fix: complete empty TUS multipart uploads when Upload-Length is 0

src/storage/protocols/tus/s3-store.test.ts

@@ -1,4 +1,6 @@
 import { HttpResponse } from '@smithy/protocol-http'
+import { S3Store as TusS3Store } from '@tus/s3-store'
+import type { Upload } from '@tus/server'
 import { S3Store } from './s3-store'
 
 class TestS3Store extends S3Store {
@@ -26,7 +28,24 @@ function createStore(
   })
 }
 
+function baseUpload(overrides: Partial<Upload> = {}): Upload {
+  return {
+    id: 'tenant/bucket/empty.txt/version-1',
+    offset: 0,
+    size: 0,
+    sizeIsDeferred: false,
+    metadata: { contentType: 'text/plain' },
+    creation_date: undefined,
+    storage: undefined,
+    ...overrides,
+  } as Upload
+}
+
 describe('S3Store', () => {
+  afterEach(() => {
+    vi.restoreAllMocks()
+  })
+
   test('removes the no-op logger middleware from the internal TUS client', () => {
     const store = createStore(vi.fn())
 
@@ -67,4 +86,42 @@ describe('S3Store', () => {
       $metadata: { attempts: 1, totalRetryDelay: 0 },
     })
   })
+
+  test('finalizes an empty multipart upload when Upload-Length is 0', async () => {
+    const store = createStore(vi.fn())
+    const upload = baseUpload({ size: 0 })
+    const metadata = {
+      file: upload,
+      'upload-id': 'mpu-123',
+      'tus-version': '1.0.0',
+    }
+
+    vi.spyOn(TusS3Store.prototype, 'create').mockResolvedValue(upload)
+    const getMetadata = vi.spyOn(store as any, 'getMetadata').mockResolvedValue(metadata)
+    const finish = vi.spyOn(store as any, 'finishMultipartUpload').mockResolvedValue('s3://loc')
+    const complete = vi.spyOn(store as any, 'completeMetadata').mockResolvedValue(undefined)
+    const clear = vi.spyOn(store as any, 'clearCache').mockResolvedValue(undefined)
+
+    await expect(store.create(upload)).resolves.toBe(upload)
+
+    expect(getMetadata).toHaveBeenCalledWith(upload.id)
+    expect(finish).toHaveBeenCalledWith(metadata, [])
+    expect(complete).toHaveBeenCalledWith(upload)
+    expect(clear).toHaveBeenCalledWith(upload.id)
+  })
+
+  test('does not finalize multipart upload for non-zero or deferred sizes', async () => {
+    const store = createStore(vi.fn())
+    const finish = vi.spyOn(store as any, 'finishMultipartUpload')
+
+    for (const upload of [
+      baseUpload({ size: 1 }),
+      baseUpload({ size: 0, sizeIsDeferred: true }),
+    ]) {
+      vi.spyOn(TusS3Store.prototype, 'create').mockResolvedValueOnce(upload)
+      await store.create(upload)
+    }
+
+    expect(finish).not.toHaveBeenCalled()
+  })
 })

src/storage/protocols/tus/s3-store.ts

@@ -1,8 +1,31 @@
 import { type Options, S3Store as TusS3Store } from '@tus/s3-store'
+import type { Upload } from '@tus/server'
 
 export class S3Store extends TusS3Store {
   constructor(options: Options) {
     super(options)
     this.client.middlewareStack.remove('loggerMiddleware')
   }
+
+  /**
+   * TUS treats `Upload-Length: 0` as immediately final and calls `onUploadFinish`
+   * without `write()`. Upstream `S3Store.create` only starts a multipart upload,
+   * so `HeadObject` in our finish hook 404s and clients see a bare Not Found.
+   *
+   * Complete the empty multipart here (upstream `finishMultipartUpload` already
+   * uploads a zero-byte part when `parts` is empty) so the object exists before
+   * finish runs.
+   */
+  async create(upload: Upload): Promise<Upload> {
+    const created = await super.create(upload)
+
+    if (upload.size === 0 && !upload.sizeIsDeferred) {
+      const metadata = await this.getMetadata(upload.id)
+      await this.finishMultipartUpload(metadata, [])
+      await this.completeMetadata(metadata.file)
+      await this.clearCache(upload.id)
+    }
+
+    return created
+  }
 }