func TestGetExtensionStability(t *testing.T) {
check := func(m *pb.MyMessage) bool {
ext1, err := proto.GetExtension(m, pb.E_Ext_More)
if err != nil {
t.Fatalf("GetExtension() failed: %s", err)
}
ext2, err := proto.GetExtension(m, pb.E_Ext_More)
if err != nil {
t.Fatalf("GetExtension() failed: %s", err)
}
return ext1 == ext2
}
msg := &pb.MyMessage{Count: proto.Int32(4)}
ext0 := &pb.Ext{}
if err := proto.SetExtension(msg, pb.E_Ext_More, ext0); err != nil {
t.Fatalf("Could not set ext1: %s", ext0)
}
if !check(msg) {
t.Errorf("GetExtension() not stable before marshaling")
}
bb, err := proto.Marshal(msg)
if err != nil {
t.Fatalf("Marshal() failed: %s", err)
}
msg1 := &pb.MyMessage{}
err = proto.Unmarshal(bb, msg1)
if err != nil {
t.Fatalf("Unmarshal() failed: %s", err)
}
if !check(msg1) {
t.Errorf("GetExtension() not stable after unmarshaling")
}
}
// 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.
headerBuf := make([]byte, binary.MaxVarintLen32)
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)
}
