Re: [Libguestfs] [nbdkit PATCH v3] vddk: Drive library loading from libdir parameter.

Instead, we can fix the problem by relying on the fact that Linux provides dlmopen(), which opens a shared library in a new namespace. We first load a shim library into this namespace which overrides the dlopen() present in the main executable, then load the VDDK library. All further dlopen() calls made during VDDK initialization now go through our shim, at which point we can rewrite them to be absolute calls before the real dlopen() kicks in. Note this may break some callers who are not using libdir and expecting LD_LIBRARY_PATH to work, so it's a change in behaviour which we will have to highlight prominently in the 1.18 release notes. Thanks: Dan Berrangé, Ming Xie, Eric Blake. [eblake: Heavy modifications to Rich's initial patch, including the idea of a shim library] --- Replaces patches 2-3/3 of v2, but keeps 1/3 of that series applied as-is. Passes 'make check' for me, although we might still need a tweak for how to resolve "nbdkit-shim-dlopen.so" from its installed location. I don't have VDDK installed locally, so I can't guarantee how this works with the REAL vddk library, but the fact that 'make check' passes proves that I got the dlmopen() stuff working correctly.