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 "log-tree.h"
   9
  10 static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr, int n, int num_parent)
  11 {
  12         struct diff_queue_struct *q = &diff_queued_diff;
  13         struct combine_diff_path *p;
  14         int i;
  15
  16         if (!n) {
  17                 struct combine_diff_path *list = NULL, **tail = &list;
  18                 for (i = 0; i < q->nr; i++) {
  19                         int len;
  20                         const char *path;
  21                         if (diff_unmodified_pair(q->queue[i]))
  22                                 continue;
  23                         path = q->queue[i]->two->path;
  24                         len = strlen(path);
  25                         p = xmalloc(combine_diff_path_size(num_parent, len));
  26                         p->path = (char*) &(p->parent[num_parent]);
  27                         memcpy(p->path, path, len);
  28                         p->path[len] = 0;
  29                         p->len = len;
  30                         p->next = NULL;
  31                         memset(p->parent, 0,
  32                                sizeof(p->parent[0]) * num_parent);
  33
  34                         hashcpy(p->sha1, q->queue[i]->two->sha1);
  35                         p->mode = q->queue[i]->two->mode;
  36                         hashcpy(p->parent[n].sha1, q->queue[i]->one->sha1);
  37                         p->parent[n].mode = q->queue[i]->one->mode;
  38                         p->parent[n].status = q->queue[i]->status;
  39                         *tail = p;
  40                         tail = &p->next;
  41                 }
  42                 return list;
  43         }
  44
  45         for (p = curr; p; p = p->next) {
  46                 int found = 0;
  47                 if (!p->len)
  48                         continue;
  49                 for (i = 0; i < q->nr; i++) {
  50                         const char *path;
  51                         int len;
  52
  53                         if (diff_unmodified_pair(q->queue[i]))
  54                                 continue;
  55                         path = q->queue[i]->two->path;
  56                         len = strlen(path);
  57                         if (len == p->len && !memcmp(path, p->path, len)) {
  58                                 found = 1;
  59                                 hashcpy(p->parent[n].sha1, q->queue[i]->one->sha1);
  60                                 p->parent[n].mode = q->queue[i]->one->mode;
  61                                 p->parent[n].status = q->queue[i]->status;
  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 has this line (i.e.
  85          * we did not change it).
  86          * bit N is used for "interesting" lines, including context.
  87          * bit (N+1) is used for "do not show deletion before this".
  88          */
  89         unsigned long flag;
  90         unsigned long *p_lno;
  91 };
  92
  93 static char *grab_blob(const unsigned char *sha1, unsigned long *size)
  94 {
  95         char *blob;
  96         enum object_type type;
  97         if (is_null_sha1(sha1)) {
  98                 /* deleted blob */
  99                 *size = 0;
 100                 return xcalloc(1, 1);
 101         }
 102         blob = read_sha1_file(sha1, &type, size);
 103         if (type != OBJ_BLOB)
 104                 die("object '%s' is not a blob!", sha1_to_hex(sha1));
 105         return blob;
 106 }
 107
 108 static void append_lost(struct sline *sline, int n, const char *line, int len)
 109 {
 110         struct lline *lline;
 111         unsigned long this_mask = (1UL<<n);
 112         if (line[len-1] == '\n')
 113                 len--;
 114
 115         /* Check to see if we can squash things */
 116         if (sline->lost_head) {
 117                 struct lline *last_one = NULL;
 118                 /* We cannot squash it with earlier one */
 119                 for (lline = sline->lost_head;
 120                      lline;
 121                      lline = lline->next)
 122                         if (lline->parent_map & this_mask)
 123                                 last_one = lline;
 124                 lline = last_one ? last_one->next : sline->lost_head;
 125                 while (lline) {
 126                         if (lline->len == len &&
 127                             !memcmp(lline->line, line, len)) {
 128                                 lline->parent_map |= this_mask;
 129                                 return;
 130                         }
 131                         lline = lline->next;
 132                 }
 133         }
 134
 135         lline = xmalloc(sizeof(*lline) + len + 1);
 136         lline->len = len;
 137         lline->next = NULL;
 138         lline->parent_map = this_mask;
 139         memcpy(lline->line, line, len);
 140         lline->line[len] = 0;
 141         *sline->lost_tail = lline;
 142         sline->lost_tail = &lline->next;
 143 }
 144
 145 struct combine_diff_state {
 146         struct xdiff_emit_state xm;
 147
 148         unsigned int lno;
 149         int ob, on, nb, nn;
 150         unsigned long nmask;
 151         int num_parent;
 152         int n;
 153         struct sline *sline;
 154         struct sline *lost_bucket;
 155 };
 156
 157 static void consume_line(void *state_, char *line, unsigned long len)
 158 {
 159         struct combine_diff_state *state = state_;
 160         if (5 < len && !memcmp("@@ -", line, 4)) {
 161                 if (parse_hunk_header(line, len,
 162                                       &state->ob, &state->on,
 163                                       &state->nb, &state->nn))
 164                         return;
 165                 state->lno = state->nb;
 166                 if (!state->nb)
 167                         /* @@ -1,2 +0,0 @@ to remove the
 168                          * first two lines...
 169                          */
 170                         state->nb = 1;
 171                 if (state->nn == 0)
 172                         /* @@ -X,Y +N,0 @@ removed Y lines
 173                          * that would have come *after* line N
 174                          * in the result.  Our lost buckets hang
 175                          * to the line after the removed lines,
 176                          */
 177                         state->lost_bucket = &state->sline[state->nb];
 178                 else
 179                         state->lost_bucket = &state->sline[state->nb-1];
 180                 if (!state->sline[state->nb-1].p_lno)
 181                         state->sline[state->nb-1].p_lno =
 182                                 xcalloc(state->num_parent,
 183                                         sizeof(unsigned long));
 184                 state->sline[state->nb-1].p_lno[state->n] = state->ob;
 185                 return;
 186         }
 187         if (!state->lost_bucket)
 188                 return; /* not in any hunk yet */
 189         switch (line[0]) {
 190         case '-':
 191                 append_lost(state->lost_bucket, state->n, line+1, len-1);
 192                 break;
 193         case '+':
 194                 state->sline[state->lno-1].flag |= state->nmask;
 195                 state->lno++;
 196                 break;
 197         }
 198 }
 199
 200 static void combine_diff(const unsigned char *parent, mmfile_t *result_file,
 201                          struct sline *sline, unsigned int cnt, int n,
 202                          int num_parent)
 203 {
 204         unsigned int p_lno, lno;
 205         unsigned long nmask = (1UL << n);
 206         xpparam_t xpp;
 207         xdemitconf_t xecfg;
 208         mmfile_t parent_file;
 209         xdemitcb_t ecb;
 210         struct combine_diff_state state;
 211         unsigned long sz;
 212
 213         if (!cnt)
 214                 return; /* result deleted */
 215
 216         parent_file.ptr = grab_blob(parent, &sz);
 217         parent_file.size = sz;
 218         xpp.flags = XDF_NEED_MINIMAL;
 219         memset(&xecfg, 0, sizeof(xecfg));
 220         memset(&state, 0, sizeof(state));
 221         state.xm.consume = consume_line;
 222         state.nmask = nmask;
 223         state.sline = sline;
 224         state.lno = 1;
 225         state.num_parent = num_parent;
 226         state.n = n;
 227
 228         xdi_diff_outf(&parent_file, result_file,
 229                       &state.xm, &xpp, &xecfg, &ecb);
 230         free(parent_file.ptr);
 231
 232         /* Assign line numbers for this parent.
 233          *
 234          * sline[lno].p_lno[n] records the first line number
 235          * (counting from 1) for parent N if the final hunk display
 236          * started by showing sline[lno] (possibly showing the lost
 237          * lines attached to it first).
 238          */
 239         for (lno = 0,  p_lno = 1; lno <= cnt; lno++) {
 240                 struct lline *ll;
 241                 sline[lno].p_lno[n] = p_lno;
 242
 243                 /* How many lines would this sline advance the p_lno? */
 244                 ll = sline[lno].lost_head;
 245                 while (ll) {
 246                         if (ll->parent_map & nmask)
 247                                 p_lno++; /* '-' means parent had it */
 248                         ll = ll->next;
 249                 }
 250                 if (lno < cnt && !(sline[lno].flag & nmask))
 251                         p_lno++; /* no '+' means parent had it */
 252         }
 253         sline[lno].p_lno[n] = p_lno; /* trailer */
 254 }
 255
 256 static unsigned long context = 3;
 257 static char combine_marker = '@';
 258
 259 static int interesting(struct sline *sline, unsigned long all_mask)
 260 {
 261         /* If some parents lost lines here, or if we have added to
 262          * some parent, it is interesting.
 263          */
 264         return ((sline->flag & all_mask) || sline->lost_head);
 265 }
 266
 267 static unsigned long adjust_hunk_tail(struct sline *sline,
 268                                       unsigned long all_mask,
 269                                       unsigned long hunk_begin,
 270                                       unsigned long i)
 271 {
 272         /* i points at the first uninteresting line.  If the last line
 273          * of the hunk was interesting only because it has some
 274          * deletion, then it is not all that interesting for the
 275          * purpose of giving trailing context lines.  This is because
 276          * we output '-' line and then unmodified sline[i-1] itself in
 277          * that case which gives us one extra context line.
 278          */
 279         if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
 280                 i--;
 281         return i;
 282 }
 283
 284 static unsigned long find_next(struct sline *sline,
 285                                unsigned long mark,
 286                                unsigned long i,
 287                                unsigned long cnt,
 288                                int look_for_uninteresting)
 289 {
 290         /* We have examined up to i-1 and are about to look at i.
 291          * Find next interesting or uninteresting line.  Here,
 292          * "interesting" does not mean interesting(), but marked by
 293          * the give_context() function below (i.e. it includes context
 294          * lines that are not interesting to interesting() function
 295          * that are surrounded by interesting() ones.
 296          */
 297         while (i <= cnt)
 298                 if (look_for_uninteresting
 299                     ? !(sline[i].flag & mark)
 300                     : (sline[i].flag & mark))
 301                         return i;
 302                 else
 303                         i++;
 304         return i;
 305 }
 306
 307 static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
 308 {
 309         unsigned long all_mask = (1UL<<num_parent) - 1;
 310         unsigned long mark = (1UL<<num_parent);
 311         unsigned long no_pre_delete = (2UL<<num_parent);
 312         unsigned long i;
 313
 314         /* Two groups of interesting lines may have a short gap of
 315          * uninteresting lines.  Connect such groups to give them a
 316          * bit of context.
 317          *
 318          * We first start from what the interesting() function says,
 319          * and mark them with "mark", and paint context lines with the
 320          * mark.  So interesting() would still say false for such context
 321          * lines but they are treated as "interesting" in the end.
 322          */
 323         i = find_next(sline, mark, 0, cnt, 0);
 324         if (cnt < i)
 325                 return 0;
 326
 327         while (i <= cnt) {
 328                 unsigned long j = (context < i) ? (i - context) : 0;
 329                 unsigned long k;
 330
 331                 /* Paint a few lines before the first interesting line. */
 332                 while (j < i)
 333                         sline[j++].flag |= mark | no_pre_delete;
 334
 335         again:
 336                 /* we know up to i is to be included.  where does the
 337                  * next uninteresting one start?
 338                  */
 339                 j = find_next(sline, mark, i, cnt, 1);
 340                 if (cnt < j)
 341                         break; /* the rest are all interesting */
 342
 343                 /* lookahead context lines */
 344                 k = find_next(sline, mark, j, cnt, 0);
 345                 j = adjust_hunk_tail(sline, all_mask, i, j);
 346
 347                 if (k < j + context) {
 348                         /* k is interesting and [j,k) are not, but
 349                          * paint them interesting because the gap is small.
 350                          */
 351                         while (j < k)
 352                                 sline[j++].flag |= mark;
 353                         i = k;
 354                         goto again;
 355                 }
 356
 357                 /* j is the first uninteresting line and there is
 358                  * no overlap beyond it within context lines.  Paint
 359                  * the trailing edge a bit.
 360                  */
 361                 i = k;
 362                 k = (j + context < cnt+1) ? j + context : cnt+1;
 363                 while (j < k)
 364                         sline[j++].flag |= mark;
 365         }
 366         return 1;
 367 }
 368
 369 static int make_hunks(struct sline *sline, unsigned long cnt,
 370                        int num_parent, int dense)
 371 {
 372         unsigned long all_mask = (1UL<<num_parent) - 1;
 373         unsigned long mark = (1UL<<num_parent);
 374         unsigned long i;
 375         int has_interesting = 0;
 376
 377         for (i = 0; i <= cnt; i++) {
 378                 if (interesting(&sline[i], all_mask))
 379                         sline[i].flag |= mark;
 380                 else
 381                         sline[i].flag &= ~mark;
 382         }
 383         if (!dense)
 384                 return give_context(sline, cnt, num_parent);
 385
 386         /* Look at each hunk, and if we have changes from only one
 387          * parent, or the changes are the same from all but one
 388          * parent, mark that uninteresting.
 389          */
 390         i = 0;
 391         while (i <= cnt) {
 392                 unsigned long j, hunk_begin, hunk_end;
 393                 unsigned long same_diff;
 394                 while (i <= cnt && !(sline[i].flag & mark))
 395                         i++;
 396                 if (cnt < i)
 397                         break; /* No more interesting hunks */
 398                 hunk_begin = i;
 399                 for (j = i + 1; j <= cnt; j++) {
 400                         if (!(sline[j].flag & mark)) {
 401                                 /* Look beyond the end to see if there
 402                                  * is an interesting line after this
 403                                  * hunk within context span.
 404                                  */
 405                                 unsigned long la; /* lookahead */
 406                                 int contin = 0;
 407                                 la = adjust_hunk_tail(sline, all_mask,
 408                                                      hunk_begin, j);
 409                                 la = (la + context < cnt + 1) ?
 410                                         (la + context) : cnt + 1;
 411                                 while (j <= --la) {
 412                                         if (sline[la].flag & mark) {
 413                                                 contin = 1;
 414                                                 break;
 415                                         }
 416                                 }
 417                                 if (!contin)
 418                                         break;
 419                                 j = la;
 420                         }
 421                 }
 422                 hunk_end = j;
 423
 424                 /* [i..hunk_end) are interesting.  Now is it really
 425                  * interesting?  We check if there are only two versions
 426                  * and the result matches one of them.  That is, we look
 427                  * at:
 428                  *   (+) line, which records lines added to which parents;
 429                  *       this line appears in the result.
 430                  *   (-) line, which records from what parents the line
 431                  *       was removed; this line does not appear in the result.
 432                  * then check the set of parents the result has difference
 433                  * from, from all lines.  If there are lines that has
 434                  * different set of parents that the result has differences
 435                  * from, that means we have more than two versions.
 436                  *
 437                  * Even when we have only two versions, if the result does
 438                  * not match any of the parents, the it should be considered
 439                  * interesting.  In such a case, we would have all '+' line.
 440                  * After passing the above "two versions" test, that would
 441                  * appear as "the same set of parents" to be "all parents".
 442                  */
 443                 same_diff = 0;
 444                 has_interesting = 0;
 445                 for (j = i; j < hunk_end && !has_interesting; j++) {
 446                         unsigned long this_diff = sline[j].flag & all_mask;
 447                         struct lline *ll = sline[j].lost_head;
 448                         if (this_diff) {
 449                                 /* This has some changes.  Is it the
 450                                  * same as others?
 451                                  */
 452                                 if (!same_diff)
 453                                         same_diff = this_diff;
 454                                 else if (same_diff != this_diff) {
 455                                         has_interesting = 1;
 456                                         break;
 457                                 }
 458                         }
 459                         while (ll && !has_interesting) {
 460                                 /* Lost this line from these parents;
 461                                  * who are they?  Are they the same?
 462                                  */
 463                                 this_diff = ll->parent_map;
 464                                 if (!same_diff)
 465                                         same_diff = this_diff;
 466                                 else if (same_diff != this_diff) {
 467                                         has_interesting = 1;
 468                                 }
 469                                 ll = ll->next;
 470                         }
 471                 }
 472
 473                 if (!has_interesting && same_diff != all_mask) {
 474                         /* This hunk is not that interesting after all */
 475                         for (j = hunk_begin; j < hunk_end; j++)
 476                                 sline[j].flag &= ~mark;
 477                 }
 478                 i = hunk_end;
 479         }
 480
 481         has_interesting = give_context(sline, cnt, num_parent);
 482         return has_interesting;
 483 }
 484
 485 static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, int n, unsigned long null_context)
 486 {
 487         l0 = sline[l0].p_lno[n];
 488         l1 = sline[l1].p_lno[n];
 489         printf(" -%lu,%lu", l0, l1-l0-null_context);
 490 }
 491
 492 static int hunk_comment_line(const char *bol)
 493 {
 494         int ch;
 495
 496         if (!bol)
 497                 return 0;
 498         ch = *bol & 0xff;
 499         return (isalpha(ch) || ch == '_' || ch == '$');
 500 }
 501
 502 static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent,
 503                        int use_color)
 504 {
 505         unsigned long mark = (1UL<<num_parent);
 506         unsigned long no_pre_delete = (2UL<<num_parent);
 507         int i;
 508         unsigned long lno = 0;
 509         const char *c_frag = diff_get_color(use_color, DIFF_FRAGINFO);
 510         const char *c_new = diff_get_color(use_color, DIFF_FILE_NEW);
 511         const char *c_old = diff_get_color(use_color, DIFF_FILE_OLD);
 512         const char *c_plain = diff_get_color(use_color, DIFF_PLAIN);
 513         const char *c_reset = diff_get_color(use_color, DIFF_RESET);
 514
 515         if (!cnt)
 516                 return; /* result deleted */
 517
 518         while (1) {
 519                 struct sline *sl = &sline[lno];
 520                 unsigned long hunk_end;
 521                 unsigned long rlines;
 522                 const char *hunk_comment = NULL;
 523                 unsigned long null_context = 0;
 524
 525                 while (lno <= cnt && !(sline[lno].flag & mark)) {
 526                         if (hunk_comment_line(sline[lno].bol))
 527                                 hunk_comment = sline[lno].bol;
 528                         lno++;
 529                 }
 530                 if (cnt < lno)
 531                         break;
 532                 else {
 533                         for (hunk_end = lno + 1; hunk_end <= cnt; hunk_end++)
 534                                 if (!(sline[hunk_end].flag & mark))
 535                                         break;
 536                 }
 537                 rlines = hunk_end - lno;
 538                 if (cnt < hunk_end)
 539                         rlines--; /* pointing at the last delete hunk */
 540
 541                 if (!context) {
 542                         /*
 543                          * Even when running with --unified=0, all
 544                          * lines in the hunk needs to be processed in
 545                          * the loop below in order to show the
 546                          * deletion recorded in lost_head.  However,
 547                          * we do not want to show the resulting line
 548                          * with all blank context markers in such a
 549                          * case.  Compensate.
 550                          */
 551                         unsigned long j;
 552                         for (j = lno; j < hunk_end; j++)
 553                                 if (!(sline[j].flag & (mark-1)))
 554                                         null_context++;
 555                         rlines -= null_context;
 556                 }
 557
 558                 fputs(c_frag, stdout);
 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, i, null_context);
 562                 printf(" +%lu,%lu ", lno+1, rlines);
 563                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 564
 565                 if (hunk_comment) {
 566                         int comment_end = 0;
 567                         for (i = 0; i < 40; i++) {
 568                                 int ch = hunk_comment[i] & 0xff;
 569                                 if (!ch || ch == '\n')
 570                                         break;
 571                                 if (!isspace(ch))
 572                                     comment_end = i;
 573                         }
 574                         if (comment_end)
 575                                 putchar(' ');
 576                         for (i = 0; i < comment_end; i++)
 577                                 putchar(hunk_comment[i]);
 578                 }
 579
 580                 printf("%s\n", c_reset);
 581                 while (lno < hunk_end) {
 582                         struct lline *ll;
 583                         int j;
 584                         unsigned long p_mask;
 585                         sl = &sline[lno++];
 586                         ll = (sl->flag & no_pre_delete) ? NULL : sl->lost_head;
 587                         while (ll) {
 588                                 fputs(c_old, stdout);
 589                                 for (j = 0; j < num_parent; j++) {
 590                                         if (ll->parent_map & (1UL<<j))
 591                                                 putchar('-');
 592                                         else
 593                                                 putchar(' ');
 594                                 }
 595                                 printf("%s%s\n", ll->line, c_reset);
 596                                 ll = ll->next;
 597                         }
 598                         if (cnt < lno)
 599                                 break;
 600                         p_mask = 1;
 601                         if (!(sl->flag & (mark-1))) {
 602                                 /*
 603                                  * This sline was here to hang the
 604                                  * lost lines in front of it.
 605                                  */
 606                                 if (!context)
 607                                         continue;
 608                                 fputs(c_plain, stdout);
 609                         }
 610                         else
 611                                 fputs(c_new, stdout);
 612                         for (j = 0; j < num_parent; j++) {
 613                                 if (p_mask & sl->flag)
 614                                         putchar('+');
 615                                 else
 616                                         putchar(' ');
 617                                 p_mask <<= 1;
 618                         }
 619                         printf("%.*s%s\n", sl->len, sl->bol, c_reset);
 620                 }
 621         }
 622 }
 623
 624 static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 625                                int i, int j)
 626 {
 627         /* We have already examined parent j and we know parent i
 628          * and parent j are the same, so reuse the combined result
 629          * of parent j for parent i.
 630          */
 631         unsigned long lno, imask, jmask;
 632         imask = (1UL<<i);
 633         jmask = (1UL<<j);
 634
 635         for (lno = 0; lno <= cnt; lno++) {
 636                 struct lline *ll = sline->lost_head;
 637                 sline->p_lno[i] = sline->p_lno[j];
 638                 while (ll) {
 639                         if (ll->parent_map & jmask)
 640                                 ll->parent_map |= imask;
 641                         ll = ll->next;
 642                 }
 643                 if (sline->flag & jmask)
 644                         sline->flag |= imask;
 645                 sline++;
 646         }
 647         /* the overall size of the file (sline[cnt]) */
 648         sline->p_lno[i] = sline->p_lno[j];
 649 }
 650
 651 static void dump_quoted_path(const char *head,
 652                              const char *prefix,
 653                              const char *path,
 654                              const char *c_meta, const char *c_reset)
 655 {
 656         static struct strbuf buf = STRBUF_INIT;
 657
 658         strbuf_reset(&buf);
 659         strbuf_addstr(&buf, c_meta);
 660         strbuf_addstr(&buf, head);
 661         quote_two_c_style(&buf, prefix, path, 0);
 662         strbuf_addstr(&buf, c_reset);
 663         puts(buf.buf);
 664 }
 665
 666 static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 667                             int dense, struct rev_info *rev)
 668 {
 669         struct diff_options *opt = &rev->diffopt;
 670         unsigned long result_size, cnt, lno;
 671         char *result, *cp;
 672         struct sline *sline; /* survived lines */
 673         int mode_differs = 0;
 674         int i, show_hunks;
 675         int working_tree_file = is_null_sha1(elem->sha1);
 676         int abbrev = DIFF_OPT_TST(opt, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
 677         mmfile_t result_file;
 678
 679         context = opt->context;
 680         /* Read the result of merge first */
 681         if (!working_tree_file)
 682                 result = grab_blob(elem->sha1, &result_size);
 683         else {
 684                 /* Used by diff-tree to read from the working tree */
 685                 struct stat st;
 686                 int fd = -1;
 687
 688                 if (lstat(elem->path, &st) < 0)
 689                         goto deleted_file;
 690
 691                 if (S_ISLNK(st.st_mode)) {
 692                         size_t len = xsize_t(st.st_size);
 693                         result_size = len;
 694                         result = xmalloc(len + 1);
 695                         if (result_size != readlink(elem->path, result, len)) {
 696                                 error("readlink(%s): %s", elem->path,
 697                                       strerror(errno));
 698                                 return;
 699                         }
 700                         result[len] = 0;
 701                         elem->mode = canon_mode(st.st_mode);
 702                 }
 703                 else if (0 <= (fd = open(elem->path, O_RDONLY)) &&
 704                          !fstat(fd, &st)) {
 705                         size_t len = xsize_t(st.st_size);
 706                         ssize_t done;
 707                         int is_file, i;
 708
 709                         elem->mode = canon_mode(st.st_mode);
 710                         /* if symlinks don't work, assume symlink if all parents
 711                          * are symlinks
 712                          */
 713                         is_file = has_symlinks;
 714                         for (i = 0; !is_file && i < num_parent; i++)
 715                                 is_file = !S_ISLNK(elem->parent[i].mode);
 716                         if (!is_file)
 717                                 elem->mode = canon_mode(S_IFLNK);
 718
 719                         result_size = len;
 720                         result = xmalloc(len + 1);
 721
 722                         done = read_in_full(fd, result, len);
 723                         if (done < 0)
 724                                 die("read error '%s'", elem->path);
 725                         else if (done < len)
 726                                 die("early EOF '%s'", elem->path);
 727
 728                         result[len] = 0;
 729                 }
 730                 else {
 731                 deleted_file:
 732                         result_size = 0;
 733                         elem->mode = 0;
 734                         result = xcalloc(1, 1);
 735                 }
 736
 737                 if (0 <= fd)
 738                         close(fd);
 739         }
 740
 741         for (cnt = 0, cp = result; cp < result + result_size; cp++) {
 742                 if (*cp == '\n')
 743                         cnt++;
 744         }
 745         if (result_size && result[result_size-1] != '\n')
 746                 cnt++; /* incomplete line */
 747
 748         sline = xcalloc(cnt+2, sizeof(*sline));
 749         sline[0].bol = result;
 750         for (lno = 0; lno <= cnt + 1; lno++) {
 751                 sline[lno].lost_tail = &sline[lno].lost_head;
 752                 sline[lno].flag = 0;
 753         }
 754         for (lno = 0, cp = result; cp < result + result_size; cp++) {
 755                 if (*cp == '\n') {
 756                         sline[lno].len = cp - sline[lno].bol;
 757                         lno++;
 758                         if (lno < cnt)
 759                                 sline[lno].bol = cp + 1;
 760                 }
 761         }
 762         if (result_size && result[result_size-1] != '\n')
 763                 sline[cnt-1].len = result_size - (sline[cnt-1].bol - result);
 764
 765         result_file.ptr = result;
 766         result_file.size = result_size;
 767
 768         /* Even p_lno[cnt+1] is valid -- that is for the end line number
 769          * for deletion hunk at the end.
 770          */
 771         sline[0].p_lno = xcalloc((cnt+2) * num_parent, sizeof(unsigned long));
 772         for (lno = 0; lno <= cnt; lno++)
 773                 sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
 774
 775         for (i = 0; i < num_parent; i++) {
 776                 int j;
 777                 for (j = 0; j < i; j++) {
 778                         if (!hashcmp(elem->parent[i].sha1,
 779                                      elem->parent[j].sha1)) {
 780                                 reuse_combine_diff(sline, cnt, i, j);
 781                                 break;
 782                         }
 783                 }
 784                 if (i <= j)
 785                         combine_diff(elem->parent[i].sha1, &result_file, sline,
 786                                      cnt, i, num_parent);
 787                 if (elem->parent[i].mode != elem->mode)
 788                         mode_differs = 1;
 789         }
 790
 791         show_hunks = make_hunks(sline, cnt, num_parent, dense);
 792
 793         if (show_hunks || mode_differs || working_tree_file) {
 794                 const char *abb;
 795                 int use_color = DIFF_OPT_TST(opt, COLOR_DIFF);
 796                 const char *c_meta = diff_get_color(use_color, DIFF_METAINFO);
 797                 const char *c_reset = diff_get_color(use_color, DIFF_RESET);
 798                 int added = 0;
 799                 int deleted = 0;
 800
 801                 if (rev->loginfo && !rev->no_commit_id)
 802                         show_log(rev);
 803                 dump_quoted_path(dense ? "diff --cc " : "diff --combined ",
 804                                  "", elem->path, c_meta, c_reset);
 805                 printf("%sindex ", c_meta);
 806                 for (i = 0; i < num_parent; i++) {
 807                         abb = find_unique_abbrev(elem->parent[i].sha1,
 808                                                  abbrev);
 809                         printf("%s%s", i ? "," : "", abb);
 810                 }
 811                 abb = find_unique_abbrev(elem->sha1, abbrev);
 812                 printf("..%s%s\n", abb, c_reset);
 813
 814                 if (mode_differs) {
 815                         deleted = !elem->mode;
 816
 817                         /* We say it was added if nobody had it */
 818                         added = !deleted;
 819                         for (i = 0; added && i < num_parent; i++)
 820                                 if (elem->parent[i].status !=
 821                                     DIFF_STATUS_ADDED)
 822                                         added = 0;
 823                         if (added)
 824                                 printf("%snew file mode %06o",
 825                                        c_meta, elem->mode);
 826                         else {
 827                                 if (deleted)
 828                                         printf("%sdeleted file ", c_meta);
 829                                 printf("mode ");
 830                                 for (i = 0; i < num_parent; i++) {
 831                                         printf("%s%06o", i ? "," : "",
 832                                                elem->parent[i].mode);
 833                                 }
 834                                 if (elem->mode)
 835                                         printf("..%06o", elem->mode);
 836                         }
 837                         printf("%s\n", c_reset);
 838                 }
 839                 if (added)
 840                         dump_quoted_path("--- ", "", "/dev/null",
 841                                          c_meta, c_reset);
 842                 else
 843                         dump_quoted_path("--- ", opt->a_prefix, elem->path,
 844                                          c_meta, c_reset);
 845                 if (deleted)
 846                         dump_quoted_path("+++ ", "", "/dev/null",
 847                                          c_meta, c_reset);
 848                 else
 849                         dump_quoted_path("+++ ", opt->b_prefix, elem->path,
 850                                          c_meta, c_reset);
 851                 dump_sline(sline, cnt, num_parent,
 852                            DIFF_OPT_TST(opt, COLOR_DIFF));
 853         }
 854         free(result);
 855
 856         for (lno = 0; lno < cnt; lno++) {
 857                 if (sline[lno].lost_head) {
 858                         struct lline *ll = sline[lno].lost_head;
 859                         while (ll) {
 860                                 struct lline *tmp = ll;
 861                                 ll = ll->next;
 862                                 free(tmp);
 863                         }
 864                 }
 865         }
 866         free(sline[0].p_lno);
 867         free(sline);
 868 }
 869
 870 #define COLONS "::::::::::::::::::::::::::::::::"
 871
 872 static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct rev_info *rev)
 873 {
 874         struct diff_options *opt = &rev->diffopt;
 875         int i, offset;
 876         const char *prefix;
 877         int line_termination, inter_name_termination;
 878
 879         line_termination = opt->line_termination;
 880         inter_name_termination = '\t';
 881         if (!line_termination)
 882                 inter_name_termination = 0;
 883
 884         if (rev->loginfo && !rev->no_commit_id)
 885                 show_log(rev);
 886
 887         if (opt->output_format & DIFF_FORMAT_RAW) {
 888                 offset = strlen(COLONS) - num_parent;
 889                 if (offset < 0)
 890                         offset = 0;
 891                 prefix = COLONS + offset;
 892
 893                 /* Show the modes */
 894                 for (i = 0; i < num_parent; i++) {
 895                         printf("%s%06o", prefix, p->parent[i].mode);
 896                         prefix = " ";
 897                 }
 898                 printf("%s%06o", prefix, p->mode);
 899
 900                 /* Show sha1's */
 901                 for (i = 0; i < num_parent; i++)
 902                         printf(" %s", diff_unique_abbrev(p->parent[i].sha1,
 903                                                          opt->abbrev));
 904                 printf(" %s ", diff_unique_abbrev(p->sha1, opt->abbrev));
 905         }
 906
 907         if (opt->output_format & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS)) {
 908                 for (i = 0; i < num_parent; i++)
 909                         putchar(p->parent[i].status);
 910                 putchar(inter_name_termination);
 911         }
 912
 913         write_name_quoted(p->path, stdout, line_termination);
 914 }
 915
 916 void show_combined_diff(struct combine_diff_path *p,
 917                        int num_parent,
 918                        int dense,
 919                        struct rev_info *rev)
 920 {
 921         struct diff_options *opt = &rev->diffopt;
 922         if (!p->len)
 923                 return;
 924         if (opt->output_format & (DIFF_FORMAT_RAW |
 925                                   DIFF_FORMAT_NAME |
 926                                   DIFF_FORMAT_NAME_STATUS))
 927                 show_raw_diff(p, num_parent, rev);
 928         else if (opt->output_format & DIFF_FORMAT_PATCH)
 929                 show_patch_diff(p, num_parent, dense, rev);
 930 }
 931
 932 void diff_tree_combined(const unsigned char *sha1,
 933                         const unsigned char parent[][20],
 934                         int num_parent,
 935                         int dense,
 936                         struct rev_info *rev)
 937 {
 938         struct diff_options *opt = &rev->diffopt;
 939         struct diff_options diffopts;
 940         struct combine_diff_path *p, *paths = NULL;
 941         int i, num_paths, needsep, show_log_first;
 942
 943         diffopts = *opt;
 944         diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
 945         DIFF_OPT_SET(&diffopts, RECURSIVE);
 946         DIFF_OPT_CLR(&diffopts, ALLOW_EXTERNAL);
 947
 948         show_log_first = !!rev->loginfo && !rev->no_commit_id;
 949         needsep = 0;
 950         /* find set of paths that everybody touches */
 951         for (i = 0; i < num_parent; i++) {
 952                 /* show stat against the first parent even
 953                  * when doing combined diff.
 954                  */
 955                 int stat_opt = (opt->output_format &
 956                                 (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT));
 957                 if (i == 0 && stat_opt)
 958                         diffopts.output_format = stat_opt;
 959                 else
 960                         diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
 961                 diff_tree_sha1(parent[i], sha1, "", &diffopts);
 962                 diffcore_std(&diffopts);
 963                 paths = intersect_paths(paths, i, num_parent);
 964
 965                 if (show_log_first && i == 0) {
 966                         show_log(rev);
 967                         if (rev->verbose_header && opt->output_format)
 968                                 putchar(opt->line_termination);
 969                 }
 970                 diff_flush(&diffopts);
 971         }
 972
 973         /* find out surviving paths */
 974         for (num_paths = 0, p = paths; p; p = p->next) {
 975                 if (p->len)
 976                         num_paths++;
 977         }
 978         if (num_paths) {
 979                 if (opt->output_format & (DIFF_FORMAT_RAW |
 980                                           DIFF_FORMAT_NAME |
 981                                           DIFF_FORMAT_NAME_STATUS)) {
 982                         for (p = paths; p; p = p->next) {
 983                                 if (p->len)
 984                                         show_raw_diff(p, num_parent, rev);
 985                         }
 986                         needsep = 1;
 987                 }
 988                 else if (opt->output_format &
 989                          (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT))
 990                         needsep = 1;
 991                 if (opt->output_format & DIFF_FORMAT_PATCH) {
 992                         if (needsep)
 993                                 putchar(opt->line_termination);
 994                         for (p = paths; p; p = p->next) {
 995                                 if (p->len)
 996                                         show_patch_diff(p, num_parent, dense,
 997                                                         rev);
 998                         }
 999                 }
1000         }
1001
1002         /* Clean things up */
1003         while (paths) {
1004                 struct combine_diff_path *tmp = paths;
1005                 paths = paths->next;
1006                 free(tmp);
1007         }
1008 }
1009
1010 void diff_tree_combined_merge(const unsigned char *sha1,
1011                              int dense, struct rev_info *rev)
1012 {
1013         int num_parent;
1014         const unsigned char (*parent)[20];
1015         struct commit *commit = lookup_commit(sha1);
1016         struct commit_list *parents;
1017
1018         /* count parents */
1019         for (parents = commit->parents, num_parent = 0;
1020              parents;
1021              parents = parents->next, num_parent++)
1022                 ; /* nothing */
1023
1024         parent = xmalloc(num_parent * sizeof(*parent));
1025         for (parents = commit->parents, num_parent = 0;
1026              parents;
1027              parents = parents->next, num_parent++)
1028                 hashcpy((unsigned char*)(parent + num_parent),
1029                         parents->item->object.sha1);
1030         diff_tree_combined(sha1, parent, num_parent, dense, rev);
1031 }