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Diffstat (limited to 'time/tzset.c')
| -rw-r--r-- | time/tzset.c | 487 |
1 files changed, 487 insertions, 0 deletions
diff --git a/time/tzset.c b/time/tzset.c new file mode 100644 index 0000000000..e4d5209e88 --- /dev/null +++ b/time/tzset.c @@ -0,0 +1,487 @@ +/* Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc. +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +#include <ansidecl.h> +#include <localeinfo.h> +#include <ctype.h> +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> + +/* Defined in mktime.c. */ +extern CONST unsigned short int __mon_lengths[2][12]; + +#define NOID +#include "tzfile.h" + +extern int __use_tzfile; +extern void EXFUN(__tzfile_read, (CONST char *file)); +extern void EXFUN(__tzfile_default, (char *std AND char *dst AND + long int stdoff AND long int dstoff)); +extern int EXFUN(__tzfile_compute, (time_t, struct tm)); + +#ifndef HAVE_WEAK_SYMBOLS +#define __tzname tzname +#define __daylight daylight +#define __timezone timezone +#else +weak_alias (__tzname, tzname) +weak_alias (__daylight, daylight) +weak_alias (__timezone, timezone) +#endif + +char *__tzname[2] = { (char *) "GMT", (char *) "GMT" }; +int __daylight = 0; +long int __timezone = 0L; + + +#define min(a, b) ((a) < (b) ? (a) : (b)) +#define max(a, b) ((a) > (b) ? (a) : (b)) +#define sign(x) ((x) < 0 ? -1 : 1) + + +/* This structure contains all the information about a + timezone given in the POSIX standard TZ envariable. */ +typedef struct + { + char *name; + + /* When to change. */ + enum { J0, J1, M } type; /* Interpretation of: */ + unsigned short int m, n, d; /* Month, week, day. */ + unsigned int secs; /* Time of day. */ + + long int offset; /* Seconds east of GMT (west if < 0). */ + + /* We cache the computed time of change for a + given year so we don't have to recompute it. */ + time_t change; /* When to change to this zone. */ + int computed_for; /* Year above is computed for. */ + } tz_rule; + +/* tz_rules[0] is standard, tz_rules[1] is daylight. */ +static tz_rule tz_rules[2]; + +int __tzset_run = 0; + +/* Interpret the TZ envariable. */ +void +DEFUN_VOID(__tzset) +{ + register CONST char *tz; + register size_t l; + unsigned short int hh, mm, ss; + unsigned short int whichrule; + + /* Free old storage. */ + if (tz_rules[0].name != NULL && *tz_rules[0].name != '\0') + free((PTR) tz_rules[0].name); + if (tz_rules[1].name != NULL && *tz_rules[1].name != '\0' && + tz_rules[1].name != tz_rules[0].name) + free((PTR) tz_rules[1].name); + + tz = getenv("TZ"); + + if (tz != NULL && *tz == ':') + { + __tzfile_read(tz + 1); + if (__use_tzfile) + { + __tzset_run = 1; + return; + } + else + tz = NULL; + } + + if (tz == NULL || *tz == '\0') + tz = _time_info->tz; + if (tz == NULL || *tz == '\0') + { + __tzfile_read((char *) NULL); + if (!__use_tzfile) + { + size_t len = strlen(_time_info->ut0) + 1; + tz_rules[0].name = (char *) malloc(len); + if (tz_rules[0].name == NULL) + return; + tz_rules[1].name = (char *) malloc(len); + if (tz_rules[1].name == NULL) + return; + memcpy((PTR) tz_rules[0].name, _time_info->ut0, len); + memcpy((PTR) tz_rules[1].name, _time_info->ut0, len); + tz_rules[0].type = tz_rules[1].type = J0; + tz_rules[0].m = tz_rules[0].n = tz_rules[0].d = 0; + tz_rules[1].m = tz_rules[1].n = tz_rules[1].d = 0; + tz_rules[0].secs = tz_rules[1].secs = 0; + tz_rules[0].offset = tz_rules[1].offset = 0L; + tz_rules[0].change = tz_rules[1].change = (time_t) -1; + tz_rules[0].computed_for = tz_rules[1].computed_for = 0; + } + __tzset_run = 1; + return; + } + + /* Clear out old state and reset to unnamed GMT. */ + memset (tz_rules, 0, sizeof tz_rules); + tz_rules[0].name = tz_rules[1].name = (char *) ""; + + /* Get the standard timezone name. */ + tz_rules[0].name = (char *) malloc (strlen (tz) + 1); + if (tz_rules[0].name == NULL) + /* Don't set __tzset_run so we will try again. */ + return; + + if (sscanf(tz, "%[^0-9,+-]", tz_rules[0].name) != 1 || + (l = strlen(tz_rules[0].name)) < 3) + { + free (tz_rules[0].name); + tz_rules[0].name = (char *) ""; + return; + } + + { + char *n = realloc ((PTR) tz_rules[0].name, l + 1); + if (n != NULL) + tz_rules[0].name = n; + } + + tz += l; + + /* Figure out the standard offset from GMT. */ + if (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit(*tz))) + return; + + if (*tz == '-' || *tz == '+') + tz_rules[0].offset = *tz++ == '-' ? 1L : -1L; + else + tz_rules[0].offset = -1L; + switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss)) + { + default: + return; + case 1: + mm = 0; + case 2: + ss = 0; + case 3: + break; + } + tz_rules[0].offset *= (min(ss, 59) + (min(mm, 59) * 60) + + (min(hh, 12) * 60 * 60)); + + for (l = 0; l < 3; ++l) + { + while (isdigit(*tz)) + ++tz; + if (l < 2 && *tz == ':') + ++tz; + } + + /* Get the DST timezone name (if any). */ + if (*tz != '\0') + { + char *n = malloc (strlen(tz) + 1); + if (n != NULL) + { + tz_rules[1].name = n; + if (sscanf(tz, "%[^0-9,+-]", tz_rules[1].name) != 1 || + (l = strlen(tz_rules[1].name)) < 3) + { + free (n); + tz_rules[1].name = (char *) ""; + goto done_names; /* Punt on name, set up the offsets. */ + } + n = realloc ((PTR) tz_rules[1].name, l + 1); + if (n != NULL) + tz_rules[1].name = n; + } + } + + tz += l; + + /* Figure out the DST offset from GMT. */ + if (*tz == '-' || *tz == '+') + tz_rules[1].offset = *tz++ == '-' ? 1L : -1L; + else + tz_rules[1].offset = -1L; + + switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss)) + { + default: + /* Default to one hour later than standard time. */ + tz_rules[1].offset = tz_rules[0].offset + (60 * 60); + break; + + case 1: + mm = 0; + case 2: + ss = 0; + case 3: + tz_rules[1].offset *= (min(ss, 59) + (min(mm, 59) * 60) + + (min(hh, 12) * (60 * 60))); + break; + } + for (l = 0; l < 3; ++l) + { + while (isdigit (*tz)) + ++tz; + if (l < 2 && *tz == ':') + ++tz; + } + + done_names: + + if (*tz == '\0' || (tz[0] == ',' && tz[1] == '\0')) + { + /* There is no rule. See if there is a default rule file. */ + __tzfile_default (tz_rules[0].name, tz_rules[1].name, + tz_rules[0].offset, tz_rules[1].offset); + if (__use_tzfile) + { + __tzset_run = 1; + return; + } + } + + /* Figure out the standard <-> DST rules. */ + for (whichrule = 0; whichrule < 2; ++whichrule) + { + register tz_rule *tzr = &tz_rules[whichrule]; + + if (*tz == ',') + { + ++tz; + if (*tz == '\0') + return; + } + + /* Get the date of the change. */ + if (*tz == 'J' || isdigit (*tz)) + { + char *end; + tzr->type = *tz == 'J' ? J1 : J0; + if (tzr->type == J1 && !isdigit (*++tz)) + return; + tzr->d = (unsigned short int) strtoul (tz, &end, 10); + if (end == tz || tzr->d > 365) + return; + else if (tzr->type == J1 && tzr->d == 0) + return; + tz = end; + } + else if (*tz == 'M') + { + int n; + tzr->type = M; + if (sscanf (tz, "M%hu.%hu.%hu%n", + &tzr->m, &tzr->n, &tzr->d, &n) != 3 || + tzr->m < 1 || tzr->m > 12 || + tzr->n < 1 || tzr->n > 5 || tzr->d > 6) + return; + tz += n; + } + else if (*tz == '\0') + { + /* United States Federal Law, the equivalent of "M4.1.0,M10.5.0". */ + tzr->type = M; + if (tzr == &tz_rules[0]) + { + tzr->m = 4; + tzr->n = 1; + tzr->d = 0; + } + else + { + tzr->m = 10; + tzr->n = 5; + tzr->d = 0; + } + } + else + return; + + if (*tz != '\0' && *tz != '/' && *tz != ',') + return; + else if (*tz == '/') + { + /* Get the time of day of the change. */ + ++tz; + if (*tz == '\0') + return; + switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss)) + { + default: + hh = 2; /* Default to 2:00 AM. */ + case 1: + mm = 0; + case 2: + ss = 0; + case 3: + break; + } + for (l = 0; l < 3; ++l) + { + while (isdigit(*tz)) + ++tz; + if (l < 2 && *tz == ':') + ++tz; + } + tzr->secs = (hh * 60 * 60) + (mm * 60) + ss; + } + else + /* Default to 2:00 AM. */ + tzr->secs = 2 * 60 * 60; + + tzr->computed_for = -1; + } + + __tzset_run = 1; +} + +/* Maximum length of a timezone name. __tz_compute keeps this up to date + (never decreasing it) when ! __use_tzfile. + tzfile.c keeps it up to date when __use_tzfile. */ +long int __tzname_cur_max; + +long int +DEFUN_VOID(__tzname_max) +{ + if (! __tzset_run) + __tzset (); + + return __tzname_cur_max; +} + +/* Figure out the exact time (as a time_t) in YEAR + when the change described by RULE will occur and + put it in RULE->change, saving YEAR in RULE->computed_for. + Return nonzero if successful, zero on failure. */ +static int +DEFUN(compute_change, (rule, year), tz_rule *rule AND int year) +{ + register time_t t; + int y; + + if (year != -1 && rule->computed_for == year) + /* Operations on times in 1969 will be slower. Oh well. */ + return 1; + + /* First set T to January 1st, 0:00:00 GMT in YEAR. */ + t = 0; + for (y = 1970; y < year; ++y) + t += SECSPERDAY * (__isleap (y) ? 366 : 365); + + switch (rule->type) + { + case J1: + /* 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. */ + t += (rule->d - 1) * SECSPERDAY; + if (rule->d >= 60 && __isleap (year)) + t += SECSPERDAY; + break; + + case J0: + /* n - Day of year. + Just add SECSPERDAY times the day number to the time of Jan 1st. */ + t += rule->d * SECSPERDAY; + break; + + case M: + /* Mm.n.d - Nth "Dth day" of month M. */ + { + register int i, d, m1, yy0, yy1, yy2, dow; + + /* First add SECSPERDAY for each day in months before M. */ + for (i = 0; i < rule->m - 1; ++i) + t += __mon_lengths[__isleap (year)][i] * SECSPERDAY; + + /* Use Zeller's Congruence to get day-of-week of first day of month. */ + m1 = (rule->m + 9) % 12 + 1; + yy0 = (rule->m <= 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 += 7; + + /* 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 = rule->d - dow; + if (d < 0) + d += 7; + for (i = 1; i < rule->n; ++i) + { + if (d + 7 >= __mon_lengths[__isleap (year)][rule->m - 1]) + break; + d += 7; + } + + /* D is the day-of-month (zero-origin) of the day we want. */ + t += d * SECSPERDAY; + } + break; + } + + /* T is now the Epoch-relative time of 0:00:00 GMT on the day we want. + Just add the time of day and local offset from GMT, and we're done. */ + + rule->change = t + rule->offset + rule->secs; + rule->computed_for = year; + return 1; +} + + +/* Figure out the correct timezone for *TIMER and TM (which must be the same) + and set `__tzname', `__timezone', and `__daylight' accordingly. + Return nonzero on success, zero on failure. */ +int +DEFUN(__tz_compute, (timer, tm), + time_t timer AND const struct tm *tm) +{ + if (! __tzset_run) + __tzset (); + + if (! compute_change (&tz_rules[0], 1900 + tm->tm_year) || + ! compute_change (&tz_rules[1], 1900 + tm->tm_year)) + return 0; + + __daylight = timer >= tz_rules[0].change && timer < tz_rules[1].change; + __timezone = tz_rules[__daylight ? 1 : 0].offset; + __tzname[0] = (char *) tz_rules[0].name; + __tzname[1] = (char *) tz_rules[1].name; + + { + /* Keep __tzname_cur_max up to date. */ + size_t len0 = strlen (__tzname[0]); + size_t len1 = strlen (__tzname[1]); + if (len0 > __tzname_cur_max) + __tzname_cur_max = len0; + if (len1 > __tzname_cur_max) + __tzname_cur_max = len1; + } + + return 1; +} + +weak_alias (__tzset, tzset) |