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-rw-r--r--base/mac/scoped_mach_vm.h92
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diff --git a/base/mac/scoped_mach_vm.h b/base/mac/scoped_mach_vm.h
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--- a/base/mac/scoped_mach_vm.h
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-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef BASE_MAC_SCOPED_MACH_VM_H_
-#define BASE_MAC_SCOPED_MACH_VM_H_
-
-#include <mach/mach.h>
-
-#include <algorithm>
-
-#include "base/base_export.h"
-#include "base/basictypes.h"
-#include "base/logging.h"
-
-// Use ScopedMachVM to supervise ownership of pages in the current process
-// through the Mach VM subsystem. Pages allocated with vm_allocate can be
-// released when exiting a scope with ScopedMachVM.
-//
-// The Mach VM subsystem operates on a page-by-page basis, and a single VM
-// allocation managed by a ScopedMachVM object may span multiple pages. As far
-// as Mach is concerned, allocated pages may be deallocated individually. This
-// is in contrast to higher-level allocators such as malloc, where the base
-// address of an allocation implies the size of an allocated block.
-// Consequently, it is not sufficient to just pass the base address of an
-// allocation to ScopedMachVM, it also needs to know the size of the
-// allocation. To avoid any confusion, both the base address and size must
-// be page-aligned.
-//
-// When dealing with Mach VM, base addresses will naturally be page-aligned,
-// but user-specified sizes may not be. If there's a concern that a size is
-// not page-aligned, use the mach_vm_round_page macro to correct it.
-//
-// Example:
-//
-// vm_address_t address = 0;
-// vm_size_t size = 12345; // This requested size is not page-aligned.
-// kern_return_t kr =
-// vm_allocate(mach_task_self(), &address, size, VM_FLAGS_ANYWHERE);
-// if (kr != KERN_SUCCESS) {
-// return false;
-// }
-// ScopedMachVM vm_owner(address, mach_vm_round_page(size));
-
-namespace base {
-namespace mac {
-
-class BASE_EXPORT ScopedMachVM {
- public:
- explicit ScopedMachVM(vm_address_t address = 0, vm_size_t size = 0)
- : address_(address), size_(size) {
- DCHECK_EQ(address % PAGE_SIZE, 0u);
- DCHECK_EQ(size % PAGE_SIZE, 0u);
- }
-
- ~ScopedMachVM() {
- if (size_) {
- vm_deallocate(mach_task_self(), address_, size_);
- }
- }
-
- void reset(vm_address_t address = 0, vm_size_t size = 0);
-
- vm_address_t address() const {
- return address_;
- }
-
- vm_size_t size() const {
- return size_;
- }
-
- void swap(ScopedMachVM& that) {
- std::swap(address_, that.address_);
- std::swap(size_, that.size_);
- }
-
- void release() {
- address_ = 0;
- size_ = 0;
- }
-
- private:
- vm_address_t address_;
- vm_size_t size_;
-
- DISALLOW_COPY_AND_ASSIGN(ScopedMachVM);
-};
-
-} // namespace mac
-} // namespace base
-
-#endif // BASE_MAC_SCOPED_MACH_VM_H_