Golang程序
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// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2010 The Go Authors. All rights reserved.
// https://github.com/golang/protobuf
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package proto
/*
* Routines for decoding protocol buffer data to construct in-memory representations.
*/
import (
"errors"
"fmt"
"io"
)
// errOverflow is returned when an integer is too large to be represented.
var errOverflow = errors.New("proto: integer overflow")
// ErrInternalBadWireType is returned by generated code when an incorrect
// wire type is encountered. It does not get returned to user code.
var ErrInternalBadWireType = errors.New("proto: internal error: bad wiretype for oneof")
// DecodeVarint reads a varint-encoded integer from the slice.
// It returns the integer and the number of bytes consumed, or
// zero if there is not enough.
// This is the format for the
// int32, int64, uint32, uint64, bool, and enum
// protocol buffer types.
func DecodeVarint(buf []byte) (x uint64, n int) {
for shift := uint(0); shift < 64; shift += 7 {
if n >= len(buf) {
return 0, 0
}
b := uint64(buf[n])
n++
x |= (b & 0x7F) << shift
if (b & 0x80) == 0 {
return x, n
}
}
// The number is too large to represent in a 64-bit value.
return 0, 0
}
func (p *Buffer) decodeVarintSlow() (x uint64, err error) {
i := p.index
l := len(p.buf)
for shift := uint(0); shift < 64; shift += 7 {
if i >= l {
err = io.ErrUnexpectedEOF
return
}
b := p.buf[i]
i++
x |= (uint64(b) & 0x7F) << shift
if b < 0x80 {
p.index = i
return
}
}
// The number is too large to represent in a 64-bit value.
err = errOverflow
return
}
// DecodeVarint reads a varint-encoded integer from the Buffer.
// This is the format for the
// int32, int64, uint32, uint64, bool, and enum
// protocol buffer types.
func (p *Buffer) DecodeVarint() (x uint64, err error) {
i := p.index
buf := p.buf
if i >= len(buf) {
return 0, io.ErrUnexpectedEOF
} else if buf[i] < 0x80 {
p.index++
return uint64(buf[i]), nil
} else if len(buf)-i < 10 {
return p.decodeVarintSlow()
}
var b uint64
// we already checked the first byte
x = uint64(buf[i]) - 0x80
i++
b = uint64(buf[i])
i++
x += b << 7
if b&0x80 == 0 {
goto done
}
x -= 0x80 << 7
b = uint64(buf[i])
i++
x += b << 14
if b&0x80 == 0 {
goto done
}
x -= 0x80 << 14
b = uint64(buf[i])
i++
x += b << 21
if b&0x80 == 0 {
goto done
}
x -= 0x80 << 21
b = uint64(buf[i])
i++
x += b << 28
if b&0x80 == 0 {
goto done
}
x -= 0x80 << 28
b = uint64(buf[i])
i++
x += b << 35
if b&0x80 == 0 {
goto done
}
x -= 0x80 << 35
b = uint64(buf[i])
i++
x += b << 42
if b&0x80 == 0 {
goto done
}
x -= 0x80 << 42
b = uint64(buf[i])
i++
x += b << 49
if b&0x80 == 0 {
goto done
}
x -= 0x80 << 49
b = uint64(buf[i])
i++
x += b << 56
if b&0x80 == 0 {
goto done
}
x -= 0x80 << 56
b = uint64(buf[i])
i++
x += b << 63
if b&0x80 == 0 {
goto done
}
return 0, errOverflow
done:
p.index = i
return x, nil
}
// DecodeFixed64 reads a 64-bit integer from the Buffer.
// This is the format for the
// fixed64, sfixed64, and double protocol buffer types.
func (p *Buffer) DecodeFixed64() (x uint64, err error) {
// x, err already 0
i := p.index + 8
if i < 0 || i > len(p.buf) {
err = io.ErrUnexpectedEOF
return
}
p.index = i
x = uint64(p.buf[i-8])
x |= uint64(p.buf[i-7]) << 8
x |= uint64(p.buf[i-6]) << 16
x |= uint64(p.buf[i-5]) << 24
x |= uint64(p.buf[i-4]) << 32
x |= uint64(p.buf[i-3]) << 40
x |= uint64(p.buf[i-2]) << 48
x |= uint64(p.buf[i-1]) << 56
return
}
// DecodeFixed32 reads a 32-bit integer from the Buffer.
// This is the format for the
// fixed32, sfixed32, and float protocol buffer types.
func (p *Buffer) DecodeFixed32() (x uint64, err error) {
// x, err already 0
i := p.index + 4
if i < 0 || i > len(p.buf) {
err = io.ErrUnexpectedEOF
return
}
p.index = i
x = uint64(p.buf[i-4])
x |= uint64(p.buf[i-3]) << 8
x |= uint64(p.buf[i-2]) << 16
x |= uint64(p.buf[i-1]) << 24
return
}
// DecodeZigzag64 reads a zigzag-encoded 64-bit integer
// from the Buffer.
// This is the format used for the sint64 protocol buffer type.
func (p *Buffer) DecodeZigzag64() (x uint64, err error) {
x, err = p.DecodeVarint()
if err != nil {
return
}
x = (x >> 1) ^ uint64((int64(x&1)<<63)>>63)
return
}
// DecodeZigzag32 reads a zigzag-encoded 32-bit integer
// from the Buffer.
// This is the format used for the sint32 protocol buffer type.
func (p *Buffer) DecodeZigzag32() (x uint64, err error) {
x, err = p.DecodeVarint()
if err != nil {
return
}
x = uint64((uint32(x) >> 1) ^ uint32((int32(x&1)<<31)>>31))
return
}
// DecodeRawBytes reads a count-delimited byte buffer from the Buffer.
// This is the format used for the bytes protocol buffer
// type and for embedded messages.
func (p *Buffer) DecodeRawBytes(alloc bool) (buf []byte, err error) {
n, err := p.DecodeVarint()
if err != nil {
return nil, err
}
nb := int(n)
if nb < 0 {
return nil, fmt.Errorf("proto: bad byte length %d", nb)
}
end := p.index + nb
if end < p.index || end > len(p.buf) {
return nil, io.ErrUnexpectedEOF
}
if !alloc {
// todo: check if can get more uses of alloc=false
buf = p.buf[p.index:end]
p.index += nb
return
}
buf = make([]byte, nb)
copy(buf, p.buf[p.index:])
p.index += nb
return
}
// DecodeStringBytes reads an encoded string from the Buffer.
// This is the format used for the proto2 string type.
func (p *Buffer) DecodeStringBytes() (s string, err error) {
buf, err := p.DecodeRawBytes(false)
if err != nil {
return
}
return string(buf), nil
}
// Unmarshaler is the interface representing objects that can
// unmarshal themselves. The argument points to data that may be
// overwritten, so implementations should not keep references to the
// buffer.
// Unmarshal implementations should not clear the receiver.
// Any unmarshaled data should be merged into the receiver.
// Callers of Unmarshal that do not want to retain existing data
// should Reset the receiver before calling Unmarshal.
type Unmarshaler interface {
Unmarshal([]byte) error
}
// newUnmarshaler is the interface representing objects that can
// unmarshal themselves. The semantics are identical to Unmarshaler.
//
// This exists to support protoc-gen-go generated messages.
// The proto package will stop type-asserting to this interface in the future.
//
// DO NOT DEPEND ON THIS.
type newUnmarshaler interface {
XXX_Unmarshal([]byte) error
}
// Unmarshal parses the protocol buffer representation in buf and places the
// decoded result in pb. If the struct underlying pb does not match
// the data in buf, the results can be unpredictable.
//
// Unmarshal resets pb before starting to unmarshal, so any
// existing data in pb is always removed. Use UnmarshalMerge
// to preserve and append to existing data.
func Unmarshal(buf []byte, pb Message) error {
pb.Reset()
if u, ok := pb.(newUnmarshaler); ok {
return u.XXX_Unmarshal(buf)
}
if u, ok := pb.(Unmarshaler); ok {
return u.Unmarshal(buf)
}
return NewBuffer(buf).Unmarshal(pb)
}
// UnmarshalMerge parses the protocol buffer representation in buf and
// writes the decoded result to pb. If the struct underlying pb does not match
// the data in buf, the results can be unpredictable.
//
// UnmarshalMerge merges into existing data in pb.
// Most code should use Unmarshal instead.
func UnmarshalMerge(buf []byte, pb Message) error {
if u, ok := pb.(newUnmarshaler); ok {
return u.XXX_Unmarshal(buf)
}
if u, ok := pb.(Unmarshaler); ok {
// NOTE: The history of proto have unfortunately been inconsistent
// whether Unmarshaler should or should not implicitly clear itself.
// Some implementations do, most do not.
// Thus, calling this here may or may not do what people want.
//
// See https://github.com/golang/protobuf/issues/424
return u.Unmarshal(buf)
}
return NewBuffer(buf).Unmarshal(pb)
}
// DecodeMessage reads a count-delimited message from the Buffer.
func (p *Buffer) DecodeMessage(pb Message) error {
enc, err := p.DecodeRawBytes(false)
if err != nil {
return err
}
return NewBuffer(enc).Unmarshal(pb)
}
// DecodeGroup reads a tag-delimited group from the Buffer.
// StartGroup tag is already consumed. This function consumes
// EndGroup tag.
func (p *Buffer) DecodeGroup(pb Message) error {
b := p.buf[p.index:]
x, y := findEndGroup(b)
if x < 0 {
return io.ErrUnexpectedEOF
}
err := Unmarshal(b[:x], pb)
p.index += y
return err
}
// Unmarshal parses the protocol buffer representation in the
// Buffer and places the decoded result in pb. If the struct
// underlying pb does not match the data in the buffer, the results can be
// unpredictable.
//
// Unlike proto.Unmarshal, this does not reset pb before starting to unmarshal.
func (p *Buffer) Unmarshal(pb Message) error {
// If the object can unmarshal itself, let it.
if u, ok := pb.(newUnmarshaler); ok {
err := u.XXX_Unmarshal(p.buf[p.index:])
p.index = len(p.buf)
return err
}
if u, ok := pb.(Unmarshaler); ok {
// NOTE: The history of proto have unfortunately been inconsistent
// whether Unmarshaler should or should not implicitly clear itself.
// Some implementations do, most do not.
// Thus, calling this here may or may not do what people want.
//
// See https://github.com/golang/protobuf/issues/424
err := u.Unmarshal(p.buf[p.index:])
p.index = len(p.buf)
return err
}
// Slow workaround for messages that aren't Unmarshalers.
// This includes some hand-coded .pb.go files and
// bootstrap protos.
// TODO: fix all of those and then add Unmarshal to
// the Message interface. Then:
// The cast above and code below can be deleted.
// The old unmarshaler can be deleted.
// Clients can call Unmarshal directly (can already do that, actually).
var info InternalMessageInfo
err := info.Unmarshal(pb, p.buf[p.index:])
p.index = len(p.buf)
return err
}