1 files changed, 64 insertions, 0 deletions
diff --git a/lib/chef/chef_fs/path_utils.rb b/lib/chef/chef_fs/path_utils.rb
new file mode 100644
index 0000000000..67c62a7545
--- /dev/null
+++ b/lib/chef/chef_fs/path_utils.rb
@@ -0,0 +1,64 @@
+#
+# Author:: John Keiser (<jkeiser@opscode.com>)
+# Copyright:: Copyright (c) 2012 Opscode, Inc.
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+require 'chef/chef_fs'
+
+class Chef
+  module ChefFS
+    class PathUtils
+
+      # If you are in 'source', this is what you would have to type to reach 'dest'
+      # relative_to('/a/b/c/d/e', '/a/b/x/y') == '../../c/d/e'
+      # relative_to('/a/b', '/a/b') == ''
+      def self.relative_to(dest, source)
+        # Skip past the common parts
+        source_parts = Chef::ChefFS::PathUtils.split(source)
+        dest_parts = Chef::ChefFS::PathUtils.split(dest)
+        i = 0
+        until i >= source_parts.length || i >= dest_parts.length || source_parts[i] != source_parts[i]
+          i+=1
+        end
+        # dot-dot up from 'source' to the common ancestor, then
+        # descend to 'dest' from the common ancestor
+        result = Chef::ChefFS::PathUtils.join(*(['..']*(source_parts.length-i) + dest_parts[i,dest.length-i]))
+        result == '' ? '.' : result
+      end
+
+      def self.join(*parts)
+        return "" if parts.length == 0
+        # Determine if it started with a slash
+        absolute = parts[0].length == 0 || parts[0].length > 0 && parts[0] =~ /^#{regexp_path_separator}/
+        # Remove leading and trailing slashes from each part so that the join will work (and the slash at the end will go away)
+        parts = parts.map { |part| part.gsub(/^\/|\/$/, "") }
+        # Don't join empty bits
+        result = parts.select { |part| part != "" }.join("/")
+        # Put the / back on
+        absolute ? "/#{result}" : result
+      end
+
+      def self.split(path)
+        path.split(Regexp.new(regexp_path_separator))
+      end
+
+      def self.regexp_path_separator
+        Chef::ChefFS::windows? ? '[/\\]' : '/'
+      end
+
+    end
+  end
+end