/* Copyright (C) 1991, 92, 93, 94, 95, 96, 97 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include #include #include #include #include #include #include #include /* Defined in mktime.c. */ extern const unsigned short int __mon_yday[2][13]; /* Defined in localtime.c. */ extern struct tm _tmbuf; #define NOID #include "tzfile.h" extern int __use_tzfile; extern void __tzfile_read __P ((const char *file)); extern int __tzfile_compute __P ((time_t timer, int use_localtime, long int *leap_correct, int *leap_hit)); extern void __tzfile_default __P ((const char *std, const char *dst, long int stdoff, long int dstoff)); extern char * __tzstring __P ((const char *string)); char *__tzname[2] = { (char *) "GMT", (char *) "GMT" }; int __daylight = 0; long int __timezone = 0L; weak_alias (__tzname, tzname) weak_alias (__daylight, daylight) weak_alias (__timezone, timezone) /* This locks all the state variables in tzfile.c and this file. */ __libc_lock_define (static, tzset_lock) #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 { const 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]; static int compute_change __P ((tz_rule *rule, int year)) internal_function; static int tz_compute __P ((time_t timer, const struct tm *tm)) internal_function; static void tzset_internal __P ((int always)) internal_function; /* Header for a list of buffers containing time zone strings. */ struct tzstring_head { struct tzstring_head *next; /* The buffer itself immediately follows the header. The buffer contains zero or more (possibly overlapping) strings. The last string is followed by 2 '\0's instead of the usual 1. */ }; /* First in a list of buffers containing time zone strings. All the buffers but the last are read-only. */ static struct { struct tzstring_head head; char data[48]; } tzstring_list; /* Size of the last buffer in the list, not counting its header. */ static size_t tzstring_last_buffer_size = sizeof tzstring_list.data; /* Allocate a time zone string with given contents. The string will never be moved or deallocated. However, its contents may be shared with other such strings. */ char * __tzstring (string) const char *string; { struct tzstring_head *h = &tzstring_list.head; size_t needed; char *p; /* Look through time zone string list for a duplicate of this one. */ for (h = &tzstring_list.head; ; h = h->next) { for (p = (char *) (h + 1); p[0] | p[1]; ++p) if (strcmp (p, string) == 0) return p; if (! h->next) break; } /* No duplicate was found. Copy to the end of this buffer if there's room; otherwise, append a large-enough new buffer to the list and use it. */ ++p; needed = strlen (string) + 2; /* Need 2 trailing '\0's after last string. */ if ((size_t) ((char *) (h + 1) + tzstring_last_buffer_size - p) < needed) { size_t buffer_size = tzstring_last_buffer_size; while ((buffer_size *= 2) < needed) continue; if (! (h = h->next = malloc (sizeof *h + buffer_size))) return NULL; h->next = NULL; tzstring_last_buffer_size = buffer_size; p = (char *) (h + 1); } return strncpy (p, string, needed); } static char *old_tz = NULL; /* Interpret the TZ envariable. */ static void internal_function tzset_internal (always) int always; { static int is_initialized = 0; register const char *tz; register size_t l; char *tzbuf; unsigned short int hh, mm, ss; unsigned short int whichrule; if (is_initialized && !always) return; is_initialized = 1; /* Examine the TZ environment variable. */ tz = getenv ("TZ"); if (tz == NULL) /* No user specification; use the site-wide default. */ tz = TZDEFAULT; else if (*tz == '\0') /* User specified the empty string; use UTC explicitly. */ tz = "Universal"; /* A leading colon means "implementation defined syntax". We ignore the colon and always use the same algorithm: try a data file, and if none exists parse the 1003.1 syntax. */ if (tz && *tz == ':') ++tz; /* Check whether the value changes since the last run. */ if (old_tz != NULL && tz != NULL && strcmp (tz, old_tz) == 0) /* No change, simply return. */ return; tz_rules[0].name = NULL; tz_rules[1].name = NULL; /* Save the value of `tz'. */ if (old_tz != NULL) free (old_tz); old_tz = tz ? __strdup (tz) : NULL; /* Try to read a data file. */ __tzfile_read (tz); if (__use_tzfile) return; /* No data file found. Default to UTC if nothing specified. */ if (tz == NULL || *tz == '\0') { tz_rules[0].name = tz_rules[1].name = "UTC"; 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; return; } /* Clear out old state and reset to unnamed UTC. */ memset (tz_rules, 0, sizeof tz_rules); tz_rules[0].name = tz_rules[1].name = ""; /* Get the standard timezone name. */ tzbuf = malloc (strlen (tz) + 1); if (! tzbuf) { /* Clear the old tz name so we will try again. */ free (old_tz); old_tz = NULL; return; } if (sscanf (tz, "%[^0-9,+-]", tzbuf) != 1 || (l = strlen (tzbuf)) < 3) { free (tzbuf); return; } tz_rules[0].name = __tzstring (tzbuf); tz += l; /* Figure out the standard offset from UTC. */ if (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit (*tz))) { free (tzbuf); 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: free (tzbuf); 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, 23) * 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 = tzbuf + strlen (tzbuf) + 1; if (sscanf (tz, "%[^0-9,+-]", n) != 1 || (l = strlen (n)) < 3) goto done_names; /* Punt on name, set up the offsets. */ tz_rules[1].name = __tzstring (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, 23) * (60 * 60))); break; } for (l = 0; l < 3; ++l) { while (isdigit (*tz)) ++tz; if (l < 2 && *tz == ':') ++tz; } 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) { free (old_tz); old_tz = NULL; free (tzbuf); return; } } } else { /* There is no DST. */ tz_rules[1].name = tz_rules[0].name; free (tzbuf); return; } done_names: free (tzbuf); /* Figure out the standard <-> DST rules. */ for (whichrule = 0; whichrule < 2; ++whichrule) { register tz_rule *tzr = &tz_rules[whichrule]; /* Ignore comma to support string following the incorrect specification in early POSIX.1 printings. */ tz += *tz == ','; /* 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; } } /* 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. */ size_t __tzname_cur_max; long int __tzname_max () { __libc_lock_lock (tzset_lock); tzset_internal (0); __libc_lock_unlock (tzset_lock); 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 internal_function compute_change (rule, year) tz_rule *rule; 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. */ { unsigned int i; int d, m1, yy0, yy1, yy2, dow; const unsigned short int *myday = &__mon_yday[__isleap (year)][rule->m]; /* First add SECSPERDAY for each day in months before M. */ t += myday[-1] * 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 >= (int) myday[0] - myday[-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. */ static int internal_function tz_compute (timer, tm) time_t timer; const struct tm *tm; { 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; } /* Reinterpret the TZ environment variable and set `tzname'. */ #undef tzset void __tzset (void) { __libc_lock_lock (tzset_lock); tzset_internal (1); if (!__use_tzfile) { /* Set `tzname'. */ __tzname[0] = (char *) tz_rules[0].name; __tzname[1] = (char *) tz_rules[1].name; } __libc_lock_unlock (tzset_lock); } weak_alias (__tzset, tzset) /* Return the `struct tm' representation of *TIMER in the local timezone. Use local time if USE_LOCALTIME is nonzero, UTC otherwise. */ struct tm * __tz_convert (const time_t *timer, int use_localtime, struct tm *tp) { long int leap_correction; int leap_extra_secs; if (timer == NULL) { __set_errno (EINVAL); return NULL; } __libc_lock_lock (tzset_lock); /* Update internal database according to current TZ setting. POSIX.1 8.3.7.2 says that localtime_r is not required to set tzname. This is a good idea since this allows at least a bit more parallelism. By analogy we apply the same rule to gmtime_r. */ tzset_internal (tp == &_tmbuf); if (__use_tzfile) { if (! __tzfile_compute (*timer, use_localtime, &leap_correction, &leap_extra_secs)) tp = NULL; } else { __offtime (timer, 0, tp); if (! tz_compute (*timer, tp)) tp = NULL; leap_correction = 0L; leap_extra_secs = 0; } if (tp) { if (use_localtime) { tp->tm_isdst = __daylight; tp->tm_zone = __tzname[__daylight]; tp->tm_gmtoff = __timezone; } else { tp->tm_isdst = 0; tp->tm_zone = "GMT"; tp->tm_gmtoff = 0L; } __offtime (timer, tp->tm_gmtoff - leap_correction, tp); tp->tm_sec += leap_extra_secs; } __libc_lock_unlock (tzset_lock); return tp; }