guests/linux: Properly escape and retry vbox shared folder mounting

lib/vagrant/errors.rb

@@ -780,6 +780,10 @@ module Vagrant
       error_key(:virtualbox_no_name)
     end
 
+    class VirtualBoxMountFailed < VagrantError
+      error_key(:virtualbox_mount_failed)
+    end
+
     class VirtualBoxNameExists < VagrantError
       error_key(:virtualbox_name_exists)
     end

plugins/guests/linux/cap/mount_virtualbox_shared_folder.rb

@@ -1,12 +1,17 @@
+require "shellwords"
+
+require "vagrant/util/retryable"
+
 module VagrantPlugins
   module GuestLinux
     module Cap
       class MountVirtualBoxSharedFolder
-        def self.mount_virtualbox_shared_folder(machine, name, guestpath, options)
-          expanded_guest_path = machine.guest.capability(
-            :shell_expand_guest_path, guestpath)
+        extend Vagrant::Util::Retryable
 
-          mount_commands = []
+        def self.mount_virtualbox_shared_folder(machine, name, guestpath, options)
+          guest_path = Shellwords.escape(guestpath)
+
+          mount_commands = ["set -e"]
 
           if options[:owner].is_a? Integer
             mount_uid = options[:owner]
@@ -25,73 +30,54 @@ module VagrantPlugins
           # First mount command uses getent to get the group
           mount_options = "-o uid=#{mount_uid},gid=#{mount_gid}"
           mount_options += ",#{options[:mount_options].join(",")}" if options[:mount_options]
-          mount_commands << "mount -t vboxsf #{mount_options} #{name} #{expanded_guest_path}"
+          mount_commands << "mount -t vboxsf #{mount_options} #{name} #{guest_path}"
 
           # Second mount command uses the old style `id -g`
           mount_options = "-o uid=#{mount_uid},gid=#{mount_gid_old}"
           mount_options += ",#{options[:mount_options].join(",")}" if options[:mount_options]
-          mount_commands << "mount -t vboxsf #{mount_options} #{name} #{expanded_guest_path}"
+          mount_commands << "mount -t vboxsf #{mount_options} #{name} #{guest_path}"
 
           # Create the guest path if it doesn't exist
-          machine.communicate.sudo("mkdir -p #{expanded_guest_path}")
+          machine.communicate.sudo("mkdir -p #{guest_path}")
 
           # Attempt to mount the folder. We retry here a few times because
           # it can fail early on.
-          attempts = 0
-          while true
-            success = true
-
-            stderr = ""
-            mount_commands.each do |command|
-              no_such_device = false
-              stderr = ""
-              status = machine.communicate.sudo(command, error_check: false) do |type, data|
-                if type == :stderr
-                  no_such_device = true if data =~ /No such device/i
-                  stderr += data.to_s
-                end
-              end
-
-              success = status == 0 && !no_such_device
-              break if success
-            end
-
-            break if success
-
-            attempts += 1
-            if attempts > 10
-              raise Vagrant::Errors::LinuxMountFailed,
-                command: mount_commands.join("\n"),
-                output: stderr
-            end
-
-            sleep(2*attempts)
+          command = mount_commands.join("\n")
+          stderr = ""
+          retryable(on: Vagrant::Errors::VirtualBoxMountFailed, tries: 3, sleep: 5) do
+            machine.communicate.sudo(command,
+              error_class: Vagrant::Errors::VirtualBoxMountFailed,
+              error_key: :virtualbox_mount_failed,
+              command: command,
+              output: stderr,
+            ) { |type, data| stderr = data if type == :stderr }
           end
 
           # Chown the directory to the proper user. We skip this if the
           # mount options contained a readonly flag, because it won't work.
           if !options[:mount_options] || !options[:mount_options].include?("ro")
             chown_commands = []
-            chown_commands << "chown #{mount_uid}:#{mount_gid} #{expanded_guest_path}"
-            chown_commands << "chown #{mount_uid}:#{mount_gid_old} #{expanded_guest_path}"
+            chown_commands << "chown #{mount_uid}:#{mount_gid} #{guest_path}"
+            chown_commands << "chown #{mount_uid}:#{mount_gid_old} #{guest_path}"
 
             exit_status = machine.communicate.sudo(chown_commands[0], error_check: false)
             machine.communicate.sudo(chown_commands[1]) if exit_status != 0
           end
 
           # Emit an upstart event if we can
-          machine.communicate.sudo <<-SCRIPT
-if command -v /sbin/init && /sbin/init --version | grep upstart; then
-  /sbin/initctl emit --no-wait vagrant-mounted MOUNTPOINT='#{expanded_guest_path}'
-fi
-SCRIPT
+          machine.communicate.sudo <<-EOH.gsub(/^ {12}/, "")
+            if command -v /sbin/init && /sbin/init --version | grep upstart; then
+              /sbin/initctl emit --no-wait vagrant-mounted MOUNTPOINT=#{guest_path}
+            fi
+          EOH
         end
 
         def self.unmount_virtualbox_shared_folder(machine, guestpath, options)
-          result = machine.communicate.sudo(
-            "umount #{guestpath}", error_check: false)
+          guest_path = Shellwords.escape(guestpath)
+
+          result = machine.communicate.sudo("umount #{guest_path}", error_check: false)
           if result == 0
-            machine.communicate.sudo("rmdir #{guestpath}", error_check: false)
+            machine.communicate.sudo("rmdir #{guest_path}", error_check: false)
           end
         end
       end

templates/locales/en.yml

@@ -1342,6 +1342,19 @@ en:
         VirtualBox is complaining that the installation is incomplete. Please
         run `VBoxManage --version` to see the error message which should contain
         instructions on how to fix this error.
+      virtualbox_mount_failed: |-
+        Vagrant was unable to mount VirtualBox shared folders. This is usually
+        because the filesystem "vboxsf" is not available. This filesystem is
+        made available via the VirtualBox Guest Additions and kernel module.
+        Please verify that these guest additions are properly installed in the
+        guest. This is not a bug in Vagrant and is usually caused by a faulty
+        Vagrant box. For context, the command attemped was:
+
+        %{command}
+
+        The error output from the command was:
+
+        %{output}
       virtualbox_name_exists: |-
         The name of your virtual machine couldn't be set because VirtualBox
         is reporting another VM with that name already exists. Most of the