xref: /minix3/usr.bin/cal/cal.c (revision 0b98e8aad89f2bd4ba80b523d73cf29e9dd82ce1)
1 /*	$NetBSD: cal.c,v 1.27 2011/08/29 13:55:22 joerg 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 1.27 2011/08/29 13:55:22 joerg 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 static 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 static int shift_days[2][4][MAXDAYS + 1];
85 
86 static const char *month_names[12] = {
87 	"January", "February", "March", "April", "May", "June",
88 	"July", "August", "September", "October", "November", "December",
89 };
90 
91 static const char *day_headings = " S  M Tu  W Th  F  S";
92 static 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 static 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 static int julian;
199 static int dow;
200 static int hilite;
201 static const char *md, *me;
202 
203 static void	init_hilite(void);
204 static int	getnum(const char *);
205 static void	gregorian_reform(const char *);
206 static void	reform_day_array(int, int, int *, int *, int *,int *,int *,int *);
207 static int	ascii_day(char *, int);
208 static void	center(const char *, int, int);
209 static void	day_array(int, int, int *);
210 static int	day_in_week(int, int, int);
211 static int	day_in_year(int, int, int);
212 static void	monthrange(int, int, int, int, int);
213 static void	trim_trailing_spaces(char *);
214 __dead static void	usage(void);
215 
216 int
217 main(int argc, char **argv)
218 {
219 	struct tm *local_time;
220 	time_t now;
221 	int ch, yflag;
222 	long month, year;
223 	int before, after, use_reform;
224 	int yearly = 0;
225 	char *when, *eoi;
226 
227 	before = after = 0;
228 	use_reform = yflag = year = 0;
229 	when = NULL;
230 	while ((ch = getopt(argc, argv, "A:B:d:hjR:ry3")) != -1) {
231 		switch (ch) {
232 		case 'A':
233 			after = getnum(optarg);
234 			if (after < 0)
235 				errx(1, "Argument to -A must be positive");
236 			break;
237 		case 'B':
238 			before = getnum(optarg);
239 			if (before < 0)
240 				errx(1, "Argument to -B must be positive");
241 			break;
242 		case 'd':
243 			dow = getnum(optarg);
244 			if (dow < 0 || dow > 6)
245 				errx(1, "illegal day of week value: use 0-6");
246 			break;
247 		case 'h':
248 			init_hilite();
249 			break;
250 		case 'j':
251 			julian = 1;
252 			break;
253 		case 'R':
254 			when = optarg;
255 			break;
256 		case 'r':
257 			use_reform = 1;
258 			break;
259 		case 'y':
260 			yflag = 1;
261 			break;
262 		case '3':
263 			before = after = 1;
264 			break;
265 		case '?':
266 		default:
267 			usage();
268 			/* NOTREACHED */
269 		}
270 	}
271 
272 	argc -= optind;
273 	argv += optind;
274 
275 	if (when != NULL)
276 		gregorian_reform(when);
277 	if (reform == NULL)
278 		gregorian_reform("DEFAULT");
279 
280 	month = 0;
281 	switch (argc) {
282 	case 2:
283 		month = strtol(*argv++, &eoi, 10);
284 		if (month < 1 || month > 12 || *eoi != '\0')
285 			errx(1, "illegal month value: use 1-12");
286 		year = strtol(*argv, &eoi, 10);
287 		if (year < 1 || year > 9999 || *eoi != '\0')
288 			errx(1, "illegal year value: use 1-9999");
289 		break;
290 	case 1:
291 		year = strtol(*argv, &eoi, 10);
292 		if (year < 1 || year > 9999 || (*eoi != '\0' && *eoi != '/' && *eoi != '-'))
293 			errx(1, "illegal year value: use 1-9999");
294 		if (*eoi != '\0') {
295 			month = strtol(eoi + 1, &eoi, 10);
296 			if (month < 1 || month > 12 || *eoi != '\0')
297 				errx(1, "illegal month value: use 1-12");
298 		}
299 		break;
300 	case 0:
301 		(void)time(&now);
302 		local_time = localtime(&now);
303 		if (use_reform)
304 			year = reform->year;
305 		else
306 			year = local_time->tm_year + TM_YEAR_BASE;
307 		if (!yflag) {
308 			if (use_reform)
309 				month = reform->month;
310 			else
311 				month = local_time->tm_mon + 1;
312 		}
313 		break;
314 	default:
315 		usage();
316 	}
317 
318 	if (!month) {
319 		/* yearly */
320 		month = 1;
321 		before = 0;
322 		after = 11;
323 		yearly = 1;
324 	}
325 
326 	monthrange(month, year, before, after, yearly);
327 
328 	exit(0);
329 }
330 
331 #define	DAY_LEN		3		/* 3 spaces per day */
332 #define	J_DAY_LEN	4		/* 4 spaces per day */
333 #define	WEEK_LEN	20		/* 7 * 3 - one space at the end */
334 #define	J_WEEK_LEN	27		/* 7 * 4 - one space at the end */
335 #define	HEAD_SEP	2		/* spaces between day headings */
336 #define	J_HEAD_SEP	2
337 #define	MONTH_PER_ROW	3		/* how many monthes in a row */
338 #define	J_MONTH_PER_ROW	2
339 
340 static void
341 monthrange(int month, int year, int before, int after, int yearly)
342 {
343 	int startmonth, startyear;
344 	int endmonth, endyear;
345 	int i, row;
346 	int days[3][MAXDAYS];
347 	char lineout[256];
348 	int inayear;
349 	int newyear;
350 	int day_len, week_len, head_sep;
351 	int month_per_row;
352 	int skip, r_off, w_off;
353 
354 	if (julian) {
355 		day_len = J_DAY_LEN;
356 		week_len = J_WEEK_LEN;
357 		head_sep = J_HEAD_SEP;
358 		month_per_row = J_MONTH_PER_ROW;
359 	}
360 	else {
361 		day_len = DAY_LEN;
362 		week_len = WEEK_LEN;
363 		head_sep = HEAD_SEP;
364 		month_per_row = MONTH_PER_ROW;
365 	}
366 
367 	month--;
368 
369 	startyear = year - (before + 12 - 1 - month) / 12;
370 	startmonth = 12 - 1 - ((before + 12 - 1 - month) % 12);
371 	endyear = year + (month + after) / 12;
372 	endmonth = (month + after) % 12;
373 
374 	if (startyear < 0 || endyear > 9999) {
375 		errx(1, "year should be in 1-9999\n");
376 	}
377 
378 	year = startyear;
379 	month = startmonth;
380 	inayear = newyear = (year != endyear || yearly);
381 	if (inayear) {
382 		skip = month % month_per_row;
383 		month -= skip;
384 	}
385 	else {
386 		skip = 0;
387 	}
388 
389 	do {
390 		if (newyear) {
391 			(void)snprintf(lineout, sizeof(lineout), "%d", year);
392 			center(lineout, week_len * month_per_row +
393 			    head_sep * (month_per_row - 1), 0);
394 			(void)printf("\n\n");
395 			newyear = 0;
396 		}
397 
398 		for (i = 0; i < skip; i++)
399 			center("", week_len, head_sep);
400 
401 		for (; i < month_per_row; i++) {
402 			int sep;
403 
404 			if (year == endyear && month + i > endmonth)
405 				break;
406 
407 			sep = (i == month_per_row - 1) ? 0 : head_sep;
408 			day_array(month + i + 1, year, days[i]);
409 			if (inayear) {
410 				center(month_names[month + i], week_len, sep);
411 			}
412 			else {
413 				snprintf(lineout, sizeof(lineout), "%s %d",
414 				    month_names[month + i], year);
415 				center(lineout, week_len, sep);
416 			}
417 		}
418 		printf("\n");
419 
420 		for (i = 0; i < skip; i++)
421 			center("", week_len, head_sep);
422 
423 		for (; i < month_per_row; i++) {
424 			int sep;
425 
426 			if (year == endyear && month + i > endmonth)
427 				break;
428 
429 			sep = (i == month_per_row - 1) ? 0 : head_sep;
430 			if (dow) {
431 				printf("%s ", (julian) ?
432 				    j_day_headings + 4 * dow :
433 				    day_headings + 3 * dow);
434 				printf("%.*s", dow * (julian ? 4 : 3) - 1,
435 				       (julian) ? j_day_headings : day_headings);
436 			} else
437 				printf("%s", (julian) ? j_day_headings : day_headings);
438 			printf("%*s", sep, "");
439 		}
440 		printf("\n");
441 
442 		for (row = 0; row < 6; row++) {
443 			char *p = NULL;
444 
445 			memset(lineout, ' ', sizeof(lineout));
446 			for (i = 0; i < skip; i++) {
447 				/* nothing */
448 			}
449 			w_off = 0;
450 			for (; i < month_per_row; i++) {
451 				int col, *dp;
452 
453 				if (year == endyear && month + i > endmonth)
454 					break;
455 
456 				p = lineout + i * (week_len + 2) + w_off;
457 				dp = &days[i][row * 7];
458 				for (col = 0; col < 7;
459 				     col++, p += day_len + r_off) {
460 					r_off = ascii_day(p, *dp++);
461 					w_off += r_off;
462 				}
463 			}
464 			*p = '\0';
465 			trim_trailing_spaces(lineout);
466 			(void)printf("%s\n", lineout);
467 		}
468 
469 		skip = 0;
470 		month += month_per_row;
471 		if (month >= 12) {
472 			month -= 12;
473 			year++;
474 			newyear = 1;
475 		}
476 	} while (year < endyear || (year == endyear && month <= endmonth));
477 }
478 
479 /*
480  * day_array --
481  *	Fill in an array of 42 integers with a calendar.  Assume for a moment
482  *	that you took the (maximum) 6 rows in a calendar and stretched them
483  *	out end to end.  You would have 42 numbers or spaces.  This routine
484  *	builds that array for any month from Jan. 1 through Dec. 9999.
485  */
486 static void
487 day_array(int month, int year, int *days)
488 {
489 	int day, dw, dm;
490 	time_t t;
491 	struct tm *tm;
492 
493 	t = time(NULL);
494 	tm = localtime(&t);
495 	tm->tm_year += TM_YEAR_BASE;
496 	tm->tm_mon++;
497 	tm->tm_yday++; /* jan 1 is 1 for us, not 0 */
498 
499 	for (dm = month + year * 12, dw = 0; dw < 4; dw++) {
500 		if (dm == shift_days[julian][dw][MAXDAYS]) {
501 			memmove(days, shift_days[julian][dw],
502 				MAXDAYS * sizeof(int));
503 			return;
504 		}
505 	}
506 
507 	memmove(days, empty, MAXDAYS * sizeof(int));
508 	dm = days_in_month[leap_year(year)][month];
509 	dw = day_in_week(1, month, year);
510 	day = julian ? day_in_year(1, month, year) : 1;
511 	while (dm--) {
512 		if (hilite && year == tm->tm_year &&
513 		    (julian ? (day == tm->tm_yday) :
514 		     (month == tm->tm_mon && day == tm->tm_mday)))
515 			days[dw++] = SPACE - day++;
516 		else
517 			days[dw++] = day++;
518 	}
519 }
520 
521 /*
522  * day_in_year --
523  *	return the 1 based day number within the year
524  */
525 static int
526 day_in_year(int day, int month, int year)
527 {
528 	int i, leap;
529 
530 	leap = leap_year(year);
531 	for (i = 1; i < month; i++)
532 		day += days_in_month[leap][i];
533 	return (day);
534 }
535 
536 /*
537  * day_in_week
538  *	return the 0 based day number for any date from 1 Jan. 1 to
539  *	31 Dec. 9999.  Returns the day of the week of the first
540  *	missing day for any given Gregorian shift.
541  */
542 static int
543 day_in_week(int day, int month, int year)
544 {
545 	long temp;
546 
547 	temp = (long)(year - 1) * 365 + leap_years_since_year_1(year - 1)
548 	    + day_in_year(day, month, year);
549 	if (temp < FIRST_MISSING_DAY)
550 		return ((temp - dow + 6 + SATURDAY) % 7);
551 	if (temp >= (FIRST_MISSING_DAY + NUMBER_MISSING_DAYS))
552 		return (((temp - dow + 6 + SATURDAY) - NUMBER_MISSING_DAYS) % 7);
553 	return ((FIRST_MISSING_DAY - dow + 6 + SATURDAY) % 7);
554 }
555 
556 static int
557 ascii_day(char *p, int day)
558 {
559 	int display, val, rc;
560 	char *b;
561 	static const char *aday[] = {
562 		"",
563 		" 1", " 2", " 3", " 4", " 5", " 6", " 7",
564 		" 8", " 9", "10", "11", "12", "13", "14",
565 		"15", "16", "17", "18", "19", "20", "21",
566 		"22", "23", "24", "25", "26", "27", "28",
567 		"29", "30", "31",
568 	};
569 
570 	if (day == SPACE) {
571 		memset(p, ' ', julian ? J_DAY_LEN : DAY_LEN);
572 		return (0);
573 	}
574 	if (day < SPACE) {
575 		b = p;
576 		day = SPACE - day;
577 	} else
578 		b = NULL;
579 	if (julian) {
580 		if ((val = day / 100) != 0) {
581 			day %= 100;
582 			*p++ = val + '0';
583 			display = 1;
584 		} else {
585 			*p++ = ' ';
586 			display = 0;
587 		}
588 		val = day / 10;
589 		if (val || display)
590 			*p++ = val + '0';
591 		else
592 			*p++ = ' ';
593 		*p++ = day % 10 + '0';
594 	} else {
595 		*p++ = aday[day][0];
596 		*p++ = aday[day][1];
597 	}
598 
599 	rc = 0;
600 	if (b != NULL) {
601 		const char *t;
602 		char h[64];
603 		int l;
604 
605 		l = p - b;
606 		memcpy(h, b, l);
607 		p = b;
608 
609 		if (md != NULL) {
610 			for (t = md; *t; rc++)
611 				*p++ = *t++;
612 			memcpy(p, h, l);
613 			p += l;
614 			for (t = me; *t; rc++)
615 				*p++ = *t++;
616 		} else {
617 			for (t = &h[0]; l--; t++) {
618 				*p++ = *t;
619 				rc++;
620 				*p++ = '\b';
621 				rc++;
622 				*p++ = *t;
623 			}
624 		}
625 	}
626 
627 	*p = ' ';
628 	return (rc);
629 }
630 
631 static void
632 trim_trailing_spaces(char *s)
633 {
634 	char *p;
635 
636 	for (p = s; *p; ++p)
637 		continue;
638 	while (p > s && isspace((unsigned char)*--p))
639 		continue;
640 	if (p > s)
641 		++p;
642 	*p = '\0';
643 }
644 
645 static void
646 center(const char *str, int len, int separate)
647 {
648 
649 	len -= strlen(str);
650 	(void)printf("%*s%s%*s", len / 2, "", str, len / 2 + len % 2, "");
651 	if (separate)
652 		(void)printf("%*s", separate, "");
653 }
654 
655 /*
656  * gregorian_reform --
657  *	Given a description of date on which the Gregorian Reform was
658  *	applied.  The argument can be any of the "country" names
659  *	listed in the reforms array (case insensitive) or a date of
660  *	the form YYYY/MM/DD.  The date and month can be omitted if
661  *	doing so would not select more than one different built-in
662  *	reform point.
663  */
664 static void
665 gregorian_reform(const char *p)
666 {
667 	int year, month, date;
668 	int i, days, diw, diy;
669 	char c;
670 
671 	i = sscanf(p, "%d%*[/,-]%d%*[/,-]%d%c", &year, &month, &date, &c);
672 	switch (i) {
673 	case 4:
674 		/*
675 		 * If the character was sscanf()ed, then there's more
676 		 * stuff than we need.
677 		 */
678 		errx(1, "date specifier %s invalid", p);
679 	case 0:
680 		/*
681 		 * Not a form we can sscanf(), so void these, and we
682 		 * can try matching "country" names later.
683 		 */
684 		year = month = date = -1;
685 		break;
686 	case 1:
687 		month = 0;
688 		/*FALLTHROUGH*/
689 	case 2:
690 		date = 0;
691 		/*FALLTHROUGH*/
692 	    case 3:
693 		/*
694 		 * At last, some sanity checking on the values we were
695 		 * given.
696 		 */
697 		if (year < 1 || year > 9999)
698 			errx(1, "%d: illegal year value: use 1-9999", year);
699 		if (i > 1 && (month < 1 || month > 12))
700 			errx(1, "%d: illegal month value: use 1-12", month);
701 		if ((i == 3 && date < 1) || date < 0 ||
702 		    date > days_in_month[1][month])
703 			/*
704 			 * What about someone specifying a leap day in
705 			 * a non-leap year?  Well...that's a tricky
706 			 * one.  We can't yet *say* whether the year
707 			 * in question is a leap year.  What if the
708 			 * date given was, for example, 1700/2/29?  is
709 			 * that a valid leap day?
710 			 *
711 			 * So...we punt, and hope that saying 29 in
712 			 * the case of February isn't too bad an idea.
713 			 */
714 			errx(1, "%d: illegal date value: use 1-%d", date,
715 			     days_in_month[1][month]);
716 		break;
717 	}
718 
719 	/*
720 	 * A complete date was specified, so use the other pope.
721 	 */
722 	if (date > 0) {
723 		static struct reform Goestheveezl;
724 
725 		reform = &Goestheveezl;
726 		reform->country = "Bompzidaize";
727 		reform->year = year;
728 		reform->month = month;
729 		reform->date = date;
730 	}
731 
732 	/*
733 	 * No date information was specified, so let's try to match on
734 	 * country name.
735 	 */
736 	else if (year == -1) {
737 		for (reform = &reforms[0]; reform->year; reform++) {
738 			if (strcasecmp(p, reform->country) == 0)
739 				break;
740 		}
741 	}
742 
743 	/*
744 	 * We have *some* date information, but not a complete date.
745 	 * Let's see if we have enough to pick a single entry from the
746 	 * list that's not ambiguous.
747 	 */
748 	else {
749 		for (reform = &reforms[0]; reform->year; reform++) {
750 			if ((year == 0 || year == reform->year) &&
751 			    (month == 0 || month == reform->month) &&
752 			    (date == 0 || month == reform->date))
753 				break;
754 		}
755 
756 		if (i <= reform->ambiguity)
757 			errx(1, "%s: ambiguous short reform date specification", p);
758 	}
759 
760 	/*
761 	 * Oops...we reached the end of the list.
762 	 */
763 	if (reform->year == 0)
764 		errx(1, "reform name %s invalid", p);
765 
766 	/*
767 	 *
768 	 */
769 	reform->missing_days =
770 		j_leap_days(reform->year, reform->month, reform->date) -
771 		g_leap_days(reform->year, reform->month, reform->date) -
772 		GREGORIAN_MAGIC;
773 
774 	reform->first_missing_day =
775 		(reform->year - 1) * 365 +
776 		day_in_year(reform->date, reform->month, reform->year) +
777 		date +
778 		j_leap_days(reform->year, reform->month, reform->date);
779 
780 	/*
781 	 * Once we know the day of the week of the first missing day,
782 	 * skip back to the first of the month's day of the week.
783 	 */
784 	diw = day_in_week(reform->date, reform->month, reform->year);
785 	diw = (diw + 8 - (reform->date % 7)) % 7;
786 	diy = day_in_year(1, reform->month, reform->year);
787 
788 	/*
789 	 * We might need all four of these (if you switch from Julian
790 	 * to Gregorian at some point after 9900, you get a gap of 73
791 	 * days, and that can affect four months), and it doesn't hurt
792 	 * all that much to precompute them, so there.
793 	 */
794 	date = 1;
795 	days = 0;
796 	for (i = 0; i < 4; i++)
797 		reform_day_array(reform->month + i, reform->year,
798 				 &days, &date, &diw, &diy,
799 				 shift_days[0][i],
800 				 shift_days[1][i]);
801 }
802 
803 /*
804  * reform_day_array --
805  *	Pre-calculates the given month's calendar (in both "standard"
806  *	and "julian day" representations) with respect for days
807  *	skipped during a reform period.
808  */
809 static void
810 reform_day_array(int month, int year, int *done, int *date, int *diw, int *diy,
811 	int *scal, int *jcal)
812 {
813 	int mdays;
814 
815 	/*
816 	 * If the reform was in the month of october or later, then
817 	 * the month number from the caller could "overflow".
818 	 */
819 	if (month > 12) {
820 		month -= 12;
821 		year++;
822 	}
823 
824 	/*
825 	 * Erase months, and set crib number.  The crib number is used
826 	 * later to determine if the month to be displayed is here or
827 	 * should be built on the fly with the generic routine
828 	 */
829 	memmove(scal, empty, MAXDAYS * sizeof(int));
830 	scal[MAXDAYS] = month + year * 12;
831 	memmove(jcal, empty, MAXDAYS * sizeof(int));
832 	jcal[MAXDAYS] = month + year * 12;
833 
834 	/*
835 	 * It doesn't matter what the actual month is when figuring
836 	 * out if this is a leap year or not, just so long as February
837 	 * gets the right number of days in it.
838 	 */
839 	mdays = days_in_month[g_leap_year(year, 3, 1)][month];
840 
841 	/*
842 	 * Bounce back to the first "row" in the day array, and fill
843 	 * in any days that actually occur.
844 	 */
845 	for (*diw %= 7; (*date - *done) <= mdays; (*date)++, (*diy)++) {
846 		/*
847 		 * "date" doesn't get reset by the caller across calls
848 		 * to this routine, so we can actually tell that we're
849 		 * looking at April the 41st.  Much easier than trying
850 		 * to calculate the absolute julian day for a given
851 		 * date and then checking that.
852 		 */
853 		if (*date < reform->date ||
854 		    *date >= reform->date + reform->missing_days) {
855 			scal[*diw] = *date - *done;
856 			jcal[*diw] = *diy;
857 			(*diw)++;
858 		}
859 	}
860 	*done += mdays;
861 }
862 
863 static int
864 getnum(const char *p)
865 {
866 	unsigned long result;
867 	char *ep;
868 
869 	errno = 0;
870 	result = strtoul(p, &ep, 10);
871 	if (p[0] == '\0' || *ep != '\0')
872 		goto error;
873 	if (errno == ERANGE && result == ULONG_MAX)
874 		goto error;
875 	if (result > INT_MAX)
876 		goto error;
877 
878 	return (int)result;
879 
880 error:
881 	errx(1, "bad number: %s", p);
882 	/*NOTREACHED*/
883 }
884 
885 static void
886 init_hilite(void)
887 {
888 	const char *term;
889 	int errret;
890 
891 	hilite++;
892 
893 	if (!isatty(fileno(stdout)))
894 		return;
895 
896 	term = getenv("TERM");
897 	if (term == NULL)
898 		term = "dumb";
899 	if (setupterm(term, fileno(stdout), &errret) != 0 && errret != 1)
900 		return;
901 
902 	if (hilite > 1)
903 		md = enter_reverse_mode;
904 	else
905 		md = enter_bold_mode;
906 	me = exit_attribute_mode;
907 	if (me == NULL || md == NULL)
908 		md = me = NULL;
909 }
910 
911 static void
912 usage(void)
913 {
914 
915 	(void)fprintf(stderr,
916 	    "usage: cal [-3hjry] [-A after] [-B before] [-d day-of-week] "
917 	    "[-R reform-spec]\n           [[month] year]\n");
918 	exit(1);
919 }
920