services/api/lib/can_be_an_owner.rb

   1 # Copyright (C) The Arvados Authors. All rights reserved.
   2 #
   3 # SPDX-License-Identifier: AGPL-3.0
   4
   5 # Protect referential integrity of owner_uuid columns in other tables
   6 # that can refer to the uuid column in this table.
   7
   8 module CanBeAnOwner
   9
  10   def self.included(base)
  11     base.extend(ClassMethods)
  12
  13     # Rails' "has_many" can prevent us from destroying the owner
  14     # record when other objects refer to it.
  15     ActiveRecord::Base.connection.tables.each do |t|
  16       next if t == base.table_name
  17       next if t.in?([
  18                       'schema_migrations',
  19                       'permission_refresh_lock',
  20                       'ar_internal_metadata',
  21                       'commit_ancestors',
  22                       'commits',
  23                       'humans',
  24                       'jobs',
  25                       'job_tasks',
  26                       'keep_disks',
  27                       'nodes',
  28                       'pipeline_instances',
  29                       'pipeline_templates',
  30                       'repositories',
  31                       'specimens',
  32                       'traits',
  33                     ])
  34       klass = t.classify.constantize
  35       next unless klass and 'owner_uuid'.in?(klass.columns.collect(&:name))
  36       base.has_many(t.to_sym,
  37                     foreign_key: 'owner_uuid',
  38                     primary_key: 'uuid',
  39                     dependent: :restrict_with_exception)
  40     end
  41     # We need custom protection for changing an owner's primary
  42     # key. (Apart from this restriction, admins are allowed to change
  43     # UUIDs.)
  44     base.validate :restrict_uuid_change_breaking_associations
  45   end
  46
  47   module ClassMethods
  48     def install_view(type)
  49       conn = ActiveRecord::Base.connection
  50       transaction do
  51         # Check whether the temporary view has already been created
  52         # during this connection. If not, create it.
  53         conn.exec_query "SAVEPOINT check_#{type}_view"
  54         begin
  55           conn.exec_query("SELECT 1 FROM #{type}_view LIMIT 0")
  56         rescue
  57           conn.exec_query "ROLLBACK TO SAVEPOINT check_#{type}_view"
  58           sql = File.read(Rails.root.join("lib", "create_#{type}_view.sql"))
  59           conn.exec_query(sql)
  60         ensure
  61           conn.exec_query "RELEASE SAVEPOINT check_#{type}_view"
  62         end
  63       end
  64     end
  65   end
  66
  67   def descendant_project_uuids
  68     self.class.install_view('ancestor')
  69     ActiveRecord::Base.connection.
  70       exec_query('SELECT ancestor_view.uuid
  71                   FROM ancestor_view
  72                   LEFT JOIN groups ON groups.uuid=ancestor_view.uuid
  73                   WHERE ancestor_uuid = $1 AND groups.group_class = $2',
  74                   # "name" arg is a query label that appears in logs:
  75                   "descendant_project_uuids for #{self.uuid}",
  76                   # "binds" arg is an array of [col_id, value] for '$1' vars:
  77                   [self.uuid, 'project'],
  78                   ).rows.map do |project_uuid,|
  79       project_uuid
  80     end
  81   end
  82
  83   protected
  84
  85   def restrict_uuid_change_breaking_associations
  86     return true if new_record? or not uuid_changed?
  87
  88     # Check for objects that have my old uuid listed as their owner.
  89     self.class.reflect_on_all_associations(:has_many).each do |assoc|
  90       next unless assoc.foreign_key == 'owner_uuid'
  91       if assoc.klass.where(owner_uuid: uuid_was).any?
  92         errors.add(:uuid,
  93                    "cannot be changed on a #{self.class} that owns objects")
  94         return false
  95       end
  96     end
  97
  98     # if I owned myself before, I'll just continue to own myself with
  99     # my new uuid.
 100     if owner_uuid == uuid_was
 101       self.owner_uuid = uuid
 102     end
 103   end
 104 end