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// Copyright Oliver Kowalke 2014.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H
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#define BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H
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extern "C" {
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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}
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#include <cmath>
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#include <cstddef>
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#include <new>
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#include <boost/assert.hpp>
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#include <boost/config.hpp>
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#include <boost/core/ignore_unused.hpp>
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#include <boost/context/detail/config.hpp>
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#include <boost/context/stack_context.hpp>
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#include <boost/context/stack_traits.hpp>
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#if defined(BOOST_USE_VALGRIND)
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#include <valgrind/valgrind.h>
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#endif
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#ifdef BOOST_HAS_ABI_HEADERS
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# include BOOST_ABI_PREFIX
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#endif
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namespace boost {
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namespace context {
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template< typename traitsT >
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class basic_protected_fixedsize_stack {
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private:
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std::size_t size_;
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public:
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typedef traitsT traits_type;
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basic_protected_fixedsize_stack( std::size_t size = traits_type::default_size() ) BOOST_NOEXCEPT_OR_NOTHROW :
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size_( size) {
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}
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stack_context allocate() {
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// calculate how many pages are required
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const std::size_t pages(
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static_cast< std::size_t >(
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std::ceil(
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static_cast< float >( size_) / traits_type::page_size() ) ) );
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// add one page at bottom that will be used as guard-page
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const std::size_t size__ = ( pages + 1) * traits_type::page_size();
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#if defined(BOOST_CONTEXT_USE_MAP_STACK)
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void * vp = ::mmap( 0, size__, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_STACK, -1, 0);
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#elif defined(MAP_ANON)
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void * vp = ::mmap( 0, size__, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
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#else
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void * vp = ::mmap( 0, size__, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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#endif
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if ( MAP_FAILED == vp) throw std::bad_alloc();
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// conforming to POSIX.1-2001
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const int result( ::mprotect( vp, traits_type::page_size(), PROT_NONE) );
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boost::ignore_unused(result);
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BOOST_ASSERT( 0 == result);
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stack_context sctx;
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sctx.size = size__;
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sctx.sp = static_cast< char * >( vp) + sctx.size;
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#if defined(BOOST_USE_VALGRIND)
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sctx.valgrind_stack_id = VALGRIND_STACK_REGISTER( sctx.sp, vp);
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#endif
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return sctx;
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}
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void deallocate( stack_context & sctx) BOOST_NOEXCEPT_OR_NOTHROW {
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BOOST_ASSERT( sctx.sp);
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#if defined(BOOST_USE_VALGRIND)
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VALGRIND_STACK_DEREGISTER( sctx.valgrind_stack_id);
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#endif
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void * vp = static_cast< char * >( sctx.sp) - sctx.size;
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// conform to POSIX.4 (POSIX.1b-1993, _POSIX_C_SOURCE=199309L)
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::munmap( vp, sctx.size);
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}
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};
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typedef basic_protected_fixedsize_stack< stack_traits > protected_fixedsize_stack;
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}}
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#ifdef BOOST_HAS_ABI_HEADERS
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# include BOOST_ABI_SUFFIX
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#endif
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#endif // BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H
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