/*

* System Call getentropy(2)

* (C) 2017 Alexander Bluhm (genua GmbH)

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include <botan/internal/getentropy.h>

#include <botan/rng.h>

#include <unistd.h>

// macOS and Android include it in sys/random.h instead

#if __has_include(<sys/random.h>)

   #include <sys/random.h>

#endif

namespace Botan {

/**

* Gather 256 bytes entropy from getentropy(2).  Note that maximum

* buffer size is limited to 256 bytes.  On OpenBSD this does neither

* block nor fail.

*/

size_t Getentropy::poll(RandomNumberGenerator& rng) {

   secure_vector<uint8_t> buf(256);

   if(::getentropy(buf.data(), buf.size()) == 0) {

      rng.add_entropy(buf.data(), buf.size());

      return buf.size() * 8;

   }

   return 0;

}

}  // namespace Botan