| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: mp-mem.c,v 1.8 2004/04/08 16:17:32 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 | /*----- Header files ------------------------------------------------------*/ |
| 31 | |
| 32 | #include <mLib/sub.h> |
| 33 | |
| 34 | |
| 35 | #include "mp.h" |
| 36 | |
| 37 | /*----- Main code ---------------------------------------------------------*/ |
| 38 | |
| 39 | /* --- @mp_new@ --- * |
| 40 | * |
| 41 | * Arguments: @size_t sz@ = size of vector required |
| 42 | * @unsigned f@ = flags to set |
| 43 | * |
| 44 | * Returns: Pointer to a new MP structure. |
| 45 | * |
| 46 | * Use: Allocates a new multiprecision integer. The data space is |
| 47 | * allocated from either the standard global or secret arena, |
| 48 | * depending on the initial flags requested. |
| 49 | */ |
| 50 | |
| 51 | mp *mp_new(size_t sz, unsigned f) |
| 52 | { |
| 53 | mp *m = CREATE(mp); |
| 54 | m->a = (f & MP_BURN) ? MPARENA_SECURE : MPARENA_GLOBAL; |
| 55 | m->v = mpalloc(m->a, sz); |
| 56 | m->vl = m->v + sz; |
| 57 | m->sz = sz; |
| 58 | m->f = f & ~(MP_CONST | MP_DESTROYED); |
| 59 | m->ref = 1; |
| 60 | return (m); |
| 61 | } |
| 62 | |
| 63 | /* --- @mp_create@ --- * |
| 64 | * |
| 65 | * Arguments: @size_t sz@ = size of vector required |
| 66 | * |
| 67 | * Returns: Pointer to pristine new MP structure with enough memory |
| 68 | * bolted onto it. |
| 69 | * |
| 70 | * Use: Creates a new multiprecision integer, initially zero. The |
| 71 | * integer has a single reference. |
| 72 | */ |
| 73 | |
| 74 | mp *mp_create(size_t sz) |
| 75 | { |
| 76 | mp *m = CREATE(mp); |
| 77 | m->v = mpalloc(MPARENA_GLOBAL, sz); |
| 78 | m->vl = m->v + sz; |
| 79 | m->sz = sz; |
| 80 | m->a = MPARENA_GLOBAL; |
| 81 | m->f = MP_UNDEF; |
| 82 | m->ref = 1; |
| 83 | return (m); |
| 84 | } |
| 85 | |
| 86 | /* --- @mp_createsecure@ --- * |
| 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 with indeterminate |
| 94 | * contents. The integer has a single reference. The integer's |
| 95 | * data space is allocated from the secure arena. Its burn flag |
| 96 | * is set. |
| 97 | */ |
| 98 | |
| 99 | mp *mp_createsecure(size_t sz) |
| 100 | { |
| 101 | mp *m = CREATE(mp); |
| 102 | m->v = mpalloc(MPARENA_SECURE, sz); |
| 103 | m->vl = m->v + sz; |
| 104 | m->sz = sz; |
| 105 | m->a = MPARENA_SECURE; |
| 106 | m->f = MP_UNDEF | MP_BURN; |
| 107 | m->ref = 1; |
| 108 | return (m); |
| 109 | } |
| 110 | |
| 111 | /* --- @mp_build@ --- * |
| 112 | * |
| 113 | * Arguments: @mp *m@ = pointer to an MP block to fill in |
| 114 | * @mpw *v@ = pointer to a word array |
| 115 | * @mpw *vl@ = pointer just past end of array |
| 116 | * |
| 117 | * Returns: --- |
| 118 | * |
| 119 | * Use: Creates a multiprecision integer representing some smallish |
| 120 | * number. You must provide storage for the number and dispose |
| 121 | * of it when you've finished with it. The number is marked as |
| 122 | * constant while it exists. |
| 123 | */ |
| 124 | |
| 125 | void mp_build(mp *m, mpw *v, mpw *vl) |
| 126 | { |
| 127 | m->v = v; |
| 128 | m->vl = vl; |
| 129 | m->sz = vl - v; |
| 130 | m->f = MP_CONST; |
| 131 | m->ref = 1; |
| 132 | } |
| 133 | |
| 134 | /* --- @mp_destroy@ --- * |
| 135 | * |
| 136 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
| 137 | * |
| 138 | * Returns: --- |
| 139 | * |
| 140 | * Use: Destroys a multiprecision integer. The reference count isn't |
| 141 | * checked. Don't use this function if you don't know what |
| 142 | * you're doing: use @mp_drop@ instead. |
| 143 | */ |
| 144 | |
| 145 | void mp_destroy(mp *m) |
| 146 | { |
| 147 | assert(((void)"Destroying a free integer", !(m->f & MP_DESTROYED))); |
| 148 | assert(((void)"Attempted to destroy a constant", !(m->f & MP_CONST))); |
| 149 | if (m->f & MP_BURN) |
| 150 | memset(m->v, 0, MPWS(m->sz)); |
| 151 | mpfree(m->a, m->v); |
| 152 | m->f |= MP_DESTROYED; |
| 153 | DESTROY(m); |
| 154 | } |
| 155 | |
| 156 | /* --- @mp_copy@ --- * |
| 157 | * |
| 158 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
| 159 | * |
| 160 | * Returns: A copy of the given multiprecision integer. |
| 161 | * |
| 162 | * Use: Copies the given integer. In fact you just get another |
| 163 | * reference to the same old one again. |
| 164 | */ |
| 165 | |
| 166 | mp *mp_copy(mp *m) { return MP_COPY(m); } |
| 167 | |
| 168 | /* --- @mp_drop@ --- * |
| 169 | * |
| 170 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
| 171 | * |
| 172 | * Returns: --- |
| 173 | * |
| 174 | * Use: Drops a reference to an integer which isn't wanted any more. |
| 175 | * If there are no more references, the integer is destroyed. |
| 176 | */ |
| 177 | |
| 178 | void mp_drop(mp *m) { if (m) MP_DROP(m); } |
| 179 | |
| 180 | /* --- @mp_split@ --- * |
| 181 | * |
| 182 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
| 183 | * |
| 184 | * Returns: A reference to the same integer, possibly with a different |
| 185 | * address. |
| 186 | * |
| 187 | * Use: Splits off a modifiable version of the integer referred to. |
| 188 | */ |
| 189 | |
| 190 | mp *mp_split(mp *m) { MP_SPLIT(m); return (m); } |
| 191 | |
| 192 | /* --- @mp_resize@ --- * |
| 193 | * |
| 194 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
| 195 | * @size_t sz@ = new size |
| 196 | * |
| 197 | * Returns: --- |
| 198 | * |
| 199 | * Use: Changes an integer's size. The length and value are not |
| 200 | * changed. It is an error to |
| 201 | */ |
| 202 | |
| 203 | void mp_resize(mp *m, size_t sz) { MP_RESIZE(m, sz); } |
| 204 | |
| 205 | /* --- @mp_ensure@ --- * |
| 206 | * |
| 207 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
| 208 | * @size_t sz@ = required length |
| 209 | * |
| 210 | * Returns: --- |
| 211 | * |
| 212 | * Use: Changes an integer's length. If there is not enough space |
| 213 | * allocated for the new length then the size is increased. It |
| 214 | */ |
| 215 | |
| 216 | void mp_ensure(mp *m, size_t sz) { MP_ENSURE(m, sz); } |
| 217 | |
| 218 | /* --- @mp_dest@ --- * |
| 219 | * |
| 220 | * Arguments: @mp *m@ = a suggested destination integer |
| 221 | * @size_t sz@ = size required for result, in digits |
| 222 | * @unsigned f@ = various flags |
| 223 | * |
| 224 | * Returns: A pointer to an appropriate destination. |
| 225 | * |
| 226 | * Use: Converts a suggested destination into a real destination with |
| 227 | * the required properties. If the real destination is @d@, |
| 228 | * then the following properties will hold: |
| 229 | * |
| 230 | * * @d@ will have exactly one reference. |
| 231 | * |
| 232 | * * If @m@ is not @MP_NEW@, then the contents of @m@ will not |
| 233 | * change, unless @f@ has the @MP_UNDEF@ flag set. |
| 234 | * |
| 235 | * * If @m@ is not @MP_NEW@, then he reference count of @m@ on |
| 236 | * entry is equal to the sum of the counts of @d@ and @m@ on |
| 237 | * exit. |
| 238 | * |
| 239 | * * The size of @d@ will be at least @sz@. |
| 240 | * |
| 241 | * * If @f@ has the @MP_BURN@ flag set, then @d@ will be |
| 242 | * allocated from @MPARENA_SECURE@. |
| 243 | * |
| 244 | * Understanding this function is crucial to using Catacomb's |
| 245 | * multiprecision integer library effectively. |
| 246 | */ |
| 247 | |
| 248 | mp *mp_dest(mp *m, size_t sz, unsigned f) |
| 249 | { |
| 250 | /* --- If no destination, make one --- */ |
| 251 | |
| 252 | if (m == MP_NEWSEC) |
| 253 | m = mp_new(sz, f | MP_UNDEF | MP_BURN); |
| 254 | else if (m == MP_NEW) |
| 255 | m = mp_new(sz, f | MP_UNDEF); |
| 256 | else { |
| 257 | size_t len = MP_LEN(m); |
| 258 | unsigned undef = (m->f | f) & MP_UNDEF; |
| 259 | |
| 260 | /* --- If the value must be preserved, the block can't shrink --- */ |
| 261 | |
| 262 | if (!undef && sz < len) |
| 263 | sz = len; |
| 264 | |
| 265 | /* --- Otherwise check whether the destination is suitable --- */ |
| 266 | |
| 267 | if (m->ref > 1 || (m->f & MP_CONST) || |
| 268 | sz > m->sz || ((f & ~m->f) & MP_BURN)) { |
| 269 | |
| 270 | /* --- No -- allocate a new buffer --- * |
| 271 | * |
| 272 | * The buffer must be secure if (a) the caller requested a secure |
| 273 | * buffer, or (b) the old buffer is secure and I'm not allowed to |
| 274 | * discard the old contents. |
| 275 | */ |
| 276 | |
| 277 | mparena *a; |
| 278 | mpw *v; |
| 279 | |
| 280 | if ((f & MP_BURN) || (!undef && (m->f & MP_BURN))) |
| 281 | a = MPARENA_SECURE; |
| 282 | else |
| 283 | a = MPARENA_GLOBAL; |
| 284 | v = mpalloc(a, sz); |
| 285 | |
| 286 | /* --- Copy the data over --- */ |
| 287 | |
| 288 | if (!undef) { |
| 289 | memcpy(v, m->v, MPWS(len)); |
| 290 | if (sz - len > 0) |
| 291 | memset(v + len, 0, MPWS(sz - len)); |
| 292 | } |
| 293 | |
| 294 | /* --- If @m@ has other references, make a new node --- * |
| 295 | * |
| 296 | * Otherwise dispose of the old buffer. |
| 297 | */ |
| 298 | |
| 299 | if (!(m->f & MP_CONST) && m->ref == 1) { |
| 300 | if (m->f & MP_BURN) |
| 301 | memset(m->v, 0, MPWS(m->sz)); |
| 302 | mpfree(m->a, m->v); |
| 303 | } else { |
| 304 | mp *mm = CREATE(mp); |
| 305 | mm->ref = 1; |
| 306 | mm->f = m->f; |
| 307 | m->ref--; |
| 308 | m = mm; |
| 309 | } |
| 310 | |
| 311 | /* --- Fix up the node --- */ |
| 312 | |
| 313 | m->v = v; |
| 314 | m->vl = v + sz; |
| 315 | m->sz = sz; |
| 316 | m->f = ((m->f & ~(MP_CONST | MP_BURN)) | |
| 317 | (f & (MP_BURN | MP_UNDEF))); |
| 318 | m->a = a; |
| 319 | } |
| 320 | |
| 321 | /* --- If the number is growing in its buffer, fix it up --- */ |
| 322 | |
| 323 | else if (sz > len) { |
| 324 | if (!undef) |
| 325 | memset(m->vl, 0, MPWS(sz - len)); |
| 326 | m->vl = m->v + sz; |
| 327 | } |
| 328 | } |
| 329 | |
| 330 | /* --- Done --- */ |
| 331 | |
| 332 | return (m); |
| 333 | } |
| 334 | |
| 335 | /*----- That's all, folks -------------------------------------------------*/ |