From cb4b44b8f41f368ee68cdc1456470e3f1f6e65c8 Mon Sep 17 00:00:00 2001
From: Matthew Chen <charlesmchen@gmail.com>
Date: Thu, 4 Jan 2018 18:17:53 -0500
Subject: [PATCH] Lock databases during backup export.

---
 Signal/src/util/OWSBackup.m | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/Signal/src/util/OWSBackup.m b/Signal/src/util/OWSBackup.m
index 640f21bf9..e011e5cbd 100644
--- a/Signal/src/util/OWSBackup.m
+++ b/Signal/src/util/OWSBackup.m
@@ -188,16 +188,22 @@ NS_ASSUME_NONNULL_BEGIN
                    backupDirPath:backupDirPath]) {
         return;
     }
-    if (![self copyDirectory:OWSFileSystem.appDocumentDirectoryPath
-                  dstDirName:@"appDocumentDirectoryPath"
-               backupDirPath:backupDirPath]) {
-        return;
-    }
-    if (![self copyDirectory:OWSFileSystem.appSharedDataDirectoryPath
-                  dstDirName:@"appSharedDataDirectoryPath"
-               backupDirPath:backupDirPath]) {
-        return;
-    }
+    // Use a read/write transaction to acquire a file lock on the database files.
+    //
+    // TODO: If we use multiple database files, lock them too.
+    [TSStorageManager.sharedManager.newDatabaseConnection
+        readWriteWithBlock:^(YapDatabaseReadWriteTransaction *_Nonnull transaction) {
+            if (![self copyDirectory:OWSFileSystem.appDocumentDirectoryPath
+                          dstDirName:@"appDocumentDirectoryPath"
+                       backupDirPath:backupDirPath]) {
+                return;
+            }
+            if (![self copyDirectory:OWSFileSystem.appSharedDataDirectoryPath
+                          dstDirName:@"appSharedDataDirectoryPath"
+                       backupDirPath:backupDirPath]) {
+                return;
+            }
+        }];
     if (![self zipDirectory:backupDirPath dstFilePath:backupZipPath]) {
         return;
     }