lilcrypto/util.c

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/*
* Copyright (c) 2024 Lucas Gabriel Vuotto <lucas@lgv5.net>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
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#include <ctype.h>
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#include <string.h>
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#include "lilcrypto.h"
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#define HEXDUMP_BUFSZ 128
static size_t
hexdump_line(char *buf, const uint8_t *blob, size_t len, size_t off, int pad)
{
/*
* Format is
* - 16-char hex offset (at most)
* - 2 spaces
* - 2-char hex byte and a space (16 times)
* - 2 spaces
* - 2 pipe chars + 16 renders of the blobs
*
* That accounts for, at most, 16 + 2 + 16 * 3 + 2 + 18. Adding an
* extra byte for the NUL ending byte, that amounts for 87.
*
* Callers MUST provide a buffer at least HEXDUMP_BUFSZ long in buf0.
*/
char *bufp;
size_t i, buflen;
int w;
bufp = buf;
buflen = HEXDUMP_BUFSZ;
if (len == 0)
(void)snprintf(bufp, buflen, "%0*zx\n", pad, off);
else {
w = snprintf(bufp, buflen, "%0*zx ", pad, off);
bufp += w;
buflen -= w;
for (i = 0; i < len && i < 8; i++) {
w = snprintf(bufp, buflen, "%02x ", blob[i]);
bufp += w;
buflen -= w;
}
if (i < 8) {
memset(bufp, ' ', 3 * (16 - i));
bufp += 3 * (16 - i);
buflen -= 3 * (16 - i);
}
for (; i < len && i < 16; i++) {
w = snprintf(bufp, buflen, " %02x", blob[i]);
bufp += w;
buflen -= w;
}
if (i < 16) {
memset(bufp, ' ', 3 * (16 - i));
bufp += 3 * (16 - i);
buflen -= 3 * (16 - i);
}
w = snprintf(bufp, buflen, " |");
bufp += w;
buflen -= w;
for (i = 0; i < len && i < 16; i++) {
w = snprintf(bufp, buflen, "%c",
isprint(blob[i]) ? blob[i] : '.');
bufp += w;
buflen -= w;
}
(void)snprintf(bufp, buflen, "|\n");
}
return len < 16 ? len : 16;
}
int
lc_hexdump_fp(FILE *fp, const void *blob, size_t len)
{
const uint8_t *p = blob;
char buf[HEXDUMP_BUFSZ];
size_t l, off;
int pad;
for (pad = 1; len > (1 << (8 * pad)); pad++)
continue;
pad *= 2;
off = 0;
while (len > 0) {
l = hexdump_line(buf, p, len, off, pad);
if (fputs(buf, fp) == EOF)
return 0;
off += l;
len -= l;
}
(void)hexdump_line(buf, p, len, off, pad);
if (fputs(buf, fp) == EOF)
return 0;
return 1;
}
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void
lc_scrub(void *b, size_t len)
{
explicit_bzero(b, len);
}