From ddd137d31769185e6de4f27dfaba8de6498bb1ea Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Thu, 19 Dec 2024 10:21:46 -0800
Subject: [PATCH] ListObjectParts should return actual size (#20782)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fixes #20781:

```
λ aws --endpoint-url http://127.0.0.1:9001 s3api list-parts --bucket testbucket --key test.testcompress --upload-id "ZDM0YzUwM2YtZWM1Zi00NWI2LTgxMzYtZTIwMGE3Yjc0Y2Y1LjYyMzgyMmFhLWU2N2QtNGUyYS04NDE1LWUzZDFlZmJmMWUyZHgxNzM0NjI1MjgyMDkyNzY4MDAw"
{
    "Parts": [
        {
            "PartNumber": 1,
            "LastModified": "2024-12-19T16:47:04.334000+00:00",
            "ETag": "\"7025f242f56479e06c435c0b500cdbb2\"",
            "Size": 2002
        }
    ],
    "ChecksumAlgorithm": "",
    "Initiator": {
        "ID": "02d6176db174dc93cb1b899f7c6078f08654445fe8cf1b6ce98d8855f66bdbf4",
        "DisplayName": "02d6176db174dc93cb1b899f7c6078f08654445fe8cf1b6ce98d8855f66bdbf4"
    },
    "Owner": {
        "DisplayName": "02d6176db174dc93cb1b899f7c6078f08654445fe8cf1b6ce98d8855f66bdbf4",
        "ID": "02d6176db174dc93cb1b899f7c6078f08654445fe8cf1b6ce98d8855f66bdbf4"
    },
    "StorageClass": "STANDARD"
}
```

(for whatever reason the python script generated a 2002 byte file ;)
---
 cmd/object-multipart-handlers.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/cmd/object-multipart-handlers.go b/cmd/object-multipart-handlers.go
index d32ad30d4..bd0c01684 100644
--- a/cmd/object-multipart-handlers.go
+++ b/cmd/object-multipart-handlers.go
@@ -1204,6 +1204,10 @@ func (api objectAPIHandlers) ListObjectPartsHandler(w http.ResponseWriter, r *ht
 			listPartsInfo.Parts[i].ETag = tryDecryptETag(objectEncryptionKey, p.ETag, kind == crypto.S3)
 			listPartsInfo.Parts[i].Size = p.ActualSize
 		}
+	} else if _, ok := listPartsInfo.UserDefined[ReservedMetadataPrefix+"compression"]; ok {
+		for i, p := range listPartsInfo.Parts {
+			listPartsInfo.Parts[i].Size = p.ActualSize
+		}
 	}
 
 	response := generateListPartsResponse(listPartsInfo, encodingType)