libstore: move Goal::getBuildResult to BuildResult

there are no other uses for this yet, but asking for just a subset of
outputs does seem at least somewhat useful to have as a generic thing

Change-Id: I30ff5055a666c351b1b086b8d05b9d7c9fb1c77a

6 files changed, 40 insertions, 42 deletions

diff --git a/src/libstore/build-result.cc b/src/libstore/build-result.cc
index 18f519c5c..de280c13f 100644
--- a/src/libstore/build-result.cc
+++ b/src/libstore/build-result.cc
@@ -15,4 +15,27 @@ GENERATE_CMP_EXT(
     me->cpuUser,
     me->cpuSystem);
 
+KeyedBuildResult BuildResult::restrictTo(DerivedPath path) const
+{
+    KeyedBuildResult res{*this, std::move(path)};
+
+    if (auto pbp = std::get_if<DerivedPath::Built>(&res.path)) {
+        auto & bp = *pbp;
+
+        /* Because goals are in general shared between derived paths
+           that share the same derivation, we need to filter their
+           results to get back just the results we care about.
+         */
+
+        for (auto it = res.builtOutputs.begin(); it != res.builtOutputs.end();) {
+            if (bp.outputs.contains(it->first))
+                ++it;
+            else
+                it = res.builtOutputs.erase(it);
+        }
+    }
+
+    return res;
+}
+
 }
diff --git a/src/libstore/build-result.hh b/src/libstore/build-result.hh
index 8840fa7e3..9634fb944 100644
--- a/src/libstore/build-result.hh
+++ b/src/libstore/build-result.hh
@@ -11,6 +11,8 @@
 
 namespace nix {
 
+struct KeyedBuildResult;
+
 struct BuildResult
 {
     /**
@@ -112,6 +114,18 @@ struct BuildResult
     {
         throw Error("%s", errorMsg);
     }
+
+    /**
+     * Project a BuildResult with just the information that pertains to
+     * the given path.
+     *
+     * A `BuildResult` may hold information for multiple derived paths;
+     * this function discards information about outputs not relevant in
+     * `path`. Build `Goal`s in particular may contain more outputs for
+     * a single build result than asked for directly, it's necessary to
+     * remove any such additional result to not leak other build infos.
+     */
+    KeyedBuildResult restrictTo(DerivedPath path) const;
 };
 
 /**
diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index c0ca18310..38c54e854 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -1560,7 +1560,7 @@ void DerivationGoal::waiteeDone(GoalPtr waitee, ExitCode result)
     auto & outputs = nodeP->value;
 
     for (auto & outputName : outputs) {
-        auto buildResult = dg->getBuildResult(DerivedPath::Built {
+        auto buildResult = dg->buildResult.restrictTo(DerivedPath::Built {
             .drvPath = makeConstantStorePathRef(dg->drvPath),
             .outputs = OutputsSpec::Names { outputName },
         });
diff --git a/src/libstore/build/entry-points.cc b/src/libstore/build/entry-points.cc
index 67236bb39..c6955600e 100644
--- a/src/libstore/build/entry-points.cc
+++ b/src/libstore/build/entry-points.cc
@@ -62,10 +62,7 @@ std::vector<KeyedBuildResult> Store::buildPathsWithResults(
     std::vector<KeyedBuildResult> results;
 
     for (auto & [req, goalPtr] : state)
-        results.emplace_back(KeyedBuildResult {
-            goalPtr->getBuildResult(req),
-            /* .path = */ req,
-        });
+        results.emplace_back(goalPtr->buildResult.restrictTo(req));
 
     return results;
 }
@@ -78,7 +75,7 @@ BuildResult Store::buildDerivation(const StorePath & drvPath, const BasicDerivat
 
     try {
         worker.run(Goals{goal});
-        return goal->getBuildResult(DerivedPath::Built {
+        return goal->buildResult.restrictTo(DerivedPath::Built {
             .drvPath = makeConstantStorePathRef(drvPath),
             .outputs = OutputsSpec::All {},
         });
diff --git a/src/libstore/build/goal.cc b/src/libstore/build/goal.cc
index f4973efc9..4db6af6e6 100644
--- a/src/libstore/build/goal.cc
+++ b/src/libstore/build/goal.cc
@@ -11,29 +11,6 @@ bool CompareGoalPtrs::operator() (const GoalPtr & a, const GoalPtr & b) const {
 }
 
 
-BuildResult Goal::getBuildResult(const DerivedPath & req) const {
-    BuildResult res { buildResult };
-
-    if (auto pbp = std::get_if<DerivedPath::Built>(&req)) {
-        auto & bp = *pbp;
-
-        /* Because goals are in general shared between derived paths
-           that share the same derivation, we need to filter their
-           results to get back just the results we care about.
-         */
-
-        for (auto it = res.builtOutputs.begin(); it != res.builtOutputs.end();) {
-            if (bp.outputs.contains(it->first))
-                ++it;
-            else
-                it = res.builtOutputs.erase(it);
-        }
-    }
-
-    return res;
-}
-
-
 void Goal::addWaitee(GoalPtr waitee)
 {
     waitees.insert(waitee);
diff --git a/src/libstore/build/goal.hh b/src/libstore/build/goal.hh
index 94346531e..575621037 100644
--- a/src/libstore/build/goal.hh
+++ b/src/libstore/build/goal.hh
@@ -98,7 +98,6 @@ struct Goal : public std::enable_shared_from_this<Goal>
      */
     std::optional<ExitCode> exitCode;
 
-protected:
     /**
      * Build result.
      */
@@ -107,18 +106,6 @@ protected:
 public:
 
     /**
-     * Project a `BuildResult` with just the information that pertains
-     * to the given request.
-     *
-     * In general, goals may be aliased between multiple requests, and
-     * the stored `BuildResult` has information for the union of all
-     * requests. We don't want to leak what the other request are for
-     * sake of both privacy and determinism, and this "safe accessor"
-     * ensures we don't.
-     */
-    BuildResult getBuildResult(const DerivedPath &) const;
-
-    /**
      * Exception containing an error message, if any.
      */
     std::unique_ptr<Error> ex;