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- //
- // Copyright (c) 2018 Andrey Semashev
- //
- // Distributed under the Boost Software License, Version 1.0.
- // (See accompanying file LICENSE_1_0.txt or copy at
- // https://www.boost.org/LICENSE_1_0.txt)
- //
- // getrandom() capable platforms
- //
- #include <boost/config.hpp>
- #include <boost/throw_exception.hpp>
- #include <boost/predef/library/c/gnu.h>
- #include <cerrno>
- #include <cstddef>
- #if !defined(BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_IMPL_GETRANDOM)
- #if BOOST_LIB_C_GNU >= BOOST_VERSION_NUMBER(2, 25, 0)
- #define BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_HAS_LIBC_WRAPPER
- #elif defined(__has_include)
- #if __has_include(<sys/random.h>)
- #define BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_HAS_LIBC_WRAPPER
- #endif
- #endif
- #endif // !defined(BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_IMPL_GETRANDOM)
- #if defined(BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_HAS_LIBC_WRAPPER)
- #include <sys/random.h>
- #else
- #include <stddef.h> // ssize_t
- #endif
- namespace boost {
- namespace uuids {
- namespace detail {
- class random_provider_base
- {
- public:
- //! Obtain entropy and place it into a memory location
- //! \param[in] buf the location to write entropy
- //! \param[in] siz the number of bytes to acquire
- void get_random_bytes(void *buf, std::size_t siz)
- {
- std::size_t offset = 0;
- while (offset < siz)
- {
- ssize_t sz = get_random(static_cast< char* >(buf) + offset, siz - offset, 0u);
- if (BOOST_UNLIKELY(sz < 0))
- {
- int err = errno;
- if (err == EINTR)
- continue;
- BOOST_THROW_EXCEPTION(entropy_error(err, "getrandom"));
- }
- offset += sz;
- }
- }
- private:
- static ssize_t get_random(void *buf, std::size_t size, unsigned int flags)
- {
- #if defined(BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_IMPL_GETRANDOM)
- return BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_IMPL_GETRANDOM(buf, size, flags);
- #elif defined(BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_HAS_LIBC_WRAPPER)
- return ::getrandom(buf, size, flags);
- #else
- return ::syscall(SYS_getrandom, buf, size, flags);
- #endif
- }
- };
- } // detail
- } // uuids
- } // boost
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