Java: Diff-informed PredictableSeed.ql

Author: jbj

java/ql/lib/semmle/code/java/security/RandomQuery.qll

@@ -37,6 +37,18 @@ private module PredictableSeedFlowConfig implements DataFlow::ConfigSig {
   predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
     predictableCalcStep(node1.asExpr(), node2.asExpr())
   }
+
+  predicate observeDiffInformedIncrementalMode() { any() }
+
+  Location getASelectedSinkLocation(DataFlow::Node sink) {
+    // This predicate matches `PredictableSeed.ql`, which is the only place
+    // where `PredictableSeedFlowConfig` is used.
+    exists(GetRandomData da, VarRead use |
+      result = da.getLocation() and
+      da.getQualifier() = use and
+      isSeeding(sink.asExpr(), use)
+    )
+  }
 }
 
 private module PredictableSeedFlow = DataFlow::Global<PredictableSeedFlowConfig>;