nametransform: reject names longer than 255 chars

Looks like we allowed creating longer names by accident.
Fix that, and add a test that verifies it.

1 files changed, 5 insertions, 0 deletions

diff --git a/internal/nametransform/names.go b/internal/nametransform/names.go
index 638a9eb..20fbede 100644
--- a/internal/nametransform/names.go
+++ b/internal/nametransform/names.go
@@ -12,6 +12,11 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
+const (
+	// Like ext4, we allow at most 255 bytes for a file name.
+	NameMax = 255
+)
+
 // NameTransform is used to transform filenames.
 type NameTransform struct {
 	emeCipher *eme.EMECipher