/*

 * Copyright (c) 1994, 2019, 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;

/**

 * A data input stream lets an application read primitive Java data

 * types from an underlying input stream in a machine-independent

 * way. An application uses a data output stream to write data that

 * can later be read by a data input stream.

 * <p>

 * DataInputStream is not necessarily safe for multithreaded access.

 * Thread safety is optional and is the responsibility of users of

 * methods in this class.

 *

 * @author  Arthur van Hoff

 * @see     java.io.DataOutputStream

 * @since   1.0

 */

    /**

     * Creates a DataInputStream that uses the specified

     * underlying InputStream.

     *

     * @param  in   the specified input stream

     */

    public DataInputStream(InputStream in) {

        super(in);

    }

    /**

     * working arrays initialized on demand by readUTF

     */

    private byte bytearr[] = new byte[80];

    private char chararr[] = new char[80];

    /**

     * Reads some number of bytes from the contained input stream and

     * stores them into the buffer array {@code b}. 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 {@code b} is null, a {@code NullPointerException} is

     * thrown. If the length of {@code b} is zero, then no bytes are

     * read and {@code 0} 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} is returned;

     * otherwise, at least one byte is read and stored into {@code b}.

     *

     * <p>The first byte read is stored into element {@code b[0]}, the

     * next one into {@code b[1]}, and so on. The number of bytes read

     * is, at most, equal to the length of {@code b}. Let {@code k}

     * be the number of bytes actually read; these bytes will be stored in

     * elements {@code b[0]} through {@code b[k-1]}, leaving

     * elements {@code b[k]} through {@code b[b.length-1]}

     * unaffected.

     *

     * <p>The {@code read(b)} method has the same effect as:

     * <blockquote><pre>

     * read(b, 0, b.length)

     * </pre></blockquote>

     *

     * @param      b   the buffer into which the data is 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     IOException if the first byte cannot be read for any reason

     *             other than end of file, the stream has been closed and the underlying

     *             input stream does not support reading after close, or another I/O

     *             error occurs.

     * @see        java.io.FilterInputStream#in

     * @see        java.io.InputStream#read(byte[], int, int)

     */

    public final int read(byte b[]) throws IOException {

        return in.read(b, 0, b.length);

    }

    /**

     * Reads up to {@code len} bytes of data from the contained

     * input stream into an array of bytes.  An attempt is made to read

     * as many as {@code len} bytes, but a smaller number may be read,

     * possibly zero. 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} is zero, then no bytes are read and

     * {@code 0} 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} is returned; otherwise, at least one

     * byte is read and stored into {@code b}.

     *

     * <p> The first byte read is stored into element {@code b[off]}, the

     * next one into {@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> In every case, elements {@code b[0]} through

     * {@code b[off]} and elements {@code b[off+len]} through

     * {@code b[b.length-1]} are unaffected.

     *

     * @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}

     * @throws     IOException if the first byte cannot be read for any reason

     *             other than end of file, the stream has been closed and the underlying

     *             input stream does not support reading after close, or another I/O

     *             error occurs.

     * @see        java.io.FilterInputStream#in

     * @see        java.io.InputStream#read(byte[], int, int)

     */

    public final int read(byte b[], int off, int len) throws IOException {

        return in.read(b, off, len);

    }

    /**

     * See the general contract of the {@code readFully}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @param   b   the buffer into which the data is read.

     * @throws  NullPointerException if {@code b} is {@code null}.

     * @throws  EOFException  if this input stream reaches the end before

     *          reading all the bytes.

     * @throws  IOException   the stream has been closed and the contained

     *          input stream does not support reading after close, or

     *          another I/O error occurs.

     * @see     java.io.FilterInputStream#in

     */

    public final void readFully(byte b[]) throws IOException {

        readFully(b, 0, b.length);

    }

    /**

     * See the general contract of the {@code readFully}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @param      b     the buffer into which the data is read.

     * @param      off   the start offset in the data array {@code b}.

     * @param      len   the number of bytes to read.

     * @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}.

     * @throws     EOFException  if this input stream reaches the end before

     *             reading all the bytes.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.FilterInputStream#in

     */

    public final void readFully(byte b[], int off, int len) throws IOException {

        if (len < 0)

            throw new IndexOutOfBoundsException();

        int n = 0;

        while (n < len) {

            int count = in.read(b, off + n, len - n);

            if (count < 0)

                throw new EOFException();

            n += count;

        }

    }

    /**

     * See the general contract of the {@code skipBytes}

     * method of {@code DataInput}.

     * <p>

     * Bytes for this operation are read from the contained

     * input stream.

     *

     * @param      n   the number of bytes to be skipped.

     * @return     the actual number of bytes skipped.

     * @throws     IOException  if the contained input stream does not support

     *             seek, or the stream has been closed and

     *             the contained input stream does not support

     *             reading after close, or another I/O error occurs.

     */

    public final int skipBytes(int n) throws IOException {

        int total = 0;

        int cur = 0;

        while ((total<n) && ((cur = (int) in.skip(n-total)) > 0)) {

            total += cur;

        }

        return total;

    }

    /**

     * See the general contract of the {@code readBoolean}

     * method of {@code DataInput}.

     * <p>

     * Bytes for this operation are read from the contained

     * input stream.

     *

     * @return     the {@code boolean} value read.

     * @throws     EOFException  if this input stream has reached the end.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.FilterInputStream#in

     */

    public final boolean readBoolean() throws IOException {

        int ch = in.read();

        if (ch < 0)

            throw new EOFException();

        return (ch != 0);

    }

    /**

     * See the general contract of the {@code readByte}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next byte of this input stream as a signed 8-bit

     *             {@code byte}.

     * @throws     EOFException  if this input stream has reached the end.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.FilterInputStream#in

     */

    public final byte readByte() throws IOException {

        int ch = in.read();

        if (ch < 0)

            throw new EOFException();

        return (byte)(ch);

    }

    /**

     * See the general contract of the {@code readUnsignedByte}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next byte of this input stream, interpreted as an

     *             unsigned 8-bit number.

     * @throws     EOFException  if this input stream has reached the end.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see         java.io.FilterInputStream#in

     */

    public final int readUnsignedByte() throws IOException {

        int ch = in.read();

        if (ch < 0)

            throw new EOFException();

        return ch;

    }

    /**

     * See the general contract of the {@code readShort}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next two bytes of this input stream, interpreted as a

     *             signed 16-bit number.

     * @throws     EOFException  if this input stream reaches the end before

     *               reading two bytes.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.FilterInputStream#in

     */

    public final short readShort() throws IOException {

        int ch1 = in.read();

        int ch2 = in.read();

        if ((ch1 | ch2) < 0)

            throw new EOFException();

        return (short)((ch1 << 8) + (ch2 << 0));

    }

    /**

     * See the general contract of the {@code readUnsignedShort}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next two bytes of this input stream, interpreted as an

     *             unsigned 16-bit integer.

     * @throws     EOFException  if this input stream reaches the end before

     *             reading two bytes.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.FilterInputStream#in

     */

    public final int readUnsignedShort() throws IOException {

        int ch1 = in.read();

        int ch2 = in.read();

        if ((ch1 | ch2) < 0)

            throw new EOFException();

        return (ch1 << 8) + (ch2 << 0);

    }

    /**

     * See the general contract of the {@code readChar}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next two bytes of this input stream, interpreted as a

     *             {@code char}.

     * @throws     EOFException  if this input stream reaches the end before

     *               reading two bytes.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.FilterInputStream#in

     */

    public final char readChar() throws IOException {

        int ch1 = in.read();

        int ch2 = in.read();

        if ((ch1 | ch2) < 0)

            throw new EOFException();

        return (char)((ch1 << 8) + (ch2 << 0));

    }

    /**

     * See the general contract of the {@code readInt}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next four bytes of this input stream, interpreted as an

     *             {@code int}.

     * @throws     EOFException  if this input stream reaches the end before

     *               reading four bytes.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.FilterInputStream#in

     */

    public final int readInt() throws IOException {

        int ch1 = in.read();

        int ch2 = in.read();

        int ch3 = in.read();

        int ch4 = in.read();

        if ((ch1 | ch2 | ch3 | ch4) < 0)

            throw new EOFException();

        return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));

    }

    private byte readBuffer[] = new byte[8];

    /**

     * See the general contract of the {@code readLong}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next eight bytes of this input stream, interpreted as a

     *             {@code long}.

     * @throws     EOFException  if this input stream reaches the end before

     *               reading eight bytes.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.FilterInputStream#in

     */

    public final long readLong() throws IOException {

        readFully(readBuffer, 0, 8);

        return (((long)readBuffer[0] << 56) +

                ((long)(readBuffer[1] & 255) << 48) +

                ((long)(readBuffer[2] & 255) << 40) +

                ((long)(readBuffer[3] & 255) << 32) +

                ((long)(readBuffer[4] & 255) << 24) +

                ((readBuffer[5] & 255) << 16) +

                ((readBuffer[6] & 255) <<  8) +

                ((readBuffer[7] & 255) <<  0));

    }

    /**

     * See the general contract of the {@code readFloat}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next four bytes of this input stream, interpreted as a

     *             {@code float}.

     * @throws     EOFException  if this input stream reaches the end before

     *               reading four bytes.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.DataInputStream#readInt()

     * @see        java.lang.Float#intBitsToFloat(int)

     */

    public final float readFloat() throws IOException {

        return Float.intBitsToFloat(readInt());

    }

    /**

     * See the general contract of the {@code readDouble}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     the next eight bytes of this input stream, interpreted as a

     *             {@code double}.

     * @throws     EOFException  if this input stream reaches the end before

     *               reading eight bytes.

     * @throws     IOException   the stream has been closed and the contained

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @see        java.io.DataInputStream#readLong()

     * @see        java.lang.Double#longBitsToDouble(long)

     */

    public final double readDouble() throws IOException {

        return Double.longBitsToDouble(readLong());

    }

    private char lineBuffer[];

    /**

     * See the general contract of the {@code readLine}

     * method of {@code DataInput}.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @deprecated This method does not properly convert bytes to characters.

     * As of JDK 1.1, the preferred way to read lines of text is via the

     * {@code BufferedReader.readLine()} method.  Programs that use the

     * {@code DataInputStream} class to read lines can be converted to use

     * the {@code BufferedReader} class by replacing code of the form:

     * <blockquote><pre>

     *     DataInputStream d = new DataInputStream(in);

     * </pre></blockquote>

     * with:

     * <blockquote><pre>

     *     BufferedReader d

     *          = new BufferedReader(new InputStreamReader(in));

     * </pre></blockquote>

     *

     * @return     the next line of text from this input stream.

     * @throws     IOException  if an I/O error occurs.

     * @see        java.io.BufferedReader#readLine()

     * @see        java.io.FilterInputStream#in

     */

    @Deprecated

    public final String readLine() throws IOException {

        char buf[] = lineBuffer;

        if (buf == null) {

            buf = lineBuffer = new char[128];

        }