lib/crypto/mpi/mpiutil.c

/* mpiutil.ac  -  Utility functions for MPI
 * Copyright (C) 1998, 1999 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * GnuPG is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include "mpi-internal.h"

/****************
 * Note:  It was a bad idea to use the number of limbs to allocate
 *	  because on a alpha the limbs are large but we normally need
 *	  integers of n bits - So we should change this to bits (or bytes).
 *
 *	  But mpi_alloc is used in a lot of places :-)
 */
MPI mpi_alloc(unsigned nlimbs)
{
	MPI a;

	a = kmalloc(sizeof *a, GFP_KERNEL);
	if (!a)
		return a;

	if (nlimbs) {
		a->d = mpi_alloc_limb_space(nlimbs);
		if (!a->d) {
			kfree(a);
			return NULL;
		}
	} else {
		a->d = NULL;
	}

	a->alloced = nlimbs;
	a->nlimbs = 0;
	a->sign = 0;
	a->flags = 0;
	a->nbits = 0;
	return a;
}
EXPORT_SYMBOL_GPL(mpi_alloc);

mpi_ptr_t mpi_alloc_limb_space(unsigned nlimbs)
{
	size_t len = nlimbs * sizeof(mpi_limb_t);

	if (!len)
		return NULL;

	return kmalloc(len, GFP_KERNEL);
}

void mpi_free_limb_space(mpi_ptr_t a)
{
	if (!a)
		return;

	kfree_sensitive(a);
}

void mpi_assign_limb_space(MPI a, mpi_ptr_t ap, unsigned nlimbs)
{
	mpi_free_limb_space(a->d);
	a->d = ap;
	a->alloced = nlimbs;
}

/****************
 * Resize the array of A to NLIMBS. the additional space is cleared
 * (set to 0) [done by m_realloc()]
 */
int mpi_resize(MPI a, unsigned nlimbs)
{
	void *p;

	if (nlimbs <= a->alloced)
		return 0;	/* no need to do it */

	if (a->d) {
		p = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL);
		if (!p)
			return -ENOMEM;
		memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t));
		kfree_sensitive(a->d);
		a->d = p;
	} else {
		a->d = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL);
		if (!a->d)
			return -ENOMEM;
	}
	a->alloced = nlimbs;
	return 0;
}

void mpi_free(MPI a)
{
	if (!a)
		return;

	if (a->flags & 4)
		kfree_sensitive(a->d);
	else
		mpi_free_limb_space(a->d);

	if (a->flags & ~7)
		pr_info("invalid flag value in mpi\n");
	kfree(a);
}
EXPORT_SYMBOL_GPL(mpi_free);

/****************
 * Note: This copy function should not interpret the MPI
 *	 but copy it transparently.
 */
MPI mpi_copy(MPI a)
{
	int i;
	MPI b;

	if (a) {
		b = mpi_alloc(a->nlimbs);
		if (!b)
			return NULL;
		b->nlimbs = a->nlimbs;
		b->sign = a->sign;
		b->flags = a->flags;
		b->flags &= ~(16|32); /* Reset the immutable and constant flags. */
		for (i = 0; i < b->nlimbs; i++)
			b->d[i] = a->d[i];
	} else
		b = NULL;
	return b;
}

MODULE_DESCRIPTION("Multiprecision maths library");
MODULE_LICENSE("GPL");