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Latest commit b5dcce9 Mar 3, 2017 @tduehr tduehr version bump to 1.9.18


ruby-ffi https://wiki.github.com/ffi/ffi Build Status


Ruby-FFI is a ruby extension for programmatically loading dynamic libraries, binding functions within them, and calling those functions from Ruby code. Moreover, a Ruby-FFI extension works without changes on Ruby and JRuby. Discover why you should write your next extension using Ruby-FFI.


  • Intuitive DSL
  • Supports all C native types
  • C structs (also nested), enums and global variables
  • Callbacks from C to ruby
  • Automatic garbage collection of native memory


require 'ffi'

module MyLib
  extend FFI::Library
  ffi_lib 'c'
  attach_function :puts, [ :string ], :int

MyLib.puts 'Hello, World using libc!'

For less minimalistic and more sane examples you may look at:


You need a sane building environment in order to compile the extension. At a minimum, you will need:

  • A C compiler (e.g. Xcode on OSX, gcc on everything else)
  • libffi development library - this is commonly in the libffi-dev or libffi-devel

On Linux systems running with PaX (Gentoo, Alpine, etc.) FFI may trigger mprotrect errors. You may need to disable mprotect for ruby (paxctl -m [/path/to/ruby]) for the time being until a solution is found.


From rubygems:

[sudo] gem install ffi

or from the git repository on github:

git clone git://github.com/ffi/ffi.git
cd ffi
rake gem:install


The ffi library is covered by the BSD license, also see the LICENSE file. The specs are shared with Rubyspec and are licensed by the same license as Rubyspec, see the LICENSE.SPECS file.


The following people have submitted code, bug reports, or otherwise contributed to the success of this project: