Support alternative lxcpath in sudo wrapper

The previously hardcoded lxc path prevented the sudo wrapper from
working in environment with alternative `lxcpath`.

I had to move `sudo_wrapper` from `provider` to `LXC` because the
concept of "provider" is tied to a machine when a command sush as
`sudoers` is not.

Fixes #413 and #399

lib/vagrant-lxc.rb

@@ -1,5 +1,6 @@
 require "vagrant-lxc/version"
 require "vagrant-lxc/plugin"
+require "vagrant-lxc/sudo_wrapper"
 
 module Vagrant
   module LXC
@@ -10,5 +11,12 @@ def self.source_root
     def self.sudo_wrapper_path
       "/usr/local/bin/vagrant-lxc-wrapper"
     end
+
+    def self.sudo_wrapper
+      wrapper = Pathname.new(sudo_wrapper_path).exist? &&
+        sudo_wrapper_path || nil
+      SudoWrapper.new(wrapper)
+    end
+
   end
 end

lib/vagrant-lxc/command/sudoers.rb

@@ -1,5 +1,7 @@
 require 'tempfile'
 
+require "vagrant-lxc/driver"
+
 module Vagrant
   module LXC
     module Command
@@ -43,11 +45,13 @@ def sudoers_path
 
         # This requires vagrant 1.5.2+ https://github.com/mitchellh/vagrant/commit/3371c3716278071680af9b526ba19235c79c64cb
         def create_wrapper!
+          lxc_base_path = Driver.new(0, LXC.sudo_wrapper).containers_path
           wrapper = Tempfile.new('lxc-wrapper').tap do |file|
             template = Vagrant::Util::TemplateRenderer.new(
               'sudoers.rb',
               :template_root  => Vagrant::LXC.source_root.join('templates').to_s,
               :cmd_paths      => build_cmd_paths_hash,
+              :lxc_base_path  => lxc_base_path,
               :pipework_regex => "#{ENV['HOME']}/\.vagrant\.d/gems/(?:\\d+?\\.\\d+?\\.\\d+?/)?gems/vagrant-lxc.+/scripts/pipework"
             )
             file.puts template.render

lib/vagrant-lxc/provider.rb

@@ -2,7 +2,6 @@
 
 require "vagrant-lxc/action"
 require "vagrant-lxc/driver"
-require "vagrant-lxc/sudo_wrapper"
 
 module Vagrant
   module LXC
@@ -26,12 +25,7 @@ def initialize(machine)
       end
 
       def sudo_wrapper
-        @shell ||= begin
-          wrapper = Pathname.new(LXC.sudo_wrapper_path).exist? &&
-            LXC.sudo_wrapper_path || nil
-          @logger.debug("Found sudo wrapper : #{wrapper}") if wrapper
-          SudoWrapper.new(wrapper)
-        end
+        @shell ||= LXC.sudo_wrapper
       end
 
       def ensure_lxc_installed!

templates/sudoers.rb.erb

@@ -78,7 +78,7 @@ class Whitelist
   end
 end
 
-base = "/var/lib/lxc"
+base = "<%= lxc_base_path %>"
 base_path = %r{\A#{base}/.*\z}
 
 ##