Allow uploading files with zero size (#274)

* Allow uploading files with zero size

* Fix test so that it actually fails without the fix

Author: aaijazi

pkg/storage/repo.go

@@ -133,7 +133,16 @@ func (r *Repo) List(ctx context.Context, ownerId, region, cursor string, limit i
 
 // UploadToPresignedURL uploads file content to a presigned URL
 func (r *Repo) UploadToPresignedURL(ctx context.Context, presignedURL string, content io.Reader, contentLength int64) error {
-	req, err := http.NewRequestWithContext(ctx, http.MethodPut, presignedURL, content)
+	body := content
+	if contentLength == 0 {
+		// In Go's net/http, a ContentLength of 0 with a non-nil Body is treated as
+		// unknown, causing the client to use chunked transfer encoding. Presigned S3
+		// URLs do not support chunked encoding, so we use http.NoBody to ensure
+		// Content-Length: 0 is sent instead.
+		body = http.NoBody
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPut, presignedURL, body)
 	if err != nil {
 		return fmt.Errorf("failed to create upload request: %w", err)
 	}

pkg/storage/repo_test.go

@@ -3,6 +3,7 @@ package storage
 import (
 	"bytes"
 	"context"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -253,3 +254,30 @@ func TestUploadToPresignedURL_Success(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, content, receivedContent.String())
 }
+
+func TestUploadToPresignedURL_ZeroLength(t *testing.T) {
+	var receivedContentLength int64
+	var receivedTransferEncoding []string
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		receivedContentLength = r.ContentLength
+		receivedTransferEncoding = r.TransferEncoding
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	repo := &Repo{
+		httpClient: server.Client(),
+	}
+
+	// NopCloser wraps the buffer so net/http can't type-switch on it.
+	// Without this, net/http detects the empty body and skips chunked
+	// encoding, which would mask the bug this test is meant to catch.
+	body := io.NopCloser(&bytes.Buffer{})
+
+	err := repo.UploadToPresignedURL(context.Background(), server.URL, body, 0)
+
+	require.NoError(t, err)
+	require.Equal(t, int64(0), receivedContentLength, "server should receive Content-Length: 0")
+	require.Empty(t, receivedTransferEncoding, "should not use chunked transfer encoding")
+}