C#: Update dataflow consistency queries to cater for non unique post and pre unique update notes for conditional branches.

michaelnebel · michaelnebel · commit 2d0a377b7a6f · 2022-09-28T14:35:09.000+02:00
diff --git a/csharp/ql/consistency-queries/DataFlowConsistency.ql b/csharp/ql/consistency-queries/DataFlowConsistency.ql
@@ -35,13 +35,7 @@ private class MyConsistencyConfiguration extends ConsistencyConfiguration {
   override predicate argHasPostUpdateExclude(ArgumentNode n) {
     n instanceof SummaryNode
     or
-    n.asExpr().(Expr).stripCasts().getType() =
-      any(Type t |
-        not t instanceof RefType and
-        not t = any(TypeParameter tp | not tp.isValueType())
-        or
-        t instanceof NullType
-      )
+    not exists(getAPostUpdateNodeForArg(n.asExpr()))
     or
     n instanceof ImplicitCapturedArgumentNode
     or
@@ -50,5 +44,21 @@ private class MyConsistencyConfiguration extends ConsistencyConfiguration {
     n.asExpr() instanceof CIL::Expr
   }
 
+  override predicate postHasUniquePreExclude(PostUpdateNode n) {
+    exists(ControlFlow::Nodes::ExprNode e, ControlFlow::Nodes::ExprNode arg |
+      e = getAPostUpdateNodeForArg(arg.getExpr()) and
+      e != arg and
+      n = TExprPostUpdateNode(e)
+    )
+  }
+
+  override predicate uniquePostUpdateExclude(Node n) {
+    exists(ControlFlow::Nodes::ExprNode e, ControlFlow::Nodes::ExprNode arg |
+      e = getAPostUpdateNodeForArg(arg.getExpr()) and
+      e != arg and
+      n.asExpr() = arg.getExpr()
+    )
+  }
+
   override predicate reverseReadExclude(Node n) { n.asExpr() = any(AwaitExpr ae).getExpr() }
 }
diff --git a/csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll b/csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
@@ -197,7 +197,7 @@ private predicate relevantArgumentType(ControlFlow::Nodes::ExprNode cfn) {
 }
 
 /** Gets a node for which to construct a post-update node for argument `arg`. */
-private ControlFlow::Nodes::ExprNode getAPostUpdateNodeForArg(Argument arg) {
+ControlFlow::Nodes::ExprNode getAPostUpdateNodeForArg(Argument arg) {
   result = getALastEvalNode*(arg.getAControlFlowNode()) and
   relevantArgumentType(result) and
   not exists(getALastEvalNode(result))

Original file line number	Diff line number	Diff line change
`@@ -197,7 +197,7 @@ private predicate relevantArgumentType(ControlFlow::Nodes::ExprNode cfn) {`
`197`	`197`	`}`
`198`	`198`
`199`	`199`	/** Gets a node for which to construct a post-update node for argument `arg`. */
`200`		`-private ControlFlow::Nodes::ExprNode getAPostUpdateNodeForArg(Argument arg) {`
	`200`	`+ControlFlow::Nodes::ExprNode getAPostUpdateNodeForArg(Argument arg) {`
`201`	`201`	`result = getALastEvalNode*(arg.getAControlFlowNode()) and`
`202`	`202`	`relevantArgumentType(result) and`
`203`	`203`	`not exists(getALastEvalNode(result))`