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go-fuse-c

Build Status GoDoc

CGO wrapper for FUSE C low-level API.

Purpose

After running into trouble getting a couple "pure-Go" FUSE wrappers working, I decided that the most practical approach was to wrap the C library. This would allow reuse of system-specific libraries (like OSXFuse) and avoid ongoing work of porting fixes from multiple client libraries. If your system has a C-API compatible libfuse, then it is likely that this will work with it.

Additionally, I want access to the FUSE Low-Level API, which deals with inodes, rather than the Path based API. Although the Path based API makes it easy to write simple filesystems, the Low Level API is more powerful and makes it easier to make the filesystem behave like a built-in Posix filesystem.

Alternatives

For more FUSE-related references, see Resources Related to FUSE

  • GoFuse: The GoFuse library is a little difficult to use, even if you're familiar with FUSE and Go.

  • Bazil Fuse: Bazil has a low-level API which is similar to this library, however it is lacks good examples and has been mostly dead for years. 4 years ago (April 2015), I spent time figuring out all the interfaces used by Bazil in order to make an in-memory FS example. That PR request is still pending add in-memory example.

  • jacobsa/fuse: Has lots of samples. Don't have any experience with it myself.

Examples

To try the hello example, which corresponds to hello low-level API example that comes with FUSE:

go build example/hello/hello.go
./hello /tmp/mountpoint

Also provided is a slightly more interesting in-memory filesystem:

go build example/memfs/memfs.go
./memfs /tmp/mountpoint

Development Notes

Bridge functions and filesystem handles

The C bridge functions handle the initial FUSE operation callbacks. They call through to static Go functions which are exported in the bridge code. These static functions lookup the filesystem from the provided filesystem handle and pass control to the filesystem implementation.

Integer filesystem handles are used instead of pointers as it is bad form to hold pointers to Go structures in C.

Testing

Bridge methods are normally called from FUSE. However the bridge methods are also available in Go for testing purposes. Since types such as fuse_req are opaque, the FUSE reply methods cannot be called during tests. An internal function enable_bridge_test_mode is used to switch to using test reply methods so that the C / Go interfaces can be tested without running FUSE code.

Run go test -v ./... to execute tests.