Adding upstream version 3.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

brotli.go

@@ -0,0 +1,55 @@
+package archiver
+
+import (
+	"fmt"
+	"io"
+	"path/filepath"
+
+	"github.com/andybalholm/brotli"
+)
+
+// Brotli facilitates brotli compression.
+type Brotli struct {
+	Quality int
+}
+
+// Compress reads in, compresses it, and writes it to out.
+func (br *Brotli) Compress(in io.Reader, out io.Writer) error {
+	w := brotli.NewWriterLevel(out, br.Quality)
+	defer w.Close()
+	_, err := io.Copy(w, in)
+	return err
+}
+
+// Decompress reads in, decompresses it, and writes it to out.
+func (br *Brotli) Decompress(in io.Reader, out io.Writer) error {
+	r := brotli.NewReader(in)
+	_, err := io.Copy(out, r)
+	return err
+}
+
+// CheckExt ensures the file extension matches the format.
+func (br *Brotli) CheckExt(filename string) error {
+	if filepath.Ext(filename) != ".br" {
+		return fmt.Errorf("filename must have a .br extension")
+	}
+	return nil
+}
+
+func (br *Brotli) String() string { return "brotli" }
+
+// NewBrotli returns a new, default instance ready to be customized and used.
+func NewBrotli() *Brotli {
+	return &Brotli{
+		Quality: brotli.DefaultCompression,
+	}
+}
+
+// Compile-time checks to ensure type implements desired interfaces.
+var (
+	_ = Compressor(new(Brotli))
+	_ = Decompressor(new(Brotli))
+)
+
+// DefaultBrotli is a default instance that is conveniently ready to use.
+var DefaultBrotli = NewBrotli()