| 1 | /* |
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| 2 | SPDX-FileCopyrightText: 2024 Andreas Hartmetz <ahartmetz@gmail.com> |
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| 3 | |
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| 4 | SPDX-License-Identifier: LGPL-2.0-or-later |
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| 5 | */ |
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| 6 | |
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| 7 | #pragma once |
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| 8 | |
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| 9 | #include <string.h> |
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| 10 | |
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| 11 | /* |
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| 12 | * KXcbEvent allocates an xcb event in a 32 bytes large, zero-initialized buffer to avoid |
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| 13 | * out-of-bounds reads and uninitialized memory reads in xcb_send_event(). According to |
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| 14 | * XCB documentation, the wire size of all XCB events is 32 bytes, and that many bytes will |
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| 15 | * be read by xcb_send_event(). |
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| 16 | */ |
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| 17 | template<class EventType, bool needsPadding = (sizeof(EventType) < 32)> |
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| 18 | struct KXcbEvent; |
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| 19 | |
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| 20 | template<class EventType> |
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| 21 | class KXcbEvent<EventType, false> : public EventType |
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| 22 | { |
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| 23 | public: |
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| 24 | inline KXcbEvent() |
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| 25 | { |
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| 26 | static_assert(sizeof(*this) == s_evtSize); |
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| 27 | memset(this, 0, s_evtSize); |
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| 28 | } |
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| 29 | |
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| 30 | inline const char *buffer() const |
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| 31 | { |
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| 32 | return reinterpret_cast<const char *>(this); |
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| 33 | } |
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| 34 | |
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| 35 | private: |
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| 36 | static constexpr size_t s_evtSize = 32; |
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| 37 | }; |
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| 38 | |
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| 39 | template<class EventType> |
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| 40 | class KXcbEvent<EventType, true> : public EventType |
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| 41 | { |
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| 42 | public: |
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| 43 | inline KXcbEvent() |
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| 44 | { |
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| 45 | static_assert(sizeof(*this) == s_evtSize); |
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| 46 | memset(this, 0, s_evtSize); |
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| 47 | } |
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| 48 | |
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| 49 | inline const char *buffer() const |
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| 50 | { |
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| 51 | return reinterpret_cast<const char *>(this); |
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| 52 | } |
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| 53 | |
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| 54 | private: |
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| 55 | static constexpr size_t s_evtSize = 32; |
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| 56 | char m_filler[s_evtSize - sizeof(EventType)]; |
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| 57 | }; |
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| 58 | |
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