ungoogled-chromium/docs/developing.md

Development notes and procedures

This document contains an assortment of information for those who want to develop ungoogled-chromium.

Information targeted towards developers and other users live in the Wiki.

Contents:

• Branches
• Adding command-line flags and chrome://flags options
• Workflow of updating to a new Chromium version

Branches

Development is focused on master, and any changes in there should not break anything unless platforms break during a Chromium version rebase.

Larger feature changes or hotfixes must be done in a separate branch. Once they are ready, then a Pull Request can be made onto master (for contributors with write access, merging directly via a git client is fine). After the branch is merged, it should be removed.

Adding command-line flags and chrome://flags options

See docs/how_to_add_your_feature_flag.md in the Chromium source tree for the steps needed. Note that updating tools/metrics/histograms/enums.xml is not required.

For new flags, first add a constant to third_party/ungoogled/ungoogled_switches.cc (by modifying patch resources/patches/ungoogled-chromium/add-third-party-ungoogled.patch). Then, use this constant in the steps outlined above.

Workflow of updating to a new Chromium version

Tested on Debian 10 (buster). Exact instructions should work on any other Linux or macOS system with the proper dependencies.

To gain a deeper understanding of this updating process, have a read through docs/design.md.

Dependencies

• quilt
  • This is available in most (if not all) Linux distributions, and also Homebrew on macOS.
  • This utility facilitates most of the updating process, so it is important to learn how to use this. The manpage for quilt (as of early 2017) lacks an example of a workflow. There are multiple guides online, but this guide from Debian and the referenced guide on that page are the ones referenced in developing the current workflow.
• Python 3.6 or newer

Downloading the source code

mkdir -p build/download_cache
./utils/downloads.py retrieve -i downloads.ini -c build/download_cache
./utils/downloads.py unpack -i downloads.ini -c build/download_cache build/src

Updating lists

The utility devutils/update_lists.py automates this process. By default, it will update the files in the local repo. Pass in -h or --help for available options.

./devutils/update_lists.py -t build/src

The resulting source tree in build/src will not have binaries pruned or domains substituted.

Updating patches

IMPORTANT: Make sure domain substitution has not been applied before updating patches.

1. Run source devutils/set_quilt_vars.sh
   • This will setup quilt to modify patches directly in patches/
2. Go into the source tree: cd build/src
3. Use quilt to refresh all patches: quilt push -a --refresh
   • If an error occurs, go to the next step. Otherwise, skip to Step 5.
4. Use quilt to fix the broken patch:
   1. Run quilt push -f
   2. Edit the broken files as necessary by adding (quilt edit ... or quilt add ...) or removing (quilt remove ...) files as necessary
      • When removing large chunks of code, remove each line instead of using language features to hide or remove the code. This makes the patches less susceptible to breakages when using quilt's refresh command (e.g. quilt refresh updates the line numbers based on the patch context, so it's possible for new but desirable code in the middle of the block comment to be excluded.). It also helps with readability when someone wants to see the changes made based on the patch alone.
   3. Refresh the patch: quilt refresh
   4. Go back to Step 3.
5. Run quilt pop -a
6. Go back to ungoogled-chromium repo: cd ../..
7. Run devutils/validate_config.py. If any warnings are printed, address them; otherwise, continue to Step 8.
8. Run devutils/validate_patches.py -l build/src. If errors occur, go back to Step 3.

This should leave unstaged changes in the git repository to be reviewed, added, and committed.

Steps for fixing patches after a failed build attempt

If domain substitution is not applied, then the steps from the previous section will work for revising patches.

If domain substitution is applied, then the steps for the initial update will not apply since that would create patches which depend on domain substitution. Here is a method of dealing with this:

1. Revert domain substitution: ./utils/domain_substitution.py revert -c CACHE_PATH_HERE build/src
2. Follow the patch updating section above
3. Reapply domain substitution: ./utils/domain_substitution.py apply -r domain_regex.list -f domain_substitution.list -c CACHE_PATH_HERE build/src
4. Reattempt build. Repeat steps as necessary.

Next steps

• Submit a Pull Request of these changes to the ungoogled-chromium repo.
• Once the PR is merged, update the repositories of each platform repository that you are maintaining under the ungoogled-software organization.