mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-01 03:53:33 +00:00
2278327eba
This change makes some miracle modifications to the System Five system call support, which lets us have safe, correct, and atomic handling of thread cancellations. It all turned out to be cheaper than anticipated because it wasn't necessary to modify the system call veneers. We were able to encode the cancellability of each system call into the magnums found in libc/sysv/syscalls.sh. Since cancellations are so waq, we are also supporting a lovely Musl Libc mask feature for raising ECANCELED.
98 lines
4.3 KiB
C
98 lines
4.3 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/struct/timespec.h"
|
|
#include "libc/calls/struct/timeval.h"
|
|
#include "libc/dce.h"
|
|
#include "libc/intrin/asan.internal.h"
|
|
#include "libc/intrin/describeflags.internal.h"
|
|
#include "libc/intrin/strace.internal.h"
|
|
#include "libc/sock/internal.h"
|
|
#include "libc/sock/select.h"
|
|
#include "libc/sysv/errfuns.h"
|
|
|
|
/**
|
|
* Does what poll() does except with bitset API.
|
|
*
|
|
* This function is the same as saying:
|
|
*
|
|
* sigset_t old;
|
|
* sigprocmask(SIG_SETMASK, sigmask, &old);
|
|
* select(nfds, readfds, writefds, exceptfds, timeout);
|
|
* sigprocmask(SIG_SETMASK, old, 0);
|
|
*
|
|
* Except it happens atomically.
|
|
*
|
|
* 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_pselect.
|
|
*
|
|
* This system call is supported on all platforms. It's like select()
|
|
* except that it atomically changes the sigprocmask() during the op.
|
|
*
|
|
* @cancellationpoint
|
|
* @asyncsignalsafe
|
|
* @threadsafe
|
|
* @norestart
|
|
*/
|
|
int pselect(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
|
|
const struct timespec *timeout, const sigset_t *sigmask) {
|
|
int rc;
|
|
sigset_t oldmask;
|
|
struct timeval tv, *tvp;
|
|
struct timespec ts, *tsp;
|
|
struct {
|
|
const sigset_t *s;
|
|
size_t n;
|
|
} ss;
|
|
if (nfds < 0) {
|
|
rc = einval();
|
|
} else if (IsAsan() &&
|
|
((readfds && !__asan_is_valid(readfds, FD_SIZE(nfds))) ||
|
|
(writefds && !__asan_is_valid(writefds, FD_SIZE(nfds))) ||
|
|
(exceptfds && !__asan_is_valid(exceptfds, FD_SIZE(nfds))) ||
|
|
(timeout && !__asan_is_valid(timeout, sizeof(*timeout))) ||
|
|
(sigmask && !__asan_is_valid(sigmask, sizeof(*sigmask))))) {
|
|
rc = efault();
|
|
} else if (IsLinux()) {
|
|
if (timeout) {
|
|
ts = *timeout;
|
|
tsp = &ts;
|
|
} else {
|
|
tsp = 0;
|
|
}
|
|
ss.s = sigmask;
|
|
ss.n = 8;
|
|
rc = sys_pselect(nfds, readfds, writefds, exceptfds, tsp, &ss);
|
|
} else if (!IsWindows()) {
|
|
rc = sys_pselect(nfds, readfds, writefds, exceptfds, timeout, sigmask);
|
|
} else {
|
|
if (timeout) {
|
|
tv.tv_sec = timeout->tv_sec;
|
|
tv.tv_usec = timeout->tv_nsec / 1000;
|
|
tvp = &tv;
|
|
} else {
|
|
tvp = 0;
|
|
}
|
|
rc = sys_select_nt(nfds, readfds, writefds, exceptfds, tvp, sigmask);
|
|
}
|
|
POLLTRACE("pselect(%d, %p, %p, %p, %s, %s) → %d% m", nfds, readfds, writefds,
|
|
exceptfds, DescribeTimeval(0, timeout), DescribeSigset(0, sigmask),
|
|
rc);
|
|
return rc;
|
|
}
|