From 59876a4873b57888f7c8e80775fc8057e1b308a6 Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Tue, 28 Nov 2017 12:08:09 +0100
Subject: [PATCH] Fix shutdown in case of errors during initialization

PR #10286 introduced a few steps which are not robust to early shutdown
in initialization.

Stumbled upon this with #11781, not sure if there are other scenarios
that can trigger it, but it's harden against this in any case.
---
 src/init.cpp                | 5 ++++-
 src/validationinterface.cpp | 7 ++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/init.cpp b/src/init.cpp
index 3e59bd952fd4bd..904e8e1437e7e5 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -232,7 +232,10 @@ void PrepareShutdown()
 #endif
     StopMapPort();
 
-    UnregisterValidationInterface(peerLogic.get());
+    // Because these depend on each-other, we make sure that neither can be
+    // using the other before destroying them.
+    if (peerLogic) UnregisterValidationInterface(peerLogic.get());
+    if (g_connman) g_connman->Stop();
     peerLogic.reset();
     g_connman.reset();
 
diff --git a/src/validationinterface.cpp b/src/validationinterface.cpp
index 30fcb04265ec26..bf59ed00806131 100644
--- a/src/validationinterface.cpp
+++ b/src/validationinterface.cpp
@@ -57,7 +57,9 @@ void CMainSignals::UnregisterBackgroundSignalScheduler() {
 }
 
 void CMainSignals::FlushBackgroundCallbacks() {
-    m_internals->m_schedulerClient.EmptyQueue();
+    if (m_internals) {
+        m_internals->m_schedulerClient.EmptyQueue();
+    }
 }
 
 CMainSignals& GetMainSignals()
@@ -93,6 +95,9 @@ void UnregisterValidationInterface(CValidationInterface* pwalletIn)
 
 void UnregisterAllValidationInterfaces()
 {
+    if (!g_signals.m_internals) {
+        return;
+    }
     g_signals.m_internals->BlockFound.disconnect_all_slots();
     g_signals.m_internals->BlockChecked.disconnect_all_slots();
     g_signals.m_internals->Broadcast.disconnect_all_slots();