/* Copyright (C) 1991-2015 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 Lesser General Public License as published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ #include #include #include #include #include #include #include #include #include #define NOID #include 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_initialized (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. */ 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 void compute_change (tz_rule *rule, int year) __THROW internal_function; static void tzset_internal (int always, int explicit) __THROW internal_function; /* List of buffers containing time zone strings. */ struct tzstring_l { struct tzstring_l *next; size_t len; /* strlen(data) - doesn't count terminating NUL! */ char data[0]; }; static struct tzstring_l *tzstring_list; /* Allocate a permanent home for the first LEN characters of S. It will never be moved or deallocated, but may share space with other strings. Don't modify the returned string. */ static char * __tzstring_len (const char *s, size_t len) { char *p; struct tzstring_l *t, *u, *new; /* Walk the list and look for a match. If this string is the same as the end of an already-allocated string, it can share space. */ for (u = t = tzstring_list; t; u = t, t = t->next) if (len <= t->len) { p = &t->data[t->len - len]; if (memcmp (s, p, len) == 0) return p; } /* Not found; allocate a new buffer. */ new = malloc (sizeof (struct tzstring_l) + len + 1); if (!new) return NULL; new->next = NULL; new->len = len; memcpy (new->data, s, len); new->data[len] = '\0'; if (u) u->next = new; else tzstring_list = new; return new->data; } /* Allocate a permanent home for S. It will never be moved or deallocated, but may share space with other strings. Don't modify the returned string. */ char * __tzstring (const char *s) { return __tzstring_len (s, strlen (s)); } /* Maximum length of a timezone name. tzset_internal 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 (void) { __libc_lock_lock (tzset_lock); tzset_internal (0, 0); __libc_lock_unlock (tzset_lock); return __tzname_cur_max; } static char *old_tz; static void internal_function update_vars (void) { __daylight = tz_rules[0].offset != tz_rules[1].offset; __timezone = -tz_rules[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; } static unsigned int __attribute_noinline__ compute_offset (unsigned int ss, unsigned int mm, unsigned int hh) { return min (ss, 59) + min (mm, 59) * 60 + min (hh, 24) * 60 * 60; } /* Parses the time zone name at *TZP, and writes a pointer to an interned string to tz_rules[WHICHRULE].name. On success, advances *TZP, and returns true. Returns false otherwise. */ static bool parse_tzname (const char **tzp, int whichrule) { const char *start = *tzp; const char *p = start; while (('a' <= *p && *p <= 'z') || ('A' <= *p && *p <= 'Z')) ++p; size_t len = p - start; if (len < 3) { p = *tzp; if (__glibc_unlikely (*p++ != '<')) return false; start = p; while (('a' <= *p && *p <= 'z') || ('A' <= *p && *p <= 'Z') || ('0' <= *p && *p <= '9') || *p == '+' || *p == '-') ++p; len = p - start; if (*p++ != '>' || len < 3) return false; } tz_rules[whichrule].name = __tzstring_len (start, len); *tzp = p; return true; } /* Parses the time zone offset at *TZP, and writes it to tz_rules[WHICHRULE].offset. Returns true if the parse was successful. */ static bool parse_offset (const char **tzp, int whichrule) { const char *tz = *tzp; if (whichrule == 0 && (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit (*tz)))) return false; long sign; if (*tz == '-' || *tz == '+') sign = *tz++ == '-' ? 1L : -1L; else sign = -1L; *tzp = tz; unsigned short int hh; unsigned short mm = 0; unsigned short ss = 0; int consumed = 0; if (sscanf (tz, "%hu%n:%hu%n:%hu%n", &hh, &consumed, &mm, &consumed, &ss, &consumed) > 0) tz_rules[whichrule].offset = sign * compute_offset (ss, mm, hh); else /* Nothing could be parsed. */ if (whichrule == 0) { /* Standard time defaults to offset zero. */ tz_rules[0].offset = 0; return false; } else /* DST defaults to one hour later than standard time. */ tz_rules[1].offset = tz_rules[0].offset + (60 * 60); *tzp = tz + consumed; return true; } /* Parses the standard <-> DST rules at *TZP. Updates tz_rule[WHICHRULE]. On success, advances *TZP and returns true. Otherwise, returns false. */ static bool parse_rule (const char **tzp, int whichrule) { const char *tz = *tzp; 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 false; unsigned long int d = strtoul (tz, &end, 10); if (end == tz || d > 365) return false; if (tzr->type == J1 && d == 0) return false; tzr->d = d; tz = end; } else if (*tz == 'M') { tzr->type = M; int consumed; if (sscanf (tz, "M%hu.%hu.%hu%n", &tzr->m, &tzr->n, &tzr->d, &consumed) != 3 || tzr->m < 1 || tzr->m > 12 || tzr->n < 1 || tzr->n > 5 || tzr->d > 6) return false; tz += consumed; } else if (*tz == '\0') { /* Daylight time rules in the U.S. are defined in the U.S. Code, Title 15, Chapter 6, Subchapter IX - Standard Time. These dates were established by Congress in the Energy Policy Act of 2005 [Pub. L. no. 109-58, 119 Stat 594 (2005)]. Below is the equivalent of "M3.2.0,M11.1.0" [/2 not needed since 2:00AM is the default]. */ tzr->type = M; if (tzr == &tz_rules[0]) { tzr->m = 3; tzr->n = 2; tzr->d = 0; } else { tzr->m = 11; tzr->n = 1; tzr->d = 0; } } else return false; if (*tz != '\0' && *tz != '/' && *tz != ',') return false; else if (*tz == '/') { /* Get the time of day of the change. */ int negative; ++tz; if (*tz == '\0') return false; negative = *tz == '-'; tz += negative; /* Default to 2:00 AM. */ unsigned short hh = 2; unsigned short mm = 0; unsigned short ss = 0; int consumed = 0; sscanf (tz, "%hu%n:%hu%n:%hu%n", &hh, &consumed, &mm, &consumed, &ss, &consumed);; tz += consumed; tzr->secs = (negative ? -1 : 1) * ((hh * 60 * 60) + (mm * 60) + ss); } else /* Default to 2:00 AM. */ tzr->secs = 2 * 60 * 60; tzr->computed_for = -1; *tzp = tz; return true; } /* Parse the POSIX TZ-style string. */ void __tzset_parse_tz (const char *tz) { /* 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. */ if (parse_tzname (&tz, 0) && parse_offset (&tz, 0)) { /* Get the DST timezone name (if any). */ if (*tz != '\0') { if (parse_tzname (&tz, 1)) { parse_offset (&tz, 1); 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; return; } } } /* Figure out the standard <-> DST rules. */ if (parse_rule (&tz, 0)) parse_rule (&tz, 1); } else { /* There is no DST. */ tz_rules[1].name = tz_rules[0].name; tz_rules[1].offset = tz_rules[0].offset; } } update_vars (); } /* Interpret the TZ envariable. */ static void internal_function tzset_internal (always, explicit) int always; int explicit; { static int is_initialized; const char *tz; if (is_initialized && !always) return; is_initialized = 1; /* Examine the TZ environment variable. */ tz = getenv ("TZ"); if (tz == NULL && !explicit) /* Use the site-wide default. This is a file name which means we would not see changes to the file if we compare only the file name for change. We want to notice file changes if tzset() has been called explicitly. Leave TZ as NULL in this case. */ tz = TZDEFAULT; if (tz && *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 changed since the last run. */ if (old_tz != NULL && tz != NULL && strcmp (tz, old_tz) == 0) /* No change, simply return. */ return; if (tz == NULL) /* No user specification; use the site-wide default. */ tz = TZDEFAULT; tz_rules[0].name = NULL; tz_rules[1].name = NULL; /* Save the value of `tz'. */ free (old_tz); old_tz = tz ? __strdup (tz) : NULL; /* Try to read a data file. */ __tzfile_read (tz, 0, NULL); if (__use_tzfile) return; /* No data file found. Default to UTC if nothing specified. */ if (tz == NULL || *tz == '\0' || (TZDEFAULT != NULL && strcmp (tz, TZDEFAULT) == 0)) { memset (tz_rules, '\0', sizeof tz_rules); tz_rules[0].name = tz_rules[1].name = "UTC"; if (J0 != 0) tz_rules[0].type = tz_rules[1].type = J0; tz_rules[0].change = tz_rules[1].change = (time_t) -1; update_vars (); return; } __tzset_parse_tz (tz); } /* 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. */ static void internal_function compute_change (rule, year) tz_rule *rule; int year; { time_t t; if (year != -1 && rule->computed_for == year) /* Operations on times in 2 BC will be slower. Oh well. */ return; /* First set T to January 1st, 0:00:00 GMT in YEAR. */ if (year > 1970) t = ((year - 1970) * 365 + /* Compute the number of leapdays between 1970 and YEAR (exclusive). There is a leapday every 4th year ... */ + ((year - 1) / 4 - 1970 / 4) /* ... except every 100th year ... */ - ((year - 1) / 100 - 1970 / 100) /* ... but still every 400th year. */ + ((year - 1) / 400 - 1970 / 400)) * SECSPERDAY; else t = 0; 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; } /* Figure out the correct timezone for TM and set `__tzname', `__timezone', and `__daylight' accordingly. */ void internal_function __tz_compute (timer, tm, use_localtime) time_t timer; struct tm *tm; int use_localtime; { compute_change (&tz_rules[0], 1900 + tm->tm_year); compute_change (&tz_rules[1], 1900 + tm->tm_year); if (use_localtime) { int isdst; /* We have to distinguish between northern and southern hemisphere. For the latter the daylight saving time ends in the next year. */ if (__builtin_expect (tz_rules[0].change > tz_rules[1].change, 0)) isdst = (timer < tz_rules[1].change || timer >= tz_rules[0].change); else isdst = (timer >= tz_rules[0].change && timer < tz_rules[1].change); tm->tm_isdst = isdst; tm->tm_zone = __tzname[isdst]; tm->tm_gmtoff = tz_rules[isdst].offset; } } /* Reinterpret the TZ environment variable and set `tzname'. */ #undef tzset void __tzset (void) { __libc_lock_lock (tzset_lock); tzset_internal (1, 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. */ tzset_internal (tp == &_tmbuf && use_localtime, 1); if (__use_tzfile) __tzfile_compute (*timer, use_localtime, &leap_correction, &leap_extra_secs, tp); else { if (! __offtime (timer, 0, tp)) tp = NULL; else __tz_compute (*timer, tp, use_localtime); leap_correction = 0L; leap_extra_secs = 0; } __libc_lock_unlock (tzset_lock); if (tp) { if (! use_localtime) { tp->tm_isdst = 0; tp->tm_zone = "GMT"; tp->tm_gmtoff = 0L; } if (__offtime (timer, tp->tm_gmtoff - leap_correction, tp)) tp->tm_sec += leap_extra_secs; else tp = NULL; } return tp; } libc_freeres_fn (free_mem) { while (tzstring_list != NULL) { struct tzstring_l *old = tzstring_list; tzstring_list = tzstring_list->next; free (old); } free (old_tz); old_tz = NULL; }