From d9f07dcee585db581688a72d3bcbea2b15794836 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@sap.com>
Date: Mon, 30 Jan 2023 16:52:43 +0100
Subject: [PATCH 1/2] nixos/envfs: use configured environment.usrbinenv and
 environment.binsh

Taken from upstream
https://github.com/Mic92/envfs/commit/d91aeefccb4485646be9415c9e5d1d3599eb5199
---
 nixos/modules/tasks/filesystems/envfs.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/tasks/filesystems/envfs.nix b/nixos/modules/tasks/filesystems/envfs.nix
index 450b805f0f580a6..df4ce12407bd99d 100644
--- a/nixos/modules/tasks/filesystems/envfs.nix
+++ b/nixos/modules/tasks/filesystems/envfs.nix
@@ -9,8 +9,8 @@ let
       options = [
         "fallback-path=${pkgs.runCommand "fallback-path" {} ''
           mkdir -p $out
-          ln -s ${pkgs.coreutils}/bin/env $out/env
-          ln -s ${config.system.build.binsh}/bin/sh $out/sh
+          ln -s ${config.environment.usrbinenv} $out/env
+          ln -s ${config.environment.binsh} $out/sh
         ''}"
       ];
     };

From 1c664befd4c198db2c6993f8afde709024bcec6d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@sap.com>
Date: Mon, 30 Jan 2023 16:53:08 +0100
Subject: [PATCH 2/2] nixos/envfs: add extraFallbackPathCommands options

this is mainly useful for restricted platforms like wsl which require
some extra entries in /bin/
---
 nixos/modules/tasks/filesystems/envfs.nix | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/nixos/modules/tasks/filesystems/envfs.nix b/nixos/modules/tasks/filesystems/envfs.nix
index df4ce12407bd99d..76344f5f87eafde 100644
--- a/nixos/modules/tasks/filesystems/envfs.nix
+++ b/nixos/modules/tasks/filesystems/envfs.nix
@@ -7,11 +7,11 @@ let
       device = "none";
       fsType = "envfs";
       options = [
-        "fallback-path=${pkgs.runCommand "fallback-path" {} ''
+        "fallback-path=${pkgs.runCommand "fallback-path" {} (''
           mkdir -p $out
           ln -s ${config.environment.usrbinenv} $out/env
           ln -s ${config.environment.binsh} $out/sh
-        ''}"
+        '' + cfg.extraFallbackPathCommands)}"
       ];
     };
     "/bin" = {
@@ -31,11 +31,19 @@ in {
           etc.
         '';
       };
+
       package = lib.mkOption {
         type = lib.types.package;
-        description = lib.mdDoc "Which package to use for the envfs.";
         default = pkgs.envfs;
         defaultText = lib.literalExpression "pkgs.envfs";
+        description = lib.mdDoc "Which package to use for the envfs.";
+      };
+
+      extraFallbackPathCommands = lib.mkOption {
+        type = lib.types.lines;
+        default = "";
+        example = "ln -s $''{pkgs.bash}/bin/bash $out/bash";
+        description = lib.mdDoc "Extra commands to run in the package that contains fallback executables in case not other executable is found";
       };
     };
   };