qlibraryinfo.cpp

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// Copyright (C) 2021 The Qt Company Ltd.
// Copyright (C) 2021 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:critical reason:execute-external-code
 
#include "qdir.h"
#include "qstringlist.h"
#include "qfile.h"
#if QT_CONFIG(settings)
#include "qresource.h"
#include "qsettings.h"
#endif
#include "qlibraryinfo.h"
#include "qlibraryinfo_p.h"
 
#include "qcoreapplication.h"
 
#include "private/qcoreapplication_p.h"
#include "private/qfilesystementry_p.h"
#include "archdetect.cpp"
#include "qconfig.cpp"
 
#ifdef Q_OS_DARWIN
#  include "private/qcore_mac_p.h"
#endif // Q_OS_DARWIN
 
#if QT_CONFIG(relocatable) && QT_CONFIG(dlopen)
#    include <dlfcn.h>
#endif
 
#if QT_CONFIG(relocatable) && defined(Q_OS_WIN)
#    include <qt_windows.h>
#endif
 
#include <memory>
 
QT_BEGIN_NAMESPACE
 
using namespace Qt::StringLiterals;
 
extern void qDumpCPUFeatures(); // in qsimd.cpp
 
static QString fromRawStringView(QStringView string)
{
    return QString::fromRawData(string.data(), string.size());
}
 
static bool pathIsRelative(const QString &path)
{
    using FromInternalPath = QFileSystemEntry::FromInternalPath;
    return !path.startsWith(':'_L1) && QFileSystemEntry(path, FromInternalPath{}).isRelative();
}
 
// Resolves and caches the Qt and application prefix roots. Resolution
// may be costly and is queried repeatedly during startup, so results
// are memoized. Wrapped in a Q_GLOBAL_STATIC (prefixCache) so lookups
// during static destruction fall back to resolving from scratch.
struct QLibraryPrefixes
{
    static QString qtPrefix();
    static QString appPrefix();
 
private:
    // Pure resolvers, without caching, so they're usable even without a
    // cache instance during static destruction. resolveAppPrefix() returns an
    // empty string when no stable source is available yet; appPrefix()
    // then falls back to the (uncached) working directory.
    static QString resolveQtPrefix();
    static QString resolveAppPrefix();
 
    // The directory the application prefix is rooted at: the app bundle on
    // Apple platforms, or the application directory once a QCoreApplication
    // exists. Empty when no stable source is available yet.
    static QString resolveAppDir();
 
    // The qt.conf "Prefix" entry the application prefix is rooted at,
    // or its "." default when there's no qt.conf (or settings) to read.
    static QString qtConfPrefix();
 
    // Memoizes resolve() in the given member. A resolver may return an
    // empty string to signal that the result is not yet stable and should
    // not be cached, in which case it is resolved anew on each call. During
    // static destruction prefixCache() returns nullptr and resolve() is
    // used directly.
    static QString cached(QString QLibraryPrefixes::*member, QString (*resolve)());
 
    QString m_qt;
    QString m_app;
};
Q_GLOBAL_STATIC(QLibraryPrefixes, prefixCache)
 
QString QLibraryPrefixes::cached(QString QLibraryPrefixes::*member, QString (*resolve)())
{
    QLibraryPrefixes *cache = prefixCache();
    if (cache && !(cache->*member).isEmpty())
        return cache->*member;
    QString prefix = resolve();
    if (cache && !prefix.isEmpty())
        cache->*member = prefix;
    return prefix;
}
 
#if QT_CONFIG(settings)
 
static std::unique_ptr<QSettings> findConfiguration();
 
struct QLibrarySettings
{
    QLibrarySettings();
    void load();
    bool havePaths();
    QSettings *configuration();
    QVariant value(QLibraryInfo::LibraryPath path);
    QList<QString> paths(QLibraryInfo::LibraryPath location);
 
    std::unique_ptr<QSettings> settings;
    bool configHasPaths;
    bool reloadOnQAppAvailable;
};
Q_GLOBAL_STATIC(QLibrarySettings, qt_library_settings)
 
QLibrarySettings::QLibrarySettings() : configHasPaths(false), reloadOnQAppAvailable(false)
{
    load();
}
 
QSettings *QLibrarySettings::configuration()
{
    if (reloadOnQAppAvailable && QCoreApplication::instanceExists())
        load();
    return settings.get();
}
 
bool QLibrarySettings::havePaths()
{
    if (reloadOnQAppAvailable && QCoreApplication::instanceExists())
        load();
    return configHasPaths;
}
 
void QLibrarySettings::load()
{
    // If we get any settings here, those won't change when the application shows up.
    settings = findConfiguration();
    reloadOnQAppAvailable = !settings && !QCoreApplication::instanceExists();
 
    if (settings) {
        // This code needs to be in the regular library, as otherwise a qt.conf that
        // works for qmake would break things for dynamically built Qt tools.
        QStringList children = settings->childGroups();
        configHasPaths = !children.contains("Platforms"_L1)
                         || children.contains("Paths"_L1);
    } else {
        configHasPaths = false;
    }
}
 
/*!
    Returns the value for a given \a path from \c qt.conf
 
    If no \c qt.conf is found, or the configuration doesn't
    specify a value for the given \a path a null-variant is
    returned.
 
    \internal
*/
QVariant QLibrarySettings::value(QLibraryInfo::LibraryPath path)
{
    const auto locationInfo = QLibraryInfoPrivate::locationInfo(path);
    if (locationInfo.key.isNull())
        return {};
 
    QSettings *config = configuration();
    if (!settings || !configHasPaths)
        return {};
 
    config->beginGroup("Paths"_L1);
    auto cleanup = qScopeGuard([&]() { config->endGroup(); });
    QVariant value = config->value(locationInfo.key);
    if (!value.isValid() && !locationInfo.fallbackKey.isNull())
        value = config->value(locationInfo.fallbackKey);
    return value;
}
 
QList<QString> QLibrarySettings::paths(QLibraryInfo::LibraryPath location)
{
    QList<QString> ret;
    if (QVariant v = value(location); v.isValid()) {
        if (auto *asList = get_if<QList<QString>>(&v))
            ret = std::move(*asList);
        else
            ret << v.toString();
 
        for (qsizetype i = 0, end = ret.size(); i < end; ++i)
            ret[i] = QLibraryInfoPrivate::expandEnvVariables(ret[i]);
    }
    return ret;
}
 
namespace {
const QString *qtconfManualPath = nullptr;
}
 
void QLibraryInfoPrivate::setQtconfManualPath(const QString *path)
{
    qtconfManualPath = path;
}
 
static std::unique_ptr<QSettings> findConfiguration()
{
    if (qtconfManualPath)
        return std::make_unique<QSettings>(*qtconfManualPath, QSettings::IniFormat);
 
    QString qtconfig = QStringLiteral(":/qt/etc/qt.conf");
    if (QResource(qtconfig, QLocale::c()).isValid())
        return std::make_unique<QSettings>(qtconfig, QSettings::IniFormat);
#ifdef Q_OS_DARWIN
    CFBundleRef bundleRef = CFBundleGetMainBundle();
    if (bundleRef) {
        QCFType<CFURLRef> urlRef = CFBundleCopyResourceURL(bundleRef,
                                                           QCFString("qt.conf"_L1),
                                                           0,
                                                           0);
        if (urlRef) {
            QCFString path = CFURLCopyFileSystemPath(urlRef, kCFURLPOSIXPathStyle);
            qtconfig = QDir::cleanPath(path);
            if (QFile::exists(qtconfig))
                return std::make_unique<QSettings>(qtconfig, QSettings::IniFormat);
        }
    }
#endif
    if (QCoreApplication::instanceExists()) {
        QString pwd = QCoreApplication::applicationDirPath();
        qtconfig = pwd + u"/qt" QT_STRINGIFY(QT_VERSION_MAJOR) ".conf"_s;
        if (QFile::exists(qtconfig))
            return std::make_unique<QSettings>(qtconfig, QSettings::IniFormat);
        qtconfig = pwd + u"/qt.conf";
        if (QFile::exists(qtconfig))
            return std::make_unique<QSettings>(qtconfig, QSettings::IniFormat);
    }
    return nullptr;     //no luck
}
 
QSettings *QLibraryInfoPrivate::configuration()
{
    QLibrarySettings *ls = qt_library_settings();
    return ls ? ls->configuration() : nullptr;
}
#endif // settings
 
void QLibraryInfoPrivate::reload()
{
#if QT_CONFIG(settings)
    if (qt_library_settings.exists())
        qt_library_settings->load();
#endif
    if (prefixCache.exists())
        *prefixCache = {};
}
 
/*!
    \class QLibraryInfo
    \inmodule QtCore
    \brief The QLibraryInfo class provides information about the Qt libraries.
 
    This class provides an abstraction for accessing information about the
    Qt libraries which the application is using, such as run-time paths,
    or the build configuration of the Qt libraries.
 
    The default run-time paths depend on the Qt build configuration, as well
    as whether the Qt libraries have been relocated, and possibly bundled along
    with the application.
 
    You can use a \c qt.conf file to override the default paths,
    in case your deployment situation does not match the defaults.
    For more information, see the \l {Using qt.conf} documentation.
 
    \sa QSysInfo, {Using qt.conf}
*/
 
/*!
    \internal
 
   You cannot create a QLibraryInfo, instead only the static functions are available to query
   information.
*/
 
QLibraryInfo::QLibraryInfo()
{ }
 
#if defined(Q_CC_CLANG) // must be before GNU, because clang claims to be GNU too
#  define COMPILER_STRING __VERSION__       /* already includes the compiler's name */
#elif defined(Q_CC_GHS)
#  define COMPILER_STRING "GHS " QT_STRINGIFY(__GHS_VERSION_NUMBER)
#elif defined(Q_CC_GNU)
#  define COMPILER_STRING "GCC " __VERSION__
#elif defined(Q_CC_MSVC)
#  if _MSC_VER < 1910
#    define COMPILER_STRING "MSVC 2015"
#  elif _MSC_VER < 1917
#    define COMPILER_STRING "MSVC 2017"
#  elif _MSC_VER < 1930
#    define COMPILER_STRING "MSVC 2019"
#  elif _MSC_VER < 1950
#    define COMPILER_STRING "MSVC 2022"
#  elif _MSC_VER < 2000
#    define COMPILER_STRING "MSVC 2026"
#  else
#    define COMPILER_STRING "MSVC _MSC_VER " QT_STRINGIFY(_MSC_VER)
#  endif
#else
#  define COMPILER_STRING "<unknown compiler>"
#endif
#ifdef QT_NO_DEBUG
#  define DEBUG_STRING " release"
#else
#  define DEBUG_STRING " debug"
#endif
#ifdef QT_SHARED
#  define SHARED_STRING " shared (dynamic)"
#else
#  define SHARED_STRING " static"
#endif
static const char *qt_build_string() noexcept
{
    return "Qt " QT_VERSION_STR " (" ARCH_FULL SHARED_STRING DEBUG_STRING " build; by " COMPILER_STRING ")";
}
 
/*!
  Returns a string describing how this version of Qt was built.
 
  \internal
 
  \since 5.3
*/
 
const char *QLibraryInfo::build() noexcept
{
    return qt_build_string();
}
 
/*!
    \since 5.0
    Returns \c true if this build of Qt was built with debugging enabled, or
    false if it was built in release mode.
*/
bool
QLibraryInfo::isDebugBuild() noexcept
{
#ifdef QT_DEBUG
    return true;
#else
    return false;
#endif
}
 
/*!
    \since 6.5
    Returns \c true if this is a shared (dynamic) build of Qt.
*/
bool QLibraryInfo::isSharedBuild() noexcept
{
#ifdef QT_SHARED
    return true;
#else
    return false;
#endif
}
 
/*!
    \since 5.8
    Returns the version of the Qt library.
 
    \sa qVersion()
*/
QVersionNumber QLibraryInfo::version() noexcept
{
    return QVersionNumber(QT_VERSION_MAJOR, QT_VERSION_MINOR, QT_VERSION_PATCH);
}
 
/*!
    \internal
 
    Returns the qt.conf "Prefix" entry the application prefix is rooted at,
    falling back to its "." default when there's no qt.conf with paths (or
    settings support), so the prefix then resolves to the application directory.
*/
QString QLibraryPrefixes::qtConfPrefix()
{
#if QT_CONFIG(settings)
    QLibrarySettings *settings = qt_library_settings();
    if (settings && settings->havePaths()) {
        const QString prefix = settings->paths(QLibraryInfo::PrefixPath).value(0);
        if (!prefix.isEmpty())
            return prefix;
    }
#endif
    return u"."_s;
}
 
/*!
    \internal
 
    The directory the application prefix is rooted at: the app bundle on
    Apple platforms, or the application directory once a QCoreApplication
    exists. Returns an empty string when no stable source is available yet.
*/
QString QLibraryPrefixes::resolveAppDir()
{
#if defined(Q_OS_DARWIN)
    // Resolve the app prefix from the app bundle instead of the
    // executable, as that correctly handles both the main executable
    // as well as possibly deeply nested helper tools, and lets us
    // root the app prefix at the base of the bundle. Note that
    // CFBundleGetMainBundle returns a bundle representation even
    // for unbundled apps, so we verify the URL is actually a bundle.
    if (CFBundleRef bundleRef = CFBundleGetMainBundle()) {
        if (QCFType<CFURLRef> urlRef = CFBundleCopyBundleURL(bundleRef)) {
            const QString bundlePath = QCFString(CFURLCopyFileSystemPath(urlRef, kCFURLPOSIXPathStyle));
            if (qt_apple_bundleType(bundlePath)) {
#if defined(Q_OS_MACOS)
                // On macOS the prefix is rooted at the bundle's Contents directory.
                return QFileInfo(bundlePath + "/Contents"_L1).canonicalFilePath();
#else
                return QFileInfo(bundlePath).canonicalFilePath(); // iOS
#endif // Q_OS_MACOS
            }
        }
    }
#endif // Q_OS_DARWIN
 
    if (QCoreApplication::instanceExists()) {
        // We make the prefix path absolute to the executable's directory.
        return QCoreApplication::applicationDirPath();
    }
 
    // Without an application instance there's no stable source; return an
    // empty string so the result isn't cached, and let appPrefix() fall back
    // to the (volatile) working directory until a stable source is available.
    return {};
}
 
/*!
    \internal
 
    The fully resolved application prefix: the qt.conf "Prefix" entry
    (explicit, or the "." default) rooted at the application directory.
    An absolute Prefix is used as-is, independent of the application
    directory. Without a qt.conf the prefix is the application directory
    itself, which is also what static builds use as their Qt prefix.
 
    Returns an empty string when the result would depend on a not-yet-stable
    application directory, so it isn't cached; appPrefix() then roots the
    prefix at the (volatile) working directory until a stable source exists.
*/
QString QLibraryPrefixes::resolveAppPrefix()
{
    const QString prefix = qtConfPrefix();
    // An absolute qt.conf Prefix is stable on its own, regardless of appDir.
    if (!pathIsRelative(prefix))
        return prefix;
    const QString appDir = resolveAppDir();
    if (appDir.isEmpty())
        return {};
    return QDir::cleanPath(appDir + u'/' + prefix);
}
 
QString QLibraryPrefixes::appPrefix()
{
    QString prefix = cached(&QLibraryPrefixes::m_app, &QLibraryPrefixes::resolveAppPrefix);
    if (!prefix.isNull())
        return prefix;
 
    // No stable source yet; root the possible qt.conf Prefix at the volatile
    // working directory, without caching, until one is available.
    return QDir::cleanPath(QDir::currentPath() + u'/' + qtConfPrefix());
}
 
#if QT_CONFIG(relocatable)
#if !defined(QT_STATIC) && (QT_CONFIG(dlopen) || defined(Q_OS_WIN))
static QString prefixFromQtCoreLibraryHelper(const QString &qtCoreLibraryPath)
{
    const QString qtCoreLibrary = QDir::fromNativeSeparators(qtCoreLibraryPath);
    QString libDir = QFileInfo(qtCoreLibrary).absolutePath();
 
#if QT_CONFIG(framework)
# if defined(Q_OS_MACOS)
    // The library in a macOS framework lives in a `Versions/A/` subdirectory
    libDir += "/../.."_L1;
# endif
    // And both macOS and iOS frameworks are `.framework` bundle directories
    libDir += "/.."_L1;
#endif
 
    const QString prefixDir = libDir + "/" QT_CONFIGURE_LIBLOCATION_TO_PREFIX_PATH;
    return QDir::cleanPath(prefixDir);
}
#endif
 
#if defined(Q_OS_WIN)
static HMODULE getWindowsModuleHandle()
{
    HMODULE hModule = NULL;
    GetModuleHandleEx(
        GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
        (LPCTSTR)&QLibraryInfo::isDebugBuild, &hModule);
    return hModule;
}
#endif // Q_OS_WIN
 
static QString relocatablePrefixFromQt()
{
    QString prefixPath;
 
    // For static builds, the prefix will be the app directory, unless it's a non-sandboxed Apple app.
    // For regular builds, the prefix will be relative to the location of the QtCore shared library.
#if defined(QT_STATIC)
# if defined(Q_OS_APPLE)
    // The default value for QT_CONFIG(relocatable) for static builds
    // used to be false, giving end users QT_CONFIGURE_PREFIX_PATH as
    // the prefix path. We've since changed the default to true for
    // Apple platforms, since sandboxed applications are always
    // relocated, even for static builds. To avoid regressions for
    // those that shipped non-sandboxed apps with static Qt relying
    // on the previous behavior, we fall back to the Qt configure
    // prefix for non-sandboxed apps.
    if (!qt_apple_isSandboxed())
        return QString::fromLocal8Bit(QT_CONFIGURE_PREFIX_PATH);
# endif
    prefixPath = QLibraryPrefixes::appPrefix();
#elif defined(Q_OS_WASM)
    // Emscripten expects to find shared libraries at the root of the in-memory
    // file system when resolving dependencies for for dlopen() calls. So that's
    // where libqt6core.so would be.
    prefixPath = QStringLiteral("/");
#elif QT_CONFIG(dlopen)
    Dl_info info;
    int result = dladdr(reinterpret_cast<void *>(&QLibraryInfo::isDebugBuild), &info);
    if (result > 0 && info.dli_fname)
        prefixPath = prefixFromQtCoreLibraryHelper(QString::fromLocal8Bit(info.dli_fname));
#elif defined(Q_OS_WIN)
    HMODULE hModule = getWindowsModuleHandle();
    const int kBufferSize = 4096;
    wchar_t buffer[kBufferSize];
    DWORD pathSize = GetModuleFileName(hModule, buffer, kBufferSize);
    const QString qtCoreFilePath = QString::fromWCharArray(buffer, int(pathSize));
    const QString qtCoreDirPath = QFileInfo(qtCoreFilePath).absolutePath();
 
    hModule = reinterpret_cast<HMODULE>(QCoreApplicationPrivate::mainInstanceHandle);
    pathSize = GetModuleFileName(hModule, buffer, kBufferSize);
    const QString exeDirPath = QFileInfo(QString::fromWCharArray(buffer, int(pathSize))).absolutePath();
    if (QFileInfo(exeDirPath) == QFileInfo(qtCoreDirPath)) {
        // QtCore DLL is next to the executable. This is either a windeployqt'ed executable or an
        // executable within the QT_HOST_BIN directory. We're detecting the latter case by checking
        // whether there's an import library corresponding to our QtCore DLL in PREFIX/lib.
        QStringView libdir = qt_configure_strs.viewAt(QLibraryInfo::LibrariesPath - 1);
        const QLatin1Char slash('/');
#if defined(Q_CC_MINGW)
        const QString implibPrefix = QStringLiteral("lib");
        const QString implibSuffix = QStringLiteral(".a");
#else
        const QString implibPrefix;
        const QString implibSuffix = QStringLiteral(".lib");
#endif
        const QString qtCoreImpLibFileName = implibPrefix
                + QFileInfo(qtCoreFilePath).completeBaseName() + implibSuffix;
        const QString qtCoreImpLibPath = qtCoreDirPath
                + slash + QT_CONFIGURE_LIBLOCATION_TO_PREFIX_PATH
                + slash + libdir
                + slash + qtCoreImpLibFileName;
        if (!QFileInfo::exists(qtCoreImpLibPath)) {
            // We did not find a corresponding import library and conclude that this is a
            // windeployqt'ed executable.
            return exeDirPath;
        }
    }
    if (!qtCoreFilePath.isEmpty())
        prefixPath = prefixFromQtCoreLibraryHelper(qtCoreFilePath);
#else
#error "The chosen platform / config does not support querying for a dynamic prefix."
#endif
 
#if defined(Q_OS_LINUX) && !defined(QT_STATIC) && defined(__GLIBC__)
    // QTBUG-78948: libQt5Core.so may be located in subdirectories below libdir.
    // See "Hardware capabilities" in the ld.so documentation and the Qt 5.3.0
    // changelog regarding SSE2 support.
    QString libdir = fromRawStringView(qt_configure_strs.viewAt(QLibraryInfo::LibrariesPath - 1));
    QDir prefixDir(prefixPath);
    while (!prefixDir.exists(libdir)) {
        prefixDir.cdUp();
        prefixPath = prefixDir.absolutePath();
        if (prefixDir.isRoot()) {
            prefixPath.clear();
            break;
        }
    }
#endif
 
    Q_ASSERT_X(!prefixPath.isEmpty(), "relocatablePrefixFromQt",
                                      "Failed to find the Qt prefix path.");
    return prefixPath;
}
#endif
 
QString QLibraryPrefixes::resolveQtPrefix()
{
#if QT_CONFIG(relocatable)
    return relocatablePrefixFromQt();
#else
    return QString::fromLocal8Bit(QT_CONFIGURE_PREFIX_PATH);
#endif
}
 
QString QLibraryPrefixes::qtPrefix()
{
#if defined(QT_STATIC)
    // In static builds the Qt prefix resolves via the app directory (see
    // relocatablePrefixFromQt), which is not stable until an application
    // instance exists, and is cached and invalidated by appPrefix().
    // Don't cache it a second time here, to avoid freezing a transient
    // working-directory value.
    return resolveQtPrefix();
#else
    return cached(&QLibraryPrefixes::m_qt, &QLibraryPrefixes::resolveQtPrefix);
#endif
}
 
QLibraryInfoPrivate::LocationInfo QLibraryInfoPrivate::locationInfo(QLibraryInfo::LibraryPath loc)
{
    /*
     * To add a new entry in QLibraryInfo::LibraryPath, add it to the enum
     * in qtbase/src/corelib/global/qlibraryinfo.h and:
     * - add its relative path in the qtConfEntries[] array below
     *   (the key is what appears in a qt.conf file)
     */
    static constexpr auto qtConfEntries = qOffsetStringArray(
        "Prefix", ".",
        "Documentation", "doc", // should be ${Data}/doc
        "Headers", "include",
        "Libraries", "lib",
#ifdef Q_OS_WIN
        "LibraryExecutables", "bin",
#else
        "LibraryExecutables", "libexec", // should be ${ArchData}/libexec
#endif
        "Binaries", "bin",
        "Plugins", "plugins", // should be ${ArchData}/plugins
 
        "QmlImports", "qml", // should be ${ArchData}/qml
 
        "ArchData", ".",
        "Data", ".",
        "Translations", "translations", // should be ${Data}/translations
        "Examples", "examples",
        "Tests", "tests"
    );
    [[maybe_unused]]
    constexpr QByteArrayView dot{"."};
 
    LocationInfo result;
 
    if (int(loc) < qtConfEntries.count()) {
        result.key = QLatin1StringView(qtConfEntries.viewAt(loc * 2));
        result.defaultValue = QLatin1StringView(qtConfEntries.viewAt(loc * 2 + 1));
        if (result.key == u"QmlImports")
            result.fallbackKey = u"Qml2Imports"_s;
#if !defined(Q_OS_WIN) // On Windows we use the registry
    } else if (loc == QLibraryInfo::SettingsPath) {
        result.key = "Settings"_L1;
        result.defaultValue = QLatin1StringView(dot);
#endif
    }
 
    return result;
}
 
/*! \fn QString QLibraryInfo::location(LibraryLocation loc)
    \deprecated [6.0] Use path() instead.
 
    Returns the path specified by \a loc.
*/
 
/*!
    \since 6.0
    Returns the path specified by \a p.
 
    If there is more than one path listed in qt.conf, it will
    only return the first one.
    \sa paths
*/
QString QLibraryInfo::path(LibraryPath p)
{
    return QLibraryInfoPrivate::path(p);
}
 
/*!
    \since 6.8
    Returns all paths specificied by \a p.
 
    \sa path
 */
QStringList QLibraryInfo::paths(LibraryPath p)
{
    return QLibraryInfoPrivate::paths(p);
}
 
/*!
    Returns whether the existence of a \c qt.conf with explicit
    paths should not trigger the stable fallback-values from
    QLibraryInfoPrivate::locationInfo() as usual, but instead
    fall back to the Qt configure defaults (which may differ
    from Qt installation to Qt installtion).
 
    This mechanism is used by QtQml's internal build machinery
    for making QML modules across different paths available
    during development.
 
    \internal
*/
static bool keepQtBuildDefaults()
{
#if QT_CONFIG(settings)
    QSettings *config = QLibraryInfoPrivate::configuration();
    Q_ASSERT(config != nullptr);
    return config->value("Config/MergeQtConf", false).toBool();
#else
    return false;
#endif
}
 
#if QT_CONFIG(settings)
QString QLibraryInfoPrivate::expandEnvVariables(QString ret)
{
    qsizetype startIndex = 0;
    /* We support placeholders of the form $(<ENV_VAR>) in qt.conf.
       The loop below tries to find all such placeholders, and replaces
       them with the actual value of the ENV_VAR environment variable
     */
    while (true) {
        startIndex = ret.indexOf(u'$', startIndex);
        if (startIndex < 0)
            break;
        if (ret.size() < startIndex + 3)
            break;
        if (ret.at(startIndex + 1) != u'(') {
            startIndex++;
            continue;
        }
        qsizetype endIndex = ret.indexOf(u')', startIndex + 2);
        if (endIndex < 0)
            break;
        auto envVarName = QStringView{ret}.sliced(startIndex + 2, endIndex - startIndex - 2);
        QString value = qEnvironmentVariable(envVarName.toLocal8Bit().constData());
        ret.replace(startIndex, endIndex - startIndex + 1, value);
        startIndex += value.size();
    }
    return QDir::fromNativeSeparators(ret);
}
 
#endif // settings
 
/*!
    \internal
 
    Roots any relative entries in \a paths at the directory returned by
    \a resolveBaseDir, which is resolved lazily (only when there's actually a
    relative path to root, and at most once).
*/
static QList<QString> makeAbsolute(QList<QString> paths, QString (*resolveBaseDir)())
{
    QString baseDir;
    for (QString &path : paths) {
        if (pathIsRelative(path)) {
            if (baseDir.isNull())
                baseDir = resolveBaseDir();
            path = QDir::cleanPath(baseDir + u'/' + std::move(path));
        }
    }
    return paths;
}
 
QStringList QLibraryInfoPrivate::paths(QLibraryInfo::LibraryPath location)
{
    QList<QString> ret = appPaths(location);
 
    if (ret.isEmpty() || keepQtBuildDefaults())
        ret += qtPaths(location);
 
    return ret;
}
 
/*!
    \internal
 
    The application-prefixed paths for \a location, rooted at the app prefix,
    sourced from a qt.conf with explicit paths. Returns empty when there's no
    such qt.conf, signaling the caller to fall through to the Qt-prefixed paths.
*/
QList<QString> QLibraryInfoPrivate::appPaths(QLibraryInfo::LibraryPath location)
{
#if QT_CONFIG(settings)
    QLibrarySettings *qtConfSettings = qt_library_settings();
    if (qtConfSettings && qtConfSettings->havePaths()) {
        if (location == QLibraryInfo::PrefixPath)
            return { QLibraryPrefixes::appPrefix() };
 
        QList<QString> paths = qtConfSettings->paths(location);
 
        // Fall back to a stable default for missing qt.conf values
        if (paths.isEmpty()) {
            const auto locationInfo = QLibraryInfoPrivate::locationInfo(location);
            if (!locationInfo.defaultValue.isNull())
                paths << locationInfo.defaultValue;
        }
 
        return makeAbsolute(std::move(paths), &QLibraryPrefixes::appPrefix);
    }
#endif
    return {};
}
 
/*!
    \internal
 
    The Qt-prefixed paths for \a location, rooted at the Qt prefix, from the
    paths baked in at configure time.
*/
QList<QString> QLibraryInfoPrivate::qtPaths(QLibraryInfo::LibraryPath location)
{
    if (location == QLibraryInfo::PrefixPath)
        return { QLibraryPrefixes::qtPrefix() };
 
    QList<QString> paths;
 
    if (int(location) <= qt_configure_strs.count()) {
        paths << fromRawStringView(qt_configure_strs.viewAt(location - 1));
#if !defined(Q_OS_WIN) // On Windows we use the registry
    } else if (location == QLibraryInfo::SettingsPath) {
        constexpr QStringView path = u"" QT_CONFIGURE_SETTINGS_PATH;
        paths << fromRawStringView(path);
#endif
    }
 
    return makeAbsolute(std::move(paths), &QLibraryPrefixes::qtPrefix);
}
 
/*
    Returns the path specified by \a p.
 */
QString QLibraryInfoPrivate::path(QLibraryInfo::LibraryPath p)
{
    return paths(p).value(0, QString());
}
 
/*!
  Returns additional arguments to the platform plugin matching
  \a platformName which can be specified as a string list using
  the key \c Arguments in a group called \c Platforms of the
  \c qt.conf  file.
 
  sa {Using qt.conf}
 
  \internal
 
  \since 5.3
*/
 
QStringList QLibraryInfo::platformPluginArguments(const QString &platformName)
{
#if QT_CONFIG(settings)
    if (const QSettings *settings = QLibraryInfoPrivate::configuration()) {
        const QString key = "Platforms/"_L1
                + platformName
                + "Arguments"_L1;
        return settings->value(key).toStringList();
    }
#else
    Q_UNUSED(platformName);
#endif // settings
    return QStringList();
}
 
/*!
    \enum QLibraryInfo::LibraryPath
 
    \keyword library location
 
    This enum type is used to query for a specific path:
 
    \value PrefixPath The default prefix for all paths.
    \value DocumentationPath The path to documentation upon install.
    \value HeadersPath The path to all headers.
    \value LibrariesPath The path to installed libraries.
    \value LibraryExecutablesPath The path to installed executables required by libraries at runtime.
    \value BinariesPath The path to installed Qt binaries (tools and applications).
    \value PluginsPath The path to installed Qt plugins.
    \value QmlImportsPath The path to installed QML extensions to import.
    \value Qml2ImportsPath This value is deprecated. Use QmlImportsPath instead.
    \value ArchDataPath The path to general architecture-dependent Qt data.
    \value DataPath The path to general architecture-independent Qt data.
    \value TranslationsPath The path to translation information for Qt strings.
    \value ExamplesPath The path to examples upon install.
    \value TestsPath The path to installed Qt testcases.
    \value SettingsPath The path to Qt settings. Not applicable on Windows.
 
    \sa path()
*/
 
/*!
    \typealias QLibraryInfo::LibraryLocation
    \deprecated [6.0] Use LibraryPath with QLibraryInfo::path() instead.
*/
 
/*!
    \headerfile <QtVersion>
    \inmodule QtCore
    \ingroup funclists
    \brief Information about which Qt version the application is running on,
           and the version it was compiled against.
*/
 
/*!
    \macro QT_VERSION_STR
    \relates <QtVersion>
 
    This macro expands to a string that specifies Qt's version number (for
    example, "6.1.2"). This is the version with which the application is
    compiled. This may be a different version than the version the application
    will find itself using at \e runtime.
 
    \sa qVersion(), QT_VERSION
*/
 
/*!
    \relates <QtVersion>
 
    Returns the version number of Qt at runtime as a string (for example,
    "6.1.2"). This is the version of the Qt library in use at \e runtime,
    which need not be the version the application was \e compiled with.
 
    \sa QT_VERSION_STR, QLibraryInfo::version()
*/
 
const char *qVersion() noexcept
{
    return QT_VERSION_STR;
}
 
#if QT_DEPRECATED_SINCE(6, 9)
 
bool qSharedBuild() noexcept
{
    return QLibraryInfo::isSharedBuild();
}
 
#endif // QT_DEPRECATED_SINCE(6, 9)
 
QT_END_NAMESPACE
 
#if defined(Q_CC_GNU) && defined(ELF_INTERPRETER)
#  include <elf.h>
#  include <stdio.h>
#  include <stdlib.h>
 
#include "private/qcoreapplication_p.h"
 
QT_WARNING_DISABLE_GCC("-Wformat-overflow")
QT_WARNING_DISABLE_GCC("-Wattributes")
QT_WARNING_DISABLE_CLANG("-Wattributes")
QT_WARNING_DISABLE_INTEL(2621)
 
#  if defined(Q_OS_LINUX)
#    include "minimum-linux_p.h"
#  endif
#  ifdef QT_ELF_NOTE_OS_TYPE
struct ElfNoteAbiTag
{
    static_assert(sizeof(Elf32_Nhdr) == sizeof(Elf64_Nhdr),
        "The size of an ELF note is wrong (should be 12 bytes)");
    struct Payload {
        Elf32_Word ostype = QT_ELF_NOTE_OS_TYPE;
        Elf32_Word major = QT_ELF_NOTE_OS_MAJOR;
        Elf32_Word minor = QT_ELF_NOTE_OS_MINOR;
#    ifdef QT_ELF_NOTE_OS_PATCH
        Elf32_Word patch = QT_ELF_NOTE_OS_PATCH;
#    endif
    };
 
    Elf32_Nhdr header = {
        .n_namesz = sizeof(name),
        .n_descsz = sizeof(Payload),
        .n_type = NT_GNU_ABI_TAG
    };
    char name[sizeof ELF_NOTE_GNU] = ELF_NOTE_GNU;  // yes, include the null terminator
    Payload payload = {};
};
__attribute__((section(".note.ABI-tag"), aligned(4), used))
extern constexpr ElfNoteAbiTag QT_MANGLE_NAMESPACE(qt_abi_tag) = {};
#  endif
 
extern const char qt_core_interpreter[] __attribute__((section(".interp")))
    = ELF_INTERPRETER;
 
extern "C" void qt_core_boilerplate() __attribute__((force_align_arg_pointer));
void qt_core_boilerplate()
{
    QT_USE_NAMESPACE
 
    printf("This is the QtCore library version %s\n"
           "%s\n"
           "Contact: https://www.qt.io/licensing/\n"
           "\n",
           QT_PREPEND_NAMESPACE(qt_build_string)(),
           QT_COPYRIGHT);
 
    QByteArray libPath =
            qt_configure_strs.viewAt(QLibraryInfo::LibrariesPath - 1).toUtf8();
    QByteArray pluginPath =
            qt_configure_strs.viewAt(QLibraryInfo::PluginsPath - 1).toUtf8();
#if QT_CONFIG(relocatable)
    QByteArray prefix = QLibraryPrefixes::qtPrefix().toUtf8();
#else
    QByteArrayView prefix = QT_CONFIGURE_PREFIX_PATH;
#endif
    printf("Installation prefix: %s\n"
           "Library path:        %s\n"
           "Plugin path:         %s\n",
           prefix.data(),
           libPath.data(),
           pluginPath.data());
 
    QT_PREPEND_NAMESPACE(qDumpCPUFeatures)();
 
    exit(0);
}
 
#endif