LXR busybox/libbb/get

   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 source tree.
   9 */
  10
  11#include "libbb.h"
  12
  13/* From <linux/kd.h> */
  14enum { KDGKBTYPE = 0x4B33 };  /* get keyboard type */
  15
  16static int open_a_console(const char *fnam)
  17{
  18        int fd;
  19
  20        /* try read-write */
  21        fd = open(fnam, O_RDWR);
  22
  23        /* if failed, try read-only */
  24        if (fd < 0 && errno == EACCES)
  25                fd = open(fnam, O_RDONLY);
  26
  27        /* if failed, try write-only */
  28        if (fd < 0 && errno == EACCES)
  29                fd = open(fnam, O_WRONLY);
  30
  31        return fd;
  32}
  33
  34/*
  35 * Get an fd for use with kbd/console ioctls.
  36 * We try several things because opening /dev/console will fail
  37 * if someone else used X (which does a chown on /dev/console).
  38 */
  39int FAST_FUNC get_console_fd_or_die(void)
  40{
  41        static const char *const console_names[] = {
  42                DEV_CONSOLE, CURRENT_VC, CURRENT_TTY
  43        };
  44
  45        int fd;
  46
  47        for (fd = 2; fd >= 0; fd--) {
  48                int fd4name;
  49                int choice_fd;
  50                char arg;
  51
  52                fd4name = open_a_console(console_names[fd]);
  53 chk_std:
  54                choice_fd = (fd4name >= 0 ? fd4name : fd);
  55
  56                arg = 0;
  57                if (ioctl(choice_fd, KDGKBTYPE, &arg) == 0)
  58                        return choice_fd;
  59                if (fd4name >= 0) {
  60                        close(fd4name);
  61                        fd4name = -1;
  62                        goto chk_std;
  63                }
  64        }
  65
  66        bb_error_msg_and_die("can't open console");
  67        /*return fd; - total failure */
  68}
  69
  70/* From <linux/vt.h> */
  71enum {
  72        VT_ACTIVATE = 0x5606,   /* make vt active */
  73        VT_WAITACTIVE = 0x5607  /* wait for vt active */
  74};
  75
  76void FAST_FUNC console_make_active(int fd, const int vt_num)
  77{
  78        xioctl(fd, VT_ACTIVATE, (void *)(ptrdiff_t)vt_num);
  79        xioctl(fd, VT_WAITACTIVE, (void *)(ptrdiff_t)vt_num);
  80}
  81