/*
* Copyright 2016 Skynav, Inc. All rights reserved.
* Portions Copyright 2009 Extensible Formatting Systems, Inc (XFSI).
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY SKYNAV, INC. AND ITS CONTRIBUTORS “AS IS” AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL SKYNAV, INC. OR ITS CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.xfsi.xav.validation.images.jpeg;
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.util.LinkedList;
/**
* Handles JPEG input stream. Tracks total bytes read and allows putting back of read data.
*/
class JpegInputStream {
private int readByteCount = 0;
private final DataInputStream inputStream;
private LinkedList<Byte> putBack = new LinkedList<Byte>();
JpegInputStream(InputStream is)
{
this.inputStream = new DataInputStream(is);
}
byte readByte() throws EOFException, IOException
{
if (this.putBack.size() == 0)
{
byte b = this.inputStream.readByte();
this.readByteCount++;
return b;
}
return this.putBack.remove();
}
short readShort() throws EOFException, IOException
{
if (this.putBack.size() == 0)
{
short s = this.inputStream.readShort();
this.readByteCount += 2;
return s;
}
short msb = readByte();
short lsb = readByte();
return (short) ((msb << 8) | (lsb & 0xff));
}
int readInt() throws EOFException, IOException
{
if (this.putBack.size() == 0)
{
int i = this.inputStream.readInt();
this.readByteCount += 4;
return i;
}
int mss = readShort();
int lss = readShort();
return (mss << 16) | (lss & 0xffff);
}
void skipBytes(int count) throws EOFException, IOException
{
// DataInputStream skipBytes() in jpegInputStream does not throw EOFException() if EOF reached,
// which we are interested in, so read the bytes to skip them which WILL generate an EOFException().
for (int i = 0; i < count; i++)
readByte();
}
void putBack(byte b)
{
this.putBack.add(b);
}
int getTotalBytesRead()
{
return this.readByteCount;
}
}