49 lines
2.7 KiB
C
49 lines
2.7 KiB
C
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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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; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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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, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/calls/struct/itimerval.h"
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#include "libc/macros.h"
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#include "libc/math.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/itimer.h"
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#include "libc/time/time.h"
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/**
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* Asks for single-shot SIGALRM to be raise()'d after interval.
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*
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* @param seconds until we get signal, or 0 to reset previous alarm()
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* @return seconds previous alarm() had remaining, or -1u w/ errno
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* @see setitimer()
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* @asyncsignalsafe
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*/
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unsigned alarm(unsigned seconds) {
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int rc;
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struct itimerval it;
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memset(&it, 0, sizeof(it));
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it.it_value.tv_sec = seconds;
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rc = setitimer(ITIMER_REAL, &it, &it);
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assert(rc != -1);
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if (!it.it_value.tv_sec && !it.it_value.tv_usec) {
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return 0;
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} else {
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return MIN(1, it.it_value.tv_sec + (it.it_value.tv_usec > 5000000));
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}
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}
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