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// Copyright Oliver Kowalke 2014.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H
#define BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H
extern "C" {
#include <windows.h>
}
#include <cmath>
#include <cstddef>
#include <new>
#include <boost/config.hpp>
#include <boost/context/detail/config.hpp>
#include <boost/context/stack_context.hpp>
#include <boost/context/stack_traits.hpp>
#ifdef BOOST_HAS_ABI_HEADERS
# include BOOST_ABI_PREFIX
#endif
namespace boost {
namespace context {
template< typename traitsT >
class basic_protected_fixedsize_stack {
private:
std::size_t size_;
public:
typedef traitsT traits_type;
basic_protected_fixedsize_stack( std::size_t size = traits_type::default_size() ) BOOST_NOEXCEPT_OR_NOTHROW :
size_( size) {
}
stack_context allocate() {
// page at bottom will be used as guard-page
const std::size_t pages(
static_cast< std::size_t >(
std::floor(
static_cast< float >( size_) / traits_type::page_size() ) ) );
BOOST_ASSERT_MSG( 2 <= pages, "at least two pages must fit into stack (one page is guard-page)");
const std::size_t size__( pages * traits_type::page_size() );
BOOST_ASSERT( 0 != size_ && 0 != size__);
BOOST_ASSERT( size__ <= size_);
void * vp = ::VirtualAlloc( 0, size__, MEM_COMMIT, PAGE_READWRITE);
if ( ! vp) throw std::bad_alloc();
DWORD old_options;
#if defined(BOOST_DISABLE_ASSERTS)
::VirtualProtect(
vp, traits_type::page_size(), PAGE_READWRITE | PAGE_GUARD /*PAGE_NOACCESS*/, & old_options);
#else
const BOOL result = ::VirtualProtect(
vp, traits_type::page_size(), PAGE_READWRITE | PAGE_GUARD /*PAGE_NOACCESS*/, & old_options);
BOOST_ASSERT( FALSE != result);
#endif
stack_context sctx;
sctx.size = size__;
sctx.sp = static_cast< char * >( vp) + sctx.size;
return sctx;
}
void deallocate( stack_context & sctx) BOOST_NOEXCEPT_OR_NOTHROW {
BOOST_ASSERT( sctx.sp);
void * vp = static_cast< char * >( sctx.sp) - sctx.size;
::VirtualFree( vp, 0, MEM_RELEASE);
}
};
typedef basic_protected_fixedsize_stack< stack_traits > protected_fixedsize_stack;
}}
#ifdef BOOST_HAS_ABI_HEADERS
# include BOOST_ABI_SUFFIX
#endif
#endif // BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H
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