Accessibility OS X: protect from accessing invalid objects

Usually when getting an object from an interface, the object
can be assumed to be valid. We need to check isValid though
since the screen reader access is inherently asynchronous and
objects might be in the QWidget destructor where the QObject is
still valid.
Thus check QAccessibleInterface::isValid in all uses of it in the
OS X implementation.

Task-number: QTBUG-50545
Change-Id: I6e142f6ead1b3281cab2cbc61ce1406bbfe29f69
Reviewed-by: Morten Johan Sørvig <morten.sorvig@theqtcompany.com>

2 files changed, 11 insertions, 11 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoaaccessibility.mm b/src/plugins/platforms/cocoa/qcocoaaccessibility.mm
index 723c341e59..624220ae5e 100644
--- a/src/plugins/platforms/cocoa/qcocoaaccessibility.mm
+++ b/src/plugins/platforms/cocoa/qcocoaaccessibility.mm
@@ -51,7 +51,7 @@ QCocoaAccessibility::~QCocoaAccessibility()
 
 void QCocoaAccessibility::notifyAccessibilityUpdate(QAccessibleEvent *event)
 {
-    if (!isActive() || !event->accessibleInterface())
+    if (!isActive() || !event->accessibleInterface() || !event->accessibleInterface()->isValid())
         return;
     QMacAccessibilityElement *element = [QMacAccessibilityElement elementWithId: event->uniqueId()];
     if (!element) {
diff --git a/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm b/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
index 608a7583c0..f554bbfe90 100644
--- a/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
+++ b/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
@@ -120,7 +120,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
     if (!element) {
         QAccessibleInterface *iface = QAccessible::accessibleInterface(anId);
         Q_ASSERT(iface);
-        if (!iface)
+        if (!iface || !iface->isValid())
             return nil;
         element = [[self alloc] initWithId:anId];
         cache->insertElement(anId, element);
@@ -172,7 +172,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
     static NSArray *defaultAttributes = nil;
 
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface)
+    if (!iface || !iface->isValid())
         return defaultAttributes;
 
     if (defaultAttributes == nil) {
@@ -226,7 +226,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 
 - (id)parentElement {
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface)
+    if (!iface || !iface->isValid())
         return nil;
 
     if (QWindow *window = iface->window()) {
@@ -259,7 +259,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 
 - (id)accessibilityAttributeValue:(NSString *)attribute {
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface) {
+    if (!iface || !iface->isValid()) {
         qWarning() << "Called attribute on invalid object: " << axid;
         return nil;
     }
@@ -354,7 +354,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 - (NSArray *)accessibilityParameterizedAttributeNames {
 
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface) {
+    if (!iface || !iface->isValid()) {
         qWarning() << "Called attribute on invalid object: " << axid;
         return nil;
     }
@@ -379,7 +379,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 
 - (id)accessibilityAttributeValue:(NSString *)attribute forParameter:(id)parameter {
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface) {
+    if (!iface || !iface->isValid()) {
         qWarning() << "Called attribute on invalid object: " << axid;
         return nil;
     }
@@ -446,7 +446,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 
 - (BOOL)accessibilityIsAttributeSettable:(NSString *)attribute {
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface)
+    if (!iface || !iface->isValid())
         return NO;
 
     if ([attribute isEqualToString:NSAccessibilityFocusedAttribute]) {
@@ -465,7 +465,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 
 - (void)accessibilitySetValue:(id)value forAttribute:(NSString *)attribute {
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface)
+    if (!iface || !iface->isValid())
         return;
     if ([attribute isEqualToString:NSAccessibilityFocusedAttribute]) {
         if (QAccessibleActionInterface *action = iface->actionInterface())
@@ -494,7 +494,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 - (NSArray *)accessibilityActionNames {
     NSMutableArray * nsActions = [NSMutableArray new];
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface)
+    if (!iface || !iface->isValid())
         return nsActions;
 
     const QStringList &supportedActionNames = QAccessibleBridgeUtils::effectiveActionNames(iface);
@@ -509,7 +509,7 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 
 - (NSString *)accessibilityActionDescription:(NSString *)action {
     QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
-    if (!iface)
+    if (!iface || !iface->isValid())
         return nil; // FIXME is that the right return type??
     QString qtAction = QCocoaAccessible::translateAction(action, iface);
     QString description;