mirror of
https://github.com/systemd/systemd.git
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c3e270f4ee
It turns out Jekyll (the engine behind GitHub Pages) requires that pages
include a "Front Matter" snippet of YAML at the top for proper rendering.
Omitting it will still render the pages, but including it opens up new
possibilities, such as using a {% for %} loop to generate index.md instead of
requiring a separate script.
I'm hoping this will also fix the issue with some of the pages (notably
CODE_OF_CONDUCT.html) not being available under systemd.io
Tested locally by rendering the website with Jekyll. Before this change, the
*.md files were kept unchanged (so not sure how that even works?!), after this
commit, proper *.html files were generated from it.
128 lines
5.7 KiB
Markdown
128 lines
5.7 KiB
Markdown
---
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title: Hacking on systemd
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---
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# Hacking on systemd
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We welcome all contributions to systemd. If you notice a bug or a missing
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feature, please feel invited to fix it, and submit your work as a GitHub Pull
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Request (PR) at https://github.com/systemd/systemd/pull/new.
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Please make sure to follow our [Coding Style](CODING_STYLE.md) when submitting patches.
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Also have a look at our [Contribution Guidelines](CONTRIBUTING.md).
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When adding new functionality, tests should be added. For shared functionality
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(in `src/basic/` and `src/shared/`) unit tests should be sufficient. The general
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policy is to keep tests in matching files underneath `src/test/`,
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e.g. `src/test/test-path-util.c` contains tests for any functions in
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`src/basic/path-util.c`. If adding a new source file, consider adding a matching
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test executable. For features at a higher level, tests in `src/test/` are very
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strongly recommended. If that is not possible, integration tests in `test/` are
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encouraged.
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Please also have a look at our list of [code quality tools](CODE_QUALITY.md) we have setup for systemd,
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to ensure our codebase stays in good shape.
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Please always test your work before submitting a PR. For many of the components
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of systemd testing is straight-forward as you can simply compile systemd and
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run the relevant tool from the build directory.
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For some components (most importantly, systemd/PID1 itself) this is not
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possible, however. In order to simplify testing for cases like this we provide
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a set of `mkosi` build files directly in the source tree. `mkosi` is a tool for
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building clean OS images from an upstream distribution in combination with a
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fresh build of the project in the local working directory. To make use of this,
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please acquire `mkosi` from https://github.com/systemd/mkosi first, unless your
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distribution has packaged it already and you can get it from there. After the
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tool is installed it is sufficient to type `mkosi` in the systemd project
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directory to generate a disk image `image.raw` you can boot either in
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`systemd-nspawn` or in an UEFI-capable VM:
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```
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# systemd-nspawn -bi image.raw
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```
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or:
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```
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# qemu-system-x86_64 -enable-kvm -m 512 -smp 2 -bios /usr/share/edk2/ovmf/OVMF_CODE.fd -hda image.raw
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```
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Every time you rerun the `mkosi` command a fresh image is built, incorporating
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all current changes you made to the project tree.
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Alternatively, you may install the systemd version from your git check-out
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directly on top of your host system's directory tree. This mostly works fine,
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but of course you should know what you are doing as you might make your system
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unbootable in case of a bug in your changes. Also, you might step into your
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package manager's territory with this. Be careful!
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And never forget: most distributions provide very simple and convenient ways to
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install all development packages necessary to build systemd. For example, on
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Fedora the following command line should be sufficient to install all of
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systemd's build dependencies:
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```
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# dnf builddep systemd
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```
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Putting this all together, here's a series of commands for preparing a patch
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for systemd (this example is for Fedora):
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```sh
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$ sudo dnf builddep systemd # install build dependencies
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$ sudo dnf install mkosi # install tool to quickly build images
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$ git clone https://github.com/systemd/systemd.git
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$ cd systemd
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$ vim src/core/main.c # or wherever you'd like to make your changes
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$ meson build # configure the build
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$ ninja -C build # build it locally, see if everything compiles fine
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$ ninja -C build test # run some simple regression tests
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$ (umask 077; echo 123 > mkosi.rootpw) # set root password used by mkosi
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$ sudo mkosi # build a test image
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$ sudo systemd-nspawn -bi image.raw # boot up the test image
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$ git add -p # interactively put together your patch
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$ git commit # commit it
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$ git push REMOTE HEAD:refs/heads/BRANCH
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# where REMOTE is your "fork" on GitHub
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# and BRANCH is a branch name.
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```
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And after that, head over to your repo on GitHub and click "Compare & pull request"
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Happy hacking!
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## Fuzzers
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systemd includes fuzzers in `src/fuzz/` that use libFuzzer and are automatically
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run by [OSS-Fuzz](https://github.com/google/oss-fuzz) with sanitizers. To add a
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fuzz target, create a new `src/fuzz/fuzz-foo.c` file with a `LLVMFuzzerTestOneInput`
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function and add it to the list in `src/fuzz/meson.build`.
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Whenever possible, a seed corpus and a dictionary should also be added with new
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fuzz targets. The dictionary should be named `src/fuzz/fuzz-foo.dict` and the seed
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corpus should be built and exported as `$OUT/fuzz-foo_seed_corpus.zip` in
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`tools/oss-fuzz.sh`.
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The fuzzers can be built locally if you have libFuzzer installed by running
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`tools/oss-fuzz.sh`. You should also confirm that the fuzzer runs in the
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OSS-Fuzz environment by checking out the OSS-Fuzz repo, and then running
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commands like this:
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```
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python infra/helper.py build_image systemd
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python infra/helper.py build_fuzzers --sanitizer memory systemd ../systemd
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python infra/helper.py run_fuzzer systemd fuzz-foo
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```
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If you find a bug that impacts the security of systemd, please follow the
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guidance in [CONTRIBUTING.md](CONTRIBUTING.md) on how to report a security vulnerability.
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For more details on building fuzzers and integrating with OSS-Fuzz, visit:
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- https://github.com/google/oss-fuzz/blob/master/docs/new_project_guide.md
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- https://llvm.org/docs/LibFuzzer.html
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- https://github.com/google/fuzzer-test-suite/blob/master/tutorial/libFuzzerTutorial.md
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- https://chromium.googlesource.com/chromium/src/testing/libfuzzer/+/HEAD/efficient_fuzzer.md
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