Issue #19347 has been updated by kjtsanaktsidis (KJ Tsanaktsidis). Having actually read the title of this issue, I see it's for implementing `fchdir`, not `openat` - but the point is the same, directory file descriptors are important to avoid some race conditions and Ruby doesn't really have a way to use them. I see a discussion on openat fizzled away many years ago - https://bugs.ruby-lang.org/issues/10181. I would be happy to take another stab at an API design for openat in Ruby if people generally agree with the proposition "we should have better support for directory file descriptors in Ruby". ---------------------------------------- Feature #19347: Add Dir.fchdir https://bugs.ruby-lang.org/issues/19347#change-101256 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Priority: Normal ---------------------------------------- Recently, I was working on a program that passes file descriptors over UNIX sockets (using `send_io`/`recv_io`). For file/socket/device descriptors, this works fine using `File#reopen`. However, I found that while Ruby supports `Dir#fileno` to return a directory file descriptor, it cannot use that file descriptor when changing directories. I worked around this in my program by writing the directory path over the UNIX socket, but this results in a TOCTOU vulnerability in certain cases. Passing the directory file descriptor would be simpler and avoid the vulnerability. I've submitted a pull request to implement this method: https://github.com/ruby/ruby/pull/7135 -- https://bugs.ruby-lang.org/