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

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "blob.h"
   4 #include "diff.h"
   5 #include "diffcore.h"
   6 #include "quote.h"
   7 #include "xdiff-interface.h"
   8 #include "xdiff/xmacros.h"
   9 #include "log-tree.h"
  10 #include "refs.h"
  11 #include "userdiff.h"
  12 #include "sha1-array.h"
  13 #include "revision.h"
  14
  15 static int compare_paths(const struct combine_diff_path *one,
  16                           const struct diff_filespec *two)
  17 {
  18         if (!S_ISDIR(one->mode) && !S_ISDIR(two->mode))
  19                 return strcmp(one->path, two->path);
  20
  21         return base_name_compare(one->path, strlen(one->path), one->mode,
  22                                  two->path, strlen(two->path), two->mode);
  23 }
  24
  25 static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr, int n, int num_parent)
  26 {
  27         struct diff_queue_struct *q = &diff_queued_diff;
  28         struct combine_diff_path *p, **tail = &curr;
  29         int i, cmp;
  30
  31         if (!n) {
  32                 for (i = 0; i < q->nr; i++) {
  33                         int len;
  34                         const char *path;
  35                         if (diff_unmodified_pair(q->queue[i]))
  36                                 continue;
  37                         path = q->queue[i]->two->path;
  38                         len = strlen(path);
  39                         p = xmalloc(combine_diff_path_size(num_parent, len));
  40                         p->path = (char *) &(p->parent[num_parent]);
  41                         memcpy(p->path, path, len);
  42                         p->path[len] = 0;
  43                         p->next = NULL;
  44                         memset(p->parent, 0,
  45                                sizeof(p->parent[0]) * num_parent);
  46
  47                         oidcpy(&p->oid, &q->queue[i]->two->oid);
  48                         p->mode = q->queue[i]->two->mode;
  49                         oidcpy(&p->parent[n].oid, &q->queue[i]->one->oid);
  50                         p->parent[n].mode = q->queue[i]->one->mode;
  51                         p->parent[n].status = q->queue[i]->status;
  52                         *tail = p;
  53                         tail = &p->next;
  54                 }
  55                 return curr;
  56         }
  57
  58         /*
  59          * paths in curr (linked list) and q->queue[] (array) are
  60          * both sorted in the tree order.
  61          */
  62         i = 0;
  63         while ((p = *tail) != NULL) {
  64                 cmp = ((i >= q->nr)
  65                        ? -1 : compare_paths(p, q->queue[i]->two));
  66
  67                 if (cmp < 0) {
  68                         /* p->path not in q->queue[]; drop it */
  69                         *tail = p->next;
  70                         free(p);
  71                         continue;
  72                 }
  73
  74                 if (cmp > 0) {
  75                         /* q->queue[i] not in p->path; skip it */
  76                         i++;
  77                         continue;
  78                 }
  79
  80                 oidcpy(&p->parent[n].oid, &q->queue[i]->one->oid);
  81                 p->parent[n].mode = q->queue[i]->one->mode;
  82                 p->parent[n].status = q->queue[i]->status;
  83
  84                 tail = &p->next;
  85                 i++;
  86         }
  87         return curr;
  88 }
  89
  90 /* Lines lost from parent */
  91 struct lline {
  92         struct lline *next, *prev;
  93         int len;
  94         unsigned long parent_map;
  95         char line[FLEX_ARRAY];
  96 };
  97
  98 /* Lines lost from current parent (before coalescing) */
  99 struct plost {
 100         struct lline *lost_head, *lost_tail;
 101         int len;
 102 };
 103
 104 /* Lines surviving in the merge result */
 105 struct sline {
 106         /* Accumulated and coalesced lost lines */
 107         struct lline *lost;
 108         int lenlost;
 109         struct plost plost;
 110         char *bol;
 111         int len;
 112         /* bit 0 up to (N-1) are on if the parent has this line (i.e.
 113          * we did not change it).
 114          * bit N is used for "interesting" lines, including context.
 115          * bit (N+1) is used for "do not show deletion before this".
 116          */
 117         unsigned long flag;
 118         unsigned long *p_lno;
 119 };
 120
 121 static int match_string_spaces(const char *line1, int len1,
 122                                const char *line2, int len2,
 123                                long flags)
 124 {
 125         if (flags & XDF_WHITESPACE_FLAGS) {
 126                 for (; len1 > 0 && XDL_ISSPACE(line1[len1 - 1]); len1--);
 127                 for (; len2 > 0 && XDL_ISSPACE(line2[len2 - 1]); len2--);
 128         }
 129
 130         if (!(flags & (XDF_IGNORE_WHITESPACE | XDF_IGNORE_WHITESPACE_CHANGE)))
 131                 return (len1 == len2 && !memcmp(line1, line2, len1));
 132
 133         while (len1 > 0 && len2 > 0) {
 134                 len1--;
 135                 len2--;
 136                 if (XDL_ISSPACE(line1[len1]) || XDL_ISSPACE(line2[len2])) {
 137                         if ((flags & XDF_IGNORE_WHITESPACE_CHANGE) &&
 138                             (!XDL_ISSPACE(line1[len1]) || !XDL_ISSPACE(line2[len2])))
 139                                 return 0;
 140
 141                         for (; len1 > 0 && XDL_ISSPACE(line1[len1]); len1--);
 142                         for (; len2 > 0 && XDL_ISSPACE(line2[len2]); len2--);
 143                 }
 144                 if (line1[len1] != line2[len2])
 145                         return 0;
 146         }
 147
 148         if (flags & XDF_IGNORE_WHITESPACE) {
 149                 /* Consume remaining spaces */
 150                 for (; len1 > 0 && XDL_ISSPACE(line1[len1 - 1]); len1--);
 151                 for (; len2 > 0 && XDL_ISSPACE(line2[len2 - 1]); len2--);
 152         }
 153
 154         /* We matched full line1 and line2 */
 155         if (!len1 && !len2)
 156                 return 1;
 157
 158         return 0;
 159 }
 160
 161 enum coalesce_direction { MATCH, BASE, NEW };
 162
 163 /* Coalesce new lines into base by finding LCS */
 164 static struct lline *coalesce_lines(struct lline *base, int *lenbase,
 165                                     struct lline *new, int lennew,
 166                                     unsigned long parent, long flags)
 167 {
 168         int **lcs;
 169         enum coalesce_direction **directions;
 170         struct lline *baseend, *newend = NULL;
 171         int i, j, origbaselen = *lenbase;
 172
 173         if (new == NULL)
 174                 return base;
 175
 176         if (base == NULL) {
 177                 *lenbase = lennew;
 178                 return new;
 179         }
 180
 181         /*
 182          * Coalesce new lines into base by finding the LCS
 183          * - Create the table to run dynamic programming
 184          * - Compute the LCS
 185          * - Then reverse read the direction structure:
 186          *   - If we have MATCH, assign parent to base flag, and consume
 187          *   both baseend and newend
 188          *   - Else if we have BASE, consume baseend
 189          *   - Else if we have NEW, insert newend lline into base and
 190          *   consume newend
 191          */
 192         lcs = xcalloc(st_add(origbaselen, 1), sizeof(int*));
 193         directions = xcalloc(st_add(origbaselen, 1), sizeof(enum coalesce_direction*));
 194         for (i = 0; i < origbaselen + 1; i++) {
 195                 lcs[i] = xcalloc(st_add(lennew, 1), sizeof(int));
 196                 directions[i] = xcalloc(st_add(lennew, 1), sizeof(enum coalesce_direction));
 197                 directions[i][0] = BASE;
 198         }
 199         for (j = 1; j < lennew + 1; j++)
 200                 directions[0][j] = NEW;
 201
 202         for (i = 1, baseend = base; i < origbaselen + 1; i++) {
 203                 for (j = 1, newend = new; j < lennew + 1; j++) {
 204                         if (match_string_spaces(baseend->line, baseend->len,
 205                                                 newend->line, newend->len, flags)) {
 206                                 lcs[i][j] = lcs[i - 1][j - 1] + 1;
 207                                 directions[i][j] = MATCH;
 208                         } else if (lcs[i][j - 1] >= lcs[i - 1][j]) {
 209                                 lcs[i][j] = lcs[i][j - 1];
 210                                 directions[i][j] = NEW;
 211                         } else {
 212                                 lcs[i][j] = lcs[i - 1][j];
 213                                 directions[i][j] = BASE;
 214                         }
 215                         if (newend->next)
 216                                 newend = newend->next;
 217                 }
 218                 if (baseend->next)
 219                         baseend = baseend->next;
 220         }
 221
 222         for (i = 0; i < origbaselen + 1; i++)
 223                 free(lcs[i]);
 224         free(lcs);
 225
 226         /* At this point, baseend and newend point to the end of each lists */
 227         i--;
 228         j--;
 229         while (i != 0 || j != 0) {
 230                 if (directions[i][j] == MATCH) {
 231                         baseend->parent_map |= 1<<parent;
 232                         baseend = baseend->prev;
 233                         newend = newend->prev;
 234                         i--;
 235                         j--;
 236                 } else if (directions[i][j] == NEW) {
 237                         struct lline *lline;
 238
 239                         lline = newend;
 240                         /* Remove lline from new list and update newend */
 241                         if (lline->prev)
 242                                 lline->prev->next = lline->next;
 243                         else
 244                                 new = lline->next;
 245                         if (lline->next)
 246                                 lline->next->prev = lline->prev;
 247
 248                         newend = lline->prev;
 249                         j--;
 250
 251                         /* Add lline to base list */
 252                         if (baseend) {
 253                                 lline->next = baseend->next;
 254                                 lline->prev = baseend;
 255                                 if (lline->prev)
 256                                         lline->prev->next = lline;
 257                         }
 258                         else {
 259                                 lline->next = base;
 260                                 base = lline;
 261                         }
 262                         (*lenbase)++;
 263
 264                         if (lline->next)
 265                                 lline->next->prev = lline;
 266
 267                 } else {
 268                         baseend = baseend->prev;
 269                         i--;
 270                 }
 271         }
 272
 273         newend = new;
 274         while (newend) {
 275                 struct lline *lline = newend;
 276                 newend = newend->next;
 277                 free(lline);
 278         }
 279
 280         for (i = 0; i < origbaselen + 1; i++)
 281                 free(directions[i]);
 282         free(directions);
 283
 284         return base;
 285 }
 286
 287 static char *grab_blob(const struct object_id *oid, unsigned int mode,
 288                        unsigned long *size, struct userdiff_driver *textconv,
 289                        const char *path)
 290 {
 291         char *blob;
 292         enum object_type type;
 293
 294         if (S_ISGITLINK(mode)) {
 295                 blob = xmalloc(100);
 296                 *size = snprintf(blob, 100,
 297                                  "Subproject commit %s\n", oid_to_hex(oid));
 298         } else if (is_null_oid(oid)) {
 299                 /* deleted blob */
 300                 *size = 0;
 301                 return xcalloc(1, 1);
 302         } else if (textconv) {
 303                 struct diff_filespec *df = alloc_filespec(path);
 304                 fill_filespec(df, oid->hash, 1, mode);
 305                 *size = fill_textconv(textconv, df, &blob);
 306                 free_filespec(df);
 307         } else {
 308                 blob = read_sha1_file(oid->hash, &type, size);
 309                 if (type != OBJ_BLOB)
 310                         die("object '%s' is not a blob!", oid_to_hex(oid));
 311         }
 312         return blob;
 313 }
 314
 315 static void append_lost(struct sline *sline, int n, const char *line, int len)
 316 {
 317         struct lline *lline;
 318         unsigned long this_mask = (1UL<<n);
 319         if (line[len-1] == '\n')
 320                 len--;
 321
 322         FLEX_ALLOC_MEM(lline, line, line, len);
 323         lline->len = len;
 324         lline->next = NULL;
 325         lline->prev = sline->plost.lost_tail;
 326         if (lline->prev)
 327                 lline->prev->next = lline;
 328         else
 329                 sline->plost.lost_head = lline;
 330         sline->plost.lost_tail = lline;
 331         sline->plost.len++;
 332         lline->parent_map = this_mask;
 333 }
 334
 335 struct combine_diff_state {
 336         unsigned int lno;
 337         int ob, on, nb, nn;
 338         unsigned long nmask;
 339         int num_parent;
 340         int n;
 341         struct sline *sline;
 342         struct sline *lost_bucket;
 343 };
 344
 345 static void consume_line(void *state_, char *line, unsigned long len)
 346 {
 347         struct combine_diff_state *state = state_;
 348         if (5 < len && !memcmp("@@ -", line, 4)) {
 349                 if (parse_hunk_header(line, len,
 350                                       &state->ob, &state->on,
 351                                       &state->nb, &state->nn))
 352                         return;
 353                 state->lno = state->nb;
 354                 if (state->nn == 0) {
 355                         /* @@ -X,Y +N,0 @@ removed Y lines
 356                          * that would have come *after* line N
 357                          * in the result.  Our lost buckets hang
 358                          * to the line after the removed lines,
 359                          *
 360                          * Note that this is correct even when N == 0,
 361                          * in which case the hunk removes the first
 362                          * line in the file.
 363                          */
 364                         state->lost_bucket = &state->sline[state->nb];
 365                         if (!state->nb)
 366                                 state->nb = 1;
 367                 } else {
 368                         state->lost_bucket = &state->sline[state->nb-1];
 369                 }
 370                 if (!state->sline[state->nb-1].p_lno)
 371                         state->sline[state->nb-1].p_lno =
 372                                 xcalloc(state->num_parent,
 373                                         sizeof(unsigned long));
 374                 state->sline[state->nb-1].p_lno[state->n] = state->ob;
 375                 return;
 376         }
 377         if (!state->lost_bucket)
 378                 return; /* not in any hunk yet */
 379         switch (line[0]) {
 380         case '-':
 381                 append_lost(state->lost_bucket, state->n, line+1, len-1);
 382                 break;
 383         case '+':
 384                 state->sline[state->lno-1].flag |= state->nmask;
 385                 state->lno++;
 386                 break;
 387         }
 388 }
 389
 390 static void combine_diff(const struct object_id *parent, unsigned int mode,
 391                          mmfile_t *result_file,
 392                          struct sline *sline, unsigned int cnt, int n,
 393                          int num_parent, int result_deleted,
 394                          struct userdiff_driver *textconv,
 395                          const char *path, long flags)
 396 {
 397         unsigned int p_lno, lno;
 398         unsigned long nmask = (1UL << n);
 399         xpparam_t xpp;
 400         xdemitconf_t xecfg;
 401         mmfile_t parent_file;
 402         struct combine_diff_state state;
 403         unsigned long sz;
 404
 405         if (result_deleted)
 406                 return; /* result deleted */
 407
 408         parent_file.ptr = grab_blob(parent, mode, &sz, textconv, path);
 409         parent_file.size = sz;
 410         memset(&xpp, 0, sizeof(xpp));
 411         xpp.flags = flags;
 412         memset(&xecfg, 0, sizeof(xecfg));
 413         memset(&state, 0, sizeof(state));
 414         state.nmask = nmask;
 415         state.sline = sline;
 416         state.lno = 1;
 417         state.num_parent = num_parent;
 418         state.n = n;
 419
 420         if (xdi_diff_outf(&parent_file, result_file, consume_line, &state,
 421                           &xpp, &xecfg))
 422                 die("unable to generate combined diff for %s",
 423                     oid_to_hex(parent));
 424         free(parent_file.ptr);
 425
 426         /* Assign line numbers for this parent.
 427          *
 428          * sline[lno].p_lno[n] records the first line number
 429          * (counting from 1) for parent N if the final hunk display
 430          * started by showing sline[lno] (possibly showing the lost
 431          * lines attached to it first).
 432          */
 433         for (lno = 0,  p_lno = 1; lno <= cnt; lno++) {
 434                 struct lline *ll;
 435                 sline[lno].p_lno[n] = p_lno;
 436
 437                 /* Coalesce new lines */
 438                 if (sline[lno].plost.lost_head) {
 439                         struct sline *sl = &sline[lno];
 440                         sl->lost = coalesce_lines(sl->lost, &sl->lenlost,
 441                                                   sl->plost.lost_head,
 442                                                   sl->plost.len, n, flags);
 443                         sl->plost.lost_head = sl->plost.lost_tail = NULL;
 444                         sl->plost.len = 0;
 445                 }
 446
 447                 /* How many lines would this sline advance the p_lno? */
 448                 ll = sline[lno].lost;
 449                 while (ll) {
 450                         if (ll->parent_map & nmask)
 451                                 p_lno++; /* '-' means parent had it */
 452                         ll = ll->next;
 453                 }
 454                 if (lno < cnt && !(sline[lno].flag & nmask))
 455                         p_lno++; /* no '+' means parent had it */
 456         }
 457         sline[lno].p_lno[n] = p_lno; /* trailer */
 458 }
 459
 460 static unsigned long context = 3;
 461 static char combine_marker = '@';
 462
 463 static int interesting(struct sline *sline, unsigned long all_mask)
 464 {
 465         /* If some parents lost lines here, or if we have added to
 466          * some parent, it is interesting.
 467          */
 468         return ((sline->flag & all_mask) || sline->lost);
 469 }
 470
 471 static unsigned long adjust_hunk_tail(struct sline *sline,
 472                                       unsigned long all_mask,
 473                                       unsigned long hunk_begin,
 474                                       unsigned long i)
 475 {
 476         /* i points at the first uninteresting line.  If the last line
 477          * of the hunk was interesting only because it has some
 478          * deletion, then it is not all that interesting for the
 479          * purpose of giving trailing context lines.  This is because
 480          * we output '-' line and then unmodified sline[i-1] itself in
 481          * that case which gives us one extra context line.
 482          */
 483         if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
 484                 i--;
 485         return i;
 486 }
 487
 488 static unsigned long find_next(struct sline *sline,
 489                                unsigned long mark,
 490                                unsigned long i,
 491                                unsigned long cnt,
 492                                int look_for_uninteresting)
 493 {
 494         /* We have examined up to i-1 and are about to look at i.
 495          * Find next interesting or uninteresting line.  Here,
 496          * "interesting" does not mean interesting(), but marked by
 497          * the give_context() function below (i.e. it includes context
 498          * lines that are not interesting to interesting() function
 499          * that are surrounded by interesting() ones.
 500          */
 501         while (i <= cnt)
 502                 if (look_for_uninteresting
 503                     ? !(sline[i].flag & mark)
 504                     : (sline[i].flag & mark))
 505                         return i;
 506                 else
 507                         i++;
 508         return i;
 509 }
 510
 511 static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
 512 {
 513         unsigned long all_mask = (1UL<<num_parent) - 1;
 514         unsigned long mark = (1UL<<num_parent);
 515         unsigned long no_pre_delete = (2UL<<num_parent);
 516         unsigned long i;
 517
 518         /* Two groups of interesting lines may have a short gap of
 519          * uninteresting lines.  Connect such groups to give them a
 520          * bit of context.
 521          *
 522          * We first start from what the interesting() function says,
 523          * and mark them with "mark", and paint context lines with the
 524          * mark.  So interesting() would still say false for such context
 525          * lines but they are treated as "interesting" in the end.
 526          */
 527         i = find_next(sline, mark, 0, cnt, 0);
 528         if (cnt < i)
 529                 return 0;
 530
 531         while (i <= cnt) {
 532                 unsigned long j = (context < i) ? (i - context) : 0;
 533                 unsigned long k;
 534
 535                 /* Paint a few lines before the first interesting line. */
 536                 while (j < i) {
 537                         if (!(sline[j].flag & mark))
 538                                 sline[j].flag |= no_pre_delete;
 539                         sline[j++].flag |= mark;
 540                 }
 541
 542         again:
 543                 /* we know up to i is to be included.  where does the
 544                  * next uninteresting one start?
 545                  */
 546                 j = find_next(sline, mark, i, cnt, 1);
 547                 if (cnt < j)
 548                         break; /* the rest are all interesting */
 549
 550                 /* lookahead context lines */
 551                 k = find_next(sline, mark, j, cnt, 0);
 552                 j = adjust_hunk_tail(sline, all_mask, i, j);
 553
 554                 if (k < j + context) {
 555                         /* k is interesting and [j,k) are not, but
 556                          * paint them interesting because the gap is small.
 557                          */
 558                         while (j < k)
 559                                 sline[j++].flag |= mark;
 560                         i = k;
 561                         goto again;
 562                 }
 563
 564                 /* j is the first uninteresting line and there is
 565                  * no overlap beyond it within context lines.  Paint
 566                  * the trailing edge a bit.
 567                  */
 568                 i = k;
 569                 k = (j + context < cnt+1) ? j + context : cnt+1;
 570                 while (j < k)
 571                         sline[j++].flag |= mark;
 572         }
 573         return 1;
 574 }
 575
 576 static int make_hunks(struct sline *sline, unsigned long cnt,
 577                        int num_parent, int dense)
 578 {
 579         unsigned long all_mask = (1UL<<num_parent) - 1;
 580         unsigned long mark = (1UL<<num_parent);
 581         unsigned long i;
 582         int has_interesting = 0;
 583
 584         for (i = 0; i <= cnt; i++) {
 585                 if (interesting(&sline[i], all_mask))
 586                         sline[i].flag |= mark;
 587                 else
 588                         sline[i].flag &= ~mark;
 589         }
 590         if (!dense)
 591                 return give_context(sline, cnt, num_parent);
 592
 593         /* Look at each hunk, and if we have changes from only one
 594          * parent, or the changes are the same from all but one
 595          * parent, mark that uninteresting.
 596          */
 597         i = 0;
 598         while (i <= cnt) {
 599                 unsigned long j, hunk_begin, hunk_end;
 600                 unsigned long same_diff;
 601                 while (i <= cnt && !(sline[i].flag & mark))
 602                         i++;
 603                 if (cnt < i)
 604                         break; /* No more interesting hunks */
 605                 hunk_begin = i;
 606                 for (j = i + 1; j <= cnt; j++) {
 607                         if (!(sline[j].flag & mark)) {
 608                                 /* Look beyond the end to see if there
 609                                  * is an interesting line after this
 610                                  * hunk within context span.
 611                                  */
 612                                 unsigned long la; /* lookahead */
 613                                 int contin = 0;
 614                                 la = adjust_hunk_tail(sline, all_mask,
 615                                                      hunk_begin, j);
 616                                 la = (la + context < cnt + 1) ?
 617                                         (la + context) : cnt + 1;
 618                                 while (la && j <= --la) {
 619                                         if (sline[la].flag & mark) {
 620                                                 contin = 1;
 621                                                 break;
 622                                         }
 623                                 }
 624                                 if (!contin)
 625                                         break;
 626                                 j = la;
 627                         }
 628                 }
 629                 hunk_end = j;
 630
 631                 /* [i..hunk_end) are interesting.  Now is it really
 632                  * interesting?  We check if there are only two versions
 633                  * and the result matches one of them.  That is, we look
 634                  * at:
 635                  *   (+) line, which records lines added to which parents;
 636                  *       this line appears in the result.
 637                  *   (-) line, which records from what parents the line
 638                  *       was removed; this line does not appear in the result.
 639                  * then check the set of parents the result has difference
 640                  * from, from all lines.  If there are lines that has
 641                  * different set of parents that the result has differences
 642                  * from, that means we have more than two versions.
 643                  *
 644                  * Even when we have only two versions, if the result does
 645                  * not match any of the parents, the it should be considered
 646                  * interesting.  In such a case, we would have all '+' line.
 647                  * After passing the above "two versions" test, that would
 648                  * appear as "the same set of parents" to be "all parents".
 649                  */
 650                 same_diff = 0;
 651                 has_interesting = 0;
 652                 for (j = i; j < hunk_end && !has_interesting; j++) {
 653                         unsigned long this_diff = sline[j].flag & all_mask;
 654                         struct lline *ll = sline[j].lost;
 655                         if (this_diff) {
 656                                 /* This has some changes.  Is it the
 657                                  * same as others?
 658                                  */
 659                                 if (!same_diff)
 660                                         same_diff = this_diff;
 661                                 else if (same_diff != this_diff) {
 662                                         has_interesting = 1;
 663                                         break;
 664                                 }
 665                         }
 666                         while (ll && !has_interesting) {
 667                                 /* Lost this line from these parents;
 668                                  * who are they?  Are they the same?
 669                                  */
 670                                 this_diff = ll->parent_map;
 671                                 if (!same_diff)
 672                                         same_diff = this_diff;
 673                                 else if (same_diff != this_diff) {
 674                                         has_interesting = 1;
 675                                 }
 676                                 ll = ll->next;
 677                         }
 678                 }
 679
 680                 if (!has_interesting && same_diff != all_mask) {
 681                         /* This hunk is not that interesting after all */
 682                         for (j = hunk_begin; j < hunk_end; j++)
 683                                 sline[j].flag &= ~mark;
 684                 }
 685                 i = hunk_end;
 686         }
 687
 688         has_interesting = give_context(sline, cnt, num_parent);
 689         return has_interesting;
 690 }
 691
 692 static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, int n, unsigned long null_context)
 693 {
 694         l0 = sline[l0].p_lno[n];
 695         l1 = sline[l1].p_lno[n];
 696         printf(" -%lu,%lu", l0, l1-l0-null_context);
 697 }
 698
 699 static int hunk_comment_line(const char *bol)
 700 {
 701         int ch;
 702
 703         if (!bol)
 704                 return 0;
 705         ch = *bol & 0xff;
 706         return (isalpha(ch) || ch == '_' || ch == '$');
 707 }
 708
 709 static void show_line_to_eol(const char *line, int len, const char *reset)
 710 {
 711         int saw_cr_at_eol = 0;
 712         if (len < 0)
 713                 len = strlen(line);
 714         saw_cr_at_eol = (len && line[len-1] == '\r');
 715
 716         printf("%.*s%s%s\n", len - saw_cr_at_eol, line,
 717                reset,
 718                saw_cr_at_eol ? "\r" : "");
 719 }
 720
 721 static void dump_sline(struct sline *sline, const char *line_prefix,
 722                        unsigned long cnt, int num_parent,
 723                        int use_color, int result_deleted)
 724 {
 725         unsigned long mark = (1UL<<num_parent);
 726         unsigned long no_pre_delete = (2UL<<num_parent);
 727         int i;
 728         unsigned long lno = 0;
 729         const char *c_frag = diff_get_color(use_color, DIFF_FRAGINFO);
 730         const char *c_func = diff_get_color(use_color, DIFF_FUNCINFO);
 731         const char *c_new = diff_get_color(use_color, DIFF_FILE_NEW);
 732         const char *c_old = diff_get_color(use_color, DIFF_FILE_OLD);
 733         const char *c_context = diff_get_color(use_color, DIFF_CONTEXT);
 734         const char *c_reset = diff_get_color(use_color, DIFF_RESET);
 735
 736         if (result_deleted)
 737                 return; /* result deleted */
 738
 739         while (1) {
 740                 unsigned long hunk_end;
 741                 unsigned long rlines;
 742                 const char *hunk_comment = NULL;
 743                 unsigned long null_context = 0;
 744
 745                 while (lno <= cnt && !(sline[lno].flag & mark)) {
 746                         if (hunk_comment_line(sline[lno].bol))
 747                                 hunk_comment = sline[lno].bol;
 748                         lno++;
 749                 }
 750                 if (cnt < lno)
 751                         break;
 752                 else {
 753                         for (hunk_end = lno + 1; hunk_end <= cnt; hunk_end++)
 754                                 if (!(sline[hunk_end].flag & mark))
 755                                         break;
 756                 }
 757                 rlines = hunk_end - lno;
 758                 if (cnt < hunk_end)
 759                         rlines--; /* pointing at the last delete hunk */
 760
 761                 if (!context) {
 762                         /*
 763                          * Even when running with --unified=0, all
 764                          * lines in the hunk needs to be processed in
 765                          * the loop below in order to show the
 766                          * deletion recorded in lost_head.  However,
 767                          * we do not want to show the resulting line
 768                          * with all blank context markers in such a
 769                          * case.  Compensate.
 770                          */
 771                         unsigned long j;
 772                         for (j = lno; j < hunk_end; j++)
 773                                 if (!(sline[j].flag & (mark-1)))
 774                                         null_context++;
 775                         rlines -= null_context;
 776                 }
 777
 778                 printf("%s%s", line_prefix, c_frag);
 779                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 780                 for (i = 0; i < num_parent; i++)
 781                         show_parent_lno(sline, lno, hunk_end, i, null_context);
 782                 printf(" +%lu,%lu ", lno+1, rlines);
 783                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 784
 785                 if (hunk_comment) {
 786                         int comment_end = 0;
 787                         for (i = 0; i < 40; i++) {
 788                                 int ch = hunk_comment[i] & 0xff;
 789                                 if (!ch || ch == '\n')
 790                                         break;
 791                                 if (!isspace(ch))
 792                                     comment_end = i;
 793                         }
 794                         if (comment_end)
 795                                 printf("%s%s %s%s", c_reset,
 796                                                     c_context, c_reset,
 797                                                     c_func);
 798                         for (i = 0; i < comment_end; i++)
 799                                 putchar(hunk_comment[i]);
 800                 }
 801
 802                 printf("%s\n", c_reset);
 803                 while (lno < hunk_end) {
 804                         struct lline *ll;
 805                         int j;
 806                         unsigned long p_mask;
 807                         struct sline *sl = &sline[lno++];
 808                         ll = (sl->flag & no_pre_delete) ? NULL : sl->lost;
 809                         while (ll) {
 810                                 printf("%s%s", line_prefix, c_old);
 811                                 for (j = 0; j < num_parent; j++) {
 812                                         if (ll->parent_map & (1UL<<j))
 813                                                 putchar('-');
 814                                         else
 815                                                 putchar(' ');
 816                                 }
 817                                 show_line_to_eol(ll->line, -1, c_reset);
 818                                 ll = ll->next;
 819                         }
 820                         if (cnt < lno)
 821                                 break;
 822                         p_mask = 1;
 823                         fputs(line_prefix, stdout);
 824                         if (!(sl->flag & (mark-1))) {
 825                                 /*
 826                                  * This sline was here to hang the
 827                                  * lost lines in front of it.
 828                                  */
 829                                 if (!context)
 830                                         continue;
 831                                 fputs(c_context, stdout);
 832                         }
 833                         else
 834                                 fputs(c_new, stdout);
 835                         for (j = 0; j < num_parent; j++) {
 836                                 if (p_mask & sl->flag)
 837                                         putchar('+');
 838                                 else
 839                                         putchar(' ');
 840                                 p_mask <<= 1;
 841                         }
 842                         show_line_to_eol(sl->bol, sl->len, c_reset);
 843                 }
 844         }
 845 }
 846
 847 static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 848                                int i, int j)
 849 {
 850         /* We have already examined parent j and we know parent i
 851          * and parent j are the same, so reuse the combined result
 852          * of parent j for parent i.
 853          */
 854         unsigned long lno, imask, jmask;
 855         imask = (1UL<<i);
 856         jmask = (1UL<<j);
 857
 858         for (lno = 0; lno <= cnt; lno++) {
 859                 struct lline *ll = sline->lost;
 860                 sline->p_lno[i] = sline->p_lno[j];
 861                 while (ll) {
 862                         if (ll->parent_map & jmask)
 863                                 ll->parent_map |= imask;
 864                         ll = ll->next;
 865                 }
 866                 if (sline->flag & jmask)
 867                         sline->flag |= imask;
 868                 sline++;
 869         }
 870         /* the overall size of the file (sline[cnt]) */
 871         sline->p_lno[i] = sline->p_lno[j];
 872 }
 873
 874 static void dump_quoted_path(const char *head,
 875                              const char *prefix,
 876                              const char *path,
 877                              const char *line_prefix,
 878                              const char *c_meta, const char *c_reset)
 879 {
 880         static struct strbuf buf = STRBUF_INIT;
 881
 882         strbuf_reset(&buf);
 883         strbuf_addstr(&buf, line_prefix);
 884         strbuf_addstr(&buf, c_meta);
 885         strbuf_addstr(&buf, head);
 886         quote_two_c_style(&buf, prefix, path, 0);
 887         strbuf_addstr(&buf, c_reset);
 888         puts(buf.buf);
 889 }
 890
 891 static void show_combined_header(struct combine_diff_path *elem,
 892                                  int num_parent,
 893                                  int dense,
 894                                  struct rev_info *rev,
 895                                  const char *line_prefix,
 896                                  int mode_differs,
 897                                  int show_file_header)
 898 {
 899         struct diff_options *opt = &rev->diffopt;
 900         int abbrev = DIFF_OPT_TST(opt, FULL_INDEX) ? GIT_SHA1_HEXSZ : DEFAULT_ABBREV;
 901         const char *a_prefix = opt->a_prefix ? opt->a_prefix : "a/";
 902         const char *b_prefix = opt->b_prefix ? opt->b_prefix : "b/";
 903         const char *c_meta = diff_get_color_opt(opt, DIFF_METAINFO);
 904         const char *c_reset = diff_get_color_opt(opt, DIFF_RESET);
 905         const char *abb;
 906         int added = 0;
 907         int deleted = 0;
 908         int i;
 909
 910         if (rev->loginfo && !rev->no_commit_id)
 911                 show_log(rev);
 912
 913         dump_quoted_path(dense ? "diff --cc " : "diff --combined ",
 914                          "", elem->path, line_prefix, c_meta, c_reset);
 915         printf("%s%sindex ", line_prefix, c_meta);
 916         for (i = 0; i < num_parent; i++) {
 917                 abb = find_unique_abbrev(elem->parent[i].oid.hash,
 918                                          abbrev);
 919                 printf("%s%s", i ? "," : "", abb);
 920         }
 921         abb = find_unique_abbrev(elem->oid.hash, abbrev);
 922         printf("..%s%s\n", abb, c_reset);
 923
 924         if (mode_differs) {
 925                 deleted = !elem->mode;
 926
 927                 /* We say it was added if nobody had it */
 928                 added = !deleted;
 929                 for (i = 0; added && i < num_parent; i++)
 930                         if (elem->parent[i].status !=
 931                             DIFF_STATUS_ADDED)
 932                                 added = 0;
 933                 if (added)
 934                         printf("%s%snew file mode %06o",
 935                                line_prefix, c_meta, elem->mode);
 936                 else {
 937                         if (deleted)
 938                                 printf("%s%sdeleted file ",
 939                                        line_prefix, c_meta);
 940                         printf("mode ");
 941                         for (i = 0; i < num_parent; i++) {
 942                                 printf("%s%06o", i ? "," : "",
 943                                        elem->parent[i].mode);
 944                         }
 945                         if (elem->mode)
 946                                 printf("..%06o", elem->mode);
 947                 }
 948                 printf("%s\n", c_reset);
 949         }
 950
 951         if (!show_file_header)
 952                 return;
 953
 954         if (added)
 955                 dump_quoted_path("--- ", "", "/dev/null",
 956                                  line_prefix, c_meta, c_reset);
 957         else
 958                 dump_quoted_path("--- ", a_prefix, elem->path,
 959                                  line_prefix, c_meta, c_reset);
 960         if (deleted)
 961                 dump_quoted_path("+++ ", "", "/dev/null",
 962                                  line_prefix, c_meta, c_reset);
 963         else
 964                 dump_quoted_path("+++ ", b_prefix, elem->path,
 965                                  line_prefix, c_meta, c_reset);
 966 }
 967
 968 static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 969                             int dense, int working_tree_file,
 970                             struct rev_info *rev)
 971 {
 972         struct diff_options *opt = &rev->diffopt;
 973         unsigned long result_size, cnt, lno;
 974         int result_deleted = 0;
 975         char *result, *cp;
 976         struct sline *sline; /* survived lines */
 977         int mode_differs = 0;
 978         int i, show_hunks;
 979         mmfile_t result_file;
 980         struct userdiff_driver *userdiff;
 981         struct userdiff_driver *textconv = NULL;
 982         int is_binary;
 983         const char *line_prefix = diff_line_prefix(opt);
 984
 985         context = opt->context;
 986         userdiff = userdiff_find_by_path(elem->path);
 987         if (!userdiff)
 988                 userdiff = userdiff_find_by_name("default");
 989         if (DIFF_OPT_TST(opt, ALLOW_TEXTCONV))
 990                 textconv = userdiff_get_textconv(userdiff);
 991
 992         /* Read the result of merge first */
 993         if (!working_tree_file)
 994                 result = grab_blob(&elem->oid, elem->mode, &result_size,
 995                                    textconv, elem->path);
 996         else {
 997                 /* Used by diff-tree to read from the working tree */
 998                 struct stat st;
 999                 int fd = -1;
1000
1001                 if (lstat(elem->path, &st) < 0)
1002                         goto deleted_file;
1003
1004                 if (S_ISLNK(st.st_mode)) {
1005                         struct strbuf buf = STRBUF_INIT;
1006
1007                         if (strbuf_readlink(&buf, elem->path, st.st_size) < 0) {
1008                                 error_errno("readlink(%s)", elem->path);
1009                                 return;
1010                         }
1011                         result_size = buf.len;
1012                         result = strbuf_detach(&buf, NULL);
1013                         elem->mode = canon_mode(st.st_mode);
1014                 } else if (S_ISDIR(st.st_mode)) {
1015                         struct object_id oid;
1016                         if (resolve_gitlink_ref(elem->path, "HEAD", oid.hash) < 0)
1017                                 result = grab_blob(&elem->oid, elem->mode,
1018                                                    &result_size, NULL, NULL);
1019                         else
1020                                 result = grab_blob(&oid, elem->mode,
1021                                                    &result_size, NULL, NULL);
1022                 } else if (textconv) {
1023                         struct diff_filespec *df = alloc_filespec(elem->path);
1024                         fill_filespec(df, null_sha1, 0, st.st_mode);
1025                         result_size = fill_textconv(textconv, df, &result);
1026                         free_filespec(df);
1027                 } else if (0 <= (fd = open(elem->path, O_RDONLY))) {
1028                         size_t len = xsize_t(st.st_size);
1029                         ssize_t done;
1030                         int is_file, i;
1031
1032                         elem->mode = canon_mode(st.st_mode);
1033                         /* if symlinks don't work, assume symlink if all parents
1034                          * are symlinks
1035                          */
1036                         is_file = has_symlinks;
1037                         for (i = 0; !is_file && i < num_parent; i++)
1038                                 is_file = !S_ISLNK(elem->parent[i].mode);
1039                         if (!is_file)
1040                                 elem->mode = canon_mode(S_IFLNK);
1041
1042                         result_size = len;
1043                         result = xmallocz(len);
1044
1045                         done = read_in_full(fd, result, len);
1046                         if (done < 0)
1047                                 die_errno("read error '%s'", elem->path);
1048                         else if (done < len)
1049                                 die("early EOF '%s'", elem->path);
1050
1051                         /* If not a fake symlink, apply filters, e.g. autocrlf */
1052                         if (is_file) {
1053                                 struct strbuf buf = STRBUF_INIT;
1054
1055                                 if (convert_to_git(elem->path, result, len, &buf, safe_crlf)) {
1056                                         free(result);
1057                                         result = strbuf_detach(&buf, &len);
1058                                         result_size = len;
1059                                 }
1060                         }
1061                 }
1062                 else {
1063                 deleted_file:
1064                         result_deleted = 1;
1065                         result_size = 0;
1066                         elem->mode = 0;
1067                         result = xcalloc(1, 1);
1068                 }
1069
1070                 if (0 <= fd)
1071                         close(fd);
1072         }
1073
1074         for (i = 0; i < num_parent; i++) {
1075                 if (elem->parent[i].mode != elem->mode) {
1076                         mode_differs = 1;
1077                         break;
1078                 }
1079         }
1080
1081         if (textconv)
1082                 is_binary = 0;
1083         else if (userdiff->binary != -1)
1084                 is_binary = userdiff->binary;
1085         else {
1086                 is_binary = buffer_is_binary(result, result_size);
1087                 for (i = 0; !is_binary && i < num_parent; i++) {
1088                         char *buf;
1089                         unsigned long size;
1090                         buf = grab_blob(&elem->parent[i].oid,
1091                                         elem->parent[i].mode,
1092                                         &size, NULL, NULL);
1093                         if (buffer_is_binary(buf, size))
1094                                 is_binary = 1;
1095                         free(buf);
1096                 }
1097         }
1098         if (is_binary) {
1099                 show_combined_header(elem, num_parent, dense, rev,
1100                                      line_prefix, mode_differs, 0);
1101                 printf("Binary files differ\n");
1102                 free(result);
1103                 return;
1104         }
1105
1106         for (cnt = 0, cp = result; cp < result + result_size; cp++) {
1107                 if (*cp == '\n')
1108                         cnt++;
1109         }
1110         if (result_size && result[result_size-1] != '\n')
1111                 cnt++; /* incomplete line */
1112
1113         sline = xcalloc(st_add(cnt, 2), sizeof(*sline));
1114         sline[0].bol = result;
1115         for (lno = 0, cp = result; cp < result + result_size; cp++) {
1116                 if (*cp == '\n') {
1117                         sline[lno].len = cp - sline[lno].bol;
1118                         lno++;
1119                         if (lno < cnt)
1120                                 sline[lno].bol = cp + 1;
1121                 }
1122         }
1123         if (result_size && result[result_size-1] != '\n')
1124                 sline[cnt-1].len = result_size - (sline[cnt-1].bol - result);
1125
1126         result_file.ptr = result;
1127         result_file.size = result_size;
1128
1129         /* Even p_lno[cnt+1] is valid -- that is for the end line number
1130          * for deletion hunk at the end.
1131          */
1132         sline[0].p_lno = xcalloc(st_mult(st_add(cnt, 2), num_parent), sizeof(unsigned long));
1133         for (lno = 0; lno <= cnt; lno++)
1134                 sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
1135
1136         for (i = 0; i < num_parent; i++) {
1137                 int j;
1138                 for (j = 0; j < i; j++) {
1139                         if (!oidcmp(&elem->parent[i].oid,
1140                                      &elem->parent[j].oid)) {
1141                                 reuse_combine_diff(sline, cnt, i, j);
1142                                 break;
1143                         }
1144                 }
1145                 if (i <= j)
1146                         combine_diff(&elem->parent[i].oid,
1147                                      elem->parent[i].mode,
1148                                      &result_file, sline,
1149                                      cnt, i, num_parent, result_deleted,
1150                                      textconv, elem->path, opt->xdl_opts);
1151         }
1152
1153         show_hunks = make_hunks(sline, cnt, num_parent, dense);
1154
1155         if (show_hunks || mode_differs || working_tree_file) {
1156                 show_combined_header(elem, num_parent, dense, rev,
1157                                      line_prefix, mode_differs, 1);
1158                 dump_sline(sline, line_prefix, cnt, num_parent,
1159                            opt->use_color, result_deleted);
1160         }
1161         free(result);
1162
1163         for (lno = 0; lno < cnt; lno++) {
1164                 if (sline[lno].lost) {
1165                         struct lline *ll = sline[lno].lost;
1166                         while (ll) {
1167                                 struct lline *tmp = ll;
1168                                 ll = ll->next;
1169                                 free(tmp);
1170                         }
1171                 }
1172         }
1173         free(sline[0].p_lno);
1174         free(sline);
1175 }
1176
1177 static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct rev_info *rev)
1178 {
1179         struct diff_options *opt = &rev->diffopt;
1180         int line_termination, inter_name_termination, i;
1181         const char *line_prefix = diff_line_prefix(opt);
1182
1183         line_termination = opt->line_termination;
1184         inter_name_termination = '\t';
1185         if (!line_termination)
1186                 inter_name_termination = 0;
1187
1188         if (rev->loginfo && !rev->no_commit_id)
1189                 show_log(rev);
1190
1191
1192         if (opt->output_format & DIFF_FORMAT_RAW) {
1193                 printf("%s", line_prefix);
1194
1195                 /* As many colons as there are parents */
1196                 for (i = 0; i < num_parent; i++)
1197                         putchar(':');
1198
1199                 /* Show the modes */
1200                 for (i = 0; i < num_parent; i++)
1201                         printf("%06o ", p->parent[i].mode);
1202                 printf("%06o", p->mode);
1203
1204                 /* Show sha1's */
1205                 for (i = 0; i < num_parent; i++)
1206                         printf(" %s", diff_unique_abbrev(p->parent[i].oid.hash,
1207                                                          opt->abbrev));
1208                 printf(" %s ", diff_unique_abbrev(p->oid.hash, opt->abbrev));
1209         }
1210
1211         if (opt->output_format & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS)) {
1212                 for (i = 0; i < num_parent; i++)
1213                         putchar(p->parent[i].status);
1214                 putchar(inter_name_termination);
1215         }
1216
1217         write_name_quoted(p->path, stdout, line_termination);
1218 }
1219
1220 /*
1221  * The result (p->elem) is from the working tree and their
1222  * parents are typically from multiple stages during a merge
1223  * (i.e. diff-files) or the state in HEAD and in the index
1224  * (i.e. diff-index).
1225  */
1226 void show_combined_diff(struct combine_diff_path *p,
1227                        int num_parent,
1228                        int dense,
1229                        struct rev_info *rev)
1230 {
1231         struct diff_options *opt = &rev->diffopt;
1232
1233         if (opt->output_format & (DIFF_FORMAT_RAW |
1234                                   DIFF_FORMAT_NAME |
1235                                   DIFF_FORMAT_NAME_STATUS))
1236                 show_raw_diff(p, num_parent, rev);
1237         else if (opt->output_format & DIFF_FORMAT_PATCH)
1238                 show_patch_diff(p, num_parent, dense, 1, rev);
1239 }
1240
1241 static void free_combined_pair(struct diff_filepair *pair)
1242 {
1243         free(pair->two);
1244         free(pair);
1245 }
1246
1247 /*
1248  * A combine_diff_path expresses N parents on the LHS against 1 merge
1249  * result. Synthesize a diff_filepair that has N entries on the "one"
1250  * side and 1 entry on the "two" side.
1251  *
1252  * In the future, we might want to add more data to combine_diff_path
1253  * so that we can fill fields we are ignoring (most notably, size) here,
1254  * but currently nobody uses it, so this should suffice for now.
1255  */
1256 static struct diff_filepair *combined_pair(struct combine_diff_path *p,
1257                                            int num_parent)
1258 {
1259         int i;
1260         struct diff_filepair *pair;
1261         struct diff_filespec *pool;
1262
1263         pair = xmalloc(sizeof(*pair));
1264         pool = xcalloc(st_add(num_parent, 1), sizeof(struct diff_filespec));
1265         pair->one = pool + 1;
1266         pair->two = pool;
1267
1268         for (i = 0; i < num_parent; i++) {
1269                 pair->one[i].path = p->path;
1270                 pair->one[i].mode = p->parent[i].mode;
1271                 oidcpy(&pair->one[i].oid, &p->parent[i].oid);
1272                 pair->one[i].oid_valid = !is_null_oid(&p->parent[i].oid);
1273                 pair->one[i].has_more_entries = 1;
1274         }
1275         pair->one[num_parent - 1].has_more_entries = 0;
1276
1277         pair->two->path = p->path;
1278         pair->two->mode = p->mode;
1279         oidcpy(&pair->two->oid, &p->oid);
1280         pair->two->oid_valid = !is_null_oid(&p->oid);
1281         return pair;
1282 }
1283
1284 static void handle_combined_callback(struct diff_options *opt,
1285                                      struct combine_diff_path *paths,
1286                                      int num_parent,
1287                                      int num_paths)
1288 {
1289         struct combine_diff_path *p;
1290         struct diff_queue_struct q;
1291         int i;
1292
1293         q.queue = xcalloc(num_paths, sizeof(struct diff_filepair *));
1294         q.alloc = num_paths;
1295         q.nr = num_paths;
1296         for (i = 0, p = paths; p; p = p->next)
1297                 q.queue[i++] = combined_pair(p, num_parent);
1298         opt->format_callback(&q, opt, opt->format_callback_data);
1299         for (i = 0; i < num_paths; i++)
1300                 free_combined_pair(q.queue[i]);
1301         free(q.queue);
1302 }
1303
1304 static const char *path_path(void *obj)
1305 {
1306         struct combine_diff_path *path = (struct combine_diff_path *)obj;
1307
1308         return path->path;
1309 }
1310
1311
1312 /* find set of paths that every parent touches */
1313 static struct combine_diff_path *find_paths_generic(const unsigned char *sha1,
1314         const struct sha1_array *parents, struct diff_options *opt)
1315 {
1316         struct combine_diff_path *paths = NULL;
1317         int i, num_parent = parents->nr;
1318
1319         int output_format = opt->output_format;
1320         const char *orderfile = opt->orderfile;
1321
1322         opt->output_format = DIFF_FORMAT_NO_OUTPUT;
1323         /* tell diff_tree to emit paths in sorted (=tree) order */
1324         opt->orderfile = NULL;
1325
1326         /* D(A,P1...Pn) = D(A,P1) ^ ... ^ D(A,Pn)  (wrt paths) */
1327         for (i = 0; i < num_parent; i++) {
1328                 /*
1329                  * show stat against the first parent even when doing
1330                  * combined diff.
1331                  */
1332                 int stat_opt = (output_format &
1333                                 (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT));
1334                 if (i == 0 && stat_opt)
1335                         opt->output_format = stat_opt;
1336                 else
1337                         opt->output_format = DIFF_FORMAT_NO_OUTPUT;
1338                 diff_tree_sha1(parents->sha1[i], sha1, "", opt);
1339                 diffcore_std(opt);
1340                 paths = intersect_paths(paths, i, num_parent);
1341
1342                 /* if showing diff, show it in requested order */
1343                 if (opt->output_format != DIFF_FORMAT_NO_OUTPUT &&
1344                     orderfile) {
1345                         diffcore_order(orderfile);
1346                 }
1347
1348                 diff_flush(opt);
1349         }
1350
1351         opt->output_format = output_format;
1352         opt->orderfile = orderfile;
1353         return paths;
1354 }
1355
1356
1357 /*
1358  * find set of paths that everybody touches, assuming diff is run without
1359  * rename/copy detection, etc, comparing all trees simultaneously (= faster).
1360  */
1361 static struct combine_diff_path *find_paths_multitree(
1362         const unsigned char *sha1, const struct sha1_array *parents,
1363         struct diff_options *opt)
1364 {
1365         int i, nparent = parents->nr;
1366         const unsigned char **parents_sha1;
1367         struct combine_diff_path paths_head;
1368         struct strbuf base;
1369
1370         ALLOC_ARRAY(parents_sha1, nparent);
1371         for (i = 0; i < nparent; i++)
1372                 parents_sha1[i] = parents->sha1[i];
1373
1374         /* fake list head, so worker can assume it is non-NULL */
1375         paths_head.next = NULL;
1376
1377         strbuf_init(&base, PATH_MAX);
1378         diff_tree_paths(&paths_head, sha1, parents_sha1, nparent, &base, opt);
1379
1380         strbuf_release(&base);
1381         free(parents_sha1);
1382         return paths_head.next;
1383 }
1384
1385
1386 void diff_tree_combined(const unsigned char *sha1,
1387                         const struct sha1_array *parents,
1388                         int dense,
1389                         struct rev_info *rev)
1390 {
1391         struct diff_options *opt = &rev->diffopt;
1392         struct diff_options diffopts;
1393         struct combine_diff_path *p, *paths;
1394         int i, num_paths, needsep, show_log_first, num_parent = parents->nr;
1395         int need_generic_pathscan;
1396
1397         /* nothing to do, if no parents */
1398         if (!num_parent)
1399                 return;
1400
1401         show_log_first = !!rev->loginfo && !rev->no_commit_id;
1402         needsep = 0;
1403         if (show_log_first) {
1404                 show_log(rev);
1405
1406                 if (rev->verbose_header && opt->output_format &&
1407                     opt->output_format != DIFF_FORMAT_NO_OUTPUT &&
1408                     !commit_format_is_empty(rev->commit_format))
1409                         printf("%s%c", diff_line_prefix(opt),
1410                                opt->line_termination);
1411         }
1412
1413         diffopts = *opt;
1414         copy_pathspec(&diffopts.pathspec, &opt->pathspec);
1415         DIFF_OPT_SET(&diffopts, RECURSIVE);
1416         DIFF_OPT_CLR(&diffopts, ALLOW_EXTERNAL);
1417
1418         /* find set of paths that everybody touches
1419          *
1420          * NOTE
1421          *
1422          * Diffcore transformations are bound to diff_filespec and logic
1423          * comparing two entries - i.e. they do not apply directly to combine
1424          * diff.
1425          *
1426          * If some of such transformations is requested - we launch generic
1427          * path scanning, which works significantly slower compared to
1428          * simultaneous all-trees-in-one-go scan in find_paths_multitree().
1429          *
1430          * TODO some of the filters could be ported to work on
1431          * combine_diff_paths - i.e. all functionality that skips paths, so in
1432          * theory, we could end up having only multitree path scanning.
1433          *
1434          * NOTE please keep this semantically in sync with diffcore_std()
1435          */
1436         need_generic_pathscan = opt->skip_stat_unmatch  ||
1437                         DIFF_OPT_TST(opt, FOLLOW_RENAMES)       ||
1438                         opt->break_opt != -1    ||
1439                         opt->detect_rename      ||
1440                         opt->pickaxe            ||
1441                         opt->filter;
1442
1443
1444         if (need_generic_pathscan) {
1445                 /*
1446                  * NOTE generic case also handles --stat, as it computes
1447                  * diff(sha1,parent_i) for all i to do the job, specifically
1448                  * for parent0.
1449                  */
1450                 paths = find_paths_generic(sha1, parents, &diffopts);
1451         }
1452         else {
1453                 int stat_opt;
1454                 paths = find_paths_multitree(sha1, parents, &diffopts);
1455
1456                 /*
1457                  * show stat against the first parent even
1458                  * when doing combined diff.
1459                  */
1460                 stat_opt = (opt->output_format &
1461                                 (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT));
1462                 if (stat_opt) {
1463                         diffopts.output_format = stat_opt;
1464
1465                         diff_tree_sha1(parents->sha1[0], sha1, "", &diffopts);
1466                         diffcore_std(&diffopts);
1467                         if (opt->orderfile)
1468                                 diffcore_order(opt->orderfile);
1469                         diff_flush(&diffopts);
1470                 }
1471         }
1472
1473         /* find out number of surviving paths */
1474         for (num_paths = 0, p = paths; p; p = p->next)
1475                 num_paths++;
1476
1477         /* order paths according to diffcore_order */
1478         if (opt->orderfile && num_paths) {
1479                 struct obj_order *o;
1480
1481                 ALLOC_ARRAY(o, num_paths);
1482                 for (i = 0, p = paths; p; p = p->next, i++)
1483                         o[i].obj = p;
1484                 order_objects(opt->orderfile, path_path, o, num_paths);
1485                 for (i = 0; i < num_paths - 1; i++) {
1486                         p = o[i].obj;
1487                         p->next = o[i+1].obj;
1488                 }
1489
1490                 p = o[num_paths-1].obj;
1491                 p->next = NULL;
1492                 paths = o[0].obj;
1493                 free(o);
1494         }
1495
1496
1497         if (num_paths) {
1498                 if (opt->output_format & (DIFF_FORMAT_RAW |
1499                                           DIFF_FORMAT_NAME |
1500                                           DIFF_FORMAT_NAME_STATUS)) {
1501                         for (p = paths; p; p = p->next)
1502                                 show_raw_diff(p, num_parent, rev);
1503                         needsep = 1;
1504                 }
1505                 else if (opt->output_format &
1506                          (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT))
1507                         needsep = 1;
1508                 else if (opt->output_format & DIFF_FORMAT_CALLBACK)
1509                         handle_combined_callback(opt, paths, num_parent, num_paths);
1510
1511                 if (opt->output_format & DIFF_FORMAT_PATCH) {
1512                         if (needsep)
1513                                 printf("%s%c", diff_line_prefix(opt),
1514                                        opt->line_termination);
1515                         for (p = paths; p; p = p->next)
1516                                 show_patch_diff(p, num_parent, dense,
1517                                                 0, rev);
1518                 }
1519         }
1520
1521         /* Clean things up */
1522         while (paths) {
1523                 struct combine_diff_path *tmp = paths;
1524                 paths = paths->next;
1525                 free(tmp);
1526         }
1527
1528         clear_pathspec(&diffopts.pathspec);
1529 }
1530
1531 void diff_tree_combined_merge(const struct commit *commit, int dense,
1532                               struct rev_info *rev)
1533 {
1534         struct commit_list *parent = get_saved_parents(rev, commit);
1535         struct sha1_array parents = SHA1_ARRAY_INIT;
1536
1537         while (parent) {
1538                 sha1_array_append(&parents, parent->item->object.oid.hash);
1539                 parent = parent->next;
1540         }
1541         diff_tree_combined(commit->object.oid.hash, &parents, dense, rev);
1542         sha1_array_clear(&parents);
1543 }