73 lines
1.4 KiB
C
73 lines
1.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) many different people. If you wrote this, please
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* acknowledge your work.
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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#include <sys/ioctl.h>
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#include "libbb.h"
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/* From <linux/kd.h> */
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enum { KDGKBTYPE = 0x4B33 }; /* get keyboard type */
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static int open_a_console(const char *fnam)
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{
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int fd;
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/* try read-write */
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fd = open(fnam, O_RDWR);
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/* if failed, try read-only */
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if (fd < 0 && errno == EACCES)
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fd = open(fnam, O_RDONLY);
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/* if failed, try write-only */
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if (fd < 0 && errno == EACCES)
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fd = open(fnam, O_WRONLY);
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return fd;
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}
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/*
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* Get an fd for use with kbd/console ioctls.
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* We try several things because opening /dev/console will fail
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* if someone else used X (which does a chown on /dev/console).
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*/
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int get_console_fd(void)
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{
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static const char *const console_names[] = {
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DEV_CONSOLE, CURRENT_VC, CURRENT_TTY
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};
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int fd;
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for (fd = 2; fd >= 0; fd--) {
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int fd4name;
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int choice_fd;
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char arg;
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fd4name = open_a_console(console_names[fd]);
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chk_std:
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choice_fd = (fd4name >= 0 ? fd4name : fd);
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arg = 0;
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if (ioctl(choice_fd, KDGKBTYPE, &arg) == 0)
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return choice_fd;
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if (fd4name >= 0) {
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close(fd4name);
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fd4name = -1;
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goto chk_std;
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}
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}
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bb_error_msg("cannot get file descriptor referring to console");
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return fd; /* total failure */
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}
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