/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.harmony.luni.util;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* The class contains static {@link java.io.InputStream} utilities.
*/
public class InputStreamExposer {
/**
* Provides access to a protected underlying buffer of
* <code>ByteArrayInputStream</code>.
*/
private static final Field BAIS_BUF;
/**
* Provides access to a protected position in the underlying buffer of
* <code>ByteArrayInputStream</code>.
*/
private static final Field BAIS_POS;
static {
final Field[] f = new Field[2];
AccessController.doPrivileged(new PrivilegedAction<Object>() {
public Object run() {
try {
f[0] = ByteArrayInputStream.class.getDeclaredField("buf");
f[0].setAccessible(true);
f[1] = ByteArrayInputStream.class.getDeclaredField("pos");
f[1].setAccessible(true);
} catch (NoSuchFieldException nsfe) {
throw new InternalError(nsfe.getLocalizedMessage());
}
return null;
}
});
BAIS_BUF = f[0];
BAIS_POS = f[1];
}
/**
* Reads all bytes from {@link java.io.ByteArrayInputStream} using its
* underlying buffer directly.
*
* @return an underlying buffer, if a current position is at the buffer
* beginning, and an end position is at the buffer end, or a copy of
* the underlying buffer part.
*/
private static byte[] expose(ByteArrayInputStream bais) {
byte[] buffer, buf;
int pos;
synchronized (bais) {
int available = bais.available();
try {
buf = (byte[]) BAIS_BUF.get(bais);
pos = BAIS_POS.getInt(bais);
} catch (IllegalAccessException iae) {
throw new InternalError(iae.getLocalizedMessage());
}
if (pos == 0 && available == buf.length) {
buffer = buf;
} else {
buffer = new byte[available];
System.arraycopy(buf, pos, buffer, 0, available);
}
bais.skip(available);
}
return buffer;
}
/**
* The utility method for reading the whole input stream into a snapshot
* buffer. To speed up the access it works with an underlying buffer for a
* given {@link java.io.ByteArrayInputStream}.
*
* @param is
* the stream to be read.
* @return the snapshot wrapping the buffer where the bytes are read to.
* @throws UnsupportedOperationException if the input stream data cannot be exposed
*/
public static byte[] expose(InputStream is) throws IOException, UnsupportedOperationException {
// BEGIN android-changed
// if (is instanceof ExposedByteArrayInputStream) {
// return ((ExposedByteArrayInputStream) is).expose();
// }
// END android-changed
if (is.getClass().equals(ByteArrayInputStream.class)) {
return expose((ByteArrayInputStream) is);
}
// We don't know how to do this
throw new UnsupportedOperationException();
}
}