644 --- a/zic.c +++ b/zic.c @@ -948,48 +948,6 @@ dolink(char const *fromfield, char const *tofield, bool staysymlink) static zic_t const min_time = MINVAL(zic_t, TIME_T_BITS_IN_FILE); static zic_t const max_time = MAXVAL(zic_t, TIME_T_BITS_IN_FILE); -/* Estimated time of the Big Bang, in seconds since the POSIX epoch. - rounded downward to the negation of a power of two that is - comfortably outside the error bounds. - - For the time of the Big Bang, see: - - Ade PAR, Aghanim N, Armitage-Caplan C et al. Planck 2013 results. - I. Overview of products and scientific results. - arXiv:1303.5062 2013-03-20 20:10:01 UTC - <https://arxiv.org/pdf/1303.5062v1> [PDF] - - Page 36, Table 9, row Age/Gyr, column Planck+WP+highL+BAO 68% limits - gives the value 13.798 plus-or-minus 0.037 billion years. - Multiplying this by 1000000000 and then by 31557600 (the number of - seconds in an astronomical year) gives a value that is comfortably - less than 2**59, so BIG_BANG is - 2**59. - - BIG_BANG is approximate, and may change in future versions. - Please do not rely on its exact value. */ - -#ifndef BIG_BANG -#define BIG_BANG (- (1LL << 59)) -#endif - -/* If true, work around GNOME glib bug 878 - <https://gitlab.gnome.org/GNOME/glib/issues/878> - by refusing to output timestamps before BIG_BANG. - Such timestamps are physically suspect anyway. - The glib bug is scheduled to be fixed in glib 2.58. - There is a similar bug in 32-bit glibc 2.27 and earlier - <https://sourceware.org/bugzilla/show_bug.cgi?id=19738> - that is scheduled to be fixed in glibc 2.28; - unfortunately a similar bug might persist in 64-bit glibc - though this has not been verified. With all this in mind, - let's hope that the workaround will no longer be needed - in the year 2025. */ -enum { WORK_AROUND_CLIENT_OVERFLOW_BUGS = true }; - -static const zic_t early_time = (WORK_AROUND_CLIENT_OVERFLOW_BUGS - ? BIG_BANG - : MINVAL(zic_t, TIME_T_BITS_IN_FILE)); - /* Return true if NAME is a directory. */ static bool itsdir(char const *name) @@ -1775,7 +1733,8 @@ swaptypes(int i, int j) } static void -writezone(const char *const name, const char *const string, char version) +writezone(const char *const name, const char *const string, char version, + int defaulttype) { register FILE * fp; register ptrdiff_t i, j; @@ -1805,13 +1764,11 @@ writezone(const char *const name, const char *const string, char version) toi = 0; fromi = 0; - while (fromi < timecnt && attypes[fromi].at < early_time) - ++fromi; for ( ; fromi < timecnt; ++fromi) { - if (toi > 1 && ((attypes[fromi].at + + if (toi != 0 && ((attypes[fromi].at + gmtoffs[attypes[toi - 1].type]) <= - (attypes[toi - 1].at + - gmtoffs[attypes[toi - 2].type]))) { + (attypes[toi - 1].at + gmtoffs[toi == 1 ? 0 + : attypes[toi - 2].type]))) { attypes[toi - 1].type = attypes[fromi].type; continue; @@ -1919,8 +1876,8 @@ writezone(const char *const name, const char *const string, char version) for (pass = 1; pass <= 2; ++pass) { register ptrdiff_t thistimei, thistimecnt, thistimelim; register int thisleapi, thisleapcnt, thisleaplim; - int old0, new0; - char omittype[TZ_MAX_TYPES + 1]; + int old0; + char omittype[TZ_MAX_TYPES]; int typemap[TZ_MAX_TYPES]; register int thistypecnt; char thischars[TZ_MAX_CHARS]; @@ -1945,45 +1902,17 @@ writezone(const char *const name, const char *const string, char version) error(_("too many transition times")); thistimelim = thistimei + thistimecnt; thisleaplim = thisleapi + thisleapcnt; - memset(omittype, thistimecnt != timecnt, typecnt); - if (thistimecnt == 0) { - /* - ** No transition times fall in the current - ** (32- or 64-bit) window. - */ - if (typecnt != 0) - omittype[typecnt - 1] = false; - } else { - for (i = thistimei - 1; i < thistimelim; ++i) - if (i >= 0) - omittype[types[i]] = false; - /* - ** For America/Godthab and Antarctica/Palmer - */ - if (thistimei == 0) - omittype[0] = false; - } - - /* Reorder types to make type 0 the first-used standard type - if one is used, otherwise the first-used DST type if one - is used, otherwise no reordering. Use TYPEMAP to swap - OLD0 and NEW0 so that NEW0 appears as type 0 in the output - instead of OLD0. TYPEMAP also omits unused types. */ - omittype[typecnt] = false; /* strlen sentinel */ + memset(omittype, true, typecnt); + omittype[defaulttype] = false; + for (i = thistimei; i < thistimelim; i++) + omittype[types[i]] = false; + + /* Reorder types to make DEFAULTTYPE type 0. + Use TYPEMAP to swap OLD0 and DEFAULTTYPE so that + DEFAULTTYPE appears as type 0 in the output instead + of OLD0. TYPEMAP also omits unused types. */ old0 = strlen(omittype); - new0 = -1; - for (i = 0; i < timecnt; i++) - if (!omittype[types[i]]) { - if (! isdsts[types[i]]) { - new0 = types[i]; - break; - } - if (new0 < 0) - new0 = types[i]; - } - if (new0 < 0) - new0 = old0; - swaptypes(old0, new0); + swaptypes(old0, defaulttype); #ifndef LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH /* @@ -2035,7 +1964,8 @@ writezone(const char *const name, const char *const string, char version) thistypecnt = 0; for (i = old0; i < typecnt; i++) if (!omittype[i]) - typemap[i == old0 ? new0 : i == new0 ? old0 : i] + typemap[i == old0 ? defaulttype + : i == defaulttype ? old0 : i] = thistypecnt++; for (i = 0; i < sizeof indmap / sizeof indmap[0]; ++i) @@ -2133,7 +2063,7 @@ writezone(const char *const name, const char *const string, char version) for (i = old0; i < typecnt; i++) if (!omittype[i]) putc(ttisgmts[i], fp); - swaptypes(old0, new0); + swaptypes(old0, defaulttype); } fprintf(fp, "\n%s\n", string); close_file(fp, directory, name); @@ -2487,6 +2417,7 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount) zic_t one = 1; zic_t y2038_boundary = one << 31; zic_t max_year0; + int defaulttype = -1; max_abbr_len = 2 + max_format_len + max_abbrvar_len; max_envvar_len = 2 * max_abbr_len + 5 * 9; @@ -2595,9 +2526,9 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount) */ stdoff = 0; zp = &zpfirst[i]; - usestart = i > 0 && (zp - 1)->z_untiltime > early_time; + usestart = i > 0 && (zp - 1)->z_untiltime > min_time; useuntil = i < (zonecount - 1); - if (useuntil && zp->z_untiltime <= early_time) + if (useuntil && zp->z_untiltime <= min_time) continue; gmtoff = zp->z_gmtoff; eat(zp->z_filename, zp->z_linenum); @@ -2612,7 +2543,8 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount) if (usestart) { addtt(starttime, type); usestart = false; - } else addtt(early_time, type); + } else + defaulttype = type; } else for (year = min_year; year <= max_year; ++year) { if (useuntil && year > zp->z_untilrule.r_hiyear) break; @@ -2726,6 +2658,8 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount) offset = oadd(zp->z_gmtoff, rp->r_stdoff); type = addtype(offset, ab, rp->r_isdst, rp->r_todisstd, rp->r_todisgmt); + if (defaulttype < 0 && !rp->r_isdst) + defaulttype = type; if (rp->r_hiyear == ZIC_MAX && ! (0 <= lastatmax && ktime < attypes[lastatmax].at)) @@ -2742,11 +2676,14 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount) eat(zp->z_filename, zp->z_linenum); if (*startbuf == '\0') error(_("can't determine time zone abbreviation to use just after until time")); - else addtt(starttime, - addtype(startoff, startbuf, - startoff != zp->z_gmtoff, - startttisstd, - startttisgmt)); + else { + bool isdst = startoff != zp->z_gmtoff; + type = addtype(startoff, startbuf, isdst, + startttisstd, startttisgmt); + if (defaulttype < 0 && !isdst) + defaulttype = type; + addtt(starttime, type); + } } /* ** Now we may get to set starttime for the next zone line. @@ -2761,6 +2698,8 @@ error(_("can't determine time zone abbreviation to use just after until time")); starttime = tadd(starttime, -gmtoff); } } + if (defaulttype < 0) + defaulttype = 0; if (0 <= lastatmax) attypes[lastatmax].dontmerge = true; if (do_extend) { @@ -2788,7 +2727,7 @@ error(_("can't determine time zone abbreviation to use just after until time")); attypes[timecnt - 1].dontmerge = true; } } - writezone(zpfirst->z_name, envvar, version); + writezone(zpfirst->z_name, envvar, version, defaulttype); free(startbuf); free(ab); free(envvar); @@ -2797,20 +2736,6 @@ error(_("can't determine time zone abbreviation to use just after until time")); static void addtt(zic_t starttime, int type) { - if (starttime <= early_time - || (timecnt == 1 && attypes[0].at < early_time)) { - gmtoffs[0] = gmtoffs[type]; - isdsts[0] = isdsts[type]; - ttisstds[0] = ttisstds[type]; - ttisgmts[0] = ttisgmts[type]; - if (abbrinds[type] != 0) - strcpy(chars, &chars[abbrinds[type]]); - abbrinds[0] = 0; - charcnt = strlen(chars) + 1; - typecnt = 1; - timecnt = 0; - type = 0; - } attypes = growalloc(attypes, sizeof *attypes, timecnt, &timecnt_alloc); attypes[timecnt].at = starttime; attypes[timecnt].dontmerge = false; -- 2.7.4