| /* Copyright (C) 1991-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <errno.h> |
| #include <time.h> |
| |
| #define SECS_PER_HOUR (60 * 60) |
| #define SECS_PER_DAY (SECS_PER_HOUR * 24) |
| |
| /* Compute the `struct tm' representation of *T, |
| offset OFFSET seconds east of UTC, |
| and store year, yday, mon, mday, wday, hour, min, sec into *TP. |
| Return nonzero if successful. */ |
| int |
| __offtime (t, offset, tp) |
| const time_t *t; |
| long int offset; |
| struct tm *tp; |
| { |
| time_t days, rem, y; |
| const unsigned short int *ip; |
| |
| days = *t / SECS_PER_DAY; |
| rem = *t % SECS_PER_DAY; |
| rem += offset; |
| while (rem < 0) |
| { |
| rem += SECS_PER_DAY; |
| --days; |
| } |
| while (rem >= SECS_PER_DAY) |
| { |
| rem -= SECS_PER_DAY; |
| ++days; |
| } |
| tp->tm_hour = rem / SECS_PER_HOUR; |
| rem %= SECS_PER_HOUR; |
| tp->tm_min = rem / 60; |
| tp->tm_sec = rem % 60; |
| /* January 1, 1970 was a Thursday. */ |
| tp->tm_wday = (4 + days) % 7; |
| if (tp->tm_wday < 0) |
| tp->tm_wday += 7; |
| y = 1970; |
| |
| #define DIV(a, b) ((a) / (b) - ((a) % (b) < 0)) |
| #define LEAPS_THRU_END_OF(y) (DIV (y, 4) - DIV (y, 100) + DIV (y, 400)) |
| |
| while (days < 0 || days >= (__isleap (y) ? 366 : 365)) |
| { |
| /* Guess a corrected year, assuming 365 days per year. */ |
| time_t yg = y + days / 365 - (days % 365 < 0); |
| |
| /* Adjust DAYS and Y to match the guessed year. */ |
| days -= ((yg - y) * 365 |
| + LEAPS_THRU_END_OF (yg - 1) |
| - LEAPS_THRU_END_OF (y - 1)); |
| y = yg; |
| } |
| tp->tm_year = y - 1900; |
| if (tp->tm_year != y - 1900) |
| { |
| /* The year cannot be represented due to overflow. */ |
| __set_errno (EOVERFLOW); |
| return 0; |
| } |
| tp->tm_yday = days; |
| ip = __mon_yday[__isleap(y)]; |
| for (y = 11; days < (long int) ip[y]; --y) |
| continue; |
| days -= ip[y]; |
| tp->tm_mon = y; |
| tp->tm_mday = days + 1; |
| return 1; |
| } |