/*
* Copyright (c) 2008, Harald Kuhr
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * 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.
*
* * Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT HOLDER OR 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.twelvemonkeys.io;
import com.twelvemonkeys.lang.
Validate;
import java.io.
FilterInputStream;
import java.io.
IOException;
import java.io.
InputStream;
/**
* An {@code InputStream} reading up to a specified number of bytes from an
* underlying stream.
* <p/>
*
* @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
* @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/SubStream.java#2 $
*/
public final class
SubStream extends
FilterInputStream {
private long
bytesLeft;
private int
markLimit;
/**
* Creates a {@code SubStream} of the given {@code pStream}.
*
* @param pStream the underlying input stream
* @param pLength maximum number of bytes to read drom this stream
*/
public
SubStream(final
InputStream pStream, final long
pLength) {
super(
Validate.
notNull(
pStream, "stream"));
bytesLeft =
pLength;
}
/**
* Marks this stream as closed.
* This implementation does <em>not</em> close the underlying stream.
*/
@
Override
public void
close() throws
IOException {
// NOTE: Do not close the underlying stream
while (
bytesLeft > 0) {
//noinspection ResultOfMethodCallIgnored
skip(
bytesLeft);
}
}
@
Override
public int
available() throws
IOException {
return (int)
Math.
min(super.available(),
bytesLeft);
}
@
Override
public void
mark(int
pReadLimit) {
super.mark(
pReadLimit);// This either succeeds or does nothing...
markLimit =
pReadLimit;
}
@
Override
public void
reset() throws
IOException {
super.reset();// This either succeeds or throws IOException
bytesLeft +=
markLimit;
}
@
Override
public int
read() throws
IOException {
if (
bytesLeft-- <= 0) {
return -1;
}
return super.read();
}
@
Override
public final int
read(byte[]
pBytes) throws
IOException {
return
read(
pBytes, 0,
pBytes.length);
}
@
Override
public int
read(final byte[]
pBytes, final int
pOffset, final int
pLength) throws
IOException {
if (
bytesLeft <= 0) {
return -1;
}
int
read = super.read(
pBytes,
pOffset, (int)
findMaxLen(
pLength));
bytesLeft =
read < 0 ? 0 :
bytesLeft -
read;
return
read;
}
/**
* Finds the maximum number of bytes we can read or skip, from this stream.
*
* @param pLength the requested length
* @return the maximum number of bytes to read
*/
private long
findMaxLen(long
pLength) {
if (
bytesLeft <
pLength) {
return (int)
Math.
max(
bytesLeft, 0);
}
else {
return
pLength;
}
}
@
Override
public long
skip(long
pLength) throws
IOException {
long
skipped = super.skip(
findMaxLen(
pLength));// Skips 0 or more, never -1
bytesLeft -=
skipped;
return
skipped;
}
}