libfuse3: A Haskell binding to libfuse-3.x

Important notes

• Executables using libfuse3 should be compiled with the threaded runtime (-threaded).
• Developed and tested on Linux only. Not tested on other UNIXes such as BSD and MacOS because I don't own them / machines to run them on.

System dependencies

This package depends on the C library libfuse and pkg-config. Please install them with your system package manager before building this package. For example, on Ubuntu:

sudo apt-get update && sudo apt-get install libfuse3-dev fuse3 pkg-config

NOTE: libfuse3-dev is not available until Ubuntu-20.04 (a.k.a. "focal").

NOTE2: Not to be confused with libfuse-dev (whose version is 2.x). It can coexist with libfuse3-dev, but it is incompatible with this package.

Building from HEAD

This packages uses the ./configure script, but it is not checked into the git repository. To build the source checked out from git, you must generate it from configure.ac before invoking any of the cabal commands:

autoreconf -fiv
# cabal v2-build, etc.

You may have to install autotools or something like that with your system package manager.

Examples

There are two examples, null and passthrough in the example directory. These are the ports of the examples in the official libfuse. They should be good start points for writing your filesystems.

Enable the cabal flag to build them:

cabal v2-configure --flags=examples

Known issues and limitations

• A signal needs to be sent twice to stop the process and unmount the filesystem.
  • This means you have to run kill -2 <pid> twice or hit Ctrl-C twice (if running in foreground).
  • On the other hand, fusermount3 -u can unmount the filesystem on the first attempt.
• Not all Haskell-friendly bindings to the FUSE operations are implemented yet, including but not limited to:
  • struct fuse_conn_info. The availability of filesystem capabilities such as FUSE_CAP_HANDLE_KILLPRIV can't be checked.
  • Setting the fields of struct fuse_file_info from the certain fuse operations.
• Look for the TODO comments in the source tree for more specific topics.

If you are able to fix/implement any of these, that would be very appreciated! Please open a PR to contribute.

Related works

• libfuse: The reference implementation, to which this package binds
• HFuse: The bindings to libfuse-2.x
  • libfuse3 is based on HFuse (with massive rewrites).
  • libfuse3 has more complete API and exposes internal (and unstable) API to allow workarounds.
• fuse-rs: The Rust implementation of FUSE. Unlike this package, fuse-rs implements the FUSE protocol itself, mostly reimplementing libfuse in Rust. See its README for overview.