#include <stdio.h>
#include <assert.h>

FILE *log_func_call;

typedef int (*func_t)(int arg);

int foo(int a) {
    return a + 1;
}

func_t create_wrap_function(func_t f) {
    int wrapped(int arg) {
        // call original function
        int val = f(arg);
        fprintf(log_func_call, "arg: %d ret: %d", arg, val);
        return val;
    }
    return wrapped;
}

int main(int argc, char* argv[]) {
    assert(log_func_call = fopen("log_func_call", "w"));
    func_t bar = create_wrap_function(foo);
    printf("%d\n", bar(2));

    return 0;
}