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[821] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Utility routines.
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| 4 | *
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| 5 | * Copyright (C) many different people. If you wrote this, please
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| 6 | * acknowledge your work.
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| 7 | *
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| 8 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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| 9 | */
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| 10 |
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[1765] | 11 | //#include <sys/ioctl.h>
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[821] | 12 | #include "libbb.h"
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| 13 |
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| 14 |
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| 15 | /* From <linux/kd.h> */
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| 16 | enum { KDGKBTYPE = 0x4B33 }; /* get keyboard type */
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| 17 |
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| 18 |
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| 19 | static int open_a_console(const char *fnam)
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| 20 | {
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| 21 | int fd;
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| 22 |
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| 23 | /* try read-write */
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| 24 | fd = open(fnam, O_RDWR);
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| 25 |
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| 26 | /* if failed, try read-only */
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| 27 | if (fd < 0 && errno == EACCES)
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| 28 | fd = open(fnam, O_RDONLY);
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| 29 |
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| 30 | /* if failed, try write-only */
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| 31 | if (fd < 0 && errno == EACCES)
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| 32 | fd = open(fnam, O_WRONLY);
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| 33 |
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| 34 | return fd;
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| 35 | }
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| 36 |
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| 37 | /*
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| 38 | * Get an fd for use with kbd/console ioctls.
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| 39 | * We try several things because opening /dev/console will fail
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| 40 | * if someone else used X (which does a chown on /dev/console).
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| 41 | */
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| 42 |
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| 43 | int get_console_fd(void)
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| 44 | {
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[1765] | 45 | static const char *const console_names[] = {
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| 46 | DEV_CONSOLE, CURRENT_VC, CURRENT_TTY
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| 47 | };
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| 48 |
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[821] | 49 | int fd;
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| 50 |
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| 51 | for (fd = 2; fd >= 0; fd--) {
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| 52 | int fd4name;
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[1765] | 53 | int choice_fd;
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[821] | 54 | char arg;
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| 55 |
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[1765] | 56 | fd4name = open_a_console(console_names[fd]);
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| 57 | chk_std:
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| 58 | choice_fd = (fd4name >= 0 ? fd4name : fd);
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[821] | 59 |
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| 60 | arg = 0;
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[1765] | 61 | if (ioctl(choice_fd, KDGKBTYPE, &arg) == 0)
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| 62 | return choice_fd;
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| 63 | if (fd4name >= 0) {
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[821] | 64 | close(fd4name);
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| 65 | fd4name = -1;
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| 66 | goto chk_std;
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| 67 | }
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| 68 | }
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| 69 |
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[1765] | 70 | bb_error_msg("cannot get file descriptor referring to console");
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[821] | 71 | return fd; /* total failure */
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| 72 | }
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