Add README, LICENSE and clean up flake.nix

.gitignore

@@ -5,6 +5,7 @@
 !.gitignore
 
 !*.lock
+!*.md
 !*.nix
 !*.zig
 !*.zon

LICENSE.md

@@ -0,0 +1,21 @@
+# MIT License
+
+Copyright (c) 2024-present RGBCube
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,86 @@
+# crash
+
+A user-configurable login shell wrapper.
+
+Crash is a super lightweight shim that executes the shells that are seperated by `:`
+in your `SHELLS` environment variable in order, halting execution if one exits
+sucessfully (with a 0 exit code).
+
+If you don't have anything in your `SHELLS` environment variable, Crash will
+use the fallback shell that is configured at compile time (by default, this is
+`bashInteractive` from nixpkgs, however you can change this by overriding the
+`fallbackShell` call option).
+
+## Why?
+
+- To allow users to configure their own shells without superuser access.
+- To have a fallback shell in case your primary one breaks (especially useful when
+  using new unstable shells like Nushell).
+
+## Installation
+
+Simply add this repository to your inputs like so:
+
+```nix
+{
+  inputs.crash = {
+    url                    = "github:RGBCube/crash";
+    inputs.nixpkgs.follows = "nixpkgs";
+  };
+}
+```
+
+And then you can set the package as your default user
+shell like so, in a NixOS module:
+
+```nix
+{
+  outputs = { nixpkgs, crash }: {
+    nixosConfigurations.myhostname = nixpkgs.lib.nixosSystem {
+      modules = [
+        ({ pkgs, lib, ... }: {
+          nixpkgs.overlays = [ crash.overlays.default ];
+
+          users.defaultUserShell = pkgs.crash;
+
+          # Here we set our default shells. Nushell will be tried first, if that
+          # exits with an error, fish will be launched instead. And if fish fails, the
+          # fallback shell, which is pkgs.bashInteractive will get run.
+          environment.sessionVariables.SHELLS = "${lib.getExe pkgs.nushell}:${lib.getExe pkgs.fish}";
+        })
+
+        # Uncomment to make the fallback shell of crash pkgs.dash. Will require a recompilation!
+        # {
+        #   nixpkgs.overlays = [(final: prev: {
+        #     crash = prev.crash.override { fallbackShell = final.dash };
+        #   })];
+        # }
+      ];
+    };
+  }
+}
+```
+
+## License
+
+```
+Copyright (c) 2024-present RGBCube
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+```

flake.nix

@@ -8,21 +8,27 @@
 
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
 
-  outputs = { nixpkgs, ... }: with nixpkgs.lib; foldl' recursiveUpdate {} (map (system: let
+  outputs = { self, nixpkgs }: let
-    pkgs = import nixpkgs { inherit system; };
+    inherit (nixpkgs) lib;
+
+    forEachSystem = lib.genAttrs [ "x86_64-linux" "aarch64-linux" "riscv64-linux" ];
   in {
-    devShell.${system} = pkgs.mkShell {
+    devShell = forEachSystem (system: with nixpkgs.legacyPackages.${system}; mkShell {
-      packages = with pkgs; [
+      packages = [
         zig_0_12
         zls
         zon2nix
       ];
-    };
+    });
 
-    packages.${system} = rec {
+    packages = forEachSystem (system: rec {
-      crash   = pkgs.callPackage ./package.nix {};
+      inherit (self.overlays.crash null nixpkgs.legacyPackages.${system}) crash;
+      default = crash;
+    });
+
+    overlays = rec {
+      crash   = (final: prev: { crash = prev.callPackage ./package.nix {}; });
       default = crash;
     };
-
+  };
-  }) [ "x86_64-linux" "aarch64-linux" "riscv64-linux" ]);
 }

package.nix

@@ -6,8 +6,8 @@
   zig_0_12,
   optimize ? "ReleaseFast",
 
-  bash,
+  bashInteractive,
-  fallbackShell ? bash,
+  fallbackShell ? bashInteractive,
 }:
 
 stdenvNoCC.mkDerivation {