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varint.go
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varint.go
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// Protocol Buffers for Go with Gadgets
//
// Copyright (c) 2013, The GoGo Authors. All rights reserved.
// http://github.com/gogo/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.
//
// 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 io
import (
"bufio"
"encoding/binary"
"errors"
"github.com/gogo/protobuf/proto"
"io"
)
var (
errSmallBuffer = errors.New("Buffer Too Small")
errLargeValue = errors.New("Value is Larger than 64 bits")
)
func NewDelimitedWriter(w io.Writer) WriteCloser {
return &varintWriter{w, make([]byte, binary.MaxVarintLen64), nil}
}
type varintWriter struct {
w io.Writer
lenBuf []byte
buffer []byte
}
func (this *varintWriter) WriteMsg(msg proto.Message) (err error) {
var data []byte
if m, ok := msg.(marshaler); ok {
n, ok := getSize(m)
if ok {
if n+binary.MaxVarintLen64 >= len(this.buffer) {
this.buffer = make([]byte, n+binary.MaxVarintLen64)
}
lenOff := binary.PutUvarint(this.buffer, uint64(n))
_, err = m.MarshalTo(this.buffer[lenOff:])
if err != nil {
return err
}
_, err = this.w.Write(this.buffer[:lenOff+n])
return err
}
}
// fallback
data, err = proto.Marshal(msg)
if err != nil {
return err
}
length := uint64(len(data))
n := binary.PutUvarint(this.lenBuf, length)
_, err = this.w.Write(this.lenBuf[:n])
if err != nil {
return err
}
_, err = this.w.Write(data)
return err
}
func (this *varintWriter) Close() error {
if closer, ok := this.w.(io.Closer); ok {
return closer.Close()
}
return nil
}
func NewDelimitedReader(r io.Reader, maxSize int) ReadCloser {
var closer io.Closer
if c, ok := r.(io.Closer); ok {
closer = c
}
return &varintReader{bufio.NewReader(r), nil, maxSize, closer}
}
type varintReader struct {
r *bufio.Reader
buf []byte
maxSize int
closer io.Closer
}
func (this *varintReader) ReadMsg(msg proto.Message) error {
length64, err := binary.ReadUvarint(this.r)
if err != nil {
return err
}
length := int(length64)
if length < 0 || length > this.maxSize {
return io.ErrShortBuffer
}
if len(this.buf) < length {
this.buf = make([]byte, length)
}
buf := this.buf[:length]
if _, err := io.ReadFull(this.r, buf); err != nil {
return err
}
return proto.Unmarshal(buf, msg)
}
func (this *varintReader) Close() error {
if this.closer != nil {
return this.closer.Close()
}
return nil
}