From 9008599975227eb2c416f27a6afed79ca0e490e2 Mon Sep 17 00:00:00 2001
From: David Baynard <git@baynard.dev>
Date: Thu, 9 Nov 2023 03:19:49 +0000
Subject: [PATCH] Write (deferred) headers

Unlike `ResponseWriter.Write`, `io.Copy` doesn't add the deferred
headers. Deferred headers are applied _after_ the proxied response.

This (not standalong) is CORS configuration, for example, that only
works with the change.

```Caddyfile
header {
  Access-Control-Allow-Origin "{re.origin.0}"
  Access-Control-Allow-Credentials true
  Access-Control-Expose-Headers "{args[1]}"
  Vary Origin
  defer
}
```
---
 s3proxy.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/s3proxy.go b/s3proxy.go
index 281acb5..bec2cfc 100644
--- a/s3proxy.go
+++ b/s3proxy.go
@@ -332,6 +332,7 @@ func (p S3Proxy) writeResponseFromGetObject(w http.ResponseWriter, obj *s3.GetOb
 	if obj.Body != nil {
 		// io.Copy will set Content-Length
 		w.Header().Del("Content-Length")
+		w.WriteHeader(http.StatusOK)
 		_, err = io.Copy(w, obj.Body)
 	}