Unify environment configuration and don't run in child shells

This should enable `nix run` to work under shells like fish and zsh,
as well as making child shells not needlessly reset any environment
that should be inherited.

Implementation adapted from NixOS.

modules/environment/default.nix

@@ -184,6 +184,10 @@ in {
     };
 
     system.build.setEnvironment = pkgs.writeText "set-environment" ''
+      # Prevent this file from being sourced by child shells.
+      export __NIX_DARWIN_SET_ENVIRONMENT_DONE=1
+
+      export PATH=${config.environment.systemPath}
       ${concatStringsSep "\n" exportVariables}
 
       # Extra initialisation

modules/programs/bash/default.nix

@@ -61,8 +61,9 @@ in
       # Don't execute this file when running in a pure nix-shell.
       if test -n "$IN_NIX_SHELL"; then return; fi
 
-      export PATH=${config.environment.systemPath}
-      ${config.system.build.setEnvironment.text}
+      if [ -z "$__NIX_DARWIN_SET_ENVIRONMENT_DONE" ]; then
+        . ${config.system.build.setEnvironment}
+      fi
 
       # Return early if not running interactively, but after basic nix setup.
       [[ $- != *i* ]] && return

modules/programs/fish.nix

@@ -109,8 +109,9 @@ in
       set fish_function_path ${pkgs.fish-foreign-env}/share/fish-foreign-env/functions $__fish_datadir/functions
       
       # source the NixOS environment config
-      fenv export PATH=${config.environment.systemPath}
-      fenv source ${config.system.build.setEnvironment}
+      if [ -z "$__NIX_DARWIN_SET_ENVIRONMENT_DONE" ]
+          fenv source ${config.system.build.setEnvironment}
+      end
 
       # clear fish_function_path so that it will be correctly set when we return to $__fish_datadir/config.fish
       set -e fish_function_path

modules/programs/zsh/default.nix

@@ -120,8 +120,9 @@ in
       # Don't execute this file when running in a pure nix-shell.
       if test -n "$IN_NIX_SHELL"; then return; fi
 
-      export PATH=${config.environment.systemPath}
-      ${config.system.build.setEnvironment.text}
+      if [ -z "$__NIX_DARWIN_SET_ENVIRONMENT_DONE" ]; then
+        . ${config.system.build.setEnvironment}
+      fi
 
       ${cfg.shellInit}
 
@@ -158,9 +159,6 @@ in
       if [ -n "$__ETC_ZSHRC_SOURCED" -o -n "$NOSYSZSHRC" ]; then return; fi
       __ETC_ZSHRC_SOURCED=1
 
-      # Also set to fix `nix run` shells.
-      __ETC_BASHRC_SOURCED=1
-
       # history defaults
       SAVEHIST=2000
       HISTSIZE=2000

release.nix

@@ -108,10 +108,11 @@ let
     tests.services-synergy = makeTest ./tests/services-synergy.nix;
     tests.services-privoxy = makeTest ./tests/services-privoxy.nix;
     tests.system-defaults-write = makeTest ./tests/system-defaults-write.nix;
+    tests.system-environment-bash = makeTest ./tests/system-environment-bash.nix;
+    tests.system-environment-fish = makeTest ./tests/system-environment-fish.nix;
     tests.system-keyboard-mapping = makeTest ./tests/system-keyboard-mapping.nix;
     tests.system-packages = makeTest ./tests/system-packages.nix;
-    tests.system-path-bash = makeTest ./tests/system-path-bash.nix;
-    tests.system-path-fish = makeTest ./tests/system-path-fish.nix;
+    tests.system-path = makeTest ./tests/system-path.nix;
     tests.system-shells = makeTest ./tests/system-shells.nix;
     tests.users-groups = makeTest ./tests/users-groups.nix;
     tests.fonts = makeTest ./tests/fonts.nix;

tests/environment-path.nix

@@ -3,13 +3,11 @@
 with lib;
 
 {
-  programs.bash.enable = true;
-
   test = ''
-    echo checking /run/current-system/sw/bin in systemPath >&2
-    grep 'export PATH=.*:/run/current-system/sw/bin' ${config.out}/etc/bashrc
+    echo checking /run/current-system/sw/bin in setEnvironment >&2
+    grep 'export PATH=.*:/run/current-system/sw/bin' ${config.system.build.setEnvironment}
 
-    echo checking /bin and /sbin in systemPath >&2
-    grep 'export PATH=.*:/usr/bin:/usr/sbin:/bin:/sbin' ${config.out}/etc/bashrc
+    echo checking /bin and /sbin in setEnvironment >&2
+    grep 'export PATH=.*:/usr/bin:/usr/sbin:/bin:/sbin' ${config.system.build.setEnvironment}
   '';
 }

tests/programs-zsh.nix

@@ -20,10 +20,10 @@
      echo >&2 "checking for share/zsh in /sw"
      test -e ${config.out}/sw/share/zsh
 
-     echo >&2 "checking environment.systemPath in /etc/zshenv"
-     grep 'export PATH=${pkgs.hello}/bin' ${config.out}/etc/zshenv
-     echo >&2 "checking SHELL in /etc/zshenv"
-     grep 'export SHELL="${pkgs.zsh}/bin/zsh"' ${config.out}/etc/zshenv
+     echo >&2 "checking setEnvironment in /etc/zshenv"
+     fgrep '. ${config.system.build.setEnvironment}' ${config.out}/etc/zshenv
+     echo >&2 "checking SHELL in setEnvironment"
+     grep 'export SHELL="${pkgs.zsh}/bin/zsh"' ${config.system.build.setEnvironment}
      echo >&2 "checking nix-shell return /etc/zshenv"
      grep 'if test -n "$IN_NIX_SHELL"; then return; fi' ${config.out}/etc/zshenv
      echo >&2 "checking zshenv.d in /etc/zshenv"

tests/services-nix-daemon.nix

@@ -8,8 +8,6 @@ in
   services.nix-daemon.enable = true;
   nix.package = nix;
 
-  programs.zsh.enable = true;
-
   test = ''
     echo checking nix-daemon service in /Library/LaunchDaemons >&2
     grep "<string>org.nixos.nix-daemon</string>" ${config.out}/Library/LaunchDaemons/org.nixos.nix-daemon.plist
@@ -20,9 +18,7 @@ in
     echo checking nix-daemon reload in /activate >&2
     grep "pkill -HUP nix-daemon" ${config.out}/activate
 
-    echo checking NIX_REMOTE=daemon in /etc/bashrc >&2
-    grep "NIX_REMOTE=daemon" ${config.out}/etc/bashrc
-    echo "checking NIX_REMOTE=daemon in /etc/zshenv" >&2
-    grep 'export NIX_REMOTE=daemon' ${config.out}/etc/zshenv
+    echo checking NIX_REMOTE=daemon in setEnvironment >&2
+    grep "NIX_REMOTE=daemon" ${config.system.build.setEnvironment}
   '';
 }

tests/system-environment-bash.nix

@@ -0,0 +1,10 @@
+{ config, pkgs, ... }:
+
+{
+   programs.bash.enable = true;
+
+   test = ''
+     echo checking setEnvironment in /etc/bashrc >&2
+     fgrep '. ${config.system.build.setEnvironment}' ${config.out}/etc/bashrc
+   '';
+}

tests/system-environment-fish.nix

@@ -0,0 +1,10 @@
+{ config, pkgs, ... }:
+
+{
+   programs.fish.enable = true;
+
+   test = ''
+     echo checking setEnvironment in /etc/fish/config.fish >&2
+     grep 'fenv source ${config.system.build.setEnvironment}' ${config.out}/etc/fish/nixos-env-preinit.fish
+   '';
+}

tests/system-path.nix

@@ -0,0 +1,10 @@
+{ config, pkgs, ... }:
+
+{
+   environment.systemPath = [ pkgs.hello ];
+
+   test = ''
+     echo checking systemPath in setEnvironment >&2
+     grep 'export PATH=${pkgs.hello}/bin' ${config.system.build.setEnvironment}
+   '';
+}