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// SPDX-License-Identifier: BSD-3-Clause
#include <assert.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include "util.h"
static inline signed char hexchr2int(char c) {
/* No, nobody uses EBCDIC anymore. */
return (c >= '0' && c <= '9') ? (c - '0') :
(c >= 'a' && c <= 'f') ? (c - 'a' + 10) :
(c >= 'A' && c <= 'F') ? (c - 'A' + 10) :
-1;
}
/**
* Decode hex.
*
* \param dest where to store the decoded data
* \param size the maximum number of bytes to decode
* \param src the hex-encoded data
*
* \return 0 if an error occurred, otherwise the number of bytes written to
* dest
*/
size_t hex2mem(unsigned char *dest, size_t size, const char *src) {
#ifdef DEBUG
fprintf(stderr, "hex decoding %zu bytes\n", size);
#endif
size_t i;
for (i = 0; i < size; i++) {
int n1 = hexchr2int(src[2*i]);
if (n1 < 0) return 0;
int n2 = hexchr2int(src[2*i+1]);
if (n2 < 0) return 0;
dest[i] = (unsigned char)(n1 << 4 | n2);
}
return i;
}
static const char *HEX_CHARS = "0123456789abcdef";
/** Encode hex.
*
* \param dest where to store the encoded data (must have at least size*2+1 bytes)
* \param src the data to encode
* \param size the number of bytes to encode
*/
void mem2hex(char *dest, const void *src, size_t size) {
size_t i;
for (i = 0; i < size; i++) {
unsigned char c = *((const unsigned char *)src + i);
dest[2*i] = HEX_CHARS[c >> 4];
dest[2*i+1] = HEX_CHARS[c & 0xf];
}
dest[2*i] = '\0';
}
ssize_t random_get(void *buf, size_t buflen, unsigned int flags) {
memset(buf, 0, buflen);
long rv = syscall(SYS_getrandom, buf, buflen, flags);
if (rv == -1) {
if (errno == ENOSYS) {
fputs("getrandom returned ENOSYS. random-seed requires Linux 3.17\n", stderr);
exit(1);
}
} else {
bool all_zero = true;
if (buflen > 32) {
for (size_t i = 0; i < buflen; i++) {
if (((unsigned char *)buf)[i] != 0) {
all_zero = false;
break;
}
}
}
if (all_zero) {
fputs("getrandom returned all zeros, probably broken\n", stderr);
exit(1);
}
}
return rv;
}
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