#1393 PMD hanging during DataflowAnomalyAnalysis

pmd-core/src/main/java/net/sourceforge/pmd/lang/dfa/Linker.java

@@ -17,6 +17,9 @@ public class Linker {
     private final static Logger LOGGER = Logger.getLogger(Linker.class.getName());
     private final static String CLASS_NAME = Linker.class.getCanonicalName();
 
+    /** Maximum loops to prevent hanging of PMD. See https://sourceforge.net/p/pmd/bugs/1393/ */
+    private static final int MAX_LOOPS = 100;
+
     private final DataFlowHandler dataFlowHandler;
     private List<StackObject> braceStack;
     private List<StackObject> continueBreakReturnStack;
@@ -37,7 +40,9 @@ public class Linker {
         // the last index of the sequence.
         LOGGER.fine("SequenceChecking continueBreakReturnStack elements");
         SequenceChecker sc = new SequenceChecker(braceStack);
-        while (!sc.run()) {
+        int i = 0;
+        while (!sc.run() && i < MAX_LOOPS) {
+            i++;
             if (LOGGER.isLoggable(Level.FINE)) {
                 LOGGER.fine("After sc.run - starting Sequence checking loop with firstIndex=" + sc.getFirstIndex()
                         + ", lastIndex " + sc.getLastIndex() + " with this StackList " + dump("braceStack", braceStack));

pmd-core/src/main/java/net/sourceforge/pmd/lang/dfa/pathfinder/DAAPathFinder.java

@@ -17,6 +17,9 @@ import net.sourceforge.pmd.lang.dfa.NodeType;
 public class DAAPathFinder {
     private static final int MAX_PATHS = 5000;
 
+    /** Maximum loops to prevent hanging of PMD. See https://sourceforge.net/p/pmd/bugs/1393/ */
+    private static final int MAX_LOOPS = 100;
+
     private DataFlowNode rootNode;
     private Executable shim;
     private CurrentPath currentPath = new CurrentPath();
@@ -59,7 +62,9 @@ public class DAAPathFinder {
      * Builds up the path.
      * */
     private void phase2(boolean flag) {
-        while (!currentPath.isEndNode()) { 
+        int i = 0;
+        while (!currentPath.isEndNode() && i < MAX_LOOPS) {
+            i++;
             if (currentPath.isBranch() || currentPath.isFirstDoStatement()) {
                 if (flag) {
                     addNodeToTree();
@@ -126,8 +131,9 @@ public class DAAPathFinder {
             PathElement last = (PathElement) stack.getLastLeaf().getUserObject();
             DataFlowNode inode = currentPath.getLast();
             if (inode.getChildren().size() > last.currentChild) { 
-                // for some unknown reasons last.currentChild might not be a children of inode, see bug 1597987 
-        	DataFlowNode child = inode.getChildren().get(last.currentChild);
+                // for some unknown reasons last.currentChild might not be a children of inode, see bug 1597987
+                // see https://sourceforge.net/p/pmd/bugs/606/
+                DataFlowNode child = inode.getChildren().get(last.currentChild);
                 this.currentPath.addLast(child);
             }
         } else {
@@ -313,6 +319,7 @@ public class DAAPathFinder {
         int counter = 0;
         if (treeNode.getParent() != null) {
             // for some unknown reasons the parent of treeNode might be null, see bug 1597987
+            // see https://sourceforge.net/p/pmd/bugs/606/
             int childCount = treeNode.getParent().getChildCount();
             for (int i = 0; i < childCount; i++) {
                 DefaultMutableTreeNode tNode = (DefaultMutableTreeNode) treeNode.getParent().getChildAt(i);

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/controversial/xml/DataflowAnomalyAnalysis.xml

@@ -73,5 +73,38 @@ public class Foo {
  }
 }
      ]]></code>
-    </test-code>    
+    </test-code>
+
+    <test-code>
+        <description>#1393 PMD hanging during DataflowAnomalyAnalysis</description>
+        <!-- Note: due to https://sourceforge.net/p/pmd/bugs/1383/ the 6 problems are false positives!  -->
+        <expected-problems>6</expected-problems>
+        <code><![CDATA[
+public class LoopTest {
+    public static void main(String[] args) {
+        int[] a = {1,2,3};
+        int[] b = {4,5,6};
+        int[] c = {7,8,9};
+        for (int i : a) {
+            if (i == 0) {
+                break;
+            } else {
+                boolean fail = false;
+                for (int j : b) {
+                    boolean match = false;
+                    for (int k : c) {
+                        if (k == 42) {
+                            match = true;
+                        }
+                    }
+                    if (!match) {
+                        fail = true;
+                    }
+                }
+            }
+        }
+    }
+}
+        ]]></code>
+    </test-code>
 </test-data>

src/site/markdown/overview/changelog.md

@@ -18,6 +18,7 @@
 *   [#1384](https://sourceforge.net/p/pmd/bugs/1384/): NullPointerException in ConsecutiveLiteralAppendsRule
 *   [#1388](https://sourceforge.net/p/pmd/bugs/1388/): ConstructorCallsOverridableMethodRule doesn't work with params?
 *   [#1392](https://sourceforge.net/p/pmd/bugs/1392/): SimplifyStartsWith false-negative
+*   [#1393](https://sourceforge.net/p/pmd/bugs/1393/): PMD hanging during DataflowAnomalyAnalysis
 *   [#1394](https://sourceforge.net/p/pmd/bugs/1394/): dogfood.xml - Unable to exclude rules [UncommentedEmptyMethod]
 *   [#1395](https://sourceforge.net/p/pmd/bugs/1395/): UnusedPrivateMethod false positive for array element method call
 *   [#1396](https://sourceforge.net/p/pmd/bugs/1396/): PrematureDeclaration lambda false positive