123 lines
3.3 KiB
C
123 lines
3.3 KiB
C
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/* Copyright (c) R. Cohen-Scali, 1998. */
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/*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose and without fee is hereby granted,
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* provided that the above copyright notice appear in all copies and that
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* both that copyright notice and this permission notice appear in
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* supporting documentation.
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*
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* This file is provided AS IS with no warranties of any kind. The author
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* shall have no liability with respect to the infringement of copyrights,
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* trade secrets or any patents by this file or any part thereof. In no
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* event will the author be liable for any lost revenue or profits or
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* other special, indirect and consequential damages.
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*
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* <remi.cohenscali@pobox.com>
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*/
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <linux/vt.h>
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#define CONSOLE "/dev/console"
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static char *progname = NULL;
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static char errmsg[1024];
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static void usage( int verb )
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{
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fprintf( stderr, "%s: usage: %s [-h] <on/off>\n", progname, progname );
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if ( verb )
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{
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fprintf( stderr, " Allows to enable/disable to VT switching ability\n" );
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fprintf( stderr, " -- %s on -- enable VT switching\n", progname );
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fprintf( stderr, " -- %s off -- disable VT switching\n", progname );
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fprintf( stderr, " Option -h display this message\n" );
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}
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fprintf( stderr, "\n", progname, progname );
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}
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main( int argc, char **argv )
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{
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char *cmd = argv[1];
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int allow = 0, consfd = -1;
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uid_t uid = -1;
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struct stat consstat;
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/* Program name */
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progname =( progname = strrchr( argv[0], '/' ) ) ? progname +1 : argv[0];
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/* Check args */
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if ( argc != 2 && argc != 3 )
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{
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usage( 0 );
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exit( 1 );
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}
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/* Process -h */
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if ( !strcmp( cmd, "-h" ) || !strcmp( cmd, "--help" ) )
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{
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usage( 1 );
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cmd = argv[2];
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if ( argc == 2 ) exit( 0 );
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}
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/* Process on/off (case insensitive) */
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if ( strcasecmp( cmd, "on" ) && strcasecmp( cmd, "off" ) )
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{
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usage( 0 );
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exit( 1 );
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}
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allow = !strcasecmp( cmd, "on" );
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/* Check user is allowed to do it */
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uid = getuid();
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if ( stat( CONSOLE, &consstat ) == -1 )
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{
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sprintf( errmsg, "%s: Cannot stat " CONSOLE, progname );
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perror( errmsg );
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exit( 1 );
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}
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if ( uid != consstat.st_uid )
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{
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fprintf(stderr,
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"%s: Sorry, you are not allowed to %slock"
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" VT switching: Operation not permitted\n",
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progname,
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allow ? "un" : "" );
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exit( 1 );
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}
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seteuid( 0 );
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/* Open console */
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if ( ( consfd = open( CONSOLE, O_RDWR ) ) == -1 )
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{
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sprintf( errmsg, "%s: Cannot open " CONSOLE, progname );
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perror( errmsg );
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seteuid( uid );
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exit( 1 );
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}
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/* Do it */
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if ( ioctl( consfd, allow?VT_UNLOCKSWITCH:VT_LOCKSWITCH ) == -1 )
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{
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sprintf( errmsg, "%s: Cannot %slock VT switching for " CONSOLE, progname, allow ? "un" : "" );
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perror( errmsg );
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seteuid( uid );
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exit( 1 );
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}
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/* Terminate */
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close( consfd );
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fprintf( stdout, "VT switching %s\n", allow ? "enabled" : "disabled" );
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seteuid( uid );
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exit( 0 );
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}
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