JS: infer this to be module.exports in node modules

Author: esbena

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

@@ -45,6 +45,19 @@ private class AnalyzedThisInBoundFunction extends AnalyzedThisExpr {
   }
 }
 
+/**
+ * Flow analysis for `this` expressions in node modules.
+ *
+ * These expressions are assumed to refer to the `module.exports` object.
+ */
+private class AnalyzedThisAsModuleExports extends DataFlow::AnalyzedNode, DataFlow::ThisNode {
+  NodeModule m;
+
+  AnalyzedThisAsModuleExports() { m = getBindingContainer() }
+
+  override AbstractValue getALocalValue() { result = TAbstractExportsObject(m) }
+}
+
 /**
  * Flow analysis for `this` expressions inside a function that is instantiated.
  *

javascript/ql/test/library-tests/ThisExpr/ThisExpr_analyzed.expected

@@ -1,4 +1,5 @@
 | module-exports.js:3:1:3:4 | this | file://:0:0:0:0 | indefinite value (call) |
+| module-exports.js:3:1:3:4 | this | module-exports.js:1:1:8:0 | exports object of module module-exports |
 | module-exports.js:4:28:4:31 | this | file://:0:0:0:0 | indefinite value (call) |
 | module-exports.js:4:28:4:31 | this | module-exports.js:1:1:8:0 | exports object of module module-exports |
 | module-exports.js:4:28:4:31 | this | module-exports.js:4:15:4:34 | instance of anonymous function |
@@ -7,7 +8,9 @@
 | module-exports.js:5:35:5:38 | this | module-exports.js:1:1:8:0 | exports object of module module-exports |
 | module-exports.js:5:35:5:38 | this | module-exports.js:5:22:5:41 | instance of anonymous function |
 | module-exports.js:6:21:6:24 | this | file://:0:0:0:0 | indefinite value (call) |
+| module-exports.js:6:21:6:24 | this | module-exports.js:1:1:8:0 | exports object of module module-exports |
 | module-exports.js:7:28:7:31 | this | file://:0:0:0:0 | indefinite value (call) |
+| module-exports.js:7:28:7:31 | this | module-exports.js:1:1:8:0 | exports object of module module-exports |
 | tst.js:4:9:4:12 | this | file://:0:0:0:0 | indefinite value (call) |
 | tst.js:4:9:4:12 | this | tst.js:1:1:11:1 | instance of class C_normal |
 | tst.js:8:15:8:18 | this | file://:0:0:0:0 | indefinite value (call) |