Cleaner append mode handling

Signed-off-by: Xavier Lucas <xavier.lucas@corp.ovh.com>

README.md

@@ -28,6 +28,7 @@ As the development goes, features are added one after another. For the moment th
 * SVFS structure and node attributes are cached as you access them and eviction only occurs on write or remove operations.
 * SVFS does not handle kernel cache invalidation, thus file attributes may appear stale if file content changed.
 * SVFS container creation and removal is not supported.
+* SVFS does not support opening a file in append mode.
 * SVFS does not support uploading SLO/DLO objects and may show erroneous file size of 0 (manifest file).
 
 SVFS limitations and particularities of using Openstack Swift as a POSIX filesystem are discussed in the [docs](docs).

svfs/object.go

@@ -40,7 +40,10 @@ func (o *Object) open(mode fuse.OpenFlags) (oh *ObjectHandle, err error) {
 		t: o,
 	}
 
-	// Modes
+	// Append mode is not supported
+	if mode&fuse.OpenAppend == fuse.OpenAppend {
+		return nil, fuse.ENOTSUP
+	}
 	if mode.IsReadOnly() {
 		oh.r, _, err = o.s.ObjectOpen(o.c.Name, o.so.Name, false, nil)
 		return oh, err