ceph/src/boost/libs/beast/test/extras/include/boost/beast/test/fuzz.hpp

   1 //
   2 // Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // Official repository: https://github.com/boostorg/beast
   8 //
   9
  10 #ifndef BOOST_BEAST_TEST_FUZZ_HPP
  11 #define BOOST_BEAST_TEST_FUZZ_HPP
  12
  13 #include <boost/beast/core/static_string.hpp>
  14 #include <boost/beast/core/string.hpp>
  15 #include <random>
  16
  17 namespace boost {
  18 namespace beast {
  19 namespace test {
  20
  21 class fuzz_rand
  22 {
  23     std::mt19937 rng_;
  24
  25 public:
  26     std::mt19937&
  27     rng()
  28     {
  29         return rng_;
  30     }
  31
  32     template<class Unsigned>
  33     Unsigned
  34     operator()(Unsigned n)
  35     {
  36         return static_cast<Unsigned>(
  37             std::uniform_int_distribution<
  38                 Unsigned>{0, n-1}(rng_));
  39     }
  40 };
  41
  42 template<std::size_t N, class Rand, class F>
  43 static
  44 void
  45 fuzz(
  46     static_string<N> const& input,
  47     std::size_t repeat,
  48     std::size_t depth,
  49     Rand& r,
  50     F const& f)
  51 {
  52     static_string<N> mod{input};
  53     for(auto i = repeat; i; --i)
  54     {
  55         switch(r(4))
  56         {
  57         case 0: // insert
  58             if(mod.size() >= mod.max_size())
  59                 continue;
  60             mod.insert(r(mod.size() + 1), 1,
  61                 static_cast<char>(r(256)));
  62             break;
  63
  64         case 1: // erase
  65             if(mod.size() == 0)
  66                 continue;
  67             mod.erase(r(mod.size()), 1);
  68             break;
  69
  70         case 2: // swap
  71         {
  72             if(mod.size() <= 1)
  73                 continue;
  74             auto off = r(mod.size() - 1);
  75             auto const temp = mod[off];
  76             mod[off] = mod[off + 1];
  77             mod[off + 1] = temp;
  78             break;
  79         }
  80         case 3: // repeat
  81         {
  82             if(mod.empty())
  83                 continue;
  84             auto n = (std::min)(
  85                 std::geometric_distribution<
  86                     std::size_t>{}(r.rng()),
  87                 mod.max_size() - mod.size());
  88             if(n == 0)
  89                 continue;
  90             auto off = r(mod.size());
  91             mod.insert(off, n, mod[off + 1]);
  92             break;
  93         }
  94         }
  95         f(string_view{mod.data(), mod.size()});
  96         if(depth > 0)
  97             fuzz(mod, repeat, depth - 1, r, f);
  98     }
  99 }
 100
 101 } // test
 102 } // beast
 103 } // boost
 104
 105 #endif