Using ssize_t vs int

Code

I've got a function which I can write in one of four possible ways:

    int do_or_die(int retval);
    int do_or_die(ssize_t retval);
    ssize_t do_or_die(int retval);   
    ssize_t do_or_die(ssize_t retval);

And then it will be called with both of these ways for library functions:

    written = do_or_die(write(...)); // POSIX write returns ssize_t
    printed = do_or_die(printf(...)); // printf returns int

Questions

Which prototype should I use?
What types should I give to written and printed?

I want to have the most robust and standard code, while still having just one do_or_die function.

I am using C99 in this case, but if answer is different for C11, then I'd like to know that too, for future.

Solution

There's no guarantee in the POSIX standard that sizeof(int) >= sizeof(ssize_t), nor the other way around. Typically ssize_t is larger than int, but the safe and portable option in C99 is to use intmax_t instead for the argument and the return value.

The only guarantees you have wrt. the relationship between int and ssize_t are:

int can store values of at least the range [-2^15 ... 2^15-1] per ISO C
ssize_t can store values of at least the range [-1 ... 2^15-1] per POSIX (see also _POSIX_SSIZE_MAX).

(Interestingly, there isn't even a guarantee that ssize_t can store the negative counterparts of its positive range. It's not a signed size_t, but a "size type" with an error value.)