> >
> > As the comment shows, when built with optimizations enabled, that
> line produces a segfault. With no optimizations, it works just fine.
> What magic must be done in order to ensure that this variable exists
> before the "constructor" function is called when loading the shared
> library?
>
> Use a C++ constructor. Execution order will follow definition order in
> the same translation unit. But between translation units, ordering
> might still not be consistent with tour requirements, so you might
> still face the same issue in the end. Therefore, it is often better to
> use a static variable in a function, where the initialization happens
> in user-defined constructor.
>
> (GNAT automatically finds a suitable global initialization order if
> such an order can be determined statically at all.)
>
> --
> Florian Weimer / Red Hat Product Security Team
Florian,
You've spoken what's taken me a few hours to find on my own. I've attempted to fix this with things like:
#include <string>
#include <dlfcn.h>
namespace {
std::string myPath __attribute__((init_priority(101)))("");
__attribute__((constructor(102)))
void SetPath() { ... }
}
This worked wonderfully in my much smaller test bed program: a single shared library and a test driver program. However, when I happily applied these changes to the larger project, a hundred or more translation units all getting wrapped into a single DLL, I was right back where I started: segfault city. Needless to say, the happiness didn't last long.
Is there some way of putting this into a constructor type function that will execute on loading the library? I want to avoid calling something to determine the path hundreds of times during execution when it won't be necessary. Thanks for the help too.
Andy
