From 62a6934af9c110c28fc1f69f4bb1b79ce9d0c43d Mon Sep 17 00:00:00 2001
From: Alan Third <alan@idiocy.org>
Date: Sat, 5 Dec 2020 19:40:08 +0000
Subject: [PATCH] Fix crash when using XRender and restoring image from X
 (bug#44930)

* src/dispextern.h (struct image): Add original dimension elements.
* src/image.c (image_set_transform): Store the original dimensions.
(image_get_x_image): If we're using transforms use the original
dimensions with XGetImage.
---
 src/dispextern.h | 4 ++++
 src/image.c      | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/src/dispextern.h b/src/dispextern.h
index 6b72e68d315..44556276ff5 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -3047,6 +3047,10 @@ struct image
 # if !defined USE_CAIRO && defined HAVE_XRENDER
   /* Picture versions of pixmap and mask for compositing.  */
   Picture picture, mask_picture;
+
+  /* We need to store the original image dimensions in case we have to
+     call XGetImage.  */
+  int original_width, original_height;
 # endif
 #endif	/* HAVE_X_WINDOWS */
 #ifdef HAVE_NTGUI
diff --git a/src/image.c b/src/image.c
index 956fb1325ed..7beb135f65c 100644
--- a/src/image.c
+++ b/src/image.c
@@ -2103,6 +2103,10 @@ image_set_transform (struct frame *f, struct image *img)
 # if !defined USE_CAIRO && defined HAVE_XRENDER
   if (!img->picture)
     return;
+
+  /* Store the original dimensions as we'll overwrite them later.  */
+  img->original_width = img->width;
+  img->original_height = img->height;
 # endif
 
   /* Determine size.  */
@@ -2930,6 +2934,11 @@ image_get_x_image (struct frame *f, struct image *img, bool mask_p)
 
   if (ximg_in_img)
     return ximg_in_img;
+#ifdef HAVE_XRENDER
+  else if (img->picture)
+    return XGetImage (FRAME_X_DISPLAY (f), !mask_p ? img->pixmap : img->mask,
+		      0, 0, img->original_width, img->original_height, ~0, ZPixmap);
+#endif
   else
     return XGetImage (FRAME_X_DISPLAY (f), !mask_p ? img->pixmap : img->mask,
 		      0, 0, img->width, img->height, ~0, ZPixmap);
-- 
2.39.2