Function sys_read_entropy 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn sys_read_entropy(
    buf: *mut u8,
    len: usize,
    flags: u32,
) -> isize

Fill len bytes in buf with cryptographically secure random data.

Returns either the number of bytes written to buf (a positive value) or

• -EINVAL if flags contains unknown flags.
• -ENOSYS if the system does not support random data generation.