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  1. /*
  2.  * Copyright (c) 2007 Michael Niedermayer
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public
  8.  * License as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14.  * Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public
  17.  * License along with FFmpeg; if not, write to the Free Software
  18.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. #include <stdio.h>
  22. #include <stdlib.h>
  23. #include <inttypes.h>
  24. #include <errno.h>
  25. #include <string.h>
  26.  
  27. static uint32_t state;
  28. static uint32_t ran(void)
  29. {
  30.     return state = state * 1664525 + 1013904223;
  31. }
  32.  
  33. static void checked_seek(FILE *stream, int64_t offset, int whence)
  34. {
  35.     offset = fseek(stream, offset, whence);
  36.     if (offset < 0) {
  37.         fprintf(stderr, "seek failed\n");
  38.         exit(1);
  39.     }
  40. }
  41.  
  42. int main(int argc, char **argv)
  43. {
  44.     FILE *f;
  45.     int count, maxburst, length;
  46.  
  47.     if (argc < 5) {
  48.         printf("USAGE: trasher <filename> <count> <maxburst> <seed>\n");
  49.         return 1;
  50.     }
  51.  
  52.     f = fopen(argv[1], "rb+");
  53.     if (!f) {
  54.         perror(argv[1]);
  55.         return 2;
  56.     }
  57.     count    = atoi(argv[2]);
  58.     maxburst = atoi(argv[3]);
  59.     state    = atoi(argv[4]);
  60.  
  61.     checked_seek(f, 0, SEEK_END);
  62.     length = ftell(f);
  63.     checked_seek(f, 0, SEEK_SET);
  64.  
  65.     while (count--) {
  66.         int burst = 1 + ran() * (uint64_t) (abs(maxburst) - 1) / UINT32_MAX;
  67.         int pos   = ran() * (uint64_t) length / UINT32_MAX;
  68.         checked_seek(f, pos, SEEK_SET);
  69.  
  70.         if (maxburst < 0)
  71.             burst = -maxburst;
  72.  
  73.         if (pos + burst > length)
  74.             continue;
  75.  
  76.         while (burst--) {
  77.             int val = ran() * 256ULL / UINT32_MAX;
  78.  
  79.             if (maxburst < 0)
  80.                 val = 0;
  81.  
  82.             fwrite(&val, 1, 1, f);
  83.         }
  84.     }
  85.  
  86.     return 0;
  87. }
  88.