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Diffstat (limited to 'src/timezone/localtime.c')
| -rw-r--r-- | src/timezone/localtime.c | 1904 |
1 files changed, 1904 insertions, 0 deletions
diff --git a/src/timezone/localtime.c b/src/timezone/localtime.c new file mode 100644 index 0000000..fa3c059 --- /dev/null +++ b/src/timezone/localtime.c @@ -0,0 +1,1904 @@ +/* Convert timestamp from pg_time_t to struct pg_tm. */ + +/* + * This file is in the public domain, so clarified as of + * 1996-06-05 by Arthur David Olson. + * + * IDENTIFICATION + * src/timezone/localtime.c + */ + +/* + * Leap second handling from Bradley White. + * POSIX-style TZ environment variable handling from Guy Harris. + */ + +/* this file needs to build in both frontend and backend contexts */ +#include "c.h" + +#include <fcntl.h> + +#include "datatype/timestamp.h" +#include "pgtz.h" + +#include "private.h" +#include "tzfile.h" + + +#ifndef WILDABBR +/* + * Someone might make incorrect use of a time zone abbreviation: + * 1. They might reference tzname[0] before calling tzset (explicitly + * or implicitly). + * 2. They might reference tzname[1] before calling tzset (explicitly + * or implicitly). + * 3. They might reference tzname[1] after setting to a time zone + * in which Daylight Saving Time is never observed. + * 4. They might reference tzname[0] after setting to a time zone + * in which Standard Time is never observed. + * 5. They might reference tm.tm_zone after calling offtime. + * What's best to do in the above cases is open to debate; + * for now, we just set things up so that in any of the five cases + * WILDABBR is used. Another possibility: initialize tzname[0] to the + * string "tzname[0] used before set", and similarly for the other cases. + * And another: initialize tzname[0] to "ERA", with an explanation in the + * manual page of what this "time zone abbreviation" means (doing this so + * that tzname[0] has the "normal" length of three characters). + */ +#define WILDABBR " " +#endif /* !defined WILDABBR */ + +static const char wildabbr[] = WILDABBR; + +static const char gmt[] = "GMT"; + +/* + * The DST rules to use if a POSIX TZ string has no rules. + * Default to US rules as of 2017-05-07. + * POSIX does not specify the default DST rules; + * for historical reasons, US rules are a common default. + */ +#define TZDEFRULESTRING ",M3.2.0,M11.1.0" + +/* structs ttinfo, lsinfo, state have been moved to pgtz.h */ + +enum r_type +{ + JULIAN_DAY, /* Jn = Julian day */ + DAY_OF_YEAR, /* n = day of year */ + MONTH_NTH_DAY_OF_WEEK /* Mm.n.d = month, week, day of week */ +}; + +struct rule +{ + enum r_type r_type; /* type of rule */ + int r_day; /* day number of rule */ + int r_week; /* week number of rule */ + int r_mon; /* month number of rule */ + int32 r_time; /* transition time of rule */ +}; + +/* + * Prototypes for static functions. + */ + +static struct pg_tm *gmtsub(pg_time_t const *, int32, struct pg_tm *); +static bool increment_overflow(int *, int); +static bool increment_overflow_time(pg_time_t *, int32); +static int64 leapcorr(struct state const *, pg_time_t); +static struct pg_tm *timesub(pg_time_t const *, int32, struct state const *, + struct pg_tm *); +static bool typesequiv(struct state const *, int, int); + + +/* + * Section 4.12.3 of X3.159-1989 requires that + * Except for the strftime function, these functions [asctime, + * ctime, gmtime, localtime] return values in one of two static + * objects: a broken-down time structure and an array of char. + * Thanks to Paul Eggert for noting this. + */ + +static struct pg_tm tm; + +/* Initialize *S to a value based on UTOFF, ISDST, and DESIGIDX. */ +static void +init_ttinfo(struct ttinfo *s, int32 utoff, bool isdst, int desigidx) +{ + s->tt_utoff = utoff; + s->tt_isdst = isdst; + s->tt_desigidx = desigidx; + s->tt_ttisstd = false; + s->tt_ttisut = false; +} + +static int32 +detzcode(const char *const codep) +{ + int32 result; + int i; + int32 one = 1; + int32 halfmaxval = one << (32 - 2); + int32 maxval = halfmaxval - 1 + halfmaxval; + int32 minval = -1 - maxval; + + result = codep[0] & 0x7f; + for (i = 1; i < 4; ++i) + result = (result << 8) | (codep[i] & 0xff); + + if (codep[0] & 0x80) + { + /* + * Do two's-complement negation even on non-two's-complement machines. + * If the result would be minval - 1, return minval. + */ + result -= !TWOS_COMPLEMENT(int32) && result != 0; + result += minval; + } + return result; +} + +static int64 +detzcode64(const char *const codep) +{ + uint64 result; + int i; + int64 one = 1; + int64 halfmaxval = one << (64 - 2); + int64 maxval = halfmaxval - 1 + halfmaxval; + int64 minval = -TWOS_COMPLEMENT(int64) - maxval; + + result = codep[0] & 0x7f; + for (i = 1; i < 8; ++i) + result = (result << 8) | (codep[i] & 0xff); + + if (codep[0] & 0x80) + { + /* + * Do two's-complement negation even on non-two's-complement machines. + * If the result would be minval - 1, return minval. + */ + result -= !TWOS_COMPLEMENT(int64) && result != 0; + result += minval; + } + return result; +} + +static bool +differ_by_repeat(const pg_time_t t1, const pg_time_t t0) +{ + if (TYPE_BIT(pg_time_t) - TYPE_SIGNED(pg_time_t) < SECSPERREPEAT_BITS) + return 0; + return t1 - t0 == SECSPERREPEAT; +} + +/* Input buffer for data read from a compiled tz file. */ +union input_buffer +{ + /* The first part of the buffer, interpreted as a header. */ + struct tzhead tzhead; + + /* The entire buffer. */ + char buf[2 * sizeof(struct tzhead) + 2 * sizeof(struct state) + + 4 * TZ_MAX_TIMES]; +}; + +/* Local storage needed for 'tzloadbody'. */ +union local_storage +{ + /* The results of analyzing the file's contents after it is opened. */ + struct file_analysis + { + /* The input buffer. */ + union input_buffer u; + + /* A temporary state used for parsing a TZ string in the file. */ + struct state st; + } u; + + /* We don't need the "fullname" member */ +}; + +/* Load tz data from the file named NAME into *SP. Read extended + * format if DOEXTEND. Use *LSP for temporary storage. Return 0 on + * success, an errno value on failure. + * PG: If "canonname" is not NULL, then on success the canonical spelling of + * given name is stored there (the buffer must be > TZ_STRLEN_MAX bytes!). + */ +static int +tzloadbody(char const *name, char *canonname, struct state *sp, bool doextend, + union local_storage *lsp) +{ + int i; + int fid; + int stored; + ssize_t nread; + union input_buffer *up = &lsp->u.u; + int tzheadsize = sizeof(struct tzhead); + + sp->goback = sp->goahead = false; + + if (!name) + { + name = TZDEFAULT; + if (!name) + return EINVAL; + } + + if (name[0] == ':') + ++name; + + fid = pg_open_tzfile(name, canonname); + if (fid < 0) + return ENOENT; /* pg_open_tzfile may not set errno */ + + nread = read(fid, up->buf, sizeof up->buf); + if (nread < tzheadsize) + { + int err = nread < 0 ? errno : EINVAL; + + close(fid); + return err; + } + if (close(fid) < 0) + return errno; + for (stored = 4; stored <= 8; stored *= 2) + { + int32 ttisstdcnt = detzcode(up->tzhead.tzh_ttisstdcnt); + int32 ttisutcnt = detzcode(up->tzhead.tzh_ttisutcnt); + int64 prevtr = 0; + int32 prevcorr = 0; + int32 leapcnt = detzcode(up->tzhead.tzh_leapcnt); + int32 timecnt = detzcode(up->tzhead.tzh_timecnt); + int32 typecnt = detzcode(up->tzhead.tzh_typecnt); + int32 charcnt = detzcode(up->tzhead.tzh_charcnt); + char const *p = up->buf + tzheadsize; + + /* + * Although tzfile(5) currently requires typecnt to be nonzero, + * support future formats that may allow zero typecnt in files that + * have a TZ string and no transitions. + */ + if (!(0 <= leapcnt && leapcnt < TZ_MAX_LEAPS + && 0 <= typecnt && typecnt < TZ_MAX_TYPES + && 0 <= timecnt && timecnt < TZ_MAX_TIMES + && 0 <= charcnt && charcnt < TZ_MAX_CHARS + && (ttisstdcnt == typecnt || ttisstdcnt == 0) + && (ttisutcnt == typecnt || ttisutcnt == 0))) + return EINVAL; + if (nread + < (tzheadsize /* struct tzhead */ + + timecnt * stored /* ats */ + + timecnt /* types */ + + typecnt * 6 /* ttinfos */ + + charcnt /* chars */ + + leapcnt * (stored + 4) /* lsinfos */ + + ttisstdcnt /* ttisstds */ + + ttisutcnt)) /* ttisuts */ + return EINVAL; + sp->leapcnt = leapcnt; + sp->timecnt = timecnt; + sp->typecnt = typecnt; + sp->charcnt = charcnt; + + /* + * Read transitions, discarding those out of pg_time_t range. But + * pretend the last transition before TIME_T_MIN occurred at + * TIME_T_MIN. + */ + timecnt = 0; + for (i = 0; i < sp->timecnt; ++i) + { + int64 at + = stored == 4 ? detzcode(p) : detzcode64(p); + + sp->types[i] = at <= TIME_T_MAX; + if (sp->types[i]) + { + pg_time_t attime + = ((TYPE_SIGNED(pg_time_t) ? at < TIME_T_MIN : at < 0) + ? TIME_T_MIN : at); + + if (timecnt && attime <= sp->ats[timecnt - 1]) + { + if (attime < sp->ats[timecnt - 1]) + return EINVAL; + sp->types[i - 1] = 0; + timecnt--; + } + sp->ats[timecnt++] = attime; + } + p += stored; + } + + timecnt = 0; + for (i = 0; i < sp->timecnt; ++i) + { + unsigned char typ = *p++; + + if (sp->typecnt <= typ) + return EINVAL; + if (sp->types[i]) + sp->types[timecnt++] = typ; + } + sp->timecnt = timecnt; + for (i = 0; i < sp->typecnt; ++i) + { + struct ttinfo *ttisp; + unsigned char isdst, + desigidx; + + ttisp = &sp->ttis[i]; + ttisp->tt_utoff = detzcode(p); + p += 4; + isdst = *p++; + if (!(isdst < 2)) + return EINVAL; + ttisp->tt_isdst = isdst; + desigidx = *p++; + if (!(desigidx < sp->charcnt)) + return EINVAL; + ttisp->tt_desigidx = desigidx; + } + for (i = 0; i < sp->charcnt; ++i) + sp->chars[i] = *p++; + sp->chars[i] = '\0'; /* ensure '\0' at end */ + + /* Read leap seconds, discarding those out of pg_time_t range. */ + leapcnt = 0; + for (i = 0; i < sp->leapcnt; ++i) + { + int64 tr = stored == 4 ? detzcode(p) : detzcode64(p); + int32 corr = detzcode(p + stored); + + p += stored + 4; + /* Leap seconds cannot occur before the Epoch. */ + if (tr < 0) + return EINVAL; + if (tr <= TIME_T_MAX) + { + /* + * Leap seconds cannot occur more than once per UTC month, and + * UTC months are at least 28 days long (minus 1 second for a + * negative leap second). Each leap second's correction must + * differ from the previous one's by 1 second. + */ + if (tr - prevtr < 28 * SECSPERDAY - 1 + || (corr != prevcorr - 1 && corr != prevcorr + 1)) + return EINVAL; + sp->lsis[leapcnt].ls_trans = prevtr = tr; + sp->lsis[leapcnt].ls_corr = prevcorr = corr; + leapcnt++; + } + } + sp->leapcnt = leapcnt; + + for (i = 0; i < sp->typecnt; ++i) + { + struct ttinfo *ttisp; + + ttisp = &sp->ttis[i]; + if (ttisstdcnt == 0) + ttisp->tt_ttisstd = false; + else + { + if (*p != true && *p != false) + return EINVAL; + ttisp->tt_ttisstd = *p++; + } + } + for (i = 0; i < sp->typecnt; ++i) + { + struct ttinfo *ttisp; + + ttisp = &sp->ttis[i]; + if (ttisutcnt == 0) + ttisp->tt_ttisut = false; + else + { + if (*p != true && *p != false) + return EINVAL; + ttisp->tt_ttisut = *p++; + } + } + + /* + * If this is an old file, we're done. + */ + if (up->tzhead.tzh_version[0] == '\0') + break; + nread -= p - up->buf; + memmove(up->buf, p, nread); + } + if (doextend && nread > 2 && + up->buf[0] == '\n' && up->buf[nread - 1] == '\n' && + sp->typecnt + 2 <= TZ_MAX_TYPES) + { + struct state *ts = &lsp->u.st; + + up->buf[nread - 1] = '\0'; + if (tzparse(&up->buf[1], ts, false)) + { + /* + * Attempt to reuse existing abbreviations. Without this, + * America/Anchorage would be right on the edge after 2037 when + * TZ_MAX_CHARS is 50, as sp->charcnt equals 40 (for LMT AST AWT + * APT AHST AHDT YST AKDT AKST) and ts->charcnt equals 10 (for + * AKST AKDT). Reusing means sp->charcnt can stay 40 in this + * example. + */ + int gotabbr = 0; + int charcnt = sp->charcnt; + + for (i = 0; i < ts->typecnt; i++) + { + char *tsabbr = ts->chars + ts->ttis[i].tt_desigidx; + int j; + + for (j = 0; j < charcnt; j++) + if (strcmp(sp->chars + j, tsabbr) == 0) + { + ts->ttis[i].tt_desigidx = j; + gotabbr++; + break; + } + if (!(j < charcnt)) + { + int tsabbrlen = strlen(tsabbr); + + if (j + tsabbrlen < TZ_MAX_CHARS) + { + strcpy(sp->chars + j, tsabbr); + charcnt = j + tsabbrlen + 1; + ts->ttis[i].tt_desigidx = j; + gotabbr++; + } + } + } + if (gotabbr == ts->typecnt) + { + sp->charcnt = charcnt; + + /* + * Ignore any trailing, no-op transitions generated by zic as + * they don't help here and can run afoul of bugs in zic 2016j + * or earlier. + */ + while (1 < sp->timecnt + && (sp->types[sp->timecnt - 1] + == sp->types[sp->timecnt - 2])) + sp->timecnt--; + + for (i = 0; i < ts->timecnt; i++) + if (sp->timecnt == 0 + || (sp->ats[sp->timecnt - 1] + < ts->ats[i] + leapcorr(sp, ts->ats[i]))) + break; + while (i < ts->timecnt + && sp->timecnt < TZ_MAX_TIMES) + { + sp->ats[sp->timecnt] + = ts->ats[i] + leapcorr(sp, ts->ats[i]); + sp->types[sp->timecnt] = (sp->typecnt + + ts->types[i]); + sp->timecnt++; + i++; + } + for (i = 0; i < ts->typecnt; i++) + sp->ttis[sp->typecnt++] = ts->ttis[i]; + } + } + } + if (sp->typecnt == 0) + return EINVAL; + if (sp->timecnt > 1) + { + for (i = 1; i < sp->timecnt; ++i) + if (typesequiv(sp, sp->types[i], sp->types[0]) && + differ_by_repeat(sp->ats[i], sp->ats[0])) + { + sp->goback = true; + break; + } + for (i = sp->timecnt - 2; i >= 0; --i) + if (typesequiv(sp, sp->types[sp->timecnt - 1], + sp->types[i]) && + differ_by_repeat(sp->ats[sp->timecnt - 1], + sp->ats[i])) + { + sp->goahead = true; + break; + } + } + + /* + * Infer sp->defaulttype from the data. Although this default type is + * always zero for data from recent tzdb releases, things are trickier for + * data from tzdb 2018e or earlier. + * + * The first set of heuristics work around bugs in 32-bit data generated + * by tzdb 2013c or earlier. The workaround is for zones like + * Australia/Macquarie where timestamps before the first transition have a + * time type that is not the earliest standard-time type. See: + * https://mm.icann.org/pipermail/tz/2013-May/019368.html + */ + + /* + * If type 0 is unused in transitions, it's the type to use for early + * times. + */ + for (i = 0; i < sp->timecnt; ++i) + if (sp->types[i] == 0) + break; + i = i < sp->timecnt ? -1 : 0; + + /* + * Absent the above, if there are transition times and the first + * transition is to a daylight time find the standard type less than and + * closest to the type of the first transition. + */ + if (i < 0 && sp->timecnt > 0 && sp->ttis[sp->types[0]].tt_isdst) + { + i = sp->types[0]; + while (--i >= 0) + if (!sp->ttis[i].tt_isdst) + break; + } + + /* + * The next heuristics are for data generated by tzdb 2018e or earlier, + * for zones like EST5EDT where the first transition is to DST. + */ + + /* + * If no result yet, find the first standard type. If there is none, punt + * to type zero. + */ + if (i < 0) + { + i = 0; + while (sp->ttis[i].tt_isdst) + if (++i >= sp->typecnt) + { + i = 0; + break; + } + } + + /* + * A simple 'sp->defaulttype = 0;' would suffice here if we didn't have to + * worry about 2018e-or-earlier data. Even simpler would be to remove the + * defaulttype member and just use 0 in its place. + */ + sp->defaulttype = i; + + return 0; +} + +/* Load tz data from the file named NAME into *SP. Read extended + * format if DOEXTEND. Return 0 on success, an errno value on failure. + * PG: If "canonname" is not NULL, then on success the canonical spelling of + * given name is stored there (the buffer must be > TZ_STRLEN_MAX bytes!). + */ +int +tzload(const char *name, char *canonname, struct state *sp, bool doextend) +{ + union local_storage *lsp = malloc(sizeof *lsp); + + if (!lsp) + return errno; + else + { + int err = tzloadbody(name, canonname, sp, doextend, lsp); + + free(lsp); + return err; + } +} + +static bool +typesequiv(const struct state *sp, int a, int b) +{ + bool result; + + if (sp == NULL || + a < 0 || a >= sp->typecnt || + b < 0 || b >= sp->typecnt) + result = false; + else + { + const struct ttinfo *ap = &sp->ttis[a]; + const struct ttinfo *bp = &sp->ttis[b]; + + result = (ap->tt_utoff == bp->tt_utoff + && ap->tt_isdst == bp->tt_isdst + && ap->tt_ttisstd == bp->tt_ttisstd + && ap->tt_ttisut == bp->tt_ttisut + && (strcmp(&sp->chars[ap->tt_desigidx], + &sp->chars[bp->tt_desigidx]) + == 0)); + } + return result; +} + +static const int mon_lengths[2][MONSPERYEAR] = { + {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}, + {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31} +}; + +static const int year_lengths[2] = { + DAYSPERNYEAR, DAYSPERLYEAR +}; + +/* + * Given a pointer into a timezone string, scan until a character that is not + * a valid character in a time zone abbreviation is found. + * Return a pointer to that character. + */ + +static const char * +getzname(const char *strp) +{ + char c; + + while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' && + c != '+') + ++strp; + return strp; +} + +/* + * Given a pointer into an extended timezone string, scan until the ending + * delimiter of the time zone abbreviation is located. + * Return a pointer to the delimiter. + * + * As with getzname above, the legal character set is actually quite + * restricted, with other characters producing undefined results. + * We don't do any checking here; checking is done later in common-case code. + */ + +static const char * +getqzname(const char *strp, const int delim) +{ + int c; + + while ((c = *strp) != '\0' && c != delim) + ++strp; + return strp; +} + +/* + * Given a pointer into a timezone string, extract a number from that string. + * Check that the number is within a specified range; if it is not, return + * NULL. + * Otherwise, return a pointer to the first character not part of the number. + */ + +static const char * +getnum(const char *strp, int *const nump, const int min, const int max) +{ + char c; + int num; + + if (strp == NULL || !is_digit(c = *strp)) + return NULL; + num = 0; + do + { + num = num * 10 + (c - '0'); + if (num > max) + return NULL; /* illegal value */ + c = *++strp; + } while (is_digit(c)); + if (num < min) + return NULL; /* illegal value */ + *nump = num; + return strp; +} + +/* + * Given a pointer into a timezone string, extract a number of seconds, + * in hh[:mm[:ss]] form, from the string. + * If any error occurs, return NULL. + * Otherwise, return a pointer to the first character not part of the number + * of seconds. + */ + +static const char * +getsecs(const char *strp, int32 *const secsp) +{ + int num; + + /* + * 'HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like + * "M10.4.6/26", which does not conform to Posix, but which specifies the + * equivalent of "02:00 on the first Sunday on or after 23 Oct". + */ + strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1); + if (strp == NULL) + return NULL; + *secsp = num * (int32) SECSPERHOUR; + if (*strp == ':') + { + ++strp; + strp = getnum(strp, &num, 0, MINSPERHOUR - 1); + if (strp == NULL) + return NULL; + *secsp += num * SECSPERMIN; + if (*strp == ':') + { + ++strp; + /* 'SECSPERMIN' allows for leap seconds. */ + strp = getnum(strp, &num, 0, SECSPERMIN); + if (strp == NULL) + return NULL; + *secsp += num; + } + } + return strp; +} + +/* + * Given a pointer into a timezone string, extract an offset, in + * [+-]hh[:mm[:ss]] form, from the string. + * If any error occurs, return NULL. + * Otherwise, return a pointer to the first character not part of the time. + */ + +static const char * +getoffset(const char *strp, int32 *const offsetp) +{ + bool neg = false; + + if (*strp == '-') + { + neg = true; + ++strp; + } + else if (*strp == '+') + ++strp; + strp = getsecs(strp, offsetp); + if (strp == NULL) + return NULL; /* illegal time */ + if (neg) + *offsetp = -*offsetp; + return strp; +} + +/* + * Given a pointer into a timezone string, extract a rule in the form + * date[/time]. See POSIX section 8 for the format of "date" and "time". + * If a valid rule is not found, return NULL. + * Otherwise, return a pointer to the first character not part of the rule. + */ + +static const char * +getrule(const char *strp, struct rule *const rulep) +{ + if (*strp == 'J') + { + /* + * Julian day. + */ + rulep->r_type = JULIAN_DAY; + ++strp; + strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR); + } + else if (*strp == 'M') + { + /* + * Month, week, day. + */ + rulep->r_type = MONTH_NTH_DAY_OF_WEEK; + ++strp; + strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR); + if (strp == NULL) + return NULL; + if (*strp++ != '.') + return NULL; + strp = getnum(strp, &rulep->r_week, 1, 5); + if (strp == NULL) + return NULL; + if (*strp++ != '.') + return NULL; + strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1); + } + else if (is_digit(*strp)) + { + /* + * Day of year. + */ + rulep->r_type = DAY_OF_YEAR; + strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1); + } + else + return NULL; /* invalid format */ + if (strp == NULL) + return NULL; + if (*strp == '/') + { + /* + * Time specified. + */ + ++strp; + strp = getoffset(strp, &rulep->r_time); + } + else + rulep->r_time = 2 * SECSPERHOUR; /* default = 2:00:00 */ + return strp; +} + +/* + * Given a year, a rule, and the offset from UT at the time that rule takes + * effect, calculate the year-relative time that rule takes effect. + */ + +static int32 +transtime(const int year, const struct rule *const rulep, + const int32 offset) +{ + bool leapyear; + int32 value; + int i; + int d, + m1, + yy0, + yy1, + yy2, + dow; + + INITIALIZE(value); + leapyear = isleap(year); + switch (rulep->r_type) + { + + case JULIAN_DAY: + + /* + * Jn - Julian day, 1 == January 1, 60 == March 1 even in leap + * years. In non-leap years, or if the day number is 59 or less, + * just add SECSPERDAY times the day number-1 to the time of + * January 1, midnight, to get the day. + */ + value = (rulep->r_day - 1) * SECSPERDAY; + if (leapyear && rulep->r_day >= 60) + value += SECSPERDAY; + break; + + case DAY_OF_YEAR: + + /* + * n - day of year. Just add SECSPERDAY times the day number to + * the time of January 1, midnight, to get the day. + */ + value = rulep->r_day * SECSPERDAY; + break; + + case MONTH_NTH_DAY_OF_WEEK: + + /* + * Mm.n.d - nth "dth day" of month m. + */ + + /* + * Use Zeller's Congruence to get day-of-week of first day of + * month. + */ + m1 = (rulep->r_mon + 9) % 12 + 1; + yy0 = (rulep->r_mon <= 2) ? (year - 1) : year; + yy1 = yy0 / 100; + yy2 = yy0 % 100; + dow = ((26 * m1 - 2) / 10 + + 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7; + if (dow < 0) + dow += DAYSPERWEEK; + + /* + * "dow" is the day-of-week of the first day of the month. Get the + * day-of-month (zero-origin) of the first "dow" day of the month. + */ + d = rulep->r_day - dow; + if (d < 0) + d += DAYSPERWEEK; + for (i = 1; i < rulep->r_week; ++i) + { + if (d + DAYSPERWEEK >= + mon_lengths[(int) leapyear][rulep->r_mon - 1]) + break; + d += DAYSPERWEEK; + } + + /* + * "d" is the day-of-month (zero-origin) of the day we want. + */ + value = d * SECSPERDAY; + for (i = 0; i < rulep->r_mon - 1; ++i) + value += mon_lengths[(int) leapyear][i] * SECSPERDAY; + break; + } + + /* + * "value" is the year-relative time of 00:00:00 UT on the day in + * question. To get the year-relative time of the specified local time on + * that day, add the transition time and the current offset from UT. + */ + return value + rulep->r_time + offset; +} + +/* + * Given a POSIX section 8-style TZ string, fill in the rule tables as + * appropriate. + * Returns true on success, false on failure. + */ +bool +tzparse(const char *name, struct state *sp, bool lastditch) +{ + const char *stdname; + const char *dstname = NULL; + size_t stdlen; + size_t dstlen; + size_t charcnt; + int32 stdoffset; + int32 dstoffset; + char *cp; + bool load_ok; + + stdname = name; + if (lastditch) + { + /* Unlike IANA, don't assume name is exactly "GMT" */ + stdlen = strlen(name); /* length of standard zone name */ + name += stdlen; + stdoffset = 0; + } + else + { + if (*name == '<') + { + name++; + stdname = name; + name = getqzname(name, '>'); + if (*name != '>') + return false; + stdlen = name - stdname; + name++; + } + else + { + name = getzname(name); + stdlen = name - stdname; + } + if (*name == '\0') /* we allow empty STD abbrev, unlike IANA */ + return false; + name = getoffset(name, &stdoffset); + if (name == NULL) + return false; + } + charcnt = stdlen + 1; + if (sizeof sp->chars < charcnt) + return false; + + /* + * The IANA code always tries to tzload(TZDEFRULES) here. We do not want + * to do that; it would be bad news in the lastditch case, where we can't + * assume pg_open_tzfile() is sane yet. Moreover, if we did load it and + * it contains leap-second-dependent info, that would cause problems too. + * Finally, IANA has deprecated the TZDEFRULES feature, so it presumably + * will die at some point. Desupporting it now seems like good + * future-proofing. + */ + load_ok = false; + sp->goback = sp->goahead = false; /* simulate failed tzload() */ + sp->leapcnt = 0; /* intentionally assume no leap seconds */ + + if (*name != '\0') + { + if (*name == '<') + { + dstname = ++name; + name = getqzname(name, '>'); + if (*name != '>') + return false; + dstlen = name - dstname; + name++; + } + else + { + dstname = name; + name = getzname(name); + dstlen = name - dstname; /* length of DST abbr. */ + } + if (!dstlen) + return false; + charcnt += dstlen + 1; + if (sizeof sp->chars < charcnt) + return false; + if (*name != '\0' && *name != ',' && *name != ';') + { + name = getoffset(name, &dstoffset); + if (name == NULL) + return false; + } + else + dstoffset = stdoffset - SECSPERHOUR; + if (*name == '\0' && !load_ok) + name = TZDEFRULESTRING; + if (*name == ',' || *name == ';') + { + struct rule start; + struct rule end; + int year; + int yearlim; + int timecnt; + pg_time_t janfirst; + int32 janoffset = 0; + int yearbeg; + + ++name; + if ((name = getrule(name, &start)) == NULL) + return false; + if (*name++ != ',') + return false; + if ((name = getrule(name, &end)) == NULL) + return false; + if (*name != '\0') + return false; + sp->typecnt = 2; /* standard time and DST */ + + /* + * Two transitions per year, from EPOCH_YEAR forward. + */ + init_ttinfo(&sp->ttis[0], -stdoffset, false, 0); + init_ttinfo(&sp->ttis[1], -dstoffset, true, stdlen + 1); + sp->defaulttype = 0; + timecnt = 0; + janfirst = 0; + yearbeg = EPOCH_YEAR; + + do + { + int32 yearsecs + = year_lengths[isleap(yearbeg - 1)] * SECSPERDAY; + + yearbeg--; + if (increment_overflow_time(&janfirst, -yearsecs)) + { + janoffset = -yearsecs; + break; + } + } while (EPOCH_YEAR - YEARSPERREPEAT / 2 < yearbeg); + + yearlim = yearbeg + YEARSPERREPEAT + 1; + for (year = yearbeg; year < yearlim; year++) + { + int32 + starttime = transtime(year, &start, stdoffset), + endtime = transtime(year, &end, dstoffset); + int32 + yearsecs = (year_lengths[isleap(year)] + * SECSPERDAY); + bool reversed = endtime < starttime; + + if (reversed) + { + int32 swap = starttime; + + starttime = endtime; + endtime = swap; + } + if (reversed + || (starttime < endtime + && (endtime - starttime + < (yearsecs + + (stdoffset - dstoffset))))) + { + if (TZ_MAX_TIMES - 2 < timecnt) + break; + sp->ats[timecnt] = janfirst; + if (!increment_overflow_time + (&sp->ats[timecnt], + janoffset + starttime)) + sp->types[timecnt++] = !reversed; + sp->ats[timecnt] = janfirst; + if (!increment_overflow_time + (&sp->ats[timecnt], + janoffset + endtime)) + { + sp->types[timecnt++] = reversed; + yearlim = year + YEARSPERREPEAT + 1; + } + } + if (increment_overflow_time + (&janfirst, janoffset + yearsecs)) + break; + janoffset = 0; + } + sp->timecnt = timecnt; + if (!timecnt) + { + sp->ttis[0] = sp->ttis[1]; + sp->typecnt = 1; /* Perpetual DST. */ + } + else if (YEARSPERREPEAT < year - yearbeg) + sp->goback = sp->goahead = true; + } + else + { + int32 theirstdoffset; + int32 theirdstoffset; + int32 theiroffset; + bool isdst; + int i; + int j; + + if (*name != '\0') + return false; + + /* + * Initial values of theirstdoffset and theirdstoffset. + */ + theirstdoffset = 0; + for (i = 0; i < sp->timecnt; ++i) + { + j = sp->types[i]; + if (!sp->ttis[j].tt_isdst) + { + theirstdoffset = + -sp->ttis[j].tt_utoff; + break; + } + } + theirdstoffset = 0; + for (i = 0; i < sp->timecnt; ++i) + { + j = sp->types[i]; + if (sp->ttis[j].tt_isdst) + { + theirdstoffset = + -sp->ttis[j].tt_utoff; + break; + } + } + + /* + * Initially we're assumed to be in standard time. + */ + isdst = false; + theiroffset = theirstdoffset; + + /* + * Now juggle transition times and types tracking offsets as you + * do. + */ + for (i = 0; i < sp->timecnt; ++i) + { + j = sp->types[i]; + sp->types[i] = sp->ttis[j].tt_isdst; + if (sp->ttis[j].tt_ttisut) + { + /* No adjustment to transition time */ + } + else + { + /* + * If daylight saving time is in effect, and the + * transition time was not specified as standard time, add + * the daylight saving time offset to the transition time; + * otherwise, add the standard time offset to the + * transition time. + */ + /* + * Transitions from DST to DDST will effectively disappear + * since POSIX provides for only one DST offset. + */ + if (isdst && !sp->ttis[j].tt_ttisstd) + { + sp->ats[i] += dstoffset - + theirdstoffset; + } + else + { + sp->ats[i] += stdoffset - + theirstdoffset; + } + } + theiroffset = -sp->ttis[j].tt_utoff; + if (sp->ttis[j].tt_isdst) + theirdstoffset = theiroffset; + else + theirstdoffset = theiroffset; + } + + /* + * Finally, fill in ttis. + */ + init_ttinfo(&sp->ttis[0], -stdoffset, false, 0); + init_ttinfo(&sp->ttis[1], -dstoffset, true, stdlen + 1); + sp->typecnt = 2; + sp->defaulttype = 0; + } + } + else + { + dstlen = 0; + sp->typecnt = 1; /* only standard time */ + sp->timecnt = 0; + init_ttinfo(&sp->ttis[0], -stdoffset, false, 0); + sp->defaulttype = 0; + } + sp->charcnt = charcnt; + cp = sp->chars; + memcpy(cp, stdname, stdlen); + cp += stdlen; + *cp++ = '\0'; + if (dstlen != 0) + { + memcpy(cp, dstname, dstlen); + *(cp + dstlen) = '\0'; + } + return true; +} + +static void +gmtload(struct state *const sp) +{ + if (tzload(gmt, NULL, sp, true) != 0) + tzparse(gmt, sp, true); +} + + +/* + * The easy way to behave "as if no library function calls" localtime + * is to not call it, so we drop its guts into "localsub", which can be + * freely called. (And no, the PANS doesn't require the above behavior, + * but it *is* desirable.) + */ +static struct pg_tm * +localsub(struct state const *sp, pg_time_t const *timep, + struct pg_tm *const tmp) +{ + const struct ttinfo *ttisp; + int i; + struct pg_tm *result; + const pg_time_t t = *timep; + + if (sp == NULL) + return gmtsub(timep, 0, tmp); + if ((sp->goback && t < sp->ats[0]) || + (sp->goahead && t > sp->ats[sp->timecnt - 1])) + { + pg_time_t newt = t; + pg_time_t seconds; + pg_time_t years; + + if (t < sp->ats[0]) + seconds = sp->ats[0] - t; + else + seconds = t - sp->ats[sp->timecnt - 1]; + --seconds; + years = (seconds / SECSPERREPEAT + 1) * YEARSPERREPEAT; + seconds = years * AVGSECSPERYEAR; + if (t < sp->ats[0]) + newt += seconds; + else + newt -= seconds; + if (newt < sp->ats[0] || + newt > sp->ats[sp->timecnt - 1]) + return NULL; /* "cannot happen" */ + result = localsub(sp, &newt, tmp); + if (result) + { + int64 newy; + + newy = result->tm_year; + if (t < sp->ats[0]) + newy -= years; + else + newy += years; + if (!(INT_MIN <= newy && newy <= INT_MAX)) + return NULL; + result->tm_year = newy; + } + return result; + } + if (sp->timecnt == 0 || t < sp->ats[0]) + { + i = sp->defaulttype; + } + else + { + int lo = 1; + int hi = sp->timecnt; + + while (lo < hi) + { + int mid = (lo + hi) >> 1; + + if (t < sp->ats[mid]) + hi = mid; + else + lo = mid + 1; + } + i = (int) sp->types[lo - 1]; + } + ttisp = &sp->ttis[i]; + + /* + * To get (wrong) behavior that's compatible with System V Release 2.0 + * you'd replace the statement below with t += ttisp->tt_utoff; + * timesub(&t, 0L, sp, tmp); + */ + result = timesub(&t, ttisp->tt_utoff, sp, tmp); + if (result) + { + result->tm_isdst = ttisp->tt_isdst; + result->tm_zone = unconstify(char *, &sp->chars[ttisp->tt_desigidx]); + } + return result; +} + + +struct pg_tm * +pg_localtime(const pg_time_t *timep, const pg_tz *tz) +{ + return localsub(&tz->state, timep, &tm); +} + + +/* + * gmtsub is to gmtime as localsub is to localtime. + * + * Except we have a private "struct state" for GMT, so no sp is passed in. + */ + +static struct pg_tm * +gmtsub(pg_time_t const *timep, int32 offset, + struct pg_tm *tmp) +{ + struct pg_tm *result; + + /* GMT timezone state data is kept here */ + static struct state *gmtptr = NULL; + + if (gmtptr == NULL) + { + /* Allocate on first use */ + gmtptr = (struct state *) malloc(sizeof(struct state)); + if (gmtptr == NULL) + return NULL; /* errno should be set by malloc */ + gmtload(gmtptr); + } + + result = timesub(timep, offset, gmtptr, tmp); + + /* + * Could get fancy here and deliver something such as "+xx" or "-xx" if + * offset is non-zero, but this is no time for a treasure hunt. + */ + if (offset != 0) + tmp->tm_zone = wildabbr; + else + tmp->tm_zone = gmtptr->chars; + + return result; +} + +struct pg_tm * +pg_gmtime(const pg_time_t *timep) +{ + return gmtsub(timep, 0, &tm); +} + +/* + * Return the number of leap years through the end of the given year + * where, to make the math easy, the answer for year zero is defined as zero. + */ + +static int +leaps_thru_end_of_nonneg(int y) +{ + return y / 4 - y / 100 + y / 400; +} + +static int +leaps_thru_end_of(const int y) +{ + return (y < 0 + ? -1 - leaps_thru_end_of_nonneg(-1 - y) + : leaps_thru_end_of_nonneg(y)); +} + +static struct pg_tm * +timesub(const pg_time_t *timep, int32 offset, + const struct state *sp, struct pg_tm *tmp) +{ + const struct lsinfo *lp; + pg_time_t tdays; + int idays; /* unsigned would be so 2003 */ + int64 rem; + int y; + const int *ip; + int64 corr; + bool hit; + int i; + + corr = 0; + hit = false; + i = (sp == NULL) ? 0 : sp->leapcnt; + while (--i >= 0) + { + lp = &sp->lsis[i]; + if (*timep >= lp->ls_trans) + { + corr = lp->ls_corr; + hit = (*timep == lp->ls_trans + && (i == 0 ? 0 : lp[-1].ls_corr) < corr); + break; + } + } + y = EPOCH_YEAR; + tdays = *timep / SECSPERDAY; + rem = *timep % SECSPERDAY; + while (tdays < 0 || tdays >= year_lengths[isleap(y)]) + { + int newy; + pg_time_t tdelta; + int idelta; + int leapdays; + + tdelta = tdays / DAYSPERLYEAR; + if (!((!TYPE_SIGNED(pg_time_t) || INT_MIN <= tdelta) + && tdelta <= INT_MAX)) + goto out_of_range; + idelta = tdelta; + if (idelta == 0) + idelta = (tdays < 0) ? -1 : 1; + newy = y; + if (increment_overflow(&newy, idelta)) + goto out_of_range; + leapdays = leaps_thru_end_of(newy - 1) - + leaps_thru_end_of(y - 1); + tdays -= ((pg_time_t) newy - y) * DAYSPERNYEAR; + tdays -= leapdays; + y = newy; + } + + /* + * Given the range, we can now fearlessly cast... + */ + idays = tdays; + rem += offset - corr; + while (rem < 0) + { + rem += SECSPERDAY; + --idays; + } + while (rem >= SECSPERDAY) + { + rem -= SECSPERDAY; + ++idays; + } + while (idays < 0) + { + if (increment_overflow(&y, -1)) + goto out_of_range; + idays += year_lengths[isleap(y)]; + } + while (idays >= year_lengths[isleap(y)]) + { + idays -= year_lengths[isleap(y)]; + if (increment_overflow(&y, 1)) + goto out_of_range; + } + tmp->tm_year = y; + if (increment_overflow(&tmp->tm_year, -TM_YEAR_BASE)) + goto out_of_range; + tmp->tm_yday = idays; + + /* + * The "extra" mods below avoid overflow problems. + */ + tmp->tm_wday = EPOCH_WDAY + + ((y - EPOCH_YEAR) % DAYSPERWEEK) * + (DAYSPERNYEAR % DAYSPERWEEK) + + leaps_thru_end_of(y - 1) - + leaps_thru_end_of(EPOCH_YEAR - 1) + + idays; + tmp->tm_wday %= DAYSPERWEEK; + if (tmp->tm_wday < 0) + tmp->tm_wday += DAYSPERWEEK; + tmp->tm_hour = (int) (rem / SECSPERHOUR); + rem %= SECSPERHOUR; + tmp->tm_min = (int) (rem / SECSPERMIN); + + /* + * A positive leap second requires a special representation. This uses + * "... ??:59:60" et seq. + */ + tmp->tm_sec = (int) (rem % SECSPERMIN) + hit; + ip = mon_lengths[isleap(y)]; + for (tmp->tm_mon = 0; idays >= ip[tmp->tm_mon]; ++(tmp->tm_mon)) + idays -= ip[tmp->tm_mon]; + tmp->tm_mday = (int) (idays + 1); + tmp->tm_isdst = 0; + tmp->tm_gmtoff = offset; + return tmp; + +out_of_range: + errno = EOVERFLOW; + return NULL; +} + +/* + * Normalize logic courtesy Paul Eggert. + */ + +static bool +increment_overflow(int *ip, int j) +{ + int const i = *ip; + + /*---------- + * If i >= 0 there can only be overflow if i + j > INT_MAX + * or if j > INT_MAX - i; given i >= 0, INT_MAX - i cannot overflow. + * If i < 0 there can only be overflow if i + j < INT_MIN + * or if j < INT_MIN - i; given i < 0, INT_MIN - i cannot overflow. + *---------- + */ + if ((i >= 0) ? (j > INT_MAX - i) : (j < INT_MIN - i)) + return true; + *ip += j; + return false; +} + +static bool +increment_overflow_time(pg_time_t *tp, int32 j) +{ + /*---------- + * This is like + * 'if (! (TIME_T_MIN <= *tp + j && *tp + j <= TIME_T_MAX)) ...', + * except that it does the right thing even if *tp + j would overflow. + *---------- + */ + if (!(j < 0 + ? (TYPE_SIGNED(pg_time_t) ? TIME_T_MIN - j <= *tp : -1 - j < *tp) + : *tp <= TIME_T_MAX - j)) + return true; + *tp += j; + return false; +} + +static int64 +leapcorr(struct state const *sp, pg_time_t t) +{ + struct lsinfo const *lp; + int i; + + i = sp->leapcnt; + while (--i >= 0) + { + lp = &sp->lsis[i]; + if (t >= lp->ls_trans) + return lp->ls_corr; + } + return 0; +} + +/* + * Find the next DST transition time in the given zone after the given time + * + * *timep and *tz are input arguments, the other parameters are output values. + * + * When the function result is 1, *boundary is set to the pg_time_t + * representation of the next DST transition time after *timep, + * *before_gmtoff and *before_isdst are set to the GMT offset and isdst + * state prevailing just before that boundary (in particular, the state + * prevailing at *timep), and *after_gmtoff and *after_isdst are set to + * the state prevailing just after that boundary. + * + * When the function result is 0, there is no known DST transition + * after *timep, but *before_gmtoff and *before_isdst indicate the GMT + * offset and isdst state prevailing at *timep. (This would occur in + * DST-less time zones, or if a zone has permanently ceased using DST.) + * + * A function result of -1 indicates failure (this case does not actually + * occur in our current implementation). + */ +int +pg_next_dst_boundary(const pg_time_t *timep, + long int *before_gmtoff, + int *before_isdst, + pg_time_t *boundary, + long int *after_gmtoff, + int *after_isdst, + const pg_tz *tz) +{ + const struct state *sp; + const struct ttinfo *ttisp; + int i; + int j; + const pg_time_t t = *timep; + + sp = &tz->state; + if (sp->timecnt == 0) + { + /* non-DST zone, use lowest-numbered standard type */ + i = 0; + while (sp->ttis[i].tt_isdst) + if (++i >= sp->typecnt) + { + i = 0; + break; + } + ttisp = &sp->ttis[i]; + *before_gmtoff = ttisp->tt_utoff; + *before_isdst = ttisp->tt_isdst; + return 0; + } + if ((sp->goback && t < sp->ats[0]) || + (sp->goahead && t > sp->ats[sp->timecnt - 1])) + { + /* For values outside the transition table, extrapolate */ + pg_time_t newt = t; + pg_time_t seconds; + pg_time_t tcycles; + int64 icycles; + int result; + + if (t < sp->ats[0]) + seconds = sp->ats[0] - t; + else + seconds = t - sp->ats[sp->timecnt - 1]; + --seconds; + tcycles = seconds / YEARSPERREPEAT / AVGSECSPERYEAR; + ++tcycles; + icycles = tcycles; + if (tcycles - icycles >= 1 || icycles - tcycles >= 1) + return -1; + seconds = icycles; + seconds *= YEARSPERREPEAT; + seconds *= AVGSECSPERYEAR; + if (t < sp->ats[0]) + newt += seconds; + else + newt -= seconds; + if (newt < sp->ats[0] || + newt > sp->ats[sp->timecnt - 1]) + return -1; /* "cannot happen" */ + + result = pg_next_dst_boundary(&newt, before_gmtoff, + before_isdst, + boundary, + after_gmtoff, + after_isdst, + tz); + if (t < sp->ats[0]) + *boundary -= seconds; + else + *boundary += seconds; + return result; + } + + if (t >= sp->ats[sp->timecnt - 1]) + { + /* No known transition > t, so use last known segment's type */ + i = sp->types[sp->timecnt - 1]; + ttisp = &sp->ttis[i]; + *before_gmtoff = ttisp->tt_utoff; + *before_isdst = ttisp->tt_isdst; + return 0; + } + if (t < sp->ats[0]) + { + /* For "before", use lowest-numbered standard type */ + i = 0; + while (sp->ttis[i].tt_isdst) + if (++i >= sp->typecnt) + { + i = 0; + break; + } + ttisp = &sp->ttis[i]; + *before_gmtoff = ttisp->tt_utoff; + *before_isdst = ttisp->tt_isdst; + *boundary = sp->ats[0]; + /* And for "after", use the first segment's type */ + i = sp->types[0]; + ttisp = &sp->ttis[i]; + *after_gmtoff = ttisp->tt_utoff; + *after_isdst = ttisp->tt_isdst; + return 1; + } + /* Else search to find the boundary following t */ + { + int lo = 1; + int hi = sp->timecnt - 1; + + while (lo < hi) + { + int mid = (lo + hi) >> 1; + + if (t < sp->ats[mid]) + hi = mid; + else + lo = mid + 1; + } + i = lo; + } + j = sp->types[i - 1]; + ttisp = &sp->ttis[j]; + *before_gmtoff = ttisp->tt_utoff; + *before_isdst = ttisp->tt_isdst; + *boundary = sp->ats[i]; + j = sp->types[i]; + ttisp = &sp->ttis[j]; + *after_gmtoff = ttisp->tt_utoff; + *after_isdst = ttisp->tt_isdst; + return 1; +} + +/* + * Identify a timezone abbreviation's meaning in the given zone + * + * Determine the GMT offset and DST flag associated with the abbreviation. + * This is generally used only when the abbreviation has actually changed + * meaning over time; therefore, we also take a UTC cutoff time, and return + * the meaning in use at or most recently before that time, or the meaning + * in first use after that time if the abbrev was never used before that. + * + * On success, returns true and sets *gmtoff and *isdst. If the abbreviation + * was never used at all in this zone, returns false. + * + * Note: abbrev is matched case-sensitively; it should be all-upper-case. + */ +bool +pg_interpret_timezone_abbrev(const char *abbrev, + const pg_time_t *timep, + long int *gmtoff, + int *isdst, + const pg_tz *tz) +{ + const struct state *sp; + const char *abbrs; + const struct ttinfo *ttisp; + int abbrind; + int cutoff; + int i; + const pg_time_t t = *timep; + + sp = &tz->state; + + /* + * Locate the abbreviation in the zone's abbreviation list. We assume + * there are not duplicates in the list. + */ + abbrs = sp->chars; + abbrind = 0; + while (abbrind < sp->charcnt) + { + if (strcmp(abbrev, abbrs + abbrind) == 0) + break; + while (abbrs[abbrind] != '\0') + abbrind++; + abbrind++; + } + if (abbrind >= sp->charcnt) + return false; /* not there! */ + + /* + * Unlike pg_next_dst_boundary, we needn't sweat about extrapolation + * (goback/goahead zones). Finding the newest or oldest meaning of the + * abbreviation should get us what we want, since extrapolation would just + * be repeating the newest or oldest meanings. + * + * Use binary search to locate the first transition > cutoff time. + */ + { + int lo = 0; + int hi = sp->timecnt; + + while (lo < hi) + { + int mid = (lo + hi) >> 1; + + if (t < sp->ats[mid]) + hi = mid; + else + lo = mid + 1; + } + cutoff = lo; + } + + /* + * Scan backwards to find the latest interval using the given abbrev + * before the cutoff time. + */ + for (i = cutoff - 1; i >= 0; i--) + { + ttisp = &sp->ttis[sp->types[i]]; + if (ttisp->tt_desigidx == abbrind) + { + *gmtoff = ttisp->tt_utoff; + *isdst = ttisp->tt_isdst; + return true; + } + } + + /* + * Not there, so scan forwards to find the first one after. + */ + for (i = cutoff; i < sp->timecnt; i++) + { + ttisp = &sp->ttis[sp->types[i]]; + if (ttisp->tt_desigidx == abbrind) + { + *gmtoff = ttisp->tt_utoff; + *isdst = ttisp->tt_isdst; + return true; + } + } + + return false; /* hm, not actually used in any interval? */ +} + +/* + * If the given timezone uses only one GMT offset, store that offset + * into *gmtoff and return true, else return false. + */ +bool +pg_get_timezone_offset(const pg_tz *tz, long int *gmtoff) +{ + /* + * The zone could have more than one ttinfo, if it's historically used + * more than one abbreviation. We return true as long as they all have + * the same gmtoff. + */ + const struct state *sp; + int i; + + sp = &tz->state; + for (i = 1; i < sp->typecnt; i++) + { + if (sp->ttis[i].tt_utoff != sp->ttis[0].tt_utoff) + return false; + } + *gmtoff = sp->ttis[0].tt_utoff; + return true; +} + +/* + * Return the name of the current timezone + */ +const char * +pg_get_timezone_name(pg_tz *tz) +{ + if (tz) + return tz->TZname; + return NULL; +} + +/* + * Check whether timezone is acceptable. + * + * What we are doing here is checking for leap-second-aware timekeeping. + * We need to reject such TZ settings because they'll wreak havoc with our + * date/time arithmetic. + */ +bool +pg_tz_acceptable(pg_tz *tz) +{ + struct pg_tm *tt; + pg_time_t time2000; + + /* + * To detect leap-second timekeeping, run pg_localtime for what should be + * GMT midnight, 2000-01-01. Insist that the tm_sec value be zero; any + * other result has to be due to leap seconds. + */ + time2000 = (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY; + tt = pg_localtime(&time2000, tz); + if (!tt || tt->tm_sec != 0) + return false; + + return true; +} |