/*
* Copyright 2006-2017 ICEsoft Technologies Canada Corp.
*
* Licensed 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.icepdf.core.pobjects.filters;
import java.io.IOException;
import java.io.InputStream;
/**
* Most of the filters have to read in a chunk of data from their input stream,
* and do some processing on it, before they can make it available to others
*
* @author Mark Collette
* @since 2.0
*/
public abstract class ChunkingInputStream extends InputStream {
protected InputStream in;
protected byte[] buffer;
private int bufferPosition;
private int bufferAvailable;
public ChunkingInputStream() {
in = null;
buffer = null;
bufferPosition = 0;
bufferAvailable = 0;
}
protected void setInputStream(InputStream input) {
in = input;
}
protected void setBufferSize(int size) {
buffer = new byte[size];
}
/**
* For some reason, when reading from InflaterInputStream, if we ask to
* fill a buffer, it will instead only give us a chunk at a time,
* even though more data is available, and buffer.length has bee requested
*
* @throws IOException
*/
protected int fillBufferFromInputStream() throws IOException {
return fillBufferFromInputStream(0, buffer.length);
}
protected int fillBufferFromInputStream(int offset, int length) throws IOException {
int read = 0;
int mayRead = in.available();
int currRead;
try {
while (mayRead >= 0 && read < length) {
currRead = in.read(buffer, offset + read, length - read);
if (currRead < 0 && read == 0)
return currRead;
if (currRead <= 0)
break;
read += currRead;
}
} catch (IOException e) {
// catch the rare and elusive zlib EOF error and keep going
}
return read;
}
/**
* This is only called if bufferAvailable is 0.
* Implementations should read in more data, and return how many bytes are now available
*/
protected abstract int fillInternalBuffer() throws IOException;
private int ensureDataAvailable() throws IOException {
if (bufferAvailable > 0)
return bufferAvailable;
bufferPosition = 0;
bufferAvailable = 0;
int avail = fillInternalBuffer();
if (avail > 0)
bufferAvailable = avail;
return bufferAvailable;
}
//
// InputStream overrides
//
public boolean markSupported() {
return false;
}
public void mark(int readlimit) {
}
public void reset() throws IOException {
}
public int read() throws IOException {
int avail = ensureDataAvailable();
if (avail <= 0)
return -1;
byte b = buffer[bufferPosition];
bufferPosition++;
bufferAvailable--;
return (((int) b) & 0xFF);
}
public int read(byte[] b) throws IOException {
return read(b, 0, b.length);
}
public int read(byte[] b, int off, int length) throws IOException {
int read = 0;
while (read < length) {
int avail = ensureDataAvailable();
if (avail <= 0) {
if (read > 0)
return read;
else
return -1;
}
int toRead = Math.min(length - read, avail);
int srcIdx = bufferPosition;
int dstIdx = off + read;
System.arraycopy(buffer, srcIdx, b, dstIdx, toRead);
bufferPosition += toRead;
bufferAvailable -= toRead;
read += toRead;
}
return read;
}
public long skip(long n) throws IOException {
long skipped = 0L;
while (skipped < n) {
int avail = ensureDataAvailable();
if (avail <= 0) {
if (skipped > 0L)
return skipped;
else
return -1;
}
long toSkip = Math.min(n - skipped, avail);
bufferPosition += toSkip;
bufferAvailable -= toSkip;
skipped += toSkip;
}
return skipped;
}
public int available() throws IOException {
return bufferAvailable;
}
public void close() throws IOException {
if (in != null) {
in.close();
in = null;
}
}
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append(super.toString());
sb.append(": ");
if (in == null)
sb.append("null");
else
sb.append(in.toString());
return sb.toString();
}
}