Improve the robustness of the migration logic.

SignalMessaging/profiles/OWSProfileManager.m

@@ -1118,8 +1118,7 @@ const NSUInteger kOWSProfileManager_MaxAvatarDiameter = 640;
     DDLogInfo(@"%@ %s", self.logTag, __PRETTY_FUNCTION__);
 
     return [OWSFileSystem moveAppFilePath:self.legacyProfileAvatarsDirPath
-                       sharedDataFilePath:self.sharedDataProfileAvatarsDirPath
+                       sharedDataFilePath:self.sharedDataProfileAvatarsDirPath];
-                            exceptionName:@"ProfileManagerCouldNotMigrateProfileDirectory"];
 }
 
 - (NSString *)profileAvatarsDirPath

SignalServiceKit/src/Messages/Attachments/TSAttachmentStream.m

@@ -199,8 +199,7 @@ NS_ASSUME_NONNULL_BEGIN
     DDLogInfo(@"%@ %s", self.logTag, __PRETTY_FUNCTION__);
 
     return [OWSFileSystem moveAppFilePath:self.legacyAttachmentsDirPath
-                       sharedDataFilePath:self.sharedDataAttachmentsDirPath
+                       sharedDataFilePath:self.sharedDataAttachmentsDirPath];
-                            exceptionName:@"CouldNotMigrateAttachmentsDirectory"];
 }
 
 + (NSString *)attachmentsFolder

SignalServiceKit/src/Storage/TSStorageManager.m

@@ -18,8 +18,6 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-NSString *const TSStorageManagerExceptionName_CouldNotMoveDatabaseFile
-    = @"TSStorageManagerExceptionName_CouldNotMoveDatabaseFile";
 NSString *const TSStorageManagerExceptionName_CouldNotCreateDatabaseDirectory
     = @"TSStorageManagerExceptionName_CouldNotCreateDatabaseDirectory";
 
@@ -255,21 +253,35 @@ void runAsyncRegistrationsForStorage(OWSStorage *storage)
     [OWSFileSystem protectFileOrFolderAtPath:self.legacyDatabaseFilePath_WAL];
 
     NSError *_Nullable error = nil;
-    error = [OWSFileSystem moveAppFilePath:self.legacyDatabaseFilePath
+    if ([fileManager fileExistsAtPath:self.legacyDatabaseFilePath] &&
-                        sharedDataFilePath:self.sharedDataDatabaseFilePath
+        [fileManager fileExistsAtPath:self.sharedDataDatabaseFilePath]) {
-                             exceptionName:TSStorageManagerExceptionName_CouldNotMoveDatabaseFile];
+        // In the case that we have a "database conflict" (i.e. database files
+        // in the src and dst locations), ensure database integrity by renaming
+        // all of the dst database files.
+        for (NSString *filePath in @[
+                 self.sharedDataDatabaseFilePath,
+                 self.sharedDataDatabaseFilePath_SHM,
+                 self.sharedDataDatabaseFilePath_WAL,
+             ]) {
+            error = [OWSFileSystem renameFilePathUsingRandomExtension:filePath];
+            if (error) {
+                return error;
+            }
+        }
+    }
+
+    error =
+        [OWSFileSystem moveAppFilePath:self.legacyDatabaseFilePath sharedDataFilePath:self.sharedDataDatabaseFilePath];
     if (error) {
         return error;
     }
     error = [OWSFileSystem moveAppFilePath:self.legacyDatabaseFilePath_SHM
-                        sharedDataFilePath:self.sharedDataDatabaseFilePath_SHM
+                        sharedDataFilePath:self.sharedDataDatabaseFilePath_SHM];
-                             exceptionName:TSStorageManagerExceptionName_CouldNotMoveDatabaseFile];
     if (error) {
         return error;
     }
     error = [OWSFileSystem moveAppFilePath:self.legacyDatabaseFilePath_WAL
-                        sharedDataFilePath:self.sharedDataDatabaseFilePath_WAL
+                        sharedDataFilePath:self.sharedDataDatabaseFilePath_WAL];
-                             exceptionName:TSStorageManagerExceptionName_CouldNotMoveDatabaseFile];
     if (error) {
         return error;
     }

SignalServiceKit/src/Util/OWSFileSystem.h

@@ -17,9 +17,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (NSString *)cachesDirectoryPath;
 
-+ (nullable NSError *)moveAppFilePath:(NSString *)oldFilePath
++ (nullable NSError *)renameFilePathUsingRandomExtension:(NSString *)oldFilePath;
-                   sharedDataFilePath:(NSString *)newFilePath
+
-                        exceptionName:(NSString *)exceptionName;
++ (nullable NSError *)moveAppFilePath:(NSString *)oldFilePath sharedDataFilePath:(NSString *)newFilePath;
 
 // Returns NO IFF the directory does not exist and could not be created.
 + (BOOL)ensureDirectoryExists:(NSString *)dirPath;

SignalServiceKit/src/Util/OWSFileSystem.m

@@ -108,38 +108,47 @@ NS_ASSUME_NONNULL_BEGIN
     return paths[0];
 }
 
-+ (nullable NSError *)moveAppFilePath:(NSString *)oldFilePath
++ (nullable NSError *)renameFilePathUsingRandomExtension:(NSString *)oldFilePath
-                   sharedDataFilePath:(NSString *)newFilePath
-                        exceptionName:(NSString *)exceptionName
 {
     NSFileManager *fileManager = [NSFileManager defaultManager];
     if (![fileManager fileExistsAtPath:oldFilePath]) {
         return nil;
     }
 
-    DDLogInfo(@"%@ Moving file or directory from: %@ to: %@", self.logTag, oldFilePath, newFilePath);
+    NSString *newFilePath =
+        [[oldFilePath stringByAppendingString:@"."] stringByAppendingString:[NSUUID UUID].UUIDString];
 
-    if ([fileManager fileExistsAtPath:newFilePath]) {
+    DDLogInfo(@"%@ Moving file or directory from: %@ to: %@", self.logTag, oldFilePath, newFilePath);
-        // If a file/directory already exists at the destination,
-        // try to move it "aside" by renaming it with an extension.
-        NSString *legacyFilePath =
-            [[newFilePath stringByAppendingString:@"."] stringByAppendingString:[NSUUID UUID].UUIDString];
-        DDLogInfo(@"%@ Trying to rename pre-existing destination file or directory from: %@ to: %@",
-            self.logTag,
-            newFilePath,
-            legacyFilePath);
 
     NSError *_Nullable error;
-        BOOL success = [fileManager moveItemAtPath:newFilePath toPath:legacyFilePath error:&error];
+    BOOL success = [fileManager moveItemAtPath:oldFilePath toPath:newFilePath error:&error];
     if (!success || error) {
-            OWSProdLogAndFail(
+        OWSProdLogAndFail(@"%@ Could not move file or directory from: %@ to: %@, error: %@",
-                @"%@ Could not move pre-existing destination file or directory from: %@ to: %@, error: %@",
             self.logTag,
+            oldFilePath,
             newFilePath,
-                legacyFilePath,
             error);
         return error;
     }
+    return nil;
+}
+
++ (nullable NSError *)moveAppFilePath:(NSString *)oldFilePath sharedDataFilePath:(NSString *)newFilePath
+{
+    NSFileManager *fileManager = [NSFileManager defaultManager];
+    if (![fileManager fileExistsAtPath:oldFilePath]) {
+        return nil;
+    }
+
+    DDLogInfo(@"%@ Moving file or directory from: %@ to: %@", self.logTag, oldFilePath, newFilePath);
+
+    if ([fileManager fileExistsAtPath:newFilePath]) {
+        // If a file/directory already exists at the destination,
+        // try to move it "aside" by renaming it with an extension.
+        NSError *_Nullable error = [self renameFilePathUsingRandomExtension:newFilePath];
+        if (error) {
+            return error;
+        }
     }
 
     if ([fileManager fileExistsAtPath:newFilePath]) {