[Libguestfs] [nbdkit] Proposed (new) filter API

Here's my second attempt at a filter API. As before, .config and .config_complete can only call the next->.config or next->.config_complete methods in the chain respectively. The change is with the connected functions (get_size, pread, pwrite, etc.). Here we pass a struct of next functions allowing the filter to call any functions on the plugin, so for example a write can turn into read + write (and vice versa although that might not be a good idea). Also .open and .close cannot be intercepted by the filter. They're just used to allow the filter to allocate a handle. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW