xref: /freebsd/bin/date/vary.c (revision 3ff369fed2a08f32dda232c10470b949bef9489f) 
1 /*-
2  * Copyright (c) 1997 Brian Somers <brian@Awfulhak.org>
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 <sys/cdefs.h>
33 #include <err.h>
34 #include <time.h>
35 #include <string.h>
36 #include <stdlib.h>
37 #include "vary.h"
38 
39 struct trans {
40   int val;
41   const char *str;
42 };
43 
44 static struct trans trans_mon[] = {
45   { 1, "january" }, { 2, "february" }, { 3, "march" }, { 4, "april" },
46   { 5, "may"}, { 6, "june" }, { 7, "july" }, { 8, "august" },
47   { 9, "september" }, { 10, "october" }, { 11, "november" }, { 12, "december" },
48   { -1, NULL }
49 };
50 
51 static struct trans trans_wday[] = {
52   { 0, "sunday" }, { 1, "monday" }, { 2, "tuesday" }, { 3, "wednesday" },
53   { 4, "thursday" }, { 5, "friday" }, { 6, "saturday" },
54   { -1, NULL }
55 };
56 
57 static char digits[] = "0123456789";
58 static int adjhour(struct tm *, char, int, int);
59 
60 static int
61 domktime(struct tm *t, char type)
62 {
63   time_t ret;
64 
65   while ((ret = mktime(t)) == -1 && t->tm_year > 68 && t->tm_year < 138)
66     /* While mktime() fails, adjust by an hour */
67     adjhour(t, type == '-' ? type : '+', 1, 0);
68 
69   return ret;
70 }
71 
72 static int
73 trans(const struct trans t[], const char *arg)
74 {
75   int f;
76 
77   for (f = 0; t[f].val != -1; f++)
78     if (!strncasecmp(t[f].str, arg, 3) ||
79         !strncasecmp(t[f].str, arg, strlen(t[f].str)))
80       return t[f].val;
81 
82   return -1;
83 }
84 
85 struct vary *
86 vary_append(struct vary *v, char *arg)
87 {
88   struct vary *result, **nextp;
89 
90   if (v) {
91     result = v;
92     while (v->next)
93       v = v->next;
94     nextp = &v->next;
95   } else
96     nextp = &result;
97 
98   if ((*nextp = (struct vary *)malloc(sizeof(struct vary))) == NULL)
99     err(1, "malloc");
100   (*nextp)->arg = arg;
101   (*nextp)->next = NULL;
102   return result;
103 }
104 
105 static int mdays[12] = { 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
106 
107 static int
108 daysinmonth(const struct tm *t)
109 {
110   int year;
111 
112   year = t->tm_year + 1900;
113 
114   if (t->tm_mon == 1)
115     if (!(year % 400))
116       return 29;
117     else if (!(year % 100))
118       return 28;
119     else if (!(year % 4))
120       return 29;
121     else
122       return 28;
123   else if (t->tm_mon >= 0 && t->tm_mon < 12)
124     return mdays[t->tm_mon];
125 
126   return 0;
127 }
128 
129 
130 static int
131 adjyear(struct tm *t, char type, int val, int mk)
132 {
133   switch (type) {
134     case '+':
135       t->tm_year += val;
136       break;
137     case '-':
138       t->tm_year -= val;
139       break;
140     default:
141       t->tm_year = val;
142       if (t->tm_year < 69)
143       	t->tm_year += 100;		/* as per date.c */
144       else if (t->tm_year > 1900)
145         t->tm_year -= 1900;             /* struct tm holds years since 1900 */
146       break;
147   }
148   return !mk || domktime(t, type) != -1;
149 }
150 
151 static int
152 adjmon(struct tm *t, char type, int val, int istext, int mk)
153 {
154   if (val < 0)
155     return 0;
156 
157   switch (type) {
158     case '+':
159       if (istext) {
160         if (val <= t->tm_mon)
161           val += 11 - t->tm_mon;	/* early next year */
162         else
163           val -= t->tm_mon + 1;		/* later this year */
164       }
165       if (val) {
166         if (!adjyear(t, '+', (t->tm_mon + val) / 12, 0))
167           return 0;
168         val %= 12;
169         t->tm_mon += val;
170         if (t->tm_mon > 11)
171           t->tm_mon -= 12;
172       }
173       break;
174 
175     case '-':
176       if (istext) {
177         if (val-1 > t->tm_mon)
178           val = 13 - val + t->tm_mon;	/* later last year */
179         else
180           val = t->tm_mon - val + 1;	/* early this year */
181       }
182       if (val) {
183         if (!adjyear(t, '-', val / 12, 0))
184           return 0;
185         val %= 12;
186         if (val > t->tm_mon) {
187           if (!adjyear(t, '-', 1, 0))
188             return 0;
189           val -= 12;
190         }
191         t->tm_mon -= val;
192       }
193       break;
194 
195     default:
196       if (val > 12 || val < 1)
197         return 0;
198       t->tm_mon = --val;
199   }
200 
201   return !mk || domktime(t, type) != -1;
202 }
203 
204 static int
205 adjday(struct tm *t, char type, int val, int mk)
206 {
207   int lmdays;
208 
209   switch (type) {
210     case '+':
211       while (val) {
212         lmdays = daysinmonth(t);
213         if (val > lmdays - t->tm_mday) {
214           val -= lmdays - t->tm_mday + 1;
215           t->tm_mday = 1;
216           if (!adjmon(t, '+', 1, 0, 0))
217             return 0;
218         } else {
219           t->tm_mday += val;
220           val = 0;
221         }
222       }
223       break;
224     case '-':
225       while (val)
226         if (val >= t->tm_mday) {
227           val -= t->tm_mday;
228           t->tm_mday = 1;
229           if (!adjmon(t, '-', 1, 0, 0))
230             return 0;
231           t->tm_mday = daysinmonth(t);
232         } else {
233           t->tm_mday -= val;
234           val = 0;
235         }
236       break;
237     default:
238       if (val > 0 && val <= daysinmonth(t))
239         t->tm_mday = val;
240       else
241         return 0;
242       break;
243   }
244 
245   return !mk || domktime(t, type) != -1;
246 }
247 
248 static int
249 adjwday(struct tm *t, char type, int val, int istext, int mk)
250 {
251   if (val < 0)
252     return 0;
253 
254   switch (type) {
255     case '+':
256       if (istext)
257         if (val < t->tm_wday)
258           val = 7 - t->tm_wday + val;  /* early next week */
259         else
260           val -= t->tm_wday;           /* later this week */
261       else
262         val *= 7;                      /* "-v+5w" == "5 weeks in the future" */
263       return !val || adjday(t, '+', val, mk);
264     case '-':
265       if (istext) {
266         if (val > t->tm_wday)
267           val = 7 - val + t->tm_wday;  /* later last week */
268         else
269           val = t->tm_wday - val;      /* early this week */
270       } else
271         val *= 7;                      /* "-v-5w" == "5 weeks ago" */
272       return !val || adjday(t, '-', val, mk);
273     default:
274       if (val < t->tm_wday)
275         return adjday(t, '-', t->tm_wday - val, mk);
276       else if (val > 6)
277         return 0;
278       else if (val > t->tm_wday)
279         return adjday(t, '+', val - t->tm_wday, mk);
280   }
281   return 1;
282 }
283 
284 static int
285 adjhour(struct tm *t, char type, int val, int mk)
286 {
287   if (val < 0)
288     return 0;
289 
290   switch (type) {
291     case '+':
292       if (val) {
293         int days;
294 
295         days = (t->tm_hour + val) / 24;
296         val %= 24;
297         t->tm_hour += val;
298         t->tm_hour %= 24;
299         if (!adjday(t, '+', days, 0))
300           return 0;
301       }
302       break;
303 
304     case '-':
305       if (val) {
306         int days;
307 
308         days = val / 24;
309         val %= 24;
310         if (val > t->tm_hour) {
311           days++;
312           val -= 24;
313         }
314         t->tm_hour -= val;
315         if (!adjday(t, '-', days, 0))
316           return 0;
317       }
318       break;
319 
320     default:
321       if (val > 23)
322         return 0;
323       t->tm_hour = val;
324   }
325 
326   return !mk || domktime(t, type) != -1;
327 }
328 
329 static int
330 adjmin(struct tm *t, char type, int val, int mk)
331 {
332   if (val < 0)
333     return 0;
334 
335   switch (type) {
336     case '+':
337       if (val) {
338         if (!adjhour(t, '+', (t->tm_min + val) / 60, 0))
339           return 0;
340         val %= 60;
341         t->tm_min += val;
342         if (t->tm_min > 59)
343           t->tm_min -= 60;
344       }
345       break;
346 
347     case '-':
348       if (val) {
349         if (!adjhour(t, '-', val / 60, 0))
350           return 0;
351         val %= 60;
352         if (val > t->tm_min) {
353           if (!adjhour(t, '-', 1, 0))
354             return 0;
355           val -= 60;
356         }
357         t->tm_min -= val;
358       }
359       break;
360 
361     default:
362       if (val > 59)
363         return 0;
364       t->tm_min = val;
365   }
366 
367   return !mk || domktime(t, type) != -1;
368 }
369 
370 static int
371 adjsec(struct tm *t, char type, int val, int mk)
372 {
373   if (val < 0)
374     return 0;
375 
376   switch (type) {
377     case '+':
378       if (val) {
379         if (!adjmin(t, '+', (t->tm_sec + val) / 60, 0))
380           return 0;
381         val %= 60;
382         t->tm_sec += val;
383         if (t->tm_sec > 59)
384           t->tm_sec -= 60;
385       }
386       break;
387 
388     case '-':
389       if (val) {
390         if (!adjmin(t, '-', val / 60, 0))
391           return 0;
392         val %= 60;
393         if (val > t->tm_sec) {
394           if (!adjmin(t, '-', 1, 0))
395             return 0;
396           val -= 60;
397         }
398         t->tm_sec -= val;
399       }
400       break;
401 
402     default:
403       if (val > 59)
404         return 0;
405       t->tm_sec = val;
406   }
407 
408   return !mk || domktime(t, type) != -1;
409 }
410 
411 const struct vary *
412 vary_apply(const struct vary *v, struct tm *t)
413 {
414   char type;
415   char which;
416   char *arg;
417   size_t len;
418   int val;
419 
420   for (; v; v = v->next) {
421     type = *v->arg;
422     arg = v->arg;
423     if (type == '+' || type == '-')
424       arg++;
425     else
426       type = '\0';
427     len = strlen(arg);
428     if (len < 2)
429       return v;
430 
431     if (type == '\0')
432       t->tm_isdst = -1;
433 
434     if (strspn(arg, digits) != len-1) {
435       val = trans(trans_wday, arg);
436       if (val != -1) {
437           if (!adjwday(t, type, val, 1, 1))
438             return v;
439       } else {
440         val = trans(trans_mon, arg);
441         if (val != -1) {
442           if (!adjmon(t, type, val, 1, 1))
443             return v;
444         } else
445           return v;
446       }
447     } else {
448       val = atoi(arg);
449       which = arg[len-1];
450 
451       switch (which) {
452         case 'S':
453           if (!adjsec(t, type, val, 1))
454             return v;
455           break;
456         case 'M':
457           if (!adjmin(t, type, val, 1))
458             return v;
459           break;
460         case 'H':
461           if (!adjhour(t, type, val, 1))
462             return v;
463           break;
464         case 'd':
465           t->tm_isdst = -1;
466           if (!adjday(t, type, val, 1))
467             return v;
468           break;
469         case 'w':
470           t->tm_isdst = -1;
471           if (!adjwday(t, type, val, 0, 1))
472             return v;
473           break;
474         case 'm':
475           t->tm_isdst = -1;
476           if (!adjmon(t, type, val, 0, 1))
477             return v;
478           break;
479         case 'y':
480           t->tm_isdst = -1;
481           if (!adjyear(t, type, val, 1))
482             return v;
483           break;
484         default:
485           return v;
486       }
487     }
488   }
489   return 0;
490 }
491 
492 void
493 vary_destroy(struct vary *v)
494 {
495   struct vary *n;
496 
497   while (v) {
498     n = v->next;
499     free(v);
500     v = n;
501   }
502 }
503