[lldb-dev] dlsym() and RTLD_FIRST

[Zachary Turner]

I actually already got the patch put together.  I posted in another thread.
 I don't know how to test plugin code, so if you or someone else there is
willing to help out and check that it works as expected, I would appreciate
it.


On Thu, Aug 21, 2014 at 5:27 PM, Greg Clayton <gclayton at apple.com> wrote:

> Sounds good to me. Hopefully if they don't want that they might accept an
> extra boolean argument that can specify to only look in the current shared
> library and then we can switch over to using LLVM's DynamicLibrary.
>
> > On Aug 21, 2014, at 4:22 PM, Zachary Turner <zturner at google.com> wrote:
> >
> > This seems like the only case we ever want, so I'm going to post a patch
> to LLVM's DynamicLibrary class to use RTLD_FIRST on Apple, and a similar
> method of checking the module filespec on other platforms, and see if they
> accept it.  If so, I will convert our Plugin code to use LLVM's
> DynamicLibrary and then delete our DynamicLibrary
> >
> >
> > On Thu, Aug 21, 2014 at 4:08 PM, Greg Clayton <gclayton at apple.com>
> wrote:
> >
> > > On Aug 21, 2014, at 3:31 PM, Zachary Turner <zturner at google.com>
> wrote:
> > >
> > > Can someone explain this flag to me?
> >
> > It says "only look in this binary, don't look in any others. We are
> looking for a plug-in initialization function and we don't want to get one
> back from another dylib.
> >
> > As Enrico said, the email from a while back details this:
> >
> > http://comments.gmane.org/gmane.comp.debugging.lldb.devel/305
> >
> > >  I've read the documentation, but it's still not clear to me.  If you
> ask dlsym() to search some module X, why would it ever search modules other
> than X?
> >
> > I don't know but it does.
> >
> > >
> > > The reason I ask about this is that llvm support library already has a
> DynamicLibrary class whose purpose almost exactly matches what we're using
> the Host::DynamicLibrary related functions for.  However, it doesn't use
> the RTLD_FIRST flag, and so I'm not sure what the implications are of us
> using it and deleting our own DynamicLibrary code.
> >
> > It would be nice if we could specify this flag so we either find the
> symbol from libx.dylib or we don't. We don't want to find the symbol in
> liby.dylib and call it in our case.
> >
>
>
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