8174098: Better image fetching

Reviewed-by: serb, vadim, skoivu

src/share/classes/sun/awt/image/ImageWatched.java

@@ -29,6 +29,10 @@ import java.lang.ref.WeakReference;
 import java.awt.Image;
 import java.awt.image.ImageObserver;
 
+import java.security.AccessControlContext;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+
 public abstract class ImageWatched {
     public static Link endlink = new Link();
 
@@ -85,16 +89,26 @@ public abstract class ImageWatched {
         }
     }
 
+    static class AccWeakReference<T> extends WeakReference<T> {
+
+         private final AccessControlContext acc;
+
+         AccWeakReference(T ref) {
+             super(ref);
+             acc = AccessController.getContext();
+         }
+    }
+
     /*
      * Standard Link implementation to manage a Weak Reference
      * to an ImageObserver.
      */
     public static class WeakLink extends Link {
-        private WeakReference<ImageObserver> myref;
+        private final AccWeakReference<ImageObserver> myref;
         private Link next;
 
         public WeakLink(ImageObserver obs, Link next) {
-            myref = new WeakReference<ImageObserver>(obs);
+            myref = new AccWeakReference<ImageObserver>(obs);
             this.next = next;
         }
 
@@ -120,6 +134,19 @@ public abstract class ImageWatched {
             return this;
         }
 
+        private static boolean update(ImageObserver iw, AccessControlContext acc,
+                                      Image img, int info,
+                                      int x, int y, int w, int h) {
+
+            if (acc != null || System.getSecurityManager() != null) {
+                return AccessController.doPrivileged(
+                       (PrivilegedAction<Boolean>) () -> {
+                            return iw.imageUpdate(img, info, x, y, w, h);
+                      }, acc);
+            }
+            return false;
+        }
+
         public boolean newInfo(Image img, int info,
                                int x, int y, int w, int h)
         {
@@ -129,7 +156,7 @@ public abstract class ImageWatched {
             if (myiw == null) {
                 // My referent is null so we must prune in a second pass.
                 ret = true;
-            } else if (myiw.imageUpdate(img, info, x, y, w, h) == false) {
+            } else if (update(myiw, myref.acc, img, info, x, y, w, h) == false) {
                 // My referent has lost interest so clear it and ask
                 // for a pruning pass to remove it later.
                 myref.clear();