6ffaa4f9e5ae10e9690a611fc849e3a95a256c10
   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
  25typedef 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
  37static 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
  63static 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
  78static 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
  94static 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
 116static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 117                              xdfenv_t *xe2, const char *name2,
 118                              int size, int i,
 119                              xdmerge_t *m, char *dest)
 120{
 121        const int marker_size = 7;
 122        int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 123        int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 124        int j;
 125
 126        /* Before conflicting part */
 127        size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 128                              dest ? dest + size : NULL);
 129
 130        if (!dest) {
 131                size += marker_size + 1 + marker1_size;
 132        } else {
 133                for (j = 0; j < marker_size; j++)
 134                        dest[size++] = '<';
 135                if (marker1_size) {
 136                        dest[size] = ' ';
 137                        memcpy(dest + size + 1, name1, marker1_size - 1);
 138                        size += marker1_size;
 139                }
 140                dest[size++] = '\n';
 141        }
 142
 143        /* Postimage from side #1 */
 144        size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 145                              dest ? dest + size : NULL);
 146        if (!dest) {
 147                size += marker_size + 1;
 148        } else {
 149                for (j = 0; j < marker_size; j++)
 150                        dest[size++] = '=';
 151                dest[size++] = '\n';
 152        }
 153
 154        /* Postimage from side #2 */
 155        size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 156                              dest ? dest + size : NULL);
 157        if (!dest) {
 158                size += marker_size + 1 + marker2_size;
 159        } else {
 160                for (j = 0; j < marker_size; j++)
 161                        dest[size++] = '>';
 162                if (marker2_size) {
 163                        dest[size] = ' ';
 164                        memcpy(dest + size + 1, name2, marker2_size - 1);
 165                        size += marker2_size;
 166                }
 167                dest[size++] = '\n';
 168        }
 169        return size;
 170}
 171
 172static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 173                xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
 174{
 175        int size, i;
 176
 177        for (size = i = 0; m; m = m->next) {
 178                if (m->mode == 0)
 179                        size = fill_conflict_hunk(xe1, name1, xe2, name2,
 180                                                  size, i, m, dest);
 181                else if (m->mode == 1)
 182                        size += xdl_recs_copy(xe1, i, m->i1 + m->chg1 - i, 0,
 183                                              dest ? dest + size : NULL);
 184                else if (m->mode == 2)
 185                        size += xdl_recs_copy(xe2, m->i2 - m->i1 + i,
 186                                              m->i1 + m->chg2 - i, 0,
 187                                              dest ? dest + size : NULL);
 188                else
 189                        continue;
 190                i = m->i1 + m->chg1;
 191        }
 192        size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
 193                              dest ? dest + size : NULL);
 194        return size;
 195}
 196
 197/*
 198 * Sometimes, changes are not quite identical, but differ in only a few
 199 * lines. Try hard to show only these few lines as conflicting.
 200 */
 201static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 202                xpparam_t const *xpp)
 203{
 204        for (; m; m = m->next) {
 205                mmfile_t t1, t2;
 206                xdfenv_t xe;
 207                xdchange_t *xscr, *x;
 208                int i1 = m->i1, i2 = m->i2;
 209
 210                /* let's handle just the conflicts */
 211                if (m->mode)
 212                        continue;
 213
 214                /* no sense refining a conflict when one side is empty */
 215                if (m->chg1 == 0 || m->chg2 == 0)
 216                        continue;
 217
 218                /*
 219                 * This probably does not work outside git, since
 220                 * we have a very simple mmfile structure.
 221                 */
 222                t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 223                t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 224                        + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 225                t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 226                t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 227                        + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 228                if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 229                        return -1;
 230                if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 231                    xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 232                    xdl_build_script(&xe, &xscr) < 0) {
 233                        xdl_free_env(&xe);
 234                        return -1;
 235                }
 236                if (!xscr) {
 237                        /* If this happens, the changes are identical. */
 238                        xdl_free_env(&xe);
 239                        m->mode = 4;
 240                        continue;
 241                }
 242                x = xscr;
 243                m->i1 = xscr->i1 + i1;
 244                m->chg1 = xscr->chg1;
 245                m->i2 = xscr->i2 + i2;
 246                m->chg2 = xscr->chg2;
 247                while (xscr->next) {
 248                        xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 249                        if (!m2) {
 250                                xdl_free_env(&xe);
 251                                xdl_free_script(x);
 252                                return -1;
 253                        }
 254                        xscr = xscr->next;
 255                        m2->next = m->next;
 256                        m->next = m2;
 257                        m = m2;
 258                        m->mode = 0;
 259                        m->i1 = xscr->i1 + i1;
 260                        m->chg1 = xscr->chg1;
 261                        m->i2 = xscr->i2 + i2;
 262                        m->chg2 = xscr->chg2;
 263                }
 264                xdl_free_env(&xe);
 265                xdl_free_script(x);
 266        }
 267        return 0;
 268}
 269
 270static int line_contains_alnum(const char *ptr, long size)
 271{
 272        while (size--)
 273                if (isalnum(*(ptr++)))
 274                        return 1;
 275        return 0;
 276}
 277
 278static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
 279{
 280        for (; chg; chg--, i++)
 281                if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
 282                                xe->xdf2.recs[i]->size))
 283                        return 1;
 284        return 0;
 285}
 286
 287/*
 288 * This function merges m and m->next, marking everything between those hunks
 289 * as conflicting, too.
 290 */
 291static void xdl_merge_two_conflicts(xdmerge_t *m)
 292{
 293        xdmerge_t *next_m = m->next;
 294        m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 295        m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 296        m->next = next_m->next;
 297        free(next_m);
 298}
 299
 300/*
 301 * If there are less than 3 non-conflicting lines between conflicts,
 302 * it appears simpler -- because it takes up less (or as many) lines --
 303 * if the lines are moved into the conflicts.
 304 */
 305static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
 306                                      int simplify_if_no_alnum)
 307{
 308        int result = 0;
 309
 310        if (!m)
 311                return result;
 312        for (;;) {
 313                xdmerge_t *next_m = m->next;
 314                int begin, end;
 315
 316                if (!next_m)
 317                        return result;
 318
 319                begin = m->i1 + m->chg1;
 320                end = next_m->i1;
 321
 322                if (m->mode != 0 || next_m->mode != 0 ||
 323                    (end - begin > 3 &&
 324                     (!simplify_if_no_alnum ||
 325                      lines_contain_alnum(xe1, begin, end - begin)))) {
 326                        m = next_m;
 327                } else {
 328                        result++;
 329                        xdl_merge_two_conflicts(m);
 330                }
 331        }
 332}
 333
 334/*
 335 * level == 0: mark all overlapping changes as conflict
 336 * level == 1: mark overlapping changes as conflict only if not identical
 337 * level == 2: analyze non-identical changes for minimal conflict set
 338 * level == 3: analyze non-identical changes for minimal conflict set, but
 339 *             treat hunks not containing any letter or number as conflicting
 340 *
 341 * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 342 */
 343static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 344                xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
 345                int level, xpparam_t const *xpp, mmbuffer_t *result) {
 346        xdmerge_t *changes, *c;
 347        int i1, i2, chg1, chg2;
 348
 349        c = changes = NULL;
 350
 351        while (xscr1 && xscr2) {
 352                if (!changes)
 353                        changes = c;
 354                if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 355                        i1 = xscr1->i2;
 356                        i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 357                        chg1 = xscr1->chg2;
 358                        chg2 = xscr1->chg1;
 359                        if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 360                                xdl_cleanup_merge(changes);
 361                                return -1;
 362                        }
 363                        xscr1 = xscr1->next;
 364                        continue;
 365                }
 366                if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 367                        i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 368                        i2 = xscr2->i2;
 369                        chg1 = xscr2->chg1;
 370                        chg2 = xscr2->chg2;
 371                        if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 372                                xdl_cleanup_merge(changes);
 373                                return -1;
 374                        }
 375                        xscr2 = xscr2->next;
 376                        continue;
 377                }
 378                if (level < 1 || xscr1->i1 != xscr2->i1 ||
 379                                xscr1->chg1 != xscr2->chg1 ||
 380                                xscr1->chg2 != xscr2->chg2 ||
 381                                xdl_merge_cmp_lines(xe1, xscr1->i2,
 382                                        xe2, xscr2->i2,
 383                                        xscr1->chg2, xpp->flags)) {
 384                        /* conflict */
 385                        int off = xscr1->i1 - xscr2->i1;
 386                        int ffo = off + xscr1->chg1 - xscr2->chg1;
 387
 388                        i1 = xscr1->i2;
 389                        i2 = xscr2->i2;
 390                        if (off > 0)
 391                                i1 -= off;
 392                        else
 393                                i2 += off;
 394                        chg1 = xscr1->i2 + xscr1->chg2 - i1;
 395                        chg2 = xscr2->i2 + xscr2->chg2 - i2;
 396                        if (ffo > 0)
 397                                chg2 += ffo;
 398                        else
 399                                chg1 -= ffo;
 400                        if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
 401                                xdl_cleanup_merge(changes);
 402                                return -1;
 403                        }
 404                }
 405
 406                i1 = xscr1->i1 + xscr1->chg1;
 407                i2 = xscr2->i1 + xscr2->chg1;
 408
 409                if (i1 >= i2)
 410                        xscr2 = xscr2->next;
 411                if (i2 >= i1)
 412                        xscr1 = xscr1->next;
 413        }
 414        while (xscr1) {
 415                if (!changes)
 416                        changes = c;
 417                i1 = xscr1->i2;
 418                i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 419                chg1 = xscr1->chg2;
 420                chg2 = xscr1->chg1;
 421                if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 422                        xdl_cleanup_merge(changes);
 423                        return -1;
 424                }
 425                xscr1 = xscr1->next;
 426        }
 427        while (xscr2) {
 428                if (!changes)
 429                        changes = c;
 430                i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 431                i2 = xscr2->i2;
 432                chg1 = xscr2->chg1;
 433                chg2 = xscr2->chg2;
 434                if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 435                        xdl_cleanup_merge(changes);
 436                        return -1;
 437                }
 438                xscr2 = xscr2->next;
 439        }
 440        if (!changes)
 441                changes = c;
 442        /* refine conflicts */
 443        if (level > 1 &&
 444            (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 445             xdl_simplify_non_conflicts(xe1, changes, level > 2) < 0)) {
 446                xdl_cleanup_merge(changes);
 447                return -1;
 448        }
 449        /* output */
 450        if (result) {
 451                int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 452                        changes, NULL);
 453                result->ptr = xdl_malloc(size);
 454                if (!result->ptr) {
 455                        xdl_cleanup_merge(changes);
 456                        return -1;
 457                }
 458                result->size = size;
 459                xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
 460                                result->ptr);
 461        }
 462        return xdl_cleanup_merge(changes);
 463}
 464
 465int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 466                mmfile_t *mf2, const char *name2,
 467                xpparam_t const *xpp, int level, mmbuffer_t *result) {
 468        xdchange_t *xscr1, *xscr2;
 469        xdfenv_t xe1, xe2;
 470        int status;
 471
 472        result->ptr = NULL;
 473        result->size = 0;
 474
 475        if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 476                        xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 477                return -1;
 478        }
 479        if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 480            xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 481            xdl_build_script(&xe1, &xscr1) < 0) {
 482                xdl_free_env(&xe1);
 483                return -1;
 484        }
 485        if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 486            xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 487            xdl_build_script(&xe2, &xscr2) < 0) {
 488                xdl_free_env(&xe2);
 489                return -1;
 490        }
 491        status = 0;
 492        if (xscr1 || xscr2) {
 493                if (!xscr1) {
 494                        result->ptr = xdl_malloc(mf2->size);
 495                        memcpy(result->ptr, mf2->ptr, mf2->size);
 496                        result->size = mf2->size;
 497                } else if (!xscr2) {
 498                        result->ptr = xdl_malloc(mf1->size);
 499                        memcpy(result->ptr, mf1->ptr, mf1->size);
 500                        result->size = mf1->size;
 501                } else {
 502                        status = xdl_do_merge(&xe1, xscr1, name1,
 503                                              &xe2, xscr2, name2,
 504                                              level, xpp, result);
 505                }
 506                xdl_free_script(xscr1);
 507                xdl_free_script(xscr2);
 508        }
 509        xdl_free_env(&xe1);
 510        xdl_free_env(&xe2);
 511
 512        return status;
 513}