From 13848969f4250d43a01f8bc973508da2d2abccfa Mon Sep 17 00:00:00 2001
From: Benjamin Otte <otte@redhat.com>
Date: Sun, 22 Oct 2023 15:59:02 +0200
Subject: [PATCH] dmabuf: Allow downloaders to fail initialization

When adding the formats of a downloader, allow them to return FALSE to
mean "This method is not supported", which is a useful way to opt out
when checking GL or Vulkan extensions and finding out that the desired
one isn't supported.
---
 gdk/gdkdisplay.c       | 3 ++-
 gdk/gdkdmabuf.c        | 4 +++-
 gdk/gdkdmabufprivate.h | 2 +-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/gdk/gdkdisplay.c b/gdk/gdkdisplay.c
index 1bfc2d2a8a..5a3fe7aae8 100644
--- a/gdk/gdkdisplay.c
+++ b/gdk/gdkdisplay.c
@@ -1847,7 +1847,8 @@ gdk_display_add_dmabuf_downloader (GdkDisplay                *display,
 {
   gsize i;
 
-  downloader->add_formats (downloader, display, builder);
+  if (!downloader->add_formats (downloader, display, builder))
+    return;
 
   /* dmabuf_downloaders is NULL-terminated */
   for (i = 0; i < G_N_ELEMENTS (display->dmabuf_downloaders) - 1; i++)
diff --git a/gdk/gdkdmabuf.c b/gdk/gdkdmabuf.c
index be723e4914..28c535df2f 100644
--- a/gdk/gdkdmabuf.c
+++ b/gdk/gdkdmabuf.c
@@ -264,7 +264,7 @@ get_drm_format_info (guint32 fourcc)
   return NULL;
 }
 
-static void
+static gboolean
 gdk_dmabuf_direct_downloader_add_formats (const GdkDmabufDownloader *downloader,
                                           GdkDisplay                *display,
                                           GdkDmabufFormatsBuilder   *builder)
@@ -277,6 +277,8 @@ gdk_dmabuf_direct_downloader_add_formats (const GdkDmabufDownloader *downloader,
                                              supported_formats[i].fourcc,
                                              DRM_FORMAT_MOD_LINEAR);
     }
+
+  return TRUE;
 }
 
 static gboolean
diff --git a/gdk/gdkdmabufprivate.h b/gdk/gdkdmabufprivate.h
index 5bca5e16b1..36af9fe734 100644
--- a/gdk/gdkdmabufprivate.h
+++ b/gdk/gdkdmabufprivate.h
@@ -22,7 +22,7 @@ struct _GdkDmabuf
 struct _GdkDmabufDownloader
 {
   const char *name;
-  void                  (* add_formats)                         (const GdkDmabufDownloader      *downloader,
+  gboolean              (* add_formats)                         (const GdkDmabufDownloader      *downloader,
                                                                  GdkDisplay                     *display,
                                                                  GdkDmabufFormatsBuilder        *builder);