Ruby: use Dataflow for Pathname instead of TypeTracking

Author: aibaars

ruby/ql/lib/codeql/ruby/frameworks/stdlib/Pathname.qll

@@ -3,11 +3,9 @@
 private import codeql.ruby.AST
 private import codeql.ruby.ApiGraphs
 private import codeql.ruby.Concepts
-private import codeql.ruby.DataFlow
 private import codeql.ruby.dataflow.FlowSummary
-private import codeql.ruby.dataflow.internal.DataFlowDispatch
 private import codeql.ruby.frameworks.data.ModelsAsData
-private import codeql.ruby.typetracking.TypeTracker
+private import codeql.ruby.dataflow.internal.DataFlowImplForLibraries
 
 /**
  * Modeling of the `Pathname` class from the Ruby standard library.
@@ -29,34 +27,34 @@ module Pathname {
    * Every `PathnameInstance` is considered to be a `FileNameSource`.
    */
   class PathnameInstance extends FileNameSource, DataFlow::Node {
-    PathnameInstance() { this = pathnameInstance() }
+    PathnameInstance() { any(PathnameConfiguration c).hasFlowTo(this) }
   }
 
-  private DataFlow::LocalSourceNode pathnameInstance(TypeTracker t) {
-    t.start() and
-    (
+  private class PathnameConfiguration extends Configuration {
+    PathnameConfiguration() { this = "PathnameConfiguration" }
+
+    override predicate isSource(DataFlow::Node source) {
       // A call to `Pathname.new`.
-      result = API::getTopLevelMember("Pathname").getAnInstantiation()
+      source = API::getTopLevelMember("Pathname").getAnInstantiation()
       or
       // Class methods on `Pathname` that return a new `Pathname`.
-      result = API::getTopLevelMember("Pathname").getAMethodCall(["getwd", "pwd",])
-      or
-      // Instance methods on `Pathname` that return a new `Pathname`.
-      exists(DataFlow::CallNode c | result = c |
-        c.getReceiver() = pathnameInstance() and
+      source = API::getTopLevelMember("Pathname").getAMethodCall(["getwd", "pwd",])
+    }
+
+    override predicate isSink(DataFlow::Node sink) { any() }
+
+    override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
+      exists(DataFlow::CallNode c | node2 = c |
+        c.getReceiver() = node1 and
         c.getMethodName() =
           [
             "+", "/", "basename", "cleanpath", "expand_path", "join", "realpath",
             "relative_path_from", "sub", "sub_ext", "to_path"
           ]
       )
-    )
-    or
-    exists(TypeTracker t2 | result = pathnameInstance(t2).track(t2, t))
+    }
   }
 
-  private DataFlow::Node pathnameInstance() { pathnameInstance(TypeTracker::end()).flowsTo(result) }
-
   /** A call where the receiver is a `Pathname`. */
   class PathnameCall extends DataFlow::CallNode {
     PathnameCall() { this.getReceiver() instanceof PathnameInstance }

ruby/ql/test/library-tests/frameworks/pathname/Pathname.expected

@@ -57,6 +57,16 @@ pathnameInstances
 | Pathname.rb:39:12:39:19 | foo_path |
 | Pathname.rb:41:1:41:3 | p08 |
 | Pathname.rb:42:1:42:3 | p01 |
+| file://:0:0:0:0 | parameter position 0 of + |
+| file://:0:0:0:0 | parameter self of + |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[cleanpath] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[expand_path] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[realpath] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[relative_path_from] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[sub_ext] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[to_path] |
+| file://:0:0:0:0 | parameter self of sub |
+| file://:0:0:0:0 | parameter self of to_s |
 fileSystemAccesses
 | Pathname.rb:26:12:26:24 | call to open | Pathname.rb:26:12:26:19 | foo_path |
 | Pathname.rb:28:11:28:22 | call to opendir | Pathname.rb:28:11:28:14 | pwd1 |
@@ -123,6 +133,16 @@ fileNameSources
 | Pathname.rb:39:12:39:19 | foo_path |
 | Pathname.rb:41:1:41:3 | p08 |
 | Pathname.rb:42:1:42:3 | p01 |
+| file://:0:0:0:0 | parameter position 0 of + |
+| file://:0:0:0:0 | parameter self of + |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[cleanpath] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[expand_path] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[realpath] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[relative_path_from] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[sub_ext] |
+| file://:0:0:0:0 | parameter self of ;Pathname;Method[to_path] |
+| file://:0:0:0:0 | parameter self of sub |
+| file://:0:0:0:0 | parameter self of to_s |
 fileSystemReadAccesses
 | Pathname.rb:32:12:32:24 | call to read | Pathname.rb:32:12:32:24 | call to read |
 fileSystemWriteAccesses