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, 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 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          */
  32         int mode;
  33         long i1, i2;
  34         long chg1, chg2;
  35 } xdmerge_t;
  36
  37 static int xdl_append_merge(xdmerge_t **merge, int mode,
  38                 long i1, long chg1, long i2, long chg2)
  39 {
  40         xdmerge_t *m = *merge;
  41         if (m && mode == m->mode &&
  42                         (i1 == m->i1 + m->chg1 || i2 == m->i2 + m->chg2)) {
  43                 m->chg1 = i1 + chg1 - m->i1;
  44                 m->chg2 = i2 + chg2 - m->i2;
  45         } else {
  46                 m = xdl_malloc(sizeof(xdmerge_t));
  47                 if (!m)
  48                         return -1;
  49                 m->next = NULL;
  50                 m->mode = mode;
  51                 m->i1 = i1;
  52                 m->chg1 = chg1;
  53                 m->i2 = i2;
  54                 m->chg2 = chg2;
  55                 if (*merge)
  56                         (*merge)->next = m;
  57                 *merge = m;
  58         }
  59         return 0;
  60 }
  61
  62 static int xdl_cleanup_merge(xdmerge_t *c)
  63 {
  64         int count = 0;
  65         xdmerge_t *next_c;
  66
  67         /* were there conflicts? */
  68         for (; c; c = next_c) {
  69                 if (c->mode == 0)
  70                         count++;
  71                 next_c = c->next;
  72                 free(c);
  73         }
  74         return count;
  75 }
  76
  77 static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
  78                 int line_count, long flags)
  79 {
  80         int i;
  81         xrecord_t **rec1 = xe1->xdf2.recs + i1;
  82         xrecord_t **rec2 = xe2->xdf2.recs + i2;
  83
  84         for (i = 0; i < line_count; i++) {
  85                 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
  86                         rec2[i]->ptr, rec2[i]->size, flags);
  87                 if (!result)
  88                         return -1;
  89         }
  90         return 0;
  91 }
  92
  93 static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
  94 {
  95         xrecord_t **recs = xe->xdf2.recs + i;
  96         int size = 0;
  97
  98         if (count < 1)
  99                 return 0;
 100
 101         for (i = 0; i < count; size += recs[i++]->size)
 102                 if (dest)
 103                         memcpy(dest + size, recs[i]->ptr, recs[i]->size);
 104         if (add_nl) {
 105                 i = recs[count - 1]->size;
 106                 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
 107                         if (dest)
 108                                 dest[size] = '\n';
 109                         size++;
 110                 }
 111         }
 112         return size;
 113 }
 114
 115 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 116                 xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
 117 {
 118         const int marker_size = 7;
 119         int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 120         int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 121         int conflict_marker_size = 3 * (marker_size + 1)
 122                 + marker1_size + marker2_size;
 123         int size, i1, j;
 124
 125         for (size = i1 = 0; m; m = m->next) {
 126                 if (m->mode == 0) {
 127                         size += xdl_recs_copy(xe1, i1, m->i1 - i1, 0,
 128                                         dest ? dest + size : NULL);
 129                         if (dest) {
 130                                 for (j = 0; j < marker_size; j++)
 131                                         dest[size++] = '<';
 132                                 if (marker1_size) {
 133                                         dest[size] = ' ';
 134                                         memcpy(dest + size + 1, name1,
 135                                                         marker1_size - 1);
 136                                         size += marker1_size;
 137                                 }
 138                                 dest[size++] = '\n';
 139                         } else
 140                                 size += conflict_marker_size;
 141                         size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 142                                         dest ? dest + size : NULL);
 143                         if (dest) {
 144                                 for (j = 0; j < marker_size; j++)
 145                                         dest[size++] = '=';
 146                                 dest[size++] = '\n';
 147                         }
 148                         size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 149                                         dest ? dest + size : NULL);
 150                         if (dest) {
 151                                 for (j = 0; j < marker_size; j++)
 152                                         dest[size++] = '>';
 153                                 if (marker2_size) {
 154                                         dest[size] = ' ';
 155                                         memcpy(dest + size + 1, name2,
 156                                                         marker2_size - 1);
 157                                         size += marker2_size;
 158                                 }
 159                                 dest[size++] = '\n';
 160                         }
 161                 } else if (m->mode == 1)
 162                         size += xdl_recs_copy(xe1, i1, m->i1 + m->chg1 - i1, 0,
 163                                         dest ? dest + size : NULL);
 164                 else if (m->mode == 2)
 165                         size += xdl_recs_copy(xe2, m->i2 - m->i1 + i1,
 166                                         m->i1 + m->chg2 - i1, 0,
 167                                         dest ? dest + size : NULL);
 168                 i1 = m->i1 + m->chg1;
 169         }
 170         size += xdl_recs_copy(xe1, i1, xe1->xdf2.nrec - i1, 0,
 171                         dest ? dest + size : NULL);
 172         return size;
 173 }
 174
 175 /*
 176  * Sometimes, changes are not quite identical, but differ in only a few
 177  * lines. Try hard to show only these few lines as conflicting.
 178  */
 179 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 180                 xpparam_t const *xpp)
 181 {
 182         for (; m; m = m->next) {
 183                 mmfile_t t1, t2;
 184                 xdfenv_t xe;
 185                 xdchange_t *xscr, *x;
 186                 int i1 = m->i1, i2 = m->i2;
 187
 188                 /* let's handle just the conflicts */
 189                 if (m->mode)
 190                         continue;
 191
 192                 /*
 193                  * This probably does not work outside git, since
 194                  * we have a very simple mmfile structure.
 195                  */
 196                 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 197                 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 198                         + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 199                 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 200                 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 201                         + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 202                 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 203                         return -1;
 204                 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 205                     xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 206                     xdl_build_script(&xe, &xscr) < 0) {
 207                         xdl_free_env(&xe);
 208                         return -1;
 209                 }
 210                 if (!xscr) {
 211                         /* If this happens, it's a bug. */
 212                         xdl_free_env(&xe);
 213                         return -2;
 214                 }
 215                 x = xscr;
 216                 m->i1 = xscr->i1 + i1;
 217                 m->chg1 = xscr->chg1;
 218                 m->i2 = xscr->i2 + i2;
 219                 m->chg2 = xscr->chg2;
 220                 while (xscr->next) {
 221                         xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 222                         if (!m2) {
 223                                 xdl_free_env(&xe);
 224                                 xdl_free_script(x);
 225                                 return -1;
 226                         }
 227                         xscr = xscr->next;
 228                         m2->next = m->next;
 229                         m->next = m2;
 230                         m = m2;
 231                         m->mode = 0;
 232                         m->i1 = xscr->i1 + i1;
 233                         m->chg1 = xscr->chg1;
 234                         m->i2 = xscr->i2 + i2;
 235                         m->chg2 = xscr->chg2;
 236                 }
 237                 xdl_free_env(&xe);
 238                 xdl_free_script(x);
 239         }
 240         return 0;
 241 }
 242
 243 /*
 244  * level == 0: mark all overlapping changes as conflict
 245  * level == 1: mark overlapping changes as conflict only if not identical
 246  * level == 2: analyze non-identical changes for minimal conflict set
 247  *
 248  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 249  */
 250 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 251                 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
 252                 int level, xpparam_t const *xpp, mmbuffer_t *result) {
 253         xdmerge_t *changes, *c;
 254         int i1, i2, chg1, chg2;
 255
 256         c = changes = NULL;
 257
 258         while (xscr1 && xscr2) {
 259                 if (!changes)
 260                         changes = c;
 261                 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 262                         i1 = xscr1->i2;
 263                         i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 264                         chg1 = xscr1->chg2;
 265                         chg2 = xscr1->chg1;
 266                         if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 267                                 xdl_cleanup_merge(changes);
 268                                 return -1;
 269                         }
 270                         xscr1 = xscr1->next;
 271                         continue;
 272                 }
 273                 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 274                         i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 275                         i2 = xscr2->i2;
 276                         chg1 = xscr2->chg1;
 277                         chg2 = xscr2->chg2;
 278                         if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 279                                 xdl_cleanup_merge(changes);
 280                                 return -1;
 281                         }
 282                         xscr2 = xscr2->next;
 283                         continue;
 284                 }
 285                 if (level < 1 || xscr1->i1 != xscr2->i1 ||
 286                                 xscr1->chg1 != xscr2->chg1 ||
 287                                 xscr1->chg2 != xscr2->chg2 ||
 288                                 xdl_merge_cmp_lines(xe1, xscr1->i2,
 289                                         xe2, xscr2->i2,
 290                                         xscr1->chg2, xpp->flags)) {
 291                         /* conflict */
 292                         int off = xscr1->i1 - xscr2->i1;
 293                         int ffo = off + xscr1->chg1 - xscr2->chg1;
 294
 295                         i1 = xscr1->i2;
 296                         i2 = xscr2->i2;
 297                         if (off > 0)
 298                                 i1 -= off;
 299                         else
 300                                 i2 += off;
 301                         chg1 = xscr1->i2 + xscr1->chg2 - i1;
 302                         chg2 = xscr2->i2 + xscr2->chg2 - i2;
 303                         if (ffo > 0)
 304                                 chg2 += ffo;
 305                         else
 306                                 chg1 -= ffo;
 307                         if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
 308                                 xdl_cleanup_merge(changes);
 309                                 return -1;
 310                         }
 311                 }
 312
 313                 i1 = xscr1->i1 + xscr1->chg1;
 314                 i2 = xscr2->i1 + xscr2->chg1;
 315
 316                 if (i1 > i2) {
 317                         xscr1->chg1 -= i1 - i2;
 318                         xscr1->i1 = i2;
 319                         xscr1->i2 += xscr1->chg2;
 320                         xscr1->chg2 = 0;
 321                         xscr2 = xscr2->next;
 322                 } else if (i2 > i1) {
 323                         xscr2->chg1 -= i2 - i1;
 324                         xscr2->i1 = i1;
 325                         xscr2->i2 += xscr2->chg2;
 326                         xscr2->chg2 = 0;
 327                         xscr1 = xscr1->next;
 328                 } else {
 329                         xscr1 = xscr1->next;
 330                         xscr2 = xscr2->next;
 331                 }
 332         }
 333         while (xscr1) {
 334                 if (!changes)
 335                         changes = c;
 336                 i1 = xscr1->i2;
 337                 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 338                 chg1 = xscr1->chg2;
 339                 chg2 = xscr1->chg1;
 340                 if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 341                         xdl_cleanup_merge(changes);
 342                         return -1;
 343                 }
 344                 xscr1 = xscr1->next;
 345         }
 346         while (xscr2) {
 347                 if (!changes)
 348                         changes = c;
 349                 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 350                 i2 = xscr2->i2;
 351                 chg1 = xscr2->chg1;
 352                 chg2 = xscr2->chg2;
 353                 if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 354                         xdl_cleanup_merge(changes);
 355                         return -1;
 356                 }
 357                 xscr2 = xscr2->next;
 358         }
 359         if (!changes)
 360                 changes = c;
 361         /* refine conflicts */
 362         if (level > 1 && xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0) {
 363                 xdl_cleanup_merge(changes);
 364                 return -1;
 365         }
 366         /* output */
 367         if (result) {
 368                 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 369                         changes, NULL);
 370                 result->ptr = xdl_malloc(size);
 371                 if (!result->ptr) {
 372                         xdl_cleanup_merge(changes);
 373                         return -1;
 374                 }
 375                 result->size = size;
 376                 xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
 377                                 result->ptr);
 378         }
 379         return xdl_cleanup_merge(changes);
 380 }
 381
 382 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 383                 mmfile_t *mf2, const char *name2,
 384                 xpparam_t const *xpp, int level, mmbuffer_t *result) {
 385         xdchange_t *xscr1, *xscr2;
 386         xdfenv_t xe1, xe2;
 387         int status;
 388
 389         result->ptr = NULL;
 390         result->size = 0;
 391
 392         if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 393                         xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 394                 return -1;
 395         }
 396         if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 397             xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 398             xdl_build_script(&xe1, &xscr1) < 0) {
 399                 xdl_free_env(&xe1);
 400                 return -1;
 401         }
 402         if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 403             xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 404             xdl_build_script(&xe2, &xscr2) < 0) {
 405                 xdl_free_env(&xe2);
 406                 return -1;
 407         }
 408         status = 0;
 409         if (xscr1 || xscr2) {
 410                 if (!xscr1) {
 411                         result->ptr = xdl_malloc(mf2->size);
 412                         memcpy(result->ptr, mf2->ptr, mf2->size);
 413                         result->size = mf2->size;
 414                 } else if (!xscr2) {
 415                         result->ptr = xdl_malloc(mf1->size);
 416                         memcpy(result->ptr, mf1->ptr, mf1->size);
 417                         result->size = mf1->size;
 418                 } else {
 419                         status = xdl_do_merge(&xe1, xscr1, name1,
 420                                               &xe2, xscr2, name2,
 421                                               level, xpp, result);
 422                 }
 423                 xdl_free_script(xscr1);
 424                 xdl_free_script(xscr2);
 425         }
 426         xdl_free_env(&xe1);
 427         xdl_free_env(&xe2);
 428
 429         return status;
 430 }