JavaScript: Simplify a few helper predicates.

javascript/ql/src/semmle/javascript/dataflow/Configuration.qll

@@ -422,19 +422,19 @@ private predicate basicFlowStep(DataFlow::Node pred, DataFlow::Node succ, PathSu
    or
    // Flow through properties of objects
    propertyFlowStep(pred, succ) and
-   summary = PathSummary::level(true)
+   summary = PathSummary::level()
    or
    // Flow through global variables
    globalFlowStep(pred, succ) and
-   summary = PathSummary::level(true)
+   summary = PathSummary::level()
    or
    // Flow into function
    callStep(pred, succ) and
-   summary = PathSummary::call(true)
+   summary = PathSummary::call()
    or
    // Flow out of function
    returnStep(pred, succ) and
-   summary = PathSummary::return(true)
+   summary = PathSummary::return()
   )
 }
 
@@ -540,7 +540,7 @@ private predicate reachableFromInput(Function f, DataFlow::Node invk,
                                      DataFlow::Node input, DataFlow::Node nd,
                                      DataFlow::Configuration cfg, PathSummary summary) {
   callInputStep(f, invk, input, nd, cfg) and
-  summary = PathSummary::empty()
+  summary = PathSummary::level()
   or
   exists (DataFlow::Node mid, PathSummary oldSummary, PathSummary newSummary |
     reachableFromInput(f, invk, input, mid, cfg, oldSummary) and
@@ -571,7 +571,7 @@ private predicate flowThroughCall(DataFlow::Node input, DataFlow::Node invk,
 private predicate storeStep(DataFlow::Node pred, DataFlow::SourceNode succ, string prop,
                             DataFlow::Configuration cfg, PathSummary summary) {
   basicStoreStep(pred, succ, prop) and
-  summary = PathSummary::level(true)
+  summary = PathSummary::level()
   or
   exists (Function f, DataFlow::Node mid, DataFlow::SourceNode base |
     // `f` stores its parameter `pred` in property `prop` of a value that it returns,
@@ -677,7 +677,7 @@ private predicate onPath(DataFlow::Node nd, DataFlow::Configuration cfg,
   reachableFromSource(nd, cfg, summary1) and
   isSink(nd, cfg, summary1.getEndLabel()) and
   not cfg.isBarrier(nd) and
-  summary2 = PathSummary::empty()
+  summary2 = PathSummary::level()
   or
   exists (DataFlow::Node mid, PathSummary newSummary, PathSummary oldSummary |
     onPath(mid, cfg, _, oldSummary) and

javascript/ql/src/semmle/javascript/dataflow/TrackedNodes.qll

@@ -70,23 +70,23 @@ private module NodeTracking {
     (
      // Local flow
      localFlowStep(pred, succ) and
-     summary = PathSummary::level(true)
+     summary = PathSummary::level()
      or
      // Flow through properties of objects
      propertyFlowStep(pred, succ) and
-     summary = PathSummary::level(true)
+     summary = PathSummary::level()
      or
      // Flow through global variables
      globalFlowStep(pred, succ) and
-     summary = PathSummary::level(true)
+     summary = PathSummary::level()
      or
      // Flow into function
      callStep(pred, succ) and
-     summary = PathSummary::call(true)
+     summary = PathSummary::call()
      or
      // Flow out of function
      returnStep(pred, succ) and
-     summary = PathSummary::return(true)
+     summary = PathSummary::return()
     )
   }
 
@@ -138,7 +138,7 @@ private module NodeTracking {
                                        DataFlow::Node input, DataFlow::Node nd,
                                        PathSummary summary) {
     callInputStep(f, invk, input, nd) and
-    summary = PathSummary::empty()
+    summary = PathSummary::level()
     or
     exists (DataFlow::Node mid, PathSummary oldSummary, PathSummary newSummary |
       reachableFromInput(f, invk, input, mid, oldSummary) and
@@ -165,7 +165,7 @@ private module NodeTracking {
   private predicate storeStep(DataFlow::Node pred, DataFlow::SourceNode succ, string prop,
                               PathSummary summary) {
     basicStoreStep(pred, succ, prop) and
-    summary = PathSummary::level(true)
+    summary = PathSummary::level()
     or
     exists (Function f, DataFlow::Node mid, DataFlow::SourceNode base |
       // `f` stores its parameter `pred` in property `prop` of a value that it returns,
@@ -214,7 +214,7 @@ private module NodeTracking {
     // Flow through a function that returns a value that depends on one of its arguments
     // or a captured variable
     flowThroughCall(pred, succ) and
-    summary = PathSummary::level(true)
+    summary = PathSummary::level()
     or
     // Flow through a property write/read pair
     flowThroughProperty(pred, succ, summary)
@@ -226,7 +226,7 @@ private module NodeTracking {
    */
   predicate flowsTo(TrackedNode source, DataFlow::Node nd, PathSummary summary) {
     source = nd and
-    summary = PathSummary::empty()
+    summary = PathSummary::level()
     or
     exists (DataFlow::Node pred, PathSummary oldSummary, PathSummary newSummary |
       flowsTo(source, pred, oldSummary) and

javascript/ql/src/semmle/javascript/dataflow/internal/FlowSteps.qll

@@ -323,47 +323,29 @@ class PathSummary extends TPathSummary {
 
 module PathSummary {
   /**
-   * Gets a summary describing an empty path.
+   * Gets a summary describing a path without any calls or returns.
    */
-  PathSummary empty() {
-    result = level(true)
-  }
-
-  private PathSummary mkPathSummary(boolean hasCall, boolean hasReturn, Boolean valuePreserving) {
-    exists (FlowLabel start, FlowLabel end |
-      if valuePreserving = false then
-        end = FlowLabel::taint()
-      else
-        start = end
-    |
-      result = MkPathSummary(hasCall, hasReturn, start, end)
+  PathSummary level() {
+    exists (FlowLabel lbl |
+      result = MkPathSummary(false, false, lbl, lbl)
     )
   }
 
-  /**
-   * Gets a summary describing a path without any calls or returns.
-   * `valuePreserving` indicates whether the path preserves the value of its
-   * start node or only its taintedness.
-   */
-  PathSummary level(Boolean valuePreserving) {
-    result = mkPathSummary(false, false, valuePreserving)
-  }
-
   /**
    * Gets a summary describing a path with one or more calls, but no returns.
-   * `valuePreserving` indicates whether the path preserves the value of its
-   * start node or only its taintedness.
    */
-  PathSummary call(Boolean valuePreserving) {
-    result = mkPathSummary(false, true, valuePreserving)
+  PathSummary call() {
+    exists (FlowLabel lbl |
+      result = MkPathSummary(false, true, lbl, lbl)
+    )
   }
 
   /**
    * Gets a summary describing a path with one or more returns, but no calls.
-   * `valuePreserving` indicates whether the path preserves the value of its
-   * start node or only its taintedness.
    */
-  PathSummary return(Boolean valuePreserving) {
-    result = mkPathSummary(true, false, valuePreserving)
+  PathSummary return() {
+    exists (FlowLabel lbl |
+      result = MkPathSummary(true, false, lbl, lbl)
+    )
   }
 }