Replace qgetenv() calls converted to QString with qEnvironmentVariable()

It's slightly more efficient.

Pick-to: 6.9
Change-Id: Id5ac04fc27eee108c8e5fffd786c3d5f793a0a9d
Reviewed-by: Ahmad Samir <[email protected]>

23 files changed, 75 insertions, 74 deletions

diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index 86800492511..d7b0f21b866 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -1186,7 +1186,7 @@ QMessagePattern::QMessagePattern()
 #ifndef QT_BOOTSTRAPPED
     timer.start();
 #endif
-    const QString envPattern = QString::fromLocal8Bit(qgetenv("QT_MESSAGE_PATTERN"));
+    const QString envPattern = qEnvironmentVariable("QT_MESSAGE_PATTERN");
     if (envPattern.isEmpty()) {
         setPattern(QLatin1StringView(defaultPattern));
         fromEnvironment = false;
diff --git a/src/corelib/io/qfilesystemengine_unix.cpp b/src/corelib/io/qfilesystemengine_unix.cpp
index 60963a1c9c2..ec962eba365 100644
--- a/src/corelib/io/qfilesystemengine_unix.cpp
+++ b/src/corelib/io/qfilesystemengine_unix.cpp
@@ -1783,7 +1783,7 @@ bool QFileSystemEngine::setFileTime(int fd, const QDateTime &newDate, QFile::Fil
 
 QString QFileSystemEngine::homePath()
 {
-    QString home = QFile::decodeName(qgetenv("HOME"));
+    QString home = qEnvironmentVariable("HOME");
     if (home.isEmpty())
         home = rootPath();
     return QDir::cleanPath(home);
@@ -1799,7 +1799,7 @@ QString QFileSystemEngine::tempPath()
 #ifdef QT_UNIX_TEMP_PATH_OVERRIDE
     return QT_UNIX_TEMP_PATH_OVERRIDE ""_L1;
 #else
-    QString temp = QFile::decodeName(qgetenv("TMPDIR"));
+    QString temp = qEnvironmentVariable("TMPDIR");
     if (temp.isEmpty()) {
         if (false) {
 #if defined(Q_OS_DARWIN) && !defined(QT_BOOTSTRAPPED)
diff --git a/src/corelib/io/qloggingregistry.cpp b/src/corelib/io/qloggingregistry.cpp
index ee7b7c56132..32e8fdec659 100644
--- a/src/corelib/io/qloggingregistry.cpp
+++ b/src/corelib/io/qloggingregistry.cpp
@@ -282,9 +282,8 @@ void QLoggingRegistry::initializeRules()
     }
     QList<QLoggingRule> er, qr, cr;
     // get rules from environment
-    const QByteArray rulesFilePath = qgetenv("QT_LOGGING_CONF");
-    if (!rulesFilePath.isEmpty())
-        er = loadRulesFromFile(QFile::decodeName(rulesFilePath));
+    if (QString rulesFilePath = qEnvironmentVariable("QT_LOGGING_CONF"); !rulesFilePath.isEmpty())
+        er = loadRulesFromFile(rulesFilePath);
 
     if (qtLoggingDebug())
         debugMsg("Checking %s environment variable", "QT_LOGGING_RULES");
diff --git a/src/corelib/io/qstandardpaths.cpp b/src/corelib/io/qstandardpaths.cpp
index 792721f50d4..c0c676d04f2 100644
--- a/src/corelib/io/qstandardpaths.cpp
+++ b/src/corelib/io/qstandardpaths.cpp
@@ -6,6 +6,7 @@
 
 #include <qdir.h>
 #include <qfileinfo.h>
+#include <qvarlengtharray.h>
 
 #ifndef QT_BOOTSTRAPPED
 #include <qobject.h>
@@ -424,6 +425,28 @@ QStringList QStandardPaths::locateAll(StandardLocation type, const QString &file
     return result;
 }
 
+static Q_DECL_COLD_FUNCTION QString fallbackPathVariable()
+{
+#if defined(_PATH_DEFPATH)
+    // BSD API.
+    return QString::fromLocal8Bit(_PATH_DEFPATH);
+#endif
+#if defined(_CS_PATH)
+    // POSIX API.
+    size_t n = confstr(_CS_PATH, nullptr, 0);
+    if (n) {
+        // n includes the terminating null
+        QVarLengthArray<char, 1024> rawpath(n);
+        confstr(_CS_PATH, rawpath.data(), n);
+        return QString::fromLocal8Bit(QByteArrayView(rawpath.data(), n - 1));
+    }
+#else
+    // Windows SDK's execvpe() does not have a fallback, so we won't
+    // apply one either.
+#endif
+    return {};
+}
+
 #ifdef Q_OS_WIN
 static QStringList executableExtensions()
 {
@@ -490,30 +513,16 @@ QString QStandardPaths::findExecutable(const QString &executableName, const QStr
 
     QStringList searchPaths = paths;
     if (paths.isEmpty()) {
-        QByteArray pEnv = qgetenv("PATH");
+        QString pEnv = qEnvironmentVariable("PATH");
         if (Q_UNLIKELY(pEnv.isNull())) {
             // Get a default path. POSIX.1 does not actually require this, but
             // most Unix libc fall back to confstr(_CS_PATH) if the PATH
             // environment variable isn't set. Let's try to do the same.
-#if defined(_PATH_DEFPATH)
-            // BSD API.
-            pEnv = _PATH_DEFPATH;
-#elif defined(_CS_PATH)
-            // POSIX API.
-            size_t n = confstr(_CS_PATH, nullptr, 0);
-            if (n) {
-                pEnv.resize(n);
-                // size()+1 is ok because QByteArray always has an extra NUL-terminator
-                confstr(_CS_PATH, pEnv.data(), pEnv.size() + 1);
-            }
-#else
-            // Windows SDK's execvpe() does not have a fallback, so we won't
-            // apply one either.
-#endif
+            pEnv = fallbackPathVariable();
         }
 
         // Remove trailing slashes, which occur on Windows.
-        const QStringList rawPaths = QString::fromLocal8Bit(pEnv.constData()).split(
+        const QStringList rawPaths = pEnv.split(
             QDir::listSeparator(), Qt::SkipEmptyParts);
         searchPaths.reserve(rawPaths.size());
         for (const QString &rawPath : rawPaths) {
diff --git a/src/corelib/io/qstandardpaths_unix.cpp b/src/corelib/io/qstandardpaths_unix.cpp
index e38f6708951..4fe8739bcc0 100644
--- a/src/corelib/io/qstandardpaths_unix.cpp
+++ b/src/corelib/io/qstandardpaths_unix.cpp
@@ -185,7 +185,7 @@ QString QStandardPaths::writableLocation(StandardLocation type)
             xdgCacheHome = QDir::homePath() + "/.qttest/cache"_L1;
         } else {
             // http://standards.freedesktop.org/basedir-spec/basedir-spec-0.6.html
-            xdgCacheHome = QFile::decodeName(qgetenv("XDG_CACHE_HOME"));
+            xdgCacheHome = qEnvironmentVariable("XDG_CACHE_HOME");
             if (!xdgCacheHome.startsWith(u'/'))
                 xdgCacheHome.clear(); // spec says relative paths should be ignored
 
@@ -204,7 +204,7 @@ QString QStandardPaths::writableLocation(StandardLocation type)
             xdgStateHome = QDir::homePath() + "/.qttest/state"_L1;
         } else {
             // http://standards.freedesktop.org/basedir-spec/basedir-spec-0.8.html
-            xdgStateHome = QFile::decodeName(qgetenv("XDG_STATE_HOME"));
+            xdgStateHome = qEnvironmentVariable("XDG_STATE_HOME");
             if (!xdgStateHome.startsWith(u'/'))
                 xdgStateHome.clear(); // spec says relative paths should be ignored
 
@@ -223,7 +223,7 @@ QString QStandardPaths::writableLocation(StandardLocation type)
         if (isTestModeEnabled()) {
             xdgDataHome = QDir::homePath() + "/.qttest/share"_L1;
         } else {
-            xdgDataHome = QFile::decodeName(qgetenv("XDG_DATA_HOME"));
+            xdgDataHome = qEnvironmentVariable("XDG_DATA_HOME");
             if (!xdgDataHome.startsWith(u'/'))
                 xdgDataHome.clear(); // spec says relative paths should be ignored
 
@@ -243,7 +243,7 @@ QString QStandardPaths::writableLocation(StandardLocation type)
             xdgConfigHome = QDir::homePath() + "/.qttest/config"_L1;
         } else {
             // http://standards.freedesktop.org/basedir-spec/latest/
-            xdgConfigHome = QFile::decodeName(qgetenv("XDG_CONFIG_HOME"));
+            xdgConfigHome = qEnvironmentVariable("XDG_CONFIG_HOME");
             if (!xdgConfigHome.startsWith(u'/'))
                 xdgConfigHome.clear(); // spec says relative paths should be ignored
 
@@ -256,7 +256,7 @@ QString QStandardPaths::writableLocation(StandardLocation type)
     }
     case RuntimeLocation:
     {
-        QString xdgRuntimeDir = QFile::decodeName(qgetenv("XDG_RUNTIME_DIR"));
+        QString xdgRuntimeDir = qEnvironmentVariable("XDG_RUNTIME_DIR");
         if (!xdgRuntimeDir.startsWith(u'/'))
             xdgRuntimeDir.clear(); // spec says relative paths should be ignored
 
@@ -285,7 +285,7 @@ QString QStandardPaths::writableLocation(StandardLocation type)
 
 #if QT_CONFIG(regularexpression)
     // http://www.freedesktop.org/wiki/Software/xdg-user-dirs
-    QString xdgConfigHome = QFile::decodeName(qgetenv("XDG_CONFIG_HOME"));
+    QString xdgConfigHome = qEnvironmentVariable("XDG_CONFIG_HOME");
     if (!xdgConfigHome.startsWith(u'/'))
         xdgConfigHome.clear(); // spec says relative paths should be ignored
 
@@ -390,7 +390,7 @@ static QStringList dirsList(const QString &xdgEnvVar)
 static QStringList xdgDataDirs()
 {
     // http://standards.freedesktop.org/basedir-spec/latest/
-    QString xdgDataDirsEnv = QFile::decodeName(qgetenv("XDG_DATA_DIRS"));
+    QString xdgDataDirsEnv = qEnvironmentVariable("XDG_DATA_DIRS");
 
     QStringList dirs = dirsList(xdgDataDirsEnv);
     if (dirs.isEmpty())
@@ -402,7 +402,7 @@ static QStringList xdgDataDirs()
 static QStringList xdgConfigDirs()
 {
     // http://standards.freedesktop.org/basedir-spec/latest/
-    const QString xdgConfigDirs = QFile::decodeName(qgetenv("XDG_CONFIG_DIRS"));
+    const QString xdgConfigDirs = qEnvironmentVariable("XDG_CONFIG_DIRS");
 
     QStringList dirs = dirsList(xdgConfigDirs);
     if (dirs.isEmpty())
diff --git a/src/gui/image/qiconloader.cpp b/src/gui/image/qiconloader.cpp
index 006b5f2793a..999c65bb438 100644
--- a/src/gui/image/qiconloader.cpp
+++ b/src/gui/image/qiconloader.cpp
@@ -50,9 +50,8 @@ QIconLoader::QIconLoader() :
 
 static inline QString systemThemeName()
 {
-    const auto override = qgetenv("QT_QPA_SYSTEM_ICON_THEME");
-    if (!override.isEmpty())
-        return QString::fromLocal8Bit(override);
+    if (QString override = qEnvironmentVariable("QT_QPA_SYSTEM_ICON_THEME"); !override.isEmpty())
+        return override;
     if (const QPlatformTheme *theme = QGuiApplicationPrivate::platformTheme()) {
         const QVariant themeHint = theme->themeHint(QPlatformTheme::SystemIconThemeName);
         if (themeHint.isValid())
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index dcdff702c44..0ca39d72451 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -1499,7 +1499,7 @@ void QGuiApplicationPrivate::createPlatformIntegration()
     QHighDpiScaling::initHighDpiScaling();
 
     // Load the platform integration
-    QString platformPluginPath = QString::fromLocal8Bit(qgetenv("QT_QPA_PLATFORM_PLUGIN_PATH"));
+    QString platformPluginPath = qEnvironmentVariable("QT_QPA_PLATFORM_PLUGIN_PATH");
 
 
     QByteArray platformName;
diff --git a/src/gui/platform/unix/qgenericunixservices.cpp b/src/gui/platform/unix/qgenericunixservices.cpp
index 32487b16511..a36976a6937 100644
--- a/src/gui/platform/unix/qgenericunixservices.cpp
+++ b/src/gui/platform/unix/qgenericunixservices.cpp
@@ -105,10 +105,10 @@ static inline bool detectWebBrowser(const QByteArray &desktop,
         return true;
 
     if (checkBrowserVariable) {
-        QByteArray browserVariable = qgetenv("DEFAULT_BROWSER");
+        QString browserVariable = qEnvironmentVariable("DEFAULT_BROWSER");
         if (browserVariable.isEmpty())
-            browserVariable = qgetenv("BROWSER");
-        if (!browserVariable.isEmpty() && checkExecutable(QString::fromLocal8Bit(browserVariable), browser))
+            browserVariable = qEnvironmentVariable("BROWSER");
+        if (!browserVariable.isEmpty() && checkExecutable(browserVariable, browser))
             return true;
     }
 
diff --git a/src/gui/platform/unix/qgenericunixthemes.cpp b/src/gui/platform/unix/qgenericunixthemes.cpp
index cd916bcf7a2..e2037639a4d 100644
--- a/src/gui/platform/unix/qgenericunixthemes.cpp
+++ b/src/gui/platform/unix/qgenericunixthemes.cpp
@@ -1204,11 +1204,11 @@ QPlatformTheme *QKdeTheme::createKdeTheme()
     // - fallback to /etc/kde<version>
 
     QStringList kdeDirs;
-    const QString kdeHomePathVar = QFile::decodeName(qgetenv("KDEHOME"));
+    const QString kdeHomePathVar = qEnvironmentVariable("KDEHOME");
     if (!kdeHomePathVar.isEmpty())
         kdeDirs += kdeHomePathVar;
 
-    const QString kdeDirsVar = QFile::decodeName(qgetenv("KDEDIRS"));
+    const QString kdeDirsVar = qEnvironmentVariable("KDEDIRS");
     if (!kdeDirsVar.isEmpty())
         kdeDirs += kdeDirsVar.split(u':', Qt::SkipEmptyParts);
 
diff --git a/src/gui/text/qplatformfontdatabase.cpp b/src/gui/text/qplatformfontdatabase.cpp
index 3d3f3c30985..381431ac4e9 100644
--- a/src/gui/text/qplatformfontdatabase.cpp
+++ b/src/gui/text/qplatformfontdatabase.cpp
@@ -360,7 +360,7 @@ void QPlatformFontDatabase::releaseHandle(void *handle)
 */
 QString QPlatformFontDatabase::fontDir() const
 {
-    QString fontpath = QString::fromLocal8Bit(qgetenv("QT_QPA_FONTDIR"));
+    QString fontpath = qEnvironmentVariable("QT_QPA_FONTDIR");
     if (fontpath.isEmpty())
         fontpath = QLibraryInfo::path(QLibraryInfo::LibrariesPath) + "/fonts"_L1;
 
diff --git a/src/gui/vulkan/qbasicvulkanplatforminstance.cpp b/src/gui/vulkan/qbasicvulkanplatforminstance.cpp
index b6a820199c0..47d9a7e962f 100644
--- a/src/gui/vulkan/qbasicvulkanplatforminstance.cpp
+++ b/src/gui/vulkan/qbasicvulkanplatforminstance.cpp
@@ -51,7 +51,7 @@ void QBasicPlatformVulkanInstance::loadVulkanLibrary(const QString &defaultLibra
     // embedded systems without a Vulkan loader and possibly with custom vendor
     // library names.
     if (qEnvironmentVariableIsSet("QT_VULKAN_LIB"))
-        loadList.append({ QString::fromUtf8(qgetenv("QT_VULKAN_LIB")), -1 });
+        loadList.append({ qEnvironmentVariable("QT_VULKAN_LIB"), -1 });
 
     // Then what the platform specified. On Linux the version is likely 1, thus
     // preferring libvulkan.so.1 over libvulkan.so.
diff --git a/src/platformsupport/input/evdevkeyboard/qevdevkeyboardmanager.cpp b/src/platformsupport/input/evdevkeyboard/qevdevkeyboardmanager.cpp
index 8fcf01ae902..da82cf12b7d 100644
--- a/src/platformsupport/input/evdevkeyboard/qevdevkeyboardmanager.cpp
+++ b/src/platformsupport/input/evdevkeyboard/qevdevkeyboardmanager.cpp
@@ -22,7 +22,7 @@ QEvdevKeyboardManager::QEvdevKeyboardManager(const QString &key, const QString &
     Q_UNUSED(key);
 
 
-    QString spec = QString::fromLocal8Bit(qgetenv("QT_QPA_EVDEV_KEYBOARD_PARAMETERS"));
+    QString spec = qEnvironmentVariable("QT_QPA_EVDEV_KEYBOARD_PARAMETERS");
 
     if (spec.isEmpty())
         spec = specification;
diff --git a/src/platformsupport/input/evdevmouse/qevdevmousemanager.cpp b/src/platformsupport/input/evdevmouse/qevdevmousemanager.cpp
index 83176a17931..a9619a53c6b 100644
--- a/src/platformsupport/input/evdevmouse/qevdevmousemanager.cpp
+++ b/src/platformsupport/input/evdevmouse/qevdevmousemanager.cpp
@@ -24,7 +24,7 @@ QEvdevMouseManager::QEvdevMouseManager(const QString &key, const QString &specif
 {
     Q_UNUSED(key);
 
-    QString spec = QString::fromLocal8Bit(qgetenv("QT_QPA_EVDEV_MOUSE_PARAMETERS"));
+    QString spec = qEnvironmentVariable("QT_QPA_EVDEV_MOUSE_PARAMETERS");
 
     if (spec.isEmpty())
         spec = specification;
diff --git a/src/platformsupport/input/evdevtablet/qevdevtabletmanager.cpp b/src/platformsupport/input/evdevtablet/qevdevtabletmanager.cpp
index d013ef04d50..6395e57c127 100644
--- a/src/platformsupport/input/evdevtablet/qevdevtabletmanager.cpp
+++ b/src/platformsupport/input/evdevtablet/qevdevtabletmanager.cpp
@@ -23,7 +23,7 @@ QEvdevTabletManager::QEvdevTabletManager(const QString &key, const QString &spec
     if (qEnvironmentVariableIsSet("QT_QPA_EVDEV_DEBUG"))
         const_cast<QLoggingCategory &>(qLcEvdevTablet()).setEnabled(QtDebugMsg, true);
 
-    QString spec = QString::fromLocal8Bit(qgetenv("QT_QPA_EVDEV_TABLET_PARAMETERS"));
+    QString spec = qEnvironmentVariable("QT_QPA_EVDEV_TABLET_PARAMETERS");
 
     if (spec.isEmpty())
         spec = specification;
diff --git a/src/platformsupport/input/evdevtouch/qevdevtouchmanager.cpp b/src/platformsupport/input/evdevtouch/qevdevtouchmanager.cpp
index bd9a3cc6767..dbfe1bad080 100644
--- a/src/platformsupport/input/evdevtouch/qevdevtouchmanager.cpp
+++ b/src/platformsupport/input/evdevtouch/qevdevtouchmanager.cpp
@@ -23,7 +23,7 @@ QEvdevTouchManager::QEvdevTouchManager(const QString &key, const QString &specif
     if (qEnvironmentVariableIsSet("QT_QPA_EVDEV_DEBUG"))
         const_cast<QLoggingCategory &>(qLcEvdevTouch()).setEnabled(QtDebugMsg, true);
 
-    QString spec = QString::fromLocal8Bit(qgetenv("QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS"));
+    QString spec = qEnvironmentVariable("QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS");
 
     if (spec.isEmpty())
         spec = specification;
diff --git a/src/platformsupport/input/shared/qoutputmapping.cpp b/src/platformsupport/input/shared/qoutputmapping.cpp
index c8683958d3c..3b9f6208c42 100644
--- a/src/platformsupport/input/shared/qoutputmapping.cpp
+++ b/src/platformsupport/input/shared/qoutputmapping.cpp
@@ -52,19 +52,19 @@ void QOutputMapping::set(QOutputMapping *mapping)
 
 bool QDefaultOutputMapping::load()
 {
-    static QByteArray configFile = qgetenv("QT_QPA_EGLFS_KMS_CONFIG");
+    static QString configFile = qEnvironmentVariable("QT_QPA_EGLFS_KMS_CONFIG");
     if (configFile.isEmpty())
         return false;
 
-    QFile file(QString::fromUtf8(configFile));
+    QFile file(configFile);
     if (!file.open(QFile::ReadOnly)) {
-        qWarning("touch input support: Failed to open %s", configFile.constData());
+        qWarning("touch input support: Failed to open %ls", qUtf16Printable(configFile));
         return false;
     }
 
     const QJsonDocument doc = QJsonDocument::fromJson(file.readAll());
     if (!doc.isObject()) {
-        qWarning("touch input support: Failed to parse %s", configFile.constData());
+        qWarning("touch input support: Failed to parse %ls", qUtf16Printable(configFile));
         return false;
     }
 
diff --git a/src/plugins/platforminputcontexts/ibus/qibusplatforminputcontext.cpp b/src/plugins/platforminputcontexts/ibus/qibusplatforminputcontext.cpp
index c38cb289c19..d59a6689592 100644
--- a/src/plugins/platforminputcontexts/ibus/qibusplatforminputcontext.cpp
+++ b/src/plugins/platforminputcontexts/ibus/qibusplatforminputcontext.cpp
@@ -731,11 +731,9 @@ QString QIBusPlatformInputContextPrivate::getSocketPath()
     QByteArray displayNumber = "0";
     bool isWayland = false;
 
-    if (qEnvironmentVariableIsSet("IBUS_ADDRESS_FILE")) {
-        QByteArray path = qgetenv("IBUS_ADDRESS_FILE");
-        return QString::fromLocal8Bit(path);
-    } else  if (qEnvironmentVariableIsSet("WAYLAND_DISPLAY")) {
-        display = qgetenv("WAYLAND_DISPLAY");
+    if (QString path = qEnvironmentVariable("IBUS_ADDRESS_FILE"); !path.isNull()) {
+        return path;
+    } else if (display = qgetenv("WAYLAND_DISPLAY"); !display.isEmpty()) {
         isWayland = true;
     } else {
         display = qgetenv("DISPLAY");
diff --git a/src/plugins/platforms/eglfs/api/qeglfshooks.cpp b/src/plugins/platforms/eglfs/api/qeglfshooks.cpp
index 6918d73ffeb..99839fce86b 100644
--- a/src/plugins/platforms/eglfs/api/qeglfshooks.cpp
+++ b/src/plugins/platforms/eglfs/api/qeglfshooks.cpp
@@ -50,29 +50,25 @@ DeviceIntegration::DeviceIntegration()
             }
         }
 
-        QByteArray requested;
-
         // The environment variable can override everything.
-        if (qEnvironmentVariableIsSet("QT_QPA_EGLFS_INTEGRATION")) {
-            requested = qgetenv("QT_QPA_EGLFS_INTEGRATION");
-        } else {
+        QString requested = qEnvironmentVariable("QT_QPA_EGLFS_INTEGRATION");
+        if (requested.isNull()) {
             // Device-specific makespecs may define a preferred plugin.
 #ifdef EGLFS_PREFERRED_PLUGIN
 #define DEFAULT_PLUGIN EGLFS_PREFERRED_PLUGIN
 #define STR(s) #s
 #define STRQ(s) STR(s)
-            requested = STRQ(DEFAULT_PLUGIN);
+            requested = QStringLiteral(STRQ(DEFAULT_PLUGIN));
 #endif
         }
 
         // Treat "none" as special. There has to be a way to indicate
         // that plugins must be ignored when the device is known to be
         // functional with the default, non-specialized integration.
-        if (requested != QByteArrayLiteral("none")) {
+        if (requested != QStringLiteral("none")) {
             if (!requested.isEmpty()) {
-                QString reqStr = QString::fromLocal8Bit(requested);
-                pluginKeys.removeOne(reqStr);
-                pluginKeys.prepend(reqStr);
+                pluginKeys.removeOne(requested);
+                pluginKeys.prepend(requested);
             }
             qCDebug(qLcEglDevDebug) << "EGL device integration plugin keys (sorted):" << pluginKeys;
             while (!m_integration && !pluginKeys.isEmpty()) {
diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index fc5a7e55c50..2c28de316f7 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -531,7 +531,7 @@ QByteArray QXcbIntegration::wmClass() const
         if (m_instanceName)
             name = QString::fromLocal8Bit(m_instanceName);
         if (name.isEmpty() && qEnvironmentVariableIsSet(resourceNameVar))
-            name = QString::fromLocal8Bit(qgetenv(resourceNameVar));
+            name = qEnvironmentVariable(resourceNameVar);
         if (name.isEmpty())
             name = argv0BaseName();
 
diff --git a/src/printsupport/kernel/qplatformprintplugin.cpp b/src/printsupport/kernel/qplatformprintplugin.cpp
index c48e5f65bfc..37222eb039d 100644
--- a/src/printsupport/kernel/qplatformprintplugin.cpp
+++ b/src/printsupport/kernel/qplatformprintplugin.cpp
@@ -54,7 +54,7 @@ QPlatformPrinterSupport *QPlatformPrinterSupportPlugin::get()
         const QMultiMap<int, QString> keyMap = loader()->keyMap();
         QMultiMap<int, QString>::const_iterator it = keyMap.cbegin();
         if (!qEnvironmentVariableIsEmpty("QT_PRINTER_MODULE")) {
-            QString module = QString::fromLocal8Bit(qgetenv("QT_PRINTER_MODULE"));
+            QString module = qEnvironmentVariable("QT_PRINTER_MODULE");
             QMultiMap<int, QString>::const_iterator it2 = std::find_if(keyMap.cbegin(), keyMap.cend(), [module](const QString &value){ return value == module; });
             if (it2 == keyMap.cend())
                 qWarning() << "Unable to load printer plugin" << module;
diff --git a/src/tools/uic/main.cpp b/src/tools/uic/main.cpp
index d46b788419c..9f995a85d40 100644
--- a/src/tools/uic/main.cpp
+++ b/src/tools/uic/main.cpp
@@ -187,7 +187,7 @@ int runUic(int argc, char *argv[])
         if (parser.isSet(pythonPathOption))
             pythonPaths = parser.value(pythonPathOption);
         else if (qEnvironmentVariableIsSet(pythonPathVar))
-            pythonPaths = QString::fromUtf8(qgetenv(pythonPathVar));
+            pythonPaths = qEnvironmentVariable(pythonPathVar);
         driver.option().pythonRoot = pythonRoot(pythonPaths, inputFile);
     }
 
diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index d414cbf841f..d52d678243e 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -3995,11 +3995,11 @@ QString QFileDialogPrivate::getEnvironmentVariable(const QString &string)
 {
 #ifdef Q_OS_UNIX
     if (string.size() > 1 && string.startsWith(u'$')) {
-        return QString::fromLocal8Bit(qgetenv(QStringView{string}.mid(1).toLatin1().constData()));
+        return qEnvironmentVariable(QStringView{string}.mid(1).toLatin1().constData());
     }
 #else
     if (string.size() > 2 && string.startsWith(u'%') && string.endsWith(u'%')) {
-        return QString::fromLocal8Bit(qgetenv(QStringView{string}.mid(1, string.size() - 2).toLatin1().constData()));
+        return qEnvironmentVariable(QStringView{string}.mid(1, string.size() - 2).toLatin1().constData());
     }
 #endif
     return string;
diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index 37be88927e6..95e1761d3e9 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -363,8 +363,8 @@ QWidget *qt_desktopWidget = nullptr;                // root window widgets
 */
 void QApplicationPrivate::process_cmdline()
 {
-    if (styleOverride.isEmpty() && qEnvironmentVariableIsSet("QT_STYLE_OVERRIDE"))
-        styleOverride = QString::fromLocal8Bit(qgetenv("QT_STYLE_OVERRIDE"));
+    if (styleOverride.isEmpty())
+        styleOverride = qEnvironmentVariable("QT_STYLE_OVERRIDE");
 
     // process platform-indep command line
     if (qt_is_tty_app || !argc)
@@ -1411,8 +1411,8 @@ QString QApplicationPrivate::desktopStyleKey()
 {
 #if defined(QT_BUILD_INTERNAL)
     // Allow auto-tests to override the desktop style
-    if (qEnvironmentVariableIsSet("QT_DESKTOP_STYLE_KEY"))
-        return QString::fromLocal8Bit(qgetenv("QT_DESKTOP_STYLE_KEY"));
+    if (QString env = qEnvironmentVariable("QT_DESKTOP_STYLE_KEY"); !env.isNull())
+        return env;
 #endif
 
     // The platform theme might return a style that is not available, find