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Diffstat (limited to 'src/encoding/binary/binary.go')
| -rw-r--r-- | src/encoding/binary/binary.go | 737 |
1 files changed, 737 insertions, 0 deletions
diff --git a/src/encoding/binary/binary.go b/src/encoding/binary/binary.go new file mode 100644 index 0000000..a311499 --- /dev/null +++ b/src/encoding/binary/binary.go @@ -0,0 +1,737 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package binary implements simple translation between numbers and byte +// sequences and encoding and decoding of varints. +// +// Numbers are translated by reading and writing fixed-size values. +// A fixed-size value is either a fixed-size arithmetic +// type (bool, int8, uint8, int16, float32, complex64, ...) +// or an array or struct containing only fixed-size values. +// +// The varint functions encode and decode single integer values using +// a variable-length encoding; smaller values require fewer bytes. +// For a specification, see +// https://developers.google.com/protocol-buffers/docs/encoding. +// +// This package favors simplicity over efficiency. Clients that require +// high-performance serialization, especially for large data structures, +// should look at more advanced solutions such as the encoding/gob +// package or protocol buffers. +package binary + +import ( + "errors" + "io" + "math" + "reflect" + "sync" +) + +// A ByteOrder specifies how to convert byte sequences into +// 16-, 32-, or 64-bit unsigned integers. +type ByteOrder interface { + Uint16([]byte) uint16 + Uint32([]byte) uint32 + Uint64([]byte) uint64 + PutUint16([]byte, uint16) + PutUint32([]byte, uint32) + PutUint64([]byte, uint64) + String() string +} + +// LittleEndian is the little-endian implementation of ByteOrder. +var LittleEndian littleEndian + +// BigEndian is the big-endian implementation of ByteOrder. +var BigEndian bigEndian + +type littleEndian struct{} + +func (littleEndian) Uint16(b []byte) uint16 { + _ = b[1] // bounds check hint to compiler; see golang.org/issue/14808 + return uint16(b[0]) | uint16(b[1])<<8 +} + +func (littleEndian) PutUint16(b []byte, v uint16) { + _ = b[1] // early bounds check to guarantee safety of writes below + b[0] = byte(v) + b[1] = byte(v >> 8) +} + +func (littleEndian) Uint32(b []byte) uint32 { + _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808 + return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24 +} + +func (littleEndian) PutUint32(b []byte, v uint32) { + _ = b[3] // early bounds check to guarantee safety of writes below + b[0] = byte(v) + b[1] = byte(v >> 8) + b[2] = byte(v >> 16) + b[3] = byte(v >> 24) +} + +func (littleEndian) Uint64(b []byte) uint64 { + _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808 + return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | + uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56 +} + +func (littleEndian) PutUint64(b []byte, v uint64) { + _ = b[7] // early bounds check to guarantee safety of writes below + b[0] = byte(v) + b[1] = byte(v >> 8) + b[2] = byte(v >> 16) + b[3] = byte(v >> 24) + b[4] = byte(v >> 32) + b[5] = byte(v >> 40) + b[6] = byte(v >> 48) + b[7] = byte(v >> 56) +} + +func (littleEndian) String() string { return "LittleEndian" } + +func (littleEndian) GoString() string { return "binary.LittleEndian" } + +type bigEndian struct{} + +func (bigEndian) Uint16(b []byte) uint16 { + _ = b[1] // bounds check hint to compiler; see golang.org/issue/14808 + return uint16(b[1]) | uint16(b[0])<<8 +} + +func (bigEndian) PutUint16(b []byte, v uint16) { + _ = b[1] // early bounds check to guarantee safety of writes below + b[0] = byte(v >> 8) + b[1] = byte(v) +} + +func (bigEndian) Uint32(b []byte) uint32 { + _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808 + return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24 +} + +func (bigEndian) PutUint32(b []byte, v uint32) { + _ = b[3] // early bounds check to guarantee safety of writes below + b[0] = byte(v >> 24) + b[1] = byte(v >> 16) + b[2] = byte(v >> 8) + b[3] = byte(v) +} + +func (bigEndian) Uint64(b []byte) uint64 { + _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808 + return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 | + uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56 +} + +func (bigEndian) PutUint64(b []byte, v uint64) { + _ = b[7] // early bounds check to guarantee safety of writes below + b[0] = byte(v >> 56) + b[1] = byte(v >> 48) + b[2] = byte(v >> 40) + b[3] = byte(v >> 32) + b[4] = byte(v >> 24) + b[5] = byte(v >> 16) + b[6] = byte(v >> 8) + b[7] = byte(v) +} + +func (bigEndian) String() string { return "BigEndian" } + +func (bigEndian) GoString() string { return "binary.BigEndian" } + +// Read reads structured binary data from r into data. +// Data must be a pointer to a fixed-size value or a slice +// of fixed-size values. +// Bytes read from r are decoded using the specified byte order +// and written to successive fields of the data. +// When decoding boolean values, a zero byte is decoded as false, and +// any other non-zero byte is decoded as true. +// When reading into structs, the field data for fields with +// blank (_) field names is skipped; i.e., blank field names +// may be used for padding. +// When reading into a struct, all non-blank fields must be exported +// or Read may panic. +// +// The error is EOF only if no bytes were read. +// If an EOF happens after reading some but not all the bytes, +// Read returns ErrUnexpectedEOF. +func Read(r io.Reader, order ByteOrder, data interface{}) error { + // Fast path for basic types and slices. + if n := intDataSize(data); n != 0 { + bs := make([]byte, n) + if _, err := io.ReadFull(r, bs); err != nil { + return err + } + switch data := data.(type) { + case *bool: + *data = bs[0] != 0 + case *int8: + *data = int8(bs[0]) + case *uint8: + *data = bs[0] + case *int16: + *data = int16(order.Uint16(bs)) + case *uint16: + *data = order.Uint16(bs) + case *int32: + *data = int32(order.Uint32(bs)) + case *uint32: + *data = order.Uint32(bs) + case *int64: + *data = int64(order.Uint64(bs)) + case *uint64: + *data = order.Uint64(bs) + case *float32: + *data = math.Float32frombits(order.Uint32(bs)) + case *float64: + *data = math.Float64frombits(order.Uint64(bs)) + case []bool: + for i, x := range bs { // Easier to loop over the input for 8-bit values. + data[i] = x != 0 + } + case []int8: + for i, x := range bs { + data[i] = int8(x) + } + case []uint8: + copy(data, bs) + case []int16: + for i := range data { + data[i] = int16(order.Uint16(bs[2*i:])) + } + case []uint16: + for i := range data { + data[i] = order.Uint16(bs[2*i:]) + } + case []int32: + for i := range data { + data[i] = int32(order.Uint32(bs[4*i:])) + } + case []uint32: + for i := range data { + data[i] = order.Uint32(bs[4*i:]) + } + case []int64: + for i := range data { + data[i] = int64(order.Uint64(bs[8*i:])) + } + case []uint64: + for i := range data { + data[i] = order.Uint64(bs[8*i:]) + } + case []float32: + for i := range data { + data[i] = math.Float32frombits(order.Uint32(bs[4*i:])) + } + case []float64: + for i := range data { + data[i] = math.Float64frombits(order.Uint64(bs[8*i:])) + } + default: + n = 0 // fast path doesn't apply + } + if n != 0 { + return nil + } + } + + // Fallback to reflect-based decoding. + v := reflect.ValueOf(data) + size := -1 + switch v.Kind() { + case reflect.Ptr: + v = v.Elem() + size = dataSize(v) + case reflect.Slice: + size = dataSize(v) + } + if size < 0 { + return errors.New("binary.Read: invalid type " + reflect.TypeOf(data).String()) + } + d := &decoder{order: order, buf: make([]byte, size)} + if _, err := io.ReadFull(r, d.buf); err != nil { + return err + } + d.value(v) + return nil +} + +// Write writes the binary representation of data into w. +// Data must be a fixed-size value or a slice of fixed-size +// values, or a pointer to such data. +// Boolean values encode as one byte: 1 for true, and 0 for false. +// Bytes written to w are encoded using the specified byte order +// and read from successive fields of the data. +// When writing structs, zero values are written for fields +// with blank (_) field names. +func Write(w io.Writer, order ByteOrder, data interface{}) error { + // Fast path for basic types and slices. + if n := intDataSize(data); n != 0 { + bs := make([]byte, n) + switch v := data.(type) { + case *bool: + if *v { + bs[0] = 1 + } else { + bs[0] = 0 + } + case bool: + if v { + bs[0] = 1 + } else { + bs[0] = 0 + } + case []bool: + for i, x := range v { + if x { + bs[i] = 1 + } else { + bs[i] = 0 + } + } + case *int8: + bs[0] = byte(*v) + case int8: + bs[0] = byte(v) + case []int8: + for i, x := range v { + bs[i] = byte(x) + } + case *uint8: + bs[0] = *v + case uint8: + bs[0] = v + case []uint8: + bs = v + case *int16: + order.PutUint16(bs, uint16(*v)) + case int16: + order.PutUint16(bs, uint16(v)) + case []int16: + for i, x := range v { + order.PutUint16(bs[2*i:], uint16(x)) + } + case *uint16: + order.PutUint16(bs, *v) + case uint16: + order.PutUint16(bs, v) + case []uint16: + for i, x := range v { + order.PutUint16(bs[2*i:], x) + } + case *int32: + order.PutUint32(bs, uint32(*v)) + case int32: + order.PutUint32(bs, uint32(v)) + case []int32: + for i, x := range v { + order.PutUint32(bs[4*i:], uint32(x)) + } + case *uint32: + order.PutUint32(bs, *v) + case uint32: + order.PutUint32(bs, v) + case []uint32: + for i, x := range v { + order.PutUint32(bs[4*i:], x) + } + case *int64: + order.PutUint64(bs, uint64(*v)) + case int64: + order.PutUint64(bs, uint64(v)) + case []int64: + for i, x := range v { + order.PutUint64(bs[8*i:], uint64(x)) + } + case *uint64: + order.PutUint64(bs, *v) + case uint64: + order.PutUint64(bs, v) + case []uint64: + for i, x := range v { + order.PutUint64(bs[8*i:], x) + } + case *float32: + order.PutUint32(bs, math.Float32bits(*v)) + case float32: + order.PutUint32(bs, math.Float32bits(v)) + case []float32: + for i, x := range v { + order.PutUint32(bs[4*i:], math.Float32bits(x)) + } + case *float64: + order.PutUint64(bs, math.Float64bits(*v)) + case float64: + order.PutUint64(bs, math.Float64bits(v)) + case []float64: + for i, x := range v { + order.PutUint64(bs[8*i:], math.Float64bits(x)) + } + } + _, err := w.Write(bs) + return err + } + + // Fallback to reflect-based encoding. + v := reflect.Indirect(reflect.ValueOf(data)) + size := dataSize(v) + if size < 0 { + return errors.New("binary.Write: invalid type " + reflect.TypeOf(data).String()) + } + buf := make([]byte, size) + e := &encoder{order: order, buf: buf} + e.value(v) + _, err := w.Write(buf) + return err +} + +// Size returns how many bytes Write would generate to encode the value v, which +// must be a fixed-size value or a slice of fixed-size values, or a pointer to such data. +// If v is neither of these, Size returns -1. +func Size(v interface{}) int { + return dataSize(reflect.Indirect(reflect.ValueOf(v))) +} + +var structSize sync.Map // map[reflect.Type]int + +// dataSize returns the number of bytes the actual data represented by v occupies in memory. +// For compound structures, it sums the sizes of the elements. Thus, for instance, for a slice +// it returns the length of the slice times the element size and does not count the memory +// occupied by the header. If the type of v is not acceptable, dataSize returns -1. +func dataSize(v reflect.Value) int { + switch v.Kind() { + case reflect.Slice: + if s := sizeof(v.Type().Elem()); s >= 0 { + return s * v.Len() + } + return -1 + + case reflect.Struct: + t := v.Type() + if size, ok := structSize.Load(t); ok { + return size.(int) + } + size := sizeof(t) + structSize.Store(t, size) + return size + + default: + return sizeof(v.Type()) + } +} + +// sizeof returns the size >= 0 of variables for the given type or -1 if the type is not acceptable. +func sizeof(t reflect.Type) int { + switch t.Kind() { + case reflect.Array: + if s := sizeof(t.Elem()); s >= 0 { + return s * t.Len() + } + + case reflect.Struct: + sum := 0 + for i, n := 0, t.NumField(); i < n; i++ { + s := sizeof(t.Field(i).Type) + if s < 0 { + return -1 + } + sum += s + } + return sum + + case reflect.Bool, + reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, + reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, + reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128: + return int(t.Size()) + } + + return -1 +} + +type coder struct { + order ByteOrder + buf []byte + offset int +} + +type decoder coder +type encoder coder + +func (d *decoder) bool() bool { + x := d.buf[d.offset] + d.offset++ + return x != 0 +} + +func (e *encoder) bool(x bool) { + if x { + e.buf[e.offset] = 1 + } else { + e.buf[e.offset] = 0 + } + e.offset++ +} + +func (d *decoder) uint8() uint8 { + x := d.buf[d.offset] + d.offset++ + return x +} + +func (e *encoder) uint8(x uint8) { + e.buf[e.offset] = x + e.offset++ +} + +func (d *decoder) uint16() uint16 { + x := d.order.Uint16(d.buf[d.offset : d.offset+2]) + d.offset += 2 + return x +} + +func (e *encoder) uint16(x uint16) { + e.order.PutUint16(e.buf[e.offset:e.offset+2], x) + e.offset += 2 +} + +func (d *decoder) uint32() uint32 { + x := d.order.Uint32(d.buf[d.offset : d.offset+4]) + d.offset += 4 + return x +} + +func (e *encoder) uint32(x uint32) { + e.order.PutUint32(e.buf[e.offset:e.offset+4], x) + e.offset += 4 +} + +func (d *decoder) uint64() uint64 { + x := d.order.Uint64(d.buf[d.offset : d.offset+8]) + d.offset += 8 + return x +} + +func (e *encoder) uint64(x uint64) { + e.order.PutUint64(e.buf[e.offset:e.offset+8], x) + e.offset += 8 +} + +func (d *decoder) int8() int8 { return int8(d.uint8()) } + +func (e *encoder) int8(x int8) { e.uint8(uint8(x)) } + +func (d *decoder) int16() int16 { return int16(d.uint16()) } + +func (e *encoder) int16(x int16) { e.uint16(uint16(x)) } + +func (d *decoder) int32() int32 { return int32(d.uint32()) } + +func (e *encoder) int32(x int32) { e.uint32(uint32(x)) } + +func (d *decoder) int64() int64 { return int64(d.uint64()) } + +func (e *encoder) int64(x int64) { e.uint64(uint64(x)) } + +func (d *decoder) value(v reflect.Value) { + switch v.Kind() { + case reflect.Array: + l := v.Len() + for i := 0; i < l; i++ { + d.value(v.Index(i)) + } + + case reflect.Struct: + t := v.Type() + l := v.NumField() + for i := 0; i < l; i++ { + // Note: Calling v.CanSet() below is an optimization. + // It would be sufficient to check the field name, + // but creating the StructField info for each field is + // costly (run "go test -bench=ReadStruct" and compare + // results when making changes to this code). + if v := v.Field(i); v.CanSet() || t.Field(i).Name != "_" { + d.value(v) + } else { + d.skip(v) + } + } + + case reflect.Slice: + l := v.Len() + for i := 0; i < l; i++ { + d.value(v.Index(i)) + } + + case reflect.Bool: + v.SetBool(d.bool()) + + case reflect.Int8: + v.SetInt(int64(d.int8())) + case reflect.Int16: + v.SetInt(int64(d.int16())) + case reflect.Int32: + v.SetInt(int64(d.int32())) + case reflect.Int64: + v.SetInt(d.int64()) + + case reflect.Uint8: + v.SetUint(uint64(d.uint8())) + case reflect.Uint16: + v.SetUint(uint64(d.uint16())) + case reflect.Uint32: + v.SetUint(uint64(d.uint32())) + case reflect.Uint64: + v.SetUint(d.uint64()) + + case reflect.Float32: + v.SetFloat(float64(math.Float32frombits(d.uint32()))) + case reflect.Float64: + v.SetFloat(math.Float64frombits(d.uint64())) + + case reflect.Complex64: + v.SetComplex(complex( + float64(math.Float32frombits(d.uint32())), + float64(math.Float32frombits(d.uint32())), + )) + case reflect.Complex128: + v.SetComplex(complex( + math.Float64frombits(d.uint64()), + math.Float64frombits(d.uint64()), + )) + } +} + +func (e *encoder) value(v reflect.Value) { + switch v.Kind() { + case reflect.Array: + l := v.Len() + for i := 0; i < l; i++ { + e.value(v.Index(i)) + } + + case reflect.Struct: + t := v.Type() + l := v.NumField() + for i := 0; i < l; i++ { + // see comment for corresponding code in decoder.value() + if v := v.Field(i); v.CanSet() || t.Field(i).Name != "_" { + e.value(v) + } else { + e.skip(v) + } + } + + case reflect.Slice: + l := v.Len() + for i := 0; i < l; i++ { + e.value(v.Index(i)) + } + + case reflect.Bool: + e.bool(v.Bool()) + + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + switch v.Type().Kind() { + case reflect.Int8: + e.int8(int8(v.Int())) + case reflect.Int16: + e.int16(int16(v.Int())) + case reflect.Int32: + e.int32(int32(v.Int())) + case reflect.Int64: + e.int64(v.Int()) + } + + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + switch v.Type().Kind() { + case reflect.Uint8: + e.uint8(uint8(v.Uint())) + case reflect.Uint16: + e.uint16(uint16(v.Uint())) + case reflect.Uint32: + e.uint32(uint32(v.Uint())) + case reflect.Uint64: + e.uint64(v.Uint()) + } + + case reflect.Float32, reflect.Float64: + switch v.Type().Kind() { + case reflect.Float32: + e.uint32(math.Float32bits(float32(v.Float()))) + case reflect.Float64: + e.uint64(math.Float64bits(v.Float())) + } + + case reflect.Complex64, reflect.Complex128: + switch v.Type().Kind() { + case reflect.Complex64: + x := v.Complex() + e.uint32(math.Float32bits(float32(real(x)))) + e.uint32(math.Float32bits(float32(imag(x)))) + case reflect.Complex128: + x := v.Complex() + e.uint64(math.Float64bits(real(x))) + e.uint64(math.Float64bits(imag(x))) + } + } +} + +func (d *decoder) skip(v reflect.Value) { + d.offset += dataSize(v) +} + +func (e *encoder) skip(v reflect.Value) { + n := dataSize(v) + zero := e.buf[e.offset : e.offset+n] + for i := range zero { + zero[i] = 0 + } + e.offset += n +} + +// intDataSize returns the size of the data required to represent the data when encoded. +// It returns zero if the type cannot be implemented by the fast path in Read or Write. +func intDataSize(data interface{}) int { + switch data := data.(type) { + case bool, int8, uint8, *bool, *int8, *uint8: + return 1 + case []bool: + return len(data) + case []int8: + return len(data) + case []uint8: + return len(data) + case int16, uint16, *int16, *uint16: + return 2 + case []int16: + return 2 * len(data) + case []uint16: + return 2 * len(data) + case int32, uint32, *int32, *uint32: + return 4 + case []int32: + return 4 * len(data) + case []uint32: + return 4 * len(data) + case int64, uint64, *int64, *uint64: + return 8 + case []int64: + return 8 * len(data) + case []uint64: + return 8 * len(data) + case float32, *float32: + return 4 + case float64, *float64: + return 8 + case []float32: + return 4 * len(data) + case []float64: + return 8 * len(data) + } + return 0 +} |