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