1/* vi: set sw=4 ts=4: */ 2/* 3 * Utility routines. 4 * 5 * Copyright (C) tons of folks. Tracking down who wrote what 6 * isn't something I'm going to worry about... If you wrote something 7 * here, please feel free to acknowledge your work. 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2 of the License, or 12 * (at your option) any later version. 13 * 14 * This program is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 * General Public License for more details. 18 * 19 * You should have received a copy of the GNU General Public License 20 * along with this program; if not, write to the Free Software 21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 22 * 23 * Based in part on code from sash, Copyright (c) 1999 by David I. Bell 24 * Permission has been granted to redistribute this code under the GPL. 25 * 26 */ 27 28#include <stdio.h> 29#include <errno.h> 30#include <fcntl.h> 31#include <unistd.h> 32#include <sys/ioctl.h> 33#include "libbb.h" 34 35 36 37 38 39/* From <linux/kd.h> */ 40static const int KDGKBTYPE = 0x4B33; /* get keyboard type */ 41static const int KB_84 = 0x01; 42static const int KB_101 = 0x02; /* this is what we always answer */ 43 44int is_a_console(int fd) 45{ 46 char arg; 47 48 arg = 0; 49 return (ioctl(fd, KDGKBTYPE, &arg) == 0 50 && ((arg == KB_101) || (arg == KB_84))); 51} 52 53static int open_a_console(char *fnam) 54{ 55 int fd; 56 57 /* try read-only */ 58 fd = open(fnam, O_RDWR); 59 60 /* if failed, try read-only */ 61 if (fd < 0 && errno == EACCES) 62 fd = open(fnam, O_RDONLY); 63 64 /* if failed, try write-only */ 65 if (fd < 0 && errno == EACCES) 66 fd = open(fnam, O_WRONLY); 67 68 /* if failed, fail */ 69 if (fd < 0) 70 return -1; 71 72 /* if not a console, fail */ 73 if (!is_a_console(fd)) { 74 close(fd); 75 return -1; 76 } 77 78 /* success */ 79 return fd; 80} 81 82/* 83 * Get an fd for use with kbd/console ioctls. 84 * We try several things because opening /dev/console will fail 85 * if someone else used X (which does a chown on /dev/console). 86 * 87 * if tty_name is non-NULL, try this one instead. 88 */ 89 90int get_console_fd(char *tty_name) 91{ 92 int fd; 93 94 if (tty_name) { 95 if (-1 == (fd = open_a_console(tty_name))) 96 return -1; 97 else 98 return fd; 99 } 100 101 fd = open_a_console(CURRENT_TTY); 102 if (fd >= 0) 103 return fd; 104 105 fd = open_a_console(CURRENT_VC); 106 if (fd >= 0) 107 return fd; 108 109 fd = open_a_console(CONSOLE_DEV); 110 if (fd >= 0) 111 return fd; 112 113 for (fd = 0; fd < 3; fd++) 114 if (is_a_console(fd)) 115 return fd; 116 117 error_msg("Couldn't get a file descriptor referring to the console"); 118 return -1; /* total failure */ 119} 120 121 122/* END CODE */ 123/* 124Local Variables: 125c-file-style: "linux" 126c-basic-offset: 4 127tab-width: 4 128End: 129*/ 130