From 7f7d9b029dba8489b460f2bbd9a23ce4881e6a71 Mon Sep 17 00:00:00 2001
From: Marius Kleidl <marius@transloadit.com>
Date: Thu, 14 Dec 2023 08:42:25 +0100
Subject: [PATCH] handler: Fix panic on GOARCH=386

Fixes https://github.com/tus/tusd/issues/1047
---
 pkg/handler/body_reader.go | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/pkg/handler/body_reader.go b/pkg/handler/body_reader.go
index 6ca7a0f44..8f8d2e3f7 100644
--- a/pkg/handler/body_reader.go
+++ b/pkg/handler/body_reader.go
@@ -19,10 +19,16 @@ import (
 // the error but this can instead be done in the handler.
 // In addition, the bodyReader keeps track of how many bytes were read.
 type bodyReader struct {
+	// bytesCounter is the first field to ensure that its properly aligned,
+	// otherwise we run into alignment issues on some 32-bit builds.
+	// See https://github.com/tus/tusd/issues/1047
+	// See https://pkg.go.dev/sync/atomic#pkg-note-BUG
+	// TODO: In the future we should move all of these values to the safe
+	// atomic.Uint64 type, which takes care of alignment automatically.
+	bytesCounter int64
 	ctx          *httpContext
 	reader       io.ReadCloser
 	err          error
-	bytesCounter int64
 	onReadDone   func()
 }