xref: /freebsd/usr.bin/ncal/ncal.c (revision 9336e0699bda8a301cd2bfa37106b6ec5e32012e)
1 /*-
2  * Copyright (c) 1997 Wolfgang Helbig
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #ifndef lint
28 static const char rcsid[] =
29   "$FreeBSD$";
30 #endif /* not lint */
31 
32 #include <calendar.h>
33 #include <ctype.h>
34 #include <err.h>
35 #include <langinfo.h>
36 #include <locale.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <sysexits.h>
41 #include <time.h>
42 #include <unistd.h>
43 
44 /* Width of one month with backward compatibility */
45 #define MONTH_WIDTH_B_J 27
46 #define MONTH_WIDTH_B 20
47 
48 #define MONTH_WIDTH_J 24
49 #define MONTH_WIDTH 18
50 
51 #define MAX_WIDTH 28
52 
53 typedef struct date date;
54 
55 struct monthlines {
56 	char name[MAX_WIDTH + 1];
57 	char lines[7][MAX_WIDTH + 1];
58 	char weeks[MAX_WIDTH + 1];
59 };
60 
61 struct weekdays {
62 	char names[7][4];
63 };
64 
65 /* The switches from Julian to Gregorian in some countries */
66 static struct djswitch {
67 	const char *cc;	/* Country code according to ISO 3166 */
68 	const char *nm;	/* Name of country */
69 	date dt;	/* Last day of Julian calendar */
70 } switches[] = {
71 	{"AL", "Albania",       {1912, 11, 30}},
72 	{"AT", "Austria",       {1583, 10,  5}},
73 	{"AU", "Australia",     {1752,  9,  2}},
74 	{"BE", "Belgium",       {1582, 12, 14}},
75 	{"BG", "Bulgaria",      {1916,  3, 18}},
76 	{"CA", "Canada",        {1752,  9,  2}},
77 	{"CH", "Switzerland",   {1655,  2, 28}},
78 	{"CN", "China",         {1911, 12, 18}},
79 	{"CZ", "Czech Republic",{1584,  1,  6}},
80 	{"DE", "Germany",       {1700,  2, 18}},
81 	{"DK", "Denmark",       {1700,  2, 18}},
82 	{"ES", "Spain",         {1582, 10,  4}},
83 	{"FI", "Finland",       {1753,  2, 17}},
84 	{"FR", "France",        {1582, 12,  9}},
85 	{"GB", "United Kingdom",{1752,  9,  2}},
86 	{"GR", "Greece",        {1924,  3,  9}},
87 	{"HU", "Hungary",       {1587, 10, 21}},
88 	{"IS", "Iceland",       {1700, 11, 16}},
89 	{"IT", "Italy",         {1582, 10,  4}},
90 	{"JP", "Japan",         {1918, 12, 18}},
91 	{"LI", "Lithuania",     {1918,  2,  1}},
92 	{"LN", "Latin",         {9999, 05, 31}},
93 	{"LU", "Luxembourg",    {1582, 12, 14}},
94 	{"LV", "Latvia",        {1918,  2,  1}},
95 	{"NL", "Netherlands",   {1582, 12, 14}},
96 	{"NO", "Norway",        {1700,  2, 18}},
97 	{"PL", "Poland",        {1582, 10,  4}},
98 	{"PT", "Portugal",      {1582, 10,  4}},
99 	{"RO", "Romania",       {1919,  3, 31}},
100 	{"RU", "Russia",        {1918,  1, 31}},
101 	{"SI", "Slovenia",      {1919,  3,  4}},
102 	{"SW", "Sweden",        {1753,  2, 17}},
103 	{"TR", "Turkey",        {1926, 12, 18}},
104 	{"US", "United States", {1752,  9,  2}},
105 	{"YU", "Yugoslavia",    {1919,  3,  4}}
106 };
107 
108 struct djswitch *dftswitch =
109     switches + sizeof(switches) / sizeof(struct djswitch) - 2;
110     /* default switch (should be "US") */
111 
112 /* Table used to print day of month and week numbers */
113 char daystr[] = "     1  2  3  4  5  6  7  8  9 10 11 12 13 14 15"
114 		" 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31"
115 		" 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47"
116 		" 48 49 50 51 52 53";
117 
118 /* Table used to print day of year and week numbers */
119 char jdaystr[] = "       1   2   3   4   5   6   7   8   9"
120 		 "  10  11  12  13  14  15  16  17  18  19"
121 		 "  20  21  22  23  24  25  26  27  28  29"
122 		 "  30  31  32  33  34  35  36  37  38  39"
123 		 "  40  41  42  43  44  45  46  47  48  49"
124 		 "  50  51  52  53  54  55  56  57  58  59"
125 		 "  60  61  62  63  64  65  66  67  68  69"
126 		 "  70  71  72  73  74  75  76  77  78  79"
127 		 "  80  81  82  83  84  85  86  87  88  89"
128 		 "  90  91  92  93  94  95  96  97  98  99"
129 		 " 100 101 102 103 104 105 106 107 108 109"
130 		 " 110 111 112 113 114 115 116 117 118 119"
131 		 " 120 121 122 123 124 125 126 127 128 129"
132 		 " 130 131 132 133 134 135 136 137 138 139"
133 		 " 140 141 142 143 144 145 146 147 148 149"
134 		 " 150 151 152 153 154 155 156 157 158 159"
135 		 " 160 161 162 163 164 165 166 167 168 169"
136 		 " 170 171 172 173 174 175 176 177 178 179"
137 		 " 180 181 182 183 184 185 186 187 188 189"
138 		 " 190 191 192 193 194 195 196 197 198 199"
139 		 " 200 201 202 203 204 205 206 207 208 209"
140 		 " 210 211 212 213 214 215 216 217 218 219"
141 		 " 220 221 222 223 224 225 226 227 228 229"
142 		 " 230 231 232 233 234 235 236 237 238 239"
143 		 " 240 241 242 243 244 245 246 247 248 249"
144 		 " 250 251 252 253 254 255 256 257 258 259"
145 		 " 260 261 262 263 264 265 266 267 268 269"
146 		 " 270 271 272 273 274 275 276 277 278 279"
147 		 " 280 281 282 283 284 285 286 287 288 289"
148 		 " 290 291 292 293 294 295 296 297 298 299"
149 		 " 300 301 302 303 304 305 306 307 308 309"
150 		 " 310 311 312 313 314 315 316 317 318 319"
151 		 " 320 321 322 323 324 325 326 327 328 329"
152 		 " 330 331 332 333 334 335 336 337 338 339"
153 		 " 340 341 342 343 344 345 346 347 348 349"
154 		 " 350 351 352 353 354 355 356 357 358 359"
155 		 " 360 361 362 363 364 365 366";
156 
157 int     flag_weeks;		/* user wants number of week */
158 int     nswitch;		/* user defined switch date */
159 int	nswitchb;		/* switch date for backward compatibility */
160 
161 char   *center(char *s, char *t, int w);
162 void	mkmonth(int year, int month, int jd_flag, struct monthlines * monthl);
163 void    mkmonthb(int year, int month, int jd_flag, struct monthlines * monthl);
164 void    mkweekdays(struct weekdays * wds);
165 int     parsemonth(const char *s);
166 void    printcc(void);
167 void    printeaster(int year, int julian, int orthodox);
168 void    printmonth(int year, int month, int jd_flag);
169 void    printmonthb(int year, int month, int jd_flag);
170 void    printyear(int year, int jd_flag);
171 void    printyearb(int year, int jd_flag);
172 int	firstday(int y, int m);
173 date   *sdate(int ndays, struct date * d);
174 date   *sdateb(int ndays, struct date * d);
175 int     sndays(struct date * d);
176 int     sndaysb(struct date * d);
177 static void usage(void);
178 int     weekdayb(int nd);
179 
180 int
181 main(int argc, char *argv[])
182 {
183 	struct  djswitch *p, *q;	/* to search user defined switch date */
184 	date	never = {10000, 1, 1};	/* outside valid range of dates */
185 	date	ukswitch = {1752, 9, 2};/* switch date for Great Britain */
186 	int     ch;			/* holds the option character */
187 	int     m = 0;			/* month */
188 	int	y = 0;			/* year */
189 	int     flag_backward = 0;	/* user called cal--backward compat. */
190 	int     flag_hole_year = 0;	/* user wants the whole year */
191 	int	flag_julian_cal = 0;	/* user wants Julian Calendar */
192 	int     flag_julian_day = 0;	/* user wants the Julian day
193 					 * numbers */
194 	int	flag_orthodox = 0;	/* use wants Orthodox easter */
195 	int	flag_easter = 0;	/* use wants easter date */
196 	char	*cp;			/* character pointer */
197 	char	*flag_month = NULL;	/* requested month as string */
198 	const char    *locale;		/* locale to get country code */
199 
200 	/*
201 	 * Use locale to determine the country code,
202 	 * and use the country code to determine the default
203 	 * switchdate and date format from the switches table.
204 	 */
205 	if (setlocale(LC_ALL, "") == NULL)
206 		warn("setlocale");
207 	locale = setlocale(LC_TIME, NULL);
208 	if (locale == NULL ||
209 	    strcmp(locale, "C") == 0 ||
210 	    strcmp(locale, "POSIX") == 0 ||
211 	    strcmp(locale, "ASCII") == 0 ||
212 	    strcmp(locale, "US-ASCII") == 0)
213 		locale = "_US";
214 	q = switches + sizeof(switches) / sizeof(struct djswitch);
215 	for (p = switches; p != q; p++)
216 		if ((cp = strstr(locale, p->cc)) != NULL && *(cp - 1) == '_')
217 			break;
218 	if (p == q) {
219 		nswitch = ndaysj(&dftswitch->dt);
220 	} else {
221 		nswitch = ndaysj(&p->dt);
222 		dftswitch = p;
223 	}
224 
225 
226 	/*
227 	 * Get the filename portion of argv[0] and set flag_backward if
228 	 * this program is called "cal".
229 	 */
230 	cp = strrchr(argv[0], '/');
231 	cp = (cp == NULL) ? argv[0] : cp + 1;
232 	if (strcmp("cal", cp) == 0)
233 		flag_backward = 1;
234 
235 	/* Set the switch date to United Kingdom if backwards compatible */
236 	if (flag_backward)
237 		nswitchb = ndaysj(&ukswitch);
238 
239 	while ((ch = getopt(argc, argv, "Jejm:ops:wy")) != -1)
240 		switch (ch) {
241 		case 'J':
242 			if (flag_backward)
243 				usage();
244 			nswitch = ndaysj(&never);
245 			flag_julian_cal = 1;
246 			break;
247 		case 'e':
248 			if (flag_backward)
249 				usage();
250 			flag_easter = 1;
251 			break;
252 		case 'j':
253 			flag_julian_day = 1;
254 			break;
255 		case 'm':
256 			flag_month = optarg;
257 			break;
258 		case 'o':
259 			if (flag_backward)
260 				usage();
261 			flag_orthodox = 1;
262 			flag_easter = 1;
263 			break;
264 		case 'p':
265 			if (flag_backward)
266 				usage();
267 			printcc();
268 			return (0);
269 			break;
270 		case 's':
271 			if (flag_backward)
272 				usage();
273 			q = switches +
274 			    sizeof(switches) / sizeof(struct djswitch);
275 			for (p = switches;
276 			     p != q && strcmp(p->cc, optarg) != 0; p++)
277 				;
278 			if (p == q)
279 				errx(EX_USAGE,
280 				    "%s: invalid country code", optarg);
281 			nswitch = ndaysj(&(p->dt));
282 			break;
283 		case 'w':
284 			if (flag_backward)
285 				usage();
286 			flag_weeks = 1;
287 			break;
288 		case 'y':
289 			flag_hole_year = 1;
290 			break;
291 		default:
292 			usage();
293 		}
294 
295 	argc -= optind;
296 	argv += optind;
297 
298 	switch (argc) {
299 	case 2:
300 		if (flag_easter)
301 			usage();
302 		flag_month = *argv++;
303 		/* FALLTHROUGH */
304 	case 1:
305 		y = atoi(*argv++);
306 		if (y < 1 || y > 9999)
307 			errx(EX_USAGE, "year %d not in range 1..9999", y);
308 		break;
309 	case 0:
310 		{
311 			time_t t;
312 			struct tm *tm;
313 
314 			t = time(NULL);
315 			tm = localtime(&t);
316 			y = tm->tm_year + 1900;
317 			m = tm->tm_mon + 1;
318 		}
319 		break;
320 	default:
321 		usage();
322 	}
323 
324 	if (flag_month != NULL) {
325 		m = parsemonth(flag_month);
326 		if (m < 1 || m > 12)
327 			errx(EX_USAGE,
328 			    "%s is neither a month number (1..12) nor a name",
329 			    flag_month);
330 	}
331 
332 	if (flag_easter)
333 		printeaster(y, flag_julian_cal, flag_orthodox);
334 	else if (argc == 1 || flag_hole_year)
335 		if (flag_backward)
336 			printyearb(y, flag_julian_day);
337 		else
338 			printyear(y, flag_julian_day);
339 	else
340 		if (flag_backward)
341 			printmonthb(y, m, flag_julian_day);
342 		else
343 			printmonth(y, m, flag_julian_day);
344 
345 	return (0);
346 }
347 
348 static void
349 usage(void)
350 {
351 
352 	fputs(
353 	    "usage: cal [-jy] [[month] year]\n"
354 	    "       cal [-j] [-m month] [year]\n"
355 	    "       ncal [-Jjpwy] [-s country_code] [[month] year]\n"
356 	    "       ncal [-Jeo] [year]\n", stderr);
357 	exit(EX_USAGE);
358 }
359 
360 /* print the assumed switches for all countries */
361 void
362 printcc(void)
363 {
364 	struct djswitch *p;
365 	int n;	/* number of lines to print */
366 	int m;	/* offset from left to right table entry on the same line */
367 
368 #define FSTR "%c%s %-15s%4d-%02d-%02d"
369 #define DFLT(p) ((p) == dftswitch ? '*' : ' ')
370 #define FSTRARG(p) DFLT(p), (p)->cc, (p)->nm, (p)->dt.y, (p)->dt.m, (p)->dt.d
371 
372 	n = sizeof(switches) / sizeof(struct djswitch);
373 	m = (n + 1) / 2;
374 	n /= 2;
375 	for (p = switches; p != switches + n; p++)
376 		printf(FSTR"     "FSTR"\n", FSTRARG(p), FSTRARG(p+m));
377 	if (m != n)
378 		printf(FSTR"\n", FSTRARG(p));
379 }
380 
381 /* print the date of easter sunday */
382 void
383 printeaster(int y, int julian, int orthodox)
384 {
385 	date    dt;
386 	struct tm tm;
387 	char    buf[80];
388 	static int d_first = -1;
389 
390 	if (d_first < 0)
391 		d_first = (*nl_langinfo(D_MD_ORDER) == 'd');
392 	/* force orthodox easter for years before 1583 */
393 	if (y < 1583)
394 		orthodox = 1;
395 
396 	if (orthodox)
397 		if (julian)
398 			easteroj(y, &dt);
399 		else
400 			easterog(y, &dt);
401 	else
402 		easterg(y, &dt);
403 
404 	memset(&tm, 0, sizeof(tm));
405 	tm.tm_year = dt.y - 1900;
406 	tm.tm_mon  = dt.m - 1;
407 	tm.tm_mday = dt.d;
408 	strftime(buf, sizeof(buf), d_first ? "%e %B %Y" : "%B %e %Y",  &tm);
409 	printf("%s\n", buf);
410 }
411 
412 void
413 printmonth(int y, int m, int jd_flag)
414 {
415 	struct monthlines month;
416 	struct weekdays wds;
417 	int i;
418 
419 	mkmonth(y, m - 1, jd_flag, &month);
420 	mkweekdays(&wds);
421 	printf("    %s %d\n", month.name, y);
422 	for (i = 0; i != 7; i++)
423 		printf("%.2s%s\n", wds.names[i], month.lines[i]);
424 	if (flag_weeks)
425 		printf("  %s\n", month.weeks);
426 }
427 
428 void
429 printmonthb(int y, int m, int jd_flag)
430 {
431 	struct monthlines month;
432 	struct weekdays wds;
433 	char s[MAX_WIDTH], t[MAX_WIDTH];
434 	int i;
435 	int mw;
436 
437 	mkmonthb(y, m - 1, jd_flag, &month);
438 	mkweekdays(&wds);
439 
440 	mw = jd_flag ? MONTH_WIDTH_B_J : MONTH_WIDTH_B;
441 
442 	sprintf(s, "%s %d", month.name, y);
443 	printf("%s\n", center(t, s, mw));
444 
445 	if (jd_flag)
446 		printf(" %s %s %s %s %s %s %.2s\n", wds.names[6], wds.names[0],
447 			wds.names[1], wds.names[2], wds.names[3],
448 			wds.names[4], wds.names[5]);
449 	else
450 		printf("%s%s%s%s%s%s%.2s\n", wds.names[6], wds.names[0],
451 			wds.names[1], wds.names[2], wds.names[3],
452 			wds.names[4], wds.names[5]);
453 
454 	for (i = 0; i != 6; i++)
455 		printf("%s\n", month.lines[i]+1);
456 }
457 
458 void
459 printyear(int y, int jd_flag)
460 {
461 	struct monthlines year[12];
462 	struct weekdays wds;
463 	char    s[80], t[80];
464 	int     i, j;
465 	int     mpl;
466 	int     mw;
467 
468 	for (i = 0; i != 12; i++)
469 		mkmonth(y, i, jd_flag, year + i);
470 	mkweekdays(&wds);
471 	mpl = jd_flag ? 3 : 4;
472 	mw = jd_flag ? MONTH_WIDTH_J : MONTH_WIDTH;
473 
474 	sprintf(s, "%d", y);
475 	printf("%s\n", center(t, s, mpl * mw));
476 
477 	for (j = 0; j != 12; j += mpl) {
478 		printf("    %-*s%-*s",
479 		    mw, year[j].name,
480 		    mw, year[j + 1].name);
481 		if (mpl == 3)
482 			printf("%s\n", year[j + 2].name);
483 		else
484 			printf("%-*s%s\n",
485 		    	    mw, year[j + 2].name,
486 		    	    year[j + 3].name);
487 		for (i = 0; i != 7; i++) {
488 			printf("%.2s%-*s%-*s",
489 			    wds.names[i],
490 			    mw, year[j].lines[i],
491 			    mw, year[j + 1].lines[i]);
492 			if (mpl == 3)
493 				printf("%s\n", year[j + 2].lines[i]);
494 			else
495 				printf("%-*s%s\n",
496 			    	    mw, year[j + 2].lines[i],
497 			    	    year[j + 3].lines[i]);
498 		}
499 		if (flag_weeks) {
500 			if (mpl == 3)
501 				printf("  %-*s%-*s%-s\n",
502 				    mw, year[j].weeks,
503 				    mw, year[j + 1].weeks,
504 				    year[j + 2].weeks);
505 			else
506 				printf("  %-*s%-*s%-*s%-s\n",
507 				    mw, year[j].weeks,
508 				    mw, year[j + 1].weeks,
509 				    mw, year[j + 2].weeks,
510 				    year[j + 3].weeks);
511 		}
512 	}
513 }
514 
515 void
516 printyearb(int y, int jd_flag)
517 {
518 	struct monthlines year[12];
519 	struct weekdays wds;
520 	char	s[80], t[80];
521 	int     i, j;
522 	int     mpl;
523 	int     mw;
524 
525 	for (i = 0; i != 12; i++)
526 		mkmonthb(y, i, jd_flag, year + i);
527 	mkweekdays(&wds);
528 	mpl = jd_flag ? 2 : 3;
529 	mw = jd_flag ? MONTH_WIDTH_B_J : MONTH_WIDTH_B;
530 
531 	sprintf(s, "%d", y);
532 	printf("%s\n\n", center(t, s, mw * mpl + mpl));
533 
534 	for (j = 0; j != 12; j += mpl) {
535 		printf("%-*s  ", mw, center(s, year[j].name, mw));
536 		if (mpl == 2)
537 			printf("%s\n", center(s, year[j + 1].name, mw));
538 		else
539 			printf("%-*s  %s\n", mw,
540 			    center(s, year[j + 1].name, mw),
541 			    center(t, year[j + 2].name, mw));
542 
543 		if (mpl == 2)
544 			printf(" %s %s %s %s %s %s %s "
545 			       " %s %s %s %s %s %s %.2s\n",
546 				wds.names[6], wds.names[0], wds.names[1],
547 				wds.names[2], wds.names[3], wds.names[4],
548 				wds.names[5],
549 				wds.names[6], wds.names[0], wds.names[1],
550 				wds.names[2], wds.names[3], wds.names[4],
551 				wds.names[5]);
552 		else
553 			printf("%s%s%s%s%s%s%s "
554 				"%s%s%s%s%s%s%s "
555 				"%s%s%s%s%s%s%.2s\n",
556 				wds.names[6], wds.names[0], wds.names[1],
557 				wds.names[2], wds.names[3], wds.names[4],
558 				wds.names[5],
559 				wds.names[6], wds.names[0], wds.names[1],
560 				wds.names[2], wds.names[3], wds.names[4],
561 				wds.names[5],
562 				wds.names[6], wds.names[0], wds.names[1],
563 				wds.names[2], wds.names[3], wds.names[4],
564 				wds.names[5]);
565 		for (i = 0; i != 6; i++) {
566 			if (mpl == 2)
567 				printf("%-*s  %s\n",
568 			    mw, year[j].lines[i]+1,
569 			    year[j + 1].lines[i]+1);
570 			else
571 				printf("%-*s  %-*s  %s\n",
572 			    mw, year[j].lines[i]+1,
573 			    mw, year[j + 1].lines[i]+1,
574 			    year[j + 2].lines[i]+1);
575 
576 		}
577 	}
578 }
579 
580 void
581 mkmonth(int y, int m, int jd_flag, struct monthlines *mlines)
582 {
583 
584 	struct tm tm;		/* for strftime printing local names of
585 				 * months */
586 	date    dt;		/* handy date */
587 	int     dw;		/* width of numbers */
588 	int     first;		/* first day of month */
589 	int     firstm;		/* first day of first week of month */
590 	int     i, j, k;	/* just indices */
591 	int     last;		/* the first day of next month */
592 	int     jan1 = 0;	/* the first day of this year */
593 	char   *ds;		/* pointer to day strings (daystr or
594 				 * jdaystr) */
595 
596 	/* Set name of month. */
597 	memset(&tm, 0, sizeof(tm));
598 	tm.tm_mon = m;
599 	strftime(mlines->name, sizeof(mlines->name), "%OB", &tm);
600 	mlines->name[0] = toupper((unsigned char)mlines->name[0]);
601 
602 	/*
603 	 * Set first and last to the day number of the first day of this
604 	 * month and the first day of next month respectively. Set jan1 to
605 	 * the day number of the first day of this year.
606 	 */
607 	first = firstday(y, m + 1);
608 	if (m == 11)
609 		last = firstday(y + 1, 1);
610 	else
611 		last = firstday(y, m + 2);
612 
613 	if (jd_flag)
614 		jan1 = firstday(y, 1);
615 
616 	/*
617 	 * Set firstm to the day number of monday of the first week of
618 	 * this month. (This might be in the last month)
619 	 */
620 	firstm = first - weekday(first);
621 
622 	/* Set ds (daystring) and dw (daywidth) according to the jd_flag */
623 	if (jd_flag) {
624 		ds = jdaystr;
625 		dw = 4;
626 	} else {
627 		ds = daystr;
628 		dw = 3;
629 	}
630 
631 	/*
632 	 * Fill the lines with day of month or day of year (julian day)
633 	 * line index: i, each line is one weekday. column index: j, each
634 	 * column is one day number. print column index: k.
635 	 */
636 	for (i = 0; i != 7; i++) {
637 		for (j = firstm + i, k = 0; j < last; j += 7, k += dw)
638 			if (j >= first) {
639 				if (jd_flag)
640 					dt.d = j - jan1 + 1;
641 				else
642 					sdate(j, &dt);
643 				memcpy(mlines->lines[i] + k,
644 				       ds + dt.d * dw, dw);
645 			} else
646 				memcpy(mlines->lines[i] + k, "    ", dw);
647 		mlines->lines[i][k] = '\0';
648 
649 	}
650 
651 	/* fill the weeknumbers */
652 	if (flag_weeks) {
653 		for (j = firstm, k = 0; j < last;  k += dw, j += 7)
654 			if (j <= nswitch)
655 				memset(mlines->weeks + k, ' ', dw);
656 			else
657 				memcpy(mlines->weeks + k,
658 				    ds + week(j, &i)*dw, dw);
659 		mlines->weeks[k] = '\0';
660 	}
661 }
662 
663 void
664 mkmonthb(int y, int m, int jd_flag, struct monthlines *mlines)
665 {
666 
667 	struct tm tm;		/* for strftime printing local names of
668 				 * months */
669 	date    dt;		/* handy date */
670 	int     dw;		/* width of numbers */
671 	int     first;		/* first day of month */
672 	int     firsts;		/* sunday of first week of month */
673 	int     i, j, k;	/* just indices */
674 	int     jan1 = 0;	/* the first day of this year */
675 	int     last;		/* the first day of next month */
676 	char   *ds;		/* pointer to day strings (daystr or
677 				 * jdaystr) */
678 
679 	/* Set ds (daystring) and dw (daywidth) according to the jd_flag */
680 	if (jd_flag) {
681 		ds = jdaystr;
682 		dw = 4;
683 	} else {
684 		ds = daystr;
685 		dw = 3;
686 	}
687 
688 	/* Set name of month centered */
689 	memset(&tm, 0, sizeof(tm));
690 	tm.tm_mon = m;
691 	strftime(mlines->name, sizeof(mlines->name), "%OB", &tm);
692 	mlines->name[0] = toupper((unsigned char)mlines->name[0]);
693 
694 	/*
695 	 * Set first and last to the day number of the first day of this
696 	 * month and the first day of next month respectively. Set jan1 to
697 	 * the day number of Jan 1st of this year.
698 	 */
699 	dt.y = y;
700 	dt.m = m + 1;
701 	dt.d = 1;
702 	first = sndaysb(&dt);
703 	if (m == 11) {
704 		dt.y = y + 1;
705 		dt.m = 1;
706 		dt.d = 1;
707 	} else {
708 		dt.y = y;
709 		dt.m = m + 2;
710 		dt.d = 1;
711 	}
712 	last = sndaysb(&dt);
713 
714 	if (jd_flag) {
715 		dt.y = y;
716 		dt.m = 1;
717 		dt.d = 1;
718 		jan1 = sndaysb(&dt);
719 	}
720 
721 	/*
722 	 * Set firsts to the day number of sunday of the first week of
723 	 * this month. (This might be in the last month)
724 	 */
725 	firsts = first - (weekday(first)+1) % 7;
726 
727 	/*
728 	 * Fill the lines with day of month or day of year (Julian day)
729 	 * line index: i, each line is one week. column index: j, each
730 	 * column is one day number. print column index: k.
731 	 */
732 	for (i = 0; i != 6; i++) {
733 		for (j = firsts + 7 * i, k = 0; j < last && k != dw * 7;
734 		     j++, k += dw)
735 			if (j >= first) {
736 				if (jd_flag)
737 					dt.d = j - jan1 + 1;
738 				else
739 					sdateb(j, &dt);
740 				memcpy(mlines->lines[i] + k,
741 				       ds + dt.d * dw, dw);
742 			} else
743 				memcpy(mlines->lines[i] + k, "    ", dw);
744 		if (k == 0)
745 			mlines->lines[i][1] = '\0';
746 		else
747 			mlines->lines[i][k] = '\0';
748 	}
749 }
750 
751 /* Put the local names of weekdays into the wds */
752 void
753 mkweekdays(struct weekdays *wds)
754 {
755 	int i, len;
756 	struct tm tm;
757 	char buf[20];
758 
759 	memset(&tm, 0, sizeof(tm));
760 
761 	for (i = 0; i != 7; i++) {
762 		tm.tm_wday = (i+1) % 7;
763 		strftime(buf, sizeof(buf), "%a", &tm);
764 		len = strlen(buf);
765 		if (len > 2)
766 			len = 2;
767 		strcpy(wds->names[i], "   ");
768 		strncpy(wds->names[i] + 2 - len, buf, len);
769 	}
770 }
771 
772 /*
773  * Compute the day number of the first
774  * existing date after the first day in month.
775  * (the first day in month and even the month might not exist!)
776  */
777 int
778 firstday(int y, int m)
779 {
780 	date dt;
781 	int nd;
782 
783 	dt.y = y;
784 	dt.m = m;
785 	dt.d = 1;
786 	nd = sndays(&dt);
787 	for (;;) {
788 		sdate(nd, &dt);
789 		if ((dt.m >= m && dt.y == y) || dt.y > y)
790 			return (nd);
791 		else
792 			nd++;
793 	}
794 	/* NEVER REACHED */
795 }
796 
797 /*
798  * Compute the number of days from date, obey the local switch from
799  * Julian to Gregorian if specified by the user.
800  */
801 int
802 sndays(struct date *d)
803 {
804 
805 	if (nswitch != 0)
806 		if (nswitch < ndaysj(d))
807 			return (ndaysg(d));
808 		else
809 			return (ndaysj(d));
810 	else
811 		return ndaysg(d);
812 }
813 
814 /*
815  * Compute the number of days from date, obey the switch from
816  * Julian to Gregorian as used by UK and her colonies.
817  */
818 int
819 sndaysb(struct date *d)
820 {
821 
822 	if (nswitchb < ndaysj(d))
823 		return (ndaysg(d));
824 	else
825 		return (ndaysj(d));
826 }
827 
828 /* Inverse of sndays */
829 struct date *
830 sdate(int nd, struct date *d)
831 {
832 
833 	if (nswitch < nd)
834 		return (gdate(nd, d));
835 	else
836 		return (jdate(nd, d));
837 }
838 
839 /* Inverse of sndaysb */
840 struct date *
841 sdateb(int nd, struct date *d)
842 {
843 
844 	if (nswitchb < nd)
845 		return (gdate(nd, d));
846 	else
847 		return (jdate(nd, d));
848 }
849 
850 /* Center string t in string s of length w by putting enough leading blanks */
851 char *
852 center(char *s, char *t, int w)
853 {
854 	char blanks[80];
855 
856 	memset(blanks, ' ', sizeof(blanks));
857 	sprintf(s, "%.*s%s", (int)(w - strlen(t)) / 2, blanks, t);
858 	return (s);
859 }
860 
861 int
862 parsemonth(const char *s)
863 {
864 	int v;
865 	char *cp;
866 	struct tm tm;
867 
868 	v = (int)strtol(s, &cp, 10);
869 	if (cp != s)
870 		return (v);
871 	if (strptime(s, "%B", &tm) != NULL)
872 		return (tm.tm_mon + 1);
873 	if (strptime(s, "%b", &tm) != NULL)
874 		return (tm.tm_mon + 1);
875 	return (0);
876 }
877