loader/glx: move multibuffers check to loader

make this code more reusable

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30128>

src/loader/loader_dri3_helper.c

@@ -2414,3 +2414,73 @@ dri3_find_back_alloc(struct loader_dri3_drawable *draw)
 
    return back;
 }
+
+/* Only request versions of these protocols which we actually support. */
+#define DRI3_SUPPORTED_MAJOR 1
+#define PRESENT_SUPPORTED_MAJOR 1
+
+#ifdef HAVE_DRI3_MODIFIERS
+#define DRI3_SUPPORTED_MINOR 2
+#define PRESENT_SUPPORTED_MINOR 2
+#else
+#define PRESENT_SUPPORTED_MINOR 0
+#define DRI3_SUPPORTED_MINOR 0
+#endif
+
+bool
+loader_dri3_check_multibuffer(xcb_connection_t *c, bool *err)
+{
+   xcb_dri3_query_version_cookie_t      dri3_cookie;
+   xcb_dri3_query_version_reply_t       *dri3_reply;
+   xcb_present_query_version_cookie_t   present_cookie;
+   xcb_present_query_version_reply_t    *present_reply;
+   xcb_generic_error_t                  *error;
+   const xcb_query_extension_reply_t    *extension;
+
+   xcb_prefetch_extension_data(c, &xcb_dri3_id);
+   xcb_prefetch_extension_data(c, &xcb_present_id);
+
+   extension = xcb_get_extension_data(c, &xcb_dri3_id);
+   if (!(extension && extension->present))
+      goto error;
+
+   extension = xcb_get_extension_data(c, &xcb_present_id);
+   if (!(extension && extension->present))
+      goto error;
+
+   dri3_cookie = xcb_dri3_query_version(c,
+                                        DRI3_SUPPORTED_MAJOR,
+                                        DRI3_SUPPORTED_MINOR);
+   present_cookie = xcb_present_query_version(c,
+                                              PRESENT_SUPPORTED_MAJOR,
+                                              PRESENT_SUPPORTED_MINOR);
+
+   dri3_reply = xcb_dri3_query_version_reply(c, dri3_cookie, &error);
+   if (!dri3_reply) {
+      free(error);
+      goto error;
+   }
+
+   int dri3Major = dri3_reply->major_version;
+   int dri3Minor = dri3_reply->minor_version;
+   free(dri3_reply);
+
+   present_reply = xcb_present_query_version_reply(c, present_cookie, &error);
+   if (!present_reply) {
+      free(error);
+      goto error;
+   }
+   int presentMajor = present_reply->major_version;
+   int presentMinor = present_reply->minor_version;
+   free(present_reply);
+
+#ifdef HAVE_DRI3_MODIFIERS
+   if ((dri3Major > 1 || (dri3Major == 1 && dri3Minor >= 2)) &&
+       (presentMajor > 1 || (presentMajor == 1 && presentMinor >= 2)))
+      return true;
+#endif
+   return false;
+error:
+   *err = true;
+   return false;
+}

src/loader/loader_dri3_helper.h

@@ -297,4 +297,6 @@ loader_dri3_swapbuffer_barrier(struct loader_dri3_drawable *draw);
 void
 loader_dri3_close_screen(__DRIscreen *dri_screen);
 
+bool
+loader_dri3_check_multibuffer(xcb_connection_t *c, bool *err);
 #endif