fusefrontend: handle empty xattrs efficiently

We handle empty files by storing an actual empty file
on disk. Handle xattrs similarily and encrypt the
empty value to the empty value.

1 files changed, 54 insertions, 0 deletions

diff --git a/tests/xattr/xattr_integration_test.go b/tests/xattr/xattr_integration_test.go
index 1e081c2..58d62d9 100644
--- a/tests/xattr/xattr_integration_test.go
+++ b/tests/xattr/xattr_integration_test.go
@@ -66,6 +66,60 @@ func TestXattrSetGetRm(t *testing.T) {
 	}
 }
 
+func TestXattrSetEmpty(t *testing.T) {
+	attr := "user.foo"
+	fn := test_helpers.DefaultPlainDir + "/TestXattrSetEmpty1"
+	err := ioutil.WriteFile(fn, nil, 0700)
+	if err != nil {
+		t.Fatalf("creating empty file failed: %v", err)
+	}
+	// Make sure it does not exist already
+	_, err = xattr.Get(fn, attr)
+	if err == nil {
+		t.Fatal("we should have got an error here")
+	}
+	// Set empty value
+	err = xattr.Set(fn, attr, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Read back
+	val, err := xattr.Get(fn, attr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(val) != 0 {
+		t.Errorf("wrong length: want=0 have=%d", len(val))
+	}
+	// Overwrite empty value with something
+	val1 := []byte("xyz123")
+	err = xattr.Set(fn, attr, val1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Read back
+	val2, err := xattr.Get(fn, attr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(val1, val2) {
+		t.Fatalf("wrong readback value: %v != %v", val1, val2)
+	}
+	// Overwrite something with empty value
+	err = xattr.Set(fn, attr, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Read back
+	val, err = xattr.Get(fn, attr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(val) != 0 {
+		t.Errorf("wrong length: want=0 have=%d", len(val2))
+	}
+}
+
 func TestXattrList(t *testing.T) {
 	fn := test_helpers.DefaultPlainDir + "/TestXattrList"
 	err := ioutil.WriteFile(fn, nil, 0700)