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         if (!S_ISREG(p->one->mode) || !S_ISREG(p->two->mode))
  12                 return 1;
  13         return 0;
  14 }
  15
  16 static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr, int n, int num_parent)
  17 {
  18         struct diff_queue_struct *q = &diff_queued_diff;
  19         struct combine_diff_path *p;
  20         int i;
  21
  22         if (!n) {
  23                 struct combine_diff_path *list = NULL, **tail = &list;
  24                 for (i = 0; i < q->nr; i++) {
  25                         int len;
  26                         const char *path;
  27                         if (uninteresting(q->queue[i]))
  28                                 continue;
  29                         path = q->queue[i]->two->path;
  30                         len = strlen(path);
  31
  32                         p = xmalloc(sizeof(*p) + len + 1 + num_parent * 20);
  33                         p->path = (char*) &(p->parent_sha1[num_parent][0]);
  34                         memcpy(p->path, path, len);
  35                         p->path[len] = 0;
  36                         p->len = len;
  37                         p->next = NULL;
  38                         memcpy(p->sha1, q->queue[i]->two->sha1, 20);
  39                         memcpy(p->parent_sha1[n], q->queue[i]->one->sha1, 20);
  40                         *tail = p;
  41                         tail = &p->next;
  42                 }
  43                 return list;
  44         }
  45
  46         for (p = curr; p; p = p->next) {
  47                 int found = 0;
  48                 if (!p->len)
  49                         continue;
  50                 for (i = 0; i < q->nr; i++) {
  51                         const char *path;
  52                         int len;
  53
  54                         if (uninteresting(q->queue[i]))
  55                                 continue;
  56                         path = q->queue[i]->two->path;
  57                         len = strlen(path);
  58                         if (len == p->len && !memcmp(path, p->path, len)) {
  59                                 found = 1;
  60                                 memcpy(p->parent_sha1[n],
  61                                        q->queue[i]->one->sha1, 20);
  62                                 break;
  63                         }
  64                 }
  65                 if (!found)
  66                         p->len = 0;
  67         }
  68         return curr;
  69 }
  70
  71 /* Lines lost from parent */
  72 struct lline {
  73         struct lline *next;
  74         int len;
  75         unsigned long parent_map;
  76         char line[FLEX_ARRAY];
  77 };
  78
  79 /* Lines surviving in the merge result */
  80 struct sline {
  81         struct lline *lost_head, **lost_tail;
  82         char *bol;
  83         int len;
  84         /* bit 0 up to (N-1) are on if the parent does _not_
  85          * have this line (i.e. we changed it).
  86          * bit N is used for "interesting" lines, including context.
  87          */
  88         unsigned long flag;
  89         unsigned long *p_lno;
  90 };
  91
  92 static char *grab_blob(const unsigned char *sha1, unsigned long *size)
  93 {
  94         char *blob;
  95         char type[20];
  96         if (!memcmp(sha1, null_sha1, 20)) {
  97                 /* deleted blob */
  98                 *size = 0;
  99                 return xcalloc(1, 1);
 100         }
 101         blob = read_sha1_file(sha1, type, size);
 102         if (strcmp(type, "blob"))
 103                 die("object '%s' is not a blob!", sha1_to_hex(sha1));
 104         return blob;
 105 }
 106
 107 #define TMPPATHLEN 50
 108 #define MAXLINELEN 10240
 109
 110 static void write_to_temp_file(char *tmpfile, void *blob, unsigned long size)
 111 {
 112         int fd = git_mkstemp(tmpfile, TMPPATHLEN, ".diff_XXXXXX");
 113         if (fd < 0)
 114                 die("unable to create temp-file");
 115         if (write(fd, blob, size) != size)
 116                 die("unable to write temp-file");
 117         close(fd);
 118 }
 119
 120 static void write_temp_blob(char *tmpfile, const unsigned char *sha1)
 121 {
 122         unsigned long size;
 123         void *blob;
 124         blob = grab_blob(sha1, &size);
 125         write_to_temp_file(tmpfile, blob, size);
 126         free(blob);
 127 }
 128
 129 static int parse_num(char **cp_p, unsigned int *num_p)
 130 {
 131         char *cp = *cp_p;
 132         unsigned int num = 0;
 133         int read_some;
 134
 135         while ('0' <= *cp && *cp <= '9')
 136                 num = num * 10 + *cp++ - '0';
 137         if (!(read_some = cp - *cp_p))
 138                 return -1;
 139         *cp_p = cp;
 140         *num_p = num;
 141         return 0;
 142 }
 143
 144 static int parse_hunk_header(char *line, int len,
 145                              unsigned int *ob, unsigned int *on,
 146                              unsigned int *nb, unsigned int *nn)
 147 {
 148         char *cp;
 149         cp = line + 4;
 150         if (parse_num(&cp, ob)) {
 151         bad_line:
 152                 return error("malformed diff output: %s", line);
 153         }
 154         if (*cp == ',') {
 155                 cp++;
 156                 if (parse_num(&cp, on))
 157                         goto bad_line;
 158         }
 159         else
 160                 *on = 1;
 161         if (*cp++ != ' ' || *cp++ != '+')
 162                 goto bad_line;
 163         if (parse_num(&cp, nb))
 164                 goto bad_line;
 165         if (*cp == ',') {
 166                 cp++;
 167                 if (parse_num(&cp, nn))
 168                         goto bad_line;
 169         }
 170         else
 171                 *nn = 1;
 172         return -!!memcmp(cp, " @@", 3);
 173 }
 174
 175 static void append_lost(struct sline *sline, int n, const char *line)
 176 {
 177         struct lline *lline;
 178         int len = strlen(line);
 179         unsigned long this_mask = (1UL<<n);
 180         if (line[len-1] == '\n')
 181                 len--;
 182
 183         /* Check to see if we can squash things */
 184         if (sline->lost_head) {
 185                 struct lline *last_one = NULL;
 186                 /* We cannot squash it with earlier one */
 187                 for (lline = sline->lost_head;
 188                      lline;
 189                      lline = lline->next)
 190                         if (lline->parent_map & this_mask)
 191                                 last_one = lline;
 192                 lline = last_one ? last_one->next : sline->lost_head;
 193                 while (lline) {
 194                         if (lline->len == len &&
 195                             !memcmp(lline->line, line, len)) {
 196                                 lline->parent_map |= this_mask;
 197                                 return;
 198                         }
 199                         lline = lline->next;
 200                 }
 201         }
 202
 203         lline = xmalloc(sizeof(*lline) + len + 1);
 204         lline->len = len;
 205         lline->next = NULL;
 206         lline->parent_map = this_mask;
 207         memcpy(lline->line, line, len);
 208         lline->line[len] = 0;
 209         *sline->lost_tail = lline;
 210         sline->lost_tail = &lline->next;
 211 }
 212
 213 static void combine_diff(const unsigned char *parent, const char *ourtmp,
 214                          struct sline *sline, int cnt, int n, int num_parent)
 215 {
 216         FILE *in;
 217         char parent_tmp[TMPPATHLEN];
 218         char cmd[TMPPATHLEN * 2 + 1024];
 219         char line[MAXLINELEN];
 220         unsigned int lno, ob, on, nb, nn, p_lno;
 221         unsigned long nmask = (1UL << n);
 222         unsigned long pmask = ~nmask;
 223         struct sline *lost_bucket = NULL;
 224
 225         write_temp_blob(parent_tmp, parent);
 226         sprintf(cmd, "diff --unified=0 -La/x -Lb/x '%s' '%s'",
 227                 parent_tmp, ourtmp);
 228         in = popen(cmd, "r");
 229         if (!in)
 230                 die("cannot spawn %s", cmd);
 231
 232         lno = 1;
 233         while (fgets(line, sizeof(line), in) != NULL) {
 234                 int len = strlen(line);
 235                 if (5 < len && !memcmp("@@ -", line, 4)) {
 236                         if (parse_hunk_header(line, len,
 237                                               &ob, &on, &nb, &nn))
 238                                 break;
 239                         lno = nb;
 240                         if (!nb)
 241                                 /* @@ -1,2 +0,0 @@ to remove the
 242                                  * first two lines...
 243                                  */
 244                                 nb = 1;
 245                         if (nn == 0)
 246                                 /* @@ -X,Y +N,0 @@ removed Y lines
 247                                  * that would have come *after* line N
 248                                  * in the result.  Our lost buckets hang
 249                                  * to the line after the removed lines,
 250                                  */
 251                                 lost_bucket = &sline[nb];
 252                         else
 253                                 lost_bucket = &sline[nb-1];
 254                         if (!sline[nb-1].p_lno)
 255                                 sline[nb-1].p_lno =
 256                                         xcalloc(num_parent,
 257                                                 sizeof(unsigned long));
 258                         sline[nb-1].p_lno[n] = ob;
 259                         continue;
 260                 }
 261                 if (!lost_bucket)
 262                         continue; /* not in any hunk yet */
 263                 switch (line[0]) {
 264                 case '-':
 265                         append_lost(lost_bucket, n, line+1);
 266                         break;
 267                 case '+':
 268                         sline[lno-1].flag &= pmask;
 269                         lno++;
 270                         break;
 271                 }
 272         }
 273         fclose(in);
 274         unlink(parent_tmp);
 275
 276         /* Assign line numbers for this parent.
 277          *
 278          * sline[lno].p_lno[n] records the first line number
 279          * (counting from 1) for parent N if the final hunk display
 280          * started by showing sline[lno] (possibly showing the lost
 281          * lines attached to it first).
 282          */
 283         for (lno = 0,  p_lno = 1; lno < cnt; lno++) {
 284                 struct lline *ll;
 285                 sline[lno].p_lno[n] = p_lno;
 286
 287                 /* How many lines would this sline advance the p_lno? */
 288                 ll = sline[lno].lost_head;
 289                 while (ll) {
 290                         if (ll->parent_map & nmask)
 291                                 p_lno++; /* '-' means parent had it */
 292                         ll = ll->next;
 293                 }
 294                 if (sline[lno].flag & nmask)
 295                         p_lno++; /* no '+' means parent had it */
 296         }
 297         sline[lno].p_lno[n] = p_lno; /* trailer */
 298 }
 299
 300 static unsigned long context = 3;
 301 static char combine_marker = '@';
 302
 303 static int interesting(struct sline *sline, unsigned long all_mask)
 304 {
 305         return ((sline->flag & all_mask) != all_mask || sline->lost_head);
 306 }
 307
 308 static unsigned long adjust_hunk_tail(struct sline *sline,
 309                                       unsigned long all_mask,
 310                                       unsigned long hunk_begin,
 311                                       unsigned long i)
 312 {
 313         /* i points at the first uninteresting line.
 314          * If the last line of the hunk was interesting
 315          * only because it has some deletion, then
 316          * it is not all that interesting for the
 317          * purpose of giving trailing context lines.
 318          */
 319         if ((hunk_begin + 1 <= i) &&
 320             ((sline[i-1].flag & all_mask) == all_mask))
 321                 i--;
 322         return i;
 323 }
 324
 325 static unsigned long next_interesting(struct sline *sline,
 326                                       unsigned long mark,
 327                                       unsigned long i,
 328                                       unsigned long cnt,
 329                                       int uninteresting)
 330 {
 331         while (i < cnt)
 332                 if (uninteresting ?
 333                     !(sline[i].flag & mark) :
 334                     (sline[i].flag & mark))
 335                         return i;
 336                 else
 337                         i++;
 338         return cnt;
 339 }
 340
 341 static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
 342 {
 343         unsigned long all_mask = (1UL<<num_parent) - 1;
 344         unsigned long mark = (1UL<<num_parent);
 345         unsigned long i;
 346
 347         i = next_interesting(sline, mark, 0, cnt, 0);
 348         if (cnt <= i)
 349                 return 0;
 350
 351         while (i < cnt) {
 352                 unsigned long j = (context < i) ? (i - context) : 0;
 353                 unsigned long k;
 354                 while (j < i)
 355                         sline[j++].flag |= mark;
 356
 357         again:
 358                 j = next_interesting(sline, mark, i, cnt, 1);
 359                 if (cnt <= j)
 360                         break; /* the rest are all interesting */
 361
 362                 /* lookahead context lines */
 363                 k = next_interesting(sline, mark, j, cnt, 0);
 364                 j = adjust_hunk_tail(sline, all_mask, i, j);
 365
 366                 if (k < j + context) {
 367                         /* k is interesting and [j,k) are not, but
 368                          * paint them interesting because the gap is small.
 369                          */
 370                         while (j < k)
 371                                 sline[j++].flag |= mark;
 372                         i = k;
 373                         goto again;
 374                 }
 375
 376                 /* j is the first uninteresting line and there is
 377                  * no overlap beyond it within context lines.
 378                  */
 379                 i = k;
 380                 k = (j + context < cnt) ? j + context : cnt;
 381                 while (j < k)
 382                         sline[j++].flag |= mark;
 383         }
 384         return 1;
 385 }
 386
 387 static int make_hunks(struct sline *sline, unsigned long cnt,
 388                        int num_parent, int dense)
 389 {
 390         unsigned long all_mask = (1UL<<num_parent) - 1;
 391         unsigned long mark = (1UL<<num_parent);
 392         unsigned long i;
 393         int has_interesting = 0;
 394
 395         for (i = 0; i < cnt; i++) {
 396                 if (interesting(&sline[i], all_mask))
 397                         sline[i].flag |= mark;
 398                 else
 399                         sline[i].flag &= ~mark;
 400         }
 401         if (!dense)
 402                 return give_context(sline, cnt, num_parent);
 403
 404         /* Look at each hunk, and if we have changes from only one
 405          * parent, or the changes are the same from all but one
 406          * parent, mark that uninteresting.
 407          */
 408         i = 0;
 409         while (i < cnt) {
 410                 unsigned long j, hunk_begin, hunk_end;
 411                 unsigned long same_diff;
 412                 while (i < cnt && !(sline[i].flag & mark))
 413                         i++;
 414                 if (cnt <= i)
 415                         break; /* No more interesting hunks */
 416                 hunk_begin = i;
 417                 for (j = i + 1; j < cnt; j++) {
 418                         if (!(sline[j].flag & mark)) {
 419                                 /* Look beyond the end to see if there
 420                                  * is an interesting line after this
 421                                  * hunk within context span.
 422                                  */
 423                                 unsigned long la; /* lookahead */
 424                                 int contin = 0;
 425                                 la = adjust_hunk_tail(sline, all_mask,
 426                                                      hunk_begin, j);
 427                                 la = (la + context < cnt) ?
 428                                         (la + context) : cnt;
 429                                 while (j <= --la) {
 430                                         if (sline[la].flag & mark) {
 431                                                 contin = 1;
 432                                                 break;
 433                                         }
 434                                 }
 435                                 if (!contin)
 436                                         break;
 437                                 j = la;
 438                         }
 439                 }
 440                 hunk_end = j;
 441
 442                 /* [i..hunk_end) are interesting.  Now is it really
 443                  * interesting?  We check if there are only two versions
 444                  * and the result matches one of them.  That is, we look
 445                  * at:
 446                  *   (+) line, which records lines added to which parents;
 447                  *       this line appears in the result.
 448                  *   (-) line, which records from what parents the line
 449                  *       was removed; this line does not appear in the result.
 450                  * then check the set of parents the result has difference
 451                  * from, from all lines.  If there are lines that has
 452                  * different set of parents that the result has differences
 453                  * from, that means we have more than two versions.
 454                  *
 455                  * Even when we have only two versions, if the result does
 456                  * not match any of the parents, the it should be considered
 457                  * interesting.  In such a case, we would have all '+' line.
 458                  * After passing the above "two versions" test, that would
 459                  * appear as "the same set of parents" to be "all parents".
 460                  */
 461                 same_diff = 0;
 462                 has_interesting = 0;
 463                 for (j = i; j < hunk_end && !has_interesting; j++) {
 464                         unsigned long this_diff = ~sline[j].flag & all_mask;
 465                         struct lline *ll = sline[j].lost_head;
 466                         if (this_diff) {
 467                                 /* This has some changes.  Is it the
 468                                  * same as others?
 469                                  */
 470                                 if (!same_diff)
 471                                         same_diff = this_diff;
 472                                 else if (same_diff != this_diff) {
 473                                         has_interesting = 1;
 474                                         break;
 475                                 }
 476                         }
 477                         while (ll && !has_interesting) {
 478                                 /* Lost this line from these parents;
 479                                  * who are they?  Are they the same?
 480                                  */
 481                                 this_diff = ll->parent_map;
 482                                 if (!same_diff)
 483                                         same_diff = this_diff;
 484                                 else if (same_diff != this_diff) {
 485                                         has_interesting = 1;
 486                                 }
 487                                 ll = ll->next;
 488                         }
 489                 }
 490
 491                 if (!has_interesting && same_diff != all_mask) {
 492                         /* This hunk is not that interesting after all */
 493                         for (j = hunk_begin; j < hunk_end; j++)
 494                                 sline[j].flag &= ~mark;
 495                 }
 496                 i = hunk_end;
 497         }
 498
 499         has_interesting = give_context(sline, cnt, num_parent);
 500         return has_interesting;
 501 }
 502
 503 static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, unsigned long cnt, int n)
 504 {
 505         l0 = sline[l0].p_lno[n];
 506         l1 = sline[l1].p_lno[n];
 507         printf("-%lu,%lu ", l0, l1-l0);
 508 }
 509
 510 static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent)
 511 {
 512         unsigned long mark = (1UL<<num_parent);
 513         int i;
 514         unsigned long lno = 0;
 515
 516         while (1) {
 517                 struct sline *sl = &sline[lno];
 518                 int hunk_end;
 519                 while (lno < cnt && !(sline[lno].flag & mark))
 520                         lno++;
 521                 if (cnt <= lno)
 522                         break;
 523                 for (hunk_end = lno + 1; hunk_end < cnt; hunk_end++)
 524                         if (!(sline[hunk_end].flag & mark))
 525                                 break;
 526                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 527                 printf(" +%lu,%lu ", lno+1, hunk_end-lno);
 528                 for (i = 0; i < num_parent; i++)
 529                         show_parent_lno(sline, lno, hunk_end, cnt, i);
 530                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 531                 putchar('\n');
 532                 while (lno < hunk_end) {
 533                         struct lline *ll;
 534                         int j;
 535                         sl = &sline[lno++];
 536                         ll = sl->lost_head;
 537                         while (ll) {
 538                                 for (j = 0; j < num_parent; j++) {
 539                                         if (ll->parent_map & (1UL<<j))
 540                                                 putchar('-');
 541                                         else
 542                                                 putchar(' ');
 543                                 }
 544                                 puts(ll->line);
 545                                 ll = ll->next;
 546                         }
 547                         for (j = 0; j < num_parent; j++) {
 548                                 if ((1UL<<j) & sl->flag)
 549                                         putchar(' ');
 550                                 else
 551                                         putchar('+');
 552                         }
 553                         printf("%.*s\n", sl->len, sl->bol);
 554                 }
 555         }
 556 }
 557
 558 static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 559                                int i, int j)
 560 {
 561         /* We have already examined parent j and we know parent i
 562          * and parent j are the same, so reuse the combined result
 563          * of parent j for parent i.
 564          */
 565         unsigned long lno, imask, jmask;
 566         imask = (1UL<<i);
 567         jmask = (1UL<<j);
 568
 569         for (lno = 0; lno < cnt; lno++) {
 570                 struct lline *ll = sline->lost_head;
 571                 sline->p_lno[i] = sline->p_lno[j];
 572                 while (ll) {
 573                         if (ll->parent_map & jmask)
 574                                 ll->parent_map |= imask;
 575                         ll = ll->next;
 576                 }
 577                 if (!(sline->flag & jmask))
 578                         sline->flag &= ~imask;
 579                 sline++;
 580         }
 581 }
 582
 583 int show_combined_diff(struct combine_diff_path *elem, int num_parent,
 584                        int dense, const char *header, int show_empty)
 585 {
 586         unsigned long size, cnt, lno;
 587         char *result, *cp, *ep;
 588         struct sline *sline; /* survived lines */
 589         int i, show_hunks, shown_header = 0;
 590         char ourtmp_buf[TMPPATHLEN];
 591         char *ourtmp = ourtmp_buf;
 592
 593         /* Read the result of merge first */
 594         if (memcmp(elem->sha1, null_sha1, 20)) {
 595                 result = grab_blob(elem->sha1, &size);
 596                 write_to_temp_file(ourtmp, result, size);
 597         }
 598         else {
 599                 struct stat st;
 600                 int fd;
 601                 ourtmp = elem->path;
 602                 if (0 <= (fd = open(ourtmp, O_RDONLY)) &&
 603                     !fstat(fd, &st)) {
 604                         int len = st.st_size;
 605                         int cnt = 0;
 606
 607                         size = len;
 608                         result = xmalloc(len + 1);
 609                         while (cnt < len) {
 610                                 int done = xread(fd, result+cnt, len-cnt);
 611                                 if (done == 0)
 612                                         break;
 613                                 if (done < 0)
 614                                         die("read error '%s'", ourtmp);
 615                                 cnt += done;
 616                         }
 617                         result[len] = 0;
 618                 }
 619                 else {
 620                         /* deleted file */
 621                         size = 0;
 622                         result = xmalloc(1);
 623                         result[0] = 0;
 624                         ourtmp = "/dev/null";
 625                 }
 626                 if (0 <= fd)
 627                         close(fd);
 628         }
 629
 630         for (cnt = 0, cp = result; cp - result < size; cp++) {
 631                 if (*cp == '\n')
 632                         cnt++;
 633         }
 634         if (result[size-1] != '\n')
 635                 cnt++; /* incomplete line */
 636
 637         sline = xcalloc(cnt+1, sizeof(*sline));
 638         ep = result;
 639         sline[0].bol = result;
 640         for (lno = 0, cp = result; cp - result < size; cp++) {
 641                 if (*cp == '\n') {
 642                         sline[lno].lost_tail = &sline[lno].lost_head;
 643                         sline[lno].len = cp - sline[lno].bol;
 644                         sline[lno].flag = (1UL<<num_parent) - 1;
 645                         lno++;
 646                         if (lno < cnt)
 647                                 sline[lno].bol = cp + 1;
 648                 }
 649         }
 650         if (result[size-1] != '\n') {
 651                 sline[cnt-1].lost_tail = &sline[cnt-1].lost_head;
 652                 sline[cnt-1].len = size - (sline[cnt-1].bol - result);
 653                 sline[cnt-1].flag = (1UL<<num_parent) - 1;
 654         }
 655
 656         sline[0].p_lno = xcalloc((cnt+1) * num_parent, sizeof(unsigned long));
 657         for (lno = 0; lno < cnt; lno++)
 658                 sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
 659
 660         for (i = 0; i < num_parent; i++) {
 661                 int j;
 662                 for (j = 0; j < i; j++) {
 663                         if (!memcmp(elem->parent_sha1[i],
 664                                     elem->parent_sha1[j], 20)) {
 665                                 reuse_combine_diff(sline, cnt, i, j);
 666                                 break;
 667                         }
 668                 }
 669                 if (i <= j)
 670                         combine_diff(elem->parent_sha1[i], ourtmp, sline,
 671                                      cnt, i, num_parent);
 672         }
 673
 674         show_hunks = make_hunks(sline, cnt, num_parent, dense);
 675
 676         if (header && (show_hunks || show_empty)) {
 677                 shown_header++;
 678                 puts(header);
 679         }
 680         if (show_hunks) {
 681                 printf("diff --%s ", dense ? "cc" : "combined");
 682                 if (quote_c_style(elem->path, NULL, NULL, 0))
 683                         quote_c_style(elem->path, NULL, stdout, 0);
 684                 else
 685                         printf("%s", elem->path);
 686                 putchar('\n');
 687                 printf("index ");
 688                 for (i = 0; i < num_parent; i++) {
 689                         printf("%s%s",
 690                                i ? ".." : "",
 691                                find_unique_abbrev(elem->parent_sha1[i],
 692                                                   DEFAULT_ABBREV));
 693                 }
 694                 printf("->%s\n",
 695                        find_unique_abbrev(elem->sha1, DEFAULT_ABBREV));
 696                 dump_sline(sline, cnt, num_parent);
 697         }
 698         if (ourtmp == ourtmp_buf)
 699                 unlink(ourtmp);
 700         free(result);
 701
 702         for (i = 0; i < cnt; i++) {
 703                 if (sline[i].lost_head) {
 704                         struct lline *ll = sline[i].lost_head;
 705                         while (ll) {
 706                                 struct lline *tmp = ll;
 707                                 ll = ll->next;
 708                                 free(tmp);
 709                         }
 710                 }
 711         }
 712         free(sline);
 713         return shown_header;
 714 }
 715
 716 int diff_tree_combined_merge(const unsigned char *sha1,
 717                              const char *header,
 718                              int show_empty_merge, int dense)
 719 {
 720         struct commit *commit = lookup_commit(sha1);
 721         struct diff_options diffopts;
 722         struct commit_list *parents;
 723         struct combine_diff_path *p, *paths = NULL;
 724         int num_parent, i, num_paths;
 725
 726         diff_setup(&diffopts);
 727         diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
 728         diffopts.recursive = 1;
 729
 730         /* count parents */
 731         for (parents = commit->parents, num_parent = 0;
 732              parents;
 733              parents = parents->next, num_parent++)
 734                 ; /* nothing */
 735
 736         /* find set of paths that everybody touches */
 737         for (parents = commit->parents, i = 0;
 738              parents;
 739              parents = parents->next, i++) {
 740                 struct commit *parent = parents->item;
 741                 diff_tree_sha1(parent->object.sha1, commit->object.sha1, "",
 742                                &diffopts);
 743                 paths = intersect_paths(paths, i, num_parent);
 744                 diff_flush(&diffopts);
 745         }
 746
 747         /* find out surviving paths */
 748         for (num_paths = 0, p = paths; p; p = p->next) {
 749                 if (p->len)
 750                         num_paths++;
 751         }
 752         if (num_paths || show_empty_merge) {
 753                 for (p = paths; p; p = p->next) {
 754                         if (!p->len)
 755                                 continue;
 756                         if (show_combined_diff(p, num_parent, dense, header,
 757                                                show_empty_merge))
 758                                 header = NULL;
 759                 }
 760         }
 761
 762         /* Clean things up */
 763         while (paths) {
 764                 struct combine_diff_path *tmp = paths;
 765                 paths = paths->next;
 766                 free(tmp);
 767         }
 768         return 0;
 769 }