/*

* Safe(r) Integer Handling

* (C) 2016 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#ifndef BOTAN_UTILS_SAFE_INT_H_

#define BOTAN_UTILS_SAFE_INT_H_

#include <botan/exceptn.h>

#include <string>

namespace Botan {

class Integer_Overflow_Detected final : public Exception

   {

   public:

      Integer_Overflow_Detected(const std::string& file, int line) :

         Exception("Integer overflow detected at " + file + ":" + std::to_string(line))

         {}

      ErrorType error_type() const noexcept override { return ErrorType::InternalError; }

   };

inline size_t checked_add(size_t x, size_t y, const char* file, int line)

   {

   // TODO: use __builtin_x_overflow on GCC and Clang

   size_t z = x + y;

   if(z < x)

      {

      throw Integer_Overflow_Detected(file, line);

      }

   return z;

   }

template<typename RT, typename AT>

RT checked_cast_to(AT i)

   {

   RT c = static_cast<RT>(i);

   if(i != static_cast<AT>(c))

      throw Internal_Error("Error during integer conversion");

   return c;

   }

#define BOTAN_CHECKED_ADD(x,y) checked_add(x,y,__FILE__,__LINE__)

}

#endif