tools/trasher.c

   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 }