/*

  * 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;

                     System.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);

     }

 }