Set a flag property on the root window to say if the X server VT is active

An X11 client may need to know whether the X server virtual terminal is
currently the active one.  This change adds a root window property which
provides that information.  Intended interface user: the VirtualBox Guest
Additions.

Signed-off-by: Michael Thayer <michael.thayer@oracle.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

hw/xfree86/common/xf86Events.c

@@ -56,6 +56,7 @@
 #include <X11/X.h>
 #include <X11/Xpoll.h>
 #include <X11/Xproto.h>
+#include <X11/Xatom.h>
 #include "misc.h"
 #include "compiler.h"
 #include "xf86.h"
@@ -431,6 +432,29 @@ xf86EnableInputDeviceForVTSwitch(InputInfoPtr pInfo)
     pInfo->flags &= ~XI86_DEVICE_DISABLED;
 }
 
+/*
+ * xf86UpdateHasVTProperty --
+ *    Update a flag property on the root window to say whether the server VT
+ *    is currently the active one as some clients need to know this.
+ */
+static void
+xf86UpdateHasVTProperty(Bool hasVT)
+{
+    Atom property_name;
+    int32_t value = hasVT ? 1 : 0;
+    int i;
+
+    property_name = MakeAtom(HAS_VT_ATOM_NAME, sizeof(HAS_VT_ATOM_NAME) - 1,
+                             FALSE);
+    if (property_name == BAD_RESOURCE)
+        FatalError("Failed to retrieve \"HAS_VT\" atom\n");
+    for (i = 0; i < xf86NumScreens; i++) {
+        ChangeWindowProperty(xf86ScrnToScreen(xf86Screens[i])->root,
+                             property_name, XA_INTEGER, 32,
+                             PropModeReplace, 1, &value, TRUE);
+    }
+}
+
 void
 xf86VTLeave(void)
 {
@@ -490,6 +514,8 @@ xf86VTLeave(void)
     if (xorgHWAccess)
         xf86DisableIO();
 
+    xf86UpdateHasVTProperty(FALSE);
+
     return;
 
 switch_failed:
@@ -574,6 +600,8 @@ xf86VTEnter(void)
     xf86platformVTProbe();
 #endif
 
+    xf86UpdateHasVTProperty(TRUE);
+
     OsReleaseSIGIO();
 }
 

hw/xfree86/common/xf86Init.c

@@ -387,6 +387,11 @@ InstallSignalHandlers(void)
     }
 }
 
+/* The memory storing the initial value of the XFree86_has_VT root window
+ * property.  This has to remain available until server start-up, so we just
+ * use a global. */
+static CARD32 HasVTValue = 1;
+
 /*
  * InitOutput --
  *	Initialize screenInfo for all actually accessible framebuffers.
@@ -731,7 +736,9 @@ InitOutput(ScreenInfo * pScreenInfo, int argc, char **argv)
         if (xf86Info.vtno >= 0) {
 #define VT_ATOM_NAME         "XFree86_VT"
             Atom VTAtom = -1;
+            Atom HasVTAtom = -1;
             CARD32 *VT = NULL;
+            CARD32 *HasVT = &HasVTValue;
             int ret;
 
             /* This memory needs to stay available until the screen has been
@@ -744,6 +751,8 @@ InitOutput(ScreenInfo * pScreenInfo, int argc, char **argv)
             *VT = xf86Info.vtno;
 
             VTAtom = MakeAtom(VT_ATOM_NAME, sizeof(VT_ATOM_NAME) - 1, TRUE);
+            HasVTAtom = MakeAtom(HAS_VT_ATOM_NAME,
+                                 sizeof(HAS_VT_ATOM_NAME) - 1, TRUE);
 
             for (i = 0, ret = Success; i < xf86NumScreens && ret == Success;
                  i++) {
@@ -751,9 +760,14 @@ InitOutput(ScreenInfo * pScreenInfo, int argc, char **argv)
                     xf86RegisterRootWindowProperty(xf86Screens[i]->scrnIndex,
                                                    VTAtom, XA_INTEGER, 32, 1,
                                                    VT);
+                if (ret == Success)
+                    ret = xf86RegisterRootWindowProperty(xf86Screens[i]
+                                                             ->scrnIndex,
+                                                         HasVTAtom, XA_INTEGER,
+                                                         32, 1, HasVT);
                 if (ret != Success)
                     xf86DrvMsg(xf86Screens[i]->scrnIndex, X_WARNING,
-                               "Failed to register VT property\n");
+                               "Failed to register VT properties\n");
             }
         }
 

hw/xfree86/common/xf86Privstr.h

@@ -163,4 +163,8 @@ typedef struct _RootWinProp {
 #define WSCONS		  32
 #endif
 
+/* Root window property to tell clients whether our VT is currently active.
+ * Name chosen to match the "XFree86_VT" property. */
+#define HAS_VT_ATOM_NAME "XFree86_has_VT"
+
 #endif                          /* _XF86PRIVSTR_H */