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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /time/tzset.c
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initial import
Diffstat (limited to 'time/tzset.c')
-rw-r--r--time/tzset.c487
1 files changed, 487 insertions, 0 deletions
diff --git a/time/tzset.c b/time/tzset.c
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--- /dev/null
+++ b/time/tzset.c
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+/* 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)