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63 lines
1.5 KiB
63 lines
1.5 KiB
package archiver
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import (
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"fmt"
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"io"
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"path/filepath"
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"github.com/pierrec/lz4/v4"
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)
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// Lz4 facilitates LZ4 compression.
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type Lz4 struct {
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CompressionLevel int
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}
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// Compress reads in, compresses it, and writes it to out.
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func (lz *Lz4) Compress(in io.Reader, out io.Writer) error {
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w := lz4.NewWriter(out)
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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 + lz.CompressionLevel))),
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}
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if err := w.Apply(options...); err != nil {
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return err
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}
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defer w.Close()
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_, err := io.Copy(w, in)
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return err
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}
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// Decompress reads in, decompresses it, and writes it to out.
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func (lz *Lz4) Decompress(in io.Reader, out io.Writer) error {
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r := lz4.NewReader(in)
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_, err := io.Copy(out, r)
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return err
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}
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// CheckExt ensures the file extension matches the format.
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func (lz *Lz4) CheckExt(filename string) error {
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if filepath.Ext(filename) != ".lz4" {
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return fmt.Errorf("filename must have a .lz4 extension")
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}
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return nil
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}
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func (lz *Lz4) String() string { return "lz4" }
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// NewLz4 returns a new, default instance ready to be customized and used.
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func NewLz4() *Lz4 {
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return &Lz4{
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CompressionLevel: 9, // https://github.com/lz4/lz4/blob/1b819bfd633ae285df2dfe1b0589e1ec064f2873/lib/lz4hc.h#L48
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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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_ = Compressor(new(Lz4))
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_ = Decompressor(new(Lz4))
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)
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// DefaultLz4 is a default instance that is conveniently ready to use.
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var DefaultLz4 = NewLz4()
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