/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et 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/calls.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/strace.h"
#include "libc/runtime/stack.h"
#include "libc/sock/struct/pollfd.h"
#include "libc/sock/struct/pollfd.internal.h"
#include "libc/stdckdint.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/f.h"
#include "libc/sysv/consts/poll.h"
#include "libc/sysv/consts/sig.h"
#include "libc/sysv/errfuns.h"
static int ppoll_impl(struct pollfd *fds, size_t nfds,
const struct timespec *timeout, const sigset_t *sigmask) {
int e, fdcount;
sigset_t oldmask;
struct timespec ts, *tsp;
// validate timeout
if (timeout && timeout->tv_nsec >= 1000000000ull)
return einval();
// The OpenBSD poll() man pages claims it'll ignore POLLERR, POLLHUP,
// and POLLNVAL in pollfd::events except it doesn't actually do this.
size_t bytes = 0;
struct pollfd *fds2 = 0;
if (IsOpenbsd()) {
if (ckd_mul(&bytes, nfds, sizeof(struct pollfd)))
return einval();
#pragma GCC push_options
#pragma GCC diagnostic ignored "-Walloca-larger-than="
#pragma GCC diagnostic ignored "-Wanalyzer-out-of-bounds"
fds2 = alloca(bytes);
#pragma GCC pop_options
CheckLargeStackAllocation(fds2, bytes);
memcpy(fds2, fds, bytes);
for (size_t i = 0; i < nfds; ++i)
fds2[i].events &= ~(POLLERR | POLLHUP | POLLNVAL);
struct pollfd *swap = fds;
fds = fds2;
fds2 = swap;
}
if (!IsWindows()) {
e = errno;
if (timeout) {
ts = *timeout;
tsp = &ts;
} else {
tsp = 0;
}
fdcount = sys_ppoll(fds, nfds, tsp, sigmask, 8);
if (fdcount == -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);
fdcount = sys_poll(fds, nfds, ms);
if (sigmask)
sys_sigprocmask(SIG_SETMASK, &oldmask, 0);
}
} else {
uint32_t ms;
uint32_t *msp;
if (timeout &&
!ckd_add(&ms, timeout->tv_sec, (timeout->tv_nsec + 999999) / 1000000)) {
msp = &ms;
} else {
msp = 0;
}
fdcount = sys_poll_nt(fds, nfds, msp, sigmask);
}
if (IsOpenbsd() && fdcount != -1) {
struct pollfd *swap = fds;
fds = fds2;
fds2 = swap;
memcpy(fds, fds2, bytes);
}
// One of the use cases for poll() is checking if a large number of
// file descriptors exist. However on XNU if none of the meaningful
// event flags are specified (e.g. POLLIN, POLLOUT) then it doesn't
// perform the POLLNVAL check that's implied on all other platforms
if (IsXnu() && fdcount != -1) {
for (size_t i = 0; i < nfds; ++i) {
if (fds[i].fd >= 0 && //
!fds[i].revents && //
!(fds[i].events & (POLLIN | POLLOUT | POLLPRI))) {
int err = errno;
if (fcntl(fds[i].fd, F_GETFL) == -1) {
errno = err;
fds[i].revents = POLLNVAL;
++fdcount;
}
}
}
}
return fdcount;
}
/**
* Checks status 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
* kernels such as XNU and NetBSD which don't, this wrapper will fall
* back to using the example above. If you need ironclad assurances of
* signal mask atomicity, then consider using pselect() which Cosmo Libc
* guarantees to be atomic on all supported platforms.
*
* Servers that need to handle an unbounded number of client connections
* should just create a separate thread for each client. poll(), ppoll()
* and select() aren't scalable i/o solutions on any platform.
*
* On Windows it's only possible to poll 64 file descriptors at a time;
* it's a limitation imposed by WSAPoll(). Cosmopolitan Libc's ppoll()
* polyfill can go higher in some cases; for example, It's possible to
* poll 64 sockets and 64 pipes/terminals at the same time. Furthermore,
* elements whose fd field is set to a negative number are ignored and
* will not count against this limit.
*
* One of the use cases for poll() is to quickly check if a number of
* file descriptors are valid. The canonical way to do this is to set
* events to 0 which prevents blocking and causes only the invalid,
* hangup, and error statuses to be checked.
*
* On XNU, the POLLHUP and POLLERR statuses aren't checked unless either
* POLLIN, POLLOUT, or POLLPRI are specified in the events field. Cosmo
* will however polyfill the checking of POLLNVAL on XNU with the events
* doesn't specify any of the above i/o events.
*
* When XNU and BSD OSes report POLLHUP, they will always set POLLIN too
* when POLLIN is requested, even in cases when there isn't unread data.
*
* @param fds[𝑖].fd should be a socket, input pipe, or conosle input
* and if it's a negative number then the entry is ignored, plus
* revents will be set to zero
* @param fds[𝑖].events flags can have POLLIN, POLLOUT, POLLPRI,
* POLLRDNORM, POLLWRNORM, POLLRDBAND, POLLWRBAND as well as
* POLLERR, POLLHUP, and POLLNVAL although the latter are
* always implied (assuming fd≥0) so they're ignored here
* @param timeout_ms if 0 means don't wait and negative waits forever
* @return number of `fds` whose revents field has been set to a nonzero
* number, 0 if the timeout elapsed without events, or -1 w/ errno
* @return fds[𝑖].revents is always zero initializaed and then will
* be populated with POLL{IN,OUT,PRI,HUP,ERR,NVAL} if something
* was determined about the file descriptor
* @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 EINVAL if `nfds` exceeded `RLIMIT_NOFILE`
* @raise ENOMEM on failure to allocate memory
* @raise EINVAL if `*timeout` is invalid
* @raise EINTR if signal was delivered
* @cancelationpoint
* @asyncsignalsafe
* @norestart
*/
int ppoll(struct pollfd *fds, size_t nfds, const struct timespec *timeout,
const sigset_t *sigmask) {
int fdcount;
BEGIN_CANCELATION_POINT;
fdcount = ppoll_impl(fds, nfds, timeout, sigmask);
END_CANCELATION_POINT;
STRACE("ppoll(%s, %'zu, %s, %s) → %d% lm",
DescribePollFds(fdcount, fds, nfds), nfds,
DescribeTimespec(0, timeout), DescribeSigset(0, sigmask), fdcount);
return fdcount;
}