Realm JS causes app crash in background when physical iOS device with PIN is locked

[gboyegadada]

Goals

No crashes while using realm js on physical iOS devices.

Expected Results

Realm queries should not crash when physical iOS device is locked with PIN.

Actual Results

App crashes when in background and phone is locked.

Thread 4 name:
Thread 4 Crashed:
0   libsystem_platform.dylib      	0x000000019d119e00 _platform_memcmp + 16
1   MyApp                    	0x0000000104e112f0 realm::ArrayStringShort::find_first(realm::StringData, unsigned long, unsigned long) const + 304
2   MyApp                    	0x0000000104e2b6d0 realm::Group::do_get_table(realm::StringData) + 48
3   MyApp                     	0x0000000104e28884 realm::Group::get_table(realm::StringData) + 24
4   MyApp                     	0x0000000104cb8f88 0x1049b0000 + 3182472 (object_store.cpp:219)
5   MyApp                     	0x0000000104ca2404 0x1049b0000 + 3089412 (js_results.hpp:153)
6   MyApp                    	0x0000000104ca1f08 0x1049b0000 + 3088136 (js_realm.hpp:921)
7   MyApp                    	0x0000000104c9d958 0x1049b0000 + 3070296 (jsc_class.hpp:985)
8   JavaScriptCore                	0x00000001ac54e85c long long JSC::APICallbackFunction::call<JSC::JSCallbackFunction>(JSC::JSGlobalObject*, JSC::CallFrame*) + 420 (APICallbackFunction.h:63)

Steps to Reproduce

• Please see similar issue in realm/realm-cocoa repo: find_first(realm::StringData, unsigned long, unsigned long) const + 200 realm-swift#5912 (comment)
• Please see this comment: find_first(realm::StringData, unsigned long, unsigned long) const + 200 realm-swift#5912 (comment)
• I believe this is also addressed in the Swift and Object C sections of the Realm docs but not addressed for JS / RN.

Code Sample

Version of Realm and Tooling

• Realm JS SDK Version: ^6.0.4
• Node or React Native: RN: v0.63.2
• Client OS & Version: iOS 13.6.1
• Which debugger for React Native: None on physical device

[steffenagger]

@gboyegadada thanks for the report, I've added it to our backlog.

It's unfortunately not as trivial as updating the docs when it come to RN - initial thoughts are that a config parameter needs to be added for Realm, and use it to ensure the NSFileProtection level behind the scenes (as described in your linked documentation).

[gboyegadada]

@steffenagger A little update: I wrote a small module to help me subscribe to the
UIApplicationProtectedDataWillBecomeUnavailable and UIApplicationProtectedDataDidBecomeAvailable notifications in iOS (turns out that it's relatively easy to send event notifications from Objective C to react native with some help from the RN docs and a tutorial (I'm completely new to Objective C !)

So right now, I basically suspend my db related tasks when the device is locked and resume when unlocked.