libs/core/luasrc/util.lua

   1 --[[
   2 LuCI - Utility library
   3
   4 Description:
   5 Several common useful Lua functions
   6
   7 FileId:
   8 $Id$
   9
  10 License:
  11 Copyright 2008 Steven Barth <steven@midlink.org>
  12
  13 Licensed under the Apache License, Version 2.0 (the "License");
  14 you may not use this file except in compliance with the License.
  15 You may obtain a copy of the License at
  16
  17         http://www.apache.org/licenses/LICENSE-2.0
  18
  19 Unless required by applicable law or agreed to in writing, software
  20 distributed under the License is distributed on an "AS IS" BASIS,
  21 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  22 See the License for the specific language governing permissions and
  23 limitations under the License.
  24
  25 ]]--
  26
  27 -- LuCI utility functions.
  28 module("luci.util", package.seeall)
  29
  30 --
  31 -- Class helper routines
  32 --
  33
  34 --- Creates a Class object (Python-style object model)
  35 -- Creates a new class object which can be instantiated by calling itself.
  36 -- Any class functions or shared parameters can be attached to this object.
  37 -- Attaching a table to the class object makes this table shared between
  38 -- all instances of this class. For object parameters use the __init__ function.
  39 -- Classes can inherit member functions and values from a base class.
  40 -- Class can be instantiated by calling them. All parameters will be passed
  41 -- to the __init__ function of this class - if such a function exists.
  42 -- The __init__ function must be used to set any object parameters that are not shared
  43 -- with other objects of this class. Any return values will be ignored.
  44 -- @param base  The base class to inherit from (optional)
  45 -- @return              A class object
  46 -- @see                 instanceof
  47 -- @see                 clone
  48 function class(base)
  49         local class = {}
  50
  51         local create = function(class, ...)
  52                 local inst = {}
  53                 setmetatable(inst, {__index = class})
  54
  55                 if inst.__init__ then
  56                         local stat, err = copcall(inst.__init__, inst, ...)
  57                         if not stat then
  58                                 error(err)
  59                         end
  60                 end
  61
  62                 return inst
  63         end
  64
  65         local classmeta = {__call = create}
  66
  67         if base then
  68                 classmeta.__index = base
  69         end
  70
  71         setmetatable(class, classmeta)
  72         return class
  73 end
  74
  75 --- Test whether the given object is an instance of the given class.
  76 -- @param object        Object instance
  77 -- @param class         Class object to test against
  78 -- @return                      Boolean indicating wheather the object is an instance
  79 -- @see                         class
  80 -- @see                         clone
  81 function instanceof(object, class)
  82         local meta = getmetatable(object)
  83         while meta and meta.__index do
  84                 if meta.__index == class then
  85                         return true
  86                 end
  87                 meta = getmetatable(meta.__index)
  88         end
  89         return false
  90 end
  91
  92
  93 --
  94 -- Scope manipulation routines
  95 --
  96
  97 --- Replace a function scope with a shallow copy of itself.
  98 -- This is useful if you want to get rid of several unwanted side effects
  99 -- while changing the scope of a certain Lua function.
 100 -- @param f             Lua function
 101 function resfenv(f)
 102         setfenv(f, clone(getfenv(f)))
 103 end
 104
 105 --- Store given object associated with given key in the scope of a function.
 106 -- @param f             Lua function
 107 -- @param key   String value containg the key of the object to store
 108 -- @param obj   Object to store in the scope
 109 -- @return              Always nil
 110 -- @see updfenv
 111 -- @see resfenv
 112 function extfenv(f, key, obj)
 113         local scope = getfenv(f)
 114         scope[key] = obj
 115 end
 116
 117 --- Extend the scope of a function with the contents of a table
 118 -- @param f             Lua function
 119 -- @param key   String value containg the key of the object to store
 120 -- @param obj   Object to store in the scope
 121 -- @return              Always nil
 122 -- @see extfenv
 123 -- @see resfenv
 124 function updfenv(f, extscope)
 125         update(getfenv(f), extscope)
 126 end
 127
 128 --- Create a new or get an already existing thread local store associated with
 129 -- the current active coroutine. A thread local store is private a table object
 130 -- whose values can't be accessed from outside of the running coroutine.
 131 -- @return      Table value representing the corresponding thread local store
 132 function threadlocal()
 133         local tbl = {}
 134
 135         local function get(self, key)
 136                 local c = coroutine.running()
 137                 local thread = coxpt[c] or c or 0
 138                 if not rawget(self, thread) then
 139                         return nil
 140                 end
 141                 return rawget(self, thread)[key]
 142         end
 143
 144         local function set(self, key, value)
 145                 local c = coroutine.running()
 146                 local thread = coxpt[c] or c or 0
 147                 if not rawget(self, thread) then
 148                         rawset(self, thread, {})
 149                 end
 150                 rawget(self, thread)[key] = value
 151         end
 152
 153         setmetatable(tbl, {__index = get, __newindex = set, __mode = "k"})
 154
 155         return tbl
 156 end
 157
 158
 159 --
 160 -- Debugging routines
 161 --
 162
 163 --- Write given object to stderr.
 164 -- @param obj   Value to write to stderr
 165 -- @return              Boolean indicating wheather the write operation was successful
 166 function perror(obj)
 167         return io.stderr:write(tostring(obj) .. "\n")
 168 end
 169
 170 --- Recursively dumps a table to stdout, useful for testing and debugging.
 171 -- @param t     Table value to dump
 172 -- @param i     Number of tabs to prepend to each line
 173 -- @return      Always nil
 174 function dumptable(t, i)
 175         i = i or 0
 176         for k,v in pairs(t) do
 177                 print(string.rep("\t", i) .. tostring(k), tostring(v))
 178                 if type(v) == "table" then
 179                         dumptable(v, i+1)
 180                 end
 181         end
 182 end
 183
 184
 185 --
 186 -- String and data manipulation routines
 187 --
 188
 189 --- Escapes all occurences of the given character in given string.
 190 -- @param s     String value containing unescaped characters
 191 -- @param c     String value with character to escape (optional, defaults to "\")
 192 -- @return      String value with each occurence of character escaped with "\"
 193 function escape(s, c)
 194         c = c or "\\"
 195         return s:gsub(c, "\\" .. c)
 196 end
 197
 198 --- Create valid XML PCDATA from given string.
 199 -- @param value String value containing the data to escape
 200 -- @return              String value containing the escaped data
 201 function pcdata(value)
 202         value = value:gsub("&", "&amp;")
 203         value = value:gsub('"', "&quot;")
 204         value = value:gsub("'", "&apos;")
 205         value = value:gsub("<", "&lt;")
 206         return value:gsub(">", "&gt;")
 207 end
 208
 209 --- Splits given string on a defined seperator sequence and return a table
 210 -- containing the resulting substrings. The optional max parameter specifies
 211 -- the number of bytes to process, regardless of the actual length of the given
 212 -- string. The optional last parameter, regex, sepcifies wheather the separator
 213 -- sequence is interpreted as regular expression.
 214 -- @param str           String value containing the data to split up
 215 -- @param pat           String with separator pattern (optional, defaults to "\n")
 216 -- @param max           Num of bytes to process (optional, default is string length)
 217 -- @param regexp        Boolean indicating wheather to interprete the separator
 218 --                                      pattern as regular expression (optional, default is false)
 219 -- @return                      Table containing the resulting substrings
 220 function split(str, pat, max, regex)
 221         pat = pat or "\n"
 222         max = max or #str
 223
 224         local t = {}
 225         local c = 1
 226
 227         if #str == 0 then
 228                 return {""}
 229         end
 230
 231         if #pat == 0 then
 232                 return nil
 233         end
 234
 235         if max == 0 then
 236                 return str
 237         end
 238
 239         repeat
 240                 local s, e = str:find(pat, c, not regex)
 241                 max = max - 1
 242                 if s and max < 0 then
 243                         table.insert(t, str:sub(c))
 244                 else
 245                         table.insert(t, str:sub(c, s and s - 1))
 246                 end
 247                 c = e and e + 1 or #str + 1
 248         until not s or max < 0
 249
 250         return t
 251 end
 252
 253 --- Remove leading and trailing whitespace from given string value.
 254 -- @param str   String value containing whitespace padded data
 255 -- @return              String value with leading and trailing space removed
 256 function trim(str)
 257         local s = str:gsub("^%s*(.-)%s*$", "%1")
 258         return s
 259 end
 260
 261 --- Parse certain units from the given string and return the canonical integer
 262 -- value or 0 if the unit is unknown. Upper- or lowercase is irrelevant.
 263 -- Recognized units are:
 264 --      o "y"   - one year   (60*60*24*366)
 265 --  o "m"       - one month  (60*60*24*31)
 266 --  o "w"       - one week   (60*60*24*7)
 267 --  o "d"       - one day    (60*60*24)
 268 --  o "h"       - one hour       (60*60)
 269 --  o "min"     - one minute (60)
 270 --  o "kb"  - one kilobyte (1024)
 271 --  o "mb"      - one megabyte (1024*1024)
 272 --  o "gb"      - one gigabyte (1024*1024*1024)
 273 --  o "kib" - one si kilobyte (1000)
 274 --  o "mib"     - one si megabyte (1000*1000)
 275 --  o "gib"     - one si gigabyte (1000*1000*1000)
 276 -- @param ustr  String containing a numerical value with trailing unit
 277 -- @return              Number containing the canonical value
 278 function parse_units(ustr)
 279
 280         local val = 0
 281
 282         -- unit map
 283         local map = {
 284                 -- date stuff
 285                 y   = 60 * 60 * 24 * 366,
 286                 m   = 60 * 60 * 24 * 31,
 287                 w   = 60 * 60 * 24 * 7,
 288                 d   = 60 * 60 * 24,
 289                 h   = 60 * 60,
 290                 min = 60,
 291
 292                 -- storage sizes
 293                 kb  = 1024,
 294                 mb  = 1024 * 1024,
 295                 gb  = 1024 * 1024 * 1024,
 296
 297                 -- storage sizes (si)
 298                 kib = 1000,
 299                 mib = 1000 * 1000,
 300                 gib = 1000 * 1000 * 1000
 301         }
 302
 303         -- parse input string
 304         for spec in ustr:lower():gmatch("[0-9%.]+[a-zA-Z]*") do
 305
 306                 local num = spec:gsub("[^0-9%.]+$","")
 307                 local spn = spec:gsub("^[0-9%.]+", "")
 308
 309                 if map[spn] or map[spn:sub(1,1)] then
 310                         val = val + num * ( map[spn] or map[spn:sub(1,1)] )
 311                 else
 312                         val = val + num
 313                 end
 314         end
 315
 316
 317         return val
 318 end
 319
 320 --- Combines two or more numerically indexed tables into one.
 321 -- @param tbl1  Table value to combine
 322 -- @param tbl2  Table value to combine
 323 -- @param tblN  More values to combine
 324 -- @return              Table value containing all values of given tables
 325 function combine(...)
 326         local result = {}
 327         for i, a in ipairs(arg) do
 328                 for j, v in ipairs(a) do
 329                         table.insert(result, v)
 330                 end
 331         end
 332         return result
 333 end
 334
 335 --- Checks whether the given table contains the given value.
 336 -- @param table Table value
 337 -- @param value Value to search within the given table
 338 -- @return              Boolean indicating wheather the given value occurs within table
 339 function contains(table, value)
 340         for k, v in pairs(table) do
 341                 if value == v then
 342                         return k
 343                 end
 344         end
 345         return false
 346 end
 347
 348 --- Update values in given table with the values from the second given table.
 349 -- Both table are - in fact - merged together.
 350 -- @param t                     Table which should be updated
 351 -- @param updates       Table containing the values to update
 352 -- @return                      Always nil
 353 function update(t, updates)
 354         for k, v in pairs(updates) do
 355                 t[k] = v
 356         end
 357 end
 358
 359 --- Clones the given object and return it's copy.
 360 -- @param object        Table value to clone
 361 -- @param deep          Boolean indicating wheather to do recursive cloning
 362 -- @return                      Cloned table value
 363 function clone(object, deep)
 364         local copy = {}
 365
 366         for k, v in pairs(object) do
 367                 if deep and type(v) == "table" then
 368                         v = clone(v, deep)
 369                 end
 370                 copy[k] = v
 371         end
 372
 373         setmetatable(copy, getmetatable(object))
 374
 375         return copy
 376 end
 377
 378
 379 --
 380 -- Byte code manipulation routines
 381 --
 382
 383 --- Return the current runtime bytecode of the given function. The byte code
 384 -- will be stripped before it is returned.
 385 -- @param f     Function value to return as bytecode
 386 -- @return      String value containing the bytecode of the given function
 387 function get_bytecode(f)
 388         local d = string.dump(f)
 389         return d and strip_bytecode(d)
 390 end
 391
 392 --- Strips unnescessary lua bytecode from given string. Information like line
 393 -- numbers and debugging numbers will be discarded. Original version by
 394 -- Peter Cawley (http://lua-users.org/lists/lua-l/2008-02/msg01158.html)
 395 -- @param code  String value containing the original lua byte code
 396 -- @return              String value containing the stripped lua byte code
 397 function strip_bytecode(code)
 398         local version, format, endian, int, size, ins, num, lnum = code:byte(5, 12)
 399         local subint
 400         if endian == 1 then
 401                 subint = function(code, i, l)
 402                         local val = 0
 403                         for n = l, 1, -1 do
 404                                 val = val * 256 + code:byte(i + n - 1)
 405                         end
 406                         return val, i + l
 407                 end
 408         else
 409                 subint = function(code, i, l)
 410                         local val = 0
 411                         for n = 1, l, 1 do
 412                                 val = val * 256 + code:byte(i + n - 1)
 413                         end
 414                         return val, i + l
 415                 end
 416         end
 417
 418         local strip_function
 419         strip_function = function(code)
 420                 local count, offset = subint(code, 1, size)
 421                 local stripped, dirty = string.rep("\0", size), offset + count
 422                 offset = offset + count + int * 2 + 4
 423                 offset = offset + int + subint(code, offset, int) * ins
 424                 count, offset = subint(code, offset, int)
 425                 for n = 1, count do
 426                         local t
 427                         t, offset = subint(code, offset, 1)
 428                         if t == 1 then
 429                                 offset = offset + 1
 430                         elseif t == 4 then
 431                                 offset = offset + size + subint(code, offset, size)
 432                         elseif t == 3 then
 433                                 offset = offset + num
 434                         elseif t == 254 or t == 9 then
 435                                 offset = offset + lnum
 436                         end
 437                 end
 438                 count, offset = subint(code, offset, int)
 439                 stripped = stripped .. code:sub(dirty, offset - 1)
 440                 for n = 1, count do
 441                         local proto, off = strip_function(code:sub(offset, -1))
 442                         stripped, offset = stripped .. proto, offset + off - 1
 443                 end
 444                 offset = offset + subint(code, offset, int) * int + int
 445                 count, offset = subint(code, offset, int)
 446                 for n = 1, count do
 447                         offset = offset + subint(code, offset, size) + size + int * 2
 448                 end
 449                 count, offset = subint(code, offset, int)
 450                 for n = 1, count do
 451                         offset = offset + subint(code, offset, size) + size
 452                 end
 453                 stripped = stripped .. string.rep("\0", int * 3)
 454                 return stripped, offset
 455         end
 456
 457         return code:sub(1,12) .. strip_function(code:sub(13,-1))
 458 end
 459
 460
 461 --
 462 -- Sorting iterator functions
 463 --
 464
 465 function _sortiter( t, f )
 466         local keys = { }
 467
 468         for k, v in pairs(t) do
 469                 table.insert( keys, k )
 470         end
 471
 472         local _pos = 0
 473         local _len = table.getn( keys )
 474
 475         table.sort( keys, f )
 476
 477         return function()
 478                 _pos = _pos + 1
 479                 if _pos <= _len then
 480                         return keys[_pos], t[keys[_pos]]
 481                 end
 482         end
 483 end
 484
 485 --- Return a key, value iterator which returns the values sorted according to
 486 -- the provided callback function.
 487 -- @param t     The table to iterate
 488 -- @param f A callback function to decide the order of elements
 489 -- @return      Function value containing the corresponding iterator
 490 function spairs(t,f)
 491         return _sortiter( t, f )
 492 end
 493
 494 --- Return a key, value iterator for the given table.
 495 -- The table pairs are sorted by key.
 496 -- @param t     The table to iterate
 497 -- @return      Function value containing the corresponding iterator
 498 function kspairs(t)
 499         return _sortiter( t )
 500 end
 501
 502 --- Return a key, value iterator for the given table.
 503 -- The table pairs are sorted by value.
 504 -- @param t     The table to iterate
 505 -- @return      Function value containing the corresponding iterator
 506 function vspairs(t)
 507         return _sortiter( t, function (a,b) return t[a] < t[b] end )
 508 end
 509
 510
 511 --
 512 -- Coroutine safe xpcall and pcall versions modified for Luci
 513 -- original version:
 514 -- coxpcall 1.13 - Copyright 2005 - Kepler Project (www.keplerproject.org)
 515 --
 516
 517 local performResume, handleReturnValue
 518 local oldpcall, oldxpcall = pcall, xpcall
 519 coxpt = {}
 520 setmetatable(coxpt, {__mode = "kv"})
 521
 522 --- Identity function for copcall
 523 local function copcall_id(trace, ...)
 524   return ...
 525 end
 526
 527 --- This is a coroutine-safe drop-in replacement for Lua's "xpcall"-function
 528 -- @param f             Lua function to be called protected
 529 -- @param err   Custom error handler
 530 -- @param ...   Parameters passed to the function
 531 -- @return              A boolean whether the function call succeeded and the return
 532 --                              values of either the function or the error handler
 533 function coxpcall(f, err, ...)
 534         local res, co = oldpcall(coroutine.create, f)
 535         if not res then
 536                 local params = {...}
 537                 local newf = function() return f(unpack(params)) end
 538                 co = coroutine.create(newf)
 539         end
 540         local c = coroutine.running()
 541         coxpt[co] = coxpt[c] or c or 0
 542
 543         return performResume(err, co, ...)
 544 end
 545
 546 --- This is a coroutine-safe drop-in replacement for Lua's "pcall"-function
 547 -- @param f             Lua function to be called protected
 548 -- @param ...   Parameters passed to the function
 549 -- @return              A boolean whether the function call succeeded and the returns
 550 --                              values of the function or the error object
 551 function copcall(f, ...)
 552         return coxpcall(f, copcall_id, ...)
 553 end
 554
 555 --- Handle return value of protected call
 556 function handleReturnValue(err, co, status, ...)
 557         if not status then
 558                 return false, err(debug.traceback(co, (...)), ...)
 559         end
 560         if coroutine.status(co) == 'suspended' then
 561                 return performResume(err, co, coroutine.yield(...))
 562         else
 563                 return true, ...
 564         end
 565 end
 566
 567 --- Resume execution of protected function call
 568 function performResume(err, co, ...)
 569         return handleReturnValue(err, co, coroutine.resume(co, ...))
 570 end