Compression: Handle auto encryption when size is unknown (minio#7600)

When size is unknown and auto encryption is enabled,
and compression is set to true, putobject API is failing.

Moving adding the SSE-S3 header as part of the request to before
checking if compression can be done, otherwise the size is set to -1
and that seems to cause problems.

cmd/object-handlers.go

@@ -1176,6 +1176,11 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 		}
 	}
 
+	// This request header needs to be set prior to setting ObjectOptions
+	if globalAutoEncryption && !crypto.SSEC.IsRequested(r.Header) {
+		r.Header.Add(crypto.SSEHeader, crypto.SSEAlgorithmAES256)
+	}
+
 	actualSize := size
 
 	if objectAPI.IsCompressionSupported() && isCompressible(r.Header, object) && size > 0 {
@@ -1205,10 +1210,6 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 	rawReader := hashReader
 	pReader := NewPutObjReader(rawReader, nil, nil)
 
-	// This request header needs to be set prior to setting ObjectOptions
-	if globalAutoEncryption && !crypto.SSEC.IsRequested(r.Header) {
-		r.Header.Add(crypto.SSEHeader, crypto.SSEAlgorithmAES256)
-	}
 	// get gateway encryption options
 	var opts ObjectOptions
 	opts, err = putOpts(ctx, r, bucket, object, metadata)