main: move and rename checkDir*() helper

To avoid confusion with fsck, rename to isDir*()
and move the functions into init_dir.go.

checkdir.go

@@ -1,36 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"io/ioutil"
-	"os"
-)
-
-// checkDirEmpty - check if "dir" exists and is an empty directory.
-// Returns an *os.PathError if Stat() on the path fails.
-func checkDirEmpty(dir string) error {
-	err := checkDir(dir)
-	if err != nil {
-		return err
-	}
-	entries, err := ioutil.ReadDir(dir)
-	if err != nil {
-		return err
-	}
-	if len(entries) == 0 {
-		return nil
-	}
-	return fmt.Errorf("directory %s not empty", dir)
-}
-
-// checkDir - check if "dir" exists and is a directory
-func checkDir(dir string) error {
-	fi, err := os.Stat(dir)
-	if err != nil {
-		return err
-	}
-	if !fi.IsDir() {
-		return fmt.Errorf("%s is not a directory", dir)
-	}
-	return nil
-}

init_dir.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"fmt"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -12,6 +14,35 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
+// isDirEmpty checks if "dir" exists and is an empty directory.
+// Returns an *os.PathError if Stat() on the path fails.
+func isDirEmpty(dir string) error {
+	err := isDir(dir)
+	if err != nil {
+		return err
+	}
+	entries, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return err
+	}
+	if len(entries) == 0 {
+		return nil
+	}
+	return fmt.Errorf("directory %s not empty", dir)
+}
+
+// isDir checks if "dir" exists and is a directory.
+func isDir(dir string) error {
+	fi, err := os.Stat(dir)
+	if err != nil {
+		return err
+	}
+	if !fi.IsDir() {
+		return fmt.Errorf("%s is not a directory", dir)
+	}
+	return nil
+}
+
 // initDir prepares a directory for use as a gocryptfs storage directory.
 // In forward mode, this means creating the gocryptfs.conf and gocryptfs.diriv
 // files in an empty directory.
@@ -26,7 +57,7 @@ func initDir(args *argContainer) {
 			os.Exit(exitcodes.Init)
 		}
 	} else {
-		err = checkDirEmpty(args.cipherdir)
+		err = isDirEmpty(args.cipherdir)
 		if err != nil {
 			tlog.Fatal.Printf("Invalid cipherdir: %v", err)
 			os.Exit(exitcodes.Init)

main.go

@@ -174,7 +174,7 @@ func main() {
 	}
 	// Check that CIPHERDIR exists
 	args.cipherdir, _ = filepath.Abs(flagSet.Arg(0))
-	err = checkDir(args.cipherdir)
+	err = isDir(args.cipherdir)
 	if err != nil {
 		tlog.Fatal.Printf("Invalid cipherdir: %v", err)
 		os.Exit(exitcodes.CipherDir)

mount.go

@@ -58,9 +58,9 @@ func doMount(args *argContainer) {
 		os.Exit(exitcodes.MountPoint)
 	}
 	if args.nonempty {
-		err = checkDir(args.mountpoint)
+		err = isDir(args.mountpoint)
 	} else {
-		err = checkDirEmpty(args.mountpoint)
+		err = isDirEmpty(args.mountpoint)
 		// OSXFuse will create the mountpoint for us ( https://github.com/rfjakob/gocryptfs/issues/194 )
 		if runtime.GOOS == "darwin" && os.IsNotExist(err) {
 			tlog.Info.Printf("Mountpoint %q does not exist, but should be created by OSXFuse",