Merge pull request NixOS#9804 from edolstra/missing-nar-crash

Fix crash when NAR is missing from binary cache

(cherry picked from commit 3b20cca)
Change-Id: I50ff18f4a6de69c323473b4a8e3e098d1f365145

src/libstore/build/worker.cc

@@ -250,7 +250,7 @@ void Worker::childTerminated(Goal * goal, bool wakeSleepers)
 
 void Worker::waitForBuildSlot(GoalPtr goal)
 {
-    debug("wait for build slot");
+    goal->trace("wait for build slot");
     bool isSubstitutionGoal = goal->jobCategory() == JobCategory::Substitution;
     if ((!isSubstitutionGoal && getNrLocalBuilds() < settings.maxBuildJobs) ||
         (isSubstitutionGoal && getNrSubstitutions() < settings.maxSubstitutionJobs))

src/libstore/local-store.cc

@@ -1203,7 +1203,11 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
     Finally cleanup = [&]() {
         if (!narRead) {
             ParseSink sink;
-            parseDump(sink, source);
+            try {
+                parseDump(sink, source);
+            } catch (...) {
+                ignoreException();
+            }
         }
     };
 

src/libstore/store-api.cc

@@ -1069,6 +1069,11 @@ void copyStorePath(
     RepairFlag repair,
     CheckSigsFlag checkSigs)
 {
+    /* Bail out early (before starting a download from srcStore) if
+       dstStore already has this path. */
+    if (!repair && dstStore.isValidPath(storePath))
+        return;
+
     auto srcUri = srcStore.getUri();
     auto dstUri = dstStore.getUri();
     auto storePathS = srcStore.printStorePath(storePath);