libstore: generatorize protocol serializers

this is cursed. deeply and profoundly cursed. under NO CIRCUMSTANCES
must protocol serializer helpers be applied to temporaries! doing so
will inevitably cause dangling references and cause the entire thing
to crash. we need to do this even so to get rid of boost coroutines,
and likewise to encapsulate the serializers we suffer today at least
a little bit to allow a gradual migration to an actual IPC protocol.

(this isn't a problem that's unique to generators. c++ coroutines in
general cannot safely take references to arbitrary temporaries since
c++ does not have a lifetime system that can make this safe. -sigh-)

Change-Id: I2921ba451e04d86798752d140885d3c5cc08e146

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 51597428d..a97c32599 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -1208,7 +1208,7 @@ HookReply DerivationGoal::tryBuildHook()
 
     /* Tell the hook all the inputs that have to be copied to the
        remote system. */
-    CommonProto::write(worker.store, conn, inputPaths);
+    conn.to << CommonProto::write(worker.store, conn, inputPaths);
 
     /* Tell the hooks the missing outputs that have to be copied back
        from the remote system. */
@@ -1219,7 +1219,7 @@ HookReply DerivationGoal::tryBuildHook()
             if (buildMode != bmCheck && status.known && status.known->isValid()) continue;
             missingOutputs.insert(outputName);
         }
-        CommonProto::write(worker.store, conn, missingOutputs);
+        conn.to << CommonProto::write(worker.store, conn, missingOutputs);
     }
 
     hook->sink = FdSink();