internal/pipewire: add type constants

This change also centralises encoding testing.

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

internal/pipewire/header.go

@@ -22,16 +22,16 @@ var (
 // A Header is the fixed-size message header described in protocol native.
 type Header struct {
 	// The message id this is the destination resource/proxy id.
-	ID uint32 `json:"Id"`
+	ID Uint `json:"Id"`
 	// The opcode on the resource/proxy interface.
 	Opcode byte `json:"opcode"`
 	// The size of the payload and optional footer of the message.
 	// Note: this value is only 24 bits long in the format.
 	Size uint32 `json:"size"`
 	// An increasing sequence number for each message.
-	Sequence uint32 `json:"seq"`
+	Sequence Uint `json:"seq"`
 	// Number of file descriptors in this message.
-	FileCount uint32 `json:"n_fds"`
+	FileCount Uint `json:"n_fds"`
 }
 
 // append appends the protocol native message header to data.
@@ -39,7 +39,7 @@ type Header struct {
 // Callers must perform bounds check on [Header.Size].
 func (h *Header) append(data []byte) []byte {
 	data = binary.NativeEndian.AppendUint32(data, h.ID)
-	data = binary.NativeEndian.AppendUint32(data, uint32(h.Opcode)<<24|h.Size)
+	data = binary.NativeEndian.AppendUint32(data, Word(h.Opcode)<<24|h.Size)
 	data = binary.NativeEndian.AppendUint32(data, h.Sequence)
 	data = binary.NativeEndian.AppendUint32(data, h.FileCount)
 	return data

internal/pipewire/header_test.go

@@ -10,11 +10,21 @@ import (
 func TestHeader(t *testing.T) {
 	t.Parallel()
 
-	testCases := []struct {
-		name string
-		data []byte
-		want pipewire.Header
-	}{
+	encodingTestCases[pipewire.Header, *pipewire.Header]{
+		{"PW_CORE_METHOD_HELLO", []byte{
+			// Id
+			0, 0, 0, 0,
+			// size
+			0x18, 0, 0,
+			// opcode
+			1,
+			// seq
+			0, 0, 0, 0,
+			// n_fds
+			0, 0, 0, 0,
+		}, pipewire.Header{ID: pipewire.PW_ID_CORE, Opcode: pipewire.PW_CORE_METHOD_HELLO,
+			Size: 0x18, Sequence: 0, FileCount: 0}, nil},
+
 		{"PW_SECURITY_CONTEXT_METHOD_CREATE", []byte{
 			// Id
 			3, 0, 0, 0,
@@ -27,7 +37,7 @@ func TestHeader(t *testing.T) {
 			// n_fds
 			2, 0, 0, 0,
 		}, pipewire.Header{ID: 3, Opcode: pipewire.PW_SECURITY_CONTEXT_METHOD_CREATE,
-			Size: 0xd8, Sequence: 5, FileCount: 2}},
+			Size: 0xd8, Sequence: 5, FileCount: 2}, nil},
 
 		{"PW_SECURITY_CONTEXT_METHOD_NUM", []byte{
 			// Id
@@ -41,35 +51,8 @@ func TestHeader(t *testing.T) {
 			// n_fds
 			0, 0, 0, 0,
 		}, pipewire.Header{ID: 0, Opcode: pipewire.PW_SECURITY_CONTEXT_METHOD_NUM,
-			Size: 0x28, Sequence: 6, FileCount: 0}},
-	}
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			t.Run("decode", func(t *testing.T) {
-				t.Parallel()
-
-				var got pipewire.Header
-				if err := got.UnmarshalBinary(tc.data); err != nil {
-					t.Fatalf("UnmarshalBinary: error = %v", err)
-				}
-				if got != tc.want {
-					t.Fatalf("UnmarshalBinary: %#v, want %#v", got, tc.want)
-				}
-			})
-
-			t.Run("encode", func(t *testing.T) {
-				t.Parallel()
-
-				if got, err := tc.want.MarshalBinary(); err != nil {
-					t.Fatalf("MarshalBinary: error = %v", err)
-				} else if string(got) != string(tc.data) {
-					t.Fatalf("MarshalBinary: %#v, want %#v", got, tc.data)
-				}
-			})
-		})
-	}
+			Size: 0x28, Sequence: 6, FileCount: 0}, nil},
+	}.run(t)
 
 	t.Run("size range", func(t *testing.T) {
 		t.Parallel()

internal/pipewire/pipewire.go

@@ -304,7 +304,7 @@ const (
 	PW_PERM_RWXML = PW_PERM_RWXM | PW_PERM_L
 
 	PW_PERM_ALL          = PW_PERM_RWXM
-	PW_PERM_INVALID uint32 = 0xffffffff
+	PW_PERM_INVALID Word = 0xffffffff
 )
 
 /* pipewire/port.h */

internal/pipewire/pod.go

@@ -0,0 +1,133 @@
+package pipewire
+
+type (
+	// A Word is a 32-bit unsigned integer.
+	//
+	// Values internal to a message appear to always be aligned to 32-bit boundary.
+	Word = uint32
+
+	// An Int is a signed integer the size of a PipeWire Word.
+	Int = int32
+	// An Uint is an unsigned integer the size of a PipeWire Word.
+	Uint = Word
+)
+
+/* Basic types */
+const (
+	/* POD's can contain a number of basic SPA types: */
+
+	SPA_TYPE_START     = 0x00000 + iota
+	SPA_TYPE_None      // No value or a NULL pointer.
+	SPA_TYPE_Bool      // A boolean value.
+	SPA_TYPE_Id        // An enumerated value.
+	SPA_TYPE_Int       // An integer value, 32-bit.
+	SPA_TYPE_Long      // An integer value, 64-bit.
+	SPA_TYPE_Float     // A floating point value, 32-bit.
+	SPA_TYPE_Double    // A floating point value, 64-bit.
+	SPA_TYPE_String    // A string.
+	SPA_TYPE_Bytes     // A byte array.
+	SPA_TYPE_Rectangle // A rectangle with width and height.
+	SPA_TYPE_Fraction  // A fraction with numerator and denominator.
+	SPA_TYPE_Bitmap    // An array of bits.
+
+	/* POD's can be grouped together in these container types: */
+
+	SPA_TYPE_Array    // An array of equal sized objects.
+	SPA_TYPE_Struct   // A collection of types and objects.
+	SPA_TYPE_Object   // An object with properties.
+	SPA_TYPE_Sequence // A timed sequence of POD's.
+
+	/* POD's can also contain some extra types: */
+
+	SPA_TYPE_Pointer // A typed pointer in memory.
+	SPA_TYPE_Fd      // A file descriptor.
+	SPA_TYPE_Choice  // A choice of values.
+	SPA_TYPE_Pod     // A generic type for the POD itself.
+
+	_SPA_TYPE_LAST // not part of ABI
+)
+
+/* Pointers */
+const (
+	SPA_TYPE_POINTER_START = 0x10000 + iota
+	SPA_TYPE_POINTER_Buffer
+	SPA_TYPE_POINTER_Meta
+	SPA_TYPE_POINTER_Dict
+
+	_SPA_TYPE_POINTER_LAST // not part of ABI
+)
+
+/* Events */
+const (
+	SPA_TYPE_EVENT_START = 0x20000 + iota
+	SPA_TYPE_EVENT_Device
+	SPA_TYPE_EVENT_Node
+
+	_SPA_TYPE_EVENT_LAST // not part of ABI
+)
+
+/* Commands */
+const (
+	SPA_TYPE_COMMAND_START = 0x30000 + iota
+	SPA_TYPE_COMMAND_Device
+	SPA_TYPE_COMMAND_Node
+
+	_SPA_TYPE_COMMAND_LAST // not part of ABI
+)
+
+/* Objects */
+const (
+	SPA_TYPE_OBJECT_START = 0x40000 + iota
+	SPA_TYPE_OBJECT_PropInfo
+	SPA_TYPE_OBJECT_Props
+	SPA_TYPE_OBJECT_Format
+	SPA_TYPE_OBJECT_ParamBuffers
+	SPA_TYPE_OBJECT_ParamMeta
+	SPA_TYPE_OBJECT_ParamIO
+	SPA_TYPE_OBJECT_ParamProfile
+	SPA_TYPE_OBJECT_ParamPortConfig
+	SPA_TYPE_OBJECT_ParamRoute
+	SPA_TYPE_OBJECT_Profiler
+	SPA_TYPE_OBJECT_ParamLatency
+	SPA_TYPE_OBJECT_ParamProcessLatency
+	SPA_TYPE_OBJECT_ParamTag
+	_SPA_TYPE_OBJECT_LAST // not part of ABI
+)
+
+/* vendor extensions */
+const (
+	SPA_TYPE_VENDOR_PipeWire = 0x02000000
+
+	SPA_TYPE_VENDOR_Other = 0x7f000000
+)
+
+const (
+	SPA_TYPE_INFO_BASE = "Spa:"
+
+	SPA_TYPE_INFO_Flags      = SPA_TYPE_INFO_BASE + "Flags"
+	SPA_TYPE_INFO_FLAGS_BASE = SPA_TYPE_INFO_Flags + ":"
+
+	SPA_TYPE_INFO_Enum      = SPA_TYPE_INFO_BASE + "Enum"
+	SPA_TYPE_INFO_ENUM_BASE = SPA_TYPE_INFO_Enum + ":"
+
+	SPA_TYPE_INFO_Pod      = SPA_TYPE_INFO_BASE + "Pod"
+	SPA_TYPE_INFO_POD_BASE = SPA_TYPE_INFO_Pod + ":"
+
+	SPA_TYPE_INFO_Struct      = SPA_TYPE_INFO_POD_BASE + "Struct"
+	SPA_TYPE_INFO_STRUCT_BASE = SPA_TYPE_INFO_Struct + ":"
+
+	SPA_TYPE_INFO_Object      = SPA_TYPE_INFO_POD_BASE + "Object"
+	SPA_TYPE_INFO_OBJECT_BASE = SPA_TYPE_INFO_Object + ":"
+
+	SPA_TYPE_INFO_Pointer      = SPA_TYPE_INFO_BASE + "Pointer"
+	SPA_TYPE_INFO_POINTER_BASE = SPA_TYPE_INFO_Pointer + ":"
+
+	SPA_TYPE_INFO_Interface      = SPA_TYPE_INFO_POINTER_BASE + "Interface"
+	SPA_TYPE_INFO_INTERFACE_BASE = SPA_TYPE_INFO_Interface + ":"
+
+	SPA_TYPE_INFO_Event      = SPA_TYPE_INFO_OBJECT_BASE + "Event"
+	SPA_TYPE_INFO_EVENT_BASE = SPA_TYPE_INFO_Event + ":"
+
+	SPA_TYPE_INFO_Command      = SPA_TYPE_INFO_OBJECT_BASE + "Command"
+	SPA_TYPE_INFO_COMMAND_BASE = SPA_TYPE_INFO_Command + ":"
+)

internal/pipewire/pod_test.go

@@ -0,0 +1,55 @@
+package pipewire_test
+
+import (
+	"encoding"
+	"reflect"
+	"testing"
+)
+
+type encodingTestCases[V any, S interface {
+	encoding.BinaryMarshaler
+	encoding.BinaryUnmarshaler
+	*V
+}] []struct {
+	// Uninterpreted name of subtest.
+	name string
+	// Encoded data.
+	wantData []byte
+	// Value corresponding to wantData.
+	value V
+	// Expected decoding error. Skips encoding check if non-nil.
+	wantErr error
+}
+
+// run runs all test cases as subtests of [testing.T].
+func (testCases encodingTestCases[V, S]) run(t *testing.T) {
+	t.Helper()
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			t.Run("decode", func(t *testing.T) {
+				t.Parallel()
+
+				var value V
+				if err := S(&value).UnmarshalBinary(tc.wantData); err != nil {
+					t.Fatalf("UnmarshalBinary: error = %v", err)
+				}
+				if !reflect.DeepEqual(&value, &tc.value) {
+					t.Fatalf("UnmarshalBinary: %#v, want %#v", value, tc.value)
+				}
+			})
+
+			t.Run("encode", func(t *testing.T) {
+				t.Parallel()
+
+				if gotData, err := S(&tc.value).MarshalBinary(); err != nil {
+					t.Fatalf("MarshalBinary: error = %v", err)
+				} else if string(gotData) != string(tc.wantData) {
+					t.Fatalf("MarshalBinary: %#v, want %#v", gotData, tc.wantData)
+				}
+			})
+		})
+	}
+}