cosmopolitan/libc/calls/setitimer.c

74 lines
3.8 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program 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 │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/internal.h"
#include "libc/calls/struct/itimerval.h"
#include "libc/dce.h"
#include "libc/sysv/errfuns.h"
#include "libc/time/time.h"
/**
* Schedules delivery of one-shot or intermittent interrupt signal, e.g.
*
* Raise SIGALRM every 1.5s:
*
* CHECK_NE(-1, sigaction(SIGALRM,
* &(struct sigaction){.sa_sigaction = missingno},
* NULL));
* CHECK_NE(-1, setitimer(ITIMER_REAL,
* &(const struct itimerval){{1, 500000}, {1, 500000}},
* NULL));
*
* Set single-shot 50ms timer callback to interrupt laggy connect():
*
* CHECK_NE(-1, sigaction(SIGALRM,
* &(struct sigaction){.sa_sigaction = missingno,
* .sa_flags = SA_RESETHAND},
* NULL));
* CHECK_NE(-1, setitimer(ITIMER_REAL,
* &(const struct itimerval){{0, 0}, {0, 50000}},
* NULL));
* if (connect(...) == -1 && errno == EINTR) { ... }
*
* Disarm timer:
*
* CHECK_NE(-1, setitimer(ITIMER_REAL, &(const struct itimerval){0}, NULL));
*
* Be sure to check for EINTR on your i/o calls, for best low latency.
*
* @param which can be ITIMER_REAL, ITIMER_VIRTUAL, etc.
* @param newvalue specifies the interval ({0,0} means one-shot) and
* duration ({0,0} means disarm) in microseconds ∈ [0,999999] and
* if this parameter is NULL, we'll polyfill getitimer() behavior
* @param out_opt_old may receive remainder of previous op (if any)
* @return 0 on success or -1 w/ errno
*/
int setitimer(int which, const struct itimerval *newvalue,
struct itimerval *out_opt_oldvalue) {
if (!IsWindows()) {
if (newvalue) {
return setitimer$sysv(which, newvalue, out_opt_oldvalue);
} else {
return getitimer$sysv(which, out_opt_oldvalue);
}
} else {
return setitimer$nt(which, newvalue, out_opt_oldvalue);
}
}