1 /* Copyright (C) 1993, 94, 95, 96, 97, 98 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Paul Eggert (eggert@twinsun.com).
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
20 /* Define this to have a standalone program to test this implementation of
29 # define HAVE_LIMITS_H 1
30 # define STDC_HEADERS 1
33 /* Assume that leap seconds are possible, unless told otherwise.
34 If the host has a `zic' command with a `-L leapsecondfilename' option,
35 then it supports leap seconds; otherwise it probably doesn't. */
36 #ifndef LEAP_SECONDS_POSSIBLE
37 # define LEAP_SECONDS_POSSIBLE 1
40 #include <sys/types.h> /* Some systems define `time_t' here. */
52 /* Make it work even if the system's libc has its own mktime routine. */
53 # define mktime my_mktime
57 # if defined __GNUC__ || (defined __STDC__ && __STDC__)
58 # define __P(args) args
68 /* The extra casts work around common compiler bugs. */
69 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
70 /* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
71 It is necessary at least when t == time_t. */
72 #define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
73 ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
74 #define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
77 # define INT_MIN TYPE_MINIMUM (int)
80 # define INT_MAX TYPE_MAXIMUM (int)
84 # define TIME_T_MIN TYPE_MINIMUM (time_t)
87 # define TIME_T_MAX TYPE_MAXIMUM (time_t)
90 #define TM_YEAR_BASE 1900
91 #define EPOCH_YEAR 1970
94 /* Nonzero if YEAR is a leap year (every 4 years,
95 except every 100th isn't, and every 400th is). */
96 # define __isleap(year) \
97 ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
100 /* How many days come before each month (0-12). */
101 const unsigned short int __mon_yday
[2][13] =
104 { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
106 { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
109 static struct tm
*ranged_convert
__P ((struct tm
*(*) __P ((const time_t *,
111 time_t *, struct tm
*));
112 static time_t ydhms_tm_diff
__P ((int, int, int, int, int, const struct tm
*));
113 time_t __mktime_internal
__P ((struct tm
*,
114 struct tm
*(*) (const time_t *, struct tm
*),
119 # define my_mktime_localtime_r __localtime_r
121 /* If we're a mktime substitute in a GNU program, then prefer
122 localtime to localtime_r, since many localtime_r implementations
124 static struct tm
*my_mktime_localtime_r
__P ((const time_t *, struct tm
*));
126 my_mktime_localtime_r (t
, tp
)
130 struct tm
*l
= localtime (t
);
139 /* Yield the difference between (YEAR-YDAY HOUR:MIN:SEC) and (*TP),
140 measured in seconds, ignoring leap seconds.
141 YEAR uses the same numbering as TM->tm_year.
142 All values are in range, except possibly YEAR.
143 If TP is null, return a nonzero value.
144 If overflow occurs, yield the low order bits of the correct answer. */
146 ydhms_tm_diff (year
, yday
, hour
, min
, sec
, tp
)
147 int year
, yday
, hour
, min
, sec
;
154 /* Compute intervening leap days correctly even if year is negative.
155 Take care to avoid int overflow. time_t overflow is OK, since
156 only the low order bits of the correct time_t answer are needed.
157 Don't convert to time_t until after all divisions are done, since
158 time_t might be unsigned. */
159 int a4
= (year
>> 2) + (TM_YEAR_BASE
>> 2) - ! (year
& 3);
160 int b4
= (tp
->tm_year
>> 2) + (TM_YEAR_BASE
>> 2) - ! (tp
->tm_year
& 3);
161 int a100
= a4
/ 25 - (a4
% 25 < 0);
162 int b100
= b4
/ 25 - (b4
% 25 < 0);
163 int a400
= a100
>> 2;
164 int b400
= b100
>> 2;
165 int intervening_leap_days
= (a4
- b4
) - (a100
- b100
) + (a400
- b400
);
166 time_t years
= year
- (time_t) tp
->tm_year
;
167 time_t days
= (365 * years
+ intervening_leap_days
168 + (yday
- tp
->tm_yday
));
169 return (60 * (60 * (24 * days
+ (hour
- tp
->tm_hour
))
170 + (min
- tp
->tm_min
))
171 + (sec
- tp
->tm_sec
));
176 static time_t localtime_offset
;
178 /* Convert *TP to a time_t value. */
184 /* POSIX.1 8.1.1 requires that whenever mktime() is called, the
185 time zone names contained in the external variable `tzname' shall
186 be set as if the tzset() function had been called. */
190 return __mktime_internal (tp
, my_mktime_localtime_r
, &localtime_offset
);
193 /* Use CONVERT to convert *T to a broken down time in *TP.
194 If *T is out of range for conversion, adjust it so that
195 it is the nearest in-range value and then convert that. */
197 ranged_convert (convert
, t
, tp
)
198 struct tm
*(*convert
) __P ((const time_t *, struct tm
*));
204 if (! (r
= (*convert
) (t
, tp
)) && *t
)
210 /* BAD is a known unconvertible time_t, and OK is a known good one.
211 Use binary search to narrow the range between BAD and OK until
213 while (bad
!= ok
+ (bad
< 0 ? -1 : 1))
215 time_t mid
= *t
= (bad
< 0
216 ? bad
+ ((ok
- bad
) >> 1)
217 : ok
+ ((bad
- ok
) >> 1));
218 if ((r
= (*convert
) (t
, tp
)))
229 /* The last conversion attempt failed;
230 revert to the most recent successful attempt. */
241 /* Convert *TP to a time_t value, inverting
242 the monotonic and mostly-unit-linear conversion function CONVERT.
243 Use *OFFSET to keep track of a guess at the offset of the result,
244 compared to what the result would be for UTC without leap seconds.
245 If *OFFSET's guess is correct, only one CONVERT call is needed. */
247 __mktime_internal (tp
, convert
, offset
)
249 struct tm
*(*convert
) __P ((const time_t *, struct tm
*));
252 time_t t
, dt
, t0
, t1
, t2
;
255 /* The maximum number of probes (calls to CONVERT) should be enough
256 to handle any combinations of time zone rule changes, solar time,
257 leap seconds, and oscillations around a spring-forward gap.
258 POSIX.1 prohibits leap seconds, but some hosts have them anyway. */
259 int remaining_probes
= 6;
261 /* Time requested. Copy it in case CONVERT modifies *TP; this can
262 occur if TP is localtime's returned value and CONVERT is localtime. */
263 int sec
= tp
->tm_sec
;
264 int min
= tp
->tm_min
;
265 int hour
= tp
->tm_hour
;
266 int mday
= tp
->tm_mday
;
267 int mon
= tp
->tm_mon
;
268 int year_requested
= tp
->tm_year
;
269 int isdst
= tp
->tm_isdst
;
271 /* Ensure that mon is in range, and set year accordingly. */
272 int mon_remainder
= mon
% 12;
273 int negative_mon_remainder
= mon_remainder
< 0;
274 int mon_years
= mon
/ 12 - negative_mon_remainder
;
275 int year
= year_requested
+ mon_years
;
277 /* The other values need not be in range:
278 the remaining code handles minor overflows correctly,
279 assuming int and time_t arithmetic wraps around.
280 Major overflows are caught at the end. */
282 /* Calculate day of year from year, month, and day of month.
283 The result need not be in range. */
284 int yday
= ((__mon_yday
[__isleap (year
+ TM_YEAR_BASE
)]
285 [mon_remainder
+ 12 * negative_mon_remainder
])
288 int sec_requested
= sec
;
289 #if LEAP_SECONDS_POSSIBLE
290 /* Handle out-of-range seconds specially,
291 since ydhms_tm_diff assumes every minute has 60 seconds. */
298 /* Invert CONVERT by probing. First assume the same offset as last time.
299 Then repeatedly use the error to improve the guess. */
301 tm
.tm_year
= EPOCH_YEAR
- TM_YEAR_BASE
;
302 tm
.tm_yday
= tm
.tm_hour
= tm
.tm_min
= tm
.tm_sec
= 0;
303 t0
= ydhms_tm_diff (year
, yday
, hour
, min
, sec
, &tm
);
305 for (t
= t1
= t2
= t0
+ *offset
;
306 (dt
= ydhms_tm_diff (year
, yday
, hour
, min
, sec
,
307 ranged_convert (convert
, &t
, &tm
)));
308 t1
= t2
, t2
= t
, t
+= dt
)
309 if (t
== t1
&& t
!= t2
310 && (isdst
< 0 || tm
.tm_isdst
< 0
311 || (isdst
!= 0) != (tm
.tm_isdst
!= 0)))
312 /* We can't possibly find a match, as we are oscillating
313 between two values. The requested time probably falls
314 within a spring-forward gap of size DT. Follow the common
315 practice in this case, which is to return a time that is DT
316 away from the requested time, preferring a time whose
317 tm_isdst differs from the requested value. In practice,
318 this is more useful than returning -1. */
320 else if (--remaining_probes
== 0)
323 /* If we have a match, check whether tm.tm_isdst has the requested
325 if (dt
== 0 && isdst
!= tm
.tm_isdst
&& 0 <= isdst
&& 0 <= tm
.tm_isdst
)
327 /* tm.tm_isdst has the wrong value. Look for a neighboring
328 time with the right value, and use its UTC offset.
329 Heuristic: probe the previous three calendar quarters (approximately),
330 looking for the desired isdst. This isn't perfect,
331 but it's good enough in practice. */
332 int quarter
= 7889238; /* seconds per average 1/4 Gregorian year */
335 /* If we're too close to the time_t limit, look in future quarters. */
336 if (t
< TIME_T_MIN
+ 3 * quarter
)
339 for (i
= 1; i
<= 3; i
++)
341 time_t ot
= t
- i
* quarter
;
343 ranged_convert (convert
, &ot
, &otm
);
344 if (otm
.tm_isdst
== isdst
)
346 /* We found the desired tm_isdst.
347 Extrapolate back to the desired time. */
348 t
= ot
+ ydhms_tm_diff (year
, yday
, hour
, min
, sec
, &otm
);
349 ranged_convert (convert
, &t
, &tm
);
357 #if LEAP_SECONDS_POSSIBLE
358 if (sec_requested
!= tm
.tm_sec
)
360 /* Adjust time to reflect the tm_sec requested, not the normalized value.
361 Also, repair any damage from a false match due to a leap second. */
362 t
+= sec_requested
- sec
+ (sec
== 0 && tm
.tm_sec
== 60);
363 if (! (*convert
) (&t
, &tm
))
368 if (TIME_T_MAX
/ INT_MAX
/ 366 / 24 / 60 / 60 < 3)
370 /* time_t isn't large enough to rule out overflows in ydhms_tm_diff,
371 so check for major overflows. A gross check suffices,
372 since if t has overflowed, it is off by a multiple of
373 TIME_T_MAX - TIME_T_MIN + 1. So ignore any component of
374 the difference that is bounded by a small value. */
376 double dyear
= (double) year_requested
+ mon_years
- tm
.tm_year
;
377 double dday
= 366 * dyear
+ mday
;
378 double dsec
= 60 * (60 * (24 * dday
+ hour
) + min
) + sec_requested
;
380 /* On Irix4.0.5 cc, dividing TIME_T_MIN by 3 does not produce
381 correct results, ie., it erroneously gives a positive value
382 of 715827882. Setting a variable first then doing math on it
383 seems to work. (ghazi@caip.rutgers.edu) */
385 const time_t time_t_max
= TIME_T_MAX
;
386 const time_t time_t_min
= TIME_T_MIN
;
388 if (time_t_max
/ 3 - time_t_min
/ 3 < (dsec
< 0 ? - dsec
: dsec
))
397 weak_alias (mktime
, timelocal
)
407 return ((a
->tm_sec
^ b
->tm_sec
)
408 | (a
->tm_min
^ b
->tm_min
)
409 | (a
->tm_hour
^ b
->tm_hour
)
410 | (a
->tm_mday
^ b
->tm_mday
)
411 | (a
->tm_mon
^ b
->tm_mon
)
412 | (a
->tm_year
^ b
->tm_year
)
413 | (a
->tm_mday
^ b
->tm_mday
)
414 | (a
->tm_yday
^ b
->tm_yday
)
415 | (a
->tm_isdst
^ b
->tm_isdst
));
423 printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
424 tp
->tm_year
+ TM_YEAR_BASE
, tp
->tm_mon
+ 1, tp
->tm_mday
,
425 tp
->tm_hour
, tp
->tm_min
, tp
->tm_sec
,
426 tp
->tm_yday
, tp
->tm_wday
, tp
->tm_isdst
);
432 check_result (tk
, tmk
, tl
, lt
)
438 if (tk
!= tl
|| !lt
|| not_equal_tm (&tmk
, lt
))
442 printf (")\nyields (");
444 printf (") == %ld, should be %ld\n", (long) tl
, (long) tk
);
457 struct tm tm
, tmk
, tml
;
462 if ((argc
== 3 || argc
== 4)
463 && (sscanf (argv
[1], "%d-%d-%d%c",
464 &tm
.tm_year
, &tm
.tm_mon
, &tm
.tm_mday
, &trailer
)
466 && (sscanf (argv
[2], "%d:%d:%d%c",
467 &tm
.tm_hour
, &tm
.tm_min
, &tm
.tm_sec
, &trailer
)
470 tm
.tm_year
-= TM_YEAR_BASE
;
472 tm
.tm_isdst
= argc
== 3 ? -1 : atoi (argv
[3]);
475 lt
= localtime (&tl
);
481 printf ("mktime returns %ld == ", (long) tl
);
484 status
= check_result (tl
, tmk
, tl
, lt
);
486 else if (argc
== 4 || (argc
== 5 && strcmp (argv
[4], "-") == 0))
488 time_t from
= atol (argv
[1]);
489 time_t by
= atol (argv
[2]);
490 time_t to
= atol (argv
[3]);
493 for (tl
= from
; tl
<= to
; tl
+= by
)
495 lt
= localtime (&tl
);
500 status
|= check_result (tk
, tmk
, tl
, tml
);
504 printf ("localtime (%ld) yields 0\n", (long) tl
);
509 for (tl
= from
; tl
<= to
; tl
+= by
)
511 /* Null benchmark. */
512 lt
= localtime (&tl
);
517 status
|= check_result (tk
, tmk
, tl
, tml
);
521 printf ("localtime (%ld) yields 0\n", (long) tl
);
528 \t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\
529 \t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\
530 \t%s FROM BY TO - # Do not test those values (for benchmark).\n",
531 argv
[0], argv
[0], argv
[0]);
540 compile-command: "gcc -DDEBUG -DHAVE_LIMITS_H -DSTDC_HEADERS -Wall -W -O -g mktime.c -o mktime"