limit writes to

* chunks of 511MiB and
* total of 2GiB

lib/serialization/FileMiddleware.js

@@ -40,7 +40,8 @@ Section -> Buffer
 
 // "wpc" + 1 in little-endian
 const VERSION = 0x01637077;
-const _1GiB = 1 * 1024 * 1024 * 1024;
+const WRITE_LIMIT_TOTAL = 0x7fff0000;
+const WRITE_LIMIT_CHUNK = 511 * 1024 * 1024;
 
 /**
  * @param {Buffer[]} buffers buffers
@@ -454,22 +455,42 @@ class FileMiddleware extends SerializerMiddleware {
 							stream.on("error", err => reject(err));
 							stream.on("finish", () => resolve());
 						}
-						// use unsafe
-						if (size <= _1GiB) {
-							for (const b of content) stream.write(b);
-							return stream.end();
+						// split into chunks for WRITE_LIMIT_CHUNK size
+						const chunks = [];
+						for (const b of content) {
+							if (b.length < WRITE_LIMIT_CHUNK) {
+								chunks.push(b);
+							} else {
+								for (let i = 0; i < b.length; i += WRITE_LIMIT_CHUNK) {
+									chunks.push(b.slice(i, i + WRITE_LIMIT_CHUNK));
+								}
+							}
 						}
 
-						const len = content.length;
+						const len = chunks.length;
 						let i = 0;
 						const batchWrite = err => {
+							// will be handled in "on" error handler
+							if (err) return;
+
 							if (i === len) {
 								stream.end();
 								return;
 							}
-							// will be handle in "on" handler
-							if (err) return;
-							stream.write(content[i++], batchWrite);
+
+							// queue up a batch of chunks up to the write limit
+							// end is exclusive
+							let end = i;
+							let sum = chunks[end++].length;
+							while (end < len) {
+								sum += chunks[end].length;
+								if (sum > WRITE_LIMIT_TOTAL) break;
+								end++;
+							}
+							while (i < end - 1) {
+								stream.write(chunks[i++]);
+							}
+							stream.write(chunks[i++], batchWrite);
 						};
 						batchWrite();
 					});