fcntl-tool

Your small yet useful swiss army knife for the fcntl system call, specifically for acquiring and testing file locks, but not limited to those.

This tool only works on UNIX or POSIX-like systems. Please find more information in the following resources:

• https://man7.org/linux/man-pages/man2/fcntl.2.html
• https://apenwarr.ca/log/20101213

🔍 What Problem Does It Solve?

This is for example useful for testing during development. Imagine you want to check how your program behaves, when a lock is already held. Using fcntl-tool, you can acquire these locks!

Supported Platforms

This crate works on all platforms that Rust code can be compiled to. It, however, only makes sense on UNIX or POSIX-like systems.

Supported fcntl Operations

operation	supported
F_GETLK	✅
F_SETLK	✅
F_OFD_GETLK	✅
F_OFD_SETLK	✅
...	Not yet

CLI Usage

Type fcntl-tool --help to get guidance.

Example

$ fcntl-tool --help

# Terminal 1
$ fcntl-tool write-lock --file ./foo.txt
Please press enter to release the Write lock ...


# Terminal 2
$ fcntl-tool test-lock --file ./foo.txt
state: ExclusiveWrite

You can also take a look onto the integration test in the repository.

MSRV

The MSRV of the binary is 1.85.0 stable.