GP-2436_fixed_args_varags_functions

Ghidra/Features/Decompiler/src/decompile/cpp/coreaction.cc

@@ -1443,6 +1443,9 @@ void ActionFuncLink::funcLinkInput(FuncCallSpecs *fc,Funcdata &data)
       ProtoParameter *param = fc->getParam(i);
       active->registerTrial(param->getAddress(),param->getSize());
       active->getTrial(i).markActive(); // Parameter is not optional
+      if (varargs){
+    	  active->getTrial(i).setFixedPosition(i);
+      }
       AddrSpace *spc = param->getAddress().getSpace();
       uintb off = param->getAddress().getOffset();
       int4 sz = param->getSize();

Ghidra/Features/Decompiler/src/decompile/cpp/fspec.cc

@@ -1701,6 +1701,25 @@ bool ParamTrial::operator<(const ParamTrial &b) const
   return (size < b.size);
 }
 
+/// Sort by fixed position then by ParamTrial::operator<
+/// \param a trial
+/// \param b trial
+/// \return \b true if \b a should be ordered before \b b
+bool ParamTrial::fixedPositionCompare(const ParamTrial &a, const ParamTrial &b)
+
+{
+	if (a.fixedPosition == -1 && b.fixedPosition == -1){
+		return a < b;
+	}
+	if (a.fixedPosition == -1){
+		return false;
+	}
+	if (b.fixedPosition == -1){
+		return true;
+	}
+	return a.fixedPosition < b.fixedPosition;
+}
+
 /// \param recoversub selects whether a sub-function or the active function is being tested
 ParamActive::ParamActive(bool recoversub)
 
@@ -5326,6 +5345,12 @@ void FuncCallSpecs::buildInputFromTrials(Funcdata &data)
 
   newparam.push_back(op->getIn(0)); // Preserve the fspec parameter
 
+  if (isDotdotdot() && isInputLocked()){
+      //if varargs, move the fixed args to the beginning of the list in order
+	  //preserve relative order of variable args
+	  activeinput.sortFixedPosition();
+  }
+
   for(int4 i=0;i<activeinput.getNumTrials();++i) {
     const ParamTrial &paramtrial( activeinput.getTrial(i) );
     if (!paramtrial.isUsed()) continue; // Don't keep unused parameters

Ghidra/Features/Decompiler/src/decompile/cpp/fspec.hh

@@ -221,9 +221,10 @@ private:
   int4 slot;			///< Slot assigned to this trial
   const ParamEntry *entry;	///< PrototypeModel entry matching this trial
   int4 offset;			///< "justified" offset into entry
+  int4 fixedPosition;   ///< argument position if a fixed arg of a varargs function, else -1
 public:
   /// \brief Construct from components
-  ParamTrial(const Address &ad,int4 sz,int4 sl) { addr = ad; size = sz; slot = sl; flags=0; entry=(ParamEntry *)0; offset=-1; }
+  ParamTrial(const Address &ad,int4 sz,int4 sl) { addr = ad; size = sz; slot = sl; flags=0; entry=(ParamEntry *)0; offset=-1; fixedPosition = -1; }
   const Address &getAddress(void) const { return addr; }	///< Get the starting address of \b this trial
   int4 getSize(void) const { return size; }			///< Get the number of bytes in \b this trial
   int4 getSlot(void) const { return slot; }			///< Get the \e slot associated with \b this trial
@@ -259,6 +260,8 @@ public:
   ParamTrial splitLo(int4 sz) const;			///< Create a trial representing the last part of \b this
   bool testShrink(const Address &newaddr,int4 sz) const;	///< Test if \b this trial can be made smaller
   bool operator<(const ParamTrial &b) const;		///< Sort trials in formal parameter order
+  void setFixedPosition(int4 pos) { fixedPosition = pos; }  ///< Set fixed position
+  static bool fixedPositionCompare(const ParamTrial &a, const ParamTrial &b); ///< Sort by fixed position; stable for fixedPosition = -1
 };
 
 /// \brief Container class for ParamTrial objects
@@ -319,6 +322,8 @@ public:
   /// \param addr is the new range's starting address
   /// \param sz is the new range's size in bytes
   void shrink(int4 i,const Address &addr,int4 sz) { trial[i].setAddress(addr,sz); }
+
+  void sortFixedPosition(void) {sort(trial.begin(),trial.end(),ParamTrial::fixedPositionCompare);}  ///< sort the trials by fixed position then <
 };
 
 /// \brief A special space for encoding FuncCallSpecs