diff --git a/util/utf8reader.go b/util/utf8reader.go
deleted file mode 100644
index bd0b51b..0000000
--- a/util/utf8reader.go
+++ /dev/null
@@ -1,140 +0,0 @@
-// Copyright (c) 2015, B3log
-//
-// 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 util
-
-import (
-	"errors"
-	"io"
-	"unicode/utf8"
-)
-
-const (
-	defaultBufSize = 4096
-)
-
-// Reader represents a reader.
-type Reader struct {
-	buf  []byte
-	rd   io.Reader
-	r, w int
-	err  error
-}
-
-const minReadBufferSize = 16
-const maxConsecutiveEmptyReads = 100
-
-// NewReaderSize creates a reader with the specified buffer size.
-func NewReaderSize(rd io.Reader, size int) *Reader {
-	b, ok := rd.(*Reader)
-	if ok && len(b.buf) >= size {
-		return b
-	}
-	if size < minReadBufferSize {
-		size = minReadBufferSize
-	}
-	r := new(Reader)
-	r.reset(make([]byte, size), rd)
-	return r
-}
-
-// NewReader returns a new Reader whose buffer has the default size.
-func NewReader(rd io.Reader) *Reader {
-	return NewReaderSize(rd, defaultBufSize)
-}
-
-func (b *Reader) reset(buf []byte, r io.Reader) {
-	*b = Reader{
-		buf: buf,
-		rd:  r,
-	}
-}
-
-func (b *Reader) Read(buf []byte) (count int, err error) {
-	return
-}
-
-var errNegativeRead = errors.New("bufio: reader returned negative count from Read")
-
-// fill reads a new chunk into the buffer.
-func (b *Reader) fill() {
-	// Slide existing data to beginning.
-	if b.r > 0 {
-		copy(b.buf, b.buf[b.r:b.w])
-		b.w -= b.r
-		b.r = 0
-	}
-
-	if b.w >= len(b.buf) {
-		panic("bufio: tried to fill full buffer")
-	}
-
-	// Read new data: try a limited number of times.
-	for i := maxConsecutiveEmptyReads; i > 0; i-- {
-		n, err := b.rd.Read(b.buf[b.w:])
-		if n < 0 {
-			panic(errNegativeRead)
-		}
-		b.w += n
-		if err != nil {
-			b.err = err
-			return
-		}
-		if n > 0 {
-			return
-		}
-	}
-	b.err = io.ErrNoProgress
-}
-
-func (b *Reader) readErr() error {
-	err := b.err
-	b.err = nil
-	return err
-}
-
-// Buffered returns the size of buffered.
-func (b *Reader) Buffered() int { return b.w - b.r }
-
-// ReadData reads a line.
-func (b *Reader) ReadData() (line string, err error) {
-	if n := b.Buffered(); n < len(b.buf) {
-		b.fill()
-	}
-	if b.err != nil {
-		line = string(b.buf[b.r:b.w])
-		b.r = b.w
-		err = b.readErr()
-		return
-	}
-	index := b.w
-	for {
-		r, _ := utf8.DecodeLastRune(b.buf[b.r:index])
-		if r == utf8.RuneError {
-			index = index - 1
-			if index < b.r {
-				break
-			}
-		} else {
-			break
-		}
-	}
-	if index > b.r {
-		line = string(b.buf[b.r : b.r+index])
-		b.r += index
-	} else {
-		panic("no utf8 char found")
-	}
-	return
-}