[project/luci.git] / libs / core / luasrc / util.lua

--[[
LuCI - Utility library

Description:
Several common useful Lua functions

FileId:
$Id$

License:
Copyright 2008 Steven Barth <steven@midlink.org>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

]]--

local io = require "io"
local math = require "math"
local table = require "table"
local debug = require "debug"
local ldebug = require "luci.debug"
local string = require "string"
local coroutine = require "coroutine"

local getmetatable, setmetatable = getmetatable, setmetatable
local rawget, rawset, unpack = rawget, rawset, unpack
local tostring, type, assert = tostring, type, assert 
local ipairs, pairs, loadstring = ipairs, pairs, loadstring
local require, pcall, xpcall = require, pcall, xpcall

--- LuCI utility functions.
module "luci.util"

--
-- Pythonic string formatting extension
--
getmetatable("").__mod = function(a, b)
        if not b then
                return a
        elseif type(b) == "table" then
                return a:format(unpack(b))
        else
                return a:format(b)
        end
end


--
-- Class helper routines
--

--- Create a Class object (Python-style object model).
-- The class object can be instantiated by calling itself.
-- Any class functions or shared parameters can be attached to this object.
-- Attaching a table to the class object makes this table shared between
-- all instances of this class. For object parameters use the __init__ function.
-- Classes can inherit member functions and values from a base class.
-- Class can be instantiated by calling them. All parameters will be passed
-- to the __init__ function of this class - if such a function exists.
-- The __init__ function must be used to set any object parameters that are not shared
-- with other objects of this class. Any return values will be ignored.
-- @param base  The base class to inherit from (optional)
-- @return              A class object
-- @see                 instanceof
-- @see                 clone
function class(base)
        local class = {}

        local create = function(class, ...)
                local inst = setmetatable({}, {__index = class})

                if inst.__init__ then
                        inst:__init__(...)
                end

                return inst
        end

        local classmeta = {__call = create}

        if base then
                classmeta.__index = base
        end

        setmetatable(class, classmeta)
        return class
end

--- Test whether the given object is an instance of the given class.
-- @param object        Object instance
-- @param class         Class object to test against
-- @return                      Boolean indicating whether the object is an instance
-- @see                         class
-- @see                         clone
function instanceof(object, class)
        local meta = getmetatable(object)
        while meta and meta.__index do
                if meta.__index == class then
                        return true
                end
                meta = getmetatable(meta.__index)
        end
        return false
end


--
-- Scope manipulation routines
--

--- Create a new or get an already existing thread local store associated with
-- the current active coroutine. A thread local store is private a table object
-- whose values can't be accessed from outside of the running coroutine.
-- @return      Table value representing the corresponding thread local store
function threadlocal()
        local tbl = {}

        local function get(self, key)
                local c = coroutine.running()
                local thread = coxpt[c] or c or 0
                if not rawget(self, thread) then
                        return nil
                end
                return rawget(self, thread)[key]
        end

        local function set(self, key, value)
                local c = coroutine.running()
                local thread = coxpt[c] or c or 0
                if not rawget(self, thread) then
                        rawset(self, thread, {})
                end
                rawget(self, thread)[key] = value
        end

        setmetatable(tbl, {__index = get, __newindex = set, __mode = "k"})

        return tbl
end


--
-- Debugging routines
--

--- Write given object to stderr.
-- @param obj   Value to write to stderr
-- @return              Boolean indicating whether the write operation was successful
function perror(obj)
        return io.stderr:write(tostring(obj) .. "\n")
end

--- Recursively dumps a table to stdout, useful for testing and debugging.
-- @param t     Table value to dump
-- @param maxdepth      Maximum depth
-- @return      Always nil
function dumptable(t, maxdepth, i, seen)
        i = i or 0
        seen = seen or setmetatable({}, {__mode="k"})
        
        for k,v in pairs(t) do
                perror(string.rep("\t", i) .. tostring(k) .. "\t" .. tostring(v))
                if type(v) == "table" and (not maxdepth or i < maxdepth) then
                        if not seen[v] then
                                seen[v] = true
                                dumptable(v, maxdepth, i+1, seen)
                        else
                                perror(string.rep("\t", i) .. "*** RECURSION ***")
                        end
                end
        end
end


--
-- String and data manipulation routines
--

--- Escapes all occurrences of the given character in given string.
-- @param s     String value containing unescaped characters
-- @param c     String value with character to escape (optional, defaults to "\")
-- @return      String value with each occurrence of character escaped with "\"
function escape(s, c)
        c = c or "\\"
        return s:gsub(c, "\\" .. c)
end

--- Create valid XML PCDATA from given string.
-- @param value String value containing the data to escape
-- @return              String value containing the escaped data
function pcdata(value)
        if not value then return end
        value = tostring(value)
        value = value:gsub("&", "&amp;")
        value = value:gsub('"', "&quot;")
        value = value:gsub("'", "&apos;")
        value = value:gsub("<", "&lt;")
        return value:gsub(">", "&gt;")
end

--- Strip HTML tags from given string.
-- @param value String containing the HTML text
-- @return      String with HTML tags stripped of
function striptags(s)
        return pcdata(s:gsub("</?[A-Za-z][A-Za-z0-9:_%-]*[^>]*>", " "):gsub("%s+", " "))
end

--- Splits given string on a defined separator sequence and return a table
-- containing the resulting substrings. The optional max parameter specifies
-- the number of bytes to process, regardless of the actual length of the given
-- string. The optional last parameter, regex, specifies whether the separator
-- sequence is interpreted as regular expression.
-- @param str           String value containing the data to split up
-- @param pat           String with separator pattern (optional, defaults to "\n")
-- @param max           Maximum times to split (optional)
-- @param regex         Boolean indicating whether to interpret the separator
--                                      pattern as regular expression (optional, default is false)
-- @return                      Table containing the resulting substrings
function split(str, pat, max, regex)
        pat = pat or "\n"
        max = max or #str

        local t = {}
        local c = 1

        if #str == 0 then
                return {""}
        end

        if #pat == 0 then
                return nil
        end

        if max == 0 then
                return str
        end

        repeat
                local s, e = str:find(pat, c, not regex)
                max = max - 1
                if s and max < 0 then
                        t[#t+1] = str:sub(c)
                else
                        t[#t+1] = str:sub(c, s and s - 1)
                end
                c = e and e + 1 or #str + 1
        until not s or max < 0

        return t
end

--- Remove leading and trailing whitespace from given string value.
-- @param str   String value containing whitespace padded data
-- @return              String value with leading and trailing space removed
function trim(str)
        return (str:gsub("^%s*(.-)%s*$", "%1"))
end

--- Parse certain units from the given string and return the canonical integer
-- value or 0 if the unit is unknown. Upper- or lower case is irrelevant.
-- Recognized units are:
--      o "y"   - one year   (60*60*24*366)
--  o "m"       - one month  (60*60*24*31)
--  o "w"       - one week   (60*60*24*7)
--  o "d"       - one day    (60*60*24)
--  o "h"       - one hour       (60*60)
--  o "min"     - one minute (60)
--  o "kb"  - one kilobyte (1024)
--  o "mb"      - one megabyte (1024*1024)
--  o "gb"      - one gigabyte (1024*1024*1024)
--  o "kib" - one si kilobyte (1000)
--  o "mib"     - one si megabyte (1000*1000)
--  o "gib"     - one si gigabyte (1000*1000*1000)
-- @param ustr  String containing a numerical value with trailing unit
-- @return              Number containing the canonical value
function parse_units(ustr)

        local val = 0

        -- unit map
        local map = {
                -- date stuff
                y   = 60 * 60 * 24 * 366,
                m   = 60 * 60 * 24 * 31,
                w   = 60 * 60 * 24 * 7,
                d   = 60 * 60 * 24,
                h   = 60 * 60,
                min = 60,

                -- storage sizes
                kb  = 1024,
                mb  = 1024 * 1024,
                gb  = 1024 * 1024 * 1024,

                -- storage sizes (si)
                kib = 1000,
                mib = 1000 * 1000,
                gib = 1000 * 1000 * 1000
        }

        -- parse input string
        for spec in ustr:lower():gmatch("[0-9%.]+[a-zA-Z]*") do

                local num = spec:gsub("[^0-9%.]+$","")
                local spn = spec:gsub("^[0-9%.]+", "")

                if map[spn] or map[spn:sub(1,1)] then
                        val = val + num * ( map[spn] or map[spn:sub(1,1)] )
                else
                        val = val + num
                end
        end


        return val
end

--- Combines two or more numerically indexed tables into one.
-- @param tbl1  Table value to combine
-- @param tbl2  Table value to combine
-- @param ...   More tables to combine
-- @return              Table value containing all values of given tables
function combine(...)
        local result = {}
        for i, a in ipairs(arg) do
                for j, v in ipairs(a) do
                        result[#result+1] = v
                end
        end
        return result
end

--- Checks whether the given table contains the given value.
-- @param table Table value
-- @param value Value to search within the given table
-- @return              Boolean indicating whether the given value occurs within table
function contains(table, value)
        for k, v in pairs(table) do
                if value == v then
                        return k
                end
        end
        return false
end

--- Update values in given table with the values from the second given table.
-- Both table are - in fact - merged together.
-- @param t                     Table which should be updated
-- @param updates       Table containing the values to update
-- @return                      Always nil
function update(t, updates)
        for k, v in pairs(updates) do
                t[k] = v
        end
end

--- Retrieve all keys of given associative table.
-- @param t     Table to extract keys from
-- @return      Sorted table containing the keys
function keys(t)
        local keys = { }
        if t then
                for k, _ in kspairs(t) do
                        keys[#keys+1] = k
                end
        end
        return keys
end

--- Clones the given object and return it's copy.
-- @param object        Table value to clone
-- @param deep          Boolean indicating whether to do recursive cloning
-- @return                      Cloned table value
function clone(object, deep)
        local copy = {}

        for k, v in pairs(object) do
                if deep and type(v) == "table" then
                        v = clone(v, deep)
                end
                copy[k] = v
        end

        return setmetatable(copy, getmetatable(object))
end


--- Create a dynamic table which automatically creates subtables.
-- @return      Dynamic Table
function dtable()
        return setmetatable({}, { __index =
                function(tbl, key)
                        return rawget(tbl, key)
                         or rawget(rawset(tbl, key, dtable()), key)
                end
        })
end


-- Serialize the contents of a table value.
function _serialize_table(t, seen)
        assert(not seen[t], "Recursion detected.")
        seen[t] = true
        
        local data  = ""
        local idata = ""
        local ilen  = 0

        for k, v in pairs(t) do
                if type(k) ~= "number" or k < 1 or math.floor(k) ~= k or ( k - #t ) > 3 then
                        k = serialize_data(k, seen)
                        v = serialize_data(v, seen)
                        data = data .. ( #data > 0 and ", " or "" ) ..
                                '[' .. k .. '] = ' .. v
                elseif k > ilen then
                        ilen = k
                end
        end

        for i = 1, ilen do
                local v = serialize_data(t[i], seen)
                idata = idata .. ( #idata > 0 and ", " or "" ) .. v
        end             

        return idata .. ( #data > 0 and #idata > 0 and ", " or "" ) .. data
end

--- Recursively serialize given data to lua code, suitable for restoring
-- with loadstring().
-- @param val   Value containing the data to serialize
-- @return              String value containing the serialized code
-- @see                 restore_data
-- @see                 get_bytecode
function serialize_data(val, seen)
        seen = seen or setmetatable({}, {__mode="k"})
        
        if val == nil then
                return "nil"
        elseif type(val) == "number" then
                return val
        elseif type(val) == "string" then
                return "%q" % val
        elseif type(val) == "boolean" then
                return val and "true" or "false"
        elseif type(val) == "function" then
                return "loadstring(%q)" % get_bytecode(val)
        elseif type(val) == "table" then
                return "{ " .. _serialize_table(val, seen) .. " }"
        else
                return '"[unhandled data type:' .. type(val) .. ']"'
        end
end

--- Restore data previously serialized with serialize_data().
-- @param str   String containing the data to restore
-- @return              Value containing the restored data structure
-- @see                 serialize_data
-- @see                 get_bytecode
function restore_data(str)
        return loadstring("return " .. str)()
end


--
-- Byte code manipulation routines
--

--- Return the current runtime bytecode of the given data. The byte code
-- will be stripped before it is returned.
-- @param val   Value to return as bytecode
-- @return              String value containing the bytecode of the given data
function get_bytecode(val)
        local code

        if type(val) == "function" then
                code = string.dump(val)
        else
                code = string.dump( loadstring( "return " .. serialize_data(val) ) )
        end

        return code and strip_bytecode(code)
end

--- Strips unnescessary lua bytecode from given string. Information like line
-- numbers and debugging numbers will be discarded. Original version by
-- Peter Cawley (http://lua-users.org/lists/lua-l/2008-02/msg01158.html)
-- @param code  String value containing the original lua byte code
-- @return              String value containing the stripped lua byte code
function strip_bytecode(code)
        local version, format, endian, int, size, ins, num, lnum = code:byte(5, 12)
        local subint
        if endian == 1 then
                subint = function(code, i, l)
                        local val = 0
                        for n = l, 1, -1 do
                                val = val * 256 + code:byte(i + n - 1)
                        end
                        return val, i + l
                end
        else
                subint = function(code, i, l)
                        local val = 0
                        for n = 1, l, 1 do
                                val = val * 256 + code:byte(i + n - 1)
                        end
                        return val, i + l
                end
        end

        local strip_function
        strip_function = function(code)
                local count, offset = subint(code, 1, size)
                local stripped, dirty = string.rep("\0", size), offset + count
                offset = offset + count + int * 2 + 4
                offset = offset + int + subint(code, offset, int) * ins
                count, offset = subint(code, offset, int)
                for n = 1, count do
                        local t
                        t, offset = subint(code, offset, 1)
                        if t == 1 then
                                offset = offset + 1
                        elseif t == 4 then
                                offset = offset + size + subint(code, offset, size)
                        elseif t == 3 then
                                offset = offset + num
                        elseif t == 254 or t == 9 then
                                offset = offset + lnum
                        end
                end
                count, offset = subint(code, offset, int)
                stripped = stripped .. code:sub(dirty, offset - 1)
                for n = 1, count do
                        local proto, off = strip_function(code:sub(offset, -1))
                        stripped, offset = stripped .. proto, offset + off - 1
                end
                offset = offset + subint(code, offset, int) * int + int
                count, offset = subint(code, offset, int)
                for n = 1, count do
                        offset = offset + subint(code, offset, size) + size + int * 2
                end
                count, offset = subint(code, offset, int)
                for n = 1, count do
                        offset = offset + subint(code, offset, size) + size
                end
                stripped = stripped .. string.rep("\0", int * 3)
                return stripped, offset
        end

        return code:sub(1,12) .. strip_function(code:sub(13,-1))
end


--
-- Sorting iterator functions
--

function _sortiter( t, f )
        local keys = { }

        for k, v in pairs(t) do
                keys[#keys+1] = k
        end

        local _pos = 0
        local _len = table.getn( keys )

        table.sort( keys, f )

        return function()
                _pos = _pos + 1
                if _pos <= _len then
                        return keys[_pos], t[keys[_pos]]
                end
        end
end

--- Return a key, value iterator which returns the values sorted according to
-- the provided callback function.
-- @param t     The table to iterate
-- @param f A callback function to decide the order of elements
-- @return      Function value containing the corresponding iterator
function spairs(t,f)
        return _sortiter( t, f )
end

--- Return a key, value iterator for the given table.
-- The table pairs are sorted by key.
-- @param t     The table to iterate
-- @return      Function value containing the corresponding iterator
function kspairs(t)
        return _sortiter( t )
end

--- Return a key, value iterator for the given table.
-- The table pairs are sorted by value.
-- @param t     The table to iterate
-- @return      Function value containing the corresponding iterator
function vspairs(t)
        return _sortiter( t, function (a,b) return t[a] < t[b] end )
end


--
-- System utility functions
--

--- Test whether the current system is operating in big endian mode.
-- @return      Boolean value indicating whether system is big endian
function bigendian()
        return string.byte(string.dump(function() end), 7) == 0
end

--- Execute given commandline and gather stdout.
-- @param command       String containing command to execute
-- @return                      String containing the command's stdout
function exec(command)
        local pp   = io.popen(command)
        local data = pp:read("*a")
        pp:close()

        return data
end

--- Return a line-buffered iterator over the output of given command.
-- @param command       String containing the command to execute
-- @return                      Iterator
function execi(command)
        local pp = io.popen(command)

        return pp and function()
                local line = pp:read()
                
                if not line then
                        pp:close()
                end
                
                return line
        end
end

-- Deprecated
function execl(command)
        local pp   = io.popen(command)
        local line = ""
        local data = {}

        while true do
                line = pp:read()
                if (line == nil) then break end
                data[#data+1] = line
        end
        pp:close()

        return data
end

--- Returns the absolute path to LuCI base directory.
-- @return              String containing the directory path
function libpath()
        return require "luci.fs".dirname(ldebug.__file__)
end


--
-- Coroutine safe xpcall and pcall versions modified for Luci
-- original version:
-- coxpcall 1.13 - Copyright 2005 - Kepler Project (www.keplerproject.org)
--
-- Copyright © 2005 Kepler Project.
-- Permission is hereby granted, free of charge, to any person obtaining a
-- copy of this software and associated documentation files (the "Software"),
-- to deal in the Software without restriction, including without limitation
-- the rights to use, copy, modify, merge, publish, distribute, sublicense,
-- and/or sell copies of the Software, and to permit persons to whom the
-- Software is furnished to do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be
-- included in all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-- EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
-- OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-- IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
-- DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-- TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
-- OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

local performResume, handleReturnValue
local oldpcall, oldxpcall = pcall, xpcall
coxpt = {}
setmetatable(coxpt, {__mode = "kv"})

-- Identity function for copcall
local function copcall_id(trace, ...)
  return ...
end

--- This is a coroutine-safe drop-in replacement for Lua's "xpcall"-function
-- @param f             Lua function to be called protected
-- @param err   Custom error handler
-- @param ...   Parameters passed to the function
-- @return              A boolean whether the function call succeeded and the return
--                              values of either the function or the error handler
function coxpcall(f, err, ...)
        local res, co = oldpcall(coroutine.create, f)
        if not res then
                local params = {...}
                local newf = function() return f(unpack(params)) end
                co = coroutine.create(newf)
        end
        local c = coroutine.running()
        coxpt[co] = coxpt[c] or c or 0

        return performResume(err, co, ...)
end

--- This is a coroutine-safe drop-in replacement for Lua's "pcall"-function
-- @param f             Lua function to be called protected
-- @param ...   Parameters passed to the function
-- @return              A boolean whether the function call succeeded and the returns
--                              values of the function or the error object
function copcall(f, ...)
        return coxpcall(f, copcall_id, ...)
end

-- Handle return value of protected call
function handleReturnValue(err, co, status, ...)
        if not status then
                return false, err(debug.traceback(co, (...)), ...)
        end
        if coroutine.status(co) == 'suspended' then
                return performResume(err, co, coroutine.yield(...))
        else
                return true, ...
        end
end

-- Resume execution of protected function call
function performResume(err, co, ...)
        return handleReturnValue(err, co, coroutine.resume(co, ...))
end