From 91731180346ce833dee29665b850b6dc03341a1b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@gmail.com>
Date: Thu, 18 Dec 2025 23:56:48 +0100
Subject: [PATCH] nixos/zfs: assert that zed.enableMail is only being used when
 sendmailSetuidWrapper is enabled
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Otherwise we crash like:

… while selecting an attribute
  at /nix/store/0b202s06rfm1vlyai37gd0zmzxg59qj0-source/nixos/modules/tasks/filesystems/zfs.nix:827:48:
   826|           lib.mkDefault (
   827|             config.security.wrapperDir + "/" + config.services.mail.sendmailSetuidWrapper.program
      |                                                ^
   828|           )

error: expected a set but found null: null
---
 nixos/modules/tasks/filesystems/zfs.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/nixos/modules/tasks/filesystems/zfs.nix b/nixos/modules/tasks/filesystems/zfs.nix
index 861c8ac8081e..0f91848a4bd0 100644
--- a/nixos/modules/tasks/filesystems/zfs.nix
+++ b/nixos/modules/tasks/filesystems/zfs.nix
@@ -696,6 +696,10 @@ in
             This error can be triggered by using an absolute path, such as `"/dev/disk/..."`.
           '';
         }
+        {
+          assertion = cfgZED.enableMail -> config.services.mail.sendmailSetuidWrapper.enable;
+          message = "services.zfs.zed.enableMail requires services.mail.sendmailSetuidWrapper.enable to be enabled as otherwise no mail can be sent.";
+        }
       ];
 
       boot = {