path: root/daemon/server.c

/* GDM - The Gnome Display Manager
 * Copyright (C) 1998, 1999 Martin Kasper Petersen <mkp@SunSITE.auc.dk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/* This file contains functions for controlling local X servers */

#include <config.h>
#include <gnome.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <strings.h>
#include <signal.h>
#include <errno.h>
#include <X11/Xlib.h>

#include "gdm.h"

static const gchar RCSid[]="$Id$";

extern gchar *GdmDisplayInit;
extern gchar *GdmAuthDir;
extern gchar *GdmLogDir;
extern gint  GdmXdmcp;

extern gchar **gdm_arg_munch(const gchar *p);
extern void gdm_auth_secure_display(GdmDisplay *);
extern void gdm_debug(const gchar *, ...);
extern void gdm_error(const gchar *, ...);
extern gint gdm_display_manage(GdmDisplay *);
extern void gdm_putenv(gchar *);
extern void gdm_xdmcp_close();

void gdm_server_start(GdmDisplay *d);
void gdm_server_stop(GdmDisplay *d);
void gdm_server_restart(GdmDisplay *d);
void gdm_server_usr1_handler(gint);
void gdm_server_alarm_handler(gint);
GdmDisplay *gdm_server_alloc (gint id, gchar *command);


GdmDisplay *d;
sigset_t mask, omask;


void
gdm_server_start(GdmDisplay *disp)
{
    struct sigaction usr1;
    sigset_t usr1mask;
    gchar *srvcmd=NULL;
    gchar **argv=NULL;
    int logfd;
    
    d=disp;

    gdm_debug("gdm_server_start: %s", d->name);

    /* Catch USR1 from X server */
    usr1.sa_handler = gdm_server_usr1_handler;
    usr1.sa_flags = SA_RESTART|SA_RESETHAND;
    sigemptyset(&usr1.sa_mask);

    if(sigaction(SIGUSR1, &usr1, NULL) < 0) {
        gdm_error(_("gdm_server_start: Error setting up USR1 signal handler"));
	exit(SERVER_ABORT);
    }

    sigemptyset(&usr1mask);
    sigaddset(&usr1mask, SIGUSR1);
    sigprocmask(SIG_UNBLOCK, &usr1mask, NULL);

    /* Log all output from spawned programs to a file */
    logfd=open(g_strconcat(GdmLogDir, "/", d->name, ".log", NULL),
	       O_CREAT|O_TRUNC|O_APPEND|O_WRONLY, 0666);
    
    if(logfd != -1) {
	dup2(logfd, 1);
	dup2(logfd, 2);
    }
    else
	gdm_error(_("gdm_server_start: Could not open logfile for display %s!"), d->name);

    /* Just in case we have an old server hanging around */
    if(d->servpid) {
	gdm_debug("gdm_server_start: Old server found (%d). Killing.", d->servpid);
	gdm_server_stop(d);
    }

    /* Secure display with cookie */
    gdm_auth_secure_display(d);
    gdm_putenv(g_strconcat("XAUTHORITY=", d->auth, NULL));
    gdm_putenv(g_strconcat("DISPLAY=", d->name, NULL));

    /* Fork into two processes. Parent remains the gdm slave
     * process. Child becomes the X server.
     */

    switch(d->servpid=fork()) {
	
    case 0:
	/* Close the XDMCP fd inherited by the daemon process */
	if(GdmXdmcp)
	    gdm_xdmcp_close();

	/* The X server expects USR1 to be SIG_IGN */
	usr1.sa_handler = SIG_IGN;
	usr1.sa_flags = SA_RESTART;
	sigemptyset(&usr1.sa_mask);

	if(sigaction(SIGUSR1, &usr1, NULL) < 0) {
	    gdm_error(_("gdm_server_start: Error setting USR1 to SIG_IGN"));
	    exit(SERVER_ABORT);
	}
	
	srvcmd=g_strconcat(d->command, " -auth ", GdmAuthDir, \
			      "/", d->name, ".xauth ", 
			      d->name, NULL);

	gdm_debug("gdm_server_start: '%s'", srvcmd);
	
	argv=gdm_arg_munch(srvcmd);
	g_free(srvcmd);

	setpgid(0, 0);

	execv(argv[0], argv);

	gdm_error(_("gdm_server_start: Xserver not found: %s"), d->command);

	exit(SERVER_ABORT);
	break;
	
    case -1:
	gdm_error(_("gdm_server_start: Can't fork Xserver process!"));
	d->servpid=0;
	break;
	
    default:
	break;
    }

    d->servstat=SERVER_STARTED;

    /* Wait for X server to send ready signal */
    pause();
}


void
gdm_server_stop(GdmDisplay *d)
{
    gdm_debug("gdm_server_stop: Server for %s going down!", d->name);

    kill(d->servpid, SIGTERM);
    waitpid(d->servpid, 0, 0);
    d->servpid=0;
    d->servstat=SERVER_DEAD;

    if(unlink(d->auth) == -1)
	gdm_error(_("gdm_server_stop: Could not unlink auth file: %s!"), strerror(errno));
}


/* FIXME: We have a race here. What if USR1 is delivered before we enable the handler? 
 * This only succeeds because the X server takes ages to shut down...
 * Maybe we should jump directly to display_manage and bail out on error?
 * Needs thinking for sure...
 */

void
gdm_server_restart(GdmDisplay *d)
{
    sigset_t usr1mask;
    struct sigaction usr1, sigalarm;

    gdm_debug("gdm_server_restart: Server for %s restarting!", d->name);

    if(d->servpid && kill(d->servpid, 0)<0) {
	gdm_debug("gdm_server_restart: Old server for %s still alive. Killing!", d->name);
	gdm_server_stop(d);
	gdm_server_start(d);
    }

    /* Create new cookie */
    gdm_auth_secure_display(d);
    gdm_putenv(g_strconcat("XAUTHORITY=", d->auth, NULL));
    gdm_putenv(g_strconcat("DISPLAY=", d->name, NULL));

    /* Catch USR1 from X server */
    usr1.sa_handler = gdm_server_usr1_handler;
    usr1.sa_flags = SA_RESTART|SA_RESETHAND;
    sigemptyset(&usr1.sa_mask);

    if(sigaction(SIGUSR1, &usr1, NULL) < 0) {
        gdm_error(_("gdm_server_start: Error setting up USR1 signal handler"));
	exit(SERVER_ABORT);
    }

    sigemptyset(&usr1mask);
    sigaddset(&usr1mask, SIGUSR1);
    sigprocmask(SIG_UNBLOCK, &usr1mask, NULL);

    /* Reset X and force auth file reread. XCloseDisplay works on most servers but we play it safe */
    gdm_debug("gdm_server_restart: Servpid=%d", d->servpid);
    kill(d->servpid, SIGHUP);

    d->servstat=SERVER_STARTED;

    /* We add a timeout in case the X server fails to start.  This
     * might happen because X servers take a while to die, close their
     * sockets etc. If the old X server isn't completely dead, the new
     * one will fail and we'll hang here forever */

    sigalarm.sa_handler = gdm_server_alarm_handler;
    sigalarm.sa_flags = 0;
    sigemptyset(&sigalarm.sa_mask);
    
    if(sigaction(SIGALRM, &sigalarm, NULL) < 0) {
	gdm_error(_("gdm_server_restart: Error setting up ALARM signal handler"));
	return;
    }

    sigemptyset(&mask);
    sigaddset(&mask, SIGALRM);
    sigprocmask(SIG_UNBLOCK, &mask, &omask);

    alarm(10);

    /* Wait for X server to send ready signal */
    pause();
}


void 
gdm_server_alarm_handler(gint signal)
{
   /* Unset alarm and try again */
    alarm(0);
    sigprocmask(SIG_SETMASK, &omask, NULL); 

    waitpid(d->servpid, 0, WNOHANG);

    gdm_debug("gdm_server_alarm_handler: Temporary server failure");
    gdm_server_restart(d);
}


void
gdm_server_usr1_handler(gint sig)
{
    sigset_t usr1mask;

    /* Unset alarm */
    alarm(0);
    sigprocmask(SIG_SETMASK, &omask, NULL);
    
    gdm_debug("gdm_server_usr1_handler: Starting display %s!", d->name);

    d->servstat=SERVER_RUNNING;

    /* Block USR1 */
    sigemptyset(&usr1mask);
    sigaddset(&usr1mask, SIGUSR1);
    sigprocmask(SIG_BLOCK, &usr1mask, NULL);

    gdm_display_manage(d);
}


GdmDisplay * 
gdm_server_alloc (gint id, gchar *command)
{
    gchar dname[1024];

    GdmDisplay *d = g_malloc(sizeof(GdmDisplay));

    sprintf(dname, ":%d", id);    
    d->auth = NULL;
    d->command = g_strdup(command);
    d->cookie = NULL;
    d->dispstat = DISPLAY_DEAD;
    d->greetpid = 0;
    d->id = id;
    d->name = strdup(dname);
    d->servpid = 0;
    d->servstat = SERVER_DEAD;
    d->sessionid = 0;
    d->sesspid = 0;
    d->slavepid = 0;
    d->type = DISPLAY_LOCAL;
    d->sessionid = 0;
    d->acctime = 0;
    d->dsp = NULL;

    return (d);
}

		
/* EOF */