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