internal/pipewire: implement Core::Error

Sample was captured from pw-cli.

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

internal/pipewire/core.go

@@ -167,6 +167,42 @@ func (c *CorePing) MarshalBinary() ([]byte, error) { return Marshal(c) }
 // UnmarshalBinary satisfies [encoding.BinaryUnmarshaler] via [Unmarshal].
 func (c *CorePing) UnmarshalBinary(data []byte) error { return Unmarshal(data, c) }
 
+// The CoreError can be emitted by both the client and the server.
+//
+// When emitted by the server, the error event is sent out when a fatal
+// (non-recoverable) error has occurred. The id argument is the proxy
+// object where the error occurred, most often in response to a request
+// to that object. The message is a brief description of the error, for
+// (debugging) convenience.
+//
+// When emitted by the client, it indicates an error occurred in an
+// object on the client.
+type CoreError struct {
+	// The id of the resource (proxy if emitted by the client) that is in error.
+	ID Int `json:"id"`
+	// A seq number from the failing request (if any).
+	Sequence Int `json:"seq"`
+	// A negative errno style error code.
+	Result Int `json:"res"`
+	// An error message.
+	Message String `json:"message"`
+}
+
+// Size satisfies [KnownSize] with a value computed at runtime.
+func (c *CoreError) Size() Word {
+	return SizePrefix +
+		Size(SizeInt) +
+		Size(SizeInt) +
+		Size(SizeInt) +
+		SizeString[Word](c.Message)
+}
+
+// MarshalBinary satisfies [encoding.BinaryMarshaler] via [Marshal].
+func (c *CoreError) MarshalBinary() ([]byte, error) { return Marshal(c) }
+
+// UnmarshalBinary satisfies [encoding.BinaryUnmarshaler] via [Unmarshal].
+func (c *CoreError) UnmarshalBinary(data []byte) error { return Unmarshal(data, c) }
+
 // The CoreBoundProps event is emitted when a local object ID is bound to a global ID.
 // It is emitted before the global becomes visible in the registry.
 type CoreBoundProps struct {

internal/pipewire/core_test.go

@@ -144,6 +144,52 @@ func TestCorePing(t *testing.T) {
 	}.run(t)
 }
 
+func TestCoreError(t *testing.T) {
+	t.Parallel()
+
+	encodingTestCases[pipewire.CoreError, *pipewire.CoreError]{
+		// captured from pw-cli
+		{"pw-cli", []byte{
+			/* size: rest of data */ 0x58, 0, 0, 0,
+			/* type: Struct */ 0xe, 0, 0, 0,
+
+			/* size: 4 bytes */ 4, 0, 0, 0,
+			/* type: Int */ 4, 0, 0, 0,
+			/* value: 2 */ 2, 0, 0, 0,
+			/* padding */ 0, 0, 0, 0,
+
+			/* size: 4 bytes */ 4, 0, 0, 0,
+			/* type: Int */ 4, 0, 0, 0,
+			/* value: 0x67 */ 0x67, 0, 0, 0,
+			/* padding */ 0, 0, 0, 0,
+
+			/* size: 4 bytes */ 4, 0, 0, 0,
+			/* type: Int */ 4, 0, 0, 0,
+			/* value: -1 */ 0xff, 0xff, 0xff, 0xff,
+			/* padding */ 0, 0, 0, 0,
+
+			/* size: 0x1b bytes */ 0x1b, 0, 0, 0,
+			/*type: String*/ 8, 0, 0, 0,
+
+			// value: "no permission to destroy 0\x00"
+			0x6e, 0x6f, 0x20, 0x70,
+			0x65, 0x72, 0x6d, 0x69,
+			0x73, 0x73, 0x69, 0x6f,
+			0x6e, 0x20, 0x74, 0x6f,
+			0x20, 0x64, 0x65, 0x73,
+			0x74, 0x72, 0x6f, 0x79,
+			0x20, 0x30, 0,
+
+			/* padding */ 0, 0, 0, 0, 0,
+		}, pipewire.CoreError{
+			ID:       2,
+			Sequence: 0x67,
+			Result:   -1,
+			Message:  "no permission to destroy 0",
+		}, nil},
+	}.run(t)
+}
+
 func TestCoreBoundProps(t *testing.T) {
 	t.Parallel()
 

internal/pipewire/header_test.go

@@ -336,6 +336,20 @@ func TestHeader(t *testing.T) {
 			Size:   0x28, Sequence: 44, FileCount: 0,
 		}, nil},
 
+		/* excerpts */
+
+		{"PW_CORE_EVENT_ERROR", []byte{
+			/* Id:     */ 0, 0, 0, 0,
+			/* size:   */ 0x60, 0, 0,
+			/* opcode: */ 3,
+			/* seq:    */ 0xf5, 0, 0, 0,
+			/* n_fds:  */ 0, 0, 0, 0,
+		}, pipewire.Header{
+			ID:     pipewire.PW_ID_CORE,
+			Opcode: pipewire.PW_CORE_EVENT_ERROR,
+			Size:   0x60, Sequence: 0xf5, FileCount: 0,
+		}, nil},
+
 		/* handmade samples */
 
 		{"PW_CORE_EVENT_PING", []byte{
@@ -350,18 +364,6 @@ func TestHeader(t *testing.T) {
 			Size:   0xbed, Sequence: 0xffff, FileCount: 0xcafe,
 		}, nil},
 
-		{"PW_CORE_EVENT_ERROR", []byte{
-			/* Id:     */ 0, 0, 0, 0,
-			/* size:   */ 0xad, 0xb, 0,
-			/* opcode: */ 3,
-			/* seq:    */ 0xfe, 0xfe, 0, 0,
-			/* n_fds:  */ 0xfe, 0xca, 0, 0,
-		}, pipewire.Header{
-			ID:     pipewire.PW_ID_CORE,
-			Opcode: pipewire.PW_CORE_EVENT_ERROR,
-			Size:   0xbad, Sequence: 0xfefe, FileCount: 0xcafe,
-		}, nil},
-
 		{"PW_CORE_METHOD_PONG", []byte{
 			/* Id:     */ 0, 0, 0, 0,
 			/* size:   */ 0xed, 0xb, 0,