From 40dc0de6652e36316fca93e838d3f44aa849d7da Mon Sep 17 00:00:00 2001
From: Chris Roberts <code@chrisroberts.org>
Date: Sat, 29 Oct 2016 15:46:12 -0700
Subject: [PATCH] Use Util::StringBlockEditor to modify /etc/exports

---
 plugins/hosts/linux/cap/nfs.rb | 94 +++++++++++++++++++---------------
 1 file changed, 53 insertions(+), 41 deletions(-)

diff --git a/plugins/hosts/linux/cap/nfs.rb b/plugins/hosts/linux/cap/nfs.rb
index 74f723f15..862ee34b3 100644
--- a/plugins/hosts/linux/cap/nfs.rb
+++ b/plugins/hosts/linux/cap/nfs.rb
@@ -37,15 +37,7 @@ module VagrantPlugins
           sleep 0.5
 
           nfs_cleanup(id)
-
-          # Only use "sudo" if we can't write to /etc/exports directly
-          sudo_command = ""
-          sudo_command = "sudo " if !File.writable?("/etc/exports")
-
-          output.split("\n").each do |line|
-            line = Vagrant::Util::ShellQuote.escape(line, "'")
-            system(%Q[echo '#{line}' | #{sudo_command}tee -a /etc/exports >/dev/null])
-          end
+          nfs_write_exports(output)
 
           if nfs_running?(nfs_check_command)
             system("sudo #{nfs_apply_command}")
@@ -67,50 +59,70 @@ module VagrantPlugins
           logger = Log4r::Logger.new("vagrant::hosts::linux")
           logger.info("Pruning invalid NFS entries...")
 
-          output = false
           user = Process.uid
 
-          File.read("/etc/exports").lines.each do |line|
-            if id = line[/^# VAGRANT-BEGIN:( #{user})? ([\.\/A-Za-z0-9\-_:]+?)$/, 2]
-              if valid_ids.include?(id)
-                logger.debug("Valid ID: #{id}")
-              else
-                if !output
-                  # We want to warn the user but we only want to output once
-                  ui.info I18n.t("vagrant.hosts.linux.nfs_prune")
-                  output = true
-                end
+          # Create editor instance for removing invalid IDs
+          editor = Util::StringBlockEditor.new(File.read("/etc/exports"))
 
-                logger.info("Invalid ID, pruning: #{id}")
-                nfs_cleanup(id)
-              end
-            end
+          # Build composite IDs with UID information and discover invalid entries
+          composite_ids = valid_ids.map do |v_id|
+            "#{user} #{v_id}"
+          end
+          remove_ids = editor.keys - composite_keys
+
+          logger.debug("Known valid NFS export IDs: #{valid_ids}")
+          logger.debug("Composite valid NFS export IDs with user: #{composite_ids}")
+          logger.debug("NFS export IDs to be removed: #{remove_ids}")
+          if !remove_ids.empty?
+            ui.info I18n.t("vagrant.hosts.linux.nfs_prune")
+            nfs_cleanup(remove_ids)
           end
         end
 
         protected
 
-        def self.nfs_cleanup(id)
+        def self.nfs_cleanup(remove_ids)
           return if !File.exist?("/etc/exports")
 
-          # Only use "sudo" if we can't write to /etc/exports directly
-          sudo_command = ""
-          sudo_command = "sudo " if !File.writable?("/etc/exports")
+          editor = Util::StringBlockEditor.new(File.read("/etc/exports"))
+          remove_ids = Array(remove_ids)
 
-          # Strip out the block of code which was inserted by Vagrant
-          user = Regexp.escape(Process.uid.to_s)
-          id = Regexp.escape(id.to_s)
-          exports_in = File.read('/etc/exports')
-          exports_out = exports_in.gsub(%r{
-            ^\#\ VAGRANT-BEGIN:((?:\ #{user})?\ #{id})$
-            .*?
-            ^\#\ VAGRANT-END:\1$
-            \n?
-          }mx, '')
-          if exports_out != exports_in
-            open(%Q[|#{sudo_command}tee /etc/exports >/dev/null], 'w+') do |p|
-              p.write(exports_out)
+          # Remove all invalid ID entries
+          remove_ids.each do |r_id|
+            editor.delete(r_id)
+          end
+          nfs_write_exports(editor.value)
+        end
+
+        def self.nfs_write_exports(new_exports_content)
+          # Write contents out to temporary file
+          new_exports_file = Tempfile.create('vagrant')
+          new_exports_file.puts(new_exports_content)
+          new_exports_file.close
+          new_exports_path = new_exports_file.path
+
+          if !FileUtils.compare_file(new_exports_path, "/etc/exports")
+            # Only use "sudo" if we can't write to /etc/exports directly
+            sudo_command = ""
+            sudo_command = "sudo " if !File.writable?("/etc/exports")
+
+            # Ensure new file mode and uid/gid match existing file to replace
+            existing_stat = File.stat("/etc/exports")
+            new_stat = File.stat(new_exports_path)
+            if existing_stat.mode != new_stat.mode
+              File.chmod(existing_stat.mode, new_exports_path)
             end
+            # TODO: Error check
+            if existing_stat.uid != new_stat.uid || existing_stat.gid != new_stat.gid
+              system("#{sudo_command}chown #{existing_stat.uid}:#{existing_stat.gid} #{new_exports_path}")
+            end
+
+            # Replace existing exports file
+            system("#{sudo_command}mv #{new_exports_path} /etc/exports")
+          end
+        ensure
+          if File.exist?(new_exports_path)
+            File.unlink(new_exports_path)
           end
         end