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	/*
	* Copyright (c) 1994, 2021, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.io;

	import java.util.Arrays;
	import java.util.Objects;

	/**
	* A {@code ByteArrayInputStream} contains
	* an internal buffer that contains bytes that
	* may be read from the stream. An internal
	* counter keeps track of the next byte to
	* be supplied by the {@code read} method.
	* <p>
	* Closing a {@code ByteArrayInputStream} has no effect. The methods in
	* this class can be called after the stream has been closed without
	* generating an {@code IOException}.
	*
	* @author Arthur van Hoff
	* @see java.io.StringBufferInputStream
	* @since 1.0
	*/
	public class ByteArrayInputStream extends InputStream {

	/**
	* An array of bytes that was provided
	* by the creator of the stream. Elements {@code buf[0]}
	* through {@code buf[count-1]} are the
	* only bytes that can ever be read from the
	* stream; element {@code buf[pos]} is
	* the next byte to be read.
	*/
	protected byte buf[];

	/**
	* The index of the next character to read from the input stream buffer.
	* This value should always be nonnegative
	* and not larger than the value of {@code count}.
	* The next byte to be read from the input stream buffer
	* will be {@code buf[pos]}.
	*/
	protected int pos;

	/**
	* The currently marked position in the stream.
	* ByteArrayInputStream objects are marked at position zero by
	* default when constructed. They may be marked at another
	* position within the buffer by the {@code mark()} method.
	* The current buffer position is set to this point by the
	* {@code reset()} method.
	* <p>
	* If no mark has been set, then the value of mark is the offset
	* passed to the constructor (or 0 if the offset was not supplied).
	*
	* @since 1.1
	*/
	protected int mark = 0;

	/**
	* The index one greater than the last valid character in the input
	* stream buffer.
	* This value should always be nonnegative
	* and not larger than the length of {@code buf}.
	* It is one greater than the position of
	* the last byte within {@code buf} that
	* can ever be read from the input stream buffer.
	*/
	protected int count;

	/**
	* Creates a {@code ByteArrayInputStream}
	* so that it uses {@code buf} as its
	* buffer array.
	* The buffer array is not copied.
	* The initial value of {@code pos}
	* is {@code 0} and the initial value
	* of {@code count} is the length of
	* {@code buf}.
	*
	* @param buf the input buffer.
	*/
	public ByteArrayInputStream(byte buf[]) {
	this.buf = buf;
	this.pos = 0;
	this.count = buf.length;
	}

	/**
	* Creates {@code ByteArrayInputStream}
	* that uses {@code buf} as its
	* buffer array. The initial value of {@code pos}
	* is {@code offset} and the initial value
	* of {@code count} is the minimum of {@code offset+length}
	* and {@code buf.length}.
	* The buffer array is not copied. The buffer's mark is
	* set to the specified offset.
	*
	* @param buf the input buffer.
	* @param offset the offset in the buffer of the first byte to read.
	* @param length the maximum number of bytes to read from the buffer.
	*/
	public ByteArrayInputStream(byte buf[], int offset, int length) {
	this.buf = buf;
	this.pos = offset;
	this.count = Math.min(offset + length, buf.length);
	this.mark = offset;
	}

	/**
	* Reads the next byte of data from this input stream. The value
	* byte is returned as an {@code int} in the range
	* {@code 0} to {@code 255}. If no byte is available
	* because the end of the stream has been reached, the value
	* {@code -1} is returned.
	* <p>
	* This {@code read} method
	* cannot block.
	*
	* @return the next byte of data, or {@code -1} if the end of the
	* stream has been reached.
	*/
	public synchronized int read() {
	return (pos < count) ? (buf[pos++] & 0xff) : -1;
	}

	/**
	* Reads up to {@code len} bytes of data into an array of bytes from this
	* input stream. If {@code pos} equals {@code count}, then {@code -1} is
	* returned to indicate end of file. Otherwise, the number {@code k} of
	* bytes read is equal to the smaller of {@code len} and {@code count-pos}.
	* If {@code k} is positive, then bytes {@code buf[pos]} through
	* {@code buf[pos+k-1]} are copied into {@code b[off]} through
	* {@code b[off+k-1]} in the manner performed by {@code System.arraycopy}.
	* The value {@code k} is added into {@code pos} and {@code k} is returned.
	* <p>
	* Unlike the {@link InputStream#read(byte[],int,int) overridden method}
	* of {@code InputStream}, this method returns {@code -1} instead of zero
	* if the end of the stream has been reached and {@code len == 0}.
	* <p>
	* This {@code read} method cannot block.
	*
	* @param b the buffer into which the data is read.
	* @param off the start offset in the destination array {@code b}
	* @param len the maximum number of bytes read.
	* @return the total number of bytes read into the buffer, or
	* {@code -1} if there is no more data because the end of
	* the stream has been reached.
	* @throws NullPointerException If {@code b} is {@code null}.
	* @throws IndexOutOfBoundsException If {@code off} is negative,
	* {@code len} is negative, or {@code len} is greater than
	* {@code b.length - off}
	*/
	public synchronized int read(byte b[], int off, int len) {
	Objects.checkFromIndexSize(off, len, b.length);

	if (pos >= count) {
	return -1;
	}

	int avail = count - pos;
	if (len > avail) {
	len = avail;
	}
	if (len <= 0) {
	return 0;
	}
	System.arraycopy(buf, pos, b, off, len);
	pos += len;
	return len;
	}

	public synchronized byte[] readAllBytes() {
	byte[] result = Arrays.copyOfRange(buf, pos, count);
	pos = count;
	return result;
	}

	public int readNBytes(byte[] b, int off, int len) {
	int n = read(b, off, len);
	return n == -1 ? 0 : n;
	}

	public synchronized long transferTo(OutputStream out) throws IOException {
	int len = count - pos;
	out.write(buf, pos, len);
	pos = count;
	return len;
	}

	/**
	* Skips {@code n} bytes of input from this input stream. Fewer
	* bytes might be skipped if the end of the input stream is reached.
	* The actual number {@code k}
	* of bytes to be skipped is equal to the smaller
	* of {@code n} and {@code count-pos}.
	* The value {@code k} is added into {@code pos}
	* and {@code k} is returned.
	*
	* @param n the number of bytes to be skipped.
	* @return the actual number of bytes skipped.
	*/
	public synchronized long skip(long n) {
	long k = count - pos;
	if (n < k) {
	k = n < 0 ? 0 : n;
	}

	pos += k;
	return k;
	}

	/**
	* Returns the number of remaining bytes that can be read (or skipped over)
	* from this input stream.
	* <p>
	* The value returned is {@code count - pos},
	* which is the number of bytes remaining to be read from the input buffer.
	*
	* @return the number of remaining bytes that can be read (or skipped
	* over) from this input stream without blocking.
	*/
	public synchronized int available() {
	return count - pos;
	}

	/**
	* Tests if this {@code InputStream} supports mark/reset. The
	* {@code markSupported} method of {@code ByteArrayInputStream}
	* always returns {@code true}.
	*
	* @since 1.1
	*/
	public boolean markSupported() {
	return true;
	}

	/**
	* Set the current marked position in the stream.
	* ByteArrayInputStream objects are marked at position zero by
	* default when constructed. They may be marked at another
	* position within the buffer by this method.
	* <p>
	* If no mark has been set, then the value of the mark is the
	* offset passed to the constructor (or 0 if the offset was not
	* supplied).
	*
	* <p> Note: The {@code readAheadLimit} for this class
	* has no meaning.
	*
	* @since 1.1
	*/
	public void mark(int readAheadLimit) {
	mark = pos;
	}

	/**
	* Resets the buffer to the marked position. The marked position
	* is 0 unless another position was marked or an offset was specified
	* in the constructor.
	*/
	public synchronized void reset() {
	pos = mark;
	}

	/**
	* Closing a {@code ByteArrayInputStream} has no effect. The methods in
	* this class can be called after the stream has been closed without
	* generating an {@code IOException}.
	*/
	public void close() throws IOException {
	}

	}

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