go-fuse

README

GO-FUSE: native bindings for the FUSE kernel module.


HIGHLIGHTS

* High speed: as fast as libfuse using the gc compiler for single
threaded loads.

* Supports in-process mounting of different FileSystems onto
subdirectories of the FUSE mount.

* Supports 3 interfaces for writing filesystems:
  - PathFileSystem: define filesystems in terms path names.
  - NodeFileSystem: define filesystems in terms of inodes.
  - RawFileSystem: define filesystems in terms of FUSE's raw
  wire protocol.

* Both NodeFileSystem and PathFileSystem support manipulation of true
  hardlinks.

* Includes two fleshed out examples, zipfs and unionfs.


EXAMPLES

* examples/hello/hello.go contains a 60-line "hello world" filesystem

* zipfs/zipfs.go contains a small and simple read-only filesystem for
  zip and tar files. The corresponding command is in example/zipfs/
  For example,

    mkdir /tmp/mountpoint
    example/zipfs/zipfs /tmp/mountpoint file.zip &
    ls /tmp/mountpoint
    fusermount -u /tmp/mountpoint

* zipfs/multizipfs.go shows how to use in-process mounts to
  combine multiple Go-FUSE filesystems into a larger filesystem.

* fuse/loopback.go mounts another piece of the filesystem.
  Functionally, it is similar to a symlink.  A binary to run is in
  example/loopback/ . For example

    mkdir /tmp/mountpoint
    example/loopback/loopback -debug /tmp/mountpoint /some/other/directory &
    ls /tmp/mountpoint
    fusermount -u /tmp/mountpoint

* unionfs/unionfs.go: implements a union mount using 1 R/W branch, and
  multiple R/O branches.

    mkdir -p  /tmp/mountpoint /tmp/writable
    example/unionfs/unionfs /tmp/mountpoint /tmp/writable /usr &
    ls /tmp/mountpoint
    ls -l /tmp/mountpoint/bin/vi
    rm /tmp/mountpoint/bin/vi
    ls -l /tmp/mountpoint/bin/vi
    cat /tmp/writable/*DELETION*/*

* union/autounionfs.go: creates UnionFs mounts automatically based on
  existence of READONLY symlinks.


Tested on:

- x86 32bits (Fedora 14).
- x86 64bits (Ubuntu Lucid).


BENCHMARKS

We use threaded stats over a read-only filesystem for benchmarking.
Automated code is under benchmark/ directory. A simple C version of
the same FS gives a FUSE baseline

Data points (Go-FUSE version May 2012), 1000 files, high level
interface, all kernel caching turned off, median stat time:

platform                    libfuse     Go-FUSE      difference (%)

Lenovo T60/Fedora16 (1cpu)  349us       355us        2% slower
Lenovo T400/Lucid   (1cpu)  138us       140us        5% slower
Dell T3500/Lucid    (1cpu)   72us        76us        5% slower

On T60, for each file we have
- Client side latency is 360us
- 106us of this is server side latency (4.5x lookup 23us, 1x getattr 4us)
- 16.5us is due to latency measurements.
- 3us is due to garbage collection.



MACOS SUPPORT

go-fuse works somewhat on OSX. Known limitations:

* All of the limitations of OSXFUSE, including lack of support for
  NOTIFY.

* OSX issues STATFS calls continuously (leading to performance
  concerns).

* OSX has trouble with concurrent reads from the FUSE device, leading
  to performance concerns.

* A bunch of tests under fuse/test/ fail, and the functionality they
  test for OSX is likely broken.


CREDITS

* Inspired by Taru Karttunen's package, https://bitbucket.org/taruti/go-extra.

* Originally based on Ivan Krasin's https://github.com/krasin/go-fuse-zip


BUGS

Yes, probably.  Report them through
https://github.com/hanwen/go-fuse/issues


DISCLAIMER

This is not an official Google product.


KNOWN PROBLEMS

Grep source code for TODO.  Major topics:

* Support for umask in Create

* Missing support for network FS file locking: FUSE_GETLK, FUSE_SETLK,
  FUSE_SETLKW

* Missing support for FUSE_INTERRUPT, CUSE, BMAP, POLL, IOCTL

* In the path API, renames are racy; See also:

    http://sourceforge.net/mailarchive/message.php?msg_id=27550667

  Don't use the path API if you care about correctness.


LICENSE

Like Go, this library is distributed under the new BSD license.  See
accompanying LICENSE file.