Move value-preserving callable class into FlowSteps

Author: smowton

java/ql/src/semmle/code/java/dataflow/FlowSteps.qll

@@ -20,6 +20,60 @@ private module Frameworks {
   private import semmle.code.java.frameworks.ApacheHttp
 }
 
+/**
+ * A method or constructor that returns the exact value of one of its parameters or the qualifier.
+ *
+ * Extend this class and override `returnsValue` to add additional value-preserving steps through a
+ * method that should be added to the basic local flow step relation.
+ *
+ * These steps will be visible for all global data-flow purposes, as well as via
+ * `DataFlow::Node.getASuccessor` and other related functions exposing intraprocedural dataflow.
+ */
+abstract class ValuePreservingCallable extends Callable {
+  /**
+   * Holds if this callable returns precisely the value passed into argument `arg`.
+   * `arg` is a parameter index, or is -1 to indicate the qualifier.
+   */
+  abstract predicate returnsValue(int arg);
+}
+
+/**
+ * A method or constructor that returns the exact value of its qualifier (e.g., `return this;`)
+ *
+ * Extend this class and override `returnsValue` to add additional value-preserving steps through a
+ * method that should be added to the basic local flow step relation.
+ *
+ * These steps will be visible for all global data-flow purposes, as well as via
+ * `DataFlow::Node.getASuccessor` and other related functions exposing intraprocedural dataflow.
+ */
+abstract class FluentMethod extends ValuePreservingCallable {
+  override predicate returnsValue(int arg) { arg = -1 }
+}
+
+private class StandardLibraryValuePreservingCallable extends ValuePreservingCallable {
+  int returnsArgNo;
+
+  StandardLibraryValuePreservingCallable() {
+    this.getDeclaringType().hasQualifiedName("java.util", "Objects") and
+    (
+      this.hasName(["requireNonNull", "requireNonNullElseGet"]) and returnsArgNo = 0
+      or
+      this.hasName("requireNonNullElse") and returnsArgNo = [0 .. this.getNumberOfParameters() - 1]
+      or
+      this.hasName("toString") and returnsArgNo = 1
+    )
+    or
+    this.getDeclaringType()
+        .getSourceDeclaration()
+        .getASourceSupertype*()
+        .hasQualifiedName("java.util", "Stack") and
+    this.hasName("push") and
+    returnsArgNo = 0
+  }
+
+  override predicate returnsValue(int argNo) { argNo = returnsArgNo }
+}
+
 /**
  * A unit class for adding additional taint steps.
  *

java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll

@@ -8,6 +8,7 @@ private import semmle.code.java.dataflow.SSA
 private import semmle.code.java.dataflow.TypeFlow
 private import semmle.code.java.controlflow.Guards
 private import semmle.code.java.dataflow.ExternalFlow
+private import semmle.code.java.dataflow.FlowSteps
 import semmle.code.java.dataflow.InstanceAccess
 
 cached
@@ -368,60 +369,6 @@ predicate hasNonlocalValue(FieldRead fr) {
  */
 predicate localFlowStep(Node node1, Node node2) { simpleLocalFlowStep(node1, node2) }
 
-/**
- * A method or constructor that returns the exact value of one of its parameters or the qualifier.
- *
- * Extend this class and override `returnsValue` to add additional value-preserving steps through a
- * method that should be added to the basic local flow step relation.
- *
- * These steps will be visible for all global data-flow purposes, as well as via
- * `DataFlow::Node.getASuccessor` and other related functions exposing intraprocedural dataflow.
- */
-abstract class ValuePreservingCallable extends Callable {
-  /**
-   * Holds if this callable returns precisely the value passed into argument `arg`.
-   * `arg` is a parameter index, or is -1 to indicate the qualifier.
-   */
-  abstract predicate returnsValue(int arg);
-}
-
-/**
- * A method or constructor that returns the exact value of its qualifier (e.g., `return this;`)
- *
- * Extend this class and override `returnsValue` to add additional value-preserving steps through a
- * method that should be added to the basic local flow step relation.
- *
- * These steps will be visible for all global data-flow purposes, as well as via
- * `DataFlow::Node.getASuccessor` and other related functions exposing intraprocedural dataflow.
- */
-abstract class FluentMethod extends ValuePreservingCallable {
-  override predicate returnsValue(int arg) { arg = -1 }
-}
-
-private class StandardLibraryValuePreservingCallable extends ValuePreservingCallable {
-  int returnsArgNo;
-
-  StandardLibraryValuePreservingCallable() {
-    this.getDeclaringType().hasQualifiedName("java.util", "Objects") and
-    (
-      this.hasName(["requireNonNull", "requireNonNullElseGet"]) and returnsArgNo = 0
-      or
-      this.hasName("requireNonNullElse") and returnsArgNo = [0 .. this.getNumberOfParameters() - 1]
-      or
-      this.hasName("toString") and returnsArgNo = 1
-    )
-    or
-    this.getDeclaringType()
-        .getSourceDeclaration()
-        .getASourceSupertype*()
-        .hasQualifiedName("java.util", "Stack") and
-    this.hasName("push") and
-    returnsArgNo = 0
-  }
-
-  override predicate returnsValue(int argNo) { argNo = returnsArgNo }
-}
-
 /**
  * INTERNAL: do not use.
  *

java/ql/test/library-tests/dataflow/fluent-methods/flow.ql

@@ -15,11 +15,11 @@ class Conf extends DataFlow::Configuration {
   }
 }
 
-class Model extends DataFlow::FluentMethod {
+class Model extends FluentMethod {
   Model() { this.getName() = "modelledFluentMethod" }
 }
 
-class IdentityModel extends DataFlow::ValuePreservingCallable {
+class IdentityModel extends ValuePreservingCallable {
   IdentityModel() { this.getName() = "modelledIdentity" }
 
   override predicate returnsValue(int arg) { arg = 0 }