librunt is a small library for building extensions to the ELF-level
process runtime typically implemented by a dynamic linker.

The main parts are:

* relf.h, an inlines-only header for introspecting on ELF-level structures
within a process (usable without linking in librunt)

* {bitmap,bitops,vas,maps}.h -- utility code

* librunt.h -- calls for querying addresses (think: souped-up dladdr)

* dso-meta.h -- extended per-DSO metadata (think: souped-up link.h)

To work, librunt must be preloaded (e.g. as librunt_preload.so) into the
process. One day soon it should be possible to use libgerald to build a
new dynamic linker, runtld.so, which may be a nicer interface.

You can also use librunt as a basis for an extended runtime that does
more interesting things. One example is libsystrap, which lets you trap
system calls (e.g. it includes an in-process system call tracer as a
demo application, basicallyj a "faster strace"). liballocs and
(transitively) libcrunch are also instances of this (or will be, once I
backport liballocs to use librunt... most of librunt's code originates
in liballocs).