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