appdata: cannot use cifs or sshfs

Fixes #827

src/apps.js

@@ -515,6 +515,9 @@ async function checkStorage(app, volumeId, prefix) {
     const volume = await volumes.get(volumeId);
     if (volume === null) throw new BoxError(BoxError.BAD_FIELD, 'Storage volume not found');
 
+    // lack of file perms makes these unsupported
+    if (volume.mountType === 'cifs' || volume.mountType === 'sshfs') throw new BoxError(BoxError.BAD_FIELD, `${volume.mountType} volumes cannot be used as data directory`);
+
     const status = await volumes.getStatus(volume);
     if (status.state !== 'active') throw new BoxError(BoxError.BAD_FIELD, 'Volume is not active');