Catching exceptions inside python with catch_exception_raise() doesn't work

Is it possible to monitor for exceptions using the Mac OS X 

catch_exception_raise function inside python?  As you may
know, after  
some setup, this function gets called whenever an exception
occurs.   
I have a program which works great in C but when I wrap it
in python  
it fails.  This is due to the fact that it calls exc_server,
which  
uses _dyld_lookup_and_bind, to try to find the location of
the  
function catch_exception_raise.  When wrapped in python,  
dyld_lookup_and_bind returns 0x2030 which is NOT the correct
 
address.  It then jumps there and tries executing which
causes a BUS  
ERROR.

In C at least, dyld_lookup_and_bind works if the  
catch_exception_raise function is compiled into the binary
or linked  
dynamically at runtime via a shared library (dylib). 
However, it  
doesn't work if it is brought into the executable space via
dlopen -  
which presumably is how python does it.

How can I set it up so that I can monitor applications for
exceptions  
in a python script?  I could fork and exec a program with
its own  
address space, but that seems ridiculous.  I could recompile
the  
python interpreter and include catch_exception_raise, but
that also  
seems terrible.  Or is it impossible to wrap such a program
in python  
- which seems silly?

Any help is appreciated.  Thanks,

Charlie


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Hi,

I haven't used the raw mach API's yet, so can't help you
here. I must  
say that this looks like a pretty evil API. I wonder why
they didn't  
use a manually passed in callback function like sane APIs.

Ronald

On Dec 11, 2006, at 11:43 PM, Charlie Miller wrote:

> Is it possible to monitor for exceptions using the Mac
OS X
> catch_exception_raise function inside python?  As you
may know, after
> some setup, this function gets called whenever an
exception occurs.
> I have a program which works great in C but when I wrap
it in python
> it fails.  This is due to the fact that it calls
exc_server, which
> uses _dyld_lookup_and_bind, to try to find the location
of the
> function catch_exception_raise.  When wrapped in
python,
> dyld_lookup_and_bind returns 0x2030 which is NOT the
correct
> address.  It then jumps there and tries executing which
causes a BUS
> ERROR.
>
> In C at least, dyld_lookup_and_bind works if the
> catch_exception_raise function is compiled into the
binary or linked
> dynamically at runtime via a shared library (dylib). 
However, it
> doesn't work if it is brought into the executable space
via dlopen -
> which presumably is how python does it.
>
> How can I set it up so that I can monitor applications
for exceptions
> in a python script?  I could fork and exec a program
with its own
> address space, but that seems ridiculous.  I could
recompile the
> python interpreter and include catch_exception_raise,
but that also
> seems terrible.  Or is it impossible to wrap such a
program in python
> - which seems silly?
>
> Any help is appreciated.  Thanks,
>
> Charlie
>
>
> _______________________________________________
> Pythonmac-SIG maillist  -  Pythonmac-SIGpython.org
> http://mail.python.org/mailman/listinfo/pythonmac-sig

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