Make mount options a synced_folder capability

lib/vagrant/action/builtin/mixin_synced_folders.rb

@@ -36,7 +36,11 @@ module Vagrant
 
           # Find the proper implementation
           ordered.each do |_, key, impl|
-            return key if impl.new.usable?(machine)
+            begin
+              return key if impl.new.usable?(machine)
+            rescue
+              # Don't do anything. If an error is raised, the impl is not usable
+            end
           end
 
           return nil

lib/vagrant/machine.rb

@@ -11,7 +11,7 @@ module Vagrant
   # API for querying the state and making state changes to the machine, which
   # is backed by any sort of provider (VirtualBox, VMware, etc.).
   class Machine
-    include Vagrant::Action::Builtin::MixinSyncedFolders
+    extend Vagrant::Action::Builtin::MixinSyncedFolders
 
     # The box that is backing this machine.
     #
@@ -619,6 +619,29 @@ module Vagrant
       end
     end
 
+    # This returns the set of shared folders that should be done for
+    # this machine. It returns the folders in a hash keyed by the
+    # implementation class for the synced folders.
+    #
+    # @return [Hash<Symbol, Hash<String, Hash>>]
+    def synced_folders
+      self.class.synced_folders(self)
+    end
+
+    # Returns the SyncedFolder object associated with this machine.
+    #
+    # @return [List<Class>]
+    def synced_folder_types
+      return @synced_folder_types if defined?(@synced_folder_types)
+      plugins = Vagrant.plugin("2").manager.synced_folders
+      @synced_folder_types = synced_folders.map { |type, folders|
+        impl = plugins[type][0].new()
+        impl._initialize(self, type)
+        [type, impl]
+      }.to_h
+      @synced_folder_types
+    end
+
     protected
 
     # Returns the path to the file that stores the UID.

plugins/guests/linux/cap/mount_virtualbox_shared_folder.rb

@@ -16,7 +16,7 @@ module VagrantPlugins
           builtin_mount_type = "-cit #{VB_MOUNT_TYPE}"
           addon_mount_type = "-t #{VB_MOUNT_TYPE}"
 
-          mount_options, mount_uid, mount_gid = mount_options(machine, name, guest_path, options)
+          mount_options, mount_uid, mount_gid = machine.synced_folder_types[:virtualbox].capability(:mount_options, name, guestpath, options)
           mount_command = "mount #{addon_mount_type} -o #{mount_options} #{name} #{guest_path}"
 
           # Create the guest path if it doesn't exist

plugins/guests/linux/cap/persist_mount_shared_folder.rb

@@ -22,7 +22,7 @@ module VagrantPlugins
           end
           export_folders = fstab_folders.map do |name, data|
             guest_path = Shellwords.escape(data[:guestpath])
-            mount_options, mount_uid, mount_gid  =  mount_options(machine, name, guest_path, data)
+            mount_options, mount_uid, mount_gid = machine.synced_folder_types[:virtualbox].capability(:mount_options, name, guest_path, data)
             mount_options = "#{mount_options},nofail"
             {
               name: name,
@@ -45,4 +45,4 @@ module VagrantPlugins
       end
     end
   end
-end
+end

plugins/kernel_v2/config/vm.rb

@@ -727,11 +727,9 @@ module VagrantPlugins
 
         if @allow_fstab_modification == UNSET_VALUE
           plugins = Vagrant.plugin("2").manager.synced_folders
-          machine.synced_folders.each do |type, _|
+          machine.synced_folder_types.each do |_, inst|
-            instance = plugins[type.to_sym][0].new
+            if inst.capability?(:default_fstab_modification)
-            instance._initialize(machine, type)
+              if inst.capability(:default_fstab_modification) == false
-            if instance.capability?(:default_fstab_modification)
-              if instance.capability(:default_fstab_modification) == false
                 @allow_fstab_modification = false
                 break
               end

plugins/providers/virtualbox/cap/mount_options.rb

@@ -0,0 +1,23 @@
+require_relative "../../../synced_folders/unix_mount_helpers"
+
+module VagrantPlugins
+  module ProviderVirtualBox
+    module Cap
+      module MountOptions
+        extend VagrantPlugins::SyncedFolder::UnixMountHelpers
+
+        def self.mount_options(machine, name, guest_path, options)
+          mount_options = options.fetch(:mount_options, [])
+          detected_ids = detect_owner_group_ids(machine, guest_path, mount_options, options)
+          mount_uid = detected_ids[:uid]
+          mount_gid = detected_ids[:gid]
+
+          mount_options << "uid=#{mount_uid}"
+          mount_options << "gid=#{mount_gid}"
+          mount_options = mount_options.join(',')
+          return mount_options, mount_uid, mount_gid
+        end
+      end
+    end
+  end
+end

plugins/providers/virtualbox/plugin.rb

@@ -68,6 +68,11 @@ module VagrantPlugins
         require_relative "cap"
         Cap
       end
+
+      synced_folder_capability(:virtualbox, "mount_options") do
+        require_relative "cap/mount_options"
+        Cap::MountOptions
+      end
     end
 
     autoload :Action, File.expand_path("../action", __FILE__)

plugins/synced_folders/unix_mount_helpers.rb

@@ -99,18 +99,6 @@ module VagrantPlugins
             fi
           EOH
       end
-
-      def mount_options(machine, name, guest_path, options)
-        mount_options = options.fetch(:mount_options, [])
-        detected_ids = detect_owner_group_ids(machine, guest_path, mount_options, options)
-        mount_uid = detected_ids[:uid]
-        mount_gid = detected_ids[:gid]
-
-        mount_options << "uid=#{mount_uid}"
-        mount_options << "gid=#{mount_gid}"
-        mount_options = mount_options.join(',')
-        return mount_options, mount_uid, mount_gid
-      end
     end
   end
 end