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/* {{{ Copyright (c) Paul R. Tagliamonte <paultag@debian.org>, 2015
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE. }}} */
package deb // import "pault.ag/go/debian/deb"
import (
"fmt"
"io"
"path/filepath"
"strings"
"archive/tar"
"compress/bzip2"
"compress/gzip"
"github.com/kjk/lzma"
"github.com/klauspost/compress/zstd"
"github.com/xi2/xz"
)
// known compression types {{{
type DecompressorFunc func(io.Reader) (io.ReadCloser, error)
func gzipNewReader(r io.Reader) (io.ReadCloser, error) {
return gzip.NewReader(r)
}
func xzNewReader(r io.Reader) (io.ReadCloser, error) {
reader, err := xz.NewReader(r, 0)
if err != nil {
return nil, err
}
return io.NopCloser(reader), nil
}
func lzmaNewReader(r io.Reader) (io.ReadCloser, error) {
return lzma.NewReader(r), nil
}
func bzipNewReader(r io.Reader) (io.ReadCloser, error) {
return io.NopCloser(bzip2.NewReader(r)), nil
}
func zstdNewReader(r io.Reader) (io.ReadCloser, error) {
reader, err := zstd.NewReader(r)
if err != nil {
return nil, err
}
return io.NopCloser(reader), err
}
// For the authoritative list of supported file formats, see
// https://manpages.debian.org/unstable/dpkg-dev/deb.5
// zstd-compressed packages are not yet (08-2021) officially supported by Debian, but they
// are used by Ubuntu.
var knownCompressionAlgorithms = map[string]DecompressorFunc{
".gz": gzipNewReader,
".bz2": bzipNewReader,
".xz": xzNewReader,
".lzma": lzmaNewReader,
".zst": zstdNewReader,
}
// DecompressorFn returns a decompressing reader for the specified reader and its
// corresponding file extension ext.
func DecompressorFor(ext string) DecompressorFunc {
if fn, ok := knownCompressionAlgorithms[ext]; ok {
return fn
}
return func(r io.Reader) (io.ReadCloser, error) { return io.NopCloser(r), nil } // uncompressed file or unknown compression scheme
}
// }}}
// IsTarfile {{{
// Check to see if the given ArEntry is, in fact, a Tarfile. This method
// will return `true` for files that have `.tar.*` or `.tar` suffix.
//
// This will return `false` for the `debian-binary` file. If this method
// returns `true`, the `.Tarfile()` method will be around to give you a
// tar.Reader back.
func (e *ArEntry) IsTarfile() bool {
ext := filepath.Ext(e.Name)
return ext == ".tar" || filepath.Ext(strings.TrimSuffix(e.Name, ext)) == ".tar"
}
// }}}
// Tarfile {{{
// `.Tarfile()` will return a `tar.Reader` created from the ArEntry member
// to allow further inspection of the contents of the `.deb`.
func (e *ArEntry) Tarfile() (*tar.Reader, io.Closer, error) {
if !e.IsTarfile() {
return nil, nil, fmt.Errorf("%s appears to not be a tarfile", e.Name)
}
readCloser, err := DecompressorFor(filepath.Ext(e.Name))(e.Data)
if err != nil {
return nil, nil, err
}
return tar.NewReader(readCloser), readCloser, nil
}
// }}}
// vim: foldmethod=marker
|
