internal/pipewire: implement Core::CreateObject

Nothing uses this right now, this would have to be called by wrapper methods on Registry that would search the objects

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pipewire/core.go

@@ -572,6 +572,58 @@ func (ctx *Context) GetRegistry() (*Registry, error) {
 	)
 }
 
+// CoreCreateObject is sent when the client requests to create a
+// new object from a factory of a certain type.
+//
+// The client allocates a new_id for the proxy. The server will
+// allocate a new resource with the same new_id and from then on,
+// Methods and Events will be exchanged between the new object of
+// the given type.
+type CoreCreateObject struct {
+	// The name of a server factory object to use.
+	FactoryName String `json:"factory_name"`
+	// The type of the object to create, this is also the type of
+	// the interface of the new_id proxy.
+	Type String `json:"type"`
+	// Undocumented, assumed to be the local version of the proxy.
+	Version Int `json:"version"`
+	// Extra properties to create the object.
+	Properties *SPADict `json:"props"`
+	// The proxy id of the new object.
+	NewID Int `json:"new_id"`
+}
+
+// Opcode satisfies [Message] with a constant value.
+func (c *CoreCreateObject) Opcode() byte { return PW_CORE_METHOD_CREATE_OBJECT }
+
+// FileCount satisfies [Message] with a constant value.
+func (c *CoreCreateObject) FileCount() Int { return 0 }
+
+// Size satisfies [KnownSize] with a value computed at runtime.
+func (c *CoreCreateObject) Size() Word {
+	return SizePrefix +
+		SizeString[Word](c.FactoryName) +
+		SizeString[Word](c.Type) +
+		Size(SizeInt) +
+		c.Properties.Size() +
+		Size(SizeInt)
+}
+
+// MarshalBinary satisfies [encoding.BinaryMarshaler] via [Marshal].
+func (c *CoreCreateObject) MarshalBinary() ([]byte, error) { return Marshal(c) }
+
+// UnmarshalBinary satisfies [encoding.BinaryUnmarshaler] via [Unmarshal].
+func (c *CoreCreateObject) UnmarshalBinary(data []byte) error { return Unmarshal(data, c) }
+
+// createObject queues a [CoreCreateObject] message for the PipeWire server.
+// This is not safe to use directly, callers should use typed wrapper methods on [Registry] instead.
+func (core *Core) createObject(factoryName, typeName String, version Int, props SPADict, newId Int) error {
+	return core.ctx.writeMessage(
+		PW_ID_CORE,
+		&CoreCreateObject{factoryName, typeName, version, &props, newId},
+	)
+}
+
 // A RegistryGlobal event is emitted to notify a client about a new global object.
 type RegistryGlobal struct {
 	// The global id.

internal/pipewire/core_test.go

@@ -171,7 +171,7 @@ func TestCoreError(t *testing.T) {
 			/* padding */ 0, 0, 0, 0,
 
 			/* size: 0x1b bytes */ 0x1b, 0, 0, 0,
-			/*type: String */ 8, 0, 0, 0,
+			/* type: String */ 8, 0, 0, 0,
 
 			// value: "no permission to destroy 0\x00"
 			0x6e, 0x6f, 0x20, 0x70,
@@ -306,6 +306,60 @@ func TestCoreGetRegistry(t *testing.T) {
 	}.run(t)
 }
 
+func TestCoreCreateObject(t *testing.T) {
+	t.Parallel()
+
+	encodingTestCases[pipewire.CoreCreateObject, *pipewire.CoreCreateObject]{
+		{"sample", []byte{
+			/* size: rest of data */ 0x70, 0, 0, 0,
+			/* type: Struct */ 0xe, 0, 0, 0,
+
+			/* size: 0x13 bytes */ 0x13, 0, 0, 0,
+			/* type: String */ 8, 0, 0, 0,
+
+			// value: "spa-device-factory\x00"
+			0x73, 0x70, 0x61, 0x2d,
+			0x64, 0x65, 0x76, 0x69,
+			0x63, 0x65, 0x2d, 0x66,
+			0x61, 0x63, 0x74, 0x6f,
+			0x72, 0x79, 0, 0,
+			0, 0, 0, 0,
+
+			/* size: 0x1a bytes */ 0x1a, 0, 0, 0,
+			/* type: String */ 8, 0, 0, 0,
+
+			// value: "PipeWire:Interface:Device\x00"
+			0x50, 0x69, 0x70, 0x65,
+			0x57, 0x69, 0x72, 0x65,
+			0x3a, 0x49, 0x6e, 0x74,
+			0x65, 0x72, 0x66, 0x61,
+			0x63, 0x65, 0x3a, 0x44,
+			0x65, 0x76, 0x69, 0x63,
+			0x65, 0, 0, 0,
+			0, 0, 0, 0,
+
+			/* size: 4 bytes */ 4, 0, 0, 0,
+			/* type: Int */ 4, 0, 0, 0,
+			/* value: 3 */ 3, 0, 0, 0,
+			/* padding */ 0, 0, 0, 0,
+
+			/* size */ 0, 0, 0, 0,
+			/* type: None */ 1, 0, 0, 0,
+
+			/* size: 4 bytes */ 4, 0, 0, 0,
+			/* type: Int */ 4, 0, 0, 0,
+			/* value: 0xbad */ 0xad, 0xb, 0, 0,
+			/* padding */ 0, 0, 0, 0,
+		}, pipewire.CoreCreateObject{
+			FactoryName: "spa-device-factory",
+			Type:        pipewire.PW_TYPE_INTERFACE_Device,
+			Version:     pipewire.PW_VERSION_FACTORY,
+			Properties:  new(pipewire.SPADict),
+			NewID:       0xbad,
+		}, nil},
+	}.run(t)
+}
+
 func TestRegistryGlobal(t *testing.T) {
 	t.Parallel()