addToStore(): Do evaluation on the main stack

This hopefully avoids the need for all our Boehm GC coroutine
workarounds, since the GC roots will be on the main stack of the
thread.

Fixes NixOS#11141.

(cherry picked from commit 048271e)

src/libstore/local-store.cc

@@ -1242,6 +1242,7 @@ StorePath LocalStore::addToStoreFromDump(
         });
         try {
             got = source.read(dumpBuffer.get() + oldSize, want);
+            if (!got) break;
         } catch (EndOfFile &) {
             inMemory = true;
             break;

src/libstore/store-api.cc

@@ -208,14 +208,16 @@ StorePath Store::addToStore(
         fsm = FileSerialisationMethod::NixArchive;
         break;
     }
-    auto source = sinkToSource([&](Sink & sink) {
-        dumpPath(path, sink, fsm, filter);
+    std::optional<StorePath> storePath;
+    auto sink = sourceToSink([&](Source & source) {
+        LengthSource lengthSource(source);
+        storePath = addToStoreFromDump(lengthSource, name, fsm, method, hashAlgo, references, repair);
+        if (lengthSource.total >= settings.warnLargePathThreshold)
+            warn("copied large path '%s' to the store (%s)", path, renderSize(lengthSource.total));
     });
-    LengthSource lengthSource(*source);
-    auto storePath = addToStoreFromDump(lengthSource, name, fsm, method, hashAlgo, references, repair);
-    if (lengthSource.total >= settings.warnLargePathThreshold)
-        warn("copied large path '%s' to the store (%s)", path, renderSize(lengthSource.total));
-    return storePath;
+    dumpPath(path, *sink, fsm, filter);
+    sink->finish();
+    return storePath.value();
 }
 
 void Store::addMultipleToStore(

src/libutil/serialise.cc

@@ -243,11 +243,11 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
             if (!coro) {
                 CoroutineContext ctx;
                 coro = coro_t::push_type(VirtualStackAllocator{}, [&](coro_t::pull_type & yield) {
-                    LambdaSource source([&](char *out, size_t out_len) {
+                    LambdaSource source([&](char * out, size_t out_len) {
                         if (cur.empty()) {
                             yield();
                             if (yield.get()) {
-                                return (size_t)0;
+                                return (size_t) 0;
                             }
                         }
 
@@ -271,12 +271,12 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
         void finish() override
         {
             if (!coro) return;
-            if (!*coro) abort();
+            //if (!*coro) abort();
             {
                 CoroutineContext ctx;
                 (*coro)(true);
             }
-            if (*coro) abort();
+            //if (*coro) abort();
         }
     };