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eXist-db NoSQL Database Core
There is a newer version: 6.3.0
/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2013 The eXist Project
 *  http://exist-db.org
 *  
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *  
 *  This program 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 Lesser General Public License for more details.
 *  
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *  
 *  $Id$
 */
package org.exist.source;

import java.io.*;

import org.exist.dom.persistent.BinaryDocument;
import org.exist.dom.persistent.DocumentImpl;
import org.exist.dom.QName;
import org.exist.dom.persistent.LockedDocument;
import org.exist.security.Permission;
import org.exist.security.PermissionDeniedException;
import org.exist.security.Subject;
import org.exist.security.internal.aider.UnixStylePermissionAider;
import org.exist.storage.DBBroker;
import org.exist.storage.lock.Lock.LockMode;
import org.exist.util.io.FastByteArrayOutputStream;
import org.exist.xmldb.XmldbURI;

/**
 * Source implementation that reads from a binary resource
 * stored in the database.
 * 
 * @author wolf
 */
public class DBSource extends AbstractSource {
    
    private final BinaryDocument doc;
    private final XmldbURI key;
    private final long lastModified;
    private String encoding = "UTF-8";
    private final boolean checkEncoding;
    private final DBBroker broker;
    
    public DBSource(final DBBroker broker, final BinaryDocument doc, final boolean checkXQEncoding) {
        this.broker = broker;
        this.doc = doc;
        this.key = doc.getURI();
        this.lastModified = doc.getMetadata().getLastModified();
        this.checkEncoding = checkXQEncoding;
    }

    @Override
    public String path() {
        return getDocumentPath().toString();
    }

    @Override
    public String type() {
        return "DB";
    }

    /* (non-Javadoc)
             * @see org.exist.source.Source#getKey()
             */
    @Override
    public Object getKey() {
        return key;
    }

    public XmldbURI getDocumentPath() {
    	return key;
    }

    public long getLastModified() {
        return lastModified;
    }

    @Override
    public Validity isValid(final DBBroker broker) {
        Validity result;
        try(final LockedDocument lockedDoc = broker.getXMLResource(key, LockMode.READ_LOCK);) {
            if(lockedDoc == null) {
                result = Validity.INVALID;
            } else if(lockedDoc.getDocument().getMetadata().getLastModified() > lastModified) {
                result = Validity.INVALID;
            } else {
                result = Validity.VALID;
            }
        } catch(final PermissionDeniedException pde) {
            result = Validity.INVALID;
        }

        return result;
    }

    @Override
    public Validity isValid(final Source other) {
        final Validity result;
        if(!(other instanceof DBSource)) {
            result = Validity.INVALID;
        } else if(((DBSource)other).getLastModified() > lastModified) {
            result = Validity.INVALID;
        } else {
            result = Validity.VALID;
        }
        
        return result;
    }

    /* (non-Javadoc)
     * @see org.exist.source.Source#getReader()
     */
    @Override
    public Reader getReader() throws IOException {
        final InputStream is = broker.getBinaryResource(doc);
        final BufferedInputStream bis = new BufferedInputStream(is);
        bis.mark(64);
        checkEncoding(bis);
        bis.reset();
        return new InputStreamReader(bis, encoding);
    }

    @Override
    public InputStream getInputStream() throws IOException {
        return broker.getBinaryResource(doc);
    }

    /* (non-Javadoc)
     * @see org.exist.source.Source#getContent()
     */
    @Override
    public String getContent() throws IOException {
        final long binaryLength = doc.getContentLength();
        if(binaryLength > (long)Integer.MAX_VALUE) {
            throw new IOException("Resource too big to be read using this method.");
        }

        //final byte [] data = new byte[(int)binaryLength];
        try(final InputStream raw = broker.getBinaryResource(doc);
        final FastByteArrayOutputStream buf = new FastByteArrayOutputStream((int)binaryLength)) {
            buf.write(raw);
            //raw.close();
            try (final InputStream is = buf.toFastByteInputStream()) {
                checkEncoding(is);
                return buf.toString(encoding);
            }
        }
    }

    @Override
    public QName isModule() throws IOException {
        try(final InputStream is = broker.getBinaryResource(doc)) {
            return getModuleDecl(is);
        }
    }

    private void checkEncoding(final InputStream is) throws IOException {
        if(checkEncoding) {
            final String checkedEnc = guessXQueryEncoding(is);
            if(checkedEnc != null) {
                encoding = checkedEnc;
            }
        }
    }
    
    @Override
    public String toString() {
    	return doc.getDocumentURI();
    }

    @Override
    public void validate(final Subject subject, final int mode) throws PermissionDeniedException {
        
        //TODO This check should not even be here! Its up to the database to refuse access not requesting source
        
        if(!doc.getPermissions().validate(subject, mode)) {
            final String modeStr = new UnixStylePermissionAider(mode).toString();
            throw new PermissionDeniedException("Subject '" + subject.getName() + "' does not have '" + modeStr + "' access to resource '" + doc.getURI() + "'.");
        }
    }
    
    public Permission getPermissions() {
        return doc.getPermissions();
    }
}