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package main
import (
"encoding/binary"
"fmt"
"math"
"strings"
)
// POD Type constants from pipewire-pod.txt
const (
TypeNone uint32 = 1
TypeBool uint32 = 2
TypeId uint32 = 3
TypeInt uint32 = 4
TypeLong uint32 = 5
TypeFloat uint32 = 6
TypeDouble uint32 = 7
TypeString uint32 = 8
TypeBytes uint32 = 9
TypeRectangle uint32 = 10
TypeFraction uint32 = 11
TypeBitmap uint32 = 12
TypeArray uint32 = 13
TypeStruct uint32 = 14
TypeObject uint32 = 15
TypeSequence uint32 = 16
TypePointer uint32 = 17
TypeFd uint32 = 18
TypeChoice uint32 = 19
TypePod uint32 = 20
)
// POD represents a PipeWire POD (Plain Old Data)
// Layout: [size:uint32][type:uint32][payload...][padding to 8 bytes]
type POD struct {
Size uint32 // Size of payload (not including size/type header)
Type uint32 // POD type
Data []byte // Raw payload data (already padded to 8 bytes)
}
// roundUp8 rounds up to nearest multiple of 8
func roundUp8(n int) int {
return (n + 7) &^ 7
}
// EncodePOD encodes a POD to bytes
func (p *POD) Encode() []byte {
totalSize := 8 + len(p.Data) // header (8 bytes) + data
buf := make([]byte, totalSize)
binary.LittleEndian.PutUint32(buf[0:4], p.Size)
binary.LittleEndian.PutUint32(buf[4:8], p.Type)
copy(buf[8:], p.Data)
return buf
}
// DecodePOD decodes a POD from bytes, returns the POD and number of bytes consumed
func DecodePOD(data []byte) (*POD, int, error) {
if len(data) < 8 {
return nil, 0, fmt.Errorf("insufficient data for POD header: need 8, got %d", len(data))
}
size := binary.LittleEndian.Uint32(data[0:4])
podType := binary.LittleEndian.Uint32(data[4:8])
// Total size is 8 (header) + rounded up payload
paddedSize := roundUp8(int(size))
totalSize := 8 + paddedSize
if len(data) < totalSize {
return nil, 0, fmt.Errorf("insufficient data for POD payload: need %d, got %d", totalSize, len(data))
}
pod := &POD{
Size: size,
Type: podType,
Data: make([]byte, paddedSize),
}
copy(pod.Data, data[8:totalSize])
return pod, totalSize, nil
}
// Helper constructors for basic POD types
// NewNone creates a None POD
func NewNone() *POD {
return &POD{Size: 0, Type: TypeNone, Data: nil}
}
// NewBool creates a Bool POD
func NewBool(value bool) *POD {
data := make([]byte, 8)
if value {
binary.LittleEndian.PutUint32(data[0:4], 1)
}
return &POD{Size: 4, Type: TypeBool, Data: data}
}
// NewInt creates an Int POD
func NewInt(value int32) *POD {
data := make([]byte, 8)
binary.LittleEndian.PutUint32(data[0:4], uint32(value))
return &POD{Size: 4, Type: TypeInt, Data: data}
}
// NewId creates an Id POD
func NewId(value uint32) *POD {
data := make([]byte, 8)
binary.LittleEndian.PutUint32(data[0:4], value)
return &POD{Size: 4, Type: TypeId, Data: data}
}
// NewLong creates a Long POD
func NewLong(value int64) *POD {
data := make([]byte, 8)
binary.LittleEndian.PutUint64(data[0:8], uint64(value))
return &POD{Size: 8, Type: TypeLong, Data: data}
}
// NewFloat creates a Float POD
func NewFloat(value float32) *POD {
data := make([]byte, 8)
binary.LittleEndian.PutUint32(data[0:4], math.Float32bits(value))
return &POD{Size: 4, Type: TypeFloat, Data: data}
}
// NewDouble creates a Double POD
func NewDouble(value float64) *POD {
data := make([]byte, 8)
binary.LittleEndian.PutUint64(data[0:8], math.Float64bits(value))
return &POD{Size: 8, Type: TypeDouble, Data: data}
}
// NewString creates a String POD (null-terminated, padded to 8 bytes)
func NewString(value string) *POD {
strBytes := []byte(value)
size := len(strBytes) + 1 // include null terminator
paddedSize := roundUp8(size)
data := make([]byte, paddedSize)
copy(data, strBytes)
// data is already zero-initialized, so null terminator is implicit
return &POD{Size: uint32(size), Type: TypeString, Data: data}
}
// NewStruct creates a Struct POD from a list of child PODs
func NewStruct(children ...*POD) *POD {
// Calculate total size
var totalSize int
for _, child := range children {
totalSize += 8 + len(child.Data) // each child is header + data
}
data := make([]byte, roundUp8(totalSize))
offset := 0
for _, child := range children {
childBytes := child.Encode()
copy(data[offset:], childBytes)
offset += len(childBytes)
}
return &POD{Size: uint32(totalSize), Type: TypeStruct, Data: data}
}
// GetInt extracts an int32 from an Int POD
func (p *POD) GetInt() (int32, error) {
if p.Type != TypeInt {
return 0, fmt.Errorf("POD type is %d, expected Int (%d)", p.Type, TypeInt)
}
if len(p.Data) < 4 {
return 0, fmt.Errorf("insufficient data for Int")
}
return int32(binary.LittleEndian.Uint32(p.Data[0:4])), nil
}
// GetLong extracts an int64 from a Long POD
func (p *POD) GetLong() (int64, error) {
if p.Type != TypeLong {
return 0, fmt.Errorf("POD type is %d, expected Long (%d)", p.Type, TypeLong)
}
if len(p.Data) < 8 {
return 0, fmt.Errorf("insufficient data for Long")
}
return int64(binary.LittleEndian.Uint64(p.Data[0:8])), nil
}
// GetString extracts a string from a String POD
func (p *POD) GetString() (string, error) {
if p.Type != TypeString {
return "", fmt.Errorf("POD type is %d, expected String (%d)", p.Type, TypeString)
}
// Find null terminator
for i := 0; i < len(p.Data) && i < int(p.Size); i++ {
if p.Data[i] == 0 {
return string(p.Data[0:i]), nil
}
}
// No null terminator found within size
if int(p.Size) <= len(p.Data) {
return string(p.Data[0:p.Size]), nil
}
return string(p.Data), nil
}
// GetStructChildren extracts child PODs from a Struct
func (p *POD) GetStructChildren() ([]*POD, error) {
if p.Type != TypeStruct {
return nil, fmt.Errorf("POD type is %d, expected Struct (%d)", p.Type, TypeStruct)
}
var children []*POD
offset := 0
dataLen := int(p.Size)
for offset < dataLen {
child, consumed, err := DecodePOD(p.Data[offset:dataLen])
if err != nil {
return nil, fmt.Errorf("failed to decode child POD at offset %d: %w", offset, err)
}
children = append(children, child)
offset += consumed
}
return children, nil
}
// ParseStruct is a helper to parse a struct into expected types
// It decodes children and returns them as a slice
func ParseStruct(p *POD) ([]*POD, error) {
return p.GetStructChildren()
}
// PrettyPrint returns a human-readable string representation of a POD
func (p *POD) PrettyPrint(indent int) string {
prefix := ""
for range indent {
prefix += " "
}
switch p.Type {
case TypeNone:
return prefix + "None"
case TypeBool:
if len(p.Data) >= 4 {
val := binary.LittleEndian.Uint32(p.Data[0:4])
return prefix + fmt.Sprintf("Bool(%v)", val != 0)
}
return prefix + "Bool(error: insufficient data)"
case TypeId:
if len(p.Data) >= 4 {
val := binary.LittleEndian.Uint32(p.Data[0:4])
return prefix + fmt.Sprintf("Id(%d)", val)
}
return prefix + "Id(error: insufficient data)"
case TypeInt:
val, err := p.GetInt()
if err != nil {
return prefix + fmt.Sprintf("Int(error: %v)", err)
}
return prefix + fmt.Sprintf("Int(%d)", val)
case TypeLong:
val, err := p.GetLong()
if err != nil {
return prefix + fmt.Sprintf("Long(error: %v)", err)
}
return prefix + fmt.Sprintf("Long(%d)", val)
case TypeFloat:
if len(p.Data) >= 4 {
val := math.Float32frombits(binary.LittleEndian.Uint32(p.Data[0:4]))
return prefix + fmt.Sprintf("Float(%f)", val)
}
return prefix + "Float(error: insufficient data)"
case TypeDouble:
if len(p.Data) >= 8 {
val := math.Float64frombits(binary.LittleEndian.Uint64(p.Data[0:8]))
return prefix + fmt.Sprintf("Double(%f)", val)
}
return prefix + "Double(error: insufficient data)"
case TypeString:
val, err := p.GetString()
if err != nil {
return prefix + fmt.Sprintf("String(error: %v)", err)
}
return prefix + fmt.Sprintf("String(%q)", val)
case TypeStruct:
children, err := p.GetStructChildren()
if err != nil {
return prefix + fmt.Sprintf("Struct(error: %v)", err)
}
var result strings.Builder
result.WriteString(prefix + fmt.Sprintf("Struct(%d children) [\n", len(children)))
for i, child := range children {
result.WriteString(prefix + fmt.Sprintf(" [%d]: %s\n", i, child.PrettyPrint(indent + 2)[len(prefix)+2:]))
}
result.WriteString(prefix + "]")
return result.String()
case TypeObject:
// Object format: [object_type:uint32][object_id:uint32][properties...]
// Each property: [key:uint32][flags:uint32][POD value]
if len(p.Data) < 8 {
return prefix + "Object(error: insufficient data)"
}
objectType := binary.LittleEndian.Uint32(p.Data[0:4])
objectID := binary.LittleEndian.Uint32(p.Data[4:8])
var result strings.Builder
result.WriteString(prefix + fmt.Sprintf("Object(type=%d, id=%d) [\n", objectType, objectID))
// Parse properties
offset := 8 // Skip object_type and object_id (8 bytes total)
propIndex := 0
for offset < len(p.Data) {
// Each property starts with key (4 bytes) and flags (4 bytes)
if len(p.Data)-offset < 8 {
break
}
key := binary.LittleEndian.Uint32(p.Data[offset : offset+4])
flags := binary.LittleEndian.Uint32(p.Data[offset+4 : offset+8])
offset += 8
// Now parse the POD value
if offset >= len(p.Data) {
result.WriteString(prefix + fmt.Sprintf(" [%d]: key=%d, flags=0x%x (no value)\n", propIndex, key, flags))
break
}
propPod, bytesRead, err := DecodePOD(p.Data[offset:])
if err != nil {
result.WriteString(prefix + fmt.Sprintf(" [%d]: key=%d, flags=0x%x (error: %v)\n", propIndex, key, flags, err))
break
}
result.WriteString(prefix + fmt.Sprintf(" [%d]: key=%d, flags=0x%x => %s\n",
propIndex, key, flags, propPod.PrettyPrint(indent + 2)[len(prefix)+2:]))
offset += bytesRead
propIndex++
}
result.WriteString(prefix + "]")
return result.String()
case TypeArray:
return prefix + fmt.Sprintf("Array(size=%d)", p.Size)
case TypeBytes:
return prefix + fmt.Sprintf("Bytes(size=%d)", p.Size)
case TypeChoice:
return prefix + fmt.Sprintf("Choice(size=%d)", p.Size)
default:
return prefix + fmt.Sprintf("Unknown(type=%d, size=%d)", p.Type, p.Size)
}
}
|