/usr/share/gocode/src/github.com/linuxkit/virtsock/pkg/hvsock/hvsock_windows.go is in golang-github-linuxkit-virtsock-dev 0.0~git20170720.0.0416e3d-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"errors"
"io"
"log"
"runtime"
"sync"
"sync/atomic"
"syscall"
"time"
"unsafe"
)
// Make sure Winsock2 is initialised
func init() {
e := syscall.WSAStartup(uint32(0x202), &wsaData)
if e != nil {
log.Fatal("WSAStartup", e)
}
}
const (
sysAF_HYPERV = 34
sysSHV_PROTO_RAW = 1
socket_error = uintptr(^uint32(0))
)
var (
ErrTimeout = &timeoutError{}
wsaData syscall.WSAData
)
// struck sockaddr equivalent
type rawSockaddrHyperv struct {
Family uint16
Reserved uint16
VMID GUID
ServiceID GUID
}
type hvsockListener struct {
acceptFD syscall.Handle
laddr HypervAddr
}
// Internal representation. Complex mostly due to asynch send()/recv() syscalls.
type hvsockConn struct {
fd syscall.Handle
local HypervAddr
remote HypervAddr
wg sync.WaitGroup
closing bool
readDeadline deadlineHandler
writeDeadline deadlineHandler
}
type deadlineHandler struct {
setLock sync.Mutex
channel timeoutChan
channelLock sync.RWMutex
timer *time.Timer
timedout atomicBool
}
// Main constructor
func newHVsockConn(h syscall.Handle, local HypervAddr, remote HypervAddr) (*HVsockConn, error) {
ioInitOnce.Do(initIo)
v := &hvsockConn{fd: h, local: local, remote: remote}
_, err := createIoCompletionPort(h, ioCompletionPort, 0, 0xffffffff)
if err != nil {
return nil, err
}
err = setFileCompletionNotificationModes(h,
cFILE_SKIP_COMPLETION_PORT_ON_SUCCESS|cFILE_SKIP_SET_EVENT_ON_HANDLE)
if err != nil {
return nil, err
}
v.readDeadline.channel = make(timeoutChan)
v.writeDeadline.channel = make(timeoutChan)
return &HVsockConn{hvsockConn: *v}, nil
}
// Utility function to build a struct sockaddr for syscalls.
func (a HypervAddr) sockaddr(sa *rawSockaddrHyperv) (unsafe.Pointer, int32, error) {
sa.Family = sysAF_HYPERV
sa.Reserved = 0
for i := 0; i < len(sa.VMID); i++ {
sa.VMID[i] = a.VMID[i]
}
for i := 0; i < len(sa.ServiceID); i++ {
sa.ServiceID[i] = a.ServiceID[i]
}
return unsafe.Pointer(sa), int32(unsafe.Sizeof(*sa)), nil
}
func hvsocket(typ, proto int) (syscall.Handle, error) {
return syscall.Socket(sysAF_HYPERV, typ, proto)
}
func connect(s syscall.Handle, a *HypervAddr) (err error) {
var sa rawSockaddrHyperv
ptr, n, err := a.sockaddr(&sa)
if err != nil {
return err
}
return sys_connect(s, ptr, n)
}
func bind(s syscall.Handle, a HypervAddr) error {
var sa rawSockaddrHyperv
ptr, n, err := a.sockaddr(&sa)
if err != nil {
return err
}
return sys_bind(s, ptr, n)
}
func accept(s syscall.Handle, a *HypervAddr) (syscall.Handle, error) {
return 0, errors.New("accept(): Unimplemented")
}
//
// File IO/Socket interface
//
func (v *HVsockConn) close() error {
v.closeHandle()
return nil
}
// Underlying raw read() function.
func (v *HVsockConn) read(buf []byte) (int, error) {
var b syscall.WSABuf
var f uint32
b.Len = uint32(len(buf))
b.Buf = &buf[0]
c, err := v.prepareIo()
if err != nil {
return 0, err
}
if v.readDeadline.timedout.isSet() {
return 0, ErrTimeout
}
var bytes uint32
err = syscall.WSARecv(v.fd, &b, 1, &bytes, &f, &c.o, nil)
n, err := v.asyncIo(c, &v.readDeadline, bytes, err)
runtime.KeepAlive(buf)
// Handle EOF conditions.
if err == nil && n == 0 && len(buf) != 0 {
return 0, io.EOF
} else if err == syscall.ERROR_BROKEN_PIPE {
return 0, io.EOF
} else {
return n, err
}
}
// Underlying raw write() function.
func (v *HVsockConn) write(buf []byte) (int, error) {
var b syscall.WSABuf
var f uint32
if len(buf) == 0 {
return 0, nil
}
f = 0
b.Len = uint32(len(buf))
b.Buf = &buf[0]
c, err := v.prepareIo()
if err != nil {
return 0, err
}
if v.writeDeadline.timedout.isSet() {
return 0, ErrTimeout
}
var bytes uint32
err = syscall.WSASend(v.fd, &b, 1, &bytes, f, &c.o, nil)
n, err := v.asyncIo(c, &v.writeDeadline, bytes, err)
runtime.KeepAlive(buf)
return n, err
}
// SetReadDeadline implementation for Hyper-V sockets
func (v *HVsockConn) SetReadDeadline(deadline time.Time) error {
return v.readDeadline.set(deadline)
}
// SetWriteDeadline implementation for Hyper-V sockets
func (v *HVsockConn) SetWriteDeadline(deadline time.Time) error {
return v.writeDeadline.set(deadline)
}
// SetDeadline implementation for Hyper-V sockets
func (v *HVsockConn) SetDeadline(deadline time.Time) error {
if err := v.SetReadDeadline(deadline); err != nil {
return err
}
return v.SetWriteDeadline(deadline)
}
// The code below here is adjusted from:
// https://github.com/Microsoft/go-winio/blob/master/file.go
type atomicBool int32
func (b *atomicBool) isSet() bool { return atomic.LoadInt32((*int32)(b)) != 0 }
func (b *atomicBool) setFalse() { atomic.StoreInt32((*int32)(b), 0) }
func (b *atomicBool) setTrue() { atomic.StoreInt32((*int32)(b), 1) }
const (
cFILE_SKIP_COMPLETION_PORT_ON_SUCCESS = 1
cFILE_SKIP_SET_EVENT_ON_HANDLE = 2
)
type timeoutError struct{}
func (e *timeoutError) Error() string { return "i/o timeout" }
func (e *timeoutError) Timeout() bool { return true }
func (e *timeoutError) Temporary() bool { return true }
type timeoutChan chan struct{}
var ioInitOnce sync.Once
var ioCompletionPort syscall.Handle
// ioResult contains the result of an asynchronous IO operation
type ioResult struct {
bytes uint32
err error
}
type ioOperation struct {
o syscall.Overlapped
ch chan ioResult
}
func initIo() {
h, err := createIoCompletionPort(syscall.InvalidHandle, 0, 0, 0xffffffff)
if err != nil {
panic(err)
}
ioCompletionPort = h
go ioCompletionProcessor(h)
}
func (v *hvsockConn) closeHandle() {
if !v.closing {
// cancel all IO and wait for it to complete
v.closing = true
cancelIoEx(v.fd, nil)
v.wg.Wait()
// at this point, no new IO can start
syscall.Close(v.fd)
v.fd = 0
}
}
// prepareIo prepares for a new IO operation
func (v *hvsockConn) prepareIo() (*ioOperation, error) {
v.wg.Add(1)
if v.closing {
return nil, ErrSocketClosed
}
c := &ioOperation{}
c.ch = make(chan ioResult)
return c, nil
}
// ioCompletionProcessor processes completed async IOs forever
func ioCompletionProcessor(h syscall.Handle) {
// Set the timer resolution to 1. This fixes a performance regression in golang 1.6.
timeBeginPeriod(1)
for {
var bytes uint32
var key uintptr
var op *ioOperation
err := getQueuedCompletionStatus(h, &bytes, &key, &op, syscall.INFINITE)
if op == nil {
panic(err)
}
op.ch <- ioResult{bytes, err}
}
}
// asyncIo processes the return value from Recv or Send, blocking until
// the operation has actually completed.
func (v *hvsockConn) asyncIo(c *ioOperation, d *deadlineHandler, bytes uint32, err error) (int, error) {
if err != syscall.ERROR_IO_PENDING {
v.wg.Done()
return int(bytes), err
}
if v.closing {
cancelIoEx(v.fd, &c.o)
}
var timeout timeoutChan
if d != nil {
d.channelLock.Lock()
timeout = d.channel
d.channelLock.Unlock()
}
var r ioResult
select {
case r = <-c.ch:
err = r.err
if err == syscall.ERROR_OPERATION_ABORTED {
if v.closing {
err = ErrSocketClosed
}
}
case <-timeout:
cancelIoEx(v.fd, &c.o)
r = <-c.ch
err = r.err
if err == syscall.ERROR_OPERATION_ABORTED {
err = ErrTimeout
}
}
// runtime.KeepAlive is needed, as c is passed via native
// code to ioCompletionProcessor, c must remain alive
// until the channel read is complete.
runtime.KeepAlive(c)
v.wg.Done()
return int(r.bytes), err
}
func (d *deadlineHandler) set(deadline time.Time) error {
d.setLock.Lock()
defer d.setLock.Unlock()
if d.timer != nil {
if !d.timer.Stop() {
<-d.channel
}
d.timer = nil
}
d.timedout.setFalse()
select {
case <-d.channel:
d.channelLock.Lock()
d.channel = make(chan struct{})
d.channelLock.Unlock()
default:
}
if deadline.IsZero() {
return nil
}
timeoutIO := func() {
d.timedout.setTrue()
close(d.channel)
}
now := time.Now()
duration := deadline.Sub(now)
if deadline.After(now) {
// Deadline is in the future, set a timer to wait
d.timer = time.AfterFunc(duration, timeoutIO)
} else {
// Deadline is in the past. Cancel all pending IO now.
timeoutIO()
}
return nil
}
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