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/**
* 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.commons.crypto.stream.input;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
* The Input interface abstract the input source of
* CryptoInputStream so that different implementation of input can
* be used. The implementation Input interface will usually wraps an input
* mechanism such as InputStream or
* ReadableByteChannel.
*/
public interface Input {
/**
* Reads a sequence of bytes from input into the given buffer.
*
*
* An attempt is made to read up to r bytes from the input, where
* r is the number of bytes remaining in the buffer, that is,
* dst.remaining(), at the moment this method is invoked.
*
*
* Suppose that a byte sequence of length n is read, where 0
* <= n <= r.
* This byte sequence will be transferred into the buffer so that the first
* byte in the sequence is at index p and the last byte is at index
* p + n - 1,
* where p is the buffer's position at the moment this method is
* invoked. Upon return the buffer's position will be equal to
* p + n; its limit will not have changed.
*
* @param dst The buffer into which bytes are to be transferred.
* @return the total number of bytes read into the buffer, or
* -1 if there is no more data because the end of the
* stream has been reached.
* @throws IOException If some other I/O error occurs.
*/
int read(ByteBuffer dst) throws IOException;
/**
* Skips over and discards n bytes of data from this input The
* skip method may, for a variety of reasons, end up skipping
* over some smaller number of bytes, possibly 0. This may
* result from any of a number of conditions; reaching end of file before
* n bytes have been skipped is only one possibility. The
* actual number of bytes skipped is returned. If n is
* negative, no bytes are skipped.
*
*
* The skip method of this class creates a byte array and then
* repeatedly reads into it until n bytes have been read or the
* end of the stream has been reached. Subclasses are encouraged to provide
* a more efficient implementation of this method. For instance, the
* implementation may depend on the ability to seek.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @throws IOException if the stream does not support seek, or if some
* other I/O error occurs.
*/
long skip(long n) throws IOException;
/**
* Returns an estimate of the number of bytes that can be read (or skipped
* over) from this input without blocking by the next invocation of a method
* for this input stream. The next invocation might be the same thread or
* another thread. A single read or skip of this many bytes will not block,
* but may read or skip fewer bytes.
*
*
* It is never correct to use the return value of this method to allocate a
* buffer intended to hold all data in this stream.
*
* @return an estimate of the number of bytes that can be read (or skipped
* over) from this input stream without blocking or {@code 0} when
* it reaches the end of the input stream.
* @throws IOException if an I/O error occurs.
*/
int available() throws IOException;
/**
* Reads up to the specified number of bytes from a given position within a
* stream and return the number of bytes read. This does not change the
* current offset of the stream and is thread-safe.
*
* An implementation may not support positioned read. If the implementation
* doesn't support positioned read, it throws UnsupportedOperationException.
*
* @param position the given position within a stream.
* @param buffer the buffer into which the data is read.
* @param offset the start offset in array buffer.
* @param length the maximum number of bytes to read.
* @return the total number of bytes read into the buffer, or
* -1 if there is no more data because the end of the
* stream has been reached.
* @throws IOException if an I/O error occurs.
*/
int read(long position, byte[] buffer, int offset, int length)
throws IOException;
/**
* Seeks to the given offset from the start of the stream. The next read()
* will be from that location.
*
* An implementation may not support seek. If the implementation doesn't
* support seek, it throws UnsupportedOperationException.
*
* @param position the offset from the start of the stream.
* @throws IOException if an I/O error occurs.
*/
void seek(long position) throws IOException;
/**
* Closes this input and releases any system resources associated with the
* under layer input.
*
* @throws IOException if an I/O error occurs.
*/
void close() throws IOException;
}