C++: Make vararg utilities internal for now.

Author: Dave Bartolomeo

cpp/ql/src/semmle/code/cpp/Function.qll

@@ -364,12 +364,6 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
   /** Holds if this function is a varargs function. */
   predicate isVarargs() { hasSpecifier("varargs") }
 
-  /**
-   * Gets the index of the `...` parameter, if any. If present, the value will always be equal to
-   * `getNumberOfParameters()`.
-   */
-  int getEllipsisParameterIndex() { isVarargs() and result = getNumberOfParameters() }
-
   /** Gets a type that is specified to be thrown by the function. */
   Type getAThrownType() { result = getADeclarationEntry().getAThrownType() }
 

cpp/ql/src/semmle/code/cpp/exprs/Call.qll

@@ -2,13 +2,6 @@ import semmle.code.cpp.exprs.Expr
 import semmle.code.cpp.Function
 private import semmle.code.cpp.dataflow.EscapesTree
 
-/**
- * Gets the index of the `...` parameter, if any.
- */
-private int getEllipsisParameterIndex(RoutineType type) {
-  type.getParameterType(result) instanceof UnknownType
-}
-
 /**
  * A C/C++ call.
  *
@@ -85,32 +78,6 @@ abstract class Call extends Expr, NameQualifiableElement {
 
   override string toString() { none() }
 
-  /**
-   * Gets the index of the `...` parameter, if any. This will be one greater than the index of the
-   * last declared positional parameter.
-   */
-  abstract int getEllipsisParameterIndex();
-
-  /**
-   * Gets the index of the parameter that will be initialized with the value of the argument
-   * specified by `argIndex`. For ordinary positional parameters, the argument and parameter indices
-   * will be equal. For a call to a varargs function, all arguments passed to the `...` will be
-   * mapped to the index returned by `getEllipsisParameterIndex()`.
-   */
-  final int getParameterIndexForArgument(int argIndex) {
-    exists(getArgument(argIndex)) and
-    if argIndex >= getEllipsisParameterIndex()
-    then result = getEllipsisParameterIndex()
-    else result = argIndex
-  }
-
-  /**
-   * Holds if the argument specified by `index` is an argument to the `...` of a varargs function.
-   */
-  final predicate isEllipsisArgumentIndex(int index) {
-    exists(getArgument(index)) and index >= getEllipsisParameterIndex()
-  }
-
   /**
    * Holds if this call passes the variable accessed by `va` by
    * reference as the `i`th argument.
@@ -229,7 +196,7 @@ class FunctionCall extends Call, @funbindexpr {
    * constructor calls, this predicate instead gets the `Class` of the constructor
    * being called.
    */
-  private Type getTargetType() { result = Call.super.getType().stripType() }
+  Type getTargetType() { result = Call.super.getType().stripType() }
 
   /**
    * Gets the expected return type of the function called by this call.
@@ -292,12 +259,6 @@ class FunctionCall extends Call, @funbindexpr {
     else result = "call to unknown function"
   }
 
-  final override int getEllipsisParameterIndex() {
-    if getTargetType() instanceof RoutineType
-    then result = getEllipsisParameterIndex(getTargetType())
-    else result = getTarget().getEllipsisParameterIndex()
-  }
-
   override predicate mayBeImpure() {
     this.getChild(_).mayBeImpure() or
     this.getTarget().mayHaveSideEffects() or
@@ -417,10 +378,6 @@ class ExprCall extends Call, @callexpr {
   override string toString() { result = "call to expression" }
 
   override Function getTarget() { none() }
-
-  final override int getEllipsisParameterIndex() {
-    result = getEllipsisParameterIndex(getExpr().getType().stripType())
-  }
 }
 
 /**

cpp/ql/src/semmle/code/cpp/exprs/ObjectiveC.qll

@@ -63,8 +63,6 @@ deprecated class MessageExpr extends Expr, Call {
   override Expr getArgument(int n) { none() }
 
   override int getPrecedence() { none() }
-
-  final override int getEllipsisParameterIndex() { none() }
 }
 
 /**

cpp/ql/src/semmle/code/cpp/ir/implementation/raw/internal/TranslatedFunction.qll

@@ -3,6 +3,7 @@ import semmle.code.cpp.ir.implementation.raw.IR
 private import semmle.code.cpp.ir.implementation.Opcode
 private import semmle.code.cpp.ir.internal.CppType
 private import semmle.code.cpp.ir.internal.IRUtilities
+private import semmle.code.cpp.ir.internal.VarArgs
 private import semmle.code.cpp.ir.implementation.internal.OperandTag
 private import semmle.code.cpp.ir.internal.TempVariableTag
 private import InstructionTag
@@ -28,7 +29,7 @@ private int getEllipsisVariableByteSize() {
         max(Call call, int callSize |
           callSize =
             sum(int argIndex |
-              call.isEllipsisArgumentIndex(argIndex)
+              isEllipsisArgumentIndex(call, argIndex)
             |
               call.getArgument(argIndex).getType().getSize()
             )
@@ -87,7 +88,7 @@ class TranslatedFunction extends TranslatedElement, TTranslatedFunction {
   final private TranslatedParameter getParameter(int index) {
     result = getTranslatedParameter(func.getParameter(index))
     or
-    index = func.getEllipsisParameterIndex() and
+    index = getEllipsisParameterIndexForFunction(func) and
     result = getTranslatedEllipsisParameter(func)
   }
 
@@ -144,7 +145,7 @@ class TranslatedFunction extends TranslatedElement, TTranslatedFunction {
       child = getParameter(paramIndex) and
       if
         exists(func.getParameter(paramIndex + 1)) or
-        func.getEllipsisParameterIndex() = paramIndex + 1
+        getEllipsisParameterIndexForFunction(func) = paramIndex + 1
       then result = getParameter(paramIndex + 1).getFirstInstruction()
       else result = getConstructorInitList().getFirstInstruction()
     )

cpp/ql/src/semmle/code/cpp/ir/internal/VarArgs.qll

@@ -0,0 +1,62 @@
+/**
+ * Utilities for determining which parameters and arguments correspond to the `...` parameter for
+ * varargs functions.
+ */
+
+private import cpp
+
+/**
+ * Gets the index of the `...` parameter, if any. If present, the value will always be equal to
+ * `func.getNumberOfParameters()`.
+ */
+int getEllipsisParameterIndexForFunction(Function func) {
+  func.isVarargs() and result = func.getNumberOfParameters()
+}
+
+/**
+ * Gets the index of the `...` parameter, if any.
+ */
+int getEllipsisParameterIndexForRoutineType(RoutineType type) {
+  // Since the extractor doesn't record this information directly, we look for routine types whose
+  // last parameter type is `UnknownType`.
+  type.getParameterType(result) instanceof UnknownType and
+  result = strictcount(type.getAParameterType()) - 1
+}
+
+/**
+ * Gets the index of the `...` parameter, if any. This will be one greater than the index of the
+ * last declared positional parameter.
+ */
+int getEllipsisParameterIndex(Call call) {
+  exists(FunctionCall funcCall |
+    funcCall = call and
+    if funcCall.getTargetType() instanceof RoutineType
+    then result = getEllipsisParameterIndexForRoutineType(funcCall.getTargetType())
+    else result = getEllipsisParameterIndexForFunction(funcCall.getTarget())
+  )
+  or
+  exists(ExprCall exprCall |
+    exprCall = call and
+    result = getEllipsisParameterIndexForRoutineType(exprCall.getExpr().getType().stripType())
+  )
+}
+
+/**
+ * Gets the index of the parameter that will be initialized with the value of the argument
+ * specified by `argIndex`. For ordinary positional parameters, the argument and parameter indices
+ * will be equal. For a call to a varargs function, all arguments passed to the `...` will be
+ * mapped to the index returned by `getEllipsisParameterIndex()`.
+ */
+int getParameterIndexForArgument(Call call, int argIndex) {
+  exists(call.getArgument(argIndex)) and
+  if argIndex >= getEllipsisParameterIndex(call)
+  then result = getEllipsisParameterIndex(call)
+  else result = argIndex
+}
+
+/**
+ * Holds if the argument specified by `index` is an argument to the `...` of a varargs function.
+ */
+predicate isEllipsisArgumentIndex(Call call, int index) {
+  exists(call.getArgument(index)) and index >= getEllipsisParameterIndex(call)
+}

cpp/ql/test/library-tests/arg_matching/arg_matching.ql

@@ -1,6 +1,7 @@
 import cpp
+import semmle.code.cpp.ir.internal.VarArgs
 
 from Call call, int argIndex, int paramIndex
 where
-    paramIndex = call.getParameterIndexForArgument(argIndex)
+    paramIndex = getParameterIndexForArgument(call, argIndex)
 select call, argIndex, paramIndex