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