Add option for autounmount

Even though filesystem notifications aren't implemented for FUSE, I decided to
try my hand at implementing the autounmount feature (#128). I based it on the
EncFS autounmount code, which records filesystem accesses and checks every X
seconds whether it's idled long enough to unmount.

I've tested the feature locally, but I haven't added any tests for this flag.
I also haven't worked with Go before. So please let me know if there's
anything that should be done differently.

One particular concern: I worked from the assumption that the open files table
is unique per-filesystem. If that's not true, I'll need to add an open file
count and associated lock to the Filesystem type instead.

https://github.com/rfjakob/gocryptfs/pull/265

1 files changed, 6 insertions, 0 deletions

diff --git a/internal/fusefrontend/names.go b/internal/fusefrontend/names.go
index 5530e3e..3bf64d5 100644
--- a/internal/fusefrontend/names.go
+++ b/internal/fusefrontend/names.go
@@ -60,9 +60,15 @@ func (fs *FS) openBackingDir(relPath string) (dirfd int, cName string, err error
 
 // encryptPath - encrypt relative plaintext path
 func (fs *FS) encryptPath(plainPath string) (string, error) {
+	if plainPath != "" { // Empty path gets encrypted all the time without actual file accesses.
+		fs.AccessedSinceLastCheck = 1
+	} else { // Empty string gets encrypted as empty string
+		return plainPath, nil
+	}
 	if fs.args.PlaintextNames {
 		return plainPath, nil
 	}
+
 	fs.dirIVLock.RLock()
 	cPath, err := fs.nameTransform.EncryptPathDirIV(plainPath, fs.args.Cipherdir)
 	tlog.Debug.Printf("encryptPath '%s' -> '%s' (err: %v)", plainPath, cPath, err)