release/src/router/busybox/shell/cttyhack.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Licensed under GPLv2
   4  *
   5  * Copyright (c) 2007 Denys Vlasenko <vda.linux@googlemail.com>
   6  */
   7 #include "libbb.h"
   8
   9 /* From <linux/vt.h> */
  10 struct vt_stat {
  11         unsigned short v_active;        /* active vt */
  12         unsigned short v_signal;        /* signal to send */
  13         unsigned short v_state;         /* vt bitmask */
  14 };
  15 enum { VT_GETSTATE = 0x5603 }; /* get global vt state info */
  16
  17 /* From <linux/serial.h> */
  18 struct serial_struct {
  19         int     type;
  20         int     line;
  21         unsigned int    port;
  22         int     irq;
  23         int     flags;
  24         int     xmit_fifo_size;
  25         int     custom_divisor;
  26         int     baud_base;
  27         unsigned short  close_delay;
  28         char    io_type;
  29         char    reserved_char[1];
  30         int     hub6;
  31         unsigned short  closing_wait;   /* time to wait before closing */
  32         unsigned short  closing_wait2;  /* no longer used... */
  33         unsigned char   *iomem_base;
  34         unsigned short  iomem_reg_shift;
  35         unsigned int    port_high;
  36         unsigned long   iomap_base;     /* cookie passed into ioremap */
  37         int     reserved[1];
  38 };
  39
  40 int cttyhack_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  41 int cttyhack_main(int argc UNUSED_PARAM, char **argv)
  42 {
  43         int fd;
  44         char console[sizeof(int)*3 + 16];
  45         union {
  46                 struct vt_stat vt;
  47                 struct serial_struct sr;
  48                 char paranoia[sizeof(struct serial_struct) * 3];
  49         } u;
  50
  51         if (!*++argv) {
  52                 bb_show_usage();
  53         }
  54
  55         strcpy(console, "/dev/tty");
  56         if (ioctl(0, TIOCGSERIAL, &u.sr) == 0) {
  57                 /* this is a serial console */
  58                 sprintf(console + 8, "S%d", u.sr.line);
  59         } else if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
  60                 /* this is linux virtual tty */
  61                 sprintf(console + 8, "S%d" + 1, u.vt.v_active);
  62         }
  63
  64         if (console[8]) {
  65                 fd = xopen(console, O_RDWR);
  66                 //bb_error_msg("switching to '%s'", console);
  67                 dup2(fd, 0);
  68                 dup2(fd, 1);
  69                 dup2(fd, 2);
  70                 while (fd > 2) close(fd--);
  71                 /* Some other session may have it as ctty. Steal it from them */
  72                 ioctl(0, TIOCSCTTY, 1);
  73         }
  74
  75         BB_EXECVP(argv[0], argv);
  76         bb_perror_msg_and_die("cannot exec '%s'", argv[0]);
  77 }