How can I validate a STEP file?

Hello,

I got great help from this forum before. Thank you!

We are using Open CASCADE to read step files. I followed the samples from OCCT and was able to read in good STEP files.

However, I also need to deal with the case that the user is providing corrupted STEP files.

Right now, it just crashes at "aReader.TransferRoot(n);". I was not able to catch anything even I used try...catch... I attached this corrupt STEP file as corrupt.step along with my question.

I tried the following ways:

1. As the document says, I used aReader.PrintCheckLoad() and aReader.PrintCheckTransfer() as samples do. Neither of those give me anything. Then it crashes at aReader.TransferRoot(n). From the comments, it seems those two functions will print something on stdout? I've directed stdout to file so I assume that all the printf/cout can be seen in that file.

2. I used "OSD::SetSignal(Standard_False);". By doing this, magically, for the same corrupted STEP file, aReader.TransferRoot(n) doesn't have problem (Actually I don't understand why it doesn't have problem. I even didn't use try...catch). Then I could use BRep_Tool::IsClosed(Sh) to test if the TopoDS_Shape is closed. If not, I can throw my own exception. This way seems working fine on Windows. However, on unix, this setting seems to have very big impact on our whole software. Other components (outside of STEP reader) started to throw for SIGSEGV. I cannot only scope the setting to our STEP reading functionality. Is there a way that I could undo "OSD::SetSignal" when I leave the STEP reader code area?

3. We used to have some legacy code that tries to do the validation work:

  Standard_Boolean stepValidator(const STEPControl_Reader& reader)
  {	
	  Handle_XSControl_WorkSession thesession = reader.WS();
	  Interface_CheckIterator checks;
	  if (!thesession->IsLoaded()) 
	  {
		  return false;
	  }
	  Interface_CheckTool cht(thesession->Graph());
	  checks = cht.CompleteCheckList();

	  Standard_Boolean noErrors = checks.IsEmpty(true);
	  
	  return noErrors;
  }

 However the problem is, it also catches some OK files. For example, for the file (attached : OK.step) if I do not use the validation code, I am able to read it without problem. The reason I am saying it is an OK file but good file is I am able to see some small problem when opening it using SolidWorks.

So what is the best way to validate a STEP before doing TransferRoot? 

Thank you very much!

-Xing