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testfs

This is a DeepState test harness for TestFS, which is a user level toy file system that is similar to ext3.

TestFS comes out of U. Toronto file system research:

J. Sun, D. Fryer, A. Goel, and A. D. Brown, “Using declarative invariants for protecting file-system integrity,” in Proceedings of the 6th Workshop on Programming Languages and Operating Systems. 2011. http://www.sigops.org/sosp/sosp11/workshops/plos/06-sun.pdf

This version is based on a series of implementations, first adapted to DeepState by Peter Goodman (https://github.com/pgoodman/testfs), now maintained by Alex Groce. The primary change is that a broken (undefined behavior causing) inode hash table has been disabled, with inode lookups always going to "disk." Disk here is a block-device emulated with a Big Old Array. Also, this adds a semi-POSIX layer on top of the low-level interface to TestFS.

Tests.cpp shows what a DeepState harness for a POSIX-like interface looks like.

The tests check that resets at inopportune times do not make the file system unmountable (which does not hold).

Usage

Easiest way to play with this is to use the DeepState docker, and:

  1. clone this repo
  2. cd testfs; make

You then have a binary you can fuzz with Eclipser, a binary you can fuzz with libFuzzer, a binary you can fuzz with AFL, and a binary that collects code coverage information.