From 4d26cd3ddde2b7cc3825e709bcd167a048a478ce Mon Sep 17 00:00:00 2001
From: Mark Banner <standard8@mozilla.com>
Date: Tue, 30 Nov 2021 10:11:50 +0000
Subject: [PATCH] Bug 1742839 - Improve handling of missing last modified dates
 in remote settings database. r=robwu,leplatrem

Differential Revision: https://phabricator.services.mozilla.com/D132053
---
 services/settings/Database.jsm                     | 12 +++++++++++-
 .../test/unit/test_remote_settings_offline.js      | 14 ++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/services/settings/Database.jsm b/services/settings/Database.jsm
index 5654e2bf119e..84f41ed851d3 100644
--- a/services/settings/Database.jsm
+++ b/services/settings/Database.jsm
@@ -177,7 +177,17 @@ class Database {
         this.identifier
       );
     }
-    return entry ? entry.value : null;
+    if (!entry) {
+      return null;
+    }
+    // Some distributions where released with a modified dump that did not
+    // contain timestamps for last_modified. Work around this here, and return
+    // the timestamp as zero, so that the entries should get updated.
+    if (isNaN(entry.value)) {
+      console.warn(`Local timestamp is NaN for ${this.identifier}`);
+      return 0;
+    }
+    return entry.value;
   }
 
   async getMetadata() {
diff --git a/services/settings/test/unit/test_remote_settings_offline.js b/services/settings/test/unit/test_remote_settings_offline.js
index 94521b644723..cdf6dcdd9350 100644
--- a/services/settings/test/unit/test_remote_settings_offline.js
+++ b/services/settings/test/unit/test_remote_settings_offline.js
@@ -117,6 +117,20 @@ add_task(async function test_load_dump_after_non_empty_import() {
 });
 add_task(clear_state);
 
+add_task(async function test_load_dump_after_import_from_broken_distro() {
+  // Dump is updated regularly, verify that the dump matches our expectations
+  // before running the test.
+  ok(DUMP_LAST_MODIFIED > 1234, "Assuming dump to be newer than dummy 1234");
+
+  // No last_modified time.
+  await importData([{ id: "dummy" }]);
+
+  const after = await client.get({ loadDumpIfNewer: true });
+  equal(after.length, DUMP_RECORDS.length, "Imported dump");
+  equal(await client.getLastModified(), DUMP_LAST_MODIFIED, "dump's timestamp");
+});
+add_task(clear_state);
+
 add_task(async function test_skip_dump_if_same_last_modified() {
   await importData([{ last_modified: DUMP_LAST_MODIFIED, id: "dummy" }]);