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/* Reads a block device and wipe a block if non-zero.
* Author: Peter Wu <peter@lekensteyn.nl>
* Date: 2014-06-26
*/
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <err.h>
#include <stdlib.h>
#define BUFSIZE (1024 * 1024 * 2)
static char zeroes[BUFSIZE];
static void wipe(int fd, size_t len) {
off_t pos;
ssize_t r;
pos = lseek(fd, -len, SEEK_CUR);
if (pos == (off_t) -1)
err(1, "failed to seek before write");
r = write(fd, zeroes, len);
if (r < 0)
err(1, "failed to write zeroes");
if ((size_t) r != len)
errx(1, "could only write %zu instead of %zu bytes", r, len);
}
static void read_and_wipe(int fd) {
ssize_t r;
off_t endpos, pos;
char *buf = malloc(BUFSIZE);
unsigned iteration = 0, rounds;
if (buf == NULL)
err(1, "malloc");
endpos = lseek(fd, 0, SEEK_END);
if (endpos == (off_t) -1)
err(1, "failed to seek end");
if (endpos == 0) {
warnx("file is empty");
return;
}
pos = lseek(fd, 0, SEEK_SET);
if (pos == (off_t) -1)
err(1, "failed to seek to begin");
rounds = endpos / BUFSIZE;
if (rounds * BUFSIZE < endpos)
++rounds;
do {
r = read(fd, buf, BUFSIZE);
printf("\r%u/%u -- %u%% (%llu/%llu)",
iteration, rounds,
(unsigned) (100 * pos / endpos),
(long long) pos, (long long) endpos);
if (r < 0) {
warn("read failed");
} else if (r > 0) {
char val = 0;
int i;
for (i = 0; i < r; i++) {
val |= buf[i];
}
pos += r;
/* if there are any non-zero bytes, act accordingly */
if (val != 0) {
printf(" WIPE ME!\n");
wipe(fd, r);
}
}
fflush(stdout);
++iteration;
} while (r > 0);
putchar('\n');
free(buf);
}
int main(int argc, char **argv) {
int fd;
if (argc < 2)
errx(1, "Missing device argument");
fd = open(argv[1], O_RDWR);
if (fd < 0)
err(1, "failed to open file");
read_and_wipe(fd);
close(fd);
return 0;
}
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