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Diffstat (limited to 'lib/mktime.c')
| -rw-r--r-- | lib/mktime.c | 664 |
1 files changed, 0 insertions, 664 deletions
diff --git a/lib/mktime.c b/lib/mktime.c deleted file mode 100644 index b2d9e52e4..000000000 --- a/lib/mktime.c +++ /dev/null @@ -1,664 +0,0 @@ -/* Convert a `struct tm' to a time_t value. - Copyright (C) 1993-1999, 2002-2004, 2005 Free Software Foundation, Inc. - This file is part of the GNU C Library. - Contributed by Paul Eggert (eggert@twinsun.com). - - This program is free software; you can redistribute it and/or modify - it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 2, or (at your option) - any later version. - - This program 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 General Public License for more details. - - You should have received a copy of the GNU General Public License along - with this program; if not, write to the Free Software Foundation, - Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ - -/* Define this to have a standalone program to test this implementation of - mktime. */ -/* #define DEBUG 1 */ - -#ifdef HAVE_CONFIG_H -# include <config.h> -#endif - -/* Assume that leap seconds are possible, unless told otherwise. - If the host has a `zic' command with a `-L leapsecondfilename' option, - then it supports leap seconds; otherwise it probably doesn't. */ -#ifndef LEAP_SECONDS_POSSIBLE -# define LEAP_SECONDS_POSSIBLE 1 -#endif - -#include <sys/types.h> /* Some systems define `time_t' here. */ -#include <time.h> - -#include <limits.h> - -#include <string.h> /* For the real memcpy prototype. */ - -#if DEBUG -# include <stdio.h> -# include <stdlib.h> -/* Make it work even if the system's libc has its own mktime routine. */ -# define mktime my_mktime -#endif /* DEBUG */ - -/* Shift A right by B bits portably, by dividing A by 2**B and - truncating towards minus infinity. A and B should be free of side - effects, and B should be in the range 0 <= B <= INT_BITS - 2, where - INT_BITS is the number of useful bits in an int. GNU code can - assume that INT_BITS is at least 32. - - ISO C99 says that A >> B is implementation-defined if A < 0. Some - implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift - right in the usual way when A < 0, so SHR falls back on division if - ordinary A >> B doesn't seem to be the usual signed shift. */ -#define SHR(a, b) \ - (-1 >> 1 == -1 \ - ? (a) >> (b) \ - : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0)) - -/* The extra casts in the following macros work around compiler bugs, - e.g., in Cray C 5.0.3.0. */ - -/* True if the arithmetic type T is an integer type. bool counts as - an integer. */ -#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1) - -/* True if negative values of the signed integer type T use two's - complement, ones' complement, or signed magnitude representation, - respectively. Much GNU code assumes two's complement, but some - people like to be portable to all possible C hosts. */ -#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1) -#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0) -#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1) - -/* True if the arithmetic type T is signed. */ -#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) - -/* The maximum and minimum values for the integer type T. These - macros have undefined behavior if T is signed and has padding bits. - If this is a problem for you, please let us know how to fix it for - your host. */ -#define TYPE_MINIMUM(t) \ - ((t) (! TYPE_SIGNED (t) \ - ? (t) 0 \ - : TYPE_SIGNED_MAGNITUDE (t) \ - ? ~ (t) 0 \ - : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))) -#define TYPE_MAXIMUM(t) \ - ((t) (! TYPE_SIGNED (t) \ - ? (t) -1 \ - : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))) - -#ifndef TIME_T_MIN -# define TIME_T_MIN TYPE_MINIMUM (time_t) -#endif -#ifndef TIME_T_MAX -# define TIME_T_MAX TYPE_MAXIMUM (time_t) -#endif -#define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1) - -/* Verify a requirement at compile-time (unlike assert, which is runtime). */ -#define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; } - -verify (time_t_is_integer, TYPE_IS_INTEGER (time_t)); -verify (twos_complement_arithmetic, TYPE_TWOS_COMPLEMENT (int)); -/* The code also assumes that signed integer overflow silently wraps - around, but this assumption can't be stated without causing a - diagnostic on some hosts. */ - -#define EPOCH_YEAR 1970 -#define TM_YEAR_BASE 1900 -verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0); - -/* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */ -static inline int -leapyear (long int year) -{ - /* Don't add YEAR to TM_YEAR_BASE, as that might overflow. - Also, work even if YEAR is negative. */ - return - ((year & 3) == 0 - && (year % 100 != 0 - || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3))); -} - -/* How many days come before each month (0-12). */ -#ifndef _LIBC -static -#endif -const unsigned short int __mon_yday[2][13] = - { - /* Normal years. */ - { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, - /* Leap years. */ - { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } - }; - - -#ifndef _LIBC -/* Portable standalone applications should supply a "time_r.h" that - declares a POSIX-compliant localtime_r, for the benefit of older - implementations that lack localtime_r or have a nonstandard one. - See the gnulib time_r module for one way to implement this. */ -# include "time_r.h" -# undef __localtime_r -# define __localtime_r localtime_r -# define __mktime_internal mktime_internal -#endif - -/* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) - - (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks - were not adjusted between the time stamps. - - The YEAR values uses the same numbering as TP->tm_year. Values - need not be in the usual range. However, YEAR1 must not be less - than 2 * INT_MIN or greater than 2 * INT_MAX. - - The result may overflow. It is the caller's responsibility to - detect overflow. */ - -static inline time_t -ydhms_diff (long int year1, long int yday1, int hour1, int min1, int sec1, - int year0, int yday0, int hour0, int min0, int sec0) -{ - verify (C99_integer_division, -1 / 2 == 0); - verify (long_int_year_and_yday_are_wide_enough, - INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX); - - /* Compute intervening leap days correctly even if year is negative. - Take care to avoid integer overflow here. */ - int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3); - int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3); - int a100 = a4 / 25 - (a4 % 25 < 0); - int b100 = b4 / 25 - (b4 % 25 < 0); - int a400 = SHR (a100, 2); - int b400 = SHR (b100, 2); - int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400); - - /* Compute the desired time in time_t precision. Overflow might - occur here. */ - time_t tyear1 = year1; - time_t years = tyear1 - year0; - time_t days = 365 * years + yday1 - yday0 + intervening_leap_days; - time_t hours = 24 * days + hour1 - hour0; - time_t minutes = 60 * hours + min1 - min0; - time_t seconds = 60 * minutes + sec1 - sec0; - return seconds; -} - - -/* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC), - assuming that *T corresponds to *TP and that no clock adjustments - occurred between *TP and the desired time. - If TP is null, return a value not equal to *T; this avoids false matches. - If overflow occurs, yield the minimal or maximal value, except do not - yield a value equal to *T. */ -static time_t -guess_time_tm (long int year, long int yday, int hour, int min, int sec, - const time_t *t, const struct tm *tp) -{ - if (tp) - { - time_t d = ydhms_diff (year, yday, hour, min, sec, - tp->tm_year, tp->tm_yday, - tp->tm_hour, tp->tm_min, tp->tm_sec); - time_t t1 = *t + d; - if ((t1 < *t) == (TYPE_SIGNED (time_t) ? d < 0 : TIME_T_MAX / 2 < d)) - return t1; - } - - /* Overflow occurred one way or another. Return the nearest result - that is actually in range, except don't report a zero difference - if the actual difference is nonzero, as that would cause a false - match. */ - return (*t < TIME_T_MIDPOINT - ? TIME_T_MIN + (*t == TIME_T_MIN) - : TIME_T_MAX - (*t == TIME_T_MAX)); -} - -/* Use CONVERT to convert *T to a broken down time in *TP. - If *T is out of range for conversion, adjust it so that - it is the nearest in-range value and then convert that. */ -static struct tm * -ranged_convert (struct tm *(*convert) (const time_t *, struct tm *), - time_t *t, struct tm *tp) -{ - struct tm *r = convert (t, tp); - - if (!r && *t) - { - time_t bad = *t; - time_t ok = 0; - - /* BAD is a known unconvertible time_t, and OK is a known good one. - Use binary search to narrow the range between BAD and OK until - they differ by 1. */ - while (bad != ok + (bad < 0 ? -1 : 1)) - { - time_t mid = *t = (bad < 0 - ? bad + ((ok - bad) >> 1) - : ok + ((bad - ok) >> 1)); - r = convert (t, tp); - if (r) - ok = mid; - else - bad = mid; - } - - if (!r && ok) - { - /* The last conversion attempt failed; - revert to the most recent successful attempt. */ - *t = ok; - r = convert (t, tp); - } - } - - return r; -} - - -/* Convert *TP to a time_t value, inverting - the monotonic and mostly-unit-linear conversion function CONVERT. - Use *OFFSET to keep track of a guess at the offset of the result, - compared to what the result would be for UTC without leap seconds. - If *OFFSET's guess is correct, only one CONVERT call is needed. - This function is external because it is used also by timegm.c. */ -time_t -__mktime_internal (struct tm *tp, - struct tm *(*convert) (const time_t *, struct tm *), - time_t *offset) -{ - time_t t, gt, t0, t1, t2; - struct tm tm; - - /* The maximum number of probes (calls to CONVERT) should be enough - to handle any combinations of time zone rule changes, solar time, - leap seconds, and oscillations around a spring-forward gap. - POSIX.1 prohibits leap seconds, but some hosts have them anyway. */ - int remaining_probes = 6; - - /* Time requested. Copy it in case CONVERT modifies *TP; this can - occur if TP is localtime's returned value and CONVERT is localtime. */ - int sec = tp->tm_sec; - int min = tp->tm_min; - int hour = tp->tm_hour; - int mday = tp->tm_mday; - int mon = tp->tm_mon; - int year_requested = tp->tm_year; - int isdst = tp->tm_isdst; - - /* 1 if the previous probe was DST. */ - int dst2; - - /* Ensure that mon is in range, and set year accordingly. */ - int mon_remainder = mon % 12; - int negative_mon_remainder = mon_remainder < 0; - int mon_years = mon / 12 - negative_mon_remainder; - long int lyear_requested = year_requested; - long int year = lyear_requested + mon_years; - - /* The other values need not be in range: - the remaining code handles minor overflows correctly, - assuming int and time_t arithmetic wraps around. - Major overflows are caught at the end. */ - - /* Calculate day of year from year, month, and day of month. - The result need not be in range. */ - int mon_yday = ((__mon_yday[leapyear (year)] - [mon_remainder + 12 * negative_mon_remainder]) - - 1); - long int lmday = mday; - long int yday = mon_yday + lmday; - - time_t guessed_offset = *offset; - - int sec_requested = sec; - - if (LEAP_SECONDS_POSSIBLE) - { - /* Handle out-of-range seconds specially, - since ydhms_tm_diff assumes every minute has 60 seconds. */ - if (sec < 0) - sec = 0; - if (59 < sec) - sec = 59; - } - - /* Invert CONVERT by probing. First assume the same offset as last - time. */ - - t0 = ydhms_diff (year, yday, hour, min, sec, - EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset); - - if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3) - { - /* time_t isn't large enough to rule out overflows, so check - for major overflows. A gross check suffices, since if t0 - has overflowed, it is off by a multiple of TIME_T_MAX - - TIME_T_MIN + 1. So ignore any component of the difference - that is bounded by a small value. */ - - /* Approximate log base 2 of the number of time units per - biennium. A biennium is 2 years; use this unit instead of - years to avoid integer overflow. For example, 2 average - Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds, - which is 63113904 seconds, and rint (log2 (63113904)) is - 26. */ - int ALOG2_SECONDS_PER_BIENNIUM = 26; - int ALOG2_MINUTES_PER_BIENNIUM = 20; - int ALOG2_HOURS_PER_BIENNIUM = 14; - int ALOG2_DAYS_PER_BIENNIUM = 10; - int LOG2_YEARS_PER_BIENNIUM = 1; - - int approx_requested_biennia = - (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM) - - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM) - + SHR (mday, ALOG2_DAYS_PER_BIENNIUM) - + SHR (hour, ALOG2_HOURS_PER_BIENNIUM) - + SHR (min, ALOG2_MINUTES_PER_BIENNIUM) - + (LEAP_SECONDS_POSSIBLE - ? 0 - : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM))); - - int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM); - int diff = approx_biennia - approx_requested_biennia; - int abs_diff = diff < 0 ? - diff : diff; - - /* IRIX 4.0.5 cc miscaculates TIME_T_MIN / 3: it erroneously - gives a positive value of 715827882. Setting a variable - first then doing math on it seems to work. - (ghazi@caip.rutgers.edu) */ - time_t time_t_max = TIME_T_MAX; - time_t time_t_min = TIME_T_MIN; - time_t overflow_threshold = - (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM; - - if (overflow_threshold < abs_diff) - { - /* Overflow occurred. Try repairing it; this might work if - the time zone offset is enough to undo the overflow. */ - time_t repaired_t0 = -1 - t0; - approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM); - diff = approx_biennia - approx_requested_biennia; - abs_diff = diff < 0 ? - diff : diff; - if (overflow_threshold < abs_diff) - return -1; - guessed_offset += repaired_t0 - t0; - t0 = repaired_t0; - } - } - - /* Repeatedly use the error to improve the guess. */ - - for (t = t1 = t2 = t0, dst2 = 0; - (gt = guess_time_tm (year, yday, hour, min, sec, &t, - ranged_convert (convert, &t, &tm)), - t != gt); - t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0) - if (t == t1 && t != t2 - && (tm.tm_isdst < 0 - || (isdst < 0 - ? dst2 <= (tm.tm_isdst != 0) - : (isdst != 0) != (tm.tm_isdst != 0)))) - /* We can't possibly find a match, as we are oscillating - between two values. The requested time probably falls - within a spring-forward gap of size GT - T. Follow the common - practice in this case, which is to return a time that is GT - T - away from the requested time, preferring a time whose - tm_isdst differs from the requested value. (If no tm_isdst - was requested and only one of the two values has a nonzero - tm_isdst, prefer that value.) In practice, this is more - useful than returning -1. */ - goto offset_found; - else if (--remaining_probes == 0) - return -1; - - /* We have a match. Check whether tm.tm_isdst has the requested - value, if any. */ - if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst) - { - /* tm.tm_isdst has the wrong value. Look for a neighboring - time with the right value, and use its UTC offset. - - Heuristic: probe the adjacent timestamps in both directions, - looking for the desired isdst. This should work for all real - time zone histories in the tz database. */ - - /* Distance between probes when looking for a DST boundary. In - tzdata2003a, the shortest period of DST is 601200 seconds - (e.g., America/Recife starting 2000-10-08 01:00), and the - shortest period of non-DST surrounded by DST is 694800 - seconds (Africa/Tunis starting 1943-04-17 01:00). Use the - minimum of these two values, so we don't miss these short - periods when probing. */ - int stride = 601200; - - /* The longest period of DST in tzdata2003a is 536454000 seconds - (e.g., America/Jujuy starting 1946-10-01 01:00). The longest - period of non-DST is much longer, but it makes no real sense - to search for more than a year of non-DST, so use the DST - max. */ - int duration_max = 536454000; - - /* Search in both directions, so the maximum distance is half - the duration; add the stride to avoid off-by-1 problems. */ - int delta_bound = duration_max / 2 + stride; - - int delta, direction; - - for (delta = stride; delta < delta_bound; delta += stride) - for (direction = -1; direction <= 1; direction += 2) - { - time_t ot = t + delta * direction; - if ((ot < t) == (direction < 0)) - { - struct tm otm; - ranged_convert (convert, &ot, &otm); - if (otm.tm_isdst == isdst) - { - /* We found the desired tm_isdst. - Extrapolate back to the desired time. */ - t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm); - ranged_convert (convert, &t, &tm); - goto offset_found; - } - } - } - } - - offset_found: - *offset = guessed_offset + t - t0; - - if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec) - { - /* Adjust time to reflect the tm_sec requested, not the normalized value. - Also, repair any damage from a false match due to a leap second. */ - int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec; - t1 = t + sec_requested; - t2 = t1 + sec_adjustment; - if (((t1 < t) != (sec_requested < 0)) - | ((t2 < t1) != (sec_adjustment < 0)) - | ! convert (&t2, &tm)) - return -1; - t = t2; - } - - *tp = tm; - return t; -} - - -/* FIXME: This should use a signed type wide enough to hold any UTC - offset in seconds. 'int' should be good enough for GNU code. We - can't fix this unilaterally though, as other modules invoke - __mktime_internal. */ -static time_t localtime_offset; - -/* Convert *TP to a time_t value. */ -time_t -mktime (struct tm *tp) -{ -#ifdef _LIBC - /* POSIX.1 8.1.1 requires that whenever mktime() is called, the - time zone names contained in the external variable `tzname' shall - be set as if the tzset() function had been called. */ - __tzset (); -#endif - - return __mktime_internal (tp, __localtime_r, &localtime_offset); -} - -#ifdef weak_alias -weak_alias (mktime, timelocal) -#endif - -#ifdef _LIBC -libc_hidden_def (mktime) -libc_hidden_weak (timelocal) -#endif - -#if DEBUG - -static int -not_equal_tm (const struct tm *a, const struct tm *b) -{ - return ((a->tm_sec ^ b->tm_sec) - | (a->tm_min ^ b->tm_min) - | (a->tm_hour ^ b->tm_hour) - | (a->tm_mday ^ b->tm_mday) - | (a->tm_mon ^ b->tm_mon) - | (a->tm_year ^ b->tm_year) - | (a->tm_yday ^ b->tm_yday) - | (a->tm_isdst ^ b->tm_isdst)); -} - -static void -print_tm (const struct tm *tp) -{ - if (tp) - printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d", - tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday, - tp->tm_hour, tp->tm_min, tp->tm_sec, - tp->tm_yday, tp->tm_wday, tp->tm_isdst); - else - printf ("0"); -} - -static int -check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt) -{ - if (tk != tl || !lt || not_equal_tm (&tmk, lt)) - { - printf ("mktime ("); - print_tm (lt); - printf (")\nyields ("); - print_tm (&tmk); - printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl); - return 1; - } - - return 0; -} - -int -main (int argc, char **argv) -{ - int status = 0; - struct tm tm, tmk, tml; - struct tm *lt; - time_t tk, tl, tl1; - char trailer; - - if ((argc == 3 || argc == 4) - && (sscanf (argv[1], "%d-%d-%d%c", - &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer) - == 3) - && (sscanf (argv[2], "%d:%d:%d%c", - &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer) - == 3)) - { - tm.tm_year -= TM_YEAR_BASE; - tm.tm_mon--; - tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]); - tmk = tm; - tl = mktime (&tmk); - lt = localtime (&tl); - if (lt) - { - tml = *lt; - lt = &tml; - } - printf ("mktime returns %ld == ", (long int) tl); - print_tm (&tmk); - printf ("\n"); - status = check_result (tl, tmk, tl, lt); - } - else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0)) - { - time_t from = atol (argv[1]); - time_t by = atol (argv[2]); - time_t to = atol (argv[3]); - - if (argc == 4) - for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1) - { - lt = localtime (&tl); - if (lt) - { - tmk = tml = *lt; - tk = mktime (&tmk); - status |= check_result (tk, tmk, tl, &tml); - } - else - { - printf ("localtime (%ld) yields 0\n", (long int) tl); - status = 1; - } - tl1 = tl + by; - if ((tl1 < tl) != (by < 0)) - break; - } - else - for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1) - { - /* Null benchmark. */ - lt = localtime (&tl); - if (lt) - { - tmk = tml = *lt; - tk = tl; - status |= check_result (tk, tmk, tl, &tml); - } - else - { - printf ("localtime (%ld) yields 0\n", (long int) tl); - status = 1; - } - tl1 = tl + by; - if ((tl1 < tl) != (by < 0)) - break; - } - } - else - printf ("Usage:\ -\t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\ -\t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\ -\t%s FROM BY TO - # Do not test those values (for benchmark).\n", - argv[0], argv[0], argv[0]); - - return status; -} - -#endif /* DEBUG */ - -/* -Local Variables: -compile-command: "gcc -DDEBUG -Wall -W -O -g mktime.c -o mktime" -End: -*/ |