windebug_logger 0.1.4

use std::{convert::TryInto, ptr::null_mut};
use winapi::um::{stringapiset::MultiByteToWideChar, winnls::CP_UTF8};

/// Convert a given `str` into a null-terminated wide character string. Does not
/// check for unexpected null characters.
///
/// Returns `None` if the input string is too long or anything goes wrong.
pub fn str_to_c_wstr(s: &str) -> Option<Box<[u16]>> {
    if s.len() == 0 {
        Some(Box::new([0]))
    } else {
        unsafe {
            let in_len = s.len().try_into().ok()?;
            let num_wchars =
                MultiByteToWideChar(CP_UTF8, 0, s.as_ptr() as *const i8, in_len, null_mut(), 0);
            if num_wchars == 0 {
                return None;
            }

            let len: usize = num_wchars.try_into().ok()?;
            let len = len.checked_add(1)?; // null termination

            let mut out = Vec::<u16>::with_capacity(len);
            let out_num_wchars = MultiByteToWideChar(
                CP_UTF8,
                0,
                s.as_ptr() as *const i8,
                in_len,
                out.as_mut_ptr(),
                num_wchars,
            );
            if out_num_wchars != num_wchars {
                return None;
            }
            out.as_mut_ptr().offset(len as isize - 1).write(0); // null termination
            out.set_len(len);

            Some(out.into())
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use wchar::wch_c;

    #[test]
    fn test_str_to_c_wstr() {
        assert_eq!(*str_to_c_wstr("").unwrap(), *wch_c!(""));
        assert_eq!(*str_to_c_wstr("книга").unwrap(), *wch_c!("книга"));
        assert_eq!(*str_to_c_wstr("🦄✨").unwrap(), *wch_c!("🦄✨"));
    }
}