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Diffstat (limited to 'REORG.TODO/time/tzset.c')
| -rw-r--r-- | REORG.TODO/time/tzset.c | 632 |
1 files changed, 632 insertions, 0 deletions
diff --git a/REORG.TODO/time/tzset.c b/REORG.TODO/time/tzset.c new file mode 100644 index 0000000000..8868e9aada --- /dev/null +++ b/REORG.TODO/time/tzset.c @@ -0,0 +1,632 @@ +/* Copyright (C) 1991-2017 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 + <http://www.gnu.org/licenses/>. */ + +#include <ctype.h> +#include <errno.h> +#include <libc-lock.h> +#include <stdbool.h> +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> + +#include <timezone/tzfile.h> + +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) + +/* 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); + +/* 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)); +} + +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; +} + + +static unsigned int +compute_offset (unsigned int ss, unsigned int mm, unsigned int hh) +{ + if (ss > 59) + ss = 59; + if (mm > 59) + mm = 59; + if (hh > 24) + hh = 24; + return ss + mm * 60 + hh * 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; + } + + const char *name = __tzstring_len (start, len); + if (name == NULL) + return false; + tz_rules[whichrule].name = name; + + *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 +tzset_internal (int always) +{ + 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 && *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 (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 (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); + + 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); + + 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; +} |