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/* Copyright (c) R. Cohen-Scali, 1998. */
/*
* 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.
*
* This file is provided AS IS with no warranties of any kind. The author
* shall have no liability with respect to the infringement of copyrights,
* trade secrets or any patents by this file or any part thereof. In no
* event will the author be liable for any lost revenue or profits or
* other special, indirect and consequential damages.
*
* <remi.cohenscali@pobox.com>
*/
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/vt.h>
#define CONSOLE "/dev/console"
static char *progname = NULL;
static char errmsg[1024];
static void usage( int verb )
{
fprintf( stderr, "%s: usage: %s [-h] <on/off>\n", progname, progname );
if ( verb )
{
fprintf( stderr, " Allows to enable/disable to VT switching ability\n" );
fprintf( stderr, " -- %s on -- enable VT switching\n", progname );
fprintf( stderr, " -- %s off -- disable VT switching\n", progname );
fprintf( stderr, " Option -h display this message\n" );
}
fprintf( stderr, "\n", progname, progname );
}
main( int argc, char **argv )
{
char *cmd = argv[1];
int allow = 0, consfd = -1;
uid_t uid = -1;
struct stat consstat;
/* Program name */
progname =( progname = strrchr( argv[0], '/' ) ) ? progname +1 : argv[0];
/* Check args */
if ( argc != 2 && argc != 3 )
{
usage( 0 );
exit( 1 );
}
/* Process -h */
if ( !strcmp( cmd, "-h" ) || !strcmp( cmd, "--help" ) )
{
usage( 1 );
cmd = argv[2];
if ( argc == 2 ) exit( 0 );
}
/* Process on/off (case insensitive) */
if ( strcasecmp( cmd, "on" ) && strcasecmp( cmd, "off" ) )
{
usage( 0 );
exit( 1 );
}
allow = !strcasecmp( cmd, "on" );
/* Check user is allowed to do it */
uid = getuid();
if ( stat( CONSOLE, &consstat ) == -1 )
{
sprintf( errmsg, "%s: Cannot stat " CONSOLE, progname );
perror( errmsg );
exit( 1 );
}
if ( uid != consstat.st_uid )
{
fprintf(stderr,
"%s: Sorry, you are not allowed to %slock"
" VT switching: Operation not permitted\n",
progname,
allow ? "un" : "" );
exit( 1 );
}
seteuid( 0 );
/* Open console */
if ( ( consfd = open( CONSOLE, O_RDWR ) ) == -1 )
{
sprintf( errmsg, "%s: Cannot open " CONSOLE, progname );
perror( errmsg );
seteuid( uid );
exit( 1 );
}
/* Do it */
if ( ioctl( consfd, allow?VT_UNLOCKSWITCH:VT_LOCKSWITCH ) == -1 )
{
sprintf( errmsg, "%s: Cannot %slock VT switching for " CONSOLE, progname, allow ? "un" : "" );
perror( errmsg );
seteuid( uid );
exit( 1 );
}
/* Terminate */
close( consfd );
fprintf( stdout, "VT switching %s\n", allow ? "enabled" : "disabled" );
seteuid( uid );
exit( 0 );
}
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