From e7c3399ed2e62ecf8a0fb5294f19ffab2061cc04 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 9 May 2023 10:40:10 -0400
Subject: [PATCH] Specialize `LocalOverlayStore::queryPathFromHashPart`

With test
---
 src/libstore/local-overlay-store.cc | 10 ++++++++++
 src/libstore/local-overlay-store.hh |  2 ++
 tests/overlay-local-store/inner.sh  |  8 ++++++++
 3 files changed, 20 insertions(+)

diff --git a/src/libstore/local-overlay-store.cc b/src/libstore/local-overlay-store.cc
index ad1947698..cb409c2bd 100644
--- a/src/libstore/local-overlay-store.cc
+++ b/src/libstore/local-overlay-store.cc
@@ -98,6 +98,16 @@ bool LocalOverlayStore::isValidPathUncached(const StorePath & path)
 }
 
 
+std::optional<StorePath> LocalOverlayStore::queryPathFromHashPart(const std::string & hashPart)
+{
+    auto res = LocalStore::queryPathFromHashPart(hashPart);
+    if (res)
+        return res;
+    else
+        return lowerStore->queryPathFromHashPart(hashPart);
+}
+
+
 void LocalOverlayStore::registerValidPaths(const ValidPathInfos & infos)
 {
     // First, get any from lower store so we merge
diff --git a/src/libstore/local-overlay-store.hh b/src/libstore/local-overlay-store.hh
index daebe8547..88da4ba4a 100644
--- a/src/libstore/local-overlay-store.hh
+++ b/src/libstore/local-overlay-store.hh
@@ -89,6 +89,8 @@ private:
 
     bool isValidPathUncached(const StorePath & path) override;
 
+    std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override;
+
     void registerValidPaths(const ValidPathInfos & infos) override;
 
     void addToStore(const ValidPathInfo & info, Source & source,
diff --git a/tests/overlay-local-store/inner.sh b/tests/overlay-local-store/inner.sh
index dc8ec8c2c..279f005a9 100755
--- a/tests/overlay-local-store/inner.sh
+++ b/tests/overlay-local-store/inner.sh
@@ -60,6 +60,14 @@ nix-store --verify-path --store "$storeA" "$path"
 # Verifying path in merged-store
 nix-store --verify-path --store "$storeB" "$path"
 
+hashPart=$(echo $path | sed "s^$NIX_STORE_DIR/^^" | sed 's/-.*//')
+
+# Lower store can find from hash part
+[[ $(nix store --store $storeA path-from-hash-part $hashPart) == $path ]]
+
+# merged store can find from hash part
+[[ $(nix store --store $storeB path-from-hash-part $hashPart) == $path ]]
+
 ### Do a redundant add
 
 # upper layer should not have it