Closures in C using libffi closures API

closure.c

#include <stdio.h>
#include <ffi.h>
#include <stdlib.h>

/* Acts like puts with the file given at time of enclosure. */
void puts_binding(ffi_cif *cif, void *ret, void* args[], void *stream) {
	*(ffi_arg *) ret = fputs(*(char **) args[0], (FILE *) stream);
}

typedef int (*puts_t)(char *);

typedef struct {
	ffi_closure* closure;
	ffi_type *arg_types[1];
	ffi_cif cif;
	puts_t fn;
} ffi_putter_t;

ffi_putter_t*
make_putter(FILE* stream) {
	ffi_status status;
	void *code_ptr;
	ffi_putter_t *ffi_putter;

	ffi_putter = malloc(sizeof(*ffi_putter));
	ffi_putter->closure = ffi_closure_alloc(sizeof(ffi_closure), &code_ptr);
	if (ffi_putter == NULL) {
		printf("Failed to allocated memory for closure!\n");
		goto err;
	}

	ffi_putter->arg_types[0] = &ffi_type_pointer;
	status = ffi_prep_cif(&(ffi_putter->cif), FFI_DEFAULT_ABI, 1, &ffi_type_sint, ffi_putter->arg_types);
	if (status != FFI_OK) {
		printf("ffi_prep_cif failed: %d\n", status);
		goto err;
	}

	status = ffi_prep_closure_loc(ffi_putter->closure, &(ffi_putter->cif), puts_binding, stream, code_ptr);
	if (status != FFI_OK) {
		printf("ffi_prep_closure_loc failed: %d\n", status);
		goto err;
	}

	ffi_putter->fn = (puts_t)code_ptr;
	return ffi_putter;
err:
	ffi_closure_free(ffi_putter->closure);
	free(ffi_putter);
	return NULL;
}

int main() {
	ffi_putter_t *stdio_putter;
	ffi_putter_t *stderr_putter;

	stdio_putter = make_putter(stdout);
	stderr_putter = make_putter(stderr);

	stderr_putter->fn("Writing to STDERR\n");
	stdio_putter->fn("Writing to STDOUT\n");
	return 0;
}