lualoader: Strip config.parse of its I/O privileges

config.parse is now purely a parser, rather than a whole proccessor. The
standard process for loading a config file has been split out into
config.processFile.

This clears the way for having nextboot read its own config file and decide
there whether it should parse the rest of the file.

stand/lua/config.lua

@@ -134,7 +134,8 @@ local function check_nextboot()
 		return text:match("^nextboot_enable=\"NO\"") == nil
 	end
 
-	if not config.parse(nextboot_file, true, check_nextboot_enabled) then
+	if not config.processFile(nextboot_file, true, check_nextboot_enabled)
+	    then
 		-- This only fails if it actually hit a parse error
 		print("Failed to parse nextboot configuration: '" ..
 		    nextboot_file .. "'")
@@ -326,10 +327,7 @@ function config.loadmod(mod, silent)
 	return status
 end
 
--- silent runs will not return false if we fail to open the file
--- check_and_halt, if it's set, will be executed on the full text of the config
--- file. If it returns false, we are to halt immediately.
-function config.parse(name, silent, check_and_halt)
+function config.processFile(name, silent, check_and_halt)
 	if silent == nil then
 		silent = false
 	end
@@ -345,6 +343,14 @@ function config.parse(name, silent, check_and_halt)
 			return true
 		end
 	end
+
+	return config.parse(text)
+end
+
+-- silent runs will not return false if we fail to open the file
+-- check_and_halt, if it's set, will be executed on the full text of the config
+-- file. If it returns false, we are to halt immediately.
+function config.parse(text)
 	local n = 1
 	local status = true
 
@@ -473,7 +479,7 @@ function config.load(file)
 		file = "/boot/defaults/loader.conf"
 	end
 
-	if not config.parse(file) then
+	if not config.processFile(file) then
 		print("Failed to parse configuration: '" .. file .. "'")
 	end
 
@@ -483,7 +489,7 @@ function config.load(file)
 			-- These may or may not exist, and that's ok. Do a
 			-- silent parse so that we complain on parse errors but
 			-- not for them simply not existing.
-			if not config.parse(name, true) then
+			if not config.processFile(name, true) then
 				print("Failed to parse configuration: '" ..
 				    name .. "'")
 			end