1/* 2 * LibXDiff by Davide Libenzi ( File Differential Library ) 3 * Copyright (C) 2003 Davide Libenzi 4 * 5 * This library is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU Lesser General Public 7 * License as published by the Free Software Foundation; either 8 * version 2.1 of the License, or (at your option) any later version. 9 * 10 * This library is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 * Lesser General Public License for more details. 14 * 15 * You should have received a copy of the GNU Lesser General Public 16 * License along with this library; if not, write to the Free Software 17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 * 19 * Davide Libenzi <davidel@xmailserver.org> 20 * 21 */ 22 23#include "xinclude.h" 24 25 26 27#define XDL_MAX_COST_MIN 256 28#define XDL_HEUR_MIN_COST 256 29#define XDL_LINE_MAX (long)((1UL << (8 * sizeof(long) - 1)) - 1) 30#define XDL_SNAKE_CNT 20 31#define XDL_K_HEUR 4 32 33 34 35typedef struct s_xdpsplit { 36 long i1, i2; 37 int min_lo, min_hi; 38} xdpsplit_t; 39 40 41 42 43static long xdl_split(unsigned long const *ha1, long off1, long lim1, 44 unsigned long const *ha2, long off2, long lim2, 45 long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl, 46 xdalgoenv_t *xenv); 47static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2); 48 49 50 51 52 53/* 54 * See "An O(ND) Difference Algorithm and its Variations", by Eugene Myers. 55 * Basically considers a "box" (off1, off2, lim1, lim2) and scan from both 56 * the forward diagonal starting from (off1, off2) and the backward diagonal 57 * starting from (lim1, lim2). If the K values on the same diagonal crosses 58 * returns the furthest point of reach. We might end up having to expensive 59 * cases using this algorithm is full, so a little bit of heuristic is needed 60 * to cut the search and to return a suboptimal point. 61 */ 62static long xdl_split(unsigned long const *ha1, long off1, long lim1, 63 unsigned long const *ha2, long off2, long lim2, 64 long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl, 65 xdalgoenv_t *xenv) { 66 long dmin = off1 - lim2, dmax = lim1 - off2; 67 long fmid = off1 - off2, bmid = lim1 - lim2; 68 long odd = (fmid - bmid) & 1; 69 long fmin = fmid, fmax = fmid; 70 long bmin = bmid, bmax = bmid; 71 long ec, d, i1, i2, prev1, best, dd, v, k; 72 73 /* 74 * Set initial diagonal values for both forward and backward path. 75 */ 76 kvdf[fmid] = off1; 77 kvdb[bmid] = lim1; 78 79 for (ec = 1;; ec++) { 80 int got_snake = 0; 81 82 /* 83 * We need to extent the diagonal "domain" by one. If the next 84 * values exits the box boundaries we need to change it in the 85 * opposite direction because (max - min) must be a power of two. 86 * Also we initialize the external K value to -1 so that we can 87 * avoid extra conditions check inside the core loop. 88 */ 89 if (fmin > dmin) 90 kvdf[--fmin - 1] = -1; 91 else 92 ++fmin; 93 if (fmax < dmax) 94 kvdf[++fmax + 1] = -1; 95 else 96 --fmax; 97 98 for (d = fmax; d >= fmin; d -= 2) { 99 if (kvdf[d - 1] >= kvdf[d + 1]) 100 i1 = kvdf[d - 1] + 1; 101 else 102 i1 = kvdf[d + 1]; 103 prev1 = i1; 104 i2 = i1 - d; 105 for (; i1 < lim1 && i2 < lim2 && ha1[i1] == ha2[i2]; i1++, i2++); 106 if (i1 - prev1 > xenv->snake_cnt) 107 got_snake = 1; 108 kvdf[d] = i1; 109 if (odd && bmin <= d && d <= bmax && kvdb[d] <= i1) { 110 spl->i1 = i1; 111 spl->i2 = i2; 112 spl->min_lo = spl->min_hi = 1; 113 return ec; 114 } 115 } 116 117 /* 118 * We need to extent the diagonal "domain" by one. If the next 119 * values exits the box boundaries we need to change it in the 120 * opposite direction because (max - min) must be a power of two. 121 * Also we initialize the external K value to -1 so that we can 122 * avoid extra conditions check inside the core loop. 123 */ 124 if (bmin > dmin) 125 kvdb[--bmin - 1] = XDL_LINE_MAX; 126 else 127 ++bmin; 128 if (bmax < dmax) 129 kvdb[++bmax + 1] = XDL_LINE_MAX; 130 else 131 --bmax; 132 133 for (d = bmax; d >= bmin; d -= 2) { 134 if (kvdb[d - 1] < kvdb[d + 1]) 135 i1 = kvdb[d - 1]; 136 else 137 i1 = kvdb[d + 1] - 1; 138 prev1 = i1; 139 i2 = i1 - d; 140 for (; i1 > off1 && i2 > off2 && ha1[i1 - 1] == ha2[i2 - 1]; i1--, i2--); 141 if (prev1 - i1 > xenv->snake_cnt) 142 got_snake = 1; 143 kvdb[d] = i1; 144 if (!odd && fmin <= d && d <= fmax && i1 <= kvdf[d]) { 145 spl->i1 = i1; 146 spl->i2 = i2; 147 spl->min_lo = spl->min_hi = 1; 148 return ec; 149 } 150 } 151 152 if (need_min) 153 continue; 154 155 /* 156 * If the edit cost is above the heuristic trigger and if 157 * we got a good snake, we sample current diagonals to see 158 * if some of the, have reached an "interesting" path. Our 159 * measure is a function of the distance from the diagonal 160 * corner (i1 + i2) penalized with the distance from the 161 * mid diagonal itself. If this value is above the current 162 * edit cost times a magic factor (XDL_K_HEUR) we consider 163 * it interesting. 164 */ 165 if (got_snake && ec > xenv->heur_min) { 166 for (best = 0, d = fmax; d >= fmin; d -= 2) { 167 dd = d > fmid ? d - fmid: fmid - d; 168 i1 = kvdf[d]; 169 i2 = i1 - d; 170 v = (i1 - off1) + (i2 - off2) - dd; 171 172 if (v > XDL_K_HEUR * ec && v > best && 173 off1 + xenv->snake_cnt <= i1 && i1 < lim1 && 174 off2 + xenv->snake_cnt <= i2 && i2 < lim2) { 175 for (k = 1; ha1[i1 - k] == ha2[i2 - k]; k++) 176 if (k == xenv->snake_cnt) { 177 best = v; 178 spl->i1 = i1; 179 spl->i2 = i2; 180 break; 181 } 182 } 183 } 184 if (best > 0) { 185 spl->min_lo = 1; 186 spl->min_hi = 0; 187 return ec; 188 } 189 190 for (best = 0, d = bmax; d >= bmin; d -= 2) { 191 dd = d > bmid ? d - bmid: bmid - d; 192 i1 = kvdb[d]; 193 i2 = i1 - d; 194 v = (lim1 - i1) + (lim2 - i2) - dd; 195 196 if (v > XDL_K_HEUR * ec && v > best && 197 off1 < i1 && i1 <= lim1 - xenv->snake_cnt && 198 off2 < i2 && i2 <= lim2 - xenv->snake_cnt) { 199 for (k = 0; ha1[i1 + k] == ha2[i2 + k]; k++) 200 if (k == xenv->snake_cnt - 1) { 201 best = v; 202 spl->i1 = i1; 203 spl->i2 = i2; 204 break; 205 } 206 } 207 } 208 if (best > 0) { 209 spl->min_lo = 0; 210 spl->min_hi = 1; 211 return ec; 212 } 213 } 214 215 /* 216 * Enough is enough. We spent too much time here and now we collect 217 * the furthest reaching path using the (i1 + i2) measure. 218 */ 219 if (ec >= xenv->mxcost) { 220 long fbest, fbest1, bbest, bbest1; 221 222 fbest = fbest1 = -1; 223 for (d = fmax; d >= fmin; d -= 2) { 224 i1 = XDL_MIN(kvdf[d], lim1); 225 i2 = i1 - d; 226 if (lim2 < i2) 227 i1 = lim2 + d, i2 = lim2; 228 if (fbest < i1 + i2) { 229 fbest = i1 + i2; 230 fbest1 = i1; 231 } 232 } 233 234 bbest = bbest1 = XDL_LINE_MAX; 235 for (d = bmax; d >= bmin; d -= 2) { 236 i1 = XDL_MAX(off1, kvdb[d]); 237 i2 = i1 - d; 238 if (i2 < off2) 239 i1 = off2 + d, i2 = off2; 240 if (i1 + i2 < bbest) { 241 bbest = i1 + i2; 242 bbest1 = i1; 243 } 244 } 245 246 if ((lim1 + lim2) - bbest < fbest - (off1 + off2)) { 247 spl->i1 = fbest1; 248 spl->i2 = fbest - fbest1; 249 spl->min_lo = 1; 250 spl->min_hi = 0; 251 } else { 252 spl->i1 = bbest1; 253 spl->i2 = bbest - bbest1; 254 spl->min_lo = 0; 255 spl->min_hi = 1; 256 } 257 return ec; 258 } 259 } 260} 261 262 263/* 264 * Rule: "Divide et Impera". Recursively split the box in sub-boxes by calling 265 * the box splitting function. Note that the real job (marking changed lines) 266 * is done in the two boundary reaching checks. 267 */ 268int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1, 269 diffdata_t *dd2, long off2, long lim2, 270 long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv) { 271 unsigned long const *ha1 = dd1->ha, *ha2 = dd2->ha; 272 273 /* 274 * Shrink the box by walking through each diagonal snake (SW and NE). 275 */ 276 for (; off1 < lim1 && off2 < lim2 && ha1[off1] == ha2[off2]; off1++, off2++); 277 for (; off1 < lim1 && off2 < lim2 && ha1[lim1 - 1] == ha2[lim2 - 1]; lim1--, lim2--); 278 279 /* 280 * If one dimension is empty, then all records on the other one must 281 * be obviously changed. 282 */ 283 if (off1 == lim1) { 284 char *rchg2 = dd2->rchg; 285 long *rindex2 = dd2->rindex; 286 287 for (; off2 < lim2; off2++) 288 rchg2[rindex2[off2]] = 1; 289 } else if (off2 == lim2) { 290 char *rchg1 = dd1->rchg; 291 long *rindex1 = dd1->rindex; 292 293 for (; off1 < lim1; off1++) 294 rchg1[rindex1[off1]] = 1; 295 } else { 296 long ec; 297 xdpsplit_t spl; 298 spl.i1 = spl.i2 = 0; 299 300 /* 301 * Divide ... 302 */ 303 if ((ec = xdl_split(ha1, off1, lim1, ha2, off2, lim2, kvdf, kvdb, 304 need_min, &spl, xenv)) < 0) { 305 306 return -1; 307 } 308 309 /* 310 * ... et Impera. 311 */ 312 if (xdl_recs_cmp(dd1, off1, spl.i1, dd2, off2, spl.i2, 313 kvdf, kvdb, spl.min_lo, xenv) < 0 || 314 xdl_recs_cmp(dd1, spl.i1, lim1, dd2, spl.i2, lim2, 315 kvdf, kvdb, spl.min_hi, xenv) < 0) { 316 317 return -1; 318 } 319 } 320 321 return 0; 322} 323 324 325int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, 326 xdfenv_t *xe) { 327 long ndiags; 328 long *kvd, *kvdf, *kvdb; 329 xdalgoenv_t xenv; 330 diffdata_t dd1, dd2; 331 332 if (xdl_prepare_env(mf1, mf2, xpp, xe) < 0) { 333 334 return -1; 335 } 336 337 /* 338 * Allocate and setup K vectors to be used by the differential algorithm. 339 * One is to store the forward path and one to store the backward path. 340 */ 341 ndiags = xe->xdf1.nreff + xe->xdf2.nreff + 3; 342 if (!(kvd = (long *) xdl_malloc((2 * ndiags + 2) * sizeof(long)))) { 343 344 xdl_free_env(xe); 345 return -1; 346 } 347 kvdf = kvd; 348 kvdb = kvdf + ndiags; 349 kvdf += xe->xdf2.nreff + 1; 350 kvdb += xe->xdf2.nreff + 1; 351 352 xenv.mxcost = xdl_bogosqrt(ndiags); 353 if (xenv.mxcost < XDL_MAX_COST_MIN) 354 xenv.mxcost = XDL_MAX_COST_MIN; 355 xenv.snake_cnt = XDL_SNAKE_CNT; 356 xenv.heur_min = XDL_HEUR_MIN_COST; 357 358 dd1.nrec = xe->xdf1.nreff; 359 dd1.ha = xe->xdf1.ha; 360 dd1.rchg = xe->xdf1.rchg; 361 dd1.rindex = xe->xdf1.rindex; 362 dd2.nrec = xe->xdf2.nreff; 363 dd2.ha = xe->xdf2.ha; 364 dd2.rchg = xe->xdf2.rchg; 365 dd2.rindex = xe->xdf2.rindex; 366 367 if (xdl_recs_cmp(&dd1, 0, dd1.nrec, &dd2, 0, dd2.nrec, 368 kvdf, kvdb, (xpp->flags & XDF_NEED_MINIMAL) != 0, &xenv) < 0) { 369 370 xdl_free(kvd); 371 xdl_free_env(xe); 372 return -1; 373 } 374 375 xdl_free(kvd); 376 377 return 0; 378} 379 380 381static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2) { 382 xdchange_t *xch; 383 384 if (!(xch = (xdchange_t *) xdl_malloc(sizeof(xdchange_t)))) 385 return NULL; 386 387 xch->next = xscr; 388 xch->i1 = i1; 389 xch->i2 = i2; 390 xch->chg1 = chg1; 391 xch->chg2 = chg2; 392 393 return xch; 394} 395 396 397int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { 398 long ix, ixo, ixs, ixref, grpsiz, nrec = xdf->nrec; 399 char *rchg = xdf->rchg, *rchgo = xdfo->rchg; 400 xrecord_t **recs = xdf->recs; 401 402 /* 403 * This is the same of what GNU diff does. Move back and forward 404 * change groups for a consistent and pretty diff output. This also 405 * helps in finding joinable change groups and reduce the diff size. 406 */ 407 for (ix = ixo = 0;;) { 408 /* 409 * Find the first changed line in the to-be-compacted file. 410 * We need to keep track of both indexes, so if we find a 411 * changed lines group on the other file, while scanning the 412 * to-be-compacted file, we need to skip it properly. Note 413 * that loops that are testing for changed lines on rchg* do 414 * not need index bounding since the array is prepared with 415 * a zero at position -1 and N. 416 */ 417 for (; ix < nrec && !rchg[ix]; ix++) 418 while (rchgo[ixo++]); 419 if (ix == nrec) 420 break; 421 422 /* 423 * Record the start of a changed-group in the to-be-compacted file 424 * and find the end of it, on both to-be-compacted and other file 425 * indexes (ix and ixo). 426 */ 427 ixs = ix; 428 for (ix++; rchg[ix]; ix++); 429 for (; rchgo[ixo]; ixo++); 430 431 do { 432 grpsiz = ix - ixs; 433 434 /* 435 * If the line before the current change group, is equal to 436 * the last line of the current change group, shift backward 437 * the group. 438 */ 439 while (ixs > 0 && recs[ixs - 1]->ha == recs[ix - 1]->ha && 440 xdl_recmatch(recs[ixs - 1]->ptr, recs[ixs - 1]->size, recs[ix - 1]->ptr, recs[ix - 1]->size, flags)) { 441 rchg[--ixs] = 1; 442 rchg[--ix] = 0; 443 444 /* 445 * This change might have joined two change groups, 446 * so we try to take this scenario in account by moving 447 * the start index accordingly (and so the other-file 448 * end-of-group index). 449 */ 450 for (; rchg[ixs - 1]; ixs--); 451 while (rchgo[--ixo]); 452 } 453 454 /* 455 * Record the end-of-group position in case we are matched 456 * with a group of changes in the other file (that is, the 457 * change record before the enf-of-group index in the other 458 * file is set). 459 */ 460 ixref = rchgo[ixo - 1] ? ix: nrec; 461 462 /* 463 * If the first line of the current change group, is equal to 464 * the line next of the current change group, shift forward 465 * the group. 466 */ 467 while (ix < nrec && recs[ixs]->ha == recs[ix]->ha && 468 xdl_recmatch(recs[ixs]->ptr, recs[ixs]->size, recs[ix]->ptr, recs[ix]->size, flags)) { 469 rchg[ixs++] = 0; 470 rchg[ix++] = 1; 471 472 /* 473 * This change might have joined two change groups, 474 * so we try to take this scenario in account by moving 475 * the start index accordingly (and so the other-file 476 * end-of-group index). Keep tracking the reference 477 * index in case we are shifting together with a 478 * corresponding group of changes in the other file. 479 */ 480 for (; rchg[ix]; ix++); 481 while (rchgo[++ixo]) 482 ixref = ix; 483 } 484 } while (grpsiz != ix - ixs); 485 486 /* 487 * Try to move back the possibly merged group of changes, to match 488 * the recorded postion in the other file. 489 */ 490 while (ixref < ix) { 491 rchg[--ixs] = 1; 492 rchg[--ix] = 0; 493 while (rchgo[--ixo]); 494 } 495 } 496 497 return 0; 498} 499 500 501int xdl_build_script(xdfenv_t *xe, xdchange_t **xscr) { 502 xdchange_t *cscr = NULL, *xch; 503 char *rchg1 = xe->xdf1.rchg, *rchg2 = xe->xdf2.rchg; 504 long i1, i2, l1, l2; 505 506 /* 507 * Trivial. Collects "groups" of changes and creates an edit script. 508 */ 509 for (i1 = xe->xdf1.nrec, i2 = xe->xdf2.nrec; i1 >= 0 || i2 >= 0; i1--, i2--) 510 if (rchg1[i1 - 1] || rchg2[i2 - 1]) { 511 for (l1 = i1; rchg1[i1 - 1]; i1--); 512 for (l2 = i2; rchg2[i2 - 1]; i2--); 513 514 if (!(xch = xdl_add_change(cscr, i1, i2, l1 - i1, l2 - i2))) { 515 xdl_free_script(cscr); 516 return -1; 517 } 518 cscr = xch; 519 } 520 521 *xscr = cscr; 522 523 return 0; 524} 525 526 527void xdl_free_script(xdchange_t *xscr) { 528 xdchange_t *xch; 529 530 while ((xch = xscr) != NULL) { 531 xscr = xscr->next; 532 xdl_free(xch); 533 } 534} 535 536 537int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, 538 xdemitconf_t const *xecfg, xdemitcb_t *ecb) { 539 xdchange_t *xscr; 540 xdfenv_t xe; 541 emit_func_t ef = xecfg->emit_func ? 542 (emit_func_t)xecfg->emit_func : xdl_emit_diff; 543 544 if (xdl_do_diff(mf1, mf2, xpp, &xe) < 0) { 545 546 return -1; 547 } 548 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 || 549 xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 || 550 xdl_build_script(&xe, &xscr) < 0) { 551 552 xdl_free_env(&xe); 553 return -1; 554 } 555 if (xscr) { 556 if (ef(&xe, xscr, ecb, xecfg) < 0) { 557 558 xdl_free_script(xscr); 559 xdl_free_env(&xe); 560 return -1; 561 } 562 xdl_free_script(xscr); 563 } 564 xdl_free_env(&xe); 565 566 return 0; 567}