feat(3p/nix/nix-daemon): Implement Worker::BuildDerivation handler r/1382

Implement the proto handler on the server side for
Worker::BuildDerivation. This includes several additions to the proto
which I had missed on the first pass, including the actual proto
definition for the Derivation itself and a few sequence number
reorderings which are fine because this is all provisional and not
deployed yet.

A couple things to note

- I implemented a couple constructors for nix classes that initialize
  themselves based on their proto variants, which felt nice and didn't
  end up causing any issues.
- I've made the conversions between the enum types in nix and in proto
  explicit via switch statements rather than using a static_cast, out of
  an abundance of caution that the error would get mismatched in the
  future and we'd convert the wrong thing to the wrong thing - this is
  verbose, but exceptionally future proof.

Change-Id: Iecf6b88e76bc37e49efa05fd65d6cd0cb0deffed
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1249
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
Reviewed-by: Kane York <rikingcoding@gmail.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/third_party/nix/src/libstore/derivations.cc b/third_party/nix/src/libstore/derivations.cc
index 59b2a505a307..419fc584f1fe 100644
--- a/third_party/nix/src/libstore/derivations.cc
+++ b/third_party/nix/src/libstore/derivations.cc
@@ -30,6 +30,28 @@ void DerivationOutput::parseHashInfo(bool& recursive, Hash& hash) const {
   hash = Hash(this->hash, hashType);
 }
 
+BasicDerivation BasicDerivation::from_proto(
+    const nix::proto::Derivation* proto_derivation, const nix::Store* store) {
+  BasicDerivation result;
+  result.platform = proto_derivation->platform();
+  result.builder = proto_derivation->builder().path();
+  store->assertStorePath(result.builder);
+
+  result.outputs.insert(proto_derivation->outputs().begin(),
+                        proto_derivation->outputs().end());
+
+  result.inputSrcs.insert(proto_derivation->input_sources().paths().begin(),
+                          proto_derivation->input_sources().paths().end());
+
+  result.args.insert(result.args.end(), proto_derivation->args().begin(),
+                     proto_derivation->args().end());
+
+  result.env.insert(proto_derivation->env().begin(),
+                    proto_derivation->env().end());
+
+  return result;
+}
+
 Path BasicDerivation::findOutput(const std::string& id) const {
   auto i = outputs.find(id);
   if (i == outputs.end()) {