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read.go
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read.go
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package msgp
import (
"io"
"math"
"sync"
"time"
"github.com/philhofer/fwd"
)
// where we keep old *Readers
var readerPool = sync.Pool{New: func() interface{} { return &Reader{} }}
// Type is a MessagePack wire type,
// including this package's built-in
// extension types.
type Type byte
// MessagePack Types
//
// The zero value of Type
// is InvalidType.
const (
InvalidType Type = iota
// MessagePack built-in types
StrType
BinType
MapType
ArrayType
Float64Type
Float32Type
BoolType
IntType
UintType
NilType
ExtensionType
// pseudo-types provided
// by extensions
Complex64Type
Complex128Type
TimeType
_maxtype
)
// String implements fmt.Stringer
func (t Type) String() string {
switch t {
case StrType:
return "str"
case BinType:
return "bin"
case MapType:
return "map"
case ArrayType:
return "array"
case Float64Type:
return "float64"
case Float32Type:
return "float32"
case BoolType:
return "bool"
case UintType:
return "uint"
case IntType:
return "int"
case ExtensionType:
return "ext"
case NilType:
return "nil"
default:
return "<invalid>"
}
}
func freeR(m *Reader) {
readerPool.Put(m)
}
// Unmarshaler is the interface fulfilled
// by objects that know how to unmarshal
// themselves from MessagePack.
// UnmarshalMsg unmarshals the object
// from binary, returing any leftover
// bytes and any errors encountered.
type Unmarshaler interface {
UnmarshalMsg([]byte) ([]byte, error)
}
// Decodable is the interface fulfilled
// by objects that know how to read
// themselves from a *Reader.
type Decodable interface {
DecodeMsg(*Reader) error
}
// Decode decodes 'd' from 'r'.
func Decode(r io.Reader, d Decodable) error {
rd := NewReader(r)
err := d.DecodeMsg(rd)
freeR(rd)
return err
}
// NewReader returns a *Reader that
// reads from the provided reader. The
// reader will be buffered.
func NewReader(r io.Reader) *Reader {
p := readerPool.Get().(*Reader)
if p.R == nil {
p.R = fwd.NewReader(r)
} else {
p.R.Reset(r)
}
return p
}
// NewReaderSize returns a *Reader with a buffer of the given size.
// (This is vastly preferable to passing the decoder a reader that is already buffered.)
func NewReaderSize(r io.Reader, sz int) *Reader {
return &Reader{R: fwd.NewReaderSize(r, sz)}
}
// Reader wraps an io.Reader and provides
// methods to read MessagePack-encoded values
// from it. Readers are buffered.
type Reader struct {
// R is the buffered reader
// that the Reader uses
// to decode MessagePack.
// The Reader itself
// is stateless; all the
// buffering is done
// within R.
R *fwd.Reader
scratch []byte
}
// Read implements `io.Reader`
func (m *Reader) Read(p []byte) (int, error) {
return m.R.Read(p)
}
// ReadFull implements `io.ReadFull`
func (m *Reader) ReadFull(p []byte) (int, error) {
return m.R.ReadFull(p)
}
// Reset resets the underlying reader.
func (m *Reader) Reset(r io.Reader) { m.R.Reset(r) }
// Buffered returns the number of bytes currently in the read buffer.
func (m *Reader) Buffered() int { return m.R.Buffered() }
// BufferSize returns the capacity of the read buffer.
func (m *Reader) BufferSize() int { return m.R.BufferSize() }
// NextType returns the next object type to be decoded.
func (m *Reader) NextType() (Type, error) {
p, err := m.R.Peek(1)
if err != nil {
return InvalidType, err
}
t := getType(p[0])
if t == InvalidType {
return t, InvalidPrefixError(p[0])
}
if t == ExtensionType {
v, err := m.peekExtensionType()
if err != nil {
return InvalidType, err
}
switch v {
case Complex64Extension:
return Complex64Type, nil
case Complex128Extension:
return Complex128Type, nil
case TimeExtension:
return TimeType, nil
}
}
return t, nil
}
// IsNil returns whether or not
// the next byte is a null messagepack byte
func (m *Reader) IsNil() bool {
p, err := m.R.Peek(1)
return err == nil && p[0] == mnil
}
// returns (obj size, obj elements, error)
// only maps and arrays have non-zero obj elements
//
// use uintptr b/c it's guaranteed to be large enough
// to hold whatever we can fit in memory.
func getNextSize(r *fwd.Reader) (uintptr, uintptr, error) {
b, err := r.Peek(1)
if err != nil {
return 0, 0, err
}
lead := b[0]
spec := &sizes[lead]
size, mode := spec.size, spec.extra
if size == 0 {
return 0, 0, InvalidPrefixError(lead)
}
if mode >= 0 {
return uintptr(size), uintptr(mode), nil
}
b, err = r.Peek(int(size))
if err != nil {
return 0, 0, err
}
switch mode {
case extra8:
return uintptr(size) + uintptr(b[1]), 0, nil
case extra16:
return uintptr(size) + uintptr(big.Uint16(b[1:])), 0, nil
case extra32:
return uintptr(size) + uintptr(big.Uint32(b[1:])), 0, nil
case map16v:
return uintptr(size), 2 * uintptr(big.Uint16(b[1:])), nil
case map32v:
return uintptr(size), 2 * uintptr(big.Uint32(b[1:])), nil
case array16v:
return uintptr(size), uintptr(big.Uint16(b[1:])), nil
case array32v:
return uintptr(size), uintptr(big.Uint32(b[1:])), nil
default:
return 0, 0, fatal
}
}
// Skip skips over the next object, regardless of
// its type. If it is an array or map, the whole array
// or map will be skipped.
func (m *Reader) Skip() error {
var (
v uintptr // bytes
o uintptr // objects
err error
p []byte
)
// we can use the faster
// method if we have enough
// buffered data
if m.R.Buffered() >= 5 {
p, err = m.R.Peek(5)
if err != nil {
return err
}
v, o, err = getSize(p)
if err != nil {
return err
}
} else {
v, o, err = getNextSize(m.R)
if err != nil {
return err
}
}
// 'v' is always non-zero
// if err == nil
_, err = m.R.Skip(int(v))
if err != nil {
return err
}
// for maps and slices, skip elements
for x := uintptr(0); x < o; x++ {
err = m.Skip()
if err != nil {
return err
}
}
return nil
}
// ReadMapHeader reads the next object
// as a map header and returns the size
// of the map and the number of bytes written.
// It will return a TypeError{} if the next
// object is not a map.
func (m *Reader) ReadMapHeader() (sz uint32, err error) {
var p []byte
var lead byte
p, err = m.R.Peek(1)
if err != nil {
return
}
lead = p[0]
if isfixmap(lead) {
sz = uint32(rfixmap(lead))
_, err = m.R.Skip(1)
return
}
switch lead {
case mmap16:
p, err = m.R.Next(3)
if err != nil {
return
}
sz = uint32(big.Uint16(p[1:]))
return
case mmap32:
p, err = m.R.Next(5)
if err != nil {
return
}
sz = big.Uint32(p[1:])
return
default:
err = badPrefix(MapType, lead)
return
}
}
// ReadMapKey reads either a 'str' or 'bin' field from
// the reader and returns the value as a []byte. It uses
// scratch for storage if it is large enough.
func (m *Reader) ReadMapKey(scratch []byte) ([]byte, error) {
out, err := m.ReadStringAsBytes(scratch)
if err != nil {
if tperr, ok := err.(TypeError); ok && tperr.Encoded == BinType {
return m.ReadBytes(scratch)
}
return nil, err
}
return out, nil
}
// MapKeyPtr returns a []byte pointing to the contents
// of a valid map key. The key cannot be empty, and it
// must be shorter than the total buffer size of the
// *Reader. Additionally, the returned slice is only
// valid until the next *Reader method call. Users
// should exercise extreme care when using this
// method; writing into the returned slice may
// corrupt future reads.
func (m *Reader) ReadMapKeyPtr() ([]byte, error) {
p, err := m.R.Peek(1)
if err != nil {
return nil, err
}
lead := p[0]
var read int
if isfixstr(lead) {
read = int(rfixstr(lead))
m.R.Skip(1)
goto fill
}
switch lead {
case mstr8, mbin8:
p, err = m.R.Next(2)
if err != nil {
return nil, err
}
read = int(p[1])
case mstr16, mbin16:
p, err = m.R.Next(3)
if err != nil {
return nil, err
}
read = int(big.Uint16(p[1:]))
case mstr32, mbin32:
p, err = m.R.Next(5)
if err != nil {
return nil, err
}
read = int(big.Uint32(p[1:]))
default:
return nil, badPrefix(StrType, lead)
}
fill:
if read == 0 {
return nil, ErrShortBytes
}
return m.R.Next(read)
}
// ReadArrayHeader reads the next object as an
// array header and returns the size of the array
// and the number of bytes read.
func (m *Reader) ReadArrayHeader() (sz uint32, err error) {
var lead byte
var p []byte
p, err = m.R.Peek(1)
if err != nil {
return
}
lead = p[0]
if isfixarray(lead) {
sz = uint32(rfixarray(lead))
_, err = m.R.Skip(1)
return
}
switch lead {
case marray16:
p, err = m.R.Next(3)
if err != nil {
return
}
sz = uint32(big.Uint16(p[1:]))
return
case marray32:
p, err = m.R.Next(5)
if err != nil {
return
}
sz = big.Uint32(p[1:])
return
default:
err = badPrefix(ArrayType, lead)
return
}
}
// ReadNil reads a 'nil' MessagePack byte from the reader
func (m *Reader) ReadNil() error {
p, err := m.R.Peek(1)
if err != nil {
return err
}
if p[0] != mnil {
return badPrefix(NilType, p[0])
}
_, err = m.R.Skip(1)
return err
}
// ReadFloat64 reads a float64 from the reader.
// (If the value on the wire is encoded as a float32,
// it will be up-cast to a float64.)
func (m *Reader) ReadFloat64() (f float64, err error) {
var p []byte
p, err = m.R.Peek(9)
if err != nil {
// we'll allow a coversion from float32 to float64,
// since we don't lose any precision
if err == io.EOF && len(p) > 0 && p[0] == mfloat32 {
ef, err := m.ReadFloat32()
return float64(ef), err
}
return
}
if p[0] != mfloat64 {
// see above
if p[0] == mfloat32 {
ef, err := m.ReadFloat32()
return float64(ef), err
}
err = badPrefix(Float64Type, p[0])
return
}
f = math.Float64frombits(getMuint64(p))
_, err = m.R.Skip(9)
return
}
// ReadFloat32 reads a float32 from the reader
func (m *Reader) ReadFloat32() (f float32, err error) {
var p []byte
p, err = m.R.Peek(5)
if err != nil {
return
}
if p[0] != mfloat32 {
err = badPrefix(Float32Type, p[0])
return
}
f = math.Float32frombits(getMuint32(p))
_, err = m.R.Skip(5)
return
}
// ReadBool reads a bool from the reader
func (m *Reader) ReadBool() (b bool, err error) {
var p []byte
p, err = m.R.Peek(1)
if err != nil {
return
}
switch p[0] {
case mtrue:
b = true
case mfalse:
default:
err = badPrefix(BoolType, p[0])
return
}
_, err = m.R.Skip(1)
return
}
// ReadInt64 reads an int64 from the reader
func (m *Reader) ReadInt64() (i int64, err error) {
var p []byte
var lead byte
p, err = m.R.Peek(1)
if err != nil {
return
}
lead = p[0]
if isfixint(lead) {
i = int64(rfixint(lead))
_, err = m.R.Skip(1)
return
} else if isnfixint(lead) {
i = int64(rnfixint(lead))
_, err = m.R.Skip(1)
return
}
switch lead {
case mint8:
p, err = m.R.Next(2)
if err != nil {
return
}
i = int64(getMint8(p))
return
case mint16:
p, err = m.R.Next(3)
if err != nil {
return
}
i = int64(getMint16(p))
return
case mint32:
p, err = m.R.Next(5)
if err != nil {
return
}
i = int64(getMint32(p))
return
case mint64:
p, err = m.R.Next(9)
if err != nil {
return
}
i = getMint64(p)
return
default:
err = badPrefix(IntType, lead)
return
}
}
// ReadInt32 reads an int32 from the reader
func (m *Reader) ReadInt32() (i int32, err error) {
var in int64
in, err = m.ReadInt64()
if in > math.MaxInt32 || in < math.MinInt32 {
err = IntOverflow{Value: in, FailedBitsize: 32}
return
}
i = int32(in)
return
}
// ReadInt16 reads an int16 from the reader
func (m *Reader) ReadInt16() (i int16, err error) {
var in int64
in, err = m.ReadInt64()
if in > math.MaxInt16 || in < math.MinInt16 {
err = IntOverflow{Value: in, FailedBitsize: 16}
return
}
i = int16(in)
return
}
// ReadInt8 reads an int8 from the reader
func (m *Reader) ReadInt8() (i int8, err error) {
var in int64
in, err = m.ReadInt64()
if in > math.MaxInt8 || in < math.MinInt8 {
err = IntOverflow{Value: in, FailedBitsize: 8}
return
}
i = int8(in)
return
}
// ReadInt reads an int from the reader
func (m *Reader) ReadInt() (i int, err error) {
if smallint {
var in int32
in, err = m.ReadInt32()
i = int(in)
return
}
var in int64
in, err = m.ReadInt64()
i = int(in)
return
}
// ReadUint64 reads a uint64 from the reader
func (m *Reader) ReadUint64() (u uint64, err error) {
var p []byte
var lead byte
p, err = m.R.Peek(1)
if err != nil {
return
}
lead = p[0]
if isfixint(lead) {
u = uint64(rfixint(lead))
_, err = m.R.Skip(1)
return
}
switch lead {
case muint8:
p, err = m.R.Next(2)
if err != nil {
return
}
u = uint64(getMuint8(p))
return
case muint16:
p, err = m.R.Next(3)
if err != nil {
return
}
u = uint64(getMuint16(p))
return
case muint32:
p, err = m.R.Next(5)
if err != nil {
return
}
u = uint64(getMuint32(p))
return
case muint64:
p, err = m.R.Next(9)
if err != nil {
return
}
u = getMuint64(p)
return
default:
err = badPrefix(UintType, lead)
return
}
}
// ReadUint32 reads a uint32 from the reader
func (m *Reader) ReadUint32() (u uint32, err error) {
var in uint64
in, err = m.ReadUint64()
if in > math.MaxUint32 {
err = UintOverflow{Value: in, FailedBitsize: 32}
return
}
u = uint32(in)
return
}
// ReadUint16 reads a uint16 from the reader
func (m *Reader) ReadUint16() (u uint16, err error) {
var in uint64
in, err = m.ReadUint64()
if in > math.MaxUint16 {
err = UintOverflow{Value: in, FailedBitsize: 16}
return
}
u = uint16(in)
return
}
// ReadUint8 reads a uint8 from the reader
func (m *Reader) ReadUint8() (u uint8, err error) {
var in uint64
in, err = m.ReadUint64()
if in > math.MaxUint8 {
err = UintOverflow{Value: in, FailedBitsize: 8}
return
}
u = uint8(in)
return
}
// ReadUint reads a uint from the reader
func (m *Reader) ReadUint() (u uint, err error) {
if smallint {
var un uint32
un, err = m.ReadUint32()
u = uint(un)
return
}
var un uint64
un, err = m.ReadUint64()
u = uint(un)
return
}
// ReadByte is analogous to ReadUint8.
//
// NOTE: this is *not* an implementation
// of io.ByteReader.
func (m *Reader) ReadByte() (b byte, err error) {
var in uint64
in, err = m.ReadUint64()
if in > math.MaxUint8 {
err = UintOverflow{Value: in, FailedBitsize: 8}
return
}
b = byte(in)
return
}
// ReadBytes reads a MessagePack 'bin' object
// from the reader and returns its value. It may
// use 'scratch' for storage if it is non-nil.
func (m *Reader) ReadBytes(scratch []byte) (b []byte, err error) {
var p []byte
var lead byte
p, err = m.R.Peek(2)
if err != nil {
return
}
lead = p[0]
var read int64
switch lead {
case mbin8:
read = int64(p[1])
m.R.Skip(2)
case mbin16:
p, err = m.R.Next(3)
if err != nil {
return
}
read = int64(big.Uint16(p[1:]))
case mbin32:
p, err = m.R.Next(5)
if err != nil {
return
}
read = int64(big.Uint32(p[1:]))
default:
err = badPrefix(BinType, lead)
return
}
if int64(cap(scratch)) < read {
b = make([]byte, read)
} else {
b = scratch[0:read]
}
_, err = m.R.ReadFull(b)
return
}
// ReadBytesHeader reads the size header
// of a MessagePack 'bin' object. The user
// is responsible for dealing with the next
// 'sz' bytes from the reader in an application-specific
// way.
func (m *Reader) ReadBytesHeader() (sz uint32, err error) {
var p []byte
p, err = m.R.Peek(1)
if err != nil {
return
}
switch p[0] {
case mbin8:
p, err = m.R.Next(2)
if err != nil {
return
}
sz = uint32(p[1])
return
case mbin16:
p, err = m.R.Next(3)
if err != nil {
return
}
sz = uint32(big.Uint16(p[1:]))
return
case mbin32:
p, err = m.R.Next(5)
if err != nil {
return
}
sz = uint32(big.Uint32(p[1:]))
return
default:
err = badPrefix(BinType, p[0])
return
}
}
// ReadExactBytes reads a MessagePack 'bin'-encoded
// object off of the wire into the provided slice. An
// ArrayError will be returned if the object is not
// exactly the length of the input slice.
func (m *Reader) ReadExactBytes(into []byte) error {
p, err := m.R.Peek(2)
if err != nil {
return err
}
lead := p[0]
var read int64 // bytes to read
var skip int // prefix size to skip
switch lead {
case mbin8:
read = int64(p[1])
skip = 2
case mbin16:
p, err = m.R.Peek(3)
if err != nil {
return err
}
read = int64(big.Uint16(p[1:]))
skip = 3
case mbin32:
p, err = m.R.Peek(5)
if err != nil {
return err
}
read = int64(big.Uint32(p[1:]))
skip = 5
default:
return badPrefix(BinType, lead)
}
if read != int64(len(into)) {
return ArrayError{Wanted: uint32(len(into)), Got: uint32(read)}
}
m.R.Skip(skip)
_, err = m.R.ReadFull(into)
return err
}
// ReadStringAsBytes reads a MessagePack 'str' (utf-8) string
// and returns its value as bytes. It may use 'scratch' for storage
// if it is non-nil.
func (m *Reader) ReadStringAsBytes(scratch []byte) (b []byte, err error) {
var p []byte
var lead byte
p, err = m.R.Peek(1)
if err != nil {
return
}
lead = p[0]
var read int64
if isfixstr(lead) {
read = int64(rfixstr(lead))
m.R.Skip(1)
goto fill
}
switch lead {
case mstr8:
p, err = m.R.Next(2)
if err != nil {
return
}
read = int64(uint8(p[1]))
case mstr16:
p, err = m.R.Next(3)
if err != nil {
return
}
read = int64(big.Uint16(p[1:]))
case mstr32:
p, err = m.R.Next(5)
if err != nil {
return
}
read = int64(big.Uint32(p[1:]))
default:
err = badPrefix(StrType, lead)
return
}
fill:
if int64(cap(scratch)) < read {
b = make([]byte, read)
} else {
b = scratch[0:read]
}
_, err = m.R.ReadFull(b)
return
}
// ReadStringHeader reads a string header
// off of the wire. The user is then responsible
// for dealing with the next 'sz' bytes from
// the reader in an application-specific manner.
func (m *Reader) ReadStringHeader() (sz uint32, err error) {
var p []byte
p, err = m.R.Peek(1)
if err != nil {
return
}
lead := p[0]
if isfixstr(lead) {
sz = uint32(rfixstr(lead))
m.R.Skip(1)
return
}
switch lead {
case mstr8:
p, err = m.R.Next(2)
if err != nil {
return
}
sz = uint32(p[1])
return
case mstr16:
p, err = m.R.Next(3)
if err != nil {
return
}
sz = uint32(big.Uint16(p[1:]))
return
case mstr32:
p, err = m.R.Next(5)
if err != nil {
return
}
sz = big.Uint32(p[1:])
return
default:
err = badPrefix(StrType, lead)
return
}
}
// ReadString reads a utf-8 string from the reader
func (m *Reader) ReadString() (s string, err error) {
var p []byte
var lead byte
var read int64
p, err = m.R.Peek(1)
if err != nil {
return
}
lead = p[0]
if isfixstr(lead) {
read = int64(rfixstr(lead))
m.R.Skip(1)
goto fill
}
switch lead {
case mstr8:
p, err = m.R.Next(2)
if err != nil {
return
}
read = int64(uint8(p[1]))
case mstr16:
p, err = m.R.Next(3)
if err != nil {
return
}
read = int64(big.Uint16(p[1:]))
case mstr32:
p, err = m.R.Next(5)
if err != nil {
return
}
read = int64(big.Uint32(p[1:]))
default:
err = badPrefix(StrType, lead)
return
}
fill:
if read == 0 {
s, err = "", nil
return
}
// reading into the memory
// that will become the string
// itself has vastly superior
// worst-case performance, because
// the reader buffer doesn't have
// to be large enough to hold the string.