/*
 * Copyright (c) 1994, 2018, 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.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;

/**
 * This abstract class is the superclass of all classes representing
 * an input stream of bytes.
 *
 * <p> Applications that need to define a subclass of <code>InputStream</code>
 * must always provide a method that returns the next byte of input.
 *
 * @author Arthur van Hoff
 * @see java.io.BufferedInputStream
 * @see java.io.ByteArrayInputStream
 * @see java.io.DataInputStream
 * @see java.io.FilterInputStream
 * @see java.io.InputStream#read()
 * @see java.io.OutputStream
 * @see java.io.PushbackInputStream
 * @since 1.0
 */
public abstract class InputStream implements Closeable {

 // MAX_SKIP_BUFFER_SIZE is used to determine the maximum buffer size to
 // use when skipping.
 private static final int MAX_SKIP_BUFFER_SIZE = 2048;

 private static final int DEFAULT_BUFFER_SIZE = 8192;

 /**
 * Returns a new {@code InputStream} that reads no bytes. The returned
 * stream is initially open. The stream is closed by calling the
 * {@code close()} method. Subsequent calls to {@code close()} have no
 * effect.
 *
 * <p> While the stream is open, the {@code available()}, {@code read()},
 * {@code read(byte[])}, {@code read(byte[], int, int)},
 * {@code readAllBytes()}, {@code readNBytes(byte[], int, int)},
 * {@code readNBytes(int)}, {@code skip(long)}, {@code skipNBytes(long)},
 * and {@code transferTo()} methods all behave as if end of stream has been
 * reached. After the stream has been closed, these methods all throw
 * {@code IOException}.
 *
 * <p> The {@code markSupported()} method returns {@code false}. The
 * {@code mark()} method does nothing, and the {@code reset()} method
 * throws {@code IOException}.
 *
 * @return an {@code InputStream} which contains no bytes
 *
 * @since 11
 */
 public static InputStream nullInputStream() {
 return new InputStream() {
 private volatile boolean closed;

 private void ensureOpen() throws IOException {
 if (closed) {
 throw new IOException("Stream closed");
 }
 }

 @Override
 public int available () throws IOException {
 ensureOpen();
 return 0;
 }

 @Override
 public int read() throws IOException {
 ensureOpen();
 return -1;
 }

 @Override
 public int read(byte[] b, int off, int len) throws IOException {
 Objects.checkFromIndexSize(off, len, b.length);
 if (len == 0) {
 return 0;
 }
 ensureOpen();
 return -1;
 }

 @Override
 public byte[] readAllBytes() throws IOException {
 ensureOpen();
 return new byte[0];
 }

 @Override
 public int readNBytes(byte[] b, int off, int len)
 throws IOException {
 Objects.checkFromIndexSize(off, len, b.length);
 ensureOpen();
 return 0;
 }

 @Override
 public byte[] readNBytes(int len) throws IOException {
 if (len < 0) {
 throw new IllegalArgumentException("len < 0");
 }
 ensureOpen();
 return new byte[0];
 }

 @Override
 public long skip(long n) throws IOException {
 ensureOpen();
 return 0L;
 }

 @Override
 public void skipNBytes(long n) throws IOException {
 ensureOpen();
 if (n > 0) {
 throw new EOFException();
 }
 }

 @Override
 public long transferTo(OutputStream out) throws IOException {
 Objects.requireNonNull(out);
 ensureOpen();
 return 0L;
 }

 @Override
 public void close() throws IOException {
 closed = true;
 }
 };
 }

 /**
 * Reads the next byte of data from the input stream. The value byte is
 * returned as an <code>int</code> in the range <code>0</code> to
 * <code>255</code>. If no byte is available because the end of the stream
 * has been reached, the value <code>-1</code> is returned. This method
 * blocks until input data is available, the end of the stream is detected,
 * or an exception is thrown.
 *
 * <p> A subclass must provide an implementation of this method.
 *
 * @return the next byte of data, or <code>-1</code> if the end of the
 * stream is reached.
 * @exception IOException if an I/O error occurs.
 */
 public abstract int read() throws IOException;

 /**
 * Reads some number of bytes from the input stream and stores them into
 * the buffer array <code>b</code>. The number of bytes actually read is
 * returned as an integer. This method blocks until input data is
 * available, end of file is detected, or an exception is thrown.
 *
 * <p> If the length of <code>b</code> is zero, then no bytes are read and
 * <code>0</code> is returned; otherwise, there is an attempt to read at
 * least one byte. If no byte is available because the stream is at the
 * end of the file, the value <code>-1</code> is returned; otherwise, at
 * least one byte is read and stored into <code>b</code>.
 *
 * <p> The first byte read is stored into element <code>b[0]</code>, the
 * next one into <code>b[1]</code>, and so on. The number of bytes read is,
 * at most, equal to the length of <code>b</code>. Let <i>k</i> be the
 * number of bytes actually read; these bytes will be stored in elements
 * <code>b[0]</code> through <code>b[</code><i>k</i><code>-1]</code>,
 * leaving elements <code>b[</code><i>k</i><code>]</code> through
 * <code>b[b.length-1]</code> unaffected.
 *
 * <p> The <code>read(b)</code> method for class <code>InputStream</code>
 * has the same effect as: <pre><code> read(b, 0, b.length) </code></pre>
 *
 * @param b the buffer into which the data is read.
 * @return the total number of bytes read into the buffer, or
 * <code>-1</code> if there is no more data because the end of
 * the stream has been reached.
 * @exception IOException If the first byte cannot be read for any reason
 * other than the end of the file, if the input stream has been closed, or
 * if some other I/O error occurs.
 * @exception NullPointerException if <code>b</code> is <code>null</code>.
 * @see java.io.InputStream#read(byte[], int, int)
 */
 public int read(byte b[]) throws IOException {
 return read(b, 0, b.length);
 }

 /**
 * Reads up to <code>len</code> bytes of data from the input stream into
 * an array of bytes. An attempt is made to read as many as
 * <code>len</code> bytes, but a smaller number may be read.
 * The number of bytes actually read is returned as an integer.
 *
 * <p> This method blocks until input data is available, end of file is
 * detected, or an exception is thrown.
 *
 * <p> If <code>len</code> is zero, then no bytes are read and
 * <code>0</code> is returned; otherwise, there is an attempt to read at
 * least one byte. If no byte is available because the stream is at end of
 * file, the value <code>-1</code> is returned; otherwise, at least one
 * byte is read and stored into <code>b</code>.
 *
 * <p> The first byte read is stored into element <code>b[off]</code>, the
 * next one into <code>b[off+1]</code>, and so on. The number of bytes read
 * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of
 * bytes actually read; these bytes will be stored in elements
 * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>,
 * leaving elements <code>b[off+</code><i>k</i><code>]</code> through
 * <code>b[off+len-1]</code> unaffected.
 *
 * <p> In every case, elements <code>b[0]</code> through
 * <code>b[off]</code> and elements <code>b[off+len]</code> through
 * <code>b[b.length-1]</code> are unaffected.
 *
 * <p> The <code>read(b,</code> <code>off,</code> <code>len)</code> method
 * for class <code>InputStream</code> simply calls the method
 * <code>read()</code> repeatedly. If the first such call results in an
 * <code>IOException</code>, that exception is returned from the call to
 * the <code>read(b,</code> <code>off,</code> <code>len)</code> method. If
 * any subsequent call to <code>read()</code> results in a
 * <code>IOException</code>, the exception is caught and treated as if it
 * were end of file; the bytes read up to that point are stored into
 * <code>b</code> and the number of bytes read before the exception
 * occurred is returned. The default implementation of this method blocks
 * until the requested amount of input data <code>len</code> has been read,
 * end of file is detected, or an exception is thrown. Subclasses are
 * encouraged to provide a more efficient implementation of this method.
 *
 * @param b the buffer into which the data is read.
 * @param off the start offset in array <code>b</code>
 * at which the data is written.
 * @param len the maximum number of bytes to read.
 * @return the total number of bytes read into the buffer, or
 * <code>-1</code> if there is no more data because the end of
 * the stream has been reached.
 * @exception IOException If the first byte cannot be read for any reason
 * other than end of file, or if the input stream has been closed, or if
 * some other I/O error occurs.
 * @exception NullPointerException If <code>b</code> is <code>null</code>.
 * @exception IndexOutOfBoundsException If <code>off</code> is negative,
 * <code>len</code> is negative, or <code>len</code> is greater than
 * <code>b.length - off</code>
 * @see java.io.InputStream#read()
 */
 public int read(byte b[], int off, int len) throws IOException {
 Objects.checkFromIndexSize(off, len, b.length);
 if (len == 0) {
 return 0;
 }

 int c = read();
 if (c == -1) {
 return -1;
 }
 b[off] = (byte)c;

 int i = 1;
 try {
 for (; i < len ; i++) {
 c = read();
 if (c == -1) {
 break;
 }
 b[off + i] = (byte)c;
 }
 } catch (IOException ee) {
 }
 return i;
 }

 /**
 * The maximum size of array to allocate.
 * Some VMs reserve some header words in an array.
 * Attempts to allocate larger arrays may result in
 * OutOfMemoryError: Requested array size exceeds VM limit
 */
 private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8;

 /**
 * Reads all remaining bytes from the input stream. This method blocks until
 * all remaining bytes have been read and end of stream is detected, or an
 * exception is thrown. This method does not close the input stream.
 *
 * <p> When this stream reaches end of stream, further invocations of this
 * method will return an empty byte array.
 *
 * <p> Note that this method is intended for simple cases where it is
 * convenient to read all bytes into a byte array. It is not intended for
 * reading input streams with large amounts of data.
 *
 * <p> The behavior for the case where the input stream is <i>asynchronously
 * closed</i>, or the thread interrupted during the read, is highly input
 * stream specific, and therefore not specified.
 *
 * <p> If an I/O error occurs reading from the input stream, then it may do
 * so after some, but not all, bytes have been read. Consequently the input
 * stream may not be at end of stream and may be in an inconsistent state.
 * It is strongly recommended that the stream be promptly closed if an I/O
 * error occurs.
 *
 * @implSpec
 * This method invokes {@link #readNBytes(int)} with a length of
 * {@link Integer#MAX_VALUE}.
 *
 * @return a byte array containing the bytes read from this input stream
 * @throws IOException if an I/O error occurs
 * @throws OutOfMemoryError if an array of the required size cannot be
 * allocated.
 *
 * @since 9
 */
 public byte[] readAllBytes() throws IOException {
 return readNBytes(Integer.MAX_VALUE);
 }

 /**
 * Reads up to a specified number of bytes from the input stream. This
 * method blocks until the requested number of bytes have been read, end
 * of stream is detected, or an exception is thrown. This method does not
 * close the input stream.
 *
 * <p> The length of the returned array equals the number of bytes read
 * from the stream. If {@code len} is zero, then no bytes are read and
 * an empty byte array is returned. Otherwise, up to {@code len} bytes
 * are read from the stream. Fewer than {@code len} bytes may be read if
 * end of stream is encountered.
 *
 * <p> When this stream reaches end of stream, further invocations of this
 * method will return an empty byte array.
 *
 * <p> Note that this method is intended for simple cases where it is
 * convenient to read the specified number of bytes into a byte array. The
 * total amount of memory allocated by this method is proportional to the
 * number of bytes read from the stream which is bounded by {@code len}.
 * Therefore, the method may be safely called with very large values of
 * {@code len} provided sufficient memory is available.
 *
 * <p> The behavior for the case where the input stream is <i>asynchronously
 * closed</i>, or the thread interrupted during the read, is highly input
 * stream specific, and therefore not specified.
 *
 * <p> If an I/O error occurs reading from the input stream, then it may do
 * so after some, but not all, bytes have been read. Consequently the input
 * stream may not be at end of stream and may be in an inconsistent state.
 * It is strongly recommended that the stream be promptly closed if an I/O
 * error occurs.
 *
 * @implNote
 * The number of bytes allocated to read data from this stream and return
 * the result is bounded by {@code 2*(long)len}, inclusive.
 *
 * @param len the maximum number of bytes to read
 * @return a byte array containing the bytes read from this input stream
 * @throws IllegalArgumentException if {@code length} is negative
 * @throws IOException if an I/O error occurs
 * @throws OutOfMemoryError if an array of the required size cannot be
 * allocated.
 *
 * @since 11
 */
 public byte[] readNBytes(int len) throws IOException {
 if (len < 0) {
 throw new IllegalArgumentException("len < 0");
 }

 List<byte[]> bufs = null;
 byte[] result = null;
 int total = 0;
 int remaining = len;
 int n;
 do {
 byte[] buf = new byte[Math.min(remaining, DEFAULT_BUFFER_SIZE)];
 int nread = 0;

 // read to EOF which may read more or less than buffer size
 while ((n = read(buf, nread,
 Math.min(buf.length - nread, remaining))) > 0) {
 nread += n;
 remaining -= n;
 }

 if (nread > 0) {
 if (MAX_BUFFER_SIZE - total < nread) {
 throw new OutOfMemoryError("Required array size too large");
 }
 total += nread;
 if (result == null) {
 result = buf;
 } else {
 if (bufs == null) {
 bufs = new ArrayList<>();
 bufs.add(result);
 }
 bufs.add(buf);
 }
 }
 // if the last call to read returned -1 or the number of bytes
 // requested have been read then break
 } while (n >= 0 && remaining > 0);

 if (bufs == null) {
 if (result == null) {
 return new byte[0];
 }
 return result.length == total ?
 result : Arrays.copyOf(result, total);
 }

 result = new byte[total];
 int offset = 0;
 remaining = total;
 for (byte[] b : bufs) {
 int count = Math.min(b.length, remaining);
 System.arraycopy(b, 0, result, offset, count);
 offset += count;
 remaining -= count;
 }

 return result;
 }

 /**
 * Reads the requested number of bytes from the input stream into the given
 * byte array. This method blocks until {@code len} bytes of input data have
 * been read, end of stream is detected, or an exception is thrown. The
 * number of bytes actually read, possibly zero, is returned. This method
 * does not close the input stream.
 *
 * <p> In the case where end of stream is reached before {@code len} bytes
 * have been read, then the actual number of bytes read will be returned.
 * When this stream reaches end of stream, further invocations of this
 * method will return zero.
 *
 * <p> If {@code len} is zero, then no bytes are read and {@code 0} is
 * returned; otherwise, there is an attempt to read up to {@code len} bytes.
 *
 * <p> The first byte read is stored into element {@code b[off]}, the next
 * one in to {@code b[off+1]}, and so on. The number of bytes read is, at
 * most, equal to {@code len}. Let <i>k</i> be the number of bytes actually
 * read; these bytes will be stored in elements {@code b[off]} through
 * {@code b[off+}<i>k</i>{@code -1]}, leaving elements {@code b[off+}<i>k</i>
 * {@code ]} through {@code b[off+len-1]} unaffected.
 *
 * <p> The behavior for the case where the input stream is <i>asynchronously
 * closed</i>, or the thread interrupted during the read, is highly input
 * stream specific, and therefore not specified.
 *
 * <p> If an I/O error occurs reading from the input stream, then it may do
 * so after some, but not all, bytes of {@code b} have been updated with
 * data from the input stream. Consequently the input stream and {@code b}
 * may be in an inconsistent state. It is strongly recommended that the
 * stream be promptly closed if an I/O error occurs.
 *
 * @param b the byte array into which the data is read
 * @param off the start offset in {@code b} at which the data is written
 * @param len the maximum number of bytes to read
 * @return the actual number of bytes read into the buffer
 * @throws IOException if an I/O error occurs
 * @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}
 *
 * @since 9
 */
 public int readNBytes(byte[] b, int off, int len) throws IOException {
 Objects.checkFromIndexSize(off, len, b.length);

 int n = 0;
 while (n < len) {
 int count = read(b, off + n, len - n);
 if (count < 0)
 break;
 n += count;
 }
 return n;
 }

 /**
 * Skips over and discards <code>n</code> bytes of data from this input
 * stream. The <code>skip</code> method may, for a variety of reasons, end
 * up skipping over some smaller number of bytes, possibly <code>0</code>.
 * This may result from any of a number of conditions; reaching end of file
 * before <code>n</code> bytes have been skipped is only one possibility.
 * The actual number of bytes skipped is returned. If {@code n} is
 * negative, the {@code skip} method for class {@code InputStream} always
 * returns 0, and no bytes are skipped. Subclasses may handle the negative
 * value differently.
 *
 * <p> The <code>skip</code> method implementation of this class creates a
 * byte array and then repeatedly reads into it until <code>n</code> 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 which might be zero.
 * @throws IOException if an I/O error occurs.
 * @see java.io.InputStream#skipNBytes(long)
 */
 public long skip(long n) throws IOException {
 long remaining = n;
 int nr;

 if (n <= 0) {
 return 0;
 }

 int size = (int)Math.min(MAX_SKIP_BUFFER_SIZE, remaining);
 byte[] skipBuffer = new byte[size];
 while (remaining > 0) {
 nr = read(skipBuffer, 0, (int)Math.min(size, remaining));
 if (nr < 0) {
 break;
 }
 remaining -= nr;
 }

 return n - remaining;
 }

 /**
 * Skips over and discards exactly {@code n} bytes of data from this input
 * stream. If {@code n} is zero, then no bytes are skipped.
 * If {@code n} is negative, then no bytes are skipped.
 * Subclasses may handle the negative value differently.
 *
 * <p> This method blocks until the requested number of bytes have been
 * skipped, end of file is reached, or an exception is thrown.
 *
 * <p> If end of stream is reached before the stream is at the desired
 * position, then an {@code EOFException} is thrown.
 *
 * <p> If an I/O error occurs, then the input stream may be
 * in an inconsistent state. It is strongly recommended that the
 * stream be promptly closed if an I/O error occurs.
 *
 * @implNote
 * Subclasses are encouraged to provide a more efficient implementation
 * of this method.
 *
 * @implSpec
 * If {@code n} is zero or negative, then no bytes are skipped.
 * If {@code n} is positive, the default implementation of this method
 * invokes {@link #skip(long) skip()} with parameter {@code n}. If the
 * return value of {@code skip(n)} is non-negative and less than {@code n},
 * then {@link #read()} is invoked repeatedly until the stream is {@code n}
 * bytes beyond its position when this method was invoked or end of stream
 * is reached. If the return value of {@code skip(n)} is negative or
 * greater than {@code n}, then an {@code IOException} is thrown. Any
 * exception thrown by {@code skip()} or {@code read()} will be propagated.
 *
 * @param n the number of bytes to be skipped.
 * @throws EOFException if end of stream is encountered before the
 * stream can be positioned {@code n} bytes beyond its position
 * when this method was invoked.
 * @throws IOException if the stream cannot be positioned properly or
 * if an I/O error occurs.
 * @see java.io.InputStream#skip(long)
 */
 public void skipNBytes(long n) throws IOException {
 if (n > 0) {
 long ns = skip(n);
 if (ns >= 0 && ns < n) { // skipped too few bytes
 // adjust number to skip
 n -= ns;
 // read until requested number skipped or EOS reached
 while (n > 0 && read() != -1) {
 n--;
 }
 // if not enough skipped, then EOFE
 if (n != 0) {
 throw new EOFException();
 }
 } else if (ns != n) { // skipped negative or too many bytes
 throw new IOException("Unable to skip exactly");
 }
 }
 }

 /**
 * Returns an estimate of the number of bytes that can be read (or skipped
 * over) from this input stream without blocking, which may be 0, or 0 when
 * end of stream is detected. The read might be on 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.
 *
 * <p> Note that while some implementations of {@code InputStream} will
 * return the total number of bytes in the stream, many will not. It is
 * never correct to use the return value of this method to allocate
 * a buffer intended to hold all data in this stream.
 *
 * <p> A subclass's implementation of this method may choose to throw an
 * {@link IOException} if this input stream has been closed by invoking the
 * {@link #close()} method.
 *
 * <p> The {@code available} method of {@code InputStream} always returns
 * {@code 0}.
 *
 * <p> This method should be overridden by subclasses.
 *
 * @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.
 * @exception IOException if an I/O error occurs.
 */
 public int available() throws IOException {
 return 0;
 }

 /**
 * Closes this input stream and releases any system resources associated
 * with the stream.
 *
 * <p> The <code>close</code> method of <code>InputStream</code> does
 * nothing.
 *
 * @exception IOException if an I/O error occurs.
 */
 public void close() throws IOException {}

 /**
 * Marks the current position in this input stream. A subsequent call to
 * the <code>reset</code> method repositions this stream at the last marked
 * position so that subsequent reads re-read the same bytes.
 *
 * <p> The <code>readlimit</code> arguments tells this input stream to
 * allow that many bytes to be read before the mark position gets
 * invalidated.
 *
 * <p> The general contract of <code>mark</code> is that, if the method
 * <code>markSupported</code> returns <code>true</code>, the stream somehow
 * remembers all the bytes read after the call to <code>mark</code> and
 * stands ready to supply those same bytes again if and whenever the method
 * <code>reset</code> is called. However, the stream is not required to
 * remember any data at all if more than <code>readlimit</code> bytes are
 * read from the stream before <code>reset</code> is called.
 *
 * <p> Marking a closed stream should not have any effect on the stream.
 *
 * <p> The <code>mark</code> method of <code>InputStream</code> does
 * nothing.
 *
 * @param readlimit the maximum limit of bytes that can be read before
 * the mark position becomes invalid.
 * @see java.io.InputStream#reset()
 */
 public synchronized void mark(int readlimit) {}

 /**
 * Repositions this stream to the position at the time the
 * <code>mark</code> method was last called on this input stream.
 *
 * <p> The general contract of <code>reset</code> is:
 *
 * <ul>
 * <li> If the method <code>markSupported</code> returns
 * <code>true</code>, then:
 *
 * <ul><li> If the method <code>mark</code> has not been called since
 * the stream was created, or the number of bytes read from the stream
 * since <code>mark</code> was last called is larger than the argument
 * to <code>mark</code> at that last call, then an
 * <code>IOException</code> might be thrown.
 *
 * <li> If such an <code>IOException</code> is not thrown, then the
 * stream is reset to a state such that all the bytes read since the
 * most recent call to <code>mark</code> (or since the start of the
 * file, if <code>mark</code> has not been called) will be resupplied
 * to subsequent callers of the <code>read</code> method, followed by
 * any bytes that otherwise would have been the next input data as of
 * the time of the call to <code>reset</code>. </ul>
 *
 * <li> If the method <code>markSupported</code> returns
 * <code>false</code>, then:
 *
 * <ul><li> The call to <code>reset</code> may throw an
 * <code>IOException</code>.
 *
 * <li> If an <code>IOException</code> is not thrown, then the stream
 * is reset to a fixed state that depends on the particular type of the
 * input stream and how it was created. The bytes that will be supplied
 * to subsequent callers of the <code>read</code> method depend on the
 * particular type of the input stream. </ul></ul>
 *
 * <p>The method <code>reset</code> for class <code>InputStream</code>
 * does nothing except throw an <code>IOException</code>.
 *
 * @exception IOException if this stream has not been marked or if the
 * mark has been invalidated.
 * @see java.io.InputStream#mark(int)
 * @see java.io.IOException
 */
 public synchronized void reset() throws IOException {
 throw new IOException("mark/reset not supported");
 }

 /**
 * Tests if this input stream supports the <code>mark</code> and
 * <code>reset</code> methods. Whether or not <code>mark</code> and
 * <code>reset</code> are supported is an invariant property of a
 * particular input stream instance. The <code>markSupported</code> method
 * of <code>InputStream</code> returns <code>false</code>.
 *
 * @return <code>true</code> if this stream instance supports the mark
 * and reset methods; <code>false</code> otherwise.
 * @see java.io.InputStream#mark(int)
 * @see java.io.InputStream#reset()
 */
 public boolean markSupported() {
 return false;
 }

 /**
 * Reads all bytes from this input stream and writes the bytes to the
 * given output stream in the order that they are read. On return, this
 * input stream will be at end of stream. This method does not close either
 * stream.
 * <p>
 * This method may block indefinitely reading from the input stream, or
 * writing to the output stream. The behavior for the case where the input
 * and/or output stream is <i>asynchronously closed</i>, or the thread
 * interrupted during the transfer, is highly input and output stream
 * specific, and therefore not specified.
 * <p>
 * If an I/O error occurs reading from the input stream or writing to the
 * output stream, then it may do so after some bytes have been read or
 * written. Consequently the input stream may not be at end of stream and
 * one, or both, streams may be in an inconsistent state. It is strongly
 * recommended that both streams be promptly closed if an I/O error occurs.
 *
 * @param out the output stream, non-null
 * @return the number of bytes transferred
 * @throws IOException if an I/O error occurs when reading or writing
 * @throws NullPointerException if {@code out} is {@code null}
 *
 * @since 9
 */
 public long transferTo(OutputStream out) throws IOException {
 Objects.requireNonNull(out, "out");
 long transferred = 0;
 byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
 int read;
 while ((read = this.read(buffer, 0, DEFAULT_BUFFER_SIZE)) >= 0) {
 out.write(buffer, 0, read);
 transferred += read;
 }
 return transferred;
 }
}