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iText, a free Java-PDF library
/*
*
* This file is part of the iText (R) project.
Copyright (c) 1998-2022 iText Group NV
* Authors: Kevin Day, Bruno Lowagie, et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License version 3
* as published by the Free Software Foundation with the addition of the
* following permission added to Section 15 as permitted in Section 7(a):
* FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
* ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
* OF THIRD PARTY RIGHTS.
*
* 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 Affero General License for more
* details. You should have received a copy of the GNU Affero General License
* along with this program; if not, see http://www.gnu.org/licenses or write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA, 02110-1301 USA, or download the license from the following URL:
* http://itextpdf.com/terms-of-use/
*
* The interactive user interfaces in modified source and object code versions
* of this program must display Appropriate Legal Notices, as required under
* Section 5 of the GNU Affero General License.
*
* In accordance with Section 7(b) of the GNU Affero General License, a covered
* work must retain the producer line in every PDF that is created or
* manipulated using iText.
*
* You can be released from the requirements of the license by purchasing a
* commercial license. Buying such a license is mandatory as soon as you develop
* commercial activities involving the iText software without disclosing the
* source code of your own applications. These activities include: offering paid
* services to customers as an ASP, serving PDFs on the fly in a web
* application, shipping iText with a closed source product.
*
* For more information, please contact iText Software Corp. at this address:
* [email protected]
*/
package com.itextpdf.text.io;
import java.io.IOException;
import java.nio.channels.FileChannel;
/**
* A RandomAccessSource that represents a memory mapped section of an underlying FileChannel.
* This source can be closed and will automatically re-open as needed.
* This class is an internal implementation detail of the {@link FileChannelRandomAccessSource} class and
* shouldn't be used by general iText users.
* @since 5.3.5
*/
class MappedChannelRandomAccessSource implements RandomAccessSource {
/**
* The underlying channel
*/
private final FileChannel channel;
/**
* The offset into the channel that this source maps to
*/
private final long offset;
/**
* The number of bytes this source maps to
*/
private final long length;
/**
* If the map is active, the actual map. null other wise.
*/
private ByteBufferRandomAccessSource source;
/**
* Create a new source based on the channel. Mapping will not occur until data is actually read.
* @param channel the underlying channel
* @param offset the offset of the map
* @param length the length of the map
*/
public MappedChannelRandomAccessSource(FileChannel channel, long offset, long length) {
if (offset < 0)
throw new IllegalArgumentException(offset + " is negative");
if (length <= 0)
throw new IllegalArgumentException(length + " is zero or negative");
this.channel = channel;
this.offset = offset;
this.length = length;
this.source = null;
}
/**
* Map the region of the channel
* @throws IOException if there is a problem with creating the map
*/
void open() throws IOException {
if (source != null)
return;
if (!channel.isOpen())
throw new IllegalStateException("Channel is closed");
try{
source = new ByteBufferRandomAccessSource(channel.map(FileChannel.MapMode.READ_ONLY, offset, length));
} catch (IOException e){
if (exceptionIsMapFailureException(e))
throw new MapFailedException(e);
throw e;
}
}
/**
* Utility method that determines whether a given IOException is the result
* of a failure to map a memory mapped file. It would be better if the runtime
* provided a special exception for this case, but it doesn't, so we have to rely
* on parsing the exception message.
* @param e the exception to check
* @return true if the exception was the result of a failure to map a memory mapped file
*/
private static boolean exceptionIsMapFailureException(IOException e){
if (e.getMessage() != null && e.getMessage().indexOf("Map failed") >= 0)
return true;
return false;
}
/**
* {@inheritDoc}
*/
public int get(long position) throws IOException {
if (source == null)
throw new IOException("RandomAccessSource not opened");
return source.get(position);
}
/**
* {@inheritDoc}
*/
public int get(long position, byte[] bytes, int off, int len) throws IOException {
if (source == null)
throw new IOException("RandomAccessSource not opened");
return source.get(position, bytes, off, len);
}
/**
* {@inheritDoc}
*/
public long length() {
return length;
}
/**
* {@inheritDoc}
*/
public void close() throws IOException {
if (source == null)
return;
source.close();
source = null;
}
@Override
public String toString() {
return getClass().getName() + " (" + offset + ", " + length + ")";
}
}