forked from chen-keinan/go-archive-extractor
/
compression.go
246 lines (216 loc) · 5.01 KB
/
compression.go
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package compression
import (
"bytes"
"compress/bzip2"
"compress/flate"
"compress/gzip"
"compress/lzw"
"compress/zlib"
"errors"
"github.com/klauspost/compress/zstd"
"github.com/ulikunitz/xz"
"github.com/ulikunitz/xz/lzma"
"io"
"io/ioutil"
"os"
"path/filepath"
)
const (
bz2Ext = ".bz2"
tbz2Ext = ".tbz2"
gzExt = ".gz"
tgzExt = ".tgz"
lzwExt = ".Z"
inflExt = ".infl"
zlibExt = ".xp3"
xzExt = ".xz"
txzExt = ".txz"
lzmaExt = ".lzma"
tlzmaExt = ".tlzma"
zstdExt = ".zst"
maxMagicBytes = 6 // 6 is the biggest used here (xz)
)
var (
gzipMagic = []byte{0x1F, 0x8B}
bz2Magic = []byte{0x42, 0x5A, 0x68}
xzMagic = []byte{0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00}
lzmaMagic = []byte{0x5D, 0x00, 0x00}
zstdMagic = []byte{0x28, 0xB5, 0x2F, 0xFD}
)
func NewReaderSkipBytes(filePath string, skip int64) (io.ReadCloser, bool, error) {
return newReader(&fileArgs{path: filePath, skipBytes: skip})
}
func NewReader(filePath string) (io.ReadCloser, bool, error) {
return newReader(&fileArgs{path: filePath})
}
type fileArgs struct {
path string
skipBytes int64
}
func (fa *fileArgs) open() (*os.File, error) {
f, err := os.Open(fa.path)
if err != nil {
return nil, err
}
if fa.skipBytes > 0 {
_, err := f.Seek(fa.skipBytes, io.SeekStart)
if err != nil {
f.Close()
return nil, err
}
}
return f, nil
}
func newReader(fa *fileArgs) (reader io.ReadCloser, isCompressed bool, err error) {
isCompressed = true
ext := filepath.Ext(fa.path)
//these types has no defined magic bytes
switch ext {
case lzwExt:
reader, err = initReader(fa, lzwReader)
return
case inflExt:
reader, err = initReader(fa, flateReader)
return
case zlibExt:
reader, err = initReader(fa, zlibReader)
return
}
// if possible init by magic bytes
if magic, magicErr := getMagicBytes(fa); magicErr == nil {
switch {
case bytes.HasPrefix(magic, bz2Magic):
reader, err = initReader(fa, bz2Reader)
return
case bytes.HasPrefix(magic, gzipMagic):
reader, err = initReader(fa, gzipReader)
return
case bytes.HasPrefix(magic, xzMagic):
reader, err = initReader(fa, xzReader)
return
case bytes.HasPrefix(magic, lzmaMagic):
reader, err = initReader(fa, lzmaReader)
return
case bytes.HasPrefix(magic, zstdMagic):
reader, err = initReader(fa, zstdReader)
return
}
}
// fallback to init by extension
switch ext {
case bz2Ext, tbz2Ext:
reader, err = initReader(fa, bz2Reader)
return
case gzExt, tgzExt:
reader, err = initReader(fa, gzipReader)
return
case xzExt, txzExt:
reader, err = initReader(fa, xzReader)
return
case lzmaExt, tlzmaExt:
reader, err = initReader(fa, lzmaReader)
return
case zstdExt:
reader, err = initReader(fa, zstdReader)
return
default:
// no compression format found
isCompressed = false
reader, err = initReader(fa, fileReader)
return
}
}
func getMagicBytes(fa *fileArgs) ([]byte, error) {
f, err := fa.open()
if err != nil {
return nil, err
}
defer f.Close()
b := make([]byte, maxMagicBytes)
if _, err = f.Read(b); err != nil {
return nil, err
}
return b, nil
}
// compression readers
type cReader struct {
reader io.ReadCloser
file *os.File
}
func (cr *cReader) Read(p []byte) (int, error) {
return cr.reader.Read(p)
}
func (cr *cReader) Close() error {
if err := cr.file.Close(); err != nil {
return err
}
if err := cr.reader.Close(); err != nil {
return err
}
return nil
}
func initReader(fa *fileArgs, getReader func(io.Reader) (io.ReadCloser, error)) (io.ReadCloser, error) {
f, err := fa.open()
if err != nil {
return nil, err
}
r, err := getReader(f)
if err != nil {
f.Close()
return nil, &ErrGetReader{err}
}
return &cReader{reader: r, file: f}, nil
}
type ErrGetReader struct {
err error
}
func (e *ErrGetReader) Error() string {
return e.err.Error()
}
func IsGetReaderError(err error) bool {
for e := err; e != nil; e = errors.Unwrap(e) {
if _, ok := e.(*ErrGetReader); ok {
return true
}
}
return false
}
func bz2Reader(reader io.Reader) (io.ReadCloser, error) {
return ioutil.NopCloser(bzip2.NewReader(reader)), nil
}
func flateReader(reader io.Reader) (io.ReadCloser, error) {
return flate.NewReader(reader), nil
}
func gzipReader(reader io.Reader) (io.ReadCloser, error) {
return gzip.NewReader(reader)
}
func lzwReader(reader io.Reader) (io.ReadCloser, error) {
return lzw.NewReader(reader, lzw.LSB, 100), nil
}
func zlibReader(reader io.Reader) (io.ReadCloser, error) {
return zlib.NewReader(reader)
}
func xzReader(reader io.Reader) (io.ReadCloser, error) {
r, err := xz.NewReader(reader)
if err != nil {
return nil, err
}
return ioutil.NopCloser(r), nil
}
func lzmaReader(reader io.Reader) (io.ReadCloser, error) {
r, err := lzma.NewReader(reader)
if err != nil {
return nil, err
}
return ioutil.NopCloser(r), nil
}
func zstdReader(reader io.Reader) (io.ReadCloser, error) {
r, err := zstd.NewReader(reader)
if err != nil {
return nil, err
}
return ioutil.NopCloser(r), nil
}
func fileReader(reader io.Reader) (io.ReadCloser, error) {
return ioutil.NopCloser(reader), nil
}