busybox/shell/cttyhack.c

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2
 *
 * Copyright (c) 2007 Denys Vlasenko <vda.linux@googlemail.com>
 */
#include "libbb.h"

/* From <linux/vt.h> */
struct vt_stat {
	unsigned short v_active;        /* active vt */
	unsigned short v_signal;        /* signal to send */
	unsigned short v_state;         /* vt bitmask */
};
enum { VT_GETSTATE = 0x5603 }; /* get global vt state info */

/* From <linux/serial.h> */
struct serial_struct {
	int	type;
	int	line;
	unsigned int	port;
	int	irq;
	int	flags;
	int	xmit_fifo_size;
	int	custom_divisor;
	int	baud_base;
	unsigned short	close_delay;
	char	io_type;
	char	reserved_char[1];
	int	hub6;
	unsigned short	closing_wait;   /* time to wait before closing */
	unsigned short	closing_wait2;  /* no longer used... */
	unsigned char	*iomem_base;
	unsigned short	iomem_reg_shift;
	unsigned int	port_high;
	unsigned long	iomap_base;	/* cookie passed into ioremap */
	int	reserved[1];
};

int cttyhack_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int cttyhack_main(int argc UNUSED_PARAM, char **argv)
{
	int fd;
	char console[sizeof(int)*3 + 16];
	union {
		struct vt_stat vt;
		struct serial_struct sr;
		char paranoia[sizeof(struct serial_struct) * 3];
	} u;

	if (!*++argv) {
		bb_show_usage();
	}

	strcpy(console, "/dev/tty");
	if (ioctl(0, TIOCGSERIAL, &u.sr) == 0) {
		/* this is a serial console */
		sprintf(console + 8, "S%d", u.sr.line);
	} else if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
		/* this is linux virtual tty */
		sprintf(console + 8, "S%d" + 1, u.vt.v_active);
	}

	if (console[8]) {
		fd = xopen(console, O_RDWR);
		//bb_error_msg("switching to '%s'", console);
		dup2(fd, 0);
		dup2(fd, 1);
		dup2(fd, 2);
		while (fd > 2) close(fd--);
		/* Some other session may have it as ctty. Steal it from them */
		ioctl(0, TIOCSCTTY, 1);
	}

	BB_EXECVP(argv[0], argv);
	bb_perror_msg_and_die("can't execute '%s'", argv[0]);
}
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("can't execute '%s'", argv[0]);
77	}