busybox/console-tools/fgconsole.c
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   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Mini fgconsole implementation for busybox
   4 *
   5 * Copyright (C) 2010 by Grigory Batalov <bga@altlinux.org>
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 */
   9//config:config FGCONSOLE
  10//config:       bool "fgconsole (1.5 kb)"
  11//config:       default y
  12//config:       select PLATFORM_LINUX
  13//config:       help
  14//config:       This program prints active (foreground) console number.
  15
  16//applet:IF_FGCONSOLE(APPLET_NOEXEC(fgconsole, fgconsole, BB_DIR_USR_BIN, BB_SUID_DROP, fgconsole))
  17
  18//kbuild:lib-$(CONFIG_FGCONSOLE) += fgconsole.o
  19
  20//usage:#define fgconsole_trivial_usage
  21//usage:        ""
  22//usage:#define fgconsole_full_usage "\n\n"
  23//usage:        "Get active console"
  24
  25#include "libbb.h"
  26
  27/* From <linux/vt.h> */
  28struct vt_stat {
  29        unsigned short v_active;        /* active vt */
  30        unsigned short v_signal;        /* signal to send */
  31        unsigned short v_state;         /* vt bitmask */
  32};
  33enum { VT_GETSTATE = 0x5603 }; /* get global vt state info */
  34
  35int fgconsole_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  36int fgconsole_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
  37{
  38        struct vt_stat vtstat;
  39
  40        vtstat.v_active = 0;
  41        xioctl(get_console_fd_or_die(), VT_GETSTATE, &vtstat);
  42        printf("%d\n", vtstat.v_active);
  43
  44        return EXIT_SUCCESS;
  45}
  46