From b02a66d13ec83a40fce6072da99a258050acc482 Mon Sep 17 00:00:00 2001
From: eldritch horrors <pennae@lix.systems>
Date: Sat, 18 Oct 2025 19:43:44 +0200
Subject: [PATCH] libstore: simplify hook instance handling

we never need the connection or the rpc client directly after the hook
is constructed, only the hook instance rpc object. wrapping them using
kj primitives makes this more explicit and prevents destruction errors

Change-Id: I7e0b14d7e365c2e001273e04c0e741ba4afb12f2
---
 lix/libstore/build/derivation-goal.cc |  4 +---
 lix/libstore/build/hook-instance.cc   |  5 ++---
 lix/libstore/build/hook-instance.hh   | 12 ++----------
 3 files changed, 5 insertions(+), 16 deletions(-)

diff --git a/lix/libstore/build/derivation-goal.cc b/lix/libstore/build/derivation-goal.cc
index 0cad92073..01972f6d9 100644
--- a/lix/libstore/build/derivation-goal.cc
+++ b/lix/libstore/build/derivation-goal.cc
@@ -1055,7 +1055,7 @@ try {
     KJ_DEFER(hook = nullptr);
     auto output = handleChildOutput();
 
-    auto buildReq = hook->rpc.buildRequest();
+    auto buildReq = hook->rpc->buildRequest();
     RPC_FILL(buildReq, setAmWilling, slotToken.valid());
     RPC_FILL(buildReq, setNeededSystem, drv->platform);
     RPC_FILL(buildReq, initDrvPath, drvPath, worker.store);
@@ -1114,8 +1114,6 @@ try {
 
     // close the rpc connection to have the hook exit
     hook->rpc = nullptr;
-    hook->client = nullptr;
-    hook->conn = nullptr;
 
     if (auto error = TRY_AWAIT(output)) {
         co_return HookResult::Accept{std::move(*error)};
diff --git a/lix/libstore/build/hook-instance.cc b/lix/libstore/build/hook-instance.cc
index 0f76d61fc..7e050d37e 100644
--- a/lix/libstore/build/hook-instance.cc
+++ b/lix/libstore/build/hook-instance.cc
@@ -7,6 +7,7 @@
 #include "lix/libutil/rpc.hh"
 #include "lix/libutil/strings.hh"
 #include "lix/libutil/types-rpc.hh" // IWYU pragma: keep
+#include <kj/memory.h>
 #include <memory>
 
 namespace nix {
@@ -76,9 +77,7 @@ try {
 
     co_return std::make_unique<HookInstance>(
         std::move(fromHook_.readSide),
-        std::move(conn),
-        std::move(client),
-        std::move(rpc),
+        kj::heap(std::move(rpc)).attach(std::move(conn), std::move(client)),
         std::move(pid)
     );
 } catch (...) {
diff --git a/lix/libstore/build/hook-instance.hh b/lix/libstore/build/hook-instance.hh
index 7d55d0a20..5bddf3ba7 100644
--- a/lix/libstore/build/hook-instance.hh
+++ b/lix/libstore/build/hook-instance.hh
@@ -19,24 +19,16 @@ struct HookInstance
      */
     AutoCloseFD fromHook;
 
-    kj::Own<kj::AsyncCapabilityStream> conn;
-    std::unique_ptr<capnp::TwoPartyClient> client;
-    rpc::build_remote::HookInstance::Client rpc;
+    kj::Own<rpc::build_remote::HookInstance::Client> rpc;
 
     std::map<ActivityId, Activity> activities;
 
     static kj::Promise<Result<std::unique_ptr<HookInstance>>> create();
 
     HookInstance(
-        AutoCloseFD fromHook,
-        kj::Own<kj::AsyncCapabilityStream> conn,
-        std::unique_ptr<capnp::TwoPartyClient> client,
-        rpc::build_remote::HookInstance::Client rpc,
-        Pid pid
+        AutoCloseFD fromHook, kj::Own<rpc::build_remote::HookInstance::Client> rpc, Pid pid
     )
         : fromHook(std::move(fromHook))
-        , conn(std::move(conn))
-        , client(std::move(client))
         , rpc(std::move(rpc))
         , pidOrStatus(std::move(pid))
     {