1 files changed, 81 insertions, 0 deletions
diff --git a/lib/chef/blacklist.rb b/lib/chef/blacklist.rb
new file mode 100644
index 0000000000..a60e0318cd
--- /dev/null
+++ b/lib/chef/blacklist.rb
@@ -0,0 +1,81 @@
+
+require "chef/exceptions"
+
+class Chef
+  class Blacklist
+
+    # filter takes two arguments - the data you want to filter, and a blacklisted array
+    # of keys you want discluded. You can capture a subtree of the data to filter by
+    # providing a "/"-delimited string of keys. If some key includes "/"-characters,
+    # you must provide an array of keys instead.
+    #
+    # Blacklist.filter(
+    #   { "filesystem" => {
+    #       "/dev/disk" => {
+    #         "size" => "10mb"
+    #       },
+    #       "map - autohome" => {
+    #         "size" => "10mb"
+    #       }
+    #     },
+    #     "network" => {
+    #       "interfaces" => {
+    #         "eth0" => {...},
+    #         "eth1" => {...}
+    #       }
+    #     }
+    #   },
+    #   ["network/interfaces/eth0", ["filesystem", "/dev/disk"]])
+    # will exclude the eth0 and /dev/disk subtrees.
+    def self.filter(data, blacklist = nil)
+      return data if blacklist.nil?
+
+      blacklist.each do |item|
+	Chef::Log.warn("Removing item #{item}")
+        remove_data(data, item)
+      end
+      data
+    end
+
+    # Walk the data according to the keys provided by the blacklisted item
+    # and add the data to the whitelisting result.
+    def self.remove_data(data, item)
+      parts = to_array(item)
+
+      item_ref = data
+      parts[0..-2].each do |part|
+        unless item_ref[part]
+          Chef::Log.warn("Could not find blacklist attribute #{item}.")
+          return nil
+        end
+
+        item_ref = item_ref[part]
+      end
+
+      unless item_ref.key?(parts[-1])
+        Chef::Log.warn("Could not find blacklist attribute #{item}.")
+        return nil
+      end
+
+      item_ref[parts[-1]] = nil
+      data
+    end
+
+    private_class_method :remove_data
+
+    # Accepts a String or an Array, and returns an Array of String keys that
+    # are used to traverse the data hash. Strings are split on "/", Arrays are
+    # assumed to contain exact keys (that is, Array elements will not be split
+    # by "/").
+    def self.to_array(item)
+      return item if item.kind_of? Array
+
+      parts = item.split("/")
+      parts.shift if !parts.empty? && parts[0].empty?
+      parts
+    end
+
+    private_class_method :to_array
+
+  end
+end