mirror of
https://github.com/autc04/Retro68.git
synced 2024-09-08 05:54:40 +00:00
1218 lines
38 KiB
Go
1218 lines
38 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:generate go run decgen.go -output dec_helpers.go
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package gob
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import (
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"encoding"
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"errors"
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"io"
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"math"
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"reflect"
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)
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var (
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errBadUint = errors.New("gob: encoded unsigned integer out of range")
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errBadType = errors.New("gob: unknown type id or corrupted data")
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errRange = errors.New("gob: bad data: field numbers out of bounds")
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)
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type decHelper func(state *decoderState, v reflect.Value, length int, ovfl error) bool
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// decoderState is the execution state of an instance of the decoder. A new state
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// is created for nested objects.
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type decoderState struct {
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dec *Decoder
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// The buffer is stored with an extra indirection because it may be replaced
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// if we load a type during decode (when reading an interface value).
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b *decBuffer
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fieldnum int // the last field number read.
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buf []byte
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next *decoderState // for free list
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}
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// decBuffer is an extremely simple, fast implementation of a read-only byte buffer.
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// It is initialized by calling Size and then copying the data into the slice returned by Bytes().
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type decBuffer struct {
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data []byte
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offset int // Read offset.
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}
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func (d *decBuffer) Read(p []byte) (int, error) {
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n := copy(p, d.data[d.offset:])
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if n == 0 && len(p) != 0 {
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return 0, io.EOF
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}
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d.offset += n
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return n, nil
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}
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func (d *decBuffer) Drop(n int) {
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if n > d.Len() {
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panic("drop")
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}
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d.offset += n
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}
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// Size grows the buffer to exactly n bytes, so d.Bytes() will
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// return a slice of length n. Existing data is first discarded.
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func (d *decBuffer) Size(n int) {
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d.Reset()
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if cap(d.data) < n {
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d.data = make([]byte, n)
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} else {
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d.data = d.data[0:n]
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}
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}
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func (d *decBuffer) ReadByte() (byte, error) {
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if d.offset >= len(d.data) {
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return 0, io.EOF
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}
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c := d.data[d.offset]
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d.offset++
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return c, nil
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}
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func (d *decBuffer) Len() int {
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return len(d.data) - d.offset
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}
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func (d *decBuffer) Bytes() []byte {
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return d.data[d.offset:]
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}
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func (d *decBuffer) Reset() {
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d.data = d.data[0:0]
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d.offset = 0
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}
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// We pass the bytes.Buffer separately for easier testing of the infrastructure
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// without requiring a full Decoder.
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func (dec *Decoder) newDecoderState(buf *decBuffer) *decoderState {
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d := dec.freeList
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if d == nil {
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d = new(decoderState)
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d.dec = dec
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d.buf = make([]byte, uint64Size)
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} else {
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dec.freeList = d.next
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}
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d.b = buf
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return d
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}
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func (dec *Decoder) freeDecoderState(d *decoderState) {
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d.next = dec.freeList
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dec.freeList = d
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}
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func overflow(name string) error {
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return errors.New(`value for "` + name + `" out of range`)
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}
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// decodeUintReader reads an encoded unsigned integer from an io.Reader.
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// Used only by the Decoder to read the message length.
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func decodeUintReader(r io.Reader, buf []byte) (x uint64, width int, err error) {
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width = 1
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n, err := io.ReadFull(r, buf[0:width])
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if n == 0 {
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return
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}
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b := buf[0]
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if b <= 0x7f {
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return uint64(b), width, nil
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}
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n = -int(int8(b))
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if n > uint64Size {
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err = errBadUint
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return
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}
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width, err = io.ReadFull(r, buf[0:n])
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if err != nil {
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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return
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}
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// Could check that the high byte is zero but it's not worth it.
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for _, b := range buf[0:width] {
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x = x<<8 | uint64(b)
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}
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width++ // +1 for length byte
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return
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}
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// decodeUint reads an encoded unsigned integer from state.r.
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// Does not check for overflow.
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func (state *decoderState) decodeUint() (x uint64) {
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b, err := state.b.ReadByte()
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if err != nil {
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error_(err)
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}
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if b <= 0x7f {
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return uint64(b)
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}
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n := -int(int8(b))
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if n > uint64Size {
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error_(errBadUint)
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}
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width, err := state.b.Read(state.buf[0:n])
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if err != nil {
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error_(err)
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}
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// Don't need to check error; it's safe to loop regardless.
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// Could check that the high byte is zero but it's not worth it.
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for _, b := range state.buf[0:width] {
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x = x<<8 | uint64(b)
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}
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return x
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}
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// decodeInt reads an encoded signed integer from state.r.
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// Does not check for overflow.
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func (state *decoderState) decodeInt() int64 {
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x := state.decodeUint()
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if x&1 != 0 {
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return ^int64(x >> 1)
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}
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return int64(x >> 1)
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}
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// decOp is the signature of a decoding operator for a given type.
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type decOp func(i *decInstr, state *decoderState, v reflect.Value)
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// The 'instructions' of the decoding machine
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type decInstr struct {
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op decOp
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field int // field number of the wire type
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index []int // field access indices for destination type
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ovfl error // error message for overflow/underflow (for arrays, of the elements)
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}
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// ignoreUint discards a uint value with no destination.
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func ignoreUint(i *decInstr, state *decoderState, v reflect.Value) {
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state.decodeUint()
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}
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// ignoreTwoUints discards a uint value with no destination. It's used to skip
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// complex values.
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func ignoreTwoUints(i *decInstr, state *decoderState, v reflect.Value) {
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state.decodeUint()
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state.decodeUint()
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}
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// Since the encoder writes no zeros, if we arrive at a decoder we have
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// a value to extract and store. The field number has already been read
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// (it's how we knew to call this decoder).
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// Each decoder is responsible for handling any indirections associated
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// with the data structure. If any pointer so reached is nil, allocation must
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// be done.
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// decAlloc takes a value and returns a settable value that can
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// be assigned to. If the value is a pointer, decAlloc guarantees it points to storage.
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// The callers to the individual decoders are expected to have used decAlloc.
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// The individual decoders don't need to it.
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func decAlloc(v reflect.Value) reflect.Value {
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for v.Kind() == reflect.Ptr {
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if v.IsNil() {
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v.Set(reflect.New(v.Type().Elem()))
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}
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v = v.Elem()
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}
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return v
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}
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// decBool decodes a uint and stores it as a boolean in value.
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func decBool(i *decInstr, state *decoderState, value reflect.Value) {
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value.SetBool(state.decodeUint() != 0)
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}
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// decInt8 decodes an integer and stores it as an int8 in value.
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func decInt8(i *decInstr, state *decoderState, value reflect.Value) {
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v := state.decodeInt()
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if v < math.MinInt8 || math.MaxInt8 < v {
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error_(i.ovfl)
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}
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value.SetInt(v)
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}
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// decUint8 decodes an unsigned integer and stores it as a uint8 in value.
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func decUint8(i *decInstr, state *decoderState, value reflect.Value) {
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v := state.decodeUint()
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if math.MaxUint8 < v {
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error_(i.ovfl)
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}
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value.SetUint(v)
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}
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// decInt16 decodes an integer and stores it as an int16 in value.
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func decInt16(i *decInstr, state *decoderState, value reflect.Value) {
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v := state.decodeInt()
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if v < math.MinInt16 || math.MaxInt16 < v {
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error_(i.ovfl)
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}
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value.SetInt(v)
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}
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// decUint16 decodes an unsigned integer and stores it as a uint16 in value.
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func decUint16(i *decInstr, state *decoderState, value reflect.Value) {
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v := state.decodeUint()
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if math.MaxUint16 < v {
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error_(i.ovfl)
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}
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value.SetUint(v)
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}
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// decInt32 decodes an integer and stores it as an int32 in value.
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func decInt32(i *decInstr, state *decoderState, value reflect.Value) {
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v := state.decodeInt()
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if v < math.MinInt32 || math.MaxInt32 < v {
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error_(i.ovfl)
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}
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value.SetInt(v)
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}
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// decUint32 decodes an unsigned integer and stores it as a uint32 in value.
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func decUint32(i *decInstr, state *decoderState, value reflect.Value) {
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v := state.decodeUint()
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if math.MaxUint32 < v {
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error_(i.ovfl)
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}
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value.SetUint(v)
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}
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// decInt64 decodes an integer and stores it as an int64 in value.
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func decInt64(i *decInstr, state *decoderState, value reflect.Value) {
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v := state.decodeInt()
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value.SetInt(v)
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}
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// decUint64 decodes an unsigned integer and stores it as a uint64 in value.
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func decUint64(i *decInstr, state *decoderState, value reflect.Value) {
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v := state.decodeUint()
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value.SetUint(v)
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}
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// Floating-point numbers are transmitted as uint64s holding the bits
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// of the underlying representation. They are sent byte-reversed, with
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// the exponent end coming out first, so integer floating point numbers
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// (for example) transmit more compactly. This routine does the
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// unswizzling.
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func float64FromBits(u uint64) float64 {
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var v uint64
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for i := 0; i < 8; i++ {
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v <<= 8
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v |= u & 0xFF
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u >>= 8
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}
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return math.Float64frombits(v)
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}
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// float32FromBits decodes an unsigned integer, treats it as a 32-bit floating-point
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// number, and returns it. It's a helper function for float32 and complex64.
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// It returns a float64 because that's what reflection needs, but its return
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// value is known to be accurately representable in a float32.
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func float32FromBits(u uint64, ovfl error) float64 {
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v := float64FromBits(u)
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av := v
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if av < 0 {
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av = -av
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}
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// +Inf is OK in both 32- and 64-bit floats. Underflow is always OK.
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if math.MaxFloat32 < av && av <= math.MaxFloat64 {
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error_(ovfl)
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}
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return v
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}
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// decFloat32 decodes an unsigned integer, treats it as a 32-bit floating-point
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// number, and stores it in value.
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func decFloat32(i *decInstr, state *decoderState, value reflect.Value) {
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value.SetFloat(float32FromBits(state.decodeUint(), i.ovfl))
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}
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// decFloat64 decodes an unsigned integer, treats it as a 64-bit floating-point
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// number, and stores it in value.
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func decFloat64(i *decInstr, state *decoderState, value reflect.Value) {
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value.SetFloat(float64FromBits(state.decodeUint()))
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}
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// decComplex64 decodes a pair of unsigned integers, treats them as a
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// pair of floating point numbers, and stores them as a complex64 in value.
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// The real part comes first.
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func decComplex64(i *decInstr, state *decoderState, value reflect.Value) {
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real := float32FromBits(state.decodeUint(), i.ovfl)
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imag := float32FromBits(state.decodeUint(), i.ovfl)
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value.SetComplex(complex(real, imag))
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}
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// decComplex128 decodes a pair of unsigned integers, treats them as a
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// pair of floating point numbers, and stores them as a complex128 in value.
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// The real part comes first.
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func decComplex128(i *decInstr, state *decoderState, value reflect.Value) {
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real := float64FromBits(state.decodeUint())
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imag := float64FromBits(state.decodeUint())
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value.SetComplex(complex(real, imag))
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}
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// decUint8Slice decodes a byte slice and stores in value a slice header
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// describing the data.
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// uint8 slices are encoded as an unsigned count followed by the raw bytes.
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func decUint8Slice(i *decInstr, state *decoderState, value reflect.Value) {
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u := state.decodeUint()
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n := int(u)
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if n < 0 || uint64(n) != u {
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errorf("length of %s exceeds input size (%d bytes)", value.Type(), u)
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}
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if n > state.b.Len() {
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errorf("%s data too long for buffer: %d", value.Type(), n)
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}
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if n > tooBig {
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errorf("byte slice too big: %d", n)
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}
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if value.Cap() < n {
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value.Set(reflect.MakeSlice(value.Type(), n, n))
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} else {
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value.Set(value.Slice(0, n))
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}
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if _, err := state.b.Read(value.Bytes()); err != nil {
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errorf("error decoding []byte: %s", err)
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}
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}
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// decString decodes byte array and stores in value a string header
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// describing the data.
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// Strings are encoded as an unsigned count followed by the raw bytes.
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func decString(i *decInstr, state *decoderState, value reflect.Value) {
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u := state.decodeUint()
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n := int(u)
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if n < 0 || uint64(n) != u || n > state.b.Len() {
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errorf("length of %s exceeds input size (%d bytes)", value.Type(), u)
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}
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if n > state.b.Len() {
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errorf("%s data too long for buffer: %d", value.Type(), n)
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}
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// Read the data.
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data := make([]byte, n)
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if _, err := state.b.Read(data); err != nil {
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errorf("error decoding string: %s", err)
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}
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value.SetString(string(data))
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}
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// ignoreUint8Array skips over the data for a byte slice value with no destination.
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func ignoreUint8Array(i *decInstr, state *decoderState, value reflect.Value) {
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b := make([]byte, state.decodeUint())
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state.b.Read(b)
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}
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// Execution engine
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// The encoder engine is an array of instructions indexed by field number of the incoming
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// decoder. It is executed with random access according to field number.
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type decEngine struct {
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instr []decInstr
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numInstr int // the number of active instructions
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}
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// decodeSingle decodes a top-level value that is not a struct and stores it in value.
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// Such values are preceded by a zero, making them have the memory layout of a
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// struct field (although with an illegal field number).
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func (dec *Decoder) decodeSingle(engine *decEngine, ut *userTypeInfo, value reflect.Value) {
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state := dec.newDecoderState(&dec.buf)
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defer dec.freeDecoderState(state)
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state.fieldnum = singletonField
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if state.decodeUint() != 0 {
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errorf("decode: corrupted data: non-zero delta for singleton")
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}
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instr := &engine.instr[singletonField]
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instr.op(instr, state, value)
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}
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// decodeStruct decodes a top-level struct and stores it in value.
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// Indir is for the value, not the type. At the time of the call it may
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// differ from ut.indir, which was computed when the engine was built.
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// This state cannot arise for decodeSingle, which is called directly
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// from the user's value, not from the innards of an engine.
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func (dec *Decoder) decodeStruct(engine *decEngine, ut *userTypeInfo, value reflect.Value) {
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state := dec.newDecoderState(&dec.buf)
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defer dec.freeDecoderState(state)
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state.fieldnum = -1
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for state.b.Len() > 0 {
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delta := int(state.decodeUint())
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if delta < 0 {
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errorf("decode: corrupted data: negative delta")
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}
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if delta == 0 { // struct terminator is zero delta fieldnum
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break
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}
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fieldnum := state.fieldnum + delta
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if fieldnum >= len(engine.instr) {
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error_(errRange)
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break
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}
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instr := &engine.instr[fieldnum]
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var field reflect.Value
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if instr.index != nil {
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// Otherwise the field is unknown to us and instr.op is an ignore op.
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field = value.FieldByIndex(instr.index)
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if field.Kind() == reflect.Ptr {
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field = decAlloc(field)
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}
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}
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instr.op(instr, state, field)
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state.fieldnum = fieldnum
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}
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}
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var noValue reflect.Value
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// ignoreStruct discards the data for a struct with no destination.
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func (dec *Decoder) ignoreStruct(engine *decEngine) {
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state := dec.newDecoderState(&dec.buf)
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defer dec.freeDecoderState(state)
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state.fieldnum = -1
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for state.b.Len() > 0 {
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delta := int(state.decodeUint())
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if delta < 0 {
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errorf("ignore decode: corrupted data: negative delta")
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}
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if delta == 0 { // struct terminator is zero delta fieldnum
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break
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}
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fieldnum := state.fieldnum + delta
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if fieldnum >= len(engine.instr) {
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error_(errRange)
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}
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instr := &engine.instr[fieldnum]
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instr.op(instr, state, noValue)
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state.fieldnum = fieldnum
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}
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}
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// ignoreSingle discards the data for a top-level non-struct value with no
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// destination. It's used when calling Decode with a nil value.
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func (dec *Decoder) ignoreSingle(engine *decEngine) {
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state := dec.newDecoderState(&dec.buf)
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defer dec.freeDecoderState(state)
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state.fieldnum = singletonField
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delta := int(state.decodeUint())
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if delta != 0 {
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errorf("decode: corrupted data: non-zero delta for singleton")
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}
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instr := &engine.instr[singletonField]
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instr.op(instr, state, noValue)
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}
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// decodeArrayHelper does the work for decoding arrays and slices.
|
|
func (dec *Decoder) decodeArrayHelper(state *decoderState, value reflect.Value, elemOp decOp, length int, ovfl error, helper decHelper) {
|
|
if helper != nil && helper(state, value, length, ovfl) {
|
|
return
|
|
}
|
|
instr := &decInstr{elemOp, 0, nil, ovfl}
|
|
isPtr := value.Type().Elem().Kind() == reflect.Ptr
|
|
for i := 0; i < length; i++ {
|
|
if state.b.Len() == 0 {
|
|
errorf("decoding array or slice: length exceeds input size (%d elements)", length)
|
|
}
|
|
v := value.Index(i)
|
|
if isPtr {
|
|
v = decAlloc(v)
|
|
}
|
|
elemOp(instr, state, v)
|
|
}
|
|
}
|
|
|
|
// decodeArray decodes an array and stores it in value.
|
|
// The length is an unsigned integer preceding the elements. Even though the length is redundant
|
|
// (it's part of the type), it's a useful check and is included in the encoding.
|
|
func (dec *Decoder) decodeArray(atyp reflect.Type, state *decoderState, value reflect.Value, elemOp decOp, length int, ovfl error, helper decHelper) {
|
|
if n := state.decodeUint(); n != uint64(length) {
|
|
errorf("length mismatch in decodeArray")
|
|
}
|
|
dec.decodeArrayHelper(state, value, elemOp, length, ovfl, helper)
|
|
}
|
|
|
|
// decodeIntoValue is a helper for map decoding.
|
|
func decodeIntoValue(state *decoderState, op decOp, isPtr bool, value reflect.Value, ovfl error) reflect.Value {
|
|
instr := &decInstr{op, 0, nil, ovfl}
|
|
v := value
|
|
if isPtr {
|
|
v = decAlloc(value)
|
|
}
|
|
op(instr, state, v)
|
|
return value
|
|
}
|
|
|
|
// decodeMap decodes a map and stores it in value.
|
|
// Maps are encoded as a length followed by key:value pairs.
|
|
// Because the internals of maps are not visible to us, we must
|
|
// use reflection rather than pointer magic.
|
|
func (dec *Decoder) decodeMap(mtyp reflect.Type, state *decoderState, value reflect.Value, keyOp, elemOp decOp, ovfl error) {
|
|
if value.IsNil() {
|
|
// Allocate map.
|
|
value.Set(reflect.MakeMap(mtyp))
|
|
}
|
|
n := int(state.decodeUint())
|
|
keyIsPtr := mtyp.Key().Kind() == reflect.Ptr
|
|
elemIsPtr := mtyp.Elem().Kind() == reflect.Ptr
|
|
for i := 0; i < n; i++ {
|
|
key := decodeIntoValue(state, keyOp, keyIsPtr, allocValue(mtyp.Key()), ovfl)
|
|
elem := decodeIntoValue(state, elemOp, elemIsPtr, allocValue(mtyp.Elem()), ovfl)
|
|
value.SetMapIndex(key, elem)
|
|
}
|
|
}
|
|
|
|
// ignoreArrayHelper does the work for discarding arrays and slices.
|
|
func (dec *Decoder) ignoreArrayHelper(state *decoderState, elemOp decOp, length int) {
|
|
instr := &decInstr{elemOp, 0, nil, errors.New("no error")}
|
|
for i := 0; i < length; i++ {
|
|
elemOp(instr, state, noValue)
|
|
}
|
|
}
|
|
|
|
// ignoreArray discards the data for an array value with no destination.
|
|
func (dec *Decoder) ignoreArray(state *decoderState, elemOp decOp, length int) {
|
|
if n := state.decodeUint(); n != uint64(length) {
|
|
errorf("length mismatch in ignoreArray")
|
|
}
|
|
dec.ignoreArrayHelper(state, elemOp, length)
|
|
}
|
|
|
|
// ignoreMap discards the data for a map value with no destination.
|
|
func (dec *Decoder) ignoreMap(state *decoderState, keyOp, elemOp decOp) {
|
|
n := int(state.decodeUint())
|
|
keyInstr := &decInstr{keyOp, 0, nil, errors.New("no error")}
|
|
elemInstr := &decInstr{elemOp, 0, nil, errors.New("no error")}
|
|
for i := 0; i < n; i++ {
|
|
keyOp(keyInstr, state, noValue)
|
|
elemOp(elemInstr, state, noValue)
|
|
}
|
|
}
|
|
|
|
// decodeSlice decodes a slice and stores it in value.
|
|
// Slices are encoded as an unsigned length followed by the elements.
|
|
func (dec *Decoder) decodeSlice(state *decoderState, value reflect.Value, elemOp decOp, ovfl error, helper decHelper) {
|
|
u := state.decodeUint()
|
|
typ := value.Type()
|
|
size := uint64(typ.Elem().Size())
|
|
nBytes := u * size
|
|
n := int(u)
|
|
// Take care with overflow in this calculation.
|
|
if n < 0 || uint64(n) != u || nBytes > tooBig || (size > 0 && nBytes/size != u) {
|
|
// We don't check n against buffer length here because if it's a slice
|
|
// of interfaces, there will be buffer reloads.
|
|
errorf("%s slice too big: %d elements of %d bytes", typ.Elem(), u, size)
|
|
}
|
|
if value.Cap() < n {
|
|
value.Set(reflect.MakeSlice(typ, n, n))
|
|
} else {
|
|
value.Set(value.Slice(0, n))
|
|
}
|
|
dec.decodeArrayHelper(state, value, elemOp, n, ovfl, helper)
|
|
}
|
|
|
|
// ignoreSlice skips over the data for a slice value with no destination.
|
|
func (dec *Decoder) ignoreSlice(state *decoderState, elemOp decOp) {
|
|
dec.ignoreArrayHelper(state, elemOp, int(state.decodeUint()))
|
|
}
|
|
|
|
// decodeInterface decodes an interface value and stores it in value.
|
|
// Interfaces are encoded as the name of a concrete type followed by a value.
|
|
// If the name is empty, the value is nil and no value is sent.
|
|
func (dec *Decoder) decodeInterface(ityp reflect.Type, state *decoderState, value reflect.Value) {
|
|
// Read the name of the concrete type.
|
|
nr := state.decodeUint()
|
|
if nr < 0 || nr > 1<<31 { // zero is permissible for anonymous types
|
|
errorf("invalid type name length %d", nr)
|
|
}
|
|
if nr > uint64(state.b.Len()) {
|
|
errorf("invalid type name length %d: exceeds input size", nr)
|
|
}
|
|
b := make([]byte, nr)
|
|
state.b.Read(b)
|
|
name := string(b)
|
|
// Allocate the destination interface value.
|
|
if name == "" {
|
|
// Copy the nil interface value to the target.
|
|
value.Set(reflect.Zero(value.Type()))
|
|
return
|
|
}
|
|
if len(name) > 1024 {
|
|
errorf("name too long (%d bytes): %.20q...", len(name), name)
|
|
}
|
|
// The concrete type must be registered.
|
|
registerLock.RLock()
|
|
typ, ok := nameToConcreteType[name]
|
|
registerLock.RUnlock()
|
|
if !ok {
|
|
errorf("name not registered for interface: %q", name)
|
|
}
|
|
// Read the type id of the concrete value.
|
|
concreteId := dec.decodeTypeSequence(true)
|
|
if concreteId < 0 {
|
|
error_(dec.err)
|
|
}
|
|
// Byte count of value is next; we don't care what it is (it's there
|
|
// in case we want to ignore the value by skipping it completely).
|
|
state.decodeUint()
|
|
// Read the concrete value.
|
|
v := allocValue(typ)
|
|
dec.decodeValue(concreteId, v)
|
|
if dec.err != nil {
|
|
error_(dec.err)
|
|
}
|
|
// Assign the concrete value to the interface.
|
|
// Tread carefully; it might not satisfy the interface.
|
|
if !typ.AssignableTo(ityp) {
|
|
errorf("%s is not assignable to type %s", typ, ityp)
|
|
}
|
|
// Copy the interface value to the target.
|
|
value.Set(v)
|
|
}
|
|
|
|
// ignoreInterface discards the data for an interface value with no destination.
|
|
func (dec *Decoder) ignoreInterface(state *decoderState) {
|
|
// Read the name of the concrete type.
|
|
b := make([]byte, state.decodeUint())
|
|
_, err := state.b.Read(b)
|
|
if err != nil {
|
|
error_(err)
|
|
}
|
|
id := dec.decodeTypeSequence(true)
|
|
if id < 0 {
|
|
error_(dec.err)
|
|
}
|
|
// At this point, the decoder buffer contains a delimited value. Just toss it.
|
|
state.b.Drop(int(state.decodeUint()))
|
|
}
|
|
|
|
// decodeGobDecoder decodes something implementing the GobDecoder interface.
|
|
// The data is encoded as a byte slice.
|
|
func (dec *Decoder) decodeGobDecoder(ut *userTypeInfo, state *decoderState, value reflect.Value) {
|
|
// Read the bytes for the value.
|
|
b := make([]byte, state.decodeUint())
|
|
_, err := state.b.Read(b)
|
|
if err != nil {
|
|
error_(err)
|
|
}
|
|
// We know it's one of these.
|
|
switch ut.externalDec {
|
|
case xGob:
|
|
err = value.Interface().(GobDecoder).GobDecode(b)
|
|
case xBinary:
|
|
err = value.Interface().(encoding.BinaryUnmarshaler).UnmarshalBinary(b)
|
|
case xText:
|
|
err = value.Interface().(encoding.TextUnmarshaler).UnmarshalText(b)
|
|
}
|
|
if err != nil {
|
|
error_(err)
|
|
}
|
|
}
|
|
|
|
// ignoreGobDecoder discards the data for a GobDecoder value with no destination.
|
|
func (dec *Decoder) ignoreGobDecoder(state *decoderState) {
|
|
// Read the bytes for the value.
|
|
b := make([]byte, state.decodeUint())
|
|
_, err := state.b.Read(b)
|
|
if err != nil {
|
|
error_(err)
|
|
}
|
|
}
|
|
|
|
// Index by Go types.
|
|
var decOpTable = [...]decOp{
|
|
reflect.Bool: decBool,
|
|
reflect.Int8: decInt8,
|
|
reflect.Int16: decInt16,
|
|
reflect.Int32: decInt32,
|
|
reflect.Int64: decInt64,
|
|
reflect.Uint8: decUint8,
|
|
reflect.Uint16: decUint16,
|
|
reflect.Uint32: decUint32,
|
|
reflect.Uint64: decUint64,
|
|
reflect.Float32: decFloat32,
|
|
reflect.Float64: decFloat64,
|
|
reflect.Complex64: decComplex64,
|
|
reflect.Complex128: decComplex128,
|
|
reflect.String: decString,
|
|
}
|
|
|
|
// Indexed by gob types. tComplex will be added during type.init().
|
|
var decIgnoreOpMap = map[typeId]decOp{
|
|
tBool: ignoreUint,
|
|
tInt: ignoreUint,
|
|
tUint: ignoreUint,
|
|
tFloat: ignoreUint,
|
|
tBytes: ignoreUint8Array,
|
|
tString: ignoreUint8Array,
|
|
tComplex: ignoreTwoUints,
|
|
}
|
|
|
|
// decOpFor returns the decoding op for the base type under rt and
|
|
// the indirection count to reach it.
|
|
func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string, inProgress map[reflect.Type]*decOp) *decOp {
|
|
ut := userType(rt)
|
|
// If the type implements GobEncoder, we handle it without further processing.
|
|
if ut.externalDec != 0 {
|
|
return dec.gobDecodeOpFor(ut)
|
|
}
|
|
|
|
// If this type is already in progress, it's a recursive type (e.g. map[string]*T).
|
|
// Return the pointer to the op we're already building.
|
|
if opPtr := inProgress[rt]; opPtr != nil {
|
|
return opPtr
|
|
}
|
|
typ := ut.base
|
|
var op decOp
|
|
k := typ.Kind()
|
|
if int(k) < len(decOpTable) {
|
|
op = decOpTable[k]
|
|
}
|
|
if op == nil {
|
|
inProgress[rt] = &op
|
|
// Special cases
|
|
switch t := typ; t.Kind() {
|
|
case reflect.Array:
|
|
name = "element of " + name
|
|
elemId := dec.wireType[wireId].ArrayT.Elem
|
|
elemOp := dec.decOpFor(elemId, t.Elem(), name, inProgress)
|
|
ovfl := overflow(name)
|
|
helper := decArrayHelper[t.Elem().Kind()]
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.decodeArray(t, state, value, *elemOp, t.Len(), ovfl, helper)
|
|
}
|
|
|
|
case reflect.Map:
|
|
keyId := dec.wireType[wireId].MapT.Key
|
|
elemId := dec.wireType[wireId].MapT.Elem
|
|
keyOp := dec.decOpFor(keyId, t.Key(), "key of "+name, inProgress)
|
|
elemOp := dec.decOpFor(elemId, t.Elem(), "element of "+name, inProgress)
|
|
ovfl := overflow(name)
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.decodeMap(t, state, value, *keyOp, *elemOp, ovfl)
|
|
}
|
|
|
|
case reflect.Slice:
|
|
name = "element of " + name
|
|
if t.Elem().Kind() == reflect.Uint8 {
|
|
op = decUint8Slice
|
|
break
|
|
}
|
|
var elemId typeId
|
|
if tt, ok := builtinIdToType[wireId]; ok {
|
|
elemId = tt.(*sliceType).Elem
|
|
} else {
|
|
elemId = dec.wireType[wireId].SliceT.Elem
|
|
}
|
|
elemOp := dec.decOpFor(elemId, t.Elem(), name, inProgress)
|
|
ovfl := overflow(name)
|
|
helper := decSliceHelper[t.Elem().Kind()]
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.decodeSlice(state, value, *elemOp, ovfl, helper)
|
|
}
|
|
|
|
case reflect.Struct:
|
|
// Generate a closure that calls out to the engine for the nested type.
|
|
ut := userType(typ)
|
|
enginePtr, err := dec.getDecEnginePtr(wireId, ut)
|
|
if err != nil {
|
|
error_(err)
|
|
}
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
// indirect through enginePtr to delay evaluation for recursive structs.
|
|
dec.decodeStruct(*enginePtr, ut, value)
|
|
}
|
|
case reflect.Interface:
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.decodeInterface(t, state, value)
|
|
}
|
|
}
|
|
}
|
|
if op == nil {
|
|
errorf("decode can't handle type %s", rt)
|
|
}
|
|
return &op
|
|
}
|
|
|
|
// decIgnoreOpFor returns the decoding op for a field that has no destination.
|
|
func (dec *Decoder) decIgnoreOpFor(wireId typeId) decOp {
|
|
op, ok := decIgnoreOpMap[wireId]
|
|
if !ok {
|
|
if wireId == tInterface {
|
|
// Special case because it's a method: the ignored item might
|
|
// define types and we need to record their state in the decoder.
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.ignoreInterface(state)
|
|
}
|
|
return op
|
|
}
|
|
// Special cases
|
|
wire := dec.wireType[wireId]
|
|
switch {
|
|
case wire == nil:
|
|
errorf("bad data: undefined type %s", wireId.string())
|
|
case wire.ArrayT != nil:
|
|
elemId := wire.ArrayT.Elem
|
|
elemOp := dec.decIgnoreOpFor(elemId)
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.ignoreArray(state, elemOp, wire.ArrayT.Len)
|
|
}
|
|
|
|
case wire.MapT != nil:
|
|
keyId := dec.wireType[wireId].MapT.Key
|
|
elemId := dec.wireType[wireId].MapT.Elem
|
|
keyOp := dec.decIgnoreOpFor(keyId)
|
|
elemOp := dec.decIgnoreOpFor(elemId)
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.ignoreMap(state, keyOp, elemOp)
|
|
}
|
|
|
|
case wire.SliceT != nil:
|
|
elemId := wire.SliceT.Elem
|
|
elemOp := dec.decIgnoreOpFor(elemId)
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.ignoreSlice(state, elemOp)
|
|
}
|
|
|
|
case wire.StructT != nil:
|
|
// Generate a closure that calls out to the engine for the nested type.
|
|
enginePtr, err := dec.getIgnoreEnginePtr(wireId)
|
|
if err != nil {
|
|
error_(err)
|
|
}
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
// indirect through enginePtr to delay evaluation for recursive structs
|
|
state.dec.ignoreStruct(*enginePtr)
|
|
}
|
|
|
|
case wire.GobEncoderT != nil, wire.BinaryMarshalerT != nil, wire.TextMarshalerT != nil:
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
state.dec.ignoreGobDecoder(state)
|
|
}
|
|
}
|
|
}
|
|
if op == nil {
|
|
errorf("bad data: ignore can't handle type %s", wireId.string())
|
|
}
|
|
return op
|
|
}
|
|
|
|
// gobDecodeOpFor returns the op for a type that is known to implement
|
|
// GobDecoder.
|
|
func (dec *Decoder) gobDecodeOpFor(ut *userTypeInfo) *decOp {
|
|
rcvrType := ut.user
|
|
if ut.decIndir == -1 {
|
|
rcvrType = reflect.PtrTo(rcvrType)
|
|
} else if ut.decIndir > 0 {
|
|
for i := int8(0); i < ut.decIndir; i++ {
|
|
rcvrType = rcvrType.Elem()
|
|
}
|
|
}
|
|
var op decOp
|
|
op = func(i *decInstr, state *decoderState, value reflect.Value) {
|
|
// We now have the base type. We need its address if the receiver is a pointer.
|
|
if value.Kind() != reflect.Ptr && rcvrType.Kind() == reflect.Ptr {
|
|
value = value.Addr()
|
|
}
|
|
state.dec.decodeGobDecoder(ut, state, value)
|
|
}
|
|
return &op
|
|
}
|
|
|
|
// compatibleType asks: Are these two gob Types compatible?
|
|
// Answers the question for basic types, arrays, maps and slices, plus
|
|
// GobEncoder/Decoder pairs.
|
|
// Structs are considered ok; fields will be checked later.
|
|
func (dec *Decoder) compatibleType(fr reflect.Type, fw typeId, inProgress map[reflect.Type]typeId) bool {
|
|
if rhs, ok := inProgress[fr]; ok {
|
|
return rhs == fw
|
|
}
|
|
inProgress[fr] = fw
|
|
ut := userType(fr)
|
|
wire, ok := dec.wireType[fw]
|
|
// If wire was encoded with an encoding method, fr must have that method.
|
|
// And if not, it must not.
|
|
// At most one of the booleans in ut is set.
|
|
// We could possibly relax this constraint in the future in order to
|
|
// choose the decoding method using the data in the wireType.
|
|
// The parentheses look odd but are correct.
|
|
if (ut.externalDec == xGob) != (ok && wire.GobEncoderT != nil) ||
|
|
(ut.externalDec == xBinary) != (ok && wire.BinaryMarshalerT != nil) ||
|
|
(ut.externalDec == xText) != (ok && wire.TextMarshalerT != nil) {
|
|
return false
|
|
}
|
|
if ut.externalDec != 0 { // This test trumps all others.
|
|
return true
|
|
}
|
|
switch t := ut.base; t.Kind() {
|
|
default:
|
|
// chan, etc: cannot handle.
|
|
return false
|
|
case reflect.Bool:
|
|
return fw == tBool
|
|
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
|
|
return fw == tInt
|
|
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
|
|
return fw == tUint
|
|
case reflect.Float32, reflect.Float64:
|
|
return fw == tFloat
|
|
case reflect.Complex64, reflect.Complex128:
|
|
return fw == tComplex
|
|
case reflect.String:
|
|
return fw == tString
|
|
case reflect.Interface:
|
|
return fw == tInterface
|
|
case reflect.Array:
|
|
if !ok || wire.ArrayT == nil {
|
|
return false
|
|
}
|
|
array := wire.ArrayT
|
|
return t.Len() == array.Len && dec.compatibleType(t.Elem(), array.Elem, inProgress)
|
|
case reflect.Map:
|
|
if !ok || wire.MapT == nil {
|
|
return false
|
|
}
|
|
MapType := wire.MapT
|
|
return dec.compatibleType(t.Key(), MapType.Key, inProgress) && dec.compatibleType(t.Elem(), MapType.Elem, inProgress)
|
|
case reflect.Slice:
|
|
// Is it an array of bytes?
|
|
if t.Elem().Kind() == reflect.Uint8 {
|
|
return fw == tBytes
|
|
}
|
|
// Extract and compare element types.
|
|
var sw *sliceType
|
|
if tt, ok := builtinIdToType[fw]; ok {
|
|
sw, _ = tt.(*sliceType)
|
|
} else if wire != nil {
|
|
sw = wire.SliceT
|
|
}
|
|
elem := userType(t.Elem()).base
|
|
return sw != nil && dec.compatibleType(elem, sw.Elem, inProgress)
|
|
case reflect.Struct:
|
|
return true
|
|
}
|
|
}
|
|
|
|
// typeString returns a human-readable description of the type identified by remoteId.
|
|
func (dec *Decoder) typeString(remoteId typeId) string {
|
|
if t := idToType[remoteId]; t != nil {
|
|
// globally known type.
|
|
return t.string()
|
|
}
|
|
return dec.wireType[remoteId].string()
|
|
}
|
|
|
|
// compileSingle compiles the decoder engine for a non-struct top-level value, including
|
|
// GobDecoders.
|
|
func (dec *Decoder) compileSingle(remoteId typeId, ut *userTypeInfo) (engine *decEngine, err error) {
|
|
rt := ut.user
|
|
engine = new(decEngine)
|
|
engine.instr = make([]decInstr, 1) // one item
|
|
name := rt.String() // best we can do
|
|
if !dec.compatibleType(rt, remoteId, make(map[reflect.Type]typeId)) {
|
|
remoteType := dec.typeString(remoteId)
|
|
// Common confusing case: local interface type, remote concrete type.
|
|
if ut.base.Kind() == reflect.Interface && remoteId != tInterface {
|
|
return nil, errors.New("gob: local interface type " + name + " can only be decoded from remote interface type; received concrete type " + remoteType)
|
|
}
|
|
return nil, errors.New("gob: decoding into local type " + name + ", received remote type " + remoteType)
|
|
}
|
|
op := dec.decOpFor(remoteId, rt, name, make(map[reflect.Type]*decOp))
|
|
ovfl := errors.New(`value for "` + name + `" out of range`)
|
|
engine.instr[singletonField] = decInstr{*op, singletonField, nil, ovfl}
|
|
engine.numInstr = 1
|
|
return
|
|
}
|
|
|
|
// compileIgnoreSingle compiles the decoder engine for a non-struct top-level value that will be discarded.
|
|
func (dec *Decoder) compileIgnoreSingle(remoteId typeId) (engine *decEngine, err error) {
|
|
engine = new(decEngine)
|
|
engine.instr = make([]decInstr, 1) // one item
|
|
op := dec.decIgnoreOpFor(remoteId)
|
|
ovfl := overflow(dec.typeString(remoteId))
|
|
engine.instr[0] = decInstr{op, 0, nil, ovfl}
|
|
engine.numInstr = 1
|
|
return
|
|
}
|
|
|
|
// compileDec compiles the decoder engine for a value. If the value is not a struct,
|
|
// it calls out to compileSingle.
|
|
func (dec *Decoder) compileDec(remoteId typeId, ut *userTypeInfo) (engine *decEngine, err error) {
|
|
rt := ut.base
|
|
srt := rt
|
|
if srt.Kind() != reflect.Struct || ut.externalDec != 0 {
|
|
return dec.compileSingle(remoteId, ut)
|
|
}
|
|
var wireStruct *structType
|
|
// Builtin types can come from global pool; the rest must be defined by the decoder.
|
|
// Also we know we're decoding a struct now, so the client must have sent one.
|
|
if t, ok := builtinIdToType[remoteId]; ok {
|
|
wireStruct, _ = t.(*structType)
|
|
} else {
|
|
wire := dec.wireType[remoteId]
|
|
if wire == nil {
|
|
error_(errBadType)
|
|
}
|
|
wireStruct = wire.StructT
|
|
}
|
|
if wireStruct == nil {
|
|
errorf("type mismatch in decoder: want struct type %s; got non-struct", rt)
|
|
}
|
|
engine = new(decEngine)
|
|
engine.instr = make([]decInstr, len(wireStruct.Field))
|
|
seen := make(map[reflect.Type]*decOp)
|
|
// Loop over the fields of the wire type.
|
|
for fieldnum := 0; fieldnum < len(wireStruct.Field); fieldnum++ {
|
|
wireField := wireStruct.Field[fieldnum]
|
|
if wireField.Name == "" {
|
|
errorf("empty name for remote field of type %s", wireStruct.Name)
|
|
}
|
|
ovfl := overflow(wireField.Name)
|
|
// Find the field of the local type with the same name.
|
|
localField, present := srt.FieldByName(wireField.Name)
|
|
// TODO(r): anonymous names
|
|
if !present || !isExported(wireField.Name) {
|
|
op := dec.decIgnoreOpFor(wireField.Id)
|
|
engine.instr[fieldnum] = decInstr{op, fieldnum, nil, ovfl}
|
|
continue
|
|
}
|
|
if !dec.compatibleType(localField.Type, wireField.Id, make(map[reflect.Type]typeId)) {
|
|
errorf("wrong type (%s) for received field %s.%s", localField.Type, wireStruct.Name, wireField.Name)
|
|
}
|
|
op := dec.decOpFor(wireField.Id, localField.Type, localField.Name, seen)
|
|
engine.instr[fieldnum] = decInstr{*op, fieldnum, localField.Index, ovfl}
|
|
engine.numInstr++
|
|
}
|
|
return
|
|
}
|
|
|
|
// getDecEnginePtr returns the engine for the specified type.
|
|
func (dec *Decoder) getDecEnginePtr(remoteId typeId, ut *userTypeInfo) (enginePtr **decEngine, err error) {
|
|
rt := ut.user
|
|
decoderMap, ok := dec.decoderCache[rt]
|
|
if !ok {
|
|
decoderMap = make(map[typeId]**decEngine)
|
|
dec.decoderCache[rt] = decoderMap
|
|
}
|
|
if enginePtr, ok = decoderMap[remoteId]; !ok {
|
|
// To handle recursive types, mark this engine as underway before compiling.
|
|
enginePtr = new(*decEngine)
|
|
decoderMap[remoteId] = enginePtr
|
|
*enginePtr, err = dec.compileDec(remoteId, ut)
|
|
if err != nil {
|
|
delete(decoderMap, remoteId)
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// emptyStruct is the type we compile into when ignoring a struct value.
|
|
type emptyStruct struct{}
|
|
|
|
var emptyStructType = reflect.TypeOf(emptyStruct{})
|
|
|
|
// getDecEnginePtr returns the engine for the specified type when the value is to be discarded.
|
|
func (dec *Decoder) getIgnoreEnginePtr(wireId typeId) (enginePtr **decEngine, err error) {
|
|
var ok bool
|
|
if enginePtr, ok = dec.ignorerCache[wireId]; !ok {
|
|
// To handle recursive types, mark this engine as underway before compiling.
|
|
enginePtr = new(*decEngine)
|
|
dec.ignorerCache[wireId] = enginePtr
|
|
wire := dec.wireType[wireId]
|
|
if wire != nil && wire.StructT != nil {
|
|
*enginePtr, err = dec.compileDec(wireId, userType(emptyStructType))
|
|
} else {
|
|
*enginePtr, err = dec.compileIgnoreSingle(wireId)
|
|
}
|
|
if err != nil {
|
|
delete(dec.ignorerCache, wireId)
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// decodeValue decodes the data stream representing a value and stores it in value.
|
|
func (dec *Decoder) decodeValue(wireId typeId, value reflect.Value) {
|
|
defer catchError(&dec.err)
|
|
// If the value is nil, it means we should just ignore this item.
|
|
if !value.IsValid() {
|
|
dec.decodeIgnoredValue(wireId)
|
|
return
|
|
}
|
|
// Dereference down to the underlying type.
|
|
ut := userType(value.Type())
|
|
base := ut.base
|
|
var enginePtr **decEngine
|
|
enginePtr, dec.err = dec.getDecEnginePtr(wireId, ut)
|
|
if dec.err != nil {
|
|
return
|
|
}
|
|
value = decAlloc(value)
|
|
engine := *enginePtr
|
|
if st := base; st.Kind() == reflect.Struct && ut.externalDec == 0 {
|
|
if engine.numInstr == 0 && st.NumField() > 0 &&
|
|
dec.wireType[wireId] != nil && len(dec.wireType[wireId].StructT.Field) > 0 {
|
|
name := base.Name()
|
|
errorf("type mismatch: no fields matched compiling decoder for %s", name)
|
|
}
|
|
dec.decodeStruct(engine, ut, value)
|
|
} else {
|
|
dec.decodeSingle(engine, ut, value)
|
|
}
|
|
}
|
|
|
|
// decodeIgnoredValue decodes the data stream representing a value of the specified type and discards it.
|
|
func (dec *Decoder) decodeIgnoredValue(wireId typeId) {
|
|
var enginePtr **decEngine
|
|
enginePtr, dec.err = dec.getIgnoreEnginePtr(wireId)
|
|
if dec.err != nil {
|
|
return
|
|
}
|
|
wire := dec.wireType[wireId]
|
|
if wire != nil && wire.StructT != nil {
|
|
dec.ignoreStruct(*enginePtr)
|
|
} else {
|
|
dec.ignoreSingle(*enginePtr)
|
|
}
|
|
}
|
|
|
|
func init() {
|
|
var iop, uop decOp
|
|
switch reflect.TypeOf(int(0)).Bits() {
|
|
case 32:
|
|
iop = decInt32
|
|
uop = decUint32
|
|
case 64:
|
|
iop = decInt64
|
|
uop = decUint64
|
|
default:
|
|
panic("gob: unknown size of int/uint")
|
|
}
|
|
decOpTable[reflect.Int] = iop
|
|
decOpTable[reflect.Uint] = uop
|
|
|
|
// Finally uintptr
|
|
switch reflect.TypeOf(uintptr(0)).Bits() {
|
|
case 32:
|
|
uop = decUint32
|
|
case 64:
|
|
uop = decUint64
|
|
default:
|
|
panic("gob: unknown size of uintptr")
|
|
}
|
|
decOpTable[reflect.Uintptr] = uop
|
|
}
|
|
|
|
// Gob depends on being able to take the address
|
|
// of zeroed Values it creates, so use this wrapper instead
|
|
// of the standard reflect.Zero.
|
|
// Each call allocates once.
|
|
func allocValue(t reflect.Type) reflect.Value {
|
|
return reflect.New(t).Elem()
|
|
}
|