Load attachments before writing them upon export

js/modules/backup.js

@@ -506,9 +506,11 @@ async function writeAttachment(attachment, options) {
   await stream.close();
 }
 
-async function writeAttachments(attachments, options) {
+async function writeAttachments(rawAttachments, options) {
   const { name } = options;
 
+  const { loadAttachmentData } = Signal.Migrations;
+  const attachments = await Promise.all(rawAttachments.map(loadAttachmentData));
   const promises = _.map(
     attachments,
     (attachment, index) => writeAttachment(attachment, Object.assign({}, options, {
@@ -626,7 +628,7 @@ async function exportConversation(db, conversation, options) {
         const jsonString = JSON.stringify(stringify(message));
         stream.write(jsonString);
 
-        if (attachments && attachments.length) {
+        if (attachments && attachments.length > 0) {
           const exportAttachments = () => writeAttachments(attachments, {
             dir: attachmentsDir,
             name,

preload.js

@@ -116,6 +116,8 @@ const readAttachmentData = Attachments.createReader(attachmentsPath);
 const writeNewAttachmentData = Attachments.createWriterForNew(attachmentsPath);
 const writeExistingAttachmentData = Attachments.createWriterForExisting(attachmentsPath);
 
+const loadAttachmentData = Attachment.loadData(readAttachmentData);
+
 // Injected context functions to keep `Message` agnostic from Electron:
 const upgradeSchemaContext = {
   writeNewAttachmentData,
@@ -140,7 +142,7 @@ window.Signal.Migrations.deleteAttachmentData =
 window.Signal.Migrations.getPlaceholderMigrations = getPlaceholderMigrations;
 window.Signal.Migrations.importMessage =
   Message.createImporter(writeExistingAttachmentData);
-window.Signal.Migrations.loadAttachmentData = Attachment.loadData(readAttachmentData);
+window.Signal.Migrations.loadAttachmentData = loadAttachmentData;
 window.Signal.Migrations.Migrations0DatabaseWithAttachmentData =
   require('./js/modules/migrations/migrations_0_database_with_attachment_data');
 window.Signal.Migrations.Migrations1DatabaseWithoutAttachmentData =