]>
Commit | Line | Data |
---|---|---|
b168057a | 1 | /* Copyright (C) 1991-2015 Free Software Foundation, Inc. |
fd26970f | 2 | This file is part of the GNU C Library. |
28f540f4 | 3 | |
fd26970f | 4 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
28f540f4 | 8 | |
fd26970f UD |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 12 | Lesser General Public License for more details. |
28f540f4 | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ | |
28f540f4 | 17 | |
f7501ae6 | 18 | #include <errno.h> |
28f540f4 RM |
19 | #include <time.h> |
20 | ||
28f540f4 RM |
21 | #define SECS_PER_HOUR (60 * 60) |
22 | #define SECS_PER_DAY (SECS_PER_HOUR * 24) | |
23 | ||
c2216480 RM |
24 | /* Compute the `struct tm' representation of *T, |
25 | offset OFFSET seconds east of UTC, | |
fe0ec73e UD |
26 | and store year, yday, mon, mday, wday, hour, min, sec into *TP. |
27 | Return nonzero if successful. */ | |
28 | int | |
fd26970f UD |
29 | __offtime (t, offset, tp) |
30 | const time_t *t; | |
31 | long int offset; | |
32 | struct tm *tp; | |
28f540f4 | 33 | { |
f196c7f7 | 34 | time_t days, rem, y; |
9a0a462c | 35 | const unsigned short int *ip; |
28f540f4 | 36 | |
28f540f4 RM |
37 | days = *t / SECS_PER_DAY; |
38 | rem = *t % SECS_PER_DAY; | |
39 | rem += offset; | |
40 | while (rem < 0) | |
41 | { | |
42 | rem += SECS_PER_DAY; | |
43 | --days; | |
44 | } | |
45 | while (rem >= SECS_PER_DAY) | |
46 | { | |
47 | rem -= SECS_PER_DAY; | |
48 | ++days; | |
49 | } | |
c2216480 | 50 | tp->tm_hour = rem / SECS_PER_HOUR; |
28f540f4 | 51 | rem %= SECS_PER_HOUR; |
c2216480 RM |
52 | tp->tm_min = rem / 60; |
53 | tp->tm_sec = rem % 60; | |
28f540f4 | 54 | /* January 1, 1970 was a Thursday. */ |
c2216480 RM |
55 | tp->tm_wday = (4 + days) % 7; |
56 | if (tp->tm_wday < 0) | |
57 | tp->tm_wday += 7; | |
28f540f4 | 58 | y = 1970; |
b20e47cb | 59 | |
fe0ec73e UD |
60 | #define DIV(a, b) ((a) / (b) - ((a) % (b) < 0)) |
61 | #define LEAPS_THRU_END_OF(y) (DIV (y, 4) - DIV (y, 100) + DIV (y, 400)) | |
b20e47cb RM |
62 | |
63 | while (days < 0 || days >= (__isleap (y) ? 366 : 365)) | |
28f540f4 | 64 | { |
b20e47cb | 65 | /* Guess a corrected year, assuming 365 days per year. */ |
f196c7f7 | 66 | time_t yg = y + days / 365 - (days % 365 < 0); |
b20e47cb RM |
67 | |
68 | /* Adjust DAYS and Y to match the guessed year. */ | |
69 | days -= ((yg - y) * 365 | |
70 | + LEAPS_THRU_END_OF (yg - 1) | |
71 | - LEAPS_THRU_END_OF (y - 1)); | |
72 | y = yg; | |
28f540f4 | 73 | } |
c2216480 | 74 | tp->tm_year = y - 1900; |
fe0ec73e | 75 | if (tp->tm_year != y - 1900) |
f7501ae6 UD |
76 | { |
77 | /* The year cannot be represented due to overflow. */ | |
78 | __set_errno (EOVERFLOW); | |
79 | return 0; | |
80 | } | |
c2216480 | 81 | tp->tm_yday = days; |
80fd7387 | 82 | ip = __mon_yday[__isleap(y)]; |
9a0a462c | 83 | for (y = 11; days < (long int) ip[y]; --y) |
80fd7387 RM |
84 | continue; |
85 | days -= ip[y]; | |
c2216480 RM |
86 | tp->tm_mon = y; |
87 | tp->tm_mday = days + 1; | |
fe0ec73e | 88 | return 1; |
28f540f4 | 89 | } |