I am happy to finally announce cinvoke 0.1, a binding to the C library cinvoke[1], allowing functions to be loaded and called whose names and types are not known before run-time. Why? Sometimes you can't use the Haskell foreign function interface because you parse the type of the function from somewhere else, i.e. you're writing an interpreter for a language that has an FFI itself. What? The main function it exports is: cinvoke :: Symbol -> RetType b -> [Arg] -> IO b And because code is worth a thousand words, here's a small program that uses libc to write a 1Gb buffer of random garbage to a file:
module Main where
import Foreign.CInvoke
main = do cxt <- newContext libc <- loadLibrary cxt "libc.so.6" malloc <- loadSymbol libc "malloc" creat <- loadSymbol libc "creat" write <- loadSymbol libc "write" free <- loadSymbol libc "free" let sz = 2^30 buf <- cinvoke malloc (retPtr retVoid) [argCSize sz] fd <- cinvoke creat retCInt [argString "/tmp/test", argCUInt 0o644] n <- cinvoke write retCSize [argCInt fd, argPtr buf, argCSize sz] cinvoke free (retPtr retVoid) [argPtr buf]
It hopefully works on any machine on which cinvoke works, but has only been tested on linux x86_64. As the current version of cinvoke only installs a static library, it does not work from GHCi at the moment (without hacking cinvoke to build a shared library). More interesting examples are included in examples/ in the package. Where? Hackage: http://hackage.haskell.org/package/cinvoke Cheers, Remi [1] http://www.nongnu.org/cinvoke/