summaryrefslogtreecommitdiffstats
path: root/contrib/patch/maketime.c
blob: e66f9df0c3759a80915393bad19b2baa0b97d2ad (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
/* Convert struct partime into time_t.  */

/* Copyright 1992, 1993, 1994, 1995, 1997 Paul Eggert
   Distributed under license by the Free Software Foundation, Inc.

   This file is part of RCS.

   RCS 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.

   RCS 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 RCS; see the file COPYING.
   If not, write to the Free Software Foundation,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Report problems and direct all questions to:

	rcs-bugs@cs.purdue.edu

 */

#if has_conf_h
# include <conf.h>
#else
# if HAVE_CONFIG_H
#  include <config.h>
# else
#  ifndef __STDC__
#   define const
#  endif
# endif
  /* MIPS RISCOS4.52 defines time_t in <sys/types.h> not <time.h>.  */
# include <sys/types.h>
# if HAVE_LIMITS_H
#  include <limits.h>
# endif
# ifndef LONG_MIN
# define LONG_MIN (-1-2147483647L)
# endif
# if STDC_HEADERS
#  include <stdlib.h>
# endif
# include <time.h>
# ifdef __STDC__
#  define P(x) x
# else
#  define P(x) ()
# endif
#endif

#include <partime.h>
#include <maketime.h>

char const maketId[] =
  "$Id: maketime.c,v 5.15 1997/06/17 16:54:36 eggert Exp $";

static int isleap P ((int));
static int month_days P ((struct tm const *));
static time_t maketime P ((struct partime const *, time_t));

/* For maximum portability, use only localtime and gmtime.
   Make no assumptions about the time_t epoch or the range of time_t values.
   Avoid mktime because it's not universal and because there's no easy,
   portable way for mktime to yield the inverse of gmtime.  */

#define TM_YEAR_ORIGIN 1900

static int
isleap (y)
     int y;
{
  return (y & 3) == 0 && (y % 100 != 0 || y % 400 == 0);
}

/* days in year before start of months 0-12 */
static int const month_yday[] =
{
  0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
};

/* Yield the number of days in TM's month.  */
static int
month_days (tm)
     struct tm const *tm;
{
  int m = tm->tm_mon;
  return (month_yday[m + 1] - month_yday[m]
	  + (m == 1 && isleap (tm->tm_year + TM_YEAR_ORIGIN)));
}

/* Convert UNIXTIME to struct tm form.
   Use gmtime if available and if !LOCALZONE, localtime otherwise.  */
struct tm *
time2tm (unixtime, localzone)
     time_t unixtime;
     int localzone;
{
  struct tm *tm;
#ifdef TZ_is_unset
  static char const *TZ;
  if (!TZ && !(TZ = getenv ("TZ")))
    TZ_is_unset ("The TZ environment variable is not set; please set it to your timezone");
#endif
  if (localzone || !(tm = gmtime (&unixtime)))
    tm = localtime (&unixtime);
  return tm;
}

/* Yield A - B, measured in seconds.  */
time_t
difftm (a, b)
     struct tm const *a;
     struct tm const *b;
{
  int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
  int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
  int ac = ay / 100 - (ay % 100 < 0);
  int bc = by / 100 - (by % 100 < 0);
  int difference_in_day_of_year = a->tm_yday - b->tm_yday;
  int intervening_leap_days = (((ay >> 2) - (by >> 2))
			       - (ac - bc)
			       + ((ac >> 2) - (bc >> 2)));
  time_t difference_in_years = ay - by;
  time_t difference_in_days
    = (difference_in_years * 365
       + (intervening_leap_days + difference_in_day_of_year));
  return (((((difference_in_days * 24
	      + (a->tm_hour - b->tm_hour))
	     * 60)
	    + (a->tm_min - b->tm_min))
	   * 60)
	  + (a->tm_sec - b->tm_sec));
}

/*
   * Adjust time T by adding SECONDS.  SECONDS must be at most 24 hours' worth.
   * Adjust only T's year, mon, mday, hour, min and sec members;
   * plus adjust wday if it is defined.
 */
void
adjzone (t, seconds)
     register struct tm *t;
     long seconds;
{
  /*
     * This code can be off by a second if SECONDS is not a multiple of 60,
     * if T is local time, and if a leap second happens during this minute.
     * But this bug has never occurred, and most likely will not ever occur.
     * Liberia, the last country for which SECONDS % 60 was nonzero,
     * switched to UTC in May 1972; the first leap second was in June 1972.
   */
  int leap_second = t->tm_sec == 60;
  long sec = seconds + (t->tm_sec - leap_second);
  if (sec < 0)
    {
      if ((t->tm_min -= (59 - sec) / 60) < 0)
	{
	  if ((t->tm_hour -= (59 - t->tm_min) / 60) < 0)
	    {
	      t->tm_hour += 24;
	      if (TM_DEFINED (t->tm_wday) && --t->tm_wday < 0)
		t->tm_wday = 6;
	      if (--t->tm_mday <= 0)
		{
		  if (--t->tm_mon < 0)
		    {
		      --t->tm_year;
		      t->tm_mon = 11;
		    }
		  t->tm_mday = month_days (t);
		}
	    }
	  t->tm_min += 24 * 60;
	}
      sec += 24L * 60 * 60;
    }
  else if (60 <= (t->tm_min += sec / 60))
    if (24 <= (t->tm_hour += t->tm_min / 60))
      {
	t->tm_hour -= 24;
	if (TM_DEFINED (t->tm_wday) && ++t->tm_wday == 7)
	  t->tm_wday = 0;
	if (month_days (t) < ++t->tm_mday)
	  {
	    if (11 < ++t->tm_mon)
	      {
		++t->tm_year;
		t->tm_mon = 0;
	      }
	    t->tm_mday = 1;
	  }
      }
  t->tm_min %= 60;
  t->tm_sec = (int) (sec % 60) + leap_second;
}

/*
   * Convert TM to time_t, using localtime if LOCALZONE and gmtime otherwise.
   * Use only TM's year, mon, mday, hour, min, and sec members.
   * Ignore TM's old tm_yday and tm_wday, but fill in their correct values.
   * Yield -1 on failure (e.g. a member out of range).
   * Posix 1003.1-1990 doesn't allow leap seconds, but some implementations
   * have them anyway, so allow them if localtime/gmtime does.
 */
time_t
tm2time (tm, localzone)
     struct tm *tm;
     int localzone;
{
  /* Cache the most recent t,tm pairs; 1 for gmtime, 1 for localtime.  */
  static time_t t_cache[2];
  static struct tm tm_cache[2];

  time_t d, gt;
  struct tm const *gtm;
  /*
     * The maximum number of iterations should be enough to handle any
     * combinations of leap seconds, time zone rule changes, and solar time.
     * 4 is probably enough; we use a bigger number just to be safe.
   */
  int remaining_tries = 8;

  /* Avoid subscript errors.  */
  if (12 <= (unsigned) tm->tm_mon)
    return -1;

  tm->tm_yday = month_yday[tm->tm_mon] + tm->tm_mday
    - (tm->tm_mon < 2 || !isleap (tm->tm_year + TM_YEAR_ORIGIN));

  /* Make a first guess.  */
  gt = t_cache[localzone];
  gtm = gt ? &tm_cache[localzone] : time2tm (gt, localzone);

  /* Repeatedly use the error from the guess to improve the guess.  */
  while ((d = difftm (tm, gtm)) != 0)
    {
      if (--remaining_tries == 0)
	return -1;
      gt += d;
      gtm = time2tm (gt, localzone);
    }

  /*
     * Check that the guess actually matches;
     * overflow can cause difftm to yield 0 even on differing times,
     * or tm may have members out of range (e.g. bad leap seconds).
   */
#define TM_DIFFER(a,b) \
		( \
			((a)->tm_year ^ (b)->tm_year) | \
			((a)->tm_mon ^ (b)->tm_mon) | \
			((a)->tm_mday ^ (b)->tm_mday) | \
			((a)->tm_hour ^ (b)->tm_hour) | \
			((a)->tm_min ^ (b)->tm_min) | \
			((a)->tm_sec ^ (b)->tm_sec) \
		)
  if (TM_DIFFER (tm, gtm))
    {
      /*
         * If gt is a leap second, try gt+1; if it is one greater than
         * a leap second, try gt-1; otherwise, it doesn't matter.
         * Leap seconds always fall at month end.
       */
      int yd = tm->tm_year - gtm->tm_year;
      gt += yd + (yd ? 0 : tm->tm_mon - gtm->tm_mon);
      gtm = time2tm (gt, localzone);
      if (TM_DIFFER (tm, gtm))
	return -1;
    }
  t_cache[localzone] = gt;
  tm_cache[localzone] = *gtm;

  tm->tm_wday = gtm->tm_wday;
  return gt;
}

/*
   * Check *PT and convert it to time_t.
   * If it is incompletely specified, use DEFAULT_TIME to fill it out.
   * Use localtime if PT->zone is the special value TM_LOCAL_ZONE.
   * Yield -1 on failure.
   * ISO 8601 day-of-year and week numbers are not yet supported.
 */
static time_t
maketime (pt, default_time)
     struct partime const *pt;
     time_t default_time;
{
  int localzone, wday;
  struct tm tm;
  struct tm *tm0 = 0;
  time_t r;

  tm0 = 0;			/* Keep gcc -Wall happy.  */
  localzone = pt->zone == TM_LOCAL_ZONE;

  tm = pt->tm;

  if (TM_DEFINED (pt->ymodulus) || !TM_DEFINED (tm.tm_year))
    {
      /* Get tm corresponding to default time.  */
      tm0 = time2tm (default_time, localzone);
      if (!localzone)
	adjzone (tm0, pt->zone);
    }

  if (TM_DEFINED (pt->ymodulus))
    tm.tm_year +=
      (tm0->tm_year + TM_YEAR_ORIGIN) / pt->ymodulus * pt->ymodulus;
  else if (!TM_DEFINED (tm.tm_year))
    {
      /* Set default year, month, day from current time.  */
      tm.tm_year = tm0->tm_year + TM_YEAR_ORIGIN;
      if (!TM_DEFINED (tm.tm_mon))
	{
	  tm.tm_mon = tm0->tm_mon;
	  if (!TM_DEFINED (tm.tm_mday))
	    tm.tm_mday = tm0->tm_mday;
	}
    }

  /* Convert from partime year (Gregorian) to Posix year.  */
  tm.tm_year -= TM_YEAR_ORIGIN;

  /* Set remaining default fields to be their minimum values.  */
  if (!TM_DEFINED (tm.tm_mon))
    tm.tm_mon = 0;
  if (!TM_DEFINED (tm.tm_mday))
    tm.tm_mday = 1;
  if (!TM_DEFINED (tm.tm_hour))
    tm.tm_hour = 0;
  if (!TM_DEFINED (tm.tm_min))
    tm.tm_min = 0;
  if (!TM_DEFINED (tm.tm_sec))
    tm.tm_sec = 0;

  if (!localzone)
    adjzone (&tm, -pt->zone);
  wday = tm.tm_wday;

  /* Convert and fill in the rest of the tm.  */
  r = tm2time (&tm, localzone);

  /* Check weekday.  */
  if (r != -1 && TM_DEFINED (wday) && wday != tm.tm_wday)
    return -1;

  return r;
}

/* Parse a free-format date in SOURCE, yielding a Unix format time.  */
time_t
str2time (source, default_time, default_zone)
     char const *source;
     time_t default_time;
     long default_zone;
{
  struct partime pt;

  if (*partime (source, &pt))
    return -1;
  if (pt.zone == TM_UNDEFINED_ZONE)
    pt.zone = default_zone;
  return maketime (&pt, default_time);
}

#if TEST
#include <stdio.h>
int
main (argc, argv)
     int argc;
     char **argv;
{
  time_t default_time = time ((time_t *) 0);
  long default_zone = argv[1] ? atol (argv[1]) : 0;
  char buf[1000];
  while (fgets (buf, sizeof (buf), stdin))
    {
      time_t t = str2time (buf, default_time, default_zone);
      printf ("%s", asctime (gmtime (&t)));
    }
  return 0;
}
#endif
OpenPOWER on IntegriCloud