Python: Model builtin open function better

Author: RasmusWL

python/ql/src/semmle/python/frameworks/Stdlib.qll

@@ -651,7 +651,7 @@ private module Stdlib {
    * WARNING: Only holds for a few predefined attributes.
    */
   private DataFlow::Node builtins_attr(DataFlow::TypeTracker t, string attr_name) {
-    attr_name in ["exec", "eval", "compile"] and
+    attr_name in ["exec", "eval", "compile", "open"] and
     (
       t.start() and
       result = DataFlow::importNode(["builtins", "__builtin__"] + "." + attr_name)
@@ -729,6 +729,20 @@ private module Stdlib {
     }
   }
 
+  /**
+   * A call to the builtin `open` function.
+   * See https://docs.python.org/3/library/functions.html#open
+   */
+  private class OpenCall extends FileSystemAccess::Range, DataFlow::CfgNode {
+    override CallNode node;
+
+    OpenCall() { node.getFunction() = builtins_attr("open").asCfgNode() }
+
+    override DataFlow::Node getAPathArgument() {
+      result.asCfgNode() in [node.getArg(0), node.getArgByName("file")]
+    }
+  }
+
   /**
    * An exec statement (only Python 2).
    * Se ehttps://docs.python.org/2/reference/simple_stmts.html#the-exec-statement.
@@ -743,20 +757,6 @@ private module Stdlib {
     override DataFlow::Node getCode() { result = this }
   }
 
-  /**
-   * A call to the builtin `open` function.
-   * See https://docs.python.org/3/library/functions.html#open
-   */
-  private class OpenCall extends FileSystemAccess::Range, DataFlow::CfgNode {
-    override CallNode node;
-
-    OpenCall() { node.getFunction().(NameNode).getId() = "open" }
-
-    override DataFlow::Node getAPathArgument() {
-      result.asCfgNode() in [node.getArg(0), node.getArgByName("file")]
-    }
-  }
-
   // ---------------------------------------------------------------------------
   // base64
   // ---------------------------------------------------------------------------

python/ql/test/experimental/library-tests/frameworks/stdlib/FileSystemAccess.py

@@ -6,12 +6,12 @@
 
 o = open
 
-o("filepath")  # $ MISSING: getAPathArgument="filepath"
-o(file="filepath")  # $ MISSING: getAPathArgument="filepath"
+o("filepath")  # $getAPathArgument="filepath"
+o(file="filepath")  # $getAPathArgument="filepath"
 
 
-builtins.open("filepath")  # $ MISSING: getAPathArgument="filepath"
-builtins.open(file="filepath")  # $ MISSING: getAPathArgument="filepath"
+builtins.open("filepath")  # $getAPathArgument="filepath"
+builtins.open(file="filepath")  # $getAPathArgument="filepath"
 
 
 io.open("filepath")  # $ MISSING: getAPathArgument="filepath"