@tus/s3-store: gracefully handle zero byte uploads

.changeset/public-beds-sing.md

@@ -0,0 +1,5 @@
+---
+"@tus/s3-store": patch
+---
+
+Handle zero byte uploads gracefully

packages/s3-store/src/index.ts

@@ -1,7 +1,7 @@
 import os from 'node:os'
 import fs, {promises as fsProm} from 'node:fs'
 import stream, {promises as streamProm} from 'node:stream'
-import type {Readable} from 'node:stream'
+import {Readable} from 'node:stream'
 
 import type AWS from '@aws-sdk/client-s3'
 import {NoSuchKey, NotFound, S3, type S3ClientConfig} from '@aws-sdk/client-s3'
@@ -231,7 +231,7 @@ export class S3Store extends DataStore {
 
   protected async uploadPart(
     metadata: MetadataValue,
-    readStream: fs.ReadStream | Readable,
+    readStream: fs.ReadStream | Readable | Buffer,
     partNumber: number
   ): Promise<string> {
     const data = await this.client.uploadPart({
@@ -445,7 +445,6 @@ export class S3Store extends DataStore {
           log(`[${metadata.file.id}] failed to remove chunk ${pendingChunkFilepath}`)
         }
       }
-
       promises.push(Promise.reject(error))
     } finally {
       // Wait for all promises. We don't want to return
@@ -463,6 +462,16 @@ export class S3Store extends DataStore {
    * This is where S3 concatenates all the uploaded parts.
    */
   protected async finishMultipartUpload(metadata: MetadataValue, parts: Array<AWS.Part>) {
+    // Handle zero-byte uploads - S3 requires at least one part to complete a multipart upload
+    // S3 allows the last part to be 0 bytes, so we upload a single empty part
+    if (parts.length === 0) {
+      const eTag = await this.uploadPart(metadata, Buffer.alloc(0), 1)
+      parts.push({
+        ETag: eTag,
+        PartNumber: 1,
+      })
+    }
+
     const response = await this.client.completeMultipartUpload({
       Bucket: this.bucket,
       Key: metadata.file.id,

packages/s3-store/src/test/index.ts

@@ -1,12 +1,13 @@
 import path from 'node:path'
 import assert from 'node:assert/strict'
 import {Readable} from 'node:stream'
+import stream from 'node:stream/promises'
 
 import sinon from 'sinon'
 
 import {S3Store} from '@tus/s3-store'
 import * as shared from '../../../utils/dist/test/stores.js'
-import {Upload} from '@tus/utils'
+import {StreamLimiter, Upload} from '@tus/utils'
 
 const fixturesPath = path.resolve('../', '../', 'test', 'fixtures')
 const storePath = path.resolve('../', '../', 'test', 'output', 's3-store')
@@ -18,6 +19,7 @@ const s3ClientConfig = {
     secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY as string,
   },
   region: process.env.AWS_REGION,
+  endpoint: process.env.AWS_ENDPOINT,
 }
 
 describe('S3DataStore', () => {
@@ -253,10 +255,12 @@ describe('S3DataStore', () => {
 
     await store.create(upload)
 
-    const offset = await store.write(
+    const offset = await stream.pipeline(
       Readable.from(Buffer.alloc(size)),
-      upload.id,
-      upload.offset
+      new StreamLimiter(999),
+      async (stream) => {
+        return store.write(stream as StreamLimiter, upload.id, upload.offset)
+      }
     )
     assert.equal(offset, size, 'Write should return 0 offset')