2fd401c8f1
From-SVN: r181964
1280 lines
40 KiB
Go
1280 lines
40 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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package gob
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// TODO(rsc): When garbage collector changes, revisit
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// the allocations in this file that use unsafe.Pointer.
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import (
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"bytes"
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"errors"
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"io"
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"math"
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"reflect"
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"unsafe"
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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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// 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 *bytes.Buffer
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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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// 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 *bytes.Buffer) *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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_, err = r.Read(buf[0:width])
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if err != nil {
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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, p unsafe.Pointer)
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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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indir int // how many pointer indirections to reach the value in the struct
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offset uintptr // offset in the structure of the field to encode
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ovfl error // error message for overflow/underflow (for arrays, of the elements)
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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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// Walk the pointer hierarchy, allocating if we find a nil. Stop one before the end.
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func decIndirect(p unsafe.Pointer, indir int) unsafe.Pointer {
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for ; indir > 1; indir-- {
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if *(*unsafe.Pointer)(p) == nil {
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// Allocation required
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(unsafe.Pointer))
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}
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p = *(*unsafe.Pointer)(p)
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}
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return p
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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, p unsafe.Pointer) {
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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, p unsafe.Pointer) {
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state.decodeUint()
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state.decodeUint()
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}
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// decBool decodes a uint and stores it as a boolean through p.
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func decBool(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(bool))
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}
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p = *(*unsafe.Pointer)(p)
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}
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*(*bool)(p) = state.decodeUint() != 0
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}
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// decInt8 decodes an integer and stores it as an int8 through p.
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func decInt8(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int8))
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}
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p = *(*unsafe.Pointer)(p)
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}
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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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} else {
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*(*int8)(p) = int8(v)
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}
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}
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// decUint8 decodes an unsigned integer and stores it as a uint8 through p.
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func decUint8(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(uint8))
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}
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p = *(*unsafe.Pointer)(p)
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}
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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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} else {
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*(*uint8)(p) = uint8(v)
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}
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}
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// decInt16 decodes an integer and stores it as an int16 through p.
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func decInt16(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int16))
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}
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p = *(*unsafe.Pointer)(p)
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}
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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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} else {
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*(*int16)(p) = int16(v)
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}
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}
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// decUint16 decodes an unsigned integer and stores it as a uint16 through p.
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func decUint16(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(uint16))
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}
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p = *(*unsafe.Pointer)(p)
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}
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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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} else {
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*(*uint16)(p) = uint16(v)
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}
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}
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// decInt32 decodes an integer and stores it as an int32 through p.
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func decInt32(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int32))
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}
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p = *(*unsafe.Pointer)(p)
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}
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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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} else {
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*(*int32)(p) = int32(v)
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}
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}
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// decUint32 decodes an unsigned integer and stores it as a uint32 through p.
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func decUint32(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(uint32))
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}
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p = *(*unsafe.Pointer)(p)
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}
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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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} else {
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*(*uint32)(p) = uint32(v)
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}
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}
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// decInt64 decodes an integer and stores it as an int64 through p.
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func decInt64(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int64))
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}
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p = *(*unsafe.Pointer)(p)
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}
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*(*int64)(p) = int64(state.decodeInt())
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}
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// decUint64 decodes an unsigned integer and stores it as a uint64 through p.
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func decUint64(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(uint64))
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}
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p = *(*unsafe.Pointer)(p)
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}
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*(*uint64)(p) = uint64(state.decodeUint())
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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 floatFromBits(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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// storeFloat32 decodes an unsigned integer, treats it as a 32-bit floating-point
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// number, and stores it through p. It's a helper function for float32 and complex64.
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func storeFloat32(i *decInstr, state *decoderState, p unsafe.Pointer) {
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v := floatFromBits(state.decodeUint())
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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_(i.ovfl)
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} else {
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*(*float32)(p) = float32(v)
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}
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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 through p.
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func decFloat32(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(float32))
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}
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p = *(*unsafe.Pointer)(p)
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}
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storeFloat32(i, state, p)
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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 through p.
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func decFloat64(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(float64))
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}
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p = *(*unsafe.Pointer)(p)
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}
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*(*float64)(p) = floatFromBits(uint64(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 through p.
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// The real part comes first.
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func decComplex64(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(complex64))
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}
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p = *(*unsafe.Pointer)(p)
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}
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storeFloat32(i, state, p)
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storeFloat32(i, state, unsafe.Pointer(uintptr(p)+unsafe.Sizeof(float32(0))))
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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 through p.
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// The real part comes first.
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func decComplex128(i *decInstr, state *decoderState, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(complex128))
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}
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p = *(*unsafe.Pointer)(p)
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}
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real := floatFromBits(uint64(state.decodeUint()))
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imag := floatFromBits(uint64(state.decodeUint()))
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*(*complex128)(p) = complex(real, imag)
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}
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// decUint8Slice decodes a byte slice and stores through p 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, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new([]uint8))
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}
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p = *(*unsafe.Pointer)(p)
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}
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n := int(state.decodeUint())
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if n < 0 {
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errorf("negative length decoding []byte")
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}
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slice := (*[]uint8)(p)
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if cap(*slice) < n {
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*slice = make([]uint8, n)
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} else {
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*slice = (*slice)[0:n]
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}
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if _, err := state.b.Read(*slice); 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 through p 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, p unsafe.Pointer) {
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if i.indir > 0 {
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if *(*unsafe.Pointer)(p) == nil {
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*(*unsafe.Pointer)(p) = unsafe.Pointer(new(string))
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}
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p = *(*unsafe.Pointer)(p)
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}
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b := make([]byte, state.decodeUint())
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state.b.Read(b)
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// It would be a shame to do the obvious thing here,
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// *(*string)(p) = string(b)
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// because we've already allocated the storage and this would
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// allocate again and copy. So we do this ugly hack, which is even
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// even more unsafe than it looks as it depends the memory
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// representation of a string matching the beginning of the memory
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// representation of a byte slice (a byte slice is longer).
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*(*string)(p) = *(*string)(unsafe.Pointer(&b))
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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, p unsafe.Pointer) {
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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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// allocate makes sure storage is available for an object of underlying type rtyp
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// that is indir levels of indirection through p.
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func allocate(rtyp reflect.Type, p uintptr, indir int) uintptr {
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if indir == 0 {
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return p
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}
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up := unsafe.Pointer(p)
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if indir > 1 {
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up = decIndirect(up, indir)
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}
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if *(*unsafe.Pointer)(up) == nil {
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// Allocate object.
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*(*unsafe.Pointer)(up) = unsafe.New(rtyp)
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}
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return *(*uintptr)(up)
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}
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// decodeSingle decodes a top-level value that is not a struct and stores it through p.
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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, basep uintptr) (err error) {
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state := dec.newDecoderState(&dec.buf)
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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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if instr.indir != ut.indir {
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return errors.New("gob: internal error: inconsistent indirection")
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}
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ptr := unsafe.Pointer(basep) // offset will be zero
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if instr.indir > 1 {
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ptr = decIndirect(ptr, instr.indir)
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}
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instr.op(instr, state, ptr)
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dec.freeDecoderState(state)
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return nil
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}
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// decodeSingle decodes a top-level struct and stores it through p.
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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, p uintptr, indir int) {
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p = allocate(ut.base, p, indir)
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state := dec.newDecoderState(&dec.buf)
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state.fieldnum = -1
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basep := p
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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
|
|
}
|
|
fieldnum := state.fieldnum + delta
|
|
if fieldnum >= len(engine.instr) {
|
|
error_(errRange)
|
|
break
|
|
}
|
|
instr := &engine.instr[fieldnum]
|
|
p := unsafe.Pointer(basep + instr.offset)
|
|
if instr.indir > 1 {
|
|
p = decIndirect(p, instr.indir)
|
|
}
|
|
instr.op(instr, state, p)
|
|
state.fieldnum = fieldnum
|
|
}
|
|
dec.freeDecoderState(state)
|
|
}
|
|
|
|
// ignoreStruct discards the data for a struct with no destination.
|
|
func (dec *Decoder) ignoreStruct(engine *decEngine) {
|
|
state := dec.newDecoderState(&dec.buf)
|
|
state.fieldnum = -1
|
|
for state.b.Len() > 0 {
|
|
delta := int(state.decodeUint())
|
|
if delta < 0 {
|
|
errorf("ignore decode: corrupted data: negative delta")
|
|
}
|
|
if delta == 0 { // struct terminator is zero delta fieldnum
|
|
break
|
|
}
|
|
fieldnum := state.fieldnum + delta
|
|
if fieldnum >= len(engine.instr) {
|
|
error_(errRange)
|
|
}
|
|
instr := &engine.instr[fieldnum]
|
|
instr.op(instr, state, unsafe.Pointer(nil))
|
|
state.fieldnum = fieldnum
|
|
}
|
|
dec.freeDecoderState(state)
|
|
}
|
|
|
|
// ignoreSingle discards the data for a top-level non-struct value with no
|
|
// destination. It's used when calling Decode with a nil value.
|
|
func (dec *Decoder) ignoreSingle(engine *decEngine) {
|
|
state := dec.newDecoderState(&dec.buf)
|
|
state.fieldnum = singletonField
|
|
delta := int(state.decodeUint())
|
|
if delta != 0 {
|
|
errorf("decode: corrupted data: non-zero delta for singleton")
|
|
}
|
|
instr := &engine.instr[singletonField]
|
|
instr.op(instr, state, unsafe.Pointer(nil))
|
|
dec.freeDecoderState(state)
|
|
}
|
|
|
|
// decodeArrayHelper does the work for decoding arrays and slices.
|
|
func (dec *Decoder) decodeArrayHelper(state *decoderState, p uintptr, elemOp decOp, elemWid uintptr, length, elemIndir int, ovfl error) {
|
|
instr := &decInstr{elemOp, 0, elemIndir, 0, ovfl}
|
|
for i := 0; i < length; i++ {
|
|
up := unsafe.Pointer(p)
|
|
if elemIndir > 1 {
|
|
up = decIndirect(up, elemIndir)
|
|
}
|
|
elemOp(instr, state, up)
|
|
p += uintptr(elemWid)
|
|
}
|
|
}
|
|
|
|
// decodeArray decodes an array and stores it through p, that is, p points to the zeroth element.
|
|
// 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, p uintptr, elemOp decOp, elemWid uintptr, length, indir, elemIndir int, ovfl error) {
|
|
if indir > 0 {
|
|
p = allocate(atyp, p, 1) // All but the last level has been allocated by dec.Indirect
|
|
}
|
|
if n := state.decodeUint(); n != uint64(length) {
|
|
errorf("length mismatch in decodeArray")
|
|
}
|
|
dec.decodeArrayHelper(state, p, elemOp, elemWid, length, elemIndir, ovfl)
|
|
}
|
|
|
|
// decodeIntoValue is a helper for map decoding. Since maps are decoded using reflection,
|
|
// unlike the other items we can't use a pointer directly.
|
|
func decodeIntoValue(state *decoderState, op decOp, indir int, v reflect.Value, ovfl error) reflect.Value {
|
|
instr := &decInstr{op, 0, indir, 0, ovfl}
|
|
up := unsafe.Pointer(unsafeAddr(v))
|
|
if indir > 1 {
|
|
up = decIndirect(up, indir)
|
|
}
|
|
op(instr, state, up)
|
|
return v
|
|
}
|
|
|
|
// decodeMap decodes a map and stores its header through p.
|
|
// 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, p uintptr, keyOp, elemOp decOp, indir, keyIndir, elemIndir int, ovfl error) {
|
|
if indir > 0 {
|
|
p = allocate(mtyp, p, 1) // All but the last level has been allocated by dec.Indirect
|
|
}
|
|
up := unsafe.Pointer(p)
|
|
if *(*unsafe.Pointer)(up) == nil { // maps are represented as a pointer in the runtime
|
|
// Allocate map.
|
|
*(*unsafe.Pointer)(up) = unsafe.Pointer(reflect.MakeMap(mtyp).Pointer())
|
|
}
|
|
// Maps cannot be accessed by moving addresses around the way
|
|
// that slices etc. can. We must recover a full reflection value for
|
|
// the iteration.
|
|
v := reflect.ValueOf(unsafe.Unreflect(mtyp, unsafe.Pointer(p)))
|
|
n := int(state.decodeUint())
|
|
for i := 0; i < n; i++ {
|
|
key := decodeIntoValue(state, keyOp, keyIndir, allocValue(mtyp.Key()), ovfl)
|
|
elem := decodeIntoValue(state, elemOp, elemIndir, allocValue(mtyp.Elem()), ovfl)
|
|
v.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, 0, 0, errors.New("no error")}
|
|
for i := 0; i < length; i++ {
|
|
elemOp(instr, state, nil)
|
|
}
|
|
}
|
|
|
|
// 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, 0, 0, errors.New("no error")}
|
|
elemInstr := &decInstr{elemOp, 0, 0, 0, errors.New("no error")}
|
|
for i := 0; i < n; i++ {
|
|
keyOp(keyInstr, state, nil)
|
|
elemOp(elemInstr, state, nil)
|
|
}
|
|
}
|
|
|
|
// decodeSlice decodes a slice and stores the slice header through p.
|
|
// Slices are encoded as an unsigned length followed by the elements.
|
|
func (dec *Decoder) decodeSlice(atyp reflect.Type, state *decoderState, p uintptr, elemOp decOp, elemWid uintptr, indir, elemIndir int, ovfl error) {
|
|
n := int(uintptr(state.decodeUint()))
|
|
if indir > 0 {
|
|
up := unsafe.Pointer(p)
|
|
if *(*unsafe.Pointer)(up) == nil {
|
|
// Allocate the slice header.
|
|
*(*unsafe.Pointer)(up) = unsafe.Pointer(new([]unsafe.Pointer))
|
|
}
|
|
p = *(*uintptr)(up)
|
|
}
|
|
// Allocate storage for the slice elements, that is, the underlying array,
|
|
// if the existing slice does not have the capacity.
|
|
// Always write a header at p.
|
|
hdrp := (*reflect.SliceHeader)(unsafe.Pointer(p))
|
|
if hdrp.Cap < n {
|
|
hdrp.Data = uintptr(unsafe.NewArray(atyp.Elem(), n))
|
|
hdrp.Cap = n
|
|
}
|
|
hdrp.Len = n
|
|
dec.decodeArrayHelper(state, hdrp.Data, elemOp, elemWid, n, elemIndir, ovfl)
|
|
}
|
|
|
|
// 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()))
|
|
}
|
|
|
|
// setInterfaceValue sets an interface value to a concrete value,
|
|
// but first it checks that the assignment will succeed.
|
|
func setInterfaceValue(ivalue reflect.Value, value reflect.Value) {
|
|
if !value.Type().AssignableTo(ivalue.Type()) {
|
|
errorf("cannot assign value of type %s to %s", value.Type(), ivalue.Type())
|
|
}
|
|
ivalue.Set(value)
|
|
}
|
|
|
|
// decodeInterface decodes an interface value and stores it through p.
|
|
// 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, p uintptr, indir int) {
|
|
// Create a writable interface reflect.Value. We need one even for the nil case.
|
|
ivalue := allocValue(ityp)
|
|
// Read the name of the concrete type.
|
|
b := make([]byte, state.decodeUint())
|
|
state.b.Read(b)
|
|
name := string(b)
|
|
if name == "" {
|
|
// Copy the representation of the nil interface value to the target.
|
|
// This is horribly unsafe and special.
|
|
*(*[2]uintptr)(unsafe.Pointer(p)) = ivalue.InterfaceData()
|
|
return
|
|
}
|
|
// The concrete type must be registered.
|
|
typ, ok := nameToConcreteType[name]
|
|
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.
|
|
value := allocValue(typ)
|
|
dec.decodeValue(concreteId, value)
|
|
if dec.err != nil {
|
|
error_(dec.err)
|
|
}
|
|
// Allocate the destination interface value.
|
|
if indir > 0 {
|
|
p = allocate(ityp, p, 1) // All but the last level has been allocated by dec.Indirect
|
|
}
|
|
// Assign the concrete value to the interface.
|
|
// Tread carefully; it might not satisfy the interface.
|
|
setInterfaceValue(ivalue, value)
|
|
// Copy the representation of the interface value to the target.
|
|
// This is horribly unsafe and special.
|
|
*(*[2]uintptr)(unsafe.Pointer(p)) = ivalue.InterfaceData()
|
|
}
|
|
|
|
// 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.Next(int(state.decodeUint()))
|
|
}
|
|
|
|
// decodeGobDecoder decodes something implementing the GobDecoder interface.
|
|
// The data is encoded as a byte slice.
|
|
func (dec *Decoder) decodeGobDecoder(state *decoderState, v 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 a GobDecoder, so just call the method directly.
|
|
err = v.Interface().(GobDecoder).GobDecode(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, int) {
|
|
ut := userType(rt)
|
|
// If the type implements GobEncoder, we handle it without further processing.
|
|
if ut.isGobDecoder {
|
|
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, ut.indir
|
|
}
|
|
typ := ut.base
|
|
indir := ut.indir
|
|
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, elemIndir := dec.decOpFor(elemId, t.Elem(), name, inProgress)
|
|
ovfl := overflow(name)
|
|
op = func(i *decInstr, state *decoderState, p unsafe.Pointer) {
|
|
state.dec.decodeArray(t, state, uintptr(p), *elemOp, t.Elem().Size(), t.Len(), i.indir, elemIndir, ovfl)
|
|
}
|
|
|
|
case reflect.Map:
|
|
name = "element of " + name
|
|
keyId := dec.wireType[wireId].MapT.Key
|
|
elemId := dec.wireType[wireId].MapT.Elem
|
|
keyOp, keyIndir := dec.decOpFor(keyId, t.Key(), name, inProgress)
|
|
elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name, inProgress)
|
|
ovfl := overflow(name)
|
|
op = func(i *decInstr, state *decoderState, p unsafe.Pointer) {
|
|
up := unsafe.Pointer(p)
|
|
state.dec.decodeMap(t, state, uintptr(up), *keyOp, *elemOp, i.indir, keyIndir, elemIndir, 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, elemIndir := dec.decOpFor(elemId, t.Elem(), name, inProgress)
|
|
ovfl := overflow(name)
|
|
op = func(i *decInstr, state *decoderState, p unsafe.Pointer) {
|
|
state.dec.decodeSlice(t, state, uintptr(p), *elemOp, t.Elem().Size(), i.indir, elemIndir, ovfl)
|
|
}
|
|
|
|
case reflect.Struct:
|
|
// Generate a closure that calls out to the engine for the nested type.
|
|
enginePtr, err := dec.getDecEnginePtr(wireId, userType(typ))
|
|
if err != nil {
|
|
error_(err)
|
|
}
|
|
op = func(i *decInstr, state *decoderState, p unsafe.Pointer) {
|
|
// indirect through enginePtr to delay evaluation for recursive structs.
|
|
dec.decodeStruct(*enginePtr, userType(typ), uintptr(p), i.indir)
|
|
}
|
|
case reflect.Interface:
|
|
op = func(i *decInstr, state *decoderState, p unsafe.Pointer) {
|
|
state.dec.decodeInterface(t, state, uintptr(p), i.indir)
|
|
}
|
|
}
|
|
}
|
|
if op == nil {
|
|
errorf("decode can't handle type %s", rt)
|
|
}
|
|
return &op, indir
|
|
}
|
|
|
|
// 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, p unsafe.Pointer) {
|
|
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, p unsafe.Pointer) {
|
|
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, p unsafe.Pointer) {
|
|
state.dec.ignoreMap(state, keyOp, elemOp)
|
|
}
|
|
|
|
case wire.SliceT != nil:
|
|
elemId := wire.SliceT.Elem
|
|
elemOp := dec.decIgnoreOpFor(elemId)
|
|
op = func(i *decInstr, state *decoderState, p unsafe.Pointer) {
|
|
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, p unsafe.Pointer) {
|
|
// indirect through enginePtr to delay evaluation for recursive structs
|
|
state.dec.ignoreStruct(*enginePtr)
|
|
}
|
|
|
|
case wire.GobEncoderT != nil:
|
|
op = func(i *decInstr, state *decoderState, p unsafe.Pointer) {
|
|
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, int) {
|
|
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, p unsafe.Pointer) {
|
|
// Caller has gotten us to within one indirection of our value.
|
|
if i.indir > 0 {
|
|
if *(*unsafe.Pointer)(p) == nil {
|
|
*(*unsafe.Pointer)(p) = unsafe.New(ut.base)
|
|
}
|
|
}
|
|
// Now p is a pointer to the base type. Do we need to climb out to
|
|
// get to the receiver type?
|
|
var v reflect.Value
|
|
if ut.decIndir == -1 {
|
|
v = reflect.ValueOf(unsafe.Unreflect(rcvrType, unsafe.Pointer(&p)))
|
|
} else {
|
|
v = reflect.ValueOf(unsafe.Unreflect(rcvrType, p))
|
|
}
|
|
state.dec.decodeGobDecoder(state, v)
|
|
}
|
|
return &op, int(ut.indir)
|
|
|
|
}
|
|
|
|
// 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 fr is a GobDecoder, the wire type must be GobEncoder.
|
|
// And if fr is not a GobDecoder, the wire type must not be either.
|
|
if ut.isGobDecoder != (ok && wire.GobEncoderT != nil) { // the parentheses look odd but are correct.
|
|
return false
|
|
}
|
|
if ut.isGobDecoder { // 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 {
|
|
sw = dec.wireType[fw].SliceT
|
|
}
|
|
elem := userType(t.Elem()).base
|
|
return sw != nil && dec.compatibleType(elem, sw.Elem, inProgress)
|
|
case reflect.Struct:
|
|
return true
|
|
}
|
|
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)) {
|
|
return nil, errors.New("gob: wrong type received for local value " + name + ": " + dec.typeString(remoteId))
|
|
}
|
|
op, indir := 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, indir, 0, 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, 0, 0, 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.isGobDecoder {
|
|
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, 0, 0, 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, indir := dec.decOpFor(wireField.Id, localField.Type, localField.Name, seen)
|
|
engine.instr[fieldnum] = decInstr{*op, fieldnum, indir, uintptr(localField.Offset), 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.base
|
|
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 val.
|
|
func (dec *Decoder) decodeValue(wireId typeId, val reflect.Value) {
|
|
defer catchError(&dec.err)
|
|
// If the value is nil, it means we should just ignore this item.
|
|
if !val.IsValid() {
|
|
dec.decodeIgnoredValue(wireId)
|
|
return
|
|
}
|
|
// Dereference down to the underlying type.
|
|
ut := userType(val.Type())
|
|
base := ut.base
|
|
var enginePtr **decEngine
|
|
enginePtr, dec.err = dec.getDecEnginePtr(wireId, ut)
|
|
if dec.err != nil {
|
|
return
|
|
}
|
|
engine := *enginePtr
|
|
if st := base; st.Kind() == reflect.Struct && !ut.isGobDecoder {
|
|
if engine.numInstr == 0 && st.NumField() > 0 && 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, uintptr(unsafeAddr(val)), ut.indir)
|
|
} else {
|
|
dec.decodeSingle(engine, ut, uintptr(unsafeAddr(val)))
|
|
}
|
|
}
|
|
|
|
// 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 assumes it can call UnsafeAddr on any Value
|
|
// in order to get a pointer it can copy data from.
|
|
// Values that have just been created and do not point
|
|
// into existing structs or slices cannot be addressed,
|
|
// so simulate it by returning a pointer to a copy.
|
|
// Each call allocates once.
|
|
func unsafeAddr(v reflect.Value) uintptr {
|
|
if v.CanAddr() {
|
|
return v.UnsafeAddr()
|
|
}
|
|
x := reflect.New(v.Type()).Elem()
|
|
x.Set(v)
|
|
return x.UnsafeAddr()
|
|
}
|
|
|
|
// 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()
|
|
}
|