LSS Tests

Source Layout

The general layout of the tests:

  • test_skel.h: Test helpers for common checks/etc...
  • xxx.c: Unittest for the xxx syscall (e.g. open.c).
  • Makefile: New tests should be registered in the TESTS variable.

Test Guidelines

The unittest itself generally follows the conventions:

  • Written in C (unless a very specific language behavior is needed).
  • You should only need to #include "test_skel.h". For new system headers, try to add them here rather than copying to exact unittest (if possible). It might slow compilation down slightly, but makes the code easier to manage. Make sure it is included first.
  • Use assert() on everything to check return values.
  • Use sys_xxx() to access the syscall via LSS (compared to xxx() which tends to come from the C library).
  • If you need a tempfile, use tempfile.XXXXXX for templates with helpers like mkstemp. Try to clean them up when you‘re done with them. These will be created in the cwd, but that’s fine.
  • Don't worry about trying to verify the kernel/C library API and various edge cases. The goal of LSS is to make sure that we pass args along correctly to the syscall only.
  • Make sure to leave comments in the test so it‘s clear what behavior you’re trying to verify (and how).

Feel free to extend test_skel.h with more helpers if they're useful to more than one test.

If you're looking for a simple example, start with unlink.c. You should be able to copy this over and replace the content of main().

Running The Tests

Simply run make. This will compile & execute all the tests on your local system. A standard make clean will clean up all the objects.

If you need to debug something, then the programs are simply named xxx_test and can easily be thrown into gdb ./xxx_test.

We have rudimentary cross-compile testing via gcc and clang. Try running make cross -- for any toolchains you don't have available, it should skip things automatically. This only verifies the compilation & linking stages though.

The cross-compilers can be created using