2 files changed, 33 insertions, 0 deletions
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 40a406468..d040560ca 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -9,6 +9,7 @@
 #include "url.hh"
 #include "archive.hh"
 #include "callback.hh"
+#include "remote-store.hh"
 
 #include <regex>
 
@@ -881,6 +882,16 @@ std::map<StorePath, StorePath> copyPaths(ref<Store> srcStore, ref<Store> dstStor
     for (auto & path : storePaths)
         pathsMap.insert_or_assign(path, path);
 
+    // FIXME: Temporary hack to copy closures in a single round-trip.
+    if (dynamic_cast<RemoteStore *>(&*dstStore)) {
+        if (!missing.empty()) {
+            auto source = sinkToSource([&](Sink & sink) {
+                srcStore->exportPaths(missing, sink);
+            });
+            dstStore->importPaths(*source, NoCheckSigs);
+        }
+        return pathsMap;
+    }
 
     Activity act(*logger, lvlInfo, actCopyPaths, fmt("copying %d paths", missing.size()));
 
@@ -958,6 +969,22 @@ std::map<StorePath, StorePath> copyPaths(ref<Store> srcStore, ref<Store> dstStor
     return pathsMap;
 }
 
+void copyClosure(
+    ref<Store> srcStore,
+    ref<Store> dstStore,
+    const RealisedPath::Set & paths,
+    RepairFlag repair,
+    CheckSigsFlag checkSigs,
+    SubstituteFlag substitute)
+{
+    if (srcStore == dstStore) return;
+
+    RealisedPath::Set closure;
+    RealisedPath::closure(*srcStore, paths, closure);
+
+    copyPaths(srcStore, dstStore, closure, repair, checkSigs, substitute);
+}
+
 std::optional<ValidPathInfo> decodeValidPathInfo(const Store & store, std::istream & str, std::optional<HashResult> hashGiven)
 {
     std::string path;
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 356ae615c..c39d9f894 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -773,6 +773,12 @@ std::map<StorePath, StorePath> copyPaths(ref<Store> srcStore, ref<Store> dstStor
     CheckSigsFlag checkSigs = CheckSigs,
     SubstituteFlag substitute = NoSubstitute);
 
+/* Copy the closure of `paths` from `srcStore` to `dstStore`. */
+void copyClosure(ref<Store> srcStore, ref<Store> dstStore,
+    const RealisedPath::Set & paths,
+    RepairFlag repair = NoRepair,
+    CheckSigsFlag checkSigs = CheckSigs,
+    SubstituteFlag substitute = NoSubstitute);
 
 /* Remove the temporary roots file for this process.  Any temporary
    root becomes garbage after this point unless it has been registered