mirror of
https://github.com/jart/cosmopolitan.git
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102 lines
4.4 KiB
C
102 lines
4.4 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 2022 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/cp.internal.h"
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#include "libc/calls/struct/sigset.h"
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#include "libc/calls/struct/sigset.internal.h"
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#include "libc/calls/struct/timespec.h"
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#include "libc/calls/struct/timespec.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/strace.h"
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#include "libc/sock/struct/pollfd.h"
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#include "libc/sock/struct/pollfd.internal.h"
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#include "libc/stdckdint.h"
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#include "libc/sysv/consts/sig.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Waits for something to happen on multiple file descriptors at once.
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*
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* This function is the same as saying:
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*
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* sigset_t old;
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* sigprocmask(SIG_SETMASK, sigmask, &old);
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* poll(fds, nfds, timeout);
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* sigprocmask(SIG_SETMASK, old, 0);
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*
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* Except it happens atomically when the kernel supports doing that. On
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* kernel such as XNU and NetBSD which don't, this wrapper will fall
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* back to using the example above. Consider using pselect() which is
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* atomic on all supported platforms.
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*
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* The Linux Kernel modifies the timeout parameter. This wrapper gives
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* it a local variable due to POSIX requiring that `timeout` be const.
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* If you need that information from the Linux Kernel use sys_ppoll().
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*
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* @param timeout if null will block indefinitely
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* @param sigmask may be null in which case no mask change happens
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* @raise ECANCELED if thread was cancelled in masked mode
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* @raise EINTR if signal was delivered
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* @cancelationpoint
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* @asyncsignalsafe
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* @norestart
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*/
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int ppoll(struct pollfd *fds, size_t nfds, const struct timespec *timeout,
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const sigset_t *sigmask) {
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int e, rc;
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sigset_t oldmask;
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struct timespec ts, *tsp;
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BEGIN_CANCELATION_POINT;
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if (!IsWindows()) {
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e = errno;
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if (timeout) {
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ts = *timeout;
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tsp = &ts;
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} else {
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tsp = 0;
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}
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rc = sys_ppoll(fds, nfds, tsp, sigmask, 8);
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if (rc == -1 && errno == ENOSYS) {
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int ms;
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errno = e;
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if (!timeout || ckd_add(&ms, timeout->tv_sec,
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(timeout->tv_nsec + 999999) / 1000000)) {
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ms = -1;
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}
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if (sigmask)
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sys_sigprocmask(SIG_SETMASK, sigmask, &oldmask);
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rc = poll(fds, nfds, ms);
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if (sigmask)
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sys_sigprocmask(SIG_SETMASK, &oldmask, 0);
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}
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} else {
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uint32_t ms;
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if (!timeout ||
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ckd_add(&ms, timeout->tv_sec, (timeout->tv_nsec + 999999) / 1000000)) {
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ms = -1u;
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}
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rc = sys_poll_nt(fds, nfds, &ms, sigmask);
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}
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END_CANCELATION_POINT;
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STRACE("ppoll(%s, %'zu, %s, %s) → %d% lm", DescribePollFds(rc, fds, nfds),
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nfds, DescribeTimespec(0, timeout), DescribeSigset(0, sigmask), rc);
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return rc;
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}
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