From 56f6d3d4af2c61c050a4f940c37a6f6f30f51553 Mon Sep 17 00:00:00 2001
From: lassulus <git@lassul.us>
Date: Mon, 4 Mar 2024 01:50:21 +0100
Subject: [PATCH] types gpt: hash label if it's > 36 characters

---
 lib/types/gpt.nix | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/types/gpt.nix b/lib/types/gpt.nix
index 1b47020..5a70f07 100644
--- a/lib/types/gpt.nix
+++ b/lib/types/gpt.nix
@@ -55,7 +55,15 @@ in
           };
           label = lib.mkOption {
             type = lib.types.str;
-            default = "${config._parent.type}-${config._parent.name}-${partition.config.name}";
+            default = let
+              # 72 bytes is the maximum length of a GPT partition name
+              # the labels seem to be in UTF-16, so 2 bytes per character
+              limit = 36;
+              label = "${config._parent.type}-${config._parent.name}-${partition.config.name}"; 
+            in if (lib.stringLength label) > limit then
+              builtins.substring 0 limit (builtins.hashString "sha256" label)
+            else
+              label;
           };
           size = lib.mkOption {
             type = lib.types.either (lib.types.enum [ "100%" ]) (lib.types.strMatching "[0-9]+[KMGTP]?");