git/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 && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
  42                 if (mode != m->mode)
  43                         m->mode = 0;
  44                 m->chg1 = i1 + chg1 - m->i1;
  45                 m->chg2 = i2 + chg2 - m->i2;
  46         } else {
  47                 m = xdl_malloc(sizeof(xdmerge_t));
  48                 if (!m)
  49                         return -1;
  50                 m->next = NULL;
  51                 m->mode = mode;
  52                 m->i1 = i1;
  53                 m->chg1 = chg1;
  54                 m->i2 = i2;
  55                 m->chg2 = chg2;
  56                 if (*merge)
  57                         (*merge)->next = m;
  58                 *merge = m;
  59         }
  60         return 0;
  61 }
  62
  63 static int xdl_cleanup_merge(xdmerge_t *c)
  64 {
  65         int count = 0;
  66         xdmerge_t *next_c;
  67
  68         /* were there conflicts? */
  69         for (; c; c = next_c) {
  70                 if (c->mode == 0)
  71                         count++;
  72                 next_c = c->next;
  73                 free(c);
  74         }
  75         return count;
  76 }
  77
  78 static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
  79                 int line_count, long flags)
  80 {
  81         int i;
  82         xrecord_t **rec1 = xe1->xdf2.recs + i1;
  83         xrecord_t **rec2 = xe2->xdf2.recs + i2;
  84
  85         for (i = 0; i < line_count; i++) {
  86                 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
  87                         rec2[i]->ptr, rec2[i]->size, flags);
  88                 if (!result)
  89                         return -1;
  90         }
  91         return 0;
  92 }
  93
  94 static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
  95 {
  96         xrecord_t **recs = xe->xdf2.recs + i;
  97         int size = 0;
  98
  99         if (count < 1)
 100                 return 0;
 101
 102         for (i = 0; i < count; size += recs[i++]->size)
 103                 if (dest)
 104                         memcpy(dest + size, recs[i]->ptr, recs[i]->size);
 105         if (add_nl) {
 106                 i = recs[count - 1]->size;
 107                 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
 108                         if (dest)
 109                                 dest[size] = '\n';
 110                         size++;
 111                 }
 112         }
 113         return size;
 114 }
 115
 116 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 117                 xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
 118 {
 119         const int marker_size = 7;
 120         int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 121         int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 122         int conflict_marker_size = 3 * (marker_size + 1)
 123                 + marker1_size + marker2_size;
 124         int size, i1, j;
 125
 126         for (size = i1 = 0; m; m = m->next) {
 127                 if (m->mode == 0) {
 128                         size += xdl_recs_copy(xe1, i1, m->i1 - i1, 0,
 129                                         dest ? dest + size : NULL);
 130                         if (dest) {
 131                                 for (j = 0; j < marker_size; j++)
 132                                         dest[size++] = '<';
 133                                 if (marker1_size) {
 134                                         dest[size] = ' ';
 135                                         memcpy(dest + size + 1, name1,
 136                                                         marker1_size - 1);
 137                                         size += marker1_size;
 138                                 }
 139                                 dest[size++] = '\n';
 140                         } else
 141                                 size += conflict_marker_size;
 142                         size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 143                                         dest ? dest + size : NULL);
 144                         if (dest) {
 145                                 for (j = 0; j < marker_size; j++)
 146                                         dest[size++] = '=';
 147                                 dest[size++] = '\n';
 148                         }
 149                         size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 150                                         dest ? dest + size : NULL);
 151                         if (dest) {
 152                                 for (j = 0; j < marker_size; j++)
 153                                         dest[size++] = '>';
 154                                 if (marker2_size) {
 155                                         dest[size] = ' ';
 156                                         memcpy(dest + size + 1, name2,
 157                                                         marker2_size - 1);
 158                                         size += marker2_size;
 159                                 }
 160                                 dest[size++] = '\n';
 161                         }
 162                 } else if (m->mode == 1)
 163                         size += xdl_recs_copy(xe1, i1, m->i1 + m->chg1 - i1, 0,
 164                                         dest ? dest + size : NULL);
 165                 else if (m->mode == 2)
 166                         size += xdl_recs_copy(xe2, m->i2 - m->i1 + i1,
 167                                         m->i1 + m->chg2 - i1, 0,
 168                                         dest ? dest + size : NULL);
 169                 else
 170                         continue;
 171                 i1 = m->i1 + m->chg1;
 172         }
 173         size += xdl_recs_copy(xe1, i1, xe1->xdf2.nrec - i1, 0,
 174                         dest ? dest + size : NULL);
 175         return size;
 176 }
 177
 178 /*
 179  * Sometimes, changes are not quite identical, but differ in only a few
 180  * lines. Try hard to show only these few lines as conflicting.
 181  */
 182 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 183                 xpparam_t const *xpp)
 184 {
 185         for (; m; m = m->next) {
 186                 mmfile_t t1, t2;
 187                 xdfenv_t xe;
 188                 xdchange_t *xscr, *x;
 189                 int i1 = m->i1, i2 = m->i2;
 190
 191                 /* let's handle just the conflicts */
 192                 if (m->mode)
 193                         continue;
 194
 195                 /* no sense refining a conflict when one side is empty */
 196                 if (m->chg1 == 0 || m->chg2 == 0)
 197                         continue;
 198
 199                 /*
 200                  * This probably does not work outside git, since
 201                  * we have a very simple mmfile structure.
 202                  */
 203                 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 204                 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 205                         + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 206                 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 207                 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 208                         + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 209                 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 210                         return -1;
 211                 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 212                     xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 213                     xdl_build_script(&xe, &xscr) < 0) {
 214                         xdl_free_env(&xe);
 215                         return -1;
 216                 }
 217                 if (!xscr) {
 218                         /* If this happens, the changes are identical. */
 219                         xdl_free_env(&xe);
 220                         m->mode = 4;
 221                         continue;
 222                 }
 223                 x = xscr;
 224                 m->i1 = xscr->i1 + i1;
 225                 m->chg1 = xscr->chg1;
 226                 m->i2 = xscr->i2 + i2;
 227                 m->chg2 = xscr->chg2;
 228                 while (xscr->next) {
 229                         xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 230                         if (!m2) {
 231                                 xdl_free_env(&xe);
 232                                 xdl_free_script(x);
 233                                 return -1;
 234                         }
 235                         xscr = xscr->next;
 236                         m2->next = m->next;
 237                         m->next = m2;
 238                         m = m2;
 239                         m->mode = 0;
 240                         m->i1 = xscr->i1 + i1;
 241                         m->chg1 = xscr->chg1;
 242                         m->i2 = xscr->i2 + i2;
 243                         m->chg2 = xscr->chg2;
 244                 }
 245                 xdl_free_env(&xe);
 246                 xdl_free_script(x);
 247         }
 248         return 0;
 249 }
 250
 251 /*
 252  * level == 0: mark all overlapping changes as conflict
 253  * level == 1: mark overlapping changes as conflict only if not identical
 254  * level == 2: analyze non-identical changes for minimal conflict set
 255  *
 256  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 257  */
 258 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 259                 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
 260                 int level, xpparam_t const *xpp, mmbuffer_t *result) {
 261         xdmerge_t *changes, *c;
 262         int i1, i2, chg1, chg2;
 263
 264         c = changes = NULL;
 265
 266         while (xscr1 && xscr2) {
 267                 if (!changes)
 268                         changes = c;
 269                 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 270                         i1 = xscr1->i2;
 271                         i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 272                         chg1 = xscr1->chg2;
 273                         chg2 = xscr1->chg1;
 274                         if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 275                                 xdl_cleanup_merge(changes);
 276                                 return -1;
 277                         }
 278                         xscr1 = xscr1->next;
 279                         continue;
 280                 }
 281                 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 282                         i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 283                         i2 = xscr2->i2;
 284                         chg1 = xscr2->chg1;
 285                         chg2 = xscr2->chg2;
 286                         if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 287                                 xdl_cleanup_merge(changes);
 288                                 return -1;
 289                         }
 290                         xscr2 = xscr2->next;
 291                         continue;
 292                 }
 293                 if (level < 1 || xscr1->i1 != xscr2->i1 ||
 294                                 xscr1->chg1 != xscr2->chg1 ||
 295                                 xscr1->chg2 != xscr2->chg2 ||
 296                                 xdl_merge_cmp_lines(xe1, xscr1->i2,
 297                                         xe2, xscr2->i2,
 298                                         xscr1->chg2, xpp->flags)) {
 299                         /* conflict */
 300                         int off = xscr1->i1 - xscr2->i1;
 301                         int ffo = off + xscr1->chg1 - xscr2->chg1;
 302
 303                         i1 = xscr1->i2;
 304                         i2 = xscr2->i2;
 305                         if (off > 0)
 306                                 i1 -= off;
 307                         else
 308                                 i2 += off;
 309                         chg1 = xscr1->i2 + xscr1->chg2 - i1;
 310                         chg2 = xscr2->i2 + xscr2->chg2 - i2;
 311                         if (ffo > 0)
 312                                 chg2 += ffo;
 313                         else
 314                                 chg1 -= ffo;
 315                         if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
 316                                 xdl_cleanup_merge(changes);
 317                                 return -1;
 318                         }
 319                 }
 320
 321                 i1 = xscr1->i1 + xscr1->chg1;
 322                 i2 = xscr2->i1 + xscr2->chg1;
 323
 324                 if (i1 >= i2)
 325                         xscr2 = xscr2->next;
 326                 if (i2 >= i1)
 327                         xscr1 = xscr1->next;
 328         }
 329         while (xscr1) {
 330                 if (!changes)
 331                         changes = c;
 332                 i1 = xscr1->i2;
 333                 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 334                 chg1 = xscr1->chg2;
 335                 chg2 = xscr1->chg1;
 336                 if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 337                         xdl_cleanup_merge(changes);
 338                         return -1;
 339                 }
 340                 xscr1 = xscr1->next;
 341         }
 342         while (xscr2) {
 343                 if (!changes)
 344                         changes = c;
 345                 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 346                 i2 = xscr2->i2;
 347                 chg1 = xscr2->chg1;
 348                 chg2 = xscr2->chg2;
 349                 if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 350                         xdl_cleanup_merge(changes);
 351                         return -1;
 352                 }
 353                 xscr2 = xscr2->next;
 354         }
 355         if (!changes)
 356                 changes = c;
 357         /* refine conflicts */
 358         if (level > 1 && xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0) {
 359                 xdl_cleanup_merge(changes);
 360                 return -1;
 361         }
 362         /* output */
 363         if (result) {
 364                 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 365                         changes, NULL);
 366                 result->ptr = xdl_malloc(size);
 367                 if (!result->ptr) {
 368                         xdl_cleanup_merge(changes);
 369                         return -1;
 370                 }
 371                 result->size = size;
 372                 xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
 373                                 result->ptr);
 374         }
 375         return xdl_cleanup_merge(changes);
 376 }
 377
 378 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 379                 mmfile_t *mf2, const char *name2,
 380                 xpparam_t const *xpp, int level, mmbuffer_t *result) {
 381         xdchange_t *xscr1, *xscr2;
 382         xdfenv_t xe1, xe2;
 383         int status;
 384
 385         result->ptr = NULL;
 386         result->size = 0;
 387
 388         if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 389                         xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 390                 return -1;
 391         }
 392         if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 393             xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 394             xdl_build_script(&xe1, &xscr1) < 0) {
 395                 xdl_free_env(&xe1);
 396                 return -1;
 397         }
 398         if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 399             xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 400             xdl_build_script(&xe2, &xscr2) < 0) {
 401                 xdl_free_env(&xe2);
 402                 return -1;
 403         }
 404         status = 0;
 405         if (xscr1 || xscr2) {
 406                 if (!xscr1) {
 407                         result->ptr = xdl_malloc(mf2->size);
 408                         memcpy(result->ptr, mf2->ptr, mf2->size);
 409                         result->size = mf2->size;
 410                 } else if (!xscr2) {
 411                         result->ptr = xdl_malloc(mf1->size);
 412                         memcpy(result->ptr, mf1->ptr, mf1->size);
 413                         result->size = mf1->size;
 414                 } else {
 415                         status = xdl_do_merge(&xe1, xscr1, name1,
 416                                               &xe2, xscr2, name2,
 417                                               level, xpp, result);
 418                 }
 419                 xdl_free_script(xscr1);
 420                 xdl_free_script(xscr2);
 421         }
 422         xdl_free_env(&xe1);
 423         xdl_free_env(&xe2);
 424
 425         return status;
 426 }