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