libffi

libffi is Free Software. It has a very liberal license.

What is libffi?

Some programs may not know at the time of compilation what arguments are to be passed to a function. For instance, an interpreter may be told at run-time about the number and types of arguments used to call a given function. Libffi can be used in such programs to provide a bridge from the interpreter program to compiled code.

The libffi library provides a portable, high level programming interface to various calling conventions. This allows a programmer to call any function specified by a call interface description at run-time.

FFI stands for Foreign Function Interface. A foreign function interface is the popular name for the interface that allows code written in one language to call code written in another language. The libffi library really only provides the lowest, machine dependent layer of a fully featured foreign function interface. A layer must exist above libffi that handles type conversions for values passed between the two languages.

Who uses it?

• CPython - the default, most-widely used implementation of the Python programming language uses libffi in the standard ctypes library.
• OpenJDK - the open-source implementation of the Java Platform Standard Edition uses libffi to bridge between the interpreter and native code for some platforms.
• js-ctypes - a foreign function interface for javascript that Mozilla will be shipping in Firefox 3.6.
• Dalvik - Dalvik is the virtual machine which runs the Java platform on Android mobile devices. libffi is used on Android ports for which no custom bridging code has been written.
• Java Native Access (JNA) - the JNI-free way to call native code from Java.
• Ruby-FFI - a Foreign Function Interface extension for Ruby.
• fsbv - Foreign Structure By Value is a foreign function interface library for Common Lisp that extends the standard CFFI package to include support for passing structure arguments by value.
• JSCocoa - call Objective-C code from javascript on Mac OSX and the iPhone (via the libffi-iphone port).
• PyObjC - call Objective-C code from Python on Mac OSX.
• RubyCocoa - call Objective-C code from Ruby on Mac OSX.
• The Glasgow Haskell Compiler - call C code from this popular Haskell implementation.
• Racket - call C code from this popular Scheme implementation.
• gcj - the runtime library for the GNU Compiler for the Java Programming Language uses libffi to handle calls back and forth between interpreted and natively compiled code. gcj is part of the GCC, the GNU Compiler Collection.

Supported Platforms

Please send additional platform test results to libffi-discuss@sourceware.org and feel free to update the wiki page above.

How to get it

You can also check out the very latest version from the development git repository at http://github.com/libffi/libffi. Here's how:

  git clone git://github.com/libffi/libffi.git

Mailing lists

• libffi-announce is a low volume mailing list for libffi release announcements
• libffi-discuss is a mailing list for asking questions, reporting bugs, etc.

Authors and Credits

The developers of the GNU Compiler Collection project have made innumerable valuable contributions. See this ChangeLog files in the source distribution for details.

Some of the ideas behind libffi were inspired by Gianni Mariani's free gencall library for Silicon Graphics machines.

The closure mechanism was designed and implemented by Kresten Krab Thorup.

Major processor architecture ports were contributed by the following developers:

    aarch64             Marcus Shawcroft, James Greenhalgh
    alpha               Richard Henderson
    arc                 Hackers at Synopsis
    arm                 Raffaele Sena
    avr32               Bradley Smith
    blackfin            Alexandre Keunecke I. de Mendonca
    cris                Simon Posnjak, Hans-Peter Nilsson
    csky                Ma Jun, Zhang Wenmeng
    frv                 Anthony Green
    ia64                Hans Boehm
    kvx                 Yann Sionneau
    loongarch64         Cheng Lulu, Xi Ruoyao, Xu Hao,
                        Zhang Wenlong, Pan Xuefeng
    m32r                Kazuhiro Inaoka
    m68k                Andreas Schwab
    m88k                Miod Vallat
    metag               Hackers at Imagination Technologies
    microblaze          Nathan Rossi
    mips                Anthony Green, Casey Marshall
    mips64              David Daney
    moxie               Anthony Green
    nios ii             Sandra Loosemore
    openrisc            Sebastian Macke
    pa                  Randolph Chung, Dave Anglin, Andreas Tobler
    powerpc             Geoffrey Keating, Andreas Tobler,
                        David Edelsohn, John Hornkvist
    powerpc64           Jakub Jelinek
    riscv               Michael Knyszek, Andrew Waterman, Stef O'Rear
    s390                Gerhard Tonn, Ulrich Weigand
    sh                  Kaz Kojima
    sh64                Kaz Kojima
    sparc               Anthony Green, Gordon Irlam
    tile-gx/tilepro     Walter Lee
    vax                 Miod Vallat
    x86                 Anthony Green, Jon Beniston
    x86-64              Bo Thorsen
    xtensa              Chris Zankel

Jesper Skov and Andrew Haley both did more than their fair share of stepping through the code and tracking down bugs.

Thanks also to Tom Tromey for bug fixes, documentation and configuration help.

Thanks to Jim Blandy, who provided some useful feedback on the libffi interface.

Andreas Tobler has done a tremendous amount of work on the testsuite.

Alex Oliva solved the executable page problem for SElinux.

The list above is almost certainly incomplete and inaccurate. I'm happy to make corrections or additions upon request.

If you have a problem, or have found a bug, please file and issue on our issue tracker at https://github.com/libffi/libffi/issues The author can be reached at green@moxielogic.com.