comparison DEPENDENCIES/generic/include/boost/uuid/seed_rng.hpp @ 16:2665513ce2d3

Add boost headers

+// Boost seed_rng.hpp header file  ----------------------------------------------//
+
+// Copyright 2007 Andy Tompkins.
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// Revision History
+//  09 Nov 2007 - Initial Revision
+//  25 Feb 2008 - moved to namespace boost::uuids::detail
+//  28 Nov 2009 - disabled deprecated warnings for MSVC
+
+// seed_rng models a UniformRandomNumberGenerator (see Boost.Random).
+// Random number generators are hard to seed well.  This is intended to provide
+// good seed values for random number generators.
+// It creates random numbers from a sha1 hash of data from a variary of sources,
+// all of which are standard function calls.  It produces random numbers slowly.
+// Peter Dimov provided the details of sha1_random_digest_().
+// see http://archives.free.net.ph/message/20070507.175609.4c4f503a.en.html
+
+#ifndef BOOST_UUID_SEED_RNG_HPP
+#define BOOST_UUID_SEED_RNG_HPP
+
+#include <boost/config.hpp>
+#include <cstring> // for memcpy
+#include <limits>
+#include <ctime> // for time_t, time, clock_t, clock
+#include <cstdlib> // for rand
+#include <cstdio> // for FILE, fopen, fread, fclose
+#include <boost/uuid/sha1.hpp>
+//#include <boost/nondet_random.hpp> //forward declare boost::random::random_device
+
+// can't use boost::generator_iterator since boost::random number seed(Iter&, Iter)
+// functions need a last iterator
+//#include <boost/generator_iterator.hpp>
+# include <boost/iterator/iterator_facade.hpp>
+
+#if defined(_MSC_VER)
+#pragma warning(push) // Save warning settings.
+#pragma warning(disable : 4996) // Disable deprecated std::fopen
+#endif
+
+#ifdef BOOST_NO_STDC_NAMESPACE
+namespace std {
+    using ::memcpy;
+    using ::time_t;
+    using ::time;
+    using ::clock_t;
+    using ::clock;
+    using ::rand;
+    using ::FILE;
+    using ::fopen;
+    using ::fread;
+    using ::fclose;
+} //namespace std
+#endif
+
+// forward declare random number generators
+namespace boost { namespace random {
+class random_device;
+}} //namespace boost::random
+
+namespace boost {
+namespace uuids {
+namespace detail {
+
+// should this be part of Boost.Random?
+class seed_rng
+{
+public:
+    typedef unsigned int result_type;
+    BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
+    //BOOST_STATIC_CONSTANT(unsigned int, min_value = 0);
+    //BOOST_STATIC_CONSTANT(unsigned int, max_value = UINT_MAX);
+
+public:
+    // note: rd_ intentionally left uninitialized
+    seed_rng()
+        : rd_index_(5)
+        , random_(std::fopen( "/dev/urandom", "rb" ))
+    {}
+
+    ~seed_rng()
+    {
+        if (random_) {
+            std::fclose(random_);
+        }
+    }
+
+    result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const
+    {
+        return (std::numeric_limits<result_type>::min)();
+    }
+    result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const
+    {
+        return (std::numeric_limits<result_type>::max)();
+    }
+
+    result_type operator()()
+    {
+        if (rd_index_ >= 5) {
+            //get new digest
+            sha1_random_digest_();
+
+            rd_index_ = 0;
+        }
+
+        return rd_[rd_index_++];
+    }
+
+private:
+    inline void ignore_size(size_t) {}
+
+    static unsigned int * sha1_random_digest_state_()
+    {
+        static unsigned int state[ 5 ];
+        return state;
+    }
+
+    void sha1_random_digest_()
+    {
+        boost::uuids::detail::sha1 sha;
+
+        unsigned int * ps = sha1_random_digest_state_();
+
+        unsigned int state[ 5 ];
+        std::memcpy( state, ps, sizeof( state ) ); // harmless data race
+
+        sha.process_bytes( (unsigned char const*)state, sizeof( state ) );
+        sha.process_bytes( (unsigned char const*)&ps, sizeof( ps ) );
+
+        {
+            std::time_t tm = std::time( 0 );
+            sha.process_bytes( (unsigned char const*)&tm, sizeof( tm ) );
+        }
+
+        {
+            std::clock_t ck = std::clock();
+            sha.process_bytes( (unsigned char const*)&ck, sizeof( ck ) );
+        }
+
+        {
+            unsigned int rn[] =
+                { static_cast<unsigned int>(std::rand())
+                , static_cast<unsigned int>(std::rand())
+                , static_cast<unsigned int>(std::rand())
+                };
+            sha.process_bytes( (unsigned char const*)rn, sizeof( rn ) );
+        }
+
+        {
+            // intentionally left uninitialized
+            unsigned char buffer[ 20 ];
+
+            if(random_)
+            {
+                ignore_size(std::fread( buffer, 1, 20, random_ ));
+            }
+
+            // using an uninitialized buffer[] if fopen fails
+            // intentional, we rely on its contents being random
+            sha.process_bytes( buffer, sizeof( buffer ) );
+        }
+
+        {
+            // *p is intentionally left uninitialized
+            unsigned int * p = new unsigned int;
+
+            sha.process_bytes( (unsigned char const*)p, sizeof( *p ) );
+            sha.process_bytes( (unsigned char const*)&p, sizeof( p ) );
+
+            delete p;
+        }
+
+        sha.process_bytes( (unsigned char const*)rd_, sizeof( rd_ ) );
+
+        unsigned int digest[ 5 ];
+        sha.get_digest( digest );
+
+        for( int i = 0; i < 5; ++i )
+        {
+            // harmless data race
+            ps[ i ] ^= digest[ i ];
+            rd_[ i ] ^= digest[ i ];
+        }
+    }
+
+private:
+    unsigned int rd_[5];
+    int rd_index_;
+    std::FILE * random_;
+
+private: // make seed_rng noncopyable
+    seed_rng(seed_rng const&);
+    seed_rng& operator=(seed_rng const&);
+};
+
+// almost a copy of boost::generator_iterator
+// but default constructor sets m_g to NULL
+template <class Generator>
+class generator_iterator
+  : public iterator_facade<
+        generator_iterator<Generator>
+      , typename Generator::result_type
+      , single_pass_traversal_tag
+      , typename Generator::result_type const&
+    >
+{
+    typedef iterator_facade<
+        generator_iterator<Generator>
+      , typename Generator::result_type
+      , single_pass_traversal_tag
+      , typename Generator::result_type const&
+    > super_t;
+
+ public:
+    generator_iterator() : m_g(NULL), m_value(0) {}
+    generator_iterator(Generator* g) : m_g(g), m_value((*m_g)()) {}
+
+    void increment()
+    {
+        m_value = (*m_g)();
+    }
+
+    const typename Generator::result_type&
+    dereference() const
+    {
+        return m_value;
+    }
+
+    bool equal(generator_iterator const& y) const
+    {
+        return this->m_g == y.m_g && this->m_value == y.m_value;
+    }
+
+ private:
+    Generator* m_g;
+    typename Generator::result_type m_value;
+};
+
+// seed() seeds a random number generator with good seed values
+
+template <typename UniformRandomNumberGenerator>
+inline void seed(UniformRandomNumberGenerator& rng)
+{
+    seed_rng seed_gen;
+    generator_iterator<seed_rng> begin(&seed_gen);
+    generator_iterator<seed_rng> end;
+    rng.seed(begin, end);
+}
+
+// random_device does not / can not be seeded
+template <>
+inline void seed<boost::random::random_device>(boost::random::random_device&) {}
+
+// random_device does not / can not be seeded
+template <>
+inline void seed<seed_rng>(seed_rng&) {}
+
+}}} //namespace boost::uuids::detail
+
+#if defined(_MSC_VER)
+#pragma warning(pop) // Restore warnings to previous state.
+#endif
+
+#endif