busybox/libbb/get_console.c

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) many different people.  If you wrote this, please
 * acknowledge your work.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"

/* From <linux/kd.h> */
enum { KDGKBTYPE = 0x4B33 };  /* get keyboard type */

static int open_a_console(const char *fnam)
{
	int fd;

	/* try read-write */
	fd = open(fnam, O_RDWR);

	/* if failed, try read-only */
	if (fd < 0 && errno == EACCES)
		fd = open(fnam, O_RDONLY);

	/* if failed, try write-only */
	if (fd < 0 && errno == EACCES)
		fd = open(fnam, O_WRONLY);

	return fd;
}

/*
 * Get an fd for use with kbd/console ioctls.
 * We try several things because opening /dev/console will fail
 * if someone else used X (which does a chown on /dev/console).
 */
int FAST_FUNC get_console_fd_or_die(void)
{
	static const char *const console_names[] = {
		DEV_CONSOLE, CURRENT_VC, CURRENT_TTY
	};

	int fd;

	for (fd = 2; fd >= 0; fd--) {
		int fd4name;
		int choice_fd;
		char arg;

		fd4name = open_a_console(console_names[fd]);
 chk_std:
		choice_fd = (fd4name >= 0 ? fd4name : fd);

		arg = 0;
		if (ioctl(choice_fd, KDGKBTYPE, &arg) == 0)
			return choice_fd;
		if (fd4name >= 0) {
			close(fd4name);
			fd4name = -1;
			goto chk_std;
		}
	}

	bb_error_msg_and_die("can't open console");
	/*return fd; - total failure */
}

/* From <linux/vt.h> */
enum {
	VT_ACTIVATE = 0x5606,   /* make vt active */
	VT_WAITACTIVE = 0x5607  /* wait for vt active */
};

void FAST_FUNC console_make_active(int fd, const int vt_num)
{
	xioctl(fd, VT_ACTIVATE, (void *)(ptrdiff_t)vt_num);
	xioctl(fd, VT_WAITACTIVE, (void *)(ptrdiff_t)vt_num);
}
1	/* vi: set sw=4 ts=4: */
2	/*
3	* Utility routines.
4	*
5	* Copyright (C) many different people. If you wrote this, please
6	* acknowledge your work.
7	*
8	* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
9	*/
10
11	#include "libbb.h"
12
13	/* From <linux/kd.h> */
14	enum { KDGKBTYPE = 0x4B33 }; /* get keyboard type */
15
16	static int open_a_console(const char *fnam)
17	{
18	int fd;
19
20	/* try read-write */
21	fd = open(fnam, O_RDWR);
22
23	/* if failed, try read-only */
24	if (fd < 0 && errno == EACCES)
25	fd = open(fnam, O_RDONLY);
26
27	/* if failed, try write-only */
28	if (fd < 0 && errno == EACCES)
29	fd = open(fnam, O_WRONLY);
30
31	return fd;
32	}
33
34	/*
35	* Get an fd for use with kbd/console ioctls.
36	* We try several things because opening /dev/console will fail
37	* if someone else used X (which does a chown on /dev/console).
38	*/
39	int FAST_FUNC get_console_fd_or_die(void)
40	{
41	static const char *const console_names[] = {
42	DEV_CONSOLE, CURRENT_VC, CURRENT_TTY
43	};
44
45	int fd;
46
47	for (fd = 2; fd >= 0; fd--) {
48	int fd4name;
49	int choice_fd;
50	char arg;
51
52	fd4name = open_a_console(console_names[fd]);
53	chk_std:
54	choice_fd = (fd4name >= 0 ? fd4name : fd);
55
56	arg = 0;
57	if (ioctl(choice_fd, KDGKBTYPE, &arg) == 0)
58	return choice_fd;
59	if (fd4name >= 0) {
60	close(fd4name);
61	fd4name = -1;
62	goto chk_std;
63	}
64	}
65
66	bb_error_msg_and_die("can't open console");
67	/return fd; - total failure /
68	}
69
70	/* From <linux/vt.h> */
71	enum {
72	VT_ACTIVATE = 0x5606, /* make vt active */
73	VT_WAITACTIVE = 0x5607 /* wait for vt active */
74	};
75
76	void FAST_FUNC console_make_active(int fd, const int vt_num)
77	{
78	xioctl(fd, VT_ACTIVATE, (void *)(ptrdiff_t)vt_num);
79	xioctl(fd, VT_WAITACTIVE, (void *)(ptrdiff_t)vt_num);
80	}