001    /* DataInputStream.java -- FilteredInputStream that implements DataInput
002       Copyright (C) 1998, 1999, 2000, 2001, 2003, 2005  Free Software Foundation
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010     
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037     
038    package java.io;
039    
040    /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
041     * "The Java Language Specification", ISBN 0-201-63451-1
042     * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
043     * Status:  Believed complete and correct.
044     */
045     
046    /**
047     * This subclass of <code>FilteredInputStream</code> implements the
048     * <code>DataInput</code> interface that provides method for reading primitive
049     * Java data types from a stream.
050     *
051     * @see DataInput
052     *
053     * @author Warren Levy (warrenl@cygnus.com)
054     * @author Aaron M. Renn (arenn@urbanophile.com)
055     * @date October 20, 1998.  
056     */
057    public class DataInputStream extends FilterInputStream implements DataInput
058    {
059      // Byte buffer, used to make primitive read calls more efficient.
060      byte[] buf = new byte [8];
061      
062      /**
063       * This constructor initializes a new <code>DataInputStream</code>
064       * to read from the specified subordinate stream.
065       *
066       * @param in The subordinate <code>InputStream</code> to read from
067       */
068      public DataInputStream (InputStream in)
069      {
070        super (in);
071      }
072    
073      /**
074       * This method reads bytes from the underlying stream into the specified
075       * byte array buffer.  It will attempt to fill the buffer completely, but
076       * may return a short count if there is insufficient data remaining to be
077       * read to fill the buffer.
078       *
079       * @param b The buffer into which bytes will be read.
080       * 
081       * @return The actual number of bytes read, or -1 if end of stream reached 
082       * before reading any bytes.
083       *
084       * @exception IOException If an error occurs.
085       */
086      public final int read (byte[] b) throws IOException
087      {
088        return in.read (b, 0, b.length);
089      }
090    
091      /**
092       * This method reads bytes from the underlying stream into the specified
093       * byte array buffer.  It will attempt to read <code>len</code> bytes and
094       * will start storing them at position <code>off</code> into the buffer.
095       * This method can return a short count if there is insufficient data
096       * remaining to be read to complete the desired read length.
097       *
098       * @param b The buffer into which bytes will be read.
099       * @param off The offset into the buffer to start storing bytes.
100       * @param len The requested number of bytes to read.
101       *
102       * @return The actual number of bytes read, or -1 if end of stream reached
103       * before reading any bytes.
104       *
105       * @exception IOException If an error occurs.
106       */
107      public final int read (byte[] b, int off, int len) throws IOException
108      {
109        return in.read (b, off, len);
110      }
111    
112      /**
113       * This method reads a Java boolean value from an input stream.  It does
114       * so by reading a single byte of data.  If that byte is zero, then the
115       * value returned is <code>false</code>.  If the byte is non-zero, then
116       * the value returned is <code>true</code>.
117       * <p>
118       * This method can read a <code>boolean</code> written by an object
119       * implementing the <code>writeBoolean()</code> method in the
120       * <code>DataOutput</code> interface. 
121       *
122       * @return The <code>boolean</code> value read
123       *
124       * @exception EOFException If end of file is reached before reading
125       * the boolean
126       * @exception IOException If any other error occurs
127       *
128       * @see DataOutput#writeBoolean
129       */
130      public final boolean readBoolean () throws IOException
131      {
132        return convertToBoolean (in.read ());
133      }
134    
135      /**
136       * This method reads a Java byte value from an input stream.  The value
137       * is in the range of -128 to 127.
138       * <p>
139       * This method can read a <code>byte</code> written by an object
140       * implementing the <code>writeByte()</code> method in the
141       * <code>DataOutput</code> interface.
142       *
143       * @return The <code>byte</code> value read
144       *
145       * @exception EOFException If end of file is reached before reading the byte
146       * @exception IOException If any other error occurs
147       *
148       * @see DataOutput#writeByte
149       */
150      public final byte readByte () throws IOException
151      {
152        return convertToByte (in.read ());
153      }
154    
155      /**
156       * This method reads a Java <code>char</code> value from an input stream.  
157       * It operates by reading two bytes from the stream and converting them to 
158       * a single 16-bit Java <code>char</code>.  The two bytes are stored most
159       * significant byte first (i.e., "big endian") regardless of the native
160       * host byte ordering. 
161       * <p>
162       * As an example, if <code>byte1</code> and <code>byte2</code>
163       * represent the first and second byte read from the stream
164       * respectively, they will be transformed to a <code>char</code> in
165       * the following manner: 
166       * <p>
167       * <code>(char)(((byte1 &amp; 0xFF) &lt;&lt; 8) | (byte2 &amp; 0xFF)</code>
168       * <p>
169       * This method can read a <code>char</code> written by an object
170       * implementing the <code>writeChar()</code> method in the
171       * <code>DataOutput</code> interface. 
172       *
173       * @return The <code>char</code> value read 
174       *
175       * @exception EOFException If end of file is reached before reading the char
176       * @exception IOException If any other error occurs
177       *
178       * @see DataOutput#writeChar
179       */
180      public final char readChar () throws IOException
181      {
182        readFully (buf, 0, 2);
183        return convertToChar (buf);
184      }
185    
186      /**
187       * This method reads a Java double value from an input stream.  It operates
188       * by first reading a <code>long</code> value from the stream by calling the
189       * <code>readLong()</code> method in this interface, then converts
190       * that <code>long</code> to a <code>double</code> using the
191       * <code>longBitsToDouble</code> method in the class
192       * <code>java.lang.Double</code> 
193       * <p>
194       * This method can read a <code>double</code> written by an object
195       * implementing the <code>writeDouble()</code> method in the
196       * <code>DataOutput</code> interface.
197       *
198       * @return The <code>double</code> value read
199       *
200       * @exception EOFException If end of file is reached before reading
201       * the double
202       * @exception IOException If any other error occurs
203       *
204       * @see DataOutput#writeDouble
205       * @see java.lang.Double#longBitsToDouble
206       */
207      public final double readDouble () throws IOException
208      {
209        return Double.longBitsToDouble (readLong ());
210      }
211    
212      /**
213       * This method reads a Java float value from an input stream.  It
214       * operates by first reading an <code>int</code> value from the
215       * stream by calling the <code>readInt()</code> method in this
216       * interface, then converts that <code>int</code> to a
217       * <code>float</code> using the <code>intBitsToFloat</code> method
218       * in the class <code>java.lang.Float</code>
219       * <p>
220       * This method can read a <code>float</code> written by an object
221       * implementing the <code>writeFloat()</code> method in the
222       * <code>DataOutput</code> interface.
223       *
224       * @return The <code>float</code> value read
225       *
226       * @exception EOFException If end of file is reached before reading the float
227       * @exception IOException If any other error occurs
228       *
229       * @see DataOutput#writeFloat 
230       * @see java.lang.Float#intBitsToFloat
231       */
232      public final float readFloat () throws IOException
233      {
234        return Float.intBitsToFloat (readInt ());
235      }
236    
237      /**
238       * This method reads raw bytes into the passed array until the array is
239       * full.  Note that this method blocks until the data is available and
240       * throws an exception if there is not enough data left in the stream to
241       * fill the buffer.  Note also that zero length buffers are permitted.
242       * In this case, the method will return immediately without reading any
243       * bytes from the stream.
244       *
245       * @param b The buffer into which to read the data
246       *
247       * @exception EOFException If end of file is reached before filling the
248       * buffer
249       * @exception IOException If any other error occurs
250       */
251      public final void readFully (byte[] b) throws IOException
252      {
253        readFully (b, 0, b.length);
254      }
255    
256      /**
257       * This method reads raw bytes into the passed array <code>buf</code>
258       * starting
259       * <code>offset</code> bytes into the buffer.  The number of bytes read
260       * will be
261       * exactly <code>len</code>.  Note that this method blocks until the data is
262       * available and throws an exception if there is not enough data left in
263       * the stream to read <code>len</code> bytes.  Note also that zero length
264       * buffers are permitted.  In this case, the method will return immediately
265       * without reading any bytes from the stream.
266       *
267       * @param buf The buffer into which to read the data
268       * @param offset The offset into the buffer to start storing data
269       * @param len The number of bytes to read into the buffer
270       *
271       * @exception EOFException If end of file is reached before filling the
272       * buffer
273       * @exception IOException If any other error occurs
274       */
275      public final void readFully (byte[] buf, int offset, int len) throws IOException
276      {
277        if (len < 0)
278          throw new IndexOutOfBoundsException("Negative length: " + len);
279        
280        while (len > 0)
281          {
282            // in.read will block until some data is available.
283            int numread = in.read (buf, offset, len);
284            if (numread < 0)
285              throw new EOFException ();
286            len -= numread;
287            offset += numread;
288          }
289      }
290    
291      /**
292       * This method reads a Java <code>int</code> value from an input stream
293       * It operates by reading four bytes from the stream and converting them to
294       * a single Java <code>int</code>.  The bytes are stored most
295       * significant byte first (i.e., "big endian") regardless of the native
296       * host byte ordering.
297       * <p>
298       * As an example, if <code>byte1</code> through <code>byte4</code> represent
299       * the first four bytes read from the stream, they will be
300       * transformed to an <code>int</code> in the following manner:
301       * <p>
302       * <code>(int)(((byte1 &amp; 0xFF) &lt;&lt; 24) + ((byte2 &amp; 0xFF) &lt;&lt; 16) +
303       * ((byte3 &amp; 0xFF)&lt;&lt; 8) + (byte4 &amp; 0xFF)))</code>
304       * <p>
305       * The value returned is in the range of -2147483648 to 2147483647.
306       * <p>
307       * This method can read an <code>int</code> written by an object
308       * implementing the <code>writeInt()</code> method in the
309       * <code>DataOutput</code> interface.
310       *
311       * @return The <code>int</code> value read
312       *
313       * @exception EOFException If end of file is reached before reading the int
314       * @exception IOException If any other error occurs
315       *
316       * @see DataOutput#writeInt
317       */
318      public final int readInt () throws IOException
319      {
320        readFully (buf, 0, 4);
321        return convertToInt (buf);
322      }
323    
324      /**
325       * This method reads the next line of text data from an input
326       * stream.  It operates by reading bytes and converting those bytes
327       * to <code>char</code> values by treating the byte read as the low
328       * eight bits of the <code>char</code> and using 0 as the high eight
329       * bits.  Because of this, it does not support the full 16-bit
330       * Unicode character set.
331       * <p>
332       * The reading of bytes ends when either the end of file or a line
333       * terminator is encountered.  The bytes read are then returned as a
334       * <code>String</code> A line terminator is a byte sequence
335       * consisting of either <code>\r</code>, <code>\n</code> or
336       * <code>\r\n</code>.  These termination charaters are discarded and
337       * are not returned as part of the string.
338       * <p>
339       * This method can read data that was written by an object implementing the
340       * <code>writeLine()</code> method in <code>DataOutput</code>.
341       *
342       * @return The line read as a <code>String</code>
343       *
344       * @exception IOException If an error occurs
345       *
346       * @see DataOutput
347       *
348       * @deprecated
349       */
350      public final String readLine() throws IOException
351      {
352        StringBuffer strb = new StringBuffer();
353    
354        while (true)
355          {
356            int c = in.read();
357            if (c == -1)    // got an EOF
358                return strb.length() > 0 ? strb.toString() : null;
359            if (c == '\r')
360              {
361                int next_c = in.read();
362                if (next_c != '\n' && next_c != -1)
363                  {
364                    if (!(in instanceof PushbackInputStream))
365                      in = new PushbackInputStream(in);
366                    ((PushbackInputStream) in).unread(next_c);
367                  }
368                break;
369              }
370            if (c == '\n')
371                break;
372            strb.append((char) c);
373          }
374    
375        return strb.length() > 0 ? strb.toString() : "";
376      }
377    
378      /**
379       * This method reads a Java <code>long</code> value from an input stream
380       * It operates by reading eight bytes from the stream and converting them to
381       * a single Java <code>long</code>.  The bytes are stored most
382       * significant byte first (i.e., "big endian") regardless of the native
383       * host byte ordering.
384       * <p>
385       * As an example, if <code>byte1</code> through <code>byte8</code> represent
386       * the first eight bytes read from the stream, they will be
387       * transformed to an <code>long</code> in the following manner:
388       * <p>
389       * <code>(long)(((byte1 &amp; 0xFF) &lt;&lt; 56) + ((byte2 &amp; 0xFF) &lt;&lt; 48) +
390       * ((byte3 &amp; 0xFF) &lt;&lt; 40) + ((byte4 &amp; 0xFF) &lt;&lt; 32) +
391       * ((byte5 &amp; 0xFF) &lt;&lt; 24) + ((byte6 &amp; 0xFF) &lt;&lt; 16) +
392       * ((byte7 &amp; 0xFF) &lt;&lt; 8) + (byte8 &amp; 0xFF)))
393       * </code>
394       * <p>
395       * The value returned is in the range of -9223372036854775808 to
396       * 9223372036854775807.
397       * <p>
398       * This method can read an <code>long</code> written by an object
399       * implementing the <code>writeLong()</code> method in the
400       * <code>DataOutput</code> interface.
401       *
402       * @return The <code>long</code> value read
403       *
404       * @exception EOFException If end of file is reached before reading the long
405       * @exception IOException If any other error occurs
406       *
407       * @see DataOutput#writeLong
408       */
409      public final long readLong () throws IOException
410      {
411        readFully (buf, 0, 8);
412        return convertToLong (buf);
413      }
414    
415      /**
416       * This method reads a signed 16-bit value into a Java in from the
417       * stream.  It operates by reading two bytes from the stream and
418       * converting them to a single 16-bit Java <code>short</code>.  The
419       * two bytes are stored most significant byte first (i.e., "big
420       * endian") regardless of the native host byte ordering.
421       * <p>
422       * As an example, if <code>byte1</code> and <code>byte2</code>
423       * represent the first and second byte read from the stream
424       * respectively, they will be transformed to a <code>short</code>. in
425       * the following manner:
426       * <p>
427       * <code>(short)(((byte1 &amp; 0xFF) &lt;&lt; 8) | (byte2 &amp; 0xFF))</code>
428       * <p>
429       * The value returned is in the range of -32768 to 32767.
430       * <p>
431       * This method can read a <code>short</code> written by an object
432       * implementing the <code>writeShort()</code> method in the
433       * <code>DataOutput</code> interface.
434       *
435       * @return The <code>short</code> value read
436       *
437       * @exception EOFException If end of file is reached before reading the value
438       * @exception IOException If any other error occurs
439       *
440       * @see DataOutput#writeShort
441       */
442      public final short readShort () throws IOException
443      {
444        readFully (buf, 0, 2);
445        return convertToShort (buf);
446      }
447      
448      /**
449       * This method reads 8 unsigned bits into a Java <code>int</code>
450       * value from the stream. The value returned is in the range of 0 to
451       * 255.
452       * <p>
453       * This method can read an unsigned byte written by an object
454       * implementing the <code>writeUnsignedByte()</code> method in the
455       * <code>DataOutput</code> interface.
456       *
457       * @return The unsigned bytes value read as a Java <code>int</code>.
458       *
459       * @exception EOFException If end of file is reached before reading the value
460       * @exception IOException If any other error occurs
461       *
462       * @see DataOutput#writeByte
463       */
464      public final int readUnsignedByte () throws IOException
465      {
466        return convertToUnsignedByte (in.read ());
467      }
468    
469      /**
470       * This method reads 16 unsigned bits into a Java int value from the stream.
471       * It operates by reading two bytes from the stream and converting them to 
472       * a single Java <code>int</code>  The two bytes are stored most
473       * significant byte first (i.e., "big endian") regardless of the native
474       * host byte ordering. 
475       * <p>
476       * As an example, if <code>byte1</code> and <code>byte2</code>
477       * represent the first and second byte read from the stream
478       * respectively, they will be transformed to an <code>int</code> in
479       * the following manner:
480       * <p>
481       * <code>(int)(((byte1 &amp; 0xFF) &lt;&lt; 8) + (byte2 &amp; 0xFF))</code>
482       * <p>
483       * The value returned is in the range of 0 to 65535.
484       * <p>
485       * This method can read an unsigned short written by an object
486       * implementing the <code>writeUnsignedShort()</code> method in the
487       * <code>DataOutput</code> interface.
488       *
489       * @return The unsigned short value read as a Java <code>int</code>
490       *
491       * @exception EOFException If end of file is reached before reading the value
492       * @exception IOException If any other error occurs
493       *
494       * @see DataOutput#writeShort
495       */
496      public final int readUnsignedShort () throws IOException
497      {
498        readFully (buf, 0, 2);
499        return convertToUnsignedShort (buf);
500      }
501    
502      /**
503       * This method reads a <code>String</code> from an input stream that
504       * is encoded in a modified UTF-8 format.  This format has a leading
505       * two byte sequence that contains the remaining number of bytes to
506       * read.  This two byte sequence is read using the
507       * <code>readUnsignedShort()</code> method of this interface.
508       * <p>
509       * After the number of remaining bytes have been determined, these
510       * bytes are read an transformed into <code>char</code> values.
511       * These <code>char</code> values are encoded in the stream using
512       * either a one, two, or three byte format.  The particular format
513       * in use can be determined by examining the first byte read.
514       * <p>
515       * If the first byte has a high order bit of 0, then that character
516       * consists on only one byte.  This character value consists of
517       * seven bits that are at positions 0 through 6 of the byte.  As an
518       * example, if <code>byte1</code> is the byte read from the stream,
519       * it would be converted to a <code>char</code> like so:
520       * <p>
521       * <code>(char)byte1</code>
522       * <p>
523       * If the first byte has 110 as its high order bits, then the 
524       * character consists of two bytes.  The bits that make up the character
525       * value are in positions 0 through 4 of the first byte and bit positions
526       * 0 through 5 of the second byte.  (The second byte should have 
527       * 10 as its high order bits).  These values are in most significant
528       * byte first (i.e., "big endian") order.
529       * <p>
530       * As an example, if <code>byte1</code> and <code>byte2</code> are
531       * the first two bytes read respectively, and the high order bits of
532       * them match the patterns which indicate a two byte character
533       * encoding, then they would be converted to a Java
534       * <code>char</code> like so:
535       * <p>
536       * <code>(char)(((byte1 & 0x1F) << 6) | (byte2 & 0x3F))</code>
537       * <p>
538       * If the first byte has a 1110 as its high order bits, then the
539       * character consists of three bytes.  The bits that make up the character
540       * value are in positions 0 through 3 of the first byte and bit positions
541       * 0 through 5 of the other two bytes.  (The second and third bytes should
542       * have 10 as their high order bits).  These values are in most
543       * significant byte first (i.e., "big endian") order.
544       * <p>
545       * As an example, if <code>byte1</code> <code>byte2</code> and
546       * <code>byte3</code> are the three bytes read, and the high order
547       * bits of them match the patterns which indicate a three byte
548       * character encoding, then they would be converted to a Java
549       * <code>char</code> like so:
550       * <p>
551       * <code>(char)(((byte1 & 0x0F) << 12) | ((byte2 & 0x3F) << 6) | 
552       * (byte3 & 0x3F))</code>
553       * <p>
554       * Note that all characters are encoded in the method that requires
555       * the fewest number of bytes with the exception of the character
556       * with the value of <code>&#92;u0000</code> which is encoded as two
557       * bytes.  This is a modification of the UTF standard used to
558       * prevent C language style <code>NUL</code> values from appearing
559       * in the byte stream.
560       * <p>
561       * This method can read data that was written by an object implementing the
562       * <code>writeUTF()</code> method in <code>DataOutput</code>
563       * 
564       * @return The <code>String</code> read
565       *
566       * @exception EOFException If end of file is reached before reading
567       * the String
568       * @exception UTFDataFormatException If the data is not in UTF-8 format
569       * @exception IOException If any other error occurs
570       *
571       * @see DataOutput#writeUTF
572       */
573      public final String readUTF () throws IOException
574      {
575        return readUTF (this);
576      }
577    
578      /**
579       * This method reads a String encoded in UTF-8 format from the 
580       * specified <code>DataInput</code> source.
581       *
582       * @param in The <code>DataInput</code> source to read from
583       *
584       * @return The String read from the source
585       *
586       * @exception IOException If an error occurs
587       *
588       * @see DataInput#readUTF
589       */
590      public static final String readUTF(DataInput in) throws IOException
591      {
592        final int UTFlen = in.readUnsignedShort ();
593        byte[] buf = new byte [UTFlen];
594    
595        // This blocks until the entire string is available rather than
596        // doing partial processing on the bytes that are available and then
597        // blocking.  An advantage of the latter is that Exceptions
598        // could be thrown earlier.  The former is a bit cleaner.
599        in.readFully (buf, 0, UTFlen);
600    
601        return convertFromUTF (buf);
602      }
603    
604      /**
605       * This method attempts to skip and discard the specified number of bytes 
606       * in the input stream.  It may actually skip fewer bytes than requested. 
607       * This method will not skip any bytes if passed a negative number of bytes 
608       * to skip. 
609       *
610       * @param n The requested number of bytes to skip.
611       *
612       * @return The requested number of bytes to skip.
613       *
614       * @exception IOException If an error occurs.
615       * @specnote The JDK docs claim that this returns the number of bytes 
616       *  actually skipped. The JCL claims that this method can throw an 
617       *  EOFException. Neither of these appear to be true in the JDK 1.3's
618       *  implementation. This tries to implement the actual JDK behaviour.
619       */
620      public final int skipBytes (int n) throws IOException
621      {
622        if (n <= 0)
623          return 0;    
624        try
625          {
626            return (int) in.skip (n);
627          }
628        catch (EOFException x)
629          {
630            // do nothing.
631          }         
632        return n;
633      }
634      
635      static boolean convertToBoolean (int b) throws EOFException
636      {
637        if (b < 0)
638          throw new EOFException ();
639        
640        return (b != 0);
641      }
642    
643      static byte convertToByte (int i) throws EOFException
644      {
645        if (i < 0)
646          throw new EOFException ();
647        
648        return (byte) i;
649      }
650    
651      static int convertToUnsignedByte (int i) throws EOFException
652      {
653        if (i < 0)
654          throw new EOFException ();
655        
656        return (i & 0xFF);
657      }
658    
659      static char convertToChar (byte[] buf)
660      {
661        return (char) ((buf [0] << 8)
662                        | (buf [1] & 0xff));  
663      }  
664    
665      static short convertToShort (byte[] buf)
666      {
667        return (short) ((buf [0] << 8)
668                        | (buf [1] & 0xff));  
669      }  
670    
671      static int convertToUnsignedShort (byte[] buf)
672      {
673        return (((buf [0] & 0xff) << 8)
674                | (buf [1] & 0xff));  
675      }
676    
677      static int convertToInt (byte[] buf)
678      {
679        return (((buf [0] & 0xff) << 24)
680                | ((buf [1] & 0xff) << 16)
681                | ((buf [2] & 0xff) << 8)
682                | (buf [3] & 0xff));  
683      }
684    
685      static long convertToLong (byte[] buf)
686      {
687        return (((long)(buf [0] & 0xff) << 56) |
688                ((long)(buf [1] & 0xff) << 48) |
689                ((long)(buf [2] & 0xff) << 40) |
690                ((long)(buf [3] & 0xff) << 32) |
691                ((long)(buf [4] & 0xff) << 24) |
692                ((long)(buf [5] & 0xff) << 16) |
693                ((long)(buf [6] & 0xff) <<  8) |
694                ((long)(buf [7] & 0xff)));  
695      }
696    
697      // FIXME: This method should be re-thought.  I suspect we have multiple
698      // UTF-8 decoders floating around.  We should use the standard charset
699      // converters, maybe and adding a direct call into one of the new
700      // NIO converters for a super-fast UTF8 decode.
701      static String convertFromUTF (byte[] buf) 
702        throws EOFException, UTFDataFormatException
703      {
704        // Give StringBuffer an initial estimated size to avoid 
705        // enlarge buffer frequently
706        StringBuffer strbuf = new StringBuffer (buf.length / 2 + 2);
707    
708        for (int i = 0; i < buf.length; )
709          {
710            if ((buf [i] & 0x80) == 0)          // bit pattern 0xxxxxxx
711              strbuf.append ((char) (buf [i++] & 0xFF));
712            else if ((buf [i] & 0xE0) == 0xC0)  // bit pattern 110xxxxx
713              {
714                if (i + 1 >= buf.length
715                    || (buf [i + 1] & 0xC0) != 0x80)
716                  throw new UTFDataFormatException ();
717    
718                strbuf.append((char) (((buf [i++] & 0x1F) << 6)
719                                      | (buf [i++] & 0x3F)));
720              }
721            else if ((buf [i] & 0xF0) == 0xE0)  // bit pattern 1110xxxx
722              {
723                if (i + 2 >= buf.length
724                    || (buf [i + 1] & 0xC0) != 0x80
725                    || (buf [i + 2] & 0xC0) != 0x80)
726                  throw new UTFDataFormatException ();
727    
728                strbuf.append ((char) (((buf [i++] & 0x0F) << 12)
729                                       | ((buf [i++] & 0x3F) << 6)
730                                       | (buf [i++] & 0x3F)));
731              }
732            else // must be ((buf [i] & 0xF0) == 0xF0 || (buf [i] & 0xC0) == 0x80)
733              throw new UTFDataFormatException ();  // bit patterns 1111xxxx or
734                                                    //              10xxxxxx
735          }
736    
737        return strbuf.toString ();
738      }
739    }