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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jasper.runtime;

import java.io.IOException;
import java.io.Writer;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Enumeration;
import java.util.HashMap;

import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.ValueExpression;
import javax.servlet.RequestDispatcher;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspFactory;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.el.ELException;
import javax.servlet.jsp.el.ExpressionEvaluator;
import javax.servlet.jsp.el.VariableResolver;
import javax.servlet.jsp.tagext.BodyContent;

import org.apache.jasper.compiler.Localizer;
import org.apache.jasper.el.ELContextImpl;
import org.apache.jasper.el.ExpressionEvaluatorImpl;
import org.apache.jasper.el.FunctionMapperImpl;
import org.apache.jasper.el.VariableResolverImpl;
import org.apache.jasper.security.SecurityUtil;
import org.apache.jasper.util.Enumerator;

/**
 * Implementation of the PageContext class from the JSP spec. Also doubles as a
 * VariableResolver for the EL.
 * 
 * @author Anil K. Vijendran
 * @author Larry Cable
 * @author Hans Bergsten
 * @author Pierre Delisle
 * @author Mark Roth
 * @author Jan Luehe
 * @author Jacob Hookom
 */
public class PageContextImpl extends PageContext {

    private static final JspFactory jspf = JspFactory.getDefaultFactory(); 

    private BodyContentImpl[] outs;

    private int depth;

    // per-servlet state
    private Servlet servlet;

    private ServletConfig config;

    private ServletContext context;

    private JspApplicationContextImpl applicationContext;

    private String errorPageURL;

    // page-scope attributes
    private transient HashMap attributes;

    // per-request state
    private transient ServletRequest request;

    private transient ServletResponse response;

    private transient HttpSession session;
    
    private transient ELContextImpl elContext;

    private boolean isIncluded;
    
    
    // initial output stream
    private transient JspWriter out;

    private transient JspWriterImpl baseOut;

    /*
     * Constructor.
     */
    PageContextImpl() {
        this.outs = new BodyContentImpl[0];
        this.attributes = new HashMap(16);
        this.depth = -1;
    }

    @Override
    public void initialize(Servlet servlet, ServletRequest request,
            ServletResponse response, String errorPageURL,
            boolean needsSession, int bufferSize, boolean autoFlush)
            throws IOException {

        _initialize(servlet, request, response, errorPageURL, needsSession,
                bufferSize, autoFlush);
    }

    private void _initialize(Servlet servlet, ServletRequest request,
            ServletResponse response, String errorPageURL,
            boolean needsSession, int bufferSize, boolean autoFlush) {

        // initialize state
        this.servlet = servlet;
        this.config = servlet.getServletConfig();
        this.context = config.getServletContext();
        this.errorPageURL = errorPageURL;
        this.request = request;
        this.response = response;
        
        // initialize application context
        this.applicationContext = JspApplicationContextImpl.getInstance(context);

        // Setup session (if required)
        if (request instanceof HttpServletRequest && needsSession)
            this.session = ((HttpServletRequest) request).getSession();
        if (needsSession && session == null)
            throw new IllegalStateException(
                    "Page needs a session and none is available");

        // initialize the initial out ...
        depth = -1;
        if (this.baseOut == null) {
            this.baseOut = new JspWriterImpl(response, bufferSize, autoFlush);
        } else {
            this.baseOut.init(response, bufferSize, autoFlush);
        }
        this.out = baseOut;

        // register names/values as per spec
        setAttribute(OUT, this.out);
        setAttribute(REQUEST, request);
        setAttribute(RESPONSE, response);

        if (session != null)
            setAttribute(SESSION, session);

        setAttribute(PAGE, servlet);
        setAttribute(CONFIG, config);
        setAttribute(PAGECONTEXT, this);
        setAttribute(APPLICATION, context);

        isIncluded = request.getAttribute(
                RequestDispatcher.INCLUDE_SERVLET_PATH) != null;
    }

    @Override
    public void release() {
        out = baseOut;
        try {
            if (isIncluded) {
                ((JspWriterImpl) out).flushBuffer();
                // push it into the including jspWriter
            } else {
                // Old code:
                // out.flush();
                // Do not flush the buffer even if we're not included (i.e.
                // we are the main page. The servlet will flush it and close
                // the stream.
                ((JspWriterImpl) out).flushBuffer();
            }
        } catch (IOException ex) {
            IllegalStateException ise = new IllegalStateException(Localizer.getMessage("jsp.error.flush"), ex);
            throw ise;
        } finally {
            servlet = null;
            config = null;
            context = null;
            applicationContext = null;
            elContext = null;
            errorPageURL = null;
            request = null;
            response = null;
            depth = -1;
            baseOut.recycle();
            session = null;
            attributes.clear();
            for (BodyContentImpl body: outs) {
                body.recycle();
            }
        }
    }

    @Override
    public Object getAttribute(final String name) {

        if (name == null) {
            throw new NullPointerException(Localizer
                    .getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()) {
            return AccessController.doPrivileged(
                    new PrivilegedAction() {
                @Override
                public Object run() {
                    return doGetAttribute(name);
                }
            });
        } else {
            return doGetAttribute(name);
        }

    }

    private Object doGetAttribute(String name) {
        return attributes.get(name);
    }

    @Override
    public Object getAttribute(final String name, final int scope) {

        if (name == null) {
            throw new NullPointerException(Localizer
                    .getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()) {
            return AccessController.doPrivileged(
                    new PrivilegedAction() {
                @Override
                public Object run() {
                    return doGetAttribute(name, scope);
                }
            });
        } else {
            return doGetAttribute(name, scope);
        }

    }

    private Object doGetAttribute(String name, int scope) {
        switch (scope) {
        case PAGE_SCOPE:
            return attributes.get(name);

        case REQUEST_SCOPE:
            return request.getAttribute(name);

        case SESSION_SCOPE:
            if (session == null) {
                throw new IllegalStateException(Localizer
                        .getMessage("jsp.error.page.noSession"));
            }
            return session.getAttribute(name);

        case APPLICATION_SCOPE:
            return context.getAttribute(name);

        default:
            throw new IllegalArgumentException("Invalid scope");
        }
    }

    @Override
    public void setAttribute(final String name, final Object attribute) {

        if (name == null) {
            throw new NullPointerException(Localizer
                    .getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()) {
            AccessController.doPrivileged(new PrivilegedAction() {
                @Override
                public Void run() {
                    doSetAttribute(name, attribute);
                    return null;
                }
            });
        } else {
            doSetAttribute(name, attribute);
        }
    }

    private void doSetAttribute(String name, Object attribute) {
        if (attribute != null) {
            attributes.put(name, attribute);
        } else {
            removeAttribute(name, PAGE_SCOPE);
        }
    }

    @Override
    public void setAttribute(final String name, final Object o, final int scope) {

        if (name == null) {
            throw new NullPointerException(Localizer
                    .getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()) {
            AccessController.doPrivileged(new PrivilegedAction() {
                @Override
                public Void run() {
                    doSetAttribute(name, o, scope);
                    return null;
                }
            });
        } else {
            doSetAttribute(name, o, scope);
        }

    }

    private void doSetAttribute(String name, Object o, int scope) {
        if (o != null) {
            switch (scope) {
            case PAGE_SCOPE:
                attributes.put(name, o);
                break;

            case REQUEST_SCOPE:
                request.setAttribute(name, o);
                break;

            case SESSION_SCOPE:
                if (session == null) {
                    throw new IllegalStateException(Localizer
                            .getMessage("jsp.error.page.noSession"));
                }
                session.setAttribute(name, o);
                break;

            case APPLICATION_SCOPE:
                context.setAttribute(name, o);
                break;

            default:
                throw new IllegalArgumentException("Invalid scope");
            }
        } else {
            removeAttribute(name, scope);
        }
    }

    @Override
    public void removeAttribute(final String name, final int scope) {

        if (name == null) {
            throw new NullPointerException(Localizer
                    .getMessage("jsp.error.attribute.null_name"));
        }
        if (SecurityUtil.isPackageProtectionEnabled()) {
            AccessController.doPrivileged(new PrivilegedAction() {
                @Override
                public Void run() {
                    doRemoveAttribute(name, scope);
                    return null;
                }
            });
        } else {
            doRemoveAttribute(name, scope);
        }
    }

    private void doRemoveAttribute(String name, int scope) {
        switch (scope) {
        case PAGE_SCOPE:
            attributes.remove(name);
            break;

        case REQUEST_SCOPE:
            request.removeAttribute(name);
            break;

        case SESSION_SCOPE:
            if (session == null) {
                throw new IllegalStateException(Localizer
                        .getMessage("jsp.error.page.noSession"));
            }
            session.removeAttribute(name);
            break;

        case APPLICATION_SCOPE:
            context.removeAttribute(name);
            break;

        default:
            throw new IllegalArgumentException("Invalid scope");
        }
    }

    @Override
    public int getAttributesScope(final String name) {

        if (name == null) {
            throw new NullPointerException(Localizer
                    .getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (AccessController
                    .doPrivileged(new PrivilegedAction() {
                        @Override
                        public Integer run() {
                            return new Integer(doGetAttributeScope(name));
                        }
                    })).intValue();
        } else {
            return doGetAttributeScope(name);
        }
    }

    private int doGetAttributeScope(String name) {
        if (attributes.get(name) != null)
            return PAGE_SCOPE;

        if (request.getAttribute(name) != null)
            return REQUEST_SCOPE;

        if (session != null) {
            try {
                if (session.getAttribute(name) != null)
                    return SESSION_SCOPE;
            } catch(IllegalStateException ise) {
                // Session has been invalidated.
                // Ignore and fall through to application scope.
            }
        }

        if (context.getAttribute(name) != null)
            return APPLICATION_SCOPE;

        return 0;
    }

    @Override
    public Object findAttribute(final String name) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return AccessController.doPrivileged(
                    new PrivilegedAction() {
                @Override
                public Object run() {
                    if (name == null) {
                        throw new NullPointerException(Localizer
                                .getMessage("jsp.error.attribute.null_name"));
                    }

                    return doFindAttribute(name);
                }
            });
        } else {
            if (name == null) {
                throw new NullPointerException(Localizer
                        .getMessage("jsp.error.attribute.null_name"));
            }

            return doFindAttribute(name);
        }
    }

    private Object doFindAttribute(String name) {

        Object o = attributes.get(name);
        if (o != null)
            return o;

        o = request.getAttribute(name);
        if (o != null)
            return o;

        if (session != null) {
            try {
                o = session.getAttribute(name);
            } catch(IllegalStateException ise) {
                // Session has been invalidated.
                // Ignore and fall through to application scope.
            }
            if (o != null)
                return o;
        }

        return context.getAttribute(name);
    }

    @Override
    public Enumeration getAttributeNamesInScope(final int scope) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return AccessController.doPrivileged(
                    new PrivilegedAction>() {
                        @Override
                        public Enumeration run() {
                            return doGetAttributeNamesInScope(scope);
                        }
                    });
        } else {
            return doGetAttributeNamesInScope(scope);
        }
    }

    private Enumeration doGetAttributeNamesInScope(int scope) {
        switch (scope) {
        case PAGE_SCOPE:
            return new Enumerator(attributes.keySet().iterator());

        case REQUEST_SCOPE:
            return request.getAttributeNames();

        case SESSION_SCOPE:
            if (session == null) {
                throw new IllegalStateException(Localizer
                        .getMessage("jsp.error.page.noSession"));
            }
            return session.getAttributeNames();

        case APPLICATION_SCOPE:
            return context.getAttributeNames();

        default:
            throw new IllegalArgumentException("Invalid scope");
        }
    }

    @Override
    public void removeAttribute(final String name) {

        if (name == null) {
            throw new NullPointerException(Localizer
                    .getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()) {
            AccessController.doPrivileged(new PrivilegedAction() {
                @Override
                public Void run() {
                    doRemoveAttribute(name);
                    return null;
                }
            });
        } else {
            doRemoveAttribute(name);
        }
    }

    private void doRemoveAttribute(String name) {
        removeAttribute(name, PAGE_SCOPE);
        removeAttribute(name, REQUEST_SCOPE);
        if( session != null ) {
            try {
                removeAttribute(name, SESSION_SCOPE);
            } catch(IllegalStateException ise) {
                // Session has been invalidated.
                // Ignore and fall throw to application scope.
            }
        }
        removeAttribute(name, APPLICATION_SCOPE);
    }

    @Override
    public JspWriter getOut() {
        return out;
    }

    @Override
    public HttpSession getSession() {
        return session;
    }

    public Servlet getServlet() {
        return servlet;
    }

    @Override
    public ServletConfig getServletConfig() {
        return config;
    }

    @Override
    public ServletContext getServletContext() {
        return config.getServletContext();
    }

    @Override
    public ServletRequest getRequest() {
        return request;
    }

    @Override
    public ServletResponse getResponse() {
        return response;
    }

    /**
     * Returns the exception associated with this page context, if any. 

* Added wrapping for Throwables to avoid ClassCastException: see Bugzilla * 31171 for details. * * @return The Exception associated with this page context, if any. */ @Override public Exception getException() { Throwable t = JspRuntimeLibrary.getThrowable(request); // Only wrap if needed if ((t != null) && (!(t instanceof Exception))) { t = new JspException(t); } return (Exception) t; } @Override public Object getPage() { return servlet; } private final String getAbsolutePathRelativeToContext(String relativeUrlPath) { String path = relativeUrlPath; if (!path.startsWith("/")) { String uri = (String) request.getAttribute( RequestDispatcher.INCLUDE_SERVLET_PATH); if (uri == null) uri = ((HttpServletRequest) request).getServletPath(); String baseURI = uri.substring(0, uri.lastIndexOf('/')); path = baseURI + '/' + path; } return path; } @Override public void include(String relativeUrlPath) throws ServletException, IOException { JspRuntimeLibrary .include(request, response, relativeUrlPath, out, true); } @Override public void include(final String relativeUrlPath, final boolean flush) throws ServletException, IOException { if (SecurityUtil.isPackageProtectionEnabled()) { try { AccessController.doPrivileged( new PrivilegedExceptionAction() { @Override public Void run() throws Exception { doInclude(relativeUrlPath, flush); return null; } }); } catch (PrivilegedActionException e) { Exception ex = e.getException(); if (ex instanceof IOException) { throw (IOException) ex; } else { throw (ServletException) ex; } } } else { doInclude(relativeUrlPath, flush); } } private void doInclude(String relativeUrlPath, boolean flush) throws ServletException, IOException { JspRuntimeLibrary.include(request, response, relativeUrlPath, out, flush); } @Override @Deprecated public VariableResolver getVariableResolver() { return new VariableResolverImpl(this.getELContext()); } @Override public void forward(final String relativeUrlPath) throws ServletException, IOException { if (SecurityUtil.isPackageProtectionEnabled()) { try { AccessController.doPrivileged( new PrivilegedExceptionAction() { @Override public Void run() throws Exception { doForward(relativeUrlPath); return null; } }); } catch (PrivilegedActionException e) { Exception ex = e.getException(); if (ex instanceof IOException) { throw (IOException) ex; } else { throw (ServletException) ex; } } } else { doForward(relativeUrlPath); } } private void doForward(String relativeUrlPath) throws ServletException, IOException { // JSP.4.5 If the buffer was flushed, throw IllegalStateException try { out.clear(); } catch (IOException ex) { IllegalStateException ise = new IllegalStateException(Localizer .getMessage("jsp.error.attempt_to_clear_flushed_buffer")); ise.initCause(ex); throw ise; } // Make sure that the response object is not the wrapper for include while (response instanceof ServletResponseWrapperInclude) { response = ((ServletResponseWrapperInclude) response).getResponse(); } final String path = getAbsolutePathRelativeToContext(relativeUrlPath); String includeUri = (String) request.getAttribute( RequestDispatcher.INCLUDE_SERVLET_PATH); if (includeUri != null) request.removeAttribute(RequestDispatcher.INCLUDE_SERVLET_PATH); try { context.getRequestDispatcher(path).forward(request, response); } finally { if (includeUri != null) request.setAttribute(RequestDispatcher.INCLUDE_SERVLET_PATH, includeUri); } } @Override public BodyContent pushBody() { return (BodyContent) pushBody(null); } @Override public JspWriter pushBody(Writer writer) { depth++; if (depth >= outs.length) { BodyContentImpl[] newOuts = new BodyContentImpl[depth + 1]; for (int i = 0; i < outs.length; i++) { newOuts[i] = outs[i]; } newOuts[depth] = new BodyContentImpl(out); outs = newOuts; } outs[depth].setWriter(writer); out = outs[depth]; // Update the value of the "out" attribute in the page scope // attribute namespace of this PageContext setAttribute(OUT, out); return outs[depth]; } @Override public JspWriter popBody() { depth--; if (depth >= 0) { out = outs[depth]; } else { out = baseOut; } // Update the value of the "out" attribute in the page scope // attribute namespace of this PageContext setAttribute(OUT, out); return out; } /** * Provides programmatic access to the ExpressionEvaluator. The JSP * Container must return a valid instance of an ExpressionEvaluator that can * parse EL expressions. */ @Override @Deprecated public ExpressionEvaluator getExpressionEvaluator() { return new ExpressionEvaluatorImpl(this.applicationContext.getExpressionFactory()); } @Override public void handlePageException(Exception ex) throws IOException, ServletException { // Should never be called since handleException() called with a // Throwable in the generated servlet. handlePageException((Throwable) ex); } @Override public void handlePageException(final Throwable t) throws IOException, ServletException { if (t == null) throw new NullPointerException("null Throwable"); if (SecurityUtil.isPackageProtectionEnabled()) { try { AccessController.doPrivileged( new PrivilegedExceptionAction() { @Override public Void run() throws Exception { doHandlePageException(t); return null; } }); } catch (PrivilegedActionException e) { Exception ex = e.getException(); if (ex instanceof IOException) { throw (IOException) ex; } else { throw (ServletException) ex; } } } else { doHandlePageException(t); } } private void doHandlePageException(Throwable t) throws IOException, ServletException { if (errorPageURL != null && !errorPageURL.equals("")) { /* * Set request attributes. Do not set the * javax.servlet.error.exception attribute here (instead, set in the * generated servlet code for the error page) in order to prevent * the ErrorReportValve, which is invoked as part of forwarding the * request to the error page, from throwing it if the response has * not been committed (the response will have been committed if the * error page is a JSP page). */ request.setAttribute(PageContext.EXCEPTION, t); request.setAttribute(RequestDispatcher.ERROR_STATUS_CODE, new Integer(HttpServletResponse.SC_INTERNAL_SERVER_ERROR)); request.setAttribute(RequestDispatcher.ERROR_REQUEST_URI, ((HttpServletRequest) request).getRequestURI()); request.setAttribute(RequestDispatcher.ERROR_SERVLET_NAME, config.getServletName()); try { forward(errorPageURL); } catch (IllegalStateException ise) { include(errorPageURL); } // The error page could be inside an include. Object newException = request.getAttribute(RequestDispatcher.ERROR_EXCEPTION); // t==null means the attribute was not set. if ((newException != null) && (newException == t)) { request.removeAttribute(RequestDispatcher.ERROR_EXCEPTION); } // now clear the error code - to prevent double handling. request.removeAttribute(RequestDispatcher.ERROR_STATUS_CODE); request.removeAttribute(RequestDispatcher.ERROR_REQUEST_URI); request.removeAttribute(RequestDispatcher.ERROR_SERVLET_NAME); request.removeAttribute(PageContext.EXCEPTION); } else { // Otherwise throw the exception wrapped inside a ServletException. // Set the exception as the root cause in the ServletException // to get a stack trace for the real problem if (t instanceof IOException) throw (IOException) t; if (t instanceof ServletException) throw (ServletException) t; if (t instanceof RuntimeException) throw (RuntimeException) t; Throwable rootCause = null; if (t instanceof JspException) { rootCause = ((JspException) t).getCause(); } else if (t instanceof ELException) { rootCause = ((ELException) t).getCause(); } if (rootCause != null) { throw new ServletException(t.getClass().getName() + ": " + t.getMessage(), rootCause); } throw new ServletException(t); } } private static String XmlEscape(String s) { if (s == null) return null; StringBuilder sb = new StringBuilder(); for (int i = 0; i < s.length(); i++) { char c = s.charAt(i); if (c == '<') { sb.append("<"); } else if (c == '>') { sb.append(">"); } else if (c == '\'') { sb.append("'"); // ' } else if (c == '&') { sb.append("&"); } else if (c == '"') { sb.append("""); // " } else { sb.append(c); } } return sb.toString(); } /** * Proprietary method to evaluate EL expressions. XXX - This method should * go away once the EL interpreter moves out of JSTL and into its own * project. For now, this is necessary because the standard machinery is too * slow. * * @param expression * The expression to be evaluated * @param expectedType * The expected resulting type * @param pageContext * The page context * @param functionMap * Maps prefix and name to Method * @return The result of the evaluation */ public static Object proprietaryEvaluate(final String expression, final Class expectedType, final PageContext pageContext, final ProtectedFunctionMapper functionMap, final boolean escape) throws ELException { Object retValue; final ExpressionFactory exprFactory = jspf.getJspApplicationContext(pageContext.getServletContext()).getExpressionFactory(); if (SecurityUtil.isPackageProtectionEnabled()) { try { retValue = AccessController .doPrivileged(new PrivilegedExceptionAction() { @Override public Object run() throws Exception { ELContextImpl ctx = (ELContextImpl) pageContext.getELContext(); ctx.setFunctionMapper(new FunctionMapperImpl(functionMap)); ValueExpression ve = exprFactory.createValueExpression(ctx, expression, expectedType); return ve.getValue(ctx); } }); } catch (PrivilegedActionException ex) { Exception realEx = ex.getException(); if (realEx instanceof ELException) { throw (ELException) realEx; } else { throw new ELException(realEx); } } } else { ELContextImpl ctx = (ELContextImpl) pageContext.getELContext(); ctx.setFunctionMapper(new FunctionMapperImpl(functionMap)); ValueExpression ve = exprFactory.createValueExpression(ctx, expression, expectedType); retValue = ve.getValue(ctx); } if (escape && retValue != null) { retValue = XmlEscape(retValue.toString()); } return retValue; } @Override public ELContext getELContext() { if (this.elContext == null) { this.elContext = this.applicationContext.createELContext(this); } return this.elContext; } }