let the user to customize the 403 error page (#1581)

fixes #1575

Author: tulinkry

README.txt

@@ -433,6 +433,9 @@ web.xml of source.war file and change them (see note1) appropriately.
   - The file 'body_include' can be created under DATA_ROOT.
     The contents of this file will be inserted above the footer of the web
     application's "Home" page.
+  - The file 'error_forbidden_include' can be created under DATA_ROOT.
+    The contents of this file will be displayed as the error page when
+    the user is forbidden to see a particular project with HTTP 403 code.
 
 
 5.4.3 - Path Descriptions (optional)

src/org/opensolaris/opengrok/configuration/Configuration.java

@@ -1014,6 +1014,30 @@ public String getBodyIncludeFileContent() {
         return body;
     }
 
+    /**
+     * The name of the file relative to the <var>DATA_ROOT</var>, which should
+     * be included into the error page handling access forbidden errors - HTTP
+     * code 403 Forbidden.
+     */
+    public static final String E_FORBIDDEN_INCLUDE_FILE = "error_forbidden_include";
+
+    private transient String eforbidden_content = null;
+
+    /**
+     * Get the contents of the page for forbidden error page (403 Forbidden)
+     * include file.
+     *
+     * @return an empty string if it could not be read successfully, the
+     * contents of the file otherwise.
+     * @see Configuration#E_FORBIDDEN_INCLUDE_FILE
+     */
+    public String getForbiddenIncludeFileContent() {
+        if (eforbidden_content == null) {
+            eforbidden_content = getFileContent(new File(getDataRoot(), E_FORBIDDEN_INCLUDE_FILE));
+        }
+        return eforbidden_content;
+    }
+
     /**
      * Get the eftar file, which contains definition tags.
      *

web/WEB-INF/web.xml

@@ -127,6 +127,15 @@
 <param-name>keepgenerated</param-name><param-value>true</param-value>
 </init-param>
   </servlet>
+  <servlet>
+      <display-name>Forbidden error handler</display-name>
+      <servlet-name>eforbidden</servlet-name>
+      <jsp-file>/eforbidden.jsp</jsp-file>
+      <init-param>
+          <param-name>keepgenerated</param-name>
+          <param-value>true</param-value>
+      </init-param>
+  </servlet>
   <servlet-mapping>
     <servlet-name>search</servlet-name>
     <url-pattern>/search</url-pattern>		<!-- SEARCH_P -->
@@ -179,6 +188,10 @@
     <servlet-name>enoent</servlet-name>
     <url-pattern>/enoent</url-pattern>		<!-- NOT_FOUND -->
   </servlet-mapping>
+  <servlet-mapping>
+      <servlet-name>eforbidden</servlet-name>
+      <url-pattern>/eforbidden</url-pattern>		<!-- FORBIDDEN -->
+  </servlet-mapping>
   <error-page>
     <error-code>404</error-code>
     <location>/enoent</location>
@@ -187,8 +200,12 @@
     <error-code>500</error-code>
     <location>/error</location>
   </error-page>
+  <error-page>
+      <error-code>403</error-code>
+      <location>/eforbidden</location>
+  </error-page>
   <jsp-config>
-    <jsp-property-group>
+      <jsp-property-group>
       <url-pattern>*.jsp</url-pattern>
       <trim-directive-whitespaces>true</trim-directive-whitespaces>
     </jsp-property-group>

web/eforbidden.jsp

@@ -0,0 +1,30 @@
+<%--
+CDDL HEADER START
+
+The contents of this file are subject to the terms of the
+Common Development and Distribution License (the "License").
+You may not use this file except in compliance with the License.
+
+See LICENSE.txt included in this distribution for the specific
+language governing permissions and limitations under the License.
+
+When distributing Covered Code, include this CDDL HEADER in each
+file and include the License file at LICENSE.txt.
+If applicable, add the following below this CDDL HEADER, with the
+fields enclosed by brackets "[]" replaced with your own identifying
+information: Portions Copyright [yyyy] [name of copyright owner]
+
+CDDL HEADER END
+
+Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+--%><%@page  session="false" isErrorPage="true" import="
+             org.opensolaris.opengrok.web.PageConfig"
+%><%
+    /* ---------------------- eforbidden.jspf start --------------------- */
+    {
+%>
+<%= PageConfig.get(request).getEnv().getConfiguration().getForbiddenIncludeFileContent()%>
+<%
+    }
+    /* ---------------------- eforbidden.jspf end --------------------- */
+%>