1 /*
2  * Copyright (c) 2003, 2019, 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.
8  *
9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  */
23 
24 import  java.io.*;
25 
26 /*
27  * Copyright 2003 Wily Technology, Inc.
28  */
29 
30 public class NamedBuffer
31 {
32     private final String    fName;
33     private final byte[]    fBuffer;
34 
35     public
NamedBuffer( String name, byte[] buffer)36     NamedBuffer(    String  name,
37                     byte[]  buffer)
38         {
39         fName =     name;
40         fBuffer =   buffer;
41         }
42 
43     public
NamedBuffer( String name, InputStream stream)44     NamedBuffer(    String      name,
45                     InputStream stream)
46         throws IOException
47         {
48         this(   name,
49                 loadBufferFromStream(stream));
50         }
51 
52     public String
getName()53     getName()
54         {
55         return fName;
56         }
57 
58     public byte[]
getBuffer()59     getBuffer()
60         {
61         return fBuffer;
62         }
63 
64     public static byte[]
loadBufferFromStream(InputStream stream)65     loadBufferFromStream(InputStream stream)
66         throws IOException
67     {
68         // hack for now, just assume the stream will fit in our reasonable size buffer.
69         // if not, panic
70         int bufferLimit = 200 * 1024;
71         byte[]  readBuffer = new byte[bufferLimit];
72         int actualSize = stream.read(readBuffer);
73         if ( actualSize >= bufferLimit )
74             {
75             // if there might be more bytes, just surrender
76             throw new IOException("too big for buffer");
77             }
78 
79         byte[] resultBuffer = new byte[actualSize];
80         System.arraycopy(   readBuffer,
81                             0,
82                             resultBuffer,
83                             0,
84                             actualSize);
85         return resultBuffer;
86     }
87 
88     static final String DEST = System.getProperty("test.classes");
89     static final boolean VERBOSE = false;
90 
checkMatch(byte[] buf, byte[] name, int begIdx)91     static boolean checkMatch(byte[] buf, byte[] name, int begIdx) {
92         if (buf.length < name.length + begIdx) {
93             return false;
94         }
95         for (int i = 0; i < name.length; i++) {
96             if (buf[i + begIdx] != name[i]) {
97                 return false;
98             }
99         }
100         return true;
101     }
102 
103     // This function reads a class file from disk and replaces the first character of
104     // the name with the one passed as "replace".  Then goes through the bytecodes to
105     // replace all instances of the name of the class with the new name.  The
106     // redefinition tests use this to redefine Host$ classes with precompiled class files
107     // Xost.java, Yost.java and Zost.java.
108     static byte[]
bytesForHostClass(char replace, String className)109     bytesForHostClass(char replace, String className) throws Throwable {
110         String tail = className.substring(1);
111         String origClassName = "" + replace + tail;
112         File clsfile = new File(DEST + "/" + origClassName + ".class");
113 
114         if (VERBOSE) {
115             System.out.println("   Reading bytes from " + clsfile);
116         }
117         byte[] buf = null;
118         try (FileInputStream str = new FileInputStream(clsfile)) {
119             buf = loadBufferFromStream(str);
120         }
121 
122         boolean found = false;
123         int dollarSignIdx = className.indexOf('$');
124         int ptrnLen = (dollarSignIdx == -1) ? className.length() : dollarSignIdx;
125         byte[] ptrnBytes = origClassName.substring(0, ptrnLen).getBytes();
126         byte firstByte = className.getBytes()[0];
127 
128         for (int i = 0; i < buf.length - ptrnLen; i++) {
129             if (checkMatch(buf, ptrnBytes, i)) {
130                 if (VERBOSE) {
131                     System.out.println("Appear to have found " + origClassName + " starting at " + i);
132                 }
133                 buf[i] = firstByte;
134                 found = true;
135             }
136         }
137         if (!found) {
138             throw new Error("Could not locate '" + ptrnBytes + "' name in byte array");
139         }
140         return buf;
141     }
142 }
143