null byte check for JSON.stringify in archiving

services/track-changes/app/coffee/MongoAWS.coffee

@@ -46,6 +46,9 @@ module.exports = MongoAWS =
 			return callback new Error("cannot find pack to send to s3") if not result?
 			return callback new Error("refusing to send pack with TTL to s3") if result.expiresAt?
 			uncompressedData = JSON.stringify(result)
+			if uncompressedData.indexOf("\u0000") != -1
+				error = new Error("null bytes found in upload")
+				logger.error err: error, project_id: project_id, doc_id: doc_id, pack_id: pack_id, error.message
 			zlib.gzip uncompressedData, (err, buf) ->
 				logger.log {project_id, doc_id, pack_id, origSize: uncompressedData.length, newSize: buf.length}, "compressed pack"
 				return callback(err) if err?