python: make content sets an IPA type

this should have no semantic consequences

Author: yoff

python/ql/lib/semmle/python/dataflow/new/TypeTracking.qll

@@ -48,7 +48,7 @@ class TypeTracker extends Impl::TypeTracker {
    */
   predicate startInAttr(string attrName) {
     exists(DataFlowPublic::AttributeContent content | content.getAttribute() = attrName |
-      this.startInContent(content)
+      this.startInContent(DataFlowPublic::TSingletonContent(content))
     )
   }
 
@@ -58,8 +58,10 @@ class TypeTracker extends Impl::TypeTracker {
    * Gets the attribute associated with this type tracker.
    */
   string getAttr() {
-    if this.getContent().asSome() instanceof DataFlowPublic::AttributeContent
-    then result = this.getContent().asSome().(DataFlowPublic::AttributeContent).getAttribute()
+    if this.getContent().asSome().asSingleton() instanceof DataFlowPublic::AttributeContent
+    then
+      result =
+        this.getContent().asSome().asSingleton().(DataFlowPublic::AttributeContent).getAttribute()
     else result = ""
   }
 }

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPrivate.qll

@@ -679,13 +679,13 @@ predicate jumpStepNotSharedWithTypeTracker(Node nodeFrom, Node nodeTo) {
  * no reason to include steps for list content right now.
  */
 predicate storeStepCommon(Node nodeFrom, ContentSet c, Node nodeTo) {
-  tupleStoreStep(nodeFrom, c, nodeTo)
+  tupleStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  dictStoreStep(nodeFrom, c, nodeTo)
+  dictStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  moreDictStoreSteps(nodeFrom, c, nodeTo)
+  moreDictStoreSteps(nodeFrom, c.asSingleton(), nodeTo)
   or
-  iterableUnpackingStoreStep(nodeFrom, c, nodeTo)
+  iterableUnpackingStoreStep(nodeFrom, c.asSingleton(), nodeTo)
 }
 
 /**
@@ -695,26 +695,26 @@ predicate storeStepCommon(Node nodeFrom, ContentSet c, Node nodeTo) {
 predicate storeStep(Node nodeFrom, ContentSet c, Node nodeTo) {
   storeStepCommon(nodeFrom, c, nodeTo)
   or
-  listStoreStep(nodeFrom, c, nodeTo)
+  listStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  setStoreStep(nodeFrom, c, nodeTo)
+  setStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  attributeStoreStep(nodeFrom, c, nodeTo)
+  attributeStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  matchStoreStep(nodeFrom, c, nodeTo)
+  matchStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  any(Orm::AdditionalOrmSteps es).storeStep(nodeFrom, c, nodeTo)
+  any(Orm::AdditionalOrmSteps es).storeStep(nodeFrom, c.asSingleton(), nodeTo)
   or
   FlowSummaryImpl::Private::Steps::summaryStoreStep(nodeFrom.(FlowSummaryNode).getSummaryNode(), c,
     nodeTo.(FlowSummaryNode).getSummaryNode())
   or
-  synthStarArgsElementParameterNodeStoreStep(nodeFrom, c, nodeTo)
+  synthStarArgsElementParameterNodeStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  synthDictSplatArgumentNodeStoreStep(nodeFrom, c, nodeTo)
+  synthDictSplatArgumentNodeStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  yieldStoreStep(nodeFrom, c, nodeTo)
+  yieldStoreStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  VariableCapture::storeStep(nodeFrom, c, nodeTo)
+  VariableCapture::storeStep(nodeFrom, c.asSingleton(), nodeTo)
 }
 
 /**
@@ -911,9 +911,9 @@ predicate attributeStoreStep(Node nodeFrom, AttributeContent c, Node nodeTo) {
  * Subset of `readStep` that should be shared with type-tracking.
  */
 predicate readStepCommon(Node nodeFrom, ContentSet c, Node nodeTo) {
-  subscriptReadStep(nodeFrom, c, nodeTo)
+  subscriptReadStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  iterableUnpackingReadStep(nodeFrom, c, nodeTo)
+  iterableUnpackingReadStep(nodeFrom, c.asSingleton(), nodeTo)
 }
 
 /**
@@ -922,18 +922,18 @@ predicate readStepCommon(Node nodeFrom, ContentSet c, Node nodeTo) {
 predicate readStep(Node nodeFrom, ContentSet c, Node nodeTo) {
   readStepCommon(nodeFrom, c, nodeTo)
   or
-  matchReadStep(nodeFrom, c, nodeTo)
+  matchReadStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  forReadStep(nodeFrom, c, nodeTo)
+  forReadStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  attributeReadStep(nodeFrom, c, nodeTo)
+  attributeReadStep(nodeFrom, c.asSingleton(), nodeTo)
   or
   FlowSummaryImpl::Private::Steps::summaryReadStep(nodeFrom.(FlowSummaryNode).getSummaryNode(), c,
     nodeTo.(FlowSummaryNode).getSummaryNode())
   or
-  synthDictSplatParameterNodeReadStep(nodeFrom, c, nodeTo)
+  synthDictSplatParameterNodeReadStep(nodeFrom, c.asSingleton(), nodeTo)
   or
-  VariableCapture::readStep(nodeFrom, c, nodeTo)
+  VariableCapture::readStep(nodeFrom, c.asSingleton(), nodeTo)
 }
 
 /** Data flows from a sequence to a subscript of the sequence. */
@@ -995,17 +995,17 @@ predicate attributeReadStep(Node nodeFrom, AttributeContent c, AttrRead nodeTo)
  * in `x.f = newValue`.
  */
 predicate clearsContent(Node n, ContentSet c) {
-  matchClearStep(n, c)
+  matchClearStep(n, c.asSingleton())
   or
-  attributeClearStep(n, c)
+  attributeClearStep(n, c.asSingleton())
   or
-  dictClearStep(n, c)
+  dictClearStep(n, c.asSingleton())
   or
   FlowSummaryImpl::Private::Steps::summaryClearsContent(n.(FlowSummaryNode).getSummaryNode(), c)
   or
-  dictSplatParameterNodeClearStep(n, c)
+  dictSplatParameterNodeClearStep(n, c.asSingleton())
   or
-  VariableCapture::clearsContent(n, c)
+  VariableCapture::clearsContent(n, c.asSingleton())
 }
 
 /**

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPublic.qll

@@ -769,19 +769,27 @@ class CapturedVariableContent extends Content, TCapturedVariableContent {
   override string getMaDRepresentation() { none() }
 }
 
+newtype TContentSet = TSingletonContent(Content c)
+
 /**
  * An entity that represents a set of `Content`s.
  *
  * The set may be interpreted differently depending on whether it is
  * stored into (`getAStoreContent`) or read from (`getAReadContent`).
  */
-class ContentSet instanceof Content {
+class ContentSet extends TContentSet {
+  /** Holds if this content set is the singleton `{c}`. */
+  predicate isSingleton(Content c) { this = TSingletonContent(c) }
+
+  /** Gets the singleton `Content` underlying this `ContentSet`, if any. */
+  Content asSingleton() { this.isSingleton(result) }
+
   /** Gets a content that may be stored into when storing into this set. */
-  Content getAStoreContent() { result = this }
+  Content getAStoreContent() { this.isSingleton(result) }
 
   /** Gets a content that may be read from when reading from this set. */
-  Content getAReadContent() { result = this }
+  Content getAReadContent() { this.isSingleton(result) }
 
   /** Gets a textual representation of this content set. */
-  string toString() { result = super.toString() }
+  string toString() { result = any(Content c | this.isSingleton(c)).toString() }
 }

python/ql/lib/semmle/python/dataflow/new/internal/FlowSummaryImpl.qll

@@ -62,21 +62,23 @@ module Input implements InputSig<Location, DataFlowImplSpecific::PythonDataFlow>
   }
 
   string encodeContent(ContentSet cs, string arg) {
-    cs = TListElementContent() and result = "ListElement" and arg = ""
-    or
-    cs = TSetElementContent() and result = "SetElement" and arg = ""
-    or
-    exists(int index |
-      cs = TTupleElementContent(index) and result = "TupleElement" and arg = index.toString()
-    )
-    or
-    exists(string key |
-      cs = TDictionaryElementContent(key) and result = "DictionaryElement" and arg = key
+    exists(Content c | cs.isSingleton(c) |
+      c = TListElementContent() and result = "ListElement" and arg = ""
+      or
+      c = TSetElementContent() and result = "SetElement" and arg = ""
+      or
+      exists(int index |
+        c = TTupleElementContent(index) and result = "TupleElement" and arg = index.toString()
+      )
+      or
+      exists(string key |
+        c = TDictionaryElementContent(key) and result = "DictionaryElement" and arg = key
+      )
+      or
+      c = TDictionaryElementAnyContent() and result = "DictionaryElementAny" and arg = ""
+      or
+      exists(string attr | c = TAttributeContent(attr) and result = "Attribute" and arg = attr)
     )
-    or
-    cs = TDictionaryElementAnyContent() and result = "DictionaryElementAny" and arg = ""
-    or
-    exists(string attr | cs = TAttributeContent(attr) and result = "Attribute" and arg = attr)
   }
 
   bindingset[token]
@@ -132,27 +134,35 @@ module Private {
     predicate withContent = SC::withContent/1;
 
     /** Gets a summary component that represents a list element. */
-    SummaryComponent listElement() { result = content(any(ListElementContent c)) }
+    SummaryComponent listElement() { result = content(TSingletonContent(TListElementContent())) }
 
     /** Gets a summary component that represents a set element. */
-    SummaryComponent setElement() { result = content(any(SetElementContent c)) }
+    SummaryComponent setElement() { result = content(TSingletonContent(TSetElementContent())) }
 
     /** Gets a summary component that represents a tuple element. */
     SummaryComponent tupleElement(int index) {
-      exists(TupleElementContent c | c.getIndex() = index and result = content(c))
+      exists(TupleElementContent c |
+        c.getIndex() = index and result = content(TSingletonContent(c))
+      )
     }
 
     /** Gets a summary component that represents a dictionary element. */
     SummaryComponent dictionaryElement(string key) {
-      exists(DictionaryElementContent c | c.getKey() = key and result = content(c))
+      exists(DictionaryElementContent c |
+        c.getKey() = key and result = content(TSingletonContent(c))
+      )
     }
 
     /** Gets a summary component that represents a dictionary element at any key. */
-    SummaryComponent dictionaryElementAny() { result = content(any(DictionaryElementAnyContent c)) }
+    SummaryComponent dictionaryElementAny() {
+      result = content(TSingletonContent(TDictionaryElementAnyContent()))
+    }
 
     /** Gets a summary component that represents an attribute element. */
     SummaryComponent attribute(string attr) {
-      exists(AttributeContent c | c.getAttribute() = attr and result = content(c))
+      exists(AttributeContent c |
+        c.getAttribute() = attr and result = content(TSingletonContent(c))
+      )
     }
 
     /** Gets a summary component that represents the return value of a call. */

python/ql/lib/semmle/python/dataflow/new/internal/TypeTrackingImpl.qll

@@ -111,19 +111,19 @@ module TypeTrackingInput implements Shared::TypeTrackingInput<Location> {
 
   class LocalSourceNode = DataFlowPublic::LocalSourceNode;
 
-  class Content extends DataFlowPublic::Content {
+  class Content extends DataFlowPublic::ContentSet {
     Content() {
       // TODO: for now, it's not 100% clear if should support non-precise content in
       // type-tracking, or if it will lead to bad results. We start with only allowing
       // precise content, which should always be a good improvement! It also simplifies
       // the process of examining new results from non-precise content steps in the
       // future, since you will _only_ have to look over the results from the new
       // non-precise steps.
-      this instanceof DataFlowPublic::AttributeContent
+      this.asSingleton() instanceof DataFlowPublic::AttributeContent
       or
-      this instanceof DataFlowPublic::DictionaryElementContent
+      this.asSingleton() instanceof DataFlowPublic::DictionaryElementContent
       or
-      this instanceof DataFlowPublic::TupleElementContent
+      this.asSingleton() instanceof DataFlowPublic::TupleElementContent
     }
   }
 
@@ -212,7 +212,7 @@ module TypeTrackingInput implements Shared::TypeTrackingInput<Location> {
    */
   predicate storeStep(Node nodeFrom, Node nodeTo, Content content) {
     exists(DataFlowPublic::AttrWrite a, string attrName |
-      content.(DataFlowPublic::AttributeContent).getAttribute() = attrName and
+      content.asSingleton().(DataFlowPublic::AttributeContent).getAttribute() = attrName and
       a.mayHaveAttributeName(attrName) and
       nodeFrom = a.getValue() and
       nodeTo = a.getObject()
@@ -242,7 +242,7 @@ module TypeTrackingInput implements Shared::TypeTrackingInput<Location> {
    */
   predicate loadStep(Node nodeFrom, LocalSourceNode nodeTo, Content content) {
     exists(DataFlowPublic::AttrRead a, string attrName |
-      content.(DataFlowPublic::AttributeContent).getAttribute() = attrName and
+      content.asSingleton().(DataFlowPublic::AttributeContent).getAttribute() = attrName and
       a.mayHaveAttributeName(attrName) and
       nodeFrom = a.getObject() and
       nodeTo = a

python/ql/src/Variables/LoopVariableCapture/LoopVariableCaptureQuery.qll

@@ -58,11 +58,11 @@ module EscapingCaptureFlowConfig implements DataFlow::ConfigSig {
 
   predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet cs) {
     isSink(node) and
-    (
-      cs.(DataFlow::TupleElementContent).getIndex() in [0 .. 10] or
-      cs instanceof DataFlow::ListElementContent or
-      cs instanceof DataFlow::SetElementContent or
-      cs instanceof DataFlow::DictionaryElementAnyContent
+    exists(DataFlow::Content c | cs = DataFlow::TSingletonContent(c) |
+      c.(DataFlow::TupleElementContent).getIndex() in [0 .. 10] or
+      c instanceof DataFlow::ListElementContent or
+      c instanceof DataFlow::SetElementContent or
+      c instanceof DataFlow::DictionaryElementAnyContent
     )
   }
 }