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https://github.com/jart/cosmopolitan.git
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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.
112 lines
4.7 KiB
C
112 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/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/sig.internal.h"
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#include "libc/calls/struct/fd.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_support-nt.internal.h"
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#include "libc/calls/wincrash.internal.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/nt/enum/filetype.h"
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#include "libc/nt/errors.h"
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#include "libc/nt/files.h"
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#include "libc/nt/ipc.h"
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#include "libc/nt/runtime.h"
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#include "libc/nt/struct/overlapped.h"
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#include "libc/nt/synchronization.h"
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#include "libc/sysv/errfuns.h"
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static textwindows ssize_t sys_read_nt_impl(struct Fd *fd, void *data,
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size_t size, ssize_t offset) {
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bool32 ok;
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int64_t p;
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uint32_t got, avail;
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struct NtOverlapped overlap;
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// our terrible polling mechanism
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if (GetFileType(fd->handle) == kNtFileTypePipe) {
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for (;;) {
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if (!PeekNamedPipe(fd->handle, 0, 0, 0, &avail, 0)) break;
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if (avail) break;
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POLLTRACE("sys_read_nt polling");
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if (SleepEx(__SIG_POLLING_INTERVAL_MS, true) == kNtWaitIoCompletion) {
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POLLTRACE("IOCP EINTR");
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}
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if (_check_interrupts(true, g_fds.p)) {
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POLLTRACE("sys_read_nt interrupted");
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return -1;
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}
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}
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POLLTRACE("sys_read_nt ready to read");
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}
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if (offset != -1) {
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// windows changes the file pointer even if overlapped is passed
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_npassert(SetFilePointerEx(fd->handle, 0, &p, SEEK_CUR));
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}
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ok = ReadFile(fd->handle, data, _clampio(size), &got,
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_offset2overlap(fd->handle, offset, &overlap));
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if (offset != -1) {
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// windows clobbers file pointer even on error
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_npassert(SetFilePointerEx(fd->handle, p, 0, SEEK_SET));
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}
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if (ok) {
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return got;
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}
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switch (GetLastError()) {
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case kNtErrorBrokenPipe: // broken pipe
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case kNtErrorNoData: // closing named pipe
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case kNtErrorHandleEof: // pread read past EOF
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return 0; //
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case kNtErrorAccessDenied: // read doesn't return EACCESS
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return ebadf(); //
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default:
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return __winerr();
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}
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}
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textwindows ssize_t sys_read_nt(struct Fd *fd, const struct iovec *iov,
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size_t iovlen, ssize_t opt_offset) {
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ssize_t rc;
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uint32_t size;
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size_t i, total;
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if (opt_offset < -1) return einval();
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if (_check_interrupts(true, fd)) return -1;
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while (iovlen && !iov[0].iov_len) iov++, iovlen--;
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if (iovlen) {
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for (total = i = 0; i < iovlen; ++i) {
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if (!iov[i].iov_len) continue;
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rc = sys_read_nt_impl(fd, iov[i].iov_base, iov[i].iov_len, opt_offset);
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if (rc == -1) return -1;
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total += rc;
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if (opt_offset != -1) opt_offset += rc;
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if (rc < iov[i].iov_len) break;
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}
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return total;
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} else {
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return sys_read_nt_impl(fd, NULL, 0, opt_offset);
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}
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}
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