1 /*
2  * DeltaOutputStream
3  *
4  * Author: Lasse Collin <lasse.collin@tukaani.org>
5  *
6  * This file has been put into the public domain.
7  * You can do whatever you want with this file.
8  */
9 
10 package org.tukaani.xz;
11 
12 import java.io.IOException;
13 import org.tukaani.xz.delta.DeltaEncoder;
14 
15 class DeltaOutputStream extends FinishableOutputStream {
16     private static final int FILTER_BUF_SIZE = 4096;
17 
18     private FinishableOutputStream out;
19     private final DeltaEncoder delta;
20     private final byte[] filterBuf = new byte[FILTER_BUF_SIZE];
21 
22     private boolean finished = false;
23     private IOException exception = null;
24 
25     private final byte[] tempBuf = new byte[1];
26 
getMemoryUsage()27     static int getMemoryUsage() {
28         return 1 + FILTER_BUF_SIZE / 1024;
29     }
30 
DeltaOutputStream(FinishableOutputStream out, DeltaOptions options)31     DeltaOutputStream(FinishableOutputStream out, DeltaOptions options) {
32         this.out = out;
33         delta = new DeltaEncoder(options.getDistance());
34     }
35 
write(int b)36     public void write(int b) throws IOException {
37         tempBuf[0] = (byte)b;
38         write(tempBuf, 0, 1);
39     }
40 
write(byte[] buf, int off, int len)41     public void write(byte[] buf, int off, int len) throws IOException {
42         if (off < 0 || len < 0 || off + len < 0 || off + len > buf.length)
43             throw new IndexOutOfBoundsException();
44 
45         if (exception != null)
46             throw exception;
47 
48         if (finished)
49             throw new XZIOException("Stream finished");
50 
51         try {
52             while (len > FILTER_BUF_SIZE) {
53                 delta.encode(buf, off, FILTER_BUF_SIZE, filterBuf);
54                 out.write(filterBuf);
55                 off += FILTER_BUF_SIZE;
56                 len -= FILTER_BUF_SIZE;
57             }
58 
59             delta.encode(buf, off, len, filterBuf);
60             out.write(filterBuf, 0, len);
61         } catch (IOException e) {
62             exception = e;
63             throw e;
64         }
65     }
66 
flush()67     public void flush() throws IOException {
68         if (exception != null)
69             throw exception;
70 
71         if (finished)
72             throw new XZIOException("Stream finished or closed");
73 
74         try {
75             out.flush();
76         } catch (IOException e) {
77             exception = e;
78             throw e;
79         }
80     }
81 
finish()82     public void finish() throws IOException {
83         if (!finished) {
84             if (exception != null)
85                 throw exception;
86 
87             try {
88                 out.finish();
89             } catch (IOException e) {
90                 exception = e;
91                 throw e;
92             }
93 
94             finished = true;
95         }
96     }
97 
close()98     public void close() throws IOException {
99         if (out != null) {
100             try {
101                 out.close();
102             } catch (IOException e) {
103                 if (exception == null)
104                     exception = e;
105             }
106 
107             out = null;
108         }
109 
110         if (exception != null)
111             throw exception;
112     }
113 }
114