org.apache.hadoop.dfs.DfsServlet.java Source code

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Here is the source code for org.apache.hadoop.dfs.DfsServlet.java

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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.hadoop.dfs;

import java.io.IOException;

import javax.servlet.ServletContext;
import javax.servlet.http.*;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.security.*;
import org.znerd.xmlenc.XMLOutputter;

/**
 * A base class for the servlets in DFS.
 */
abstract class DfsServlet extends HttpServlet {
    static final Log LOG = LogFactory.getLog(DfsServlet.class.getCanonicalName());

    /** Get {@link UserGroupInformation} from request */
    protected UnixUserGroupInformation getUGI(HttpServletRequest request) {
        String ugi = request.getParameter("ugi");
        try {
            return new UnixUserGroupInformation(ugi.split(","));
        } catch (Exception e) {
            LOG.warn("Invalid ugi (= " + ugi + ")");
        }
        return JspHelper.webUGI;
    }

    /**
     * Create a {@link NameNode} proxy from the current {@link ServletContext}. 
     */
    protected ClientProtocol createNameNodeProxy(UnixUserGroupInformation ugi) throws IOException {
        ServletContext context = getServletContext();
        NameNode nn = (NameNode) context.getAttribute("name.node");
        Configuration conf = new Configuration((Configuration) context.getAttribute("name.conf"));
        UnixUserGroupInformation.saveToConf(conf, UnixUserGroupInformation.UGI_PROPERTY_NAME, ugi);
        return DFSClient.createNamenode(nn.getNameNodeAddress(), conf);
    }

    static void writeRemoteException(String path, RemoteException re, XMLOutputter doc) throws IOException {
        doc.startTag("RemoteException");
        doc.attribute("path", path);
        doc.attribute("class", re.getClassName());
        String msg = re.getLocalizedMessage();
        int i = msg.indexOf("\n");
        if (i >= 0) {
            msg = msg.substring(0, i);
        }
        doc.attribute("message", msg.substring(msg.indexOf(":") + 1).trim());
        doc.endTag();
    }
}