diff options
Diffstat (limited to 'src/corelib/global/qversiontagging.h')
| -rw-r--r-- | src/corelib/global/qversiontagging.h | 184 |
1 files changed, 115 insertions, 69 deletions
diff --git a/src/corelib/global/qversiontagging.h b/src/corelib/global/qversiontagging.h index 75c2e9df7e..73faf5b6eb 100644 --- a/src/corelib/global/qversiontagging.h +++ b/src/corelib/global/qversiontagging.h @@ -1,88 +1,134 @@ -/**************************************************************************** -** -** Copyright (C) 2016 Intel Corporation. -** Contact: https://www.qt.io/licensing/ -** -** This file is part of the QtCore module of the Qt Toolkit. -** -** $QT_BEGIN_LICENSE:LGPL$ -** Commercial License Usage -** Licensees holding valid commercial Qt licenses may use this file in -** accordance with the commercial license agreement provided with the -** Software or, alternatively, in accordance with the terms contained in -** a written agreement between you and The Qt Company. For licensing terms -** and conditions see https://www.qt.io/terms-conditions. For further -** information use the contact form at https://www.qt.io/contact-us. -** -** GNU Lesser General Public License Usage -** Alternatively, this file may be used under the terms of the GNU Lesser -** General Public License version 3 as published by the Free Software -** Foundation and appearing in the file LICENSE.LGPL3 included in the -** packaging of this file. Please review the following information to -** ensure the GNU Lesser General Public License version 3 requirements -** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. -** -** GNU General Public License Usage -** Alternatively, this file may be used under the terms of the GNU -** General Public License version 2.0 or (at your option) the GNU General -** Public license version 3 or any later version approved by the KDE Free -** Qt Foundation. The licenses are as published by the Free Software -** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 -** included in the packaging of this file. Please review the following -** information to ensure the GNU General Public License requirements will -** be met: https://www.gnu.org/licenses/gpl-2.0.html and -** https://www.gnu.org/licenses/gpl-3.0.html. -** -** $QT_END_LICENSE$ -** -****************************************************************************/ - -// qglobal.h includes this header, so keep it outside of our include guards -#include <QtCore/qglobal.h> +// Copyright (C) 2022 Intel Corporation. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only #if !defined(QVERSIONTAGGING_H) #define QVERSIONTAGGING_H +#include <QtCore/qcompilerdetection.h> +#include <QtCore/qtconfigmacros.h> +#include <QtCore/qtversionchecks.h> +#include <QtCore/qtypes.h> + QT_BEGIN_NAMESPACE /* - * Ugly hack warning and explanation: + * Explanation + * + * This file causes all libraries, plugins, and applications that #include this + * file to automatically pull in a symbol found in QtCore that encodes the + * current Qt version number at the time of compilation. The relocation is + * designed so that it's impossible for the dynamic linker to perform lazy + * binding. Instead, it must resolve at load time or fail. That way, attempting + * to load such a library or plugin while an older QtCore is loaded will fail. + * Similarly, if an older QtCore is found when launching an application, the + * application will fail to launch. * - * This file causes all ELF modules, be they libraries or applications, to use the - * qt_version_tag symbol that is present in QtCore. Such symbol is versioned, - * so the linker will automatically pull the current Qt version and add it to - * the ELF header of the library/application. The assembly produces one section - * called ".qtversion" containing two 32-bit values. The first is a - * relocation to the qt_version_tag symbol (which is what causes the ELF - * version to get used). The second value is the current Qt version at the time - * of compilation. + * It's also possible to inspect which version is required by decoding the + * .qtversion section. The second pointer-sized variable is the required + * version, for example, for Qt 6.4.1: + * + * Hex dump of section [18] '.qtversion', 16 bytes at offset 0x1ee48: + * 0x00000000 b0ffffff ffffffff 01040600 00000000 ................ + * ^^^^^^^^ ^^^^^^^^ * * There will only be one copy of the section in the output library or application. + * + * This functionality can be disabled by defining QT_NO_VERSION_TAGGING. It's + * disabled if Qt was built statically. + * + * Windows notes: + * + * On Windows, the address of a __declspec(dllimport) variable is not a + * constant expression, unlike Unix systems. So we instead use the address of + * the import variable, which is created by prefixing the external name with + * "__imp_". Using that variable causes an import of the corresponding symbol + * from QtCore DLL. + * + * With MinGW (GCC and Clang), we use a C++17 inline variable, so the compiler + * and linker automatically merge the variables. The "used" __attribute__ + * tells the compiler to always emit that variable, whether it's used or not. + * + * MSVC has no equivalent to that attribute, so instead we create an extern + * const variable and tell the linker to merge them all via + * __declspec(selectany). + * + * Unix notes: + * + * On Unix, we use the same C++17 inline variable solution as MinGW, but we + * don't need the "__imp_" trick. + * + * Additionally, on ELF systems like Linux and FreeBSD, the symbol in question + * is simply "qt_version_tag" in both QtCore and in this ELF module, but it + * has an ELF version attached to it (see qversiontagging.cpp and + * QtFlagHandlingHelpers.cmake). That way, the error message from the dynamic + * linker will say it can't find version "Qt_6.x". */ -#if defined(QT_BUILD_CORE_LIB) || defined(QT_BOOTSTRAPPED) || defined(QT_NO_VERSION_TAGGING) || defined(QT_STATIC) +namespace QtPrivate { +struct QVersionTag +{ + const void *symbol; + quintptr version; + constexpr QVersionTag(const void *sym, int currentVersion = QT_VERSION) + : symbol(sym), version(currentVersion) + {} +}; +} + +#if !defined(QT_NO_VERSION_TAGGING) && (defined(QT_BUILD_CORE_LIB) || defined(QT_BOOTSTRAPPED) || defined(QT_STATIC)) // don't make tags in QtCore, bootstrapped systems or if the user asked not to -#elif defined(Q_CC_GNU) && !defined(Q_OS_ANDROID) -# if defined(Q_PROCESSOR_X86) && (defined(Q_OS_LINUX) || defined(Q_OS_FREEBSD_KERNEL)) -# if defined(Q_PROCESSOR_X86_64) && QT_POINTER_SIZE == 8 // x86-64 64-bit -# define QT_VERSION_TAG_RELOC(sym) ".quad " QT_STRINGIFY(QT_MANGLE_NAMESPACE(sym)) "@GOT\n" -# else // x86 or x86-64 32-bit (x32) -# define QT_VERSION_TAG_RELOC(sym) ".long " QT_STRINGIFY(QT_MANGLE_NAMESPACE(sym)) "@GOT\n" -# endif -# define QT_VERSION_TAG(sym) \ - asm ( \ - ".section .qtversion, \"aG\", @progbits, " QT_STRINGIFY(QT_MANGLE_NAMESPACE(sym)) ", comdat\n" \ - ".align 8\n" \ - QT_VERSION_TAG_RELOC(sym) \ - ".long " QT_STRINGIFY(QT_VERSION) "\n" \ - ".align 8\n" \ - ".previous" \ - ) +# define QT_NO_VERSION_TAGGING +#endif + +#if defined(Q_OS_WIN) +# ifdef Q_PROCESSOR_X86_32 +// 32-bit x86 convention does prepend a _ +# define QT_MANGLE_IMPORT_PREFIX _imp__ +# else +// Calling convention on other architectures does not prepend a _ +# define QT_MANGLE_IMPORT_PREFIX __imp_ +# endif +# if defined(Q_CC_MSVC_ONLY) +# pragma section(".qtversion",read,shared) +# define QT_VERSION_TAG_SECTION __declspec(allocate(".qtversion")) +# define QT_VERSION_TAG_ATTRIBUTE __declspec(selectany) extern const +# else +# define QT_VERSION_TAG_ATTRIBUTE __attribute__((used)) constexpr inline +# endif +# define QT_VERSION_TAG2(sym, imp) \ + extern "C" const char * const imp; \ + QT_VERSION_TAG_ATTRIBUTE QT_VERSION_TAG_SECTION QtPrivate::QVersionTag sym ## _used(&imp) +# define QT_VERSION_TAG(sym, imp) QT_VERSION_TAG2(sym, imp) +#elif defined(Q_CC_GNU) && __has_attribute(used) +# ifdef Q_OS_DARWIN +# define QT_VERSION_TAG_SECTION __attribute__((section("__DATA,.qtversion"))) # endif +# define QT_VERSION_TAG_ATTRIBUTE __attribute__((visibility("hidden"), used)) +# define QT_VERSION_TAG2(sym, imp) \ + extern "C" Q_DECL_IMPORT const char sym; \ + QT_VERSION_TAG_ATTRIBUTE QT_VERSION_TAG_SECTION constexpr inline QtPrivate::QVersionTag sym ## _use(&sym) +# define QT_VERSION_TAG(sym, imp) QT_VERSION_TAG2(sym, imp) #endif -#if defined(QT_VERSION_TAG) -QT_VERSION_TAG(qt_version_tag); +#ifdef Q_OF_ELF +# define QT_VERSION_TAG_SYMBOL(prefix, sym, m, n) sym +#else +# define QT_VERSION_TAG_SYMBOL2(prefix, sym, m, n) prefix ## sym ## _ ## m ## _ ## n +# define QT_VERSION_TAG_SYMBOL(prefix, sym, m, n) QT_VERSION_TAG_SYMBOL2(prefix, sym, m, n) +#endif + +#if defined(QT_VERSION_TAG) && !defined(QT_NO_VERSION_TAGGING) +# ifndef QT_VERSION_TAG_SECTION +# define QT_VERSION_TAG_SECTION __attribute__((section(".qtversion"))) +# endif +# define QT_MANGLED_VERSION_TAG_IMPORT QT_VERSION_TAG_SYMBOL(QT_MANGLE_IMPORT_PREFIX, QT_MANGLE_NAMESPACE(qt_version_tag), QT_VERSION_MAJOR, QT_VERSION_MINOR) +# define QT_MANGLED_VERSION_TAG QT_VERSION_TAG_SYMBOL(, QT_MANGLE_NAMESPACE(qt_version_tag), QT_VERSION_MAJOR, QT_VERSION_MINOR) + +QT_VERSION_TAG(QT_MANGLED_VERSION_TAG, QT_MANGLED_VERSION_TAG_IMPORT); + +# undef QT_MANGLED_VERSION_TAG +# undef QT_MANGLED_VERSION_TAG_IMPORT +# undef QT_VERSION_TAG_SECTION #endif QT_END_NAMESPACE |