/*

 * Copyright (c) 1994, 2006, 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   JDK1.0

 */

public

class DataInputStream extends FilterInputStream implements DataInput {

    /**

     * 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</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 <code>b</code> is null, a <code>NullPointerException</code> is

     * thrown. 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 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[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 <code>k</code>

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

     * elements <code>b[0]</code> through <code>b[k-1]</code>, leaving

     * elements <code>b[k]</code> through <code>b[b.length-1]</code>

     * unaffected.

     *

     * <p>The <code>read(b)</code> 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</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, 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</code> bytes of data from the contained

     * 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,

     * 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</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.

     *

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

     * @param off the start offset in the destination array <code>b</code>

     * @param      len   the maximum number of bytes 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  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>

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

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

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

     *             reading all the bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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 of the data.

     * @param      len   the number of bytes to read.

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

     *               reading all the bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <p>

     * Bytes for this operation are read from the contained

     * input stream.

     *

     * @return     the <code>boolean</code> value read.

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

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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</code>.

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

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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.

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

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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.

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

     *               reading two bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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.

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

     *             reading two bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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</code>.

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

     *               reading two bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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</code>.

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

     *               reading four bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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</code>.

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

     *               reading eight bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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</code>.

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

     *               reading four bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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</code>.

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

     *               reading eight bytes.

     * @exception  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</code>

     * method of <code>DataInput</code>.

     * <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()</code> method.  Programs that use the

     * <code>DataInputStream</code> class to read lines can be converted to use

     * the <code>BufferedReader</code> 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.

     * @exception  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];

        }

        int room = buf.length;

        int offset = 0;

        int c;

loop:   while (true) {

            switch (c = in.read()) {

              case -1:

              case '\n':

                break loop;

              case '\r':

                int c2 = in.read();

                if ((c2 != '\n') && (c2 != -1)) {

                    if (!(in instanceof PushbackInputStream)) {

                        this.in = new PushbackInputStream(in);

                    }

                    ((PushbackInputStream)in).unread(c2);

                }

                break loop;

              default:

                if (--room < 0) {

                    buf = new char[offset + 128];

                    room = buf.length - offset - 1;

                    arraycopy(lineBuffer, 0, buf, 0, offset);

                    lineBuffer = buf;

                }

                buf[offset++] = (char) c;

                break;

            }

        }

        if ((c == -1) && (offset == 0)) {

            return null;

        }

        return String.copyValueOf(buf, 0, offset);

    }

    /**

     * See the general contract of the <code>readUTF</code>

     * method of <code>DataInput</code>.

     * <p>

     * Bytes

     * for this operation are read from the contained

     * input stream.

     *

     * @return     a Unicode string.

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

     *               reading all the bytes.

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

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @exception  UTFDataFormatException if the bytes do not represent a valid

     *             modified UTF-8 encoding of a string.

     * @see        java.io.DataInputStream#readUTF(java.io.DataInput)

     */

    public final String readUTF() throws IOException {

        return readUTF(this);

    }

    /**

     * Reads from the

     * stream <code>in</code> a representation

     * of a Unicode  character string encoded in

     * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> format;

     * this string of characters is then returned as a <code>String</code>.

     * The details of the modified UTF-8 representation

     * are  exactly the same as for the <code>readUTF</code>

     * method of <code>DataInput</code>.

     *

     * @param      in   a data input stream.

     * @return     a Unicode string.

     * @exception  EOFException            if the input stream reaches the end

     *               before all the bytes.

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

     *             input stream does not support reading after close, or

     *             another I/O error occurs.

     * @exception  UTFDataFormatException  if the bytes do not represent a

     *               valid modified UTF-8 encoding of a Unicode string.

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

     */

    public final static String readUTF(DataInput in) throws IOException {

        int utflen = in.readUnsignedShort();

        byte[] bytearr = null;

        char[] chararr = null;

        if (in instanceof DataInputStream) {

            DataInputStream dis = (DataInputStream)in;

            if (dis.bytearr.length < utflen){

                dis.bytearr = new byte[utflen*2];

                dis.chararr = new char[utflen*2];

            }

            chararr = dis.chararr;

            bytearr = dis.bytearr;

        } else {

            bytearr = new byte[utflen];

            chararr = new char[utflen];

        }

        int c, char2, char3;

        int count = 0;

        int chararr_count=0;

        in.readFully(bytearr, 0, utflen);

        while (count < utflen) {

            c = (int) bytearr[count] & 0xff;

            if (c > 127) break;

            count++;

            chararr[chararr_count++]=(char)c;

        }

        while (count < utflen) {

            c = (int) bytearr[count] & 0xff;

            switch (c >> 4) {

                case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:

                    /* 0xxxxxxx*/

                    count++;

                    chararr[chararr_count++]=(char)c;

                    break;

                case 12: case 13:

                    /* 110x xxxx   10xx xxxx*/

                    count += 2;

                    if (count > utflen)

                        throw new UTFDataFormatException(

                            "malformed input: partial character at end");

                    char2 = (int) bytearr[count-1];

                    if ((char2 & 0xC0) != 0x80)

                        throw new UTFDataFormatException(

                            "malformed input around byte " + count);

                    chararr[chararr_count++]=(char)(((c & 0x1F) << 6) |

                                                    (char2 & 0x3F));

                    break;

                case 14:

                    /* 1110 xxxx  10xx xxxx  10xx xxxx */

                    count += 3;

                    if (count > utflen)

                        throw new UTFDataFormatException(

                            "malformed input: partial character at end");

                    char2 = (int) bytearr[count-2];

                    char3 = (int) bytearr[count-1];

                    if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80))

                        throw new UTFDataFormatException(

                            "malformed input around byte " + (count-1));

                    chararr[chararr_count++]=(char)(((c     & 0x0F) << 12) |

                                                    ((char2 & 0x3F) << 6)  |

                                                    ((char3 & 0x3F) << 0));

                    break;

                default:

                    /* 10xx xxxx,  1111 xxxx */

                    throw new UTFDataFormatException(

                        "malformed input around byte " + count);

            }

        }

        // The number of chars produced may be less than utflen

        return new String(chararr, 0, chararr_count);

    }

    static void arraycopy(char[] value, int srcBegin, char[] dst, int dstBegin, int count) {

        while (count-- > 0) {

            dst[dstBegin++] = value[srcBegin++];

        }

    }

}