mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 19:43:32 +00:00
c7a8cd21e9
This change improves copy_file_range(), sendfile(), splice(), openpty(), closefrom(), close_range(), fadvise() and posix_fadvise() in addition to writing tests that confirm things like errno and seeking behavior across platforms. We now less aggressively polyfill behavior with some of these functions when the platform support isn't available. Please see: https://justine.lol/cosmopolitan/functions.html
109 lines
5.2 KiB
C
109 lines
5.2 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 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/calls.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/likely.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/macros.internal.h"
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#include "libc/sock/internal.h"
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#include "libc/sock/sock.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/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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* Warning: XNU has an inconsistency with other platforms. If you have
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* pollfds with fd≥0 and none of the meaningful events flags are added
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* e.g. POLLIN then XNU won't check for POLLNVAL. This matters because
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* one of the use-cases for poll() is quickly checking for open files.
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*
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* Note: Polling works best on Windows for sockets. We're able to poll
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* input on named pipes. But for anything that isn't a socket, or pipe
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* with POLLIN, (e.g. regular file) then POLLIN/POLLOUT are always set
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* into revents if they're requested, provided they were opened with a
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* mode that permits reading and/or writing.
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*
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* Note: Windows has a limit of 64 file descriptors and ENOMEM with -1
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* is returned if that limit is exceeded. In practice the limit is not
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* this low. For example, pollfds with fd<0 don't count. So the caller
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* could flip the sign bit with a short timeout, to poll a larger set.
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*
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* @param fds[𝑖].fd should be a socket, input pipe, or conosle input
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* and if it's a negative number then the entry is ignored
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* @param fds[𝑖].events flags can have POLLIN, POLLOUT, POLLPRI,
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* POLLRDNORM, POLLWRNORM, POLLRDBAND, POLLWRBAND as well as
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* POLLERR, POLLHUP, and POLLNVAL although the latter are
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* always implied (assuming fd≥0) so they're ignored here
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* @param timeout_ms if 0 means don't wait and -1 means wait forever
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* @return number of items fds whose revents field has been set to
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* nonzero to describe its events, or 0 if the timeout elapsed,
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* or -1 w/ errno
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* @return fds[𝑖].revents is always zero initializaed and then will
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* be populated with POLL{IN,OUT,PRI,HUP,ERR,NVAL} if something
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* was determined about the file descriptor
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* @asyncsignalsafe
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* @threadsafe
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* @norestart
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*/
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int poll(struct pollfd *fds, size_t nfds, int timeout_ms) {
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size_t n;
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int i, rc;
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uint64_t millis;
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if (IsAsan() && (__builtin_mul_overflow(nfds, sizeof(struct pollfd), &n) ||
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!__asan_is_valid(fds, n))) {
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rc = efault();
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} else if (!IsWindows()) {
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if (!IsMetal()) {
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rc = sys_poll(fds, nfds, timeout_ms);
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} else {
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rc = sys_poll_metal(fds, nfds, timeout_ms);
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}
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} else {
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millis = timeout_ms;
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rc = sys_poll_nt(fds, nfds, &millis, 0);
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}
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#if defined(SYSDEBUG) && _POLLTRACE
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if (UNLIKELY(__strace > 0)) {
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kprintf(STRACE_PROLOGUE "poll(");
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if ((!IsAsan() && kisdangerous(fds)) ||
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(IsAsan() && !__asan_is_valid(fds, nfds * sizeof(struct pollfd)))) {
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kprintf("%p", fds);
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} else {
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kprintf("[{");
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for (i = 0; i < MIN(5, nfds); ++i) {
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kprintf("%s{%d, %s, %s}", i ? ", " : "", fds[i].fd,
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DescribePollFlags(fds[i].events),
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DescribePollFlags(fds[i].revents));
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}
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kprintf("%s}]", i == 5 ? "..." : "");
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}
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kprintf(", %'zu, %'d) → %d% lm\n", nfds, timeout_ms, rc);
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}
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#endif
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return rc;
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}
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