From b7199fe3d71f88ae72718980643eef9a3d3f2ed5 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Wed, 29 May 2019 10:24:49 +0100
Subject: [PATCH] s3: when copying from s3 to s3, preserve metadata #111

See: https://forum.rclone.org/t/s3-bucket-migration-with-metadata-issues/10262
---
 backend/s3/s3.go | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/backend/s3/s3.go b/backend/s3/s3.go
index fc570413b..8a7242a22 100644
--- a/backend/s3/s3.go
+++ b/backend/s3/s3.go
@@ -3171,11 +3171,26 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 
 	multipart := size < 0 || size >= int64(o.fs.opt.UploadCutoff)
 
-	// Set the mtime in the meta data
-	metadata := map[string]*string{
-		metaMtime: aws.String(swift.TimeToFloatString(modTime)),
+	// Metadata for upload
+	metadata := map[string]*string{}
+	fs.Debugf(o, "src = %#v", src)
+
+	// Read metadata from source s3 object if available
+	srcObj, ok := fs.UnWrapObjectInfo(src).(*Object)
+	if ok {
+		fs.Debugf(o, "Reading metadata from %v", srcObj)
+		err := srcObj.readMetaData(ctx) // reads info and meta, returning an error
+		if err != nil {
+			return err
+		}
+		for k, v := range srcObj.meta {
+			metadata[k] = v
+		}
 	}
 
+	// Set the mtime in the meta data
+	metadata[metaMtime] = aws.String(swift.TimeToFloatString(modTime))
+
 	// read the md5sum if available
 	// - for non multipart
 	//    - so we can add a ContentMD5