services/api/lib/has_uuid.rb

   1 module HasUuid
   2
   3   UUID_REGEX = /^[0-9a-z]{5}-([0-9a-z]{5})-[0-9a-z]{15}$/
   4
   5   def self.included(base)
   6     base.extend(ClassMethods)
   7     base.validate :validate_uuid
   8     base.before_create :assign_uuid
   9     base.before_destroy :destroy_permission_links
  10     base.has_many(:links_via_head,
  11                   -> { where("not (link_class = 'permission')") },
  12                   class_name: 'Link',
  13                   foreign_key: :head_uuid,
  14                   primary_key: :uuid,
  15                   dependent: :destroy)
  16     base.has_many(:links_via_tail,
  17                   -> { where("not (link_class = 'permission')") },
  18                   class_name: 'Link',
  19                   foreign_key: :tail_uuid,
  20                   primary_key: :uuid,
  21                   dependent: :destroy)
  22   end
  23
  24   module ClassMethods
  25     def uuid_prefix
  26       Digest::MD5.hexdigest(self.to_s).to_i(16).to_s(36)[-5..-1]
  27     end
  28     def generate_uuid
  29       [Server::Application.config.uuid_prefix,
  30        self.uuid_prefix,
  31        rand(2**256).to_s(36)[-15..-1]].
  32         join '-'
  33     end
  34   end
  35
  36   protected
  37
  38   def respond_to_uuid?
  39     self.respond_to? :uuid
  40   end
  41
  42   def validate_uuid
  43     if self.respond_to_uuid? and self.uuid_changed?
  44       if current_user.andand.is_admin and self.uuid.is_a?(String)
  45         if (re = self.uuid.match HasUuid::UUID_REGEX)
  46           if re[1] == self.class.uuid_prefix
  47             return true
  48           else
  49             self.errors.add(:uuid, "type field is '#{re[1]}', expected '#{self.class.uuid_prefix}'")
  50             return false
  51           end
  52         else
  53           self.errors.add(:uuid, "not a valid Arvados uuid '#{self.uuid}'")
  54           return false
  55         end
  56       else
  57         if self.new_record?
  58           self.errors.add(:uuid, "assignment not permitted")
  59         else
  60           self.errors.add(:uuid, "change not permitted")
  61         end
  62         return false
  63       end
  64     else
  65       return true
  66     end
  67   end
  68
  69   def assign_uuid
  70     if self.respond_to_uuid? and self.uuid.nil? or self.uuid.empty?
  71       self.uuid = self.class.generate_uuid
  72     end
  73     true
  74   end
  75
  76   def destroy_permission_links
  77     if uuid
  78       Link.destroy_all(['link_class=? and (head_uuid=? or tail_uuid=?)',
  79                         'permission', uuid, uuid])
  80     end
  81   end
  82 end