DITools: Application-Level Support for Dynamic Extension and Flexible Composition

Today, operating systems set-up process images from executable files using fixed rules. Programs are restricted to run in essentially the same environment at every execution. However, we believe that this behavior is not always convenient, and that many times it is interesting to make variations to the execution environment, either to introduce new functionality or to specialize critical services, even when their source code is not available. This problem can be mitigated through application-level extensibility and flexible composition of binary modules.

In this paper, we describe DITOOLS an application-level tool that supports dynamic interposition on dynamically-linked procedure-call boundaries. This tool enables both global and per-module dynamic interposition. We also present a detailed use of DITOOLS and various short examples of extensions.