xref: /freebsd/bin/date/vary.c (revision 4cf49a43559ed9fdad601bdcccd2c55963008675) 
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 <time.h>
33 #include <string.h>
34 #include <stdlib.h>
35 #include "vary.h"
36 
37 struct trans {
38   int val;
39   char *str;
40 };
41 
42 static struct trans trans_mon[] = {
43   { 1, "january" }, { 2, "february" }, { 3, "march" }, { 4, "april" },
44   { 6, "june" }, { 7, "july" }, { 8, "august" }, { 9, "september" },
45   { 10, "october" }, { 11, "november" }, { 12, "december" },
46   { -1, NULL }
47 };
48 
49 static struct trans trans_wday[] = {
50   { 0, "sunday" }, { 1, "monday" }, { 2, "tuesday" }, { 3, "wednesday" },
51   { 4, "thursday" }, { 5, "friday" }, { 6, "saturday" },
52   { -1, NULL }
53 };
54 
55 static char digits[] = "0123456789";
56 
57 static int
58 trans(const struct trans t[], const char *arg)
59 {
60   int f;
61 
62   for (f = 0; t[f].val != -1; f++)
63     if (!strncasecmp(t[f].str, arg, 3) ||
64         !strncasecmp(t[f].str, arg, strlen(t[f].str)))
65       return t[f].val;
66 
67   return -1;
68 }
69 
70 struct vary *
71 vary_append(struct vary *v, char *arg)
72 {
73   struct vary *result, **nextp;
74 
75   if (v) {
76     result = v;
77     while (v->next)
78       v = v->next;
79     nextp = &v->next;
80   } else
81     nextp = &result;
82 
83   *nextp = (struct vary *)malloc(sizeof(struct vary));
84   (*nextp)->arg = arg;
85   (*nextp)->next = NULL;
86   return result;
87 }
88 
89 static int mdays[12] = { 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
90 
91 static int
92 daysinmonth(const struct tm *t)
93 {
94   int year;
95 
96   year = t->tm_year + 1900;
97 
98   if (t->tm_mon == 1)
99     if (!(year % 400))
100       return 29;
101     else if (!(year % 100))
102       return 28;
103     else if (!(year % 4))
104       return 29;
105     else
106       return 28;
107   else if (t->tm_mon >= 0 && t->tm_mon < 12)
108     return mdays[t->tm_mon];
109 
110   return 0;
111 }
112 
113 
114 static int
115 adjyear(struct tm *t, char type, int val)
116 {
117   switch (type) {
118     case '+':
119       t->tm_year += val;
120       break;
121     case '-':
122       t->tm_year -= val;
123       break;
124     default:
125       t->tm_year = val;
126       if (t->tm_year < 69)
127       	t->tm_year += 100;		/* as per date.c */
128       else if (t->tm_year > 1900)
129         t->tm_year -= 1900;             /* struct tm holds years since 1900 */
130       break;
131   }
132   return mktime(t) != -1;
133 }
134 
135 static int
136 adjmon(struct tm *t, char type, int val, int istext)
137 {
138   if (val < 0)
139     return 0;
140 
141   switch (type) {
142     case '+':
143       if (istext) {
144         if (val <= t->tm_mon)
145           val += 11 - t->tm_mon;	/* early next year */
146         else
147           val -= t->tm_mon + 1;		/* later this year */
148       }
149       if (!adjyear(t, '+', (t->tm_mon + val) / 12))
150         return 0;
151       val %= 12;
152       t->tm_mon += val;
153       if (t->tm_mon > 11)
154         t->tm_mon -= 12;
155       break;
156 
157     case '-':
158       if (istext) {
159         if (val-1 > t->tm_mon)
160           val = 13 - val + t->tm_mon;	/* later last year */
161         else
162           val = t->tm_mon - val + 1;	/* early this year */
163       }
164       if (!adjyear(t, '-', val / 12))
165         return 0;
166       val %= 12;
167       if (val > t->tm_mon) {
168         if (!adjyear(t, '-', 1))
169           return 0;
170         val -= 12;
171       }
172       t->tm_mon -= val;
173       break;
174 
175     default:
176       if (val > 12 || val < 1)
177         return 0;
178       t->tm_mon = --val;
179   }
180 
181   return mktime(t) != -1;
182 }
183 
184 static int
185 adjday(struct tm *t, char type, int val)
186 {
187   int mdays;
188   switch (type) {
189     case '+':
190       while (val) {
191         mdays = daysinmonth(t);
192         if (val > mdays - t->tm_mday) {
193           val -= mdays - t->tm_mday + 1;
194           t->tm_mday = 1;
195           if (!adjmon(t, '+', 1, 0))
196             return 0;
197         } else {
198           t->tm_mday += val;
199           val = 0;
200         }
201       }
202       break;
203     case '-':
204       while (val)
205         if (val >= t->tm_mday) {
206           val -= t->tm_mday;
207           t->tm_mday = 1;
208           if (!adjmon(t, '-', 1, 0))
209             return 0;
210           t->tm_mday = daysinmonth(t);
211         } else {
212           t->tm_mday -= val;
213           val = 0;
214         }
215       break;
216     default:
217       if (val > 0 && val <= daysinmonth(t))
218         t->tm_mday = val;
219       else
220         return 0;
221       break;
222   }
223 
224   return mktime(t) != -1;
225 }
226 
227 static int
228 adjwday(struct tm *t, char type, int val, int istext)
229 {
230   if (val < 0)
231     return 0;
232 
233   switch (type) {
234     case '+':
235       if (istext)
236         if (val < t->tm_wday)
237           val = 7 - t->tm_wday + val;  /* early next week */
238         else
239           val -= t->tm_wday;           /* later this week */
240       else
241         val *= 7;                      /* "-W +5" == "5 weeks in the future" */
242       return adjday(t, '+', val);
243     case '-':
244       if (istext)
245         if (val > t->tm_wday)
246           val = 7 - val + t->tm_wday;  /* later last week */
247         else
248           val = t->tm_wday - val;      /* early this week */
249       else
250         val *= 7;                      /* "-W -5" == "5 weeks ago" */
251       return adjday(t, '-', val);
252     default:
253       if (val < t->tm_wday)
254         return adjday(t, '-', t->tm_wday - val);
255       else if (val > 6)
256         return 0;
257       else if (val > t->tm_wday)
258         return adjday(t, '+', val - t->tm_wday);
259   }
260   return 1;
261 }
262 
263 static int
264 adjhour(struct tm *t, char type, int val)
265 {
266   if (val < 0)
267     return 0;
268 
269   switch (type) {
270     case '+':
271       if (!adjday(t, '+', (t->tm_hour + val) / 24))
272         return 0;
273       val %= 24;
274       t->tm_hour += val;
275       if (t->tm_hour > 23)
276         t->tm_hour -= 24;
277       break;
278 
279     case '-':
280       if (!adjday(t, '-', val / 24))
281         return 0;
282       val %= 24;
283       if (val > t->tm_hour) {
284         if (!adjday(t, '-', 1))
285           return 0;
286         val -= 24;
287       }
288       t->tm_hour -= val;
289       break;
290 
291     default:
292       if (val > 23)
293         return 0;
294       t->tm_hour = val;
295   }
296 
297   return mktime(t) != -1;
298 }
299 
300 static int
301 adjmin(struct tm *t, char type, int val)
302 {
303   if (val < 0)
304     return 0;
305 
306   switch (type) {
307     case '+':
308       if (!adjhour(t, '+', (t->tm_min + val) / 60))
309         return 0;
310       val %= 60;
311       t->tm_min += val;
312       if (t->tm_min > 59)
313         t->tm_min -= 60;
314       break;
315 
316     case '-':
317       if (!adjhour(t, '-', val / 60))
318         return 0;
319       val %= 60;
320       if (val > t->tm_min) {
321         if (!adjhour(t, '-', 1))
322           return 0;
323         val -= 60;
324       }
325       t->tm_min -= val;
326       break;
327 
328     default:
329       if (val > 59)
330         return 0;
331       t->tm_min = val;
332   }
333 
334   return mktime(t) != -1;
335 }
336 
337 static int
338 adjsec(struct tm *t, char type, int val)
339 {
340   if (val < 0)
341     return 0;
342 
343   switch (type) {
344     case '+':
345       if (!adjmin(t, '+', (t->tm_sec + val) / 60))
346         return 0;
347       val %= 60;
348       t->tm_sec += val;
349       if (t->tm_sec > 59)
350         t->tm_sec -= 60;
351       break;
352 
353     case '-':
354       if (!adjmin(t, '-', val / 60))
355         return 0;
356       val %= 60;
357       if (val > t->tm_sec) {
358         if (!adjmin(t, '-', 1))
359           return 0;
360         val -= 60;
361       }
362       t->tm_sec -= val;
363       break;
364 
365     default:
366       if (val > 59)
367         return 0;
368       t->tm_sec = val;
369   }
370 
371   return mktime(t) != -1;
372 }
373 
374 const struct vary *
375 vary_apply(const struct vary *v, struct tm *t)
376 {
377   char type;
378   char which;
379   char *arg;
380   int len;
381   int val;
382 
383   for (; v; v = v->next) {
384     type = *v->arg;
385     arg = v->arg;
386     if (type == '+' || type == '-')
387       arg++;
388     else
389       type = '\0';
390     len = strlen(arg);
391     if (len < 2)
392       return v;
393 
394     if (strspn(arg, digits) != len-1) {
395       val = trans(trans_wday, arg);
396       if (val != -1) {
397           if (!adjwday(t, type, val, 1))
398             return v;
399       } else {
400         val = trans(trans_mon, arg);
401         if (val != -1) {
402           if (!adjmon(t, type, val, 1))
403             return v;
404         } else
405           return v;
406       }
407     } else {
408       val = atoi(arg);
409       which = arg[len-1];
410 
411       switch (which) {
412         case 'S':
413           if (!adjsec(t, type, val))
414             return v;
415           break;
416         case 'M':
417           if (!adjmin(t, type, val))
418             return v;
419           break;
420         case 'H':
421           if (!adjhour(t, type, val))
422             return v;
423           break;
424         case 'd':
425           if (!adjday(t, type, val))
426             return v;
427           break;
428         case 'w':
429           if (!adjwday(t, type, val, 0))
430             return v;
431           break;
432         case 'm':
433           if (!adjmon(t, type, val, 0))
434             return v;
435           break;
436         case 'y':
437           if (!adjyear(t, type, val))
438             return v;
439           break;
440         default:
441           return v;
442       }
443     }
444   }
445   return 0;
446 }
447 
448 void
449 vary_destroy(struct vary *v)
450 {
451   struct vary *n;
452 
453   while (v) {
454     n = v->next;
455     free(v);
456     v = n;
457   }
458 }
459