xref: /netbsd/usr.bin/cal/cal.c (revision 6550d01e)
1 /*	$NetBSD: cal.c,v 1.26 2010/02/03 15:34:45 roy Exp $	*/
2 
3 /*
4  * Copyright (c) 1989, 1993, 1994
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Kim Letkeman.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #include <sys/cdefs.h>
36 #ifndef lint
37 __COPYRIGHT("@(#) Copyright (c) 1989, 1993, 1994\
38  The Regents of the University of California.  All rights reserved.");
39 #endif /* not lint */
40 
41 #ifndef lint
42 #if 0
43 static char sccsid[] = "@(#)cal.c	8.4 (Berkeley) 4/2/94";
44 #else
45 __RCSID("$NetBSD: cal.c,v 1.26 2010/02/03 15:34:45 roy Exp $");
46 #endif
47 #endif /* not lint */
48 
49 #include <sys/types.h>
50 
51 #include <ctype.h>
52 #include <err.h>
53 #include <errno.h>
54 #include <limits.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <term.h>
59 #include <time.h>
60 #include <tzfile.h>
61 #include <unistd.h>
62 
63 #define	SATURDAY 		6		/* 1 Jan 1 was a Saturday */
64 
65 #define	FIRST_MISSING_DAY 	reform->first_missing_day
66 #define	NUMBER_MISSING_DAYS 	reform->missing_days
67 
68 #define	MAXDAYS			42		/* max slots in a month array */
69 #define	SPACE			-1		/* used in day array */
70 
71 static int days_in_month[2][13] = {
72 	{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
73 	{0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
74 };
75 
76 int empty[MAXDAYS] = {
77 	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,
78 	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,
79 	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,
80 	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,
81 	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,
82 	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,	SPACE,
83 };
84 int shift_days[2][4][MAXDAYS + 1];
85 
86 const char *month_names[12] = {
87 	"January", "February", "March", "April", "May", "June",
88 	"July", "August", "September", "October", "November", "December",
89 };
90 
91 const char *day_headings = " S  M Tu  W Th  F  S";
92 const char *j_day_headings = "  S   M  Tu   W  Th   F   S";
93 
94 /* leap years according to the julian calendar */
95 #define j_leap_year(y, m, d) \
96 	(((m) > 2) && \
97 	 !((y) % 4))
98 
99 /* leap years according to the gregorian calendar */
100 #define g_leap_year(y, m, d) \
101 	(((m) > 2) && \
102 	 ((!((y) % 4) && ((y) % 100)) || \
103 	  !((y) % 400)))
104 
105 /* leap year -- account for gregorian reformation at some point */
106 #define	leap_year(yr) \
107 	((yr) <= reform->year ? j_leap_year((yr), 3, 1) : \
108 	g_leap_year((yr), 3, 1))
109 
110 /* number of julian leap days that have passed by a given date */
111 #define j_leap_days(y, m, d) \
112 	((((y) - 1) / 4) + j_leap_year(y, m, d))
113 
114 /* number of gregorian leap days that have passed by a given date */
115 #define g_leap_days(y, m, d) \
116 	((((y) - 1) / 4) - (((y) - 1) / 100) + (((y) - 1) / 400) + \
117 	g_leap_year(y, m, d))
118 
119 /*
120  * Subtracting the gregorian leap day count (for a given date) from
121  * the julian leap day count (for the same date) describes the number
122  * of days from the date before the shift to the next date that
123  * appears in the calendar.  Since we want to know the number of
124  * *missing* days, not the number of days that the shift spans, we
125  * subtract 2.
126  *
127  * Alternately...
128  *
129  * There's a reason they call the Dark ages the Dark Ages.  Part of it
130  * is that we don't have that many records of that period of time.
131  * One of the reasons for this is that a lot of the Dark Ages never
132  * actually took place.  At some point in the first millenium A.D., a
133  * ruler of some power decided that he wanted the number of the year
134  * to be different than what it was, so he changed it to coincide
135  * nicely with some event (a birthday or anniversary, perhaps a
136  * wedding, or maybe a centennial for a largish city).  One of the
137  * side effects of this upon the Gregorian reform is that two Julian
138  * leap years (leap days celebrated during centennial years that are
139  * not quatro-centennial years) were skipped.
140  */
141 #define GREGORIAN_MAGIC 2
142 
143 /* number of centuries since the reform, not inclusive */
144 #define	centuries_since_reform(yr) \
145 	((yr) > reform->year ? ((yr) / 100) - (reform->year / 100) : 0)
146 
147 /* number of centuries since the reform whose modulo of 400 is 0 */
148 #define	quad_centuries_since_reform(yr) \
149 	((yr) > reform->year ? ((yr) / 400) - (reform->year / 400) : 0)
150 
151 /* number of leap years between year 1 and this year, not inclusive */
152 #define	leap_years_since_year_1(yr) \
153 	((yr) / 4 - centuries_since_reform(yr) + quad_centuries_since_reform(yr))
154 
155 struct reform {
156 	const char *country;
157 	int ambiguity, year, month, date;
158 	long first_missing_day;
159 	int missing_days;
160 	/*
161 	 * That's 2 for standard/julian display, 4 for months possibly
162 	 * affected by the Gregorian shift, and MAXDAYS + 1 for the
163 	 * days that get displayed, plus a crib slot.
164 	 */
165 } *reform, reforms[] = {
166 	{ "DEFAULT",		0, 1752,  9,  3, 0, 0 },
167 	{ "Italy",		1, 1582, 10,  5, 0, 0 },
168 	{ "Spain",		1, 1582, 10,  5, 0, 0 },
169 	{ "Portugal",		1, 1582, 10,  5, 0, 0 },
170 	{ "Poland",		1, 1582, 10,  5, 0, 0 },
171 	{ "France",		2, 1582, 12, 10, 0, 0 },
172 	{ "Luxembourg",		2, 1582, 12, 22, 0, 0 },
173 	{ "Netherlands",	2, 1582, 12, 22, 0, 0 },
174 	{ "Bavaria",		0, 1583, 10,  6, 0, 0 },
175 	{ "Austria",		2, 1584,  1,  7, 0, 0 },
176 	{ "Switzerland",	2, 1584,  1, 12, 0, 0 },
177 	{ "Hungary",		0, 1587, 10, 22, 0, 0 },
178 	{ "Germany",		0, 1700,  2, 19, 0, 0 },
179 	{ "Norway",		0, 1700,  2, 19, 0, 0 },
180 	{ "Denmark",		0, 1700,  2, 19, 0, 0 },
181 	{ "Great Britain",	0, 1752,  9,  3, 0, 0 },
182 	{ "England",		0, 1752,  9,  3, 0, 0 },
183 	{ "America",		0, 1752,  9,  3, 0, 0 },
184 	{ "Sweden",		0, 1753,  2, 18, 0, 0 },
185 	{ "Finland",		0, 1753,  2, 18, 0, 0 },
186 	{ "Japan",		0, 1872, 12, 20, 0, 0 },
187 	{ "China",		0, 1911, 11,  7, 0, 0 },
188 	{ "Bulgaria",		0, 1916,  4,  1, 0, 0 },
189 	{ "U.S.S.R.",		0, 1918,  2,  1, 0, 0 },
190 	{ "Serbia",		0, 1919,  1, 19, 0, 0 },
191 	{ "Romania",		0, 1919,  1, 19, 0, 0 },
192 	{ "Greece",		0, 1924,  3, 10, 0, 0 },
193 	{ "Turkey",		0, 1925, 12, 19, 0, 0 },
194 	{ "Egypt",		0, 1928,  9, 18, 0, 0 },
195 	{ NULL,			0,    0,  0,  0, 0, 0 },
196 };
197 
198 int julian;
199 int dow;
200 int hilite;
201 const char *md, *me;
202 
203 void	init_hilite(void);
204 int	getnum(const char *);
205 void	gregorian_reform(const char *);
206 void	reform_day_array(int, int, int *, int *, int *,int *,int *,int *);
207 int	ascii_day(char *, int);
208 void	center(const char *, int, int);
209 void	day_array(int, int, int *);
210 int	day_in_week(int, int, int);
211 int	day_in_year(int, int, int);
212 void	monthrange(int, int, int, int, int);
213 int	main(int, char **);
214 void	trim_trailing_spaces(char *);
215 void	usage(void);
216 
217 int
218 main(int argc, char **argv)
219 {
220 	struct tm *local_time;
221 	time_t now;
222 	int ch, yflag;
223 	long month, year;
224 	int before, after, use_reform;
225 	int yearly = 0;
226 	char *when, *eoi;
227 
228 	before = after = 0;
229 	use_reform = yflag = year = 0;
230 	when = NULL;
231 	while ((ch = getopt(argc, argv, "A:B:d:hjR:ry3")) != -1) {
232 		switch (ch) {
233 		case 'A':
234 			after = getnum(optarg);
235 			if (after < 0)
236 				errx(1, "Argument to -A must be positive");
237 			break;
238 		case 'B':
239 			before = getnum(optarg);
240 			if (before < 0)
241 				errx(1, "Argument to -B must be positive");
242 			break;
243 		case 'd':
244 			dow = getnum(optarg);
245 			if (dow < 0 || dow > 6)
246 				errx(1, "illegal day of week value: use 0-6");
247 			break;
248 		case 'h':
249 			init_hilite();
250 			break;
251 		case 'j':
252 			julian = 1;
253 			break;
254 		case 'R':
255 			when = optarg;
256 			break;
257 		case 'r':
258 			use_reform = 1;
259 			break;
260 		case 'y':
261 			yflag = 1;
262 			break;
263 		case '3':
264 			before = after = 1;
265 			break;
266 		case '?':
267 		default:
268 			usage();
269 			/* NOTREACHED */
270 		}
271 	}
272 
273 	argc -= optind;
274 	argv += optind;
275 
276 	if (when != NULL)
277 		gregorian_reform(when);
278 	if (reform == NULL)
279 		gregorian_reform("DEFAULT");
280 
281 	month = 0;
282 	switch (argc) {
283 	case 2:
284 		month = strtol(*argv++, &eoi, 10);
285 		if (month < 1 || month > 12 || *eoi != '\0')
286 			errx(1, "illegal month value: use 1-12");
287 		year = strtol(*argv, &eoi, 10);
288 		if (year < 1 || year > 9999 || *eoi != '\0')
289 			errx(1, "illegal year value: use 1-9999");
290 		break;
291 	case 1:
292 		year = strtol(*argv, &eoi, 10);
293 		if (year < 1 || year > 9999 || (*eoi != '\0' && *eoi != '/' && *eoi != '-'))
294 			errx(1, "illegal year value: use 1-9999");
295 		if (*eoi != '\0') {
296 			month = strtol(eoi + 1, &eoi, 10);
297 			if (month < 1 || month > 12 || *eoi != '\0')
298 				errx(1, "illegal month value: use 1-12");
299 		}
300 		break;
301 	case 0:
302 		(void)time(&now);
303 		local_time = localtime(&now);
304 		if (use_reform)
305 			year = reform->year;
306 		else
307 			year = local_time->tm_year + TM_YEAR_BASE;
308 		if (!yflag) {
309 			if (use_reform)
310 				month = reform->month;
311 			else
312 				month = local_time->tm_mon + 1;
313 		}
314 		break;
315 	default:
316 		usage();
317 	}
318 
319 	if (!month) {
320 		/* yearly */
321 		month = 1;
322 		before = 0;
323 		after = 11;
324 		yearly = 1;
325 	}
326 
327 	monthrange(month, year, before, after, yearly);
328 
329 	exit(0);
330 }
331 
332 #define	DAY_LEN		3		/* 3 spaces per day */
333 #define	J_DAY_LEN	4		/* 4 spaces per day */
334 #define	WEEK_LEN	20		/* 7 * 3 - one space at the end */
335 #define	J_WEEK_LEN	27		/* 7 * 4 - one space at the end */
336 #define	HEAD_SEP	2		/* spaces between day headings */
337 #define	J_HEAD_SEP	2
338 #define	MONTH_PER_ROW	3		/* how many monthes in a row */
339 #define	J_MONTH_PER_ROW	2
340 
341 void
342 monthrange(int month, int year, int before, int after, int yearly)
343 {
344 	int startmonth, startyear;
345 	int endmonth, endyear;
346 	int i, row;
347 	int days[3][MAXDAYS];
348 	char lineout[256];
349 	int inayear;
350 	int newyear;
351 	int day_len, week_len, head_sep;
352 	int month_per_row;
353 	int skip, r_off, w_off;
354 
355 	if (julian) {
356 		day_len = J_DAY_LEN;
357 		week_len = J_WEEK_LEN;
358 		head_sep = J_HEAD_SEP;
359 		month_per_row = J_MONTH_PER_ROW;
360 	}
361 	else {
362 		day_len = DAY_LEN;
363 		week_len = WEEK_LEN;
364 		head_sep = HEAD_SEP;
365 		month_per_row = MONTH_PER_ROW;
366 	}
367 
368 	month--;
369 
370 	startyear = year - (before + 12 - 1 - month) / 12;
371 	startmonth = 12 - 1 - ((before + 12 - 1 - month) % 12);
372 	endyear = year + (month + after) / 12;
373 	endmonth = (month + after) % 12;
374 
375 	if (startyear < 0 || endyear > 9999) {
376 		errx(1, "year should be in 1-9999\n");
377 	}
378 
379 	year = startyear;
380 	month = startmonth;
381 	inayear = newyear = (year != endyear || yearly);
382 	if (inayear) {
383 		skip = month % month_per_row;
384 		month -= skip;
385 	}
386 	else {
387 		skip = 0;
388 	}
389 
390 	do {
391 		if (newyear) {
392 			(void)snprintf(lineout, sizeof(lineout), "%d", year);
393 			center(lineout, week_len * month_per_row +
394 			    head_sep * (month_per_row - 1), 0);
395 			(void)printf("\n\n");
396 			newyear = 0;
397 		}
398 
399 		for (i = 0; i < skip; i++)
400 			center("", week_len, head_sep);
401 
402 		for (; i < month_per_row; i++) {
403 			int sep;
404 
405 			if (year == endyear && month + i > endmonth)
406 				break;
407 
408 			sep = (i == month_per_row - 1) ? 0 : head_sep;
409 			day_array(month + i + 1, year, days[i]);
410 			if (inayear) {
411 				center(month_names[month + i], week_len, sep);
412 			}
413 			else {
414 				snprintf(lineout, sizeof(lineout), "%s %d",
415 				    month_names[month + i], year);
416 				center(lineout, week_len, sep);
417 			}
418 		}
419 		printf("\n");
420 
421 		for (i = 0; i < skip; i++)
422 			center("", week_len, head_sep);
423 
424 		for (; i < month_per_row; i++) {
425 			int sep;
426 
427 			if (year == endyear && month + i > endmonth)
428 				break;
429 
430 			sep = (i == month_per_row - 1) ? 0 : head_sep;
431 			if (dow) {
432 				printf("%s ", (julian) ?
433 				    j_day_headings + 4 * dow :
434 				    day_headings + 3 * dow);
435 				printf("%.*s", dow * (julian ? 4 : 3) - 1,
436 				       (julian) ? j_day_headings : day_headings);
437 			} else
438 				printf("%s", (julian) ? j_day_headings : day_headings);
439 			printf("%*s", sep, "");
440 		}
441 		printf("\n");
442 
443 		for (row = 0; row < 6; row++) {
444 			char *p = NULL;
445 
446 			memset(lineout, ' ', sizeof(lineout));
447 			for (i = 0; i < skip; i++) {
448 				/* nothing */
449 			}
450 			w_off = 0;
451 			for (; i < month_per_row; i++) {
452 				int col, *dp;
453 
454 				if (year == endyear && month + i > endmonth)
455 					break;
456 
457 				p = lineout + i * (week_len + 2) + w_off;
458 				dp = &days[i][row * 7];
459 				for (col = 0; col < 7;
460 				     col++, p += day_len + r_off) {
461 					r_off = ascii_day(p, *dp++);
462 					w_off += r_off;
463 				}
464 			}
465 			*p = '\0';
466 			trim_trailing_spaces(lineout);
467 			(void)printf("%s\n", lineout);
468 		}
469 
470 		skip = 0;
471 		month += month_per_row;
472 		if (month >= 12) {
473 			month -= 12;
474 			year++;
475 			newyear = 1;
476 		}
477 	} while (year < endyear || (year == endyear && month <= endmonth));
478 }
479 
480 /*
481  * day_array --
482  *	Fill in an array of 42 integers with a calendar.  Assume for a moment
483  *	that you took the (maximum) 6 rows in a calendar and stretched them
484  *	out end to end.  You would have 42 numbers or spaces.  This routine
485  *	builds that array for any month from Jan. 1 through Dec. 9999.
486  */
487 void
488 day_array(int month, int year, int *days)
489 {
490 	int day, dw, dm;
491 	time_t t;
492 	struct tm *tm;
493 
494 	t = time(NULL);
495 	tm = localtime(&t);
496 	tm->tm_year += TM_YEAR_BASE;
497 	tm->tm_mon++;
498 	tm->tm_yday++; /* jan 1 is 1 for us, not 0 */
499 
500 	for (dm = month + year * 12, dw = 0; dw < 4; dw++) {
501 		if (dm == shift_days[julian][dw][MAXDAYS]) {
502 			memmove(days, shift_days[julian][dw],
503 				MAXDAYS * sizeof(int));
504 			return;
505 		}
506 	}
507 
508 	memmove(days, empty, MAXDAYS * sizeof(int));
509 	dm = days_in_month[leap_year(year)][month];
510 	dw = day_in_week(1, month, year);
511 	day = julian ? day_in_year(1, month, year) : 1;
512 	while (dm--) {
513 		if (hilite && year == tm->tm_year &&
514 		    (julian ? (day == tm->tm_yday) :
515 		     (month == tm->tm_mon && day == tm->tm_mday)))
516 			days[dw++] = SPACE - day++;
517 		else
518 			days[dw++] = day++;
519 	}
520 }
521 
522 /*
523  * day_in_year --
524  *	return the 1 based day number within the year
525  */
526 int
527 day_in_year(int day, int month, int year)
528 {
529 	int i, leap;
530 
531 	leap = leap_year(year);
532 	for (i = 1; i < month; i++)
533 		day += days_in_month[leap][i];
534 	return (day);
535 }
536 
537 /*
538  * day_in_week
539  *	return the 0 based day number for any date from 1 Jan. 1 to
540  *	31 Dec. 9999.  Returns the day of the week of the first
541  *	missing day for any given Gregorian shift.
542  */
543 int
544 day_in_week(int day, int month, int year)
545 {
546 	long temp;
547 
548 	temp = (long)(year - 1) * 365 + leap_years_since_year_1(year - 1)
549 	    + day_in_year(day, month, year);
550 	if (temp < FIRST_MISSING_DAY)
551 		return ((temp - dow + 6 + SATURDAY) % 7);
552 	if (temp >= (FIRST_MISSING_DAY + NUMBER_MISSING_DAYS))
553 		return (((temp - dow + 6 + SATURDAY) - NUMBER_MISSING_DAYS) % 7);
554 	return ((FIRST_MISSING_DAY - dow + 6 + SATURDAY) % 7);
555 }
556 
557 int
558 ascii_day(char *p, int day)
559 {
560 	int display, val, rc;
561 	char *b;
562 	static const char *aday[] = {
563 		"",
564 		" 1", " 2", " 3", " 4", " 5", " 6", " 7",
565 		" 8", " 9", "10", "11", "12", "13", "14",
566 		"15", "16", "17", "18", "19", "20", "21",
567 		"22", "23", "24", "25", "26", "27", "28",
568 		"29", "30", "31",
569 	};
570 
571 	if (day == SPACE) {
572 		memset(p, ' ', julian ? J_DAY_LEN : DAY_LEN);
573 		return (0);
574 	}
575 	if (day < SPACE) {
576 		b = p;
577 		day = SPACE - day;
578 	} else
579 		b = NULL;
580 	if (julian) {
581 		if ((val = day / 100) != 0) {
582 			day %= 100;
583 			*p++ = val + '0';
584 			display = 1;
585 		} else {
586 			*p++ = ' ';
587 			display = 0;
588 		}
589 		val = day / 10;
590 		if (val || display)
591 			*p++ = val + '0';
592 		else
593 			*p++ = ' ';
594 		*p++ = day % 10 + '0';
595 	} else {
596 		*p++ = aday[day][0];
597 		*p++ = aday[day][1];
598 	}
599 
600 	rc = 0;
601 	if (b != NULL) {
602 		const char *t;
603 		char h[64];
604 		int l;
605 
606 		l = p - b;
607 		memcpy(h, b, l);
608 		p = b;
609 
610 		if (md != NULL) {
611 			for (t = md; *t; rc++)
612 				*p++ = *t++;
613 			memcpy(p, h, l);
614 			p += l;
615 			for (t = me; *t; rc++)
616 				*p++ = *t++;
617 		} else {
618 			for (t = &h[0]; l--; t++) {
619 				*p++ = *t;
620 				rc++;
621 				*p++ = '\b';
622 				rc++;
623 				*p++ = *t;
624 			}
625 		}
626 	}
627 
628 	*p = ' ';
629 	return (rc);
630 }
631 
632 void
633 trim_trailing_spaces(char *s)
634 {
635 	char *p;
636 
637 	for (p = s; *p; ++p)
638 		continue;
639 	while (p > s && isspace((unsigned char)*--p))
640 		continue;
641 	if (p > s)
642 		++p;
643 	*p = '\0';
644 }
645 
646 void
647 center(const char *str, int len, int separate)
648 {
649 
650 	len -= strlen(str);
651 	(void)printf("%*s%s%*s", len / 2, "", str, len / 2 + len % 2, "");
652 	if (separate)
653 		(void)printf("%*s", separate, "");
654 }
655 
656 /*
657  * gregorian_reform --
658  *	Given a description of date on which the Gregorian Reform was
659  *	applied.  The argument can be any of the "country" names
660  *	listed in the reforms array (case insensitive) or a date of
661  *	the form YYYY/MM/DD.  The date and month can be omitted if
662  *	doing so would not select more than one different built-in
663  *	reform point.
664  */
665 void
666 gregorian_reform(const char *p)
667 {
668 	int year, month, date;
669 	int i, days, diw, diy;
670 	char c;
671 
672 	i = sscanf(p, "%d%*[/,-]%d%*[/,-]%d%c", &year, &month, &date, &c);
673 	switch (i) {
674 	case 4:
675 		/*
676 		 * If the character was sscanf()ed, then there's more
677 		 * stuff than we need.
678 		 */
679 		errx(1, "date specifier %s invalid", p);
680 	case 0:
681 		/*
682 		 * Not a form we can sscanf(), so void these, and we
683 		 * can try matching "country" names later.
684 		 */
685 		year = month = date = -1;
686 		break;
687 	case 1:
688 		month = 0;
689 		/*FALLTHROUGH*/
690 	case 2:
691 		date = 0;
692 		/*FALLTHROUGH*/
693 	    case 3:
694 		/*
695 		 * At last, some sanity checking on the values we were
696 		 * given.
697 		 */
698 		if (year < 1 || year > 9999)
699 			errx(1, "%d: illegal year value: use 1-9999", year);
700 		if (i > 1 && (month < 1 || month > 12))
701 			errx(1, "%d: illegal month value: use 1-12", month);
702 		if ((i == 3 && date < 1) || date < 0 ||
703 		    date > days_in_month[1][month])
704 			/*
705 			 * What about someone specifying a leap day in
706 			 * a non-leap year?  Well...that's a tricky
707 			 * one.  We can't yet *say* whether the year
708 			 * in question is a leap year.  What if the
709 			 * date given was, for example, 1700/2/29?  is
710 			 * that a valid leap day?
711 			 *
712 			 * So...we punt, and hope that saying 29 in
713 			 * the case of February isn't too bad an idea.
714 			 */
715 			errx(1, "%d: illegal date value: use 1-%d", date,
716 			     days_in_month[1][month]);
717 		break;
718 	}
719 
720 	/*
721 	 * A complete date was specified, so use the other pope.
722 	 */
723 	if (date > 0) {
724 		static struct reform Goestheveezl;
725 
726 		reform = &Goestheveezl;
727 		reform->country = "Bompzidaize";
728 		reform->year = year;
729 		reform->month = month;
730 		reform->date = date;
731 	}
732 
733 	/*
734 	 * No date information was specified, so let's try to match on
735 	 * country name.
736 	 */
737 	else if (year == -1) {
738 		for (reform = &reforms[0]; reform->year; reform++) {
739 			if (strcasecmp(p, reform->country) == 0)
740 				break;
741 		}
742 	}
743 
744 	/*
745 	 * We have *some* date information, but not a complete date.
746 	 * Let's see if we have enough to pick a single entry from the
747 	 * list that's not ambiguous.
748 	 */
749 	else {
750 		for (reform = &reforms[0]; reform->year; reform++) {
751 			if ((year == 0 || year == reform->year) &&
752 			    (month == 0 || month == reform->month) &&
753 			    (date == 0 || month == reform->date))
754 				break;
755 		}
756 
757 		if (i <= reform->ambiguity)
758 			errx(1, "%s: ambiguous short reform date specification", p);
759 	}
760 
761 	/*
762 	 * Oops...we reached the end of the list.
763 	 */
764 	if (reform->year == 0)
765 		errx(1, "reform name %s invalid", p);
766 
767 	/*
768 	 *
769 	 */
770 	reform->missing_days =
771 		j_leap_days(reform->year, reform->month, reform->date) -
772 		g_leap_days(reform->year, reform->month, reform->date) -
773 		GREGORIAN_MAGIC;
774 
775 	reform->first_missing_day =
776 		(reform->year - 1) * 365 +
777 		day_in_year(reform->date, reform->month, reform->year) +
778 		date +
779 		j_leap_days(reform->year, reform->month, reform->date);
780 
781 	/*
782 	 * Once we know the day of the week of the first missing day,
783 	 * skip back to the first of the month's day of the week.
784 	 */
785 	diw = day_in_week(reform->date, reform->month, reform->year);
786 	diw = (diw + 8 - (reform->date % 7)) % 7;
787 	diy = day_in_year(1, reform->month, reform->year);
788 
789 	/*
790 	 * We might need all four of these (if you switch from Julian
791 	 * to Gregorian at some point after 9900, you get a gap of 73
792 	 * days, and that can affect four months), and it doesn't hurt
793 	 * all that much to precompute them, so there.
794 	 */
795 	date = 1;
796 	days = 0;
797 	for (i = 0; i < 4; i++)
798 		reform_day_array(reform->month + i, reform->year,
799 				 &days, &date, &diw, &diy,
800 				 shift_days[0][i],
801 				 shift_days[1][i]);
802 }
803 
804 /*
805  * reform_day_array --
806  *	Pre-calculates the given month's calendar (in both "standard"
807  *	and "julian day" representations) with respect for days
808  *	skipped during a reform period.
809  */
810 void
811 reform_day_array(int month, int year, int *done, int *date, int *diw, int *diy,
812 	int *scal, int *jcal)
813 {
814 	int mdays;
815 
816 	/*
817 	 * If the reform was in the month of october or later, then
818 	 * the month number from the caller could "overflow".
819 	 */
820 	if (month > 12) {
821 		month -= 12;
822 		year++;
823 	}
824 
825 	/*
826 	 * Erase months, and set crib number.  The crib number is used
827 	 * later to determine if the month to be displayed is here or
828 	 * should be built on the fly with the generic routine
829 	 */
830 	memmove(scal, empty, MAXDAYS * sizeof(int));
831 	scal[MAXDAYS] = month + year * 12;
832 	memmove(jcal, empty, MAXDAYS * sizeof(int));
833 	jcal[MAXDAYS] = month + year * 12;
834 
835 	/*
836 	 * It doesn't matter what the actual month is when figuring
837 	 * out if this is a leap year or not, just so long as February
838 	 * gets the right number of days in it.
839 	 */
840 	mdays = days_in_month[g_leap_year(year, 3, 1)][month];
841 
842 	/*
843 	 * Bounce back to the first "row" in the day array, and fill
844 	 * in any days that actually occur.
845 	 */
846 	for (*diw %= 7; (*date - *done) <= mdays; (*date)++, (*diy)++) {
847 		/*
848 		 * "date" doesn't get reset by the caller across calls
849 		 * to this routine, so we can actually tell that we're
850 		 * looking at April the 41st.  Much easier than trying
851 		 * to calculate the absolute julian day for a given
852 		 * date and then checking that.
853 		 */
854 		if (*date < reform->date ||
855 		    *date >= reform->date + reform->missing_days) {
856 			scal[*diw] = *date - *done;
857 			jcal[*diw] = *diy;
858 			(*diw)++;
859 		}
860 	}
861 	*done += mdays;
862 }
863 
864 int
865 getnum(const char *p)
866 {
867 	unsigned long result;
868 	char *ep;
869 
870 	errno = 0;
871 	result = strtoul(p, &ep, 10);
872 	if (p[0] == '\0' || *ep != '\0')
873 		goto error;
874 	if (errno == ERANGE && result == ULONG_MAX)
875 		goto error;
876 	if (result > INT_MAX)
877 		goto error;
878 
879 	return (int)result;
880 
881 error:
882 	errx(1, "bad number: %s", p);
883 	/*NOTREACHED*/
884 }
885 
886 void
887 init_hilite(void)
888 {
889 	const char *term;
890 	int errret;
891 
892 	hilite++;
893 
894 	if (!isatty(fileno(stdout)))
895 		return;
896 
897 	term = getenv("TERM");
898 	if (term == NULL)
899 		term = "dumb";
900 	if (setupterm(term, fileno(stdout), &errret) != 0 && errret != 1)
901 		return;
902 
903 	if (hilite > 1)
904 		md = enter_reverse_mode;
905 	else
906 		md = enter_bold_mode;
907 	me = exit_attribute_mode;
908 	if (me == NULL || md == NULL)
909 		md = me = NULL;
910 }
911 
912 void
913 usage(void)
914 {
915 
916 	(void)fprintf(stderr,
917 	    "usage: cal [-3hjry] [-A after] [-B before] [-d day-of-week] "
918 	    "[-R reform-spec]\n           [[month] year]\n");
919 	exit(1);
920 }
921