Function mbcs_decode

crates/vm/src/stdlib/_codecs.rs:480–564

(args: MbcsDecodeArgs, vm: &VirtualMachine)

    #[pyfunction]
    fn mbcs_decode(args: MbcsDecodeArgs, vm: &VirtualMachine) -> PyResult<(String, usize)> {
        use windows_sys::Win32::Globalization::{
            CP_ACP, MB_ERR_INVALID_CHARS, MultiByteToWideChar,
        };

        let _errors = args.errors.as_ref().map(|s| s.as_str()).unwrap_or("strict");
        let data = args.data.borrow_buf();
        let len = data.len();

        if data.is_empty() {
            return Ok((String::new(), 0));
        }

        // Get the required buffer size for UTF-16
        let size = unsafe {
            MultiByteToWideChar(
                CP_ACP,
                MB_ERR_INVALID_CHARS,
                data.as_ptr().cast(),
                len as i32,
                core::ptr::null_mut(),
                0,
            )
        };

        if size == 0 {
            // Try without MB_ERR_INVALID_CHARS for non-strict mode (replacement behavior)
            let size = unsafe {
                MultiByteToWideChar(
                    CP_ACP,
                    0,
                    data.as_ptr().cast(),
                    len as i32,
                    core::ptr::null_mut(),
                    0,
                )
            };
            if size == 0 {
                let err = std::io::Error::last_os_error();
                return Err(vm.new_os_error(format!("mbcs_decode failed: {}", err)));
            }

            let mut buffer = vec![0u16; size as usize];
            let result = unsafe {
                MultiByteToWideChar(
                    CP_ACP,
                    0,
                    data.as_ptr().cast(),
                    len as i32,
                    buffer.as_mut_ptr(),
                    size,
                )
            };
            if result == 0 {
                let err = std::io::Error::last_os_error();
                return Err(vm.new_os_error(format!("mbcs_decode failed: {}", err)));
            }
            buffer.truncate(result as usize);