mirror of https://github.com/go-gitea/gitea.git
118 lines
2.7 KiB
Go
118 lines
2.7 KiB
Go
// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package xz
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import (
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"errors"
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"fmt"
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"io"
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"github.com/ulikunitz/xz/lzma"
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)
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// LZMA filter constants.
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const (
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lzmaFilterID = 0x21
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lzmaFilterLen = 3
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)
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// lzmaFilter declares the LZMA2 filter information stored in an xz
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// block header.
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type lzmaFilter struct {
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dictCap int64
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}
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// String returns a representation of the LZMA filter.
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func (f lzmaFilter) String() string {
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return fmt.Sprintf("LZMA dict cap %#x", f.dictCap)
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}
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// id returns the ID for the LZMA2 filter.
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func (f lzmaFilter) id() uint64 { return lzmaFilterID }
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// MarshalBinary converts the lzmaFilter in its encoded representation.
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func (f lzmaFilter) MarshalBinary() (data []byte, err error) {
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c := lzma.EncodeDictCap(f.dictCap)
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return []byte{lzmaFilterID, 1, c}, nil
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}
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// UnmarshalBinary unmarshals the given data representation of the LZMA2
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// filter.
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func (f *lzmaFilter) UnmarshalBinary(data []byte) error {
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if len(data) != lzmaFilterLen {
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return errors.New("xz: data for LZMA2 filter has wrong length")
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}
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if data[0] != lzmaFilterID {
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return errors.New("xz: wrong LZMA2 filter id")
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}
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if data[1] != 1 {
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return errors.New("xz: wrong LZMA2 filter size")
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}
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dc, err := lzma.DecodeDictCap(data[2])
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if err != nil {
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return errors.New("xz: wrong LZMA2 dictionary size property")
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}
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f.dictCap = dc
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return nil
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}
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// reader creates a new reader for the LZMA2 filter.
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func (f lzmaFilter) reader(r io.Reader, c *ReaderConfig) (fr io.Reader,
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err error) {
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config := new(lzma.Reader2Config)
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if c != nil {
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config.DictCap = c.DictCap
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}
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dc := int(f.dictCap)
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if dc < 1 {
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return nil, errors.New("xz: LZMA2 filter parameter " +
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"dictionary capacity overflow")
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}
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if dc > config.DictCap {
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config.DictCap = dc
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}
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fr, err = config.NewReader2(r)
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if err != nil {
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return nil, err
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}
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return fr, nil
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}
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// writeCloser creates a io.WriteCloser for the LZMA2 filter.
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func (f lzmaFilter) writeCloser(w io.WriteCloser, c *WriterConfig,
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) (fw io.WriteCloser, err error) {
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config := new(lzma.Writer2Config)
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if c != nil {
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*config = lzma.Writer2Config{
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Properties: c.Properties,
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DictCap: c.DictCap,
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BufSize: c.BufSize,
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Matcher: c.Matcher,
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}
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}
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dc := int(f.dictCap)
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if dc < 1 {
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return nil, errors.New("xz: LZMA2 filter parameter " +
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"dictionary capacity overflow")
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}
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if dc > config.DictCap {
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config.DictCap = dc
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}
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fw, err = config.NewWriter2(w)
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if err != nil {
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return nil, err
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}
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return fw, nil
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}
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// last returns true, because an LZMA2 filter must be the last filter in
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// the filter list.
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func (f lzmaFilter) last() bool { return true }
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