linux-imx

/* mpicoder.c  -  Coder for the external representation of MPIs

 * 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 <linux/bitops.h>

#include <linux/count_zeros.h>

#include <linux/byteorder/generic.h>

#include <linux/scatterlist.h>

#include <linux/string.h>

#include "mpi-internal.h"

​

#define MAX_EXTERN_MPI_BITS 16384

​

/**

 * mpi_read_raw_data - Read a raw byte stream as a positive integer

 * @xbuffer: The data to read

 * @nbytes: The amount of data to read

 */

MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes)

{

    const uint8_t *buffer = xbuffer;

    int i, j;

    unsigned nbits, nlimbs;

    mpi_limb_t a;

    MPI val = NULL;

​

    while (nbytes > 0 && buffer[0] == 0) {

        buffer++;

        nbytes--;

    }

​

    nbits = nbytes * 8;

    if (nbits > MAX_EXTERN_MPI_BITS) {

        pr_info("MPI: mpi too large (%u bits)\n", nbits);

        return NULL;

    }

    if (nbytes > 0)

        nbits -= count_leading_zeros(buffer[0]) - (BITS_PER_LONG - 8);

​

    nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);

    val = mpi_alloc(nlimbs);

    if (!val)

        return NULL;

    val->nbits = nbits;

    val->sign = 0;

    val->nlimbs = nlimbs;

​

    if (nbytes > 0) {

        i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;

        i %= BYTES_PER_MPI_LIMB;

        for (j = nlimbs; j > 0; j--) {

            a = 0;

            for (; i < BYTES_PER_MPI_LIMB; i++) {

                a <<= 8;

                a |= *buffer++;

            }

            i = 0;

            val->d[j - 1] = a;

        }

    }

    return val;

}

EXPORT_SYMBOL_GPL(mpi_read_raw_data);

​

MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread)

{

    const uint8_t *buffer = xbuffer;

    unsigned int nbits, nbytes;

    MPI val;

​

    if (*ret_nread < 2)

        return ERR_PTR(-EINVAL);

    nbits = buffer[0] << 8 | buffer[1];

​

    if (nbits > MAX_EXTERN_MPI_BITS) {

        pr_info("MPI: mpi too large (%u bits)\n", nbits);