golangci-lint: fix issues found by "unused" and "deadcode"

Except xattrSupported, this is a false positive.

$ golangci-lint run --disable-all --enable unused --enable deadcode
gocryptfs-xray/xray_main.go:24:5: `GitVersionFuse` is unused (deadcode)
var GitVersionFuse = "[GitVersionFuse not set - please compile using ./build.bash]"
    ^
tests/symlink_race/main.go:47:6: `chmodLoop` is unused (deadcode)
func chmodLoop() {
     ^
internal/readpassword/extpass_test.go:11:5: `testPw` is unused (deadcode)
var testPw = []byte("test")
    ^
tests/reverse/xattr_test.go:13:6: func `xattrSupported` is unused (unused)
func xattrSupported(path string) bool {
     ^
internal/fusefrontend_reverse/rpath.go:20:22: func `(*RootNode).abs` is unused (unused)
func (rfs *RootNode) abs(relPath string, err error) (string, error) {
                     ^
tests/matrix/matrix_test.go:310:6: `sContains` is unused (deadcode)
func sContains(haystack []string, needle string) bool {

gocryptfs-xray/xray_main.go

@@ -20,9 +20,6 @@ import (
 // GitVersion is the gocryptfs version according to git, set by build.bash
 var GitVersion = "[GitVersion not set - please compile using ./build.bash]"
 
-// GitVersionFuse is the go-fuse library version, set by build.bash
-var GitVersionFuse = "[GitVersionFuse not set - please compile using ./build.bash]"
-
 // BuildDate is a date string like "2017-09-06", set by build.bash
 var BuildDate = "0000-00-00"
 

internal/fusefrontend_reverse/rpath.go

@@ -12,18 +12,6 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
-// abs basically returns storage dir + "/" + relPath.
-// It takes an error parameter so it can directly wrap decryptPath like this:
-// a, err := rfs.abs(rfs.decryptPath(relPath))
-// abs never generates an error on its own. In other words, abs(p, nil) never
-// fails.
-func (rfs *RootNode) abs(relPath string, err error) (string, error) {
-	if err != nil {
-		return "", err
-	}
-	return filepath.Join(rfs.args.Cipherdir, relPath), nil
-}
-
 // rDecryptName decrypts the ciphertext name "cName", given the dirIV of the
 // directory "cName" lies in. The relative plaintext path to the directory
 // "pDir" is used if a "gocryptfs.longname.XYZ.name" must be resolved.

internal/readpassword/extpass_test.go

@@ -8,8 +8,6 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
-var testPw = []byte("test")
-
 func TestMain(m *testing.M) {
 	// Shut up info output
 	tlog.Info.Enabled = false

tests/matrix/matrix_test.go

@@ -306,16 +306,6 @@ func TestFileHoles(t *testing.T) {
 	}
 }
 
-// sContains - does the slice of strings "haystack" contain "needle"?
-func sContains(haystack []string, needle string) bool {
-	for _, element := range haystack {
-		if element == needle {
-			return true
-		}
-	}
-	return false
-}
-
 func TestRmwRace(t *testing.T) {
 
 	runtime.GOMAXPROCS(10)

tests/symlink_race/main.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"os"
 	"syscall"
-	"time"
 )
 
 const (
@@ -44,19 +43,6 @@ func renameLoop() {
 	}
 }
 
-func chmodLoop() {
-	var err error
-	for {
-		err = syscall.Chmod(testFile, 0777)
-		if err != nil {
-			fmt.Printf("Chmod() failed: %v\n", err)
-		} else {
-			fmt.Printf("Chmod() ok\n")
-		}
-		time.Sleep(100 * time.Microsecond)
-	}
-}
-
 func openLoop() {
 	var err error
 	var f *os.File