nixos/ldso: init module

nixos/modules/config/ldso.nix

@@ -0,0 +1,58 @@
+{ config, lib, pkgs, ... }:
+
+let
+  inherit (lib) last splitString mkOption types mdDoc optionals;
+
+  libDir = pkgs.stdenv.hostPlatform.libDir;
+  ldsoBasename = last (splitString "/" pkgs.stdenv.cc.bintools.dynamicLinker);
+
+  pkgs32 = pkgs.pkgsi686Linux;
+  libDir32 = pkgs32.stdenv.hostPlatform.libDir;
+  ldsoBasename32 = last (splitString "/" pkgs32.stdenv.cc.bintools.dynamicLinker);
+in {
+  options = {
+    environment.ldso = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = mdDoc ''
+        The executable to link into the normal FHS location of the ELF loader.
+      '';
+    };
+
+    environment.ldso32 = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = mdDoc ''
+        The executable to link into the normal FHS location of the 32-bit ELF loader.
+
+        This currently only works on x86_64 architectures.
+      '';
+    };
+  };
+
+  config = {
+    assertions = [
+      { assertion = isNull config.environment.ldso32 || pkgs.stdenv.isx86_64;
+        message = "Option environment.ldso32 currently only works on x86_64.";
+      }
+    ];
+
+    systemd.tmpfiles.rules = (
+      if isNull config.environment.ldso then [
+        "r /${libDir}/${ldsoBasename} - - - - -"
+      ] else [
+        "d /${libDir} 0755 root root - -"
+        "L+ /${libDir}/${ldsoBasename} - - - - ${config.environment.ldso}"
+      ]
+    ) ++ optionals pkgs.stdenv.isx86_64 (
+      if isNull config.environment.ldso32 then [
+        "r /${libDir32}/${ldsoBasename32} - - - - -"
+      ] else [
+        "d /${libDir32} 0755 root root - -"
+        "L+ /${libDir32}/${ldsoBasename32} - - - - ${config.environment.ldso32}"
+      ]
+    );
+  };
+
+  meta.maintainers = with lib.maintainers; [ tejing ];
+}

nixos/modules/module-list.nix

@@ -12,6 +12,7 @@
   ./config/iproute2.nix
   ./config/krb5/default.nix
   ./config/ldap.nix
+  ./config/ldso.nix
   ./config/locale.nix
   ./config/malloc.nix
   ./config/mysql.nix

nixos/modules/programs/nix-ld.nix

@@ -47,7 +47,7 @@ in
   };
 
   config = lib.mkIf config.programs.nix-ld.enable {
-    systemd.tmpfiles.packages = [ cfg.package ];
+    environment.ldso = "${cfg.package}/libexec/nix-ld";
 
     environment.systemPackages = [ nix-ld-libraries ];