59 lines
2 KiB
C++
59 lines
2 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:expandtab:shiftwidth=4:tabstop=4:
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*/
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsGtkUtils_h__
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#define nsGtkUtils_h__
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#include <glib.h>
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// Some gobject functions expect functions for gpointer arguments.
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// gpointer is void* but C++ doesn't like casting functions to void*.
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template <class T>
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static inline gpointer FuncToGpointer(T aFunction) {
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return reinterpret_cast<gpointer>(
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reinterpret_cast<uintptr_t>
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// This cast just provides a warning if T is not a function.
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(reinterpret_cast<void (*)()>(aFunction)));
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}
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// Type-safe alternative to glib's g_clear_pointer.
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//
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// Using `g_clear_pointer` itself causes UBSan to report undefined
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// behavior. The function-based definition of `g_clear_pointer` (as
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// opposed to the older preprocessor macro) treats the `destroy`
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// function as a `void (*)(void *)`, but the actual destroy functions
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// that are used (say `wl_buffer_destroy`) usually have more specific
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// pointer types.
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//
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// C++ draft n4901 [expr.call] para 6:
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//
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// Calling a function through an expression whose function type E
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// is different from the function type F of the called function’s
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// definition results in undefined behavior unless the type
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// “pointer to F” can be converted to the type “pointer to E” via
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// a function pointer conversion (7.3.14).
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//
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// §7.3.14 only talks about converting between noexcept and ordinary
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// function pointers.
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template <class T>
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static inline void MozClearPointer(T*& pointer, void (*destroy)(T*)) {
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T* hold = pointer;
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pointer = nullptr;
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if (hold) {
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destroy(hold);
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}
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}
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template <class T>
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static inline void MozClearHandleID(T& handle, gboolean (*destroy)(T)) {
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if (handle) {
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destroy(handle);
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handle = 0;
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}
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}
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#endif // nsGtkUtils_h__
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