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 --- Create a Class object (Python-style object model).
  35 -- The class object 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 whether 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 whether 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 occurrences 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 occurrence 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 separator 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, specifies whether 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           Maximum times to split (optional)
 217 -- @param regex         Boolean indicating whether to interpret 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*$", "%1")
 258         return s
 259 end
 260
 261 --- Parse certain units from the given string and return the canonical integer
 262 -- value or 0 if the unit is unknown. Upper- or lower case is irrelevant.
 263 -- Recognized units are:
 264 --      o "y"   - one year   (60*60*24*366)
 265 --  o "m"       - one month  (60*60*24*31)
 266 --  o "w"       - one week   (60*60*24*7)
 267 --  o "d"       - one day    (60*60*24)
 268 --  o "h"       - one hour       (60*60)
 269 --  o "min"     - one minute (60)
 270 --  o "kb"  - one kilobyte (1024)
 271 --  o "mb"      - one megabyte (1024*1024)
 272 --  o "gb"      - one gigabyte (1024*1024*1024)
 273 --  o "kib" - one si kilobyte (1000)
 274 --  o "mib"     - one si megabyte (1000*1000)
 275 --  o "gib"     - one si gigabyte (1000*1000*1000)
 276 -- @param ustr  String containing a numerical value with trailing unit
 277 -- @return              Number containing the canonical value
 278 function parse_units(ustr)
 279
 280         local val = 0
 281
 282         -- unit map
 283         local map = {
 284                 -- date stuff
 285                 y   = 60 * 60 * 24 * 366,
 286                 m   = 60 * 60 * 24 * 31,
 287                 w   = 60 * 60 * 24 * 7,
 288                 d   = 60 * 60 * 24,
 289                 h   = 60 * 60,
 290                 min = 60,
 291
 292                 -- storage sizes
 293                 kb  = 1024,
 294                 mb  = 1024 * 1024,
 295                 gb  = 1024 * 1024 * 1024,
 296
 297                 -- storage sizes (si)
 298                 kib = 1000,
 299                 mib = 1000 * 1000,
 300                 gib = 1000 * 1000 * 1000
 301         }
 302
 303         -- parse input string
 304         for spec in ustr:lower():gmatch("[0-9%.]+[a-zA-Z]*") do
 305
 306                 local num = spec:gsub("[^0-9%.]+$","")
 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 ...   More tables 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 whether 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 whether 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 --- Create a dynamic table which automatically creates subtables.
 380 -- @return      Dynamic Table
 381 function dtable()
 382         return setmetatable({}, { __index =
 383                 function(tbl, key)
 384                         return rawget(tbl, key)
 385                          or rawget(rawset(tbl, key, dtable()), key)
 386                 end
 387         })
 388 end
 389
 390
 391 -- Serialize the contents of a table value.
 392 function _serialize_table(t)
 393         local data = ""
 394         for k, v in pairs(t) do
 395                 k = serialize_data(k)
 396                 v = serialize_data(v)
 397                 data = data .. ( #data > 0 and ", " or "" ) ..
 398                         '[' .. k .. '] = ' .. v
 399         end
 400         return data
 401 end
 402
 403 --- Recursively serialize given data to lua code, suitable for restoring
 404 -- with loadstring().
 405 -- @param val   Value containing the data to serialize
 406 -- @return              String value containing the serialized code
 407 -- @see                 restore_data
 408 -- @see                 get_bytecode
 409 function serialize_data(val)
 410         if val == nil then
 411                 return "nil"
 412         elseif type(val) == "number" then
 413                 return val
 414         elseif type(val) == "string" then
 415                 return string.format("%q", val)
 416         elseif type(val) == "boolean" then
 417                 return val and "true" or "false"
 418         elseif type(val) == "function" then
 419                 return string.format("loadstring(%q)", get_bytecode(val))
 420         elseif type(val) == "table" then
 421                 return "{ " .. _serialize_table(val) .. " }"
 422         else
 423                 return '"[unhandled data type:' .. type(val) .. ']"'
 424         end
 425 end
 426
 427 --- Restore data previously serialized with serialize_data().
 428 -- @param str   String containing the data to restore
 429 -- @return              Value containing the restored data structure
 430 -- @see                 serialize_data
 431 -- @see                 get_bytecode
 432 function restore_data(str)
 433         return loadstring("return " .. str)()
 434 end
 435
 436
 437 --
 438 -- Byte code manipulation routines
 439 --
 440
 441 --- Return the current runtime bytecode of the given data. The byte code
 442 -- will be stripped before it is returned.
 443 -- @param val   Value to return as bytecode
 444 -- @return              String value containing the bytecode of the given data
 445 function get_bytecode(val)
 446         local code
 447
 448         if type(val) == "function" then
 449                 code = string.dump(val)
 450         else
 451                 code = string.dump( loadstring( "return " .. serialize_data(val) ) )
 452         end
 453
 454         return code and strip_bytecode(code)
 455 end
 456
 457 --- Strips unnescessary lua bytecode from given string. Information like line
 458 -- numbers and debugging numbers will be discarded. Original version by
 459 -- Peter Cawley (http://lua-users.org/lists/lua-l/2008-02/msg01158.html)
 460 -- @param code  String value containing the original lua byte code
 461 -- @return              String value containing the stripped lua byte code
 462 function strip_bytecode(code)
 463         local version, format, endian, int, size, ins, num, lnum = code:byte(5, 12)
 464         local subint
 465         if endian == 1 then
 466                 subint = function(code, i, l)
 467                         local val = 0
 468                         for n = l, 1, -1 do
 469                                 val = val * 256 + code:byte(i + n - 1)
 470                         end
 471                         return val, i + l
 472                 end
 473         else
 474                 subint = function(code, i, l)
 475                         local val = 0
 476                         for n = 1, l, 1 do
 477                                 val = val * 256 + code:byte(i + n - 1)
 478                         end
 479                         return val, i + l
 480                 end
 481         end
 482
 483         local strip_function
 484         strip_function = function(code)
 485                 local count, offset = subint(code, 1, size)
 486                 local stripped, dirty = string.rep("\0", size), offset + count
 487                 offset = offset + count + int * 2 + 4
 488                 offset = offset + int + subint(code, offset, int) * ins
 489                 count, offset = subint(code, offset, int)
 490                 for n = 1, count do
 491                         local t
 492                         t, offset = subint(code, offset, 1)
 493                         if t == 1 then
 494                                 offset = offset + 1
 495                         elseif t == 4 then
 496                                 offset = offset + size + subint(code, offset, size)
 497                         elseif t == 3 then
 498                                 offset = offset + num
 499                         elseif t == 254 or t == 9 then
 500                                 offset = offset + lnum
 501                         end
 502                 end
 503                 count, offset = subint(code, offset, int)
 504                 stripped = stripped .. code:sub(dirty, offset - 1)
 505                 for n = 1, count do
 506                         local proto, off = strip_function(code:sub(offset, -1))
 507                         stripped, offset = stripped .. proto, offset + off - 1
 508                 end
 509                 offset = offset + subint(code, offset, int) * int + int
 510                 count, offset = subint(code, offset, int)
 511                 for n = 1, count do
 512                         offset = offset + subint(code, offset, size) + size + int * 2
 513                 end
 514                 count, offset = subint(code, offset, int)
 515                 for n = 1, count do
 516                         offset = offset + subint(code, offset, size) + size
 517                 end
 518                 stripped = stripped .. string.rep("\0", int * 3)
 519                 return stripped, offset
 520         end
 521
 522         return code:sub(1,12) .. strip_function(code:sub(13,-1))
 523 end
 524
 525
 526 --
 527 -- Sorting iterator functions
 528 --
 529
 530 function _sortiter( t, f )
 531         local keys = { }
 532
 533         for k, v in pairs(t) do
 534                 table.insert( keys, k )
 535         end
 536
 537         local _pos = 0
 538         local _len = table.getn( keys )
 539
 540         table.sort( keys, f )
 541
 542         return function()
 543                 _pos = _pos + 1
 544                 if _pos <= _len then
 545                         return keys[_pos], t[keys[_pos]]
 546                 end
 547         end
 548 end
 549
 550 --- Return a key, value iterator which returns the values sorted according to
 551 -- the provided callback function.
 552 -- @param t     The table to iterate
 553 -- @param f A callback function to decide the order of elements
 554 -- @return      Function value containing the corresponding iterator
 555 function spairs(t,f)
 556         return _sortiter( t, f )
 557 end
 558
 559 --- Return a key, value iterator for the given table.
 560 -- The table pairs are sorted by key.
 561 -- @param t     The table to iterate
 562 -- @return      Function value containing the corresponding iterator
 563 function kspairs(t)
 564         return _sortiter( t )
 565 end
 566
 567 --- Return a key, value iterator for the given table.
 568 -- The table pairs are sorted by value.
 569 -- @param t     The table to iterate
 570 -- @return      Function value containing the corresponding iterator
 571 function vspairs(t)
 572         return _sortiter( t, function (a,b) return t[a] < t[b] end )
 573 end
 574
 575
 576 --
 577 -- Coroutine safe xpcall and pcall versions modified for Luci
 578 -- original version:
 579 -- coxpcall 1.13 - Copyright 2005 - Kepler Project (www.keplerproject.org)
 580 --
 581
 582 local performResume, handleReturnValue
 583 local oldpcall, oldxpcall = pcall, xpcall
 584 coxpt = {}
 585 setmetatable(coxpt, {__mode = "kv"})
 586
 587 -- Identity function for copcall
 588 local function copcall_id(trace, ...)
 589   return ...
 590 end
 591
 592 --- This is a coroutine-safe drop-in replacement for Lua's "xpcall"-function
 593 -- @param f             Lua function to be called protected
 594 -- @param err   Custom error handler
 595 -- @param ...   Parameters passed to the function
 596 -- @return              A boolean whether the function call succeeded and the return
 597 --                              values of either the function or the error handler
 598 function coxpcall(f, err, ...)
 599         local res, co = oldpcall(coroutine.create, f)
 600         if not res then
 601                 local params = {...}
 602                 local newf = function() return f(unpack(params)) end
 603                 co = coroutine.create(newf)
 604         end
 605         local c = coroutine.running()
 606         coxpt[co] = coxpt[c] or c or 0
 607
 608         return performResume(err, co, ...)
 609 end
 610
 611 --- This is a coroutine-safe drop-in replacement for Lua's "pcall"-function
 612 -- @param f             Lua function to be called protected
 613 -- @param ...   Parameters passed to the function
 614 -- @return              A boolean whether the function call succeeded and the returns
 615 --                              values of the function or the error object
 616 function copcall(f, ...)
 617         return coxpcall(f, copcall_id, ...)
 618 end
 619
 620 -- Handle return value of protected call
 621 function handleReturnValue(err, co, status, ...)
 622         if not status then
 623                 return false, err(debug.traceback(co, (...)), ...)
 624         end
 625         if coroutine.status(co) == 'suspended' then
 626                 return performResume(err, co, coroutine.yield(...))
 627         else
 628                 return true, ...
 629         end
 630 end
 631
 632 -- Resume execution of protected function call
 633 function performResume(err, co, ...)
 634         return handleReturnValue(err, co, coroutine.resume(co, ...))
 635 end