From d25579e4789b890d67fe8697f4d03879b51a1a75 Mon Sep 17 00:00:00 2001
From: Matt Rubin <opensource@mattrubin.me>
Date: Sun, 9 Sep 2018 19:50:36 -0400
Subject: [PATCH] Treat failure to delete a non-existent password as success

Fixes https://github.com/signalapp/Signal-iOS/issues/3876
---
 SignalServiceKit/src/Storage/KeychainStorage.swift | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/SignalServiceKit/src/Storage/KeychainStorage.swift b/SignalServiceKit/src/Storage/KeychainStorage.swift
index 12e76e4da..b19139b4c 100644
--- a/SignalServiceKit/src/Storage/KeychainStorage.swift
+++ b/SignalServiceKit/src/Storage/KeychainStorage.swift
@@ -94,6 +94,10 @@ public class SSKDefaultKeychainStorage: NSObject, SSKKeychainStorage {
         var error: NSError?
         let result = SAMKeychain.deletePassword(forService: service, account: key, error: &error)
         if let error = error {
+            // If deletion failed because the specified item could not be found in the keychain, consider it success.
+            if error.code == errSecItemNotFound {
+                return
+            }
             throw KeychainStorageError.failure(description: "\(logTag) error removing data: \(error)")
         }
         guard result else {