From 3795b2c8bae9c09131bb72b662333bdf39771512 Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Sun, 24 Jul 2022 07:15:49 -0700
Subject: [PATCH] Add compression scheme to header (#15395)

For easier debugging. We still do not return compressed size for security reasons.
---
 cmd/api-headers.go       | 7 +++++++
 internal/http/headers.go | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/cmd/api-headers.go b/cmd/api-headers.go
index 2a8b2ab04..60cd14f14 100644
--- a/cmd/api-headers.go
+++ b/cmd/api-headers.go
@@ -199,5 +199,12 @@ func setObjectHeaders(w http.ResponseWriter, objInfo ObjectInfo, rs *HTTPRangeSp
 		lc.SetPredictionHeaders(w, objInfo.ToLifecycleOpts())
 	}
 
+	if v, ok := objInfo.UserDefined[ReservedMetadataPrefix+"compression"]; ok {
+		if i := strings.LastIndexByte(v, '/'); i >= 0 {
+			v = v[i+1:]
+		}
+		w.Header()[xhttp.MinIOCompressed] = []string{v}
+	}
+
 	return nil
 }
diff --git a/internal/http/headers.go b/internal/http/headers.go
index 294dad0df..9b92dd4be 100644
--- a/internal/http/headers.go
+++ b/internal/http/headers.go
@@ -187,6 +187,9 @@ const (
 	MinIOSourceObjectLegalHoldTimestamp = "X-Minio-Source-Replication-LegalHold-Timestamp"
 	// predicted date/time of transition
 	MinIOTransition = "X-Minio-Transition"
+
+	// MinIOCompressed is returned when object is compressed
+	MinIOCompressed = "X-Minio-Compressed"
 )
 
 // Common http query params S3 API