lualoader: Accept that people use unquoted values in loader.conf

While loader.conf(5) suggests that all values should be quoted, reality is
that this was never strictly enforced and it is used. We already make some
concession to this in number values, which aren't strictly quoted either.

The compromise here is that multi-word values must be quoted. This lets
things like `foo_load=YES` work, while denying more complex expressions on
the right hand side. This likely catches the vast majority of current usage.

A bit of a kludge is needed to accomplish this since Lua regex doesn't
support branching. I had considered splitting up expressions and generating
the right-hand side of the expressions completely in config.parse, but
deemed this too large of an overhaul to take given the current timing. This
should be re-worked shortly after the thaw.

Reported by:	royger

stand/lua/config.lua

@@ -57,6 +57,10 @@ local MSG_MODLOADING = "Loading configured modules..."
 local MSG_MODLOADFAIL = "Could not load one or more modules!"
 
 local MODULEEXPR = '([%w-_]+)'
+local QVALEXPR = "\"([%w%s%p]-)\""
+local QVALREPL = QVALEXPR:gsub('%%', '%%%%')
+local WORDEXPR = "([%w]+)"
+local WORDREPL = WORDEXPR:gsub('%%', '%%%%')
 
 local function restoreEnv()
 	-- Examine changed environment variables
@@ -125,11 +129,31 @@ local function processEnvVar(value)
 	return value
 end
 
+local function checkPattern(line, pattern)
+	local function _realCheck(_line, _pattern)
+		return _line:match(_pattern)
+	end
+
+	if pattern:find('$VALUE') then
+		local k, v, c
+		k, v, c = _realCheck(line, pattern:gsub('$VALUE', QVALREPL))
+		if k ~= nil then
+			return k,v, c
+		end
+		return _realCheck(line, pattern:gsub('$VALUE', WORDREPL))
+	else
+		return _realCheck(line, pattern)
+	end
+end
+
 -- str in this table is a regex pattern.  It will automatically be anchored to
 -- the beginning of a line and any preceding whitespace will be skipped.  The
 -- pattern should have no more than two captures patterns, which correspond to
 -- the two parameters (usually 'key' and 'value') that are passed to the
--- process function.  All trailing characters will be validated.
+-- process function.  All trailing characters will be validated.  Any $VALUE
+-- token included in a pattern will be tried first with a quoted value capture
+-- group, then a single-word value capture group.  This is our kludge for Lua
+-- regex not supporting branching.
 --
 -- We have two special entries in this table: the first is the first entry,
 -- a full-line comment.  The second is for 'exec' handling.  Both have a single
@@ -139,6 +163,7 @@ end
 -- We document the exceptions with a special 'groups' index that indicates
 -- the number of capture groups, if not two.  We'll use this later to do
 -- validation on the proper entry.
+--
 local pattern_table = {
 	{
 		str = "(#.*)",
@@ -147,7 +172,7 @@ local pattern_table = {
 	},
 	--  module_load="value"
 	{
-		str = MODULEEXPR .. "_load%s*=%s*\"([%w%s%p]-)\"",
+		str = MODULEEXPR .. "_load%s*=%s*$VALUE",
 		process = function(k, v)
 			if modules[k] == nil then
 				modules[k] = {}
@@ -157,49 +182,49 @@ local pattern_table = {
 	},
 	--  module_name="value"
 	{
-		str = MODULEEXPR .. "_name%s*=%s*\"([%w%s%p]-)\"",
+		str = MODULEEXPR .. "_name%s*=%s*$VALUE",
 		process = function(k, v)
 			setKey(k, "name", v)
 		end,
 	},
 	--  module_type="value"
 	{
-		str = MODULEEXPR .. "_type%s*=%s*\"([%w%s%p]-)\"",
+		str = MODULEEXPR .. "_type%s*=%s*$VALUE",
 		process = function(k, v)
 			setKey(k, "type", v)
 		end,
 	},
 	--  module_flags="value"
 	{
-		str = MODULEEXPR .. "_flags%s*=%s*\"([%w%s%p]-)\"",
+		str = MODULEEXPR .. "_flags%s*=%s*$VALUE",
 		process = function(k, v)
 			setKey(k, "flags", v)
 		end,
 	},
 	--  module_before="value"
 	{
-		str = MODULEEXPR .. "_before%s*=%s*\"([%w%s%p]-)\"",
+		str = MODULEEXPR .. "_before%s*=%s*$VALUE",
 		process = function(k, v)
 			setKey(k, "before", v)
 		end,
 	},
 	--  module_after="value"
 	{
-		str = MODULEEXPR .. "_after%s*=%s*\"([%w%s%p]-)\"",
+		str = MODULEEXPR .. "_after%s*=%s*$VALUE",
 		process = function(k, v)
 			setKey(k, "after", v)
 		end,
 	},
 	--  module_error="value"
 	{
-		str = MODULEEXPR .. "_error%s*=%s*\"([%w%s%p]-)\"",
+		str = MODULEEXPR .. "_error%s*=%s*$VALUE",
 		process = function(k, v)
 			setKey(k, "error", v)
 		end,
 	},
 	--  exec="command"
 	{
-		str = "exec%s*=%s*\"([%w%s%p]-)\"",
+		str = "exec%s*=%s*" .. QVALEXPR,
 		process = function(k, _)
 			if cli_execute_unparsed(k) ~= 0 then
 				print(MSG_FAILEXEC:format(k))
@@ -209,7 +234,7 @@ local pattern_table = {
 	},
 	--  env_var="value"
 	{
-		str = "([%w%p]+)%s*=%s*\"([%w%s%p]-)\"",
+		str = "([%w%p]+)%s*=%s*$VALUE",
 		process = function(k, v)
 			if setEnv(k, processEnvVar(v)) ~= 0 then
 				print(MSG_FAILSETENV:format(k, v))
@@ -410,7 +435,7 @@ function config.parse(text)
 			for _, val in ipairs(pattern_table) do
 				local pattern = '^%s*' .. val.str .. '%s*(.*)';
 				local cgroups = val.groups or 2
-				local k, v, c = line:match(pattern)
+				local k, v, c = checkPattern(line, pattern)
 				if k ~= nil then
 					-- Offset by one, drats
 					if cgroups == 1 then