It's come up several times that it'd be nice to have somewhere to dump
drgn scripts that people write while debugging without requiring them to
be cleaned up and scrutinized in code review. Serapheim Dimitropoulos
noted that several projects have a "contrib" directory for this purpose.
See [1]. Let's create one, document it, exclude it from pre-commit, and
move our (mostly unmaintained) examples there.
1: https://drewdevault.com/2020/06/06/Add-a-contrib-directory.html
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Some things want this file to exist (e.g., the Fedora RPM spec, GitHub;
see #221). Let's do what the Linux kernel does and provide a summary of
the licensing situation in COPYING. The REUSE FAQ [1] doesn't discourage
this.
1: https://reuse.software/faq/#tradition
Signed-off-by: Omar Sandoval <osandov@osandov.com>
This has been useful to run manually before, but I haven't added it to
the CI because it was somewhat noisy. But, it reports some really useful
warnings, so let's configure it for our needs and add it to pre-commit.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Now that commit d999703f94 ("vmtest: add kernel module build
dependencies to kernel packages") added the files necessary to build a
test kernel module, add the module (currently a stub) and the
scaffolding necessary to build and load it.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
In particular, the Fedora RPM build needs pytest.ini. CONTRIBUTING.rst
should be included along the same lines as README.rst. libdrgn/Doxyfile
should be included so that users with a source distribution can build
the libdrgn documentation.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Now that we have tests for kernel-specific functionality, we should run
them on various kernel versions. This adds a script for doing so using
QEMU with a pre-built root filesystem image and kernels that I'm hosting
on my Dropbox. The script can be run locally, but this also sets it up
to be run on Travis. For now, we're testing the mainline, stable, and
longterm releases from kernel.org (not including v3.16, which doesn't
even boot for me).
drgn has pretty thorough in-program documentation, but it doesn't have a
nice overview or introduction to the basic concepts. This commit adds
that using Sphinx. In order to avoid documenting everything in two
places, the libdrgn bindings have their docstrings generated from the
API documentation. The alternative would be to use Sphinx's autodoc
extension, but that's not as flexible and would also require building
the extension to build the docs. The documentation for the helpers is
generated using autodoc and a small custom extension.
I went back and forth on using setuptools or autotools for the Python
extension, but I eventually settled on using only setuptools after
fighting to get the two to integrate well. However, setuptools is kind
of crappy; for one, it rebuilds every source file when rebuilding the
extension, which is really annoying for development. automake is a
better designed build system overall, so let's use that for the
extension. We override the build_ext command to build using autotools
and copy things where setuptools expects them.
The current mixed Python/C implementation works well, but it has a
couple of important limitations:
- It's too slow for some common use cases, like iterating over large
data structures.
- It can't be reused in utilities written in other languages.
This replaces the internals with a new library written in C, libdrgn. It
includes Python bindings with mostly the same public interface as
before, with some important improvements:
- Types are now represented by a single Type class rather than the messy
polymorphism in the Python implementation.
- Qualifiers are a bitmask instead of a set of strings.
- Bit fields are not considered a separate type.
- The lvalue/rvalue terminology is replaced with reference/value.
- Structure, union, and array values are better supported.
- Function objects are supported.
- Program distinguishes between lookups of variables, constants, and
functions.
The C rewrite is about 6x as fast as the original Python when using the
Python bindings, and about 8x when using the C API directly.
Currently, the exposed API in C is fairly conservative. In the future,
the memory reader, type index, and object index APIs will probably be
exposed for more flexibility.
