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130 lines
3.5 KiB
130 lines
3.5 KiB
package archiver
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import (
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"fmt"
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"io"
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"strings"
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"github.com/pierrec/lz4/v4"
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)
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// TarLz4 facilitates lz4 compression
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// (https://github.com/lz4/lz4/tree/master/doc)
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// of tarball archives.
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type TarLz4 struct {
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*Tar
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// The compression level to use when writing.
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// Minimum 0 (fast compression), maximum 12
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// (most space savings).
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CompressionLevel int
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}
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// CheckExt ensures the file extension matches the format.
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func (*TarLz4) CheckExt(filename string) error {
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if !strings.HasSuffix(filename, ".tar.lz4") &&
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!strings.HasSuffix(filename, ".tlz4") {
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return fmt.Errorf("filename must have a .tar.lz4 or .tlz4 extension")
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}
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return nil
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}
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// Archive creates a compressed tar file at destination
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// containing the files listed in sources. The destination
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// must end with ".tar.lz4" or ".tlz4". File paths can be
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// those of regular files or directories; directories will
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// be recursively added.
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func (tlz4 *TarLz4) Archive(sources []string, destination string) error {
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err := tlz4.CheckExt(destination)
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if err != nil {
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return fmt.Errorf("output %s", err.Error())
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}
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tlz4.wrapWriter()
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return tlz4.Tar.Archive(sources, destination)
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}
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// Unarchive unpacks the compressed tarball at
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// source to destination. Destination will be
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// treated as a folder name.
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func (tlz4 *TarLz4) Unarchive(source, destination string) error {
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tlz4.wrapReader()
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return tlz4.Tar.Unarchive(source, destination)
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}
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// Walk calls walkFn for each visited item in archive.
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func (tlz4 *TarLz4) Walk(archive string, walkFn WalkFunc) error {
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tlz4.wrapReader()
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return tlz4.Tar.Walk(archive, walkFn)
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}
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// Create opens tlz4 for writing a compressed
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// tar archive to out.
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func (tlz4 *TarLz4) Create(out io.Writer) error {
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tlz4.wrapWriter()
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return tlz4.Tar.Create(out)
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}
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// Open opens t for reading a compressed archive from
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// in. The size parameter is not used.
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func (tlz4 *TarLz4) Open(in io.Reader, size int64) error {
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tlz4.wrapReader()
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return tlz4.Tar.Open(in, size)
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}
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// Extract extracts a single file from the tar archive.
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// If the target is a directory, the entire folder will
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// be extracted into destination.
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func (tlz4 *TarLz4) Extract(source, target, destination string) error {
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tlz4.wrapReader()
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return tlz4.Tar.Extract(source, target, destination)
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}
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func (tlz4 *TarLz4) wrapWriter() {
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var lz4w *lz4.Writer
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tlz4.Tar.writerWrapFn = func(w io.Writer) (io.Writer, error) {
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lz4w = lz4.NewWriter(w)
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// TODO archiver v4: use proper lz4.Fast
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// bitshifting for backwards compatibility with lz4/v3
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options := []lz4.Option{
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lz4.CompressionLevelOption(lz4.CompressionLevel(1 << (8 + tlz4.CompressionLevel))),
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}
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if err := lz4w.Apply(options...); err != nil {
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return lz4w, err
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}
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return lz4w, nil
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}
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tlz4.Tar.cleanupWrapFn = func() {
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lz4w.Close()
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}
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}
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func (tlz4 *TarLz4) wrapReader() {
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tlz4.Tar.readerWrapFn = func(r io.Reader) (io.Reader, error) {
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return lz4.NewReader(r), nil
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}
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}
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func (tlz4 *TarLz4) String() string { return "tar.lz4" }
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// NewTarLz4 returns a new, default instance ready to be customized and used.
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func NewTarLz4() *TarLz4 {
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return &TarLz4{
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CompressionLevel: 9, // https://github.com/lz4/lz4/blob/1b819bfd633ae285df2dfe1b0589e1ec064f2873/lib/lz4hc.h#L48
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Tar: NewTar(),
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}
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}
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// Compile-time checks to ensure type implements desired interfaces.
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var (
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_ = Reader(new(TarLz4))
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_ = Writer(new(TarLz4))
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_ = Archiver(new(TarLz4))
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_ = Unarchiver(new(TarLz4))
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_ = Walker(new(TarLz4))
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_ = Extractor(new(TarLz4))
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)
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// DefaultTarLz4 is a convenient archiver ready to use.
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var DefaultTarLz4 = NewTarLz4()
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