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fix for mpz_urandomm reuse error

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This commit is contained in:
jasonmoxham 2009-03-13 00:42:52 +00:00
parent 4e5c7fb422
commit cb4298e911
1 changed files with 11 additions and 3 deletions
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14
mpz/urandomm.c
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@ -36,6 +36,7 @@ mpz_urandomm (mpz_ptr rop, gmp_randstate_t rstate, mpz_srcptr n)
int count;
int pow2;
int cmp;
int overlap=0;
size = ABSIZ (n);
if (size == 0)
@ -52,7 +53,6 @@ mpz_urandomm (mpz_ptr rop, gmp_randstate_t rstate, mpz_srcptr n)
pow2 = 0; /* Mark n as `not a power of two'. */
break;
}
count_leading_zeros (count, *nlast);
nbits = size * GMP_NUMB_BITS - (count - GMP_NAIL_BITS) - pow2;
if (nbits == 0) /* nbits == 0 means that n was == 1. */
@ -61,6 +61,13 @@ mpz_urandomm (mpz_ptr rop, gmp_randstate_t rstate, mpz_srcptr n)
return;
}
np=PTR(n);
rp=PTR(rop);
if(np==rp)
{overlap=1;
np=__GMP_ALLOCATE_FUNC_LIMBS(size);
MPN_COPY(np,PTR(n),size);
}
/* Here the allocated size can be one too much if n is a power of
(2^GMP_NUMB_BITS) but it's convenient for using mpn_cmp below. */
rp = MPZ_REALLOC (rop, size);
@ -71,14 +78,15 @@ mpz_urandomm (mpz_ptr rop, gmp_randstate_t rstate, mpz_srcptr n)
do
{
_gmp_rand (rp, rstate, nbits);
MPN_CMP (cmp, rp, PTR (n), size);
MPN_CMP (cmp, rp, np, size);
}
while (cmp >= 0 && --count != 0);
if (count == 0)
/* Too many iterations; return result mod n == result - n */
mpn_sub_n (rp, rp, PTR (n), size);
mpn_sub_n (rp, rp, np, size);
if(overlap)__GMP_FREE_FUNC_LIMBS(np,size);
MPN_NORMALIZE (rp, size);
SIZ (rop) = size;
}