RedBear-OS/src/macros.rs

#[macro_export]
macro_rules! strto_impl {
    (
        $rettype:ty, $signed:expr, $maxval:expr, $minval:expr, $s:ident, $endptr:ident, $base:ident
    ) => {{
        // ensure these are constants
        const CHECK_SIGN: bool = $signed;
        const MAX_VAL: $rettype = $maxval;
        const MIN_VAL: $rettype = $minval;

        let set_endptr = |idx: isize| {
            if !$endptr.is_null() {
                // This is stupid, but apparently strto* functions want
                // const input but mut output, yet the man page says
                // "stores the address of the first invalid character in *endptr"
                // so obviously it doesn't want us to clone it.
                *$endptr = $s.offset(idx) as *mut _;
            }
        };

        let invalid_input = || {
            platform::errno = EINVAL;
            set_endptr(0);
        };

        // only valid bases are 2 through 36
        if $base != 0 && ($base < 2 || $base > 36) {
            invalid_input();
            return 0;
        }

        let mut idx = 0;

        // skip any whitespace at the beginning of the string
        while ctype::isspace(*$s.offset(idx) as c_int) != 0 {
            idx += 1;
        }

        // check for +/-
        let positive = match is_positive(*$s.offset(idx)) {
            Some((pos, i)) => {
                idx += i;
                pos
            }
            None => {
                invalid_input();
                return 0;
            }
        };

        // convert the string to a number
        let num_str = $s.offset(idx);
        let res = match $base {
            0 => detect_base(num_str)
                .and_then(|($base, i)| convert_integer(num_str.offset(i), $base)),
            8 => convert_octal(num_str),
            16 => convert_hex(num_str),
            _ => convert_integer(num_str, $base),
        };

        // check for error parsing octal/hex prefix
        // also check to ensure a number was indeed parsed
        let (num, i, overflow) = match res {
            Some(res) => res,
            None => {
                invalid_input();
                return 0;
            }
        };
        idx += i;

        let overflow = if CHECK_SIGN {
            overflow || (num as c_long).is_negative()
        } else {
            overflow
        };
        // account for the sign
        let num = num as $rettype;
        let num = if overflow {
            platform::errno = ERANGE;
            if CHECK_SIGN {
                if positive {
                    MAX_VAL
                } else {
                    MIN_VAL
                }
            } else {
                MAX_VAL
            }
        } else {
            if positive {
                num
            } else {
                // not using -num to keep the compiler happy
                num.overflowing_neg().0
            }
        };

        set_endptr(idx);

        num
    }};
}