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/*
* Mlock Allocator
* (C) 2012,2014,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/locking_allocator.h>
#include <botan/internal/os_utils.h>
#include <botan/internal/mem_pool.h>
namespace Botan {
void* mlock_allocator::allocate(size_t num_elems, size_t elem_size)
{
if(!m_pool)
return nullptr;
const size_t n = num_elems * elem_size;
if(n / elem_size != num_elems)
return nullptr; // overflow!
return m_pool->allocate(n);
}
bool mlock_allocator::deallocate(void* p, size_t num_elems, size_t elem_size) noexcept
{
if(!m_pool)
return false;
size_t n = num_elems * elem_size;
/*
We return nullptr in allocate if there was an overflow, so if an
overflow occurs here we know the pointer was not allocated by this pool.
*/
if(n / elem_size != num_elems)
return false;
return m_pool->deallocate(p, n);
}
mlock_allocator::mlock_allocator()
{
const size_t mem_to_lock = OS::get_memory_locking_limit();
const size_t page_size = OS::system_page_size();
if(mem_to_lock > 0 && mem_to_lock % page_size == 0)
{
m_locked_pages = OS::allocate_locked_pages(mem_to_lock / page_size);
if(m_locked_pages.size() > 0)
{
m_pool.reset(new Memory_Pool(m_locked_pages, page_size));
}
}
}
mlock_allocator::~mlock_allocator()
{
if(m_pool)
{
m_pool.reset();
// OS::free_locked_pages scrubs the memory before free
OS::free_locked_pages(m_locked_pages);
}
}
mlock_allocator& mlock_allocator::instance()
{
static mlock_allocator mlock;
return mlock;
}
}