/*
  * Copyright (c) 2007 Michael Niedermayer
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 
 #include <stdio.h>

 #include <stdlib.h>

 #include <inttypes.h>

 #include <errno.h>
 #include <string.h>

 static uint32_t state;

 static uint32_t ran(void)
 {
     return state = state * 1664525 + 1013904223;

 }
 

 static void checked_seek(FILE *stream, int64_t offset, int whence)
 {
     offset = fseek(stream, offset, whence);
     if (offset < 0) {
         fprintf(stderr, "seek failed\n");
         exit(1);
     }
 }
 

 int main(int argc, char **argv)

 {

     FILE *f;
     int count, maxburst, length;
 

     if (argc < 5) {

         printf("USAGE: trasher <filename> <count> <maxburst> <seed>\n");

         return 1;
     }
 

     f = fopen(argv[1], "rb+");
     if (!f) {

         perror(argv[1]);
         return 2;
     }

     count    = atoi(argv[2]);
     maxburst = atoi(argv[3]);
     state    = atoi(argv[4]);

     checked_seek(f, 0, SEEK_END);

     length = ftell(f);

     checked_seek(f, 0, SEEK_SET);

     while (count--) {
         int burst = 1 + ran() * (uint64_t) (abs(maxburst) - 1) / UINT32_MAX;
         int pos   = ran() * (uint64_t) length / UINT32_MAX;

         checked_seek(f, pos, SEEK_SET);

         if (maxburst < 0)
             burst = -maxburst;

         if (pos + burst > length)

             continue;
 

         while (burst--) {
             int val = ran() * 256ULL / UINT32_MAX;

             if (maxburst < 0)
                 val = 0;

 
             fwrite(&val, 1, 1, f);
         }
     }
 
     return 0;
 }