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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.
89 lines
4.7 KiB
C
89 lines
4.7 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/internal.h"
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#include "libc/calls/struct/iovec.h"
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#include "libc/calls/struct/iovec.internal.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/intrin/weaken.h"
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#include "libc/sock/sock.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/zipos/zipos.internal.h"
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/**
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* Writes data to file descriptor.
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*
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* This function changes the current file position. For documentation
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* on file position behaviors and gotchas, see the lseek() function.
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* This function may be used on socket file descriptors, including on
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* Windows.
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*
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* @param fd is open file descriptor
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* @param buf is copied from, cf. copy_file_range(), sendfile(), etc.
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* @return [1..size] bytes on success, or -1 w/ errno; noting zero is
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* impossible unless size was passed as zero to do an error check
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* @raise EBADF if `fd` is negative or not an open file descriptor
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* @raise EBADF if `fd` wasn't opened with `O_WRONLY` or `O_RDWR`
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* @raise EPIPE if `fd` is a pipe whose other reader end was closed,
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* after the `SIGPIPE` signal was delivered, blocked, or ignored
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* @raise EFBIG if `RLIMIT_FSIZE` soft limit was exceeded, after the
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* `SIGXFSZ` signal was either delivered, blocked, or ignored
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* @raise EFAULT if `size` is nonzero and `buf` points to bad memory
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* @raise EPERM if pledge() is in play without the stdio promise
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* @raise ENOSPC if device containing `fd` is full
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* @raise EIO if low-level i/o error happened
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* @raise EINTR if signal was delivered instead
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* @raise EAGAIN if `O_NONBLOCK` is in play and write needs to block
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* @raise ENOBUFS if kernel lacked internal resources; which FreeBSD
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* and XNU say could happen with sockets, and OpenBSD documents it
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* as a general possibility; whereas other system don't specify it
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* @raise ENXIO is specified only by POSIX and XNU when a request is
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* made of a nonexistent device or outside device capabilities
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* @cancellationpoint
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* @asyncsignalsafe
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* @restartable
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* @vforksafe
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*/
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ssize_t write(int fd, const void *buf, size_t size) {
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ssize_t rc;
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if (fd >= 0) {
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if ((!buf && size) || (IsAsan() && !__asan_is_valid(buf, size))) {
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rc = efault();
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} else if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip) {
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rc = _weaken(__zipos_write)(
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(struct ZiposHandle *)(intptr_t)g_fds.p[fd].handle,
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&(struct iovec){buf, size}, 1, -1);
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} else if (!IsWindows() && !IsMetal()) {
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rc = sys_write(fd, buf, size);
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} else if (fd >= g_fds.n) {
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rc = ebadf();
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} else if (IsMetal()) {
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rc = sys_writev_metal(g_fds.p + fd, &(struct iovec){buf, size}, 1);
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} else {
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rc = sys_writev_nt(fd, &(struct iovec){buf, size}, 1);
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}
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} else {
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rc = ebadf();
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}
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DATATRACE("write(%d, %#.*hhs%s, %'zu) → %'zd% m", fd, MAX(0, MIN(40, rc)),
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buf, rc > 40 ? "..." : "", size, rc);
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return rc;
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}
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