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                       'materialized_permissions',
  28                       'nodes',
  29                       'pipeline_instances',
  30                       'pipeline_templates',
  31                       'repositories',
  32                       'specimens',
  33                       'traits',
  34                     ])
  35       klass = t.classify.constantize
  36       next unless klass and 'owner_uuid'.in?(klass.columns.collect(&:name))
  37       base.has_many(t.to_sym,
  38                     foreign_key: 'owner_uuid',
  39                     primary_key: 'uuid',
  40                     dependent: :restrict_with_exception)
  41     end
  42     # We need custom protection for changing an owner's primary
  43     # key. (Apart from this restriction, admins are allowed to change
  44     # UUIDs.)
  45     base.validate :restrict_uuid_change_breaking_associations
  46   end
  47
  48   module ClassMethods
  49     def install_view(type)
  50       conn = ActiveRecord::Base.connection
  51       transaction do
  52         # Check whether the temporary view has already been created
  53         # during this connection. If not, create it.
  54         conn.exec_query "SAVEPOINT check_#{type}_view"
  55         begin
  56           conn.exec_query("SELECT 1 FROM #{type}_view LIMIT 0")
  57         rescue
  58           conn.exec_query "ROLLBACK TO SAVEPOINT check_#{type}_view"
  59           sql = File.read(Rails.root.join("lib", "create_#{type}_view.sql"))
  60           conn.exec_query(sql)
  61         ensure
  62           conn.exec_query "RELEASE SAVEPOINT check_#{type}_view"
  63         end
  64       end
  65     end
  66   end
  67
  68   def descendant_project_uuids
  69     self.class.install_view('ancestor')
  70     ActiveRecord::Base.connection.
  71       exec_query('SELECT ancestor_view.uuid
  72                   FROM ancestor_view
  73                   LEFT JOIN groups ON groups.uuid=ancestor_view.uuid
  74                   WHERE ancestor_uuid = $1 AND groups.group_class = $2',
  75                   # "name" arg is a query label that appears in logs:
  76                   "descendant_project_uuids for #{self.uuid}",
  77                   # "binds" arg is an array of [col_id, value] for '$1' vars:
  78                   [self.uuid, 'project'],
  79                   ).rows.map do |project_uuid,|
  80       project_uuid
  81     end
  82   end
  83
  84   protected
  85
  86   def restrict_uuid_change_breaking_associations
  87     return true if new_record? or not uuid_changed?
  88
  89     # Check for objects that have my old uuid listed as their owner.
  90     self.class.reflect_on_all_associations(:has_many).each do |assoc|
  91       next unless assoc.foreign_key == 'owner_uuid'
  92       if assoc.klass.where(owner_uuid: uuid_was).any?
  93         errors.add(:uuid,
  94                    "cannot be changed on a #{self.class} that owns objects")
  95         return false
  96       end
  97     end
  98
  99     # if I owned myself before, I'll just continue to own myself with
 100     # my new uuid.
 101     if owner_uuid == uuid_was
 102       self.owner_uuid = uuid
 103     end
 104   end
 105 end