Export an appliance and let the .ovf and .vmdk files be owned by user 'A'. The files have modes 644 (user A read/write, read-only for everyone else).
Now, as user 'B', attempt to import the appliance. This will fail with the following rather unintuitive error message:
$ VBoxManage import ~someone/somewhere/build.ovf
VirtualBox Command Line Management Interface Version 3.1.0
(C) 2005-2009 Sun Microsystems, Inc.
All rights reserved.
0%...
ERROR: <NULL>
Details: code NS_OK (0x0), component <NULL>, interface <NULL>, callee <NULL>
Context: "ImportAppliance" at line 252 of file VBoxManageImport.cpp
Changing the permissions on the .ovf file to 666 will "solve" this problem. However, there should be no need for the import to write to the OVF file, and for a setup where a number of people all use appliances from the same exported read-only file system, this is a complete show-stopper. VirtualBox 3.0 did not require write access to the .ovf file either.
I believe this is a bug and it is definitely a regression from 3.0.
