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 <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#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 get_console_fd(void)
{
	int fd;

	static const char * const choise_console_names[] = {
		CONSOLE_DEV, CURRENT_VC, CURRENT_TTY
	};

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

		fd4name = open_a_console(choise_console_names[fd]);
	chk_std:
		choise_fd = fd4name >= 0 ? fd4name : fd;

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

	bb_error_msg("cannot get file descriptor referring to console");
	return fd;                      /* total failure */
}
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 <stdio.h>
12	#include <errno.h>
13	#include <fcntl.h>
14	#include <unistd.h>
15	#include <sys/ioctl.h>
16	#include "libbb.h"
17
18
19
20	/* From <linux/kd.h> */
21	enum { KDGKBTYPE = 0x4B33 }; /* get keyboard type */
22
23
24	static int open_a_console(const char *fnam)
25	{
26	int fd;
27
28	/* try read-write */
29	fd = open(fnam, O_RDWR);
30
31	/* if failed, try read-only */
32	if (fd < 0 && errno == EACCES)
33	fd = open(fnam, O_RDONLY);
34
35	/* if failed, try write-only */
36	if (fd < 0 && errno == EACCES)
37	fd = open(fnam, O_WRONLY);
38
39	return fd;
40	}
41
42	/*
43	* Get an fd for use with kbd/console ioctls.
44	* We try several things because opening /dev/console will fail
45	* if someone else used X (which does a chown on /dev/console).
46	*/
47
48	int get_console_fd(void)
49	{
50	int fd;
51
52	static const char * const choise_console_names[] = {
53	CONSOLE_DEV, CURRENT_VC, CURRENT_TTY
54	};
55
56	for (fd = 2; fd >= 0; fd--) {
57	int fd4name;
58	int choise_fd;
59	char arg;
60
61	fd4name = open_a_console(choise_console_names[fd]);
62	chk_std:
63	choise_fd = fd4name >= 0 ? fd4name : fd;
64
65	arg = 0;
66	if (ioctl(choise_fd, KDGKBTYPE, &arg) == 0)
67	return choise_fd;
68	if(fd4name >= 0) {
69	close(fd4name);
70	fd4name = -1;
71	goto chk_std;
72	}
73	}
74
75	bb_error_msg("cannot get file descriptor referring to console");
76	return fd; /* total failure */
77	}