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vmnet.go
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vmnet.go
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package vmnet
// #cgo CFLAGS: -x objective-c
// #cgo LDFLAGS: -lobjc -framework vmnet
// #include "vmnet.h"
import "C"
import (
"io"
"sync"
"unsafe"
)
type VMNet struct {
io.ReadWriter
iface C.interface_ref
mps C.ulonglong
MaxPacketSize int
}
func (v *VMNet) Start() error {
C._vmnet_start(&v.iface, &v.mps)
if v.iface == nil {
return ErrUnableToStart
}
v.MaxPacketSize = int(v.mps)
return nil
}
func (v *VMNet) Stop() error {
C._vmnet_stop(v.iface)
return nil
}
func (v *VMNet) Read(p []byte) (n int, err error) {
for {
var cBytes unsafe.Pointer
var cBytesLen C.ulong
C._vmnet_read(v.iface, v.mps, &cBytes, &cBytesLen)
if cBytes == nil || int(cBytesLen) == 0 {
waitForEvent()
continue
}
copy(p, C.GoBytes(cBytes, C.int(cBytesLen)))
return int(cBytesLen), nil
}
}
func (v *VMNet) Write(p []byte) (n int, err error) {
C._vmnet_write(v.iface, C.CBytes(p), C.ulong(len(p)))
return len(p), nil
}
func New() *VMNet {
return &VMNet{}
}
type EventType uint32
const (
packetsAvailableEvent EventType = 1 << 0
)
var eventQueue = make(chan bool, 1)
var eventQueueLock = new(sync.Mutex)
func waitForEvent() {
<-eventQueue
}
//export emitEvent
func emitEvent(eventType uint32, nPktAvail uint64) {
etype := EventType(eventType)
switch etype {
case packetsAvailableEvent:
eventQueueLock.Lock()
if len(eventQueue) == 0 {
eventQueue <- true
}
eventQueueLock.Unlock()
}
}