You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
76 lines
2.8 KiB
76 lines
2.8 KiB
7 years ago
|
// Copyright 2013 Matt T. Proud
|
||
|
|
//
|
||
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
// you may not use this file except in compliance with the License.
|
||
|
|
// You may obtain a copy of the License at
|
||
|
|
//
|
||
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
//
|
||
|
|
// Unless required by applicable law or agreed to in writing, software
|
||
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
// See the License for the specific language governing permissions and
|
||
|
|
// limitations under the License.
|
||
|
|
|
||
|
|
package pbutil
|
||
|
|
|
||
|
|
import (
|
||
|
|
"encoding/binary"
|
||
|
|
"errors"
|
||
|
|
"io"
|
||
|
|
|
||
|
|
"github.com/golang/protobuf/proto"
|
||
|
|
)
|
||
|
|
|
||
|
|
var errInvalidVarint = errors.New("invalid varint32 encountered")
|
||
|
|
|
||
|
|
// ReadDelimited decodes a message from the provided length-delimited stream,
|
||
|
|
// where the length is encoded as 32-bit varint prefix to the message body.
|
||
|
|
// It returns the total number of bytes read and any applicable error. This is
|
||
|
|
// roughly equivalent to the companion Java API's
|
||
|
|
// MessageLite#parseDelimitedFrom. As per the reader contract, this function
|
||
|
|
// calls r.Read repeatedly as required until exactly one message including its
|
||
|
|
// prefix is read and decoded (or an error has occurred). The function never
|
||
|
|
// reads more bytes from the stream than required. The function never returns
|
||
|
|
// an error if a message has been read and decoded correctly, even if the end
|
||
|
|
// of the stream has been reached in doing so. In that case, any subsequent
|
||
|
|
// calls return (0, io.EOF).
|
||
|
|
func ReadDelimited(r io.Reader, m proto.Message) (n int, err error) {
|
||
|
|
// Per AbstractParser#parsePartialDelimitedFrom with
|
||
|
|
// CodedInputStream#readRawVarint32.
|
||
|
|
var headerBuf [binary.MaxVarintLen32]byte
|
||
|
|
var bytesRead, varIntBytes int
|
||
|
|
var messageLength uint64
|
||
|
|
for varIntBytes == 0 { // i.e. no varint has been decoded yet.
|
||
|
|
if bytesRead >= len(headerBuf) {
|
||
|
|
return bytesRead, errInvalidVarint
|
||
|
|
}
|
||
|
|
// We have to read byte by byte here to avoid reading more bytes
|
||
|
|
// than required. Each read byte is appended to what we have
|
||
|
|
// read before.
|
||
|
|
newBytesRead, err := r.Read(headerBuf[bytesRead : bytesRead+1])
|
||
|
|
if newBytesRead == 0 {
|
||
|
|
if err != nil {
|
||
|
|
return bytesRead, err
|
||
|
|
}
|
||
|
|
// A Reader should not return (0, nil), but if it does,
|
||
|
|
// it should be treated as no-op (according to the
|
||
|
|
// Reader contract). So let's go on...
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
bytesRead += newBytesRead
|
||
|
|
// Now present everything read so far to the varint decoder and
|
||
|
|
// see if a varint can be decoded already.
|
||
|
|
messageLength, varIntBytes = proto.DecodeVarint(headerBuf[:bytesRead])
|
||
|
|
}
|
||
|
|
|
||
|
|
messageBuf := make([]byte, messageLength)
|
||
|
|
newBytesRead, err := io.ReadFull(r, messageBuf)
|
||
|
|
bytesRead += newBytesRead
|
||
|
|
if err != nil {
|
||
|
|
return bytesRead, err
|
||
|
|
}
|
||
|
|
|
||
|
|
return bytesRead, proto.Unmarshal(messageBuf, m)
|
||
|
|
}
|