From e73c944fc079f7f08a32270eb83854e3270b05e4 Mon Sep 17 00:00:00 2001
From: Kyle Evans <kevans@FreeBSD.org>
Date: Tue, 20 Feb 2018 22:47:49 +0000
Subject: [PATCH] lualoader: When restoring environment, only restore unchanged
 vars

Track the latest value we've set an environment variable to, and only
restore those that are unchanged from that.

This gives us some leeway to make sure we're not clobbering variables
overwritten by menu changes.
---
 stand/lua/config.lua | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/stand/lua/config.lua b/stand/lua/config.lua
index 4d307ade4dd2..cf9118f50f83 100644
--- a/stand/lua/config.lua
+++ b/stand/lua/config.lua
@@ -142,13 +142,26 @@ function config.setCarouselIndex(id, idx)
 end
 
 function config.restoreEnv()
+	-- Examine changed environment variables
 	for k, v in pairs(config.env_changed) do
 		local restore_value = config.env_restore[k];
+		if (restore_value == nil) then
+			-- This one doesn't need restored for some reason
+			goto continue;
+		end
+		local current_value = loader.getenv(k);
+		if (current_value ~= v) then
+			-- This was overwritten by some action taken on the menu
+			-- most likely; we'll leave it be.
+			goto continue;
+		end
+		restore_value = restore_value.value;
 		if (restore_value ~= nil) then
 			loader.setenv(k, restore_value);
 		else
 			loader.unsetenv(k);
 		end
+		::continue::
 	end
 
 	config.env_changed = {};
@@ -156,12 +169,13 @@ function config.restoreEnv()
 end
 
 function config.setenv(k, v)
-	-- Do we need to track this change?
-	if (config.env_changed[k] == nil) then
-		config.env_changed[k] = true;
-		config.env_restore[k] = loader.getenv(k);
+	-- Track the original value for this if we haven't already
+	if (config.env_restore[k] == nil) then
+		config.env_restore[k] = {value = loader.getenv(k)};
 	end
 
+	config.env_changed[k] = v;
+
 	return loader.setenv(k, v);
 end