bug#51707: 29.0.50; [PATCH] Fix a crash on X when trying to show a tiny xwidget inside a tiny window

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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Thanks.


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From da3b274bb17c7283bc73fefc4bc38803ef895523 Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Tue, 9 Nov 2021 15:37:01 +0800
Subject: [PATCH] Prevent BadValue errors when creating tiny xwidget views

* src/xwidget.c (x_draw_glph_string): Avoid resizing xwidget views
to an invalid size.
---
 src/xwidget.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/xwidget.c b/src/xwidget.c
index d3a8d5eb82..fc76ce307e 100644
--- a/src/xwidget.c
+++ b/src/xwidget.c
@@ -1439,6 +1439,13 @@ x_draw_xwidget_glyph_string (struct glyph_string *s)
       a.event_mask = (ExposureMask | ButtonPressMask | ButtonReleaseMask
 		      | PointerMotionMask | EnterWindowMask | LeaveWindowMask);
 
+      if (clip_right - clip_left <= 0
+	  || clip_bottom - clip_top <= 0)
+	{
+	  unblock_input ();
+	  return;
+	}
+
       xv->wdesc = XCreateWindow (xv->dpy, FRAME_X_WINDOW (s->f),
 				 x + clip_left, y + clip_top,
 				 clip_right - clip_left,
@@ -1484,8 +1491,17 @@ x_draw_xwidget_glyph_string (struct glyph_string *s)
 #ifdef USE_GTK
       if (!wdesc_was_none && !moved)
 	{
-	  XResizeWindow (xv->dpy, xv->wdesc, clip_right - clip_left,
-			 clip_bottom - clip_top);
+	  if (clip_right - clip_left <= 0
+	      || clip_bottom - clip_top <= 0)
+	    {
+	      XUnmapWindow (xv->dpy, xv->wdesc);
+	      xv->hidden = true;
+	    }
+	  else
+	    {
+	      XResizeWindow (xv->dpy, xv->wdesc, clip_right - clip_left,
+			     clip_bottom - clip_top);
+	    }
 	  XFlush (xv->dpy);
 	  cairo_xlib_surface_set_size (xv->cr_surface, clip_right - clip_left,
 				       clip_bottom - clip_top);
-- 
2.31.1