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                         nixio.syslog("info", "Buried thread: " .. pid)
 149                         if tpids[pid] then
 150                                 tcount = tcount - 1
 151                                 if tpids[pid] ~= true then
 152                                         tpids[pid](pid, stat, code)
 153                                 end
 154                         end
 155                         pid, stat, code = nixio.wait(-1, "nohang")
 156                 end
 157         end
 158 end
 159
 160 --- Add a file descriptor for the main loop and associate handler functions.
 161 -- @param polle Table containing: {fd = FILE DESCRIPTOR, events = POLL EVENTS,
 162 -- handler = EVENT HANDLER CALLBACK}
 163 -- @see unregister_pollfd
 164 -- @return boolean status
 165 function register_pollfd(polle)
 166         pollt[#pollt+1] = polle
 167         return true
 168 end
 169
 170 --- Unregister a file desciptor and associate handler from the main loop.
 171 -- @param polle Poll descriptor
 172 -- @see register_pollfd
 173 -- @return boolean status
 174 function unregister_pollfd(polle)
 175         for k, v in ipairs(pollt) do
 176                 if v == polle then
 177                         table.remove(pollt, k)
 178                         return true
 179                 end
 180         end
 181         return false
 182 end
 183
 184 --- Close all registered file descriptors from main loop.
 185 -- This is useful for forked child processes.
 186 function close_pollfds()
 187         for k, v in ipairs(pollt) do
 188                 if v.fd and v.fd.close then
 189                         v.fd:close()
 190                 end
 191         end
 192 end
 193
 194 --- Register a tick function that will be called at each cycle of the main loop.
 195 -- @param cb Callback
 196 -- @see unregister_tick
 197 -- @return boolean status
 198 function register_tick(cb)
 199         tickt[#tickt+1] = cb
 200         return true
 201 end
 202
 203 --- Unregister a tick function from the main loop.
 204 -- @param cb Callback
 205 -- @see register_tick
 206 -- @return boolean status
 207 function unregister_tick(cb)
 208         for k, v in ipairs(tickt) do
 209                 if v == cb then
 210                         table.remove(tickt, k)
 211                         return true
 212                 end
 213         end
 214         return false
 215 end
 216
 217 --- Tests whether a given number of processes can be created.
 218 -- @oaram num Processes to be created
 219 -- @return boolean status
 220 function try_process(num)
 221         local threadlimit = tonumber((cursor:get(UCINAME, "main", "threadlimit")))
 222         return not threadlimit or (threadlimit - tcount) >= (num or 1)
 223 end
 224
 225 --- Create a new child process from a Lua function and assign a destructor.
 226 -- @param threadcb main function of the new process
 227 -- @param waitcb destructor callback
 228 -- @return process identifier or nil, error code, error message
 229 function create_process(threadcb, waitcb)
 230         local threadlimit = tonumber(cursor:get(UCINAME, "main", "threadlimit"))
 231         if threadlimit and tcount >= threadlimit then
 232                 nixio.syslog("warning", "Cannot create thread: process limit reached")
 233                 return nil
 234         end
 235         local pid, code, err = nixio.fork()
 236         if pid and pid ~= 0 then
 237                 nixio.syslog("info", "Created thread: " .. pid)
 238                 tpids[pid] = waitcb or true
 239                 tcount = tcount + 1
 240         elseif pid == 0 then
 241                 local code = threadcb()
 242                 os.exit(code)
 243         else
 244                 nixio.syslog("err", "Unable to fork(): " .. err)
 245         end
 246         return pid, code, err
 247 end
 248
 249 --- Prepare a daemon from a given configuration table.
 250 -- @param config Configuration data.
 251 -- @return boolean status or nil, error code, error message
 252 function prepare_daemon(config)
 253         nixio.syslog("info", "Preparing daemon " .. config[".name"])
 254         local modname = cursor:get(UCINAME, config.slave)
 255         if not modname then
 256                 return nil, -1, "invalid slave"
 257         end
 258
 259         local stat, module = pcall(require, _NAME .. "." .. modname)
 260         if not stat or not module.prepare_daemon then
 261                 return nil, -2, "slave type not supported"
 262         end
 263
 264         config.slave = prepare_slave(config.slave)
 265
 266         return module.prepare_daemon(config, _M)
 267 end
 268
 269 --- Prepare a slave.
 270 -- @param name slave name
 271 -- @return table containing slave module and configuration or nil, error message
 272 function prepare_slave(name)
 273         local slave = slaves[name]
 274         if not slave then
 275                 local config = cursor:get_all(UCINAME, name)
 276
 277                 local stat, module = pcall(require, config and config.entrypoint)
 278                 if stat then
 279                         slave = {module = module, config = config}
 280                 end
 281         end
 282
 283         if slave then
 284                 return slave
 285         else
 286                 return nil, module
 287         end
 288 end
 289
 290 --- Return a list of available network interfaces on the host.
 291 -- @return table returned by nixio.getifaddrs()
 292 function get_interfaces()
 293         return ifaddrs
 294 end
 295
 296 --- Revoke process privileges.
 297 -- @param user new user name or uid
 298 -- @param group new group name or gid
 299 -- @return boolean status or nil, error code, error message
 300 function revoke_privileges(user, group)
 301         if nixio.getuid() == 0 then
 302                 return nixio.setgid(group) and nixio.setuid(user)
 303         end
 304 end
 305
 306 --- Return a secure UCI cursor.
 307 -- @return UCI cursor
 308 function securestate()
 309         local stat = nixio.fs.stat(SSTATE) or {}
 310         local uid = nixio.getuid()
 311         if stat.type ~= "dir" or (stat.modedec % 100) ~= 0 or stat.uid ~= uid then
 312                 nixio.fs.remover(SSTATE)
 313                 if not nixio.fs.mkdir(SSTATE, 700) then
 314                         local errno = nixio.errno()
 315                         nixio.syslog("err", "Integrity check on secure state failed!")
 316                         return nil, errno, nixio.perror(errno)
 317                 end
 318         end
 319
 320         return uci.cursor(nil, SSTATE)
 321 end
 322
 323 --- Daemonize the process.
 324 -- @return boolean status or nil, error code, error message
 325 function daemonize()
 326         if nixio.getppid() == 1 then
 327                 return
 328         end
 329
 330         local pid, code, msg = nixio.fork()
 331         if not pid then
 332                 return nil, code, msg
 333         elseif pid > 0 then
 334                 os.exit(0)
 335         end
 336
 337         nixio.setsid()
 338         nixio.chdir("/")
 339
 340         local devnull = nixio.open("/dev/null", nixio.open_flags("rdwr"))
 341         nixio.dup(devnull, nixio.stdin)
 342         nixio.dup(devnull, nixio.stdout)
 343         nixio.dup(devnull, nixio.stderr)
 344
 345         return true
 346 end