gluon-core: add functions to manage a list of mesh interfaces

package/gluon-core/files/usr/lib/lua/gluon/mesh.lua

@@ -0,0 +1,76 @@
+local util = require 'gluon.util'
+
+local json = require 'luci.jsonc'
+local ltn12 = require 'luci.ltn12'
+local lutil = require 'luci.util'
+
+local assert = assert
+local io = io
+local ipairs = ipairs
+
+
+local mesh_interfaces = '/lib/gluon/core/mesh_interfaces.json'
+local interface_lock = '/var/lock/gluon_core_mesh_interfaces'
+
+
+local function _interfaces()
+  local file = io.open(mesh_interfaces)
+  if not file then
+    return {}
+  end
+
+  local decoder = json.new()
+  ltn12.pump.all(ltn12.source.file(file), decoder:sink())
+
+  file:close()
+
+  return assert(decoder:get())
+end
+
+local function _update(ifs)
+  for _, v in pairs(ifs) do
+    v[{}] = true
+  end
+  ifs[{}] = true
+
+  file = assert(io.open(mesh_interfaces, 'w'))
+  file:write(json.stringify(ifs))
+  file:close()
+end
+
+local function _register_interface(name, info)
+  local ifs = _interfaces()
+  if not ifs[name] then
+    ifs[name] = info or {}
+    _update(ifs)
+  end
+end
+
+local function _unregister_interface(name)
+  local ifs = _interfaces()
+  if ifs[name] then
+    ifs[name] = nil
+    _update(ifs)
+  end
+end
+
+
+module 'gluon.mesh'
+
+function interfaces()
+  return util.locked(interface_lock, _interfaces)
+end
+
+-- info may hold additional information about a mesh interface, the following values are defined:
+--
+-- transitive (boolean): defines if the interface provides transitive connectivity (default: false)
+-- fixed_mtu (boolean): defines if the interface's MTU may not be changed (default: false)
+--
+-- Note: if the interface is already registered, the info is not updated
+function register_interface(name, info)
+  util.locked(interface_lock, _register_interface, name, info)
+end
+
+function unregister_interface(name)
+  util.locked(interface_lock, _unregister_interface, name)
+end

package/gluon-core/luasrc/usr/lib/lua/gluon/util.lua

@@ -23,12 +23,15 @@ local function escape_args(ret, arg0, ...)
 end
 
 
+local error = error
 local io = io
+local ipairs = ipairs
 local os = os
+local pcall = pcall
 local string = string
 local tonumber = tonumber
-local ipairs = ipairs
 local table = table
+local unpack = unpack
 
 local nixio = require 'nixio'
 local hash = require 'hash'
@@ -70,6 +73,19 @@ function unlock(file)
   exec('lock', '-u', file)
 end
 
+function locked(file, f, ...)
+	lock(file)
+	local ret = {pcall(f, ...)}
+	unlock(file)
+
+	if ret[1] then
+		table.remove(ret, 1)
+		return unpack(ret)
+	else
+		error(ret[2])
+	end
+end
+
 function node_id()
   return string.gsub(sysconfig.primary_mac, ':', '')
 end