subsonic-tui/vendor/github.com/godbus/dbus/v5/prop/prop.go
Sagi Dayan a3923cf42c initial commit
Signed-off-by: Sagi Dayan <sagidayan@gmail.com>
2024-03-29 17:56:39 +03:00

348 lines
10 KiB
Go

// Package prop provides the Properties struct which can be used to implement
// org.freedesktop.DBus.Properties.
package prop
import (
"reflect"
"sync"
"github.com/godbus/dbus/v5"
"github.com/godbus/dbus/v5/introspect"
)
// EmitType controls how org.freedesktop.DBus.Properties.PropertiesChanged is
// emitted for a property. If it is EmitTrue, the signal is emitted. If it is
// EmitInvalidates, the signal is also emitted, but the new value of the property
// is not disclosed. If it is EmitConst, the property never changes value during
// the lifetime of the object it belongs to, and hence the signal is never emitted
// for it.
type EmitType byte
const (
EmitFalse EmitType = iota
EmitTrue
EmitInvalidates
EmitConst
)
func (e EmitType) String() (str string) {
switch e {
case EmitFalse:
str = "false"
case EmitTrue:
str = "true"
case EmitInvalidates:
str = "invalidates"
case EmitConst:
str = "const"
default:
panic("invalid value for EmitType")
}
return
}
// ErrIfaceNotFound is the error returned to peers who try to access properties
// on interfaces that aren't found.
var ErrIfaceNotFound = dbus.NewError("org.freedesktop.DBus.Properties.Error.InterfaceNotFound", nil)
// ErrPropNotFound is the error returned to peers trying to access properties
// that aren't found.
var ErrPropNotFound = dbus.NewError("org.freedesktop.DBus.Properties.Error.PropertyNotFound", nil)
// ErrReadOnly is the error returned to peers trying to set a read-only
// property.
var ErrReadOnly = dbus.NewError("org.freedesktop.DBus.Properties.Error.ReadOnly", nil)
// ErrInvalidArg is returned to peers if the type of the property that is being
// changed and the argument don't match.
var ErrInvalidArg = dbus.NewError("org.freedesktop.DBus.Properties.Error.InvalidArg", nil)
// The introspection data for the org.freedesktop.DBus.Properties interface.
var IntrospectData = introspect.Interface{
Name: "org.freedesktop.DBus.Properties",
Methods: []introspect.Method{
{
Name: "Get",
Args: []introspect.Arg{
{Name: "interface", Type: "s", Direction: "in"},
{Name: "property", Type: "s", Direction: "in"},
{Name: "value", Type: "v", Direction: "out"},
},
},
{
Name: "GetAll",
Args: []introspect.Arg{
{Name: "interface", Type: "s", Direction: "in"},
{Name: "props", Type: "a{sv}", Direction: "out"},
},
},
{
Name: "Set",
Args: []introspect.Arg{
{Name: "interface", Type: "s", Direction: "in"},
{Name: "property", Type: "s", Direction: "in"},
{Name: "value", Type: "v", Direction: "in"},
},
},
},
Signals: []introspect.Signal{
{
Name: "PropertiesChanged",
Args: []introspect.Arg{
{Name: "interface", Type: "s", Direction: "out"},
{Name: "changed_properties", Type: "a{sv}", Direction: "out"},
{Name: "invalidates_properties", Type: "as", Direction: "out"},
},
},
},
}
// The introspection data for the org.freedesktop.DBus.Properties interface, as
// a string.
const IntrospectDataString = `
<interface name="org.freedesktop.DBus.Properties">
<method name="Get">
<arg name="interface" direction="in" type="s"/>
<arg name="property" direction="in" type="s"/>
<arg name="value" direction="out" type="v"/>
</method>
<method name="GetAll">
<arg name="interface" direction="in" type="s"/>
<arg name="props" direction="out" type="a{sv}"/>
</method>
<method name="Set">
<arg name="interface" direction="in" type="s"/>
<arg name="property" direction="in" type="s"/>
<arg name="value" direction="in" type="v"/>
</method>
<signal name="PropertiesChanged">
<arg name="interface" type="s"/>
<arg name="changed_properties" type="a{sv}"/>
<arg name="invalidates_properties" type="as"/>
</signal>
</interface>
`
// Prop represents a single property. It is used for creating a Properties
// value.
type Prop struct {
// Initial value. Must be a DBus-representable type. This is not modified
// after Properties has been initialized; use Get or GetMust to access the
// value.
Value interface{}
// If true, the value can be modified by calls to Set.
Writable bool
// Controls how org.freedesktop.DBus.Properties.PropertiesChanged is
// emitted if this property changes.
Emit EmitType
// If not nil, anytime this property is changed by Set, this function is
// called with an appropriate Change as its argument. If the returned error
// is not nil, it is sent back to the caller of Set and the property is not
// changed.
Callback func(*Change) *dbus.Error
}
// Introspection returns the introspection data for p.
// The "name" argument is used as the property's name in the resulting data.
func (p *Prop) Introspection(name string) introspect.Property {
var result = introspect.Property{Name: name, Type: dbus.SignatureOf(p.Value).String()}
if p.Writable {
result.Access = "readwrite"
} else {
result.Access = "read"
}
result.Annotations = []introspect.Annotation{
{
Name: "org.freedesktop.DBus.Property.EmitsChangedSignal",
Value: p.Emit.String(),
},
}
return result
}
// Change represents a change of a property by a call to Set.
type Change struct {
Props *Properties
Iface string
Name string
Value interface{}
}
// Properties is a set of values that can be made available to the message bus
// using the org.freedesktop.DBus.Properties interface. It is safe for
// concurrent use by multiple goroutines.
type Properties struct {
m Map
mut sync.RWMutex
conn *dbus.Conn
path dbus.ObjectPath
}
// New falls back to Export, but it returns nil if properties export fails,
// swallowing the error, shouldn't be used.
//
// Deprecated: use Export instead.
func New(conn *dbus.Conn, path dbus.ObjectPath, props Map) *Properties {
p, err := Export(conn, path, props)
if err != nil {
return nil
}
return p
}
// Export returns a new Properties structure that manages the given properties.
// The key for the first-level map of props is the name of the interface; the
// second-level key is the name of the property. The returned structure will be
// exported as org.freedesktop.DBus.Properties on path.
func Export(
conn *dbus.Conn, path dbus.ObjectPath, props Map,
) (*Properties, error) {
p := &Properties{m: copyProps(props), conn: conn, path: path}
if err := conn.Export(p, path, "org.freedesktop.DBus.Properties"); err != nil {
return nil, err
}
return p, nil
}
// Map is a helper type for supplying the configuration of properties to be handled.
type Map = map[string]map[string]*Prop
func copyProps(in Map) Map {
out := make(Map, len(in))
for intf, props := range in {
out[intf] = make(map[string]*Prop)
for name, prop := range props {
out[intf][name] = new(Prop)
*out[intf][name] = *prop
val := reflect.New(reflect.TypeOf(prop.Value))
val.Elem().Set(reflect.ValueOf(prop.Value))
out[intf][name].Value = val.Interface()
}
}
return out
}
// Get implements org.freedesktop.DBus.Properties.Get.
func (p *Properties) Get(iface, property string) (dbus.Variant, *dbus.Error) {
p.mut.RLock()
defer p.mut.RUnlock()
m, ok := p.m[iface]
if !ok {
return dbus.Variant{}, ErrIfaceNotFound
}
prop, ok := m[property]
if !ok {
return dbus.Variant{}, ErrPropNotFound
}
return dbus.MakeVariant(reflect.ValueOf(prop.Value).Elem().Interface()), nil
}
// GetAll implements org.freedesktop.DBus.Properties.GetAll.
func (p *Properties) GetAll(iface string) (map[string]dbus.Variant, *dbus.Error) {
p.mut.RLock()
defer p.mut.RUnlock()
m, ok := p.m[iface]
if !ok {
return nil, ErrIfaceNotFound
}
rm := make(map[string]dbus.Variant, len(m))
for k, v := range m {
rm[k] = dbus.MakeVariant(reflect.ValueOf(v.Value).Elem().Interface())
}
return rm, nil
}
// GetMust returns the value of the given property and panics if either the
// interface or the property name are invalid.
func (p *Properties) GetMust(iface, property string) interface{} {
p.mut.RLock()
defer p.mut.RUnlock()
return reflect.ValueOf(p.m[iface][property].Value).Elem().Interface()
}
// Introspection returns the introspection data that represents the properties
// of iface.
func (p *Properties) Introspection(iface string) []introspect.Property {
p.mut.RLock()
defer p.mut.RUnlock()
m := p.m[iface]
s := make([]introspect.Property, 0, len(m))
for name, prop := range m {
s = append(s, prop.Introspection(name))
}
return s
}
// set sets the given property and emits PropertyChanged if appropriate. p.mut
// must already be locked.
func (p *Properties) set(iface, property string, v interface{}) error {
prop := p.m[iface][property]
err := dbus.Store([]interface{}{v}, prop.Value)
if err != nil {
return err
}
return p.emitChange(iface, property)
}
func (p *Properties) emitChange(iface, property string) error {
prop := p.m[iface][property]
switch prop.Emit {
case EmitFalse:
return nil // do nothing
case EmitInvalidates:
return p.conn.Emit(p.path, "org.freedesktop.DBus.Properties.PropertiesChanged",
iface, map[string]dbus.Variant{}, []string{property})
case EmitTrue:
return p.conn.Emit(p.path, "org.freedesktop.DBus.Properties.PropertiesChanged",
iface, map[string]dbus.Variant{property: dbus.MakeVariant(prop.Value)},
[]string{})
case EmitConst:
return nil
default:
panic("invalid value for EmitType")
}
}
// Set implements org.freedesktop.Properties.Set.
func (p *Properties) Set(iface, property string, newv dbus.Variant) *dbus.Error {
p.mut.Lock()
defer p.mut.Unlock()
m, ok := p.m[iface]
if !ok {
return ErrIfaceNotFound
}
prop, ok := m[property]
if !ok {
return ErrPropNotFound
}
if !prop.Writable {
return ErrReadOnly
}
if newv.Signature() != dbus.SignatureOf(prop.Value) {
return ErrInvalidArg
}
if prop.Callback != nil {
err := prop.Callback(&Change{p, iface, property, newv.Value()})
if err != nil {
return err
}
}
if err := p.set(iface, property, newv.Value()); err != nil {
return dbus.MakeFailedError(err)
}
return nil
}
// SetMust sets the value of the given property and panics if the interface or
// the property name are invalid.
func (p *Properties) SetMust(iface, property string, v interface{}) {
p.mut.Lock()
defer p.mut.Unlock() // unlock in case of panic
err := p.set(iface, property, v)
if err != nil {
panic(err)
}
}