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Diffstat (limited to 'vendor/github.com/matttproud/golang_protobuf_extensions/pbutil/decode.go')
-rw-r--r--vendor/github.com/matttproud/golang_protobuf_extensions/pbutil/decode.go75
1 files changed, 75 insertions, 0 deletions
diff --git a/vendor/github.com/matttproud/golang_protobuf_extensions/pbutil/decode.go b/vendor/github.com/matttproud/golang_protobuf_extensions/pbutil/decode.go
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index 000000000..258c0636a
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+++ b/vendor/github.com/matttproud/golang_protobuf_extensions/pbutil/decode.go
@@ -0,0 +1,75 @@
+// 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)
+}