Further performance improvements

Further removed multiple pointer instances
Re-use decompression readers (except zstd due to bugs)

squashfs_test.go

@@ -17,7 +17,7 @@ import (
 
 const (
 	squashfsURL  = "https://darkstorm.tech/files/LinuxPATest.sfs"
-	squashfsName = "LinuxPATest.sfs"
+	squashfsName = "tensorflow.sqfs"
 )
 
 func preTest(dir string) (fil *os.File, err error) {
@@ -111,7 +111,7 @@ func BenchmarkRace(b *testing.B) {
 		b.Fatal(err)
 	}
 	libTime = time.Since(start)
-	cmd := exec.Command("unsquashfs", "-d", unsquashPath, fil.Name())
+	cmd := exec.Command("unsquashfs", "-q", "-d", unsquashPath, fil.Name())
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 	start = time.Now()
@@ -187,7 +187,7 @@ func TestExtractQuick(t *testing.T) {
 	}
 }
 
-var filePath = "Start.exe"
+var filePath = "usr/sbin/add-shell"
 
 func TestSingleFile(t *testing.T) {
 	tmpDir := "testing"
@@ -195,7 +195,7 @@ func TestSingleFile(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	os.Remove(filepath.Join(tmpDir, filePath))
+	os.RemoveAll("testing/stuff")
 	rdr, err := NewReader(fil)
 	if err != nil {
 		t.Fatal(err)
@@ -206,7 +206,7 @@ func TestSingleFile(t *testing.T) {
 	}
 	op := DefaultOptions()
 	op.Verbose = true
-	err = f.(*File).ExtractWithOptions("testing", op)
+	err = f.(*File).ExtractWithOptions("testing/stuff", op)
 	if err != nil {
 		t.Fatal(err)
 	}