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xdmshell.c

/* $Xorg: xdmshell.c,v 1.4 2001/02/09 02:05:41 xorgcvs Exp $ */
/*
 * xdmshell - simple program for running xdm from login
 *
 * 
Copyright 1988, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of The Open Group shall not be
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in this Software without prior written authorization from The Open Group.
 * *
 * Author:  Jim Fulton, MIT X Consortium
 *
 * This program should probably be setuid to root.  On the macII, it must be
 * run from the console so that getty doesn't get confused about zero-length
 * reads.
 *
 * WARNING:  Make sure that you tailor your Xresources file to have a
 * way of invoking the abort-display() action.  Otherwise, you won't be able
 * bring down X when you are finished.
 */

/* $XFree86: xc/programs/xdm/xdmshell.c,v 3.6 2001/07/25 15:05:19 dawes Exp $ */

#include <stdio.h>
#include "dm.h"
#include <errno.h>

#ifdef macII
#define ON_CONSOLE_ONLY
#endif

#ifdef ON_CONSOLE_ONLY
#include <sys/ioctl.h>
#endif

#ifndef BINDIR
#define BINDIR "/usr/bin/X11"
#endif

/*
 * HP-UX does have vfork, but A/UX doesn't
 */
#ifdef HAVE_WORKING_VFORK /* autoconf's preferred name */
# define HAS_VFORK
#endif

#ifndef HAS_VFORK
#define vfork() fork()
#endif

char *ProgramName;

static int exec_args (
    char *filename,
    char **args)
{
    int pid;
    waitType status;

    if (!filename) return -1;

    if (filename[0] != '/') {
      fprintf (stderr, 
             "%s:  attempt to execute program with relative pathname:  %s\n",
             ProgramName, filename);
      return -1;
    }

    if (access (filename, X_OK) != 0) return -1;

    switch (pid = vfork ()) {
      case -1:                                  /* error */
      return -1;
      case 0:                             /* child */
      execv (filename, args);
      _exit (1);
      /* NOTREACHED */
      default:                                  /* parent */
      while (wait (&status) != pid) ;
    }
    return waitCode (status);
}

#if defined(macII) || defined(sun)
static int exec_one_arg (
    char    *filename,
    char    *arg)
{
    char    *argv[3];

    argv[0] = filename;
    argv[1] = arg;
    argv[2] = NULL;
    return exec_args (filename, argv);
}
#endif

int
main (
    int argc,
    char *argv[])
{
    int ttyfd;
    char cmdbuf[256];
    char *args[10];
#ifdef ON_CONSOLE_ONLY
    int consfd;
    int ttypgrp, conspgrp;
    char *ttyName;
    extern char *ttyname();
#endif

    ProgramName = argv[0];

    if (argc > 1) {
      fprintf (stderr, "usage:  %s\r\n", ProgramName);
      exit (1);
    }

    ttyfd = open ("/dev/tty", O_RDWR, 0);
    if (ttyfd < 3) {                /* stdin = 0, stdout = 1, stderr = 2 */
      fprintf (stderr, 
             "%s:  must be run directly from the console.\r\n",
             ProgramName);
      exit (1);
    }
#ifdef ON_CONSOLE_ONLY
    if (ioctl (ttyfd, TIOCGPGRP, (char *)&ttypgrp) != 0) {
      fprintf (stderr, "%s:  unable to get process group of /dev/tty\r\n",
             ProgramName);
      (void) close (ttyfd);
      exit (1);
    }
#endif
    (void) close (ttyfd);
    
#ifdef ON_CONSOLE_ONLY
    ttyName = ttyname (0);
    if (!ttyName || strcmp (ttyName, "/dev/console") != 0) {
      fprintf (stderr, "%s:  must login on /dev/console instead of %s\r\n",
             ProgramName, ttyName ? ttyName : "non-terminal device");
      exit (1);
    }

    consfd = open ("/dev/console", O_RDWR, 0);
    if (consfd < 3) {               /* stdin = 0, stdout = 1, stderr = 2 */
      fprintf (stderr, "%s:  unable to open /dev/console\r\n",
             ProgramName);
      exit (1);
    }

    if (ioctl (consfd, TIOCGPGRP, (char *)&conspgrp) != 0) {
      fprintf (stderr,
             "%s:  unable to get process group of /dev/console\r\n",
             ProgramName);
      (void) close (consfd);
      exit (1);
    }
    (void) close (consfd);

    if (ttypgrp != conspgrp) {
      fprintf (stderr, "%s:  must be run from /dev/console\r\n", 
             ProgramName);
      exit (1);
    }
#endif

    /* make xdm run in a non-setuid environment */
    setuid (geteuid());

    /*
     * exec /usr/bin/X11/xdm -nodaemon -udpPort 0
     */
    strcpy (cmdbuf, BINDIR);
    strcat (cmdbuf, "/xdm");
    args[0] = cmdbuf;
    args[1] = "-nodaemon";
    args[2] = "-udpPort";
    args[3] = "0";
    args[4] = NULL;
    if (exec_args (cmdbuf, args) == -1) {
      fprintf (stderr, "%s:  unable to execute %s (error %d, %s)\r\n",
             ProgramName, cmdbuf, errno, strerror(errno));
      exit (1);
    }

#ifdef macII
    strcpy (cmdbuf, BINDIR);
    strcat (cmdbuf, "/Xrepair");
    (void) exec_one_arg (cmdbuf, NULL);
    (void) exec_one_arg ("/usr/bin/screenrestore", NULL);
#endif

#ifdef sun
    strcpy (cmdbuf, BINDIR);
    strcat (cmdbuf, "/kbd_mode");
    (void) exec_one_arg (cmdbuf, "-a");
#endif

    exit (0);
    /*NOTREACHED*/
}


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