source: trunk/athena/etc/xdm/xdm/reset.c @ 6052

/*
 * xdm - display manager daemon
 *
 * $XConsortium: reset.c,v 1.10 91/09/19 16:26:03 keith Exp $
 *
 * Copyright 1988 Massachusetts Institute of Technology
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose and without fee is hereby granted, provided
 * that the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  M.I.T. makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 * Author:  Keith Packard, MIT X Consortium
 */

/*
 * pseudoReset -- pretend to reset the server by killing all clients
 * with windows.  It will reset the server most of the time, unless
 * a client remains connected with no windows.
 */

# include       "dm.h"
# include       <X11/Xlib.h>
# include       <signal.h>

/*ARGSUSED*/
static int
ignoreErrors (dpy, event)
Display *dpy;
XErrorEvent     *event;
{
        Debug ("ignoring error\n");
}

/*
 * this is mostly bogus -- but quite useful.  I wish the protocol
 * had some way of enumerating and identifying clients, that way
 * this code wouldn't have to be this kludgy.
 */

static
killWindows (dpy, window)
Display *dpy;
Window  window;
{
        Window  root, parent, *children;
        int     child;
        unsigned int nchildren = 0;
        
        while (XQueryTree (dpy, window, &root, &parent, &children, &nchildren)
               && nchildren > 0)
        {
                for (child = 0; child < nchildren; child++) {
                        Debug ("XKillClient 0x%x\n", children[child]);
                        XKillClient (dpy, children[child]);
                }
                XFree ((char *)children);
        }
}

static Jmp_buf  resetJmp;

/* ARGSUSED */
static SIGVAL
abortReset (n)
    int n;
{
        Longjmp (resetJmp, 1);
}

/*
 * this display connection better not have any windows...
 */
 
pseudoReset (dpy)
Display *dpy;
{
        Window  root;
        int     screen;

        if (Setjmp (resetJmp)) {
                LogError ("pseudoReset timeout\n");
        } else {
                (void) Signal (SIGALRM, abortReset);
                (void) alarm (30);
                XSetErrorHandler (ignoreErrors);
                for (screen = 0; screen < ScreenCount (dpy); screen++) {
                        Debug ("pseudoReset screen %d\n", screen);
                        root = RootWindow (dpy, screen);
                        killWindows (dpy, root);
                }
                Debug ("before XSync\n");
                XSync (dpy, False);
                (void) alarm (0);
        }
        Signal (SIGALRM, SIG_DFL);
        XSetErrorHandler ((int (*)()) 0);
        Debug ("pseudoReset done\n");
}