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