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-rw-r--r--libc/misc/time/mktime.c475
1 files changed, 258 insertions, 217 deletions
diff --git a/libc/misc/time/mktime.c b/libc/misc/time/mktime.c
index 7286e666b..065126e0e 100644
--- a/libc/misc/time/mktime.c
+++ b/libc/misc/time/mktime.c
@@ -1,92 +1,90 @@
-
-/* This is adapted from glibc */
-/* Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc. */
-
-
-/* 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. */
+/* Convert a `struct tm' to a time_t value.
+ Copyright (C) 1993, 94, 95, 96, 97, 98, 99 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Paul Eggert (eggert@twinsun.com).
+
+ 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+/* Define this to have a standalone program to test this implementation of
+ mktime. */
+
+#include <features.h>
+/* Assume that leap seconds are not possible */
+#undef LEAP_SECONDS_POSSIBLE
+#include <sys/types.h> /* Some systems define `time_t' here. */
#include <time.h>
-
-#if __STDC__ || __GNU_LIBRARY__ || STDC_HEADERS
#include <limits.h>
-#endif
-
-#if DEBUG
-#include <stdio.h>
-#if __STDC__ || __GNU_LIBRARY__ || STDC_HEADERS
-#include <stdlib.h>
-#endif
-/* Make it work even if the system's libc has its own mktime routine. */
-#define mktime my_mktime
-#endif /* DEBUG */
-
-#ifndef __P
-#if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
-#define __P(args) args
-#else
-#define __P(args) ()
-#endif /* GCC. */
-#endif /* Not __P. */
+#if 0
#ifndef CHAR_BIT
-#define CHAR_BIT 8
+# define CHAR_BIT 8
#endif
+/* The extra casts work around common compiler bugs. */
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+/* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
+ It is necessary at least when t == time_t. */
+#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
+ ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
+#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
+
#ifndef INT_MIN
-#define INT_MIN (~0 << (sizeof (int) * CHAR_BIT - 1))
+# define INT_MIN TYPE_MINIMUM (int)
#endif
#ifndef INT_MAX
-#define INT_MAX (~0 - INT_MIN)
+# define INT_MAX TYPE_MAXIMUM (int)
#endif
#ifndef TIME_T_MIN
-#define TIME_T_MIN (0 < (time_t) -1 ? (time_t) 0 \
- : ~ (time_t) 0 << (sizeof (time_t) * CHAR_BIT - 1))
+# define TIME_T_MIN TYPE_MINIMUM (time_t)
#endif
#ifndef TIME_T_MAX
-#define TIME_T_MAX (~ (time_t) 0 - TIME_T_MIN)
+# define TIME_T_MAX TYPE_MAXIMUM (time_t)
#endif
#define TM_YEAR_BASE 1900
#define EPOCH_YEAR 1970
-#ifndef __isleap
-/* Nonzero if YEAR is a leap year (every 4 years,
- except every 100th isn't, and every 400th is). */
-#define __isleap(year) \
- ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
-#endif
+/* How many days come before each month (0-12). */
extern const unsigned short int __mon_yday[2][13];
-static time_t ydhms_tm_diff
-__P((int, int, int, int, int, const struct tm *));
-time_t __mktime_internal
-__P((struct tm *, struct tm * (*)(const time_t *, struct tm *), time_t *));
/* Yield the difference between (YEAR-YDAY HOUR:MIN:SEC) and (*TP),
measured in seconds, ignoring leap seconds.
YEAR uses the same numbering as TM->tm_year.
All values are in range, except possibly YEAR.
+ If TP is null, return a nonzero value.
If overflow occurs, yield the low order bits of the correct answer. */
-static time_t ydhms_tm_diff(year, yday, hour, min, sec, tp)
-int year, yday, hour, min, sec;
-const struct tm *tp;
+static time_t
+__ydhms_tm_diff (int year, int yday, int hour, int min, int sec,
+ const struct tm *tp)
{
+ if (!tp)
+ return 1;
+ else
+ {
/* Compute intervening leap days correctly even if year is negative.
Take care to avoid int overflow. time_t overflow is OK, since
only the low order bits of the correct time_t answer are needed.
Don't convert to time_t until after all divisions are done, since
time_t might be unsigned. */
- int a4 = (year >> 2) + (TM_YEAR_BASE >> 2) - !(year & 3);
- int b4 = (tp->tm_year >> 2) + (TM_YEAR_BASE >> 2) - !(tp->tm_year & 3);
+ int a4 = (year >> 2) + (TM_YEAR_BASE >> 2) - ! (year & 3);
+ int b4 = (tp->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (tp->tm_year & 3);
int a100 = a4 / 25 - (a4 % 25 < 0);
int b100 = b4 / 25 - (b4 % 25 < 0);
int a400 = a100 >> 2;
@@ -94,193 +92,236 @@ const struct tm *tp;
int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
time_t years = year - (time_t) tp->tm_year;
time_t days = (365 * years + intervening_leap_days
-
- + (yday - tp->tm_yday));
+ + (yday - tp->tm_yday));
return (60 * (60 * (24 * days + (hour - tp->tm_hour))
- + (min - tp->tm_min))
- + (sec - tp->tm_sec));
+ + (min - tp->tm_min))
+ + (sec - tp->tm_sec));
+ }
}
-
-/* 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];
-
-/* Warning -- this function is a stub andd always does UTC
- * no matter what it is given */
-void tzset (void)
+/* 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)
{
- 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;
-}
-
+ struct tm *r;
+ if (! (r = (*convert) (t, tp)) && *t)
+ {
+ time_t bad = *t;
+ time_t ok = 0;
+ struct tm tm;
-static time_t localtime_offset;
+ /* 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));
+ if ((r = (*convert) (t, tp)))
+ {
+ tm = *r;
+ ok = mid;
+ }
+ else
+ bad = mid;
+ }
-/* Convert *TP to a time_t value. */
-time_t mktime(tp)
-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
+ if (!r && ok)
+ {
+ /* The last conversion attempt failed;
+ revert to the most recent successful attempt. */
+ *t = ok;
+ *tp = tm;
+ r = tp;
+ }
+ }
- return __mktime_internal(tp, localtime_r, &localtime_offset);
+ 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. */
-time_t __mktime_internal(tp, convert, offset)
-struct tm *tp;
-struct tm *(*convert) __P((const time_t *, struct tm *));
-time_t *offset;
+time_t __mktime_internal (struct tm *tp,
+ struct tm *(*convert) (const time_t *, struct tm *), time_t *offset)
{
- time_t t, dt, t0;
- 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,
- and leap seconds. Posix.1 prohibits leap seconds, but some hosts
- have them anyway. */
- int remaining_probes = 4;
-
- /* 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;
-
- /* 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;
- int year = year_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 yday = ((__mon_yday[__isleap(year + TM_YEAR_BASE)]
- [mon_remainder + 12 * negative_mon_remainder])
- + mday - 1);
-
+ time_t t, dt, 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;
+
+ /* 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;
+ int year = year_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 yday = ((__mon_yday[__isleap (year + TM_YEAR_BASE)]
+ [mon_remainder + 12 * negative_mon_remainder])
+ + mday - 1);
+
+ int sec_requested = sec;
#if LEAP_SECONDS_POSSIBLE
- /* Handle out-of-range seconds specially,
- since ydhms_tm_diff assumes every minute has 60 seconds. */
- int sec_requested = sec;
-
- if (sec < 0)
- sec = 0;
- if (59 < sec)
- sec = 59;
+ /* 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;
#endif
- /* Invert CONVERT by probing. First assume the same offset as last time.
- Then repeatedly use the error to improve the guess. */
-
- tm.tm_year = EPOCH_YEAR - TM_YEAR_BASE;
- tm.tm_yday = tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
- t0 = ydhms_tm_diff(year, yday, hour, min, sec, &tm);
-
- for (t = t0 + *offset;
- (dt =
- ydhms_tm_diff(year, yday, hour, min, sec, (*convert) (&t, &tm)));
- t += dt)
- if (--remaining_probes == 0)
- return -1;
-
- /* Check whether tm.tm_isdst has the requested value, if any. */
- if (0 <= isdst && 0 <= tm.tm_isdst) {
- int dst_diff = (isdst != 0) - (tm.tm_isdst != 0);
-
- if (dst_diff) {
- /* Move two hours in the direction indicated by the disagreement,
- probe some more, and switch to a new time if found.
- The largest known fallback due to daylight savings is two hours:
- once, in Newfoundland, 1988-10-30 02:00 -> 00:00. */
- time_t ot = t - 2 * 60 * 60 * dst_diff;
-
- while (--remaining_probes != 0) {
- struct tm otm;
-
- if (!(dt = ydhms_tm_diff(year, yday, hour, min, sec,
- (*convert) (&ot, &otm)))) {
- t = ot;
- tm = otm;
- break;
- }
- if ((ot += dt) == t)
- break; /* Avoid a redundant probe. */
- }
- }
+ /* Invert CONVERT by probing. First assume the same offset as last time.
+ Then repeatedly use the error to improve the guess. */
+
+ tm.tm_year = EPOCH_YEAR - TM_YEAR_BASE;
+ tm.tm_yday = tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+ t0 = __ydhms_tm_diff (year, yday, hour, min, sec, &tm);
+
+ for (t = t1 = t2 = t0 + *offset;
+ (dt = __ydhms_tm_diff (year, yday, hour, min, sec,
+ __ranged_convert (convert, &t, &tm)));
+ t1 = t2, t2 = t, t += dt)
+ if (t == t1 && t != t2
+ && (isdst < 0 || 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 DT. Follow the common
+ practice in this case, which is to return a time that is DT
+ away from the requested time, preferring a time whose
+ tm_isdst differs from the requested value. In practice,
+ this is more useful than returning -1. */
+ break;
+ else if (--remaining_probes == 0)
+ return -1;
+
+ /* If we have a match, check whether tm.tm_isdst has the requested
+ value, if any. */
+ if (dt == 0 && 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 previous three calendar quarters (approximately),
+looking for the desired isdst. This isn't perfect,
+but it's good enough in practice. */
+ int quarter = 7889238; /* seconds per average 1/4 Gregorian year */
+ int i;
+
+ /* If we're too close to the time_t limit, look in future quarters. */
+ if (t < TIME_T_MIN + 3 * quarter)
+ quarter = -quarter;
+
+ for (i = 1; i <= 3; i++)
+ {
+ time_t ot = t - i * quarter;
+ 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 = ot + __ydhms_tm_diff (year, yday, hour, min, sec, &otm);
+ __ranged_convert (convert, &t, &tm);
+ break;
+ }
}
+ }
- *offset = t - t0;
+ *offset = t - t0;
#if LEAP_SECONDS_POSSIBLE
- if (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. */
- t += sec_requested - sec + (sec == 0 && tm.tm_sec == 60);
- (*convert) (&t, &tm);
- }
+ if (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. */
+ t += sec_requested - sec + (sec == 0 && tm.tm_sec == 60);
+ if (! (*convert) (&t, &tm))
+ return -1;
+ }
#endif
-#if 0
- if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3) {
- /* time_t isn't large enough to rule out overflows in ydhms_tm_diff,
- so check for major overflows. A gross check suffices,
- since if t 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. */
-
- double dyear = (double) year_requested + mon_years - tm.tm_year;
- double dday = 366 * dyear + mday;
- double dsec = 60 * (60 * (24 * dday + hour) + min) + sec_requested;
-
- if (TIME_T_MAX / 3 - TIME_T_MIN / 3 < (dsec < 0 ? -dsec : dsec))
- return -1;
- }
-#endif
+ if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
+ {
+ /* time_t isn't large enough to rule out overflows in __ydhms_tm_diff,
+ so check for major overflows. A gross check suffices,
+ since if t 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. */
+
+ double dyear = (double) year_requested + mon_years - tm.tm_year;
+ double dday = 366 * dyear + mday;
+ double dsec = 60 * (60 * (24 * dday + hour) + min) + sec_requested;
+
+ /* On Irix4.0.5 cc, dividing TIME_T_MIN by 3 does not produce
+ correct results, ie., it erroneously gives a positive value
+ of 715827882. Setting a variable first then doing math on it
+ seems to work. (ghazi@caip.rutgers.edu) */
+
+ const time_t time_t_max = TIME_T_MAX;
+ const time_t time_t_min = TIME_T_MIN;
+
+ if (time_t_max / 3 - time_t_min / 3 < (dsec < 0 ? - dsec : dsec))
+ return -1;
+ }
- *tp = tm;
- return t;
+ *tp = tm;
+ return t;
}
+
+
+
+/* Convert *TP to a time_t value. */
+time_t mktime (struct tm *tp)
+{
+ static time_t localtime_offset;
+ /* 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 ();
+
+ return __mktime_internal (tp, localtime_r, &localtime_offset);
+}
+#else
+
+/* Convert *TP to a time_t value. */
+time_t mktime (struct tm *tp)
+{
+ time_t m_secs=tp->tm_min*60;
+ time_t h_secs=tp->tm_hour*3600;
+ time_t d_secs=tp->tm_yday*86400;
+ time_t y_secs=(tp->tm_year-70)*31536000;
+ time_t l_secs1=((tp->tm_year-69)/4)*86400;
+ time_t l_secs2=((tp->tm_year-1)/100)*86400;
+ time_t l_secs3=((tp->tm_year+299)/400)*86400;
+ return m_secs+h_secs+d_secs+y_secs+l_secs1-l_secs2+l_secs3+tp->tm_gmtoff;
+}
+#endif