From 35e0982e35bd98f6f318e4ef5342c21f5701c1ac Mon Sep 17 00:00:00 2001
From: "Jasper St. Pierre" <jstpierre@mecheye.net>
Date: Tue, 19 Aug 2014 11:02:33 -0400
Subject: [PATCH] xrandr: Port some checks to XCB so we don't have to deal with
 BadName

RandR's QueryOutputProperty request makes the incredible decision of
throwing a BadName if you pass a property that doesn't exist, which
means that trying to check if a property exists is a royal pain when
using Xlib.

XCB's interface is much more friendly about errors and not having global
state and things like that, so use that instead to query our backlight
property.
---
 configure.ac                                  |  1 +
 .../x11/meta-monitor-manager-xrandr.c         | 32 +++++++++++--------
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/configure.ac b/configure.ac
index 61f67e26a..4b2e0e388 100644
--- a/configure.ac
+++ b/configure.ac
@@ -87,6 +87,7 @@ MUTTER_PC_MODULES="
    xkbfile
    xkeyboard-config
    xkbcommon-x11
+   xcb-randr
 "
 
 GLIB_GSETTINGS
diff --git a/src/backends/x11/meta-monitor-manager-xrandr.c b/src/backends/x11/meta-monitor-manager-xrandr.c
index a751d6d92..d7729e1d8 100644
--- a/src/backends/x11/meta-monitor-manager-xrandr.c
+++ b/src/backends/x11/meta-monitor-manager-xrandr.c
@@ -35,6 +35,8 @@
 #include <X11/Xatom.h>
 #include <X11/extensions/Xrandr.h>
 #include <X11/extensions/dpms.h>
+#include <X11/Xlib-xcb.h>
+#include <xcb/randr.h>
 
 #include "meta-backend-x11.h"
 #include <meta/main.h>
@@ -214,30 +216,34 @@ output_get_backlight_limits_xrandr (MetaMonitorManagerXrandr *manager_xrandr,
                                     MetaOutput               *output)
 {
   Atom atom;
-  XRRPropertyInfo *info;
+  xcb_connection_t *xcb_conn;
+  xcb_randr_query_output_property_reply_t *reply;
 
   atom = XInternAtom (manager_xrandr->xdisplay, "Backlight", False);
-  info = XRRQueryOutputProperty (manager_xrandr->xdisplay,
-                                 (XID)output->winsys_id,
-                                 atom);
 
-  if (info == NULL)
-    {
-      meta_verbose ("could not get output property for %s\n", output->name);
-      return;
-    }
+  xcb_conn = XGetXCBConnection (manager_xrandr->xdisplay);
+  reply = xcb_randr_query_output_property_reply (xcb_conn,
+                                                 xcb_randr_query_output_property (xcb_conn,
+                                                                                  (xcb_randr_output_t) output->winsys_id,
+                                                                                  (xcb_atom_t) atom),
+                                                 NULL);
 
-  if (!info->range || info->num_values != 2)
+  /* This can happen on systems without backlights. */
+  if (reply == NULL)
+    return;
+
+  if (!reply->range || reply->length != 2)
     {
       meta_verbose ("backlight %s was not range\n", output->name);
       goto out;
     }
 
-  output->backlight_min = info->values[0];
-  output->backlight_max = info->values[1];
+  int32_t *values = xcb_randr_query_output_property_valid_values (reply);
+  output->backlight_min = values[0];
+  output->backlight_max = values[1];
 
 out:
-  XFree (info);
+  free (reply);
 }
 
 static int