githaven-fork/vendor/github.com/mholt/archiver/v3/gz.go

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package archiver
import (
"fmt"
"io"
"path/filepath"
"github.com/klauspost/compress/gzip"
"github.com/klauspost/pgzip"
)
// Gz facilitates gzip compression.
type Gz struct {
CompressionLevel int
SingleThreaded bool
}
// Compress reads in, compresses it, and writes it to out.
func (gz *Gz) Compress(in io.Reader, out io.Writer) error {
var w io.WriteCloser
var err error
if gz.SingleThreaded {
w, err = gzip.NewWriterLevel(out, gz.CompressionLevel)
} else {
w, err = pgzip.NewWriterLevel(out, gz.CompressionLevel)
}
if err != nil {
return err
}
defer w.Close()
_, err = io.Copy(w, in)
return err
}
// Decompress reads in, decompresses it, and writes it to out.
func (gz *Gz) Decompress(in io.Reader, out io.Writer) error {
var r io.ReadCloser
var err error
if gz.SingleThreaded {
r, err = gzip.NewReader(in)
} else {
r, err = pgzip.NewReader(in)
}
if err != nil {
return err
}
defer r.Close()
_, err = io.Copy(out, r)
return err
}
// CheckExt ensures the file extension matches the format.
func (gz *Gz) CheckExt(filename string) error {
if filepath.Ext(filename) != ".gz" {
return fmt.Errorf("filename must have a .gz extension")
}
return nil
}
func (gz *Gz) String() string { return "gz" }
// NewGz returns a new, default instance ready to be customized and used.
func NewGz() *Gz {
return &Gz{
CompressionLevel: gzip.DefaultCompression,
}
}
// Compile-time checks to ensure type implements desired interfaces.
var (
_ = Compressor(new(Gz))
_ = Decompressor(new(Gz))
)
// DefaultGz is a default instance that is conveniently ready to use.
var DefaultGz = NewGz()