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-rw-r--r--libtommath/bn_mp_grow.c53
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diff --git a/libtommath/bn_mp_grow.c b/libtommath/bn_mp_grow.c
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+++ b/libtommath/bn_mp_grow.c
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+#include <tommath.h>
+#ifdef BN_MP_GROW_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
+ */
+
+/* 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 = OPT_CAST(mp_digit) XREALLOC (a->dp, sizeof (mp_digit) * size);
+ 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;
+ for (; i < a->alloc; i++) {
+ a->dp[i] = 0;
+ }
+ }
+ return MP_OKAY;
+}
+#endif