Implement settings interface.

src/conf_defaults.lua

@@ -1,5 +1,8 @@
 local M = {}
 
+--NOTE: proposed notation for baseline configuration (containing defaults as well as type and constraint information)
+--the table name is the configuration key; min, max and regex are all optional; type is one of: {bool, int, float, string}
+
 --NOTE: pcall protects from invocation exceptions, which is what we need except
 --during debugging. This flag replaces them with a normal call so we can inspect stack traces.
 M.DEBUG_PCALLS = true
@@ -7,28 +10,38 @@ M.DEBUG_PCALLS = true
 --REST responses will contain 'module' and 'function' keys describing what was requested
 M.API_INCLUDE_ENDPOINT_INFO = false
 
-M.DEFAULT_AP_SSID = "d3d-ap-%MAC_ADDR_TAIL%"
-M.DEFAULT_AP_ADDRESS = "192.168.10.1"
-M.DEFAULT_AP_NETMASK = "255.255.255.0"
 
+-- was: M.DEFAULT_AP_SSID = "d3d-ap-%MAC_ADDR_TAIL%"
+M.apSsid = {
+	default = 'd3d-ap-%%MAC_ADDR_TAIL%%',
+	type = 'string',
+	description = 'Access Point mode SSID',
+	min = 1,
+	max = 32
+}
+
+-- was: M.DEFAULT_AP_ADDRESS = "192.168.10.1"
+M.apAddress = {
+	default = '192.168.10.1',
+	type = 'string',
+	description = 'Access Point mode IP address',
+	regex = '%d+\.%d+\.%d+\.%d+'
+}
+
+-- was: M.DEFAULT_AP_NETMASK = "255.255.255.0"
+M.apNetmask = {
+	default = '255.255.255.0',
+	type = 'string',
+	description = 'Access Point mode netmask',
+	regex = '%d+\.%d+\.%d+\.%d+'
+}
 
---NOTE: proposed notation for baseline configuration (containing defaults as well as type and constraint information)
---the table name is the configuration key; min, max and regex are all optional; type is one of: {int, float, string, ...?}
 M.temperature = {
 	default = 230,
 	type = 'int',
-	description = '...xyzzy',
+	description = '3D printer temperature',
 	min = 0,
 	max = 350
 }
 
-M.ssid = {
-	default = 'd3d-ap-%%MAC_TAIL%%',
-	type = 'int', --one of: {int, float, string, ...?}
-	min = 1,
-	max = 32,
-	regex = '[a-zA-Z0-9 -=+]+'
-}
-
-
 return M

src/test/test_settings.lua

@@ -0,0 +1,66 @@
+local s = require('util.settings')
+local defaults = require('conf_defaults')
+
+local uciConfigFile = '/etc/config/wifibox'
+local uciConfigFileBackup = '/etc/config/wifibox.orig'
+
+local M = {
+	_is_test = true,
+	_skip = { },
+	_wifibox_only = { 'get' }
+}
+
+
+function M:_setup()
+	os.execute('mv -f ' .. uciConfigFile .. ' ' .. uciConfigFileBackup .. ' 2>/dev/null')
+end
+
+function M:_teardown()
+	os.execute('rm -f ' .. uciConfigFile)
+	os.execute('mv -f ' .. uciConfigFileBackup .. ' ' .. uciConfigFile .. ' 2>/dev/null')
+end
+
+
+function M:test_get()
+	local realKey, fakeKey = 'apAddress', 'theAnswer'
+	
+	assert(not s.exists(fakeKey))
+	local fakeValue = s.get(fakeKey)
+	assert(fakeValue == nil)
+	
+	assert(s.exists(realKey))
+	local realValue = s.get(realKey)
+	assert(realValue ~= nil)
+	assert(realValue == defaults.apAddress.default)
+end
+
+function M:test_set()
+	local key = 'apAddress'
+	local goodValue, badValue1, badValue2 = '10.0.0.1', '10.00.1', '10.0.0d.1'
+	
+	assert(s.get(key) == defaults.apAddress.default)
+	assert(s.isDefault(key))
+	
+	assert(s.set(key, goodValue))
+	assert(s.get(key) == goodValue)
+	assert(not s.isDefault(key))
+	
+	assert(s.set(key, badValue1) == nil)
+	assert(s.get(key) == goodValue)
+	
+	assert(s.set(key, badValue2) == nil)
+	assert(s.get(key) == goodValue)
+	
+	assert(s.set(key, nil))
+	assert(s.isDefault(key))
+end
+
+function M:test_setNonExistent()
+	local fakeKey = 'theAnswer'
+	
+	assert(s.get(fakeKey) == nil)
+	assert(s.set(fakeKey, 42) == nil)
+	assert(s.get(fakeKey) == nil)
+end
+
+return M

src/util/settings.lua

@@ -0,0 +1,115 @@
+--[[
+	This settings interface reads and writes its configuration using UCI.
+	The corresponding config file is /etc/config/wifibox. To have an initial
+	set of reasonable settings (and allow users to easily return to them),
+	any key not found in the UCI configuration is looked up in the (immutable)
+	'base configuration' (base_config.lua). This file also contains constraints
+	to check if newly set values are valid.
+]]--
+local u = require('util.utils')
+local baseconfig = require('conf_defaults')
+local uci = require('uci').cursor()
+
+local M = {}
+
+local UCI_CONFIG_NAME = 'wifibox' -- the file under /etc/config
+local UCI_CONFIG_FILE = '/etc/config/' .. UCI_CONFIG_NAME
+local UCI_CONFIG_TYPE = 'settings' -- the section type that will be used in UCI_CONFIG_FILE
+local UCI_CONFIG_SECTION = 'general' -- the section name that will be used in UCI_CONFIG_FILE
+local ERR_NO_SUCH_KEY = "key does not exist"
+
+
+local function toUciValue(v, type)
+	if type == 'bool' then return v and '1' or '0' end
+	return tostring(v)
+end
+
+local function fromUciValue(v, type)
+	if type == 'bool' then
+		return (v == '1') and true or false
+	elseif type == 'float' or type == 'int' then
+		return tonumber(v)
+	else
+		return v
+	end
+	
+end
+
+local function isValid(value, baseTable)
+	local type, min, max, regex = baseTable.type, baseTable.min, baseTable.max, baseTable.regex
+	
+	if type == 'bool' then
+		return isboolean(value) or nil,"invalid bool value"
+	elseif type == 'int' or type == 'float' then
+		local ok = isnumber(value)
+		ok = ok and (type == 'float' or math.floor(value) == value)
+		if min then ok = ok and value >= min end
+		if max then ok = ok and value <= max end
+		return ok or nil,"invalid int/float value"
+	elseif type == 'string' then
+		local ok = true
+		if min then ok = ok and value:len() >= min end
+		if max then ok = ok and value:len() <= max end
+		if regex then ok = ok and value:match(regex) ~= nil end
+		return ok or nil,"invalid string value"
+	end
+	
+	return true
+end
+
+local function getBaseKeyTable(key)
+	local base = baseconfig[key]
+	return type(base) == 'table' and base.default ~= nil and base or nil
+end
+
+
+function M.get(key)
+	local base = getBaseKeyTable(key)
+	
+	if not base then return nil,ERR_NO_SUCH_KEY end
+	
+	local v = base.default
+	local uciV = fromUciValue(uci:get(UCI_CONFIG_NAME, UCI_CONFIG_SECTION, key))
+	
+	return uciV or v
+end
+
+function M.exists(key)
+	return getBaseKeyTable(key) ~= nil
+end
+
+function M.isDefault(key)
+	if not M.exists(key) then return nil,ERR_NO_SUCH_KEY end
+	return uci:get(UCI_CONFIG_NAME, UCI_CONFIG_SECTION, key) == nil
+end
+
+-- pass nil as value to restore default
+function M.set(key, value)
+	local r = u.create(UCI_CONFIG_FILE)
+	uci:set(UCI_CONFIG_NAME, UCI_CONFIG_SECTION, UCI_CONFIG_TYPE)
+	
+	local base = getBaseKeyTable(key)
+	if not base then return nil,ERR_NO_SUCH_KEY end
+	
+	if M.isDefault(key) and value == nil then return true end -- key is default already
+	
+	local current = uci:get(UCI_CONFIG_NAME, UCI_CONFIG_SECTION, key)
+	
+	if fromUciValue(current) == value then return true end
+	
+	if value ~= nil then
+		local valid,m = isValid(value, base)
+		if (valid) then
+			uci:set(UCI_CONFIG_NAME, UCI_CONFIG_SECTION, key, toUciValue(value, base.type))
+		else
+			return nil,m
+		end
+	else
+		uci:delete(UCI_CONFIG_NAME, UCI_CONFIG_SECTION, key)
+	end
+	
+	uci:commit(UCI_CONFIG_NAME)
+	return true
+end
+
+return M