summaryrefslogtreecommitdiff
path: root/src/libical/icaltime.c
blob: b8b0f11bb08a8a4133d4ed0f3c04d1da99bbe164 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
/*======================================================================
 FILE: icaltime.c
 CREATOR: eric 02 June 2000

 (C) COPYRIGHT 2000, Eric Busboom <eric@civicknowledge.com>

 The timegm code is Copyright (c) 2001-2006, NLnet Labs. All rights reserved.

 This library is free software; you can redistribute it and/or modify
 it under the terms of either:

    The LGPL as published by the Free Software Foundation, version
    2.1, available at: https://www.gnu.org/licenses/lgpl-2.1.html

 Or:

    The Mozilla Public License Version 2.0. You may obtain a copy of
    the License at https://www.mozilla.org/MPL/

 The Original Code is eric. The Initial Developer of the Original
 Code is Eric Busboom

 The timegm code in this file is copyrighted by NLNET LABS 2001-2006,
 according to the following conditions:

 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
  * and/or other materials provided with the distribution.

 * Neither the name of the NLNET LABS nor the names of its contributors may
   be used to endorse or promote products derived from this software without
   specific prior written permission.

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   POSSIBILITY OF SUCH DAMAGE.
======================================================================*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "icaltime.h"
#include "astime.h"
#include "icalerror.h"
#include "icalmemory.h"
#include "icaltimezone.h"

#include <ctype.h>
#include <stdlib.h>

/* The first array is for non-leap years, the second for leap years*/
static const int days_in_year_passed_month[2][13] = {
    /* jan feb mar  apr  may  jun  jul  aug  sep  oct  nov  dec */
    {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
    {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}
};

static int icaltime_leap_days(int y1, int y2)
{
    --y1;
    --y2;
    return (y2 / 4 - y1 / 4) - (y2 / 100 - y1 / 100) + (y2 / 400 - y1 / 400);
}

/*
 * Code adapted from Python 2.4.1 sources (Lib/calendar.py).
 */
static time_t icaltime_timegm(const struct tm *tm)
{
    int year;
    time_t days;
    time_t hours;
    time_t minutes;
    time_t seconds;

    year = 1900 + tm->tm_year;
    days = (time_t)(365 * (year - 1970) + icaltime_leap_days(1970, year));
    days += days_in_year_passed_month[0][tm->tm_mon];

    if (tm->tm_mon > 1 && icaltime_is_leap_year(year))
        ++days;

    days += tm->tm_mday - 1;
    hours = days * 24 + tm->tm_hour;
    minutes = hours * 60 + tm->tm_min;
    seconds = minutes * 60 + tm->tm_sec;

    return seconds;
}

/*
 *  Function to convert a struct tm time specification
 *  to an ANSI time_t using the specified time zone.
 *  This is different from the standard mktime() function
 *  in that we don't want the automatic adjustments for
 *  local daylight savings time applied to the result.
 *  This function expects well-formed input.
 */
static time_t make_time(struct tm *tm, int tzm)
{
    time_t tim;
    int febs;

    static int days[] = { -1, 30, 58, 89, 119, 150, 180, 211, 242, 272, 303, 333, 364 };

    /* check that month specification within range */

    if (tm->tm_mon < 0 || tm->tm_mon > 11)
        return ((time_t) - 1);

    if (tm->tm_year < 2)
        return ((time_t)-1);

#if (SIZEOF_TIME_T == 4)
    /* check that year specification within range */

    if (tm->tm_year > 138)
        return ((time_t) - 1);

    /* check for upper bound of Jan 17, 2038 (to avoid possibility of
       32-bit arithmetic overflow) */

    if (tm->tm_year == 138) {
        if (tm->tm_mon > 0) {
            return ((time_t) - 1);
        } else if (tm->tm_mday > 17) {
            return ((time_t) - 1);
        }
    }
#else
    /* We don't support years >= 10000, because the function has not been tested at this range. */
    if (tm->tm_year >= 8100) {
        return ((time_t)-1);
    }
#endif /* SIZEOF_TIME_T */

    /*
     *  calculate elapsed days since start of the epoch (midnight Jan
     *  1st, 1970 UTC) 17 = number of leap years between 1900 and 1970
     *  (number of leap days to subtract)
     */

    tim = (time_t) ((tm->tm_year - 70) * 365 + ((tm->tm_year - 1) / 4) - 17);

    /* adjust: no leap days every 100 years, except every 400 years. */

    febs = (tm->tm_year - 100) - ((tm->tm_mon <= 1) ? 1 : 0);
    tim -= febs / 100;
    tim += febs / 400;

    /* add number of days elapsed in the current year */

    tim += days[tm->tm_mon];

    /* check and adjust for leap years */

    if ((tm->tm_year & 3) == 0 && tm->tm_mon > 1)
        tim += 1;

    /* elapsed days to current date */

    tim += tm->tm_mday;

    /* calculate elapsed hours since start of the epoch */

    tim = tim * 24 + tm->tm_hour;

    /* calculate elapsed minutes since start of the epoch */

    tim = tim * 60 + tm->tm_min;

    /* adjust per time zone specification */

    tim -= tzm;

    /* calculate elapsed seconds since start of the epoch */

    tim = tim * 60 + tm->tm_sec;

    /* return number of seconds since start of the epoch */

    return (tim);
}

struct icaltimetype icaltime_from_timet_with_zone(const time_t tm, const int is_date,
                                                  const icaltimezone *zone)
{
    struct icaltimetype tt;
    struct tm t;
    icaltimezone *utc_zone;

    utc_zone = icaltimezone_get_utc_timezone();

    /* Convert the time_t to a struct tm in UTC time. We can trust gmtime for this. */
    if (!gmtime_r(&tm, &t))
        return is_date ? icaltime_null_date () : icaltime_null_time ();

    tt.year = t.tm_year + 1900;
    tt.month = t.tm_mon + 1;
    tt.day = t.tm_mday;
    tt.hour = t.tm_hour;
    tt.minute = t.tm_min;
    tt.second = t.tm_sec;
    tt.is_date = 0;
    tt.is_daylight = 0;
    tt.zone = (zone == NULL) ? NULL : utc_zone;

    /* Use our timezone functions to convert to the required timezone. */
    icaltimezone_convert_time(&tt, utc_zone, (icaltimezone *) zone);

    tt.is_date = is_date;

    /* If it is a DATE value, make sure hour, minute & second are 0. */
    if (is_date) {
        tt.hour = 0;
        tt.minute = 0;
        tt.second = 0;
    }

    return tt;
}

struct icaltimetype icaltime_current_time_with_zone(const icaltimezone *zone)
{
    return icaltime_from_timet_with_zone(time(NULL), 0, zone);
}

struct icaltimetype icaltime_today(void)
{
    return icaltime_from_timet_with_zone(time(NULL), 1, NULL);
}

time_t icaltime_as_timet(const struct icaltimetype tt)
{
    struct tm stm;
    time_t t;

    /* If the time is the special null time, return 0. */
    if (icaltime_is_null_time(tt)) {
        return 0;
    }

    /* Copy the icaltimetype to a struct tm. */
    memset(&stm, 0, sizeof(struct tm));

    if (icaltime_is_date(tt)) {
        stm.tm_sec = stm.tm_min = stm.tm_hour = 0;
    } else {
        stm.tm_sec = tt.second;
        stm.tm_min = tt.minute;
        stm.tm_hour = tt.hour;
    }

    stm.tm_mday = tt.day;
    stm.tm_mon = tt.month - 1;
    stm.tm_year = tt.year - 1900;
    stm.tm_isdst = -1;

    t = make_time(&stm, 0);

    return t;
}

time_t icaltime_as_timet_with_zone(const struct icaltimetype tt, const icaltimezone *zone)
{
    icaltimezone *utc_zone;
    struct tm stm;
    time_t t;
    struct icaltimetype local_tt;

    utc_zone = icaltimezone_get_utc_timezone();

    /* If the time is the special null time, return 0. */
    if (icaltime_is_null_time(tt)) {
        return 0;
    }

    local_tt = tt;

    /* Clear the is_date flag, so we can convert the time. */
    local_tt.is_date = 0;

    /* Use our timezone functions to convert to UTC. */
    icaltimezone_convert_time(&local_tt, (icaltimezone *) zone, utc_zone);

    /* Copy the icaltimetype to a struct tm. */
    memset(&stm, 0, sizeof(struct tm));

    stm.tm_sec = local_tt.second;
    stm.tm_min = local_tt.minute;
    stm.tm_hour = local_tt.hour;
    stm.tm_mday = local_tt.day;
    stm.tm_mon = local_tt.month - 1;
    stm.tm_year = local_tt.year - 1900;
    stm.tm_isdst = -1;

    t = icaltime_timegm(&stm);

    return t;
}

const char *icaltime_as_ical_string(const struct icaltimetype tt)
{
    char *buf;

    buf = icaltime_as_ical_string_r(tt);
    icalmemory_add_tmp_buffer(buf);
    return buf;
}

char *icaltime_as_ical_string_r(const struct icaltimetype tt)
{
    size_t size = 17;
    char *buf = icalmemory_new_buffer(size);

    if (tt.is_date) {
        snprintf(buf, size, "%04d%02d%02d", tt.year, tt.month, tt.day);
    } else {
        const char *fmt;

        if (icaltime_is_utc(tt)) {
            fmt = "%04d%02d%02dT%02d%02d%02dZ";
        } else {
            fmt = "%04d%02d%02dT%02d%02d%02d";
        }
        snprintf(buf, size, fmt, tt.year, tt.month, tt.day, tt.hour, tt.minute, tt.second);
    }

    return buf;
}

/* Implementation note: we call icaltime_adjust() with no adjustment. */
struct icaltimetype icaltime_normalize(const struct icaltimetype tt)
{
    struct icaltimetype ret = tt;

    icaltime_adjust(&ret, 0, 0, 0, 0);
    return ret;
}

struct icaltimetype icaltime_from_string(const char *str)
{
    struct icaltimetype tt = icaltime_null_time();
    size_t size;

    icalerror_check_arg_re(str != 0, "str", icaltime_null_time());

    size = strlen(str);

    if ((size == 15) || (size == 19)) { /* floating time with/without separators */
        tt.is_date = 0;
    } else if ((size == 16) || (size == 20)) {  /* UTC time, ends in 'Z' */
        if ((str[size-1] != 'Z'))
            goto FAIL;

        tt.zone = icaltimezone_get_utc_timezone();
        tt.is_date = 0;
    } else if ((size == 8) || (size == 10)) {   /* A DATE */
        tt.is_date = 1;
    } else {    /* error */
        goto FAIL;
    }

    if (tt.is_date == 1) {
        if (size == 10) {
            char dsep1, dsep2;

            if (sscanf(str, "%04d%c%02d%c%02d",
                       &tt.year, &dsep1, &tt.month, &dsep2, &tt.day) < 5) {
                goto FAIL;
            }

            if ((dsep1 != '-') || (dsep2 != '-')) {
                goto FAIL;
            }
        } else if (sscanf(str, "%04d%02d%02d", &tt.year, &tt.month, &tt.day) < 3) {
            goto FAIL;
        }
    } else {
        if (size > 16) {
            char dsep1, dsep2, tsep, tsep1, tsep2;

            if (sscanf(str, "%04d%c%02d%c%02d%c%02d%c%02d%c%02d",
                       &tt.year, &dsep1, &tt.month, &dsep2, &tt.day, &tsep,
                       &tt.hour, &tsep1, &tt.minute, &tsep2, &tt.second) < 11) {
                goto FAIL;
            }

            if ((tsep != 'T') ||
                (dsep1 != '-') || (dsep2 != '-') ||
                (tsep1 != ':') || (tsep2 != ':')) {
                goto FAIL;
            }

        } else {
            char tsep;

            if (sscanf(str, "%04d%02d%02d%c%02d%02d%02d",
                       &tt.year, &tt.month, &tt.day, &tsep,
                       &tt.hour, &tt.minute, &tt.second) < 7) {
                goto FAIL;
            }

            if (tsep != 'T') {
                goto FAIL;
            }
        }
    }

    return tt;

  FAIL:
    icalerror_set_errno(ICAL_MALFORMEDDATA_ERROR);
    return icaltime_null_time();
}

int icaltime_is_leap_year(const int year)
{
    if (year <= 1752) {
        return (year % 4 == 0);
    } else {
        return ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0);
    }
}

int icaltime_days_in_year(const int year)
{
    if (icaltime_is_leap_year(year)) {
        return 366;
    } else {
        return 365;
    }
}

static const int _days_in_month[] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

int icaltime_days_in_month(const int month, const int year)
{
    int days;

/* The old code aborting if it was passed a parameter like BYMONTH=0
 * Unfortunately it's not practical right now to pass an error all
 * the way up the stack, so instead of aborting we're going to apply
 * the GIGO principle and simply return '30 days' if we get an
 * invalid month.  Modern applications cannot tolerate crashing.
 *  assert(month > 0);
 *  assert(month <= 12);
 */
    if ((month < 1) || (month > 12)) {
        return 30;
    }

    days = _days_in_month[month];

    if (month == 2) {
        days += icaltime_is_leap_year(year);
    }

    return days;
}

/* 1-> Sunday, 7->Saturday */
int icaltime_day_of_week(const struct icaltimetype t)
{
    UTinstant jt;

    memset(&jt, 0, sizeof(UTinstant));

    jt.year = t.year;
    jt.month = t.month;
    jt.day = t.day;
    jt.i_hour = 0;
    jt.i_minute = 0;
    jt.i_second = 0;

    (void)juldat(&jt);

    return jt.weekday + 1;
}

int icaltime_start_doy_week(const struct icaltimetype t, int fdow)
{
    UTinstant jt;
    int delta;

    memset(&jt, 0, sizeof(UTinstant));

    jt.year = t.year;
    jt.month = t.month;
    jt.day = t.day;
    jt.i_hour = 0;
    jt.i_minute = 0;
    jt.i_second = 0;

    (void)juldat(&jt);
    (void)caldat(&jt);

    delta = jt.weekday - (fdow - 1);
    if (delta < 0) {
        delta += 7;
    }
    return jt.day_of_year - delta;
}

int icaltime_week_number(const struct icaltimetype ictt)
{
    UTinstant jt;

    memset(&jt, 0, sizeof(UTinstant));

    jt.year = ictt.year;
    jt.month = ictt.month;
    jt.day = ictt.day;
    jt.i_hour = 0;
    jt.i_minute = 0;
    jt.i_second = 0;

    (void)juldat(&jt);
    (void)caldat(&jt);

    return (jt.day_of_year - jt.weekday) / 7;
}

int icaltime_day_of_year(const struct icaltimetype t)
{
    int is_leap = icaltime_is_leap_year(t.year);

    return days_in_year_passed_month[is_leap][t.month - 1] + t.day;
}

struct icaltimetype icaltime_from_day_of_year(const int _doy, const int _year)
{
    struct icaltimetype tt = icaltime_null_date();
    int is_leap;
    int month;
    int doy = _doy;
    int year = _year;

    is_leap = icaltime_is_leap_year(year);

    /* Zero and neg numbers represent days  of the previous year */
    if (doy < 1) {
        year--;
        is_leap = icaltime_is_leap_year(year);
        doy += days_in_year_passed_month[is_leap][12];
    } else if (doy > days_in_year_passed_month[is_leap][12]) {
        /* Move on to the next year */
        is_leap = icaltime_is_leap_year(year);
        doy -= days_in_year_passed_month[is_leap][12];
        year++;
    }

    tt.year = year;

    for (month = 11; month >= 0; month--) {
        if (doy > days_in_year_passed_month[is_leap][month]) {
            tt.month = month + 1;
            tt.day = doy - days_in_year_passed_month[is_leap][month];
            break;
        }
    }

    return tt;
}

struct icaltimetype icaltime_null_time(void)
{
    struct icaltimetype t;

    memset(&t, 0, sizeof(struct icaltimetype));

    return t;
}

struct icaltimetype icaltime_null_date(void)
{
    struct icaltimetype t;

    memset(&t, 0, sizeof(struct icaltimetype));

    t.is_date = 1;

    /*
     * Init to -1 to match what icalyacc.y used to do.
     * Does anything depend on this?
     */
    t.hour = -1;
    t.minute = -1;
    t.second = -1;

    return t;
}

int icaltime_is_valid_time(const struct icaltimetype t)
{
    if (t.year < 0 || t.year > 3000 || t.is_date > 1 || t.is_date < 0) {
        return 0;
    } else {
        return 1;
    }
}

int icaltime_is_date(const struct icaltimetype t)
{
    return t.is_date;
}

int icaltime_is_utc(const struct icaltimetype t)
{
    return t.zone == icaltimezone_get_utc_timezone();
}

int icaltime_is_null_time(const struct icaltimetype t)
{
    if (t.second + t.minute + t.hour + t.day + t.month + t.year == 0) {
        return 1;
    }

    return 0;
}

int icaltime_compare(const struct icaltimetype a_in, const struct icaltimetype b_in)
{
    struct icaltimetype a, b;

    /* We only need to perform time zone conversion if times aren't in the same time zone
       or neither of them is floating (zone equals NULL) */
    if (a_in.zone != b_in.zone && a_in.zone != NULL && b_in.zone != NULL) {
        a = icaltime_convert_to_zone(a_in, icaltimezone_get_utc_timezone());
        b = icaltime_convert_to_zone(b_in, icaltimezone_get_utc_timezone());
    } else {
        a = a_in;
        b = b_in;
    }

    if (a.year > b.year) {
        return 1;
    } else if (a.year < b.year) {
        return -1;
    } else if (a.month > b.month) {
        return 1;
    } else if (a.month < b.month) {
        return -1;
    } else if (a.day > b.day) {
        return 1;
    } else if (a.day < b.day) {
        return -1;
    }

    /* if both are dates, we are done */
    if (a.is_date && b.is_date) {
        return 0;

    /* else, if only one is a date (and we already know the date part is equal),
       then the other is greater */
    } else if (b.is_date) {
        return 1;
    } else if (a.is_date) {
        return -1;
    } else if (a.hour > b.hour) {
        return 1;
    } else if (a.hour < b.hour) {
        return -1;
    } else if (a.minute > b.minute) {
        return 1;
    } else if (a.minute < b.minute) {
        return -1;
    } else if (a.second > b.second) {
        return 1;
    } else if (a.second < b.second) {
        return -1;
    }

    return 0;
}

int icaltime_compare_date_only(const struct icaltimetype a_in,
                               const struct icaltimetype b_in)
{
    struct icaltimetype a, b;
    icaltimezone *tz = icaltimezone_get_utc_timezone();

    a = icaltime_convert_to_zone(a_in, tz);
    b = icaltime_convert_to_zone(b_in, tz);

    if (a.year > b.year) {
        return 1;
    } else if (a.year < b.year) {
        return -1;
    }

    if (a.month > b.month) {
        return 1;
    } else if (a.month < b.month) {
        return -1;
    }

    if (a.day > b.day) {
        return 1;
    } else if (a.day < b.day) {
        return -1;
    }

    return 0;
}

int icaltime_compare_date_only_tz(const struct icaltimetype a_in,
                                  const struct icaltimetype b_in,
                                  icaltimezone *tz)
{
    struct icaltimetype a, b;

    a = icaltime_convert_to_zone(a_in, tz);
    b = icaltime_convert_to_zone(b_in, tz);

    if (a.year > b.year) {
        return 1;
    } else if (a.year < b.year) {
        return -1;
    }

    if (a.month > b.month) {
        return 1;
    } else if (a.month < b.month) {
        return -1;
    }

    if (a.day > b.day) {
        return 1;
    } else if (a.day < b.day) {
        return -1;
    }

    return 0;
}

/* These are defined in icalduration.c:
struct icaltimetype  icaltime_add(struct icaltimetype t,
                                  struct icaldurationtype  d)
struct icaldurationtype  icaltime_subtract(struct icaltimetype t1,
                                           struct icaltimetype t2)
*/

void icaltime_adjust(struct icaltimetype *tt,
                     const int days, const int hours,
                     const int minutes, const int seconds)
{
    int second, minute, hour, day;
    int minutes_overflow, hours_overflow, days_overflow = 0, years_overflow;
    int days_in_month;

    /* If we are passed a date make sure to ignore hour minute and second */
    if (tt->is_date)
        goto IS_DATE;

    /* Add on the seconds. */
    second = tt->second + seconds;
    tt->second = second % 60;
    minutes_overflow = second / 60;
    if (tt->second < 0) {
        tt->second += 60;
        minutes_overflow--;
    }

    /* Add on the minutes. */
    minute = tt->minute + minutes + minutes_overflow;
    tt->minute = minute % 60;
    hours_overflow = minute / 60;
    if (tt->minute < 0) {
        tt->minute += 60;
        hours_overflow--;
    }

    /* Add on the hours. */
    hour = tt->hour + hours + hours_overflow;
    tt->hour = hour % 24;
    days_overflow = hour / 24;
    if (tt->hour < 0) {
        tt->hour += 24;
        days_overflow--;
    }

  IS_DATE:
    /* Normalize the month. We do this before handling the day since we may
       need to know what month it is to get the number of days in it.
       Note that months are 1 to 12, so we have to be a bit careful. */
    if (tt->month >= 13) {
        years_overflow = (tt->month - 1) / 12;
        tt->year += years_overflow;
        tt->month -= years_overflow * 12;
    } else if (tt->month <= 0) {
        /* 0 to -11 is -1 year out, -12 to -23 is -2 years. */
        years_overflow = (tt->month / 12) - 1;
        tt->year += years_overflow;
        tt->month -= years_overflow * 12;
    }

    /* Add on the days. */
    day = tt->day + days + days_overflow;
    if (day > 0) {
        for (;;) {
            days_in_month = icaltime_days_in_month(tt->month, tt->year);
            if (day <= days_in_month)
                break;

            tt->month++;
            if (tt->month >= 13) {
                tt->year++;
                tt->month = 1;
            }

            day -= days_in_month;
        }
    } else {
        while (day <= 0) {
            if (tt->month == 1) {
                tt->year--;
                tt->month = 12;
            } else {
                tt->month--;
            }

            day += icaltime_days_in_month(tt->month, tt->year);
        }
    }
    tt->day = day;
}

struct icaltimetype icaltime_convert_to_zone(const struct icaltimetype tt, icaltimezone *zone)
{
    struct icaltimetype ret = tt;

    /* If it's a date do nothing */
    if (tt.is_date) {
        return ret;
    }

    if (tt.zone == zone) {
        return ret;
    }

    /* If it's a floating time we don't want to adjust the time */
    if (tt.zone != NULL) {
        icaltimezone *from_zone = (icaltimezone *) tt.zone;

        if (!from_zone) {
            from_zone = icaltimezone_get_utc_timezone();
        }

        icaltimezone_convert_time(&ret, from_zone, zone);
    }

    ret.zone = zone;

    return ret;
}

const icaltimezone *icaltime_get_timezone(const struct icaltimetype t)
{
    return t.zone;
}

const char *icaltime_get_tzid(const struct icaltimetype t)
{
    if (t.zone != NULL) {
        return icaltimezone_get_tzid((icaltimezone *) t.zone);
    } else {
        return NULL;
    }
}

struct icaltimetype icaltime_set_timezone(struct icaltimetype *t, const icaltimezone *zone)
{
    /* If it's a date do nothing */
    if (t->is_date) {
        return *t;
    }

    if (t->zone == zone) {
        return *t;
    }

    t->zone = zone;

    return *t;
}

icaltime_span icaltime_span_new(struct icaltimetype dtstart, struct icaltimetype dtend, int is_busy)
{
    icaltime_span span;

    span.is_busy = is_busy;

    span.start = icaltime_as_timet_with_zone(dtstart,
                                             dtstart.zone ? dtstart.
                                             zone : icaltimezone_get_utc_timezone());

    if (icaltime_is_null_time(dtend)) {
        if (!icaltime_is_date(dtstart)) {
            /* If dtstart is a DATE-TIME and there is no DTEND nor DURATION
               it takes no time */
            span.end = span.start;
            return span;
        } else {
            dtend = dtstart;
        }
    }

    span.end = icaltime_as_timet_with_zone(dtend,
                                           dtend.zone ? dtend.
                                           zone : icaltimezone_get_utc_timezone());

    if (icaltime_is_date(dtstart)) {
        /* no time specified, go until the end of the day.. */
        span.end += 60 * 60 * 24 - 1;
    }
    return span;
}

int icaltime_span_overlaps(icaltime_span *s1, icaltime_span *s2)
{
    /* s1->start in s2 */
    if (s1->start > s2->start && s1->start < s2->end)
        return 1;

    /* s1->end in s2 */
    if (s1->end > s2->start && s1->end < s2->end)
        return 1;

    /* s2->start in s1 */
    if (s2->start > s1->start && s2->start < s1->end)
        return 1;

    /* s2->end in s1 */
    if (s2->end > s1->start && s2->end < s1->end)
        return 1;

    if (s1->start == s2->start && s1->end == s2->end)
        return 1;

    return 0;
}

int icaltime_span_contains(icaltime_span *s, icaltime_span *container)
{
    if ((s->start >= container->start && s->start < container->end) &&
        (s->end <= container->end && s->end > container->start)) {
        return 1;
    }

    return 0;
}