1// Copyright (C) 2016 The Qt Company Ltd.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3// Qt-Security score:significant reason:default
4
5#ifndef QSHAREDMEMORY_P_H
6#define QSHAREDMEMORY_P_H
7
8//
9// W A R N I N G
10// -------------
11//
12// This file is not part of the Qt API. It exists purely as an
13// implementation detail. This header file may change from version to
14// version without notice, or even be removed.
15//
16// We mean it.
17//
18
19#include "qsharedmemory.h"
20
21#include <QtCore/qstring.h>
22
23#if QT_CONFIG(sharedmemory)
24#include "qsystemsemaphore.h"
25#include "qtipccommon_p.h"
26#include "private/qobject_p.h"
27
28#if QT_CONFIG(posix_shm)
29# include <sys/mman.h>
30#endif
31#if QT_CONFIG(sysv_shm)
32# include <sys/shm.h>
33#endif
34
35QT_BEGIN_NAMESPACE
36
37class QSharedMemoryPrivate;
38
39#if QT_CONFIG(systemsemaphore)
40/*!
41 Helper class
42 */
43class QSharedMemoryLocker
44{
45 Q_DISABLE_COPY(QSharedMemoryLocker)
46public:
47 Q_NODISCARD_CTOR explicit QSharedMemoryLocker(QSharedMemory *sharedMemory)
48 : q_sm(sharedMemory)
49 {
50 Q_ASSERT(q_sm);
51 }
52
53 Q_NODISCARD_CTOR QSharedMemoryLocker(QSharedMemoryLocker &&other) noexcept
54 : q_sm{std::exchange(obj&: other.q_sm, new_val: nullptr)}
55 {}
56
57 QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QSharedMemoryLocker)
58
59 void swap(QSharedMemoryLocker &other) noexcept
60 { qt_ptr_swap(lhs&: q_sm, rhs&: other.q_sm); }
61
62 inline ~QSharedMemoryLocker()
63 {
64 if (q_sm)
65 q_sm->unlock();
66 }
67
68 inline bool lock()
69 {
70 if (q_sm && q_sm->lock())
71 return true;
72 q_sm = nullptr;
73 return false;
74 }
75
76private:
77 friend void swap(QSharedMemoryLocker &lhs, QSharedMemoryLocker &rhs) noexcept
78 { lhs.swap(other&: rhs); }
79
80 QSharedMemory *q_sm;
81};
82#endif // QT_CONFIG(systemsemaphore)
83
84class QSharedMemoryPosix
85{
86public:
87 static constexpr bool Enabled = QT_CONFIG(posix_shm);
88 static bool supports(QNativeIpcKey::Type type)
89 { return type == QNativeIpcKey::Type::PosixRealtime; }
90 static bool runtimeSupportCheck();
91
92 bool handle(QSharedMemoryPrivate *self);
93 bool cleanHandle(QSharedMemoryPrivate *self);
94 bool create(QSharedMemoryPrivate *self, qsizetype size);
95 bool attach(QSharedMemoryPrivate *self, QSharedMemory::AccessMode mode);
96 bool detach(QSharedMemoryPrivate *self);
97
98 int hand = -1;
99};
100
101class QSharedMemorySystemV
102{
103public:
104 static constexpr bool Enabled = QT_CONFIG(sysv_shm);
105 static bool supports(QNativeIpcKey::Type type)
106 { return quint16(type) <= 0xff; }
107 static bool runtimeSupportCheck();
108
109#if QT_CONFIG(sysv_shm)
110 key_t handle(QSharedMemoryPrivate *self);
111 bool cleanHandle(QSharedMemoryPrivate *self);
112 bool create(QSharedMemoryPrivate *self, qsizetype size);
113 bool attach(QSharedMemoryPrivate *self, QSharedMemory::AccessMode mode);
114 bool detach(QSharedMemoryPrivate *self);
115
116private:
117 void updateNativeKeyFile(const QNativeIpcKey &nativeKey);
118
119 QByteArray nativeKeyFile;
120 key_t unix_key = 0;
121#endif
122};
123
124class QSharedMemoryWin32
125{
126public:
127#ifdef Q_OS_WIN32
128 static constexpr bool Enabled = true;
129#else
130 static constexpr bool Enabled = false;
131#endif
132 static bool runtimeSupportCheck() { return Enabled; }
133 static bool supports(QNativeIpcKey::Type type)
134 { return type == QNativeIpcKey::Type::Windows; }
135
136 Qt::HANDLE handle(QSharedMemoryPrivate *self);
137 bool cleanHandle(QSharedMemoryPrivate *self);
138 bool create(QSharedMemoryPrivate *self, qsizetype size);
139 bool attach(QSharedMemoryPrivate *self, QSharedMemory::AccessMode mode);
140 bool detach(QSharedMemoryPrivate *self);
141
142 Qt::HANDLE hand = nullptr;
143};
144
145class Q_AUTOTEST_EXPORT QSharedMemoryPrivate : public QObjectPrivate
146{
147 Q_DECLARE_PUBLIC(QSharedMemory)
148
149public:
150 QSharedMemoryPrivate(QNativeIpcKey::Type type) : nativeKey(type)
151 { constructBackend(); }
152 ~QSharedMemoryPrivate();
153
154 void *memory = nullptr;
155 qsizetype size = 0;
156 QNativeIpcKey nativeKey;
157 QString errorString;
158#if QT_CONFIG(systemsemaphore)
159 using SemaphoreAccessMode = QSystemSemaphore::AccessMode;
160 QSystemSemaphore systemSemaphore{ QNativeIpcKey() };
161 bool lockedByMe = false;
162#else
163 enum SemaphoreAccessMode {};
164#endif
165 QSharedMemory::SharedMemoryError error = QSharedMemory::NoError;
166
167 union Backend {
168 Backend() {}
169 ~Backend() {}
170 QSharedMemoryPosix posix;
171 QSharedMemorySystemV sysv;
172 QSharedMemoryWin32 win32;
173 };
174 QtIpcCommon::IpcStorageVariant<&Backend::posix, &Backend::sysv, &Backend::win32> backend;
175
176 void constructBackend();
177 void destructBackend();
178 bool initKey(SemaphoreAccessMode mode);
179
180 template <typename Lambda> auto visit(const Lambda &lambda)
181 {
182 return backend.visit(nativeKey.type(), lambda);
183 }
184
185 bool handle()
186 {
187 return visit(lambda: [&](auto p) { return !!p->handle(this); });
188 }
189 bool cleanHandle()
190 {
191 return visit(lambda: [&](auto p) { return p->cleanHandle(this); });
192 }
193 bool create(qsizetype sz)
194 {
195 return visit(lambda: [&](auto p) { return p->create(this, sz); });
196 }
197 bool attach(QSharedMemory::AccessMode mode)
198 {
199 return visit(lambda: [&](auto p) { return p->attach(this, mode); });
200 }
201 bool detach()
202 {
203 return visit(lambda: [&](auto p) { return p->detach(this); });
204 }
205
206 inline void setError(QSharedMemory::SharedMemoryError e, const QString &message)
207 { error = e; errorString = message; }
208 void setUnixErrorString(QLatin1StringView function);
209 void setWindowsErrorString(QLatin1StringView function);
210
211#if QT_CONFIG(systemsemaphore)
212 bool tryLocker(QSharedMemoryLocker *locker, const QString &function) {
213 if (!locker->lock()) {
214 errorString = QSharedMemory::tr(s: "%1: unable to lock").arg(a: function);
215 error = QSharedMemory::LockError;
216 return false;
217 }
218 return true;
219 }
220 QNativeIpcKey semaphoreNativeKey() const;
221#endif // QT_CONFIG(systemsemaphore)
222};
223
224QT_END_NAMESPACE
225
226#endif // QT_CONFIG(sharedmemory)
227
228#endif // QSHAREDMEMORY_P_H
229
230

source code of qtbase/src/corelib/ipc/qsharedmemory_p.h