/* * 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;}