From 7015bb3efd5e588e50be9948f32ee04fa4bd8319 Mon Sep 17 00:00:00 2001
From: Carlos Garnacho <carlosg@gnome.org>
Date: Sat, 11 Apr 2020 17:21:20 +0200
Subject: [PATCH] x11: Don't exceed transfer size in INCR chunks

The stream automatically flushes after data size exceeds the
size we deem for INCR chunks, but we still try to copy it all.
Actually limit the data we copy, and leave the rest for future
INCR chunks.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1198
---
 src/x11/meta-x11-selection-output-stream.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/x11/meta-x11-selection-output-stream.c b/src/x11/meta-x11-selection-output-stream.c
index 4cdde8ab3..7179074e9 100644
--- a/src/x11/meta-x11-selection-output-stream.c
+++ b/src/x11/meta-x11-selection-output-stream.c
@@ -203,7 +203,7 @@ meta_x11_selection_output_stream_perform_flush (MetaX11SelectionOutputStream *st
   MetaX11SelectionOutputStreamPrivate *priv =
     meta_x11_selection_output_stream_get_instance_private (stream);
   Display *xdisplay;
-  size_t element_size, n_elements;
+  size_t element_size, n_elements, max_size;
   gboolean first_chunk = FALSE;
   int error_code;
 
@@ -218,6 +218,7 @@ meta_x11_selection_output_stream_perform_flush (MetaX11SelectionOutputStream *st
 
   element_size = get_element_size (priv->format);
   n_elements = priv->data->len / element_size;
+  max_size = get_max_request_size (priv->x11_display);
 
   if (!priv->incr)
     first_chunk = TRUE;
@@ -247,9 +248,13 @@ meta_x11_selection_output_stream_perform_flush (MetaX11SelectionOutputStream *st
     }
   else
     {
+      size_t copy_n_elements;
+
       if (priv->incr && priv->data->len > 0)
         priv->delete_pending = TRUE;
 
+      copy_n_elements = MIN (n_elements, max_size / element_size);
+
       XChangeProperty (xdisplay,
                        priv->xwindow,
                        priv->xproperty,
@@ -257,8 +262,8 @@ meta_x11_selection_output_stream_perform_flush (MetaX11SelectionOutputStream *st
                        priv->format,
                        PropModeReplace,
                        priv->data->data,
-                       n_elements);
-      g_byte_array_remove_range (priv->data, 0, n_elements * element_size);
+                       copy_n_elements);
+      g_byte_array_remove_range (priv->data, 0, copy_n_elements * element_size);
     }
 
   if (first_chunk)