Code for testing case sensitivity of filesystem [GH-1202]

lib/vagrant/util/platform.rb

@@ -1,4 +1,5 @@
 require 'rbconfig'
+require 'tmpdir'
 
 require "vagrant/util/subprocess"
 
@@ -39,6 +40,22 @@ module Vagrant
           process.stdout.chomp
         end
 
+        # This checks if the filesystem is case sensitive. This is not a
+        # 100% correct check, since it is possible that the temporary
+        # directory runs a different filesystem than the root directory.
+        # However, this works in many cases.
+        def fs_case_sensitive?
+          tmp_dir = Dir.mktmpdir("vagrant")
+          tmp_file = File.join(tmp_dir, "FILE")
+          File.open(tmp_file, "w") do |f|
+            f.write("foo")
+          end
+
+          # The filesystem is case sensitive if the lowercased version
+          # of the filename is NOT reported as existing.
+          return !File.file?(File.join(tmp_dir, "file"))
+        end
+
         # Returns a boolean noting whether the terminal supports color.
         # output.
         def terminal_supports_colors?