build-remote.pl: Use ‘nix-store --serve’ on the remote side

This makes things more efficient (we don't need to use an SSH master
connection, and we only start a single remote process) and gets rid of
locking issues (the remote nix-store process will keep inputs and
outputs locked as long as they're needed).

It also makes it more or less secure to connect directly to the root
account on the build machine, using a forced command
(e.g. ‘command="nix-store --serve --write"’). This bypasses the Nix
daemon and is therefore more efficient.

Also, don't call nix-store to import the output paths.

1 files changed, 11 insertions, 0 deletions

diff --git a/perl/lib/Nix/Store.xs b/perl/lib/Nix/Store.xs
index 07ccebe62f51..ff90616d3766 100644
--- a/perl/lib/Nix/Store.xs
+++ b/perl/lib/Nix/Store.xs
@@ -179,6 +179,17 @@ void exportPaths(int fd, int sign, ...)
         }
 
 
+void importPaths(int fd)
+    PPCODE:
+        try {
+            doInit();
+            FdSource source(fd);
+            store->importPaths(false, source);
+        } catch (Error & e) {
+            croak(e.what());
+        }
+
+
 SV * hashPath(char * algo, int base32, char * path)
     PPCODE:
         try {