Advice about "Internal error, no stack for trap handler"

Problem solved (see below) Many thanks to anyone that looked in to help!

Hi,

Internal error, no stack for trap handler:
Internal error: abort on instruction fetch
at &FFFFFFCC, pc = &FFFFFFC8
registers at 00013250

Is the address part of the task’s address space, it seems rather high?

I am pretty sure the task’s stack has been corrupted as the error is generated as the flow of control leaves this function

void tabPane_addTab(Tabby *tabby, wimp_w handle)
{
   LOG("tabPane_addTab", "Entered '%s'", "tabPane_addTab");
                              
   // lots of code here

   if (info.info.titleflags & wimp_INDIRECT)
   {       
      char buffer[512];

      getWindowTitle(&info, task, buffer, 512);

      label = tabPane_extractLabel(buffer);
   }  
   else
   {       
      ...
   }    

   // more code here
 
   LOG("tabPane_addTab", "Leaving '%s'", "tabPane_addTab");
}                              

and where it is called looks like this:

      LOG("gui_monitor", "calling %s", "tabPane_addTab");

      tabPane_addTab(tabby, tabby->window);

      LOG("gui_monitor", "back from %s", "tabPane_addTab");

The end of the log contains the “Leaving ‘tabPane_addTab’” message, but not the “back from tabPane_addTab” message. LOG works by sending user messages to another task, so buffering shouldn’t be a problem. I’ve gone through all the code and I can’t see anything that is likely to corrupt the stack (and tested buffer over-runs etc). If I change buffer to contain 8192 bytes or more, the error goes away, even if I don’t call the code that uses it.

It is odd that !tabby only does this with !WinEd as far as I can tell, and it is odd that there is no problem if it is a blank (unsaved) template file.

Debugging WIMP programs is a lot harder than MATLAB! I’d be very grateful for any suggestions!

The GITHub repository is here (beware it isn’t fully working version as I have commented some parts out to try an pin down the problem):

https://github.com/usr-bin-gcc/Tabby

Problem solved, I was using wimp_get_wind_info incorrectly – it was reading in all the icon info into the buffer, which is why it was O.K. when it was a blank template file.

There’s almost no problem that the solution doesn’t become obvious to you, within a few seconds of writing down a full description posting to a forum! :)

Indeed, on the bright side, at least it is guaranteed to work! ;o)

There’s almost no problem that the solution doesn’t become obvious to you, within a few seconds of writing down a full description posting to a forum! :)

Ha-ha, that’s something that even I recognise (sometimes).

There’s almost no problem that the solution doesn’t become obvious to you, within a few seconds of writing down a full description posting to a forum! :)

This is so true that I sometimes wonder whether posts shouldn’t automatically go into a ‘pending’ section of the site, while generating a ‘do you want to think about that for a moment?’ message. This would certainly have saved me from embarassment in the past!

This is so true that I sometimes wonder whether posts shouldn’t automatically go into a ‘pending’ section of the site, while generating a ‘do you want to think about that for a moment?’ message. This would certainly have saved me from embarassment in the past!

The world doesn’t work like that – it isn’t until you’ve (potentially) embarrassed yourself that the realisation kicks in.

The world doesn’t work like that – it isn’t until you’ve (potentially) embarrassed yourself that the realisation kicks in.

Absolutely.