text: /* mpiutil.ac  -  Utility functions for MPI
   * Copyright (C) 1998, 2000, 2001, 2002, 2003,
   *               2007  Free Software Foundation, Inc.
   *
   * This file is part of Libgcrypt.
   *
   * Libgcrypt is free software; you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as
   * published by the Free Software Foundation; either version 2.1 of
   * the License, or (at your option) any later version.
   *
   * Libgcrypt 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 Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this program; if not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <config.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "g10lib.h"
  #include "mpi-internal.h"
  #include "mod-source-info.h"
  
  
  const char *
  _gcry_mpi_get_hw_config (void)
  {
    return mod_source_info + 1;
  }
  
  
  /****************
   * 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 :-(.  New code
   *	  should use mpi_new.
   */
  gcry_mpi_t
  _gcry_mpi_alloc( unsigned nlimbs )
  {
      gcry_mpi_t a;
  
      a = gcry_xmalloc( sizeof *a );
      a->d = nlimbs? mpi_alloc_limb_space( nlimbs, 0 ) : NULL;
      a->alloced = nlimbs;
      a->nlimbs = 0;
      a->sign = 0;
      a->flags = 0;
      return a;
  }
  
  void
  _gcry_mpi_m_check( gcry_mpi_t a )
  {
      _gcry_check_heap(a);
      _gcry_check_heap(a->d);
  }
  
  gcry_mpi_t
  _gcry_mpi_alloc_secure( unsigned nlimbs )
  {
      gcry_mpi_t a;
  
      a = gcry_xmalloc( sizeof *a );
      a->d = nlimbs? mpi_alloc_limb_space( nlimbs, 1 ) : NULL;
      a->alloced = nlimbs;
      a->flags = 1;
      a->nlimbs = 0;
      a->sign = 0;
      return a;
  }
  
  
  
  mpi_ptr_t
  _gcry_mpi_alloc_limb_space( unsigned int nlimbs, int secure )
  {
      mpi_ptr_t p;
      size_t len;
  
      len = (nlimbs ? nlimbs : 1) * sizeof (mpi_limb_t);
      p = secure ? gcry_xmalloc_secure (len) : gcry_xmalloc (len);
      if (! nlimbs)
        *p = 0;
  
      return p;
  }
  
  void
  _gcry_mpi_free_limb_space( mpi_ptr_t a, unsigned int nlimbs)
  {
    if (a)
      {
        size_t len = nlimbs * sizeof(mpi_limb_t);
  
        /* If we have information on the number of allocated limbs, we
           better wipe that space out.  This is a failsafe feature if
           secure memory has been disabled or was not properly
           implemented in user provided allocation functions. */
        if (len)
          wipememory (a, len);
        gcry_free(a);
      }
  }
  
  
  void
  _gcry_mpi_assign_limb_space( gcry_mpi_t a, mpi_ptr_t ap, unsigned int nlimbs )
  {
    _gcry_mpi_free_limb_space (a->d, a->alloced);
    a->d = ap;
    a->alloced = nlimbs;
  }
  
  
  
  /****************
   * Resize the array of A to NLIMBS. The additional space is cleared
   * (set to 0).
   */
  void
  _gcry_mpi_resize (gcry_mpi_t a, unsigned nlimbs)
  {
    size_t i;
  
    if (nlimbs <= a->alloced)
      {
        /* We only need to clear the new space (this is a nop if the
           limb space is already of the correct size. */
        for (i=a->nlimbs; i < a->alloced; i++)
          a->d[i] = 0;
        return;
      }
  
    /* Actually resize the limb space.  */
    if (a->d)
      {
        a->d = gcry_xrealloc (a->d, nlimbs * sizeof (mpi_limb_t));
        for (i=a->alloced; i < nlimbs; i++)
          a->d[i] = 0;
      }
    else
      {
        if (a->flags & 1)
  	/* Secure memory is wanted.  */
  	a->d = gcry_xcalloc_secure (nlimbs , sizeof (mpi_limb_t));
        else
  	/* Standard memory.  */
  	a->d = gcry_xcalloc (nlimbs , sizeof (mpi_limb_t));
      }
    a->alloced = nlimbs;
  }
  
  void
  _gcry_mpi_clear( gcry_mpi_t a )
  {
      a->nlimbs = 0;
      a->flags = 0;
  }
  
  
  void
  _gcry_mpi_free( gcry_mpi_t a )
  {
    if (!a )
      return;
    if ((a->flags & 4))
      gcry_free( a->d );
    else
      {
        _gcry_mpi_free_limb_space(a->d, a->alloced);
      }
    if ((a->flags & ~7))
      log_bug("invalid flag value in mpi\n");
    gcry_free(a);
  }
  
  static void
  mpi_set_secure( gcry_mpi_t a )
  {
    mpi_ptr_t ap, bp;
  
    if ( (a->flags & 1) )
      return;
    a->flags |= 1;
    ap = a->d;
    if (!a->nlimbs)
      {
        gcry_assert (!ap);
        return;
      }
    bp = mpi_alloc_limb_space (a->nlimbs, 1);
    MPN_COPY( bp, ap, a->nlimbs );
    a->d = bp;
    _gcry_mpi_free_limb_space (ap, a->alloced);
  }
  
  
  gcry_mpi_t
  gcry_mpi_set_opaque( gcry_mpi_t a, void *p, unsigned int nbits )
  {
    if (!a)
      a = mpi_alloc(0);
  
    if( a->flags & 4 )
      gcry_free( a->d );
    else
      _gcry_mpi_free_limb_space (a->d, a->alloced);
  
    a->d = p;
    a->alloced = 0;
    a->nlimbs = 0;
    a->sign  = nbits;
    a->flags = 4;
    return a;
  }
  
  
  void *
  gcry_mpi_get_opaque( gcry_mpi_t a, unsigned int *nbits )
  {
      if( !(a->flags & 4) )
  	log_bug("mpi_get_opaque on normal mpi\n");
      if( nbits )
  	*nbits = a->sign;
      return a->d;
  }
  
  
  /****************
   * Note: This copy function should not interpret the MPI
   *	 but copy it transparently.
   */
  gcry_mpi_t
  gcry_mpi_copy( gcry_mpi_t a )
  {
      int i;
      gcry_mpi_t b;
  
      if( a && (a->flags & 4) ) {
  	void *p = gcry_is_secure(a->d)? gcry_xmalloc_secure( (a->sign+7)/8 )
  				     : gcry_xmalloc( (a->sign+7)/8 );
  	memcpy( p, a->d, (a->sign+7)/8 );
  	b = gcry_mpi_set_opaque( NULL, p, a->sign );
      }
      else if( a ) {
  	b = mpi_is_secure(a)? mpi_alloc_secure( a->nlimbs )
  			    : mpi_alloc( a->nlimbs );
  	b->nlimbs = a->nlimbs;
  	b->sign = a->sign;
  	b->flags  = a->flags;
  	for(i=0; i < b->nlimbs; i++ )
  	    b->d[i] = a->d[i];
      }
      else
  	b = NULL;
      return b;
  }
  
  
  /****************
   * This function allocates an MPI which is optimized to hold
   * a value as large as the one given in the argument and allocates it
   * with the same flags as A.
   */
  gcry_mpi_t
  _gcry_mpi_alloc_like( gcry_mpi_t a )
  {
      gcry_mpi_t b;
  
      if( a && (a->flags & 4) ) {
  	int n = (a->sign+7)/8;
  	void *p = gcry_is_secure(a->d)? gcry_malloc_secure( n )
  				     : gcry_malloc( n );
  	memcpy( p, a->d, n );
  	b = gcry_mpi_set_opaque( NULL, p, a->sign );
      }
      else if( a ) {
  	b = mpi_is_secure(a)? mpi_alloc_secure( a->nlimbs )
  			    : mpi_alloc( a->nlimbs );
  	b->nlimbs = 0;
  	b->sign = 0;
  	b->flags = a->flags;
      }
      else
  	b = NULL;
      return b;
  }
  
  
  gcry_mpi_t
  gcry_mpi_set( gcry_mpi_t w, gcry_mpi_t u)
  {
    mpi_ptr_t wp, up;
    mpi_size_t usize = u->nlimbs;
    int usign = u->sign;
  
    if (!w)
      w = _gcry_mpi_alloc( mpi_get_nlimbs(u) );
    RESIZE_IF_NEEDED(w, usize);
    wp = w->d;
    up = u->d;
    MPN_COPY( wp, up, usize );
    w->nlimbs = usize;
    w->flags = u->flags;
    w->sign = usign;
    return w;
  }
  
  
  gcry_mpi_t
  gcry_mpi_set_ui( gcry_mpi_t w, unsigned long u)
  {
    if (!w)
      w = _gcry_mpi_alloc (1);
    /* FIXME: If U is 0 we have no need to resize and thus possible
       allocating the the limbs. */
    RESIZE_IF_NEEDED(w, 1);
    w->d[0] = u;
    w->nlimbs = u? 1:0;
    w->sign = 0;
    w->flags = 0;
    return w;
  }
  
  gcry_err_code_t
  _gcry_mpi_get_ui (gcry_mpi_t w, unsigned long *u)
  {
    gcry_err_code_t err = GPG_ERR_NO_ERROR;
    unsigned long x = 0;
  
    if (w->nlimbs > 1)
      err = GPG_ERR_TOO_LARGE;
    else if (w->nlimbs == 1)
      x = w->d[0];
    else
      x = 0;
  
    if (! err)
      *u = x;
  
    return err;
  }
  
  gcry_error_t
  gcry_mpi_get_ui (gcry_mpi_t w, unsigned long *u)
  {
    gcry_err_code_t err = GPG_ERR_NO_ERROR;
  
    err = _gcry_mpi_get_ui (w, u);
  
    return gcry_error (err);
  }
  
  gcry_mpi_t
  _gcry_mpi_alloc_set_ui( unsigned long u)
  {
      gcry_mpi_t w = mpi_alloc(1);
      w->d[0] = u;
      w->nlimbs = u? 1:0;
      w->sign = 0;
      return w;
  }
  
  void
  gcry_mpi_swap( gcry_mpi_t a, gcry_mpi_t b)
  {
      struct gcry_mpi tmp;
  
      tmp = *a; *a = *b; *b = tmp;
  }
  
  
  gcry_mpi_t
  gcry_mpi_new( unsigned int nbits )
  {
      return _gcry_mpi_alloc ( (nbits+BITS_PER_MPI_LIMB-1)
                               / BITS_PER_MPI_LIMB );
  }
  
  
  gcry_mpi_t
  gcry_mpi_snew( unsigned int nbits )
  {
    return _gcry_mpi_alloc_secure ( (nbits+BITS_PER_MPI_LIMB-1)
                                    / BITS_PER_MPI_LIMB );
  }
  
  void
  gcry_mpi_release( gcry_mpi_t a )
  {
      _gcry_mpi_free( a );
  }
  
  void
  gcry_mpi_randomize( gcry_mpi_t w,
  		    unsigned int nbits, enum gcry_random_level level )
  {
    unsigned char *p;
    size_t nbytes = (nbits+7)/8;
  
    if (level == GCRY_WEAK_RANDOM)
      {
        p = mpi_is_secure(w) ? gcry_xmalloc_secure (nbytes)
                             : gcry_xmalloc (nbytes);
        gcry_create_nonce (p, nbytes);
      }
    else
      {
        p = mpi_is_secure(w) ? gcry_random_bytes_secure (nbytes, level)
                             : gcry_random_bytes (nbytes, level);
      }
    _gcry_mpi_set_buffer( w, p, nbytes, 0 );
    gcry_free (p);
  }
  
  
  void
  gcry_mpi_set_flag( gcry_mpi_t a, enum gcry_mpi_flag flag )
  {
      switch( flag ) {
        case GCRYMPI_FLAG_SECURE:  mpi_set_secure(a); break;
        case GCRYMPI_FLAG_OPAQUE:
        default: log_bug("invalid flag value\n");
      }
  }
  
  void
  gcry_mpi_clear_flag( gcry_mpi_t a, enum gcry_mpi_flag flag )
  {
    (void)a; /* Not yet used. */
  
    switch (flag)
      {
      case GCRYMPI_FLAG_SECURE:
      case GCRYMPI_FLAG_OPAQUE:
      default: log_bug("invalid flag value\n");
      }
  }
  
  int
  gcry_mpi_get_flag( gcry_mpi_t a, enum gcry_mpi_flag flag )
  {
    switch (flag)
      {
      case GCRYMPI_FLAG_SECURE: return (a->flags & 1);
      case GCRYMPI_FLAG_OPAQUE: return (a->flags & 4);
      default: log_bug("invalid flag value\n");
      }
    /*NOTREACHED*/
    return 0;
  }
  