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export.go
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export.go
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package dbus
import (
"errors"
"reflect"
"strings"
"unicode"
)
var (
errmsgInvalidArg = Error{
"org.freedesktop.DBus.Error.InvalidArgs",
[]interface{}{"Invalid type / number of args"},
}
errmsgNoObject = Error{
"org.freedesktop.DBus.Error.NoSuchObject",
[]interface{}{"No such object"},
}
errmsgUnknownMethod = Error{
"org.freedesktop.DBus.Error.UnknownMethod",
[]interface{}{"Unknown / invalid method"},
}
)
// Sender is a type which can be used in exported methods to receive the message
// sender.
type Sender string
func exportedMethod(v interface{}, name string) reflect.Value {
if v == nil {
return reflect.Value{}
}
m := reflect.ValueOf(v).MethodByName(name)
if !m.IsValid() {
return reflect.Value{}
}
t := m.Type()
if t.NumOut() == 0 ||
t.Out(t.NumOut()-1) != reflect.TypeOf(&errmsgInvalidArg) {
return reflect.Value{}
}
return m
}
// handleCall handles the given method call (i.e. looks if it's one of the
// pre-implemented ones and searches for a corresponding handler if not).
func (conn *Conn) handleCall(msg *Message) {
name := msg.Headers[FieldMember].value.(string)
path := msg.Headers[FieldPath].value.(ObjectPath)
ifaceName, hasIface := msg.Headers[FieldInterface].value.(string)
sender, hasSender := msg.Headers[FieldSender].value.(string)
serial := msg.serial
if ifaceName == "org.freedesktop.DBus.Peer" {
switch name {
case "Ping":
conn.sendReply(sender, serial)
case "GetMachineId":
conn.sendReply(sender, serial, conn.uuid)
default:
conn.sendError(errmsgUnknownMethod, sender, serial)
}
return
}
if len(name) == 0 || unicode.IsLower([]rune(name)[0]) {
conn.sendError(errmsgUnknownMethod, sender, serial)
}
var m reflect.Value
if hasIface {
conn.handlersLck.RLock()
obj, ok := conn.handlers[path]
if !ok {
conn.sendError(errmsgNoObject, sender, serial)
conn.handlersLck.RUnlock()
return
}
iface := obj[ifaceName]
conn.handlersLck.RUnlock()
m = exportedMethod(iface, name)
} else {
conn.handlersLck.RLock()
if _, ok := conn.handlers[path]; !ok {
conn.sendError(errmsgNoObject, sender, serial)
conn.handlersLck.RUnlock()
return
}
for _, v := range conn.handlers[path] {
m = exportedMethod(v, name)
if m.IsValid() {
break
}
}
conn.handlersLck.RUnlock()
}
if !m.IsValid() {
conn.sendError(errmsgUnknownMethod, sender, serial)
return
}
t := m.Type()
vs := msg.Body
pointers := make([]interface{}, t.NumIn())
decode := make([]interface{}, 0, len(vs))
for i := 0; i < t.NumIn(); i++ {
tp := t.In(i)
val := reflect.New(tp)
pointers[i] = val.Interface()
if tp == reflect.TypeOf((*Sender)(nil)).Elem() {
val.Elem().SetString(sender)
} else {
decode = append(decode, pointers[i])
}
}
if len(decode) != len(vs) {
conn.sendError(errmsgInvalidArg, sender, serial)
return
}
if err := Store(vs, decode...); err != nil {
conn.sendError(errmsgInvalidArg, sender, serial)
return
}
params := make([]reflect.Value, len(pointers))
for i := 0; i < len(pointers); i++ {
params[i] = reflect.ValueOf(pointers[i]).Elem()
}
ret := m.Call(params)
if em := ret[t.NumOut()-1].Interface().(*Error); em != nil {
conn.sendError(*em, sender, serial)
return
}
if msg.Flags&FlagNoReplyExpected == 0 {
reply := new(Message)
reply.Type = TypeMethodReply
reply.serial = conn.getSerial()
reply.Headers = make(map[HeaderField]Variant)
if hasSender {
reply.Headers[FieldDestination] = msg.Headers[FieldSender]
}
reply.Headers[FieldReplySerial] = MakeVariant(msg.serial)
reply.Body = make([]interface{}, len(ret)-1)
for i := 0; i < len(ret)-1; i++ {
reply.Body[i] = ret[i].Interface()
}
if len(ret) != 1 {
reply.Headers[FieldSignature] = MakeVariant(SignatureOf(reply.Body...))
}
conn.outLck.RLock()
if !conn.closed {
conn.out <- reply
}
conn.outLck.RUnlock()
}
}
// Emit emits the given signal on the message bus. The name parameter must be
// formatted as "interface.member", e.g., "org.freedesktop.DBus.NameLost".
func (conn *Conn) Emit(path ObjectPath, name string, values ...interface{}) error {
if !path.IsValid() {
return errors.New("dbus: invalid object path")
}
i := strings.LastIndex(name, ".")
if i == -1 {
return errors.New("dbus: invalid method name")
}
iface := name[:i]
member := name[i+1:]
if !isValidMember(member) {
return errors.New("dbus: invalid method name")
}
if !isValidInterface(iface) {
return errors.New("dbus: invalid interface name")
}
msg := new(Message)
msg.Type = TypeSignal
msg.serial = conn.getSerial()
msg.Headers = make(map[HeaderField]Variant)
msg.Headers[FieldInterface] = MakeVariant(iface)
msg.Headers[FieldMember] = MakeVariant(member)
msg.Headers[FieldPath] = MakeVariant(path)
msg.Body = values
if len(values) > 0 {
msg.Headers[FieldSignature] = MakeVariant(SignatureOf(values...))
}
conn.outLck.RLock()
defer conn.outLck.RUnlock()
if conn.closed {
return ErrClosed
}
conn.out <- msg
return nil
}
// Export registers the given value to be exported as an object on the
// message bus.
//
// If a method call on the given path and interface is received, an exported
// method with the same name is called with v as the receiver if the
// parameters match and the last return value is of type *Error. If this
// *Error is not nil, it is sent back to the caller as an error.
// Otherwise, a method reply is sent with the other return values as its body.
//
// Any parameters with the special type Sender are set to the sender of the
// dbus message when the method is called. Parameters of this type do not
// contribute to the dbus signature of the method (i.e. the method is exposed
// as if the parameters of type Sender were not there).
//
// Every method call is executed in a new goroutine, so the method may be called
// in multiple goroutines at once.
//
// Method calls on the interface org.freedesktop.DBus.Peer will be automatically
// handled for every object.
//
// Passing nil as the first parameter will cause conn to cease handling calls on
// the given combination of path and interface.
//
// Export returns an error if path is not a valid path name.
func (conn *Conn) Export(v interface{}, path ObjectPath, iface string) error {
if !path.IsValid() {
return errors.New("dbus: invalid path name")
}
conn.handlersLck.Lock()
if v == nil {
if _, ok := conn.handlers[path]; ok {
delete(conn.handlers[path], iface)
if len(conn.handlers[path]) == 0 {
delete(conn.handlers, path)
}
}
return nil
}
if _, ok := conn.handlers[path]; !ok {
conn.handlers[path] = make(map[string]interface{})
}
conn.handlers[path][iface] = v
conn.handlersLck.Unlock()
return nil
}
// ReleaseName calls org.freedesktop.DBus.ReleaseName. You should use only this
// method to release a name (see below).
func (conn *Conn) ReleaseName(name string) (ReleaseNameReply, error) {
var r uint32
err := conn.busObj.Call("org.freedesktop.DBus.ReleaseName", 0, name).Store(&r)
if err != nil {
return 0, err
}
if r == uint32(ReleaseNameReplyReleased) {
conn.namesLck.Lock()
for i, v := range conn.names {
if v == name {
copy(conn.names[i:], conn.names[i+1:])
conn.names = conn.names[:len(conn.names)-1]
}
}
conn.namesLck.Unlock()
}
return ReleaseNameReply(r), nil
}
// RequestName calls org.freedesktop.DBus.RequestName. You should use only this
// method to request a name because package dbus needs to keep track of all
// names that the connection has.
func (conn *Conn) RequestName(name string, flags RequestNameFlags) (RequestNameReply, error) {
var r uint32
err := conn.busObj.Call("org.freedesktop.DBus.RequestName", 0, name, flags).Store(&r)
if err != nil {
return 0, err
}
if r == uint32(RequestNameReplyPrimaryOwner) {
conn.namesLck.Lock()
conn.names = append(conn.names, name)
conn.namesLck.Unlock()
}
return RequestNameReply(r), nil
}
// ReleaseNameReply is the reply to a ReleaseName call.
type ReleaseNameReply uint32
const (
ReleaseNameReplyReleased ReleaseNameReply = 1 + iota
ReleaseNameReplyNonExistent
ReleaseNameReplyNotOwner
)
// RequestNameFlags represents the possible flags for a RequestName call.
type RequestNameFlags uint32
const (
NameFlagAllowReplacement RequestNameFlags = 1 << iota
NameFlagReplaceExisting
NameFlagDoNotQueue
)
// RequestNameReply is the reply to a RequestName call.
type RequestNameReply uint32
const (
RequestNameReplyPrimaryOwner RequestNameReply = 1 + iota
RequestNameReplyInQueue
RequestNameReplyExists
RequestNameReplyAlreadyOwner
)