fix read from io.Reader, n == 0 is not eof

jsoniter.go

@@ -73,20 +73,25 @@ func (iter *Iterator) readByte() (ret byte) {
 			iter.Error = io.EOF
 			return
 		}
+		for {
 			n, err := iter.reader.Read(iter.buf)
+			if n == 0 {
 				if err != nil {
 					iter.Error = err
 					return
+				} else {
+					// n == 0, err == nil is not EOF
+					continue
 				}
-		if n == 0 {
+			} else {
-			iter.Error = io.EOF
-			return
-		}
 				iter.head = 0
 				iter.tail = n
+				break
+			}
+		}
 	}
 	ret = iter.buf[iter.head]
-	iter.head += 1
+	iter.head++
 	return ret
 }