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byte_input.go
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/
byte_input.go
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package internal
import (
"encoding/binary"
"io"
)
// ByteInput typed interface around io.Reader or raw bytes
type ByteInput interface {
// Next returns a slice containing the next n bytes from the buffer,
// advancing the buffer as if the bytes had been returned by Read.
Next(n int) ([]byte, error)
// NextReturnsSafeSlice returns true if Next() returns a safe slice as opposed
// to a slice that points to an underlying buffer possibly owned by another system.
// When NextReturnsSafeSlice returns false, the result from Next() should be copied
// before it is modified (i.e., it is immutable).
NextReturnsSafeSlice() bool
// ReadUInt32 reads uint32 with LittleEndian order
ReadUInt32() (uint32, error)
// ReadUInt16 reads uint16 with LittleEndian order
ReadUInt16() (uint16, error)
// GetReadBytes returns read bytes
GetReadBytes() int64
// SkipBytes skips exactly n bytes
SkipBytes(n int) error
}
// NewByteInputFromReader creates reader wrapper
func NewByteInputFromReader(reader io.Reader) ByteInput {
return &ByteInputAdapter{
r: reader,
readBytes: 0,
}
}
// NewByteInput creates raw bytes wrapper
func NewByteInput(buf []byte) ByteInput {
return &ByteBuffer{
buf: buf,
off: 0,
}
}
// ByteBuffer raw bytes wrapper
type ByteBuffer struct {
buf []byte
off int
}
// NewByteBuffer creates a new ByteBuffer.
func NewByteBuffer(buf []byte) *ByteBuffer {
return &ByteBuffer{
buf: buf,
}
}
var _ io.Reader = (*ByteBuffer)(nil)
// Read implements io.Reader.
func (b *ByteBuffer) Read(p []byte) (int, error) {
data, err := b.Next(len(p))
if err != nil {
return 0, err
}
copy(p, data)
return len(data), nil
}
// Next returns a slice containing the next n bytes from the reader
// If there are fewer bytes than the given n, io.ErrUnexpectedEOF will be returned
func (b *ByteBuffer) Next(n int) ([]byte, error) {
m := len(b.buf) - b.off
if n > m {
return nil, io.ErrUnexpectedEOF
}
data := b.buf[b.off : b.off+n]
b.off += n
return data, nil
}
// NextReturnsSafeSlice returns false since ByteBuffer might hold
// an array owned by some other systems.
func (b *ByteBuffer) NextReturnsSafeSlice() bool {
return false
}
// ReadUInt32 reads uint32 with LittleEndian order
func (b *ByteBuffer) ReadUInt32() (uint32, error) {
if len(b.buf)-b.off < 4 {
return 0, io.ErrUnexpectedEOF
}
v := binary.LittleEndian.Uint32(b.buf[b.off:])
b.off += 4
return v, nil
}
// ReadUInt16 reads uint16 with LittleEndian order
func (b *ByteBuffer) ReadUInt16() (uint16, error) {
if len(b.buf)-b.off < 2 {
return 0, io.ErrUnexpectedEOF
}
v := binary.LittleEndian.Uint16(b.buf[b.off:])
b.off += 2
return v, nil
}
// GetReadBytes returns read bytes
func (b *ByteBuffer) GetReadBytes() int64 {
return int64(b.off)
}
// SkipBytes skips exactly n bytes
func (b *ByteBuffer) SkipBytes(n int) error {
m := len(b.buf) - b.off
if n > m {
return io.ErrUnexpectedEOF
}
b.off += n
return nil
}
// Reset resets the given buffer with a new byte slice
func (b *ByteBuffer) Reset(buf []byte) {
b.buf = buf
b.off = 0
}
// ByteInputAdapter reader wrapper
type ByteInputAdapter struct {
r io.Reader
readBytes int
buf [4]byte
}
var _ io.Reader = (*ByteInputAdapter)(nil)
// Read implements io.Reader.
func (b *ByteInputAdapter) Read(buf []byte) (int, error) {
m, err := io.ReadAtLeast(b.r, buf, len(buf))
b.readBytes += m
if err != nil {
return 0, err
}
return m, nil
}
// Next returns a slice containing the next n bytes from the buffer,
// advancing the buffer as if the bytes had been returned by Read.
func (b *ByteInputAdapter) Next(n int) ([]byte, error) {
buf := make([]byte, n)
_, err := b.Read(buf)
if err != nil {
return nil, err
}
return buf, nil
}
// NextReturnsSafeSlice returns true since ByteInputAdapter always returns a slice
// allocated with make([]byte, ...)
func (b *ByteInputAdapter) NextReturnsSafeSlice() bool {
return true
}
// ReadUInt32 reads uint32 with LittleEndian order
func (b *ByteInputAdapter) ReadUInt32() (uint32, error) {
buf := b.buf[:4]
_, err := b.Read(buf)
if err != nil {
return 0, err
}
return binary.LittleEndian.Uint32(buf), nil
}
// ReadUInt16 reads uint16 with LittleEndian order
func (b *ByteInputAdapter) ReadUInt16() (uint16, error) {
buf := b.buf[:2]
_, err := b.Read(buf)
if err != nil {
return 0, err
}
return binary.LittleEndian.Uint16(buf), nil
}
// GetReadBytes returns read bytes
func (b *ByteInputAdapter) GetReadBytes() int64 {
return int64(b.readBytes)
}
// SkipBytes skips exactly n bytes
func (b *ByteInputAdapter) SkipBytes(n int) error {
_, err := b.Next(n)
return err
}
// Reset resets the given buffer with a new stream
func (b *ByteInputAdapter) Reset(stream io.Reader) {
b.r = stream
b.readBytes = 0
}