content: /*
   * 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;
  
  import java.nio.ByteOrder;
  import libcore.io.Memory;
  
  /**
   * 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     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        FilterInputStream#in
       * @see        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        FilterInputStream#in
       * @see        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        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        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        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        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         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        FilterInputStream#in
       */
      public final short readShort() throws IOException {
          // b/30268192
          // Android-changed: Use read(byte[], int, int) instead of read().
          readFully(readBuffer, 0, 2);
          return Memory.peekShort(readBuffer, 0, ByteOrder.BIG_ENDIAN);
      }
  
      /**
       * 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        FilterInputStream#in
       */
      public final int readUnsignedShort() throws IOException {
          // b/30268192
          // Android-changed: Use read(byte[], int, int) instead of read().
          readFully(readBuffer, 0, 2);
          return Memory.peekShort(readBuffer, 0, ByteOrder.BIG_ENDIAN) & 0xffff;
      }
  
      /**
       * 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        FilterInputStream#in
       */
      public final char readChar() throws IOException {
          // b/30268192
          // Android-changed: Use read(byte[], int, int) instead of read().
          readFully(readBuffer, 0, 2);
          return (char)Memory.peekShort(readBuffer, 0, ByteOrder.BIG_ENDIAN);
      }
  
      /**
       * 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        FilterInputStream#in
       */
      public final int readInt() throws IOException {
          // b/30268192
          // Android-changed: Use read(byte[], int, int) instead of read().
          readFully(readBuffer, 0, 4);
          return Memory.peekInt(readBuffer, 0, ByteOrder.BIG_ENDIAN);
      }
  
      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        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        DataInputStream#readInt()
       * @see        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        DataInputStream#readLong()
       * @see        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        BufferedReader#readLine()
       * @see        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        DataInputStream#readUTF(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        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);
      }
  }
  