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Date: Sun, 27 Nov 2011 00:06:00 -0000
From: wp1068189-ssc <stefan.sonnenberg@pythonmeister.com>
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Subject: Passing function pointer to fcall
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Please take a look at this piece of code:
=C2=A0
#include <stdio.h>
#include <ffi.h>
#include <stdlib.h>

int msg(void (*a) (char *)) {
=C2=A0=C2=A0=C2=A0 return 23;
=C2=A0=C2=A0=C2=A0 // but this doesn't work :-(
=C2=A0=C2=A0=C2=A0 a("Hi, there !\n");
}

int main(int argc, char ** argv)
=C2=A0=C2=A0=C2=A0 {


=C2=A0=C2=A0=C2=A0 ffi_cif cif;
=C2=A0=C2=A0=C2=A0 ffi_abi abi;
=C2=A0=C2=A0=C2=A0 ffi_status status;
=C2=A0=C2=A0=C2=A0 int nargs =3D 1;
=C2=A0=C2=A0=C2=A0 ffi_type *rtype =3D &ffi_type_uint32;
=C2=A0=C2=A0=C2=A0 ffi_type **atypes;
=C2=A0=C2=A0=C2=A0 void **avalues;
=C2=A0=C2=A0=C2=A0 void *result;

=C2=A0=C2=A0=C2=A0 atypes =3D malloc(sizeof(ffi_type));
=C2=A0=C2=A0=C2=A0 atypes[0] =3D &ffi_type_pointer;

=C2=A0=C2=A0=C2=A0 avalues =3D malloc(sizeof(ffi_type_pointer));
=C2=A0=C2=A0=C2=A0 // I want to call msg with a pointer to printf
=C2=A0=C2=A0=C2=A0 *(void**)avalues[0] =3D printf;

=C2=A0=C2=A0=C2=A0 status =3D ffi_prep_cif(&cif, FFI_DEFAULT_ABI, nargs, rt=
ype, atypes);

=C2=A0=C2=A0=C2=A0 result =3D (ffi_type *) malloc(sizeof(rtype->size));

=C2=A0=C2=A0=C2=A0 if(status !=3D FFI_OK)
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 printf("ffi_prep_cif failed (%i)=
\n",status);

=C2=A0=C2=A0=C2=A0 ffi_call(&cif,FFI_FN(msg),result,avalues);

=C2=A0=C2=A0=C2=A0 return(*(int *)result);
=C2=A0=C2=A0=C2=A0 }
=C2=A0
As you might imagine, I'd like to call a function "msg" and send it a point=
er to
printf,
but that does not work.
I guess it has to do with the pointer me is constructing.
=C2=A0
But I have absolutely no idea what I'm doing wrong.
=C2=A0
Can anyone help, please ?=C2=A0