8213431: Improve file protocol handling

Reviewed-by: chegar, dfuchs, igerasim, rhalade, weijun

src/java.base/windows/classes/sun/net/www/protocol/file/Handler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -95,7 +95,7 @@ public synchronized URLConnection openConnection(URL url, Proxy p)
         path = "\\\\" + host + path;
         File f = new File(path);
         if (f.exists()) {
-            return createFileURLConnection(url, f);
+            return new UNCFileURLConnection(url, f, path);
         }
 
         /*

src/java.base/windows/classes/sun/net/www/protocol/file/UNCFileURLConnection.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package sun.net.www.protocol.file;
+
+import java.io.File;
+import java.io.FilePermission;
+import java.net.URL;
+import java.security.Permission;
+
+final class UNCFileURLConnection extends FileURLConnection {
+
+    private final String effectivePath;
+    private volatile Permission permission;
+
+    UNCFileURLConnection(URL u, File file, String effectivePath) {
+        super(u, file);
+        this.effectivePath = effectivePath;
+    }
+
+    @Override
+    public Permission getPermission() {
+        Permission perm = permission;
+        if (perm == null) {
+            permission = perm = new FilePermission(effectivePath, "read");
+        }
+        return perm;
+    }
+}
+