combine-diff.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "diff.h"
   4 #include "diffcore.h"
   5 #include "quote.h"
   6
   7 static int uninteresting(struct diff_filepair *p)
   8 {
   9         if (diff_unmodified_pair(p))
  10                 return 1;
  11         return 0;
  12 }
  13
  14 static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr, int n, int num_parent)
  15 {
  16         struct diff_queue_struct *q = &diff_queued_diff;
  17         struct combine_diff_path *p;
  18         int i;
  19
  20         if (!n) {
  21                 struct combine_diff_path *list = NULL, **tail = &list;
  22                 for (i = 0; i < q->nr; i++) {
  23                         int len;
  24                         const char *path;
  25                         if (uninteresting(q->queue[i]))
  26                                 continue;
  27                         path = q->queue[i]->two->path;
  28                         len = strlen(path);
  29                         p = xmalloc(combine_diff_path_size(num_parent, len));
  30                         p->path = (char*) &(p->parent[num_parent]);
  31                         memcpy(p->path, path, len);
  32                         p->path[len] = 0;
  33                         p->len = len;
  34                         p->next = NULL;
  35                         memset(p->parent, 0,
  36                                sizeof(p->parent[0]) * num_parent);
  37
  38                         memcpy(p->sha1, q->queue[i]->two->sha1, 20);
  39                         p->mode = q->queue[i]->two->mode;
  40                         memcpy(p->parent[n].sha1, q->queue[i]->one->sha1, 20);
  41                         p->parent[n].mode = q->queue[i]->one->mode;
  42                         *tail = p;
  43                         tail = &p->next;
  44                 }
  45                 return list;
  46         }
  47
  48         for (p = curr; p; p = p->next) {
  49                 int found = 0;
  50                 if (!p->len)
  51                         continue;
  52                 for (i = 0; i < q->nr; i++) {
  53                         const char *path;
  54                         int len;
  55
  56                         if (uninteresting(q->queue[i]))
  57                                 continue;
  58                         path = q->queue[i]->two->path;
  59                         len = strlen(path);
  60                         if (len == p->len && !memcmp(path, p->path, len)) {
  61                                 found = 1;
  62                                 memcpy(p->parent[n].sha1,
  63                                        q->queue[i]->one->sha1, 20);
  64                                 p->parent[n].mode = q->queue[i]->one->mode;
  65                                 break;
  66                         }
  67                 }
  68                 if (!found)
  69                         p->len = 0;
  70         }
  71         return curr;
  72 }
  73
  74 /* Lines lost from parent */
  75 struct lline {
  76         struct lline *next;
  77         int len;
  78         unsigned long parent_map;
  79         char line[FLEX_ARRAY];
  80 };
  81
  82 /* Lines surviving in the merge result */
  83 struct sline {
  84         struct lline *lost_head, **lost_tail;
  85         char *bol;
  86         int len;
  87         /* bit 0 up to (N-1) are on if the parent has this line (i.e.
  88          * we did not change it).
  89          * bit N is used for "interesting" lines, including context.
  90          */
  91         unsigned long flag;
  92         unsigned long *p_lno;
  93 };
  94
  95 static char *grab_blob(const unsigned char *sha1, unsigned long *size)
  96 {
  97         char *blob;
  98         char type[20];
  99         if (!memcmp(sha1, null_sha1, 20)) {
 100                 /* deleted blob */
 101                 *size = 0;
 102                 return xcalloc(1, 1);
 103         }
 104         blob = read_sha1_file(sha1, type, size);
 105         if (strcmp(type, "blob"))
 106                 die("object '%s' is not a blob!", sha1_to_hex(sha1));
 107         return blob;
 108 }
 109
 110 #define TMPPATHLEN 50
 111 #define MAXLINELEN 10240
 112
 113 static void write_to_temp_file(char *tmpfile, void *blob, unsigned long size)
 114 {
 115         int fd = git_mkstemp(tmpfile, TMPPATHLEN, ".diff_XXXXXX");
 116         if (fd < 0)
 117                 die("unable to create temp-file");
 118         if (write(fd, blob, size) != size)
 119                 die("unable to write temp-file");
 120         close(fd);
 121 }
 122
 123 static void write_temp_blob(char *tmpfile, const unsigned char *sha1)
 124 {
 125         unsigned long size;
 126         void *blob;
 127         blob = grab_blob(sha1, &size);
 128         write_to_temp_file(tmpfile, blob, size);
 129         free(blob);
 130 }
 131
 132 static int parse_num(char **cp_p, unsigned int *num_p)
 133 {
 134         char *cp = *cp_p;
 135         unsigned int num = 0;
 136         int read_some;
 137
 138         while ('0' <= *cp && *cp <= '9')
 139                 num = num * 10 + *cp++ - '0';
 140         if (!(read_some = cp - *cp_p))
 141                 return -1;
 142         *cp_p = cp;
 143         *num_p = num;
 144         return 0;
 145 }
 146
 147 static int parse_hunk_header(char *line, int len,
 148                              unsigned int *ob, unsigned int *on,
 149                              unsigned int *nb, unsigned int *nn)
 150 {
 151         char *cp;
 152         cp = line + 4;
 153         if (parse_num(&cp, ob)) {
 154         bad_line:
 155                 return error("malformed diff output: %s", line);
 156         }
 157         if (*cp == ',') {
 158                 cp++;
 159                 if (parse_num(&cp, on))
 160                         goto bad_line;
 161         }
 162         else
 163                 *on = 1;
 164         if (*cp++ != ' ' || *cp++ != '+')
 165                 goto bad_line;
 166         if (parse_num(&cp, nb))
 167                 goto bad_line;
 168         if (*cp == ',') {
 169                 cp++;
 170                 if (parse_num(&cp, nn))
 171                         goto bad_line;
 172         }
 173         else
 174                 *nn = 1;
 175         return -!!memcmp(cp, " @@", 3);
 176 }
 177
 178 static void append_lost(struct sline *sline, int n, const char *line)
 179 {
 180         struct lline *lline;
 181         int len = strlen(line);
 182         unsigned long this_mask = (1UL<<n);
 183         if (line[len-1] == '\n')
 184                 len--;
 185
 186         /* Check to see if we can squash things */
 187         if (sline->lost_head) {
 188                 struct lline *last_one = NULL;
 189                 /* We cannot squash it with earlier one */
 190                 for (lline = sline->lost_head;
 191                      lline;
 192                      lline = lline->next)
 193                         if (lline->parent_map & this_mask)
 194                                 last_one = lline;
 195                 lline = last_one ? last_one->next : sline->lost_head;
 196                 while (lline) {
 197                         if (lline->len == len &&
 198                             !memcmp(lline->line, line, len)) {
 199                                 lline->parent_map |= this_mask;
 200                                 return;
 201                         }
 202                         lline = lline->next;
 203                 }
 204         }
 205
 206         lline = xmalloc(sizeof(*lline) + len + 1);
 207         lline->len = len;
 208         lline->next = NULL;
 209         lline->parent_map = this_mask;
 210         memcpy(lline->line, line, len);
 211         lline->line[len] = 0;
 212         *sline->lost_tail = lline;
 213         sline->lost_tail = &lline->next;
 214 }
 215
 216 static void combine_diff(const unsigned char *parent, const char *ourtmp,
 217                          struct sline *sline, int cnt, int n, int num_parent)
 218 {
 219         FILE *in;
 220         char parent_tmp[TMPPATHLEN];
 221         char cmd[TMPPATHLEN * 2 + 1024];
 222         char line[MAXLINELEN];
 223         unsigned int lno, ob, on, nb, nn, p_lno;
 224         unsigned long nmask = (1UL << n);
 225         struct sline *lost_bucket = NULL;
 226
 227         if (!cnt)
 228                 return; /* result deleted */
 229
 230         write_temp_blob(parent_tmp, parent);
 231         sprintf(cmd, "diff --unified=0 -La/x -Lb/x '%s' '%s'",
 232                 parent_tmp, ourtmp);
 233         in = popen(cmd, "r");
 234         if (!in)
 235                 die("cannot spawn %s", cmd);
 236
 237         lno = 1;
 238         while (fgets(line, sizeof(line), in) != NULL) {
 239                 int len = strlen(line);
 240                 if (5 < len && !memcmp("@@ -", line, 4)) {
 241                         if (parse_hunk_header(line, len,
 242                                               &ob, &on, &nb, &nn))
 243                                 break;
 244                         lno = nb;
 245                         if (!nb)
 246                                 /* @@ -1,2 +0,0 @@ to remove the
 247                                  * first two lines...
 248                                  */
 249                                 nb = 1;
 250                         if (nn == 0)
 251                                 /* @@ -X,Y +N,0 @@ removed Y lines
 252                                  * that would have come *after* line N
 253                                  * in the result.  Our lost buckets hang
 254                                  * to the line after the removed lines,
 255                                  */
 256                                 lost_bucket = &sline[nb];
 257                         else
 258                                 lost_bucket = &sline[nb-1];
 259                         if (!sline[nb-1].p_lno)
 260                                 sline[nb-1].p_lno =
 261                                         xcalloc(num_parent,
 262                                                 sizeof(unsigned long));
 263                         sline[nb-1].p_lno[n] = ob;
 264                         continue;
 265                 }
 266                 if (!lost_bucket)
 267                         continue; /* not in any hunk yet */
 268                 switch (line[0]) {
 269                 case '-':
 270                         append_lost(lost_bucket, n, line+1);
 271                         break;
 272                 case '+':
 273                         sline[lno-1].flag |= nmask;
 274                         lno++;
 275                         break;
 276                 }
 277         }
 278         fclose(in);
 279         unlink(parent_tmp);
 280
 281         /* Assign line numbers for this parent.
 282          *
 283          * sline[lno].p_lno[n] records the first line number
 284          * (counting from 1) for parent N if the final hunk display
 285          * started by showing sline[lno] (possibly showing the lost
 286          * lines attached to it first).
 287          */
 288         for (lno = 0,  p_lno = 1; lno < cnt; lno++) {
 289                 struct lline *ll;
 290                 sline[lno].p_lno[n] = p_lno;
 291
 292                 /* How many lines would this sline advance the p_lno? */
 293                 ll = sline[lno].lost_head;
 294                 while (ll) {
 295                         if (ll->parent_map & nmask)
 296                                 p_lno++; /* '-' means parent had it */
 297                         ll = ll->next;
 298                 }
 299                 if (!(sline[lno].flag & nmask))
 300                         p_lno++; /* no '+' means parent had it */
 301         }
 302         sline[lno].p_lno[n] = p_lno; /* trailer */
 303 }
 304
 305 static unsigned long context = 3;
 306 static char combine_marker = '@';
 307
 308 static int interesting(struct sline *sline, unsigned long all_mask)
 309 {
 310         /* If some parents lost lines here, or if we have added to
 311          * some parent, it is interesting.
 312          */
 313         return ((sline->flag & all_mask) || sline->lost_head);
 314 }
 315
 316 static unsigned long adjust_hunk_tail(struct sline *sline,
 317                                       unsigned long all_mask,
 318                                       unsigned long hunk_begin,
 319                                       unsigned long i)
 320 {
 321         /* i points at the first uninteresting line.  If the last line
 322          * of the hunk was interesting only because it has some
 323          * deletion, then it is not all that interesting for the
 324          * purpose of giving trailing context lines.  This is because
 325          * we output '-' line and then unmodified sline[i-1] itself in
 326          * that case which gives us one extra context line.
 327          */
 328         if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
 329                 i--;
 330         return i;
 331 }
 332
 333 static unsigned long find_next(struct sline *sline,
 334                                unsigned long mark,
 335                                unsigned long i,
 336                                unsigned long cnt,
 337                                int uninteresting)
 338 {
 339         /* We have examined up to i-1 and are about to look at i.
 340          * Find next interesting or uninteresting line.  Here,
 341          * "interesting" does not mean interesting(), but marked by
 342          * the give_context() function below (i.e. it includes context
 343          * lines that are not interesting to interesting() function
 344          * that are surrounded by interesting() ones.
 345          */
 346         while (i < cnt)
 347                 if (uninteresting
 348                     ? !(sline[i].flag & mark)
 349                     : (sline[i].flag & mark))
 350                         return i;
 351                 else
 352                         i++;
 353         return cnt;
 354 }
 355
 356 static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
 357 {
 358         unsigned long all_mask = (1UL<<num_parent) - 1;
 359         unsigned long mark = (1UL<<num_parent);
 360         unsigned long i;
 361
 362         /* Two groups of interesting lines may have a short gap of
 363          * unintersting lines.  Connect such groups to give them a
 364          * bit of context.
 365          *
 366          * We first start from what the interesting() function says,
 367          * and mark them with "mark", and paint context lines with the
 368          * mark.  So interesting() would still say false for such context
 369          * lines but they are treated as "interesting" in the end.
 370          */
 371         i = find_next(sline, mark, 0, cnt, 0);
 372         if (cnt <= i)
 373                 return 0;
 374
 375         while (i < cnt) {
 376                 unsigned long j = (context < i) ? (i - context) : 0;
 377                 unsigned long k;
 378
 379                 /* Paint a few lines before the first interesting line. */
 380                 while (j < i)
 381                         sline[j++].flag |= mark;
 382
 383         again:
 384                 /* we know up to i is to be included.  where does the
 385                  * next uninteresting one start?
 386                  */
 387                 j = find_next(sline, mark, i, cnt, 1);
 388                 if (cnt <= j)
 389                         break; /* the rest are all interesting */
 390
 391                 /* lookahead context lines */
 392                 k = find_next(sline, mark, j, cnt, 0);
 393                 j = adjust_hunk_tail(sline, all_mask, i, j);
 394
 395                 if (k < j + context) {
 396                         /* k is interesting and [j,k) are not, but
 397                          * paint them interesting because the gap is small.
 398                          */
 399                         while (j < k)
 400                                 sline[j++].flag |= mark;
 401                         i = k;
 402                         goto again;
 403                 }
 404
 405                 /* j is the first uninteresting line and there is
 406                  * no overlap beyond it within context lines.  Paint
 407                  * the trailing edge a bit.
 408                  */
 409                 i = k;
 410                 k = (j + context < cnt) ? j + context : cnt;
 411                 while (j < k)
 412                         sline[j++].flag |= mark;
 413         }
 414         return 1;
 415 }
 416
 417 static int make_hunks(struct sline *sline, unsigned long cnt,
 418                        int num_parent, int dense)
 419 {
 420         unsigned long all_mask = (1UL<<num_parent) - 1;
 421         unsigned long mark = (1UL<<num_parent);
 422         unsigned long i;
 423         int has_interesting = 0;
 424
 425         for (i = 0; i < cnt; i++) {
 426                 if (interesting(&sline[i], all_mask))
 427                         sline[i].flag |= mark;
 428                 else
 429                         sline[i].flag &= ~mark;
 430         }
 431         if (!dense)
 432                 return give_context(sline, cnt, num_parent);
 433
 434         /* Look at each hunk, and if we have changes from only one
 435          * parent, or the changes are the same from all but one
 436          * parent, mark that uninteresting.
 437          */
 438         i = 0;
 439         while (i < cnt) {
 440                 unsigned long j, hunk_begin, hunk_end;
 441                 unsigned long same_diff;
 442                 while (i < cnt && !(sline[i].flag & mark))
 443                         i++;
 444                 if (cnt <= i)
 445                         break; /* No more interesting hunks */
 446                 hunk_begin = i;
 447                 for (j = i + 1; j < cnt; j++) {
 448                         if (!(sline[j].flag & mark)) {
 449                                 /* Look beyond the end to see if there
 450                                  * is an interesting line after this
 451                                  * hunk within context span.
 452                                  */
 453                                 unsigned long la; /* lookahead */
 454                                 int contin = 0;
 455                                 la = adjust_hunk_tail(sline, all_mask,
 456                                                      hunk_begin, j);
 457                                 la = (la + context < cnt) ?
 458                                         (la + context) : cnt;
 459                                 while (j <= --la) {
 460                                         if (sline[la].flag & mark) {
 461                                                 contin = 1;
 462                                                 break;
 463                                         }
 464                                 }
 465                                 if (!contin)
 466                                         break;
 467                                 j = la;
 468                         }
 469                 }
 470                 hunk_end = j;
 471
 472                 /* [i..hunk_end) are interesting.  Now is it really
 473                  * interesting?  We check if there are only two versions
 474                  * and the result matches one of them.  That is, we look
 475                  * at:
 476                  *   (+) line, which records lines added to which parents;
 477                  *       this line appears in the result.
 478                  *   (-) line, which records from what parents the line
 479                  *       was removed; this line does not appear in the result.
 480                  * then check the set of parents the result has difference
 481                  * from, from all lines.  If there are lines that has
 482                  * different set of parents that the result has differences
 483                  * from, that means we have more than two versions.
 484                  *
 485                  * Even when we have only two versions, if the result does
 486                  * not match any of the parents, the it should be considered
 487                  * interesting.  In such a case, we would have all '+' line.
 488                  * After passing the above "two versions" test, that would
 489                  * appear as "the same set of parents" to be "all parents".
 490                  */
 491                 same_diff = 0;
 492                 has_interesting = 0;
 493                 for (j = i; j < hunk_end && !has_interesting; j++) {
 494                         unsigned long this_diff = sline[j].flag & all_mask;
 495                         struct lline *ll = sline[j].lost_head;
 496                         if (this_diff) {
 497                                 /* This has some changes.  Is it the
 498                                  * same as others?
 499                                  */
 500                                 if (!same_diff)
 501                                         same_diff = this_diff;
 502                                 else if (same_diff != this_diff) {
 503                                         has_interesting = 1;
 504                                         break;
 505                                 }
 506                         }
 507                         while (ll && !has_interesting) {
 508                                 /* Lost this line from these parents;
 509                                  * who are they?  Are they the same?
 510                                  */
 511                                 this_diff = ll->parent_map;
 512                                 if (!same_diff)
 513                                         same_diff = this_diff;
 514                                 else if (same_diff != this_diff) {
 515                                         has_interesting = 1;
 516                                 }
 517                                 ll = ll->next;
 518                         }
 519                 }
 520
 521                 if (!has_interesting && same_diff != all_mask) {
 522                         /* This hunk is not that interesting after all */
 523                         for (j = hunk_begin; j < hunk_end; j++)
 524                                 sline[j].flag &= ~mark;
 525                 }
 526                 i = hunk_end;
 527         }
 528
 529         has_interesting = give_context(sline, cnt, num_parent);
 530         return has_interesting;
 531 }
 532
 533 static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, unsigned long cnt, int n)
 534 {
 535         l0 = sline[l0].p_lno[n];
 536         l1 = sline[l1].p_lno[n];
 537         printf(" -%lu,%lu", l0, l1-l0);
 538 }
 539
 540 static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent)
 541 {
 542         unsigned long mark = (1UL<<num_parent);
 543         int i;
 544         unsigned long lno = 0;
 545
 546         if (!cnt)
 547                 return; /* result deleted */
 548
 549         while (1) {
 550                 struct sline *sl = &sline[lno];
 551                 int hunk_end;
 552                 while (lno < cnt && !(sline[lno].flag & mark))
 553                         lno++;
 554                 if (cnt <= lno)
 555                         break;
 556                 for (hunk_end = lno + 1; hunk_end < cnt; hunk_end++)
 557                         if (!(sline[hunk_end].flag & mark))
 558                                 break;
 559                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 560                 for (i = 0; i < num_parent; i++)
 561                         show_parent_lno(sline, lno, hunk_end, cnt, i);
 562                 printf(" +%lu,%lu ", lno+1, hunk_end-lno);
 563                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 564                 putchar('\n');
 565                 while (lno < hunk_end) {
 566                         struct lline *ll;
 567                         int j;
 568                         unsigned long p_mask;
 569                         sl = &sline[lno++];
 570                         ll = sl->lost_head;
 571                         while (ll) {
 572                                 for (j = 0; j < num_parent; j++) {
 573                                         if (ll->parent_map & (1UL<<j))
 574                                                 putchar('-');
 575                                         else
 576                                                 putchar(' ');
 577                                 }
 578                                 puts(ll->line);
 579                                 ll = ll->next;
 580                         }
 581                         p_mask = 1;
 582                         for (j = 0; j < num_parent; j++) {
 583                                 if (p_mask & sl->flag)
 584                                         putchar('+');
 585                                 else
 586                                         putchar(' ');
 587                                 p_mask <<= 1;
 588                         }
 589                         printf("%.*s\n", sl->len, sl->bol);
 590                 }
 591         }
 592 }
 593
 594 static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 595                                int i, int j)
 596 {
 597         /* We have already examined parent j and we know parent i
 598          * and parent j are the same, so reuse the combined result
 599          * of parent j for parent i.
 600          */
 601         unsigned long lno, imask, jmask;
 602         imask = (1UL<<i);
 603         jmask = (1UL<<j);
 604
 605         for (lno = 0; lno < cnt; lno++) {
 606                 struct lline *ll = sline->lost_head;
 607                 sline->p_lno[i] = sline->p_lno[j];
 608                 while (ll) {
 609                         if (ll->parent_map & jmask)
 610                                 ll->parent_map |= imask;
 611                         ll = ll->next;
 612                 }
 613                 if (sline->flag & jmask)
 614                         sline->flag |= imask;
 615                 sline++;
 616         }
 617         /* the overall size of the file (sline[cnt]) */
 618         sline->p_lno[i] = sline->p_lno[j];
 619 }
 620
 621 int show_combined_diff(struct combine_diff_path *elem, int num_parent,
 622                        int dense, const char *header)
 623 {
 624         unsigned long size, cnt, lno;
 625         char *result, *cp, *ep;
 626         struct sline *sline; /* survived lines */
 627         int mode_differs = 0;
 628         int i, show_hunks, shown_header = 0;
 629         char ourtmp_buf[TMPPATHLEN];
 630         char *ourtmp = ourtmp_buf;
 631
 632         /* Read the result of merge first */
 633         if (memcmp(elem->sha1, null_sha1, 20)) {
 634                 result = grab_blob(elem->sha1, &size);
 635                 write_to_temp_file(ourtmp, result, size);
 636         }
 637         else {
 638                 /* Used by diff-tree to read from the working tree */
 639                 struct stat st;
 640                 int fd;
 641                 ourtmp = elem->path;
 642                 if (0 <= (fd = open(ourtmp, O_RDONLY)) &&
 643                     !fstat(fd, &st)) {
 644                         int len = st.st_size;
 645                         int cnt = 0;
 646
 647                         size = len;
 648                         result = xmalloc(len + 1);
 649                         while (cnt < len) {
 650                                 int done = xread(fd, result+cnt, len-cnt);
 651                                 if (done == 0)
 652                                         break;
 653                                 if (done < 0)
 654                                         die("read error '%s'", ourtmp);
 655                                 cnt += done;
 656                         }
 657                         result[len] = 0;
 658                 }
 659                 else {
 660                         /* deleted file */
 661                         size = 0;
 662                         result = xmalloc(1);
 663                         result[0] = 0;
 664                         ourtmp = "/dev/null";
 665                 }
 666                 if (0 <= fd)
 667                         close(fd);
 668         }
 669
 670         for (cnt = 0, cp = result; cp - result < size; cp++) {
 671                 if (*cp == '\n')
 672                         cnt++;
 673         }
 674         if (size && result[size-1] != '\n')
 675                 cnt++; /* incomplete line */
 676
 677         sline = xcalloc(cnt+1, sizeof(*sline));
 678         ep = result;
 679         sline[0].bol = result;
 680         for (lno = 0; lno <= cnt; lno++) {
 681                 sline[lno].lost_tail = &sline[lno].lost_head;
 682                 sline[lno].flag = 0;
 683         }
 684         for (lno = 0, cp = result; cp - result < size; cp++) {
 685                 if (*cp == '\n') {
 686                         sline[lno].len = cp - sline[lno].bol;
 687                         lno++;
 688                         if (lno < cnt)
 689                                 sline[lno].bol = cp + 1;
 690                 }
 691         }
 692         if (size && result[size-1] != '\n')
 693                 sline[cnt-1].len = size - (sline[cnt-1].bol - result);
 694
 695         sline[0].p_lno = xcalloc((cnt+1) * num_parent, sizeof(unsigned long));
 696         for (lno = 0; lno < cnt; lno++)
 697                 sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
 698
 699         for (i = 0; i < num_parent; i++) {
 700                 int j;
 701                 for (j = 0; j < i; j++) {
 702                         if (!memcmp(elem->parent[i].sha1,
 703                                     elem->parent[j].sha1, 20)) {
 704                                 reuse_combine_diff(sline, cnt, i, j);
 705                                 break;
 706                         }
 707                 }
 708                 if (i <= j)
 709                         combine_diff(elem->parent[i].sha1, ourtmp, sline,
 710                                      cnt, i, num_parent);
 711                 if (elem->parent[i].mode != elem->mode)
 712                         mode_differs = 1;
 713         }
 714
 715         show_hunks = make_hunks(sline, cnt, num_parent, dense);
 716
 717         if (show_hunks || mode_differs) {
 718                 const char *abb;
 719                 char null_abb[DEFAULT_ABBREV + 1];
 720
 721                 memset(null_abb, '0', DEFAULT_ABBREV);
 722                 null_abb[DEFAULT_ABBREV] = 0;
 723                 if (header) {
 724                         shown_header++;
 725                         puts(header);
 726                 }
 727                 printf("diff --%s ", dense ? "cc" : "combined");
 728                 if (quote_c_style(elem->path, NULL, NULL, 0))
 729                         quote_c_style(elem->path, NULL, stdout, 0);
 730                 else
 731                         printf("%s", elem->path);
 732                 putchar('\n');
 733                 printf("index ");
 734                 for (i = 0; i < num_parent; i++) {
 735                         if (elem->parent[i].mode != elem->mode)
 736                                 mode_differs = 1;
 737                         if (memcmp(elem->parent[i].sha1, null_sha1, 20))
 738                                 abb = find_unique_abbrev(elem->parent[i].sha1,
 739                                                          DEFAULT_ABBREV);
 740                         else
 741                                 abb = null_abb;
 742                         printf("%s%s", i ? "," : "", abb);
 743                 }
 744                 if (memcmp(elem->sha1, null_sha1, 20))
 745                         abb = find_unique_abbrev(elem->sha1, DEFAULT_ABBREV);
 746                 else
 747                         abb = null_abb;
 748                 printf("..%s\n", abb);
 749
 750                 if (mode_differs) {
 751                         printf("mode ");
 752                         for (i = 0; i < num_parent; i++) {
 753                                 printf("%s%06o", i ? "," : "",
 754                                        elem->parent[i].mode);
 755                         }
 756                         printf("..%06o\n", elem->mode);
 757                 }
 758                 dump_sline(sline, cnt, num_parent);
 759         }
 760         if (ourtmp == ourtmp_buf)
 761                 unlink(ourtmp);
 762         free(result);
 763
 764         for (i = 0; i < cnt; i++) {
 765                 if (sline[i].lost_head) {
 766                         struct lline *ll = sline[i].lost_head;
 767                         while (ll) {
 768                                 struct lline *tmp = ll;
 769                                 ll = ll->next;
 770                                 free(tmp);
 771                         }
 772                 }
 773         }
 774         free(sline[0].p_lno);
 775         free(sline);
 776         return shown_header;
 777 }
 778
 779 int diff_tree_combined_merge(const unsigned char *sha1,
 780                              const char *header, int dense)
 781 {
 782         struct commit *commit = lookup_commit(sha1);
 783         struct diff_options diffopts;
 784         struct commit_list *parents;
 785         struct combine_diff_path *p, *paths = NULL;
 786         int num_parent, i, num_paths;
 787
 788         diff_setup(&diffopts);
 789         diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
 790         diffopts.recursive = 1;
 791
 792         /* count parents */
 793         for (parents = commit->parents, num_parent = 0;
 794              parents;
 795              parents = parents->next, num_parent++)
 796                 ; /* nothing */
 797
 798         /* find set of paths that everybody touches */
 799         for (parents = commit->parents, i = 0;
 800              parents;
 801              parents = parents->next, i++) {
 802                 struct commit *parent = parents->item;
 803                 diff_tree_sha1(parent->object.sha1, commit->object.sha1, "",
 804                                &diffopts);
 805                 paths = intersect_paths(paths, i, num_parent);
 806                 diff_flush(&diffopts);
 807         }
 808
 809         /* find out surviving paths */
 810         for (num_paths = 0, p = paths; p; p = p->next) {
 811                 if (p->len)
 812                         num_paths++;
 813         }
 814         if (num_paths) {
 815                 for (p = paths; p; p = p->next) {
 816                         if (!p->len)
 817                                 continue;
 818                         if (show_combined_diff(p, num_parent, dense, header))
 819                                 header = NULL;
 820                 }
 821         }
 822
 823         /* Clean things up */
 824         while (paths) {
 825                 struct combine_diff_path *tmp = paths;
 826                 paths = paths->next;
 827                 free(tmp);
 828         }
 829         return 0;
 830 }