Replace string kind with boolean preservesValue

Author: hvitved

ql/lib/codeql/ruby/dataflow/FlowSummary.qll

@@ -96,7 +96,7 @@ abstract class SummarizedCallable extends LibraryCallable {
    * but uses an external (string) representation of the input and output stacks.
    */
   pragma[nomagic]
-  predicate propagatesFlowExt(string input, string output, string kind) { none() }
+  predicate propagatesFlowExt(string input, string output, boolean preservesValue) { none() }
 
   /**
    * Holds if values stored inside `content` are cleared on objects passed as

ql/lib/codeql/ruby/dataflow/internal/FlowSummaryImplSpecific.qll

@@ -45,9 +45,10 @@ DataFlowType getCallbackReturnType(DataFlowType t, ReturnKind rk) { any() }
  * `input`, output specification `output`, and kind `kind`.
  */
 predicate summaryElement(DataFlowCallable c, string input, string output, string kind) {
-  exists(FlowSummary::SummarizedCallable sc |
-    sc.propagatesFlowExt(input, output, kind) and
-    c.asLibraryCallable() = sc
+  exists(FlowSummary::SummarizedCallable sc, boolean preservesValue |
+    sc.propagatesFlowExt(input, output, preservesValue) and
+    c.asLibraryCallable() = sc and
+    if preservesValue = true then kind = "value" else kind = "taint"
   )
 }
 

ql/test/library-tests/dataflow/summaries/Summaries.ql

@@ -18,10 +18,10 @@ private class SummarizedCallableIdentity extends SummarizedCallable {
 
   override MethodCall getACall() { result.getMethodName() = this }
 
-  override predicate propagatesFlowExt(string input, string output, string kind) {
+  override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
     input = "Argument[0]" and
     output = "ReturnValue" and
-    kind = "value"
+    preservesValue = true
   }
 }
 
@@ -30,14 +30,14 @@ private class SummarizedCallableApplyBlock extends SummarizedCallable {
 
   override MethodCall getACall() { result.getMethodName() = this }
 
-  override predicate propagatesFlowExt(string input, string output, string kind) {
+  override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
     input = "Argument[0]" and
     output = "Parameter[0] of BlockArgument" and
-    kind = "value"
+    preservesValue = true
     or
     input = "ReturnValue of BlockArgument" and
     output = "ReturnValue" and
-    kind = "value"
+    preservesValue = true
   }
 }
 
@@ -46,14 +46,14 @@ private class SummarizedCallableApplyLambda extends SummarizedCallable {
 
   override MethodCall getACall() { result.getMethodName() = this }
 
-  override predicate propagatesFlowExt(string input, string output, string kind) {
+  override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
     input = "Argument[1]" and
     output = "Parameter[0] of Argument[0]" and
-    kind = "value"
+    preservesValue = true
     or
     input = "ReturnValue of Argument[0]" and
     output = "ReturnValue" and
-    kind = "value"
+    preservesValue = true
   }
 }