topic Possible False Positive? in Software Archive

Possible False Positive?

Ash_McConnell — Wed, 22 Dec 2010 16:57:40 GMT

Hi Folks,

I can't see why I am getting this error.

[cpp]void AeroDynamics::setWingsFromParams()
    {
        
        
        ComponentPropertyPtr fw = _aeroParams->prop("FrontWingAngle");
        ComponentPropertyPtr rw = _aeroParams->prop("RearWingAngle");

        _frontWingDegrees = fw->valueFloat();
        _rearWingDegrees = rw->valueFloat();

        _frontWingAeroCoeff->setPrimaryAngleDegrees(_frontWingDegrees);
        _frontWingAeroCoeff->setSecondaryAngleDegrees(_rearWingDegrees);
        _rearWingAeroCoeff->setPrimaryAngleDegrees(_rearWingDegrees);
        _dragAeroCoeff->setPrimaryAngleDegrees(_frontWingDegrees);
        _dragAeroCoeff->setSecondaryAngleDegrees(_rearWingDegrees);
    }[/cpp]

I am getting a "Uninitialized partial memory access" error on line 8. When I trace the fw variable contains properly initialized variables.

aeroParams is a CarComponent variable: -

[cpp]class ComponentProperty{
	public:
		string name;
		string valueString;
		bool dynamic;
		string defaultValue;
		float min,max;
		float valueFloat(){
			float res = atof(valueString.c_str());
			return res;
		}
		int valueInt(){
			return atoi(valueString.c_str());
		}

		float valuePercent(){
			return 100.0f * (valueFloat() - min) / (max-min);
		}

		void setValuePercent(float percent){
			float ratio = MathUtil::limit(percent,0.0f,100.0f) / 100.0f;

			float val = (ratio * (max - min)) +min;
			valueString = STR(val);
		}

		ComponentProperty(){
			name = "";
			valueString = "";
			dynamic = false;
			defaultValue = "";
			min = -;
			max = 0;
		}
	};

	typedef std::shared_ptr ComponentPropertyPtr;
	typedef std::map ComponentPropertyList;
	typedef std::shared_ptr ComponentPropertyListPtr;

	class CarComponent{
	public:
		CarComponent(){
			ownedByPlayer = false;
			price = 0;
			componentId = carId = type = name = filename = description = picture = "";
		}		
 string componentId;
		string carId;
		string type;
		string name;
		string filename;
		bool ownedByPlayer; // Only used when transferring to menus, don't trust otherwise
		int price; // In credits
		ComponentPropertyList propertyList;
		string description;
		string picture;
		SPTR prop(const string &propName){
			auto res = propertyList.find(propName);
			if (res == propertyList.end()){
				throw "Property Not Found";
			}else{
				return res->second;
			}
		}

	private:
		
	};

	typedef std::shared_ptr CarComponentPtr;
	typedef std::vector CarComponentList;
	typedef std::shared_ptr CarComponentListPtr;[/cpp]

I do think that both the CarComponent and the ComponentProperty are correctly. Any idea what the problem could be?

Thanks for your help
All the best,
Ash

Possible False Positive?

Ash_McConnell — Wed, 22 Dec 2010 17:08:53 GMT

Actually from the stack trace it is complaining about _threadhandle (line 8 above is aerodynamics.cpp:154)

[plain]MSVCR100.dll!_threadhandle - :0x000230b0
MSVCR100.dll!swab - :0x0002328e
MSVCR100.dll!swab - :0x00023357
MSVCR100.dll!swab - :0x00023386
Orc.exe!setWingsFromParams - aerodynamics.cpp:154
Orc.exe!AeroDynamics - aerodynamics.cpp:67
Orc.exe!initDefaults - vehicle.cpp:483
Orc.exe!Vehicle - vehicle.cpp:165
Orc.exe!initCarPhysics - mastercarobject.cpp:146
Orc.exe!init - mastercarobject.cpp:92
Orc.exe!loadCar - cardatamanager.cpp:199
Orc.exe!switchPlayerCar - gameeventhandler.cpp:1753
Orc.exe!initRace - gameeventhandler.cpp:1784[/plain]

Any idea what the problem could be?

Possible False Positive?

David_M_Intel3 — Thu, 23 Dec 2010 00:10:56 GMT

The message about "partial" typically means size difference. It looks like the right hand side of line 8 is a float. if the left hand side is a double - that might be why Intel Parallel Inspector might be reporting a diagnostic. The recipient is larger than what is being provided.

Possible False Positive?

Ash_McConnell — Thu, 23 Dec 2010 07:44:57 GMT

Hi David,

Thanks for your reply. Both sides are floats in this case. Any other reasons as to why there would be a problem?

Thanks!
Ash

Possible False Positive?

Ash_McConnell — Thu, 23 Dec 2010 09:20:31 GMT

Hi David,

Thanks for the tip, I tracked it down to the atof. I switched the functionality so that when the value is set the atof is done then rather than in the valueFloat. This has reduced the amount of errors reported greatly.

I do think this is a bug, conversions like this shouldn't be marked as an error IMO, especially as it's explicitly cast.

Thanks again!
All the best,
Ash

Possible False Positive?

Krishna_R_Intel — Thu, 30 Dec 2010 22:01:08 GMT

Hello Ash,
I did some tests here to reproduce the issue here. Below is what I am doing.

(Note: I have ensured that the function "atof" is getting called in the below code.)

char bank_balance_str[20];
scanf("%s", bank_balance_str); //reading a floating point value from the user

float bank_balance_float = atof((const char*)bank_balance_str);
double bank_balance_double = bank_balance_float;

Please let me know if your code is doing something different from the above.

Inspector XE did not report any problems although the C++ compiler warned about possible loss of data when assigning a double (atof returns a double) to a float type variable. Could you please send me some code snippets that I can try here?

Also, can you please tell me the datatype of the variable "_frontWingDegrees" in your code?

We greatly appreciate you being very active in the forum.

Regards,
Krishna

Possible False Positive?

Ash_McConnell — Fri, 31 Dec 2010 12:53:56 GMT

Hi Krishna,

_frontWingDegrees is declared as float. The only difference I can see in the code is that bank_balance_str is a char array rather than a string. I've heard that there are some memory problems with strings in VS 2010 (non-SP1) that are fixed in SP1. I am using VS 2010(non-SP1) at the moment.

Perhaps that is the problem. I also get similar problems reported when I'm putting a float into a file stream (with my log files). Perhaps it is converting using a atof too?

Are you using VS 2010 to test? It may be that VS 2010 is at fault here?

All the best,
Ash

Possible False Positive?

Krishna_R_Intel — Mon, 03 Jan 2011 23:07:09 GMT

Yes. I am using VS 2010 but can't see how that could be a problem. I will try using string now and see what happens. Thanks for the above note, Ash.

--krishna