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author | Zack Weinberg <zackw@panix.com> | 2017-06-08 15:39:03 -0400 |
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committer | Zack Weinberg <zackw@panix.com> | 2017-06-08 15:39:03 -0400 |
commit | 5046dbb4a7eba5eccfd258f92f4735c9ffc8d069 (patch) | |
tree | 4470480d904b65cf14ca524f96f79eca818c3eaf /REORG.TODO/time/offtime.c | |
parent | 199fc19d3aaaf57944ef036e15904febe877fc93 (diff) | |
download | glibc-5046dbb4a7eba5eccfd258f92f4735c9ffc8d069.tar glibc-5046dbb4a7eba5eccfd258f92f4735c9ffc8d069.tar.gz glibc-5046dbb4a7eba5eccfd258f92f4735c9ffc8d069.tar.bz2 glibc-5046dbb4a7eba5eccfd258f92f4735c9ffc8d069.zip |
Prepare for radical source tree reorganization.zack/build-layout-experiment
All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).
Diffstat (limited to 'REORG.TODO/time/offtime.c')
-rw-r--r-- | REORG.TODO/time/offtime.c | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/REORG.TODO/time/offtime.c b/REORG.TODO/time/offtime.c new file mode 100644 index 0000000000..75a28fed84 --- /dev/null +++ b/REORG.TODO/time/offtime.c @@ -0,0 +1,86 @@ +/* Copyright (C) 1991-2017 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 (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; +} |