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fc389d3a83
This incorporates: 2018-09-10 timespec: fix resolution confusion 2018-09-09 mktime: simplify in prep for glibc merge 2018-09-07 intprops: minor clarification of code 2018-09-06 stddef: Override max_align_t on NetBSD 8.0/x86 2018-09-06 fcntl: Fix F_DUPFD_CLOEXEC behaviour on Haiku 2018-09-06 strtoll, strtoull: Rely on limits-h module 2018-09-06 limits-h: Provide numerical limits macros 2018-09-06 fcntl: Don't access nonexistent optional argument 2018-09-02 mktime: fix unlikely race+overflow bug 2018-08-31 mktime, timegm: simplify glibc time64_t 2018-08-31 mktime, timegm: simplify merge to glibc * build-aux/config.guess, build-aux/config.sub: * lib/dtotimespec.c, lib/fcntl.c, lib/intprops.h: * lib/limits.in.h, lib/mktime-internal.h, lib/mktime.c: * lib/stat-time.h, lib/strtol.c, lib/timegm.c: * lib/timespec-add.c, lib/timespec-sub.c, lib/timespec.h: * lib/utimens.c, m4/limits-h.m4, m4/stddef_h.m4: Copy from Gnulib.
71 lines
1.9 KiB
C
71 lines
1.9 KiB
C
/* Subtract two struct timespec values.
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Copyright (C) 2011-2018 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Paul Eggert. */
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/* Return the difference between two timespec values A and B. On
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overflow, return an extremal value. This assumes 0 <= tv_nsec <
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TIMESPEC_HZ. */
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#include <config.h>
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#include "timespec.h"
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#include "intprops.h"
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struct timespec
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timespec_sub (struct timespec a, struct timespec b)
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{
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time_t rs = a.tv_sec;
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time_t bs = b.tv_sec;
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int ns = a.tv_nsec - b.tv_nsec;
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int rns = ns;
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time_t tmin = TYPE_MINIMUM (time_t);
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time_t tmax = TYPE_MAXIMUM (time_t);
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if (ns < 0)
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{
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rns = ns + TIMESPEC_HZ;
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if (bs < tmax)
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bs++;
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else if (- TYPE_SIGNED (time_t) < rs)
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rs--;
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else
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goto low_overflow;
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}
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/* INT_SUBTRACT_WRAPV is not appropriate since time_t might be unsigned.
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In theory time_t might be narrower than int, so plain
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INT_SUBTRACT_OVERFLOW does not suffice. */
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if (! INT_SUBTRACT_OVERFLOW (rs, bs) && tmin <= rs - bs && rs - bs <= tmax)
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rs -= bs;
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else
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{
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if (rs < 0)
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{
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low_overflow:
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rs = tmin;
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rns = 0;
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}
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else
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{
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rs = tmax;
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rns = TIMESPEC_HZ - 1;
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}
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}
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return make_timespec (rs, rns);
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}
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