btrfs-crc.c

   1 /*
   2  * Copyright (C) 2013 STRATO.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include "crc32c.h"
  23 #include "utils.h"
  24
  25 void print_usage(int status)
  26 {
  27         printf("usage: btrfs-crc filename\n");
  28         printf("    print out the btrfs crc for \"filename\"\n");
  29         printf("usage: btrfs-crc -c crc [-s seed] [-l length]\n");
  30         printf("    brute force search for file names with the given crc\n");
  31         printf("      -s seed    the random seed (default: random)\n");
  32         printf("      -l length  the length of the file names (default: 10)\n");
  33         printf("usage: btrfs-crc -h\n");
  34         printf("    print this message\n");
  35         exit(status);
  36 }
  37
  38 int main(int argc, char **argv)
  39 {
  40         int c;
  41         unsigned long checksum = 0;
  42         char *str;
  43         char *buf;
  44         int length = 10;
  45         u64 seed = 0;
  46         int loop = 0;
  47         int i;
  48
  49         while ((c = getopt(argc, argv, "l:c:s:h")) != -1) {
  50                 switch (c) {
  51                 case 'l':
  52                         length = atol(optarg);
  53                         break;
  54                 case 'c':
  55                         sscanf(optarg, "%li", &checksum);
  56                         loop = 1;
  57                         break;
  58                 case 's':
  59                         seed = atoll(optarg);
  60                         break;
  61                 case 'h':
  62                         print_usage(1);
  63                 case '?':
  64                         print_usage(255);
  65                 }
  66         }
  67
  68         set_argv0(argv);
  69         str = argv[optind];
  70
  71         if (!loop) {
  72                 if (check_argc_exact(argc - optind, 1))
  73                         print_usage(255);
  74
  75                 printf("%12u - %s\n", crc32c(~1, str, strlen(str)), str);
  76                 return 0;
  77         }
  78         if (check_argc_exact(argc - optind, 0))
  79                 print_usage(255);
  80
  81         buf = malloc(length);
  82         if (!buf)
  83                 return -ENOMEM;
  84         if (seed)
  85                 init_rand_seed(seed);
  86
  87         while (1) {
  88                 for (i = 0; i < length; i++)
  89                         buf[i] = rand_range(94) + 33;
  90                 if (crc32c(~1, buf, length) == checksum)
  91                         printf("%12lu - %.*s\n", checksum, length, buf);
  92         }
  93
  94         return 0;
  95 }