15f28198e125ae08af937ca7f302c7a18c88f22a
[git/git.git] / date.c
1 /*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6
7 #include <stdio.h>
8 #include <stdlib.h>
9 #include <string.h>
10 #include <ctype.h>
11 #include <time.h>
12
13 static time_t my_mktime(struct tm *tm)
14 {
15 static const int mdays[] = {
16 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
17 };
18 int year = tm->tm_year - 70;
19 int month = tm->tm_mon;
20 int day = tm->tm_mday;
21
22 if (year < 0 || year > 129) /* algo only works for 1970-2099 */
23 return -1;
24 if (month < 0 || month > 11) /* array bounds */
25 return -1;
26 if (month < 2 || (year + 2) % 4)
27 day--;
28 return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
29 tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
30 }
31
32 static const char *month_names[] = {
33 "January", "February", "March", "April", "May", "June",
34 "July", "August", "September", "October", "November", "December"
35 };
36
37 static const char *weekday_names[] = {
38 "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
39 };
40
41 /*
42 * Check these. And note how it doesn't do the summer-time conversion.
43 *
44 * In my world, it's always summer, and things are probably a bit off
45 * in other ways too.
46 */
47 static const struct {
48 const char *name;
49 int offset;
50 } timezone_names[] = {
51 { "IDLW", -12 }, /* International Date Line West */
52 { "NT", -11 }, /* Nome */
53 { "CAT", -10 }, /* Central Alaska */
54 { "HST", -10 }, /* Hawaii Standard */
55 { "HDT", -9 }, /* Hawaii Daylight */
56 { "YDT", -8 }, /* Yukon Daylight */
57 { "YST", -9 }, /* Yukon Standard */
58 { "PST", -8 }, /* Pacific Standard */
59 { "PDT", -7 }, /* Pacific Daylight */
60 { "MST", -7 }, /* Mountain Standard */
61 { "MDT", -6 }, /* Mountain Daylight */
62 { "CST", -6 }, /* Central Standard */
63 { "CDT", -5 }, /* Central Daylight */
64 { "EST", -5 }, /* Eastern Standard */
65 { "EDT", -4 }, /* Eastern Daylight */
66 { "AST", -3 }, /* Atlantic Standard */
67 { "ADT", -2 }, /* Atlantic Daylight */
68 { "WAT", -1 }, /* West Africa */
69
70 { "GMT", 0 }, /* Greenwich Mean */
71 { "UTC", 0 }, /* Universal (Coordinated) */
72
73 { "WET", 0 }, /* Western European */
74 { "BST", 0 }, /* British Summer */
75 { "CET", +1 }, /* Central European */
76 { "MET", +1 }, /* Middle European */
77 { "MEWT", +1 }, /* Middle European Winter */
78 { "MEST", +2 }, /* Middle European Summer */
79 { "CEST", +2 }, /* Central European Summer */
80 { "MESZ", +1 }, /* Middle European Summer */
81 { "FWT", +1 }, /* French Winter */
82 { "FST", +2 }, /* French Summer */
83 { "EET", +2 }, /* Eastern Europe, USSR Zone 1 */
84 { "WAST", +7 }, /* West Australian Standard */
85 { "WADT", +8 }, /* West Australian Daylight */
86 { "CCT", +8 }, /* China Coast, USSR Zone 7 */
87 { "JST", +9 }, /* Japan Standard, USSR Zone 8 */
88 { "EAST", +10 }, /* Eastern Australian Standard */
89 { "EADT", +11 }, /* Eastern Australian Daylight */
90 { "GST", +10 }, /* Guam Standard, USSR Zone 9 */
91 { "NZT", +11 }, /* New Zealand */
92 { "NZST", +11 }, /* New Zealand Standard */
93 { "NZDT", +12 }, /* New Zealand Daylight */
94 { "IDLE", +12 }, /* International Date Line East */
95 };
96
97 #define NR_TZ (sizeof(timezone_names) / sizeof(timezone_names[0]))
98
99 static int match_string(const char *date, const char *str)
100 {
101 int i = 0;
102
103 for (i = 0; *date; date++, str++, i++) {
104 if (*date == *str)
105 continue;
106 if (toupper(*date) == toupper(*str))
107 continue;
108 if (!isalnum(*date))
109 break;
110 return 0;
111 }
112 return i;
113 }
114
115 /*
116 * Parse month, weekday, or timezone name
117 */
118 static int match_alpha(const char *date, struct tm *tm, int *offset)
119 {
120 int i;
121
122 for (i = 0; i < 12; i++) {
123 int match = match_string(date, month_names[i]);
124 if (match >= 3) {
125 tm->tm_mon = i;
126 return match;
127 }
128 }
129
130 for (i = 0; i < 7; i++) {
131 int match = match_string(date, weekday_names[i]);
132 if (match >= 3) {
133 tm->tm_wday = i;
134 return match;
135 }
136 }
137
138 for (i = 0; i < NR_TZ; i++) {
139 int match = match_string(date, timezone_names[i].name);
140 if (match >= 3) {
141 *offset = 60*timezone_names[i].offset;
142 return match;
143 }
144 }
145
146 /* BAD CRAP */
147 return 0;
148 }
149
150 static int match_digit(char *date, struct tm *tm, int *offset)
151 {
152 char *end, c;
153 unsigned long num, num2, num3;
154
155 num = strtoul(date, &end, 10);
156
157 /* Time? num:num[:num] */
158 if (num < 24 && end[0] == ':' && isdigit(end[1])) {
159 tm->tm_hour = num;
160 num = strtoul(end+1, &end, 10);
161 if (num < 60) {
162 tm->tm_min = num;
163 if (end[0] == ':' && isdigit(end[1])) {
164 num = strtoul(end+1, &end, 10);
165 if (num < 61)
166 tm->tm_sec = num;
167 }
168 }
169 return end - date;
170 }
171
172 /* Year? Day of month? Numeric date-string?*/
173 c = *end;
174 switch (c) {
175 default:
176 if (num > 0 && num < 32) {
177 tm->tm_mday = num;
178 break;
179 }
180 if (num > 1900) {
181 tm->tm_year = num - 1900;
182 break;
183 }
184 if (num > 70) {
185 tm->tm_year = num;
186 break;
187 }
188 break;
189
190 case '-':
191 case '/':
192 if (num && num < 32 && isdigit(end[1])) {
193 num2 = strtoul(end+1, &end, 10);
194 if (!num2 || num2 > 31)
195 break;
196 if (num > 12) {
197 if (num2 > 12)
198 break;
199 num3 = num;
200 num = num2;
201 num2 = num3;
202 }
203 tm->tm_mon = num - 1;
204 tm->tm_mday = num2;
205 if (*end == c && isdigit(end[1])) {
206 num3 = strtoul(end+1, &end, 10);
207 if (num3 > 1900)
208 num3 -= 1900;
209 else if (num3 < 38)
210 num3 += 100;
211 tm->tm_year = num3;
212 }
213 break;
214 }
215 }
216
217 return end - date;
218
219 }
220
221 static int match_tz(char *date, int *offp)
222 {
223 char *end;
224 int offset = strtoul(date+1, &end, 10);
225 int min, hour;
226
227 min = offset % 100;
228 hour = offset / 100;
229
230 offset = hour*60+min;
231 if (*date == '-')
232 offset = -offset;
233
234 *offp = offset;
235 return end - date;
236 }
237
238 /* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
239 (i.e. English) day/month names, and it doesn't work correctly with %z. */
240 void parse_date(char *date, char *result, int maxlen)
241 {
242 struct tm tm;
243 int offset;
244 time_t then;
245
246 memset(&tm, 0, sizeof(tm));
247 tm.tm_year = -1;
248 tm.tm_mon = -1;
249 tm.tm_mday = -1;
250 tm.tm_isdst = -1;
251 offset = -1;
252
253 for (;;) {
254 int match = 0;
255 unsigned char c = *date;
256
257 /* Stop at end of string or newline */
258 if (!c || c == '\n')
259 break;
260
261 if (isalpha(c))
262 match = match_alpha(date, &tm, &offset);
263 else if (isdigit(c))
264 match = match_digit(date, &tm, &offset);
265 else if ((c == '-' || c == '+') && isdigit(date[1]))
266 match = match_tz(date, &offset);
267
268 if (!match) {
269 /* BAD CRAP */
270 match = 1;
271 }
272
273 date += match;
274 }
275
276 /* mktime uses local timezone */
277 then = my_mktime(&tm);
278 if (offset == -1)
279 offset = (then - mktime(&tm)) / 60;
280
281 if (then == -1)
282 return;
283
284 then -= offset * 60;
285
286 snprintf(result, maxlen, "%lu %+03d%02d", then, offset/60, offset % 60);
287 }
288
289 void datestamp(char *buf, int bufsize)
290 {
291 time_t now;
292 int offset;
293
294 time(&now);
295
296 offset = my_mktime(localtime(&now)) - now;
297 offset /= 60;
298
299 snprintf(buf, bufsize, "%lu %+05d", now, offset/60*100 + offset%60);
300 }