grub/util/garbage-gen.c

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/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2013 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
/* Standard random generator is slow. For FS testing we need just some
garbage files, we don't need them to be high-quality random.
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
static unsigned long long buffer[1048576];
int
main (int argc, char **argv)
{
unsigned long long high = 0, low = 1;
unsigned long i, j;
unsigned long long cnt = strtoull (argv[1], 0, 0);
struct timeval tv;
gettimeofday (&tv, NULL);
high = tv.tv_sec;
low = tv.tv_usec;
if (!high)
high = 1;
if (!low)
low = 2;
for (j = 0; j < (cnt + sizeof (buffer) - 1) / sizeof (buffer); j++)
{
for (i = 0; i < sizeof (buffer) / sizeof (buffer[0]); i += 2)
{
int c1 = 0, c2 = 0;
buffer[i] = low;
buffer[i+1] = high;
if (low & (1ULL << 63))
c1 = 1;
low <<= 1;
if (high & (1ULL << 63))
c2 = 1;
high = (high << 1) | c1;
if (c2)
low ^= 0x87;
}
if (sizeof (buffer) < cnt - sizeof (buffer) * j)
fwrite (buffer, 1, sizeof (buffer), stdout);
else
fwrite (buffer, 1, cnt - sizeof (buffer) * j, stdout);
}
return 0;
}