util/post/post.c

   1 /*
   2  * Copyright (C) 2016 Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <errno.h>
  16 #include <limits.h>
  17 #include <stdarg.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <sys/io.h>
  21
  22 #define POST_DEFAULT_IO_PORT 0x80
  23
  24 void usage(char *progname, const char *error, ...)
  25 {
  26         printf("Usage: %s <VALUE> [PORT]\n", progname);
  27         printf("The VALUE argument is an integer between 0x00 and 0xff\n");
  28         printf("The PORT argument is an integer between 0x00 and 0xffff\n");
  29
  30         if (error) {
  31                 va_list args;
  32
  33                 va_start(args, error);
  34                 vprintf(error, args);
  35                 va_end(args);
  36         };
  37 }
  38
  39 void check_int(long val, int min, int max, int err, char *string, char *endptr,
  40                char *progname)
  41 {
  42         if (val < min || val > max) {
  43                 usage(progname,
  44                       "\nError: The value has to be between 0x%x and 0x%x\n",
  45                       min, max);
  46                 exit(EXIT_FAILURE);
  47         }
  48
  49         if (endptr == string || *endptr != '\0') {
  50                 usage(progname, "\nError: An integer is required\n");
  51                 exit(EXIT_FAILURE);
  52         }
  53
  54         if ((err) && (!val)) {
  55                 perror("strtol");
  56                 exit(EXIT_FAILURE);
  57         }
  58 }
  59
  60 int main(int argc, char *argv[])
  61 {
  62         unsigned long val;
  63         unsigned long port = POST_DEFAULT_IO_PORT;
  64         char *endptr;
  65         int err;
  66
  67         if (argc != 2 && argc != 3) {
  68                 usage(argv[0], NULL);
  69                 exit(EXIT_FAILURE);
  70         }
  71
  72         val = strtol(argv[1], &endptr, 0);
  73         err = errno;
  74         check_int(val, 0x00, 0xff, err, argv[1], endptr, argv[0]);
  75
  76         if (argc > 2) {
  77                 port = strtol(argv[2], &endptr, 0);
  78                 err = errno;
  79                 check_int(port, 0x0000, 0xffff, err, argv[2], endptr, argv[0]);
  80         }
  81
  82         err = iopl(3);
  83         if (err == -1) {
  84                 perror("Not root");
  85                 exit(EXIT_FAILURE);
  86         }
  87
  88         outb(val, port);
  89
  90         return 0;
  91 }