From c5a4dfa6602796ebb3c62493a2fd33f2b58ec91c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 9 Sep 2024 15:41:38 +0200
Subject: [PATCH] nix flake {metadata,archive}: Fix chroot stores

Fixes

  $ nix flake metadata --store /tmp/nix nixpkgs
  error: path '/tmp/nix/nix/store/65xpqkz92d9j7k5ric4z8lzhiigxsfbg-source/flake.nix' is not in the Nix store

This has been broken since 598deb2b23bc59df61c92ea25745d675686f3991.
---
 src/libflake/flake/flake.cc       | 27 ++++++++++++++++-----------
 src/libflake/flake/flake.hh       | 10 ++++++++++
 src/nix/flake.cc                  |  4 ++--
 tests/functional/flakes/flakes.sh |  3 +++
 4 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/src/libflake/flake/flake.cc b/src/libflake/flake/flake.cc
index fd1183514..35db13f7e 100644
--- a/src/libflake/flake/flake.cc
+++ b/src/libflake/flake/flake.cc
@@ -751,6 +751,21 @@ LockedFlake lockFlake(
     }
 }
 
+std::pair<StorePath, Path> sourcePathToStorePath(
+    ref<Store> store,
+    const SourcePath & _path)
+{
+    auto path = _path.path.abs();
+
+    if (auto store2 = store.dynamic_pointer_cast<LocalFSStore>()) {
+        auto realStoreDir = store2->getRealStoreDir();
+        if (isInDir(path, realStoreDir))
+            path = store2->storeDir + path.substr(realStoreDir.size());
+    }
+
+    return store->toStorePath(path);
+}
+
 void callFlake(EvalState & state,
     const LockedFlake & lockedFlake,
     Value & vRes)
@@ -768,17 +783,7 @@ void callFlake(EvalState & state,
 
         auto lockedNode = node.dynamic_pointer_cast<const LockedNode>();
 
-        // FIXME: This is a hack to support chroot stores. Remove this
-        // once we can pass a sourcePath rather than a storePath to
-        // call-flake.nix.
-        auto path = sourcePath.path.abs();
-        if (auto store = state.store.dynamic_pointer_cast<LocalFSStore>()) {
-            auto realStoreDir = store->getRealStoreDir();
-            if (isInDir(path, realStoreDir))
-                path = store->storeDir + path.substr(realStoreDir.size());
-        }
-
-        auto [storePath, subdir] = state.store->toStorePath(path);
+        auto [storePath, subdir] = sourcePathToStorePath(state.store, sourcePath);
 
         emitTreeAttrs(
             state,
diff --git a/src/libflake/flake/flake.hh b/src/libflake/flake/flake.hh
index cce17009c..496e18673 100644
--- a/src/libflake/flake/flake.hh
+++ b/src/libflake/flake/flake.hh
@@ -214,6 +214,16 @@ void callFlake(
     const LockedFlake & lockedFlake,
     Value & v);
 
+/**
+ * Map a `SourcePath` to the corresponding store path. This is a
+ * temporary hack to support chroot stores while we don't have full
+ * lazy trees. FIXME: Remove this once we can pass a sourcePath rather
+ * than a storePath to call-flake.nix.
+ */
+std::pair<StorePath, Path> sourcePathToStorePath(
+    ref<Store> store,
+    const SourcePath & path);
+
 }
 
 void emitTreeAttrs(
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 2db1e039e..8e109b327 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -214,7 +214,7 @@ struct CmdFlakeMetadata : FlakeCommand, MixJSON
         auto & flake = lockedFlake.flake;
 
         // Currently, all flakes are in the Nix store via the rootFS accessor.
-        auto storePath = store->printStorePath(store->toStorePath(flake.path.path.abs()).first);
+        auto storePath = store->printStorePath(sourcePathToStorePath(store, flake.path).first);
 
         if (json) {
             nlohmann::json j;
@@ -1079,7 +1079,7 @@ struct CmdFlakeArchive : FlakeCommand, MixJSON, MixDryRun
 
         StorePathSet sources;
 
-        auto storePath = store->toStorePath(flake.flake.path.path.abs()).first;
+        auto storePath = sourcePathToStorePath(store, flake.flake.path).first;
 
         sources.insert(storePath);
 
diff --git a/tests/functional/flakes/flakes.sh b/tests/functional/flakes/flakes.sh
index 26b91eda7..aa4cb1e18 100755
--- a/tests/functional/flakes/flakes.sh
+++ b/tests/functional/flakes/flakes.sh
@@ -184,6 +184,9 @@ nix registry list | grepInverse '^user' # nothing in user registry
 nix flake metadata flake1
 nix flake metadata flake1 | grepQuiet 'Locked URL:.*flake1.*'
 
+# Test 'nix flake metadata' on a chroot store.
+nix flake metadata --store $TEST_ROOT/chroot-store flake1
+
 # Test 'nix flake metadata' on a local flake.
 (cd "$flake1Dir" && nix flake metadata) | grepQuiet 'URL:.*flake1.*'
 (cd "$flake1Dir" && nix flake metadata .) | grepQuiet 'URL:.*flake1.*'