random.cpp
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#include "crucible/core/random.hpp"
#include "crucible/core/platform.hpp"
#if CRUCIBLE_PLATFORM_IS_POSIX_LIKE
#include <cerrno>
#include <fcntl.h>
#include <unistd.h>
#endif // CRUCIBLE_PLATFORM_IS_POSIX_LIKE
namespace crucible
{
auto read_random_bytes(std::size_t const count) -> random_result<heap_buffer<std::byte>>
{
auto buffer { make_heap_buffer<std::byte>(count) };
CRUCIBLE_TRY(read_random_bytes_into(buffer.view()));
return make_success(std::move(buffer));
}
auto read_random_bytes_into(mutable_view<std::byte> sink) -> random_result<none>
{
int const fd = ::open("/dev/urandom", O_RDONLY);
if (fd < 0) {
return make_failure<random_error>(randomness_source_unavailable {});
}
int read_status { 0 };
std::size_t bytes_read { 0 };
// ::read() is allowed to not read the whole buffer, so we do it in a loop until we're sure we're done
do {
errno = 0;
read_status = ::read(fd, sink.data() + bytes_read, sink.size() - bytes_read);
if (read_status > 0) {
bytes_read += read_status;
}
} while (bytes_read < sink.size() && read_status > 0);
if (read_status < 0 || bytes_read < sink.size()) {
return make_failure<random_error>(randomness_source_read_failed {});
}
return make_success<none>();
}
}