From 6d0f4fa66682331f201f276473ea89d4e8314cfb Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Fri, 21 Nov 2025 00:21:23 +0300
Subject: [PATCH] libutil: Fix copyRecursive and use for nix flake clone

The use of sourceToSink is an unnecessary serialization bottleneck.
While we are at it, fix the copyRecursive implementation to actually copy
the whole directory. It wasn't used for anything prior, but now it has a use
and accompanying tests for flake clone.
---
 src/libfetchers/fetchers.cc | 6 +++---
 src/libutil/fs-sink.cc      | 1 -
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/libfetchers/fetchers.cc b/src/libfetchers/fetchers.cc
index 03d525a61be..7e091ef1071 100644
--- a/src/libfetchers/fetchers.cc
+++ b/src/libfetchers/fetchers.cc
@@ -495,9 +495,9 @@ void InputScheme::clone(
 
     Activity act(*logger, lvlTalkative, actUnknown, fmt("copying '%s' to %s...", input2.to_string(), destDir));
 
-    auto source = sinkToSource([&](Sink & sink) { accessor->dumpPath(CanonPath::root, sink); });
-
-    restorePath(destDir, *source);
+    RestoreSink sink(/*startFsync=*/false);
+    sink.dstPath = destDir;
+    copyRecursive(*accessor, CanonPath::root, sink, CanonPath::root);
 }
 
 std::optional<ExperimentalFeature> InputScheme::experimentalFeature() const
diff --git a/src/libutil/fs-sink.cc b/src/libutil/fs-sink.cc
index 45c0262e620..a78fe1af422 100644
--- a/src/libutil/fs-sink.cc
+++ b/src/libutil/fs-sink.cc
@@ -37,7 +37,6 @@ void copyRecursive(SourceAccessor & accessor, const CanonPath & from, FileSystem
         sink.createDirectory(to, [&](FileSystemObjectSink & dirSink, const CanonPath & relDirPath) {
             for (auto & [name, _] : accessor.readDirectory(from)) {
                 copyRecursive(accessor, from / name, dirSink, relDirPath / name);
-                break;
             }
         });
         break;