From 23f8a12922a019e74b464016c167bed6efdc8f8f Mon Sep 17 00:00:00 2001
From: Richard Hansen <rhansen@rhansen.org>
Date: Fri, 26 Nov 2021 01:35:02 -0500
Subject: [PATCH] ImportEtherpad: Don't make any changes if data is bad

---
 src/node/utils/ImportEtherpad.js          | 14 ++++++++++++--
 src/tests/backend/specs/ImportEtherpad.js | 10 ++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/node/utils/ImportEtherpad.js b/src/node/utils/ImportEtherpad.js
index cfa6a2643..bc54e9ca1 100644
--- a/src/node/utils/ImportEtherpad.js
+++ b/src/node/utils/ImportEtherpad.js
@@ -47,6 +47,11 @@ exports.setPadRaw = async (padId, r) => {
     if (originalPadId !== padId) throw new Error('unexpected pad ID in record');
   };
 
+  // First validate and transform values. Do not commit any records to the database yet in case
+  // there is a problem with the data.
+
+  const dbRecords = new Map();
+  const existingAuthors = new Set();
   await Promise.all(Object.entries(records).map(async ([key, value]) => {
     if (!value) {
       return;
@@ -62,7 +67,7 @@ exports.setPadRaw = async (padId, r) => {
       }
       checkOriginalPadId(value.padIDs);
       if (await authorManager.doesAuthorExist(id)) {
-        await authorManager.addPad(id, padId);
+        existingAuthors.add(id);
         return;
       }
       value.padIDs = {[padId]: 1};
@@ -79,11 +84,16 @@ exports.setPadRaw = async (padId, r) => {
       logger.warn(`(pad ${padId}) Ignoring record with unsupported key: ${key}`);
       return;
     }
-    await db.set(key, value);
+    dbRecords.set(key, value);
   }));
 
   if (unsupportedElements.size) {
     logger.warn('Ignoring unsupported elements (you might want to install a plugin): ' +
                 `${[...unsupportedElements].join(', ')}`);
   }
+
+  await Promise.all([
+    ...[...dbRecords].map(async ([k, v]) => await db.set(k, v)),
+    ...[...existingAuthors].map(async (authorId) => await authorManager.addPad(authorId, padId)),
+  ]);
 };
diff --git a/src/tests/backend/specs/ImportEtherpad.js b/src/tests/backend/specs/ImportEtherpad.js
index 7906c3afb..6dfd11112 100644
--- a/src/tests/backend/specs/ImportEtherpad.js
+++ b/src/tests/backend/specs/ImportEtherpad.js
@@ -62,6 +62,16 @@ describe(__filename, function () {
     assert(await db.get(badKey) == null);
   });
 
+  it('changes are all or nothing', async function () {
+    const authorId = makeAuthorId();
+    const data = makeExport(authorId);
+    data['pad:differentPadId:revs:0'] = data['pad:testing:revs:0'];
+    delete data['pad:testing:revs:0'];
+    assert.rejects(importEtherpad.setPadRaw(padId, JSON.stringify(data)), /unexpected pad ID/);
+    assert(!await authorManager.doesAuthorExist(authorId));
+    assert(!await padManager.doesPadExist(padId));
+  });
+
   describe('author pad IDs', function () {
     let existingAuthorId;
     let newAuthorId;