From 7f35c8b2ac51c9c93abaa4eaa23f4ac39e5db5a5 Mon Sep 17 00:00:00 2001
From: Majiir Paktu <majiir@nabaal.net>
Date: Sun, 29 Jan 2023 15:48:47 -0500
Subject: [PATCH] nixos/systemd/coredump: fix kernel.core_pattern truncation

Fixes #213408
---
 nixos/modules/system/boot/systemd/coredump.nix | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/system/boot/systemd/coredump.nix b/nixos/modules/system/boot/systemd/coredump.nix
index c2ca973d3807..03ef00e5683c 100644
--- a/nixos/modules/system/boot/systemd/coredump.nix
+++ b/nixos/modules/system/boot/systemd/coredump.nix
@@ -44,7 +44,21 @@ in {
         '';
 
         # install provided sysctl snippets
-        "sysctl.d/50-coredump.conf".source = "${systemd}/example/sysctl.d/50-coredump.conf";
+        "sysctl.d/50-coredump.conf".source =
+          # Fix systemd-coredump error caused by truncation of `kernel.core_pattern`
+          # when the `systemd` derivation name is too long. This works by substituting
+          # the path to `systemd` with a symlink that has a constant-length path.
+          #
+          # See: https://github.com/NixOS/nixpkgs/issues/213408
+          pkgs.substitute {
+            src = "${systemd}/example/sysctl.d/50-coredump.conf";
+            replacements = [
+              "--replace"
+              "${systemd}"
+              "${pkgs.symlinkJoin { name = "systemd"; paths = [ systemd ]; }}"
+            ];
+          };
+
         "sysctl.d/50-default.conf".source = "${systemd}/example/sysctl.d/50-default.conf";
       };