c - Using ssize_t vs int -


code

i've got function can write in one of 4 possible ways:

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

and called both of these ways library functions:

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

questions

  • which prototype should use?
  • what types should give written , printed?

i want have robust , standard code, while still having 1 do_or_die function.

i using c99 in case, if answer different c11, i'd know too, future.

there's no guarantee in c or posix standards sizeof(int) >= sizeof(ssize_t), nor other way around. typically ssize_t larger int, safe , portable option in c99 use intmax_t instead argument , return value.

the guarantees have wrt. relationship between int , ssize_t are:

  • int can store values of @ least range [-2^15 ... 2^15-1] per iso c
  • ssize_t can store values of @ least range [-1 ... 2^15-1] per posix (see _posix_ssize_max).

(interestingly, there isn't guarantee ssize_t can store negative counterparts of positive range. it's not signed size_t, "size type" error value.)


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