From 225fc6fe51940da23103d4136e490913953d3994 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Fri, 10 Mar 2023 18:40:45 +0000
Subject: [PATCH] configurable busybox

allows modules to add to the busybox applets and change config
---
 default.nix                              |  1 +
 modules/base.nix                         | 10 +--
 modules/busybox.nix                      | 85 ++++++++++++++++++++++++
 modules/s6/default.nix                   |  3 +-
 modules/wlan.nix                         |  5 +-
 pkgs/liminix-tools/networking/pppoe.nix  |  1 -
 pkgs/liminix-tools/networking/udhcpc.nix |  3 +-
 pkgs/liminix-tools/services/default.nix  |  3 +-
 pkgs/s6-init-bin/default.nix             |  3 +-
 pkgs/write-ash-script/default.nix        |  7 +-
 10 files changed, 101 insertions(+), 20 deletions(-)
 create mode 100644 modules/busybox.nix

diff --git a/default.nix b/default.nix
index 0f96a55..0876baa 100644
--- a/default.nix
+++ b/default.nix
@@ -22,6 +22,7 @@ let
       { _module.args = { inherit pkgs; lib = pkgs.lib; }; }
       ./modules/hardware.nix
       ./modules/base.nix
+      ./modules/busybox.nix
       ./modules/hostname.nix
       device.module
       liminix-config
diff --git a/modules/base.nix b/modules/base.nix
index 18df6db..ef7e60d 100644
--- a/modules/base.nix
+++ b/modules/base.nix
@@ -2,7 +2,7 @@
 let
   inherit (lib) mkEnableOption mkOption types isDerivation hasAttr ;
   inherit (pkgs.pseudofile) dir symlink;
-  inherit (pkgs) busybox;
+#  inherit (pkgs) busybox;
   inherit (pkgs.liminix.networking) address interface;
   inherit (pkgs.liminix.services) bundle;
 
@@ -46,7 +46,7 @@ in {
   };
   config = {
     defaultProfile.packages = with pkgs;
-      [ s6 s6-init-bin busybox execline s6-linux-init s6-rc ];
+      [ s6 s6-init-bin execline s6-linux-init s6-rc ];
 
     hardware.networkInterfaces = {
       lo =
@@ -113,10 +113,6 @@ in {
     };
 
     filesystem = dir {
-      bin = dir {
-        sh = symlink "${busybox}/bin/sh";
-        busybox = symlink "${busybox}/bin/busybox";
-      };
       dev =
         let node = type: major: minor: mode : { inherit type major minor mode; };
         in dir {
@@ -129,7 +125,7 @@ in {
       etc = dir {
         profile = symlink
           (pkgs.writeScript ".profile" ''
-            PATH=${lib.makeBinPath config.defaultProfile.packages}
+            PATH=${lib.makeBinPath config.defaultProfile.packages}:/bin
             export PATH
           '');
       };
diff --git a/modules/busybox.nix b/modules/busybox.nix
new file mode 100644
index 0000000..503c01d
--- /dev/null
+++ b/modules/busybox.nix
@@ -0,0 +1,85 @@
+{ lib, pkgs, config, ...}:
+let
+  inherit (lib) mkOption mkEnableOption types mapAttrsToList;
+  inherit (pkgs.pseudofile) dir symlink;
+  inherit (lib.strings) toUpper;
+
+  attrs = { options, applets } :
+    let
+      extraOptions = builtins.concatStringsSep "\n"
+        (mapAttrsToList (n: v: "CONFIG_${toUpper n} ${toString v}") options);
+      appletOptions = builtins.concatStringsSep "\n"
+        (map (n: "CONFIG_${toUpper n} y") applets);
+    in {
+      enableMinimal = true;
+      extraConfig = ''
+        ${extraOptions}
+        ${appletOptions}
+      '';
+    };
+  cfg = config.programs.busybox;
+  busybox = pkgs.busybox.override (attrs { inherit (cfg) applets options; });
+  makeLinks = lib.attrsets.genAttrs
+    cfg.applets
+    (a: symlink "${busybox}/bin/busybox");
+  minimalApplets = [
+    # this is probably less minimal than it could be "arch" "ash"
+    "base64" "basename" "bc" "brctl" "bunzip2"
+    "bzcat" "bzip2" "cal" "cat" "chattr" "chgrp" "chmod" "chown"
+    "chpst" "chroot" "clear" "cmp" "comm" "cp" "cpio" "cut" "date"
+    "dd" "df" "dirname" "dmesg" "du" "echo" "egrep" "env" "expand"
+    "expr" "false" "fdisk" "fgrep" "find" "free" "fuser" "grep"
+    "gunzip" "gzip" "head" "hexdump" "hostname" "hwclock" "ifconfig"
+    "ip" "iplink" "ipneigh" "iproute" "iprule" "kill" "killall"
+    "killall5" "less" "ln" "ls" "lsattr" "lsof" "md5sum" "mkdir"
+    "mknod" "mktemp" "mount" "mv" "nc" "netstat" "nohup" "od" "pgrep"
+    "pidof" "ping" "ping6" "pkill" "pmap" "printenv" "printf" "ps"
+    "pwd" "readlink" "realpath" "reset" "rm" "rmdir" "route" "sed"
+    "seq" "setsid" "sha1sum" "sha256sum" "sha512sum" "sleep" "sort"
+    "stat" "strings" "stty" "su" "sum" "swapoff" "swapon" "sync"
+    "tail" "tee" "test" "time" "touch" "tr" "traceroute"
+    "traceroute6" "true" "truncate" "tty" "udhcpc" "udhcpc6" "umount"
+    "uname" "unexpand" "uniq" "unlink" "unlzma" "unxz" "unzip"
+    "uptime" "watch" "wc" "whoami" "xargs" "xxd" "xz" "xzcat" "yes"
+    "zcat"
+  ];
+in {
+  options = {
+    programs.busybox = {
+      applets =  mkOption {
+        type = types.listOf types.str;
+        default = [];
+        example = ["sh" "getty" "login"];
+      };
+      options = mkOption {
+        # mostly the values are y n or m, but sometimes
+        # other strings are also used
+        type = types.attrsOf types.nonEmptyStr;
+        default =  { };
+      };
+    };
+  };
+  config = {
+    programs.busybox = {
+      applets = minimalApplets;
+      options = {
+        ASH_ECHO = "y";
+        # ASH_OPTIMIZE_FOR_SIZE = "y";
+        BASH_IS_NONE = "y";
+        SH_IS_ASH = "y";
+        ASH_BASH_COMPAT = "y";
+        FEATURE_EDITING = "y"; # readline-ish command editing
+        FEATURE_EDITING_HISTORY = "128";
+        FEATURE_EDITING_MAX_LEN = "1024";
+        FEATURE_TAB_COMPLETION = "y";
+        FEATURE_EDITING_WINCH = "y";
+      };
+    };
+    filesystem = dir {
+      bin = dir ({
+        busybox = symlink "${busybox}/bin/busybox";
+        sh = symlink "${busybox}/bin/busybox";
+      } // makeLinks);
+    };
+  };
+}
diff --git a/modules/s6/default.nix b/modules/s6/default.nix
index 064621c..75253ed 100644
--- a/modules/s6/default.nix
+++ b/modules/s6/default.nix
@@ -73,7 +73,7 @@ let
       run = {
         file = ''
               #!${execline}/bin/execlineb -P
-              ${busybox}/bin/getty -l ${busybox}/bin/login 115200 /dev/console
+              /bin/getty -l /bin/login 115200 /dev/console
           '';
         mode = "0755";
       };
@@ -134,6 +134,7 @@ let
   };
 in {
   config = {
+    programs.busybox.applets = [ "login" "getty" ];
     filesystem = dir {
       etc = dir {
         s6-rc = dir {
diff --git a/modules/wlan.nix b/modules/wlan.nix
index 4af730a..6e62dda 100644
--- a/modules/wlan.nix
+++ b/modules/wlan.nix
@@ -2,7 +2,7 @@
 let
   inherit (lib) mkEnableOption mkOption types isDerivation hasAttr ;
   inherit (pkgs.pseudofile) dir symlink;
-  inherit (pkgs) stdenv busybox wireless-regdb;
+  inherit (pkgs) stdenv wireless-regdb;
   regulatory = stdenv.mkDerivation {
     name = "regulatory.db";
     phases = ["installPhase"];
@@ -20,6 +20,9 @@ in {
         };
       };
     };
+    programs.busybox.applets = [
+      "insmod" "rmmod"
+    ];
     kernel = rec {
       config = {
         # Most of this is necessary infra to allow wireless stack/
diff --git a/pkgs/liminix-tools/networking/pppoe.nix b/pkgs/liminix-tools/networking/pppoe.nix
index d5c5d69..402a416 100644
--- a/pkgs/liminix-tools/networking/pppoe.nix
+++ b/pkgs/liminix-tools/networking/pppoe.nix
@@ -1,7 +1,6 @@
 {
   liminix
 , lib
-, busybox
 , ppp
 , pppoe
 , writeAshScript
diff --git a/pkgs/liminix-tools/networking/udhcpc.nix b/pkgs/liminix-tools/networking/udhcpc.nix
index ee9ed47..002184e 100644
--- a/pkgs/liminix-tools/networking/udhcpc.nix
+++ b/pkgs/liminix-tools/networking/udhcpc.nix
@@ -1,6 +1,5 @@
 {
   liminix
-, busybox
 , writeAshScript
 , serviceFns
 } :
@@ -43,7 +42,7 @@ let
   '';
 in longrun {
   inherit name;
-  run = "${busybox}/bin/udhcpc -f -i ${interface.device} -x hostname:$(cat /proc/sys/kernel/hostname) -s ${script}";
+  run = "/bin/udhcpc -f -i ${interface.device} -x hostname:$(cat /proc/sys/kernel/hostname) -s ${script}";
   notification-fd = 10;
   dependencies = [ interface ] ++ dependencies;
 }
diff --git a/pkgs/liminix-tools/services/default.nix b/pkgs/liminix-tools/services/default.nix
index b2cb939..138e77e 100644
--- a/pkgs/liminix-tools/services/default.nix
+++ b/pkgs/liminix-tools/services/default.nix
@@ -3,7 +3,6 @@
 , s6-rc
 , s6
 , lib
-, busybox
 , callPackage
 , writeScript
 , serviceFns
@@ -12,7 +11,7 @@ let
   inherit (builtins) concatStringsSep;
   output = service: name: "/run/service-state/${service.name}/${name}";
   serviceScript = commands : ''
-    #!${busybox}/bin/sh
+    #!/bin/sh
     exec 2>&1
     . ${serviceFns}
     ${commands}
diff --git a/pkgs/s6-init-bin/default.nix b/pkgs/s6-init-bin/default.nix
index 3feed91..c43feaf 100644
--- a/pkgs/s6-init-bin/default.nix
+++ b/pkgs/s6-init-bin/default.nix
@@ -4,7 +4,6 @@
 , writeScript
 , stdenvNoCC
 , lib
-, busybox
 , s6-rc
 }:
 let
@@ -14,7 +13,7 @@ let
   '';
   init = writeScript "init" ''
     #!${execline}/bin/execlineb -S0
-    ${s6-linux-init}/bin/s6-linux-init -c /etc/s6-linux-init/current -m 0022 -p ${lib.makeBinPath [busybox execline s6-linux-init s6-rc]}:/usr/bin:/bin -d /dev -- "\$@"
+    ${s6-linux-init}/bin/s6-linux-init -c /etc/s6-linux-init/current -m 0022 -p ${lib.makeBinPath [execline s6-linux-init s6-rc]}:/usr/bin:/bin -d /dev -- "\$@"
   '';
 in stdenvNoCC.mkDerivation {
   name = "s6-init-bin";
diff --git a/pkgs/write-ash-script/default.nix b/pkgs/write-ash-script/default.nix
index 2744383..0763a0f 100644
--- a/pkgs/write-ash-script/default.nix
+++ b/pkgs/write-ash-script/default.nix
@@ -1,14 +1,13 @@
 {
-  busybox
-, writeScript
+  writeScript
 , lib
 }
 : name : { runtimeInputs ? [] } : text : writeScript name ''
-#!${busybox}/bin/sh
+#!/bin/sh
 set -o errexit
 set -o nounset
 set -o pipefail
 
-export PATH="${lib.makeBinPath ([ busybox ] ++ runtimeInputs)}:$PATH"
+export PATH="${lib.makeBinPath runtimeInputs}:$PATH"
 ${text}
 ''