node_exporter/vendor/github.com/godbus/dbus/object.go

148 lines
3.9 KiB
Go

package dbus
import (
"errors"
"strings"
)
// BusObject is the interface of a remote object on which methods can be
// invoked.
type BusObject interface {
Call(method string, flags Flags, args ...interface{}) *Call
Go(method string, flags Flags, ch chan *Call, args ...interface{}) *Call
GetProperty(p string) (Variant, error)
Destination() string
Path() ObjectPath
}
// Object represents a remote object on which methods can be invoked.
type Object struct {
conn *Conn
dest string
path ObjectPath
}
// Call calls a method with (*Object).Go and waits for its reply.
func (o *Object) Call(method string, flags Flags, args ...interface{}) *Call {
return <-o.Go(method, flags, make(chan *Call, 1), args...).Done
}
// AddMatchSignal subscribes BusObject to signals from specified interface and
// method (member).
func (o *Object) AddMatchSignal(iface, member string) *Call {
return o.Call(
"org.freedesktop.DBus.AddMatch",
0,
"type='signal',interface='"+iface+"',member='"+member+"'",
)
}
// Go calls a method with the given arguments asynchronously. It returns a
// Call structure representing this method call. The passed channel will
// return the same value once the call is done. If ch is nil, a new channel
// will be allocated. Otherwise, ch has to be buffered or Go will panic.
//
// If the flags include FlagNoReplyExpected, ch is ignored and a Call structure
// is returned with any error in Err and a closed channel in Done containing
// the returned Call as it's one entry.
//
// If the method parameter contains a dot ('.'), the part before the last dot
// specifies the interface on which the method is called.
func (o *Object) Go(method string, flags Flags, ch chan *Call, args ...interface{}) *Call {
iface := ""
i := strings.LastIndex(method, ".")
if i != -1 {
iface = method[:i]
}
method = method[i+1:]
msg := new(Message)
msg.Type = TypeMethodCall
msg.serial = o.conn.getSerial()
msg.Flags = flags & (FlagNoAutoStart | FlagNoReplyExpected)
msg.Headers = make(map[HeaderField]Variant)
msg.Headers[FieldPath] = MakeVariant(o.path)
msg.Headers[FieldDestination] = MakeVariant(o.dest)
msg.Headers[FieldMember] = MakeVariant(method)
if iface != "" {
msg.Headers[FieldInterface] = MakeVariant(iface)
}
msg.Body = args
if len(args) > 0 {
msg.Headers[FieldSignature] = MakeVariant(SignatureOf(args...))
}
if msg.Flags&FlagNoReplyExpected == 0 {
if ch == nil {
ch = make(chan *Call, 10)
} else if cap(ch) == 0 {
panic("dbus: unbuffered channel passed to (*Object).Go")
}
call := &Call{
Destination: o.dest,
Path: o.path,
Method: method,
Args: args,
Done: ch,
}
o.conn.callsLck.Lock()
o.conn.calls[msg.serial] = call
o.conn.callsLck.Unlock()
o.conn.outLck.RLock()
if o.conn.closed {
call.Err = ErrClosed
call.Done <- call
} else {
o.conn.out <- msg
}
o.conn.outLck.RUnlock()
return call
}
o.conn.outLck.RLock()
defer o.conn.outLck.RUnlock()
done := make(chan *Call, 1)
call := &Call{
Err: nil,
Done: done,
}
defer func() {
call.Done <- call
close(done)
}()
if o.conn.closed {
call.Err = ErrClosed
return call
}
o.conn.out <- msg
return call
}
// GetProperty calls org.freedesktop.DBus.Properties.GetProperty on the given
// object. The property name must be given in interface.member notation.
func (o *Object) GetProperty(p string) (Variant, error) {
idx := strings.LastIndex(p, ".")
if idx == -1 || idx+1 == len(p) {
return Variant{}, errors.New("dbus: invalid property " + p)
}
iface := p[:idx]
prop := p[idx+1:]
result := Variant{}
err := o.Call("org.freedesktop.DBus.Properties.Get", 0, iface, prop).Store(&result)
if err != nil {
return Variant{}, err
}
return result, nil
}
// Destination returns the destination that calls on (o *Object) are sent to.
func (o *Object) Destination() string {
return o.dest
}
// Path returns the path that calls on (o *Object") are sent to.
func (o *Object) Path() ObjectPath {
return o.path
}