[Vm-dev] argCnt, argVec, engVec alternatives

[Esteban Lorenzano]

Hi, 

El 05/01/2011, a las 10:56p.m., David T. Lewis escribió:

> 
> On Wed, Jan 05, 2011 at 03:30:19PM -0300, Esteban Lorenzano wrote:
>> 
>> ok... removing call to printAllStack in plugin and adding initialization
>> of argCnt, argVec and engVec (plus the changes made last week),
>> UnixOSProcessPlugin, without AioPlugin, is running in Cocoa Cog VM :D
>> 
> 
> Excellent!
> 
>> I would like to commit a OSProcessPlugin package with modifications...
>> or well, maybe project owner can do this changes for me (I just removed
>> primitivePrintAllStacksOnSignal, printAllStacksFunctionAddress and
>> printAllStacksOnSignal).
>> 
> 
> Actually, if you don't mind working with me on this a bit more, I'd
> like to debug it. I suspect we can can make this work on Cocoa.
> 
> We know now that external plugins can access global values such
> as argVec and interpreterProxy, and we know that this works the
> same on Unix and Mac. The last thing that is giving us problems
> is when primitivePrintAllStacksOnSignal tries to access the address
> of the function printAllStacks(). This happens here in the plugin:
> 
>  static void * printAllStacksFunctionAddress(void) {
>      extern sqInt printAllStacks();
>          return printAllStacks;
>  }
> 
> So the declaration looks right, but apparently accessing the
> address of a global function is not the same as accessing the
> value of a global variable, and perhaps this is a difference
> between the Unix/Linux systems and Mac.
> 
> So I am guessing that if, in the support code, we were to assign
> the function address to a global variable, then the plugin would
> be able to access it, and #primitivePrintAllStacksOnSignal would
> work properly.
> 
> If this sounds like it might be right, I'll try to think of a way
> to implement it without breaking the existing unix implementations.


yes, that would work. In fact, declaring printAllStacks() as:

EXPORT(sqint) printAllStacks(); 

... works too. And even adding setting -fvisibility=default (which exports ALL symbols) will work too. But I think the last one is a little bit too much: visibility=default is default for plain gcc compiler, but not un mac now (I think that's the reason why it was working before and not now) :)

Cheers,
Esteban