git.oblomov.eu Git - git/blob - combine-diff.c

   1 #include "cache.h"
   2 #include "object-store.h"
   3 #include "commit.h"
   4 #include "blob.h"
   5 #include "diff.h"
   6 #include "diffcore.h"
   7 #include "quote.h"
   8 #include "xdiff-interface.h"
   9 #include "xdiff/xmacros.h"
  10 #include "log-tree.h"
  11 #include "refs.h"
  12 #include "userdiff.h"
  13 #include "oid-array.h"
  14 #include "revision.h"
  15
  16 static int compare_paths(const struct combine_diff_path *one,
  17                           const struct diff_filespec *two)
  18 {
  19         if (!S_ISDIR(one->mode) && !S_ISDIR(two->mode))
  20                 return strcmp(one->path, two->path);
  21
  22         return base_name_compare(one->path, strlen(one->path), one->mode,
  23                                  two->path, strlen(two->path), two->mode);
  24 }
  25
  26 static int filename_changed(char status)
  27 {
  28         return status == 'R' || status == 'C';
  29 }
  30
  31 static struct combine_diff_path *intersect_paths(
  32         struct combine_diff_path *curr,
  33         int n,
  34         int num_parent,
  35         int combined_all_paths)
  36 {
  37         struct diff_queue_struct *q = &diff_queued_diff;
  38         struct combine_diff_path *p, **tail = &curr;
  39         int i, j, cmp;
  40
  41         if (!n) {
  42                 for (i = 0; i < q->nr; i++) {
  43                         int len;
  44                         const char *path;
  45                         if (diff_unmodified_pair(q->queue[i]))
  46                                 continue;
  47                         path = q->queue[i]->two->path;
  48                         len = strlen(path);
  49                         p = xmalloc(combine_diff_path_size(num_parent, len));
  50                         p->path = (char *) &(p->parent[num_parent]);
  51                         memcpy(p->path, path, len);
  52                         p->path[len] = 0;
  53                         p->next = NULL;
  54                         memset(p->parent, 0,
  55                                sizeof(p->parent[0]) * num_parent);
  56
  57                         oidcpy(&p->oid, &q->queue[i]->two->oid);
  58                         p->mode = q->queue[i]->two->mode;
  59                         oidcpy(&p->parent[n].oid, &q->queue[i]->one->oid);
  60                         p->parent[n].mode = q->queue[i]->one->mode;
  61                         p->parent[n].status = q->queue[i]->status;
  62
  63                         if (combined_all_paths &&
  64                             filename_changed(p->parent[n].status)) {
  65                                 strbuf_init(&p->parent[n].path, 0);
  66                                 strbuf_addstr(&p->parent[n].path,
  67                                               q->queue[i]->one->path);
  68                         }
  69                         *tail = p;
  70                         tail = &p->next;
  71                 }
  72                 return curr;
  73         }
  74
  75         /*
  76          * paths in curr (linked list) and q->queue[] (array) are
  77          * both sorted in the tree order.
  78          */
  79         i = 0;
  80         while ((p = *tail) != NULL) {
  81                 cmp = ((i >= q->nr)
  82                        ? -1 : compare_paths(p, q->queue[i]->two));
  83
  84                 if (cmp < 0) {
  85                         /* p->path not in q->queue[]; drop it */
  86                         *tail = p->next;
  87                         for (j = 0; j < num_parent; j++)
  88                                 if (combined_all_paths &&
  89                                     filename_changed(p->parent[j].status))
  90                                         strbuf_release(&p->parent[j].path);
  91                         free(p);
  92                         continue;
  93                 }
  94
  95                 if (cmp > 0) {
  96                         /* q->queue[i] not in p->path; skip it */
  97                         i++;
  98                         continue;
  99                 }
 100
 101                 oidcpy(&p->parent[n].oid, &q->queue[i]->one->oid);
 102                 p->parent[n].mode = q->queue[i]->one->mode;
 103                 p->parent[n].status = q->queue[i]->status;
 104                 if (combined_all_paths &&
 105                     filename_changed(p->parent[n].status))
 106                         strbuf_addstr(&p->parent[n].path,
 107                                       q->queue[i]->one->path);
 108
 109                 tail = &p->next;
 110                 i++;
 111         }
 112         return curr;
 113 }
 114
 115 /* Lines lost from parent */
 116 struct lline {
 117         struct lline *next, *prev;
 118         int len;
 119         unsigned long parent_map;
 120         char line[FLEX_ARRAY];
 121 };
 122
 123 /* Lines lost from current parent (before coalescing) */
 124 struct plost {
 125         struct lline *lost_head, *lost_tail;
 126         int len;
 127 };
 128
 129 /* Lines surviving in the merge result */
 130 struct sline {
 131         /* Accumulated and coalesced lost lines */
 132         struct lline *lost;
 133         int lenlost;
 134         struct plost plost;
 135         char *bol;
 136         int len;
 137         /* bit 0 up to (N-1) are on if the parent has this line (i.e.
 138          * we did not change it).
 139          * bit N is used for "interesting" lines, including context.
 140          * bit (N+1) is used for "do not show deletion before this".
 141          */
 142         unsigned long flag;
 143         unsigned long *p_lno;
 144 };
 145
 146 static int match_string_spaces(const char *line1, int len1,
 147                                const char *line2, int len2,
 148                                long flags)
 149 {
 150         if (flags & XDF_WHITESPACE_FLAGS) {
 151                 for (; len1 > 0 && XDL_ISSPACE(line1[len1 - 1]); len1--);
 152                 for (; len2 > 0 && XDL_ISSPACE(line2[len2 - 1]); len2--);
 153         }
 154
 155         if (!(flags & (XDF_IGNORE_WHITESPACE | XDF_IGNORE_WHITESPACE_CHANGE)))
 156                 return (len1 == len2 && !memcmp(line1, line2, len1));
 157
 158         while (len1 > 0 && len2 > 0) {
 159                 len1--;
 160                 len2--;
 161                 if (XDL_ISSPACE(line1[len1]) || XDL_ISSPACE(line2[len2])) {
 162                         if ((flags & XDF_IGNORE_WHITESPACE_CHANGE) &&
 163                             (!XDL_ISSPACE(line1[len1]) || !XDL_ISSPACE(line2[len2])))
 164                                 return 0;
 165
 166                         for (; len1 > 0 && XDL_ISSPACE(line1[len1]); len1--);
 167                         for (; len2 > 0 && XDL_ISSPACE(line2[len2]); len2--);
 168                 }
 169                 if (line1[len1] != line2[len2])
 170                         return 0;
 171         }
 172
 173         if (flags & XDF_IGNORE_WHITESPACE) {
 174                 /* Consume remaining spaces */
 175                 for (; len1 > 0 && XDL_ISSPACE(line1[len1 - 1]); len1--);
 176                 for (; len2 > 0 && XDL_ISSPACE(line2[len2 - 1]); len2--);
 177         }
 178
 179         /* We matched full line1 and line2 */
 180         if (!len1 && !len2)
 181                 return 1;
 182
 183         return 0;
 184 }
 185
 186 enum coalesce_direction { MATCH, BASE, NEW };
 187
 188 /* Coalesce new lines into base by finding LCS */
 189 static struct lline *coalesce_lines(struct lline *base, int *lenbase,
 190                                     struct lline *newline, int lennew,
 191                                     unsigned long parent, long flags)
 192 {
 193         int **lcs;
 194         enum coalesce_direction **directions;
 195         struct lline *baseend, *newend = NULL;
 196         int i, j, origbaselen = *lenbase;
 197
 198         if (newline == NULL)
 199                 return base;
 200
 201         if (base == NULL) {
 202                 *lenbase = lennew;
 203                 return newline;
 204         }
 205
 206         /*
 207          * Coalesce new lines into base by finding the LCS
 208          * - Create the table to run dynamic programming
 209          * - Compute the LCS
 210          * - Then reverse read the direction structure:
 211          *   - If we have MATCH, assign parent to base flag, and consume
 212          *   both baseend and newend
 213          *   - Else if we have BASE, consume baseend
 214          *   - Else if we have NEW, insert newend lline into base and
 215          *   consume newend
 216          */
 217         lcs = xcalloc(st_add(origbaselen, 1), sizeof(int*));
 218         directions = xcalloc(st_add(origbaselen, 1), sizeof(enum coalesce_direction*));
 219         for (i = 0; i < origbaselen + 1; i++) {
 220                 lcs[i] = xcalloc(st_add(lennew, 1), sizeof(int));
 221                 directions[i] = xcalloc(st_add(lennew, 1), sizeof(enum coalesce_direction));
 222                 directions[i][0] = BASE;
 223         }
 224         for (j = 1; j < lennew + 1; j++)
 225                 directions[0][j] = NEW;
 226
 227         for (i = 1, baseend = base; i < origbaselen + 1; i++) {
 228                 for (j = 1, newend = newline; j < lennew + 1; j++) {
 229                         if (match_string_spaces(baseend->line, baseend->len,
 230                                                 newend->line, newend->len, flags)) {
 231                                 lcs[i][j] = lcs[i - 1][j - 1] + 1;
 232                                 directions[i][j] = MATCH;
 233                         } else if (lcs[i][j - 1] >= lcs[i - 1][j]) {
 234                                 lcs[i][j] = lcs[i][j - 1];
 235                                 directions[i][j] = NEW;
 236                         } else {
 237                                 lcs[i][j] = lcs[i - 1][j];
 238                                 directions[i][j] = BASE;
 239                         }
 240                         if (newend->next)
 241                                 newend = newend->next;
 242                 }
 243                 if (baseend->next)
 244                         baseend = baseend->next;
 245         }
 246
 247         for (i = 0; i < origbaselen + 1; i++)
 248                 free(lcs[i]);
 249         free(lcs);
 250
 251         /* At this point, baseend and newend point to the end of each lists */
 252         i--;
 253         j--;
 254         while (i != 0 || j != 0) {
 255                 if (directions[i][j] == MATCH) {
 256                         baseend->parent_map |= 1<<parent;
 257                         baseend = baseend->prev;
 258                         newend = newend->prev;
 259                         i--;
 260                         j--;
 261                 } else if (directions[i][j] == NEW) {
 262                         struct lline *lline;
 263
 264                         lline = newend;
 265                         /* Remove lline from new list and update newend */
 266                         if (lline->prev)
 267                                 lline->prev->next = lline->next;
 268                         else
 269                                 newline = lline->next;
 270                         if (lline->next)
 271                                 lline->next->prev = lline->prev;
 272
 273                         newend = lline->prev;
 274                         j--;
 275
 276                         /* Add lline to base list */
 277                         if (baseend) {
 278                                 lline->next = baseend->next;
 279                                 lline->prev = baseend;
 280                                 if (lline->prev)
 281                                         lline->prev->next = lline;
 282                         }
 283                         else {
 284                                 lline->next = base;
 285                                 base = lline;
 286                         }
 287                         (*lenbase)++;
 288
 289                         if (lline->next)
 290                                 lline->next->prev = lline;
 291
 292                 } else {
 293                         baseend = baseend->prev;
 294                         i--;
 295                 }
 296         }
 297
 298         newend = newline;
 299         while (newend) {
 300                 struct lline *lline = newend;
 301                 newend = newend->next;
 302                 free(lline);
 303         }
 304
 305         for (i = 0; i < origbaselen + 1; i++)
 306                 free(directions[i]);
 307         free(directions);
 308
 309         return base;
 310 }
 311
 312 static char *grab_blob(struct repository *r,
 313                        const struct object_id *oid, unsigned int mode,
 314                        unsigned long *size, struct userdiff_driver *textconv,
 315                        const char *path)
 316 {
 317         char *blob;
 318         enum object_type type;
 319
 320         if (S_ISGITLINK(mode)) {
 321                 struct strbuf buf = STRBUF_INIT;
 322                 strbuf_addf(&buf, "Subproject commit %s\n", oid_to_hex(oid));
 323                 *size = buf.len;
 324                 blob = strbuf_detach(&buf, NULL);
 325         } else if (is_null_oid(oid)) {
 326                 /* deleted blob */
 327                 *size = 0;
 328                 return xcalloc(1, 1);
 329         } else if (textconv) {
 330                 struct diff_filespec *df = alloc_filespec(path);
 331                 fill_filespec(df, oid, 1, mode);
 332                 *size = fill_textconv(r, textconv, df, &blob);
 333                 free_filespec(df);
 334         } else {
 335                 blob = read_object_file(oid, &type, size);
 336                 if (type != OBJ_BLOB)
 337                         die("object '%s' is not a blob!", oid_to_hex(oid));
 338         }
 339         return blob;
 340 }
 341
 342 static void append_lost(struct sline *sline, int n, const char *line, int len)
 343 {
 344         struct lline *lline;
 345         unsigned long this_mask = (1UL<<n);
 346         if (line[len-1] == '\n')
 347                 len--;
 348
 349         FLEX_ALLOC_MEM(lline, line, line, len);
 350         lline->len = len;
 351         lline->next = NULL;
 352         lline->prev = sline->plost.lost_tail;
 353         if (lline->prev)
 354                 lline->prev->next = lline;
 355         else
 356                 sline->plost.lost_head = lline;
 357         sline->plost.lost_tail = lline;
 358         sline->plost.len++;
 359         lline->parent_map = this_mask;
 360 }
 361
 362 struct combine_diff_state {
 363         unsigned int lno;
 364         int ob, on, nb, nn;
 365         unsigned long nmask;
 366         int num_parent;
 367         int n;
 368         struct sline *sline;
 369         struct sline *lost_bucket;
 370 };
 371
 372 static void consume_hunk(void *state_,
 373                          long ob, long on,
 374                          long nb, long nn,
 375                          const char *funcline, long funclen)
 376 {
 377         struct combine_diff_state *state = state_;
 378
 379         state->ob = ob;
 380         state->on = on;
 381         state->nb = nb;
 382         state->nn = nn;
 383         state->lno = state->nb;
 384         if (state->nn == 0) {
 385                 /* @@ -X,Y +N,0 @@ removed Y lines
 386                  * that would have come *after* line N
 387                  * in the result.  Our lost buckets hang
 388                  * to the line after the removed lines,
 389                  *
 390                  * Note that this is correct even when N == 0,
 391                  * in which case the hunk removes the first
 392                  * line in the file.
 393                  */
 394                 state->lost_bucket = &state->sline[state->nb];
 395                 if (!state->nb)
 396                         state->nb = 1;
 397         } else {
 398                 state->lost_bucket = &state->sline[state->nb-1];
 399         }
 400         if (!state->sline[state->nb-1].p_lno)
 401                 state->sline[state->nb-1].p_lno =
 402                         xcalloc(state->num_parent, sizeof(unsigned long));
 403         state->sline[state->nb-1].p_lno[state->n] = state->ob;
 404 }
 405
 406 static void consume_line(void *state_, char *line, unsigned long len)
 407 {
 408         struct combine_diff_state *state = state_;
 409         if (!state->lost_bucket)
 410                 return; /* not in any hunk yet */
 411         switch (line[0]) {
 412         case '-':
 413                 append_lost(state->lost_bucket, state->n, line+1, len-1);
 414                 break;
 415         case '+':
 416                 state->sline[state->lno-1].flag |= state->nmask;
 417                 state->lno++;
 418                 break;
 419         }
 420 }
 421
 422 static void combine_diff(struct repository *r,
 423                          const struct object_id *parent, unsigned int mode,
 424                          mmfile_t *result_file,
 425                          struct sline *sline, unsigned int cnt, int n,
 426                          int num_parent, int result_deleted,
 427                          struct userdiff_driver *textconv,
 428                          const char *path, long flags)
 429 {
 430         unsigned int p_lno, lno;
 431         unsigned long nmask = (1UL << n);
 432         xpparam_t xpp;
 433         xdemitconf_t xecfg;
 434         mmfile_t parent_file;
 435         struct combine_diff_state state;
 436         unsigned long sz;
 437
 438         if (result_deleted)
 439                 return; /* result deleted */
 440
 441         parent_file.ptr = grab_blob(r, parent, mode, &sz, textconv, path);
 442         parent_file.size = sz;
 443         memset(&xpp, 0, sizeof(xpp));
 444         xpp.flags = flags;
 445         memset(&xecfg, 0, sizeof(xecfg));
 446         memset(&state, 0, sizeof(state));
 447         state.nmask = nmask;
 448         state.sline = sline;
 449         state.lno = 1;
 450         state.num_parent = num_parent;
 451         state.n = n;
 452
 453         if (xdi_diff_outf(&parent_file, result_file, consume_hunk,
 454                           consume_line, &state, &xpp, &xecfg))
 455                 die("unable to generate combined diff for %s",
 456                     oid_to_hex(parent));
 457         free(parent_file.ptr);
 458
 459         /* Assign line numbers for this parent.
 460          *
 461          * sline[lno].p_lno[n] records the first line number
 462          * (counting from 1) for parent N if the final hunk display
 463          * started by showing sline[lno] (possibly showing the lost
 464          * lines attached to it first).
 465          */
 466         for (lno = 0,  p_lno = 1; lno <= cnt; lno++) {
 467                 struct lline *ll;
 468                 sline[lno].p_lno[n] = p_lno;
 469
 470                 /* Coalesce new lines */
 471                 if (sline[lno].plost.lost_head) {
 472                         struct sline *sl = &sline[lno];
 473                         sl->lost = coalesce_lines(sl->lost, &sl->lenlost,
 474                                                   sl->plost.lost_head,
 475                                                   sl->plost.len, n, flags);
 476                         sl->plost.lost_head = sl->plost.lost_tail = NULL;
 477                         sl->plost.len = 0;
 478                 }
 479
 480                 /* How many lines would this sline advance the p_lno? */
 481                 ll = sline[lno].lost;
 482                 while (ll) {
 483                         if (ll->parent_map & nmask)
 484                                 p_lno++; /* '-' means parent had it */
 485                         ll = ll->next;
 486                 }
 487                 if (lno < cnt && !(sline[lno].flag & nmask))
 488                         p_lno++; /* no '+' means parent had it */
 489         }
 490         sline[lno].p_lno[n] = p_lno; /* trailer */
 491 }
 492
 493 static unsigned long context = 3;
 494 static char combine_marker = '@';
 495
 496 static int interesting(struct sline *sline, unsigned long all_mask)
 497 {
 498         /* If some parents lost lines here, or if we have added to
 499          * some parent, it is interesting.
 500          */
 501         return ((sline->flag & all_mask) || sline->lost);
 502 }
 503
 504 static unsigned long adjust_hunk_tail(struct sline *sline,
 505                                       unsigned long all_mask,
 506                                       unsigned long hunk_begin,
 507                                       unsigned long i)
 508 {
 509         /* i points at the first uninteresting line.  If the last line
 510          * of the hunk was interesting only because it has some
 511          * deletion, then it is not all that interesting for the
 512          * purpose of giving trailing context lines.  This is because
 513          * we output '-' line and then unmodified sline[i-1] itself in
 514          * that case which gives us one extra context line.
 515          */
 516         if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
 517                 i--;
 518         return i;
 519 }
 520
 521 static unsigned long find_next(struct sline *sline,
 522                                unsigned long mark,
 523                                unsigned long i,
 524                                unsigned long cnt,
 525                                int look_for_uninteresting)
 526 {
 527         /* We have examined up to i-1 and are about to look at i.
 528          * Find next interesting or uninteresting line.  Here,
 529          * "interesting" does not mean interesting(), but marked by
 530          * the give_context() function below (i.e. it includes context
 531          * lines that are not interesting to interesting() function
 532          * that are surrounded by interesting() ones.
 533          */
 534         while (i <= cnt)
 535                 if (look_for_uninteresting
 536                     ? !(sline[i].flag & mark)
 537                     : (sline[i].flag & mark))
 538                         return i;
 539                 else
 540                         i++;
 541         return i;
 542 }
 543
 544 static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
 545 {
 546         unsigned long all_mask = (1UL<<num_parent) - 1;
 547         unsigned long mark = (1UL<<num_parent);
 548         unsigned long no_pre_delete = (2UL<<num_parent);
 549         unsigned long i;
 550
 551         /* Two groups of interesting lines may have a short gap of
 552          * uninteresting lines.  Connect such groups to give them a
 553          * bit of context.
 554          *
 555          * We first start from what the interesting() function says,
 556          * and mark them with "mark", and paint context lines with the
 557          * mark.  So interesting() would still say false for such context
 558          * lines but they are treated as "interesting" in the end.
 559          */
 560         i = find_next(sline, mark, 0, cnt, 0);
 561         if (cnt < i)
 562                 return 0;
 563
 564         while (i <= cnt) {
 565                 unsigned long j = (context < i) ? (i - context) : 0;
 566                 unsigned long k;
 567
 568                 /* Paint a few lines before the first interesting line. */
 569                 while (j < i) {
 570                         if (!(sline[j].flag & mark))
 571                                 sline[j].flag |= no_pre_delete;
 572                         sline[j++].flag |= mark;
 573                 }
 574
 575         again:
 576                 /* we know up to i is to be included.  where does the
 577                  * next uninteresting one start?
 578                  */
 579                 j = find_next(sline, mark, i, cnt, 1);
 580                 if (cnt < j)
 581                         break; /* the rest are all interesting */
 582
 583                 /* lookahead context lines */
 584                 k = find_next(sline, mark, j, cnt, 0);
 585                 j = adjust_hunk_tail(sline, all_mask, i, j);
 586
 587                 if (k < j + context) {
 588                         /* k is interesting and [j,k) are not, but
 589                          * paint them interesting because the gap is small.
 590                          */
 591                         while (j < k)
 592                                 sline[j++].flag |= mark;
 593                         i = k;
 594                         goto again;
 595                 }
 596
 597                 /* j is the first uninteresting line and there is
 598                  * no overlap beyond it within context lines.  Paint
 599                  * the trailing edge a bit.
 600                  */
 601                 i = k;
 602                 k = (j + context < cnt+1) ? j + context : cnt+1;
 603                 while (j < k)
 604                         sline[j++].flag |= mark;
 605         }
 606         return 1;
 607 }
 608
 609 static int make_hunks(struct sline *sline, unsigned long cnt,
 610                        int num_parent, int dense)
 611 {
 612         unsigned long all_mask = (1UL<<num_parent) - 1;
 613         unsigned long mark = (1UL<<num_parent);
 614         unsigned long i;
 615         int has_interesting = 0;
 616
 617         for (i = 0; i <= cnt; i++) {
 618                 if (interesting(&sline[i], all_mask))
 619                         sline[i].flag |= mark;
 620                 else
 621                         sline[i].flag &= ~mark;
 622         }
 623         if (!dense)
 624                 return give_context(sline, cnt, num_parent);
 625
 626         /* Look at each hunk, and if we have changes from only one
 627          * parent, or the changes are the same from all but one
 628          * parent, mark that uninteresting.
 629          */
 630         i = 0;
 631         while (i <= cnt) {
 632                 unsigned long j, hunk_begin, hunk_end;
 633                 unsigned long same_diff;
 634                 while (i <= cnt && !(sline[i].flag & mark))
 635                         i++;
 636                 if (cnt < i)
 637                         break; /* No more interesting hunks */
 638                 hunk_begin = i;
 639                 for (j = i + 1; j <= cnt; j++) {
 640                         if (!(sline[j].flag & mark)) {
 641                                 /* Look beyond the end to see if there
 642                                  * is an interesting line after this
 643                                  * hunk within context span.
 644                                  */
 645                                 unsigned long la; /* lookahead */
 646                                 int contin = 0;
 647                                 la = adjust_hunk_tail(sline, all_mask,
 648                                                      hunk_begin, j);
 649                                 la = (la + context < cnt + 1) ?
 650                                         (la + context) : cnt + 1;
 651                                 while (la && j <= --la) {
 652                                         if (sline[la].flag & mark) {
 653                                                 contin = 1;
 654                                                 break;
 655                                         }
 656                                 }
 657                                 if (!contin)
 658                                         break;
 659                                 j = la;
 660                         }
 661                 }
 662                 hunk_end = j;
 663
 664                 /* [i..hunk_end) are interesting.  Now is it really
 665                  * interesting?  We check if there are only two versions
 666                  * and the result matches one of them.  That is, we look
 667                  * at:
 668                  *   (+) line, which records lines added to which parents;
 669                  *       this line appears in the result.
 670                  *   (-) line, which records from what parents the line
 671                  *       was removed; this line does not appear in the result.
 672                  * then check the set of parents the result has difference
 673                  * from, from all lines.  If there are lines that has
 674                  * different set of parents that the result has differences
 675                  * from, that means we have more than two versions.
 676                  *
 677                  * Even when we have only two versions, if the result does
 678                  * not match any of the parents, the it should be considered
 679                  * interesting.  In such a case, we would have all '+' line.
 680                  * After passing the above "two versions" test, that would
 681                  * appear as "the same set of parents" to be "all parents".
 682                  */
 683                 same_diff = 0;
 684                 has_interesting = 0;
 685                 for (j = i; j < hunk_end && !has_interesting; j++) {
 686                         unsigned long this_diff = sline[j].flag & all_mask;
 687                         struct lline *ll = sline[j].lost;
 688                         if (this_diff) {
 689                                 /* This has some changes.  Is it the
 690                                  * same as others?
 691                                  */
 692                                 if (!same_diff)
 693                                         same_diff = this_diff;
 694                                 else if (same_diff != this_diff) {
 695                                         has_interesting = 1;
 696                                         break;
 697                                 }
 698                         }
 699                         while (ll && !has_interesting) {
 700                                 /* Lost this line from these parents;
 701                                  * who are they?  Are they the same?
 702                                  */
 703                                 this_diff = ll->parent_map;
 704                                 if (!same_diff)
 705                                         same_diff = this_diff;
 706                                 else if (same_diff != this_diff) {
 707                                         has_interesting = 1;
 708                                 }
 709                                 ll = ll->next;
 710                         }
 711                 }
 712
 713                 if (!has_interesting && same_diff != all_mask) {
 714                         /* This hunk is not that interesting after all */
 715                         for (j = hunk_begin; j < hunk_end; j++)
 716                                 sline[j].flag &= ~mark;
 717                 }
 718                 i = hunk_end;
 719         }
 720
 721         has_interesting = give_context(sline, cnt, num_parent);
 722         return has_interesting;
 723 }
 724
 725 static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, int n, unsigned long null_context)
 726 {
 727         l0 = sline[l0].p_lno[n];
 728         l1 = sline[l1].p_lno[n];
 729         printf(" -%lu,%lu", l0, l1-l0-null_context);
 730 }
 731
 732 static int hunk_comment_line(const char *bol)
 733 {
 734         int ch;
 735
 736         if (!bol)
 737                 return 0;
 738         ch = *bol & 0xff;
 739         return (isalpha(ch) || ch == '_' || ch == '$');
 740 }
 741
 742 static void show_line_to_eol(const char *line, int len, const char *reset)
 743 {
 744         int saw_cr_at_eol = 0;
 745         if (len < 0)
 746                 len = strlen(line);
 747         saw_cr_at_eol = (len && line[len-1] == '\r');
 748
 749         printf("%.*s%s%s\n", len - saw_cr_at_eol, line,
 750                reset,
 751                saw_cr_at_eol ? "\r" : "");
 752 }
 753
 754 static void dump_sline(struct sline *sline, const char *line_prefix,
 755                        unsigned long cnt, int num_parent,
 756                        int use_color, int result_deleted)
 757 {
 758         unsigned long mark = (1UL<<num_parent);
 759         unsigned long no_pre_delete = (2UL<<num_parent);
 760         int i;
 761         unsigned long lno = 0;
 762         const char *c_frag = diff_get_color(use_color, DIFF_FRAGINFO);
 763         const char *c_func = diff_get_color(use_color, DIFF_FUNCINFO);
 764         const char *c_new = diff_get_color(use_color, DIFF_FILE_NEW);
 765         const char *c_old = diff_get_color(use_color, DIFF_FILE_OLD);
 766         const char *c_context = diff_get_color(use_color, DIFF_CONTEXT);
 767         const char *c_reset = diff_get_color(use_color, DIFF_RESET);
 768
 769         if (result_deleted)
 770                 return; /* result deleted */
 771
 772         while (1) {
 773                 unsigned long hunk_end;
 774                 unsigned long rlines;
 775                 const char *hunk_comment = NULL;
 776                 unsigned long null_context = 0;
 777
 778                 while (lno <= cnt && !(sline[lno].flag & mark)) {
 779                         if (hunk_comment_line(sline[lno].bol))
 780                                 hunk_comment = sline[lno].bol;
 781                         lno++;
 782                 }
 783                 if (cnt < lno)
 784                         break;
 785                 else {
 786                         for (hunk_end = lno + 1; hunk_end <= cnt; hunk_end++)
 787                                 if (!(sline[hunk_end].flag & mark))
 788                                         break;
 789                 }
 790                 rlines = hunk_end - lno;
 791                 if (cnt < hunk_end)
 792                         rlines--; /* pointing at the last delete hunk */
 793
 794                 if (!context) {
 795                         /*
 796                          * Even when running with --unified=0, all
 797                          * lines in the hunk needs to be processed in
 798                          * the loop below in order to show the
 799                          * deletion recorded in lost_head.  However,
 800                          * we do not want to show the resulting line
 801                          * with all blank context markers in such a
 802                          * case.  Compensate.
 803                          */
 804                         unsigned long j;
 805                         for (j = lno; j < hunk_end; j++)
 806                                 if (!(sline[j].flag & (mark-1)))
 807                                         null_context++;
 808                         rlines -= null_context;
 809                 }
 810
 811                 printf("%s%s", line_prefix, c_frag);
 812                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 813                 for (i = 0; i < num_parent; i++)
 814                         show_parent_lno(sline, lno, hunk_end, i, null_context);
 815                 printf(" +%lu,%lu ", lno+1, rlines);
 816                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 817
 818                 if (hunk_comment) {
 819                         int comment_end = 0;
 820                         for (i = 0; i < 40; i++) {
 821                                 int ch = hunk_comment[i] & 0xff;
 822                                 if (!ch || ch == '\n')
 823                                         break;
 824                                 if (!isspace(ch))
 825                                     comment_end = i;
 826                         }
 827                         if (comment_end)
 828                                 printf("%s%s %s%s", c_reset,
 829                                                     c_context, c_reset,
 830                                                     c_func);
 831                         for (i = 0; i < comment_end; i++)
 832                                 putchar(hunk_comment[i]);
 833                 }
 834
 835                 printf("%s\n", c_reset);
 836                 while (lno < hunk_end) {
 837                         struct lline *ll;
 838                         int j;
 839                         unsigned long p_mask;
 840                         struct sline *sl = &sline[lno++];
 841                         ll = (sl->flag & no_pre_delete) ? NULL : sl->lost;
 842                         while (ll) {
 843                                 printf("%s%s", line_prefix, c_old);
 844                                 for (j = 0; j < num_parent; j++) {
 845                                         if (ll->parent_map & (1UL<<j))
 846                                                 putchar('-');
 847                                         else
 848                                                 putchar(' ');
 849                                 }
 850                                 show_line_to_eol(ll->line, -1, c_reset);
 851                                 ll = ll->next;
 852                         }
 853                         if (cnt < lno)
 854                                 break;
 855                         p_mask = 1;
 856                         fputs(line_prefix, stdout);
 857                         if (!(sl->flag & (mark-1))) {
 858                                 /*
 859                                  * This sline was here to hang the
 860                                  * lost lines in front of it.
 861                                  */
 862                                 if (!context)
 863                                         continue;
 864                                 fputs(c_context, stdout);
 865                         }
 866                         else
 867                                 fputs(c_new, stdout);
 868                         for (j = 0; j < num_parent; j++) {
 869                                 if (p_mask & sl->flag)
 870                                         putchar('+');
 871                                 else
 872                                         putchar(' ');
 873                                 p_mask <<= 1;
 874                         }
 875                         show_line_to_eol(sl->bol, sl->len, c_reset);
 876                 }
 877         }
 878 }
 879
 880 static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 881                                int i, int j)
 882 {
 883         /* We have already examined parent j and we know parent i
 884          * and parent j are the same, so reuse the combined result
 885          * of parent j for parent i.
 886          */
 887         unsigned long lno, imask, jmask;
 888         imask = (1UL<<i);
 889         jmask = (1UL<<j);
 890
 891         for (lno = 0; lno <= cnt; lno++) {
 892                 struct lline *ll = sline->lost;
 893                 sline->p_lno[i] = sline->p_lno[j];
 894                 while (ll) {
 895                         if (ll->parent_map & jmask)
 896                                 ll->parent_map |= imask;
 897                         ll = ll->next;
 898                 }
 899                 if (sline->flag & jmask)
 900                         sline->flag |= imask;
 901                 sline++;
 902         }
 903         /* the overall size of the file (sline[cnt]) */
 904         sline->p_lno[i] = sline->p_lno[j];
 905 }
 906
 907 static void dump_quoted_path(const char *head,
 908                              const char *prefix,
 909                              const char *path,
 910                              const char *line_prefix,
 911                              const char *c_meta, const char *c_reset)
 912 {
 913         static struct strbuf buf = STRBUF_INIT;
 914
 915         strbuf_reset(&buf);
 916         strbuf_addstr(&buf, line_prefix);
 917         strbuf_addstr(&buf, c_meta);
 918         strbuf_addstr(&buf, head);
 919         quote_two_c_style(&buf, prefix, path, 0);
 920         strbuf_addstr(&buf, c_reset);
 921         puts(buf.buf);
 922 }
 923
 924 static void show_combined_header(struct combine_diff_path *elem,
 925                                  int num_parent,
 926                                  int dense,
 927                                  struct rev_info *rev,
 928                                  const char *line_prefix,
 929                                  int mode_differs,
 930                                  int show_file_header)
 931 {
 932         struct diff_options *opt = &rev->diffopt;
 933         int abbrev = opt->flags.full_index ? the_hash_algo->hexsz : DEFAULT_ABBREV;
 934         const char *a_prefix = opt->a_prefix ? opt->a_prefix : "a/";
 935         const char *b_prefix = opt->b_prefix ? opt->b_prefix : "b/";
 936         const char *c_meta = diff_get_color_opt(opt, DIFF_METAINFO);
 937         const char *c_reset = diff_get_color_opt(opt, DIFF_RESET);
 938         const char *abb;
 939         int added = 0;
 940         int deleted = 0;
 941         int i;
 942
 943         if (rev->loginfo && !rev->no_commit_id)
 944                 show_log(rev);
 945
 946         dump_quoted_path(dense ? "diff --cc " : "diff --combined ",
 947                          "", elem->path, line_prefix, c_meta, c_reset);
 948         printf("%s%sindex ", line_prefix, c_meta);
 949         for (i = 0; i < num_parent; i++) {
 950                 abb = find_unique_abbrev(&elem->parent[i].oid,
 951                                          abbrev);
 952                 printf("%s%s", i ? "," : "", abb);
 953         }
 954         abb = find_unique_abbrev(&elem->oid, abbrev);
 955         printf("..%s%s\n", abb, c_reset);
 956
 957         if (mode_differs) {
 958                 deleted = !elem->mode;
 959
 960                 /* We say it was added if nobody had it */
 961                 added = !deleted;
 962                 for (i = 0; added && i < num_parent; i++)
 963                         if (elem->parent[i].status !=
 964                             DIFF_STATUS_ADDED)
 965                                 added = 0;
 966                 if (added)
 967                         printf("%s%snew file mode %06o",
 968                                line_prefix, c_meta, elem->mode);
 969                 else {
 970                         if (deleted)
 971                                 printf("%s%sdeleted file ",
 972                                        line_prefix, c_meta);
 973                         printf("mode ");
 974                         for (i = 0; i < num_parent; i++) {
 975                                 printf("%s%06o", i ? "," : "",
 976                                        elem->parent[i].mode);
 977                         }
 978                         if (elem->mode)
 979                                 printf("..%06o", elem->mode);
 980                 }
 981                 printf("%s\n", c_reset);
 982         }
 983
 984         if (!show_file_header)
 985                 return;
 986
 987         if (rev->combined_all_paths) {
 988                 for (i = 0; i < num_parent; i++) {
 989                         char *path = filename_changed(elem->parent[i].status)
 990                                 ? elem->parent[i].path.buf : elem->path;
 991                         if (elem->parent[i].status == DIFF_STATUS_ADDED)
 992                                 dump_quoted_path("--- ", "", "/dev/null",
 993                                                  line_prefix, c_meta, c_reset);
 994                         else
 995                                 dump_quoted_path("--- ", a_prefix, path,
 996                                                  line_prefix, c_meta, c_reset);
 997                 }
 998         } else {
 999                 if (added)
1000                         dump_quoted_path("--- ", "", "/dev/null",
1001                                          line_prefix, c_meta, c_reset);
1002                 else
1003                         dump_quoted_path("--- ", a_prefix, elem->path,
1004                                          line_prefix, c_meta, c_reset);
1005         }
1006         if (deleted)
1007                 dump_quoted_path("+++ ", "", "/dev/null",
1008                                  line_prefix, c_meta, c_reset);
1009         else
1010                 dump_quoted_path("+++ ", b_prefix, elem->path,
1011                                  line_prefix, c_meta, c_reset);
1012 }
1013
1014 static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
1015                             int dense, int working_tree_file,
1016                             struct rev_info *rev)
1017 {
1018         struct diff_options *opt = &rev->diffopt;
1019         unsigned long result_size, cnt, lno;
1020         int result_deleted = 0;
1021         char *result, *cp;
1022         struct sline *sline; /* survived lines */
1023         int mode_differs = 0;
1024         int i, show_hunks;
1025         mmfile_t result_file;
1026         struct userdiff_driver *userdiff;
1027         struct userdiff_driver *textconv = NULL;
1028         int is_binary;
1029         const char *line_prefix = diff_line_prefix(opt);
1030
1031         context = opt->context;
1032         userdiff = userdiff_find_by_path(opt->repo->index, elem->path);
1033         if (!userdiff)
1034                 userdiff = userdiff_find_by_name("default");
1035         if (opt->flags.allow_textconv)
1036                 textconv = userdiff_get_textconv(opt->repo, userdiff);
1037
1038         /* Read the result of merge first */
1039         if (!working_tree_file)
1040                 result = grab_blob(opt->repo, &elem->oid, elem->mode, &result_size,
1041                                    textconv, elem->path);
1042         else {
1043                 /* Used by diff-tree to read from the working tree */
1044                 struct stat st;
1045                 int fd = -1;
1046
1047                 if (lstat(elem->path, &st) < 0)
1048                         goto deleted_file;
1049
1050                 if (S_ISLNK(st.st_mode)) {
1051                         struct strbuf buf = STRBUF_INIT;
1052
1053                         if (strbuf_readlink(&buf, elem->path, st.st_size) < 0) {
1054                                 error_errno("readlink(%s)", elem->path);
1055                                 return;
1056                         }
1057                         result_size = buf.len;
1058                         result = strbuf_detach(&buf, NULL);
1059                         elem->mode = canon_mode(st.st_mode);
1060                 } else if (S_ISDIR(st.st_mode)) {
1061                         struct object_id oid;
1062                         if (resolve_gitlink_ref(elem->path, "HEAD", &oid) < 0)
1063                                 result = grab_blob(opt->repo, &elem->oid,
1064                                                    elem->mode, &result_size,
1065                                                    NULL, NULL);
1066                         else
1067                                 result = grab_blob(opt->repo, &oid, elem->mode,
1068                                                    &result_size, NULL, NULL);
1069                 } else if (textconv) {
1070                         struct diff_filespec *df = alloc_filespec(elem->path);
1071                         fill_filespec(df, &null_oid, 0, st.st_mode);
1072                         result_size = fill_textconv(opt->repo, textconv, df, &result);
1073                         free_filespec(df);
1074                 } else if (0 <= (fd = open(elem->path, O_RDONLY))) {
1075                         size_t len = xsize_t(st.st_size);
1076                         ssize_t done;
1077                         int is_file, i;
1078
1079                         elem->mode = canon_mode(st.st_mode);
1080                         /* if symlinks don't work, assume symlink if all parents
1081                          * are symlinks
1082                          */
1083                         is_file = has_symlinks;
1084                         for (i = 0; !is_file && i < num_parent; i++)
1085                                 is_file = !S_ISLNK(elem->parent[i].mode);
1086                         if (!is_file)
1087                                 elem->mode = canon_mode(S_IFLNK);
1088
1089                         result_size = len;
1090                         result = xmallocz(len);
1091
1092                         done = read_in_full(fd, result, len);
1093                         if (done < 0)
1094                                 die_errno("read error '%s'", elem->path);
1095                         else if (done < len)
1096                                 die("early EOF '%s'", elem->path);
1097
1098                         /* If not a fake symlink, apply filters, e.g. autocrlf */
1099                         if (is_file) {
1100                                 struct strbuf buf = STRBUF_INIT;
1101
1102                                 if (convert_to_git(rev->diffopt.repo->index,
1103                                                    elem->path, result, len, &buf, global_conv_flags_eol)) {
1104                                         free(result);
1105                                         result = strbuf_detach(&buf, &len);
1106                                         result_size = len;
1107                                 }
1108                         }
1109                 }
1110                 else {
1111                 deleted_file:
1112                         result_deleted = 1;
1113                         result_size = 0;
1114                         elem->mode = 0;
1115                         result = xcalloc(1, 1);
1116                 }
1117
1118                 if (0 <= fd)
1119                         close(fd);
1120         }
1121
1122         for (i = 0; i < num_parent; i++) {
1123                 if (elem->parent[i].mode != elem->mode) {
1124                         mode_differs = 1;
1125                         break;
1126                 }
1127         }
1128
1129         if (textconv)
1130                 is_binary = 0;
1131         else if (userdiff->binary != -1)
1132                 is_binary = userdiff->binary;
1133         else {
1134                 is_binary = buffer_is_binary(result, result_size);
1135                 for (i = 0; !is_binary && i < num_parent; i++) {
1136                         char *buf;
1137                         unsigned long size;
1138                         buf = grab_blob(opt->repo,
1139                                         &elem->parent[i].oid,
1140                                         elem->parent[i].mode,
1141                                         &size, NULL, NULL);
1142                         if (buffer_is_binary(buf, size))
1143                                 is_binary = 1;
1144                         free(buf);
1145                 }
1146         }
1147         if (is_binary) {
1148                 show_combined_header(elem, num_parent, dense, rev,
1149                                      line_prefix, mode_differs, 0);
1150                 printf("Binary files differ\n");
1151                 free(result);
1152                 return;
1153         }
1154
1155         for (cnt = 0, cp = result; cp < result + result_size; cp++) {
1156                 if (*cp == '\n')
1157                         cnt++;
1158         }
1159         if (result_size && result[result_size-1] != '\n')
1160                 cnt++; /* incomplete line */
1161
1162         sline = xcalloc(st_add(cnt, 2), sizeof(*sline));
1163         sline[0].bol = result;
1164         for (lno = 0, cp = result; cp < result + result_size; cp++) {
1165                 if (*cp == '\n') {
1166                         sline[lno].len = cp - sline[lno].bol;
1167                         lno++;
1168                         if (lno < cnt)
1169                                 sline[lno].bol = cp + 1;
1170                 }
1171         }
1172         if (result_size && result[result_size-1] != '\n')
1173                 sline[cnt-1].len = result_size - (sline[cnt-1].bol - result);
1174
1175         result_file.ptr = result;
1176         result_file.size = result_size;
1177
1178         /* Even p_lno[cnt+1] is valid -- that is for the end line number
1179          * for deletion hunk at the end.
1180          */
1181         sline[0].p_lno = xcalloc(st_mult(st_add(cnt, 2), num_parent), sizeof(unsigned long));
1182         for (lno = 0; lno <= cnt; lno++)
1183                 sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
1184
1185         for (i = 0; i < num_parent; i++) {
1186                 int j;
1187                 for (j = 0; j < i; j++) {
1188                         if (oideq(&elem->parent[i].oid,
1189                                   &elem->parent[j].oid)) {
1190                                 reuse_combine_diff(sline, cnt, i, j);
1191                                 break;
1192                         }
1193                 }
1194                 if (i <= j)
1195                         combine_diff(opt->repo,
1196                                      &elem->parent[i].oid,
1197                                      elem->parent[i].mode,
1198                                      &result_file, sline,
1199                                      cnt, i, num_parent, result_deleted,
1200                                      textconv, elem->path, opt->xdl_opts);
1201         }
1202
1203         show_hunks = make_hunks(sline, cnt, num_parent, dense);
1204
1205         if (show_hunks || mode_differs || working_tree_file) {
1206                 show_combined_header(elem, num_parent, dense, rev,
1207                                      line_prefix, mode_differs, 1);
1208                 dump_sline(sline, line_prefix, cnt, num_parent,
1209                            opt->use_color, result_deleted);
1210         }
1211         free(result);
1212
1213         for (lno = 0; lno < cnt; lno++) {
1214                 if (sline[lno].lost) {
1215                         struct lline *ll = sline[lno].lost;
1216                         while (ll) {
1217                                 struct lline *tmp = ll;
1218                                 ll = ll->next;
1219                                 free(tmp);
1220                         }
1221                 }
1222         }
1223         free(sline[0].p_lno);
1224         free(sline);
1225 }
1226
1227 static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct rev_info *rev)
1228 {
1229         struct diff_options *opt = &rev->diffopt;
1230         int line_termination, inter_name_termination, i;
1231         const char *line_prefix = diff_line_prefix(opt);
1232
1233         line_termination = opt->line_termination;
1234         inter_name_termination = '\t';
1235         if (!line_termination)
1236                 inter_name_termination = 0;
1237
1238         if (rev->loginfo && !rev->no_commit_id)
1239                 show_log(rev);
1240
1241
1242         if (opt->output_format & DIFF_FORMAT_RAW) {
1243                 printf("%s", line_prefix);
1244
1245                 /* As many colons as there are parents */
1246                 for (i = 0; i < num_parent; i++)
1247                         putchar(':');
1248
1249                 /* Show the modes */
1250                 for (i = 0; i < num_parent; i++)
1251                         printf("%06o ", p->parent[i].mode);
1252                 printf("%06o", p->mode);
1253
1254                 /* Show sha1's */
1255                 for (i = 0; i < num_parent; i++)
1256                         printf(" %s", diff_aligned_abbrev(&p->parent[i].oid,
1257                                                           opt->abbrev));
1258                 printf(" %s ", diff_aligned_abbrev(&p->oid, opt->abbrev));
1259         }
1260
1261         if (opt->output_format & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS)) {
1262                 for (i = 0; i < num_parent; i++)
1263                         putchar(p->parent[i].status);
1264                 putchar(inter_name_termination);
1265         }
1266
1267         for (i = 0; i < num_parent; i++)
1268                 if (rev->combined_all_paths) {
1269                         if (filename_changed(p->parent[i].status))
1270                                 write_name_quoted(p->parent[i].path.buf, stdout,
1271                                                   inter_name_termination);
1272                         else
1273                                 write_name_quoted(p->path, stdout,
1274                                                   inter_name_termination);
1275                 }
1276         write_name_quoted(p->path, stdout, line_termination);
1277 }
1278
1279 /*
1280  * The result (p->elem) is from the working tree and their
1281  * parents are typically from multiple stages during a merge
1282  * (i.e. diff-files) or the state in HEAD and in the index
1283  * (i.e. diff-index).
1284  */
1285 void show_combined_diff(struct combine_diff_path *p,
1286                        int num_parent,
1287                        int dense,
1288                        struct rev_info *rev)
1289 {
1290         struct diff_options *opt = &rev->diffopt;
1291
1292         if (opt->output_format & (DIFF_FORMAT_RAW |
1293                                   DIFF_FORMAT_NAME |
1294                                   DIFF_FORMAT_NAME_STATUS))
1295                 show_raw_diff(p, num_parent, rev);
1296         else if (opt->output_format & DIFF_FORMAT_PATCH)
1297                 show_patch_diff(p, num_parent, dense, 1, rev);
1298 }
1299
1300 static void free_combined_pair(struct diff_filepair *pair)
1301 {
1302         free(pair->two);
1303         free(pair);
1304 }
1305
1306 /*
1307  * A combine_diff_path expresses N parents on the LHS against 1 merge
1308  * result. Synthesize a diff_filepair that has N entries on the "one"
1309  * side and 1 entry on the "two" side.
1310  *
1311  * In the future, we might want to add more data to combine_diff_path
1312  * so that we can fill fields we are ignoring (most notably, size) here,
1313  * but currently nobody uses it, so this should suffice for now.
1314  */
1315 static struct diff_filepair *combined_pair(struct combine_diff_path *p,
1316                                            int num_parent)
1317 {
1318         int i;
1319         struct diff_filepair *pair;
1320         struct diff_filespec *pool;
1321
1322         pair = xmalloc(sizeof(*pair));
1323         pool = xcalloc(st_add(num_parent, 1), sizeof(struct diff_filespec));
1324         pair->one = pool + 1;
1325         pair->two = pool;
1326
1327         for (i = 0; i < num_parent; i++) {
1328                 pair->one[i].path = p->path;
1329                 pair->one[i].mode = p->parent[i].mode;
1330                 oidcpy(&pair->one[i].oid, &p->parent[i].oid);
1331                 pair->one[i].oid_valid = !is_null_oid(&p->parent[i].oid);
1332                 pair->one[i].has_more_entries = 1;
1333         }
1334         pair->one[num_parent - 1].has_more_entries = 0;
1335
1336         pair->two->path = p->path;
1337         pair->two->mode = p->mode;
1338         oidcpy(&pair->two->oid, &p->oid);
1339         pair->two->oid_valid = !is_null_oid(&p->oid);
1340         return pair;
1341 }
1342
1343 static void handle_combined_callback(struct diff_options *opt,
1344                                      struct combine_diff_path *paths,
1345                                      int num_parent,
1346                                      int num_paths)
1347 {
1348         struct combine_diff_path *p;
1349         struct diff_queue_struct q;
1350         int i;
1351
1352         q.queue = xcalloc(num_paths, sizeof(struct diff_filepair *));
1353         q.alloc = num_paths;
1354         q.nr = num_paths;
1355         for (i = 0, p = paths; p; p = p->next)
1356                 q.queue[i++] = combined_pair(p, num_parent);
1357         opt->format_callback(&q, opt, opt->format_callback_data);
1358         for (i = 0; i < num_paths; i++)
1359                 free_combined_pair(q.queue[i]);
1360         free(q.queue);
1361 }
1362
1363 static const char *path_path(void *obj)
1364 {
1365         struct combine_diff_path *path = (struct combine_diff_path *)obj;
1366
1367         return path->path;
1368 }
1369
1370 /*
1371  * Diff stat formats which we always compute solely against the first parent.
1372  */
1373 #define STAT_FORMAT_MASK (DIFF_FORMAT_NUMSTAT \
1374                           | DIFF_FORMAT_SHORTSTAT \
1375                           | DIFF_FORMAT_SUMMARY \
1376                           | DIFF_FORMAT_DIRSTAT \
1377                           | DIFF_FORMAT_DIFFSTAT)
1378
1379 /* find set of paths that every parent touches */
1380 static struct combine_diff_path *find_paths_generic(const struct object_id *oid,
1381         const struct oid_array *parents,
1382         struct diff_options *opt,
1383         int combined_all_paths)
1384 {
1385         struct combine_diff_path *paths = NULL;
1386         int i, num_parent = parents->nr;
1387
1388         int output_format = opt->output_format;
1389         const char *orderfile = opt->orderfile;
1390
1391         opt->output_format = DIFF_FORMAT_NO_OUTPUT;
1392         /* tell diff_tree to emit paths in sorted (=tree) order */
1393         opt->orderfile = NULL;
1394
1395         /* D(A,P1...Pn) = D(A,P1) ^ ... ^ D(A,Pn)  (wrt paths) */
1396         for (i = 0; i < num_parent; i++) {
1397                 /*
1398                  * show stat against the first parent even when doing
1399                  * combined diff.
1400                  */
1401                 int stat_opt = output_format & STAT_FORMAT_MASK;
1402                 if (i == 0 && stat_opt)
1403                         opt->output_format = stat_opt;
1404                 else
1405                         opt->output_format = DIFF_FORMAT_NO_OUTPUT;
1406                 diff_tree_oid(&parents->oid[i], oid, "", opt);
1407                 diffcore_std(opt);
1408                 paths = intersect_paths(paths, i, num_parent,
1409                                         combined_all_paths);
1410
1411                 /* if showing diff, show it in requested order */
1412                 if (opt->output_format != DIFF_FORMAT_NO_OUTPUT &&
1413                     orderfile) {
1414                         diffcore_order(orderfile);
1415                 }
1416
1417                 diff_flush(opt);
1418         }
1419
1420         opt->output_format = output_format;
1421         opt->orderfile = orderfile;
1422         return paths;
1423 }
1424
1425
1426 /*
1427  * find set of paths that everybody touches, assuming diff is run without
1428  * rename/copy detection, etc, comparing all trees simultaneously (= faster).
1429  */
1430 static struct combine_diff_path *find_paths_multitree(
1431         const struct object_id *oid, const struct oid_array *parents,
1432         struct diff_options *opt)
1433 {
1434         int i, nparent = parents->nr;
1435         const struct object_id **parents_oid;
1436         struct combine_diff_path paths_head;
1437         struct strbuf base;
1438
1439         ALLOC_ARRAY(parents_oid, nparent);
1440         for (i = 0; i < nparent; i++)
1441                 parents_oid[i] = &parents->oid[i];
1442
1443         /* fake list head, so worker can assume it is non-NULL */
1444         paths_head.next = NULL;
1445
1446         strbuf_init(&base, PATH_MAX);
1447         diff_tree_paths(&paths_head, oid, parents_oid, nparent, &base, opt);
1448
1449         strbuf_release(&base);
1450         free(parents_oid);
1451         return paths_head.next;
1452 }
1453
1454
1455 void diff_tree_combined(const struct object_id *oid,
1456                         const struct oid_array *parents,
1457                         int dense,
1458                         struct rev_info *rev)
1459 {
1460         struct diff_options *opt = &rev->diffopt;
1461         struct diff_options diffopts;
1462         struct combine_diff_path *p, *paths;
1463         int i, num_paths, needsep, show_log_first, num_parent = parents->nr;
1464         int need_generic_pathscan;
1465
1466         /* nothing to do, if no parents */
1467         if (!num_parent)
1468                 return;
1469
1470         show_log_first = !!rev->loginfo && !rev->no_commit_id;
1471         needsep = 0;
1472         if (show_log_first) {
1473                 show_log(rev);
1474
1475                 if (rev->verbose_header && opt->output_format &&
1476                     opt->output_format != DIFF_FORMAT_NO_OUTPUT &&
1477                     !commit_format_is_empty(rev->commit_format))
1478                         printf("%s%c", diff_line_prefix(opt),
1479                                opt->line_termination);
1480         }
1481
1482         diffopts = *opt;
1483         copy_pathspec(&diffopts.pathspec, &opt->pathspec);
1484         diffopts.flags.recursive = 1;
1485         diffopts.flags.allow_external = 0;
1486
1487         /* find set of paths that everybody touches
1488          *
1489          * NOTE
1490          *
1491          * Diffcore transformations are bound to diff_filespec and logic
1492          * comparing two entries - i.e. they do not apply directly to combine
1493          * diff.
1494          *
1495          * If some of such transformations is requested - we launch generic
1496          * path scanning, which works significantly slower compared to
1497          * simultaneous all-trees-in-one-go scan in find_paths_multitree().
1498          *
1499          * TODO some of the filters could be ported to work on
1500          * combine_diff_paths - i.e. all functionality that skips paths, so in
1501          * theory, we could end up having only multitree path scanning.
1502          *
1503          * NOTE please keep this semantically in sync with diffcore_std()
1504          */
1505         need_generic_pathscan = opt->skip_stat_unmatch  ||
1506                         opt->flags.follow_renames       ||
1507                         opt->break_opt != -1    ||
1508                         opt->detect_rename      ||
1509                         (opt->pickaxe_opts & DIFF_PICKAXE_KINDS_MASK)   ||
1510                         opt->filter;
1511
1512
1513         if (need_generic_pathscan) {
1514                 /*
1515                  * NOTE generic case also handles --stat, as it computes
1516                  * diff(sha1,parent_i) for all i to do the job, specifically
1517                  * for parent0.
1518                  */
1519                 paths = find_paths_generic(oid, parents, &diffopts,
1520                                            rev->combined_all_paths);
1521         }
1522         else {
1523                 int stat_opt;
1524                 paths = find_paths_multitree(oid, parents, &diffopts);
1525
1526                 /*
1527                  * show stat against the first parent even
1528                  * when doing combined diff.
1529                  */
1530                 stat_opt = opt->output_format & STAT_FORMAT_MASK;
1531                 if (stat_opt) {
1532                         diffopts.output_format = stat_opt;
1533
1534                         diff_tree_oid(&parents->oid[0], oid, "", &diffopts);
1535                         diffcore_std(&diffopts);
1536                         if (opt->orderfile)
1537                                 diffcore_order(opt->orderfile);
1538                         diff_flush(&diffopts);
1539                 }
1540         }
1541
1542         /* find out number of surviving paths */
1543         for (num_paths = 0, p = paths; p; p = p->next)
1544                 num_paths++;
1545
1546         /* order paths according to diffcore_order */
1547         if (opt->orderfile && num_paths) {
1548                 struct obj_order *o;
1549
1550                 ALLOC_ARRAY(o, num_paths);
1551                 for (i = 0, p = paths; p; p = p->next, i++)
1552                         o[i].obj = p;
1553                 order_objects(opt->orderfile, path_path, o, num_paths);
1554                 for (i = 0; i < num_paths - 1; i++) {
1555                         p = o[i].obj;
1556                         p->next = o[i+1].obj;
1557                 }
1558
1559                 p = o[num_paths-1].obj;
1560                 p->next = NULL;
1561                 paths = o[0].obj;
1562                 free(o);
1563         }
1564
1565
1566         if (num_paths) {
1567                 if (opt->output_format & (DIFF_FORMAT_RAW |
1568                                           DIFF_FORMAT_NAME |
1569                                           DIFF_FORMAT_NAME_STATUS)) {
1570                         for (p = paths; p; p = p->next)
1571                                 show_raw_diff(p, num_parent, rev);
1572                         needsep = 1;
1573                 }
1574                 else if (opt->output_format & STAT_FORMAT_MASK)
1575                         needsep = 1;
1576                 else if (opt->output_format & DIFF_FORMAT_CALLBACK)
1577                         handle_combined_callback(opt, paths, num_parent, num_paths);
1578
1579                 if (opt->output_format & DIFF_FORMAT_PATCH) {
1580                         if (needsep)
1581                                 printf("%s%c", diff_line_prefix(opt),
1582                                        opt->line_termination);
1583                         for (p = paths; p; p = p->next)
1584                                 show_patch_diff(p, num_parent, dense,
1585                                                 0, rev);
1586                 }
1587         }
1588
1589         /* Clean things up */
1590         while (paths) {
1591                 struct combine_diff_path *tmp = paths;
1592                 paths = paths->next;
1593                 for (i = 0; i < num_parent; i++)
1594                         if (rev->combined_all_paths &&
1595                             filename_changed(tmp->parent[i].status))
1596                                 strbuf_release(&tmp->parent[i].path);
1597                 free(tmp);
1598         }
1599
1600         clear_pathspec(&diffopts.pathspec);
1601 }
1602
1603 void diff_tree_combined_merge(const struct commit *commit, int dense,
1604                               struct rev_info *rev)
1605 {
1606         struct commit_list *parent = get_saved_parents(rev, commit);
1607         struct oid_array parents = OID_ARRAY_INIT;
1608
1609         while (parent) {
1610                 oid_array_append(&parents, &parent->item->object.oid);
1611                 parent = parent->next;
1612         }
1613         diff_tree_combined(&commit->object.oid, &parents, dense, rev);
1614         oid_array_clear(&parents);
1615 }