+++ /dev/null
-/*
- * Copyright (C) 2010 Apple Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#ifndef PageReservation_h
-#define PageReservation_h
-
-#include <wtf/PageAllocation.h>
-
-namespace WTF {
-
-/*
- PageReservation
-
- Like PageAllocation, the PageReservation class provides a cross-platform memory
- allocation interface, but with a set of capabilities more similar to that of
- VirtualAlloc than posix mmap. PageReservation can be used to allocate virtual
- memory without committing physical memory pages using PageReservation::reserve.
- Following a call to reserve all memory in the region is in a decommited state,
- in which the memory should not be used (accessing the memory may cause a fault).
-
- Before using memory it must be committed by calling commit, which is passed start
- and size values (both of which require system page size granularity). One the
- committed memory is no longer needed 'decommit' may be called to return the
- memory to its devommitted state. Commit should only be called on memory that is
- currently decommitted, and decommit should only be called on memory regions that
- are currently committed. All memory should be decommited before the reservation
- is deallocated. Values in memory may not be retained accross a pair of calls if
- the region of memory is decommitted and then committed again.
-
- Memory protection should not be changed on decommitted memory, and if protection
- is changed on memory while it is committed it should be returned to the orignal
- protection before decommit is called.
-*/
-
-class PageReservation : private PageBlock {
-public:
- PageReservation()
- : m_committed(0)
- , m_writable(false)
- , m_executable(false)
- {
- }
-
- using PageBlock::base;
- using PageBlock::size;
-
-#ifndef __clang__
- using PageBlock::operator bool;
-#else
- // FIXME: This is a workaround for <rdar://problem/8876150>, wherein Clang incorrectly emits an access
- // control warning when a client tries to use operator bool exposed above via "using PageBlock::operator bool".
- operator bool() const { return PageBlock::operator bool(); }
-#endif
-
- void commit(void* start, size_t size)
- {
- ASSERT(*this);
- ASSERT(isPageAligned(start));
- ASSERT(isPageAligned(size));
- ASSERT(contains(start, size));
-
- m_committed += size;
- OSAllocator::commit(start, size, m_writable, m_executable);
- }
-
- void decommit(void* start, size_t size)
- {
- ASSERT(*this);
- ASSERT(isPageAligned(start));
- ASSERT(isPageAligned(size));
- ASSERT(contains(start, size));
-
- m_committed -= size;
- OSAllocator::decommit(start, size);
- }
-
- size_t committed()
- {
- return m_committed;
- }
-
- static PageReservation reserve(size_t size, OSAllocator::Usage usage = OSAllocator::UnknownUsage, bool writable = true, bool executable = false)
- {
- ASSERT(isPageAligned(size));
- return PageReservation(OSAllocator::reserveUncommitted(size, usage, writable, executable), size, writable, executable, false);
- }
-
- static PageReservation reserveWithGuardPages(size_t size, OSAllocator::Usage usage = OSAllocator::UnknownUsage, bool writable = true, bool executable = false)
- {
- ASSERT(isPageAligned(size));
- return PageReservation(OSAllocator::reserveUncommitted(size + pageSize() * 2, usage, writable, executable, true), size, writable, executable, true);
- }
-
- void deallocate()
- {
- ASSERT(!m_committed);
-
- // Clear base & size before calling release; if this is *inside* allocation
- // then we won't be able to clear then after deallocating the memory.
- PageReservation tmp;
- std::swap(tmp, *this);
-
- ASSERT(tmp);
- ASSERT(!*this);
-
- OSAllocator::releaseDecommitted(tmp.base(), tmp.size());
- }
-
-private:
- PageReservation(void* base, size_t size, bool writable, bool executable, bool hasGuardPages)
- : PageBlock(base, size, hasGuardPages)
- , m_committed(0)
- , m_writable(writable)
- , m_executable(executable)
- {
- }
-
- size_t m_committed;
- bool m_writable;
- bool m_executable;
-};
-
-}
-
-using WTF::PageReservation;
-
-#endif // PageReservation_h
projects / apple / javascriptcore.git / blobdiff