Implement backup import logic.

Signal/src/util/OWSBackup.h

@@ -61,6 +61,7 @@ typedef NS_ENUM(NSUInteger, OWSBackupState) {
 //       preserve our PIN and/or private key so that restored users
 //       continues to backup.
 - (void)tryToImportBackup;
+- (void)cancelImportBackup;
 
 @end
 

Signal/src/util/OWSBackup.m

@@ -320,6 +320,18 @@ NS_ASSUME_NONNULL_BEGIN
     self.backupImport =
         [[OWSBackupImport alloc] initWithDelegate:self primaryStorage:[OWSPrimaryStorage sharedManager]];
     [self.backupImport startAsync];
+
+    [self postDidChangeNotification];
+}
+
+- (void)cancelImportBackup
+{
+    [self.backupImport cancel];
+    self.backupImport = nil;
+
+    _backupImportState = OWSBackupState_Idle;
+
+    [self postDidChangeNotification];
 }
 
 #pragma mark -
@@ -392,13 +404,17 @@ NS_ASSUME_NONNULL_BEGIN
 
     DDLogInfo(@"%@ %s: %@, %@", self.logTag, __PRETTY_FUNCTION__, description, progress);
 
+    BOOL didChange = !([NSObject isNullableObject:self.backupExportDescription equalTo:description] &&
+        [NSObject isNullableObject:self.backupExportProgress equalTo:progress]);
+
     self.backupExportDescription = description;
     self.backupExportProgress = progress;
 
-    [self postDidChangeNotification];
+    if (didChange) {
+        [self postDidChangeNotification];
+    }
 }
 
-
 #pragma mark - OWSBackupImportDelegate
 
 - (void)backupImportDidSucceed:(OWSBackupImport *)backupImport
@@ -447,16 +463,23 @@ NS_ASSUME_NONNULL_BEGIN
 
     DDLogInfo(@"%@ %s: %@, %@", self.logTag, __PRETTY_FUNCTION__, description, progress);
 
+    BOOL didChange = !([NSObject isNullableObject:self.backupImportDescription equalTo:description] &&
+        [NSObject isNullableObject:self.backupImportProgress equalTo:progress]);
+
     self.backupImportDescription = description;
     self.backupImportProgress = progress;
 
-    [self postDidChangeNotification];
+    if (didChange) {
+        [self postDidChangeNotification];
+    }
 }
 
 #pragma mark - Notifications
 
 - (void)postDidChangeNotification
 {
+    OWSAssertIsOnMainThread();
+
     [[NSNotificationCenter defaultCenter] postNotificationNameAsync:NSNotificationNameBackupStateDidChange
                                                              object:nil
                                                            userInfo:nil];

SignalMessaging/profiles/OWSUserProfile.m

@@ -106,17 +106,11 @@ NSString *const kLocalProfileUniqueId = @"kLocalProfileUniqueId";
 {
     @synchronized(self)
     {
-        BOOL isEqual;
-        if (avatarUrlPath != nil) {
-            isEqual = [avatarUrlPath isEqual:_avatarUrlPath];
-        } else {
-            // are they both nil?
-            isEqual = _avatarUrlPath == nil;
-        }
+        BOOL didChange = ![NSObject isNullableObject:_avatarUrlPath equalTo:avatarUrlPath];
 
         _avatarUrlPath = avatarUrlPath;
 
-        if (!isEqual) {
+        if (didChange) {
             // If the avatarURL changed, the avatarFileName can't be valid.
             // Clear it.
             self.avatarFileName = nil;

SignalServiceKit/src/Util/NSObject+OWS.h

@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 NS_ASSUME_NONNULL_BEGIN
@@ -12,6 +12,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (NSString *)logTag;
 
++ (BOOL)isNullableObject:(nullable NSObject *)left equalTo:(nullable NSObject *)right;
+
 @end
 
 NS_ASSUME_NONNULL_END

SignalServiceKit/src/Util/NSObject+OWS.m

@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "NSObject+OWS.h"
@@ -21,6 +21,17 @@ NS_ASSUME_NONNULL_BEGIN
     return self.class.logTag;
 }
 
++ (BOOL)isNullableObject:(nullable NSObject *)left equalTo:(nullable NSObject *)right
+{
+    if (!left && !right) {
+        return YES;
+    } else if (!left || !right) {
+        return NO;
+    } else {
+        return [left isEqual:right];
+    }
+}
+
 @end
 
 NS_ASSUME_NONNULL_END

SignalServiceKit/src/Util/OWSError.h

@@ -35,6 +35,10 @@ typedef NS_ENUM(NSInteger, OWSErrorCode) {
     OWSErrorCodeExportBackupFailed = 777415,
     // A possibly recoverable error occured while exporting a backup.
     OWSErrorCodeExportBackupError = 777416,
+    // A non-recoverable error occured while importing a backup.
+    OWSErrorCodeImportBackupFailed = 777417,
+    // A possibly recoverable error occured while importing a backup.
+    OWSErrorCodeImportBackupError = 777418,
 };
 
 extern NSString *const OWSErrorRecipientIdentifierKey;