title="Userspace file system and device driver code sharing"
As is well-known, [puffs(3)](http://netbsd.gw.com/cgi-bin/man-cgi?puffs+3+NetBSD-5.1+i386) is the NetBSD userspace file system framework. It provides support for implementing file servers in userspace. A lesser known "cousin" of puffs is the Pass-to-Userspace Device, or [pud(4)](http://netbsd.gw.com/cgi-bin/man-cgi?pud+4+NetBSD-5.1+i386) framework, which provides support for implementing character and block device servers in userspace. Both use [putter(9)](http://netbsd.gw.com/cgi-bin/man-cgi?putter+9+NetBSD-5.1+i386) for transmitting requests to and from the kernel.
Currently, puffs includes a userspace support library: libpuffs. It provides two facets:
* file system routines and callback interface
* generic parts, including kernel request handling
On the other hand, pud is without a userspace support library and servers talk with kernel directly with `read()` and `write()`.
The goal of the project is to modify libpuffs into a generic library which pud and puffs can share, and provide libpuffs and libpud built on this base. The submission should include a rough analysis of the source modules of libpuffs and what is going to happen to them during the project.
This project is fairly straightforward, but involves a reasonable amount of work. Plenty of [documentation](http://www.netbsd.org/docs/puffs/#moreinfo) exists to make the learning curve manageable. This project is an excellent opportunity to practise getting your hands dirty with real world systems.
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