From: Tom Clegg <tom@curoverse.com>
Date: Sat, 1 Apr 2017 02:07:19 +0000 (-0400)
Subject: 11100: Adjust delete_at in before_validation hook instead of validation. Permit chang... 
X-Git-Tag: 1.1.0~333^2
X-Git-Url: https://git.arvados.org/arvados.git/commitdiff_plain/ff3bb22d4b2bff5666907a6eeb6cd68cd3cbe22b

11100: Adjust delete_at in before_validation hook instead of validation. Permit changing trash_at without extending delete_at.
---

diff --git a/services/api/app/models/collection.rb b/services/api/app/models/collection.rb
index 92300d6a8e..4a1e610303 100644
--- a/services/api/app/models/collection.rb
+++ b/services/api/app/models/collection.rb
@@ -510,35 +510,49 @@ class Collection < ArvadosModel
     true
   end
 
-  # If trash_at is updated without touching delete_at, automatically
-  # update delete_at to a sensible value.
   def default_trash_interval
     if trash_at_changed? && !delete_at_changed?
+      # If trash_at is updated without touching delete_at,
+      # automatically update delete_at to a sensible value.
       if trash_at.nil?
         self.delete_at = nil
       else
         self.delete_at = trash_at + Rails.configuration.default_trash_lifetime.seconds
       end
+    elsif !trash_at || !delete_at || trash_at > delete_at
+      # Not trash, or bogus arguments? Just validate in
+      # validate_trash_and_delete_timing.
+    elsif delete_at_changed? && delete_at >= trash_at
+      # Fix delete_at if needed, so it's not earlier than the expiry
+      # time on any permission tokens that might have been given out.
+
+      # In any case there are no signatures expiring after now+TTL.
+      # Also, if the existing trash_at time has already passed, we
+      # know we haven't given out any signatures since then.
+      earliest_delete = [
+        @validation_timestamp,
+        trash_at_was,
+      ].compact.min + Rails.configuration.blob_signature_ttl.seconds
+
+      # The previous value of delete_at is also an upper bound on the
+      # longest-lived permission token. For example, if TTL=14,
+      # trash_at_was=now-7, delete_at_was=now+7, then it is safe to
+      # set trash_at=now+6, delete_at=now+8.
+      earliest_delete = [earliest_delete, delete_at_was].compact.min
+
+      # If delete_at is too soon, use the earliest possible time.
+      if delete_at < earliest_delete
+        self.delete_at = earliest_delete
+      end
     end
   end
 
   def validate_trash_and_delete_timing
     if trash_at.nil? != delete_at.nil?
       errors.add :delete_at, "must be set if trash_at is set, and must be nil otherwise"
+    elsif delete_at && delete_at < trash_at
+      errors.add :delete_at, "must not be earlier than trash_at"
     end
-
-    if delete_at
-      if delete_at < trash_at
-        errors.add :delete_at, "must not be earlier than trash_at"
-      else
-        earliest_delete = ([@validation_timestamp, trash_at_was].compact.min +
-                           Rails.configuration.blob_signature_ttl.seconds)
-        if delete_at < earliest_delete
-          self.delete_at = earliest_delete
-        end
-      end
-    end
-
     true
   end
 end