// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package poll
import (
"errors"
"internal/race"
"internal/syscall/windows"
"io"
"runtime"
"sync"
"syscall"
"unicode/utf16"
"unicode/utf8"
"unsafe"
)
var (
initErr error
ioSync uint64
)
// CancelIo Windows API cancels all outstanding IO for a particular
// socket on current thread. To overcome that limitation, we run
// special goroutine, locked to OS single thread, that both starts
// and cancels IO. It means, there are 2 unavoidable thread switches
// for every IO.
// Some newer versions of Windows has new CancelIoEx API, that does
// not have that limitation and can be used from any thread. This
// package uses CancelIoEx API, if present, otherwise it fallback
// to CancelIo.
var canCancelIO bool // determines if CancelIoEx API is present
// This package uses the SetFileCompletionNotificationModes Windows
// API to skip calling GetQueuedCompletionStatus if an IO operation
// completes synchronously. There is a known bug where
// SetFileCompletionNotificationModes crashes on some systems (see
// https://support.microsoft.com/kb/2568167 for details).
var useSetFileCompletionNotificationModes bool // determines is SetFileCompletionNotificationModes is present and safe to use
// checkSetFileCompletionNotificationModes verifies that
// SetFileCompletionNotificationModes Windows API is present
// on the system and is safe to use.
// See https://support.microsoft.com/kb/2568167 for details.
func checkSetFileCompletionNotificationModes() {
err := syscall.LoadSetFileCompletionNotificationModes()
if err != nil {
return
}
protos := [2]int32{syscall.IPPROTO_TCP, 0}
var buf [32]syscall.WSAProtocolInfo
len := uint32(unsafe.Sizeof(buf))
n, err := syscall.WSAEnumProtocols(&protos[0], &buf[0], &len)
if err != nil {
return
}
for i := int32(0); i < n; i++ {
if buf[i].ServiceFlags1&syscall.XP1_IFS_HANDLES == 0 {
return
}
}
useSetFileCompletionNotificationModes = true
}
func init() {
var d syscall.WSAData
e := syscall.WSAStartup(uint32(0x202), &d)
if e != nil {
initErr = e
}
canCancelIO = syscall.LoadCancelIoEx() == nil
checkSetFileCompletionNotificationModes()
}
// operation contains superset of data necessary to perform all async IO.
type operation struct {
// Used by IOCP interface, it must be first field
// of the struct, as our code rely on it.
o syscall.Overlapped
// fields used by runtime.netpoll
runtimeCtx uintptr
mode int32
errno int32
qty uint32
// fields used only by net package
fd *FD
errc chan error
buf syscall.WSABuf
msg windows.WSAMsg
sa syscall.Sockaddr
rsa *syscall.RawSockaddrAny
rsan int32
handle syscall.Handle
flags uint32
bufs []syscall.WSABuf
}
func (o *operation) InitBuf(buf []byte) {
o.buf.Len = uint32(len(buf))
o.buf.Buf = nil
if len(buf) != 0 {
o.buf.Buf = &buf[0]
}
}
func (o *operation) InitBufs(buf *[][]byte) {
if o.bufs == nil {
o.bufs = make([]syscall.WSABuf, 0, len(*buf))
} else {
o.bufs = o.bufs[:0]
}
for _, b := range *buf {
if len(b) == 0 {
o.bufs = append(o.bufs, syscall.WSABuf{})
continue
}
for len(b) > maxRW {
o.bufs = append(o.bufs, syscall.WSABuf{Len: maxRW, Buf: &b[0]})
b = b[maxRW:]
}
if len(b) > 0 {
o.bufs = append(o.bufs, syscall.WSABuf{Len: uint32(len(b)), Buf: &b[0]})
}
}
}
// ClearBufs clears all pointers to Buffers parameter captured
// by InitBufs, so it can be released by garbage collector.
func (o *operation) ClearBufs() {
for i := range o.bufs {
o.bufs[i].Buf = nil
}
o.bufs = o.bufs[:0]
}
func (o *operation) InitMsg(p []byte, oob []byte) {
o.InitBuf(p)
o.msg.Buffers = &o.buf
o.msg.BufferCount = 1
o.msg.Name = nil
o.msg.Namelen = 0
o.msg.Flags = 0
o.msg.Control.Len = uint32(len(oob))
o.msg.Control.Buf = nil
if len(oob) != 0 {
o.msg.Control.Buf = &oob[0]
}
}
// ioSrv executes net IO requests.
type ioSrv struct {
req chan ioSrvReq
}
type ioSrvReq struct {
o *operation
submit func(o *operation) error // if nil, cancel the operation
}
// ProcessRemoteIO will execute submit IO requests on behalf
// of other goroutines, all on a single os thread, so it can
// cancel them later. Results of all operations will be sent
// back to their requesters via channel supplied in request.
// It is used only when the CancelIoEx API is unavailable.
func (s *ioSrv) ProcessRemoteIO() {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
for r := range s.req {
if r.submit != nil {
r.o.errc <- r.submit(r.o)
} else {
r.o.errc <- syscall.CancelIo(r.o.fd.Sysfd)
}
}
}
// ExecIO executes a single IO operation o. It submits and cancels
// IO in the current thread for systems where Windows CancelIoEx API
// is available. Alternatively, it passes the request onto
// runtime netpoll and waits for completion or cancels request.
func (s *ioSrv) ExecIO(o *operation, submit func(o *operation) error) (int, error) {
if o.fd.pd.runtimeCtx == 0 {
return 0, errors.New("internal error: polling on unsupported descriptor type")
}
if !canCancelIO {
onceStartServer.Do(startServer)
}
fd := o.fd
// Notify runtime netpoll about starting IO.
err := fd.pd.prepare(int(o.mode), fd.isFile)
if err != nil {
return 0, err
}
// Start IO.
if canCancelIO {
err = submit(o)
} else {
// Send request to a special dedicated thread,
// so it can stop the IO with CancelIO later.
s.req <- ioSrvReq{o, submit}
err = <-o.errc
}
switch err {
case nil:
// IO completed immediately
if o.fd.skipSyncNotif {
// No completion message will follow, so return immediately.
return int(o.qty), nil
}
// Need to get our completion message anyway.
case syscall.ERROR_IO_PENDING:
// IO started, and we have to wait for its completion.
err = nil
default:
return 0, err
}
// Wait for our request to complete.
err = fd.pd.wait(int(o.mode), fd.isFile)
if err == nil {
// All is good. Extract our IO results and return.
if o.errno != 0 {
err = syscall.Errno(o.errno)
// More data available. Return back the size of received data.
if err == syscall.ERROR_MORE_DATA || err == windows.WSAEMSGSIZE {
return int(o.qty), err
}
return 0, err
}
return int(o.qty), nil
}
// IO is interrupted by "close" or "timeout"
netpollErr := err
switch netpollErr {
case ErrNetClosing, ErrFileClosing, ErrTimeout:
// will deal with those.
default:
panic("unexpected runtime.netpoll error: " + netpollErr.Error())
}
// Cancel our request.
if canCancelIO {
err := syscall.CancelIoEx(fd.Sysfd, &o.o)
// Assuming ERROR_NOT_FOUND is returned, if IO is completed.
if err != nil && err != syscall.ERROR_NOT_FOUND {
// TODO(brainman): maybe do something else, but panic.
panic(err)
}
} else {
s.req <- ioSrvReq{o, nil}
<-o.errc
}
// Wait for cancelation to complete.
fd.pd.waitCanceled(int(o.mode))
if o.errno != 0 {
err = syscall.Errno(o.errno)
if err == syscall.ERROR_OPERATION_ABORTED { // IO Canceled
err = netpollErr
}
return 0, err
}
// We issued a cancelation request. But, it seems, IO operation succeeded
// before the cancelation request run. We need to treat the IO operation as
// succeeded (the bytes are actually sent/recv from network).
return int(o.qty), nil
}
// Start helper goroutines.
var rsrv, wsrv ioSrv
var onceStartServer sync.Once
func startServer() {
// This is called, once, when only the CancelIo API is available.
// Start two special goroutines, both locked to an OS thread,
// that start and cancel IO requests.
// One will process read requests, while the other will do writes.
rsrv.req = make(chan ioSrvReq)
go rsrv.ProcessRemoteIO()
wsrv.req = make(chan ioSrvReq)
go wsrv.ProcessRemoteIO()
}
// FD is a file descriptor. The net and os packages embed this type in
// a larger type representing a network connection or OS file.
type FD struct {
// Lock sysfd and serialize access to Read and Write methods.
fdmu fdMutex
// System file descriptor. Immutable until Close.
Sysfd syscall.Handle
// Read operation.
rop operation
// Write operation.
wop operation
// I/O poller.
pd pollDesc
// Used to implement pread/pwrite.
l sync.Mutex
// For console I/O.
isConsole bool
lastbits []byte // first few bytes of the last incomplete rune in last write
readuint16 []uint16 // buffer to hold uint16s obtained with ReadConsole
readbyte []byte // buffer to hold decoding of readuint16 from utf16 to utf8
readbyteOffset int // readbyte[readOffset:] is yet to be consumed with file.Read
// Semaphore signaled when file is closed.
csema uint32
skipSyncNotif bool
// Whether this is a streaming descriptor, as opposed to a
// packet-based descriptor like a UDP socket.
IsStream bool
// Whether a zero byte read indicates EOF. This is false for a
// message based socket connection.
ZeroReadIsEOF bool
// Whether this is a normal file.
isFile bool
// Whether this is a directory.
isDir bool
}
// logInitFD is set by tests to enable file descriptor initialization logging.
var logInitFD func(net string, fd *FD, err error)
// Init initializes the FD. The Sysfd field should already be set.
// This can be called multiple times on a single FD.
// The net argument is a network name from the net package (e.g., "tcp"),
// or "file" or "console" or "dir".
// Set pollable to true if fd should be managed by runtime netpoll.
func (fd *FD) Init(net string, pollable bool) (string, error) {
if initErr != nil {
return "", initErr
}
switch net {
case "file":
fd.isFile = true
case "console":
fd.isConsole = true
case "dir":
fd.isDir = true
case "tcp", "tcp4", "tcp6":
case "udp", "udp4", "udp6":
case "ip", "ip4", "ip6":
case "unix", "unixgram", "unixpacket":
default:
return "", errors.New("internal error: unknown network type " + net)
}
var err error
if pollable {
// Only call init for a network socket.
// This means that we don't add files to the runtime poller.
// Adding files to the runtime poller can confuse matters
// if the user is doing their own overlapped I/O.
// See issue #21172.
//
// In general the code below avoids calling the ExecIO
// method for non-network sockets. If some method does
// somehow call ExecIO, then ExecIO, and therefore the
// calling method, will return an error, because
// fd.pd.runtimeCtx will be 0.
err = fd.pd.init(fd)
}
if logInitFD != nil {
logInitFD(net, fd, err)
}
if err != nil {
return "", err
}
if pollable && useSetFileCompletionNotificationModes {
// We do not use events, so we can skip them always.
flags := uint8(syscall.FILE_SKIP_SET_EVENT_ON_HANDLE)
// It's not safe to skip completion notifications for UDP:
// https://blogs.technet.com/b/winserverperformance/archive/2008/06/26/designing-applications-for-high-performance-part-iii.aspx
if net == "tcp" {
flags |= syscall.FILE_SKIP_COMPLETION_PORT_ON_SUCCESS
}
err := syscall.SetFileCompletionNotificationModes(fd.Sysfd, flags)
if err == nil && flags&syscall.FILE_SKIP_COMPLETION_PORT_ON_SUCCESS != 0 {
fd.skipSyncNotif = true
}
}
// Disable SIO_UDP_CONNRESET behavior.
// http://support.microsoft.com/kb/263823
switch net {
case "udp", "udp4", "udp6":
ret := uint32(0)
flag := uint32(0)
size := uint32(unsafe.Sizeof(flag))
err := syscall.WSAIoctl(fd.Sysfd, syscall.SIO_UDP_CONNRESET, (*byte)(unsafe.Pointer(&flag)), size, nil, 0, &ret, nil, 0)
if err != nil {
return "wsaioctl", err
}
}
fd.rop.mode = 'r'
fd.wop.mode = 'w'
fd.rop.fd = fd
fd.wop.fd = fd
fd.rop.runtimeCtx = fd.pd.runtimeCtx
fd.wop.runtimeCtx = fd.pd.runtimeCtx
if !canCancelIO {
fd.rop.errc = make(chan error)
fd.wop.errc = make(chan error)
}
return "", nil
}
func (fd *FD) destroy() error {
if fd.Sysfd == syscall.InvalidHandle {
return syscall.EINVAL
}
// Poller may want to unregister fd in readiness notification mechanism,
// so this must be executed before fd.CloseFunc.
fd.pd.close()
var err error
if fd.isFile || fd.isConsole {
err = syscall.CloseHandle(fd.Sysfd)
} else if fd.isDir {
err = syscall.FindClose(fd.Sysfd)
} else {
// The net package uses the CloseFunc variable for testing.
err = CloseFunc(fd.Sysfd)
}
fd.Sysfd = syscall.InvalidHandle
runtime_Semrelease(&fd.csema)
return err
}
// Close closes the FD. The underlying file descriptor is closed by
// the destroy method when there are no remaining references.
func (fd *FD) Close() error {
if !fd.fdmu.increfAndClose() {
return errClosing(fd.isFile)
}
// unblock pending reader and writer
fd.pd.evict()
err := fd.decref()
// Wait until the descriptor is closed. If this was the only
// reference, it is already closed.
runtime_Semacquire(&fd.csema)
return err
}
// Shutdown wraps the shutdown network call.
func (fd *FD) Shutdown(how int) error {
if err := fd.incref(); err != nil {
return err
}
defer fd.decref()
return syscall.Shutdown(fd.Sysfd, how)
}
// Windows ReadFile and WSARecv use DWORD (uint32) parameter to pass buffer length.
// This prevents us reading blocks larger than 4GB.
// See golang.org/issue/26923.
const maxRW = 1 << 30 // 1GB is large enough and keeps subsequent reads aligned
// Read implements io.Reader.
func (fd *FD) Read(buf []byte) (int, error) {
if err := fd.readLock(); err != nil {
return 0, err
}
defer fd.readUnlock()
if len(buf) > maxRW {
buf = buf[:maxRW]
}
var n int
var err error
if fd.isFile || fd.isDir || fd.isConsole {
fd.l.Lock()
defer fd.l.Unlock()
if fd.isConsole {
n, err = fd.readConsole(buf)
} else {
n, err = syscall.Read(fd.Sysfd, buf)
}
if err != nil {
n = 0
}
} else {
o := &fd.rop
o.InitBuf(buf)
n, err = rsrv.ExecIO(o, func(o *operation) error {
return syscall.WSARecv(o.fd.Sysfd, &o.buf, 1, &o.qty, &o.flags, &o.o, nil)
})
if race.Enabled {
race.Acquire(unsafe.Pointer(&ioSync))
}
}
if len(buf) != 0 {
err = fd.eofError(n, err)
}
return n, err
}
var ReadConsole = syscall.ReadConsole // changed for testing
// readConsole reads utf16 characters from console File,
// encodes them into utf8 and stores them in buffer b.
// It returns the number of utf8 bytes read and an error, if any.
func (fd *FD) readConsole(b []byte) (int, error) {
if len(b) == 0 {
return 0, nil
}
if fd.readuint16 == nil {
// Note: syscall.ReadConsole fails for very large buffers.
// The limit is somewhere around (but not exactly) 16384.
// Stay well below.
fd.readuint16 = make([]uint16, 0, 10000)
fd.readbyte = make([]byte, 0, 4*cap(fd.readuint16))
}
for fd.readbyteOffset >= len(fd.readbyte) {
n := cap(fd.readuint16) - len(fd.readuint16)
if n > len(b) {
n = len(b)
}
var nw uint32
err := ReadConsole(fd.Sysfd, &fd.readuint16[:len(fd.readuint16)+1][len(fd.readuint16)], uint32(n), &nw, nil)
if err != nil {
return 0, err
}
uint16s := fd.readuint16[:len(fd.readuint16)+int(nw)]
fd.readuint16 = fd.readuint16[:0]
buf := fd.readbyte[:0]
for i := 0; i < len(uint16s); i++ {
r := rune(uint16s[i])
if utf16.IsSurrogate(r) {
if i+1 == len(uint16s) {
if nw > 0 {
// Save half surrogate pair for next time.
fd.readuint16 = fd.readuint16[:1]
fd.readuint16[0] = uint16(r)
break
}
r = utf8.RuneError
} else {
r = utf16.DecodeRune(r, rune(uint16s[i+1]))
if r != utf8.RuneError {
i++
}
}
}
n := utf8.EncodeRune(buf[len(buf):cap(buf)], r)
buf = buf[:len(buf)+n]
}
fd.readbyte = buf
fd.readbyteOffset = 0
if nw == 0 {
break
}
}
src := fd.readbyte[fd.readbyteOffset:]
var i int
for i = 0; i < len(src) && i < len(b); i++ {
x := src[i]
if x == 0x1A { // Ctrl-Z
if i == 0 {
fd.readbyteOffset++
}
break
}
b[i] = x
}
fd.readbyteOffset += i
return i, nil
}
// Pread emulates the Unix pread system call.
func (fd *FD) Pread(b []byte, off int64) (int, error) {
// Call incref, not readLock, because since pread specifies the
// offset it is independent from other reads.
if err := fd.incref(); err != nil {
return 0, err
}
defer fd.decref()
if len(b) > maxRW {
b = b[:maxRW]
}
fd.l.Lock()
defer fd.l.Unlock()
curoffset, e := syscall.Seek(fd.Sysfd, 0, io.SeekCurrent)
if e != nil {
return 0, e
}
defer syscall.Seek(fd.Sysfd, curoffset, io.SeekStart)
o := syscall.Overlapped{
OffsetHigh: uint32(off >> 32),
Offset: uint32(off),
}
var done uint32
e = syscall.ReadFile(fd.Sysfd, b, &done, &o)
if e != nil {
done = 0
if e == syscall.ERROR_HANDLE_EOF {
e = io.EOF
}
}
if len(b) != 0 {
e = fd.eofError(int(done), e)
}
return int(done), e
}
// ReadFrom wraps the recvfrom network call.
func (fd *FD) ReadFrom(buf []byte) (int, syscall.Sockaddr, error) {
if len(buf) == 0 {
return 0, nil, nil
}
if len(buf) > maxRW {
buf = buf[:maxRW]
}
if err := fd.readLock(); err != nil {
return 0, nil, err
}
defer fd.readUnlock()
o := &fd.rop
o.InitBuf(buf)
n, err := rsrv.ExecIO(o, func(o *operation) error {
if o.rsa == nil {
o.rsa = new(syscall.RawSockaddrAny)
}
o.rsan = int32(unsafe.Sizeof(*o.rsa))
return syscall.WSARecvFrom(o.fd.Sysfd, &o.buf, 1, &o.qty, &o.flags, o.rsa, &o.rsan, &o.o, nil)
})
err = fd.eofError(n, err)
if err != nil {
return n, nil, err
}
sa, _ := o.rsa.Sockaddr()
return n, sa, nil
}
// Write implements io.Writer.
func (fd *FD) Write(buf []byte) (int, error) {
if err := fd.writeLock(); err != nil {
return 0, err
}
defer fd.writeUnlock()
ntotal := 0
for len(buf) > 0 {
b := buf
if len(b) > maxRW {
b = b[:maxRW]
}
var n int
var err error
if fd.isFile || fd.isDir || fd.isConsole {
fd.l.Lock()
defer fd.l.Unlock()
if fd.isConsole {
n, err = fd.writeConsole(b)
} else {
n, err = syscall.Write(fd.Sysfd, b)
}
if err != nil {
n = 0
}
} else {
if race.Enabled {
race.ReleaseMerge(unsafe.Pointer(&ioSync))
}
o := &fd.wop
o.InitBuf(b)
n, err = wsrv.ExecIO(o, func(o *operation) error {
return syscall.WSASend(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, &o.o, nil)
})
}
ntotal += n
if err != nil {
return ntotal, err
}
buf = buf[n:]
}
return ntotal, nil
}
// writeConsole writes len(b) bytes to the console File.
// It returns the number of bytes written and an error, if any.
func (fd *FD) writeConsole(b []byte) (int, error) {
n := len(b)
runes := make([]rune, 0, 256)
if len(fd.lastbits) > 0 {
b = append(fd.lastbits, b...)
fd.lastbits = nil
}
for len(b) >= utf8.UTFMax || utf8.FullRune(b) {
r, l := utf8.DecodeRune(b)
runes = append(runes, r)
b = b[l:]
}
if len(b) > 0 {
fd.lastbits = make([]byte, len(b))
copy(fd.lastbits, b)
}
// syscall.WriteConsole seems to fail, if given large buffer.
// So limit the buffer to 16000 characters. This number was
// discovered by experimenting with syscall.WriteConsole.
const maxWrite = 16000
for len(runes) > 0 {
m := len(runes)
if m > maxWrite {
m = maxWrite
}
chunk := runes[:m]
runes = runes[m:]
uint16s := utf16.Encode(chunk)
for len(uint16s) > 0 {
var written uint32
err := syscall.WriteConsole(fd.Sysfd, &uint16s[0], uint32(len(uint16s)), &written, nil)
if err != nil {
return 0, err
}
uint16s = uint16s[written:]
}
}
return n, nil
}
// Pwrite emulates the Unix pwrite system call.
func (fd *FD) Pwrite(buf []byte, off int64) (int, error) {
// Call incref, not writeLock, because since pwrite specifies the
// offset it is independent from other writes.
if err := fd.incref(); err != nil {
return 0, err
}
defer fd.decref()
fd.l.Lock()
defer fd.l.Unlock()
curoffset, e := syscall.Seek(fd.Sysfd, 0, io.SeekCurrent)
if e != nil {
return 0, e
}
defer syscall.Seek(fd.Sysfd, curoffset, io.SeekStart)
ntotal := 0
for len(buf) > 0 {
b := buf
if len(b) > maxRW {
b = b[:maxRW]
}
var n uint32
o := syscall.Overlapped{
OffsetHigh: uint32(off >> 32),
Offset: uint32(off),
}
e = syscall.WriteFile(fd.Sysfd, b, &n, &o)
ntotal += int(n)
if e != nil {
return ntotal, e
}
buf = buf[n:]
off += int64(n)
}
return ntotal, nil
}
// Writev emulates the Unix writev system call.
func (fd *FD) Writev(buf *[][]byte) (int64, error) {
if len(*buf) == 0 {
return 0, nil
}
if err := fd.writeLock(); err != nil {
return 0, err
}
defer fd.writeUnlock()
if race.Enabled {
race.ReleaseMerge(unsafe.Pointer(&ioSync))
}
o := &fd.wop
o.InitBufs(buf)
n, err := wsrv.ExecIO(o, func(o *operation) error {
return syscall.WSASend(o.fd.Sysfd, &o.bufs[0], uint32(len(o.bufs)), &o.qty, 0, &o.o, nil)
})
o.ClearBufs()
TestHookDidWritev(n)
consume(buf, int64(n))
return int64(n), err
}
// WriteTo wraps the sendto network call.
func (fd *FD) WriteTo(buf []byte, sa syscall.Sockaddr) (int, error) {
if err := fd.writeLock(); err != nil {
return 0, err
}
defer fd.writeUnlock()
if len(buf) == 0 {
// handle zero-byte payload
o := &fd.wop
o.InitBuf(buf)
o.sa = sa
n, err := wsrv.ExecIO(o, func(o *operation) error {
return syscall.WSASendto(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, o.sa, &o.o, nil)
})
return n, err
}
ntotal := 0
for len(buf) > 0 {
b := buf
if len(b) > maxRW {
b = b[:maxRW]
}
o := &fd.wop
o.InitBuf(b)
o.sa = sa
n, err := wsrv.ExecIO(o, func(o *operation) error {
return syscall.WSASendto(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, o.sa, &o.o, nil)
})
ntotal += int(n)
if err != nil {
return ntotal, err
}
buf = buf[n:]
}
return ntotal, nil
}
// Call ConnectEx. This doesn't need any locking, since it is only
// called when the descriptor is first created. This is here rather
// than in the net package so that it can use fd.wop.
func (fd *FD) ConnectEx(ra syscall.Sockaddr) error {
o := &fd.wop
o.sa = ra
_, err := wsrv.ExecIO(o, func(o *operation) error {
return ConnectExFunc(o.fd.Sysfd, o.sa, nil, 0, nil, &o.o)
})
return err
}
func (fd *FD) acceptOne(s syscall.Handle, rawsa []syscall.RawSockaddrAny, o *operation) (string, error) {
// Submit accept request.
o.handle = s
o.rsan = int32(unsafe.Sizeof(rawsa[0]))
_, err := rsrv.ExecIO(o, func(o *operation) error {
return AcceptFunc(o.fd.Sysfd, o.handle, (*byte)(unsafe.Pointer(&rawsa[0])), 0, uint32(o.rsan), uint32(o.rsan), &o.qty, &o.o)
})
if err != nil {
CloseFunc(s)
return "acceptex", err
}
// Inherit properties of the listening socket.
err = syscall.Setsockopt(s, syscall.SOL_SOCKET, syscall.SO_UPDATE_ACCEPT_CONTEXT, (*byte)(unsafe.Pointer(&fd.Sysfd)), int32(unsafe.Sizeof(fd.Sysfd)))
if err != nil {
CloseFunc(s)
return "setsockopt", err
}
return "", nil
}
// Accept handles accepting a socket. The sysSocket parameter is used
// to allocate the net socket.
func (fd *FD) Accept(sysSocket func() (syscall.Handle, error)) (syscall.Handle, []syscall.RawSockaddrAny, uint32, string, error) {
if err := fd.readLock(); err != nil {
return syscall.InvalidHandle, nil, 0, "", err
}
defer fd.readUnlock()
o := &fd.rop
var rawsa [2]syscall.RawSockaddrAny
for {
s, err := sysSocket()
if err != nil {
return syscall.InvalidHandle, nil, 0, "", err
}
errcall, err := fd.acceptOne(s, rawsa[:], o)
if err == nil {
return s, rawsa[:], uint32(o.rsan), "", nil
}
// Sometimes we see WSAECONNRESET and ERROR_NETNAME_DELETED is
// returned here. These happen if connection reset is received
// before AcceptEx could complete. These errors relate to new
// connection, not to AcceptEx, so ignore broken connection and
// try AcceptEx again for more connections.
errno, ok := err.(syscall.Errno)
if !ok {
return syscall.InvalidHandle, nil, 0, errcall, err
}
switch errno {
case syscall.ERROR_NETNAME_DELETED, syscall.WSAECONNRESET:
// ignore these and try again
default:
return syscall.InvalidHandle, nil, 0, errcall, err
}
}
}
// Seek wraps syscall.Seek.
func (fd *FD) Seek(offset int64, whence int) (int64, error) {
if err := fd.incref(); err != nil {
return 0, err
}
defer fd.decref()
fd.l.Lock()
defer fd.l.Unlock()
return syscall.Seek(fd.Sysfd, offset, whence)
}
// FindNextFile wraps syscall.FindNextFile.
func (fd *FD) FindNextFile(data *syscall.Win32finddata) error {
if err := fd.incref(); err != nil {
return err
}
defer fd.decref()
return syscall.FindNextFile(fd.Sysfd, data)
}
// Fchdir wraps syscall.Fchdir.
func (fd *FD) Fchdir() error {
if err := fd.incref(); err != nil {
return err
}
defer fd.decref()
return syscall.Fchdir(fd.Sysfd)
}
// GetFileType wraps syscall.GetFileType.
func (fd *FD) GetFileType() (uint32, error) {
if err := fd.incref(); err != nil {
return 0, err
}
defer fd.decref()
return syscall.GetFileType(fd.Sysfd)
}
// GetFileInformationByHandle wraps GetFileInformationByHandle.
func (fd *FD) GetFileInformationByHandle(data *syscall.ByHandleFileInformation) error {
if err := fd.incref(); err != nil {
return err
}
defer fd.decref()
return syscall.GetFileInformationByHandle(fd.Sysfd, data)
}
// RawControl invokes the user-defined function f for a non-IO
// operation.
func (fd *FD) RawControl(f func(uintptr)) error {
if err := fd.incref(); err != nil {
return err
}
defer fd.decref()
f(uintptr(fd.Sysfd))
return nil
}
// RawRead invokes the user-defined function f for a read operation.
func (fd *FD) RawRead(f func(uintptr) bool) error {
if err := fd.readLock(); err != nil {
return err
}
defer fd.readUnlock()
for {
if f(uintptr(fd.Sysfd)) {
return nil
}
// Use a zero-byte read as a way to get notified when this
// socket is readable. h/t https://stackoverflow.com/a/42019668/332798
o := &fd.rop
o.InitBuf(nil)
if !fd.IsStream {
o.flags |= windows.MSG_PEEK
}
_, err := rsrv.ExecIO(o, func(o *operation) error {
return syscall.WSARecv(o.fd.Sysfd, &o.buf, 1, &o.qty, &o.flags, &o.o, nil)
})
if err == windows.WSAEMSGSIZE {
// expected with a 0-byte peek, ignore.
} else if err != nil {
return err
}
}
}
// RawWrite invokes the user-defined function f for a write operation.
func (fd *FD) RawWrite(f func(uintptr) bool) error {
if err := fd.writeLock(); err != nil {
return err
}
defer fd.writeUnlock()
if f(uintptr(fd.Sysfd)) {
return nil
}
// TODO(tmm1): find a way to detect socket writability
return syscall.EWINDOWS
}
func sockaddrToRaw(sa syscall.Sockaddr) (unsafe.Pointer, int32, error) {
switch sa := sa.(type) {
case *syscall.SockaddrInet4:
var raw syscall.RawSockaddrInet4
raw.Family = syscall.AF_INET
p := (*[2]byte)(unsafe.Pointer(&raw.Port))
p[0] = byte(sa.Port >> 8)
p[1] = byte(sa.Port)
for i := 0; i < len(sa.Addr); i++ {
raw.Addr[i] = sa.Addr[i]
}
return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw)), nil
case *syscall.SockaddrInet6:
var raw syscall.RawSockaddrInet6
raw.Family = syscall.AF_INET6
p := (*[2]byte)(unsafe.Pointer(&raw.Port))
p[0] = byte(sa.Port >> 8)
p[1] = byte(sa.Port)
raw.Scope_id = sa.ZoneId
for i := 0; i < len(sa.Addr); i++ {
raw.Addr[i] = sa.Addr[i]
}
return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw)), nil
default:
return nil, 0, syscall.EWINDOWS
}
}
// ReadMsg wraps the WSARecvMsg network call.
func (fd *FD) ReadMsg(p []byte, oob []byte) (int, int, int, syscall.Sockaddr, error) {
if err := fd.readLock(); err != nil {
return 0, 0, 0, nil, err
}
defer fd.readUnlock()
if len(p) > maxRW {
p = p[:maxRW]
}
o := &fd.rop
o.InitMsg(p, oob)
o.rsa = new(syscall.RawSockaddrAny)
o.msg.Name = o.rsa
o.msg.Namelen = int32(unsafe.Sizeof(*o.rsa))
n, err := rsrv.ExecIO(o, func(o *operation) error {
return windows.WSARecvMsg(o.fd.Sysfd, &o.msg, &o.qty, &o.o, nil)
})
err = fd.eofError(n, err)
var sa syscall.Sockaddr
if err == nil {
sa, err = o.rsa.Sockaddr()
}
return n, int(o.msg.Control.Len), int(o.msg.Flags), sa, err
}
// WriteMsg wraps the WSASendMsg network call.
func (fd *FD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (int, int, error) {
if len(p) > maxRW {
return 0, 0, errors.New("packet is too large (only 1GB is allowed)")
}
if err := fd.writeLock(); err != nil {
return 0, 0, err
}
defer fd.writeUnlock()
o := &fd.wop
o.InitMsg(p, oob)
if sa != nil {
rsa, len, err := sockaddrToRaw(sa)
if err != nil {
return 0, 0, err
}
o.msg.Name = (*syscall.RawSockaddrAny)(rsa)
o.msg.Namelen = len
}
n, err := wsrv.ExecIO(o, func(o *operation) error {
return windows.WSASendMsg(o.fd.Sysfd, &o.msg, 0, &o.qty, &o.o, nil)
})
return n, int(o.msg.Control.Len), err
}