combine-diff.con commit glossary: improve description of SHA-1 related topics (3ab5012)
   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#include "refs.h"
  10#include "userdiff.h"
  11#include "sha1-array.h"
  12
  13static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr, int n, int num_parent)
  14{
  15        struct diff_queue_struct *q = &diff_queued_diff;
  16        struct combine_diff_path *p;
  17        int i;
  18
  19        if (!n) {
  20                struct combine_diff_path *list = NULL, **tail = &list;
  21                for (i = 0; i < q->nr; i++) {
  22                        int len;
  23                        const char *path;
  24                        if (diff_unmodified_pair(q->queue[i]))
  25                                continue;
  26                        path = q->queue[i]->two->path;
  27                        len = strlen(path);
  28                        p = xmalloc(combine_diff_path_size(num_parent, len));
  29                        p->path = (char *) &(p->parent[num_parent]);
  30                        memcpy(p->path, path, len);
  31                        p->path[len] = 0;
  32                        p->len = len;
  33                        p->next = NULL;
  34                        memset(p->parent, 0,
  35                               sizeof(p->parent[0]) * num_parent);
  36
  37                        hashcpy(p->sha1, q->queue[i]->two->sha1);
  38                        p->mode = q->queue[i]->two->mode;
  39                        hashcpy(p->parent[n].sha1, q->queue[i]->one->sha1);
  40                        p->parent[n].mode = q->queue[i]->one->mode;
  41                        p->parent[n].status = q->queue[i]->status;
  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 (diff_unmodified_pair(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                                hashcpy(p->parent[n].sha1, q->queue[i]->one->sha1);
  63                                p->parent[n].mode = q->queue[i]->one->mode;
  64                                p->parent[n].status = q->queue[i]->status;
  65                                break;
  66                        }
  67                }
  68                if (!found)
  69                        p->len = 0;
  70        }
  71        return curr;
  72}
  73
  74/* Lines lost from parent */
  75struct 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 */
  83struct sline {
  84        struct lline *lost_head, **lost_tail;
  85        struct lline *next_lost;
  86        char *bol;
  87        int len;
  88        /* bit 0 up to (N-1) are on if the parent has this line (i.e.
  89         * we did not change it).
  90         * bit N is used for "interesting" lines, including context.
  91         * bit (N+1) is used for "do not show deletion before this".
  92         */
  93        unsigned long flag;
  94        unsigned long *p_lno;
  95};
  96
  97static char *grab_blob(const unsigned char *sha1, unsigned int mode,
  98                       unsigned long *size, struct userdiff_driver *textconv,
  99                       const char *path)
 100{
 101        char *blob;
 102        enum object_type type;
 103
 104        if (S_ISGITLINK(mode)) {
 105                blob = xmalloc(100);
 106                *size = snprintf(blob, 100,
 107                                 "Subproject commit %s\n", sha1_to_hex(sha1));
 108        } else if (is_null_sha1(sha1)) {
 109                /* deleted blob */
 110                *size = 0;
 111                return xcalloc(1, 1);
 112        } else if (textconv) {
 113                struct diff_filespec *df = alloc_filespec(path);
 114                fill_filespec(df, sha1, 1, mode);
 115                *size = fill_textconv(textconv, df, &blob);
 116                free_filespec(df);
 117        } else {
 118                blob = read_sha1_file(sha1, &type, size);
 119                if (type != OBJ_BLOB)
 120                        die("object '%s' is not a blob!", sha1_to_hex(sha1));
 121        }
 122        return blob;
 123}
 124
 125static void append_lost(struct sline *sline, int n, const char *line, int len)
 126{
 127        struct lline *lline;
 128        unsigned long this_mask = (1UL<<n);
 129        if (line[len-1] == '\n')
 130                len--;
 131
 132        /* Check to see if we can squash things */
 133        if (sline->lost_head) {
 134                lline = sline->next_lost;
 135                while (lline) {
 136                        if (lline->len == len &&
 137                            !memcmp(lline->line, line, len)) {
 138                                lline->parent_map |= this_mask;
 139                                sline->next_lost = lline->next;
 140                                return;
 141                        }
 142                        lline = lline->next;
 143                }
 144        }
 145
 146        lline = xmalloc(sizeof(*lline) + len + 1);
 147        lline->len = len;
 148        lline->next = NULL;
 149        lline->parent_map = this_mask;
 150        memcpy(lline->line, line, len);
 151        lline->line[len] = 0;
 152        *sline->lost_tail = lline;
 153        sline->lost_tail = &lline->next;
 154        sline->next_lost = NULL;
 155}
 156
 157struct combine_diff_state {
 158        unsigned int lno;
 159        int ob, on, nb, nn;
 160        unsigned long nmask;
 161        int num_parent;
 162        int n;
 163        struct sline *sline;
 164        struct sline *lost_bucket;
 165};
 166
 167static void consume_line(void *state_, char *line, unsigned long len)
 168{
 169        struct combine_diff_state *state = state_;
 170        if (5 < len && !memcmp("@@ -", line, 4)) {
 171                if (parse_hunk_header(line, len,
 172                                      &state->ob, &state->on,
 173                                      &state->nb, &state->nn))
 174                        return;
 175                state->lno = state->nb;
 176                if (state->nn == 0) {
 177                        /* @@ -X,Y +N,0 @@ removed Y lines
 178                         * that would have come *after* line N
 179                         * in the result.  Our lost buckets hang
 180                         * to the line after the removed lines,
 181                         *
 182                         * Note that this is correct even when N == 0,
 183                         * in which case the hunk removes the first
 184                         * line in the file.
 185                         */
 186                        state->lost_bucket = &state->sline[state->nb];
 187                        if (!state->nb)
 188                                state->nb = 1;
 189                } else {
 190                        state->lost_bucket = &state->sline[state->nb-1];
 191                }
 192                if (!state->sline[state->nb-1].p_lno)
 193                        state->sline[state->nb-1].p_lno =
 194                                xcalloc(state->num_parent,
 195                                        sizeof(unsigned long));
 196                state->sline[state->nb-1].p_lno[state->n] = state->ob;
 197                state->lost_bucket->next_lost = state->lost_bucket->lost_head;
 198                return;
 199        }
 200        if (!state->lost_bucket)
 201                return; /* not in any hunk yet */
 202        switch (line[0]) {
 203        case '-':
 204                append_lost(state->lost_bucket, state->n, line+1, len-1);
 205                break;
 206        case '+':
 207                state->sline[state->lno-1].flag |= state->nmask;
 208                state->lno++;
 209                break;
 210        }
 211}
 212
 213static void combine_diff(const unsigned char *parent, unsigned int mode,
 214                         mmfile_t *result_file,
 215                         struct sline *sline, unsigned int cnt, int n,
 216                         int num_parent, int result_deleted,
 217                         struct userdiff_driver *textconv,
 218                         const char *path)
 219{
 220        unsigned int p_lno, lno;
 221        unsigned long nmask = (1UL << n);
 222        xpparam_t xpp;
 223        xdemitconf_t xecfg;
 224        mmfile_t parent_file;
 225        struct combine_diff_state state;
 226        unsigned long sz;
 227
 228        if (result_deleted)
 229                return; /* result deleted */
 230
 231        parent_file.ptr = grab_blob(parent, mode, &sz, textconv, path);
 232        parent_file.size = sz;
 233        memset(&xpp, 0, sizeof(xpp));
 234        xpp.flags = 0;
 235        memset(&xecfg, 0, sizeof(xecfg));
 236        memset(&state, 0, sizeof(state));
 237        state.nmask = nmask;
 238        state.sline = sline;
 239        state.lno = 1;
 240        state.num_parent = num_parent;
 241        state.n = n;
 242
 243        xdi_diff_outf(&parent_file, result_file, consume_line, &state,
 244                      &xpp, &xecfg);
 245        free(parent_file.ptr);
 246
 247        /* Assign line numbers for this parent.
 248         *
 249         * sline[lno].p_lno[n] records the first line number
 250         * (counting from 1) for parent N if the final hunk display
 251         * started by showing sline[lno] (possibly showing the lost
 252         * lines attached to it first).
 253         */
 254        for (lno = 0,  p_lno = 1; lno <= cnt; lno++) {
 255                struct lline *ll;
 256                sline[lno].p_lno[n] = p_lno;
 257
 258                /* How many lines would this sline advance the p_lno? */
 259                ll = sline[lno].lost_head;
 260                while (ll) {
 261                        if (ll->parent_map & nmask)
 262                                p_lno++; /* '-' means parent had it */
 263                        ll = ll->next;
 264                }
 265                if (lno < cnt && !(sline[lno].flag & nmask))
 266                        p_lno++; /* no '+' means parent had it */
 267        }
 268        sline[lno].p_lno[n] = p_lno; /* trailer */
 269}
 270
 271static unsigned long context = 3;
 272static char combine_marker = '@';
 273
 274static int interesting(struct sline *sline, unsigned long all_mask)
 275{
 276        /* If some parents lost lines here, or if we have added to
 277         * some parent, it is interesting.
 278         */
 279        return ((sline->flag & all_mask) || sline->lost_head);
 280}
 281
 282static unsigned long adjust_hunk_tail(struct sline *sline,
 283                                      unsigned long all_mask,
 284                                      unsigned long hunk_begin,
 285                                      unsigned long i)
 286{
 287        /* i points at the first uninteresting line.  If the last line
 288         * of the hunk was interesting only because it has some
 289         * deletion, then it is not all that interesting for the
 290         * purpose of giving trailing context lines.  This is because
 291         * we output '-' line and then unmodified sline[i-1] itself in
 292         * that case which gives us one extra context line.
 293         */
 294        if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
 295                i--;
 296        return i;
 297}
 298
 299static unsigned long find_next(struct sline *sline,
 300                               unsigned long mark,
 301                               unsigned long i,
 302                               unsigned long cnt,
 303                               int look_for_uninteresting)
 304{
 305        /* We have examined up to i-1 and are about to look at i.
 306         * Find next interesting or uninteresting line.  Here,
 307         * "interesting" does not mean interesting(), but marked by
 308         * the give_context() function below (i.e. it includes context
 309         * lines that are not interesting to interesting() function
 310         * that are surrounded by interesting() ones.
 311         */
 312        while (i <= cnt)
 313                if (look_for_uninteresting
 314                    ? !(sline[i].flag & mark)
 315                    : (sline[i].flag & mark))
 316                        return i;
 317                else
 318                        i++;
 319        return i;
 320}
 321
 322static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
 323{
 324        unsigned long all_mask = (1UL<<num_parent) - 1;
 325        unsigned long mark = (1UL<<num_parent);
 326        unsigned long no_pre_delete = (2UL<<num_parent);
 327        unsigned long i;
 328
 329        /* Two groups of interesting lines may have a short gap of
 330         * uninteresting lines.  Connect such groups to give them a
 331         * bit of context.
 332         *
 333         * We first start from what the interesting() function says,
 334         * and mark them with "mark", and paint context lines with the
 335         * mark.  So interesting() would still say false for such context
 336         * lines but they are treated as "interesting" in the end.
 337         */
 338        i = find_next(sline, mark, 0, cnt, 0);
 339        if (cnt < i)
 340                return 0;
 341
 342        while (i <= cnt) {
 343                unsigned long j = (context < i) ? (i - context) : 0;
 344                unsigned long k;
 345
 346                /* Paint a few lines before the first interesting line. */
 347                while (j < i)
 348                        sline[j++].flag |= mark | no_pre_delete;
 349
 350        again:
 351                /* we know up to i is to be included.  where does the
 352                 * next uninteresting one start?
 353                 */
 354                j = find_next(sline, mark, i, cnt, 1);
 355                if (cnt < j)
 356                        break; /* the rest are all interesting */
 357
 358                /* lookahead context lines */
 359                k = find_next(sline, mark, j, cnt, 0);
 360                j = adjust_hunk_tail(sline, all_mask, i, j);
 361
 362                if (k < j + context) {
 363                        /* k is interesting and [j,k) are not, but
 364                         * paint them interesting because the gap is small.
 365                         */
 366                        while (j < k)
 367                                sline[j++].flag |= mark;
 368                        i = k;
 369                        goto again;
 370                }
 371
 372                /* j is the first uninteresting line and there is
 373                 * no overlap beyond it within context lines.  Paint
 374                 * the trailing edge a bit.
 375                 */
 376                i = k;
 377                k = (j + context < cnt+1) ? j + context : cnt+1;
 378                while (j < k)
 379                        sline[j++].flag |= mark;
 380        }
 381        return 1;
 382}
 383
 384static int make_hunks(struct sline *sline, unsigned long cnt,
 385                       int num_parent, int dense)
 386{
 387        unsigned long all_mask = (1UL<<num_parent) - 1;
 388        unsigned long mark = (1UL<<num_parent);
 389        unsigned long i;
 390        int has_interesting = 0;
 391
 392        for (i = 0; i <= cnt; i++) {
 393                if (interesting(&sline[i], all_mask))
 394                        sline[i].flag |= mark;
 395                else
 396                        sline[i].flag &= ~mark;
 397        }
 398        if (!dense)
 399                return give_context(sline, cnt, num_parent);
 400
 401        /* Look at each hunk, and if we have changes from only one
 402         * parent, or the changes are the same from all but one
 403         * parent, mark that uninteresting.
 404         */
 405        i = 0;
 406        while (i <= cnt) {
 407                unsigned long j, hunk_begin, hunk_end;
 408                unsigned long same_diff;
 409                while (i <= cnt && !(sline[i].flag & mark))
 410                        i++;
 411                if (cnt < i)
 412                        break; /* No more interesting hunks */
 413                hunk_begin = i;
 414                for (j = i + 1; j <= cnt; j++) {
 415                        if (!(sline[j].flag & mark)) {
 416                                /* Look beyond the end to see if there
 417                                 * is an interesting line after this
 418                                 * hunk within context span.
 419                                 */
 420                                unsigned long la; /* lookahead */
 421                                int contin = 0;
 422                                la = adjust_hunk_tail(sline, all_mask,
 423                                                     hunk_begin, j);
 424                                la = (la + context < cnt + 1) ?
 425                                        (la + context) : cnt + 1;
 426                                while (la && j <= --la) {
 427                                        if (sline[la].flag & mark) {
 428                                                contin = 1;
 429                                                break;
 430                                        }
 431                                }
 432                                if (!contin)
 433                                        break;
 434                                j = la;
 435                        }
 436                }
 437                hunk_end = j;
 438
 439                /* [i..hunk_end) are interesting.  Now is it really
 440                 * interesting?  We check if there are only two versions
 441                 * and the result matches one of them.  That is, we look
 442                 * at:
 443                 *   (+) line, which records lines added to which parents;
 444                 *       this line appears in the result.
 445                 *   (-) line, which records from what parents the line
 446                 *       was removed; this line does not appear in the result.
 447                 * then check the set of parents the result has difference
 448                 * from, from all lines.  If there are lines that has
 449                 * different set of parents that the result has differences
 450                 * from, that means we have more than two versions.
 451                 *
 452                 * Even when we have only two versions, if the result does
 453                 * not match any of the parents, the it should be considered
 454                 * interesting.  In such a case, we would have all '+' line.
 455                 * After passing the above "two versions" test, that would
 456                 * appear as "the same set of parents" to be "all parents".
 457                 */
 458                same_diff = 0;
 459                has_interesting = 0;
 460                for (j = i; j < hunk_end && !has_interesting; j++) {
 461                        unsigned long this_diff = sline[j].flag & all_mask;
 462                        struct lline *ll = sline[j].lost_head;
 463                        if (this_diff) {
 464                                /* This has some changes.  Is it the
 465                                 * same as others?
 466                                 */
 467                                if (!same_diff)
 468                                        same_diff = this_diff;
 469                                else if (same_diff != this_diff) {
 470                                        has_interesting = 1;
 471                                        break;
 472                                }
 473                        }
 474                        while (ll && !has_interesting) {
 475                                /* Lost this line from these parents;
 476                                 * who are they?  Are they the same?
 477                                 */
 478                                this_diff = ll->parent_map;
 479                                if (!same_diff)
 480                                        same_diff = this_diff;
 481                                else if (same_diff != this_diff) {
 482                                        has_interesting = 1;
 483                                }
 484                                ll = ll->next;
 485                        }
 486                }
 487
 488                if (!has_interesting && same_diff != all_mask) {
 489                        /* This hunk is not that interesting after all */
 490                        for (j = hunk_begin; j < hunk_end; j++)
 491                                sline[j].flag &= ~mark;
 492                }
 493                i = hunk_end;
 494        }
 495
 496        has_interesting = give_context(sline, cnt, num_parent);
 497        return has_interesting;
 498}
 499
 500static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, int n, unsigned long null_context)
 501{
 502        l0 = sline[l0].p_lno[n];
 503        l1 = sline[l1].p_lno[n];
 504        printf(" -%lu,%lu", l0, l1-l0-null_context);
 505}
 506
 507static int hunk_comment_line(const char *bol)
 508{
 509        int ch;
 510
 511        if (!bol)
 512                return 0;
 513        ch = *bol & 0xff;
 514        return (isalpha(ch) || ch == '_' || ch == '$');
 515}
 516
 517static void show_line_to_eol(const char *line, int len, const char *reset)
 518{
 519        int saw_cr_at_eol = 0;
 520        if (len < 0)
 521                len = strlen(line);
 522        saw_cr_at_eol = (len && line[len-1] == '\r');
 523
 524        printf("%.*s%s%s\n", len - saw_cr_at_eol, line,
 525               reset,
 526               saw_cr_at_eol ? "\r" : "");
 527}
 528
 529static void dump_sline(struct sline *sline, const char *line_prefix,
 530                       unsigned long cnt, int num_parent,
 531                       int use_color, int result_deleted)
 532{
 533        unsigned long mark = (1UL<<num_parent);
 534        unsigned long no_pre_delete = (2UL<<num_parent);
 535        int i;
 536        unsigned long lno = 0;
 537        const char *c_frag = diff_get_color(use_color, DIFF_FRAGINFO);
 538        const char *c_func = diff_get_color(use_color, DIFF_FUNCINFO);
 539        const char *c_new = diff_get_color(use_color, DIFF_FILE_NEW);
 540        const char *c_old = diff_get_color(use_color, DIFF_FILE_OLD);
 541        const char *c_plain = diff_get_color(use_color, DIFF_PLAIN);
 542        const char *c_reset = diff_get_color(use_color, DIFF_RESET);
 543
 544        if (result_deleted)
 545                return; /* result deleted */
 546
 547        while (1) {
 548                unsigned long hunk_end;
 549                unsigned long rlines;
 550                const char *hunk_comment = NULL;
 551                unsigned long null_context = 0;
 552
 553                while (lno <= cnt && !(sline[lno].flag & mark)) {
 554                        if (hunk_comment_line(sline[lno].bol))
 555                                hunk_comment = sline[lno].bol;
 556                        lno++;
 557                }
 558                if (cnt < lno)
 559                        break;
 560                else {
 561                        for (hunk_end = lno + 1; hunk_end <= cnt; hunk_end++)
 562                                if (!(sline[hunk_end].flag & mark))
 563                                        break;
 564                }
 565                rlines = hunk_end - lno;
 566                if (cnt < hunk_end)
 567                        rlines--; /* pointing at the last delete hunk */
 568
 569                if (!context) {
 570                        /*
 571                         * Even when running with --unified=0, all
 572                         * lines in the hunk needs to be processed in
 573                         * the loop below in order to show the
 574                         * deletion recorded in lost_head.  However,
 575                         * we do not want to show the resulting line
 576                         * with all blank context markers in such a
 577                         * case.  Compensate.
 578                         */
 579                        unsigned long j;
 580                        for (j = lno; j < hunk_end; j++)
 581                                if (!(sline[j].flag & (mark-1)))
 582                                        null_context++;
 583                        rlines -= null_context;
 584                }
 585
 586                printf("%s%s", line_prefix, c_frag);
 587                for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 588                for (i = 0; i < num_parent; i++)
 589                        show_parent_lno(sline, lno, hunk_end, i, null_context);
 590                printf(" +%lu,%lu ", lno+1, rlines);
 591                for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 592
 593                if (hunk_comment) {
 594                        int comment_end = 0;
 595                        for (i = 0; i < 40; i++) {
 596                                int ch = hunk_comment[i] & 0xff;
 597                                if (!ch || ch == '\n')
 598                                        break;
 599                                if (!isspace(ch))
 600                                    comment_end = i;
 601                        }
 602                        if (comment_end)
 603                                printf("%s%s %s%s", c_reset,
 604                                                    c_plain, c_reset,
 605                                                    c_func);
 606                        for (i = 0; i < comment_end; i++)
 607                                putchar(hunk_comment[i]);
 608                }
 609
 610                printf("%s\n", c_reset);
 611                while (lno < hunk_end) {
 612                        struct lline *ll;
 613                        int j;
 614                        unsigned long p_mask;
 615                        struct sline *sl = &sline[lno++];
 616                        ll = (sl->flag & no_pre_delete) ? NULL : sl->lost_head;
 617                        while (ll) {
 618                                printf("%s%s", line_prefix, c_old);
 619                                for (j = 0; j < num_parent; j++) {
 620                                        if (ll->parent_map & (1UL<<j))
 621                                                putchar('-');
 622                                        else
 623                                                putchar(' ');
 624                                }
 625                                show_line_to_eol(ll->line, -1, c_reset);
 626                                ll = ll->next;
 627                        }
 628                        if (cnt < lno)
 629                                break;
 630                        p_mask = 1;
 631                        fputs(line_prefix, stdout);
 632                        if (!(sl->flag & (mark-1))) {
 633                                /*
 634                                 * This sline was here to hang the
 635                                 * lost lines in front of it.
 636                                 */
 637                                if (!context)
 638                                        continue;
 639                                fputs(c_plain, stdout);
 640                        }
 641                        else
 642                                fputs(c_new, stdout);
 643                        for (j = 0; j < num_parent; j++) {
 644                                if (p_mask & sl->flag)
 645                                        putchar('+');
 646                                else
 647                                        putchar(' ');
 648                                p_mask <<= 1;
 649                        }
 650                        show_line_to_eol(sl->bol, sl->len, c_reset);
 651                }
 652        }
 653}
 654
 655static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 656                               int i, int j)
 657{
 658        /* We have already examined parent j and we know parent i
 659         * and parent j are the same, so reuse the combined result
 660         * of parent j for parent i.
 661         */
 662        unsigned long lno, imask, jmask;
 663        imask = (1UL<<i);
 664        jmask = (1UL<<j);
 665
 666        for (lno = 0; lno <= cnt; lno++) {
 667                struct lline *ll = sline->lost_head;
 668                sline->p_lno[i] = sline->p_lno[j];
 669                while (ll) {
 670                        if (ll->parent_map & jmask)
 671                                ll->parent_map |= imask;
 672                        ll = ll->next;
 673                }
 674                if (sline->flag & jmask)
 675                        sline->flag |= imask;
 676                sline++;
 677        }
 678        /* the overall size of the file (sline[cnt]) */
 679        sline->p_lno[i] = sline->p_lno[j];
 680}
 681
 682static void dump_quoted_path(const char *head,
 683                             const char *prefix,
 684                             const char *path,
 685                             const char *line_prefix,
 686                             const char *c_meta, const char *c_reset)
 687{
 688        static struct strbuf buf = STRBUF_INIT;
 689
 690        strbuf_reset(&buf);
 691        strbuf_addstr(&buf, line_prefix);
 692        strbuf_addstr(&buf, c_meta);
 693        strbuf_addstr(&buf, head);
 694        quote_two_c_style(&buf, prefix, path, 0);
 695        strbuf_addstr(&buf, c_reset);
 696        puts(buf.buf);
 697}
 698
 699static void show_combined_header(struct combine_diff_path *elem,
 700                                 int num_parent,
 701                                 int dense,
 702                                 struct rev_info *rev,
 703                                 const char *line_prefix,
 704                                 int mode_differs,
 705                                 int show_file_header)
 706{
 707        struct diff_options *opt = &rev->diffopt;
 708        int abbrev = DIFF_OPT_TST(opt, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
 709        const char *a_prefix = opt->a_prefix ? opt->a_prefix : "a/";
 710        const char *b_prefix = opt->b_prefix ? opt->b_prefix : "b/";
 711        const char *c_meta = diff_get_color_opt(opt, DIFF_METAINFO);
 712        const char *c_reset = diff_get_color_opt(opt, DIFF_RESET);
 713        const char *abb;
 714        int added = 0;
 715        int deleted = 0;
 716        int i;
 717
 718        if (rev->loginfo && !rev->no_commit_id)
 719                show_log(rev);
 720
 721        dump_quoted_path(dense ? "diff --cc " : "diff --combined ",
 722                         "", elem->path, line_prefix, c_meta, c_reset);
 723        printf("%s%sindex ", line_prefix, c_meta);
 724        for (i = 0; i < num_parent; i++) {
 725                abb = find_unique_abbrev(elem->parent[i].sha1,
 726                                         abbrev);
 727                printf("%s%s", i ? "," : "", abb);
 728        }
 729        abb = find_unique_abbrev(elem->sha1, abbrev);
 730        printf("..%s%s\n", abb, c_reset);
 731
 732        if (mode_differs) {
 733                deleted = !elem->mode;
 734
 735                /* We say it was added if nobody had it */
 736                added = !deleted;
 737                for (i = 0; added && i < num_parent; i++)
 738                        if (elem->parent[i].status !=
 739                            DIFF_STATUS_ADDED)
 740                                added = 0;
 741                if (added)
 742                        printf("%s%snew file mode %06o",
 743                               line_prefix, c_meta, elem->mode);
 744                else {
 745                        if (deleted)
 746                                printf("%s%sdeleted file ",
 747                                       line_prefix, c_meta);
 748                        printf("mode ");
 749                        for (i = 0; i < num_parent; i++) {
 750                                printf("%s%06o", i ? "," : "",
 751                                       elem->parent[i].mode);
 752                        }
 753                        if (elem->mode)
 754                                printf("..%06o", elem->mode);
 755                }
 756                printf("%s\n", c_reset);
 757        }
 758
 759        if (!show_file_header)
 760                return;
 761
 762        if (added)
 763                dump_quoted_path("--- ", "", "/dev/null",
 764                                 line_prefix, c_meta, c_reset);
 765        else
 766                dump_quoted_path("--- ", a_prefix, elem->path,
 767                                 line_prefix, c_meta, c_reset);
 768        if (deleted)
 769                dump_quoted_path("+++ ", "", "/dev/null",
 770                                 line_prefix, c_meta, c_reset);
 771        else
 772                dump_quoted_path("+++ ", b_prefix, elem->path,
 773                                 line_prefix, c_meta, c_reset);
 774}
 775
 776static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 777                            int dense, int working_tree_file,
 778                            struct rev_info *rev)
 779{
 780        struct diff_options *opt = &rev->diffopt;
 781        unsigned long result_size, cnt, lno;
 782        int result_deleted = 0;
 783        char *result, *cp;
 784        struct sline *sline; /* survived lines */
 785        int mode_differs = 0;
 786        int i, show_hunks;
 787        mmfile_t result_file;
 788        struct userdiff_driver *userdiff;
 789        struct userdiff_driver *textconv = NULL;
 790        int is_binary;
 791        const char *line_prefix = diff_line_prefix(opt);
 792
 793        context = opt->context;
 794        userdiff = userdiff_find_by_path(elem->path);
 795        if (!userdiff)
 796                userdiff = userdiff_find_by_name("default");
 797        if (DIFF_OPT_TST(opt, ALLOW_TEXTCONV))
 798                textconv = userdiff_get_textconv(userdiff);
 799
 800        /* Read the result of merge first */
 801        if (!working_tree_file)
 802                result = grab_blob(elem->sha1, elem->mode, &result_size,
 803                                   textconv, elem->path);
 804        else {
 805                /* Used by diff-tree to read from the working tree */
 806                struct stat st;
 807                int fd = -1;
 808
 809                if (lstat(elem->path, &st) < 0)
 810                        goto deleted_file;
 811
 812                if (S_ISLNK(st.st_mode)) {
 813                        struct strbuf buf = STRBUF_INIT;
 814
 815                        if (strbuf_readlink(&buf, elem->path, st.st_size) < 0) {
 816                                error("readlink(%s): %s", elem->path,
 817                                      strerror(errno));
 818                                return;
 819                        }
 820                        result_size = buf.len;
 821                        result = strbuf_detach(&buf, NULL);
 822                        elem->mode = canon_mode(st.st_mode);
 823                } else if (S_ISDIR(st.st_mode)) {
 824                        unsigned char sha1[20];
 825                        if (resolve_gitlink_ref(elem->path, "HEAD", sha1) < 0)
 826                                result = grab_blob(elem->sha1, elem->mode,
 827                                                   &result_size, NULL, NULL);
 828                        else
 829                                result = grab_blob(sha1, elem->mode,
 830                                                   &result_size, NULL, NULL);
 831                } else if (textconv) {
 832                        struct diff_filespec *df = alloc_filespec(elem->path);
 833                        fill_filespec(df, null_sha1, 0, st.st_mode);
 834                        result_size = fill_textconv(textconv, df, &result);
 835                        free_filespec(df);
 836                } else if (0 <= (fd = open(elem->path, O_RDONLY))) {
 837                        size_t len = xsize_t(st.st_size);
 838                        ssize_t done;
 839                        int is_file, i;
 840
 841                        elem->mode = canon_mode(st.st_mode);
 842                        /* if symlinks don't work, assume symlink if all parents
 843                         * are symlinks
 844                         */
 845                        is_file = has_symlinks;
 846                        for (i = 0; !is_file && i < num_parent; i++)
 847                                is_file = !S_ISLNK(elem->parent[i].mode);
 848                        if (!is_file)
 849                                elem->mode = canon_mode(S_IFLNK);
 850
 851                        result_size = len;
 852                        result = xmalloc(len + 1);
 853
 854                        done = read_in_full(fd, result, len);
 855                        if (done < 0)
 856                                die_errno("read error '%s'", elem->path);
 857                        else if (done < len)
 858                                die("early EOF '%s'", elem->path);
 859
 860                        result[len] = 0;
 861
 862                        /* If not a fake symlink, apply filters, e.g. autocrlf */
 863                        if (is_file) {
 864                                struct strbuf buf = STRBUF_INIT;
 865
 866                                if (convert_to_git(elem->path, result, len, &buf, safe_crlf)) {
 867                                        free(result);
 868                                        result = strbuf_detach(&buf, &len);
 869                                        result_size = len;
 870                                }
 871                        }
 872                }
 873                else {
 874                deleted_file:
 875                        result_deleted = 1;
 876                        result_size = 0;
 877                        elem->mode = 0;
 878                        result = xcalloc(1, 1);
 879                }
 880
 881                if (0 <= fd)
 882                        close(fd);
 883        }
 884
 885        for (i = 0; i < num_parent; i++) {
 886                if (elem->parent[i].mode != elem->mode) {
 887                        mode_differs = 1;
 888                        break;
 889                }
 890        }
 891
 892        if (textconv)
 893                is_binary = 0;
 894        else if (userdiff->binary != -1)
 895                is_binary = userdiff->binary;
 896        else {
 897                is_binary = buffer_is_binary(result, result_size);
 898                for (i = 0; !is_binary && i < num_parent; i++) {
 899                        char *buf;
 900                        unsigned long size;
 901                        buf = grab_blob(elem->parent[i].sha1,
 902                                        elem->parent[i].mode,
 903                                        &size, NULL, NULL);
 904                        if (buffer_is_binary(buf, size))
 905                                is_binary = 1;
 906                        free(buf);
 907                }
 908        }
 909        if (is_binary) {
 910                show_combined_header(elem, num_parent, dense, rev,
 911                                     line_prefix, mode_differs, 0);
 912                printf("Binary files differ\n");
 913                free(result);
 914                return;
 915        }
 916
 917        for (cnt = 0, cp = result; cp < result + result_size; cp++) {
 918                if (*cp == '\n')
 919                        cnt++;
 920        }
 921        if (result_size && result[result_size-1] != '\n')
 922                cnt++; /* incomplete line */
 923
 924        sline = xcalloc(cnt+2, sizeof(*sline));
 925        sline[0].bol = result;
 926        for (lno = 0; lno <= cnt + 1; lno++) {
 927                sline[lno].lost_tail = &sline[lno].lost_head;
 928                sline[lno].flag = 0;
 929        }
 930        for (lno = 0, cp = result; cp < result + result_size; cp++) {
 931                if (*cp == '\n') {
 932                        sline[lno].len = cp - sline[lno].bol;
 933                        lno++;
 934                        if (lno < cnt)
 935                                sline[lno].bol = cp + 1;
 936                }
 937        }
 938        if (result_size && result[result_size-1] != '\n')
 939                sline[cnt-1].len = result_size - (sline[cnt-1].bol - result);
 940
 941        result_file.ptr = result;
 942        result_file.size = result_size;
 943
 944        /* Even p_lno[cnt+1] is valid -- that is for the end line number
 945         * for deletion hunk at the end.
 946         */
 947        sline[0].p_lno = xcalloc((cnt+2) * num_parent, sizeof(unsigned long));
 948        for (lno = 0; lno <= cnt; lno++)
 949                sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
 950
 951        for (i = 0; i < num_parent; i++) {
 952                int j;
 953                for (j = 0; j < i; j++) {
 954                        if (!hashcmp(elem->parent[i].sha1,
 955                                     elem->parent[j].sha1)) {
 956                                reuse_combine_diff(sline, cnt, i, j);
 957                                break;
 958                        }
 959                }
 960                if (i <= j)
 961                        combine_diff(elem->parent[i].sha1,
 962                                     elem->parent[i].mode,
 963                                     &result_file, sline,
 964                                     cnt, i, num_parent, result_deleted,
 965                                     textconv, elem->path);
 966        }
 967
 968        show_hunks = make_hunks(sline, cnt, num_parent, dense);
 969
 970        if (show_hunks || mode_differs || working_tree_file) {
 971                show_combined_header(elem, num_parent, dense, rev,
 972                                     line_prefix, mode_differs, 1);
 973                dump_sline(sline, line_prefix, cnt, num_parent,
 974                           opt->use_color, result_deleted);
 975        }
 976        free(result);
 977
 978        for (lno = 0; lno < cnt; lno++) {
 979                if (sline[lno].lost_head) {
 980                        struct lline *ll = sline[lno].lost_head;
 981                        while (ll) {
 982                                struct lline *tmp = ll;
 983                                ll = ll->next;
 984                                free(tmp);
 985                        }
 986                }
 987        }
 988        free(sline[0].p_lno);
 989        free(sline);
 990}
 991
 992static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct rev_info *rev)
 993{
 994        struct diff_options *opt = &rev->diffopt;
 995        int line_termination, inter_name_termination, i;
 996        const char *line_prefix = diff_line_prefix(opt);
 997
 998        line_termination = opt->line_termination;
 999        inter_name_termination = '\t';
1000        if (!line_termination)
1001                inter_name_termination = 0;
1002
1003        if (rev->loginfo && !rev->no_commit_id)
1004                show_log(rev);
1005
1006
1007        if (opt->output_format & DIFF_FORMAT_RAW) {
1008                printf("%s", line_prefix);
1009
1010                /* As many colons as there are parents */
1011                for (i = 0; i < num_parent; i++)
1012                        putchar(':');
1013
1014                /* Show the modes */
1015                for (i = 0; i < num_parent; i++)
1016                        printf("%06o ", p->parent[i].mode);
1017                printf("%06o", p->mode);
1018
1019                /* Show sha1's */
1020                for (i = 0; i < num_parent; i++)
1021                        printf(" %s", diff_unique_abbrev(p->parent[i].sha1,
1022                                                         opt->abbrev));
1023                printf(" %s ", diff_unique_abbrev(p->sha1, opt->abbrev));
1024        }
1025
1026        if (opt->output_format & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS)) {
1027                for (i = 0; i < num_parent; i++)
1028                        putchar(p->parent[i].status);
1029                putchar(inter_name_termination);
1030        }
1031
1032        write_name_quoted(p->path, stdout, line_termination);
1033}
1034
1035/*
1036 * The result (p->elem) is from the working tree and their
1037 * parents are typically from multiple stages during a merge
1038 * (i.e. diff-files) or the state in HEAD and in the index
1039 * (i.e. diff-index).
1040 */
1041void show_combined_diff(struct combine_diff_path *p,
1042                       int num_parent,
1043                       int dense,
1044                       struct rev_info *rev)
1045{
1046        struct diff_options *opt = &rev->diffopt;
1047
1048        if (!p->len)
1049                return;
1050        if (opt->output_format & (DIFF_FORMAT_RAW |
1051                                  DIFF_FORMAT_NAME |
1052                                  DIFF_FORMAT_NAME_STATUS))
1053                show_raw_diff(p, num_parent, rev);
1054        else if (opt->output_format & DIFF_FORMAT_PATCH)
1055                show_patch_diff(p, num_parent, dense, 1, rev);
1056}
1057
1058static void free_combined_pair(struct diff_filepair *pair)
1059{
1060        free(pair->two);
1061        free(pair);
1062}
1063
1064/*
1065 * A combine_diff_path expresses N parents on the LHS against 1 merge
1066 * result. Synthesize a diff_filepair that has N entries on the "one"
1067 * side and 1 entry on the "two" side.
1068 *
1069 * In the future, we might want to add more data to combine_diff_path
1070 * so that we can fill fields we are ignoring (most notably, size) here,
1071 * but currently nobody uses it, so this should suffice for now.
1072 */
1073static struct diff_filepair *combined_pair(struct combine_diff_path *p,
1074                                           int num_parent)
1075{
1076        int i;
1077        struct diff_filepair *pair;
1078        struct diff_filespec *pool;
1079
1080        pair = xmalloc(sizeof(*pair));
1081        pool = xcalloc(num_parent + 1, sizeof(struct diff_filespec));
1082        pair->one = pool + 1;
1083        pair->two = pool;
1084
1085        for (i = 0; i < num_parent; i++) {
1086                pair->one[i].path = p->path;
1087                pair->one[i].mode = p->parent[i].mode;
1088                hashcpy(pair->one[i].sha1, p->parent[i].sha1);
1089                pair->one[i].sha1_valid = !is_null_sha1(p->parent[i].sha1);
1090                pair->one[i].has_more_entries = 1;
1091        }
1092        pair->one[num_parent - 1].has_more_entries = 0;
1093
1094        pair->two->path = p->path;
1095        pair->two->mode = p->mode;
1096        hashcpy(pair->two->sha1, p->sha1);
1097        pair->two->sha1_valid = !is_null_sha1(p->sha1);
1098        return pair;
1099}
1100
1101static void handle_combined_callback(struct diff_options *opt,
1102                                     struct combine_diff_path *paths,
1103                                     int num_parent,
1104                                     int num_paths)
1105{
1106        struct combine_diff_path *p;
1107        struct diff_queue_struct q;
1108        int i;
1109
1110        q.queue = xcalloc(num_paths, sizeof(struct diff_filepair *));
1111        q.alloc = num_paths;
1112        q.nr = num_paths;
1113        for (i = 0, p = paths; p; p = p->next) {
1114                if (!p->len)
1115                        continue;
1116                q.queue[i++] = combined_pair(p, num_parent);
1117        }
1118        opt->format_callback(&q, opt, opt->format_callback_data);
1119        for (i = 0; i < num_paths; i++)
1120                free_combined_pair(q.queue[i]);
1121        free(q.queue);
1122}
1123
1124void diff_tree_combined(const unsigned char *sha1,
1125                        const struct sha1_array *parents,
1126                        int dense,
1127                        struct rev_info *rev)
1128{
1129        struct diff_options *opt = &rev->diffopt;
1130        struct diff_options diffopts;
1131        struct combine_diff_path *p, *paths = NULL;
1132        int i, num_paths, needsep, show_log_first, num_parent = parents->nr;
1133
1134        diffopts = *opt;
1135        diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
1136        DIFF_OPT_SET(&diffopts, RECURSIVE);
1137        DIFF_OPT_CLR(&diffopts, ALLOW_EXTERNAL);
1138
1139        show_log_first = !!rev->loginfo && !rev->no_commit_id;
1140        needsep = 0;
1141        /* find set of paths that everybody touches */
1142        for (i = 0; i < num_parent; i++) {
1143                /* show stat against the first parent even
1144                 * when doing combined diff.
1145                 */
1146                int stat_opt = (opt->output_format &
1147                                (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT));
1148                if (i == 0 && stat_opt)
1149                        diffopts.output_format = stat_opt;
1150                else
1151                        diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
1152                diff_tree_sha1(parents->sha1[i], sha1, "", &diffopts);
1153                diffcore_std(&diffopts);
1154                paths = intersect_paths(paths, i, num_parent);
1155
1156                if (show_log_first && i == 0) {
1157                        show_log(rev);
1158
1159                        if (rev->verbose_header && opt->output_format)
1160                                printf("%s%c", diff_line_prefix(opt),
1161                                       opt->line_termination);
1162                }
1163                diff_flush(&diffopts);
1164        }
1165
1166        /* find out surviving paths */
1167        for (num_paths = 0, p = paths; p; p = p->next) {
1168                if (p->len)
1169                        num_paths++;
1170        }
1171        if (num_paths) {
1172                if (opt->output_format & (DIFF_FORMAT_RAW |
1173                                          DIFF_FORMAT_NAME |
1174                                          DIFF_FORMAT_NAME_STATUS)) {
1175                        for (p = paths; p; p = p->next) {
1176                                if (p->len)
1177                                        show_raw_diff(p, num_parent, rev);
1178                        }
1179                        needsep = 1;
1180                }
1181                else if (opt->output_format &
1182                         (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT))
1183                        needsep = 1;
1184                else if (opt->output_format & DIFF_FORMAT_CALLBACK)
1185                        handle_combined_callback(opt, paths, num_parent, num_paths);
1186
1187                if (opt->output_format & DIFF_FORMAT_PATCH) {
1188                        if (needsep)
1189                                printf("%s%c", diff_line_prefix(opt),
1190                                       opt->line_termination);
1191                        for (p = paths; p; p = p->next) {
1192                                if (p->len)
1193                                        show_patch_diff(p, num_parent, dense,
1194                                                        0, rev);
1195                        }
1196                }
1197        }
1198
1199        /* Clean things up */
1200        while (paths) {
1201                struct combine_diff_path *tmp = paths;
1202                paths = paths->next;
1203                free(tmp);
1204        }
1205}
1206
1207void diff_tree_combined_merge(const struct commit *commit, int dense,
1208                              struct rev_info *rev)
1209{
1210        struct commit_list *parent = commit->parents;
1211        struct sha1_array parents = SHA1_ARRAY_INIT;
1212
1213        while (parent) {
1214                sha1_array_append(&parents, parent->item->object.sha1);
1215                parent = parent->next;
1216        }
1217        diff_tree_combined(commit->object.sha1, &parents, dense, rev);
1218        sha1_array_clear(&parents);
1219}