use core::convert::TryInto;

use crate::{bindings, c_types, error};

/// Fills `dest` with random bytes generated from the kernel's CSPRNG. Ensures

/// that the CSPRNG has been seeded before generating any random bytes, and

/// will block until it's ready.

pub fn getrandom(dest: &mut [u8]) -> error::KernelResult<()> {

let res = unsafe { bindings::wait_for_random_bytes() };

if res != 0 {

return Err(error::Error::from_kernel_errno(res));

}

// FIXME !

// unsafe {

// bindings::get_random_bytes(

// dest.as_mut_ptr() as *mut c_types::c_void,

// dest.len().try_into()?,

// );

// }

Ok(())

}

/// Fills `dest` with random bytes generated from the kernel's CSPRNG. If the

/// CSPRNG is not yet seeded, returns an `Err(EAGAIN)` immediately. Only

/// available on 4.19 and later kernels.

#[cfg(kernel_4_19_0_or_greater)]

pub fn getrandom_nonblock(dest: &mut [u8]) -> error::KernelResult<()> {

if !unsafe { bindings::rng_is_initialized() } {

return Err(error::Error::EAGAIN);

}

getrandom(dest)

}

/// Contributes the contents of `data` to the kernel's entropy pool. Does _not_

/// credit the kernel entropy counter though.

pub fn add_randomness(data: &[u8]) {

unsafe {

bindings::add_device_randomness(

data.as_ptr() as *const c_types::c_void,

data.len().try_into().unwrap(),

);

}

}