core/pkgs/build-support/make-hardcode-gsettings-patch/default.nix

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2024-05-02 00:46:19 +00:00
{
runCommand,
git,
coccinelle,
python3,
}:
/*
Creates a patch that replaces every instantiation of GSettings in a C project
with a code that loads a GSettings schema from a hardcoded path.
This is useful so that libraries can find schemas even though Nix lacks
a standard location like /usr/share, where GSettings system could look for schemas.
The derivation is is somewhat dependency-heavy so it is best used as part of an update script.
For each schema id referenced in the source code (e.g. org.gnome.evolution),
a variable name such as `EVOLUTION` must be provided.
It will end up in the generated patch as `@EVOLUTION@` placeholder, which should be replaced at build time
with a path to the directory containing a `gschemas.compiled` file that includes the schema.
Arguments:
- `src`: source to generate the patch for.
- `schemaIdToVariableMapping`: attrset assigning schema ids to variable names.
All used schemas must be listed.
For example, `{ "org.gnome.evolution" = "EVOLUTION_SCHEMA_PATH"; }`
hardcodes looking for `org.gnome.evolution` into `@EVOLUTION_SCHEMA_PATH@`.
- `patches`: A list of patches to apply before generating the patch.
Example:
passthru = {
hardcodeGsettingsPatch = makeHardcodeGsettingsPatch {
inherit (finalAttrs) src;
schemaIdToVariableMapping = {
...
};
};
updateScript =
let
updateSource = ...;
updatePatch = _experimental-update-script-combinators.copyAttrOutputToFile "evolution-ews.hardcodeGsettingsPatch" ./hardcode-gsettings.patch;
in
_experimental-update-script-combinators.sequence [
updateSource
updatePatch
];
};
}
*/
{
src,
patches ? [ ],
schemaIdToVariableMapping,
}:
runCommand
"hardcode-gsettings.patch"
{
inherit src patches;
nativeBuildInputs = [
git
coccinelle
python3 # For patch script
];
}
''
unpackPhase
cd "''${sourceRoot:-.}"
patchPhase
set -x
cp ${builtins.toFile "glib-schema-to-var.json" (builtins.toJSON schemaIdToVariableMapping)} ./glib-schema-to-var.json
git init
git add -A
spatch --sp-file "${./hardcode-gsettings.cocci}" --dir . --in-place
git diff > "$out"
''