Re: [Libguestfs] [nbdkit PATCH v2 1/3] backend: Rework internal/filter error return semantics

I had a think about this. How about (for the internal backend interface only) returning an extra ‘int *err’ parameter? int (*pread) (struct backend *, struct connection *conn, void *buf, uint32_t count, uint64_t offset, uint32_t flags, int *err); This has some advantages: - It's explicit. - It means we preserve the convention that -1 = error used everywhere else in nbdkit. - Better for APIs that actually return something like get_size. - Can be both read and written. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/