Make sure we don't load invalid SVGs twice

Fixes a bug where loading an invalid SVG that happens
to be valid XML could behave differently in QML and C++,
because readimage() in qquickpixmapcache.cpp calls
QImageReader::size() twice.

Task-number: QTBUG-117944
Pick-to: 6.6 6.5
Change-Id: Ibef7f54627c76414c66f81804f5f46f2db3594ba
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 9 insertions, 7 deletions

diff --git a/src/plugins/imageformats/svg/qsvgiohandler.cpp b/src/plugins/imageformats/svg/qsvgiohandler.cpp
index b04ee6b..570c982 100644
--- a/src/plugins/imageformats/svg/qsvgiohandler.cpp
+++ b/src/plugins/imageformats/svg/qsvgiohandler.cpp
@@ -19,7 +19,7 @@ class QSvgIOHandlerPrivate
 {
 public:
     QSvgIOHandlerPrivate(QSvgIOHandler *qq)
-        : q(qq), loaded(false), readDone(false), backColor(Qt::transparent)
+        : q(qq), loadAttempted(false), loadStatus(false), readDone(false), backColor(Qt::transparent)
     {}
 
     bool load(QIODevice *device);
@@ -31,7 +31,8 @@ public:
     QRect            clipRect;
     QSize            scaledSize;
     QRect            scaledClipRect;
-    bool             loaded;
+    bool             loadAttempted;
+    bool             loadStatus;
     bool             readDone;
     QColor           backColor;
 };
@@ -39,8 +40,9 @@ public:
 
 bool QSvgIOHandlerPrivate::load(QIODevice *device)
 {
-    if (loaded)
-        return true;
+    if (loadAttempted)
+        return loadStatus;
+    loadAttempted = true;
     if (q->format().isEmpty())
         q->canRead();
 
@@ -63,10 +65,10 @@ bool QSvgIOHandlerPrivate::load(QIODevice *device)
 
     if (res) {
         defaultSize = r.defaultSize();
-        loaded = true;
+        loadStatus = true;
     }
 
-    return loaded;
+    return loadStatus;
 }
 
 
@@ -105,7 +107,7 @@ bool QSvgIOHandler::canRead() const
 {
     if (!device())
         return false;
-    if (d->loaded && !d->readDone)
+    if (d->loadStatus && !d->readDone)
         return true;        // Will happen if we have been asked for the size
 
     bool isCompressed = false;