mirror of
https://github.com/jart/cosmopolitan.git
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85 lines
4.1 KiB
C
85 lines
4.1 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et 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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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/struct/itimerval.h"
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#include "libc/calls/struct/itimerval.internal.h"
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#include "libc/dce.h"
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#include "libc/intrin/describeflags.h"
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#include "libc/intrin/strace.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/time.h"
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/**
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* Schedules delivery of one-shot or intermittent interrupt signal, e.g.
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*
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* Raise SIGALRM every 1.5s:
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*
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* sigaction(SIGALRM,
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* &(struct sigaction){.sa_handler = OnSigalrm},
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* NULL);
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* setitimer(ITIMER_REAL,
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* &(const struct itimerval){{1, 500000},
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* {1, 500000}},
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* NULL);
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*
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* Single-shot alarm to interrupt connect() after 50ms:
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*
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* sigaction(SIGALRM,
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* &(struct sigaction){.sa_handler = OnSigalrm,
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* .sa_flags = SA_RESETHAND},
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* NULL);
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* setitimer(ITIMER_REAL,
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* &(const struct itimerval){{0, 0}, {0, 50000}},
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* NULL);
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* if (connect(...) == -1 && errno == EINTR) { ... }
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*
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* Disarm existing timer:
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*
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* setitimer(ITIMER_REAL, &(const struct itimerval){0}, NULL);
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*
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* If the goal is to use alarms to interrupt blocking i/o routines, e.g.
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* read(), connect(), etc. then it's important to install the signal
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* handler using sigaction() rather than signal(), because the latter
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* sets the `SA_RESTART` flag.
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*
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* Timers are not inherited across fork.
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*
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* @param which can be ITIMER_REAL, ITIMER_VIRTUAL, etc.
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* @param newvalue specifies the interval ({0,0} means one-shot) and
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* duration ({0,0} means disarm) in microseconds ∈ [0,999999] and
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* if this parameter is NULL, we'll polyfill getitimer() behavior
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* @param out_opt_old may receive remainder of previous op (if any)
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* @return 0 on success or -1 w/ errno
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* @asyncsignalsafe
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*/
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int setitimer(int which, const struct itimerval *newvalue,
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struct itimerval *oldvalue) {
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int rc;
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if (!IsWindows()) {
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if (newvalue) {
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rc = sys_setitimer(which, newvalue, oldvalue);
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} else {
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rc = sys_getitimer(which, oldvalue);
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}
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} else {
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rc = sys_setitimer_nt(which, newvalue, oldvalue);
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}
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STRACE("setitimer(%s, %s, [%s]) → %d% m", DescribeItimer(which),
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DescribeItimerval(0, newvalue), DescribeItimerval(rc, oldvalue), rc);
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return rc;
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}
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