cosmopolitan/libc/calls/ppoll.c
Justine Tunney 0c5dd7b342
Make improvements
- Improved async signal safety of read() particularly for longjmp()
- Started adding cancel cleanup handlers for locks / etc on Windows
- Make /dev/tty work better particularly for uses like `foo | less`
- Eagerly read console input into a linked list, so poll can signal
- Fix some libc definitional bugs, which configure scripts detected
2023-09-21 07:30:39 -07:00

111 lines
4.8 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 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/bo.internal.h"
#include "libc/calls/cp.internal.h"
#include "libc/calls/struct/sigset.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/struct/timespec.h"
#include "libc/calls/struct/timespec.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/strace.internal.h"
#include "libc/sock/struct/pollfd.h"
#include "libc/sock/struct/pollfd.internal.h"
#include "libc/stdckdint.h"
#include "libc/sysv/consts/sig.h"
#include "libc/sysv/errfuns.h"
/**
* Waits for something to happen on multiple file descriptors at once.
*
* This function is the same as saying:
*
* sigset_t old;
* sigprocmask(SIG_SETMASK, sigmask, &old);
* poll(fds, nfds, timeout);
* sigprocmask(SIG_SETMASK, old, 0);
*
* Except it happens atomically when the kernel supports doing that. On
* kernel such as XNU and NetBSD which don't, this wrapper will fall
* back to using the example above. Consider using pselect() which is
* atomic on all supported platforms.
*
* The Linux Kernel modifies the timeout parameter. This wrapper gives
* it a local variable due to POSIX requiring that `timeout` be const.
* If you need that information from the Linux Kernel use sys_ppoll().
*
* @param timeout if null will block indefinitely
* @param sigmask may be null in which case no mask change happens
* @raise ECANCELED if thread was cancelled in masked mode
* @raise EINTR if signal was delivered
* @cancellationpoint
* @asyncsignalsafe
* @threadsafe
* @norestart
*/
int ppoll(struct pollfd *fds, size_t nfds, const struct timespec *timeout,
const sigset_t *sigmask) {
size_t n;
int e, rc;
sigset_t oldmask;
struct timespec ts, *tsp;
BEGIN_CANCELLATION_POINT;
if (IsAsan() &&
(ckd_mul(&n, nfds, sizeof(struct pollfd)) || !__asan_is_valid(fds, n) ||
(timeout && !__asan_is_valid(timeout, sizeof(timeout))) ||
(sigmask && !__asan_is_valid(sigmask, sizeof(sigmask))))) {
rc = efault();
} else if (!IsWindows()) {
e = errno;
if (timeout) {
ts = *timeout;
tsp = &ts;
} else {
tsp = 0;
}
rc = sys_ppoll(fds, nfds, tsp, sigmask, 8);
if (rc == -1 && errno == ENOSYS) {
int ms;
errno = e;
if (!timeout || ckd_add(&ms, timeout->tv_sec,
(timeout->tv_nsec + 999999) / 1000000)) {
ms = -1;
}
if (sigmask) sys_sigprocmask(SIG_SETMASK, sigmask, &oldmask);
rc = poll(fds, nfds, ms);
if (sigmask) sys_sigprocmask(SIG_SETMASK, &oldmask, 0);
}
} else {
uint32_t ms;
if (!timeout ||
ckd_add(&ms, timeout->tv_sec, (timeout->tv_nsec + 999999) / 1000000)) {
ms = -1u;
}
BEGIN_BLOCKING_OPERATION;
rc = sys_poll_nt(fds, nfds, &ms, sigmask);
END_BLOCKING_OPERATION;
}
END_CANCELLATION_POINT;
STRACE("ppoll(%s, %'zu, %s, %s) → %d% lm", DescribePollFds(rc, fds, nfds),
nfds, DescribeTimespec(0, timeout), DescribeSigset(0, sigmask), rc);
return rc;
}