-/* Copyright (C) 1991 Free Software Foundation, Inc.
-This file is part of the GNU C Library.
+/* Copyright (C) 1993, 1994 Free Software Foundation, Inc.
+ Contributed by Noel Cragg (noel@cs.oberlin.edu), with fixes by
+ Michael E. Calwas (calwas@ttd.teradyne.com) and
+ Wade Hampton (tasi029@tmn.com).
-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,
+NOTE: The canonical source of this file is maintained with the GNU C Library.
+Bugs can be reported to bug-glibc@prep.ai.mit.edu.
+
+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
-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., 675 Mass Ave,
-Cambridge, MA 02139, USA. */
-
-#include <sys/types.h>
-#include <errno.h>
-#ifndef STDC_HEADERS
-extern int errno;
+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, 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+/* Define this to have a standalone program to test this implementation of
+ mktime. */
+/* #define DEBUG */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
#endif
-#ifdef TM_IN_SYS_TIME
-#include <sys/time.h>
-#else
+
+#include <sys/types.h> /* Some systems define `time_t' here. */
#include <time.h>
-#endif
-#ifdef HAVE_LIMITS_H
-#include <limits.h>
-#else
-#define LONG_MAX (~(1 << (sizeof (long) * 8 - 1)))
-#define LONG_MIN (-LONG_MAX - 1)
-#define INT_MAX (~(1 << (sizeof (int) * 8 - 1)))
-#define INT_MIN (-INT_MAX - 1)
-#endif
-#ifndef NULL
-#define NULL 0
-#endif
#ifndef __isleap
/* Nonzero if YEAR is a leap year (every 4 years,
- except every 100th isn't, and every 1000th is). */
+ except every 100th isn't, and every 400th is). */
#define __isleap(year) \
- ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 1000 == 0))
+ ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
#endif
+#ifndef __P
+#if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
+#define __P(args) args
+#else
+#define __P(args) ()
+#endif /* GCC. */
+#endif /* Not __P. */
+
/* How many days are in each month. */
-static unsigned short int __mon_lengths[2][12] =
+const unsigned short int __mon_lengths[2][12] =
+ {
+ /* Normal years. */
+ { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+ /* Leap years. */
+ { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+ };
+
+
+static int times_through_search; /* This library routine should never
+ hang -- make sure we always return
+ when we're searching for a value */
+
+
+#ifdef DEBUG
+
+#include <stdio.h>
+#include <ctype.h>
+
+int debugging_enabled = 0;
+
+/* Print the values in a `struct tm'. */
+static void
+printtm (it)
+ struct tm *it;
{
- /* Normal years. */
- { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
- /* Leap years. */
- { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
-};
-
-#define invalid() return (time_t) -1
-
-/* Return the `time_t' representation of TP and normalizes TP.
- Return (time_t) -1 if TP is not representable as a `time_t'.
- Note that 31 Dec 1969 23:59:59 is not representable
- because it is represented as (time_t) -1. */
-time_t
-mktime(tp)
-register struct tm *tp;
+ printf ("%02d/%02d/%04d %02d:%02d:%02d (%s) yday:%03d dst:%d gmtoffset:%ld",
+ it->tm_mon + 1,
+ it->tm_mday,
+ it->tm_year + 1900,
+ it->tm_hour,
+ it->tm_min,
+ it->tm_sec,
+ it->tm_zone,
+ it->tm_yday,
+ it->tm_isdst,
+ it->tm_gmtoff);
+}
+#endif
+
+
+static time_t
+dist_tm (t1, t2)
+ struct tm *t1;
+ struct tm *t2;
{
- static struct tm min, max;
- static char init = 0;
+ time_t distance = 0;
+ unsigned long int v1, v2;
+ int diff_flag = 0;
- register time_t result;
- register time_t t;
- register int i;
- register unsigned short *l;
- register struct tm *new;
- time_t end;
+ v1 = v2 = 0;
- if (tp == NULL)
- {
- errno = EINVAL;
- invalid();
+#define doit(x, secs) \
+ v1 += t1->x * secs; \
+ v2 += t2->x * secs; \
+ if (!diff_flag) \
+ { \
+ if (t1->x < t2->x) \
+ diff_flag = -1; \
+ else if (t1->x > t2->x) \
+ diff_flag = 1; \
}
+
+ doit (tm_year, 31536000); /* Okay, not all years have 365 days. */
+ doit (tm_mon, 2592000); /* Okay, not all months have 30 days. */
+ doit (tm_mday, 86400);
+ doit (tm_hour, 3600);
+ doit (tm_min, 60);
+ doit (tm_sec, 1);
+
+#undef doit
+
+ /* We should also make sure that the sign of DISTANCE is correct -- if
+ DIFF_FLAG is positive, the distance should be positive and vice versa. */
+
+ distance = (v1 > v2) ? (v1 - v2) : (v2 - v1);
+ if (diff_flag < 0)
+ distance = -distance;
- if (!init)
+ if (times_through_search > 20) /* Arbitrary # of calls, but makes sure we
+ never hang if there's a problem with
+ this algorithm. */
{
- init = 1;
- end = (time_t) LONG_MIN;
- new = gmtime(&end);
- if (new != NULL)
- min = *new;
- else
- min.tm_sec = min.tm_min = min.tm_hour =
- min.tm_mday = min.tm_mon = min.tm_year = INT_MIN;
-
- end = (time_t) LONG_MAX;
- new = gmtime(&end);
- if (new != NULL)
- max = *new;
- else
- max.tm_sec = max.tm_min = max.tm_hour =
- max.tm_mday = max.tm_mon = max.tm_year = INT_MAX;
+ distance = diff_flag;
}
- /* Make all the elements of TP that we pay attention to
- be within the ranges of reasonable values for those things. */
-#define normalize(elt, min, max, nextelt) \
- while (tp->elt < min) \
- { \
- --tp->nextelt; \
- tp->elt += max + 1; \
- } \
- while (tp->elt > max) \
- { \
- ++tp->nextelt; \
- tp->elt -= max + 1; \
- }
+ /* We need this DIFF_FLAG business because it is forseeable that the
+ distance may be zero when, in actuality, the two structures are
+ different. This is usually the case when the dates are 366 days apart
+ and one of the years is a leap year. */
+ if (distance == 0 && diff_flag)
+ distance = 86400 * diff_flag;
+
+ return distance;
+}
+
+
+/* MKTIME converts the values in a struct tm to a time_t. The values
+ in tm_wday and tm_yday are ignored; other values can be put outside
+ of legal ranges since they will be normalized. This routine takes
+ care of that normalization. */
+
+void
+do_normalization (tmptr)
+ struct tm *tmptr;
+{
+
+#define normalize(foo,x,y,bar); \
+ while (tmptr->foo < x) \
+ { \
+ tmptr->bar--; \
+ tmptr->foo = (y - (x - tmptr->foo) + 1); \
+ } \
+ while (tmptr->foo > y) \
+ { \
+ tmptr->foo = (x + (tmptr->foo - y) - 1); \
+ tmptr->bar++; \
+ }
+
normalize (tm_sec, 0, 59, tm_min);
normalize (tm_min, 0, 59, tm_hour);
- normalize (tm_hour, 0, 24, tm_mday);
-
- /* Normalize the month first so we can use
- it to figure the range for the day. */
+ normalize (tm_hour, 0, 23, tm_mday);
+
+ /* Do the month first, so day range can be found. */
normalize (tm_mon, 0, 11, tm_year);
- normalize (tm_mday, 1, __mon_lengths[__isleap (tp->tm_year)][tp->tm_mon],
+
+ /* Since the day range modifies the month, we should be careful how
+ we reference the array of month lengths -- it is possible that
+ the month will go negative, hence the modulo...
+
+ Also, tm_year is the year - 1900, so we have to 1900 to have it
+ work correctly. */
+
+ normalize (tm_mday, 1,
+ __mon_lengths[__isleap (tmptr->tm_year + 1900)]
+ [((tmptr->tm_mon < 0)
+ ? (12 + (tmptr->tm_mon % 12))
+ : (tmptr->tm_mon % 12)) ],
tm_mon);
- /* Normalize the month again, since normalizing
- the day may have pushed it out of range. */
+ /* Do the month again, because the day may have pushed it out of range. */
normalize (tm_mon, 0, 11, tm_year);
- /* Normalize the day again, because normalizing
- the month may have changed the range. */
- normalize (tm_mday, 1, __mon_lengths[__isleap (tp->tm_year)][tp->tm_mon],
+ /* Do the day again, because the month may have changed the range. */
+ normalize (tm_mday, 1,
+ __mon_lengths[__isleap (tmptr->tm_year + 1900)]
+ [((tmptr->tm_mon < 0)
+ ? (12 + (tmptr->tm_mon % 12))
+ : (tmptr->tm_mon % 12)) ],
tm_mon);
+
+#ifdef DEBUG
+ if (debugging_enabled)
+ {
+ printf (" After normalizing:\n ");
+ printtm (tmptr);
+ putchar ('\n');
+ }
+#endif
+
+}
+
+
+/* Here's where the work gets done. */
+
+#define BAD_STRUCT_TM ((time_t) -1)
+
+time_t
+_mktime_internal (timeptr, producer)
+ struct tm *timeptr;
+ struct tm *(*producer) __P ((const time_t *));
+{
+ struct tm our_tm; /* our working space */
+ struct tm *me = &our_tm; /* a pointer to the above */
+ time_t result; /* the value we return */
+
+ *me = *timeptr; /* copy the struct tm that was passed
+ in by the caller */
+
+
+ /***************************/
+ /* Normalize the structure */
+ /***************************/
+
+ /* This routine assumes that the value of TM_ISDST is -1, 0, or 1.
+ If the user didn't pass it in that way, fix it. */
+
+ if (me->tm_isdst > 0)
+ me->tm_isdst = 1;
+ else if (me->tm_isdst < 0)
+ me->tm_isdst = -1;
- /* Check for out-of-range values. */
-#define lowhigh(field, minmax, cmp) (tp->field cmp minmax.field)
-#define low(field) lowhigh(field, min, <)
-#define high(field) lowhigh(field, max, >)
-#define oor(field) (low(field) || high(field))
-#define lowbound(field) (tp->field == min.field)
-#define highbound(field) (tp->field == max.field)
- if (oor(tm_year))
- invalid();
- else if (lowbound(tm_year))
+ do_normalization (me);
+
+ /* Get out of here if it's not possible to represent this struct.
+ If any of the values in the normalized struct tm are negative,
+ our algorithms won't work. Luckily, we only need to check the
+ year at this point; normalization guarantees that all values will
+ be in correct ranges EXCEPT the year. */
+
+ if (me->tm_year < 0)
+ return BAD_STRUCT_TM;
+
+ /*************************************************/
+ /* Find the appropriate time_t for the structure */
+ /*************************************************/
+
+ /* Modified b-search -- make intelligent guesses as to where the
+ time might lie along the timeline, assuming that our target time
+ lies a linear distance (w/o considering time jumps of a
+ particular region).
+
+ Assume that time does not fluctuate at all along the timeline --
+ e.g., assume that a day will always take 86400 seconds, etc. --
+ and come up with a hypothetical value for the time_t
+ representation of the struct tm TARGET, in relation to the guess
+ variable -- it should be pretty close!
+
+ After testing this, the maximum number of iterations that I had
+ on any number that I tried was 3! Not bad.
+
+ The reason this is not a subroutine is that we will modify some
+ fields in the struct tm (yday and mday). I've never felt good
+ about side-effects when writing structured code... */
+
+ {
+ struct tm *guess_tm;
+ time_t guess = 0;
+ time_t distance = 0;
+ time_t last_distance = 0;
+
+ times_through_search = 0;
+
+ do
+ {
+ guess += distance;
+
+ times_through_search++;
+
+ guess_tm = (*producer) (&guess);
+
+#ifdef DEBUG
+ if (debugging_enabled)
+ {
+ printf (" Guessing time_t == %d\n ", (int) guess);
+ printtm (guess_tm);
+ putchar ('\n');
+ }
+#endif
+
+ /* How far is our guess from the desired struct tm? */
+ distance = dist_tm (me, guess_tm);
+
+ /* Handle periods of time where a period of time is skipped.
+ For example, 2:15 3 April 1994 does not exist, because DST
+ is in effect. The distance function will alternately
+ return values of 3600 and -3600, because it doesn't know
+ that the requested time doesn't exist. In these situations
+ (even if the skip is not exactly an hour) the distances
+ returned will be the same, but alternating in sign. We
+ want the later time, so check to see that the distance is
+ oscillating and we've chosen the correct of the two
+ possibilities.
+
+ Useful: 3 Apr 94 765356300, 30 Oct 94 783496000 */
+
+ if ((distance == -last_distance) && (distance < last_distance))
+ {
+ /* If the caller specified that the DST flag was off, it's
+ not possible to represent this time. */
+ if (me->tm_isdst == 0)
+ {
+#ifdef DEBUG
+ printf (" Distance is oscillating -- dst flag nixes struct!\n");
+#endif
+ return BAD_STRUCT_TM;
+ }
+
+#ifdef DEBUG
+ printf (" Distance is oscillating -- chose the later time.\n");
+#endif
+ distance = 0;
+ }
+
+ if ((distance == 0) && (me->tm_isdst != -1)
+ && (me->tm_isdst != guess_tm->tm_isdst))
+ {
+ /* If we're in this code, we've got the right time but the
+ wrong daylight savings flag. We need to move away from
+ the time that we have and approach the other time from
+ the other direction. That is, if I've requested the
+ non-DST version of a time and I get the DST version
+ instead, I want to put us forward in time and search
+ backwards to get the other time. I checked all of the
+ configuration files for the tz package -- no entry
+ saves more than two hours, so I think we'll be safe by
+ moving 24 hours in one direction. IF THE AMOUNT OF
+ TIME SAVED IN THE CONFIGURATION FILES CHANGES, THIS
+ VALUE MAY NEED TO BE ADJUSTED. Luckily, we can never
+ have more than one level of overlaps, or this would
+ never work. */
+
+#define SKIP_VALUE 86400
+
+ if (guess_tm->tm_isdst == 0)
+ /* we got the later one, but want the earlier one */
+ distance = -SKIP_VALUE;
+ else
+ distance = SKIP_VALUE;
+
+#ifdef DEBUG
+ printf (" Got the right time, wrong DST value -- adjusting\n");
+#endif
+ }
+
+ last_distance = distance;
+
+ } while (distance != 0);
+
+ /* Check to see that the dst flag matches */
+
+ if (me->tm_isdst != -1)
+ {
+ if (me->tm_isdst != guess_tm->tm_isdst)
+ {
+#ifdef DEBUG
+ printf (" DST flag doesn't match! FIXME?\n");
+#endif
+ return BAD_STRUCT_TM;
+ }
+ }
+
+ result = guess; /* Success! */
+
+ /* On successful completion, the values of tm_wday and tm_yday
+ have to be set appropriately. */
+
+ /* me->tm_yday = guess_tm->tm_yday;
+ me->tm_mday = guess_tm->tm_mday; */
+
+ *me = *guess_tm;
+ }
+
+ /* Update the caller's version of the structure */
+
+ *timeptr = *me;
+
+ return result;
+}
+
+time_t
+#ifdef DEBUG /* make it work even if the system's
+ libc has it's own mktime routine */
+my_mktime (timeptr)
+#else
+mktime (timeptr)
+#endif
+ struct tm *timeptr;
+{
+ return _mktime_internal (timeptr, localtime);
+}
+\f
+#ifdef DEBUG
+void
+main (argc, argv)
+ int argc;
+ char *argv[];
+{
+ int time;
+ int result_time;
+ struct tm *tmptr;
+
+ if (argc == 1)
{
- if (low(tm_mon))
- invalid();
- else if (lowbound(tm_mon))
+ long q;
+
+ printf ("starting long test...\n");
+
+ for (q = 10000000; q < 1000000000; q += 599)
{
- if (low(tm_mday))
- invalid();
- else if (lowbound(tm_mday))
- {
- if (low(tm_hour))
- invalid();
- else if (lowbound(tm_hour))
- {
- if (low(tm_min))
- invalid();
- else if (lowbound(tm_min))
- {
- if (low(tm_sec))
- invalid();
- }
- }
- }
+ struct tm *tm = localtime ((time_t *) &q);
+ if ((q % 10000) == 0) { printf ("%ld\n", q); fflush (stdout); }
+ if (q != my_mktime (tm))
+ { printf ("failed for %ld\n", q); fflush (stdout); }
}
+
+ printf ("test finished\n");
+
+ exit (0);
}
- else if (highbound(tm_year))
+
+ if (argc != 2)
{
- if (high(tm_mon))
- invalid();
- else if (highbound(tm_mon))
- {
- if (high(tm_mday))
- invalid();
- else if (highbound(tm_mday))
- {
- if (high(tm_hour))
- invalid();
- else if (highbound(tm_hour))
- {
- if (high(tm_min))
- invalid();
- else if (highbound(tm_min))
- {
- if (high(tm_sec))
- invalid();
- }
- }
- }
- }
+ printf ("wrong # of args\n");
+ exit (0);
}
+
+ debugging_enabled = 1; /* We want to see the info */
+
+ ++argv;
+ time = atoi (*argv);
+
+ tmptr = localtime ((time_t *) &time);
+ printf ("Localtime tells us that a time_t of %d represents\n ", time);
+ printtm (tmptr);
+ putchar ('\n');
+
+ printf (" Given localtime's return val, mktime returns %d which is\n ",
+ (int) my_mktime (tmptr));
+ printtm (tmptr);
+ putchar ('\n');
- t = 0;
- for (i = 1970; i > 1900 + tp->tm_year; --i)
- t -= __isleap(i) ? 366 : 365;
- for (i = 1970; i < 1900 + tp->tm_year; ++i)
- t += __isleap(i) ? 366 : 365;
- l = __mon_lengths[__isleap(1900 + tp->tm_year)];
- for (i = 0; i < tp->tm_mon; ++i)
- t += l[i];
- t += tp->tm_mday - 1;
- result = ((t * 60 * 60 * 24) +
- (tp->tm_hour * 60 * 60) +
- (tp->tm_min * 60) +
- tp->tm_sec);
-
- end = result;
-#if 0 /* This code breaks it, on SunOS anyway. */
- if (tp->tm_isdst < 0)
- new = localtime(&end);
- else
+#if 0
+ tmptr->tm_sec -= 20;
+ tmptr->tm_min -= 20;
+ tmptr->tm_hour -= 20;
+ tmptr->tm_mday -= 20;
+ tmptr->tm_mon -= 20;
+ tmptr->tm_year -= 20;
+ tmptr->tm_gmtoff -= 20000; /* This has no effect! */
+ tmptr->tm_zone = NULL; /* Nor does this! */
+ tmptr->tm_isdst = -1;
#endif
- new = gmtime(&end);
- if (new == NULL)
- invalid();
- new->tm_isdst = tp->tm_isdst;
- *tp = *new;
+
+ tmptr->tm_hour += 1;
+ tmptr->tm_isdst = -1;
- return result;
+ printf ("\n\nchanged ranges: ");
+ printtm (tmptr);
+ putchar ('\n');
+
+ result_time = my_mktime (tmptr);
+ printf ("\nmktime: %d\n", result_time);
+
+ tmptr->tm_isdst = 0;
+
+ printf ("\n\nchanged ranges: ");
+ printtm (tmptr);
+ putchar ('\n');
+
+ result_time = my_mktime (tmptr);
+ printf ("\nmktime: %d\n", result_time);
}
+#endif /* DEBUG */
+
+\f
+/*
+Local Variables:
+compile-command: "gcc -g mktime.c -o mktime -DDEBUG"
+End:
+*/
projects / gnulib.git / blobdiff