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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.
// Provides a way to handle exceptions that happen while a WindowProc is
// running. The behavior of exceptions generated inside a WindowProc is OS
// dependent, but it is possible that the OS just ignores the exception and
// continues execution, which leads to unpredictable behavior for Chrome.
#ifndef BASE_WIN_WRAPPED_WINDOW_PROC_H_
#define BASE_WIN_WRAPPED_WINDOW_PROC_H_
#include <windows.h>
#include "base/base_export.h"
#include "base/strings/string16.h"
namespace base {
namespace win {
// An exception filter for a WindowProc. The return value determines how the
// exception should be handled, following standard SEH rules. However, the
// expected behavior for this function is to not return, instead of returning
// EXCEPTION_EXECUTE_HANDLER or similar, given that in general we are not
// prepared to handle exceptions.
typedef int (__cdecl *WinProcExceptionFilter)(EXCEPTION_POINTERS* info);
// Sets the filter to deal with exceptions inside a WindowProc. Returns the old
// exception filter, if any.
// This function should be called before any window is created.
BASE_EXPORT WinProcExceptionFilter SetWinProcExceptionFilter(
WinProcExceptionFilter filter);
// Calls the registered exception filter.
BASE_EXPORT int CallExceptionFilter(EXCEPTION_POINTERS* info);
// Initializes the WNDCLASSEX structure |*class_out| to be passed to
// RegisterClassEx() making sure that it is associated with the module
// containing the window procedure.
BASE_EXPORT void InitializeWindowClass(
const char16* class_name,
WNDPROC window_proc,
UINT style,
int class_extra,
int window_extra,
HCURSOR cursor,
HBRUSH background,
const char16* menu_name,
HICON large_icon,
HICON small_icon,
WNDCLASSEX* class_out);
// Wrapper that supplies a standard exception frame for the provided WindowProc.
// The normal usage is something like this:
//
// LRESULT CALLBACK MyWinProc(HWND hwnd, UINT message,
// WPARAM wparam, LPARAM lparam) {
// // Do Something.
// }
//
// ...
//
// WNDCLASSEX wc = {0};
// wc.lpfnWndProc = WrappedWindowProc<MyWinProc>;
// wc.lpszClassName = class_name;
// ...
// RegisterClassEx(&wc);
//
// CreateWindowW(class_name, window_name, ...
//
template <WNDPROC proc>
LRESULT CALLBACK WrappedWindowProc(HWND hwnd, UINT message,
WPARAM wparam, LPARAM lparam) {
LRESULT rv = 0;
__try {
rv = proc(hwnd, message, wparam, lparam);
} __except(CallExceptionFilter(GetExceptionInformation())) {
}
return rv;
}
} // namespace win
} // namespace base
#endif // BASE_WIN_WRAPPED_WINDOW_PROC_H_
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