Op 01-02-13 01:42, Peter Hutterer schreef: > On Thu, Jan 31, 2013 at 03:55:57PM +0100, Maarten Lankhorst wrote: >> It looks like xorg-gtest and libX11 have a different idea of where the error >> handler pointer is supposed to point at. >> Check for the default handler returned from XSet*ErrorHandler by setting a >> NULL error handler first. >> >> Signed-off-by: Maarten Lankhorst <[email protected]> >> --- >> Probably some funny interaction with symbol lookup, presumably >> _XDefault*Error points to some stub first or something, >> >> I don't really want to know, but it fixes up xorg-gtest 0.7.0 >> enough to make it run all selftests again on precise. > You'll need to figure out why this doesn't work on precise. XOpenDisplay() > calls XSetErrorHandler(NULL) if _XErrorFunction is NULL, which will install > the default error handler. And _XErrorFunction should only be non-NULL if > something else has set it already. So something is out-of-order here and we > need to figure out what. > I think it's due to lazy symbol lookup, old_handler correctly points to _XDefaultIOError, but when I print the pointer to _XDefaultIOError before the call it points to something different, presumably to some stub that would look up _XDefaultIOError.
When I added a breakpoint in the debug branch, and printed out old_handler and _XDefaultIOError, it would happily print that they were equal, so the only logical explanation is that the application had a different pointer for _XDefaultIOError than the library did. That's not to say either is incorrect, but it is likely that the application's pointer pointed to a stub that would do the symbol lookup then call the real function. ~Maarten _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel
