Quick: Sanitize reading environment variables.

Where possible, use qEnvironmentVariableIsSet()/
qEnvironmentVariableIsEmpty() instead of checking on the
return value of qgetenv().
Where the value is required, add a check using one of
qEnvironmentVariableIsSet()/Empty().

Move QSGAtlasTexture::qsg_envInt() to qsgrenderer.cpp
for reuse as qt_sg_envInt() and add qt_sg_envFloat().

Change-Id: I4c93f16c228d4f537154f389a0fa1427654485f7
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

9 files changed, 71 insertions, 67 deletions

diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
index 60ada14c32..66a8f6fbd3 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
@@ -61,6 +61,8 @@ QT_BEGIN_NAMESPACE
 
 extern QByteArray qsgShaderRewriter_insertZAttributes(const char *input, QSurfaceFormat::OpenGLContextProfile profile);
 
+int qt_sg_envInt(const char *name, int defaultValue);
+
 namespace QSGBatchRenderer
 {
 
@@ -785,30 +787,17 @@ Renderer::Renderer(QSGRenderContext *ctx)
     }
 
     m_bufferStrategy = GL_STATIC_DRAW;
-    QByteArray strategy = qgetenv("QSG_RENDERER_BUFFER_STRATEGY");
-    if (strategy == "dynamic") {
-        m_bufferStrategy = GL_DYNAMIC_DRAW;
-    } else if (strategy == "stream") {
-        m_bufferStrategy = GL_STREAM_DRAW;
-    }
-
-    m_batchNodeThreshold = 64;
-    QByteArray alternateThreshold = qgetenv("QSG_RENDERER_BATCH_NODE_THRESHOLD");
-    if (alternateThreshold.length() > 0) {
-        bool ok = false;
-        int threshold = alternateThreshold.toInt(&ok);
-        if (ok)
-            m_batchNodeThreshold = threshold;
-    }
-
-    m_batchVertexThreshold = 1024;
-    alternateThreshold = qgetenv("QSG_RENDERER_BATCH_VERTEX_THRESHOLD");
-    if (alternateThreshold.length() > 0) {
-        bool ok = false;
-        int threshold = alternateThreshold.toInt(&ok);
-        if (ok)
-            m_batchVertexThreshold = threshold;
+    if (Q_UNLIKELY(qEnvironmentVariableIsSet("QSG_RENDERER_BUFFER_STRATEGY"))) {
+        const QByteArray strategy = qgetenv("QSG_RENDERER_BUFFER_STRATEGY");
+        if (strategy == "dynamic")
+            m_bufferStrategy = GL_DYNAMIC_DRAW;
+        else if (strategy == "stream")
+            m_bufferStrategy = GL_STREAM_DRAW;
     }
+
+    m_batchNodeThreshold = qt_sg_envInt("QSG_RENDERER_BATCH_NODE_THRESHOLD", 64);
+    m_batchVertexThreshold = qt_sg_envInt("QSG_RENDERER_BATCH_VERTEX_THRESHOLD", 1024);
+
     if (Q_UNLIKELY(debug_build() || debug_render())) {
         qDebug() << "Batch thresholds: nodes:" << m_batchNodeThreshold << " vertices:" << m_batchVertexThreshold;
         qDebug() << "Using buffer strategy:" << (m_bufferStrategy == GL_STATIC_DRAW ? "static" : (m_bufferStrategy == GL_DYNAMIC_DRAW ? "dynamic" : "stream"));
diff --git a/src/quick/scenegraph/coreapi/qsgmaterial.cpp b/src/quick/scenegraph/coreapi/qsgmaterial.cpp
index c68c0b93d2..633cab8078 100644
--- a/src/quick/scenegraph/coreapi/qsgmaterial.cpp
+++ b/src/quick/scenegraph/coreapi/qsgmaterial.cpp
@@ -64,7 +64,7 @@ const char *QSGMaterialShaderPrivate::loadShaderSource(QOpenGLShader::ShaderType
 }
 
 #ifndef QT_NO_DEBUG
-static bool qsg_leak_check = !qgetenv("QML_LEAK_CHECK").isEmpty();
+static const bool qsg_leak_check = !qEnvironmentVariableIsEmpty("QML_LEAK_CHECK");
 #endif
 
 /*!
diff --git a/src/quick/scenegraph/coreapi/qsgnode.cpp b/src/quick/scenegraph/coreapi/qsgnode.cpp
index 51f3976ed9..c09af7c0a3 100644
--- a/src/quick/scenegraph/coreapi/qsgnode.cpp
+++ b/src/quick/scenegraph/coreapi/qsgnode.cpp
@@ -42,7 +42,7 @@
 QT_BEGIN_NAMESPACE
 
 #ifndef QT_NO_DEBUG
-static bool qsg_leak_check = !qgetenv("QML_LEAK_CHECK").isEmpty();
+static const bool qsg_leak_check = !qEnvironmentVariableIsEmpty("QML_LEAK_CHECK");
 static int qt_node_count = 0;
 
 static void qt_print_node_count()
diff --git a/src/quick/scenegraph/coreapi/qsgrenderer.cpp b/src/quick/scenegraph/coreapi/qsgrenderer.cpp
index a9752cb9a9..775277e588 100644
--- a/src/quick/scenegraph/coreapi/qsgrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgrenderer.cpp
@@ -40,12 +40,21 @@
 
 QT_BEGIN_NAMESPACE
 
-static bool qsg_sanity_check = qgetenv("QSG_SANITY_CHECK").toInt();
+static const bool qsg_sanity_check = qEnvironmentVariableIntValue("QSG_SANITY_CHECK");
 
 static QElapsedTimer frameTimer;
 static qint64 preprocessTime;
 static qint64 updatePassTime;
 
+int qt_sg_envInt(const char *name, int defaultValue)
+{
+    if (Q_LIKELY(!qEnvironmentVariableIsSet(name)))
+        return defaultValue;
+    bool ok = false;
+    int value = qgetenv(name).toInt(&ok);
+    return ok ? value : defaultValue;
+}
+
 void QSGBindable::clear(QSGAbstractRenderer::ClearMode mode) const
 {
     GLuint bits = 0;
diff --git a/src/quick/scenegraph/qsgcontext.cpp b/src/quick/scenegraph/qsgcontext.cpp
index 150f8475d8..dd6977e42e 100644
--- a/src/quick/scenegraph/qsgcontext.cpp
+++ b/src/quick/scenegraph/qsgcontext.cpp
@@ -134,8 +134,8 @@ static bool qsg_useConsistentTiming()
 {
     static int use = -1;
     if (use < 0) {
-        QByteArray fixed = qgetenv("QSG_FIXED_ANIMATION_STEP");
-        use = !(fixed.isEmpty() || fixed == "no");
+        use = !qEnvironmentVariableIsEmpty("QSG_FIXED_ANIMATION_STEP") && qgetenv("QSG_FIXED_ANIMATION_STEP") != "no"
+            ? 1 : 0;
         qCDebug(QSG_LOG_INFO, "Using %s", bool(use) ? "fixed animation steps" : "sg animation driver");
     }
     return bool(use);
@@ -297,15 +297,16 @@ QSGContext::QSGContext(QObject *parent) :
     QObject(*(new QSGContextPrivate), parent)
 {
     Q_D(QSGContext);
-    QByteArray mode = qgetenv("QSG_DISTANCEFIELD_ANTIALIASING");
-    if (!mode.isEmpty())
+    if (Q_UNLIKELY(!qEnvironmentVariableIsEmpty("QSG_DISTANCEFIELD_ANTIALIASING"))) {
+        const QByteArray mode = qgetenv("QSG_DISTANCEFIELD_ANTIALIASING");
         d->distanceFieldAntialiasingDecided = true;
-    if (mode == "subpixel")
-        d->distanceFieldAntialiasing = QSGGlyphNode::HighQualitySubPixelAntialiasing;
-    else if (mode == "subpixel-lowq")
-        d->distanceFieldAntialiasing = QSGGlyphNode::LowQualitySubPixelAntialiasing;
-    else if (mode == "gray")
-        d->distanceFieldAntialiasing = QSGGlyphNode::GrayAntialiasing;
+        if (mode == "subpixel")
+            d->distanceFieldAntialiasing = QSGGlyphNode::HighQualitySubPixelAntialiasing;
+        else if (mode == "subpixel-lowq")
+            d->distanceFieldAntialiasing = QSGGlyphNode::LowQualitySubPixelAntialiasing;
+        else if (mode == "gray")
+            d->distanceFieldAntialiasing = QSGGlyphNode::GrayAntialiasing;
+    }
 
     // Adds compatibility with Qt 5.3 and earlier's QSG_RENDER_TIMING
     if (qEnvironmentVariableIsSet("QSG_RENDER_TIMING")) {
@@ -333,12 +334,14 @@ void QSGContext::renderContextInitialized(QSGRenderContext *renderContext)
 
     d->mutex.lock();
     if (d->antialiasingMethod == UndecidedAntialiasing) {
-        QByteArray aaType = qgetenv("QSG_ANTIALIASING_METHOD");
-        if (aaType == "msaa") {
-            d->antialiasingMethod = MsaaAntialiasing;
-        } else if (aaType == "vertex") {
-            d->antialiasingMethod = VertexAntialiasing;
-        } else {
+        if (Q_UNLIKELY(qEnvironmentVariableIsSet("QSG_ANTIALIASING_METHOD"))) {
+            const QByteArray aaType = qgetenv("QSG_ANTIALIASING_METHOD");
+            if (aaType == "msaa")
+                d->antialiasingMethod = MsaaAntialiasing;
+            else if (aaType == "vertex")
+                d->antialiasingMethod = VertexAntialiasing;
+        }
+        if (d->antialiasingMethod == UndecidedAntialiasing) {
             if (renderContext->openglContext()->format().samples() > 0)
                 d->antialiasingMethod = MsaaAntialiasing;
             else
diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index 87dd521807..68947d3a3c 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -199,13 +199,15 @@ QSGRenderLoop *QSGRenderLoop::instance()
             else if (qmlForceThreadedRenderer())
                 loopType = ThreadedRenderLoop;
 
-            const QByteArray loopName = qgetenv("QSG_RENDER_LOOP");
-            if (loopName == QByteArrayLiteral("windows"))
-                loopType = WindowsRenderLoop;
-            else if (loopName == QByteArrayLiteral("basic"))
-                loopType = BasicRenderLoop;
-            else if (loopName == QByteArrayLiteral("threaded"))
-                loopType = ThreadedRenderLoop;
+            if (Q_UNLIKELY(qEnvironmentVariableIsSet("QSG_RENDER_LOOP"))) {
+                const QByteArray loopName = qgetenv("QSG_RENDER_LOOP");
+                if (loopName == QByteArrayLiteral("windows"))
+                    loopType = WindowsRenderLoop;
+                else if (loopName == QByteArrayLiteral("basic"))
+                    loopType = BasicRenderLoop;
+                else if (loopName == QByteArrayLiteral("threaded"))
+                    loopType = ThreadedRenderLoop;
+            }
 
             switch (loopType) {
             case ThreadedRenderLoop:
diff --git a/src/quick/scenegraph/util/qsgatlastexture.cpp b/src/quick/scenegraph/util/qsgatlastexture.cpp
index 8c649fb6bd..8e8e870505 100644
--- a/src/quick/scenegraph/util/qsgatlastexture.cpp
+++ b/src/quick/scenegraph/util/qsgatlastexture.cpp
@@ -54,21 +54,13 @@ QT_BEGIN_NAMESPACE
 #define GL_BGRA 0x80E1
 #endif
 
+int qt_sg_envInt(const char *name, int defaultValue);
 
 static QElapsedTimer qsg_renderer_timer;
 
 namespace QSGAtlasTexture
 {
 
-static int qsg_envInt(const char *name, int defaultValue)
-{
-    QByteArray content = qgetenv(name);
-
-    bool ok = false;
-    int value = content.toInt(&ok);
-    return ok ? value : defaultValue;
-}
-
 Manager::Manager()
     : m_atlas(0)
 {
@@ -79,8 +71,8 @@ Manager::Manager()
     int max;
     gl->functions()->glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max);
 
-    int w = qMin(max, qsg_envInt("QSG_ATLAS_WIDTH", qMax(512U, qNextPowerOfTwo(surfaceSize.width() - 1))));
-    int h = qMin(max, qsg_envInt("QSG_ATLAS_HEIGHT", qMax(512U, qNextPowerOfTwo(surfaceSize.height() - 1))));
+    int w = qMin(max, qt_sg_envInt("QSG_ATLAS_WIDTH", qMax(512U, qNextPowerOfTwo(surfaceSize.width() - 1))));
+    int h = qMin(max, qt_sg_envInt("QSG_ATLAS_HEIGHT", qMax(512U, qNextPowerOfTwo(surfaceSize.height() - 1))));
 
     if (surface->surfaceClass() == QSurface::Window) {
         QWindow *window = static_cast<QWindow *>(surface);
@@ -91,7 +83,7 @@ Manager::Manager()
         }
     }
 
-    m_atlas_size_limit = qsg_envInt("QSG_ATLAS_SIZE_LIMIT", qMax(w, h) / 2);
+    m_atlas_size_limit = qt_sg_envInt("QSG_ATLAS_SIZE_LIMIT", qMax(w, h) / 2);
     m_atlas_size = QSize(w, h);
 
     qCDebug(QSG_LOG_INFO, "texture atlas dimensions: %dx%d", w, h);
diff --git a/src/quick/scenegraph/util/qsgdistancefieldutil.cpp b/src/quick/scenegraph/util/qsgdistancefieldutil.cpp
index 8e02681703..96b606aa3c 100644
--- a/src/quick/scenegraph/util/qsgdistancefieldutil.cpp
+++ b/src/quick/scenegraph/util/qsgdistancefieldutil.cpp
@@ -39,18 +39,27 @@
 
 QT_BEGIN_NAMESPACE
 
+static float qt_sg_envFloat(const char *name, float defaultValue)
+{
+    if (Q_LIKELY(!qEnvironmentVariableIsSet(name)))
+        return defaultValue;
+    bool ok = false;
+    const float value = qgetenv(name).toFloat(&ok);
+    return ok ? value : defaultValue;
+}
+
 static float defaultThresholdFunc(float glyphScale)
 {
-    static float base = qgetenv("QT_DF_BASE").isEmpty() ? 0.5f : qgetenv("QT_DF_BASE").toFloat();
-    static float baseDev = qgetenv("QT_DF_BASEDEVIATION").isEmpty() ? 0.065f : qgetenv("QT_DF_BASEDEVIATION").toFloat();
-    static float devScaleMin = qgetenv("QT_DF_SCALEFORMAXDEV").isEmpty() ? 0.15f : qgetenv("QT_DF_SCALEFORMAXDEV").toFloat();
-    static float devScaleMax = qgetenv("QT_DF_SCALEFORNODEV").isEmpty() ? 0.3f : qgetenv("QT_DF_SCALEFORNODEV").toFloat();
+    static const float base = qt_sg_envFloat("QT_DF_BASE", 0.5f);
+    static const float baseDev = qt_sg_envFloat("QT_DF_BASEDEVIATION", 0.065f);
+    static const float devScaleMin = qt_sg_envFloat("QT_DF_SCALEFORMAXDEV", 0.15f);
+    static const float devScaleMax = qt_sg_envFloat("QT_DF_SCALEFORNODEV", 0.3f);
     return base - ((qBound(devScaleMin, glyphScale, devScaleMax) - devScaleMin) / (devScaleMax - devScaleMin) * -baseDev + baseDev);
 }
 
 static float defaultAntialiasingSpreadFunc(float glyphScale)
 {
-    static float range = qgetenv("QT_DF_RANGE").isEmpty() ? 0.06f : qgetenv("QT_DF_RANGE").toFloat();
+    static const float range = qt_sg_envFloat("QT_DF_RANGE", 0.06f);
     return range / glyphScale;
 }
 
diff --git a/src/quick/scenegraph/util/qsgtexture.cpp b/src/quick/scenegraph/util/qsgtexture.cpp
index c89ad7a608..df9e569ca3 100644
--- a/src/quick/scenegraph/util/qsgtexture.cpp
+++ b/src/quick/scenegraph/util/qsgtexture.cpp
@@ -65,7 +65,7 @@
 static QElapsedTimer qsg_renderer_timer;
 
 #ifndef QT_NO_DEBUG
-static bool qsg_leak_check = !qgetenv("QML_LEAK_CHECK").isEmpty();
+static const bool qsg_leak_check = !qEnvironmentVariableIsEmpty("QML_LEAK_CHECK");
 #endif