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|
-- |
-- Module : Crypto.Random.Entropy.Unsafe
-- License : BSD-style
-- Maintainer : Vincent Hanquez <vincent@snarc.org>
-- Stability : experimental
-- Portability : Good
--
module Crypto.Random.Entropy.Unsafe
( replenish
, module Crypto.Random.Entropy.Backend
) where
import Data.Word (Word8)
import Foreign.Ptr (Ptr, plusPtr)
import Crypto.Random.Entropy.Backend
-- | Refill the entropy in a buffer
--
-- Call each entropy backend in turn until the buffer has
-- been replenished.
--
-- If the buffer cannot be refill after 3 loopings, this will raise
-- an User Error exception
replenish :: Int -> [EntropyBackend] -> Ptr Word8 -> IO ()
replenish _ [] _ = fail "cryptonite: random: cannot get any source of entropy on this system"
replenish poolSize backends ptr = loop 0 backends ptr poolSize
where loop :: Int -> [EntropyBackend] -> Ptr Word8 -> Int -> IO ()
loop retry [] p n | n == 0 = return ()
| retry == 3 = error "cryptonite: random: cannot fully replenish"
| otherwise = loop (retry+1) backends p n
loop _ (_:_) _ 0 = return ()
loop retry (b:bs) p n = do
r <- gatherBackend b p n
loop retry bs (p `plusPtr` r) (n - r)
|
