From fe446f8bb4aca0c63fca176dfa2e7be75c5ae360 Mon Sep 17 00:00:00 2001
From: Florian Klink <flokli@flokli.de>
Date: Thu, 14 Dec 2023 18:53:01 +0200
Subject: [PATCH 1/2] nixos/udev: allow /bin/sh in udev rules

Using `/bin/sh` in udev rules is fine (as it's guaranteed to point to a
(bash) shell on NixOS), and actually is better than hardcoding absolute
paths, at least in cases where these rules are also added to the
(systemd-based) initrd (via boot.initrd.services.udev.rules).

To allow this, we need to update the check routine that assembles the
list of files needing fixup, to explicitly exclude `/bin/sh` occurences.

To do this, we convert the pattern to a PCRE regex (which requires "/"
to be escaped), and add `(?!/bin/sh\b)` as a negative lookahead.

This subsequently allows udev rules to (start using) `/bin/sh` again, so
they'll work in-initrd.
---
 nixos/modules/services/hardware/udev.nix | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/services/hardware/udev.nix b/nixos/modules/services/hardware/udev.nix
index 311f60795bae..670b9087f110 100644
--- a/nixos/modules/services/hardware/udev.nix
+++ b/nixos/modules/services/hardware/udev.nix
@@ -112,7 +112,8 @@ let
       echo "OK"
 
       filesToFixup="$(for i in "$out"/*; do
-        grep -l '\B\(/usr\)\?/s\?bin' "$i" || :
+        # list all files referring to (/usr)/bin paths, but allow references to /bin/sh.
+        grep -P -l '\B(?!\/bin\/sh\b)(\/usr)?\/bin(?:\/.*)?' "$i" || :
       done)"
 
       if [ -n "$filesToFixup" ]; then

From 74461420f9412c02dff402b7701e303ba852c4cf Mon Sep 17 00:00:00 2001
From: Florian Klink <flokli@flokli.de>
Date: Thu, 14 Dec 2023 19:09:57 +0200
Subject: [PATCH 2/2] bcache-tools: don't patch path to /bin/sh

This will make these udev rules not work in the systemd-based initrd,
which only has /bin/sh.
---
 pkgs/tools/filesystems/bcache-tools/default.nix | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/pkgs/tools/filesystems/bcache-tools/default.nix b/pkgs/tools/filesystems/bcache-tools/default.nix
index f6dfdd84d8c4..58f6a05992e9 100644
--- a/pkgs/tools/filesystems/bcache-tools/default.nix
+++ b/pkgs/tools/filesystems/bcache-tools/default.nix
@@ -35,10 +35,6 @@ stdenv.mkDerivation rec {
     "UDEVLIBDIR=${placeholder "out"}/lib/udev/"
   ];
 
-  preBuild = ''
-    sed -e "s|/bin/sh|${bash}/bin/sh|" -i *.rules
-  '';
-
   preInstall = ''
     mkdir -p "$out/sbin" "$out/lib/udev/rules.d" "$out/share/man/man8"
   '';