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751 lines
16 KiB
751 lines
16 KiB
/* mpicoder.c - Coder for the external representation of MPIs |
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* Copyright (C) 1998, 1999 Free Software Foundation, Inc. |
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* |
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* This file is part of GnuPG. |
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* |
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* GnuPG is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* GnuPG is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA |
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*/ |
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|
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#include <linux/bitops.h> |
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#include <linux/count_zeros.h> |
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#include <linux/byteorder/generic.h> |
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#include <linux/scatterlist.h> |
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#include <linux/string.h> |
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#include "mpi-internal.h" |
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#define MAX_EXTERN_SCAN_BYTES (16*1024*1024) |
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#define MAX_EXTERN_MPI_BITS 16384 |
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|
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/** |
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* mpi_read_raw_data - Read a raw byte stream as a positive integer |
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* @xbuffer: The data to read |
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* @nbytes: The amount of data to read |
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*/ |
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MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes) |
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{ |
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const uint8_t *buffer = xbuffer; |
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int i, j; |
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unsigned nbits, nlimbs; |
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mpi_limb_t a; |
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MPI val = NULL; |
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while (nbytes > 0 && buffer[0] == 0) { |
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buffer++; |
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nbytes--; |
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} |
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nbits = nbytes * 8; |
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if (nbits > MAX_EXTERN_MPI_BITS) { |
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pr_info("MPI: mpi too large (%u bits)\n", nbits); |
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return NULL; |
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} |
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if (nbytes > 0) |
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nbits -= count_leading_zeros(buffer[0]) - (BITS_PER_LONG - 8); |
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nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB); |
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val = mpi_alloc(nlimbs); |
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if (!val) |
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return NULL; |
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val->nbits = nbits; |
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val->sign = 0; |
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val->nlimbs = nlimbs; |
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if (nbytes > 0) { |
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i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; |
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i %= BYTES_PER_MPI_LIMB; |
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for (j = nlimbs; j > 0; j--) { |
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a = 0; |
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for (; i < BYTES_PER_MPI_LIMB; i++) { |
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a <<= 8; |
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a |= *buffer++; |
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} |
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i = 0; |
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val->d[j - 1] = a; |
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} |
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} |
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return val; |
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} |
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EXPORT_SYMBOL_GPL(mpi_read_raw_data); |
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MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread) |
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{ |
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const uint8_t *buffer = xbuffer; |
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unsigned int nbits, nbytes; |
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MPI val; |
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if (*ret_nread < 2) |
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return ERR_PTR(-EINVAL); |
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nbits = buffer[0] << 8 | buffer[1]; |
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if (nbits > MAX_EXTERN_MPI_BITS) { |
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pr_info("MPI: mpi too large (%u bits)\n", nbits); |
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return ERR_PTR(-EINVAL); |
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} |
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nbytes = DIV_ROUND_UP(nbits, 8); |
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if (nbytes + 2 > *ret_nread) { |
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pr_info("MPI: mpi larger than buffer nbytes=%u ret_nread=%u\n", |
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nbytes, *ret_nread); |
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return ERR_PTR(-EINVAL); |
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} |
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val = mpi_read_raw_data(buffer + 2, nbytes); |
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if (!val) |
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return ERR_PTR(-ENOMEM); |
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*ret_nread = nbytes + 2; |
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return val; |
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} |
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EXPORT_SYMBOL_GPL(mpi_read_from_buffer); |
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|
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/**************** |
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* Fill the mpi VAL from the hex string in STR. |
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*/ |
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int mpi_fromstr(MPI val, const char *str) |
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{ |
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int sign = 0; |
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int prepend_zero = 0; |
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int i, j, c, c1, c2; |
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unsigned int nbits, nbytes, nlimbs; |
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mpi_limb_t a; |
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if (*str == '-') { |
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sign = 1; |
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str++; |
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} |
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/* Skip optional hex prefix. */ |
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if (*str == '0' && str[1] == 'x') |
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str += 2; |
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nbits = strlen(str); |
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if (nbits > MAX_EXTERN_SCAN_BYTES) { |
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mpi_clear(val); |
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return -EINVAL; |
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} |
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nbits *= 4; |
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if ((nbits % 8)) |
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prepend_zero = 1; |
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nbytes = (nbits+7) / 8; |
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nlimbs = (nbytes+BYTES_PER_MPI_LIMB-1) / BYTES_PER_MPI_LIMB; |
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if (val->alloced < nlimbs) |
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mpi_resize(val, nlimbs); |
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i = BYTES_PER_MPI_LIMB - (nbytes % BYTES_PER_MPI_LIMB); |
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i %= BYTES_PER_MPI_LIMB; |
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j = val->nlimbs = nlimbs; |
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val->sign = sign; |
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for (; j > 0; j--) { |
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a = 0; |
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for (; i < BYTES_PER_MPI_LIMB; i++) { |
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if (prepend_zero) { |
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c1 = '0'; |
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prepend_zero = 0; |
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} else |
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c1 = *str++; |
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if (!c1) { |
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mpi_clear(val); |
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return -EINVAL; |
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} |
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c2 = *str++; |
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if (!c2) { |
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mpi_clear(val); |
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return -EINVAL; |
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} |
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if (c1 >= '0' && c1 <= '9') |
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c = c1 - '0'; |
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else if (c1 >= 'a' && c1 <= 'f') |
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c = c1 - 'a' + 10; |
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else if (c1 >= 'A' && c1 <= 'F') |
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c = c1 - 'A' + 10; |
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else { |
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mpi_clear(val); |
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return -EINVAL; |
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} |
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c <<= 4; |
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if (c2 >= '0' && c2 <= '9') |
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c |= c2 - '0'; |
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else if (c2 >= 'a' && c2 <= 'f') |
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c |= c2 - 'a' + 10; |
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else if (c2 >= 'A' && c2 <= 'F') |
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c |= c2 - 'A' + 10; |
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else { |
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mpi_clear(val); |
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return -EINVAL; |
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} |
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a <<= 8; |
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a |= c; |
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} |
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i = 0; |
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val->d[j-1] = a; |
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} |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(mpi_fromstr); |
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MPI mpi_scanval(const char *string) |
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{ |
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MPI a; |
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a = mpi_alloc(0); |
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if (!a) |
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return NULL; |
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if (mpi_fromstr(a, string)) { |
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mpi_free(a); |
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return NULL; |
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} |
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mpi_normalize(a); |
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return a; |
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} |
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EXPORT_SYMBOL_GPL(mpi_scanval); |
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static int count_lzeros(MPI a) |
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{ |
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mpi_limb_t alimb; |
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int i, lzeros = 0; |
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for (i = a->nlimbs - 1; i >= 0; i--) { |
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alimb = a->d[i]; |
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if (alimb == 0) { |
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lzeros += sizeof(mpi_limb_t); |
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} else { |
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lzeros += count_leading_zeros(alimb) / 8; |
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break; |
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} |
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} |
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return lzeros; |
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} |
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/** |
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* mpi_read_buffer() - read MPI to a buffer provided by user (msb first) |
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* |
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* @a: a multi precision integer |
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* @buf: buffer to which the output will be written to. Needs to be at |
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* least mpi_get_size(a) long. |
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* @buf_len: size of the buf. |
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* @nbytes: receives the actual length of the data written on success and |
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* the data to-be-written on -EOVERFLOW in case buf_len was too |
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* small. |
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* @sign: if not NULL, it will be set to the sign of a. |
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* |
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* Return: 0 on success or error code in case of error |
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*/ |
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int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes, |
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int *sign) |
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{ |
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uint8_t *p; |
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#if BYTES_PER_MPI_LIMB == 4 |
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__be32 alimb; |
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#elif BYTES_PER_MPI_LIMB == 8 |
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__be64 alimb; |
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#else |
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#error please implement for this limb size. |
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#endif |
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unsigned int n = mpi_get_size(a); |
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int i, lzeros; |
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if (!buf || !nbytes) |
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return -EINVAL; |
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if (sign) |
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*sign = a->sign; |
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lzeros = count_lzeros(a); |
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if (buf_len < n - lzeros) { |
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*nbytes = n - lzeros; |
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return -EOVERFLOW; |
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} |
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p = buf; |
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*nbytes = n - lzeros; |
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for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB, |
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lzeros %= BYTES_PER_MPI_LIMB; |
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i >= 0; i--) { |
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#if BYTES_PER_MPI_LIMB == 4 |
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alimb = cpu_to_be32(a->d[i]); |
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#elif BYTES_PER_MPI_LIMB == 8 |
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alimb = cpu_to_be64(a->d[i]); |
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#else |
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#error please implement for this limb size. |
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#endif |
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memcpy(p, (u8 *)&alimb + lzeros, BYTES_PER_MPI_LIMB - lzeros); |
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p += BYTES_PER_MPI_LIMB - lzeros; |
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lzeros = 0; |
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} |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(mpi_read_buffer); |
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|
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/* |
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* mpi_get_buffer() - Returns an allocated buffer with the MPI (msb first). |
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* Caller must free the return string. |
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* This function does return a 0 byte buffer with nbytes set to zero if the |
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* value of A is zero. |
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* |
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* @a: a multi precision integer. |
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* @nbytes: receives the length of this buffer. |
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* @sign: if not NULL, it will be set to the sign of the a. |
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* |
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* Return: Pointer to MPI buffer or NULL on error |
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*/ |
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void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign) |
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{ |
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uint8_t *buf; |
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unsigned int n; |
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int ret; |
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if (!nbytes) |
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return NULL; |
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n = mpi_get_size(a); |
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if (!n) |
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n++; |
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buf = kmalloc(n, GFP_KERNEL); |
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if (!buf) |
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return NULL; |
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ret = mpi_read_buffer(a, buf, n, nbytes, sign); |
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if (ret) { |
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kfree(buf); |
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return NULL; |
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} |
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return buf; |
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} |
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EXPORT_SYMBOL_GPL(mpi_get_buffer); |
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/** |
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* mpi_write_to_sgl() - Funnction exports MPI to an sgl (msb first) |
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* |
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* This function works in the same way as the mpi_read_buffer, but it |
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* takes an sgl instead of u8 * buf. |
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* |
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* @a: a multi precision integer |
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* @sgl: scatterlist to write to. Needs to be at least |
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* mpi_get_size(a) long. |
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* @nbytes: the number of bytes to write. Leading bytes will be |
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* filled with zero. |
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* @sign: if not NULL, it will be set to the sign of a. |
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* |
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* Return: 0 on success or error code in case of error |
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*/ |
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int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned nbytes, |
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int *sign) |
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{ |
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u8 *p, *p2; |
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#if BYTES_PER_MPI_LIMB == 4 |
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__be32 alimb; |
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#elif BYTES_PER_MPI_LIMB == 8 |
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__be64 alimb; |
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#else |
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#error please implement for this limb size. |
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#endif |
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unsigned int n = mpi_get_size(a); |
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struct sg_mapping_iter miter; |
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int i, x, buf_len; |
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int nents; |
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if (sign) |
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*sign = a->sign; |
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if (nbytes < n) |
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return -EOVERFLOW; |
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nents = sg_nents_for_len(sgl, nbytes); |
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if (nents < 0) |
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return -EINVAL; |
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sg_miter_start(&miter, sgl, nents, SG_MITER_ATOMIC | SG_MITER_TO_SG); |
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sg_miter_next(&miter); |
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buf_len = miter.length; |
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p2 = miter.addr; |
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while (nbytes > n) { |
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i = min_t(unsigned, nbytes - n, buf_len); |
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memset(p2, 0, i); |
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p2 += i; |
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nbytes -= i; |
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buf_len -= i; |
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if (!buf_len) { |
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sg_miter_next(&miter); |
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buf_len = miter.length; |
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p2 = miter.addr; |
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} |
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} |
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for (i = a->nlimbs - 1; i >= 0; i--) { |
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#if BYTES_PER_MPI_LIMB == 4 |
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alimb = a->d[i] ? cpu_to_be32(a->d[i]) : 0; |
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#elif BYTES_PER_MPI_LIMB == 8 |
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alimb = a->d[i] ? cpu_to_be64(a->d[i]) : 0; |
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#else |
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#error please implement for this limb size. |
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#endif |
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p = (u8 *)&alimb; |
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for (x = 0; x < sizeof(alimb); x++) { |
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*p2++ = *p++; |
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if (!--buf_len) { |
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sg_miter_next(&miter); |
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buf_len = miter.length; |
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p2 = miter.addr; |
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} |
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} |
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} |
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sg_miter_stop(&miter); |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(mpi_write_to_sgl); |
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/* |
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* mpi_read_raw_from_sgl() - Function allocates an MPI and populates it with |
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* data from the sgl |
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* |
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* This function works in the same way as the mpi_read_raw_data, but it |
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* takes an sgl instead of void * buffer. i.e. it allocates |
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* a new MPI and reads the content of the sgl to the MPI. |
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* |
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* @sgl: scatterlist to read from |
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* @nbytes: number of bytes to read |
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* |
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* Return: Pointer to a new MPI or NULL on error |
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*/ |
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MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes) |
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{ |
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struct sg_mapping_iter miter; |
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unsigned int nbits, nlimbs; |
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int x, j, z, lzeros, ents; |
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unsigned int len; |
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const u8 *buff; |
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mpi_limb_t a; |
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MPI val = NULL; |
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ents = sg_nents_for_len(sgl, nbytes); |
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if (ents < 0) |
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return NULL; |
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sg_miter_start(&miter, sgl, ents, SG_MITER_ATOMIC | SG_MITER_FROM_SG); |
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lzeros = 0; |
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len = 0; |
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while (nbytes > 0) { |
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while (len && !*buff) { |
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lzeros++; |
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len--; |
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buff++; |
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} |
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if (len && *buff) |
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break; |
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sg_miter_next(&miter); |
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buff = miter.addr; |
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len = miter.length; |
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nbytes -= lzeros; |
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lzeros = 0; |
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} |
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miter.consumed = lzeros; |
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nbytes -= lzeros; |
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nbits = nbytes * 8; |
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if (nbits > MAX_EXTERN_MPI_BITS) { |
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sg_miter_stop(&miter); |
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pr_info("MPI: mpi too large (%u bits)\n", nbits); |
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return NULL; |
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} |
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if (nbytes > 0) |
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nbits -= count_leading_zeros(*buff) - (BITS_PER_LONG - 8); |
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sg_miter_stop(&miter); |
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nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB); |
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val = mpi_alloc(nlimbs); |
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if (!val) |
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return NULL; |
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val->nbits = nbits; |
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val->sign = 0; |
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val->nlimbs = nlimbs; |
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|
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if (nbytes == 0) |
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return val; |
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j = nlimbs - 1; |
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a = 0; |
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z = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; |
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z %= BYTES_PER_MPI_LIMB; |
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while (sg_miter_next(&miter)) { |
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buff = miter.addr; |
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len = miter.length; |
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for (x = 0; x < len; x++) { |
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a <<= 8; |
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a |= *buff++; |
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if (((z + x + 1) % BYTES_PER_MPI_LIMB) == 0) { |
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val->d[j--] = a; |
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a = 0; |
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} |
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} |
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z += x; |
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} |
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return val; |
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} |
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EXPORT_SYMBOL_GPL(mpi_read_raw_from_sgl); |
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|
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/* Perform a two's complement operation on buffer P of size N bytes. */ |
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static void twocompl(unsigned char *p, unsigned int n) |
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{ |
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int i; |
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|
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for (i = n-1; i >= 0 && !p[i]; i--) |
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; |
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if (i >= 0) { |
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if ((p[i] & 0x01)) |
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p[i] = (((p[i] ^ 0xfe) | 0x01) & 0xff); |
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else if ((p[i] & 0x02)) |
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p[i] = (((p[i] ^ 0xfc) | 0x02) & 0xfe); |
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else if ((p[i] & 0x04)) |
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p[i] = (((p[i] ^ 0xf8) | 0x04) & 0xfc); |
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else if ((p[i] & 0x08)) |
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p[i] = (((p[i] ^ 0xf0) | 0x08) & 0xf8); |
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else if ((p[i] & 0x10)) |
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p[i] = (((p[i] ^ 0xe0) | 0x10) & 0xf0); |
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else if ((p[i] & 0x20)) |
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p[i] = (((p[i] ^ 0xc0) | 0x20) & 0xe0); |
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else if ((p[i] & 0x40)) |
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p[i] = (((p[i] ^ 0x80) | 0x40) & 0xc0); |
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else |
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p[i] = 0x80; |
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|
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for (i--; i >= 0; i--) |
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p[i] ^= 0xff; |
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} |
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} |
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|
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int mpi_print(enum gcry_mpi_format format, unsigned char *buffer, |
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size_t buflen, size_t *nwritten, MPI a) |
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{ |
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unsigned int nbits = mpi_get_nbits(a); |
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size_t len; |
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size_t dummy_nwritten; |
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int negative; |
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|
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if (!nwritten) |
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nwritten = &dummy_nwritten; |
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|
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/* Libgcrypt does no always care to set clear the sign if the value |
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* is 0. For printing this is a bit of a surprise, in particular |
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* because if some of the formats don't support negative numbers but |
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* should be able to print a zero. Thus we need this extra test |
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* for a negative number. |
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*/ |
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if (a->sign && mpi_cmp_ui(a, 0)) |
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negative = 1; |
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else |
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negative = 0; |
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|
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len = buflen; |
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*nwritten = 0; |
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if (format == GCRYMPI_FMT_STD) { |
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unsigned char *tmp; |
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int extra = 0; |
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unsigned int n; |
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|
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tmp = mpi_get_buffer(a, &n, NULL); |
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if (!tmp) |
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return -EINVAL; |
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|
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if (negative) { |
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twocompl(tmp, n); |
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if (!(*tmp & 0x80)) { |
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/* Need to extend the sign. */ |
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n++; |
|
extra = 2; |
|
} |
|
} else if (n && (*tmp & 0x80)) { |
|
/* Positive but the high bit of the returned buffer is set. |
|
* Thus we need to print an extra leading 0x00 so that the |
|
* output is interpreted as a positive number. |
|
*/ |
|
n++; |
|
extra = 1; |
|
} |
|
|
|
if (buffer && n > len) { |
|
/* The provided buffer is too short. */ |
|
kfree(tmp); |
|
return -E2BIG; |
|
} |
|
if (buffer) { |
|
unsigned char *s = buffer; |
|
|
|
if (extra == 1) |
|
*s++ = 0; |
|
else if (extra) |
|
*s++ = 0xff; |
|
memcpy(s, tmp, n-!!extra); |
|
} |
|
kfree(tmp); |
|
*nwritten = n; |
|
return 0; |
|
} else if (format == GCRYMPI_FMT_USG) { |
|
unsigned int n = (nbits + 7)/8; |
|
|
|
/* Note: We ignore the sign for this format. */ |
|
/* FIXME: for performance reasons we should put this into |
|
* mpi_aprint because we can then use the buffer directly. |
|
*/ |
|
|
|
if (buffer && n > len) |
|
return -E2BIG; |
|
if (buffer) { |
|
unsigned char *tmp; |
|
|
|
tmp = mpi_get_buffer(a, &n, NULL); |
|
if (!tmp) |
|
return -EINVAL; |
|
memcpy(buffer, tmp, n); |
|
kfree(tmp); |
|
} |
|
*nwritten = n; |
|
return 0; |
|
} else if (format == GCRYMPI_FMT_PGP) { |
|
unsigned int n = (nbits + 7)/8; |
|
|
|
/* The PGP format can only handle unsigned integers. */ |
|
if (negative) |
|
return -EINVAL; |
|
|
|
if (buffer && n+2 > len) |
|
return -E2BIG; |
|
|
|
if (buffer) { |
|
unsigned char *tmp; |
|
unsigned char *s = buffer; |
|
|
|
s[0] = nbits >> 8; |
|
s[1] = nbits; |
|
|
|
tmp = mpi_get_buffer(a, &n, NULL); |
|
if (!tmp) |
|
return -EINVAL; |
|
memcpy(s+2, tmp, n); |
|
kfree(tmp); |
|
} |
|
*nwritten = n+2; |
|
return 0; |
|
} else if (format == GCRYMPI_FMT_SSH) { |
|
unsigned char *tmp; |
|
int extra = 0; |
|
unsigned int n; |
|
|
|
tmp = mpi_get_buffer(a, &n, NULL); |
|
if (!tmp) |
|
return -EINVAL; |
|
|
|
if (negative) { |
|
twocompl(tmp, n); |
|
if (!(*tmp & 0x80)) { |
|
/* Need to extend the sign. */ |
|
n++; |
|
extra = 2; |
|
} |
|
} else if (n && (*tmp & 0x80)) { |
|
n++; |
|
extra = 1; |
|
} |
|
|
|
if (buffer && n+4 > len) { |
|
kfree(tmp); |
|
return -E2BIG; |
|
} |
|
|
|
if (buffer) { |
|
unsigned char *s = buffer; |
|
|
|
*s++ = n >> 24; |
|
*s++ = n >> 16; |
|
*s++ = n >> 8; |
|
*s++ = n; |
|
if (extra == 1) |
|
*s++ = 0; |
|
else if (extra) |
|
*s++ = 0xff; |
|
memcpy(s, tmp, n-!!extra); |
|
} |
|
kfree(tmp); |
|
*nwritten = 4+n; |
|
return 0; |
|
} else if (format == GCRYMPI_FMT_HEX) { |
|
unsigned char *tmp; |
|
int i; |
|
int extra = 0; |
|
unsigned int n = 0; |
|
|
|
tmp = mpi_get_buffer(a, &n, NULL); |
|
if (!tmp) |
|
return -EINVAL; |
|
if (!n || (*tmp & 0x80)) |
|
extra = 2; |
|
|
|
if (buffer && 2*n + extra + negative + 1 > len) { |
|
kfree(tmp); |
|
return -E2BIG; |
|
} |
|
if (buffer) { |
|
unsigned char *s = buffer; |
|
|
|
if (negative) |
|
*s++ = '-'; |
|
if (extra) { |
|
*s++ = '0'; |
|
*s++ = '0'; |
|
} |
|
|
|
for (i = 0; i < n; i++) { |
|
unsigned int c = tmp[i]; |
|
|
|
*s++ = (c >> 4) < 10 ? '0'+(c>>4) : 'A'+(c>>4)-10; |
|
c &= 15; |
|
*s++ = c < 10 ? '0'+c : 'A'+c-10; |
|
} |
|
*s++ = 0; |
|
*nwritten = s - buffer; |
|
} else { |
|
*nwritten = 2*n + extra + negative + 1; |
|
} |
|
kfree(tmp); |
|
return 0; |
|
} else |
|
return -EINVAL; |
|
} |
|
EXPORT_SYMBOL_GPL(mpi_print);
|
|
|