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
  24 void usage(void)
  25 {
  26         printf("usage: btrfs-crc filename\n");
  27         printf("    print out the btrfs crc for \"filename\"\n");
  28         printf("usage: btrfs-crc filename -c crc [-s seed] [-l length]\n");
  29         printf("    brute force search for file names with the given crc\n");
  30         printf("      -s seed    the random seed (default: random)\n");
  31         printf("      -l length  the length of the file names (default: 10)\n");
  32         exit(1);
  33 }
  34
  35 int main(int argc, char **argv)
  36 {
  37         int c;
  38         unsigned long checksum = 0;
  39         char *str;
  40         char *buf;
  41         int length = 10;
  42         int seed = getpid() ^ getppid();
  43         int loop = 0;
  44         int i;
  45
  46         while ((c = getopt(argc, argv, "l:c:s:h")) != -1) {
  47                 switch (c) {
  48                 case 'l':
  49                         length = atol(optarg);
  50                         break;
  51                 case 'c':
  52                         sscanf(optarg, "%li", &checksum);
  53                         loop = 1;
  54                         break;
  55                 case 's':
  56                         seed = atol(optarg);
  57                         break;
  58                 case 'h':
  59                         usage();
  60                 case '?':
  61                         return 255;
  62                 }
  63         }
  64
  65         str = argv[optind];
  66
  67         if (!loop) {
  68                 if (optind >= argc) {
  69                         fprintf(stderr, "not enough arguments\n");
  70                         return 255;
  71                 }
  72                 printf("%12u - %s\n", crc32c(~1, str, strlen(str)), str);
  73                 return 0;
  74         }
  75
  76         buf = malloc(length);
  77         if (!buf)
  78                 return -ENOMEM;
  79         srand(seed);
  80
  81         while (1) {
  82                 for (i = 0; i < length; i++)
  83                         buf[i] = rand() % 94 + 33;
  84                 if (crc32c(~1, buf, length) == checksum)
  85                         printf("%12lu - %.*s\n", checksum, length, buf);
  86         }
  87
  88         return 0;
  89 }