Add content verification + retries for metadata writes (#3436)

* Add content verification + retries for metadata writes

* Lint

* Rename

* Typo

creator-node/src/fileManager.js

@@ -24,7 +24,7 @@ const EMPTY_FILE_CID = 'QmbFMke1KXqnYyBBWxB74N4c5SBnJMVAiMNRcGu6x1AwQH' // deter
 /**
  * Saves file to disk under /multihash name
  */
-async function saveFileFromBufferToDisk(req, buffer) {
+async function saveFileFromBufferToDisk(req, buffer, numRetries = 5) {
   // Make sure user has authenticated before saving file
   if (!req.session.cnodeUserUUID) {
     throw new Error('User must be authenticated to save a file')
@@ -39,6 +39,35 @@ async function saveFileFromBufferToDisk(req, buffer) {
   const dstPath = DiskManager.computeFilePath(cid)
   await fs.writeFile(dstPath, buffer)
 
+  // verify that the contents of the file match the file's cid
+  try {
+    const fileSize = (await fs.stat(dstPath)).size
+    const fileIsEmpty = fileSize === 0
+    // there is one case where an empty file could be valid, check for that CID explicitly
+    if (fileIsEmpty && cid !== EMPTY_FILE_CID) {
+      throw new Error(`File has no content, content length is 0: ${cid}`)
+    }
+
+    const expectedCID = await LibsUtils.fileHasher.generateNonImageCid(
+      dstPath,
+      genericLogger.child(req.logContext)
+    )
+    if (cid !== expectedCID) {
+      // delete this file because the next time we run sync and we see it on disk, we'll assume we have it and it's correct
+      throw new Error(
+        `File contents don't match their expected CID. CID: ${cid} expected CID: ${expectedCID}`
+      )
+    }
+  } catch (e) {
+    await removeFile(dstPath)
+    if (numRetries > 0) {
+      return saveFileFromBufferToDisk(req, buffer, numRetries - 1)
+    }
+    throw new Error(
+      `saveFileFromBufferToDisk - Error during content verification for multihash ${cid} ${e.message}`
+    )
+  }
+
   return { cid, dstPath }
 }
 
@@ -358,7 +387,7 @@ async function saveFileForMultihashToFS(
         })
         // delete this file because the next time we run sync and we see it on disk, we'll assume we have it and it's correct
         throw new Error(
-          `File contents don't their expected CID. CID: ${multihash} expected CID: ${expectedCid}`
+          `File contents don't match their expected CID. CID: ${multihash} expected CID: ${expectedCid}`
         )
       }
       decisionTree.push({