Python: Cleanup, docs, and an extra test case

tausbn · tausbn · commit 2d3e23ebb041 · 2020-09-16T14:46:04.000+02:00
diff --git a/python/ql/src/experimental/dataflow/internal/DataFlowPrivate.qll b/python/ql/src/experimental/dataflow/internal/DataFlowPrivate.qll
@@ -240,6 +240,7 @@ class DataFlowClassValue extends DataFlowCallable, TClassValue {
   override string getName() { result = c.getName() }
 }
 
+/** A class representing the scope in which a `ModuleVariableNode` appears. */
 class DataFlowModuleScope extends DataFlowCallable, TModule {
   Module mod;
 
diff --git a/python/ql/src/experimental/dataflow/internal/DataFlowPublic.qll b/python/ql/src/experimental/dataflow/internal/DataFlowPublic.qll
@@ -150,6 +150,7 @@ class ParameterNode extends EssaNode {
   override DataFlowCallable getEnclosingCallable() { this.isParameterOf(result, _) }
 }
 
+/** A data flow node corresponding to a module-level (global) variable that is accessed outside of the module scope. */
 class ModuleVariableNode extends Node, TModuleVariableNode {
   Module mod;
   GlobalVariable var;
@@ -176,10 +177,8 @@ class ModuleVariableNode extends Node, TModuleVariableNode {
   }
 
   /** Gets an `EssaNode` that corresponds to an assignment of this global variable. */
-  Node getAWrite() {
-    exists(DefinitionNode defn |
-      result.asVar().getDefinition().(EssaNodeDefinition).definedBy(var, defn)
-    )
+  EssaNode getAWrite() {
+    result.asVar().getDefinition().(EssaNodeDefinition).definedBy(var, any(DefinitionNode defn))
   }
 
   override DataFlowCallable getEnclosingCallable() { result.(DataFlowModuleScope).getScope() = mod }
diff --git a/python/ql/test/experimental/dataflow/global-flow/test.py b/python/ql/test/experimental/dataflow/global-flow/test.py
@@ -37,6 +37,12 @@
 else:
     g_mult = [300] # $writes=g_mult
 
+# Potential reassignment
+
+g_mult2 = [400] # $writes=g_mult2
+if unknown_module.attr:
+    g_mult2 = [500] # $writes=g_mult2
+
 def global_access():
     l = 5
     print(g) # $reads=g
@@ -45,6 +51,7 @@ def global_access():
     print(g_mod) # $reads=g_mod
     print(g_ins) # $reads=g_ins
     print(g_mult) # $reads=g_mult
+    print(g_mult2) # $reads=g_mult2
 
 def print_g_mod(): # $writes=print_g_mod
     print(g_mod) # $reads=g_mod

Original file line number	Diff line number	Diff line change
`@@ -240,6 +240,7 @@ class DataFlowClassValue extends DataFlowCallable, TClassValue {`
`240`	`240`	`override string getName() { result = c.getName() }`
`241`	`241`	`}`
`242`	`242`
	`243`	+/** A class representing the scope in which a `ModuleVariableNode` appears. */
`243`	`244`	`class DataFlowModuleScope extends DataFlowCallable, TModule {`
`244`	`245`	`Module mod;`
`245`	`246`
Original file line number	Diff line number	Diff line change
`@@ -150,6 +150,7 @@ class ParameterNode extends EssaNode {`
`150`	`150`	`override DataFlowCallable getEnclosingCallable() { this.isParameterOf(result, _) }`
`151`	`151`	`}`
`152`	`152`
	`153`	`+/** A data flow node corresponding to a module-level (global) variable that is accessed outside of the module scope. */`
`153`	`154`	`class ModuleVariableNode extends Node, TModuleVariableNode {`
`154`	`155`	`Module mod;`
`155`	`156`	`GlobalVariable var;`
`@@ -176,10 +177,8 @@ class ModuleVariableNode extends Node, TModuleVariableNode {`
`176`	`177`	`}`
`177`	`178`
`178`	`179`	/** Gets an `EssaNode` that corresponds to an assignment of this global variable. */
`179`		`- Node getAWrite() {`
`180`		`- exists(DefinitionNode defn \|`
`181`		`- result.asVar().getDefinition().(EssaNodeDefinition).definedBy(var, defn)`
`182`		`- )`
	`180`	`+ EssaNode getAWrite() {`
	`181`	`+ result.asVar().getDefinition().(EssaNodeDefinition).definedBy(var, any(DefinitionNode defn))`
`183`	`182`	`}`
`184`	`183`
`185`	`184`	`override DataFlowCallable getEnclosingCallable() { result.(DataFlowModuleScope).getScope() = mod }`