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	niro	532	/* 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	niro	816	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	niro	532
45			int fd;
46
47			for (fd = 2; fd >= 0; fd--) {
48			int fd4name;
49	niro	816	int choice_fd;
50	niro	532	char arg;
51
52	niro	816	fd4name = open_a_console(console_names[fd]);
53			chk_std:
54			choice_fd = (fd4name >= 0 ? fd4name : fd);
55	niro	532
56			arg = 0;
57	niro	816	if (ioctl(choice_fd, KDGKBTYPE, &arg) == 0)
58			return choice_fd;
59			if (fd4name >= 0) {
60	niro	532	close(fd4name);
61			fd4name = -1;
62			goto chk_std;
63			}
64			}
65
66	niro	816	bb_error_msg_and_die("can't open console");
67			/return fd; - total failure /
68	niro	532	}
69	niro	816
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			}