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   1 /* -*-c-*-
   2  *
   3  * $Id: mp-mem.c,v 1.5 2001/06/16 12:57:00 mdw Exp $
   4  *
   5  * Memory management for multiprecision numbers
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: mp-mem.c,v $
  33  * Revision 1.5  2001/06/16 12:57:00  mdw
  34  * Implement some missing functions.
  35  *
  36  * Revision 1.4  2001/02/03 12:00:29  mdw
  37  * Now @mp_drop@ checks its argument is non-NULL before attempting to free
  38  * it.  Note that the macro version @MP_DROP@ doesn't do this.
  39  *
  40  * Revision 1.3  2000/06/17 11:45:09  mdw
  41  * Major memory management overhaul.  Added arena support.  Use the secure
  42  * arena for secret integers.  Replace and improve the MP management macros
  43  * (e.g., replace MP_MODIFY by MP_DEST).
  44  *
  45  * Revision 1.2  1999/12/10 23:19:02  mdw
  46  * Improve error-checking.
  47  *
  48  * Revision 1.1  1999/11/17 18:02:16  mdw
  49  * New multiprecision integer arithmetic suite.
  50  *
  51  */
  52
  53 /*----- Header files ------------------------------------------------------*/
  54
  55 #include <mLib/sub.h>
  56
  57
  58 #include "mp.h"
  59
  60 /*----- Main code ---------------------------------------------------------*/
  61
  62 /* --- @mp_new@ --- *
  63  *
  64  * Arguments:   @size_t sz@ = size of vector required
  65  *              @unsigned f@ = flags to set
  66  *
  67  * Returns:     Pointer to a new MP structure.
  68  *
  69  * Use:         Allocates a new multiprecision integer.  The data space is
  70  *              allocated from either the standard global or secret arena,
  71  *              depending on the initial flags requested.
  72  */
  73
  74 mp *mp_new(size_t sz, unsigned f)
  75 {
  76   mp *m = CREATE(mp);
  77   m->a = (f & MP_BURN) ? MPARENA_SECURE : MPARENA_GLOBAL;
  78   m->v = mpalloc(m->a, sz);
  79   m->vl = m->v + sz;
  80   m->sz = sz;
  81   m->f = f & ~(MP_CONST | MP_DESTROYED);
  82   m->ref = 1;
  83   return (m);
  84 }
  85
  86 /* --- @mp_create@ --- *
  87  *
  88  * Arguments:   @size_t sz@ = size of vector required
  89  *
  90  * Returns:     Pointer to pristine new MP structure with enough memory
  91  *              bolted onto it.
  92  *
  93  * Use:         Creates a new multiprecision integer, initially zero.  The
  94  *              integer has a single reference.
  95  */
  96
  97 mp *mp_create(size_t sz)
  98 {
  99   mp *m = CREATE(mp);
 100   m->v = mpalloc(MPARENA_GLOBAL, sz);
 101   m->vl = m->v + sz;
 102   m->sz = sz;
 103   m->a = MPARENA_GLOBAL;
 104   m->f = MP_UNDEF;
 105   m->ref = 1;
 106   return (m);
 107 }
 108
 109 /* --- @mp_createsecure@ --- *
 110  *
 111  * Arguments:   @size_t sz@ = size of vector required
 112  *
 113  * Returns:     Pointer to pristine new MP structure with enough memory
 114  *              bolted onto it.
 115  *
 116  * Use:         Creates a new multiprecision integer with indeterminate
 117  *              contents.  The integer has a single reference.  The integer's
 118  *              data space is allocated from the secure arena.  Its burn flag
 119  *              is set.
 120  */
 121
 122 mp *mp_createsecure(size_t sz)
 123 {
 124   mp *m = CREATE(mp);
 125   m->v = mpalloc(MPARENA_SECURE, sz);
 126   m->vl = m->v + sz;
 127   m->sz = sz;
 128   m->a = MPARENA_SECURE;
 129   m->f = MP_UNDEF | MP_BURN;
 130   m->ref = 1;
 131   return (m);
 132 }
 133
 134 /* --- @mp_build@ --- *
 135  *
 136  * Arguments:   @mp *m@ = pointer to an MP block to fill in
 137  *              @mpw *v@ = pointer to a word array
 138  *              @mpw *vl@ = pointer just past end of array
 139  *
 140  * Returns:     ---
 141  *
 142  * Use:         Creates a multiprecision integer representing some smallish
 143  *              number.  You must provide storage for the number and dispose
 144  *              of it when you've finished with it.  The number is marked as
 145  *              constant while it exists.
 146  */
 147
 148 void mp_build(mp *m, mpw *v, mpw *vl)
 149 {
 150   m->v = v;
 151   m->vl = vl;
 152   m->sz = vl - v;
 153   m->f = MP_CONST;
 154   m->ref = 1;
 155 }
 156
 157 /* --- @mp_destroy@ --- *
 158  *
 159  * Arguments:   @mp *m@ = pointer to a multiprecision integer
 160  *
 161  * Returns:     ---
 162  *
 163  * Use:         Destroys a multiprecision integer. The reference count isn't
 164  *              checked.  Don't use this function if you don't know what
 165  *              you're doing: use @mp_drop@ instead.
 166  */
 167
 168 void mp_destroy(mp *m)
 169 {
 170   assert(((void)"Destroying a free integer", !(m->f & MP_DESTROYED)));
 171   assert(((void)"Attempted to destroy a constant", !(m->f & MP_CONST)));
 172   if (m->f & MP_BURN)
 173     memset(m->v, 0, MPWS(m->sz));
 174   mpfree(m->a, m->v);
 175   m->f |= MP_DESTROYED;
 176   DESTROY(m);
 177 }
 178
 179 /* --- @mp_copy@ --- *
 180  *
 181  * Arguments:   @mp *m@ = pointer to a multiprecision integer
 182  *
 183  * Returns:     A copy of the given multiprecision integer.
 184  *
 185  * Use:         Copies the given integer.  In fact you just get another
 186  *              reference to the same old one again.
 187  */
 188
 189 mp *mp_copy(mp *m) { return MP_COPY(m); }
 190
 191 /* --- @mp_drop@ --- *
 192  *
 193  * Arguments:   @mp *m@ = pointer to a multiprecision integer
 194  *
 195  * Returns:     ---
 196  *
 197  * Use:         Drops a reference to an integer which isn't wanted any more.
 198  *              If there are no more references, the integer is destroyed.
 199  */
 200
 201 void mp_drop(mp *m) { if (m) MP_DROP(m); }
 202
 203 /* --- @mp_split@ --- *
 204  *
 205  * Arguments:   @mp *m@ = pointer to a multiprecision integer
 206  *
 207  * Returns:     A reference to the same integer, possibly with a different
 208  *              address.
 209  *
 210  * Use:         Splits off a modifiable version of the integer referred to.
 211  */
 212
 213 mp *mp_split(mp *m) { MP_SPLIT(m); return (m); }
 214
 215 /* --- @mp_resize@ --- *
 216  *
 217  * Arguments:   @mp *m@ = pointer to a multiprecision integer
 218  *              @size_t sz@ = new size
 219  *
 220  * Returns:     ---
 221  *
 222  * Use:         Changes an integer's size.  The length and value are not
 223  *              changed.  It is an error to
 224  */
 225
 226 void mp_resize(mp *m, size_t sz) { MP_RESIZE(m, sz); }
 227
 228 /* --- @mp_ensure@ --- *
 229  *
 230  * Arguments:   @mp *m@ = pointer to a multiprecision integer
 231  *              @size_t sz@ = required length
 232  *
 233  * Returns:     ---
 234  *
 235  * Use:         Changes an integer's length.  If there is not enough space
 236  *              allocated for the new length then the size is increased.  It
 237  */
 238
 239 void mp_ensure(mp *m, size_t sz) { MP_ENSURE(m, sz); }
 240
 241 /* --- @mp_dest@ --- *
 242  *
 243  * Arguments:   @mp *m@ = a suggested destination integer
 244  *              @size_t sz@ = size required for result, in digits
 245  *              @unsigned f@ = various flags
 246  *
 247  * Returns:     A pointer to an appropriate destination.
 248  *
 249  * Use:         Converts a suggested destination into a real destination with
 250  *              the required properties.  If the real destination is @d@,
 251  *              then the following properties will hold:
 252  *
 253  *                * @d@ will have exactly one reference.
 254  *
 255  *                * If @m@ is not @MP_NEW@, then the contents of @m@ will not
 256  *                  change, unless @f@ has the @MP_UNDEF@ flag set.
 257  *
 258  *                * If @m@ is not @MP_NEW@, then he reference count of @m@ on
 259  *                  entry is equal to the sum of the counts of @d@ and @m@ on
 260  *                  exit.
 261  *
 262  *                * The size of @d@ will be at least @sz@.
 263  *
 264  *                * If @f@ has the @MP_BURN@ flag set, then @d@ will be
 265  *                  allocated from @MPARENA_SECURE@.
 266  *
 267  *              Understanding this function is crucial to using Catacomb's
 268  *              multiprecision integer library effectively.
 269  */
 270
 271 mp *mp_dest(mp *m, size_t sz, unsigned f)
 272 {
 273   /* --- If no destination, make one --- */
 274
 275   if (m == MP_NEWSEC)
 276     m = mp_new(sz, f | MP_UNDEF | MP_BURN);
 277   else if (m == MP_NEW)
 278     m = mp_new(sz, f | MP_UNDEF);
 279   else {
 280     size_t len = MP_LEN(m);
 281     unsigned undef = (m->f | f) & MP_UNDEF;
 282
 283     /* --- If the value must be preserved, the block can't shrink --- */
 284
 285     if (!undef && sz < len)
 286       sz = len;
 287
 288     /* --- Otherwise check whether the destination is suitable --- */
 289
 290     if (m->ref > 1 || (m->f & MP_CONST) ||
 291         m->sz > len || !((f & ~m->f) & MP_BURN)) {
 292
 293       /* --- No -- allocate a new buffer --- *
 294        *
 295        * The buffer must be secure if (a) the caller requested a secure
 296        * buffer, or (b) the old buffer is secure and I'm not allowed to
 297        * discard the old contents.
 298        */
 299
 300       mparena *a;
 301       mpw *v;
 302
 303       if ((f & MP_BURN) || (!undef && (m->f & MP_BURN)))
 304         a = MPARENA_SECURE;
 305       else
 306         a = MPARENA_GLOBAL;
 307       v = mpalloc(a, sz);
 308
 309       /* --- Copy the data over --- */
 310
 311       if (!undef) {
 312         memcpy(v, m->v, MPWS(len));
 313         if (sz - len > 0)
 314           memset(v + len, 0, MPWS(sz - len));
 315       }
 316
 317       /* --- If @m@ has other references, make a new node --- *
 318        *
 319        * Otherwise dispose of the old buffer.
 320        */
 321
 322       if (!(m->f & MP_CONST) && m->ref == 1) {
 323         if (m->f & MP_BURN)
 324           memset(m->v, 0, MPWS(m->sz));
 325         mpfree(m->a, m->v);
 326       } else {
 327         mp *mm = CREATE(mp);
 328         mm->ref = 1;
 329         mm->f = m->f;
 330         m->ref--;
 331         m = mm;
 332       }
 333
 334       /* --- Fix up the node --- */
 335
 336       m->v = v;
 337       m->vl = v + sz;
 338       m->sz = sz;
 339       m->f = ((m->f & ~(MP_CONST | MP_BURN)) |
 340               (f & (MP_BURN | MP_UNDEF)));
 341       m->a = a;
 342     }
 343
 344     /* --- If the number is growing in its buffer, fix it up --- */
 345
 346     else if (sz > len) {
 347       if (!undef)
 348         memset(m->vl, 0, MPWS(sz - len));
 349       m->vl = m->v + sz;
 350     }
 351   }
 352
 353   /* --- Done --- */
 354
 355   return (m);
 356 }
 357
 358 /*----- That's all, folks -------------------------------------------------*/