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[git/git.git] / date.c
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ecee9d9e
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1/*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6
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7#include <ctype.h>
8#include <time.h>
9
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10#include "cache.h"
11
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12static time_t my_mktime(struct tm *tm)
13{
14 static const int mdays[] = {
15 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
16 };
17 int year = tm->tm_year - 70;
18 int month = tm->tm_mon;
19 int day = tm->tm_mday;
20
21 if (year < 0 || year > 129) /* algo only works for 1970-2099 */
22 return -1;
23 if (month < 0 || month > 11) /* array bounds */
24 return -1;
25 if (month < 2 || (year + 2) % 4)
26 day--;
27 return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
28 tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
29}
30
31static const char *month_names[] = {
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32 "January", "February", "March", "April", "May", "June",
33 "July", "August", "September", "October", "November", "December"
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34};
35
36static const char *weekday_names[] = {
89967023 37 "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
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38};
39
f80cd783
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40/*
41 * The "tz" thing is passed in as this strange "decimal parse of tz"
42 * thing, which means that tz -0100 is passed in as the integer -100,
43 * even though it means "sixty minutes off"
44 */
45const char *show_date(unsigned long time, int tz)
46{
47 struct tm *tm;
48 time_t t;
49 static char timebuf[200];
50 int minutes;
51
52 minutes = tz < 0 ? -tz : tz;
fbab835c 53 minutes = (minutes / 100)*60 + (minutes % 100);
f80cd783 54 minutes = tz < 0 ? -minutes : minutes;
fbab835c 55 t = time + minutes * 60;
f80cd783
LT
56 tm = gmtime(&t);
57 if (!tm)
58 return NULL;
59 sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d %+05d",
60 weekday_names[tm->tm_wday],
61 month_names[tm->tm_mon],
62 tm->tm_mday,
63 tm->tm_hour, tm->tm_min, tm->tm_sec,
64 tm->tm_year + 1900, tz);
65 return timebuf;
66}
67
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68/*
69 * Check these. And note how it doesn't do the summer-time conversion.
70 *
71 * In my world, it's always summer, and things are probably a bit off
72 * in other ways too.
73 */
74static const struct {
75 const char *name;
76 int offset;
5e2a78a4 77 int dst;
89967023 78} timezone_names[] = {
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79 { "IDLW", -12, 0, }, /* International Date Line West */
80 { "NT", -11, 0, }, /* Nome */
81 { "CAT", -10, 0, }, /* Central Alaska */
82 { "HST", -10, 0, }, /* Hawaii Standard */
83 { "HDT", -10, 1, }, /* Hawaii Daylight */
84 { "YST", -9, 0, }, /* Yukon Standard */
85 { "YDT", -9, 1, }, /* Yukon Daylight */
86 { "PST", -8, 0, }, /* Pacific Standard */
87 { "PDT", -8, 1, }, /* Pacific Daylight */
88 { "MST", -7, 0, }, /* Mountain Standard */
89 { "MDT", -7, 1, }, /* Mountain Daylight */
90 { "CST", -6, 0, }, /* Central Standard */
91 { "CDT", -6, 1, }, /* Central Daylight */
92 { "EST", -5, 0, }, /* Eastern Standard */
93 { "EDT", -5, 1, }, /* Eastern Daylight */
94 { "AST", -3, 0, }, /* Atlantic Standard */
95 { "ADT", -3, 1, }, /* Atlantic Daylight */
96 { "WAT", -1, 0, }, /* West Africa */
97
98 { "GMT", 0, 0, }, /* Greenwich Mean */
99 { "UTC", 0, 0, }, /* Universal (Coordinated) */
100
101 { "WET", 0, 0, }, /* Western European */
102 { "BST", 0, 1, }, /* British Summer */
103 { "CET", +1, 0, }, /* Central European */
104 { "MET", +1, 0, }, /* Middle European */
105 { "MEWT", +1, 0, }, /* Middle European Winter */
106 { "MEST", +1, 1, }, /* Middle European Summer */
107 { "CEST", +1, 1, }, /* Central European Summer */
108 { "MESZ", +1, 1, }, /* Middle European Summer */
109 { "FWT", +1, 0, }, /* French Winter */
110 { "FST", +1, 1, }, /* French Summer */
111 { "EET", +2, 0, }, /* Eastern Europe, USSR Zone 1 */
92e2311b 112 { "EEST", +2, 1, }, /* Eastern European Daylight */
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113 { "WAST", +7, 0, }, /* West Australian Standard */
114 { "WADT", +7, 1, }, /* West Australian Daylight */
115 { "CCT", +8, 0, }, /* China Coast, USSR Zone 7 */
116 { "JST", +9, 0, }, /* Japan Standard, USSR Zone 8 */
117 { "EAST", +10, 0, }, /* Eastern Australian Standard */
118 { "EADT", +10, 1, }, /* Eastern Australian Daylight */
119 { "GST", +10, 0, }, /* Guam Standard, USSR Zone 9 */
120 { "NZT", +11, 0, }, /* New Zealand */
121 { "NZST", +11, 0, }, /* New Zealand Standard */
122 { "NZDT", +11, 1, }, /* New Zealand Daylight */
123 { "IDLE", +12, 0, }, /* International Date Line East */
89967023 124};
ecee9d9e 125
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126#define NR_TZ (sizeof(timezone_names) / sizeof(timezone_names[0]))
127
128static int match_string(const char *date, const char *str)
ecee9d9e 129{
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130 int i = 0;
131
132 for (i = 0; *date; date++, str++, i++) {
133 if (*date == *str)
134 continue;
135 if (toupper(*date) == toupper(*str))
136 continue;
137 if (!isalnum(*date))
138 break;
139 return 0;
140 }
141 return i;
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142}
143
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144static int skip_alpha(const char *date)
145{
146 int i = 0;
147 do {
148 i++;
149 } while (isalpha(date[i]));
150 return i;
151}
152
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153/*
154* Parse month, weekday, or timezone name
155*/
156static int match_alpha(const char *date, struct tm *tm, int *offset)
ecee9d9e 157{
89967023 158 int i;
ecee9d9e 159
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160 for (i = 0; i < 12; i++) {
161 int match = match_string(date, month_names[i]);
162 if (match >= 3) {
163 tm->tm_mon = i;
164 return match;
ecee9d9e 165 }
89967023 166 }
ecee9d9e 167
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168 for (i = 0; i < 7; i++) {
169 int match = match_string(date, weekday_names[i]);
170 if (match >= 3) {
171 tm->tm_wday = i;
172 return match;
173 }
174 }
ecee9d9e 175
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176 for (i = 0; i < NR_TZ; i++) {
177 int match = match_string(date, timezone_names[i].name);
178 if (match >= 3) {
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179 int off = timezone_names[i].offset;
180
181 /* This is bogus, but we like summer */
182 off += timezone_names[i].dst;
183
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184 /* Only use the tz name offset if we don't have anything better */
185 if (*offset == -1)
186 *offset = 60*off;
187
89967023 188 return match;
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189 }
190 }
ecee9d9e 191
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192 if (match_string(date, "PM") == 2) {
193 if (tm->tm_hour > 0 && tm->tm_hour < 12)
194 tm->tm_hour += 12;
195 return 2;
196 }
197
89967023 198 /* BAD CRAP */
68849b54 199 return skip_alpha(date);
89967023 200}
ecee9d9e 201
198b0fb6 202static int is_date(int year, int month, int day, struct tm *tm)
89967023 203{
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204 if (month > 0 && month < 13 && day > 0 && day < 32) {
205 if (year == -1) {
206 tm->tm_mon = month-1;
207 tm->tm_mday = day;
208 return 1;
89967023 209 }
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210 if (year >= 1970 && year < 2100) {
211 year -= 1900;
212 } else if (year > 70 && year < 100) {
213 /* ok */
214 } else if (year < 38) {
215 year += 100;
216 } else
217 return 0;
218
219 tm->tm_mon = month-1;
220 tm->tm_mday = day;
221 tm->tm_year = year;
222 return 1;
89967023 223 }
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224 return 0;
225}
ecee9d9e 226
26a2d8ae 227static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
198b0fb6
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228{
229 long num2, num3;
230
231 num2 = strtol(end+1, &end, 10);
232 num3 = -1;
233 if (*end == c && isdigit(end[1]))
234 num3 = strtol(end+1, &end, 10);
235
236 /* Time? Date? */
89967023 237 switch (c) {
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238 case ':':
239 if (num3 < 0)
240 num3 = 0;
241 if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
242 tm->tm_hour = num;
243 tm->tm_min = num2;
244 tm->tm_sec = num3;
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245 break;
246 }
198b0fb6 247 return 0;
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248
249 case '-':
250 case '/':
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251 if (num > 70) {
252 /* yyyy-mm-dd? */
253 if (is_date(num, num2, num3, tm))
254 break;
255 /* yyyy-dd-mm? */
256 if (is_date(num, num3, num2, tm))
89967023 257 break;
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258 }
259 /* mm/dd/yy ? */
260 if (is_date(num3, num2, num, tm))
89967023 261 break;
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262 /* dd/mm/yy ? */
263 if (is_date(num3, num, num2, tm))
264 break;
265 return 0;
266 }
267 return end - date;
268}
269
270/*
271 * We've seen a digit. Time? Year? Date?
272 */
26a2d8ae 273static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
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274{
275 int n;
276 char *end;
277 unsigned long num;
278
279 num = strtoul(date, &end, 10);
280
281 /*
282 * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
283 */
284 if (num > 946684800) {
285 time_t time = num;
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286 if (gmtime_r(&time, tm)) {
287 *tm_gmt = 1;
198b0fb6 288 return end - date;
9cb480f2 289 }
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290 }
291
292 /*
293 * Check for special formats: num[:-/]num[same]num
294 */
295 switch (*end) {
296 case ':':
297 case '/':
298 case '-':
299 if (isdigit(end[1])) {
300 int match = match_multi_number(num, *end, date, end, tm);
301 if (match)
302 return match;
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303 }
304 }
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305
306 /*
307 * None of the special formats? Try to guess what
308 * the number meant. We use the number of digits
309 * to make a more educated guess..
310 */
311 n = 0;
312 do {
313 n++;
314 } while (isdigit(date[n]));
315
316 /* Four-digit year or a timezone? */
317 if (n == 4) {
318 if (num <= 1200 && *offset == -1) {
319 unsigned int minutes = num % 100;
320 unsigned int hours = num / 100;
321 *offset = hours*60 + minutes;
322 } else if (num > 1900 && num < 2100)
323 tm->tm_year = num - 1900;
324 return n;
325 }
326
327 /*
328 * NOTE! We will give precedence to day-of-month over month or
329 * year numebers in the 1-12 range. So 05 is always "mday 5",
330 * unless we already have a mday..
331 *
332 * IOW, 01 Apr 05 parses as "April 1st, 2005".
333 */
334 if (num > 0 && num < 32 && tm->tm_mday < 0) {
335 tm->tm_mday = num;
336 return n;
337 }
338
339 /* Two-digit year? */
340 if (n == 2 && tm->tm_year < 0) {
341 if (num < 10 && tm->tm_mday >= 0) {
342 tm->tm_year = num + 100;
343 return n;
344 }
345 if (num >= 70) {
346 tm->tm_year = num;
347 return n;
348 }
349 }
350
351 if (num > 0 && num < 32) {
352 tm->tm_mday = num;
353 } else if (num > 1900) {
354 tm->tm_year = num - 1900;
355 } else if (num > 70) {
356 tm->tm_year = num;
357 } else if (num > 0 && num < 13) {
358 tm->tm_mon = num-1;
359 }
ecee9d9e 360
198b0fb6 361 return n;
89967023 362}
ecee9d9e 363
26a2d8ae 364static int match_tz(const char *date, int *offp)
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LT
365{
366 char *end;
367 int offset = strtoul(date+1, &end, 10);
368 int min, hour;
198b0fb6 369 int n = end - date - 1;
ecee9d9e 370
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371 min = offset % 100;
372 hour = offset / 100;
ecee9d9e 373
198b0fb6
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374 /*
375 * Don't accept any random crap.. At least 3 digits, and
376 * a valid minute. We might want to check that the minutes
377 * are divisible by 30 or something too.
378 */
68849b54
LT
379 if (min < 60 && n > 2) {
380 offset = hour*60+min;
381 if (*date == '-')
382 offset = -offset;
ecee9d9e 383
68849b54
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384 *offp = offset;
385 }
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386 return end - date;
387}
ecee9d9e 388
89967023
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389/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
390 (i.e. English) day/month names, and it doesn't work correctly with %z. */
26a2d8ae 391void parse_date(const char *date, char *result, int maxlen)
89967023
LT
392{
393 struct tm tm;
9cb480f2 394 int offset, sign, tm_gmt;
89967023 395 time_t then;
ecee9d9e 396
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397 memset(&tm, 0, sizeof(tm));
398 tm.tm_year = -1;
399 tm.tm_mon = -1;
400 tm.tm_mday = -1;
eaa85129
LT
401 tm.tm_isdst = -1;
402 offset = -1;
9cb480f2 403 tm_gmt = 0;
89967023
LT
404
405 for (;;) {
406 int match = 0;
407 unsigned char c = *date;
408
409 /* Stop at end of string or newline */
410 if (!c || c == '\n')
411 break;
412
413 if (isalpha(c))
414 match = match_alpha(date, &tm, &offset);
415 else if (isdigit(c))
9cb480f2 416 match = match_digit(date, &tm, &offset, &tm_gmt);
89967023
LT
417 else if ((c == '-' || c == '+') && isdigit(date[1]))
418 match = match_tz(date, &offset);
419
420 if (!match) {
421 /* BAD CRAP */
422 match = 1;
423 }
424
425 date += match;
426 }
ecee9d9e 427
eaa85129
LT
428 /* mktime uses local timezone */
429 then = my_mktime(&tm);
430 if (offset == -1)
431 offset = (then - mktime(&tm)) / 60;
432
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ET
433 if (then == -1)
434 return;
435
9cb480f2
JH
436 if (!tm_gmt)
437 then -= offset * 60;
ecee9d9e 438
7f26664f
LT
439 sign = '+';
440 if (offset < 0) {
441 offset = -offset;
442 sign = '-';
443 }
444
445 snprintf(result, maxlen, "%lu %c%02d%02d", then, sign, offset/60, offset % 60);
ecee9d9e
ET
446}
447
448void datestamp(char *buf, int bufsize)
449{
450 time_t now;
451 int offset;
452
453 time(&now);
454
455 offset = my_mktime(localtime(&now)) - now;
456 offset /= 60;
457
458 snprintf(buf, bufsize, "%lu %+05d", now, offset/60*100 + offset%60);
459}