[#149] client: Fill buffer completely when reading stream data

In previous implementation all `Read` methods read single response
per-call, so buffer could be incompletely filled w/o an error. In order
to follow `io.Reader` docs we need to continue filling the buffer while
it is possible.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

client/object_get.go

@@ -166,14 +166,20 @@ func (x *ObjectReader) readChunk(buf []byte) (int, bool) {
 		return read, true
 	}
 
+	var ok bool
+	var part v2object.GetObjectPart
+	var chunk []byte
+	var lastRead int
+
+	for {
 		// receive next message
-	ok := x.ctxCall.readResponse()
+		ok = x.ctxCall.readResponse()
 		if !ok {
 			return read, false
 		}
 
 		// get chunk part message
-	part := x.bodyResp.GetObjectPart()
+		part = x.bodyResp.GetObjectPart()
 
 		var partChunk *v2object.GetObjectPartChunk
 
@@ -184,16 +190,23 @@ func (x *ObjectReader) readChunk(buf []byte) (int, bool) {
 		}
 
 		// read new chunk
-	chunk := partChunk.GetChunk()
+		chunk = partChunk.GetChunk()
+		if len(chunk) == 0 {
+			// just skip empty chunks since they are not prohibited by protocol
+			continue
+		}
 
-	tailOffset := copy(buf[read:], chunk)
+		lastRead = copy(buf[read:], chunk)
 
-	read += tailOffset
+		read += lastRead
 
+		if read == len(buf) {
 			// save the tail
-	x.tailPayload = append(x.tailPayload, chunk[tailOffset:]...)
+			x.tailPayload = append(x.tailPayload, chunk[lastRead:]...)
 
 			return read, true
+		}
+	}
 }
 
 // ReadChunk reads another chunk of the object payload. Works similar to
@@ -593,15 +606,19 @@ func (x *ObjectRangeReader) readChunk(buf []byte) (int, bool) {
 		return read, true
 	}
 
+	var ok bool
+	var partChunk *v2object.GetRangePartChunk
+	var chunk []byte
+	var lastRead int
+
+	for {
 		// receive next message
-	ok := x.ctxCall.readResponse()
+		ok = x.ctxCall.readResponse()
 		if !ok {
 			return read, false
 		}
 
 		// get chunk message
-	var partChunk *v2object.GetRangePartChunk
-
 		switch v := x.bodyResp.GetRangePart().(type) {
 		default:
 			x.ctxCall.err = fmt.Errorf("unexpected message received: %T", v)
@@ -613,17 +630,23 @@ func (x *ObjectRangeReader) readChunk(buf []byte) (int, bool) {
 			partChunk = v
 		}
 
-	// read new chunk
+		chunk = partChunk.GetChunk()
-	chunk := partChunk.GetChunk()
+		if len(chunk) == 0 {
+			// just skip empty chunks since they are not prohibited by protocol
+			continue
+		}
 
-	tailOffset := copy(buf[read:], chunk)
+		lastRead = copy(buf[read:], chunk)
 
-	read += tailOffset
+		read += lastRead
 
+		if read == len(buf) {
 			// save the tail
-	x.tailPayload = append(x.tailPayload, chunk[tailOffset:]...)
+			x.tailPayload = append(x.tailPayload, chunk[lastRead:]...)
 
 			return read, true
+		}
+	}
 }
 
 // ReadChunk reads another chunk of the object payload range.

client/object_search.go

@@ -166,13 +166,13 @@ func (x *ObjectListReader) Read(buf []oid.ID) (int, bool) {
 
 		read += ln
 
-		// save the tail and break
+		if read == len(buf) {
+			// save the tail
 			x.tail = append(x.tail, ids[ln:]...)
 
-		break
-	}
-
 			return read, true
+		}
+	}
 }
 
 // Close ends reading list of the matched objects and returns the result of the operation