1/*
2 * Copyright (c) 1994, 2006, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package java.io;
27
28/**
29 * A data input stream lets an application read primitive Java data
30 * types from an underlying input stream in a machine-independent
31 * way. An application uses a data output stream to write data that
32 * can later be read by a data input stream.
33 * <p>
34 * DataInputStream is not necessarily safe for multithreaded access.
35 * Thread safety is optional and is the responsibility of users of
36 * methods in this class.
37 *
38 * @author  Arthur van Hoff
39 * @see     java.io.DataOutputStream
40 * @since   JDK1.0
41 */
42public
43class DataInputStream extends FilterInputStream implements DataInput {
44
45    /**
46     * Creates a DataInputStream that uses the specified
47     * underlying InputStream.
48     *
49     * @param  in   the specified input stream
50     */
51    public DataInputStream(InputStream in) {
52        super(in);
53    }
54
55    /**
56     * working arrays initialized on demand by readUTF
57     */
58    private byte bytearr[] = new byte[80];
59    private char chararr[] = new char[80];
60
61    /**
62     * Reads some number of bytes from the contained input stream and
63     * stores them into the buffer array <code>b</code>. The number of
64     * bytes actually read is returned as an integer. This method blocks
65     * until input data is available, end of file is detected, or an
66     * exception is thrown.
67     *
68     * <p>If <code>b</code> is null, a <code>NullPointerException</code> is
69     * thrown. If the length of <code>b</code> is zero, then no bytes are
70     * read and <code>0</code> is returned; otherwise, there is an attempt
71     * to read at least one byte. If no byte is available because the
72     * stream is at end of file, the value <code>-1</code> is returned;
73     * otherwise, at least one byte is read and stored into <code>b</code>.
74     *
75     * <p>The first byte read is stored into element <code>b[0]</code>, the
76     * next one into <code>b[1]</code>, and so on. The number of bytes read
77     * is, at most, equal to the length of <code>b</code>. Let <code>k</code>
78     * be the number of bytes actually read; these bytes will be stored in
79     * elements <code>b[0]</code> through <code>b[k-1]</code>, leaving
80     * elements <code>b[k]</code> through <code>b[b.length-1]</code>
81     * unaffected.
82     *
83     * <p>The <code>read(b)</code> method has the same effect as:
84     * <blockquote><pre>
85     * read(b, 0, b.length)
86     * </pre></blockquote>
87     *
88     * @param      b   the buffer into which the data is read.
89     * @return     the total number of bytes read into the buffer, or
90     *             <code>-1</code> if there is no more data because the end
91     *             of the stream has been reached.
92     * @exception  IOException if the first byte cannot be read for any reason
93     * other than end of file, the stream has been closed and the underlying
94     * input stream does not support reading after close, or another I/O
95     * error occurs.
96     * @see        java.io.FilterInputStream#in
97     * @see        java.io.InputStream#read(byte[], int, int)
98     */
99    public final int read(byte b[]) throws IOException {
100        return in.read(b, 0, b.length);
101    }
102
103    /**
104     * Reads up to <code>len</code> bytes of data from the contained
105     * input stream into an array of bytes.  An attempt is made to read
106     * as many as <code>len</code> bytes, but a smaller number may be read,
107     * possibly zero. The number of bytes actually read is returned as an
108     * integer.
109     *
110     * <p> This method blocks until input data is available, end of file is
111     * detected, or an exception is thrown.
112     *
113     * <p> If <code>len</code> is zero, then no bytes are read and
114     * <code>0</code> is returned; otherwise, there is an attempt to read at
115     * least one byte. If no byte is available because the stream is at end of
116     * file, the value <code>-1</code> is returned; otherwise, at least one
117     * byte is read and stored into <code>b</code>.
118     *
119     * <p> The first byte read is stored into element <code>b[off]</code>, the
120     * next one into <code>b[off+1]</code>, and so on. The number of bytes read
121     * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of
122     * bytes actually read; these bytes will be stored in elements
123     * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>,
124     * leaving elements <code>b[off+</code><i>k</i><code>]</code> through
125     * <code>b[off+len-1]</code> unaffected.
126     *
127     * <p> In every case, elements <code>b[0]</code> through
128     * <code>b[off]</code> and elements <code>b[off+len]</code> through
129     * <code>b[b.length-1]</code> are unaffected.
130     *
131     * @param      b     the buffer into which the data is read.
132     * @param off the start offset in the destination array <code>b</code>
133     * @param      len   the maximum number of bytes read.
134     * @return     the total number of bytes read into the buffer, or
135     *             <code>-1</code> if there is no more data because the end
136     *             of the stream has been reached.
137     * @exception  NullPointerException If <code>b</code> is <code>null</code>.
138     * @exception  IndexOutOfBoundsException If <code>off</code> is negative,
139     * <code>len</code> is negative, or <code>len</code> is greater than
140     * <code>b.length - off</code>
141     * @exception  IOException if the first byte cannot be read for any reason
142     * other than end of file, the stream has been closed and the underlying
143     * input stream does not support reading after close, or another I/O
144     * error occurs.
145     * @see        java.io.FilterInputStream#in
146     * @see        java.io.InputStream#read(byte[], int, int)
147     */
148    public final int read(byte b[], int off, int len) throws IOException {
149        return in.read(b, off, len);
150    }
151
152    /**
153     * See the general contract of the <code>readFully</code>
154     * method of <code>DataInput</code>.
155     * <p>
156     * Bytes
157     * for this operation are read from the contained
158     * input stream.
159     *
160     * @param      b   the buffer into which the data is read.
161     * @exception  EOFException  if this input stream reaches the end before
162     *             reading all the bytes.
163     * @exception  IOException   the stream has been closed and the contained
164     *             input stream does not support reading after close, or
165     *             another I/O error occurs.
166     * @see        java.io.FilterInputStream#in
167     */
168    public final void readFully(byte b[]) throws IOException {
169        readFully(b, 0, b.length);
170    }
171
172    /**
173     * See the general contract of the <code>readFully</code>
174     * method of <code>DataInput</code>.
175     * <p>
176     * Bytes
177     * for this operation are read from the contained
178     * input stream.
179     *
180     * @param      b     the buffer into which the data is read.
181     * @param      off   the start offset of the data.
182     * @param      len   the number of bytes to read.
183     * @exception  EOFException  if this input stream reaches the end before
184     *               reading all the bytes.
185     * @exception  IOException   the stream has been closed and the contained
186     *             input stream does not support reading after close, or
187     *             another I/O error occurs.
188     * @see        java.io.FilterInputStream#in
189     */
190    public final void readFully(byte b[], int off, int len) throws IOException {
191        if (len < 0)
192            throw new IndexOutOfBoundsException();
193        int n = 0;
194        while (n < len) {
195            int count = in.read(b, off + n, len - n);
196            if (count < 0)
197                throw new EOFException();
198            n += count;
199        }
200    }
201
202    /**
203     * See the general contract of the <code>skipBytes</code>
204     * method of <code>DataInput</code>.
205     * <p>
206     * Bytes for this operation are read from the contained
207     * input stream.
208     *
209     * @param      n   the number of bytes to be skipped.
210     * @return     the actual number of bytes skipped.
211     * @exception  IOException  if the contained input stream does not support
212     *             seek, or the stream has been closed and
213     *             the contained input stream does not support
214     *             reading after close, or another I/O error occurs.
215     */
216    public final int skipBytes(int n) throws IOException {
217        int total = 0;
218        int cur = 0;
219
220        while ((total<n) && ((cur = (int) in.skip(n-total)) > 0)) {
221            total += cur;
222        }
223
224        return total;
225    }
226
227    /**
228     * See the general contract of the <code>readBoolean</code>
229     * method of <code>DataInput</code>.
230     * <p>
231     * Bytes for this operation are read from the contained
232     * input stream.
233     *
234     * @return     the <code>boolean</code> value read.
235     * @exception  EOFException  if this input stream has reached the end.
236     * @exception  IOException   the stream has been closed and the contained
237     *             input stream does not support reading after close, or
238     *             another I/O error occurs.
239     * @see        java.io.FilterInputStream#in
240     */
241    public final boolean readBoolean() throws IOException {
242        int ch = in.read();
243        if (ch < 0)
244            throw new EOFException();
245        return (ch != 0);
246    }
247
248    /**
249     * See the general contract of the <code>readByte</code>
250     * method of <code>DataInput</code>.
251     * <p>
252     * Bytes
253     * for this operation are read from the contained
254     * input stream.
255     *
256     * @return     the next byte of this input stream as a signed 8-bit
257     *             <code>byte</code>.
258     * @exception  EOFException  if this input stream has reached the end.
259     * @exception  IOException   the stream has been closed and the contained
260     *             input stream does not support reading after close, or
261     *             another I/O error occurs.
262     * @see        java.io.FilterInputStream#in
263     */
264    public final byte readByte() throws IOException {
265        int ch = in.read();
266        if (ch < 0)
267            throw new EOFException();
268        return (byte)(ch);
269    }
270
271    /**
272     * See the general contract of the <code>readUnsignedByte</code>
273     * method of <code>DataInput</code>.
274     * <p>
275     * Bytes
276     * for this operation are read from the contained
277     * input stream.
278     *
279     * @return     the next byte of this input stream, interpreted as an
280     *             unsigned 8-bit number.
281     * @exception  EOFException  if this input stream has reached the end.
282     * @exception  IOException   the stream has been closed and the contained
283     *             input stream does not support reading after close, or
284     *             another I/O error occurs.
285     * @see         java.io.FilterInputStream#in
286     */
287    public final int readUnsignedByte() throws IOException {
288        int ch = in.read();
289        if (ch < 0)
290            throw new EOFException();
291        return ch;
292    }
293
294    /**
295     * See the general contract of the <code>readShort</code>
296     * method of <code>DataInput</code>.
297     * <p>
298     * Bytes
299     * for this operation are read from the contained
300     * input stream.
301     *
302     * @return     the next two bytes of this input stream, interpreted as a
303     *             signed 16-bit number.
304     * @exception  EOFException  if this input stream reaches the end before
305     *               reading two bytes.
306     * @exception  IOException   the stream has been closed and the contained
307     *             input stream does not support reading after close, or
308     *             another I/O error occurs.
309     * @see        java.io.FilterInputStream#in
310     */
311    public final short readShort() throws IOException {
312        int ch1 = in.read();
313        int ch2 = in.read();
314        if ((ch1 | ch2) < 0)
315            throw new EOFException();
316        return (short)((ch1 << 8) + (ch2 << 0));
317    }
318
319    /**
320     * See the general contract of the <code>readUnsignedShort</code>
321     * method of <code>DataInput</code>.
322     * <p>
323     * Bytes
324     * for this operation are read from the contained
325     * input stream.
326     *
327     * @return     the next two bytes of this input stream, interpreted as an
328     *             unsigned 16-bit integer.
329     * @exception  EOFException  if this input stream reaches the end before
330     *             reading two bytes.
331     * @exception  IOException   the stream has been closed and the contained
332     *             input stream does not support reading after close, or
333     *             another I/O error occurs.
334     * @see        java.io.FilterInputStream#in
335     */
336    public final int readUnsignedShort() throws IOException {
337        int ch1 = in.read();
338        int ch2 = in.read();
339        if ((ch1 | ch2) < 0)
340            throw new EOFException();
341        return (ch1 << 8) + (ch2 << 0);
342    }
343
344    /**
345     * See the general contract of the <code>readChar</code>
346     * method of <code>DataInput</code>.
347     * <p>
348     * Bytes
349     * for this operation are read from the contained
350     * input stream.
351     *
352     * @return     the next two bytes of this input stream, interpreted as a
353     *             <code>char</code>.
354     * @exception  EOFException  if this input stream reaches the end before
355     *               reading two bytes.
356     * @exception  IOException   the stream has been closed and the contained
357     *             input stream does not support reading after close, or
358     *             another I/O error occurs.
359     * @see        java.io.FilterInputStream#in
360     */
361    public final char readChar() throws IOException {
362        int ch1 = in.read();
363        int ch2 = in.read();
364        if ((ch1 | ch2) < 0)
365            throw new EOFException();
366        return (char)((ch1 << 8) + (ch2 << 0));
367    }
368
369    /**
370     * See the general contract of the <code>readInt</code>
371     * method of <code>DataInput</code>.
372     * <p>
373     * Bytes
374     * for this operation are read from the contained
375     * input stream.
376     *
377     * @return     the next four bytes of this input stream, interpreted as an
378     *             <code>int</code>.
379     * @exception  EOFException  if this input stream reaches the end before
380     *               reading four bytes.
381     * @exception  IOException   the stream has been closed and the contained
382     *             input stream does not support reading after close, or
383     *             another I/O error occurs.
384     * @see        java.io.FilterInputStream#in
385     */
386    public final int readInt() throws IOException {
387        int ch1 = in.read();
388        int ch2 = in.read();
389        int ch3 = in.read();
390        int ch4 = in.read();
391        if ((ch1 | ch2 | ch3 | ch4) < 0)
392            throw new EOFException();
393        return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
394    }
395
396    private byte readBuffer[] = new byte[8];
397
398    /**
399     * See the general contract of the <code>readLong</code>
400     * method of <code>DataInput</code>.
401     * <p>
402     * Bytes
403     * for this operation are read from the contained
404     * input stream.
405     *
406     * @return     the next eight bytes of this input stream, interpreted as a
407     *             <code>long</code>.
408     * @exception  EOFException  if this input stream reaches the end before
409     *               reading eight bytes.
410     * @exception  IOException   the stream has been closed and the contained
411     *             input stream does not support reading after close, or
412     *             another I/O error occurs.
413     * @see        java.io.FilterInputStream#in
414     */
415    public final long readLong() throws IOException {
416        readFully(readBuffer, 0, 8);
417        return (((long)readBuffer[0] << 56) +
418                ((long)(readBuffer[1] & 255) << 48) +
419                ((long)(readBuffer[2] & 255) << 40) +
420                ((long)(readBuffer[3] & 255) << 32) +
421                ((long)(readBuffer[4] & 255) << 24) +
422                ((readBuffer[5] & 255) << 16) +
423                ((readBuffer[6] & 255) <<  8) +
424                ((readBuffer[7] & 255) <<  0));
425    }
426
427    /**
428     * See the general contract of the <code>readFloat</code>
429     * method of <code>DataInput</code>.
430     * <p>
431     * Bytes
432     * for this operation are read from the contained
433     * input stream.
434     *
435     * @return     the next four bytes of this input stream, interpreted as a
436     *             <code>float</code>.
437     * @exception  EOFException  if this input stream reaches the end before
438     *               reading four bytes.
439     * @exception  IOException   the stream has been closed and the contained
440     *             input stream does not support reading after close, or
441     *             another I/O error occurs.
442     * @see        java.io.DataInputStream#readInt()
443     * @see        java.lang.Float#intBitsToFloat(int)
444     */
445    public final float readFloat() throws IOException {
446        return Float.intBitsToFloat(readInt());
447    }
448
449    /**
450     * See the general contract of the <code>readDouble</code>
451     * method of <code>DataInput</code>.
452     * <p>
453     * Bytes
454     * for this operation are read from the contained
455     * input stream.
456     *
457     * @return     the next eight bytes of this input stream, interpreted as a
458     *             <code>double</code>.
459     * @exception  EOFException  if this input stream reaches the end before
460     *               reading eight bytes.
461     * @exception  IOException   the stream has been closed and the contained
462     *             input stream does not support reading after close, or
463     *             another I/O error occurs.
464     * @see        java.io.DataInputStream#readLong()
465     * @see        java.lang.Double#longBitsToDouble(long)
466     */
467    public final double readDouble() throws IOException {
468        return Double.longBitsToDouble(readLong());
469    }
470
471    private char lineBuffer[];
472
473    /**
474     * See the general contract of the <code>readLine</code>
475     * method of <code>DataInput</code>.
476     * <p>
477     * Bytes
478     * for this operation are read from the contained
479     * input stream.
480     *
481     * @deprecated This method does not properly convert bytes to characters.
482     * As of JDK&nbsp;1.1, the preferred way to read lines of text is via the
483     * <code>BufferedReader.readLine()</code> method.  Programs that use the
484     * <code>DataInputStream</code> class to read lines can be converted to use
485     * the <code>BufferedReader</code> class by replacing code of the form:
486     * <blockquote><pre>
487     *     DataInputStream d =&nbsp;new&nbsp;DataInputStream(in);
488     * </pre></blockquote>
489     * with:
490     * <blockquote><pre>
491     *     BufferedReader d
492     *          =&nbsp;new&nbsp;BufferedReader(new&nbsp;InputStreamReader(in));
493     * </pre></blockquote>
494     *
495     * @return     the next line of text from this input stream.
496     * @exception  IOException  if an I/O error occurs.
497     * @see        java.io.BufferedReader#readLine()
498     * @see        java.io.FilterInputStream#in
499     */
500    @Deprecated
501    public final String readLine() throws IOException {
502        char buf[] = lineBuffer;
503
504        if (buf == null) {
505            buf = lineBuffer = new char[128];
506        }
507
508        int room = buf.length;
509        int offset = 0;
510        int c;
511
512loop:   while (true) {
513            switch (c = in.read()) {
514              case -1:
515              case '\n':
516                break loop;
517
518              case '\r':
519                int c2 = in.read();
520                if ((c2 != '\n') && (c2 != -1)) {
521                    if (!(in instanceof PushbackInputStream)) {
522                        this.in = new PushbackInputStream(in);
523                    }
524                    ((PushbackInputStream)in).unread(c2);
525                }
526                break loop;
527
528              default:
529                if (--room < 0) {
530                    buf = new char[offset + 128];
531                    room = buf.length - offset - 1;
532                    System.arraycopy(lineBuffer, 0, buf, 0, offset);
533                    lineBuffer = buf;
534                }
535                buf[offset++] = (char) c;
536                break;
537            }
538        }
539        if ((c == -1) && (offset == 0)) {
540            return null;
541        }
542        return String.copyValueOf(buf, 0, offset);
543    }
544
545    /**
546     * See the general contract of the <code>readUTF</code>
547     * method of <code>DataInput</code>.
548     * <p>
549     * Bytes
550     * for this operation are read from the contained
551     * input stream.
552     *
553     * @return     a Unicode string.
554     * @exception  EOFException  if this input stream reaches the end before
555     *               reading all the bytes.
556     * @exception  IOException   the stream has been closed and the contained
557     *             input stream does not support reading after close, or
558     *             another I/O error occurs.
559     * @exception  UTFDataFormatException if the bytes do not represent a valid
560     *             modified UTF-8 encoding of a string.
561     * @see        java.io.DataInputStream#readUTF(java.io.DataInput)
562     */
563    public final String readUTF() throws IOException {
564        return readUTF(this);
565    }
566
567    /**
568     * Reads from the
569     * stream <code>in</code> a representation
570     * of a Unicode  character string encoded in
571     * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> format;
572     * this string of characters is then returned as a <code>String</code>.
573     * The details of the modified UTF-8 representation
574     * are  exactly the same as for the <code>readUTF</code>
575     * method of <code>DataInput</code>.
576     *
577     * @param      in   a data input stream.
578     * @return     a Unicode string.
579     * @exception  EOFException            if the input stream reaches the end
580     *               before all the bytes.
581     * @exception  IOException   the stream has been closed and the contained
582     *             input stream does not support reading after close, or
583     *             another I/O error occurs.
584     * @exception  UTFDataFormatException  if the bytes do not represent a
585     *               valid modified UTF-8 encoding of a Unicode string.
586     * @see        java.io.DataInputStream#readUnsignedShort()
587     */
588    public final static String readUTF(DataInput in) throws IOException {
589        int utflen = in.readUnsignedShort();
590        byte[] bytearr = null;
591        char[] chararr = null;
592        if (in instanceof DataInputStream) {
593            DataInputStream dis = (DataInputStream)in;
594            if (dis.bytearr.length < utflen){
595                dis.bytearr = new byte[utflen*2];
596                dis.chararr = new char[utflen*2];
597            }
598            chararr = dis.chararr;
599            bytearr = dis.bytearr;
600        } else {
601            bytearr = new byte[utflen];
602            chararr = new char[utflen];
603        }
604
605        int c, char2, char3;
606        int count = 0;
607        int chararr_count=0;
608
609        in.readFully(bytearr, 0, utflen);
610
611        while (count < utflen) {
612            c = (int) bytearr[count] & 0xff;
613            if (c > 127) break;
614            count++;
615            chararr[chararr_count++]=(char)c;
616        }
617
618        while (count < utflen) {
619            c = (int) bytearr[count] & 0xff;
620            switch (c >> 4) {
621                case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
622                    /* 0xxxxxxx*/
623                    count++;
624                    chararr[chararr_count++]=(char)c;
625                    break;
626                case 12: case 13:
627                    /* 110x xxxx   10xx xxxx*/
628                    count += 2;
629                    if (count > utflen)
630                        throw new UTFDataFormatException(
631                            "malformed input: partial character at end");
632                    char2 = (int) bytearr[count-1];
633                    if ((char2 & 0xC0) != 0x80)
634                        throw new UTFDataFormatException(
635                            "malformed input around byte " + count);
636                    chararr[chararr_count++]=(char)(((c & 0x1F) << 6) |
637                                                    (char2 & 0x3F));
638                    break;
639                case 14:
640                    /* 1110 xxxx  10xx xxxx  10xx xxxx */
641                    count += 3;
642                    if (count > utflen)
643                        throw new UTFDataFormatException(
644                            "malformed input: partial character at end");
645                    char2 = (int) bytearr[count-2];
646                    char3 = (int) bytearr[count-1];
647                    if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80))
648                        throw new UTFDataFormatException(
649                            "malformed input around byte " + (count-1));
650                    chararr[chararr_count++]=(char)(((c     & 0x0F) << 12) |
651                                                    ((char2 & 0x3F) << 6)  |
652                                                    ((char3 & 0x3F) << 0));
653                    break;
654                default:
655                    /* 10xx xxxx,  1111 xxxx */
656                    throw new UTFDataFormatException(
657                        "malformed input around byte " + count);
658            }
659        }
660        // The number of chars produced may be less than utflen
661        return new String(chararr, 0, chararr_count);
662    }
663}
664