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mirror of https://github.com/systemd/systemd synced 2024-07-08 20:15:55 +00:00

Drop mkosi + clang section from HACKING

We removed a few features that made this work, will be added back
in the future when we restructure the way mkosi does build images.
This commit is contained in:
Daan De Meyer 2023-02-16 20:06:27 +01:00
parent 2edcf8e7db
commit e9c47453d2

View File

@ -188,83 +188,6 @@ For more details on building fuzzers and integrating with OSS-Fuzz, visit:
- [Setting up a new project - OSS-Fuzz](https://google.github.io/oss-fuzz/getting-started/new-project-guide/)
- [Tutorials - OSS-Fuzz](https://google.github.io/oss-fuzz/reference/useful-links/#tutorials)
## mkosi + clangd
[clangd](https://clangd.llvm.org/) is a language server that provides code completion, diagnostics and more
right in your editor of choice (with the right plugin installed). When using mkosi, we can run clangd in the
mkosi build container to avoid needing to build systemd on the host machine just to make clangd work. To
achieve this, create a script with the following contents in systemd's project directory on the host:
```sh
#!/usr/bin/env sh
tee mkosi-clangd.build >/dev/null <<EOF
#!/usr/bin/env sh
exec clangd \\
--compile-commands-dir=/root/build \\
--path-mappings=\\
"\\
$(pwd)=/root/src,\\
$(pwd)/mkosi.builddir=/root/build,\\
$(pwd)/mkosi.includedir=/usr/include,\\
$(pwd)/mkosi.installdir=/root/dest\\
" \\
--header-insertion=never
EOF
chmod +x mkosi-clangd.build
exec pkexec mkosi --source-file-transfer=mount --incremental --skip-final-phase --build-script mkosi-clangd.build build
```
Next, mark the script as executable and point your editor plugin to use this script to start clangd. For
vscode's clangd extension, this is done via setting the `clangd.path` option to the path of the
mkosi-clangd.sh script.
To be able to navigate to include files of systemd's dependencies, we need to make the /usr/include folder of
the build image available on the host. mkosi supports this by setting the `IncludeDirectory` option in
mkosi's config. The easiest way to set the option is to create a file 20-local.conf in mkosi.default.d/ and
add the following contents:
```
[Content]
IncludeDirectory=mkosi.includedir
```
This will make the contents of /usr/include available in mkosi.includedir in the systemd project directory.
We already configured clangd to map any paths in /usr/include in the build image to mkosi.includedir/ on the
host in the mkosi-clangd.sh script.
We also need to make sure clangd is installed in the build image. To have mkosi install clangd in the build
image, edit the 20-local.conf file we created earlier and add the following contents under the `[Content]`
section:
```
BuildPackages=<clangd-package>
```
Note that the exact package containing clangd will differ depending on the distribution used. Some
distributions have a separate clangd package, others put the clangd binary in a clang-tools-extra package and
some bundle clangd in the clang package.
Because mkosi needs to run as root, we also need to make sure we can enter the root password when the editor
plugin tries to run the mkosi-clangd.sh script. To be able to enter the root password in non-interactive
scripts, we use pkexec instead of sudo. pkexec will launch a graphical interface to let the user enter their
password, so that the password can be entered by the user even when pkexec is executed from a non-interactive
shell.
Due to a bug in btrfs, it's currently impossible to mount two mkosi btrfs images at the same time. Because of
this, trying to do a regular build while the clangd image is running will fail. To circumvent this, use ext4
instead of btrfs for the images by adding the following contents to 20-local.conf:
```
[Output]
Format=gpt_ext4
```
Finally, to ensure clangd starts up quickly in the editor, run an incremental build with mkosi to make sure
the cached images are initialized (`mkosi -i`).
Now, your editor will start clangd in the mkosi build image and all of clangd's features will work as
expected.
## Debugging binaries that need to run as root in vscode
When trying to debug binaries that need to run as root, we need to do some custom configuration in vscode to