guests/linux: try `id -g` to determine group as well [GH-2197]

CHANGELOG.md

@@ -17,6 +17,8 @@ BUG FIXES:
   - core: Increase timeout for individual SSH connection to 60 seconds. [GH-2163]
   - core: Call realpath after creating directory so NFS directory creation
     works. [GH-2196]
+  - guests/linux: Try `id -g` in addition to `getent` for mounting
+    VirtualBox shared folders [GH-2197]
   - hosts/arch: NFS exporting works properly, no exceptions. [GH-2161]
   - hosts/bsd: Use only `sudo` for writing NFS exports. This lets NFS
     exports work if you have sudo privs but not `su`. [GH-2191]

plugins/guests/linux/cap/mount_virtualbox_shared_folder.rb

@@ -6,13 +6,17 @@ module VagrantPlugins
           expanded_guest_path = machine.guest.capability(
             :shell_expand_guest_path, guestpath)
 
-          # Determine the permission string to attach to the mount command
-          mount_options = "-o uid=`id -u #{options[:owner]}`,gid=`getent group #{options[:group]} | cut -d: -f3`"
-          if options[:mount_options]
-            mount_options += ",#{options[:mount_options].join(",")}"
-          end
+          mount_commands = []
 
-          mount_command = "mount -t vboxsf #{mount_options} #{name} #{expanded_guest_path}"
+          # First mount command uses getent to get the group
+          mount_options = "-o uid=`id -u #{options[:owner]}`,gid=`getent group #{options[:group]} | cut -d: -f3`"
+          mount_options += ",#{options[:mount_options].join(",")}" if options[:mount_options]
+          mount_commands << "mount -t vboxsf #{mount_options} #{name} #{expanded_guest_path}"
+
+          # Second mount command uses the old style `id -g`
+          mount_options = "-o uid=`id -u #{options[:owner]}`,gid=`id -g #{options[:group]}`"
+          mount_options += ",#{options[:mount_options].join(",")}" if options[:mount_options]
+          mount_commands << "mount -t vboxsf #{mount_options} #{name} #{expanded_guest_path}"
 
           # Create the guest path if it doesn't exist
           machine.communicate.sudo("mkdir -p #{expanded_guest_path}")
@@ -22,8 +26,13 @@ module VagrantPlugins
           attempts = 0
           while true
             success = true
-            machine.communicate.sudo(mount_command) do |type, data|
-              success = false if type == :stderr && data =~ /No such device/i
+
+            mount_commands.each do |command|
+              machine.communicate.sudo(command) do |type, data|
+                success = false if type == :stderr && data =~ /No such device/i
+              end
+
+              break if success
             end
 
             break if success
@@ -34,8 +43,15 @@ module VagrantPlugins
           end
 
           # Chown the directory to the proper user
-          machine.communicate.sudo(
-            "chown `id -u #{options[:owner]}`:`getent group #{options[:group]} | cut -d: -f3` #{expanded_guest_path}")
+          chown_commands = []
+          chown_commands << "chown `id -u #{options[:owner]}`:`getent group #{options[:group]} " +
+            "| cut -d: -f3` #{expanded_guest_path}"
+          chown_commands << "chown `id -u #{options[:owner]}`:`id -g #{options[:group]} " +
+            "#{expanded_guest_path}"
+
+          exit_status = machine.communicate.sudo(chown_commands[0], error_check: false)
+          return if exit_status == 0
+          machine.communicate.sudo(chown_commands[1])
         end
       end
     end