blame.con commit Merge branch 'rs/qsort-s' (bd40f41)
   1#include "cache.h"
   2#include "refs.h"
   3#include "cache-tree.h"
   4#include "mergesort.h"
   5#include "diff.h"
   6#include "diffcore.h"
   7#include "tag.h"
   8#include "blame.h"
   9
  10void blame_origin_decref(struct blame_origin *o)
  11{
  12        if (o && --o->refcnt <= 0) {
  13                struct blame_origin *p, *l = NULL;
  14                if (o->previous)
  15                        blame_origin_decref(o->previous);
  16                free(o->file.ptr);
  17                /* Should be present exactly once in commit chain */
  18                for (p = o->commit->util; p; l = p, p = p->next) {
  19                        if (p == o) {
  20                                if (l)
  21                                        l->next = p->next;
  22                                else
  23                                        o->commit->util = p->next;
  24                                free(o);
  25                                return;
  26                        }
  27                }
  28                die("internal error in blame_origin_decref");
  29        }
  30}
  31
  32/*
  33 * Given a commit and a path in it, create a new origin structure.
  34 * The callers that add blame to the scoreboard should use
  35 * get_origin() to obtain shared, refcounted copy instead of calling
  36 * this function directly.
  37 */
  38static struct blame_origin *make_origin(struct commit *commit, const char *path)
  39{
  40        struct blame_origin *o;
  41        FLEX_ALLOC_STR(o, path, path);
  42        o->commit = commit;
  43        o->refcnt = 1;
  44        o->next = commit->util;
  45        commit->util = o;
  46        return o;
  47}
  48
  49/*
  50 * Locate an existing origin or create a new one.
  51 * This moves the origin to front position in the commit util list.
  52 */
  53static struct blame_origin *get_origin(struct commit *commit, const char *path)
  54{
  55        struct blame_origin *o, *l;
  56
  57        for (o = commit->util, l = NULL; o; l = o, o = o->next) {
  58                if (!strcmp(o->path, path)) {
  59                        /* bump to front */
  60                        if (l) {
  61                                l->next = o->next;
  62                                o->next = commit->util;
  63                                commit->util = o;
  64                        }
  65                        return blame_origin_incref(o);
  66                }
  67        }
  68        return make_origin(commit, path);
  69}
  70
  71
  72
  73static void verify_working_tree_path(struct commit *work_tree, const char *path)
  74{
  75        struct commit_list *parents;
  76        int pos;
  77
  78        for (parents = work_tree->parents; parents; parents = parents->next) {
  79                const struct object_id *commit_oid = &parents->item->object.oid;
  80                struct object_id blob_oid;
  81                unsigned mode;
  82
  83                if (!get_tree_entry(commit_oid->hash, path, blob_oid.hash, &mode) &&
  84                    sha1_object_info(blob_oid.hash, NULL) == OBJ_BLOB)
  85                        return;
  86        }
  87
  88        pos = cache_name_pos(path, strlen(path));
  89        if (pos >= 0)
  90                ; /* path is in the index */
  91        else if (-1 - pos < active_nr &&
  92                 !strcmp(active_cache[-1 - pos]->name, path))
  93                ; /* path is in the index, unmerged */
  94        else
  95                die("no such path '%s' in HEAD", path);
  96}
  97
  98static struct commit_list **append_parent(struct commit_list **tail, const struct object_id *oid)
  99{
 100        struct commit *parent;
 101
 102        parent = lookup_commit_reference(oid);
 103        if (!parent)
 104                die("no such commit %s", oid_to_hex(oid));
 105        return &commit_list_insert(parent, tail)->next;
 106}
 107
 108static void append_merge_parents(struct commit_list **tail)
 109{
 110        int merge_head;
 111        struct strbuf line = STRBUF_INIT;
 112
 113        merge_head = open(git_path_merge_head(), O_RDONLY);
 114        if (merge_head < 0) {
 115                if (errno == ENOENT)
 116                        return;
 117                die("cannot open '%s' for reading", git_path_merge_head());
 118        }
 119
 120        while (!strbuf_getwholeline_fd(&line, merge_head, '\n')) {
 121                struct object_id oid;
 122                if (line.len < GIT_SHA1_HEXSZ || get_oid_hex(line.buf, &oid))
 123                        die("unknown line in '%s': %s", git_path_merge_head(), line.buf);
 124                tail = append_parent(tail, &oid);
 125        }
 126        close(merge_head);
 127        strbuf_release(&line);
 128}
 129
 130/*
 131 * This isn't as simple as passing sb->buf and sb->len, because we
 132 * want to transfer ownership of the buffer to the commit (so we
 133 * must use detach).
 134 */
 135static void set_commit_buffer_from_strbuf(struct commit *c, struct strbuf *sb)
 136{
 137        size_t len;
 138        void *buf = strbuf_detach(sb, &len);
 139        set_commit_buffer(c, buf, len);
 140}
 141
 142/*
 143 * Prepare a dummy commit that represents the work tree (or staged) item.
 144 * Note that annotating work tree item never works in the reverse.
 145 */
 146static struct commit *fake_working_tree_commit(struct diff_options *opt,
 147                                               const char *path,
 148                                               const char *contents_from)
 149{
 150        struct commit *commit;
 151        struct blame_origin *origin;
 152        struct commit_list **parent_tail, *parent;
 153        struct object_id head_oid;
 154        struct strbuf buf = STRBUF_INIT;
 155        const char *ident;
 156        time_t now;
 157        int size, len;
 158        struct cache_entry *ce;
 159        unsigned mode;
 160        struct strbuf msg = STRBUF_INIT;
 161
 162        read_cache();
 163        time(&now);
 164        commit = alloc_commit_node();
 165        commit->object.parsed = 1;
 166        commit->date = now;
 167        parent_tail = &commit->parents;
 168
 169        if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, head_oid.hash, NULL))
 170                die("no such ref: HEAD");
 171
 172        parent_tail = append_parent(parent_tail, &head_oid);
 173        append_merge_parents(parent_tail);
 174        verify_working_tree_path(commit, path);
 175
 176        origin = make_origin(commit, path);
 177
 178        ident = fmt_ident("Not Committed Yet", "not.committed.yet", NULL, 0);
 179        strbuf_addstr(&msg, "tree 0000000000000000000000000000000000000000\n");
 180        for (parent = commit->parents; parent; parent = parent->next)
 181                strbuf_addf(&msg, "parent %s\n",
 182                            oid_to_hex(&parent->item->object.oid));
 183        strbuf_addf(&msg,
 184                    "author %s\n"
 185                    "committer %s\n\n"
 186                    "Version of %s from %s\n",
 187                    ident, ident, path,
 188                    (!contents_from ? path :
 189                     (!strcmp(contents_from, "-") ? "standard input" : contents_from)));
 190        set_commit_buffer_from_strbuf(commit, &msg);
 191
 192        if (!contents_from || strcmp("-", contents_from)) {
 193                struct stat st;
 194                const char *read_from;
 195                char *buf_ptr;
 196                unsigned long buf_len;
 197
 198                if (contents_from) {
 199                        if (stat(contents_from, &st) < 0)
 200                                die_errno("Cannot stat '%s'", contents_from);
 201                        read_from = contents_from;
 202                }
 203                else {
 204                        if (lstat(path, &st) < 0)
 205                                die_errno("Cannot lstat '%s'", path);
 206                        read_from = path;
 207                }
 208                mode = canon_mode(st.st_mode);
 209
 210                switch (st.st_mode & S_IFMT) {
 211                case S_IFREG:
 212                        if (DIFF_OPT_TST(opt, ALLOW_TEXTCONV) &&
 213                            textconv_object(read_from, mode, &null_oid, 0, &buf_ptr, &buf_len))
 214                                strbuf_attach(&buf, buf_ptr, buf_len, buf_len + 1);
 215                        else if (strbuf_read_file(&buf, read_from, st.st_size) != st.st_size)
 216                                die_errno("cannot open or read '%s'", read_from);
 217                        break;
 218                case S_IFLNK:
 219                        if (strbuf_readlink(&buf, read_from, st.st_size) < 0)
 220                                die_errno("cannot readlink '%s'", read_from);
 221                        break;
 222                default:
 223                        die("unsupported file type %s", read_from);
 224                }
 225        }
 226        else {
 227                /* Reading from stdin */
 228                mode = 0;
 229                if (strbuf_read(&buf, 0, 0) < 0)
 230                        die_errno("failed to read from stdin");
 231        }
 232        convert_to_git(&the_index, path, buf.buf, buf.len, &buf, 0);
 233        origin->file.ptr = buf.buf;
 234        origin->file.size = buf.len;
 235        pretend_sha1_file(buf.buf, buf.len, OBJ_BLOB, origin->blob_oid.hash);
 236
 237        /*
 238         * Read the current index, replace the path entry with
 239         * origin->blob_sha1 without mucking with its mode or type
 240         * bits; we are not going to write this index out -- we just
 241         * want to run "diff-index --cached".
 242         */
 243        discard_cache();
 244        read_cache();
 245
 246        len = strlen(path);
 247        if (!mode) {
 248                int pos = cache_name_pos(path, len);
 249                if (0 <= pos)
 250                        mode = active_cache[pos]->ce_mode;
 251                else
 252                        /* Let's not bother reading from HEAD tree */
 253                        mode = S_IFREG | 0644;
 254        }
 255        size = cache_entry_size(len);
 256        ce = xcalloc(1, size);
 257        oidcpy(&ce->oid, &origin->blob_oid);
 258        memcpy(ce->name, path, len);
 259        ce->ce_flags = create_ce_flags(0);
 260        ce->ce_namelen = len;
 261        ce->ce_mode = create_ce_mode(mode);
 262        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
 263
 264        cache_tree_invalidate_path(&the_index, path);
 265
 266        return commit;
 267}
 268
 269
 270
 271static int diff_hunks(mmfile_t *file_a, mmfile_t *file_b,
 272                      xdl_emit_hunk_consume_func_t hunk_func, void *cb_data, int xdl_opts)
 273{
 274        xpparam_t xpp = {0};
 275        xdemitconf_t xecfg = {0};
 276        xdemitcb_t ecb = {NULL};
 277
 278        xpp.flags = xdl_opts;
 279        xecfg.hunk_func = hunk_func;
 280        ecb.priv = cb_data;
 281        return xdi_diff(file_a, file_b, &xpp, &xecfg, &ecb);
 282}
 283
 284/*
 285 * Given an origin, prepare mmfile_t structure to be used by the
 286 * diff machinery
 287 */
 288static void fill_origin_blob(struct diff_options *opt,
 289                             struct blame_origin *o, mmfile_t *file, int *num_read_blob)
 290{
 291        if (!o->file.ptr) {
 292                enum object_type type;
 293                unsigned long file_size;
 294
 295                (*num_read_blob)++;
 296                if (DIFF_OPT_TST(opt, ALLOW_TEXTCONV) &&
 297                    textconv_object(o->path, o->mode, &o->blob_oid, 1, &file->ptr, &file_size))
 298                        ;
 299                else
 300                        file->ptr = read_sha1_file(o->blob_oid.hash, &type,
 301                                                   &file_size);
 302                file->size = file_size;
 303
 304                if (!file->ptr)
 305                        die("Cannot read blob %s for path %s",
 306                            oid_to_hex(&o->blob_oid),
 307                            o->path);
 308                o->file = *file;
 309        }
 310        else
 311                *file = o->file;
 312}
 313
 314static void drop_origin_blob(struct blame_origin *o)
 315{
 316        if (o->file.ptr) {
 317                FREE_AND_NULL(o->file.ptr);
 318        }
 319}
 320
 321/*
 322 * Any merge of blames happens on lists of blames that arrived via
 323 * different parents in a single suspect.  In this case, we want to
 324 * sort according to the suspect line numbers as opposed to the final
 325 * image line numbers.  The function body is somewhat longish because
 326 * it avoids unnecessary writes.
 327 */
 328
 329static struct blame_entry *blame_merge(struct blame_entry *list1,
 330                                       struct blame_entry *list2)
 331{
 332        struct blame_entry *p1 = list1, *p2 = list2,
 333                **tail = &list1;
 334
 335        if (!p1)
 336                return p2;
 337        if (!p2)
 338                return p1;
 339
 340        if (p1->s_lno <= p2->s_lno) {
 341                do {
 342                        tail = &p1->next;
 343                        if ((p1 = *tail) == NULL) {
 344                                *tail = p2;
 345                                return list1;
 346                        }
 347                } while (p1->s_lno <= p2->s_lno);
 348        }
 349        for (;;) {
 350                *tail = p2;
 351                do {
 352                        tail = &p2->next;
 353                        if ((p2 = *tail) == NULL)  {
 354                                *tail = p1;
 355                                return list1;
 356                        }
 357                } while (p1->s_lno > p2->s_lno);
 358                *tail = p1;
 359                do {
 360                        tail = &p1->next;
 361                        if ((p1 = *tail) == NULL) {
 362                                *tail = p2;
 363                                return list1;
 364                        }
 365                } while (p1->s_lno <= p2->s_lno);
 366        }
 367}
 368
 369static void *get_next_blame(const void *p)
 370{
 371        return ((struct blame_entry *)p)->next;
 372}
 373
 374static void set_next_blame(void *p1, void *p2)
 375{
 376        ((struct blame_entry *)p1)->next = p2;
 377}
 378
 379/*
 380 * Final image line numbers are all different, so we don't need a
 381 * three-way comparison here.
 382 */
 383
 384static int compare_blame_final(const void *p1, const void *p2)
 385{
 386        return ((struct blame_entry *)p1)->lno > ((struct blame_entry *)p2)->lno
 387                ? 1 : -1;
 388}
 389
 390static int compare_blame_suspect(const void *p1, const void *p2)
 391{
 392        const struct blame_entry *s1 = p1, *s2 = p2;
 393        /*
 394         * to allow for collating suspects, we sort according to the
 395         * respective pointer value as the primary sorting criterion.
 396         * The actual relation is pretty unimportant as long as it
 397         * establishes a total order.  Comparing as integers gives us
 398         * that.
 399         */
 400        if (s1->suspect != s2->suspect)
 401                return (intptr_t)s1->suspect > (intptr_t)s2->suspect ? 1 : -1;
 402        if (s1->s_lno == s2->s_lno)
 403                return 0;
 404        return s1->s_lno > s2->s_lno ? 1 : -1;
 405}
 406
 407void blame_sort_final(struct blame_scoreboard *sb)
 408{
 409        sb->ent = llist_mergesort(sb->ent, get_next_blame, set_next_blame,
 410                                  compare_blame_final);
 411}
 412
 413static int compare_commits_by_reverse_commit_date(const void *a,
 414                                                  const void *b,
 415                                                  void *c)
 416{
 417        return -compare_commits_by_commit_date(a, b, c);
 418}
 419
 420/*
 421 * For debugging -- origin is refcounted, and this asserts that
 422 * we do not underflow.
 423 */
 424static void sanity_check_refcnt(struct blame_scoreboard *sb)
 425{
 426        int baa = 0;
 427        struct blame_entry *ent;
 428
 429        for (ent = sb->ent; ent; ent = ent->next) {
 430                /* Nobody should have zero or negative refcnt */
 431                if (ent->suspect->refcnt <= 0) {
 432                        fprintf(stderr, "%s in %s has negative refcnt %d\n",
 433                                ent->suspect->path,
 434                                oid_to_hex(&ent->suspect->commit->object.oid),
 435                                ent->suspect->refcnt);
 436                        baa = 1;
 437                }
 438        }
 439        if (baa)
 440                sb->on_sanity_fail(sb, baa);
 441}
 442
 443/*
 444 * If two blame entries that are next to each other came from
 445 * contiguous lines in the same origin (i.e. <commit, path> pair),
 446 * merge them together.
 447 */
 448void blame_coalesce(struct blame_scoreboard *sb)
 449{
 450        struct blame_entry *ent, *next;
 451
 452        for (ent = sb->ent; ent && (next = ent->next); ent = next) {
 453                if (ent->suspect == next->suspect &&
 454                    ent->s_lno + ent->num_lines == next->s_lno) {
 455                        ent->num_lines += next->num_lines;
 456                        ent->next = next->next;
 457                        blame_origin_decref(next->suspect);
 458                        free(next);
 459                        ent->score = 0;
 460                        next = ent; /* again */
 461                }
 462        }
 463
 464        if (sb->debug) /* sanity */
 465                sanity_check_refcnt(sb);
 466}
 467
 468/*
 469 * Merge the given sorted list of blames into a preexisting origin.
 470 * If there were no previous blames to that commit, it is entered into
 471 * the commit priority queue of the score board.
 472 */
 473
 474static void queue_blames(struct blame_scoreboard *sb, struct blame_origin *porigin,
 475                         struct blame_entry *sorted)
 476{
 477        if (porigin->suspects)
 478                porigin->suspects = blame_merge(porigin->suspects, sorted);
 479        else {
 480                struct blame_origin *o;
 481                for (o = porigin->commit->util; o; o = o->next) {
 482                        if (o->suspects) {
 483                                porigin->suspects = sorted;
 484                                return;
 485                        }
 486                }
 487                porigin->suspects = sorted;
 488                prio_queue_put(&sb->commits, porigin->commit);
 489        }
 490}
 491
 492/*
 493 * Fill the blob_sha1 field of an origin if it hasn't, so that later
 494 * call to fill_origin_blob() can use it to locate the data.  blob_sha1
 495 * for an origin is also used to pass the blame for the entire file to
 496 * the parent to detect the case where a child's blob is identical to
 497 * that of its parent's.
 498 *
 499 * This also fills origin->mode for corresponding tree path.
 500 */
 501static int fill_blob_sha1_and_mode(struct blame_origin *origin)
 502{
 503        if (!is_null_oid(&origin->blob_oid))
 504                return 0;
 505        if (get_tree_entry(origin->commit->object.oid.hash,
 506                           origin->path,
 507                           origin->blob_oid.hash, &origin->mode))
 508                goto error_out;
 509        if (sha1_object_info(origin->blob_oid.hash, NULL) != OBJ_BLOB)
 510                goto error_out;
 511        return 0;
 512 error_out:
 513        oidclr(&origin->blob_oid);
 514        origin->mode = S_IFINVALID;
 515        return -1;
 516}
 517
 518/*
 519 * We have an origin -- check if the same path exists in the
 520 * parent and return an origin structure to represent it.
 521 */
 522static struct blame_origin *find_origin(struct commit *parent,
 523                                  struct blame_origin *origin)
 524{
 525        struct blame_origin *porigin;
 526        struct diff_options diff_opts;
 527        const char *paths[2];
 528
 529        /* First check any existing origins */
 530        for (porigin = parent->util; porigin; porigin = porigin->next)
 531                if (!strcmp(porigin->path, origin->path)) {
 532                        /*
 533                         * The same path between origin and its parent
 534                         * without renaming -- the most common case.
 535                         */
 536                        return blame_origin_incref (porigin);
 537                }
 538
 539        /* See if the origin->path is different between parent
 540         * and origin first.  Most of the time they are the
 541         * same and diff-tree is fairly efficient about this.
 542         */
 543        diff_setup(&diff_opts);
 544        DIFF_OPT_SET(&diff_opts, RECURSIVE);
 545        diff_opts.detect_rename = 0;
 546        diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 547        paths[0] = origin->path;
 548        paths[1] = NULL;
 549
 550        parse_pathspec(&diff_opts.pathspec,
 551                       PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
 552                       PATHSPEC_LITERAL_PATH, "", paths);
 553        diff_setup_done(&diff_opts);
 554
 555        if (is_null_oid(&origin->commit->object.oid))
 556                do_diff_cache(&parent->tree->object.oid, &diff_opts);
 557        else
 558                diff_tree_oid(&parent->tree->object.oid,
 559                              &origin->commit->tree->object.oid,
 560                              "", &diff_opts);
 561        diffcore_std(&diff_opts);
 562
 563        if (!diff_queued_diff.nr) {
 564                /* The path is the same as parent */
 565                porigin = get_origin(parent, origin->path);
 566                oidcpy(&porigin->blob_oid, &origin->blob_oid);
 567                porigin->mode = origin->mode;
 568        } else {
 569                /*
 570                 * Since origin->path is a pathspec, if the parent
 571                 * commit had it as a directory, we will see a whole
 572                 * bunch of deletion of files in the directory that we
 573                 * do not care about.
 574                 */
 575                int i;
 576                struct diff_filepair *p = NULL;
 577                for (i = 0; i < diff_queued_diff.nr; i++) {
 578                        const char *name;
 579                        p = diff_queued_diff.queue[i];
 580                        name = p->one->path ? p->one->path : p->two->path;
 581                        if (!strcmp(name, origin->path))
 582                                break;
 583                }
 584                if (!p)
 585                        die("internal error in blame::find_origin");
 586                switch (p->status) {
 587                default:
 588                        die("internal error in blame::find_origin (%c)",
 589                            p->status);
 590                case 'M':
 591                        porigin = get_origin(parent, origin->path);
 592                        oidcpy(&porigin->blob_oid, &p->one->oid);
 593                        porigin->mode = p->one->mode;
 594                        break;
 595                case 'A':
 596                case 'T':
 597                        /* Did not exist in parent, or type changed */
 598                        break;
 599                }
 600        }
 601        diff_flush(&diff_opts);
 602        clear_pathspec(&diff_opts.pathspec);
 603        return porigin;
 604}
 605
 606/*
 607 * We have an origin -- find the path that corresponds to it in its
 608 * parent and return an origin structure to represent it.
 609 */
 610static struct blame_origin *find_rename(struct commit *parent,
 611                                  struct blame_origin *origin)
 612{
 613        struct blame_origin *porigin = NULL;
 614        struct diff_options diff_opts;
 615        int i;
 616
 617        diff_setup(&diff_opts);
 618        DIFF_OPT_SET(&diff_opts, RECURSIVE);
 619        diff_opts.detect_rename = DIFF_DETECT_RENAME;
 620        diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 621        diff_opts.single_follow = origin->path;
 622        diff_setup_done(&diff_opts);
 623
 624        if (is_null_oid(&origin->commit->object.oid))
 625                do_diff_cache(&parent->tree->object.oid, &diff_opts);
 626        else
 627                diff_tree_oid(&parent->tree->object.oid,
 628                              &origin->commit->tree->object.oid,
 629                              "", &diff_opts);
 630        diffcore_std(&diff_opts);
 631
 632        for (i = 0; i < diff_queued_diff.nr; i++) {
 633                struct diff_filepair *p = diff_queued_diff.queue[i];
 634                if ((p->status == 'R' || p->status == 'C') &&
 635                    !strcmp(p->two->path, origin->path)) {
 636                        porigin = get_origin(parent, p->one->path);
 637                        oidcpy(&porigin->blob_oid, &p->one->oid);
 638                        porigin->mode = p->one->mode;
 639                        break;
 640                }
 641        }
 642        diff_flush(&diff_opts);
 643        clear_pathspec(&diff_opts.pathspec);
 644        return porigin;
 645}
 646
 647/*
 648 * Append a new blame entry to a given output queue.
 649 */
 650static void add_blame_entry(struct blame_entry ***queue,
 651                            const struct blame_entry *src)
 652{
 653        struct blame_entry *e = xmalloc(sizeof(*e));
 654        memcpy(e, src, sizeof(*e));
 655        blame_origin_incref(e->suspect);
 656
 657        e->next = **queue;
 658        **queue = e;
 659        *queue = &e->next;
 660}
 661
 662/*
 663 * src typically is on-stack; we want to copy the information in it to
 664 * a malloced blame_entry that gets added to the given queue.  The
 665 * origin of dst loses a refcnt.
 666 */
 667static void dup_entry(struct blame_entry ***queue,
 668                      struct blame_entry *dst, struct blame_entry *src)
 669{
 670        blame_origin_incref(src->suspect);
 671        blame_origin_decref(dst->suspect);
 672        memcpy(dst, src, sizeof(*src));
 673        dst->next = **queue;
 674        **queue = dst;
 675        *queue = &dst->next;
 676}
 677
 678const char *blame_nth_line(struct blame_scoreboard *sb, long lno)
 679{
 680        return sb->final_buf + sb->lineno[lno];
 681}
 682
 683/*
 684 * It is known that lines between tlno to same came from parent, and e
 685 * has an overlap with that range.  it also is known that parent's
 686 * line plno corresponds to e's line tlno.
 687 *
 688 *                <---- e ----->
 689 *                   <------>
 690 *                   <------------>
 691 *             <------------>
 692 *             <------------------>
 693 *
 694 * Split e into potentially three parts; before this chunk, the chunk
 695 * to be blamed for the parent, and after that portion.
 696 */
 697static void split_overlap(struct blame_entry *split,
 698                          struct blame_entry *e,
 699                          int tlno, int plno, int same,
 700                          struct blame_origin *parent)
 701{
 702        int chunk_end_lno;
 703        memset(split, 0, sizeof(struct blame_entry [3]));
 704
 705        if (e->s_lno < tlno) {
 706                /* there is a pre-chunk part not blamed on parent */
 707                split[0].suspect = blame_origin_incref(e->suspect);
 708                split[0].lno = e->lno;
 709                split[0].s_lno = e->s_lno;
 710                split[0].num_lines = tlno - e->s_lno;
 711                split[1].lno = e->lno + tlno - e->s_lno;
 712                split[1].s_lno = plno;
 713        }
 714        else {
 715                split[1].lno = e->lno;
 716                split[1].s_lno = plno + (e->s_lno - tlno);
 717        }
 718
 719        if (same < e->s_lno + e->num_lines) {
 720                /* there is a post-chunk part not blamed on parent */
 721                split[2].suspect = blame_origin_incref(e->suspect);
 722                split[2].lno = e->lno + (same - e->s_lno);
 723                split[2].s_lno = e->s_lno + (same - e->s_lno);
 724                split[2].num_lines = e->s_lno + e->num_lines - same;
 725                chunk_end_lno = split[2].lno;
 726        }
 727        else
 728                chunk_end_lno = e->lno + e->num_lines;
 729        split[1].num_lines = chunk_end_lno - split[1].lno;
 730
 731        /*
 732         * if it turns out there is nothing to blame the parent for,
 733         * forget about the splitting.  !split[1].suspect signals this.
 734         */
 735        if (split[1].num_lines < 1)
 736                return;
 737        split[1].suspect = blame_origin_incref(parent);
 738}
 739
 740/*
 741 * split_overlap() divided an existing blame e into up to three parts
 742 * in split.  Any assigned blame is moved to queue to
 743 * reflect the split.
 744 */
 745static void split_blame(struct blame_entry ***blamed,
 746                        struct blame_entry ***unblamed,
 747                        struct blame_entry *split,
 748                        struct blame_entry *e)
 749{
 750        if (split[0].suspect && split[2].suspect) {
 751                /* The first part (reuse storage for the existing entry e) */
 752                dup_entry(unblamed, e, &split[0]);
 753
 754                /* The last part -- me */
 755                add_blame_entry(unblamed, &split[2]);
 756
 757                /* ... and the middle part -- parent */
 758                add_blame_entry(blamed, &split[1]);
 759        }
 760        else if (!split[0].suspect && !split[2].suspect)
 761                /*
 762                 * The parent covers the entire area; reuse storage for
 763                 * e and replace it with the parent.
 764                 */
 765                dup_entry(blamed, e, &split[1]);
 766        else if (split[0].suspect) {
 767                /* me and then parent */
 768                dup_entry(unblamed, e, &split[0]);
 769                add_blame_entry(blamed, &split[1]);
 770        }
 771        else {
 772                /* parent and then me */
 773                dup_entry(blamed, e, &split[1]);
 774                add_blame_entry(unblamed, &split[2]);
 775        }
 776}
 777
 778/*
 779 * After splitting the blame, the origins used by the
 780 * on-stack blame_entry should lose one refcnt each.
 781 */
 782static void decref_split(struct blame_entry *split)
 783{
 784        int i;
 785
 786        for (i = 0; i < 3; i++)
 787                blame_origin_decref(split[i].suspect);
 788}
 789
 790/*
 791 * reverse_blame reverses the list given in head, appending tail.
 792 * That allows us to build lists in reverse order, then reverse them
 793 * afterwards.  This can be faster than building the list in proper
 794 * order right away.  The reason is that building in proper order
 795 * requires writing a link in the _previous_ element, while building
 796 * in reverse order just requires placing the list head into the
 797 * _current_ element.
 798 */
 799
 800static struct blame_entry *reverse_blame(struct blame_entry *head,
 801                                         struct blame_entry *tail)
 802{
 803        while (head) {
 804                struct blame_entry *next = head->next;
 805                head->next = tail;
 806                tail = head;
 807                head = next;
 808        }
 809        return tail;
 810}
 811
 812/*
 813 * Process one hunk from the patch between the current suspect for
 814 * blame_entry e and its parent.  This first blames any unfinished
 815 * entries before the chunk (which is where target and parent start
 816 * differing) on the parent, and then splits blame entries at the
 817 * start and at the end of the difference region.  Since use of -M and
 818 * -C options may lead to overlapping/duplicate source line number
 819 * ranges, all we can rely on from sorting/merging is the order of the
 820 * first suspect line number.
 821 */
 822static void blame_chunk(struct blame_entry ***dstq, struct blame_entry ***srcq,
 823                        int tlno, int offset, int same,
 824                        struct blame_origin *parent)
 825{
 826        struct blame_entry *e = **srcq;
 827        struct blame_entry *samep = NULL, *diffp = NULL;
 828
 829        while (e && e->s_lno < tlno) {
 830                struct blame_entry *next = e->next;
 831                /*
 832                 * current record starts before differing portion.  If
 833                 * it reaches into it, we need to split it up and
 834                 * examine the second part separately.
 835                 */
 836                if (e->s_lno + e->num_lines > tlno) {
 837                        /* Move second half to a new record */
 838                        int len = tlno - e->s_lno;
 839                        struct blame_entry *n = xcalloc(1, sizeof (struct blame_entry));
 840                        n->suspect = e->suspect;
 841                        n->lno = e->lno + len;
 842                        n->s_lno = e->s_lno + len;
 843                        n->num_lines = e->num_lines - len;
 844                        e->num_lines = len;
 845                        e->score = 0;
 846                        /* Push new record to diffp */
 847                        n->next = diffp;
 848                        diffp = n;
 849                } else
 850                        blame_origin_decref(e->suspect);
 851                /* Pass blame for everything before the differing
 852                 * chunk to the parent */
 853                e->suspect = blame_origin_incref(parent);
 854                e->s_lno += offset;
 855                e->next = samep;
 856                samep = e;
 857                e = next;
 858        }
 859        /*
 860         * As we don't know how much of a common stretch after this
 861         * diff will occur, the currently blamed parts are all that we
 862         * can assign to the parent for now.
 863         */
 864
 865        if (samep) {
 866                **dstq = reverse_blame(samep, **dstq);
 867                *dstq = &samep->next;
 868        }
 869        /*
 870         * Prepend the split off portions: everything after e starts
 871         * after the blameable portion.
 872         */
 873        e = reverse_blame(diffp, e);
 874
 875        /*
 876         * Now retain records on the target while parts are different
 877         * from the parent.
 878         */
 879        samep = NULL;
 880        diffp = NULL;
 881        while (e && e->s_lno < same) {
 882                struct blame_entry *next = e->next;
 883
 884                /*
 885                 * If current record extends into sameness, need to split.
 886                 */
 887                if (e->s_lno + e->num_lines > same) {
 888                        /*
 889                         * Move second half to a new record to be
 890                         * processed by later chunks
 891                         */
 892                        int len = same - e->s_lno;
 893                        struct blame_entry *n = xcalloc(1, sizeof (struct blame_entry));
 894                        n->suspect = blame_origin_incref(e->suspect);
 895                        n->lno = e->lno + len;
 896                        n->s_lno = e->s_lno + len;
 897                        n->num_lines = e->num_lines - len;
 898                        e->num_lines = len;
 899                        e->score = 0;
 900                        /* Push new record to samep */
 901                        n->next = samep;
 902                        samep = n;
 903                }
 904                e->next = diffp;
 905                diffp = e;
 906                e = next;
 907        }
 908        **srcq = reverse_blame(diffp, reverse_blame(samep, e));
 909        /* Move across elements that are in the unblamable portion */
 910        if (diffp)
 911                *srcq = &diffp->next;
 912}
 913
 914struct blame_chunk_cb_data {
 915        struct blame_origin *parent;
 916        long offset;
 917        struct blame_entry **dstq;
 918        struct blame_entry **srcq;
 919};
 920
 921/* diff chunks are from parent to target */
 922static int blame_chunk_cb(long start_a, long count_a,
 923                          long start_b, long count_b, void *data)
 924{
 925        struct blame_chunk_cb_data *d = data;
 926        if (start_a - start_b != d->offset)
 927                die("internal error in blame::blame_chunk_cb");
 928        blame_chunk(&d->dstq, &d->srcq, start_b, start_a - start_b,
 929                    start_b + count_b, d->parent);
 930        d->offset = start_a + count_a - (start_b + count_b);
 931        return 0;
 932}
 933
 934/*
 935 * We are looking at the origin 'target' and aiming to pass blame
 936 * for the lines it is suspected to its parent.  Run diff to find
 937 * which lines came from parent and pass blame for them.
 938 */
 939static void pass_blame_to_parent(struct blame_scoreboard *sb,
 940                                 struct blame_origin *target,
 941                                 struct blame_origin *parent)
 942{
 943        mmfile_t file_p, file_o;
 944        struct blame_chunk_cb_data d;
 945        struct blame_entry *newdest = NULL;
 946
 947        if (!target->suspects)
 948                return; /* nothing remains for this target */
 949
 950        d.parent = parent;
 951        d.offset = 0;
 952        d.dstq = &newdest; d.srcq = &target->suspects;
 953
 954        fill_origin_blob(&sb->revs->diffopt, parent, &file_p, &sb->num_read_blob);
 955        fill_origin_blob(&sb->revs->diffopt, target, &file_o, &sb->num_read_blob);
 956        sb->num_get_patch++;
 957
 958        if (diff_hunks(&file_p, &file_o, blame_chunk_cb, &d, sb->xdl_opts))
 959                die("unable to generate diff (%s -> %s)",
 960                    oid_to_hex(&parent->commit->object.oid),
 961                    oid_to_hex(&target->commit->object.oid));
 962        /* The rest are the same as the parent */
 963        blame_chunk(&d.dstq, &d.srcq, INT_MAX, d.offset, INT_MAX, parent);
 964        *d.dstq = NULL;
 965        queue_blames(sb, parent, newdest);
 966
 967        return;
 968}
 969
 970/*
 971 * The lines in blame_entry after splitting blames many times can become
 972 * very small and trivial, and at some point it becomes pointless to
 973 * blame the parents.  E.g. "\t\t}\n\t}\n\n" appears everywhere in any
 974 * ordinary C program, and it is not worth to say it was copied from
 975 * totally unrelated file in the parent.
 976 *
 977 * Compute how trivial the lines in the blame_entry are.
 978 */
 979unsigned blame_entry_score(struct blame_scoreboard *sb, struct blame_entry *e)
 980{
 981        unsigned score;
 982        const char *cp, *ep;
 983
 984        if (e->score)
 985                return e->score;
 986
 987        score = 1;
 988        cp = blame_nth_line(sb, e->lno);
 989        ep = blame_nth_line(sb, e->lno + e->num_lines);
 990        while (cp < ep) {
 991                unsigned ch = *((unsigned char *)cp);
 992                if (isalnum(ch))
 993                        score++;
 994                cp++;
 995        }
 996        e->score = score;
 997        return score;
 998}
 999
1000/*
1001 * best_so_far[] and this[] are both a split of an existing blame_entry
1002 * that passes blame to the parent.  Maintain best_so_far the best split
1003 * so far, by comparing this and best_so_far and copying this into
1004 * bst_so_far as needed.
1005 */
1006static void copy_split_if_better(struct blame_scoreboard *sb,
1007                                 struct blame_entry *best_so_far,
1008                                 struct blame_entry *this)
1009{
1010        int i;
1011
1012        if (!this[1].suspect)
1013                return;
1014        if (best_so_far[1].suspect) {
1015                if (blame_entry_score(sb, &this[1]) < blame_entry_score(sb, &best_so_far[1]))
1016                        return;
1017        }
1018
1019        for (i = 0; i < 3; i++)
1020                blame_origin_incref(this[i].suspect);
1021        decref_split(best_so_far);
1022        memcpy(best_so_far, this, sizeof(struct blame_entry [3]));
1023}
1024
1025/*
1026 * We are looking at a part of the final image represented by
1027 * ent (tlno and same are offset by ent->s_lno).
1028 * tlno is where we are looking at in the final image.
1029 * up to (but not including) same match preimage.
1030 * plno is where we are looking at in the preimage.
1031 *
1032 * <-------------- final image ---------------------->
1033 *       <------ent------>
1034 *         ^tlno ^same
1035 *    <---------preimage----->
1036 *         ^plno
1037 *
1038 * All line numbers are 0-based.
1039 */
1040static void handle_split(struct blame_scoreboard *sb,
1041                         struct blame_entry *ent,
1042                         int tlno, int plno, int same,
1043                         struct blame_origin *parent,
1044                         struct blame_entry *split)
1045{
1046        if (ent->num_lines <= tlno)
1047                return;
1048        if (tlno < same) {
1049                struct blame_entry this[3];
1050                tlno += ent->s_lno;
1051                same += ent->s_lno;
1052                split_overlap(this, ent, tlno, plno, same, parent);
1053                copy_split_if_better(sb, split, this);
1054                decref_split(this);
1055        }
1056}
1057
1058struct handle_split_cb_data {
1059        struct blame_scoreboard *sb;
1060        struct blame_entry *ent;
1061        struct blame_origin *parent;
1062        struct blame_entry *split;
1063        long plno;
1064        long tlno;
1065};
1066
1067static int handle_split_cb(long start_a, long count_a,
1068                           long start_b, long count_b, void *data)
1069{
1070        struct handle_split_cb_data *d = data;
1071        handle_split(d->sb, d->ent, d->tlno, d->plno, start_b, d->parent,
1072                     d->split);
1073        d->plno = start_a + count_a;
1074        d->tlno = start_b + count_b;
1075        return 0;
1076}
1077
1078/*
1079 * Find the lines from parent that are the same as ent so that
1080 * we can pass blames to it.  file_p has the blob contents for
1081 * the parent.
1082 */
1083static void find_copy_in_blob(struct blame_scoreboard *sb,
1084                              struct blame_entry *ent,
1085                              struct blame_origin *parent,
1086                              struct blame_entry *split,
1087                              mmfile_t *file_p)
1088{
1089        const char *cp;
1090        mmfile_t file_o;
1091        struct handle_split_cb_data d;
1092
1093        memset(&d, 0, sizeof(d));
1094        d.sb = sb; d.ent = ent; d.parent = parent; d.split = split;
1095        /*
1096         * Prepare mmfile that contains only the lines in ent.
1097         */
1098        cp = blame_nth_line(sb, ent->lno);
1099        file_o.ptr = (char *) cp;
1100        file_o.size = blame_nth_line(sb, ent->lno + ent->num_lines) - cp;
1101
1102        /*
1103         * file_o is a part of final image we are annotating.
1104         * file_p partially may match that image.
1105         */
1106        memset(split, 0, sizeof(struct blame_entry [3]));
1107        if (diff_hunks(file_p, &file_o, handle_split_cb, &d, sb->xdl_opts))
1108                die("unable to generate diff (%s)",
1109                    oid_to_hex(&parent->commit->object.oid));
1110        /* remainder, if any, all match the preimage */
1111        handle_split(sb, ent, d.tlno, d.plno, ent->num_lines, parent, split);
1112}
1113
1114/* Move all blame entries from list *source that have a score smaller
1115 * than score_min to the front of list *small.
1116 * Returns a pointer to the link pointing to the old head of the small list.
1117 */
1118
1119static struct blame_entry **filter_small(struct blame_scoreboard *sb,
1120                                         struct blame_entry **small,
1121                                         struct blame_entry **source,
1122                                         unsigned score_min)
1123{
1124        struct blame_entry *p = *source;
1125        struct blame_entry *oldsmall = *small;
1126        while (p) {
1127                if (blame_entry_score(sb, p) <= score_min) {
1128                        *small = p;
1129                        small = &p->next;
1130                        p = *small;
1131                } else {
1132                        *source = p;
1133                        source = &p->next;
1134                        p = *source;
1135                }
1136        }
1137        *small = oldsmall;
1138        *source = NULL;
1139        return small;
1140}
1141
1142/*
1143 * See if lines currently target is suspected for can be attributed to
1144 * parent.
1145 */
1146static void find_move_in_parent(struct blame_scoreboard *sb,
1147                                struct blame_entry ***blamed,
1148                                struct blame_entry **toosmall,
1149                                struct blame_origin *target,
1150                                struct blame_origin *parent)
1151{
1152        struct blame_entry *e, split[3];
1153        struct blame_entry *unblamed = target->suspects;
1154        struct blame_entry *leftover = NULL;
1155        mmfile_t file_p;
1156
1157        if (!unblamed)
1158                return; /* nothing remains for this target */
1159
1160        fill_origin_blob(&sb->revs->diffopt, parent, &file_p, &sb->num_read_blob);
1161        if (!file_p.ptr)
1162                return;
1163
1164        /* At each iteration, unblamed has a NULL-terminated list of
1165         * entries that have not yet been tested for blame.  leftover
1166         * contains the reversed list of entries that have been tested
1167         * without being assignable to the parent.
1168         */
1169        do {
1170                struct blame_entry **unblamedtail = &unblamed;
1171                struct blame_entry *next;
1172                for (e = unblamed; e; e = next) {
1173                        next = e->next;
1174                        find_copy_in_blob(sb, e, parent, split, &file_p);
1175                        if (split[1].suspect &&
1176                            sb->move_score < blame_entry_score(sb, &split[1])) {
1177                                split_blame(blamed, &unblamedtail, split, e);
1178                        } else {
1179                                e->next = leftover;
1180                                leftover = e;
1181                        }
1182                        decref_split(split);
1183                }
1184                *unblamedtail = NULL;
1185                toosmall = filter_small(sb, toosmall, &unblamed, sb->move_score);
1186        } while (unblamed);
1187        target->suspects = reverse_blame(leftover, NULL);
1188}
1189
1190struct blame_list {
1191        struct blame_entry *ent;
1192        struct blame_entry split[3];
1193};
1194
1195/*
1196 * Count the number of entries the target is suspected for,
1197 * and prepare a list of entry and the best split.
1198 */
1199static struct blame_list *setup_blame_list(struct blame_entry *unblamed,
1200                                           int *num_ents_p)
1201{
1202        struct blame_entry *e;
1203        int num_ents, i;
1204        struct blame_list *blame_list = NULL;
1205
1206        for (e = unblamed, num_ents = 0; e; e = e->next)
1207                num_ents++;
1208        if (num_ents) {
1209                blame_list = xcalloc(num_ents, sizeof(struct blame_list));
1210                for (e = unblamed, i = 0; e; e = e->next)
1211                        blame_list[i++].ent = e;
1212        }
1213        *num_ents_p = num_ents;
1214        return blame_list;
1215}
1216
1217/*
1218 * For lines target is suspected for, see if we can find code movement
1219 * across file boundary from the parent commit.  porigin is the path
1220 * in the parent we already tried.
1221 */
1222static void find_copy_in_parent(struct blame_scoreboard *sb,
1223                                struct blame_entry ***blamed,
1224                                struct blame_entry **toosmall,
1225                                struct blame_origin *target,
1226                                struct commit *parent,
1227                                struct blame_origin *porigin,
1228                                int opt)
1229{
1230        struct diff_options diff_opts;
1231        int i, j;
1232        struct blame_list *blame_list;
1233        int num_ents;
1234        struct blame_entry *unblamed = target->suspects;
1235        struct blame_entry *leftover = NULL;
1236
1237        if (!unblamed)
1238                return; /* nothing remains for this target */
1239
1240        diff_setup(&diff_opts);
1241        DIFF_OPT_SET(&diff_opts, RECURSIVE);
1242        diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1243
1244        diff_setup_done(&diff_opts);
1245
1246        /* Try "find copies harder" on new path if requested;
1247         * we do not want to use diffcore_rename() actually to
1248         * match things up; find_copies_harder is set only to
1249         * force diff_tree_oid() to feed all filepairs to diff_queue,
1250         * and this code needs to be after diff_setup_done(), which
1251         * usually makes find-copies-harder imply copy detection.
1252         */
1253        if ((opt & PICKAXE_BLAME_COPY_HARDEST)
1254            || ((opt & PICKAXE_BLAME_COPY_HARDER)
1255                && (!porigin || strcmp(target->path, porigin->path))))
1256                DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
1257
1258        if (is_null_oid(&target->commit->object.oid))
1259                do_diff_cache(&parent->tree->object.oid, &diff_opts);
1260        else
1261                diff_tree_oid(&parent->tree->object.oid,
1262                              &target->commit->tree->object.oid,
1263                              "", &diff_opts);
1264
1265        if (!DIFF_OPT_TST(&diff_opts, FIND_COPIES_HARDER))
1266                diffcore_std(&diff_opts);
1267
1268        do {
1269                struct blame_entry **unblamedtail = &unblamed;
1270                blame_list = setup_blame_list(unblamed, &num_ents);
1271
1272                for (i = 0; i < diff_queued_diff.nr; i++) {
1273                        struct diff_filepair *p = diff_queued_diff.queue[i];
1274                        struct blame_origin *norigin;
1275                        mmfile_t file_p;
1276                        struct blame_entry this[3];
1277
1278                        if (!DIFF_FILE_VALID(p->one))
1279                                continue; /* does not exist in parent */
1280                        if (S_ISGITLINK(p->one->mode))
1281                                continue; /* ignore git links */
1282                        if (porigin && !strcmp(p->one->path, porigin->path))
1283                                /* find_move already dealt with this path */
1284                                continue;
1285
1286                        norigin = get_origin(parent, p->one->path);
1287                        oidcpy(&norigin->blob_oid, &p->one->oid);
1288                        norigin->mode = p->one->mode;
1289                        fill_origin_blob(&sb->revs->diffopt, norigin, &file_p, &sb->num_read_blob);
1290                        if (!file_p.ptr)
1291                                continue;
1292
1293                        for (j = 0; j < num_ents; j++) {
1294                                find_copy_in_blob(sb, blame_list[j].ent,
1295                                                  norigin, this, &file_p);
1296                                copy_split_if_better(sb, blame_list[j].split,
1297                                                     this);
1298                                decref_split(this);
1299                        }
1300                        blame_origin_decref(norigin);
1301                }
1302
1303                for (j = 0; j < num_ents; j++) {
1304                        struct blame_entry *split = blame_list[j].split;
1305                        if (split[1].suspect &&
1306                            sb->copy_score < blame_entry_score(sb, &split[1])) {
1307                                split_blame(blamed, &unblamedtail, split,
1308                                            blame_list[j].ent);
1309                        } else {
1310                                blame_list[j].ent->next = leftover;
1311                                leftover = blame_list[j].ent;
1312                        }
1313                        decref_split(split);
1314                }
1315                free(blame_list);
1316                *unblamedtail = NULL;
1317                toosmall = filter_small(sb, toosmall, &unblamed, sb->copy_score);
1318        } while (unblamed);
1319        target->suspects = reverse_blame(leftover, NULL);
1320        diff_flush(&diff_opts);
1321        clear_pathspec(&diff_opts.pathspec);
1322}
1323
1324/*
1325 * The blobs of origin and porigin exactly match, so everything
1326 * origin is suspected for can be blamed on the parent.
1327 */
1328static void pass_whole_blame(struct blame_scoreboard *sb,
1329                             struct blame_origin *origin, struct blame_origin *porigin)
1330{
1331        struct blame_entry *e, *suspects;
1332
1333        if (!porigin->file.ptr && origin->file.ptr) {
1334                /* Steal its file */
1335                porigin->file = origin->file;
1336                origin->file.ptr = NULL;
1337        }
1338        suspects = origin->suspects;
1339        origin->suspects = NULL;
1340        for (e = suspects; e; e = e->next) {
1341                blame_origin_incref(porigin);
1342                blame_origin_decref(e->suspect);
1343                e->suspect = porigin;
1344        }
1345        queue_blames(sb, porigin, suspects);
1346}
1347
1348/*
1349 * We pass blame from the current commit to its parents.  We keep saying
1350 * "parent" (and "porigin"), but what we mean is to find scapegoat to
1351 * exonerate ourselves.
1352 */
1353static struct commit_list *first_scapegoat(struct rev_info *revs, struct commit *commit,
1354                                        int reverse)
1355{
1356        if (!reverse) {
1357                if (revs->first_parent_only &&
1358                    commit->parents &&
1359                    commit->parents->next) {
1360                        free_commit_list(commit->parents->next);
1361                        commit->parents->next = NULL;
1362                }
1363                return commit->parents;
1364        }
1365        return lookup_decoration(&revs->children, &commit->object);
1366}
1367
1368static int num_scapegoats(struct rev_info *revs, struct commit *commit, int reverse)
1369{
1370        struct commit_list *l = first_scapegoat(revs, commit, reverse);
1371        return commit_list_count(l);
1372}
1373
1374/* Distribute collected unsorted blames to the respected sorted lists
1375 * in the various origins.
1376 */
1377static void distribute_blame(struct blame_scoreboard *sb, struct blame_entry *blamed)
1378{
1379        blamed = llist_mergesort(blamed, get_next_blame, set_next_blame,
1380                                 compare_blame_suspect);
1381        while (blamed)
1382        {
1383                struct blame_origin *porigin = blamed->suspect;
1384                struct blame_entry *suspects = NULL;
1385                do {
1386                        struct blame_entry *next = blamed->next;
1387                        blamed->next = suspects;
1388                        suspects = blamed;
1389                        blamed = next;
1390                } while (blamed && blamed->suspect == porigin);
1391                suspects = reverse_blame(suspects, NULL);
1392                queue_blames(sb, porigin, suspects);
1393        }
1394}
1395
1396#define MAXSG 16
1397
1398static void pass_blame(struct blame_scoreboard *sb, struct blame_origin *origin, int opt)
1399{
1400        struct rev_info *revs = sb->revs;
1401        int i, pass, num_sg;
1402        struct commit *commit = origin->commit;
1403        struct commit_list *sg;
1404        struct blame_origin *sg_buf[MAXSG];
1405        struct blame_origin *porigin, **sg_origin = sg_buf;
1406        struct blame_entry *toosmall = NULL;
1407        struct blame_entry *blames, **blametail = &blames;
1408
1409        num_sg = num_scapegoats(revs, commit, sb->reverse);
1410        if (!num_sg)
1411                goto finish;
1412        else if (num_sg < ARRAY_SIZE(sg_buf))
1413                memset(sg_buf, 0, sizeof(sg_buf));
1414        else
1415                sg_origin = xcalloc(num_sg, sizeof(*sg_origin));
1416
1417        /*
1418         * The first pass looks for unrenamed path to optimize for
1419         * common cases, then we look for renames in the second pass.
1420         */
1421        for (pass = 0; pass < 2 - sb->no_whole_file_rename; pass++) {
1422                struct blame_origin *(*find)(struct commit *, struct blame_origin *);
1423                find = pass ? find_rename : find_origin;
1424
1425                for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
1426                     i < num_sg && sg;
1427                     sg = sg->next, i++) {
1428                        struct commit *p = sg->item;
1429                        int j, same;
1430
1431                        if (sg_origin[i])
1432                                continue;
1433                        if (parse_commit(p))
1434                                continue;
1435                        porigin = find(p, origin);
1436                        if (!porigin)
1437                                continue;
1438                        if (!oidcmp(&porigin->blob_oid, &origin->blob_oid)) {
1439                                pass_whole_blame(sb, origin, porigin);
1440                                blame_origin_decref(porigin);
1441                                goto finish;
1442                        }
1443                        for (j = same = 0; j < i; j++)
1444                                if (sg_origin[j] &&
1445                                    !oidcmp(&sg_origin[j]->blob_oid, &porigin->blob_oid)) {
1446                                        same = 1;
1447                                        break;
1448                                }
1449                        if (!same)
1450                                sg_origin[i] = porigin;
1451                        else
1452                                blame_origin_decref(porigin);
1453                }
1454        }
1455
1456        sb->num_commits++;
1457        for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
1458             i < num_sg && sg;
1459             sg = sg->next, i++) {
1460                struct blame_origin *porigin = sg_origin[i];
1461                if (!porigin)
1462                        continue;
1463                if (!origin->previous) {
1464                        blame_origin_incref(porigin);
1465                        origin->previous = porigin;
1466                }
1467                pass_blame_to_parent(sb, origin, porigin);
1468                if (!origin->suspects)
1469                        goto finish;
1470        }
1471
1472        /*
1473         * Optionally find moves in parents' files.
1474         */
1475        if (opt & PICKAXE_BLAME_MOVE) {
1476                filter_small(sb, &toosmall, &origin->suspects, sb->move_score);
1477                if (origin->suspects) {
1478                        for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
1479                             i < num_sg && sg;
1480                             sg = sg->next, i++) {
1481                                struct blame_origin *porigin = sg_origin[i];
1482                                if (!porigin)
1483                                        continue;
1484                                find_move_in_parent(sb, &blametail, &toosmall, origin, porigin);
1485                                if (!origin->suspects)
1486                                        break;
1487                        }
1488                }
1489        }
1490
1491        /*
1492         * Optionally find copies from parents' files.
1493         */
1494        if (opt & PICKAXE_BLAME_COPY) {
1495                if (sb->copy_score > sb->move_score)
1496                        filter_small(sb, &toosmall, &origin->suspects, sb->copy_score);
1497                else if (sb->copy_score < sb->move_score) {
1498                        origin->suspects = blame_merge(origin->suspects, toosmall);
1499                        toosmall = NULL;
1500                        filter_small(sb, &toosmall, &origin->suspects, sb->copy_score);
1501                }
1502                if (!origin->suspects)
1503                        goto finish;
1504
1505                for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
1506                     i < num_sg && sg;
1507                     sg = sg->next, i++) {
1508                        struct blame_origin *porigin = sg_origin[i];
1509                        find_copy_in_parent(sb, &blametail, &toosmall,
1510                                            origin, sg->item, porigin, opt);
1511                        if (!origin->suspects)
1512                                goto finish;
1513                }
1514        }
1515
1516finish:
1517        *blametail = NULL;
1518        distribute_blame(sb, blames);
1519        /*
1520         * prepend toosmall to origin->suspects
1521         *
1522         * There is no point in sorting: this ends up on a big
1523         * unsorted list in the caller anyway.
1524         */
1525        if (toosmall) {
1526                struct blame_entry **tail = &toosmall;
1527                while (*tail)
1528                        tail = &(*tail)->next;
1529                *tail = origin->suspects;
1530                origin->suspects = toosmall;
1531        }
1532        for (i = 0; i < num_sg; i++) {
1533                if (sg_origin[i]) {
1534                        drop_origin_blob(sg_origin[i]);
1535                        blame_origin_decref(sg_origin[i]);
1536                }
1537        }
1538        drop_origin_blob(origin);
1539        if (sg_buf != sg_origin)
1540                free(sg_origin);
1541}
1542
1543/*
1544 * The main loop -- while we have blobs with lines whose true origin
1545 * is still unknown, pick one blob, and allow its lines to pass blames
1546 * to its parents. */
1547void assign_blame(struct blame_scoreboard *sb, int opt)
1548{
1549        struct rev_info *revs = sb->revs;
1550        struct commit *commit = prio_queue_get(&sb->commits);
1551
1552        while (commit) {
1553                struct blame_entry *ent;
1554                struct blame_origin *suspect = commit->util;
1555
1556                /* find one suspect to break down */
1557                while (suspect && !suspect->suspects)
1558                        suspect = suspect->next;
1559
1560                if (!suspect) {
1561                        commit = prio_queue_get(&sb->commits);
1562                        continue;
1563                }
1564
1565                assert(commit == suspect->commit);
1566
1567                /*
1568                 * We will use this suspect later in the loop,
1569                 * so hold onto it in the meantime.
1570                 */
1571                blame_origin_incref(suspect);
1572                parse_commit(commit);
1573                if (sb->reverse ||
1574                    (!(commit->object.flags & UNINTERESTING) &&
1575                     !(revs->max_age != -1 && commit->date < revs->max_age)))
1576                        pass_blame(sb, suspect, opt);
1577                else {
1578                        commit->object.flags |= UNINTERESTING;
1579                        if (commit->object.parsed)
1580                                mark_parents_uninteresting(commit);
1581                }
1582                /* treat root commit as boundary */
1583                if (!commit->parents && !sb->show_root)
1584                        commit->object.flags |= UNINTERESTING;
1585
1586                /* Take responsibility for the remaining entries */
1587                ent = suspect->suspects;
1588                if (ent) {
1589                        suspect->guilty = 1;
1590                        for (;;) {
1591                                struct blame_entry *next = ent->next;
1592                                if (sb->found_guilty_entry)
1593                                        sb->found_guilty_entry(ent, sb->found_guilty_entry_data);
1594                                if (next) {
1595                                        ent = next;
1596                                        continue;
1597                                }
1598                                ent->next = sb->ent;
1599                                sb->ent = suspect->suspects;
1600                                suspect->suspects = NULL;
1601                                break;
1602                        }
1603                }
1604                blame_origin_decref(suspect);
1605
1606                if (sb->debug) /* sanity */
1607                        sanity_check_refcnt(sb);
1608        }
1609}
1610
1611static const char *get_next_line(const char *start, const char *end)
1612{
1613        const char *nl = memchr(start, '\n', end - start);
1614        return nl ? nl + 1 : end;
1615}
1616
1617/*
1618 * To allow quick access to the contents of nth line in the
1619 * final image, prepare an index in the scoreboard.
1620 */
1621static int prepare_lines(struct blame_scoreboard *sb)
1622{
1623        const char *buf = sb->final_buf;
1624        unsigned long len = sb->final_buf_size;
1625        const char *end = buf + len;
1626        const char *p;
1627        int *lineno;
1628        int num = 0;
1629
1630        for (p = buf; p < end; p = get_next_line(p, end))
1631                num++;
1632
1633        ALLOC_ARRAY(sb->lineno, num + 1);
1634        lineno = sb->lineno;
1635
1636        for (p = buf; p < end; p = get_next_line(p, end))
1637                *lineno++ = p - buf;
1638
1639        *lineno = len;
1640
1641        sb->num_lines = num;
1642        return sb->num_lines;
1643}
1644
1645static struct commit *find_single_final(struct rev_info *revs,
1646                                        const char **name_p)
1647{
1648        int i;
1649        struct commit *found = NULL;
1650        const char *name = NULL;
1651
1652        for (i = 0; i < revs->pending.nr; i++) {
1653                struct object *obj = revs->pending.objects[i].item;
1654                if (obj->flags & UNINTERESTING)
1655                        continue;
1656                obj = deref_tag(obj, NULL, 0);
1657                if (obj->type != OBJ_COMMIT)
1658                        die("Non commit %s?", revs->pending.objects[i].name);
1659                if (found)
1660                        die("More than one commit to dig from %s and %s?",
1661                            revs->pending.objects[i].name, name);
1662                found = (struct commit *)obj;
1663                name = revs->pending.objects[i].name;
1664        }
1665        if (name_p)
1666                *name_p = xstrdup_or_null(name);
1667        return found;
1668}
1669
1670static struct commit *dwim_reverse_initial(struct rev_info *revs,
1671                                           const char **name_p)
1672{
1673        /*
1674         * DWIM "git blame --reverse ONE -- PATH" as
1675         * "git blame --reverse ONE..HEAD -- PATH" but only do so
1676         * when it makes sense.
1677         */
1678        struct object *obj;
1679        struct commit *head_commit;
1680        struct object_id head_oid;
1681
1682        if (revs->pending.nr != 1)
1683                return NULL;
1684
1685        /* Is that sole rev a committish? */
1686        obj = revs->pending.objects[0].item;
1687        obj = deref_tag(obj, NULL, 0);
1688        if (obj->type != OBJ_COMMIT)
1689                return NULL;
1690
1691        /* Do we have HEAD? */
1692        if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, head_oid.hash, NULL))
1693                return NULL;
1694        head_commit = lookup_commit_reference_gently(&head_oid, 1);
1695        if (!head_commit)
1696                return NULL;
1697
1698        /* Turn "ONE" into "ONE..HEAD" then */
1699        obj->flags |= UNINTERESTING;
1700        add_pending_object(revs, &head_commit->object, "HEAD");
1701
1702        if (name_p)
1703                *name_p = revs->pending.objects[0].name;
1704        return (struct commit *)obj;
1705}
1706
1707static struct commit *find_single_initial(struct rev_info *revs,
1708                                          const char **name_p)
1709{
1710        int i;
1711        struct commit *found = NULL;
1712        const char *name = NULL;
1713
1714        /*
1715         * There must be one and only one negative commit, and it must be
1716         * the boundary.
1717         */
1718        for (i = 0; i < revs->pending.nr; i++) {
1719                struct object *obj = revs->pending.objects[i].item;
1720                if (!(obj->flags & UNINTERESTING))
1721                        continue;
1722                obj = deref_tag(obj, NULL, 0);
1723                if (obj->type != OBJ_COMMIT)
1724                        die("Non commit %s?", revs->pending.objects[i].name);
1725                if (found)
1726                        die("More than one commit to dig up from, %s and %s?",
1727                            revs->pending.objects[i].name, name);
1728                found = (struct commit *) obj;
1729                name = revs->pending.objects[i].name;
1730        }
1731
1732        if (!name)
1733                found = dwim_reverse_initial(revs, &name);
1734        if (!name)
1735                die("No commit to dig up from?");
1736
1737        if (name_p)
1738                *name_p = xstrdup(name);
1739        return found;
1740}
1741
1742void init_scoreboard(struct blame_scoreboard *sb)
1743{
1744        memset(sb, 0, sizeof(struct blame_scoreboard));
1745        sb->move_score = BLAME_DEFAULT_MOVE_SCORE;
1746        sb->copy_score = BLAME_DEFAULT_COPY_SCORE;
1747}
1748
1749void setup_scoreboard(struct blame_scoreboard *sb, const char *path, struct blame_origin **orig)
1750{
1751        const char *final_commit_name = NULL;
1752        struct blame_origin *o;
1753        struct commit *final_commit = NULL;
1754        enum object_type type;
1755
1756        if (sb->reverse && sb->contents_from)
1757                die(_("--contents and --reverse do not blend well."));
1758
1759        if (!sb->reverse) {
1760                sb->final = find_single_final(sb->revs, &final_commit_name);
1761                sb->commits.compare = compare_commits_by_commit_date;
1762        } else {
1763                sb->final = find_single_initial(sb->revs, &final_commit_name);
1764                sb->commits.compare = compare_commits_by_reverse_commit_date;
1765        }
1766
1767        if (sb->final && sb->contents_from)
1768                die(_("cannot use --contents with final commit object name"));
1769
1770        if (sb->reverse && sb->revs->first_parent_only)
1771                sb->revs->children.name = NULL;
1772
1773        if (!sb->final) {
1774                /*
1775                 * "--not A B -- path" without anything positive;
1776                 * do not default to HEAD, but use the working tree
1777                 * or "--contents".
1778                 */
1779                setup_work_tree();
1780                sb->final = fake_working_tree_commit(&sb->revs->diffopt,
1781                                                     path, sb->contents_from);
1782                add_pending_object(sb->revs, &(sb->final->object), ":");
1783        }
1784
1785        if (sb->reverse && sb->revs->first_parent_only) {
1786                final_commit = find_single_final(sb->revs, NULL);
1787                if (!final_commit)
1788                        die(_("--reverse and --first-parent together require specified latest commit"));
1789        }
1790
1791        /*
1792         * If we have bottom, this will mark the ancestors of the
1793         * bottom commits we would reach while traversing as
1794         * uninteresting.
1795         */
1796        if (prepare_revision_walk(sb->revs))
1797                die(_("revision walk setup failed"));
1798
1799        if (sb->reverse && sb->revs->first_parent_only) {
1800                struct commit *c = final_commit;
1801
1802                sb->revs->children.name = "children";
1803                while (c->parents &&
1804                       oidcmp(&c->object.oid, &sb->final->object.oid)) {
1805                        struct commit_list *l = xcalloc(1, sizeof(*l));
1806
1807                        l->item = c;
1808                        if (add_decoration(&sb->revs->children,
1809                                           &c->parents->item->object, l))
1810                                die("BUG: not unique item in first-parent chain");
1811                        c = c->parents->item;
1812                }
1813
1814                if (oidcmp(&c->object.oid, &sb->final->object.oid))
1815                        die(_("--reverse --first-parent together require range along first-parent chain"));
1816        }
1817
1818        if (is_null_oid(&sb->final->object.oid)) {
1819                o = sb->final->util;
1820                sb->final_buf = xmemdupz(o->file.ptr, o->file.size);
1821                sb->final_buf_size = o->file.size;
1822        }
1823        else {
1824                o = get_origin(sb->final, path);
1825                if (fill_blob_sha1_and_mode(o))
1826                        die(_("no such path %s in %s"), path, final_commit_name);
1827
1828                if (DIFF_OPT_TST(&sb->revs->diffopt, ALLOW_TEXTCONV) &&
1829                    textconv_object(path, o->mode, &o->blob_oid, 1, (char **) &sb->final_buf,
1830                                    &sb->final_buf_size))
1831                        ;
1832                else
1833                        sb->final_buf = read_sha1_file(o->blob_oid.hash, &type,
1834                                                       &sb->final_buf_size);
1835
1836                if (!sb->final_buf)
1837                        die(_("cannot read blob %s for path %s"),
1838                            oid_to_hex(&o->blob_oid),
1839                            path);
1840        }
1841        sb->num_read_blob++;
1842        prepare_lines(sb);
1843
1844        if (orig)
1845                *orig = o;
1846
1847        free((char *)final_commit_name);
1848}
1849
1850
1851
1852struct blame_entry *blame_entry_prepend(struct blame_entry *head,
1853                                        long start, long end,
1854                                        struct blame_origin *o)
1855{
1856        struct blame_entry *new_head = xcalloc(1, sizeof(struct blame_entry));
1857        new_head->lno = start;
1858        new_head->num_lines = end - start;
1859        new_head->suspect = o;
1860        new_head->s_lno = start;
1861        new_head->next = head;
1862        blame_origin_incref(o);
1863        return new_head;
1864}