This is a fork of the libfuse reference implementation which may be found here: https://github.com/libfuse/libfuse
This fork is designed to build with CMake, otherwise it should be identical to the reference platform. The best reference for using libfuse is the reference implementation. BUT - This is the place to come for information about building libfuse with CMake instead of meson.
FUSE (Filesystem in Userspace) is an interface for userspace programs to export a filesystem to the Linux kernel. The FUSE project consists of two components: the fuse kernel module (maintained in the regular kernel repositories) and the libfuse userspace library (maintained in this repository). libfuse provides the reference implementation for communicating with the FUSE kernel module.
A FUSE file system is typically implemented as a standalone application that links with libfuse. libfuse provides functions to mount the file system, unmount it, read requests from the kernel, and send responses back. libfuse offers two APIs: a "high-level", synchronous API, and a "low-level" asynchronous API. In both cases, incoming requests from the kernel are passed to the main program using callbacks. When using the high-level API, the callbacks may work with file names and paths instead of inodes, and processing of a request finishes when the callback function returns. When using the low-level API, the callbacks must work with inodes and responses must be sent explicitly using a separate set of API functions.
libfuse is shipped by all major Linux distributions and has been in production use across a wide range of systems for many years. However, at present libfuse does not have any active, regular contributors. The current maintainer continues to apply pull requests and makes regular releases, but unfortunately has no capacity to do any development beyond addressing high-impact issues. When reporting bugs, please understand that unless you are including a pull request or are reporting a critical issue, you will probably not get a response. If you are using libfuse, please consider contributing to the project.
- Linux (fully)
- BSD (mostly/best-effort)
- For OS-X, please use OSXFUSE
You can download libfuse from https://github.com/libfuse/libfuse/releases. To build and
install, you must use Meson and
Ninja; or, CMake. After downloading the tarball and .sig file, verify
it using signify:
signify -V -m fuse-X.Y.Z.tar.gz -p fuse-X.Y.pub
The fuse-X.Y.pub file contains the signing key and needs to be obtained from a
trustworthy source. Each libfuse release contains the signing key for the release after it
in the signify directory, so you only need to manually acquire this file once when you
install libfuse for the first time.
To build and install, you are free to use meson or CMake
We recommend to use CMake the hugely superior meta-make system. CMake allows a developer to use a wide variety of build systems and includes native support for various command-line or GUI environments such as Visual Studio, Eclipse, CodeBlocks, Ninja, or plain old Unix make.
You are free to use the Unix make, Ninja, or any other CMake supported make system - see, CMake is better than meson !
Out of source builds are highly recommended. Simply create a (temporary) build directory and run CMake:
$ mkdir build; cd build
$ cmake ..
Normally, the default build options will work fine. However, to build examples, tests, and other recommended utilities, you will probably want to do this: (this also explicitly uses Unix Makefiles - the cmake default)
$ cmake -G "Unix Makefiles" \
-DOPTION_BUILD_UTILS=ON \
-DOPTION_BUILD_EXAMPLES=ON \
-DCMAKE_INSTALL_PREFIX=/home/<USER>/FUSE/install \
-DCMAKE_BUILD_TYPE=Debug ..
To build, test and install, you then use make (or other supported build systems):
The equivalent for Meson build is as follows:
$ meson configure # list options
$ meson configure -D disable-mtab=true # set an optionq
$ # ensure all meson options are applied to the final build system
$ meson setup --reconfigure ../
IMPORTANT !!! - Almost all tests will fail unless you either
- run as root
- change permissions on util/fusermount3 (see blow)
$ make
$ python3 -m pytest test/
$ sudo make install
NOTE: One of the primary outstanding issues (with this libfuse-Cmake fork) is to remove any dependency upon python. Expect to see native ctest replace python pytest soon. IMPORTANT - Tests current perform best when run under python3.6. Issues have been reported attempting to use python3.7 with pytest.
Running the tests requires the py.test Python module.
Instead of running the tests as root, the majority of tests can also be run as a regular user if util/fusermount3 is made setuid root first:
$ sudo chown root:root util/fusermount3
$ sudo chmod 4755 util/fusermount3
$ python3 -m pytest test/
NOTE: Some tests are designed to "drop privileges" and so will be skipped if the user is not root.
The fusermount3 program is installed setuid root. This is done to allow normal users to mount their own filesystem implementations.
To limit the harm that malicious users can do this way, fusermount3 enforces the following limitations:
-
The user can only mount on a mountpoint for which they have write permission
-
The mountpoint must not be a sticky directory which isn't owned by the user (like /tmp usually is)
-
No other user (including root) can access the contents of the mounted filesystem (though this can be relaxed by allowing the use of the allow_other and allow_root mount options in /etc/fuse.conf)
If you intend to use the allow_other mount options, be aware that FUSE has an unresolved security bug: if the default_permissions mount option is not used, the results of the first permission check performed by the file system for a directory entry will be re-used for subsequent accesses as long as the inode of the accessed entry is present in the kernel cache - even if the permissions have since changed, and even if the subsequent access is made by a different user. This is of little concern if the filesystem is accessible only to the mounting user (which has full access to the filesystem anyway), but becomes a security issue when other users are allowed to access the filesystem (since they can exploit this to perform operations on the filesystem that they do not actually have permissions for).
This bug needs to be fixed in the Linux kernel and has been known
since 2006 but unfortunately no fix has been applied yet. If you
depend on correct permission handling for FUSE file systems, the only
workaround is to use default_permissions (which does not currently
support ACLs), or to completely disable caching of directory entry
attributes.
FUSE comes with several example file systems in the example
directory. For example, the passthrough examples mirror the contents
of the root directory under the mountpoint. Start from there and adapt
the code!
The documentation of the API functions and necessary callbacks is
mostly contained in the files include/fuse.h (for the high-level
API) and include/fuse_lowlevel.h (for the low-level API). An
autogenerated html version of the API is available in the doc/html
directory and at http://libfuse.github.io/doxygen.
If you need help, please ask on the [email protected] mailing list (subscribe at https://lists.sourceforge.net/lists/listinfo/fuse-devel).
Please report any bugs on the GitHub issue tracker at https://github.com/libfuse/libfuse/issues.
Please report CMake related libfuse bugs here: https://github.com/Smit-tay/libfuse-cmake/issues
Professional support is offered via Rath Consulting.