libtommath/bn_mp_grow.c
Daniel Mendler 61d9e528a4
hardening: add MP_ZERO_BUFFER, MP_ZERO_DIGITS
* (!) Always zero buffer before freeing if MP_NO_ZERO_ON_FREE is not defined
* Add MP_NO_ZERO_ON_FREE to disable hardening
* Add MP_ZERO_BUFFER, MP_ZERO_DIGITS, MP_FREE_BUFFFER, MP_FREE_DIGITS
* Never use MP_FREE directly, use MP_FREE_DIGITS or MP_FREE_BUFFER
* Add MP_USE_MEMSET to use memset instead of loop
* Disable astyle backups which are annonying in the times of git
2019-05-12 01:01:03 +02:00

42 lines
1.2 KiB
C

#include "tommath_private.h"
#ifdef BN_MP_GROW_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* grow as required */
int mp_grow(mp_int *a, int size)
{
int i;
mp_digit *tmp;
/* if the alloc size is smaller alloc more ram */
if (a->alloc < size) {
/* ensure there are always at least MP_PREC digits extra on top */
size += (MP_PREC * 2) - (size % MP_PREC);
/* reallocate the array a->dp
*
* We store the return in a temporary variable
* in case the operation failed we don't want
* to overwrite the dp member of a.
*/
tmp = (mp_digit *) MP_REALLOC(a->dp,
(size_t)a->alloc * sizeof(mp_digit),
(size_t)size * sizeof(mp_digit));
if (tmp == NULL) {
/* reallocation failed but "a" is still valid [can be freed] */
return MP_MEM;
}
/* reallocation succeeded so set a->dp */
a->dp = tmp;
/* zero excess digits */
i = a->alloc;
a->alloc = size;
MP_ZERO_DIGITS(a->dp + i, a->alloc - i);
}
return MP_OKAY;
}
#endif