Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include <cstring>
       4             : #include <cassert>
       5             : #include <type_traits>
       6             : #include <vector>
       7             : #include <string>
       8             : #include <atomic>
       9             : 
      10             : #ifdef __INTEL_COMPILER
      11             : #pragma warning(disable : 597) // will not be called for implicit or explicit conversions
      12             : #endif
      13             : 
      14             : namespace dev {
      15             : 
      16             : /**
      17             :  * A modifiable reference to an existing object or vector in memory.
      18             :  */
      19             : template<class _T>
      20             : class vector_ref
      21             : {
      22             : public:
      23             :     using value_type = _T;
      24             :     using element_type = _T;
      25             :     using mutable_value_type = typename std::
      26             :         conditional<std::is_const<_T>::value, typename std::remove_const<_T>::type, _T>::type;
      27             : 
      28             :     static_assert(std::is_pod<value_type>::value,
      29             :                   "vector_ref can only be used with PODs due to its low-level treatment of data.");
      30             : 
      31          44 :     vector_ref()
      32          44 :         : m_data(nullptr)
      33          44 :         , m_count(0)
      34          44 :     {}
      35             :     /// Creates a new vector_ref to point to @a _count elements starting at @a _data.
      36        7659 :     vector_ref(_T* _data, size_t _count)
      37        7659 :         : m_data(_data)
      38        7659 :         , m_count(_count)
      39        7659 :     {}
      40             :     /// Creates a new vector_ref pointing to the data part of a string (given as pointer).
      41             :     vector_ref(
      42             :         typename std::conditional<std::is_const<_T>::value, std::string const*, std::string*>::type
      43             :             _data)
      44             :         : m_data(reinterpret_cast<_T*>(_data->data()))
      45             :         , m_count(_data->size() / sizeof(_T))
      46             :     {}
      47             :     /// Creates a new vector_ref pointing to the data part of a vector (given as pointer).
      48             :     vector_ref(typename std::conditional<std::is_const<_T>::value,
      49             :                                          std::vector<typename std::remove_const<_T>::type> const*,
      50             :                                          std::vector<_T>*>::type _data)
      51             :         : m_data(_data->data())
      52             :         , m_count(_data->size())
      53             :     {}
      54             :     /// Creates a new vector_ref pointing to the data part of a string (given as reference).
      55             :     vector_ref(
      56             :         typename std::conditional<std::is_const<_T>::value, std::string const&, std::string&>::type
      57             :             _data)
      58             :         : m_data(reinterpret_cast<_T*>(_data.data()))
      59             :         , m_count(_data.size() / sizeof(_T))
      60             :     {}
      61             :     explicit operator bool() const { return m_data && m_count; }
      62             : 
      63             :     bool contentsEqual(std::vector<mutable_value_type> const& _c) const
      64             :     {
      65             :         if (!m_data || m_count == 0)
      66             :             return _c.empty();
      67             :         else
      68             :             return _c.size() == m_count && !memcmp(_c.data(), m_data, m_count * sizeof(_T));
      69             :     }
      70             :     std::vector<mutable_value_type> toVector() const
      71             :     {
      72             :         return std::vector<mutable_value_type>(m_data, m_data + m_count);
      73             :     }
      74             :     std::vector<unsigned char> toBytes() const
      75             :     {
      76             :         return std::vector<unsigned char>(reinterpret_cast<unsigned char const*>(m_data),
      77             :                                           reinterpret_cast<unsigned char const*>(m_data)
      78             :                                               + m_count * sizeof(_T));
      79             :     }
      80             :     std::string toString() const
      81             :     {
      82             :         return std::string((char const*) m_data, ((char const*) m_data) + m_count * sizeof(_T));
      83             :     }
      84             : 
      85             :     template<class _T2>
      86             :     explicit operator vector_ref<_T2>() const
      87             :     {
      88             :         assert(m_count * sizeof(_T) / sizeof(_T2) * sizeof(_T2) / sizeof(_T) == m_count);
      89             :         return vector_ref<_T2>(reinterpret_cast<_T2*>(m_data), m_count * sizeof(_T) / sizeof(_T2));
      90             :     }
      91             :     operator vector_ref<_T const>() const { return vector_ref<_T const>(m_data, m_count); }
      92             : 
      93        3134 :     _T* data() const { return m_data; }
      94             :     /// @returns the number of elements referenced (not necessarily number of bytes).
      95             :     size_t count() const { return m_count; }
      96             :     /// @returns the number of elements referenced (not necessarily number of bytes).
      97        3134 :     size_t size() const { return m_count; }
      98             :     bool empty() const { return !m_count; }
      99             :     /// @returns a new vector_ref pointing at the next chunk of @a size() elements.
     100             :     vector_ref<_T> next() const
     101             :     {
     102             :         if (!m_data)
     103             :             return *this;
     104             :         else
     105             :             return vector_ref<_T>(m_data + m_count, m_count);
     106             :     }
     107             :     /// @returns a new vector_ref which is a shifted and shortened view of the original data.
     108             :     /// If this goes out of bounds in any way, returns an empty vector_ref.
     109             :     /// If @a _count is ~size_t(0), extends the view to the end of the data.
     110             :     vector_ref<_T> cropped(size_t _begin, size_t _count) const
     111             :     {
     112             :         if (m_data && _begin <= m_count && _count <= m_count && _begin + _count <= m_count)
     113             :             return vector_ref<_T>(m_data + _begin, _count == ~size_t(0) ? m_count - _begin : _count);
     114             :         else
     115             :             return vector_ref<_T>();
     116             :     }
     117             :     /// @returns a new vector_ref which is a shifted view of the original data (not going beyond it).
     118             :     vector_ref<_T> cropped(size_t _begin) const
     119             :     {
     120             :         if (m_data && _begin <= m_count)
     121             :             return vector_ref<_T>(m_data + _begin, m_count - _begin);
     122             :         else
     123             :             return vector_ref<_T>();
     124             :     }
     125             :     void retarget(_T* _d, size_t _s)
     126             :     {
     127             :         m_data = _d;
     128             :         m_count = _s;
     129             :     }
     130             :     void retarget(std::vector<_T> const& _t)
     131             :     {
     132             :         m_data = _t.data();
     133             :         m_count = _t.size();
     134             :     }
     135             :     /// Securely overwrite the memory.
     136             :     /// @note adapted from OpenSSL's implementation.
     137        3785 :     void cleanse()
     138             :     {
     139             :         static std::atomic<unsigned char> s_cleanseCounter {0u};
     140        3785 :         uint8_t* p = (uint8_t*) begin();
     141        3785 :         size_t const len = (uint8_t*) end() - p;
     142        3785 :         size_t loop = len;
     143        3785 :         size_t count = s_cleanseCounter;
     144      124905 :         while (loop--) {
     145      121120 :             *(p++) = (uint8_t) count;
     146      121120 :             count += (17 + ((size_t) p & 0xf));
     147             :         }
     148        3785 :         p = (uint8_t*) memchr((uint8_t*) begin(), (uint8_t) count, len);
     149        3785 :         if (p)
     150           0 :             count += (63 + (size_t) p);
     151        3785 :         s_cleanseCounter = (uint8_t) count;
     152        3785 :         memset((uint8_t*) begin(), 0, len);
     153        3785 :     }
     154             : 
     155       11355 :     _T* begin() { return m_data; }
     156        3785 :     _T* end() { return m_data + m_count; }
     157         784 :     _T const* begin() const { return m_data; }
     158         784 :     _T const* end() const { return m_data + m_count; }
     159             : 
     160             :     _T& operator[](size_t _i)
     161             :     {
     162             :         assert(m_data);
     163             :         assert(_i < m_count);
     164             :         return m_data[_i];
     165             :     }
     166             :     _T const& operator[](size_t _i) const
     167             :     {
     168             :         assert(m_data);
     169             :         assert(_i < m_count);
     170             :         return m_data[_i];
     171             :     }
     172             : 
     173             :     bool operator==(vector_ref<_T> const& _cmp) const
     174             :     {
     175             :         return m_data == _cmp.m_data && m_count == _cmp.m_count;
     176             :     }
     177             :     bool operator!=(vector_ref<_T> const& _cmp) const { return !operator==(_cmp); }
     178             : 
     179             :     void reset()
     180             :     {
     181             :         m_data = nullptr;
     182             :         m_count = 0;
     183             :     }
     184             : 
     185             : private:
     186             :     _T* m_data;
     187             :     size_t m_count;
     188             : };
     189             : 
     190             : template<class _T>
     191             : vector_ref<_T const>
     192             : ref(_T const& _t)
     193             : {
     194             :     return vector_ref<_T const>(&_t, 1);
     195             : }
     196             : template<class _T>
     197             : vector_ref<_T>
     198             : ref(_T& _t)
     199             : {
     200             :     return vector_ref<_T>(&_t, 1);
     201             : }
     202             : template<class _T>
     203             : vector_ref<_T const>
     204             : ref(std::vector<_T> const& _t)
     205             : {
     206             :     return vector_ref<_T const>(&_t);
     207             : }
     208             : template<class _T>
     209             : vector_ref<_T>
     210             : ref(std::vector<_T>& _t)
     211             : {
     212             :     return vector_ref<_T>(&_t);
     213             : }
     214             : 
     215             : } // namespace dev