Respond to CR.

Signal/src/util/OWSBackupImportJob.m

@@ -276,6 +276,13 @@ NSString *const kOWSBackup_ImportDatabaseKeySpec = @"kOWSBackup_ImportDatabaseKe
             DDLogError(@"%@ skipping redundant file restore: %@.", self.logTag, dstFilePath);
             continue;
         }
+        NSString *dstDirPath = [dstFilePath stringByDeletingLastPathComponent];
+        if (![NSFileManager.defaultManager fileExistsAtPath:dstDirPath]) {
+            if (![OWSFileSystem ensureDirectoryExists:dstDirPath]) {
+                DDLogError(@"%@ couldn't create directory for file restore: %@.", self.logTag, dstFilePath);
+                continue;
+            }
+        }
         @autoreleasepool {
             if (![self.backupIO decryptFileAsFile:item.downloadFilePath
                                       dstFilePath:dstFilePath

Signal/src/util/OWSBackupJob.h

@@ -26,7 +26,9 @@ typedef void (^OWSBackupJobManifestFailure)(NSError *error);
 
 @property (nonatomic) NSData *encryptionKey;
 
-// This property is only set for certain types of manifest item;
+// This property is only set for certain types of manifest item,
+// namely attachments where we need to know where the attachment's
+// file should reside relative to the attachments folder.
 @property (nonatomic, nullable) NSString *relativeFilePath;
 
 // This property is only set if the manifest item is downloaded.