mem_ops.cpp

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/*
* (C) 2017 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/mem_ops.h>
#include <botan/internal/ct_utils.h>
#include <cstdlib>
#include <new>
 
#if defined(BOTAN_HAS_LOCKING_ALLOCATOR)
  #include <botan/internal/locking_allocator.h>
#endif
 
namespace Botan {
 
BOTAN_MALLOC_FN void* allocate_memory(size_t elems, size_t elem_size)
   {
   if(elems == 0 || elem_size == 0)
      return nullptr;
 
   // Some calloc implementations do not check for overflow (?!?)
   const size_t total_size = elems * elem_size;
 
   if(total_size < elems || total_size < elem_size)
      throw std::bad_alloc();
 
#if defined(BOTAN_HAS_LOCKING_ALLOCATOR)
   if(void* p = mlock_allocator::instance().allocate(elems, elem_size))
      return p;
#endif
 
#if defined(BOTAN_TARGET_OS_HAS_ALLOC_CONCEAL)
   void *ptr = ::calloc_conceal(elems, elem_size);
#else
   void* ptr = std::calloc(elems, elem_size);
#endif
   if(!ptr)
      throw std::bad_alloc();
   return ptr;
   }
 
void deallocate_memory(void* p, size_t elems, size_t elem_size)
   {
   if(p == nullptr)
      return;
 
   secure_scrub_memory(p, elems * elem_size);
 
#if defined(BOTAN_HAS_LOCKING_ALLOCATOR)
   if(mlock_allocator::instance().deallocate(p, elems, elem_size))
      return;
#endif
   std::free(p);
   }
 
void initialize_allocator()
   {
#if defined(BOTAN_HAS_LOCKING_ALLOCATOR)
   mlock_allocator::instance();
#endif
   }
 
uint8_t ct_compare_u8(const uint8_t x[],
                      const uint8_t y[],
                      size_t len)
   {
   volatile uint8_t difference = 0;
 
   for(size_t i = 0; i != len; ++i)
      difference = difference | (x[i] ^ y[i]);
 
   return CT::Mask<uint8_t>::is_zero(difference).value();
   }
 
}