master 11080420dd: Improve gif_load error messages

[Lars Ingebrigtsen]

branch: master
commit 11080420dd7f2c34bbebf797de6eb4d4a14dae35
Author: Lars Ingebrigtsen <larsi@gnus.org>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Improve gif_load error messages
    
    * src/image.c (gif_load): Improve error reporting (bug#54848).
---
 src/image.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/image.c b/src/image.c
index e3e540e5e2..3f9111a709 100644
--- a/src/image.c
+++ b/src/image.c
@@ -8754,10 +8754,21 @@ gif_load (struct frame *f, struct image *img)
   rc = DGifSlurp (gif);
   if (rc == GIF_ERROR || gif->ImageCount <= 0)
     {
-      if (NILP (specified_data))
-       image_error ("Error reading `%s'", img->spec);
+#if HAVE_GIFERRORSTRING
+      const char *errstr = GifErrorString (gif->Error);
+      if (errstr)
+       if (NILP (specified_data))
+         image_error ("Error reading `%s' (%s)", img->spec,
+                      build_string (errstr));
+       else
+         image_error ("Error reading GIF data: %s",
+                      build_string (errstr));
       else
-       image_error ("Error reading GIF data");
+#endif
+       if (NILP (specified_data))
+         image_error ("Error reading `%s'", img->spec);
+       else
+         image_error ("Error reading GIF data");
       goto gif_error;
     }