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Java > Open Source Codes > edu > umd > cs > findbugs > detect > MutableLock


1 /*
2  * FindBugs - Find bugs in Java programs
3  * Copyright (C) 2003-2005 University of Maryland
4  *
5  * This library is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation; either
8  * version 2.1 of the License, or (at your option) any later version.
9  *
10  * This library is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with this library; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18  */
19
20 package edu.umd.cs.findbugs.detect;
21
22
23 import edu.umd.cs.findbugs.*;
24 import java.util.*;
25
26 import org.apache.bcel.classfile.Field;
27 import org.apache.bcel.classfile.JavaClass;
28 import org.apache.bcel.classfile.Method;
29
30 public class MutableLock extends BytecodeScanningDetector implements StatelessDetector {
31     Set<String JavaDoc> setFields = new HashSet<String JavaDoc>();
32     Set<String JavaDoc> finalFields = new HashSet<String JavaDoc>();
33     boolean thisOnTOS = false;
34     private BugReporter bugReporter;
35
36     public MutableLock(BugReporter bugReporter) {
37         this.bugReporter = bugReporter;
38     }
39
40
41     @Override JavaDoc
42     public void visit(JavaClass obj) {
43         finalFields.clear();
44         super.visit(obj);
45     }
46
47     @Override JavaDoc
48     public void visit(Field obj) {
49     super.visit(obj);
50     if (obj.isFinal()) finalFields.add(obj.getName());
51 }
52     @Override JavaDoc
53          public void visit(Method obj) {
54         super.visit(obj);
55         setFields.clear();
56         thisOnTOS = false;
57     }
58
59     @Override JavaDoc
60          public void sawOpcode(int seen) {
61
62         switch (seen) {
63         case ALOAD_0:
64             thisOnTOS = true;
65             return;
66         case MONITOREXIT:
67             setFields.clear();
68             break;
69         case PUTFIELD:
70             if (getClassConstantOperand().equals(getClassName()))
71                 setFields.add(getNameConstantOperand());
72             break;
73         case GETFIELD:
74             if (thisOnTOS && getClassConstantOperand().equals(getClassName())
75                     && setFields.contains(getNameConstantOperand())
76                     && asUnsignedByte(codeBytes[getPC() + 3]) == DUP
77                     && asUnsignedByte(codeBytes[getPC() + 5]) == MONITORENTER
78                     
79                     && !finalFields.contains(getNameConstantOperand())
80             )
81                 bugReporter.reportBug(new BugInstance(this, "ML_SYNC_ON_UPDATED_FIELD", NORMAL_PRIORITY)
82                         .addClassAndMethod(this)
83                         .addReferencedField(this)
84                         .addSourceLine(this, getPC() + 5));
85             break;
86         default:
87         }
88         thisOnTOS = false;
89     }
90 }
91
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