[mutter/gnome-3-36] x11: Add STRING/UTF8_STRING targets for selection sources lacking them

[Robert Mader <rmader src gnome org>]

commit 52a6b5df5f60dd3caef34fb3d66467a381906b2e
Author: Sebastian Keller <skeller gnome org>
Date:   Fri Jul 24 21:20:58 2020 +0200

    x11: Add STRING/UTF8_STRING targets for selection sources lacking them
    
    The memory selection source was only providing the "text/plain" or the
    "text/plain;charset=utf-8" mimetype, but not "STRING" or "UTF8_STRING",
    which some X11 clients, like wine, are looking for. This was breaking
    pasting from the clipboard in wine applications.
    
    Fix this by adding those targets when they are missing and the selection
    source provides the corresponding mimetypes.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1369
    
    (cherry picked from commit c7d14244b1b025199fed945e8eb51ebc5d804b4e)

 src/x11/meta-x11-selection.c | 45 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 38 insertions(+), 7 deletions(-)
---
diff --git a/src/x11/meta-x11-selection.c b/src/x11/meta-x11-selection.c
index 77659fcfaa..f9b3607a75 100644
--- a/src/x11/meta-x11-selection.c
+++ b/src/x11/meta-x11-selection.c
@@ -79,18 +79,49 @@ static GBytes *
 mimetypes_to_bytes (GList   *mimetypes,
                     Display *xdisplay)
 {
-  gint i = 0, len = g_list_length (mimetypes) + 2;
-  Atom *atoms = g_new0 (Atom, len);
+  GArray *atoms = g_array_new (FALSE, FALSE, sizeof (Atom));
   GList *l;
+  char *mimetype;
+  Atom atom;
+  gboolean utf8_string_found = FALSE, utf8_string_mimetype_found = FALSE;
+  gboolean string_found = FALSE, string_mimetype_found = FALSE;
+  GBytes *bytes;
 
   for (l = mimetypes; l; l = l->next)
-    atoms[i++] = XInternAtom (xdisplay, l->data, False);
+    {
+      mimetype = l->data;
+      atom = XInternAtom (xdisplay, mimetype, False);
+      g_array_append_val (atoms, atom);
+      utf8_string_mimetype_found |= strcmp (mimetype, UTF8_STRING_MIMETYPE) == 0;
+      utf8_string_found |= strcmp (mimetype, "UTF8_STRING") == 0;
+      string_mimetype_found |= strcmp (mimetype, STRING_MIMETYPE) == 0;
+      string_found |= strcmp (mimetype, "STRING") == 0;
+    }
+
+  /* Some X11 clients can only handle STRING/UTF8_STRING but not the
+   * corresponding mimetypes. */
+  if (utf8_string_mimetype_found && !utf8_string_found)
+    {
+      atom = XInternAtom (xdisplay, "UTF8_STRING", False);
+      g_array_append_val (atoms, atom);
+    }
+
+  if (string_mimetype_found && !string_found)
+    {
+      atom = XInternAtom (xdisplay, "STRING", False);
+      g_array_append_val (atoms, atom);
+    }
+
+  atom = XInternAtom (xdisplay, "TARGETS", False);
+  g_array_append_val (atoms, atom);
+
+  atom = XInternAtom (xdisplay, "TIMESTAMP", False);
+  g_array_append_val (atoms, atom);
 
-  atoms[i++] = XInternAtom (xdisplay, "TARGETS", False);
-  atoms[i++] = XInternAtom (xdisplay, "TIMESTAMP", False);
-  g_assert (i == len);
+  bytes = g_bytes_new_take (atoms->data, atoms->len * sizeof (Atom));
+  g_array_free (atoms, FALSE);
 
-  return g_bytes_new_take (atoms, len * sizeof (Atom));
+  return bytes;
 }
 
 static void