xdiff/xmerge.c

   1 /*
   2  *  LibXDiff by Davide Libenzi ( File Differential Library )
   3  *  Copyright (C) 2003-2006 Davide Libenzi, Johannes E. Schindelin
   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, see
  17  *  <http://www.gnu.org/licenses/>.
  18  *
  19  *  Davide Libenzi <davidel@xmailserver.org>
  20  *
  21  */
  22
  23 #include "xinclude.h"
  24
  25 typedef struct s_xdmerge {
  26         struct s_xdmerge *next;
  27         /*
  28          * 0 = conflict,
  29          * 1 = no conflict, take first,
  30          * 2 = no conflict, take second.
  31          * 3 = no conflict, take both.
  32          */
  33         int mode;
  34         /*
  35          * These point at the respective postimages.  E.g. <i1,chg1> is
  36          * how side #1 wants to change the common ancestor; if there is no
  37          * overlap, lines before i1 in the postimage of side #1 appear
  38          * in the merge result as a region touched by neither side.
  39          */
  40         long i1, i2;
  41         long chg1, chg2;
  42         /*
  43          * These point at the preimage; of course there is just one
  44          * preimage, that is from the shared common ancestor.
  45          */
  46         long i0;
  47         long chg0;
  48 } xdmerge_t;
  49
  50 static int xdl_append_merge(xdmerge_t **merge, int mode,
  51                             long i0, long chg0,
  52                             long i1, long chg1,
  53                             long i2, long chg2)
  54 {
  55         xdmerge_t *m = *merge;
  56         if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
  57                 if (mode != m->mode)
  58                         m->mode = 0;
  59                 m->chg0 = i0 + chg0 - m->i0;
  60                 m->chg1 = i1 + chg1 - m->i1;
  61                 m->chg2 = i2 + chg2 - m->i2;
  62         } else {
  63                 m = xdl_malloc(sizeof(xdmerge_t));
  64                 if (!m)
  65                         return -1;
  66                 m->next = NULL;
  67                 m->mode = mode;
  68                 m->i0 = i0;
  69                 m->chg0 = chg0;
  70                 m->i1 = i1;
  71                 m->chg1 = chg1;
  72                 m->i2 = i2;
  73                 m->chg2 = chg2;
  74                 if (*merge)
  75                         (*merge)->next = m;
  76                 *merge = m;
  77         }
  78         return 0;
  79 }
  80
  81 static int xdl_cleanup_merge(xdmerge_t *c)
  82 {
  83         int count = 0;
  84         xdmerge_t *next_c;
  85
  86         /* were there conflicts? */
  87         for (; c; c = next_c) {
  88                 if (c->mode == 0)
  89                         count++;
  90                 next_c = c->next;
  91                 free(c);
  92         }
  93         return count;
  94 }
  95
  96 static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
  97                 int line_count, long flags)
  98 {
  99         int i;
 100         xrecord_t **rec1 = xe1->xdf2.recs + i1;
 101         xrecord_t **rec2 = xe2->xdf2.recs + i2;
 102
 103         for (i = 0; i < line_count; i++) {
 104                 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
 105                         rec2[i]->ptr, rec2[i]->size, flags);
 106                 if (!result)
 107                         return -1;
 108         }
 109         return 0;
 110 }
 111
 112 static int xdl_recs_copy_0(int use_orig, xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)
 113 {
 114         xrecord_t **recs;
 115         int size = 0;
 116
 117         recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;
 118
 119         if (count < 1)
 120                 return 0;
 121
 122         for (i = 0; i < count; size += recs[i++]->size)
 123                 if (dest)
 124                         memcpy(dest + size, recs[i]->ptr, recs[i]->size);
 125         if (add_nl) {
 126                 i = recs[count - 1]->size;
 127                 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
 128                         if (needs_cr) {
 129                                 if (dest)
 130                                         dest[size] = '\r';
 131                                 size++;
 132                         }
 133
 134                         if (dest)
 135                                 dest[size] = '\n';
 136                         size++;
 137                 }
 138         }
 139         return size;
 140 }
 141
 142 static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)
 143 {
 144         return xdl_recs_copy_0(0, xe, i, count, needs_cr, add_nl, dest);
 145 }
 146
 147 static int xdl_orig_copy(xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)
 148 {
 149         return xdl_recs_copy_0(1, xe, i, count, needs_cr, add_nl, dest);
 150 }
 151
 152 /*
 153  * Returns 1 if the i'th line ends in CR/LF (if it is the last line and
 154  * has no eol, the preceding line, if any), 0 if it ends in LF-only, and
 155  * -1 if the line ending cannot be determined.
 156  */
 157 static int is_eol_crlf(xdfile_t *file, int i)
 158 {
 159         long size;
 160
 161         if (i < file->nrec - 1)
 162                 /* All lines before the last *must* end in LF */
 163                 return (size = file->recs[i]->size) > 1 &&
 164                         file->recs[i]->ptr[size - 2] == '\r';
 165         if (!file->nrec)
 166                 /* Cannot determine eol style from empty file */
 167                 return -1;
 168         if ((size = file->recs[i]->size) &&
 169                         file->recs[i]->ptr[size - 1] == '\n')
 170                 /* Last line; ends in LF; Is it CR/LF? */
 171                 return size > 1 &&
 172                         file->recs[i]->ptr[size - 2] == '\r';
 173         if (!i)
 174                 /* The only line has no eol */
 175                 return -1;
 176         /* Determine eol from second-to-last line */
 177         return (size = file->recs[i - 1]->size) > 1 &&
 178                 file->recs[i - 1]->ptr[size - 2] == '\r';
 179 }
 180
 181 static int is_cr_needed(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m)
 182 {
 183         int needs_cr;
 184
 185         /* Match post-images' preceding, or first, lines' end-of-line style */
 186         needs_cr = is_eol_crlf(&xe1->xdf2, m->i1 ? m->i1 - 1 : 0);
 187         if (needs_cr)
 188                 needs_cr = is_eol_crlf(&xe2->xdf2, m->i2 ? m->i2 - 1 : 0);
 189         /* Look at pre-image's first line, unless we already settled on LF */
 190         if (needs_cr)
 191                 needs_cr = is_eol_crlf(&xe1->xdf1, 0);
 192         /* If still undecided, use LF-only */
 193         return needs_cr < 0 ? 0 : needs_cr;
 194 }
 195
 196 static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 197                               xdfenv_t *xe2, const char *name2,
 198                               const char *name3,
 199                               int size, int i, int style,
 200                               xdmerge_t *m, char *dest, int marker_size)
 201 {
 202         int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 203         int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 204         int marker3_size = (name3 ? strlen(name3) + 1 : 0);
 205         int needs_cr = is_cr_needed(xe1, xe2, m);
 206
 207         if (marker_size <= 0)
 208                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 209
 210         /* Before conflicting part */
 211         size += xdl_recs_copy(xe1, i, m->i1 - i, 0, 0,
 212                               dest ? dest + size : NULL);
 213
 214         if (!dest) {
 215                 size += marker_size + 1 + needs_cr + marker1_size;
 216         } else {
 217                 memset(dest + size, '<', marker_size);
 218                 size += marker_size;
 219                 if (marker1_size) {
 220                         dest[size] = ' ';
 221                         memcpy(dest + size + 1, name1, marker1_size - 1);
 222                         size += marker1_size;
 223                 }
 224                 if (needs_cr)
 225                         dest[size++] = '\r';
 226                 dest[size++] = '\n';
 227         }
 228
 229         /* Postimage from side #1 */
 230         size += xdl_recs_copy(xe1, m->i1, m->chg1, needs_cr, 1,
 231                               dest ? dest + size : NULL);
 232
 233         if (style == XDL_MERGE_DIFF3 || style == XDL_MERGE_ZEALOUS_DIFF3) {
 234                 /* Shared preimage */
 235                 if (!dest) {
 236                         size += marker_size + 1 + needs_cr + marker3_size;
 237                 } else {
 238                         memset(dest + size, '|', marker_size);
 239                         size += marker_size;
 240                         if (marker3_size) {
 241                                 dest[size] = ' ';
 242                                 memcpy(dest + size + 1, name3, marker3_size - 1);
 243                                 size += marker3_size;
 244                         }
 245                         if (needs_cr)
 246                                 dest[size++] = '\r';
 247                         dest[size++] = '\n';
 248                 }
 249                 size += xdl_orig_copy(xe1, m->i0, m->chg0, needs_cr, 1,
 250                                       dest ? dest + size : NULL);
 251         }
 252
 253         if (!dest) {
 254                 size += marker_size + 1 + needs_cr;
 255         } else {
 256                 memset(dest + size, '=', marker_size);
 257                 size += marker_size;
 258                 if (needs_cr)
 259                         dest[size++] = '\r';
 260                 dest[size++] = '\n';
 261         }
 262
 263         /* Postimage from side #2 */
 264         size += xdl_recs_copy(xe2, m->i2, m->chg2, needs_cr, 1,
 265                               dest ? dest + size : NULL);
 266         if (!dest) {
 267                 size += marker_size + 1 + needs_cr + marker2_size;
 268         } else {
 269                 memset(dest + size, '>', marker_size);
 270                 size += marker_size;
 271                 if (marker2_size) {
 272                         dest[size] = ' ';
 273                         memcpy(dest + size + 1, name2, marker2_size - 1);
 274                         size += marker2_size;
 275                 }
 276                 if (needs_cr)
 277                         dest[size++] = '\r';
 278                 dest[size++] = '\n';
 279         }
 280         return size;
 281 }
 282
 283 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 284                                  xdfenv_t *xe2, const char *name2,
 285                                  const char *ancestor_name,
 286                                  int favor,
 287                                  xdmerge_t *m, char *dest, int style,
 288                                  int marker_size)
 289 {
 290         int size, i;
 291
 292         for (size = i = 0; m; m = m->next) {
 293                 if (favor && !m->mode)
 294                         m->mode = favor;
 295
 296                 if (m->mode == 0)
 297                         size = fill_conflict_hunk(xe1, name1, xe2, name2,
 298                                                   ancestor_name,
 299                                                   size, i, style, m, dest,
 300                                                   marker_size);
 301                 else if (m->mode & 3) {
 302                         /* Before conflicting part */
 303                         size += xdl_recs_copy(xe1, i, m->i1 - i, 0, 0,
 304                                               dest ? dest + size : NULL);
 305                         /* Postimage from side #1 */
 306                         if (m->mode & 1) {
 307                                 int needs_cr = is_cr_needed(xe1, xe2, m);
 308
 309                                 size += xdl_recs_copy(xe1, m->i1, m->chg1, needs_cr, (m->mode & 2),
 310                                                       dest ? dest + size : NULL);
 311                         }
 312                         /* Postimage from side #2 */
 313                         if (m->mode & 2)
 314                                 size += xdl_recs_copy(xe2, m->i2, m->chg2, 0, 0,
 315                                                       dest ? dest + size : NULL);
 316                 } else
 317                         continue;
 318                 i = m->i1 + m->chg1;
 319         }
 320         size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0, 0,
 321                               dest ? dest + size : NULL);
 322         return size;
 323 }
 324
 325 static int recmatch(xrecord_t *rec1, xrecord_t *rec2, unsigned long flags)
 326 {
 327         return xdl_recmatch(rec1->ptr, rec1->size,
 328                             rec2->ptr, rec2->size, flags);
 329 }
 330
 331 /*
 332  * Remove any common lines from the beginning and end of the conflicted region.
 333  */
 334 static void xdl_refine_zdiff3_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 335                 xpparam_t const *xpp)
 336 {
 337         xrecord_t **rec1 = xe1->xdf2.recs, **rec2 = xe2->xdf2.recs;
 338         for (; m; m = m->next) {
 339                 /* let's handle just the conflicts */
 340                 if (m->mode)
 341                         continue;
 342
 343                 while(m->chg1 && m->chg2 &&
 344                       recmatch(rec1[m->i1], rec2[m->i2], xpp->flags)) {
 345                         m->chg1--;
 346                         m->chg2--;
 347                         m->i1++;
 348                         m->i2++;
 349                 }
 350                 while (m->chg1 && m->chg2 &&
 351                        recmatch(rec1[m->i1 + m->chg1 - 1],
 352                                 rec2[m->i2 + m->chg2 - 1], xpp->flags)) {
 353                         m->chg1--;
 354                         m->chg2--;
 355                 }
 356         }
 357 }
 358
 359 /*
 360  * Sometimes, changes are not quite identical, but differ in only a few
 361  * lines. Try hard to show only these few lines as conflicting.
 362  */
 363 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 364                 xpparam_t const *xpp)
 365 {
 366         for (; m; m = m->next) {
 367                 mmfile_t t1, t2;
 368                 xdfenv_t xe;
 369                 xdchange_t *xscr, *x;
 370                 int i1 = m->i1, i2 = m->i2;
 371
 372                 /* let's handle just the conflicts */
 373                 if (m->mode)
 374                         continue;
 375
 376                 /* no sense refining a conflict when one side is empty */
 377                 if (m->chg1 == 0 || m->chg2 == 0)
 378                         continue;
 379
 380                 /*
 381                  * This probably does not work outside git, since
 382                  * we have a very simple mmfile structure.
 383                  */
 384                 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 385                 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 386                         + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 387                 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 388                 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 389                         + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 390                 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 391                         return -1;
 392                 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 393                     xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 394                     xdl_build_script(&xe, &xscr) < 0) {
 395                         xdl_free_env(&xe);
 396                         return -1;
 397                 }
 398                 if (!xscr) {
 399                         /* If this happens, the changes are identical. */
 400                         xdl_free_env(&xe);
 401                         m->mode = 4;
 402                         continue;
 403                 }
 404                 x = xscr;
 405                 m->i1 = xscr->i1 + i1;
 406                 m->chg1 = xscr->chg1;
 407                 m->i2 = xscr->i2 + i2;
 408                 m->chg2 = xscr->chg2;
 409                 while (xscr->next) {
 410                         xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 411                         if (!m2) {
 412                                 xdl_free_env(&xe);
 413                                 xdl_free_script(x);
 414                                 return -1;
 415                         }
 416                         xscr = xscr->next;
 417                         m2->next = m->next;
 418                         m->next = m2;
 419                         m = m2;
 420                         m->mode = 0;
 421                         m->i1 = xscr->i1 + i1;
 422                         m->chg1 = xscr->chg1;
 423                         m->i2 = xscr->i2 + i2;
 424                         m->chg2 = xscr->chg2;
 425                 }
 426                 xdl_free_env(&xe);
 427                 xdl_free_script(x);
 428         }
 429         return 0;
 430 }
 431
 432 static int line_contains_alnum(const char *ptr, long size)
 433 {
 434         while (size--)
 435                 if (isalnum((unsigned char)*(ptr++)))
 436                         return 1;
 437         return 0;
 438 }
 439
 440 static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
 441 {
 442         for (; chg; chg--, i++)
 443                 if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
 444                                 xe->xdf2.recs[i]->size))
 445                         return 1;
 446         return 0;
 447 }
 448
 449 /*
 450  * This function merges m and m->next, marking everything between those hunks
 451  * as conflicting, too.
 452  */
 453 static void xdl_merge_two_conflicts(xdmerge_t *m)
 454 {
 455         xdmerge_t *next_m = m->next;
 456         m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 457         m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 458         m->next = next_m->next;
 459         free(next_m);
 460 }
 461
 462 /*
 463  * If there are less than 3 non-conflicting lines between conflicts,
 464  * it appears simpler -- because it takes up less (or as many) lines --
 465  * if the lines are moved into the conflicts.
 466  */
 467 static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
 468                                       int simplify_if_no_alnum)
 469 {
 470         int result = 0;
 471
 472         if (!m)
 473                 return result;
 474         for (;;) {
 475                 xdmerge_t *next_m = m->next;
 476                 int begin, end;
 477
 478                 if (!next_m)
 479                         return result;
 480
 481                 begin = m->i1 + m->chg1;
 482                 end = next_m->i1;
 483
 484                 if (m->mode != 0 || next_m->mode != 0 ||
 485                     (end - begin > 3 &&
 486                      (!simplify_if_no_alnum ||
 487                       lines_contain_alnum(xe1, begin, end - begin)))) {
 488                         m = next_m;
 489                 } else {
 490                         result++;
 491                         xdl_merge_two_conflicts(m);
 492                 }
 493         }
 494 }
 495
 496 /*
 497  * level == 0: mark all overlapping changes as conflict
 498  * level == 1: mark overlapping changes as conflict only if not identical
 499  * level == 2: analyze non-identical changes for minimal conflict set
 500  * level == 3: analyze non-identical changes for minimal conflict set, but
 501  *             treat hunks not containing any letter or number as conflicting
 502  *
 503  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 504  */
 505 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1,
 506                 xdfenv_t *xe2, xdchange_t *xscr2,
 507                 xmparam_t const *xmp, mmbuffer_t *result)
 508 {
 509         xdmerge_t *changes, *c;
 510         xpparam_t const *xpp = &xmp->xpp;
 511         const char *const ancestor_name = xmp->ancestor;
 512         const char *const name1 = xmp->file1;
 513         const char *const name2 = xmp->file2;
 514         int i0, i1, i2, chg0, chg1, chg2;
 515         int level = xmp->level;
 516         int style = xmp->style;
 517         int favor = xmp->favor;
 518
 519         /*
 520          * XDL_MERGE_DIFF3 does not attempt to refine conflicts by looking
 521          * at common areas of sides 1 & 2, because the base (side 0) does
 522          * not match and is being shown.  Similarly, simplification of
 523          * non-conflicts is also skipped due to the skipping of conflict
 524          * refinement.
 525          *
 526          * XDL_MERGE_ZEALOUS_DIFF3, on the other hand, will attempt to
 527          * refine conflicts looking for common areas of sides 1 & 2.
 528          * However, since the base is being shown and does not match,
 529          * it will only look for common areas at the beginning or end
 530          * of the conflict block.  Since XDL_MERGE_ZEALOUS_DIFF3's
 531          * conflict refinement is much more limited in this fashion, the
 532          * conflict simplification will be skipped.
 533          */
 534         if (style == XDL_MERGE_DIFF3 || style == XDL_MERGE_ZEALOUS_DIFF3) {
 535                 /*
 536                  * "diff3 -m" output does not make sense for anything
 537                  * more aggressive than XDL_MERGE_EAGER.
 538                  */
 539                 if (XDL_MERGE_EAGER < level)
 540                         level = XDL_MERGE_EAGER;
 541         }
 542
 543         c = changes = NULL;
 544
 545         while (xscr1 && xscr2) {
 546                 if (!changes)
 547                         changes = c;
 548                 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 549                         i0 = xscr1->i1;
 550                         i1 = xscr1->i2;
 551                         i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 552                         chg0 = xscr1->chg1;
 553                         chg1 = xscr1->chg2;
 554                         chg2 = xscr1->chg1;
 555                         if (xdl_append_merge(&c, 1,
 556                                              i0, chg0, i1, chg1, i2, chg2)) {
 557                                 xdl_cleanup_merge(changes);
 558                                 return -1;
 559                         }
 560                         xscr1 = xscr1->next;
 561                         continue;
 562                 }
 563                 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 564                         i0 = xscr2->i1;
 565                         i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 566                         i2 = xscr2->i2;
 567                         chg0 = xscr2->chg1;
 568                         chg1 = xscr2->chg1;
 569                         chg2 = xscr2->chg2;
 570                         if (xdl_append_merge(&c, 2,
 571                                              i0, chg0, i1, chg1, i2, chg2)) {
 572                                 xdl_cleanup_merge(changes);
 573                                 return -1;
 574                         }
 575                         xscr2 = xscr2->next;
 576                         continue;
 577                 }
 578                 if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||
 579                                 xscr1->chg1 != xscr2->chg1 ||
 580                                 xscr1->chg2 != xscr2->chg2 ||
 581                                 xdl_merge_cmp_lines(xe1, xscr1->i2,
 582                                         xe2, xscr2->i2,
 583                                         xscr1->chg2, xpp->flags)) {
 584                         /* conflict */
 585                         int off = xscr1->i1 - xscr2->i1;
 586                         int ffo = off + xscr1->chg1 - xscr2->chg1;
 587
 588                         i0 = xscr1->i1;
 589                         i1 = xscr1->i2;
 590                         i2 = xscr2->i2;
 591                         if (off > 0) {
 592                                 i0 -= off;
 593                                 i1 -= off;
 594                         }
 595                         else
 596                                 i2 += off;
 597                         chg0 = xscr1->i1 + xscr1->chg1 - i0;
 598                         chg1 = xscr1->i2 + xscr1->chg2 - i1;
 599                         chg2 = xscr2->i2 + xscr2->chg2 - i2;
 600                         if (ffo < 0) {
 601                                 chg0 -= ffo;
 602                                 chg1 -= ffo;
 603                         } else
 604                                 chg2 += ffo;
 605                         if (xdl_append_merge(&c, 0,
 606                                              i0, chg0, i1, chg1, i2, chg2)) {
 607                                 xdl_cleanup_merge(changes);
 608                                 return -1;
 609                         }
 610                 }
 611
 612                 i1 = xscr1->i1 + xscr1->chg1;
 613                 i2 = xscr2->i1 + xscr2->chg1;
 614
 615                 if (i1 >= i2)
 616                         xscr2 = xscr2->next;
 617                 if (i2 >= i1)
 618                         xscr1 = xscr1->next;
 619         }
 620         while (xscr1) {
 621                 if (!changes)
 622                         changes = c;
 623                 i0 = xscr1->i1;
 624                 i1 = xscr1->i2;
 625                 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 626                 chg0 = xscr1->chg1;
 627                 chg1 = xscr1->chg2;
 628                 chg2 = xscr1->chg1;
 629                 if (xdl_append_merge(&c, 1,
 630                                      i0, chg0, i1, chg1, i2, chg2)) {
 631                         xdl_cleanup_merge(changes);
 632                         return -1;
 633                 }
 634                 xscr1 = xscr1->next;
 635         }
 636         while (xscr2) {
 637                 if (!changes)
 638                         changes = c;
 639                 i0 = xscr2->i1;
 640                 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 641                 i2 = xscr2->i2;
 642                 chg0 = xscr2->chg1;
 643                 chg1 = xscr2->chg1;
 644                 chg2 = xscr2->chg2;
 645                 if (xdl_append_merge(&c, 2,
 646                                      i0, chg0, i1, chg1, i2, chg2)) {
 647                         xdl_cleanup_merge(changes);
 648                         return -1;
 649                 }
 650                 xscr2 = xscr2->next;
 651         }
 652         if (!changes)
 653                 changes = c;
 654         /* refine conflicts */
 655         if (style == XDL_MERGE_ZEALOUS_DIFF3) {
 656                 xdl_refine_zdiff3_conflicts(xe1, xe2, changes, xpp);
 657         } else if (XDL_MERGE_ZEALOUS <= level &&
 658                    (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 659                     xdl_simplify_non_conflicts(xe1, changes,
 660                                                XDL_MERGE_ZEALOUS < level) < 0)) {
 661                 xdl_cleanup_merge(changes);
 662                 return -1;
 663         }
 664         /* output */
 665         if (result) {
 666                 int marker_size = xmp->marker_size;
 667                 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 668                                                  ancestor_name,
 669                                                  favor, changes, NULL, style,
 670                                                  marker_size);
 671                 result->ptr = xdl_malloc(size);
 672                 if (!result->ptr) {
 673                         xdl_cleanup_merge(changes);
 674                         return -1;
 675                 }
 676                 result->size = size;
 677                 xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 678                                       ancestor_name, favor, changes,
 679                                       result->ptr, style, marker_size);
 680         }
 681         return xdl_cleanup_merge(changes);
 682 }
 683
 684 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
 685                 xmparam_t const *xmp, mmbuffer_t *result)
 686 {
 687         xdchange_t *xscr1 = NULL, *xscr2 = NULL;
 688         xdfenv_t xe1, xe2;
 689         int status = -1;
 690         xpparam_t const *xpp = &xmp->xpp;
 691
 692         result->ptr = NULL;
 693         result->size = 0;
 694
 695         if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0)
 696                 return -1;
 697
 698         if (xdl_do_diff(orig, mf2, xpp, &xe2) < 0)
 699                 goto free_xe1; /* avoid double free of xe2 */
 700
 701         if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 702             xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 703             xdl_build_script(&xe1, &xscr1) < 0)
 704                 goto out;
 705
 706         if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 707             xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 708             xdl_build_script(&xe2, &xscr2) < 0)
 709                 goto out;
 710
 711         if (!xscr1) {
 712                 result->ptr = xdl_malloc(mf2->size);
 713                 if (!result->ptr)
 714                         goto out;
 715                 status = 0;
 716                 memcpy(result->ptr, mf2->ptr, mf2->size);
 717                 result->size = mf2->size;
 718         } else if (!xscr2) {
 719                 result->ptr = xdl_malloc(mf1->size);
 720                 if (!result->ptr)
 721                         goto out;
 722                 status = 0;
 723                 memcpy(result->ptr, mf1->ptr, mf1->size);
 724                 result->size = mf1->size;
 725         } else {
 726                 status = xdl_do_merge(&xe1, xscr1,
 727                                       &xe2, xscr2,
 728                                       xmp, result);
 729         }
 730  out:
 731         xdl_free_script(xscr1);
 732         xdl_free_script(xscr2);
 733
 734         xdl_free_env(&xe2);
 735  free_xe1:
 736         xdl_free_env(&xe1);
 737
 738         return status;
 739 }