From 20f446936119e0dcba2c31deb8144fc788ddd133 Mon Sep 17 00:00:00 2001
From: "J. Ryan Stinnett" <jryans@gmail.com>
Date: Thu, 28 Mar 2019 12:20:51 +0000
Subject: [PATCH] Add existence check to local storage based crypto store

This supports additional diagnostics of stores in
https://github.com/vector-im/riot-web/issues/9309.
---
 src/crypto/store/localStorage-crypto-store.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/crypto/store/localStorage-crypto-store.js b/src/crypto/store/localStorage-crypto-store.js
index 4c30b6199..af6043af1 100644
--- a/src/crypto/store/localStorage-crypto-store.js
+++ b/src/crypto/store/localStorage-crypto-store.js
@@ -57,6 +57,16 @@ export default class LocalStorageCryptoStore extends MemoryCryptoStore {
         this.store = webStore;
     }
 
+    static exists(webStore) {
+        const length = webStore.length;
+        for (let i = 0; i < length; i++) {
+            if (webStore.key(i).startsWith(E2E_PREFIX)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     // Olm Sessions
 
     countEndToEndSessions(txn, func) {