X-Git-Url: https://git.archive.openwrt.org/?p=project%2Fluci.git;a=blobdiff_plain;f=libs%2Fuvl%2Fluasrc%2Fuvl.lua;h=24dc3a25d2996d0e7aff470d4846526d15ebbd8f;hp=4894d300673c64f2b035b0c57ce8cc93798e6e40;hb=8be65461bcc64250f4ee1df3eef8de22f2c3f87f;hpb=7726e737252026683d10f5d85a32798f975ef437

diff --git a/libs/uvl/luasrc/uvl.lua b/libs/uvl/luasrc/uvl.lua
index 4894d3006..24dc3a25d 100644
--- a/libs/uvl/luasrc/uvl.lua
+++ b/libs/uvl/luasrc/uvl.lua
@@ -14,223 +14,447 @@ $Id$
 
 ]]--
 
+
+--- UVL - UCI Validation Layer
+-- @class	module
+-- @cstyle	instance
+
 module( "luci.uvl", package.seeall )
 
 require("luci.fs")
 require("luci.util")
 require("luci.model.uci")
+require("luci.uvl.errors")
 require("luci.uvl.datatypes")
+require("luci.uvl.validation")
+require("luci.uvl.dependencies")
 
-TYPE_SECTION  = 0x01
-TYPE_VARIABLE = 0x02
-TYPE_ENUM     = 0x03
 
+TYPE_SCHEME   = 0x00
+TYPE_CONFIG   = 0x01
+TYPE_SECTION  = 0x02
+TYPE_VARIABLE = 0x03
+TYPE_OPTION   = 0x04
+TYPE_ENUM     = 0x05
 
-local default_schemedir = "/etc/scheme"
-local function _assert( condition, fmt, ... )
-	if not condition then
-		return assert( nil, string.format( fmt, ... ) )
-	else
-		return condition
-	end
-end
+--- Boolean; default true;
+-- treat sections found in config but not in scheme as error
+STRICT_UNKNOWN_SECTIONS    = true
+
+--- Boolean; default true;
+-- treat options found in config but not in scheme as error
+STRICT_UNKNOWN_OPTIONS     = true
+
+--- Boolean; default true;
+-- treat failed external validators as error
+STRICT_EXTERNAL_VALIDATORS = true
+
+--- Boolean; default true;
+-- treat list values stored as options like errors
+STRICT_LIST_TYPE           = true
 
+
+local default_schemedir = "/lib/uci/schema"
+local ERR = luci.uvl.errors
+
+
+--- Object constructor
+-- @class			function
+-- @name			UVL
+-- @param schemedir	Path to the scheme directory (optional)
+-- @return			Instance object
 UVL = luci.util.class()
 
 function UVL.__init__( self, schemedir )
-
 	self.schemedir	= schemedir or default_schemedir
 	self.packages	= { }
+	self.beenthere  = { }
 	self.uci		= luci.model.uci
+	self.err		= luci.uvl.errors
+	self.dep		= luci.uvl.dependencies
 	self.datatypes  = luci.uvl.datatypes
 end
 
+
+--- Parse given scheme and return the scheme tree.
+-- @param scheme	Name of the scheme to parse
+-- @return			Table containing the parsed scheme or nil on error
+-- @return			String containing the reason for errors (if any)
+function UVL.get_scheme( self, scheme )
+	if not self.packages[scheme] then
+		local ok, err = self:read_scheme( scheme )
+		if not ok then
+			return nil, err
+		end
+	end
+	return self.packages[scheme], nil
+end
+
+--- Validate given configuration, section or option.
+-- @param config	Name of the configuration to validate
+-- @param section	Name of the section to validate (optional)
+-- @param option	Name of the option to validate (optional)
+-- @return			Boolean indicating whether the given config validates
+-- @return			String containing the reason for errors (if any)
+function UVL.validate( self, config, section, option )
+	if config and section and option then
+		return self:validate_option( config, section, option )
+	elseif config and section then
+		return self:validate_section( config, section )
+	elseif config then
+		return self:validate_config( config )
+	end
+end
+
 --- Validate given configuration.
 -- @param config	Name of the configuration to validate
--- @param scheme	Scheme to validate against (optional)
--- @return			Boolean indicating weather the given config validates
+-- @return			Boolean indicating whether the given config validates
 -- @return			String containing the reason for errors (if any)
-function UVL.validate( self, config, scheme )
+function UVL.validate_config( self, config, uci )
 
-	if not scheme then
-		return false, "No scheme found"
+	if not self.packages[config] then
+		local ok, err = self:read_scheme(config)
+		if not ok then
+			return false, err
+		end
 	end
 
-	for k, v in pairs( config ) do
-		local ok, err = self:validate_section( config, k, scheme )
+	local co = luci.uvl.config( self, uci or config, uci and config )
+	local sc = { }
 
-		if not ok then
-			return ok, err
+	self.beenthere = { }
+
+	if not co:config() then
+		return false, ERR.UCILOAD(co)
+	end
+
+	local function _uci_foreach( type, func )
+		for k, v in pairs(co:config()) do
+			if v['.type'] == type then
+				sc[type] = sc[type] + 1
+				local ok, err = func( k, v )
+				if not ok then co:error(err) end
+			end
 		end
 	end
 
-	return true, nil
+	for k, v in pairs( self.packages[config].sections ) do
+		sc[k] = 0
+		_uci_foreach( k,
+			function(s)
+				return self:_validate_section( co:section(s) )
+			end
+		)
+	end
+
+	if STRICT_UNKNOWN_SECTIONS then
+		for k, v in pairs(co:config()) do
+			local so = co:section(k)
+			if not self.beenthere[so:cid()] then
+				co:error(ERR.SECT_UNKNOWN(so))
+			end
+		end
+	end
+
+	for _, k in ipairs(luci.util.keys(sc)) do
+		local so = co:section(k)
+		if so:scheme('required') and sc[k] == 0 then
+			co:error(ERR.SECT_REQUIRED(so))
+		elseif so:scheme('unique') and sc[k] > 1 then
+			co:error(ERR.SECT_UNIQUE(so))
+		end
+	end
+
+	return co:ok(), co:errors()
 end
 
---- Validate given section of given configuration.
+--- Validate given config section.
 -- @param config	Name of the configuration to validate
--- @param section	Key of the section to validate
--- @param scheme	Scheme to validate against
--- @return			Boolean indicating weather the given config validates
+-- @param section	Name of the section to validate
+-- @return			Boolean indicating whether the given config validates
 -- @return			String containing the reason for errors (if any)
-function UVL.validate_section( self, config, section, scheme )
+function UVL.validate_section( self, config, section, uci )
 
-	if not scheme then
-		return false, "No scheme found"
+	if not self.packages[config] then
+		local ok, err = self:read_scheme( config )
+		if not ok then
+			return false, err
+		end
 	end
 
-	for k, v in pairs( config[section] ) do
-		local ok, err = self:validate_option( config, section, k, scheme )
+	local co = luci.uvl.config( self, uci or config, uci and config )
+	local so = co:section( section )
 
-		if not ok then
-			return ok, err
-		end
+	self.beenthere = { }
+
+	if not co:config() then
+		return false, ERR.UCILOAD(co)
 	end
 
-	return true, nil
+	if so:config() then
+		return self:_validate_section( so )
+	else
+		return false, ERR.SECT_NOTFOUND(so)
+	end
 end
 
---- Validate given option within section of given configuration.
+--- Validate given config option.
 -- @param config	Name of the configuration to validate
--- @param section	Key of the section to validate
+-- @param section	Name of the section to validate
 -- @param option	Name of the option to validate
--- @param scheme	Scheme to validate against
--- @return			Boolean indicating weather the given config validates
+-- @return			Boolean indicating whether the given config validates
 -- @return			String containing the reason for errors (if any)
-function UVL.validate_option( self, config, section, option, scheme )
+function UVL.validate_option( self, config, section, option, uci )
+
+	if not self.packages[config] then
+		local ok, err = self:read_scheme( config )
+		if not ok then
+			return false, err
+		end
+	end
+
+	local co = luci.uvl.config( self, uci or config, uci and config )
+	local so = co:section( section )
+	local oo = so:option( option )
 
-	if type(config) == "string" then
-		config = { ["variables"] = { [section] = { [option] = config } } }
+	if not co then
+		return false, oerr:child(ERR.UCILOAD(config))
 	end
 
-	if not scheme then
-		return false, "No scheme found"
+	if so:config() and oo:config() then
+		return self:_validate_option( oo )
+	else
+		return false, ERR.OPT_NOTFOUND(oo)
 	end
+end
 
-	local sv = scheme.variables[section]
-	if not sv then return false, "Requested section not found in scheme" end
 
-	sv = sv[option]
-	if not sv then return false, "Requested option not found in scheme" end
+function UVL._validate_section( self, section )
+
+	if section:config() then
+		if section:scheme('named') == true and
+		   section:config('.anonymous') == true
+		then
+			return false, ERR.SECT_NAMED(section)
+		end
+
+		for _, v in ipairs(section:variables()) do
+			local ok, err = self:_validate_option( v )
+			if not ok then
+				section:error(err)
+			end
+		end
+
+		local ok, err = luci.uvl.dependencies.check( self, section )
+		if not ok then
+			section:error(err)
+		end
+	else
+		return false, ERR.SECT_NOTFOUND(section)
+	end
 
-	if not ( config[section] and config[section][option] ) and sv.required then
-		return false, "Mandatory variable doesn't have a value"
+	if STRICT_UNKNOWN_OPTIONS and not section:scheme('dynamic') then
+		for k, v in pairs(section:config()) do
+			local oo = section:option(k)
+			if k:sub(1,1) ~= "." and not self.beenthere[oo:cid()] then
+				section:error(ERR.OPT_NOTFOUND(oo))
+			end
+		end
 	end
 
-	if sv.type then
-		if self.datatypes[sv.type] then
-			if not self.datatypes[sv.type]( config[section][option] ) then
-				return false, "Value of given option doesn't validate"
+	return section:ok(), section:errors()
+end
+
+function UVL._validate_option( self, option, nodeps )
+
+	if not option:scheme() and not option:parent():scheme('dynamic') then
+		return false, option:error(ERR.OPT_UNKNOWN(option))
+
+	elseif option:scheme() then
+		if option:scheme('required') and not option:value() then
+			return false, option:error(ERR.OPT_REQUIRED(option))
+
+		elseif option:value() then
+			local val = option:value()
+
+			if option:scheme('type') == "reference" or
+			   option:scheme('type') == "enum"
+			then
+				if not option:scheme('values') or
+				   not option:scheme('values')[val]
+				then
+					return false, option:error( ERR.OPT_BADVALUE(
+						option, { val, table.concat(
+							luci.util.keys(option:scheme('values') or {}), ", "
+						) }
+					) )
+				end
+			elseif option:scheme('type') == "list" then
+				if type(val) ~= "table" and STRICT_LIST_TYPE then
+					return false, option:error(ERR.OPT_NOTLIST(option))
+				end
+			elseif option:scheme('datatype') then
+				local dt = option:scheme('datatype')
+
+				if self.datatypes[dt] then
+					val = ( type(val) == "table" and val or { val } )
+					for i, v in ipairs(val) do
+						if not self.datatypes[dt]( v ) then
+							return false, option:error(
+								ERR.OPT_INVVALUE(option, {v, dt})
+							)
+						end
+					end
+				else
+					return false, option:error(ERR.OPT_DATATYPE(option, dt))
+				end
 			end
-		else
-			return false, "Unknown datatype '" .. sv.type .. "' encountered"
+		end
+
+		if not nodeps then
+			local ok, err = luci.uvl.dependencies.check( self, option )
+			if not ok then
+				option:error(err)
+			end
+		end
+
+		local ok, err = luci.uvl.validation.check( self, option )
+		if not ok and STRICT_EXTERNAL_VALIDATORS then
+			return false, option:error(err)
 		end
 	end
 
-	return true, nil
+	return option:ok(), option:errors()
 end
 
---- Find all parts of given scheme and construct validation tree
+--- Find all parts of given scheme and construct validation tree.
+-- This is normally done on demand, so you don't have to call this function
+-- by yourself.
 -- @param scheme	Name of the scheme to parse
--- @return			Parsed scheme
 function UVL.read_scheme( self, scheme )
-	local schemes = { }
 
-	for i, file in ipairs( luci.fs.glob(self.schemedir .. '/*/' .. scheme) ) do
-		_assert( luci.fs.access(file), "Can't access file '%s'", file )
+	local so = luci.uvl.scheme( self, scheme )
 
-		self.uci.set_confdir( luci.fs.dirname(file) )
-		self.uci.load( luci.fs.basename(file) )
+	local schemes = { }
+	local files = luci.fs.glob(self.schemedir .. '/*/' .. scheme)
 
-		table.insert( schemes, self.uci.get_all( luci.fs.basename(file) ) )
-	end
+	if files then
+		for i, file in ipairs( files ) do
+			if not luci.fs.access(file) then
+				return so:error(ERR.SME_READ(so,file))
+			end
 
-	return self:_read_scheme_parts( scheme, schemes )
-end
+			local uci = luci.model.uci.cursor()
+			      uci:set_confdir( luci.fs.dirname(file) )
 
--- Process all given parts and construct validation tree
-function UVL._read_scheme_parts( self, scheme, schemes )
+			local sd = uci:get_all( luci.fs.basename(file) )
 
-	local stbl = { }
+			if not sd then
+				return false, ERR.UCILOAD(so)
+			end
 
-	-- helper function to construct identifiers for given elements
-	local function _id( c, t )
-		if c == TYPE_SECTION then
-			return string.format(
-				"section '%s.%s'",
-					scheme, t.name or '?' )
-		elseif c == TYPE_VARIABLE then
-			return string.format(
-				"variable '%s.%s.%s'",
-					scheme, t.section or '?.?', t.name or '?' )
-		elseif c == TYPE_ENUM then
-			return string.format(
-				"enum '%s.%s.%s'",
-					scheme, t.variable or '?.?.?', t.value or '?' )
+			table.insert( schemes, sd )
 		end
+
+		return self:_read_scheme_parts( so, schemes )
+	else
+		return false, so:error(ERR.SME_FIND(so, self.schemedir))
 	end
+end
+
+-- Process all given parts and construct validation tree
+function UVL._read_scheme_parts( self, scheme, schemes )
 
 	-- helper function to check for required fields
 	local function _req( c, t, r )
 		for i, v in ipairs(r) do
-			_assert( t[v], "Missing required field '%s' in %s", v, _id(c, t) )
+			if not t[v] then
+				return false, ERR.SME_REQFLD({c,t}, v)
+			end
 		end
+		return true
 	end
 
 	-- helper function to validate references
 	local function _ref( c, t )
-		local k
+		local k, n
 		if c == TYPE_SECTION then
 			k = "package"
+			n = 1
 		elseif c == TYPE_VARIABLE then
 			k = "section"
+			n = 2
 		elseif c == TYPE_ENUM then
 			k = "variable"
+			n = 3
 		end
 
 		local r = luci.util.split( t[k], "." )
-		r[1] = ( #r[1] > 0 and r[1] or scheme )
+		r[1] = ( #r[1] > 0 and r[1] or scheme:sid() )
 
-		_assert( #r == c, "Malformed %s reference in %s", k, _id(c, t) )
+		if #r ~= n then
+			return false, ERR.SME_BADREF(scheme, k)
+		end
 
 		return r
 	end
 
+	-- helper function to read bools
+	local function _bool( v )
+		return ( v == "true" or v == "yes" or v == "on" or v == "1" )
+	end
+
+
+	local ok, err
+
 	-- Step 1: get all sections
 	for i, conf in ipairs( schemes ) do
 		for k, v in pairs( conf ) do
 			if v['.type'] == 'section' then
 
-				_req( TYPE_SECTION, v, { "name", "package" } )
+				ok, err = _req( TYPE_SECTION, v, { "name", "package" } )
+				if err then return false, scheme:error(err) end
 
-				local r = _ref( TYPE_SECTION, v )
+				local r, err = _ref( TYPE_SECTION, v )
+				if err then return false, scheme:error(err) end
 
-				stbl.packages[r[1]] =
-					stbl.packages[r[1]] or {
+				self.packages[r[1]] =
+					self.packages[r[1]] or {
+						["name"]      = r[1];
 						["sections"]  = { };
 						["variables"] = { };
 					}
 
-				local p = stbl.packages[r[1]]
+				local p = self.packages[r[1]]
 					  p.sections[v.name]  = p.sections[v.name]  or { }
 					  p.variables[v.name] = p.variables[v.name] or { }
 
-				local s = p.sections[v.name]
+				local s  = p.sections[v.name]
+				local so = scheme:section(v.name)
 
-				for k, v in pairs(v) do
+				for k, v2 in pairs(v) do
 					if k ~= "name" and k ~= "package" and k:sub(1,1) ~= "." then
-						if k:match("^depends") then
-							s["depends"] = _assert(
-								self:_read_depency( v, s["depends"] ),
-								"Section '%s' in scheme '%s' has malformed " ..
-								"depency specification in '%s'",
-								v.name, scheme, k
-							)
+						if k == "depends" then
+							s.depends = self:_read_dependency( v2, s.depends )
+							if not s.depends then
+								return false, scheme:error(
+									ERR.SME_BADDEP(so, luci.util.serialize_data(s.depends))
+								)
+							end
+						elseif k == "dynamic" or k == "unique" or
+						       k == "required" or k == "named"
+						then
+							s[k] = _bool(v2)
 						else
-							s[k] = v
+							s[k] = v2
 						end
 					end
 				end
+
+				s.dynamic  = s.dynamic  or false
+				s.unique   = s.unique   or false
+				s.required = s.required or false
+				s.named    = s.named    or false
 			end
 		end
 	end
@@ -240,43 +464,68 @@ function UVL._read_scheme_parts( self, scheme, schemes )
 		for k, v in pairs( conf ) do
 			if v['.type'] == "variable" then
 
-				_req( TYPE_VARIABLE, v, { "name", "type", "section" } )
+				ok, err = _req( TYPE_VARIABLE, v, { "name", "section" } )
+				if err then return false, scheme:error(err) end
 
-				local r = _ref( TYPE_VARIABLE, v )
+				local r, err = _ref( TYPE_VARIABLE, v )
+				if err then return false, scheme:error(err) end
 
-				local p = _assert( stbl.packages[r[1]],
-					"Variable '%s' in scheme '%s' references unknown package '%s'",
-					v.name, scheme, r[1] )
+				local p = self.packages[r[1]]
+				if not p then
+					return false, scheme:error(
+						ERR.SME_VBADPACK({scheme:sid(), '', v.name}, r[1])
+					)
+				end
 
-				local s = _assert( p.variables[r[2]],
-					"Variable '%s' in scheme '%s' references unknown section '%s'",
-					v.name, scheme, r[2] )
+				local s = p.variables[r[2]]
+				if not s then
+					return false, scheme:error(
+						ERR.SME_VBADSECT({scheme:sid(), '', v.name}, r[2])
+					)
+				end
 
 				s[v.name] = s[v.name] or { }
 
-				local t = s[v.name]
+				local t  = s[v.name]
+				local so = scheme:section(r[2])
+				local to = so:option(v.name)
 
-				for k, v in pairs(v) do
+				for k, v2 in pairs(v) do
 					if k ~= "name" and k ~= "section" and k:sub(1,1) ~= "." then
-						if k:match("^depends") then
-							t["depends"] = _assert(
-								self:_read_depency( v, t["depends"] ),
-								"Variable '%s' in scheme '%s' has malformed " ..
-								"depency specification in '%s'",
-								v.name, scheme, k
-							)
-						elseif k:match("^validator") then
-							t["validators"] = _assert(
-								self:_read_validator( v, t["validators"] ),
-								"Variable '%s' in scheme '%s' has malformed " ..
-								"validator specification in '%s'",
-								v.name, scheme, k
-							)
+						if k == "depends" then
+							t.depends = self:_read_dependency( v2, t.depends )
+							if not t.depends then
+								return false, scheme:error(so:error(
+									ERR.SME_BADDEP(to, luci.util.serialize_data(v2))
+								))
+							end
+						elseif k == "validator" then
+							t.validators = self:_read_validator( v2, t.validators )
+							if not t.validators then
+								return false, scheme:error(so:error(
+									ERR.SME_BADVAL(to, luci.util.serialize_data(v2))
+								))
+							end
+						elseif k == "valueof" then
+							local values, err = self:_read_reference( v2 )
+							if err then
+								return false, scheme:error(so:error(
+									ERR.REFERENCE(to, luci.util.serialize_data(v2)):child(err)
+								))
+							end
+							t.type   = "reference"
+							t.values = values
+						elseif k == "required" then
+							t[k] = _bool(v2)
 						else
-							t[k] = v
+							t[k] = t[k] or v2
 						end
 					end
 				end
+
+				t.type     = t.type     or "variable"
+				t.datatype = t.datatype or "string"
+				t.required = t.required or false
 			end
 		end
 	end
@@ -286,27 +535,41 @@ function UVL._read_scheme_parts( self, scheme, schemes )
 		for k, v in pairs( conf ) do
 			if v['.type'] == "enum" then
 
-				_req( TYPE_ENUM, v, { "value", "variable" } )
+				ok, err = _req( TYPE_ENUM, v, { "value", "variable" } )
+				if err then return false, scheme:error(err) end
+
+				local r, err = _ref( TYPE_ENUM, v )
+				if err then return false, scheme:error(err) end
+
+				local p = self.packages[r[1]]
+				if not p then
+					return false, scheme:error(
+						ERR.SME_EBADPACK({scheme:sid(), '', '', v.value}, r[1])
+					)
+				end
 
-				local r = _ref( TYPE_ENUM, v )
+				local s = p.variables[r[2]]
+				if not s then
+					return false, scheme:error(
+						ERR.SME_EBADSECT({scheme:sid(), '', '', v.value}, r[2])
+					)
+				end
 
-				local p = _assert( stbl.packages[r[1]],
-					"Enum '%s' in scheme '%s' references unknown package '%s'",
-					v.value, scheme, r[1] )
+				local t = s[r[3]]
+				if not t then
+					return false, scheme:error(
+						ERR.SME_EBADOPT({scheme:sid(), '', '', v.value}, r[3])
+					)
+				end
 
-				local s = _assert( p.variables[r[2]],
-					"Enum '%s' in scheme '%s' references unknown section '%s'",
-					v.value, scheme, r[2] )
 
-				local t = _assert( s[r[3]],
-					"Enum '%s' in scheme '%s', section '%s' references " ..
-					"unknown variable '%s'",
-					v.value, scheme, r[2], r[3] )
+				local so = scheme:section(r[2])
+				local oo = so:option(r[3])
+				local eo = oo:enum(v.value)
 
-				_assert( t.type == "enum",
-					"Enum '%s' in scheme '%s', section '%s' references " ..
-					"variable '%s' with non enum type '%s'",
-					v.value, scheme, r[2], r[3], t.type )
+				if t.type ~= "enum" then
+					return false, scheme:error(ERR.SME_EBADTYPE(eo))
+				end
 
 				if not t.values then
 					t.values = { [v.value] = v.title or v.value }
@@ -314,68 +577,126 @@ function UVL._read_scheme_parts( self, scheme, schemes )
 					t.values[v.value] = v.title or v.value
 				end
 
-				if v.default then
-					_assert( not t.default,
-						"Enum '%s' in scheme '%s', section '%s' redeclares " ..
-						"the default value of variable '%s'",
-						v.value, scheme, r[2], v.variable )
+				if not t.enum_depends then
+					t.enum_depends = { }
+				end
 
+				if v.default then
+					if t.default then
+						return false, scheme:error(ERR.SME_EBADDEF(eo))
+					end
 					t.default = v.value
 				end
+
+				if v.depends then
+					t.enum_depends[v.value] = self:_read_dependency(
+						v.depends, t.enum_depends[v.value]
+					)
+
+					if not t.enum_depends[v.value] then
+						return false, scheme:error(so:error(oo:error(
+							ERR.SME_BADDEP(eo, luci.util.serialize_data(v.depends))
+						)))
+					end
+				end
 			end
 		end
 	end
 
-	return stbl
+	return self
 end
 
--- Read a depency specification
-function UVL._read_depency( self, value, deps )
-	local parts     = luci.util.split( value, "%s*;%s*" )
-	local condition = { }
-
-	for i, val in ipairs(parts) do
-		local k, v = unpack(luci.util.split( val, "%s*=%s*" ))
+-- Read a dependency specification
+function UVL._read_dependency( self, values, deps )
+	local expr = "%$?[a-zA-Z0-9_]+"
+	if values then
+		values = ( type(values) == "table" and values or { values } )
+		for _, value in ipairs(values) do
+			local parts     = luci.util.split( value, "%s*,%s*", nil, true )
+			local condition = { }
+			for i, val in ipairs(parts) do
+				local k, v = unpack(luci.util.split(val, "%s*=%s*", nil, true))
+
+				if k and (
+					k:match("^"..expr.."%."..expr.."%."..expr.."$") or
+					k:match("^"..expr.."%."..expr.."$") or
+					k:match("^"..expr.."$")
+				) then
+					condition[k] = v or true
+				else
+					return nil
+				end
+			end
 
-		if k and (
-			k:match("^%$?[a-zA-Z0-9_]+%.%$?[a-zA-Z0-9_]+%.%$?[a-zA-Z0-9_]+$")
-			k:match("^%$?[a-zA-Z0-9_]+%.%$?[a-zA-Z0-9_]+$") or
-			k:match("^%$?[a-zA-Z0-9_]+$") or
-		) then
-			condition[k] = v or true
-		else
-			return nil
+			if not deps then
+				deps = { condition }
+			else
+				table.insert( deps, condition )
+			end
 		end
 	end
 
-	if not deps then
-		deps = { condition }
-	else
-		table.insert( deps, condition )
-	end
-
 	return deps
 end
 
 -- Read a validator specification
-function UVL._read_validator( self, value, validators )
-	local validator
+function UVL._read_validator( self, values, validators )
+	if values then
+		values = ( type(values) == "table" and values or { values } )
+		for _, value in ipairs(values) do
+			local validator
+
+			if value:match("^exec:") then
+				validator = value:gsub("^exec:","")
+			elseif value:match("^lua:") then
+				validator = self:_resolve_function( (value:gsub("^lua:","") ) )
+			end
 
-	if value and value:match("/") and self.datatypes.file(value) then
-		validator = value
-	else
-		validator = self:_resolve_function( value )
+			if validator then
+				if not validators then
+					validators = { validator }
+				else
+					table.insert( validators, validator )
+				end
+			else
+				return nil
+			end
+		end
+
+		return validators
 	end
+end
+
+-- Read a reference specification (XXX: We should validate external configs too...)
+function UVL._read_reference( self, values )
+	local val = { }
+	values = ( type(values) == "table" and values or { values } )
 
-	if validator then
-		if not validators then
-			validators = { validator }
+	for _, value in ipairs(values) do
+		local ref = luci.util.split(value, ".")
+
+		if #ref == 2 or #ref == 3 then
+			local co = luci.uvl.config( self, ref[1] )
+			if not co:config() then return false, ERR.UCILOAD(ref[1]) end
+
+			for k, v in pairs(co:config()) do
+				if v['.type'] == ref[2] then
+					if #ref == 2 then
+						if v['.anonymous'] == true then
+							return false, ERR.SME_INVREF('', value)
+						end
+						val[k] = k	-- XXX: title/description would be nice
+					elseif v[ref[3]] then
+						val[v[ref[3]]] = v[ref[3]]  -- XXX: dito
+					end
+				end
+			end
 		else
-			table.insert( validators, validator )
+			return false, ERR.SME_BADREF('', value)
 		end
-
-		return validators
 	end
+
+	return val, nil
 end
 
 -- Resolve given path
@@ -383,11 +704,14 @@ function UVL._resolve_function( self, value )
 	local path = luci.util.split(value, ".")
 
 	for i=1, #path-1 do
-		local stat, mod = pcall(require, table.concat(path, ".", 1, i))
+		local stat, mod = luci.util.copcall(
+			require, table.concat(path, ".", 1, i)
+		)
+
 		if stat and mod then
 			for j=i+1, #path-1 do
 				if not type(mod) == "table" then
-					break;
+					break
 				end
 				mod = mod[path[j]]
 				if not mod then
@@ -401,3 +725,354 @@ function UVL._resolve_function( self, value )
 		end
 	end
 end
+
+
+--- Object representation of an uvl item - base class.
+uvlitem = luci.util.class()
+
+function uvlitem.cid(self)
+	return table.concat( self.cref, '.' )
+end
+
+function uvlitem.sid(self)
+	return table.concat( self.sref, '.' )
+end
+
+function uvlitem.scheme(self, opt)
+	local s
+
+	if #self.sref == 4 or #self.sref == 3 then
+		s = self.s
+			.packages[self.sref[1]]
+			.variables[self.sref[2]][self.sref[3]]
+	elseif #self.sref == 2 then
+		s = self.s
+			.packages[self.sref[1]]
+			.sections[self.sref[2]]
+	else
+		s = self.s
+			.packages[self.sref[1]]
+	end
+
+	if s and opt then
+		return s[opt]
+	elseif s then
+		return s
+	end
+end
+
+function uvlitem.config(self, opt)
+	local c
+
+	if #self.cref == 4 or #self.cref == 3 then
+		c = self.c[self.cref[2]][self.cref[3]]
+	elseif #self.cref == 2 then
+		c = self.c[self.cref[2]]
+	else
+		c = self.c
+	end
+
+	if c and opt then
+		return c[opt]
+	elseif c then
+		return c
+	end
+end
+
+function uvlitem.title(self)
+	return self:scheme() and self:scheme('title') or
+		self.cref[3] or self.cref[2] or self.cref[1]
+end
+
+function uvlitem.type(self)
+	if self.t == luci.uvl.TYPE_CONFIG then
+		return 'config'
+	elseif self.t == luci.uvl.TYPE_SECTION then
+		return 'section'
+	elseif self.t == luci.uvl.TYPE_OPTION then
+		return 'option'
+	elseif self.t == luci.uvl.TYPE_ENUM then
+		return 'enum'
+	end
+end
+
+function uvlitem.error(self, ...)
+	if not self.e then
+		local errconst = { ERR.CONFIG, ERR.SECTION, ERR.OPTION, ERR.OPTION }
+		self.e = errconst[#self.cref]( self )
+	end
+
+	return self.e:child( ... )
+end
+
+function uvlitem.errors(self)
+	return self.e
+end
+
+function uvlitem.ok(self)
+	return not self:errors()
+end
+
+function uvlitem.parent(self)
+	if self.p then
+		return self.p
+	elseif #self.cref == 3 or #self.cref == 4 then
+		return luci.uvl.section( self.s, self.c, self.cref[1], self.cref[2] )
+	elseif #self.cref == 2 then
+		return luci.uvl.config( self.s, self.c, self.cref[1] )
+	else
+		return nil
+	end
+end
+
+
+--- Object representation of a scheme.
+-- @class	scheme
+-- @cstyle	instance
+-- @name	luci.uvl.scheme
+
+--- Scheme instance constructor.
+-- @class			function
+-- @name			scheme
+-- @param scheme	Scheme instance
+-- @param co		Configuration data
+-- @param c			Configuration name
+-- @return			Config instance
+scheme = luci.util.class(uvlitem)
+
+function scheme.__init__(self, scheme, co, c)
+	if not c then
+		c, co = co, nil
+	end
+
+	if not co then
+		local uci = luci.model.uci.cursor()
+		co = uci:get_all(c)
+	end
+
+	self.cref = { c }
+	self.sref = { c }
+	self.c    = co
+	self.s    = scheme
+	self.t    = luci.uvl.TYPE_SCHEME
+end
+
+--- Add an error to scheme.
+-- @return	Scheme error context
+function scheme.error(self, ...)
+	if not self.e then self.e = ERR.SCHEME( self ) end
+	return self.e:child( ... )
+end
+
+--- Get an associated config object.
+-- @return	Config instance
+function scheme.config(self)
+	local co = luci.uvl.config( self.s, self.cref[1] )
+	      co.p = self
+
+	return co
+end
+
+--- Get all section objects associated with this scheme.
+-- @return	Table containing all associated luci.uvl.section instances
+function scheme.sections(self)
+	local v = { }
+	if self.s.packages[self.sref[1]].sections then
+		for o, _ in pairs( self.s.packages[self.sref[1]].sections ) do
+			table.insert( v, luci.uvl.option(
+				self.s, self.c, self.cref[1], self.cref[2], o
+			) )
+		end
+	end
+	return v
+end
+
+--- Get an associated section object.
+-- @param s	Section to select
+-- @return	Section instance
+function scheme.section(self, s)
+	local so = luci.uvl.section( self.s, self.c, self.cref[1], s )
+	      so.p = self
+
+	return so
+end
+
+
+--- Object representation of a config.
+-- @class	config
+-- @cstyle	instance
+-- @name	luci.uvl.config
+
+--- Config instance constructor.
+-- @class			function
+-- @name			config
+-- @param scheme	Scheme instance
+-- @param co		Configuration data
+-- @param c			Configuration name
+-- @return			Config instance
+config = luci.util.class(uvlitem)
+
+function config.__init__(self, scheme, co, c)
+	if not c then
+		c, co = co, nil
+	end
+
+	if not co then
+		local uci = luci.model.uci.cursor()
+		co = uci:get_all(c)
+	end
+
+	self.cref = { c }
+	self.sref = { c }
+	self.c    = co
+	self.s    = scheme
+	self.t    = luci.uvl.TYPE_CONFIG
+end
+
+--- Get all section objects associated with this config.
+-- @return	Table containing all associated luci.uvl.section instances
+function config.sections(self)
+	local v = { }
+	if self.s.packages[self.sref[1]].sections then
+		for o, _ in pairs( self.s.packages[self.sref[1]].sections ) do
+			table.insert( v, luci.uvl.option(
+				self.s, self.c, self.cref[1], self.cref[2], o
+			) )
+		end
+	end
+	return v
+end
+
+--- Get an associated section object.
+-- @param s	Section to select
+-- @return	Section instance
+function config.section(self, s)
+	local so = luci.uvl.section( self.s, self.c, self.cref[1], s )
+	      so.p = self
+
+	return so
+end
+
+
+--- Object representation of a scheme/config section.
+-- @class	module
+-- @cstyle	instance
+-- @name	luci.uvl.section
+
+--- Section instance constructor.
+-- @class			function
+-- @name			section
+-- @param scheme	Scheme instance
+-- @param co		Configuration data
+-- @param c			Configuration name
+-- @param s			Section name
+-- @return			Section instance
+section = luci.util.class(uvlitem)
+
+function section.__init__(self, scheme, co, c, s)
+	self.cref = { c, s }
+	self.sref = { c, co and co[s] and co[s]['.type'] or s }
+	self.c    = co
+	self.s    = scheme
+	self.t    = luci.uvl.TYPE_SECTION
+end
+
+--- Get all option objects associated with this section.
+-- @return	Table containing all associated luci.uvl.option instances
+function section.variables(self)
+	local v = { }
+	if self.s.packages[self.sref[1]].variables[self.sref[2]] then
+		for o, _ in pairs(
+			self.s.packages[self.sref[1]].variables[self.sref[2]]
+		) do
+			table.insert( v, luci.uvl.option(
+				self.s, self.c, self.cref[1], self.cref[2], o
+			) )
+		end
+	end
+	return v
+end
+
+--- Get an associated option object.
+-- @param o	Option to select
+-- @return	Option instance
+function section.option(self, o)
+	local oo = luci.uvl.option( self.s, self.c, self.cref[1], self.cref[2], o )
+	      oo.p = self
+
+	return oo
+end
+
+
+--- Object representation of a scheme/config option.
+-- @class	module
+-- @cstyle	instance
+-- @name	luci.uvl.option
+
+--- Section instance constructor.
+-- @class			function
+-- @name			option
+-- @param scheme	Scheme instance
+-- @param co		Configuration data
+-- @param c			Configuration name
+-- @param s			Section name
+-- @param o			Option name
+-- @return			Option instance
+option = luci.util.class(uvlitem)
+
+function option.__init__(self, scheme, co, c, s, o)
+	self.cref = { c, s, o }
+	self.sref = { c, co and co[s] and co[s]['.type'] or s, o }
+	self.c    = co
+	self.s    = scheme
+	self.t    = luci.uvl.TYPE_OPTION
+end
+
+--- Get the value of this option.
+-- @return	The associated configuration value
+function option.value(self)
+	return self:config()
+end
+
+--- Get the associated section information in scheme.
+-- @return	Table containing the scheme properties
+function option.section(self)
+	return self.s.packages[self.sref[1]].sections[self.sref[2]]
+end
+
+--- Construct an enum object instance from given or default value.
+-- @param v	Value to select
+-- @return	Enum instance for selected value
+function option.enum(self, val)
+	return enum(
+		self.s, self.c,
+		self.cref[1], self.cref[2], self.cref[3],
+		val or self:value()
+	)
+end
+
+
+--- Object representation of a enum value.
+-- @class	module
+-- @cstyle	instance
+-- @name	luci.uvl.enum
+
+--- Section instance constructor.
+-- @class			function
+-- @name			enum
+-- @param scheme	Scheme instance
+-- @param co		Configuration data
+-- @param c			Configuration name
+-- @param s			Section name
+-- @param o			Enum name
+-- @param v			Enum value
+-- @return			Enum value instance
+enum = luci.util.class(option)
+
+function enum.__init__(self, scheme, co, c, s, o, v)
+	self.cref = { c, s, o, v }
+	self.sref = { c, co and co[s] and co[s]['.type'] or s, o, v }
+	self.c    = co
+	self.s    = scheme
+	self.t    = luci.uvl.TYPE_ENUM
+end