Add a "root" parameter to local stores

This makes it easier to create a diverted store, i.e.

  NIX_REMOTE="local?root=/tmp/root"

instead of

  NIX_REMOTE="local?real=/tmp/root/nix/store&state=/tmp/root/nix/var/nix" NIX_LOG_DIR=/tmp/root/nix/var/log

1 files changed, 6 insertions, 2 deletions

diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 8532101a174d..e8b56f929b13 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -483,6 +483,10 @@ static void opReadLog(Strings opFlags, Strings opArgs)
 
     RunPager pager;
 
+    // FIXME: move getting logs into Store.
+    auto store2 = std::dynamic_pointer_cast<LocalFSStore>(store);
+    if (!store2) throw Error(format("store ‘%s’ does not support reading logs") % store->getUri());
+
     for (auto & i : opArgs) {
         Path path = useDeriver(store->followLinksToStorePath(i));
 
@@ -493,8 +497,8 @@ static void opReadLog(Strings opFlags, Strings opArgs)
 
             Path logPath =
                 j == 0
-                ? (format("%1%/%2%/%3%/%4%") % settings.nixLogDir % drvsLogDir % string(baseName, 0, 2) % string(baseName, 2)).str()
-                : (format("%1%/%2%/%3%") % settings.nixLogDir % drvsLogDir % baseName).str();
+                ? (format("%1%/%2%/%3%/%4%") % store2->logDir % drvsLogDir % string(baseName, 0, 2) % string(baseName, 2)).str()
+                : (format("%1%/%2%/%3%") % store2->logDir % drvsLogDir % baseName).str();
             Path logBz2Path = logPath + ".bz2";
 
             if (pathExists(logPath)) {