askfirst.c

   1 /*
   2  * Copyright (C) 2013 Felix Fietkau <nbd@openwrt.org>
   3  * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by the Free Software Foundation
   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 <sys/types.h>
  16 #include <sys/stat.h>
  17
  18 #include <stdio.h>
  19 #include <unistd.h>
  20 #include <fcntl.h>
  21
  22 static int redirect_output(const char *dev)
  23 {
  24         pid_t p = setsid();
  25         int fd;
  26
  27         chdir("/dev");
  28         fd = open(dev, O_RDWR);
  29         chdir("/");
  30
  31         if (fd < 0)
  32                 return -1;
  33
  34         dup2(fd, STDIN_FILENO);
  35         dup2(fd, STDOUT_FILENO);
  36         dup2(fd, STDERR_FILENO);
  37         tcsetpgrp(fd, p);
  38         close(fd);
  39
  40         return 0;
  41 }
  42
  43 int main(int argc, char **argv)
  44 {
  45         int c;
  46
  47         if (redirect_output(argv[1]))
  48                 fprintf(stderr, "%s: Failed to open %s\n", argv[0], argv[1]);
  49
  50         printf("Please press Enter to activate this console.\n");
  51         do {
  52                 c = getchar();
  53                 if (c == EOF)
  54                         return -1;
  55         }
  56         while (c != 0xA);
  57
  58         execvp(argv[2], &argv[2]);
  59         printf("%s: Failed to execute %s\n", argv[0], argv[2]);
  60
  61         return -1;
  62 }