1 /*
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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
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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.
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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
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19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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24  */
25 
26 package jdk.internal.loader;
27 
28 import java.io.EOFException;
29 import java.net.URL;
30 import java.io.IOException;
31 import java.io.InterruptedIOException;
32 import java.io.InputStream;
33 import java.security.CodeSigner;
34 import java.util.jar.Manifest;
35 import java.nio.ByteBuffer;
36 import java.util.Arrays;
37 import sun.nio.ByteBuffered;
38 
39 /**
40  * This class is used to represent a Resource that has been loaded
41  * from the class path.
42  *
43  * @author  David Connelly
44  * @since   1.2
45  */
46 public abstract class Resource {
47     /**
48      * Returns the name of the Resource.
49      */
getName()50     public abstract String getName();
51 
52     /**
53      * Returns the URL of the Resource.
54      */
getURL()55     public abstract URL getURL();
56 
57     /**
58      * Returns the CodeSource URL for the Resource.
59      */
getCodeSourceURL()60     public abstract URL getCodeSourceURL();
61 
62     /**
63      * Returns an InputStream for reading the Resource data.
64      */
getInputStream()65     public abstract InputStream getInputStream() throws IOException;
66 
67     /**
68      * Returns the length of the Resource data, or -1 if unknown.
69      */
getContentLength()70     public abstract int getContentLength() throws IOException;
71 
72     private InputStream cis;
73 
74     /* Cache result in case getBytes is called after getByteBuffer. */
cachedInputStream()75     private synchronized InputStream cachedInputStream() throws IOException {
76         if (cis == null) {
77             cis = getInputStream();
78         }
79         return cis;
80     }
81 
82     /**
83      * Returns the Resource data as an array of bytes.
84      */
getBytes()85     public byte[] getBytes() throws IOException {
86         byte[] b;
87         // Get stream before content length so that a FileNotFoundException
88         // can propagate upwards without being caught too early
89         InputStream in = cachedInputStream();
90 
91         // This code has been uglified to protect against interrupts.
92         // Even if a thread has been interrupted when loading resources,
93         // the IO should not abort, so must carefully retry, failing only
94         // if the retry leads to some other IO exception.
95 
96         boolean isInterrupted = Thread.interrupted();
97         int len;
98         for (;;) {
99             try {
100                 len = getContentLength();
101                 break;
102             } catch (InterruptedIOException iioe) {
103                 Thread.interrupted();
104                 isInterrupted = true;
105             }
106         }
107 
108         try {
109             b = new byte[0];
110             if (len == -1) len = Integer.MAX_VALUE;
111             int pos = 0;
112             while (pos < len) {
113                 int bytesToRead;
114                 if (pos >= b.length) { // Only expand when there's no room
115                     bytesToRead = Math.min(len - pos, b.length + 1024);
116                     if (bytesToRead < 0) {
117                         // Can overflow only due to large b.length
118                         bytesToRead = len - pos;
119                     }
120                     b = Arrays.copyOf(b, pos + bytesToRead);
121                 } else {
122                     bytesToRead = b.length - pos;
123                 }
124                 int cc = 0;
125                 try {
126                     cc = in.read(b, pos, bytesToRead);
127                 } catch (InterruptedIOException iioe) {
128                     Thread.interrupted();
129                     isInterrupted = true;
130                 }
131                 if (cc < 0) {
132                     if (len != Integer.MAX_VALUE) {
133                         throw new EOFException("Detect premature EOF");
134                     } else {
135                         if (b.length != pos) {
136                             b = Arrays.copyOf(b, pos);
137                         }
138                         break;
139                     }
140                 }
141                 pos += cc;
142             }
143         } finally {
144             try {
145                 in.close();
146             } catch (InterruptedIOException iioe) {
147                 isInterrupted = true;
148             } catch (IOException ignore) {}
149 
150             if (isInterrupted) {
151                 Thread.currentThread().interrupt();
152             }
153         }
154         return b;
155     }
156 
157     /**
158      * Returns the Resource data as a ByteBuffer, but only if the input stream
159      * was implemented on top of a ByteBuffer. Return {@code null} otherwise.
160      * @return Resource data or null.
161      */
getByteBuffer()162     public ByteBuffer getByteBuffer() throws IOException {
163         InputStream in = cachedInputStream();
164         if (in instanceof ByteBuffered) {
165             return ((ByteBuffered)in).getByteBuffer();
166         }
167         return null;
168     }
169 
170     /**
171      * Returns the Manifest for the Resource, or null if none.
172      */
getManifest()173     public Manifest getManifest() throws IOException {
174         return null;
175     }
176 
177     /**
178      * Returns theCertificates for the Resource, or null if none.
179      */
getCertificates()180     public java.security.cert.Certificate[] getCertificates() {
181         return null;
182     }
183 
184     /**
185      * Returns the code signers for the Resource, or null if none.
186      */
getCodeSigners()187     public CodeSigner[] getCodeSigners() {
188         return null;
189     }
190 }
191