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reader.go
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/
reader.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.
//
// Modified from original GoGo Protobuf to not buffer the reader.
package protoio
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"github.com/cosmos/gogoproto/proto"
)
// NewDelimitedReader reads varint-delimited Protobuf messages from a reader.
// Unlike the gogoproto NewDelimitedReader, this does not buffer the reader,
// which may cause poor performance but is necessary when only reading single
// messages (e.g. in the p2p package). It also returns the number of bytes
// read, which is necessary for the p2p package.
func NewDelimitedReader(r io.Reader, maxSize int) ReadCloser {
var closer io.Closer
if c, ok := r.(io.Closer); ok {
closer = c
}
return &varintReader{r, nil, maxSize, closer}
}
type varintReader struct {
r io.Reader
buf []byte
maxSize int
closer io.Closer
}
func (r *varintReader) ReadMsg(msg proto.Message) (int, error) {
// ReadUvarint needs an io.ByteReader, and we also need to keep track of the
// number of bytes read, so we use our own byteReader. This can't be
// buffered, so the caller should pass a buffered io.Reader to avoid poor
// performance.
byteReader := newByteReader(r.r)
l, err := binary.ReadUvarint(byteReader)
n := byteReader.bytesRead
if err != nil {
return n, err
}
// Make sure length doesn't overflow the native int size (e.g. 32-bit),
// and that the returned sum of n+length doesn't overflow either.
length := int(l)
if l >= uint64(^uint(0)>>1) || length < 0 || n+length < 0 {
return n, fmt.Errorf("invalid out-of-range message length %v", l)
}
if length > r.maxSize {
return n, fmt.Errorf("message exceeds max size (%v > %v)", length, r.maxSize)
}
if len(r.buf) < length {
r.buf = make([]byte, length)
}
buf := r.buf[:length]
nr, err := io.ReadFull(r.r, buf)
n += nr
if err != nil {
return n, err
}
return n, proto.Unmarshal(buf, msg)
}
func (r *varintReader) Close() error {
if r.closer != nil {
return r.closer.Close()
}
return nil
}
func UnmarshalDelimited(data []byte, msg proto.Message) error {
_, err := NewDelimitedReader(bytes.NewReader(data), len(data)).ReadMsg(msg)
return err
}