core/pkgs/build-support/closure-info.nix

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2024-05-02 00:46:19 +00:00
# This derivation builds two files containing information about the
# closure of 'rootPaths': $out/store-paths contains the paths in the
# closure, and $out/registration contains a file suitable for use with
# "nix-store --load-db" and "nix-store --register-validity
# --hash-given".
{ stdenv, coreutils, jq }:
{ rootPaths }:
assert builtins.langVersion >= 5;
stdenv.mkDerivation {
name = "closure-info";
__structuredAttrs = true;
exportReferencesGraph.closure = rootPaths;
preferLocalBuild = true;
nativeBuildInputs = [ coreutils jq ];
empty = rootPaths == [];
buildCommand =
''
out=''${outputs[out]}
mkdir $out
if [[ -n "$empty" ]]; then
echo 0 > $out/total-nar-size
touch $out/registration $out/store-paths
else
jq -r ".closure | map(.narSize) | add" < "$NIX_ATTRS_JSON_FILE" > $out/total-nar-size
jq -r '.closure | map([.path, .narHash, .narSize, "", (.references | length)] + .references) | add | map("\(.)\n") | add' < "$NIX_ATTRS_JSON_FILE" | head -n -1 > $out/registration
jq -r '.closure[].path' < "$NIX_ATTRS_JSON_FILE" > $out/store-paths
fi
'';
}