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/* See LICENSE file for copyright and license details. */
#include <sys/mount.h>
#include <libsimple.h>
#include <libsimple-arg.h>
USAGE("file");
struct span {
off_t start;
off_t end;
size_t blocksize;
};
static struct span *spans = NULL;
static size_t nspans = 0;
static size_t spans_size = 0;
static off_t shredded = 0;
static off_t total_size = 0;
static char reservoir[128U << 10];
static size_t reservoir_off = sizeof(reservoir);
static char total_size_1000[256];
static char total_size_1024[256];
static off_t
filesize(int fd, const char *fname)
{
struct stat st;
if (fstat(fd, &st))
eprintf("fstat %s:", fname);
switch (st.st_mode & S_IFMT) {
case S_IFREG:
break;
case S_IFBLK:
if (ioctl(fd, BLKGETSIZE64, &st.st_size) < 0)
eprintf("ioctl %s BLKGETSIZE64:", fname);
break;
default:
eprintf("%s: not a regular file or block device", fname);
}
return st.st_size;
}
static void
ensure_random(size_t needed)
{
size_t off;
ssize_t r;
if (sizeof(reservoir) - reservoir_off >= needed)
return;
for (off = 0; off < reservoir_off;) {
r = read(STDIN_FILENO, &reservoir[off], reservoir_off - off);
if (r <= 0) {
if (!r)
eprintf("random source depleted");
if (errno == EINTR)
continue;
eprintf("read <stdin>:");
}
off += (size_t)r;
}
reservoir_off = 0;
}
static off_t
add_span(off_t off, off_t max_end, size_t blocksize)
{
off_t end;
end = MIN((off | ((off_t)blocksize - 1)) + 1, max_end);
while ((off_t)(blocksize >> 1) >= end - off)
blocksize >>= 1;
if (nspans == spans_size) {
spans_size += 1024;
spans = ereallocarray(spans, spans_size, sizeof(*spans));
}
spans[nspans].start = off;
spans[nspans].end = end;
spans[nspans].blocksize = (size_t)blocksize;
nspans++;
}
static char *
humansize1000(off_t s, char *buf)
{
const char *units = "kMGTPEZYRQ";
size_t unit = 0;
if (s < 1000) {
sprintf(buf, "%u B", (unsigned)s);
return buf;
}
s /= 100;
while (units[unit + 1U] && s >= 10000) {
s /= 1000;
unit++;
}
sprintf(buf, "%u.%u %cB", (unsigned)s / 10U, (unsigned)s % 10U, units[unit]);
return buf;
}
static char *
humansize1024(off_t s, char *buf)
{
const char *units = "KMGTPEZYRQ";
size_t unit = 0;
if (s < 1024) {
sprintf(buf, "%u B", (unsigned)s);
return buf;
}
while (units[unit + 1U] && s >= 1024 * 1024) {
s /= 1024;
unit++;
}
sprintf(buf, "%lu.%u %ciB", (unsigned long int)s / 1024U, (unsigned long int)((s * 10 % 10240) / 1024U), units[unit]);
return buf;
}
static int
print_progress(int done)
{
static char buf1[1024] = {0};
static char buf2[1024] = {0};
static int i = 0;
char subbuf1[256];
char subbuf2[256];
sprintf(i == 0 ? buf1 : buf2,
"%.2lf %% (%s, %s) of %s (%s) shredded\033[K\n%s",
100. * (double)shredded / (double)total_size,
humansize1000(shredded, subbuf1),
humansize1024(shredded, subbuf2),
total_size_1000,
total_size_1024,
done ? "" : "\033[A");
if (strcmp(buf1, buf2)) {
fprintf(stderr, "%s", i == 0 ? buf1 : buf2);
fflush(stderr);
}
i ^= 1;
}
static void
shredspan(int fd, const struct span *span, const char *fname)
{
off_t off;
ssize_t r;
for (off = span->start; off < span->end;) {
print_progress(0);
if (lseek(fd, off, SEEK_SET) < 0)
eprintf("lseek %s %ji SEEK_SET\n", fname, (intmax_t)off);
ensure_random(span->blocksize);
r = write(fd, &reservoir[reservoir_off], (size_t)MIN((off_t)span->blocksize, span->end - off));
if (r < 0) {
if (errno != EINTR)
off = add_span(off, span->end, span->blocksize == 1U ? 1U : span->blocksize);
continue;
}
off += (off_t)r;
shredded += (off_t)r;
reservoir_off += (size_t)r;
}
}
int
main(int argc, char *argv[])
{
char buf1[256];
char buf2[256];
size_t i;
int fd;
ARGBEGIN {
default:
usage();
} ARGEND;
if (argc != 1)
usage();
fd = open(argv[0], O_WRONLY);
if (fd < 0)
eprintf("open %s O_WRONLY:", argv[0]);
spans = emalloc(sizeof(*spans));
spans[0].start = 0;
spans[0].end = total_size = filesize(fd, argv[0]);
spans[0].blocksize = 8192U;
nspans = 1U;
spans_size = 1U;
humansize1000(total_size, total_size_1000);
humansize1024(total_size, total_size_1024);
while (nspans) {
size_t old_nspans = nspans;
for (i = 0; i < old_nspans; i++)
shredspan(fd, &spans[i], argv[0]);
nspans -= old_nspans;
memmove(&spans[0], &spans[old_nspans], nspans * sizeof(*spans));
}
close(fd);
print_progress(1);
return 0;
}
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