Function sigtimedwait 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn sigtimedwait(
    set: *const sigset_t,
    sig: *mut siginfo,
    tp: *const timespec,
) -> c_int

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/sigtimedwait.html.

Equivalent to sigwaitinfo() except that if none of the signals specified by set are pending, wait for the time interval specified in the timespec structure referenced by timeout. Shall return immediately with an error if timeout is zero-valued and none of the signals specified by set are pending.

Upon success, returns the selected signal number. Upon failure, returns -1 and sets errno to indicate the error.

Safety

If timeout is the null pointer, behaviour is unspecified.