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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) many different people.
* If you wrote this, please acknowledge your work.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include "libbb.h"
/* From <linux/kd.h> */
static const int KDGKBTYPE = 0x4B33; /* get keyboard type */
static const int KB_84 = 0x01;
static const int KB_101 = 0x02; /* this is what we always answer */
static int is_a_console(int fd)
{
char arg;
arg = 0;
return (ioctl(fd, KDGKBTYPE, &arg) == 0
&& ((arg == KB_101) || (arg == KB_84)));
}
static int open_a_console(char *fnam)
{
int fd;
/* try read-only */
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);
/* if failed, fail */
if (fd < 0)
return -1;
/* if not a console, fail */
if (!is_a_console(fd)) {
close(fd);
return -1;
}
/* success */
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).
*
* if tty_name is non-NULL, try this one instead.
*/
int get_console_fd(void)
{
int fd;
if (-1 == (fd = open_a_console("/dev/console")))
return -1;
else
return fd;
fd = open_a_console(CURRENT_TTY);
if (fd >= 0)
return fd;
fd = open_a_console(CURRENT_VC);
if (fd >= 0)
return fd;
fd = open_a_console(CONSOLE_DEV);
if (fd >= 0)
return fd;
for (fd = 0; fd < 3; fd++)
if (is_a_console(fd))
return fd;
bb_error_msg("Couldn't get a file descriptor referring to the console");
return -1; /* total failure */
}
/* END CODE */
/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/
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