vary.c revision 28025 
1#include <time.h>
2#include <string.h>
3#include <stdlib.h>
4#include "vary.h"
5
6struct trans {
7  int val;
8  char *str;
9};
10
11static struct trans trans_mon[] = {
12  { 1, "january" }, { 2, "february" }, { 3, "march" }, { 4, "april" },
13  { 6, "june" }, { 7, "july" }, { 8, "august" }, { 9, "september" },
14  { 10, "october" }, { 11, "november" }, { 12, "december" },
15  { -1, NULL }
16};
17
18static struct trans trans_wday[] = {
19  { 0, "sunday" }, { 1, "monday" }, { 2, "tuesday" }, { 3, "wednesday" },
20  { 4, "thursday" }, { 5, "friday" }, { 6, "saturday" },
21  { -1, NULL }
22};
23
24static char digits[] = "0123456789";
25
26static int
27trans(const struct trans t[], const char *arg)
28{
29  int f;
30
31  for (f = 0; t[f].val != -1; f++)
32    if (!strncasecmp(t[f].str, arg, 3) ||
33        !strncasecmp(t[f].str, arg, strlen(t[f].str)))
34      return t[f].val;
35
36  return -1;
37}
38
39struct vary *
40vary_append(struct vary *v, char *arg)
41{
42  struct vary *result, **nextp;
43
44  if (v) {
45    result = v;
46    while (v->next)
47      v = v->next;
48    nextp = &v->next;
49  } else
50    nextp = &result;
51
52  *nextp = (struct vary *)malloc(sizeof(struct vary));
53  (*nextp)->arg = arg;
54  (*nextp)->next = NULL;
55  return result;
56}
57
58static int mdays[12] = { 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
59
60static int
61daysinmonth(const struct tm *t)
62{
63  int year;
64
65  year = t->tm_year + 1900;
66
67  if (t->tm_mon == 1)
68    if (!(year % 400))
69      return 29;
70    else if (!(year % 100))
71      return 28;
72    else if (!(year % 4))
73      return 29;
74    else
75      return 28;
76  else if (t->tm_mon >= 0 && t->tm_mon < 12)
77    return mdays[t->tm_mon];
78
79  return 0;
80}
81
82
83static int
84adjyear(struct tm *t, char type, int val)
85{
86  switch (type) {
87    case '+':
88      t->tm_year += val;
89      break;
90    case '-':
91      t->tm_year -= val;
92      break;
93    default:
94      t->tm_year = val;
95      if (t->tm_year < 69)
96      	t->tm_year += 100;		/* as per date.c */
97      else if (t->tm_year > 1900)
98        t->tm_year -= 1900;             /* struct tm holds years since 1900 */
99      break;
100  }
101  return mktime(t) != -1;
102}
103
104static int
105adjmon(struct tm *t, char type, int val, int istext)
106{
107  if (val < 0)
108    return 0;
109
110  switch (type) {
111    case '+':
112      if (istext)
113        if (val <= t->tm_mon)
114          val += 11 - t->tm_mon;	/* early next year */
115        else
116          val -= t->tm_mon + 1;		/* later this year */
117      if (!adjyear(t, '+', (t->tm_mon + val) / 12))
118        return 0;
119      val %= 12;
120      t->tm_mon += val;
121      if (t->tm_mon > 11)
122        t->tm_mon -= 12;
123      break;
124
125    case '-':
126      if (istext)
127        if (val-1 > t->tm_mon)
128          val = 13 - val + t->tm_mon;	/* later last year */
129        else
130          val = t->tm_mon - val + 1;	/* early this year */
131      if (!adjyear(t, '-', val / 12))
132        return 0;
133      val %= 12;
134      if (val > t->tm_mon) {
135        if (!adjyear(t, '-', 1))
136          return 0;
137        val -= 12;
138      }
139      t->tm_mon -= val;
140      break;
141
142    default:
143      if (val > 12 || val < 1)
144        return 0;
145      t->tm_mon = --val;
146  }
147
148  return mktime(t) != -1;
149}
150
151static int
152adjday(struct tm *t, char type, int val)
153{
154  int mdays;
155  switch (type) {
156    case '+':
157      while (val) {
158        mdays = daysinmonth(t);
159        if (val > mdays - t->tm_mday) {
160          val -= mdays - t->tm_mday + 1;
161          t->tm_mday = 1;
162          if (!adjmon(t, '+', 1, 0))
163            return 0;
164        } else {
165          t->tm_mday += val;
166          val = 0;
167        }
168      }
169      break;
170    case '-':
171      while (val)
172        if (val >= t->tm_mday) {
173          val -= t->tm_mday;
174          t->tm_mday = 1;
175          if (!adjmon(t, '-', 1, 0))
176            return 0;
177          t->tm_mday = daysinmonth(t);
178        } else {
179          t->tm_mday -= val;
180          val = 0;
181        }
182      break;
183    default:
184      if (val > 0 && val <= daysinmonth(t))
185        t->tm_mday = val;
186      else
187        return 0;
188      break;
189  }
190
191  return mktime(t) != -1;
192}
193
194static int
195adjwday(struct tm *t, char type, int val, int istext)
196{
197  if (val < 0)
198    return 0;
199
200  switch (type) {
201    case '+':
202      if (istext)
203        if (val < t->tm_wday)
204          val = 7 - t->tm_wday + val;  /* early next week */
205        else
206          val -= t->tm_wday;           /* later this week */
207      else
208        val *= 7;                      /* "-W +5" == "5 weeks in the future" */
209      return adjday(t, '+', val);
210    case '-':
211      if (istext)
212        if (val > t->tm_wday)
213          val = 7 - val + t->tm_wday;  /* later last week */
214        else
215          val = t->tm_wday - val;      /* early this week */
216      else
217        val *= 7;                      /* "-W -5" == "5 weeks ago" */
218      return adjday(t, '-', val);
219    default:
220      if (val < t->tm_wday)
221        return adjday(t, '-', t->tm_wday - val);
222      else if (val > 6)
223        return 0;
224      else if (val > t->tm_wday)
225        return adjday(t, '+', val - t->tm_wday);
226  }
227  return 1;
228}
229
230static int
231adjhour(struct tm *t, char type, int val)
232{
233  if (val < 0)
234    return 0;
235
236  switch (type) {
237    case '+':
238      if (!adjday(t, '+', (t->tm_hour + val) / 24))
239        return 0;
240      val %= 24;
241      t->tm_hour += val;
242      if (t->tm_hour > 23)
243        t->tm_hour -= 24;
244      break;
245
246    case '-':
247      if (!adjday(t, '-', val / 24))
248        return 0;
249      val %= 24;
250      if (val > t->tm_hour) {
251        if (!adjday(t, '-', 1))
252          return 0;
253        val -= 24;
254      }
255      t->tm_hour -= val;
256      break;
257
258    default:
259      if (val > 23)
260        return 0;
261      t->tm_hour = val;
262  }
263
264  return mktime(t) != -1;
265}
266
267static int
268adjmin(struct tm *t, char type, int val)
269{
270  if (val < 0)
271    return 0;
272
273  switch (type) {
274    case '+':
275      if (!adjhour(t, '+', (t->tm_min + val) / 60))
276        return 0;
277      val %= 60;
278      t->tm_min += val;
279      if (t->tm_min > 59)
280        t->tm_min -= 60;
281      break;
282
283    case '-':
284      if (!adjhour(t, '-', val / 60))
285        return 0;
286      val %= 60;
287      if (val > t->tm_min) {
288        if (!adjhour(t, '-', 1))
289          return 0;
290        val -= 60;
291      }
292      t->tm_min -= val;
293      break;
294
295    default:
296      if (val > 59)
297        return 0;
298      t->tm_min = val;
299  }
300
301  return mktime(t) != -1;
302}
303
304const struct vary *
305vary_apply(const struct vary *v, struct tm *t)
306{
307  char type;
308  char which;
309  char *arg;
310  int len;
311  int val;
312
313  for (; v; v = v->next) {
314    type = *v->arg;
315    arg = v->arg;
316    if (type == '+' || type == '-')
317      arg++;
318    else
319      type = '\0';
320    len = strlen(arg);
321    if (len < 2)
322      return v;
323
324    if (strspn(arg, digits) != len-1) {
325      val = trans(trans_wday, arg);
326      if (val != -1) {
327          if (!adjwday(t, type, val, 1))
328            return v;
329      } else {
330        val = trans(trans_mon, arg);
331        if (val != -1) {
332          if (!adjmon(t, type, val, 1))
333            return v;
334        } else
335          return v;
336      }
337    } else {
338      val = atoi(arg);
339      which = arg[len-1];
340
341      switch (which) {
342        case 'M':
343          if (!adjmin(t, type, val))
344            return v;
345          break;
346        case 'H':
347          if (!adjhour(t, type, val))
348            return v;
349          break;
350        case 'd':
351          if (!adjday(t, type, val))
352            return v;
353          break;
354        case 'w':
355          if (!adjwday(t, type, val, 0))
356            return v;
357          break;
358        case 'm':
359          if (!adjmon(t, type, val, 0))
360            return v;
361          break;
362        case 'y':
363          if (!adjyear(t, type, val))
364            return v;
365          break;
366        default:
367          return v;
368      }
369    }
370  }
371  return 0;
372}
373
374void
375vary_destroy(struct vary *v)
376{
377  struct vary *n;
378
379  while (v) {
380    n = v->next;
381    free(v);
382    v = n;
383  }
384}
385