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// Copyright (c) 2012 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_WIN_SCOPED_HANDLE_H_
#define BASE_WIN_SCOPED_HANDLE_H_
#include "base/win/windows_types.h"
#include "base/base_export.h"
#include "base/compiler_specific.h"
#include "base/gtest_prod_util.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/macros.h"
// TODO(rvargas): remove this with the rest of the verifier.
#if defined(COMPILER_MSVC)
#include <intrin.h>
#define BASE_WIN_GET_CALLER _ReturnAddress()
#elif defined(COMPILER_GCC)
#define BASE_WIN_GET_CALLER \
__builtin_extract_return_addr(__builtin_return_address(0))
#endif
namespace base {
namespace win {
// Generic wrapper for raw handles that takes care of closing handles
// automatically. The class interface follows the style of
// the ScopedFILE class with two additions:
// - IsValid() method can tolerate multiple invalid handle values such as NULL
// and INVALID_HANDLE_VALUE (-1) for Win32 handles.
// - Set() (and the constructors and assignment operators that call it)
// preserve the Windows LastError code. This ensures that GetLastError() can
// be called after stashing a handle in a GenericScopedHandle object. Doing
// this explicitly is necessary because of bug 528394 and VC++ 2015.
template <class Traits, class Verifier>
class GenericScopedHandle {
public:
using Handle = typename Traits::Handle;
GenericScopedHandle() : handle_(Traits::NullHandle()) {}
explicit GenericScopedHandle(Handle handle) : handle_(Traits::NullHandle()) {
Set(handle);
}
GenericScopedHandle(GenericScopedHandle&& other)
: handle_(Traits::NullHandle()) {
Set(other.Take());
}
~GenericScopedHandle() { Close(); }
bool IsValid() const { return Traits::IsHandleValid(handle_); }
GenericScopedHandle& operator=(GenericScopedHandle&& other) {
DCHECK_NE(this, &other);
Set(other.Take());
return *this;
}
void Set(Handle handle) {
if (handle_ != handle) {
// Preserve old LastError to avoid bug 528394.
auto last_error = ::GetLastError();
Close();
if (Traits::IsHandleValid(handle)) {
handle_ = handle;
Verifier::StartTracking(handle, this, BASE_WIN_GET_CALLER,
GetProgramCounter());
}
::SetLastError(last_error);
}
}
Handle Get() const { return handle_; }
// Transfers ownership away from this object.
Handle Take() WARN_UNUSED_RESULT {
Handle temp = handle_;
handle_ = Traits::NullHandle();
if (Traits::IsHandleValid(temp)) {
Verifier::StopTracking(temp, this, BASE_WIN_GET_CALLER,
GetProgramCounter());
}
return temp;
}
// Explicitly closes the owned handle.
void Close() {
if (Traits::IsHandleValid(handle_)) {
Verifier::StopTracking(handle_, this, BASE_WIN_GET_CALLER,
GetProgramCounter());
Traits::CloseHandle(handle_);
handle_ = Traits::NullHandle();
}
}
private:
FRIEND_TEST_ALL_PREFIXES(ScopedHandleTest, ActiveVerifierWrongOwner);
FRIEND_TEST_ALL_PREFIXES(ScopedHandleTest, ActiveVerifierUntrackedHandle);
Handle handle_;
DISALLOW_COPY_AND_ASSIGN(GenericScopedHandle);
};
#undef BASE_WIN_GET_CALLER
// The traits class for Win32 handles that can be closed via CloseHandle() API.
class HandleTraits {
public:
using Handle = HANDLE;
// Closes the handle.
static bool BASE_EXPORT CloseHandle(HANDLE handle);
// Returns true if the handle value is valid.
static bool IsHandleValid(HANDLE handle) {
return handle != nullptr && handle != INVALID_HANDLE_VALUE;
}
// Returns NULL handle value.
static HANDLE NullHandle() { return nullptr; }
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(HandleTraits);
};
// Do-nothing verifier.
class DummyVerifierTraits {
public:
using Handle = HANDLE;
static void StartTracking(HANDLE handle,
const void* owner,
const void* pc1,
const void* pc2) {}
static void StopTracking(HANDLE handle,
const void* owner,
const void* pc1,
const void* pc2) {}
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(DummyVerifierTraits);
};
// Performs actual run-time tracking.
class BASE_EXPORT VerifierTraits {
public:
using Handle = HANDLE;
static void StartTracking(HANDLE handle,
const void* owner,
const void* pc1,
const void* pc2);
static void StopTracking(HANDLE handle,
const void* owner,
const void* pc1,
const void* pc2);
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(VerifierTraits);
};
using ScopedHandle = GenericScopedHandle<HandleTraits, VerifierTraits>;
// This function may be called by the embedder to disable the use of
// VerifierTraits at runtime. It has no effect if DummyVerifierTraits is used
// for ScopedHandle.
BASE_EXPORT void DisableHandleVerifier();
// This should be called whenever the OS is closing a handle, if extended
// verification of improper handle closing is desired. If |handle| is being
// tracked by the handle verifier and ScopedHandle is not the one closing it,
// a CHECK is generated.
BASE_EXPORT void OnHandleBeingClosed(HANDLE handle);
} // namespace win
} // namespace base
#endif // BASE_WIN_SCOPED_HANDLE_H_
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