utils/shell-wrapper: hardcode paths to the right sh/env executables (#459)

utils/default.nix

@@ -1,8 +1,13 @@
-{ rustPlatform }:
+{ rustPlatform, bash, coreutils }:
 rustPlatform.buildRustPackage {
   pname = "nixos-wsl-utils";
   version = "1.0.0";
 
   src = ./.;
   cargoLock.lockFile = ./Cargo.lock;
+
+  env = {
+    NIXOS_WSL_SH = "${bash}/bin/sh";
+    NIXOS_WSL_ENV = "${coreutils}/bin/env";
+  };
 }

utils/src/shell_wrapper.rs

@@ -19,8 +19,11 @@ fn real_main() -> anyhow::Result<()> {
     // Skip if environment was already set
     if env::var_os("__NIXOS_SET_ENVIRONMENT_DONE") != Some("1".into()) {
         // Load the environment from /etc/set-environment
-        let output = Command::new("/bin/sh")
-            .args(&["-c", ". /etc/set-environment && /usr/bin/env -0"])
+        let output = Command::new(env!("NIXOS_WSL_SH"))
+            .args(&[
+                "-c",
+                &format!(". /etc/set-environment && {} -0", env!("NIXOS_WSL_ENV")),
+            ])
             .output()
             .context("when reading /etc/set-environment")?;