/*
 * Copyright (c) 1994, 2016, 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
 */
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}
 * 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.
 * @exception NullPointerException if {@code b} is {@code null}.
 * @exception IndexOutOfBoundsException if {@code off} is negative,
 * {@code len} is negative, or {@code len} is greater than
 * {@code b.length - off}.
 * @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&nbsp;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 =&nbsp;new&nbsp;DataInputStream(in);
 * </pre></blockquote>
 * with:
 * <blockquote><pre>
 * BufferedReader d
 * =&nbsp;new&nbsp;BufferedReader(new&nbsp;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 static final 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);
 }
}