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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.
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#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)
{
static const char *const console_names[] = {
DEV_CONSOLE, CURRENT_VC, CURRENT_TTY
};
int fd;
for (fd = 2; fd >= 0; fd--) {
int fd4name;
int choise_fd;
char arg;
fd4name = open_a_console(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 */
}
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