ecbdae502c7109f0bc46e00322ae95e8815e90c3
   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 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 */
 182static 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 * This function merges m and m->next, marking everything between those hunks
 253 * as conflicting, too.
 254 */
 255static void xdl_merge_two_conflicts(xdmerge_t *m)
 256{
 257        xdmerge_t *next_m = m->next;
 258        m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 259        m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 260        m->next = next_m->next;
 261        free(next_m);
 262}
 263
 264/*
 265 * If there are less than 3 non-conflicting lines between conflicts,
 266 * it appears simpler -- because it takes up less (or as many) lines --
 267 * if the lines are moved into the conflicts.
 268 */
 269static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m)
 270{
 271        int result = 0;
 272
 273        if (!m)
 274                return result;
 275        for (;;) {
 276                xdmerge_t *next_m = m->next;
 277                int begin, end;
 278
 279                if (!next_m)
 280                        return result;
 281
 282                begin = m->i1 + m->chg1;
 283                end = next_m->i1;
 284
 285                if (m->mode != 0 || next_m->mode != 0 || end - begin > 3)
 286                        m = next_m;
 287                else {
 288                        result++;
 289                        xdl_merge_two_conflicts(m);
 290                }
 291        }
 292}
 293
 294/*
 295 * level == 0: mark all overlapping changes as conflict
 296 * level == 1: mark overlapping changes as conflict only if not identical
 297 * level == 2: analyze non-identical changes for minimal conflict set
 298 *
 299 * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 300 */
 301static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 302                xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
 303                int level, xpparam_t const *xpp, mmbuffer_t *result) {
 304        xdmerge_t *changes, *c;
 305        int i1, i2, chg1, chg2;
 306
 307        c = changes = NULL;
 308
 309        while (xscr1 && xscr2) {
 310                if (!changes)
 311                        changes = c;
 312                if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 313                        i1 = xscr1->i2;
 314                        i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 315                        chg1 = xscr1->chg2;
 316                        chg2 = xscr1->chg1;
 317                        if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 318                                xdl_cleanup_merge(changes);
 319                                return -1;
 320                        }
 321                        xscr1 = xscr1->next;
 322                        continue;
 323                }
 324                if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 325                        i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 326                        i2 = xscr2->i2;
 327                        chg1 = xscr2->chg1;
 328                        chg2 = xscr2->chg2;
 329                        if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 330                                xdl_cleanup_merge(changes);
 331                                return -1;
 332                        }
 333                        xscr2 = xscr2->next;
 334                        continue;
 335                }
 336                if (level < 1 || xscr1->i1 != xscr2->i1 ||
 337                                xscr1->chg1 != xscr2->chg1 ||
 338                                xscr1->chg2 != xscr2->chg2 ||
 339                                xdl_merge_cmp_lines(xe1, xscr1->i2,
 340                                        xe2, xscr2->i2,
 341                                        xscr1->chg2, xpp->flags)) {
 342                        /* conflict */
 343                        int off = xscr1->i1 - xscr2->i1;
 344                        int ffo = off + xscr1->chg1 - xscr2->chg1;
 345
 346                        i1 = xscr1->i2;
 347                        i2 = xscr2->i2;
 348                        if (off > 0)
 349                                i1 -= off;
 350                        else
 351                                i2 += off;
 352                        chg1 = xscr1->i2 + xscr1->chg2 - i1;
 353                        chg2 = xscr2->i2 + xscr2->chg2 - i2;
 354                        if (ffo > 0)
 355                                chg2 += ffo;
 356                        else
 357                                chg1 -= ffo;
 358                        if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
 359                                xdl_cleanup_merge(changes);
 360                                return -1;
 361                        }
 362                }
 363
 364                i1 = xscr1->i1 + xscr1->chg1;
 365                i2 = xscr2->i1 + xscr2->chg1;
 366
 367                if (i1 >= i2)
 368                        xscr2 = xscr2->next;
 369                if (i2 >= i1)
 370                        xscr1 = xscr1->next;
 371        }
 372        while (xscr1) {
 373                if (!changes)
 374                        changes = c;
 375                i1 = xscr1->i2;
 376                i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 377                chg1 = xscr1->chg2;
 378                chg2 = xscr1->chg1;
 379                if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 380                        xdl_cleanup_merge(changes);
 381                        return -1;
 382                }
 383                xscr1 = xscr1->next;
 384        }
 385        while (xscr2) {
 386                if (!changes)
 387                        changes = c;
 388                i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 389                i2 = xscr2->i2;
 390                chg1 = xscr2->chg1;
 391                chg2 = xscr2->chg2;
 392                if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 393                        xdl_cleanup_merge(changes);
 394                        return -1;
 395                }
 396                xscr2 = xscr2->next;
 397        }
 398        if (!changes)
 399                changes = c;
 400        /* refine conflicts */
 401        if (level > 1 &&
 402            (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 403             xdl_simplify_non_conflicts(xe1, changes) < 0)) {
 404                xdl_cleanup_merge(changes);
 405                return -1;
 406        }
 407        /* output */
 408        if (result) {
 409                int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 410                        changes, NULL);
 411                result->ptr = xdl_malloc(size);
 412                if (!result->ptr) {
 413                        xdl_cleanup_merge(changes);
 414                        return -1;
 415                }
 416                result->size = size;
 417                xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
 418                                result->ptr);
 419        }
 420        return xdl_cleanup_merge(changes);
 421}
 422
 423int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 424                mmfile_t *mf2, const char *name2,
 425                xpparam_t const *xpp, int level, mmbuffer_t *result) {
 426        xdchange_t *xscr1, *xscr2;
 427        xdfenv_t xe1, xe2;
 428        int status;
 429
 430        result->ptr = NULL;
 431        result->size = 0;
 432
 433        if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 434                        xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 435                return -1;
 436        }
 437        if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 438            xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 439            xdl_build_script(&xe1, &xscr1) < 0) {
 440                xdl_free_env(&xe1);
 441                return -1;
 442        }
 443        if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 444            xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 445            xdl_build_script(&xe2, &xscr2) < 0) {
 446                xdl_free_env(&xe2);
 447                return -1;
 448        }
 449        status = 0;
 450        if (xscr1 || xscr2) {
 451                if (!xscr1) {
 452                        result->ptr = xdl_malloc(mf2->size);
 453                        memcpy(result->ptr, mf2->ptr, mf2->size);
 454                        result->size = mf2->size;
 455                } else if (!xscr2) {
 456                        result->ptr = xdl_malloc(mf1->size);
 457                        memcpy(result->ptr, mf1->ptr, mf1->size);
 458                        result->size = mf1->size;
 459                } else {
 460                        status = xdl_do_merge(&xe1, xscr1, name1,
 461                                              &xe2, xscr2, name2,
 462                                              level, xpp, result);
 463                }
 464                xdl_free_script(xscr1);
 465                xdl_free_script(xscr2);
 466        }
 467        xdl_free_env(&xe1);
 468        xdl_free_env(&xe2);
 469
 470        return status;
 471}