hosts/bsd: check for exports file issues prior to exporting NFS

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 IMPROVEMENTS:
 
+  - hosts/bsd: check NFS exports file for issues prior to exporting
   - provisioners/docker: Add support for using the provisioner with RedHat
     based guests [GH-2649]
   - provisioners/docker: Remove "Docker" prefix from Client and Installer

lib/vagrant/errors.rb

@@ -364,6 +364,10 @@ module Vagrant
       error_key(:not_found, "vagrant.actions.vm.host_only_network")
     end
 
+    class NFSBadExports < VagrantError
+      error_key(:nfs_bad_exports)
+    end
+
     class NFSCantReadExports < VagrantError
       error_key(:nfs_cant_read_exports)
     end

plugins/hosts/bsd/host.rb

@@ -2,6 +2,7 @@ require 'log4r'
 
 require "vagrant"
 require 'vagrant/util/platform'
+require "vagrant/util/subprocess"
 
 module VagrantPlugins
   module HostBSD
@@ -35,6 +36,8 @@ module VagrantPlugins
       end
 
       def nfs_export(id, ips, folders)
+        nfs_checkexports!
+
         # We need to build up mapping of directories that are enclosed
         # within each other because the exports file has to have subdirectories
         # of an exported directory on the same line. e.g.:
@@ -162,6 +165,13 @@ module VagrantPlugins
 
       protected
 
+      def nfs_checkexports!
+        r = Subprocess.execute("nfsd", "checkexports")
+        if r.exit_code != 0
+          raise Vagrant::Errors::NFSBadExports, output: r.stderr
+        end
+      end
+
       def nfs_cleanup(id)
         return if !File.exist?("/etc/exports")
 

templates/locales/en.yml

@@ -429,6 +429,12 @@ en:
         A multi-vm environment is required for name specification to this command.
       multi_vm_target_required: |-
         This command requires a specific VM name to target in a multi-VM environment.
+      nfs_bad_exports: |-
+        NFS is reporting that your exports file is invalid. Vagrant does
+        this check before making any changes to the file. Please correct
+        the issues below and execute "vagrant reload":
+
+        %{output}
       nfs_cant_read_exports: |-
         Vagrant can't read your current NFS exports! The exports file should be
         readable by any user. This is usually caused by invalid permissions