port to github/pierrec/lz4/v4

Resolves #248 .

Minimum lang version needs to be bumped to 1.13, otherwise we get this
error:
./lz4.go:20:53: invalid operation: 1 << (8 + lz.CompressionLevel) (signed shift count type int) requires go1.13 or later (-lang was set to go1.12; check go.mod)
./tarlz4.go:88:54: invalid operation: 1 << (8 + tlz4.CompressionLevel) (signed shift count type int) requires go1.13 or later (-lang was set to go1.12; check go.mod)

Author: rathann

go.mod

@@ -1,6 +1,6 @@
 module github.com/mholt/archiver/v3
 
-go 1.12
+go 1.13
 
 require (
 	github.com/andybalholm/brotli v1.0.0
@@ -12,7 +12,7 @@ require (
 	github.com/klauspost/pgzip v1.2.4
 	github.com/kr/text v0.2.0 // indirect
 	github.com/nwaples/rardecode v1.1.0
-	github.com/pierrec/lz4/v3 v3.3.2
+	github.com/pierrec/lz4/v4 v4.0.3
 	github.com/ulikunitz/xz v0.5.7
 	github.com/xi2/xz v0.0.0-20171230120015-48954b6210f8
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect

go.sum

@@ -45,8 +45,8 @@ github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+W
 github.com/onsi/ginkgo v1.8.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
 github.com/onsi/gomega v1.5.0/go.mod h1:ex+gbHU/CVuBBDIJjb2X0qEXbFg53c61hWP/1CpauHY=
 github.com/pierrec/cmdflag v0.0.2/go.mod h1:a3zKGZ3cdQUfxjd0RGMLZr8xI3nvpJOB+m6o/1X5BmU=
-github.com/pierrec/lz4/v3 v3.3.2 h1:QTUOCbMNDbK4PYtkuHyOBd28C0UhPBw3T4OH4WpFDik=
-github.com/pierrec/lz4/v3 v3.3.2/go.mod h1:280XNCGS8jAcG++AHdd6SeWnzyJ1w9oow2vbORyey8Q=
+github.com/pierrec/lz4/v4 v4.0.3 h1:vNQKSVZNYUEAvRY9FaUXAF1XPbSOHJtDTiP41kzDz2E=
+github.com/pierrec/lz4/v4 v4.0.3/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/schollz/progressbar/v2 v2.13.2/go.mod h1:6YZjqdthH6SCZKv2rqGryrxPtfmRB/DWZxSMfCXPyD8=

lz4.go

@@ -5,7 +5,7 @@ import (
 	"io"
 	"path/filepath"
 
-	"github.com/pierrec/lz4/v3"
+	"github.com/pierrec/lz4/v4"
 )
 
 // Lz4 facilitates LZ4 compression.
@@ -16,7 +16,12 @@ type Lz4 struct {
 // Compress reads in, compresses it, and writes it to out.
 func (lz *Lz4) Compress(in io.Reader, out io.Writer) error {
 	w := lz4.NewWriter(out)
-	w.Header.CompressionLevel = lz.CompressionLevel
+	options := []lz4.Option{
+		lz4.CompressionLevelOption(lz4.CompressionLevel(1 << (8 + lz.CompressionLevel))),
+	}
+	if err := w.Apply(options...); err != nil {
+		return err
+	}
 	defer w.Close()
 	_, err := io.Copy(w, in)
 	return err

tarlz4.go

@@ -5,7 +5,7 @@ import (
 	"io"
 	"strings"
 
-	"github.com/pierrec/lz4/v3"
+	"github.com/pierrec/lz4/v4"
 )
 
 // TarLz4 facilitates lz4 compression
@@ -84,7 +84,12 @@ func (tlz4 *TarLz4) wrapWriter() {
 	var lz4w *lz4.Writer
 	tlz4.Tar.writerWrapFn = func(w io.Writer) (io.Writer, error) {
 		lz4w = lz4.NewWriter(w)
-		lz4w.Header.CompressionLevel = tlz4.CompressionLevel
+		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() {