vary.c revision 35773 
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
28static const char rcsid[] =
29	"$Id$";
30#endif /* not lint */
31
32#include <time.h>
33#include <string.h>
34#include <stdlib.h>
35#include "vary.h"
36
37struct trans {
38  int val;
39  char *str;
40};
41
42static 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
49static 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
55static char digits[] = "0123456789";
56
57static int
58trans(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
70struct vary *
71vary_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
89static int mdays[12] = { 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
90
91static int
92daysinmonth(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
114static int
115adjyear(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
135static int
136adjmon(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      if (!adjyear(t, '+', (t->tm_mon + val) / 12))
149        return 0;
150      val %= 12;
151      t->tm_mon += val;
152      if (t->tm_mon > 11)
153        t->tm_mon -= 12;
154      break;
155
156    case '-':
157      if (istext)
158        if (val-1 > t->tm_mon)
159          val = 13 - val + t->tm_mon;	/* later last year */
160        else
161          val = t->tm_mon - val + 1;	/* early this year */
162      if (!adjyear(t, '-', val / 12))
163        return 0;
164      val %= 12;
165      if (val > t->tm_mon) {
166        if (!adjyear(t, '-', 1))
167          return 0;
168        val -= 12;
169      }
170      t->tm_mon -= val;
171      break;
172
173    default:
174      if (val > 12 || val < 1)
175        return 0;
176      t->tm_mon = --val;
177  }
178
179  return mktime(t) != -1;
180}
181
182static int
183adjday(struct tm *t, char type, int val)
184{
185  int mdays;
186  switch (type) {
187    case '+':
188      while (val) {
189        mdays = daysinmonth(t);
190        if (val > mdays - t->tm_mday) {
191          val -= mdays - t->tm_mday + 1;
192          t->tm_mday = 1;
193          if (!adjmon(t, '+', 1, 0))
194            return 0;
195        } else {
196          t->tm_mday += val;
197          val = 0;
198        }
199      }
200      break;
201    case '-':
202      while (val)
203        if (val >= t->tm_mday) {
204          val -= t->tm_mday;
205          t->tm_mday = 1;
206          if (!adjmon(t, '-', 1, 0))
207            return 0;
208          t->tm_mday = daysinmonth(t);
209        } else {
210          t->tm_mday -= val;
211          val = 0;
212        }
213      break;
214    default:
215      if (val > 0 && val <= daysinmonth(t))
216        t->tm_mday = val;
217      else
218        return 0;
219      break;
220  }
221
222  return mktime(t) != -1;
223}
224
225static int
226adjwday(struct tm *t, char type, int val, int istext)
227{
228  if (val < 0)
229    return 0;
230
231  switch (type) {
232    case '+':
233      if (istext)
234        if (val < t->tm_wday)
235          val = 7 - t->tm_wday + val;  /* early next week */
236        else
237          val -= t->tm_wday;           /* later this week */
238      else
239        val *= 7;                      /* "-W +5" == "5 weeks in the future" */
240      return adjday(t, '+', val);
241    case '-':
242      if (istext)
243        if (val > t->tm_wday)
244          val = 7 - val + t->tm_wday;  /* later last week */
245        else
246          val = t->tm_wday - val;      /* early this week */
247      else
248        val *= 7;                      /* "-W -5" == "5 weeks ago" */
249      return adjday(t, '-', val);
250    default:
251      if (val < t->tm_wday)
252        return adjday(t, '-', t->tm_wday - val);
253      else if (val > 6)
254        return 0;
255      else if (val > t->tm_wday)
256        return adjday(t, '+', val - t->tm_wday);
257  }
258  return 1;
259}
260
261static int
262adjhour(struct tm *t, char type, int val)
263{
264  if (val < 0)
265    return 0;
266
267  switch (type) {
268    case '+':
269      if (!adjday(t, '+', (t->tm_hour + val) / 24))
270        return 0;
271      val %= 24;
272      t->tm_hour += val;
273      if (t->tm_hour > 23)
274        t->tm_hour -= 24;
275      break;
276
277    case '-':
278      if (!adjday(t, '-', val / 24))
279        return 0;
280      val %= 24;
281      if (val > t->tm_hour) {
282        if (!adjday(t, '-', 1))
283          return 0;
284        val -= 24;
285      }
286      t->tm_hour -= val;
287      break;
288
289    default:
290      if (val > 23)
291        return 0;
292      t->tm_hour = val;
293  }
294
295  return mktime(t) != -1;
296}
297
298static int
299adjmin(struct tm *t, char type, int val)
300{
301  if (val < 0)
302    return 0;
303
304  switch (type) {
305    case '+':
306      if (!adjhour(t, '+', (t->tm_min + val) / 60))
307        return 0;
308      val %= 60;
309      t->tm_min += val;
310      if (t->tm_min > 59)
311        t->tm_min -= 60;
312      break;
313
314    case '-':
315      if (!adjhour(t, '-', val / 60))
316        return 0;
317      val %= 60;
318      if (val > t->tm_min) {
319        if (!adjhour(t, '-', 1))
320          return 0;
321        val -= 60;
322      }
323      t->tm_min -= val;
324      break;
325
326    default:
327      if (val > 59)
328        return 0;
329      t->tm_min = val;
330  }
331
332  return mktime(t) != -1;
333}
334
335const struct vary *
336vary_apply(const struct vary *v, struct tm *t)
337{
338  char type;
339  char which;
340  char *arg;
341  int len;
342  int val;
343
344  for (; v; v = v->next) {
345    type = *v->arg;
346    arg = v->arg;
347    if (type == '+' || type == '-')
348      arg++;
349    else
350      type = '\0';
351    len = strlen(arg);
352    if (len < 2)
353      return v;
354
355    if (strspn(arg, digits) != len-1) {
356      val = trans(trans_wday, arg);
357      if (val != -1) {
358          if (!adjwday(t, type, val, 1))
359            return v;
360      } else {
361        val = trans(trans_mon, arg);
362        if (val != -1) {
363          if (!adjmon(t, type, val, 1))
364            return v;
365        } else
366          return v;
367      }
368    } else {
369      val = atoi(arg);
370      which = arg[len-1];
371
372      switch (which) {
373        case 'M':
374          if (!adjmin(t, type, val))
375            return v;
376          break;
377        case 'H':
378          if (!adjhour(t, type, val))
379            return v;
380          break;
381        case 'd':
382          if (!adjday(t, type, val))
383            return v;
384          break;
385        case 'w':
386          if (!adjwday(t, type, val, 0))
387            return v;
388          break;
389        case 'm':
390          if (!adjmon(t, type, val, 0))
391            return v;
392          break;
393        case 'y':
394          if (!adjyear(t, type, val))
395            return v;
396          break;
397        default:
398          return v;
399      }
400    }
401  }
402  return 0;
403}
404
405void
406vary_destroy(struct vary *v)
407{
408  struct vary *n;
409
410  while (v) {
411    n = v->next;
412    free(v);
413    v = n;
414  }
415}
416