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varint.go
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/
varint.go
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// Extensions for Protocol Buffers to create more go like structures.
//
// Copyright (c) 2013, Vastech SA (PTY) LTD. All rights reserved.
// http://github.com/gogo/protobuf/gogoproto
//
// 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 pio
import (
"bufio"
"encoding/binary"
"errors"
"io"
"github.com/gogo/protobuf/proto"
)
var (
errSmallBuffer = errors.New("Buffer Too Small")
errLargeValue = errors.New("Value is Larger than 64 bits")
)
func NewWriter(w io.Writer) Writer {
return &varintWriter{w: w, lenBuf: make([]byte, binary.MaxVarintLen64)}
}
type varintWriter struct {
w io.Writer
lenBuf []byte
buffer []byte
}
func (w *varintWriter) WriteMsg(msg proto.Message) (_ int, err error) {
var data []byte
if m, ok := msg.(marshaler); ok {
n, ok := getSize(m)
if !ok {
data, err = proto.Marshal(msg)
if err != nil {
return 0, err
}
}
if n >= len(w.buffer) {
w.buffer = make([]byte, n)
}
_, err = m.MarshalTo(w.buffer)
if err != nil {
return 0, err
}
data = w.buffer[:n]
} else {
data, err = proto.Marshal(msg)
if err != nil {
return 0, err
}
}
length := uint64(len(data))
n := binary.PutUvarint(w.lenBuf, length)
n, err = w.w.Write(w.lenBuf[:n])
if err != nil {
return n, err
}
nd, err := w.w.Write(data)
return n + nd, err
}
func NewReader(r io.Reader, maxSize int) Reader {
return &varintReader{r: bufio.NewReader(r), maxSize: maxSize}
}
type varintReader struct {
r *bufio.Reader
buf []byte
maxSize int
readLen bool
len int
}
func (r *varintReader) readLength() error {
if r.readLen {
return nil
}
length64, err := binary.ReadUvarint(r.r)
if err != nil {
return err
}
length := int(length64)
r.readLen, r.len = true, length
return nil
}
func (r *varintReader) SkipMsg() error {
if err := r.readLength(); err != nil {
return err
}
if r.len < 0 {
return io.ErrShortBuffer
}
r.readLen = false
if _, err := r.r.Discard(r.len); err != nil {
return err
}
return nil
}
func (r *varintReader) ReadMsg(msg proto.Message) error {
if err := r.readLength(); err != nil {
return err
}
if r.len < 0 || r.len > r.maxSize {
return io.ErrShortBuffer
}
r.readLen = false
if len(r.buf) < r.len {
r.buf = make([]byte, r.len)
}
buf := r.buf[:r.len]
if _, err := io.ReadFull(r.r, buf); err != nil {
return err
}
return proto.Unmarshal(buf, msg)
}