libs/lucid/luasrc/lucid.lua

   1 --[[
   2 LuCI - Lua Development Framework
   3
   4 Copyright 2009 Steven Barth <steven@midlink.org>
   5
   6 Licensed under the Apache License, Version 2.0 (the "License");
   7 you may not use this file except in compliance with the License.
   8 You may obtain a copy of the License at
   9
  10 http://www.apache.org/licenses/LICENSE-2.0
  11
  12 $Id$
  13 ]]
  14
  15 local nixio = require "nixio"
  16 local table = require "table"
  17 local uci = require "luci.model.uci"
  18 local os = require "os"
  19 local io = require "io"
  20
  21 local pairs, require, pcall, assert, type = pairs, require, pcall, assert, type
  22 local ipairs, tonumber, collectgarbage = ipairs, tonumber, collectgarbage
  23
  24
  25 module "luci.lucid"
  26
  27 local slaves = {}
  28 local pollt  = {}
  29 local tickt  = {}
  30 local tpids  = {}
  31 local tcount = 0
  32 local ifaddrs = nixio.getifaddrs()
  33
  34 cursor = uci.cursor()
  35 state  = uci.cursor_state()
  36 UCINAME = "lucid"
  37
  38 local cursor = cursor
  39 local state = state
  40 local UCINAME = UCINAME
  41 local SSTATE = "/tmp/.lucid_store"
  42
  43
  44 --- Starts a new LuCId superprocess.
  45 function start()
  46         state:revert(UCINAME, "main")
  47
  48         prepare()
  49
  50         local detach = cursor:get(UCINAME, "main", "daemonize")
  51         if detach == "1" then
  52                 local stat, code, msg = daemonize()
  53                 if not stat then
  54                         nixio.syslog("crit", "Unable to detach process: " .. msg .. "\n")
  55                         ox.exit(2)
  56                 end
  57         end
  58
  59         state:set(UCINAME, "main", "pid", nixio.getpid())
  60         state:save(UCINAME)
  61
  62         run()
  63 end
  64
  65 --- Returns the PID of the currently active LuCId process.
  66 function running()
  67         local pid = tonumber(state:get(UCINAME, "main", "pid"))
  68         return pid and nixio.kill(pid, 0) and pid
  69 end
  70
  71 --- Stops any running LuCId superprocess.
  72 function stop()
  73         local pid = tonumber(state:get(UCINAME, "main", "pid"))
  74         if pid then
  75                 return nixio.kill(pid, nixio.const.SIGTERM)
  76         end
  77         return false
  78 end
  79
  80 --- Prepares the slaves, daemons and publishers, allocate resources.
  81 function prepare()
  82         local debug = tonumber((cursor:get(UCINAME, "main", "debug")))
  83
  84         nixio.openlog("lucid", "pid", "perror")
  85         if debug ~= 1 then
  86                 nixio.setlogmask("warning")
  87         end
  88
  89         cursor:foreach(UCINAME, "daemon", function(config)
  90                 if config.enabled ~= "1" then
  91                         return
  92                 end
  93
  94                 local key = config[".name"]
  95                 if not config.slave then
  96                         nixio.syslog("crit", "Daemon "..key.." is missing a slave\n")
  97                         os.exit(1)
  98                 else
  99                         nixio.syslog("info", "Initializing daemon " .. key)
 100                 end
 101
 102                 state:revert(UCINAME, key)
 103
 104                 local daemon, code, err = prepare_daemon(config)
 105                 if daemon then
 106                         state:set(UCINAME, key, "status", "started")
 107                         nixio.syslog("info", "Prepared daemon " .. key)
 108                 else
 109                         state:set(UCINAME, key, "status", "error")
 110                         state:set(UCINAME, key, "error", err)
 111                         nixio.syslog("err", "Failed to initialize daemon "..key..": "..
 112                         err .. "\n")
 113                 end
 114         end)
 115 end
 116
 117 --- Run the superprocess if prepared before.
 118 -- This main function of LuCId will wait for events on given file descriptors.
 119 function run()
 120         local pollint = tonumber((cursor:get(UCINAME, "main", "pollinterval")))
 121         local threadlimit = tonumber((cursor:get(UCINAME, "main", "threadlimit")))
 122
 123         while true do
 124                 local stat, code = nixio.poll(pollt, pollint)
 125
 126                 if stat and stat > 0 then
 127                         local ok = false
 128                         for _, polle in ipairs(pollt) do
 129                                 if polle.revents ~= 0 and polle.handler then
 130                                         ok = ok or polle.handler(polle)
 131                                 end
 132                         end
 133                         if not ok then
 134                                 -- Avoid high CPU usage if thread limit is reached
 135                                 nixio.nanosleep(0, 100000000)
 136                         end
 137                 elseif stat == 0 then
 138                         ifaddrs = nixio.getifaddrs()
 139                         collectgarbage("collect")
 140                 end
 141
 142                 for _, cb in ipairs(tickt) do
 143                         cb()
 144                 end
 145
 146                 local pid, stat, code = nixio.wait(-1, "nohang")
 147                 while pid and pid > 0 do
 148                         tcount = tcount - 1
 149                         if tpids[pid] and tpids[pid] ~= true then
 150                                 tpids[pid](pid, stat, code)
 151                         end
 152                         pid, stat, code = nixio.wait(-1, "nohang")
 153                 end
 154         end
 155 end
 156
 157 --- Add a file descriptor for the main loop and associate handler functions.
 158 -- @param polle Table containing: {fd = FILE DESCRIPTOR, events = POLL EVENTS,
 159 -- handler = EVENT HANDLER CALLBACK}
 160 -- @see unregister_pollfd
 161 -- @return boolean status
 162 function register_pollfd(polle)
 163         pollt[#pollt+1] = polle
 164         return true
 165 end
 166
 167 --- Unregister a file desciptor and associate handler from the main loop.
 168 -- @param polle Poll descriptor
 169 -- @see register_pollfd
 170 -- @return boolean status
 171 function unregister_pollfd(polle)
 172         for k, v in ipairs(pollt) do
 173                 if v == polle then
 174                         table.remove(pollt, k)
 175                         return true
 176                 end
 177         end
 178         return false
 179 end
 180
 181 --- Close all registered file descriptors from main loop.
 182 -- This is useful for forked child processes.
 183 function close_pollfds()
 184         for k, v in ipairs(pollt) do
 185                 if v.fd and v.fd.close then
 186                         v.fd:close()
 187                 end
 188         end
 189 end
 190
 191 --- Register a tick function that will be called at each cycle of the main loop.
 192 -- @param cb Callback
 193 -- @see unregister_tick
 194 -- @return boolean status
 195 function register_tick(cb)
 196         tickt[#tickt+1] = cb
 197         return true
 198 end
 199
 200 --- Unregister a tick function from the main loop.
 201 -- @param cb Callback
 202 -- @see register_tick
 203 -- @return boolean status
 204 function unregister_tick(cb)
 205         for k, v in ipairs(tickt) do
 206                 if v == cb then
 207                         table.remove(tickt, k)
 208                         return true
 209                 end
 210         end
 211         return false
 212 end
 213
 214 --- Tests whether a given number of processes can be created.
 215 -- @oaram num Processes to be created
 216 -- @return boolean status
 217 function try_process(num)
 218         local threadlimit = tonumber((cursor:get(UCINAME, "main", "threadlimit")))
 219         return not threadlimit or (threadlimit - tcount) >= (num or 1)
 220 end
 221
 222 --- Create a new child process from a Lua function and assign a destructor.
 223 -- @param threadcb main function of the new process
 224 -- @param waitcb destructor callback
 225 -- @return process identifier or nil, error code, error message
 226 function create_process(threadcb, waitcb)
 227         local threadlimit = tonumber(cursor:get(UCINAME, "main", "threadlimit"))
 228         if threadlimit and tcount >= threadlimit then
 229                 nixio.syslog("warning", "Cannot create thread: process limit reached")
 230                 return nil
 231         end
 232         local pid, code, err = nixio.fork()
 233         if pid and pid ~= 0 then
 234                 tpids[pid] = waitcb
 235                 tcount = tcount + 1
 236         elseif pid == 0 then
 237                 local code = threadcb()
 238                 os.exit(code)
 239         else
 240                 nixio.syslog("err", "Unable to fork(): " .. err)
 241         end
 242         return pid, code, err
 243 end
 244
 245 --- Prepare a daemon from a given configuration table.
 246 -- @param config Configuration data.
 247 -- @return boolean status or nil, error code, error message
 248 function prepare_daemon(config)
 249         nixio.syslog("info", "Preparing daemon " .. config[".name"])
 250         local modname = cursor:get(UCINAME, config.slave)
 251         if not modname then
 252                 return nil, -1, "invalid slave"
 253         end
 254
 255         local stat, module = pcall(require, _NAME .. "." .. modname)
 256         if not stat or not module.prepare_daemon then
 257                 return nil, -2, "slave type not supported"
 258         end
 259
 260         config.slave = prepare_slave(config.slave)
 261
 262         return module.prepare_daemon(config, _M)
 263 end
 264
 265 --- Prepare a slave.
 266 -- @param name slave name
 267 -- @return table containing slave module and configuration or nil, error message
 268 function prepare_slave(name)
 269         local slave = slaves[name]
 270         if not slave then
 271                 local config = cursor:get_all(UCINAME, name)
 272
 273                 local stat, module = pcall(require, config and config.entrypoint)
 274                 if stat then
 275                         slave = {module = module, config = config}
 276                 end
 277         end
 278
 279         if slave then
 280                 return slave
 281         else
 282                 return nil, module
 283         end
 284 end
 285
 286 --- Return a list of available network interfaces on the host.
 287 -- @return table returned by nixio.getifaddrs()
 288 function get_interfaces()
 289         return ifaddrs
 290 end
 291
 292 --- Revoke process privileges.
 293 -- @param user new user name or uid
 294 -- @param group new group name or gid
 295 -- @return boolean status or nil, error code, error message
 296 function revoke_privileges(user, group)
 297         if nixio.getuid() == 0 then
 298                 return nixio.setgid(group) and nixio.setuid(user)
 299         end
 300 end
 301
 302 --- Return a secure UCI cursor.
 303 -- @return UCI cursor
 304 function securestate()
 305         local stat = nixio.fs.stat(SSTATE) or {}
 306         local uid = nixio.getuid()
 307         if stat.type ~= "dir" or (stat.modedec % 100) ~= 0 or stat.uid ~= uid then
 308                 nixio.fs.remover(SSTATE)
 309                 if not nixio.fs.mkdir(SSTATE, 700) then
 310                         local errno = nixio.errno()
 311                         nixio.syslog("err", "Integrity check on secure state failed!")
 312                         return nil, errno, nixio.perror(errno)
 313                 end
 314         end
 315
 316         return uci.cursor(nil, SSTATE)
 317 end
 318
 319 --- Daemonize the process.
 320 -- @return boolean status or nil, error code, error message
 321 function daemonize()
 322         if nixio.getppid() == 1 then
 323                 return
 324         end
 325
 326         local pid, code, msg = nixio.fork()
 327         if not pid then
 328                 return nil, code, msg
 329         elseif pid > 0 then
 330                 os.exit(0)
 331         end
 332
 333         nixio.setsid()
 334         nixio.chdir("/")
 335
 336         local devnull = nixio.open("/dev/null", nixio.open_flags("rdwr"))
 337         nixio.dup(devnull, nixio.stdin)
 338         nixio.dup(devnull, nixio.stdout)
 339         nixio.dup(devnull, nixio.stderr)
 340
 341         return true
 342 end