func (info DeviceInfo) Load() (Device, error) {
// Find the appropriate driver.
driver, ok := drivers[info.Driver]
if !ok {
return nil, DriverUnknown(info.Driver)
}
// Load the driver.
device, err := driver(&info)
if err != nil {
return nil, err
}
if info.Data != nil {
// Scratch data.
buffer := bytes.NewBuffer(nil)
// Encode the original object.
encoder := utils.NewEncoder(buffer)
err = encoder.Encode(info.Data)
if err != nil {
return nil, err
}
// Decode a new object.
// This will override all the default
// settings in the initialized object.
decoder := utils.NewDecoder(buffer)
log.Printf("Loading %s...", device.Name())
err = decoder.Decode(device)
if err != nil {
return nil, err
}
}
// Save the original device.
// This will allow us to implement a
// simple Save() method that serializes
// the state of this device as it exists.
info.Data = device
// We're done.
return device, nil
}
func (control *Control) handle(
conn_fd int,
server *rpc.Server) {
control_file := os.NewFile(uintptr(conn_fd), "control")
defer control_file.Close()
// Read single header.
// Our header is exactly 9 characters, and we
// expect the last character to be a newline.
// This is a simple plaintext protocol.
header_buf := make([]byte, 9, 9)
n, err := control_file.Read(header_buf)
if n != 9 || header_buf[8] != '\n' {
if err != nil {
control_file.Write([]byte(err.Error()))
} else {
control_file.Write([]byte("invalid header"))
}
return
}
header := string(header_buf)
// We read a special header before diving into RPC
// mode. This is because for the novmrun case, we turn
// the socket into a stream of input/output events.
// These are simply JSON serialized versions of the
// events for the guest RPC interface.
if header == "NOVM RUN\n" {
decoder := utils.NewDecoder(control_file)
encoder := utils.NewEncoder(control_file)
var start noguest.StartCommand
err := decoder.Decode(&start)
if err != nil {
// Poorly encoded command.
encoder.Encode(err.Error())
return
}
// Grab our client.
client, err := control.Ready()
if err != nil {
encoder.Encode(err.Error())
return
}
// Call start.
result := noguest.StartResult{}
err = client.Call("Server.Start", &start, &result)
if err != nil {
encoder.Encode(err.Error())
return
}
// Save our pid.
pid := result.Pid
inputs := make(chan error)
outputs := make(chan error)
exitcode := make(chan int)
// This indicates we're okay.
encoder.Encode(nil)
// Wait for the process to exit.
go func() {
wait := noguest.WaitCommand{
Pid: pid,
}
var wait_result noguest.WaitResult
err := client.Call("Server.Wait", &wait, &wait_result)
if err != nil {
exitcode <- 1
} else {
exitcode <- wait_result.Exitcode
}
}()
// Read from stdout & stderr.
go func() {
read := noguest.ReadCommand{
Pid: pid,
N: 4096,
}
var read_result noguest.ReadResult
for {
err := client.Call("Server.Read", &read, &read_result)
if err != nil {
inputs <- err
return
}
err = encoder.Encode(read_result.Data)
if err != nil {
inputs <- err
return
}
}
}()
// Write to stdin.
go func() {
write := noguest.WriteCommand{
Pid: pid,
}
var write_result noguest.WriteResult
for {
err := decoder.Decode(&write.Data)
if err != nil {
outputs <- err
return
}
err = client.Call("Server.Write", &write, &write_result)
if err != nil {
outputs <- err
return
}
}
}()
// Wait till exit.
status := <-exitcode
encoder.Encode(status)
// Wait till EOF.
<-inputs
// Send a notice and close the socket.
encoder.Encode(nil)
} else if header == "NOVM RPC\n" {
// Run as JSON RPC connection.
codec := jsonrpc.NewServerCodec(control_file)
server.ServeCodec(codec)
}
}
func restart(
model *machine.Model,
vm *platform.Vm,
is_tracing bool,
stop bool) error {
// Get our binary.
bin, err := os.Readlink("/proc/self/exe")
if err != nil {
return err
}
_, err = os.Stat(bin)
if err != nil {
// If this is no longer the same binary, then the
// kernel proc node will have "fixed" the symlink
// to point to "/path (deleted)". This is mildly
// annoying, as one would assume there would be a
// better way of transmitting that information.
if os.IsNotExist(err) && strings.HasSuffix(bin, " (deleted)") {
bin = strings.TrimSuffix(bin, " (deleted)")
_, err = os.Stat(bin)
}
if err != nil {
return err
}
}
// Create our state.
state, err := control.SaveState(vm, model)
if err != nil {
return err
}
// Encode our state in a temporary file.
// This is passed in to the new VMM as the statefd.
// We unlink it immediately because we don't need to
// access it by name, and can ensure it is cleaned up.
// Note that the TempFile is normally opened CLOEXEC.
// This means that need we need to perform a DUP in
// order to get an FD that can pass to the child.
state_file, err := ioutil.TempFile(os.TempDir(), "state")
if err != nil {
return err
}
defer state_file.Close()
err = os.Remove(state_file.Name())
if err != nil {
return err
}
encoder := utils.NewEncoder(state_file)
err = encoder.Encode(&state)
if err != nil {
return err
}
_, err = state_file.Seek(0, 0)
if err != nil {
return err
}
state_fd, err := syscall.Dup(int(state_file.Fd()))
if err != nil {
return err
}
defer syscall.Close(state_fd)
// Prepare to reexec.
cmd := []string{
os.Args[0],
fmt.Sprintf("-controlfd=%d", *control_fd),
fmt.Sprintf("-statefd=%d", state_fd),
fmt.Sprintf("-trace=%t", is_tracing),
fmt.Sprintf("-paused=%t", *paused),
fmt.Sprintf("-stop=%t", stop),
}
return syscall.Exec(bin, cmd, os.Environ())
}
