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1
19
20 package edu.umd.cs.findbugs.detect;
21
22
23 import edu.umd.cs.findbugs.*;
24 import java.util.*;
25 import org.apache.bcel.classfile.*;
26
27 public class MutableStaticFields extends BytecodeScanningDetector {
28
29
30 static String  extractPackage(String c) {
31 int i = c.lastIndexOf('/');
32 if (i < 0) return "";
33 return c.substring(0, i);
34 }
35
36 static boolean mutableSignature(String sig) {
37 return sig.equals("Ljava/util/Hashtable;")
38 || sig.equals("Ljava/util/Date;")
39 || sig.charAt(0) == '[';
40 }
41
42 static class FieldRecord {
43 String className;
44 String name;
45 String signature;
46 boolean isPublic;
47 boolean isFinal;
48 }
49
50
51 LinkedList<FieldRecord> seen = new LinkedList<FieldRecord>();
52 boolean publicClass;
53 boolean zeroOnTOS;
54 boolean emptyArrayOnTOS;
55 boolean inStaticInitializer;
56 String packageName;
57 Set<String > unsafeValue = new HashSet<String >();
58 Set<String > interfaces = new HashSet<String >();
59 Set<String > notFinal = new HashSet<String >();
60 Set<String > outsidePackage = new HashSet<String >();
61 Map<String , SourceLineAnnotation> firstFieldUse = new HashMap<String , SourceLineAnnotation>();
62 private BugReporter bugReporter;
63
64 public MutableStaticFields(BugReporter bugReporter) {
65 this.bugReporter = bugReporter;
66 }
67
68 @Override
69 public void visit(JavaClass obj) {
70 super.visit(obj);
71 int flags = obj.getAccessFlags();
72 publicClass = (flags & ACC_PUBLIC) != 0
73 && !getDottedClassName().startsWith("sun.");
74 if ((flags & ACC_INTERFACE) != 0) {
75 interfaces.add(getDottedClassName());
76 }
77
78 packageName = extractPackage(getClassName());
79 }
80
81 @Override
82 public void visit(Method obj) {
83 zeroOnTOS = false;
84 inStaticInitializer = getMethodName().equals("<clinit>");
86 }
87
88 @Override
89 public void sawOpcode(int seen) {
90 switch (seen) {
92 case GETSTATIC:
93 case PUTSTATIC:
94 boolean samePackage =
95 packageName.equals(extractPackage(getClassConstantOperand()));
96 boolean initOnly =
97 seen == GETSTATIC ||
98 getClassName().equals(getClassConstantOperand())
99 && inStaticInitializer;
100 boolean safeValue =
101 seen == GETSTATIC || emptyArrayOnTOS
102 || !mutableSignature(getSigConstantOperand());
103 String name = (getClassConstantOperand() + "." + getNameConstantOperand())
104 .replace('/', '.');
105
114
115 if (!samePackage)
116 outsidePackage.add(name);
117
118 if (!initOnly)
119 notFinal.add(name);
120
121 if (!safeValue)
122 unsafeValue.add(name);
123
124 if (inStaticInitializer && !firstFieldUse.containsKey(name)) {
127 SourceLineAnnotation sla = SourceLineAnnotation.fromVisitedInstruction(this);
128 firstFieldUse.put(name, sla);
129 }
130 break;
131 case ANEWARRAY:
132 case NEWARRAY:
133 if (zeroOnTOS)
134 emptyArrayOnTOS = true;
135 zeroOnTOS = false;
136 return;
137 case ICONST_0:
138 zeroOnTOS = true;
139 emptyArrayOnTOS = false;
140 return;
141 }
142 zeroOnTOS = false;
143 emptyArrayOnTOS = false;
144 }
145
146 @Override
147 public void visit(Field obj) {
148 super.visit(obj);
149 int flags = obj.getAccessFlags();
150 boolean isStatic = (flags & ACC_STATIC) != 0;
151 if (!isStatic) return;
152 boolean isVolatile = (flags & ACC_VOLATILE) != 0;
153 if (isVolatile) return;
154 boolean isFinal = (flags & ACC_FINAL) != 0;
155 boolean isPublic = publicClass && (flags & ACC_PUBLIC) != 0;
156 boolean isProtected = publicClass && (flags & ACC_PROTECTED) != 0;
157 if (!isPublic && !isProtected) return;
158
159 boolean isHashtable =
160 getFieldSig().equals("Ljava/util/Hashtable;");
161 boolean isArray = getFieldSig().charAt(0) == '[';
162
163 if (isFinal && !(isHashtable || isArray)) return;
164
165 FieldRecord f = new FieldRecord();
166 f.className = getDottedClassName();
167 f.name = getFieldName();
168 f.signature = getFieldSig();
169 f.isPublic = isPublic;
170 f.isFinal = isFinal;
171
172 seen.add(f);
173
174 }
175
176 @Override
177 public void report() {
178
183 for (FieldRecord f : seen) {
184 boolean isFinal = f.isFinal;
185 String className = f.className;
186 String fieldSig = f.signature;
187 String fieldName = f.name;
188 String name = className + "." + fieldName;
189 boolean couldBeFinal = !isFinal
190 && !notFinal.contains(name);
191 boolean isPublic = f.isPublic;
192 boolean couldBePackage = !outsidePackage.contains(name);
193 boolean movedOutofInterface = couldBePackage &&
194 interfaces.contains(className);
195 boolean isHashtable = fieldSig.equals("Ljava.util.Hashtable;");
196 boolean isArray = fieldSig.charAt(0) == '['
197 && unsafeValue.contains(name);
198
199 if (false)
200 System.out.println(className + "." + fieldName
201 + " : " + fieldSig
202 + " " + isHashtable
203 + " " + isArray
204 );
205
206
207 String bugType;
208 int priority = NORMAL_PRIORITY;
209 if (isFinal && !isHashtable && !isArray) {
210 continue;
211 } else if (movedOutofInterface) {
212 bugType = "MS_OOI_PKGPROTECT";
213 } else if (couldBePackage && couldBeFinal && (isHashtable || isArray))
214 bugType = "MS_FINAL_PKGPROTECT";
215 else if (couldBeFinal && !isHashtable && !isArray) {
216 bugType = "MS_SHOULD_BE_FINAL";
217 if (fieldName.equals(fieldName.toUpperCase())
218 || fieldSig.charAt(0) == 'L')
219 priority = HIGH_PRIORITY;
220 } else if (couldBePackage)
221 bugType = "MS_PKGPROTECT";
222 else if (isHashtable) {
223 bugType = "MS_MUTABLE_HASHTABLE";
224 if (!isFinal)
225 priority = HIGH_PRIORITY;
226 } else if (isArray) {
227 bugType = "MS_MUTABLE_ARRAY";
228 if (fieldSig.indexOf("L") >= 0 || !isFinal)
229 priority = HIGH_PRIORITY;
230 } else if (!isFinal)
231 bugType = "MS_CANNOT_BE_FINAL";
232 else
233 throw new IllegalStateException ("impossible");
234
235
236 BugInstance bug = new BugInstance(this, bugType, priority)
237 .addClass(className)
238 .addField(className, fieldName, fieldSig, true);
239 SourceLineAnnotation firstPC = firstFieldUse.get(className + "." + fieldName);
240 if (firstPC != null)
241 bug.addSourceLine(firstPC);
242 bugReporter.reportBug(bug);
243
244 }
245 }
246 }
247 |
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