1// Copyright (C) 2016 The Qt Company Ltd.
2// Copyright (C) 2016 Intel Corporation.
3// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
4
5#include "qdbus_symbols_p.h"
6#include <QtCore/qlatin1stringview.h>
7#if QT_CONFIG(library)
8#include <QtCore/qlibrary.h>
9#include <QtCore/private/qlocking_p.h>
10#endif
11#include <QtCore/qmutex.h>
12
13#ifndef QT_NO_DBUS
14
15QT_BEGIN_NAMESPACE
16
17using namespace Qt::StringLiterals;
18
19#if !defined QT_LINKED_LIBDBUS
20
21#if QT_CONFIG(library)
22Q_CONSTINIT static QLibrary *qdbus_libdbus = nullptr;
23
24void qdbus_unloadLibDBus()
25{
26 if (qdbus_libdbus) {
27 if (qEnvironmentVariableIsSet("QDBUS_FORCE_SHUTDOWN"))
28 qdbus_libdbus->resolve("dbus_shutdown")();
29 qdbus_libdbus->unload();
30 }
31 delete qdbus_libdbus;
32 qdbus_libdbus = nullptr;
33}
34#endif
35
36bool qdbus_loadLibDBus()
37{
38#if QT_CONFIG(library)
39#ifdef QT_BUILD_INTERNAL
40 // this is to simulate a library load failure for our autotest suite.
41 if (!qEnvironmentVariableIsEmpty("QT_SIMULATE_DBUS_LIBFAIL"))
42 return false;
43#endif
44
45 Q_CONSTINIT static bool triedToLoadLibrary = false;
46 Q_CONSTINIT static QBasicMutex mutex;
47 const auto locker = qt_scoped_lock(mutex);
48
49 QLibrary *&lib = qdbus_libdbus;
50 if (triedToLoadLibrary)
51 return lib && lib->isLoaded();
52
53 lib = new QLibrary;
54 lib->setLoadHints(QLibrary::ExportExternalSymbolsHint); // make libdbus symbols available for apps that need more advanced control over the dbus
55 triedToLoadLibrary = true;
56
57 static constexpr int majorversions[] = { 3, 2, -1 };
58 const QString baseNames[] = {
59#ifdef Q_OS_WIN
60 "dbus-1"_L1,
61#endif
62 "libdbus-1"_L1
63 };
64
65 lib->unload();
66 for (const int majorversion : majorversions) {
67 for (const QString &baseName : baseNames) {
68#ifdef Q_OS_WIN
69 QString suffix;
70 if (majorversion != -1)
71 suffix = QString::number(- majorversion); // negative so it prepends the dash
72 lib->setFileName(baseName + suffix);
73#else
74 lib->setFileNameAndVersion(baseName, majorversion);
75#endif
76 if (lib->load() && lib->resolve("dbus_connection_open_private"))
77 return true;
78
79 lib->unload();
80 }
81 }
82
83 delete lib;
84 lib = nullptr;
85 return false;
86#else
87 return true;
88#endif
89}
90
91QFunctionPointer qdbus_resolve_conditionally(const char *name)
92{
93#if QT_CONFIG(library)
94 if (qdbus_loadLibDBus())
95 return qdbus_libdbus->resolve(name);
96#else
97 Q_UNUSED(name);
98#endif
99 return nullptr;
100}
101
102QFunctionPointer qdbus_resolve_me(const char *name)
103{
104#if QT_CONFIG(library)
105 if (Q_UNLIKELY(!qdbus_loadLibDBus()))
106 qFatal("Cannot find libdbus-1 in your system to resolve symbol '%s'.", name);
107
108 QFunctionPointer ptr = qdbus_libdbus->resolve(name);
109 if (Q_UNLIKELY(!ptr))
110 qFatal("Cannot resolve '%s' in your libdbus-1.", name);
111
112 return ptr;
113#else
114 Q_UNUSED(name);
115 return nullptr;
116#endif
117}
118
119#else
120static void qdbus_unloadLibDBus()
121{
122 if (qEnvironmentVariableIsSet(varName: "QDBUS_FORCE_SHUTDOWN"))
123 dbus_shutdown();
124}
125
126#endif // !QT_LINKED_LIBDBUS
127
128#if defined(QT_LINKED_LIBDBUS) || QT_CONFIG(library)
129Q_DESTRUCTOR_FUNCTION(qdbus_unloadLibDBus)
130#endif
131
132QT_END_NAMESPACE
133
134#endif // QT_NO_DBUS
135

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source code of qtbase/src/dbus/qdbus_symbols.cpp