fusefrontend: implement path decryption via ctlsock

Closes https://github.com/rfjakob/gocryptfs/issues/84 .

1 files changed, 33 insertions, 2 deletions

diff --git a/internal/fusefrontend/ctlsock_interface.go b/internal/fusefrontend/ctlsock_interface.go
index 8d8b096..964775b 100644
--- a/internal/fusefrontend/ctlsock_interface.go
+++ b/internal/fusefrontend/ctlsock_interface.go
@@ -1,9 +1,12 @@
 package fusefrontend
 
 import (
-	"errors"
+	"fmt"
+	"path"
+	"strings"
 
 	"github.com/rfjakob/gocryptfs/internal/ctlsock"
+	"github.com/rfjakob/gocryptfs/internal/nametransform"
 )
 
 var _ ctlsock.Interface = &FS{} // Verify that interface is implemented.
@@ -15,5 +18,33 @@ func (fs *FS) EncryptPath(plainPath string) (string, error) {
 
 // DecryptPath implements ctlsock.Backend
 func (fs *FS) DecryptPath(cipherPath string) (string, error) {
-	return "", errors.New("Forward mode does not have path decryption implemented")
+	if fs.args.PlaintextNames || cipherPath == "" {
+		return cipherPath, nil
+	}
+	plainPath := ""
+	parts := strings.Split(cipherPath, "/")
+	wd := fs.args.Cipherdir
+	for _, part := range parts {
+		dirIV, err := nametransform.ReadDirIV(wd)
+		if err != nil {
+			fmt.Printf("ReadDirIV: %v\n", err)
+			return "", err
+		}
+		longPart := part
+		if nametransform.IsLongContent(part) {
+			longPart, err = nametransform.ReadLongName(wd + "/" + part)
+			if err != nil {
+				fmt.Printf("ReadLongName: %v\n", err)
+				return "", err
+			}
+		}
+		name, err := fs.nameTransform.DecryptName(longPart, dirIV)
+		if err != nil {
+			fmt.Printf("DecryptName: %v\n", err)
+			return "", err
+		}
+		plainPath = path.Join(plainPath, name)
+		wd = path.Join(wd, part)
+	}
+	return plainPath, nil
 }