blame.con commit conditional markdown preprocessing (c8b1cd9)
   1#include "cache.h"
   2#include "refs.h"
   3#include "object-store.h"
   4#include "cache-tree.h"
   5#include "mergesort.h"
   6#include "diff.h"
   7#include "diffcore.h"
   8#include "tag.h"
   9#include "blame.h"
  10#include "alloc.h"
  11#include "commit-slab.h"
  12
  13define_commit_slab(blame_suspects, struct blame_origin *);
  14static struct blame_suspects blame_suspects;
  15
  16struct blame_origin *get_blame_suspects(struct commit *commit)
  17{
  18        struct blame_origin **result;
  19
  20        result = blame_suspects_peek(&blame_suspects, commit);
  21
  22        return result ? *result : NULL;
  23}
  24
  25static void set_blame_suspects(struct commit *commit, struct blame_origin *origin)
  26{
  27        *blame_suspects_at(&blame_suspects, commit) = origin;
  28}
  29
  30void blame_origin_decref(struct blame_origin *o)
  31{
  32        if (o && --o->refcnt <= 0) {
  33                struct blame_origin *p, *l = NULL;
  34                if (o->previous)
  35                        blame_origin_decref(o->previous);
  36                free(o->file.ptr);
  37                /* Should be present exactly once in commit chain */
  38                for (p = get_blame_suspects(o->commit); p; l = p, p = p->next) {
  39                        if (p == o) {
  40                                if (l)
  41                                        l->next = p->next;
  42                                else
  43                                        set_blame_suspects(o->commit, p->next);
  44                                free(o);
  45                                return;
  46                        }
  47                }
  48                die("internal error in blame_origin_decref");
  49        }
  50}
  51
  52/*
  53 * Given a commit and a path in it, create a new origin structure.
  54 * The callers that add blame to the scoreboard should use
  55 * get_origin() to obtain shared, refcounted copy instead of calling
  56 * this function directly.
  57 */
  58static struct blame_origin *make_origin(struct commit *commit, const char *path)
  59{
  60        struct blame_origin *o;
  61        FLEX_ALLOC_STR(o, path, path);
  62        o->commit = commit;
  63        o->refcnt = 1;
  64        o->next = get_blame_suspects(commit);
  65        set_blame_suspects(commit, o);
  66        return o;
  67}
  68
  69/*
  70 * Locate an existing origin or create a new one.
  71 * This moves the origin to front position in the commit util list.
  72 */
  73static struct blame_origin *get_origin(struct commit *commit, const char *path)
  74{
  75        struct blame_origin *o, *l;
  76
  77        for (o = get_blame_suspects(commit), l = NULL; o; l = o, o = o->next) {
  78                if (!strcmp(o->path, path)) {
  79                        /* bump to front */
  80                        if (l) {
  81                                l->next = o->next;
  82                                o->next = get_blame_suspects(commit);
  83                                set_blame_suspects(commit, o);
  84                        }
  85                        return blame_origin_incref(o);
  86                }
  87        }
  88        return make_origin(commit, path);
  89}
  90
  91
  92
  93static void verify_working_tree_path(struct repository *r,
  94                                     struct commit *work_tree, const char *path)
  95{
  96        struct commit_list *parents;
  97        int pos;
  98
  99        for (parents = work_tree->parents; parents; parents = parents->next) {
 100                const struct object_id *commit_oid = &parents->item->object.oid;
 101                struct object_id blob_oid;
 102                unsigned short mode;
 103
 104                if (!get_tree_entry(r, commit_oid, path, &blob_oid, &mode) &&
 105                    oid_object_info(r, &blob_oid, NULL) == OBJ_BLOB)
 106                        return;
 107        }
 108
 109        pos = index_name_pos(r->index, path, strlen(path));
 110        if (pos >= 0)
 111                ; /* path is in the index */
 112        else if (-1 - pos < r->index->cache_nr &&
 113                 !strcmp(r->index->cache[-1 - pos]->name, path))
 114                ; /* path is in the index, unmerged */
 115        else
 116                die("no such path '%s' in HEAD", path);
 117}
 118
 119static struct commit_list **append_parent(struct repository *r,
 120                                          struct commit_list **tail,
 121                                          const struct object_id *oid)
 122{
 123        struct commit *parent;
 124
 125        parent = lookup_commit_reference(r, oid);
 126        if (!parent)
 127                die("no such commit %s", oid_to_hex(oid));
 128        return &commit_list_insert(parent, tail)->next;
 129}
 130
 131static void append_merge_parents(struct repository *r,
 132                                 struct commit_list **tail)
 133{
 134        int merge_head;
 135        struct strbuf line = STRBUF_INIT;
 136
 137        merge_head = open(git_path_merge_head(r), O_RDONLY);
 138        if (merge_head < 0) {
 139                if (errno == ENOENT)
 140                        return;
 141                die("cannot open '%s' for reading",
 142                    git_path_merge_head(r));
 143        }
 144
 145        while (!strbuf_getwholeline_fd(&line, merge_head, '\n')) {
 146                struct object_id oid;
 147                if (line.len < GIT_SHA1_HEXSZ || get_oid_hex(line.buf, &oid))
 148                        die("unknown line in '%s': %s",
 149                            git_path_merge_head(r), line.buf);
 150                tail = append_parent(r, tail, &oid);
 151        }
 152        close(merge_head);
 153        strbuf_release(&line);
 154}
 155
 156/*
 157 * This isn't as simple as passing sb->buf and sb->len, because we
 158 * want to transfer ownership of the buffer to the commit (so we
 159 * must use detach).
 160 */
 161static void set_commit_buffer_from_strbuf(struct repository *r,
 162                                          struct commit *c,
 163                                          struct strbuf *sb)
 164{
 165        size_t len;
 166        void *buf = strbuf_detach(sb, &len);
 167        set_commit_buffer(r, c, buf, len);
 168}
 169
 170/*
 171 * Prepare a dummy commit that represents the work tree (or staged) item.
 172 * Note that annotating work tree item never works in the reverse.
 173 */
 174static struct commit *fake_working_tree_commit(struct repository *r,
 175                                               struct diff_options *opt,
 176                                               const char *path,
 177                                               const char *contents_from)
 178{
 179        struct commit *commit;
 180        struct blame_origin *origin;
 181        struct commit_list **parent_tail, *parent;
 182        struct object_id head_oid;
 183        struct strbuf buf = STRBUF_INIT;
 184        const char *ident;
 185        time_t now;
 186        int len;
 187        struct cache_entry *ce;
 188        unsigned mode;
 189        struct strbuf msg = STRBUF_INIT;
 190
 191        repo_read_index(r);
 192        time(&now);
 193        commit = alloc_commit_node(r);
 194        commit->object.parsed = 1;
 195        commit->date = now;
 196        parent_tail = &commit->parents;
 197
 198        if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL))
 199                die("no such ref: HEAD");
 200
 201        parent_tail = append_parent(r, parent_tail, &head_oid);
 202        append_merge_parents(r, parent_tail);
 203        verify_working_tree_path(r, commit, path);
 204
 205        origin = make_origin(commit, path);
 206
 207        ident = fmt_ident("Not Committed Yet", "not.committed.yet",
 208                        WANT_BLANK_IDENT, NULL, 0);
 209        strbuf_addstr(&msg, "tree 0000000000000000000000000000000000000000\n");
 210        for (parent = commit->parents; parent; parent = parent->next)
 211                strbuf_addf(&msg, "parent %s\n",
 212                            oid_to_hex(&parent->item->object.oid));
 213        strbuf_addf(&msg,
 214                    "author %s\n"
 215                    "committer %s\n\n"
 216                    "Version of %s from %s\n",
 217                    ident, ident, path,
 218                    (!contents_from ? path :
 219                     (!strcmp(contents_from, "-") ? "standard input" : contents_from)));
 220        set_commit_buffer_from_strbuf(r, commit, &msg);
 221
 222        if (!contents_from || strcmp("-", contents_from)) {
 223                struct stat st;
 224                const char *read_from;
 225                char *buf_ptr;
 226                unsigned long buf_len;
 227
 228                if (contents_from) {
 229                        if (stat(contents_from, &st) < 0)
 230                                die_errno("Cannot stat '%s'", contents_from);
 231                        read_from = contents_from;
 232                }
 233                else {
 234                        if (lstat(path, &st) < 0)
 235                                die_errno("Cannot lstat '%s'", path);
 236                        read_from = path;
 237                }
 238                mode = canon_mode(st.st_mode);
 239
 240                switch (st.st_mode & S_IFMT) {
 241                case S_IFREG:
 242                        if (opt->flags.allow_textconv &&
 243                            textconv_object(r, read_from, mode, &null_oid, 0, &buf_ptr, &buf_len))
 244                                strbuf_attach(&buf, buf_ptr, buf_len, buf_len + 1);
 245                        else if (strbuf_read_file(&buf, read_from, st.st_size) != st.st_size)
 246                                die_errno("cannot open or read '%s'", read_from);
 247                        break;
 248                case S_IFLNK:
 249                        if (strbuf_readlink(&buf, read_from, st.st_size) < 0)
 250                                die_errno("cannot readlink '%s'", read_from);
 251                        break;
 252                default:
 253                        die("unsupported file type %s", read_from);
 254                }
 255        }
 256        else {
 257                /* Reading from stdin */
 258                mode = 0;
 259                if (strbuf_read(&buf, 0, 0) < 0)
 260                        die_errno("failed to read from stdin");
 261        }
 262        convert_to_git(r->index, path, buf.buf, buf.len, &buf, 0);
 263        origin->file.ptr = buf.buf;
 264        origin->file.size = buf.len;
 265        pretend_object_file(buf.buf, buf.len, OBJ_BLOB, &origin->blob_oid);
 266
 267        /*
 268         * Read the current index, replace the path entry with
 269         * origin->blob_sha1 without mucking with its mode or type
 270         * bits; we are not going to write this index out -- we just
 271         * want to run "diff-index --cached".
 272         */
 273        discard_index(r->index);
 274        repo_read_index(r);
 275
 276        len = strlen(path);
 277        if (!mode) {
 278                int pos = index_name_pos(r->index, path, len);
 279                if (0 <= pos)
 280                        mode = r->index->cache[pos]->ce_mode;
 281                else
 282                        /* Let's not bother reading from HEAD tree */
 283                        mode = S_IFREG | 0644;
 284        }
 285        ce = make_empty_cache_entry(r->index, len);
 286        oidcpy(&ce->oid, &origin->blob_oid);
 287        memcpy(ce->name, path, len);
 288        ce->ce_flags = create_ce_flags(0);
 289        ce->ce_namelen = len;
 290        ce->ce_mode = create_ce_mode(mode);
 291        add_index_entry(r->index, ce,
 292                        ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 293
 294        cache_tree_invalidate_path(r->index, path);
 295
 296        return commit;
 297}
 298
 299
 300
 301static int diff_hunks(mmfile_t *file_a, mmfile_t *file_b,
 302                      xdl_emit_hunk_consume_func_t hunk_func, void *cb_data, int xdl_opts)
 303{
 304        xpparam_t xpp = {0};
 305        xdemitconf_t xecfg = {0};
 306        xdemitcb_t ecb = {NULL};
 307
 308        xpp.flags = xdl_opts;
 309        xecfg.hunk_func = hunk_func;
 310        ecb.priv = cb_data;
 311        return xdi_diff(file_a, file_b, &xpp, &xecfg, &ecb);
 312}
 313
 314static const char *get_next_line(const char *start, const char *end)
 315{
 316        const char *nl = memchr(start, '\n', end - start);
 317
 318        return nl ? nl + 1 : end;
 319}
 320
 321static int find_line_starts(int **line_starts, const char *buf,
 322                            unsigned long len)
 323{
 324        const char *end = buf + len;
 325        const char *p;
 326        int *lineno;
 327        int num = 0;
 328
 329        for (p = buf; p < end; p = get_next_line(p, end))
 330                num++;
 331
 332        ALLOC_ARRAY(*line_starts, num + 1);
 333        lineno = *line_starts;
 334
 335        for (p = buf; p < end; p = get_next_line(p, end))
 336                *lineno++ = p - buf;
 337
 338        *lineno = len;
 339
 340        return num;
 341}
 342
 343struct fingerprint_entry;
 344
 345/* A fingerprint is intended to loosely represent a string, such that two
 346 * fingerprints can be quickly compared to give an indication of the similarity
 347 * of the strings that they represent.
 348 *
 349 * A fingerprint is represented as a multiset of the lower-cased byte pairs in
 350 * the string that it represents. Whitespace is added at each end of the
 351 * string. Whitespace pairs are ignored. Whitespace is converted to '\0'.
 352 * For example, the string "Darth   Radar" will be converted to the following
 353 * fingerprint:
 354 * {"\0d", "da", "da", "ar", "ar", "rt", "th", "h\0", "\0r", "ra", "ad", "r\0"}
 355 *
 356 * The similarity between two fingerprints is the size of the intersection of
 357 * their multisets, including repeated elements. See fingerprint_similarity for
 358 * examples.
 359 *
 360 * For ease of implementation, the fingerprint is implemented as a map
 361 * of byte pairs to the count of that byte pair in the string, instead of
 362 * allowing repeated elements in a set.
 363 */
 364struct fingerprint {
 365        struct hashmap map;
 366        /* As we know the maximum number of entries in advance, it's
 367         * convenient to store the entries in a single array instead of having
 368         * the hashmap manage the memory.
 369         */
 370        struct fingerprint_entry *entries;
 371};
 372
 373/* A byte pair in a fingerprint. Stores the number of times the byte pair
 374 * occurs in the string that the fingerprint represents.
 375 */
 376struct fingerprint_entry {
 377        /* The hashmap entry - the hash represents the byte pair in its
 378         * entirety so we don't need to store the byte pair separately.
 379         */
 380        struct hashmap_entry entry;
 381        /* The number of times the byte pair occurs in the string that the
 382         * fingerprint represents.
 383         */
 384        int count;
 385};
 386
 387/* See `struct fingerprint` for an explanation of what a fingerprint is.
 388 * \param result the fingerprint of the string is stored here. This must be
 389 *               freed later using free_fingerprint.
 390 * \param line_begin the start of the string
 391 * \param line_end the end of the string
 392 */
 393static void get_fingerprint(struct fingerprint *result,
 394                            const char *line_begin,
 395                            const char *line_end)
 396{
 397        unsigned int hash, c0 = 0, c1;
 398        const char *p;
 399        int max_map_entry_count = 1 + line_end - line_begin;
 400        struct fingerprint_entry *entry = xcalloc(max_map_entry_count,
 401                sizeof(struct fingerprint_entry));
 402        struct fingerprint_entry *found_entry;
 403
 404        hashmap_init(&result->map, NULL, NULL, max_map_entry_count);
 405        result->entries = entry;
 406        for (p = line_begin; p <= line_end; ++p, c0 = c1) {
 407                /* Always terminate the string with whitespace.
 408                 * Normalise whitespace to 0, and normalise letters to
 409                 * lower case. This won't work for multibyte characters but at
 410                 * worst will match some unrelated characters.
 411                 */
 412                if ((p == line_end) || isspace(*p))
 413                        c1 = 0;
 414                else
 415                        c1 = tolower(*p);
 416                hash = c0 | (c1 << 8);
 417                /* Ignore whitespace pairs */
 418                if (hash == 0)
 419                        continue;
 420                hashmap_entry_init(entry, hash);
 421
 422                found_entry = hashmap_get(&result->map, entry, NULL);
 423                if (found_entry) {
 424                        found_entry->count += 1;
 425                } else {
 426                        entry->count = 1;
 427                        hashmap_add(&result->map, entry);
 428                        ++entry;
 429                }
 430        }
 431}
 432
 433static void free_fingerprint(struct fingerprint *f)
 434{
 435        hashmap_free(&f->map, 0);
 436        free(f->entries);
 437}
 438
 439/* Calculates the similarity between two fingerprints as the size of the
 440 * intersection of their multisets, including repeated elements. See
 441 * `struct fingerprint` for an explanation of the fingerprint representation.
 442 * The similarity between "cat mat" and "father rather" is 2 because "at" is
 443 * present twice in both strings while the similarity between "tim" and "mit"
 444 * is 0.
 445 */
 446static int fingerprint_similarity(struct fingerprint *a, struct fingerprint *b)
 447{
 448        int intersection = 0;
 449        struct hashmap_iter iter;
 450        const struct fingerprint_entry *entry_a, *entry_b;
 451
 452        hashmap_iter_init(&b->map, &iter);
 453
 454        while ((entry_b = hashmap_iter_next(&iter))) {
 455                if ((entry_a = hashmap_get(&a->map, entry_b, NULL))) {
 456                        intersection += entry_a->count < entry_b->count ?
 457                                        entry_a->count : entry_b->count;
 458                }
 459        }
 460        return intersection;
 461}
 462
 463/* Subtracts byte-pair elements in B from A, modifying A in place.
 464 */
 465static void fingerprint_subtract(struct fingerprint *a, struct fingerprint *b)
 466{
 467        struct hashmap_iter iter;
 468        struct fingerprint_entry *entry_a;
 469        const struct fingerprint_entry *entry_b;
 470
 471        hashmap_iter_init(&b->map, &iter);
 472
 473        while ((entry_b = hashmap_iter_next(&iter))) {
 474                if ((entry_a = hashmap_get(&a->map, entry_b, NULL))) {
 475                        if (entry_a->count <= entry_b->count)
 476                                hashmap_remove(&a->map, entry_b, NULL);
 477                        else
 478                                entry_a->count -= entry_b->count;
 479                }
 480        }
 481}
 482
 483/* Calculate fingerprints for a series of lines.
 484 * Puts the fingerprints in the fingerprints array, which must have been
 485 * preallocated to allow storing line_count elements.
 486 */
 487static void get_line_fingerprints(struct fingerprint *fingerprints,
 488                                  const char *content, const int *line_starts,
 489                                  long first_line, long line_count)
 490{
 491        int i;
 492        const char *linestart, *lineend;
 493
 494        line_starts += first_line;
 495        for (i = 0; i < line_count; ++i) {
 496                linestart = content + line_starts[i];
 497                lineend = content + line_starts[i + 1];
 498                get_fingerprint(fingerprints + i, linestart, lineend);
 499        }
 500}
 501
 502static void free_line_fingerprints(struct fingerprint *fingerprints,
 503                                   int nr_fingerprints)
 504{
 505        int i;
 506
 507        for (i = 0; i < nr_fingerprints; i++)
 508                free_fingerprint(&fingerprints[i]);
 509}
 510
 511/* This contains the data necessary to linearly map a line number in one half
 512 * of a diff chunk to the line in the other half of the diff chunk that is
 513 * closest in terms of its position as a fraction of the length of the chunk.
 514 */
 515struct line_number_mapping {
 516        int destination_start, destination_length,
 517                source_start, source_length;
 518};
 519
 520/* Given a line number in one range, offset and scale it to map it onto the
 521 * other range.
 522 * Essentially this mapping is a simple linear equation but the calculation is
 523 * more complicated to allow performing it with integer operations.
 524 * Another complication is that if a line could map onto many lines in the
 525 * destination range then we want to choose the line at the center of those
 526 * possibilities.
 527 * Example: if the chunk is 2 lines long in A and 10 lines long in B then the
 528 * first 5 lines in B will map onto the first line in the A chunk, while the
 529 * last 5 lines will all map onto the second line in the A chunk.
 530 * Example: if the chunk is 10 lines long in A and 2 lines long in B then line
 531 * 0 in B will map onto line 2 in A, and line 1 in B will map onto line 7 in A.
 532 */
 533static int map_line_number(int line_number,
 534        const struct line_number_mapping *mapping)
 535{
 536        return ((line_number - mapping->source_start) * 2 + 1) *
 537               mapping->destination_length /
 538               (mapping->source_length * 2) +
 539               mapping->destination_start;
 540}
 541
 542/* Get a pointer to the element storing the similarity between a line in A
 543 * and a line in B.
 544 *
 545 * The similarities are stored in a 2-dimensional array. Each "row" in the
 546 * array contains the similarities for a line in B. The similarities stored in
 547 * a row are the similarities between the line in B and the nearby lines in A.
 548 * To keep the length of each row the same, it is padded out with values of -1
 549 * where the search range extends beyond the lines in A.
 550 * For example, if max_search_distance_a is 2 and the two sides of a diff chunk
 551 * look like this:
 552 * a | m
 553 * b | n
 554 * c | o
 555 * d | p
 556 * e | q
 557 * Then the similarity array will contain:
 558 * [-1, -1, am, bm, cm,
 559 *  -1, an, bn, cn, dn,
 560 *  ao, bo, co, do, eo,
 561 *  bp, cp, dp, ep, -1,
 562 *  cq, dq, eq, -1, -1]
 563 * Where similarities are denoted either by -1 for invalid, or the
 564 * concatenation of the two lines in the diff being compared.
 565 *
 566 * \param similarities array of similarities between lines in A and B
 567 * \param line_a the index of the line in A, in the same frame of reference as
 568 *      closest_line_a.
 569 * \param local_line_b the index of the line in B, relative to the first line
 570 *                     in B that similarities represents.
 571 * \param closest_line_a the index of the line in A that is deemed to be
 572 *                       closest to local_line_b. This must be in the same
 573 *                       frame of reference as line_a. This value defines
 574 *                       where similarities is centered for the line in B.
 575 * \param max_search_distance_a maximum distance in lines from the closest line
 576 *                              in A for other lines in A for which
 577 *                              similarities may be calculated.
 578 */
 579static int *get_similarity(int *similarities,
 580                           int line_a, int local_line_b,
 581                           int closest_line_a, int max_search_distance_a)
 582{
 583        assert(abs(line_a - closest_line_a) <=
 584               max_search_distance_a);
 585        return similarities + line_a - closest_line_a +
 586               max_search_distance_a +
 587               local_line_b * (max_search_distance_a * 2 + 1);
 588}
 589
 590#define CERTAIN_NOTHING_MATCHES -2
 591#define CERTAINTY_NOT_CALCULATED -1
 592
 593/* Given a line in B, first calculate its similarities with nearby lines in A
 594 * if not already calculated, then identify the most similar and second most
 595 * similar lines. The "certainty" is calculated based on those two
 596 * similarities.
 597 *
 598 * \param start_a the index of the first line of the chunk in A
 599 * \param length_a the length in lines of the chunk in A
 600 * \param local_line_b the index of the line in B, relative to the first line
 601 *                     in the chunk.
 602 * \param fingerprints_a array of fingerprints for the chunk in A
 603 * \param fingerprints_b array of fingerprints for the chunk in B
 604 * \param similarities 2-dimensional array of similarities between lines in A
 605 *                     and B. See get_similarity() for more details.
 606 * \param certainties array of values indicating how strongly a line in B is
 607 *                    matched with some line in A.
 608 * \param second_best_result array of absolute indices in A for the second
 609 *                           closest match of a line in B.
 610 * \param result array of absolute indices in A for the closest match of a line
 611 *               in B.
 612 * \param max_search_distance_a maximum distance in lines from the closest line
 613 *                              in A for other lines in A for which
 614 *                              similarities may be calculated.
 615 * \param map_line_number_in_b_to_a parameter to map_line_number().
 616 */
 617static void find_best_line_matches(
 618        int start_a,
 619        int length_a,
 620        int start_b,
 621        int local_line_b,
 622        struct fingerprint *fingerprints_a,
 623        struct fingerprint *fingerprints_b,
 624        int *similarities,
 625        int *certainties,
 626        int *second_best_result,
 627        int *result,
 628        const int max_search_distance_a,
 629        const struct line_number_mapping *map_line_number_in_b_to_a)
 630{
 631
 632        int i, search_start, search_end, closest_local_line_a, *similarity,
 633                best_similarity = 0, second_best_similarity = 0,
 634                best_similarity_index = 0, second_best_similarity_index = 0;
 635
 636        /* certainty has already been calculated so no need to redo the work */
 637        if (certainties[local_line_b] != CERTAINTY_NOT_CALCULATED)
 638                return;
 639
 640        closest_local_line_a = map_line_number(
 641                local_line_b + start_b, map_line_number_in_b_to_a) - start_a;
 642
 643        search_start = closest_local_line_a - max_search_distance_a;
 644        if (search_start < 0)
 645                search_start = 0;
 646
 647        search_end = closest_local_line_a + max_search_distance_a + 1;
 648        if (search_end > length_a)
 649                search_end = length_a;
 650
 651        for (i = search_start; i < search_end; ++i) {
 652                similarity = get_similarity(similarities,
 653                                            i, local_line_b,
 654                                            closest_local_line_a,
 655                                            max_search_distance_a);
 656                if (*similarity == -1) {
 657                        /* This value will never exceed 10 but assert just in
 658                         * case
 659                         */
 660                        assert(abs(i - closest_local_line_a) < 1000);
 661                        /* scale the similarity by (1000 - distance from
 662                         * closest line) to act as a tie break between lines
 663                         * that otherwise are equally similar.
 664                         */
 665                        *similarity = fingerprint_similarity(
 666                                fingerprints_b + local_line_b,
 667                                fingerprints_a + i) *
 668                                (1000 - abs(i - closest_local_line_a));
 669                }
 670                if (*similarity > best_similarity) {
 671                        second_best_similarity = best_similarity;
 672                        second_best_similarity_index = best_similarity_index;
 673                        best_similarity = *similarity;
 674                        best_similarity_index = i;
 675                } else if (*similarity > second_best_similarity) {
 676                        second_best_similarity = *similarity;
 677                        second_best_similarity_index = i;
 678                }
 679        }
 680
 681        if (best_similarity == 0) {
 682                /* this line definitely doesn't match with anything. Mark it
 683                 * with this special value so it doesn't get invalidated and
 684                 * won't be recalculated.
 685                 */
 686                certainties[local_line_b] = CERTAIN_NOTHING_MATCHES;
 687                result[local_line_b] = -1;
 688        } else {
 689                /* Calculate the certainty with which this line matches.
 690                 * If the line matches well with two lines then that reduces
 691                 * the certainty. However we still want to prioritise matching
 692                 * a line that matches very well with two lines over matching a
 693                 * line that matches poorly with one line, hence doubling
 694                 * best_similarity.
 695                 * This means that if we have
 696                 * line X that matches only one line with a score of 3,
 697                 * line Y that matches two lines equally with a score of 5,
 698                 * and line Z that matches only one line with a score or 2,
 699                 * then the lines in order of certainty are X, Y, Z.
 700                 */
 701                certainties[local_line_b] = best_similarity * 2 -
 702                        second_best_similarity;
 703
 704                /* We keep both the best and second best results to allow us to
 705                 * check at a later stage of the matching process whether the
 706                 * result needs to be invalidated.
 707                 */
 708                result[local_line_b] = start_a + best_similarity_index;
 709                second_best_result[local_line_b] =
 710                        start_a + second_best_similarity_index;
 711        }
 712}
 713
 714/*
 715 * This finds the line that we can match with the most confidence, and
 716 * uses it as a partition. It then calls itself on the lines on either side of
 717 * that partition. In this way we avoid lines appearing out of order, and
 718 * retain a sensible line ordering.
 719 * \param start_a index of the first line in A with which lines in B may be
 720 *                compared.
 721 * \param start_b index of the first line in B for which matching should be
 722 *                done.
 723 * \param length_a number of lines in A with which lines in B may be compared.
 724 * \param length_b number of lines in B for which matching should be done.
 725 * \param fingerprints_a mutable array of fingerprints in A. The first element
 726 *                       corresponds to the line at start_a.
 727 * \param fingerprints_b array of fingerprints in B. The first element
 728 *                       corresponds to the line at start_b.
 729 * \param similarities 2-dimensional array of similarities between lines in A
 730 *                     and B. See get_similarity() for more details.
 731 * \param certainties array of values indicating how strongly a line in B is
 732 *                    matched with some line in A.
 733 * \param second_best_result array of absolute indices in A for the second
 734 *                           closest match of a line in B.
 735 * \param result array of absolute indices in A for the closest match of a line
 736 *               in B.
 737 * \param max_search_distance_a maximum distance in lines from the closest line
 738 *                            in A for other lines in A for which
 739 *                            similarities may be calculated.
 740 * \param max_search_distance_b an upper bound on the greatest possible
 741 *                            distance between lines in B such that they will
 742 *                              both be compared with the same line in A
 743 *                            according to max_search_distance_a.
 744 * \param map_line_number_in_b_to_a parameter to map_line_number().
 745 */
 746static void fuzzy_find_matching_lines_recurse(
 747        int start_a, int start_b,
 748        int length_a, int length_b,
 749        struct fingerprint *fingerprints_a,
 750        struct fingerprint *fingerprints_b,
 751        int *similarities,
 752        int *certainties,
 753        int *second_best_result,
 754        int *result,
 755        int max_search_distance_a,
 756        int max_search_distance_b,
 757        const struct line_number_mapping *map_line_number_in_b_to_a)
 758{
 759        int i, invalidate_min, invalidate_max, offset_b,
 760                second_half_start_a, second_half_start_b,
 761                second_half_length_a, second_half_length_b,
 762                most_certain_line_a, most_certain_local_line_b = -1,
 763                most_certain_line_certainty = -1,
 764                closest_local_line_a;
 765
 766        for (i = 0; i < length_b; ++i) {
 767                find_best_line_matches(start_a,
 768                                       length_a,
 769                                       start_b,
 770                                       i,
 771                                       fingerprints_a,
 772                                       fingerprints_b,
 773                                       similarities,
 774                                       certainties,
 775                                       second_best_result,
 776                                       result,
 777                                       max_search_distance_a,
 778                                       map_line_number_in_b_to_a);
 779
 780                if (certainties[i] > most_certain_line_certainty) {
 781                        most_certain_line_certainty = certainties[i];
 782                        most_certain_local_line_b = i;
 783                }
 784        }
 785
 786        /* No matches. */
 787        if (most_certain_local_line_b == -1)
 788                return;
 789
 790        most_certain_line_a = result[most_certain_local_line_b];
 791
 792        /*
 793         * Subtract the most certain line's fingerprint in B from the matched
 794         * fingerprint in A. This means that other lines in B can't also match
 795         * the same parts of the line in A.
 796         */
 797        fingerprint_subtract(fingerprints_a + most_certain_line_a - start_a,
 798                             fingerprints_b + most_certain_local_line_b);
 799
 800        /* Invalidate results that may be affected by the choice of most
 801         * certain line.
 802         */
 803        invalidate_min = most_certain_local_line_b - max_search_distance_b;
 804        invalidate_max = most_certain_local_line_b + max_search_distance_b + 1;
 805        if (invalidate_min < 0)
 806                invalidate_min = 0;
 807        if (invalidate_max > length_b)
 808                invalidate_max = length_b;
 809
 810        /* As the fingerprint in A has changed, discard previously calculated
 811         * similarity values with that fingerprint.
 812         */
 813        for (i = invalidate_min; i < invalidate_max; ++i) {
 814                closest_local_line_a = map_line_number(
 815                        i + start_b, map_line_number_in_b_to_a) - start_a;
 816
 817                /* Check that the lines in A and B are close enough that there
 818                 * is a similarity value for them.
 819                 */
 820                if (abs(most_certain_line_a - start_a - closest_local_line_a) >
 821                        max_search_distance_a) {
 822                        continue;
 823                }
 824
 825                *get_similarity(similarities, most_certain_line_a - start_a,
 826                                i, closest_local_line_a,
 827                                max_search_distance_a) = -1;
 828        }
 829
 830        /* More invalidating of results that may be affected by the choice of
 831         * most certain line.
 832         * Discard the matches for lines in B that are currently matched with a
 833         * line in A such that their ordering contradicts the ordering imposed
 834         * by the choice of most certain line.
 835         */
 836        for (i = most_certain_local_line_b - 1; i >= invalidate_min; --i) {
 837                /* In this loop we discard results for lines in B that are
 838                 * before most-certain-line-B but are matched with a line in A
 839                 * that is after most-certain-line-A.
 840                 */
 841                if (certainties[i] >= 0 &&
 842                    (result[i] >= most_certain_line_a ||
 843                     second_best_result[i] >= most_certain_line_a)) {
 844                        certainties[i] = CERTAINTY_NOT_CALCULATED;
 845                }
 846        }
 847        for (i = most_certain_local_line_b + 1; i < invalidate_max; ++i) {
 848                /* In this loop we discard results for lines in B that are
 849                 * after most-certain-line-B but are matched with a line in A
 850                 * that is before most-certain-line-A.
 851                 */
 852                if (certainties[i] >= 0 &&
 853                    (result[i] <= most_certain_line_a ||
 854                     second_best_result[i] <= most_certain_line_a)) {
 855                        certainties[i] = CERTAINTY_NOT_CALCULATED;
 856                }
 857        }
 858
 859        /* Repeat the matching process for lines before the most certain line.
 860         */
 861        if (most_certain_local_line_b > 0) {
 862                fuzzy_find_matching_lines_recurse(
 863                        start_a, start_b,
 864                        most_certain_line_a + 1 - start_a,
 865                        most_certain_local_line_b,
 866                        fingerprints_a, fingerprints_b, similarities,
 867                        certainties, second_best_result, result,
 868                        max_search_distance_a,
 869                        max_search_distance_b,
 870                        map_line_number_in_b_to_a);
 871        }
 872        /* Repeat the matching process for lines after the most certain line.
 873         */
 874        if (most_certain_local_line_b + 1 < length_b) {
 875                second_half_start_a = most_certain_line_a;
 876                offset_b = most_certain_local_line_b + 1;
 877                second_half_start_b = start_b + offset_b;
 878                second_half_length_a =
 879                        length_a + start_a - second_half_start_a;
 880                second_half_length_b =
 881                        length_b + start_b - second_half_start_b;
 882                fuzzy_find_matching_lines_recurse(
 883                        second_half_start_a, second_half_start_b,
 884                        second_half_length_a, second_half_length_b,
 885                        fingerprints_a + second_half_start_a - start_a,
 886                        fingerprints_b + offset_b,
 887                        similarities +
 888                                offset_b * (max_search_distance_a * 2 + 1),
 889                        certainties + offset_b,
 890                        second_best_result + offset_b, result + offset_b,
 891                        max_search_distance_a,
 892                        max_search_distance_b,
 893                        map_line_number_in_b_to_a);
 894        }
 895}
 896
 897/* Find the lines in the parent line range that most closely match the lines in
 898 * the target line range. This is accomplished by matching fingerprints in each
 899 * blame_origin, and choosing the best matches that preserve the line ordering.
 900 * See struct fingerprint for details of fingerprint matching, and
 901 * fuzzy_find_matching_lines_recurse for details of preserving line ordering.
 902 *
 903 * The performance is believed to be O(n log n) in the typical case and O(n^2)
 904 * in a pathological case, where n is the number of lines in the target range.
 905 */
 906static int *fuzzy_find_matching_lines(struct blame_origin *parent,
 907                                      struct blame_origin *target,
 908                                      int tlno, int parent_slno, int same,
 909                                      int parent_len)
 910{
 911        /* We use the terminology "A" for the left hand side of the diff AKA
 912         * parent, and "B" for the right hand side of the diff AKA target. */
 913        int start_a = parent_slno;
 914        int length_a = parent_len;
 915        int start_b = tlno;
 916        int length_b = same - tlno;
 917
 918        struct line_number_mapping map_line_number_in_b_to_a = {
 919                start_a, length_a, start_b, length_b
 920        };
 921
 922        struct fingerprint *fingerprints_a = parent->fingerprints;
 923        struct fingerprint *fingerprints_b = target->fingerprints;
 924
 925        int i, *result, *second_best_result,
 926                *certainties, *similarities, similarity_count;
 927
 928        /*
 929         * max_search_distance_a means that given a line in B, compare it to
 930         * the line in A that is closest to its position, and the lines in A
 931         * that are no greater than max_search_distance_a lines away from the
 932         * closest line in A.
 933         *
 934         * max_search_distance_b is an upper bound on the greatest possible
 935         * distance between lines in B such that they will both be compared
 936         * with the same line in A according to max_search_distance_a.
 937         */
 938        int max_search_distance_a = 10, max_search_distance_b;
 939
 940        if (length_a <= 0)
 941                return NULL;
 942
 943        if (max_search_distance_a >= length_a)
 944                max_search_distance_a = length_a ? length_a - 1 : 0;
 945
 946        max_search_distance_b = ((2 * max_search_distance_a + 1) * length_b
 947                                 - 1) / length_a;
 948
 949        result = xcalloc(sizeof(int), length_b);
 950        second_best_result = xcalloc(sizeof(int), length_b);
 951        certainties = xcalloc(sizeof(int), length_b);
 952
 953        /* See get_similarity() for details of similarities. */
 954        similarity_count = length_b * (max_search_distance_a * 2 + 1);
 955        similarities = xcalloc(sizeof(int), similarity_count);
 956
 957        for (i = 0; i < length_b; ++i) {
 958                result[i] = -1;
 959                second_best_result[i] = -1;
 960                certainties[i] = CERTAINTY_NOT_CALCULATED;
 961        }
 962
 963        for (i = 0; i < similarity_count; ++i)
 964                similarities[i] = -1;
 965
 966        fuzzy_find_matching_lines_recurse(start_a, start_b,
 967                                          length_a, length_b,
 968                                          fingerprints_a + start_a,
 969                                          fingerprints_b + start_b,
 970                                          similarities,
 971                                          certainties,
 972                                          second_best_result,
 973                                          result,
 974                                          max_search_distance_a,
 975                                          max_search_distance_b,
 976                                          &map_line_number_in_b_to_a);
 977
 978        free(similarities);
 979        free(certainties);
 980        free(second_best_result);
 981
 982        return result;
 983}
 984
 985static void fill_origin_fingerprints(struct blame_origin *o)
 986{
 987        int *line_starts;
 988
 989        if (o->fingerprints)
 990                return;
 991        o->num_lines = find_line_starts(&line_starts, o->file.ptr,
 992                                        o->file.size);
 993        o->fingerprints = xcalloc(sizeof(struct fingerprint), o->num_lines);
 994        get_line_fingerprints(o->fingerprints, o->file.ptr, line_starts,
 995                              0, o->num_lines);
 996        free(line_starts);
 997}
 998
 999static void drop_origin_fingerprints(struct blame_origin *o)
1000{
1001        if (o->fingerprints) {
1002                free_line_fingerprints(o->fingerprints, o->num_lines);
1003                o->num_lines = 0;
1004                FREE_AND_NULL(o->fingerprints);
1005        }
1006}
1007
1008/*
1009 * Given an origin, prepare mmfile_t structure to be used by the
1010 * diff machinery
1011 */
1012static void fill_origin_blob(struct diff_options *opt,
1013                             struct blame_origin *o, mmfile_t *file,
1014                             int *num_read_blob, int fill_fingerprints)
1015{
1016        if (!o->file.ptr) {
1017                enum object_type type;
1018                unsigned long file_size;
1019
1020                (*num_read_blob)++;
1021                if (opt->flags.allow_textconv &&
1022                    textconv_object(opt->repo, o->path, o->mode,
1023                                    &o->blob_oid, 1, &file->ptr, &file_size))
1024                        ;
1025                else
1026                        file->ptr = read_object_file(&o->blob_oid, &type,
1027                                                     &file_size);
1028                file->size = file_size;
1029
1030                if (!file->ptr)
1031                        die("Cannot read blob %s for path %s",
1032                            oid_to_hex(&o->blob_oid),
1033                            o->path);
1034                o->file = *file;
1035        }
1036        else
1037                *file = o->file;
1038        if (fill_fingerprints)
1039                fill_origin_fingerprints(o);
1040}
1041
1042static void drop_origin_blob(struct blame_origin *o)
1043{
1044        FREE_AND_NULL(o->file.ptr);
1045        drop_origin_fingerprints(o);
1046}
1047
1048/*
1049 * Any merge of blames happens on lists of blames that arrived via
1050 * different parents in a single suspect.  In this case, we want to
1051 * sort according to the suspect line numbers as opposed to the final
1052 * image line numbers.  The function body is somewhat longish because
1053 * it avoids unnecessary writes.
1054 */
1055
1056static struct blame_entry *blame_merge(struct blame_entry *list1,
1057                                       struct blame_entry *list2)
1058{
1059        struct blame_entry *p1 = list1, *p2 = list2,
1060                **tail = &list1;
1061
1062        if (!p1)
1063                return p2;
1064        if (!p2)
1065                return p1;
1066
1067        if (p1->s_lno <= p2->s_lno) {
1068                do {
1069                        tail = &p1->next;
1070                        if ((p1 = *tail) == NULL) {
1071                                *tail = p2;
1072                                return list1;
1073                        }
1074                } while (p1->s_lno <= p2->s_lno);
1075        }
1076        for (;;) {
1077                *tail = p2;
1078                do {
1079                        tail = &p2->next;
1080                        if ((p2 = *tail) == NULL)  {
1081                                *tail = p1;
1082                                return list1;
1083                        }
1084                } while (p1->s_lno > p2->s_lno);
1085                *tail = p1;
1086                do {
1087                        tail = &p1->next;
1088                        if ((p1 = *tail) == NULL) {
1089                                *tail = p2;
1090                                return list1;
1091                        }
1092                } while (p1->s_lno <= p2->s_lno);
1093        }
1094}
1095
1096static void *get_next_blame(const void *p)
1097{
1098        return ((struct blame_entry *)p)->next;
1099}
1100
1101static void set_next_blame(void *p1, void *p2)
1102{
1103        ((struct blame_entry *)p1)->next = p2;
1104}
1105
1106/*
1107 * Final image line numbers are all different, so we don't need a
1108 * three-way comparison here.
1109 */
1110
1111static int compare_blame_final(const void *p1, const void *p2)
1112{
1113        return ((struct blame_entry *)p1)->lno > ((struct blame_entry *)p2)->lno
1114                ? 1 : -1;
1115}
1116
1117static int compare_blame_suspect(const void *p1, const void *p2)
1118{
1119        const struct blame_entry *s1 = p1, *s2 = p2;
1120        /*
1121         * to allow for collating suspects, we sort according to the
1122         * respective pointer value as the primary sorting criterion.
1123         * The actual relation is pretty unimportant as long as it
1124         * establishes a total order.  Comparing as integers gives us
1125         * that.
1126         */
1127        if (s1->suspect != s2->suspect)
1128                return (intptr_t)s1->suspect > (intptr_t)s2->suspect ? 1 : -1;
1129        if (s1->s_lno == s2->s_lno)
1130                return 0;
1131        return s1->s_lno > s2->s_lno ? 1 : -1;
1132}
1133
1134void blame_sort_final(struct blame_scoreboard *sb)
1135{
1136        sb->ent = llist_mergesort(sb->ent, get_next_blame, set_next_blame,
1137                                  compare_blame_final);
1138}
1139
1140static int compare_commits_by_reverse_commit_date(const void *a,
1141                                                  const void *b,
1142                                                  void *c)
1143{
1144        return -compare_commits_by_commit_date(a, b, c);
1145}
1146
1147/*
1148 * For debugging -- origin is refcounted, and this asserts that
1149 * we do not underflow.
1150 */
1151static void sanity_check_refcnt(struct blame_scoreboard *sb)
1152{
1153        int baa = 0;
1154        struct blame_entry *ent;
1155
1156        for (ent = sb->ent; ent; ent = ent->next) {
1157                /* Nobody should have zero or negative refcnt */
1158                if (ent->suspect->refcnt <= 0) {
1159                        fprintf(stderr, "%s in %s has negative refcnt %d\n",
1160                                ent->suspect->path,
1161                                oid_to_hex(&ent->suspect->commit->object.oid),
1162                                ent->suspect->refcnt);
1163                        baa = 1;
1164                }
1165        }
1166        if (baa)
1167                sb->on_sanity_fail(sb, baa);
1168}
1169
1170/*
1171 * If two blame entries that are next to each other came from
1172 * contiguous lines in the same origin (i.e. <commit, path> pair),
1173 * merge them together.
1174 */
1175void blame_coalesce(struct blame_scoreboard *sb)
1176{
1177        struct blame_entry *ent, *next;
1178
1179        for (ent = sb->ent; ent && (next = ent->next); ent = next) {
1180                if (ent->suspect == next->suspect &&
1181                    ent->s_lno + ent->num_lines == next->s_lno &&
1182                    ent->ignored == next->ignored &&
1183                    ent->unblamable == next->unblamable) {
1184                        ent->num_lines += next->num_lines;
1185                        ent->next = next->next;
1186                        blame_origin_decref(next->suspect);
1187                        free(next);
1188                        ent->score = 0;
1189                        next = ent; /* again */
1190                }
1191        }
1192
1193        if (sb->debug) /* sanity */
1194                sanity_check_refcnt(sb);
1195}
1196
1197/*
1198 * Merge the given sorted list of blames into a preexisting origin.
1199 * If there were no previous blames to that commit, it is entered into
1200 * the commit priority queue of the score board.
1201 */
1202
1203static void queue_blames(struct blame_scoreboard *sb, struct blame_origin *porigin,
1204                         struct blame_entry *sorted)
1205{
1206        if (porigin->suspects)
1207                porigin->suspects = blame_merge(porigin->suspects, sorted);
1208        else {
1209                struct blame_origin *o;
1210                for (o = get_blame_suspects(porigin->commit); o; o = o->next) {
1211                        if (o->suspects) {
1212                                porigin->suspects = sorted;
1213                                return;
1214                        }
1215                }
1216                porigin->suspects = sorted;
1217                prio_queue_put(&sb->commits, porigin->commit);
1218        }
1219}
1220
1221/*
1222 * Fill the blob_sha1 field of an origin if it hasn't, so that later
1223 * call to fill_origin_blob() can use it to locate the data.  blob_sha1
1224 * for an origin is also used to pass the blame for the entire file to
1225 * the parent to detect the case where a child's blob is identical to
1226 * that of its parent's.
1227 *
1228 * This also fills origin->mode for corresponding tree path.
1229 */
1230static int fill_blob_sha1_and_mode(struct repository *r,
1231                                   struct blame_origin *origin)
1232{
1233        if (!is_null_oid(&origin->blob_oid))
1234                return 0;
1235        if (get_tree_entry(r, &origin->commit->object.oid, origin->path, &origin->blob_oid, &origin->mode))
1236                goto error_out;
1237        if (oid_object_info(r, &origin->blob_oid, NULL) != OBJ_BLOB)
1238                goto error_out;
1239        return 0;
1240 error_out:
1241        oidclr(&origin->blob_oid);
1242        origin->mode = S_IFINVALID;
1243        return -1;
1244}
1245
1246/*
1247 * We have an origin -- check if the same path exists in the
1248 * parent and return an origin structure to represent it.
1249 */
1250static struct blame_origin *find_origin(struct repository *r,
1251                                        struct commit *parent,
1252                                        struct blame_origin *origin)
1253{
1254        struct blame_origin *porigin;
1255        struct diff_options diff_opts;
1256        const char *paths[2];
1257
1258        /* First check any existing origins */
1259        for (porigin = get_blame_suspects(parent); porigin; porigin = porigin->next)
1260                if (!strcmp(porigin->path, origin->path)) {
1261                        /*
1262                         * The same path between origin and its parent
1263                         * without renaming -- the most common case.
1264                         */
1265                        return blame_origin_incref (porigin);
1266                }
1267
1268        /* See if the origin->path is different between parent
1269         * and origin first.  Most of the time they are the
1270         * same and diff-tree is fairly efficient about this.
1271         */
1272        repo_diff_setup(r, &diff_opts);
1273        diff_opts.flags.recursive = 1;
1274        diff_opts.detect_rename = 0;
1275        diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1276        paths[0] = origin->path;
1277        paths[1] = NULL;
1278
1279        parse_pathspec(&diff_opts.pathspec,
1280                       PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
1281                       PATHSPEC_LITERAL_PATH, "", paths);
1282        diff_setup_done(&diff_opts);
1283
1284        if (is_null_oid(&origin->commit->object.oid))
1285                do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
1286        else
1287                diff_tree_oid(get_commit_tree_oid(parent),
1288                              get_commit_tree_oid(origin->commit),
1289                              "", &diff_opts);
1290        diffcore_std(&diff_opts);
1291
1292        if (!diff_queued_diff.nr) {
1293                /* The path is the same as parent */
1294                porigin = get_origin(parent, origin->path);
1295                oidcpy(&porigin->blob_oid, &origin->blob_oid);
1296                porigin->mode = origin->mode;
1297        } else {
1298                /*
1299                 * Since origin->path is a pathspec, if the parent
1300                 * commit had it as a directory, we will see a whole
1301                 * bunch of deletion of files in the directory that we
1302                 * do not care about.
1303                 */
1304                int i;
1305                struct diff_filepair *p = NULL;
1306                for (i = 0; i < diff_queued_diff.nr; i++) {
1307                        const char *name;
1308                        p = diff_queued_diff.queue[i];
1309                        name = p->one->path ? p->one->path : p->two->path;
1310                        if (!strcmp(name, origin->path))
1311                                break;
1312                }
1313                if (!p)
1314                        die("internal error in blame::find_origin");
1315                switch (p->status) {
1316                default:
1317                        die("internal error in blame::find_origin (%c)",
1318                            p->status);
1319                case 'M':
1320                        porigin = get_origin(parent, origin->path);
1321                        oidcpy(&porigin->blob_oid, &p->one->oid);
1322                        porigin->mode = p->one->mode;
1323                        break;
1324                case 'A':
1325                case 'T':
1326                        /* Did not exist in parent, or type changed */
1327                        break;
1328                }
1329        }
1330        diff_flush(&diff_opts);
1331        clear_pathspec(&diff_opts.pathspec);
1332        return porigin;
1333}
1334
1335/*
1336 * We have an origin -- find the path that corresponds to it in its
1337 * parent and return an origin structure to represent it.
1338 */
1339static struct blame_origin *find_rename(struct repository *r,
1340                                        struct commit *parent,
1341                                        struct blame_origin *origin)
1342{
1343        struct blame_origin *porigin = NULL;
1344        struct diff_options diff_opts;
1345        int i;
1346
1347        repo_diff_setup(r, &diff_opts);
1348        diff_opts.flags.recursive = 1;
1349        diff_opts.detect_rename = DIFF_DETECT_RENAME;
1350        diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1351        diff_opts.single_follow = origin->path;
1352        diff_setup_done(&diff_opts);
1353
1354        if (is_null_oid(&origin->commit->object.oid))
1355                do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
1356        else
1357                diff_tree_oid(get_commit_tree_oid(parent),
1358                              get_commit_tree_oid(origin->commit),
1359                              "", &diff_opts);
1360        diffcore_std(&diff_opts);
1361
1362        for (i = 0; i < diff_queued_diff.nr; i++) {
1363                struct diff_filepair *p = diff_queued_diff.queue[i];
1364                if ((p->status == 'R' || p->status == 'C') &&
1365                    !strcmp(p->two->path, origin->path)) {
1366                        porigin = get_origin(parent, p->one->path);
1367                        oidcpy(&porigin->blob_oid, &p->one->oid);
1368                        porigin->mode = p->one->mode;
1369                        break;
1370                }
1371        }
1372        diff_flush(&diff_opts);
1373        clear_pathspec(&diff_opts.pathspec);
1374        return porigin;
1375}
1376
1377/*
1378 * Append a new blame entry to a given output queue.
1379 */
1380static void add_blame_entry(struct blame_entry ***queue,
1381                            const struct blame_entry *src)
1382{
1383        struct blame_entry *e = xmalloc(sizeof(*e));
1384        memcpy(e, src, sizeof(*e));
1385        blame_origin_incref(e->suspect);
1386
1387        e->next = **queue;
1388        **queue = e;
1389        *queue = &e->next;
1390}
1391
1392/*
1393 * src typically is on-stack; we want to copy the information in it to
1394 * a malloced blame_entry that gets added to the given queue.  The
1395 * origin of dst loses a refcnt.
1396 */
1397static void dup_entry(struct blame_entry ***queue,
1398                      struct blame_entry *dst, struct blame_entry *src)
1399{
1400        blame_origin_incref(src->suspect);
1401        blame_origin_decref(dst->suspect);
1402        memcpy(dst, src, sizeof(*src));
1403        dst->next = **queue;
1404        **queue = dst;
1405        *queue = &dst->next;
1406}
1407
1408const char *blame_nth_line(struct blame_scoreboard *sb, long lno)
1409{
1410        return sb->final_buf + sb->lineno[lno];
1411}
1412
1413/*
1414 * It is known that lines between tlno to same came from parent, and e
1415 * has an overlap with that range.  it also is known that parent's
1416 * line plno corresponds to e's line tlno.
1417 *
1418 *                <---- e ----->
1419 *                   <------>
1420 *                   <------------>
1421 *             <------------>
1422 *             <------------------>
1423 *
1424 * Split e into potentially three parts; before this chunk, the chunk
1425 * to be blamed for the parent, and after that portion.
1426 */
1427static void split_overlap(struct blame_entry *split,
1428                          struct blame_entry *e,
1429                          int tlno, int plno, int same,
1430                          struct blame_origin *parent)
1431{
1432        int chunk_end_lno;
1433        int i;
1434        memset(split, 0, sizeof(struct blame_entry [3]));
1435
1436        for (i = 0; i < 3; i++) {
1437                split[i].ignored = e->ignored;
1438                split[i].unblamable = e->unblamable;
1439        }
1440
1441        if (e->s_lno < tlno) {
1442                /* there is a pre-chunk part not blamed on parent */
1443                split[0].suspect = blame_origin_incref(e->suspect);
1444                split[0].lno = e->lno;
1445                split[0].s_lno = e->s_lno;
1446                split[0].num_lines = tlno - e->s_lno;
1447                split[1].lno = e->lno + tlno - e->s_lno;
1448                split[1].s_lno = plno;
1449        }
1450        else {
1451                split[1].lno = e->lno;
1452                split[1].s_lno = plno + (e->s_lno - tlno);
1453        }
1454
1455        if (same < e->s_lno + e->num_lines) {
1456                /* there is a post-chunk part not blamed on parent */
1457                split[2].suspect = blame_origin_incref(e->suspect);
1458                split[2].lno = e->lno + (same - e->s_lno);
1459                split[2].s_lno = e->s_lno + (same - e->s_lno);
1460                split[2].num_lines = e->s_lno + e->num_lines - same;
1461                chunk_end_lno = split[2].lno;
1462        }
1463        else
1464                chunk_end_lno = e->lno + e->num_lines;
1465        split[1].num_lines = chunk_end_lno - split[1].lno;
1466
1467        /*
1468         * if it turns out there is nothing to blame the parent for,
1469         * forget about the splitting.  !split[1].suspect signals this.
1470         */
1471        if (split[1].num_lines < 1)
1472                return;
1473        split[1].suspect = blame_origin_incref(parent);
1474}
1475
1476/*
1477 * split_overlap() divided an existing blame e into up to three parts
1478 * in split.  Any assigned blame is moved to queue to
1479 * reflect the split.
1480 */
1481static void split_blame(struct blame_entry ***blamed,
1482                        struct blame_entry ***unblamed,
1483                        struct blame_entry *split,
1484                        struct blame_entry *e)
1485{
1486        if (split[0].suspect && split[2].suspect) {
1487                /* The first part (reuse storage for the existing entry e) */
1488                dup_entry(unblamed, e, &split[0]);
1489
1490                /* The last part -- me */
1491                add_blame_entry(unblamed, &split[2]);
1492
1493                /* ... and the middle part -- parent */
1494                add_blame_entry(blamed, &split[1]);
1495        }
1496        else if (!split[0].suspect && !split[2].suspect)
1497                /*
1498                 * The parent covers the entire area; reuse storage for
1499                 * e and replace it with the parent.
1500                 */
1501                dup_entry(blamed, e, &split[1]);
1502        else if (split[0].suspect) {
1503                /* me and then parent */
1504                dup_entry(unblamed, e, &split[0]);
1505                add_blame_entry(blamed, &split[1]);
1506        }
1507        else {
1508                /* parent and then me */
1509                dup_entry(blamed, e, &split[1]);
1510                add_blame_entry(unblamed, &split[2]);
1511        }
1512}
1513
1514/*
1515 * After splitting the blame, the origins used by the
1516 * on-stack blame_entry should lose one refcnt each.
1517 */
1518static void decref_split(struct blame_entry *split)
1519{
1520        int i;
1521
1522        for (i = 0; i < 3; i++)
1523                blame_origin_decref(split[i].suspect);
1524}
1525
1526/*
1527 * reverse_blame reverses the list given in head, appending tail.
1528 * That allows us to build lists in reverse order, then reverse them
1529 * afterwards.  This can be faster than building the list in proper
1530 * order right away.  The reason is that building in proper order
1531 * requires writing a link in the _previous_ element, while building
1532 * in reverse order just requires placing the list head into the
1533 * _current_ element.
1534 */
1535
1536static struct blame_entry *reverse_blame(struct blame_entry *head,
1537                                         struct blame_entry *tail)
1538{
1539        while (head) {
1540                struct blame_entry *next = head->next;
1541                head->next = tail;
1542                tail = head;
1543                head = next;
1544        }
1545        return tail;
1546}
1547
1548/*
1549 * Splits a blame entry into two entries at 'len' lines.  The original 'e'
1550 * consists of len lines, i.e. [e->lno, e->lno + len), and the second part,
1551 * which is returned, consists of the remainder: [e->lno + len, e->lno +
1552 * e->num_lines).  The caller needs to sort out the reference counting for the
1553 * new entry's suspect.
1554 */
1555static struct blame_entry *split_blame_at(struct blame_entry *e, int len,
1556                                          struct blame_origin *new_suspect)
1557{
1558        struct blame_entry *n = xcalloc(1, sizeof(struct blame_entry));
1559
1560        n->suspect = new_suspect;
1561        n->ignored = e->ignored;
1562        n->unblamable = e->unblamable;
1563        n->lno = e->lno + len;
1564        n->s_lno = e->s_lno + len;
1565        n->num_lines = e->num_lines - len;
1566        e->num_lines = len;
1567        e->score = 0;
1568        return n;
1569}
1570
1571struct blame_line_tracker {
1572        int is_parent;
1573        int s_lno;
1574};
1575
1576static int are_lines_adjacent(struct blame_line_tracker *first,
1577                              struct blame_line_tracker *second)
1578{
1579        return first->is_parent == second->is_parent &&
1580               first->s_lno + 1 == second->s_lno;
1581}
1582
1583static int scan_parent_range(struct fingerprint *p_fps,
1584                             struct fingerprint *t_fps, int t_idx,
1585                             int from, int nr_lines)
1586{
1587        int sim, p_idx;
1588        #define FINGERPRINT_FILE_THRESHOLD      10
1589        int best_sim_val = FINGERPRINT_FILE_THRESHOLD;
1590        int best_sim_idx = -1;
1591
1592        for (p_idx = from; p_idx < from + nr_lines; p_idx++) {
1593                sim = fingerprint_similarity(&t_fps[t_idx], &p_fps[p_idx]);
1594                if (sim < best_sim_val)
1595                        continue;
1596                /* Break ties with the closest-to-target line number */
1597                if (sim == best_sim_val && best_sim_idx != -1 &&
1598                    abs(best_sim_idx - t_idx) < abs(p_idx - t_idx))
1599                        continue;
1600                best_sim_val = sim;
1601                best_sim_idx = p_idx;
1602        }
1603        return best_sim_idx;
1604}
1605
1606/*
1607 * The first pass checks the blame entry (from the target) against the parent's
1608 * diff chunk.  If that fails for a line, the second pass tries to match that
1609 * line to any part of parent file.  That catches cases where a change was
1610 * broken into two chunks by 'context.'
1611 */
1612static void guess_line_blames(struct blame_origin *parent,
1613                              struct blame_origin *target,
1614                              int tlno, int offset, int same, int parent_len,
1615                              struct blame_line_tracker *line_blames)
1616{
1617        int i, best_idx, target_idx;
1618        int parent_slno = tlno + offset;
1619        int *fuzzy_matches;
1620
1621        fuzzy_matches = fuzzy_find_matching_lines(parent, target,
1622                                                  tlno, parent_slno, same,
1623                                                  parent_len);
1624        for (i = 0; i < same - tlno; i++) {
1625                target_idx = tlno + i;
1626                if (fuzzy_matches && fuzzy_matches[i] >= 0) {
1627                        best_idx = fuzzy_matches[i];
1628                } else {
1629                        best_idx = scan_parent_range(parent->fingerprints,
1630                                                     target->fingerprints,
1631                                                     target_idx, 0,
1632                                                     parent->num_lines);
1633                }
1634                if (best_idx >= 0) {
1635                        line_blames[i].is_parent = 1;
1636                        line_blames[i].s_lno = best_idx;
1637                } else {
1638                        line_blames[i].is_parent = 0;
1639                        line_blames[i].s_lno = target_idx;
1640                }
1641        }
1642        free(fuzzy_matches);
1643}
1644
1645/*
1646 * This decides which parts of a blame entry go to the parent (added to the
1647 * ignoredp list) and which stay with the target (added to the diffp list).  The
1648 * actual decision was made in a separate heuristic function, and those answers
1649 * for the lines in 'e' are in line_blames.  This consumes e, essentially
1650 * putting it on a list.
1651 *
1652 * Note that the blame entries on the ignoredp list are not necessarily sorted
1653 * with respect to the parent's line numbers yet.
1654 */
1655static void ignore_blame_entry(struct blame_entry *e,
1656                               struct blame_origin *parent,
1657                               struct blame_entry **diffp,
1658                               struct blame_entry **ignoredp,
1659                               struct blame_line_tracker *line_blames)
1660{
1661        int entry_len, nr_lines, i;
1662
1663        /*
1664         * We carve new entries off the front of e.  Each entry comes from a
1665         * contiguous chunk of lines: adjacent lines from the same origin
1666         * (either the parent or the target).
1667         */
1668        entry_len = 1;
1669        nr_lines = e->num_lines;        /* e changes in the loop */
1670        for (i = 0; i < nr_lines; i++) {
1671                struct blame_entry *next = NULL;
1672
1673                /*
1674                 * We are often adjacent to the next line - only split the blame
1675                 * entry when we have to.
1676                 */
1677                if (i + 1 < nr_lines) {
1678                        if (are_lines_adjacent(&line_blames[i],
1679                                               &line_blames[i + 1])) {
1680                                entry_len++;
1681                                continue;
1682                        }
1683                        next = split_blame_at(e, entry_len,
1684                                              blame_origin_incref(e->suspect));
1685                }
1686                if (line_blames[i].is_parent) {
1687                        e->ignored = 1;
1688                        blame_origin_decref(e->suspect);
1689                        e->suspect = blame_origin_incref(parent);
1690                        e->s_lno = line_blames[i - entry_len + 1].s_lno;
1691                        e->next = *ignoredp;
1692                        *ignoredp = e;
1693                } else {
1694                        e->unblamable = 1;
1695                        /* e->s_lno is already in the target's address space. */
1696                        e->next = *diffp;
1697                        *diffp = e;
1698                }
1699                assert(e->num_lines == entry_len);
1700                e = next;
1701                entry_len = 1;
1702        }
1703        assert(!e);
1704}
1705
1706/*
1707 * Process one hunk from the patch between the current suspect for
1708 * blame_entry e and its parent.  This first blames any unfinished
1709 * entries before the chunk (which is where target and parent start
1710 * differing) on the parent, and then splits blame entries at the
1711 * start and at the end of the difference region.  Since use of -M and
1712 * -C options may lead to overlapping/duplicate source line number
1713 * ranges, all we can rely on from sorting/merging is the order of the
1714 * first suspect line number.
1715 *
1716 * tlno: line number in the target where this chunk begins
1717 * same: line number in the target where this chunk ends
1718 * offset: add to tlno to get the chunk starting point in the parent
1719 * parent_len: number of lines in the parent chunk
1720 */
1721static void blame_chunk(struct blame_entry ***dstq, struct blame_entry ***srcq,
1722                        int tlno, int offset, int same, int parent_len,
1723                        struct blame_origin *parent,
1724                        struct blame_origin *target, int ignore_diffs)
1725{
1726        struct blame_entry *e = **srcq;
1727        struct blame_entry *samep = NULL, *diffp = NULL, *ignoredp = NULL;
1728        struct blame_line_tracker *line_blames = NULL;
1729
1730        while (e && e->s_lno < tlno) {
1731                struct blame_entry *next = e->next;
1732                /*
1733                 * current record starts before differing portion.  If
1734                 * it reaches into it, we need to split it up and
1735                 * examine the second part separately.
1736                 */
1737                if (e->s_lno + e->num_lines > tlno) {
1738                        /* Move second half to a new record */
1739                        struct blame_entry *n;
1740
1741                        n = split_blame_at(e, tlno - e->s_lno, e->suspect);
1742                        /* Push new record to diffp */
1743                        n->next = diffp;
1744                        diffp = n;
1745                } else
1746                        blame_origin_decref(e->suspect);
1747                /* Pass blame for everything before the differing
1748                 * chunk to the parent */
1749                e->suspect = blame_origin_incref(parent);
1750                e->s_lno += offset;
1751                e->next = samep;
1752                samep = e;
1753                e = next;
1754        }
1755        /*
1756         * As we don't know how much of a common stretch after this
1757         * diff will occur, the currently blamed parts are all that we
1758         * can assign to the parent for now.
1759         */
1760
1761        if (samep) {
1762                **dstq = reverse_blame(samep, **dstq);
1763                *dstq = &samep->next;
1764        }
1765        /*
1766         * Prepend the split off portions: everything after e starts
1767         * after the blameable portion.
1768         */
1769        e = reverse_blame(diffp, e);
1770
1771        /*
1772         * Now retain records on the target while parts are different
1773         * from the parent.
1774         */
1775        samep = NULL;
1776        diffp = NULL;
1777
1778        if (ignore_diffs && same - tlno > 0) {
1779                line_blames = xcalloc(sizeof(struct blame_line_tracker),
1780                                      same - tlno);
1781                guess_line_blames(parent, target, tlno, offset, same,
1782                                  parent_len, line_blames);
1783        }
1784
1785        while (e && e->s_lno < same) {
1786                struct blame_entry *next = e->next;
1787
1788                /*
1789                 * If current record extends into sameness, need to split.
1790                 */
1791                if (e->s_lno + e->num_lines > same) {
1792                        /*
1793                         * Move second half to a new record to be
1794                         * processed by later chunks
1795                         */
1796                        struct blame_entry *n;
1797
1798                        n = split_blame_at(e, same - e->s_lno,
1799                                           blame_origin_incref(e->suspect));
1800                        /* Push new record to samep */
1801                        n->next = samep;
1802                        samep = n;
1803                }
1804                if (ignore_diffs) {
1805                        ignore_blame_entry(e, parent, &diffp, &ignoredp,
1806                                           line_blames + e->s_lno - tlno);
1807                } else {
1808                        e->next = diffp;
1809                        diffp = e;
1810                }
1811                e = next;
1812        }
1813        free(line_blames);
1814        if (ignoredp) {
1815                /*
1816                 * Note ignoredp is not sorted yet, and thus neither is dstq.
1817                 * That list must be sorted before we queue_blames().  We defer
1818                 * sorting until after all diff hunks are processed, so that
1819                 * guess_line_blames() can pick *any* line in the parent.  The
1820                 * slight drawback is that we end up sorting all blame entries
1821                 * passed to the parent, including those that are unrelated to
1822                 * changes made by the ignored commit.
1823                 */
1824                **dstq = reverse_blame(ignoredp, **dstq);
1825                *dstq = &ignoredp->next;
1826        }
1827        **srcq = reverse_blame(diffp, reverse_blame(samep, e));
1828        /* Move across elements that are in the unblamable portion */
1829        if (diffp)
1830                *srcq = &diffp->next;
1831}
1832
1833struct blame_chunk_cb_data {
1834        struct blame_origin *parent;
1835        struct blame_origin *target;
1836        long offset;
1837        int ignore_diffs;
1838        struct blame_entry **dstq;
1839        struct blame_entry **srcq;
1840};
1841
1842/* diff chunks are from parent to target */
1843static int blame_chunk_cb(long start_a, long count_a,
1844                          long start_b, long count_b, void *data)
1845{
1846        struct blame_chunk_cb_data *d = data;
1847        if (start_a - start_b != d->offset)
1848                die("internal error in blame::blame_chunk_cb");
1849        blame_chunk(&d->dstq, &d->srcq, start_b, start_a - start_b,
1850                    start_b + count_b, count_a, d->parent, d->target,
1851                    d->ignore_diffs);
1852        d->offset = start_a + count_a - (start_b + count_b);
1853        return 0;
1854}
1855
1856/*
1857 * We are looking at the origin 'target' and aiming to pass blame
1858 * for the lines it is suspected to its parent.  Run diff to find
1859 * which lines came from parent and pass blame for them.
1860 */
1861static void pass_blame_to_parent(struct blame_scoreboard *sb,
1862                                 struct blame_origin *target,
1863                                 struct blame_origin *parent, int ignore_diffs)
1864{
1865        mmfile_t file_p, file_o;
1866        struct blame_chunk_cb_data d;
1867        struct blame_entry *newdest = NULL;
1868
1869        if (!target->suspects)
1870                return; /* nothing remains for this target */
1871
1872        d.parent = parent;
1873        d.target = target;
1874        d.offset = 0;
1875        d.ignore_diffs = ignore_diffs;
1876        d.dstq = &newdest; d.srcq = &target->suspects;
1877
1878        fill_origin_blob(&sb->revs->diffopt, parent, &file_p,
1879                         &sb->num_read_blob, ignore_diffs);
1880        fill_origin_blob(&sb->revs->diffopt, target, &file_o,
1881                         &sb->num_read_blob, ignore_diffs);
1882        sb->num_get_patch++;
1883
1884        if (diff_hunks(&file_p, &file_o, blame_chunk_cb, &d, sb->xdl_opts))
1885                die("unable to generate diff (%s -> %s)",
1886                    oid_to_hex(&parent->commit->object.oid),
1887                    oid_to_hex(&target->commit->object.oid));
1888        /* The rest are the same as the parent */
1889        blame_chunk(&d.dstq, &d.srcq, INT_MAX, d.offset, INT_MAX, 0,
1890                    parent, target, 0);
1891        *d.dstq = NULL;
1892        if (ignore_diffs)
1893                newdest = llist_mergesort(newdest, get_next_blame,
1894                                          set_next_blame,
1895                                          compare_blame_suspect);
1896        queue_blames(sb, parent, newdest);
1897
1898        return;
1899}
1900
1901/*
1902 * The lines in blame_entry after splitting blames many times can become
1903 * very small and trivial, and at some point it becomes pointless to
1904 * blame the parents.  E.g. "\t\t}\n\t}\n\n" appears everywhere in any
1905 * ordinary C program, and it is not worth to say it was copied from
1906 * totally unrelated file in the parent.
1907 *
1908 * Compute how trivial the lines in the blame_entry are.
1909 */
1910unsigned blame_entry_score(struct blame_scoreboard *sb, struct blame_entry *e)
1911{
1912        unsigned score;
1913        const char *cp, *ep;
1914
1915        if (e->score)
1916                return e->score;
1917
1918        score = 1;
1919        cp = blame_nth_line(sb, e->lno);
1920        ep = blame_nth_line(sb, e->lno + e->num_lines);
1921        while (cp < ep) {
1922                unsigned ch = *((unsigned char *)cp);
1923                if (isalnum(ch))
1924                        score++;
1925                cp++;
1926        }
1927        e->score = score;
1928        return score;
1929}
1930
1931/*
1932 * best_so_far[] and potential[] are both a split of an existing blame_entry
1933 * that passes blame to the parent.  Maintain best_so_far the best split so
1934 * far, by comparing potential and best_so_far and copying potential into
1935 * bst_so_far as needed.
1936 */
1937static void copy_split_if_better(struct blame_scoreboard *sb,
1938                                 struct blame_entry *best_so_far,
1939                                 struct blame_entry *potential)
1940{
1941        int i;
1942
1943        if (!potential[1].suspect)
1944                return;
1945        if (best_so_far[1].suspect) {
1946                if (blame_entry_score(sb, &potential[1]) <
1947                    blame_entry_score(sb, &best_so_far[1]))
1948                        return;
1949        }
1950
1951        for (i = 0; i < 3; i++)
1952                blame_origin_incref(potential[i].suspect);
1953        decref_split(best_so_far);
1954        memcpy(best_so_far, potential, sizeof(struct blame_entry[3]));
1955}
1956
1957/*
1958 * We are looking at a part of the final image represented by
1959 * ent (tlno and same are offset by ent->s_lno).
1960 * tlno is where we are looking at in the final image.
1961 * up to (but not including) same match preimage.
1962 * plno is where we are looking at in the preimage.
1963 *
1964 * <-------------- final image ---------------------->
1965 *       <------ent------>
1966 *         ^tlno ^same
1967 *    <---------preimage----->
1968 *         ^plno
1969 *
1970 * All line numbers are 0-based.
1971 */
1972static void handle_split(struct blame_scoreboard *sb,
1973                         struct blame_entry *ent,
1974                         int tlno, int plno, int same,
1975                         struct blame_origin *parent,
1976                         struct blame_entry *split)
1977{
1978        if (ent->num_lines <= tlno)
1979                return;
1980        if (tlno < same) {
1981                struct blame_entry potential[3];
1982                tlno += ent->s_lno;
1983                same += ent->s_lno;
1984                split_overlap(potential, ent, tlno, plno, same, parent);
1985                copy_split_if_better(sb, split, potential);
1986                decref_split(potential);
1987        }
1988}
1989
1990struct handle_split_cb_data {
1991        struct blame_scoreboard *sb;
1992        struct blame_entry *ent;
1993        struct blame_origin *parent;
1994        struct blame_entry *split;
1995        long plno;
1996        long tlno;
1997};
1998
1999static int handle_split_cb(long start_a, long count_a,
2000                           long start_b, long count_b, void *data)
2001{
2002        struct handle_split_cb_data *d = data;
2003        handle_split(d->sb, d->ent, d->tlno, d->plno, start_b, d->parent,
2004                     d->split);
2005        d->plno = start_a + count_a;
2006        d->tlno = start_b + count_b;
2007        return 0;
2008}
2009
2010/*
2011 * Find the lines from parent that are the same as ent so that
2012 * we can pass blames to it.  file_p has the blob contents for
2013 * the parent.
2014 */
2015static void find_copy_in_blob(struct blame_scoreboard *sb,
2016                              struct blame_entry *ent,
2017                              struct blame_origin *parent,
2018                              struct blame_entry *split,
2019                              mmfile_t *file_p)
2020{
2021        const char *cp;
2022        mmfile_t file_o;
2023        struct handle_split_cb_data d;
2024
2025        memset(&d, 0, sizeof(d));
2026        d.sb = sb; d.ent = ent; d.parent = parent; d.split = split;
2027        /*
2028         * Prepare mmfile that contains only the lines in ent.
2029         */
2030        cp = blame_nth_line(sb, ent->lno);
2031        file_o.ptr = (char *) cp;
2032        file_o.size = blame_nth_line(sb, ent->lno + ent->num_lines) - cp;
2033
2034        /*
2035         * file_o is a part of final image we are annotating.
2036         * file_p partially may match that image.
2037         */
2038        memset(split, 0, sizeof(struct blame_entry [3]));
2039        if (diff_hunks(file_p, &file_o, handle_split_cb, &d, sb->xdl_opts))
2040                die("unable to generate diff (%s)",
2041                    oid_to_hex(&parent->commit->object.oid));
2042        /* remainder, if any, all match the preimage */
2043        handle_split(sb, ent, d.tlno, d.plno, ent->num_lines, parent, split);
2044}
2045
2046/* Move all blame entries from list *source that have a score smaller
2047 * than score_min to the front of list *small.
2048 * Returns a pointer to the link pointing to the old head of the small list.
2049 */
2050
2051static struct blame_entry **filter_small(struct blame_scoreboard *sb,
2052                                         struct blame_entry **small,
2053                                         struct blame_entry **source,
2054                                         unsigned score_min)
2055{
2056        struct blame_entry *p = *source;
2057        struct blame_entry *oldsmall = *small;
2058        while (p) {
2059                if (blame_entry_score(sb, p) <= score_min) {
2060                        *small = p;
2061                        small = &p->next;
2062                        p = *small;
2063                } else {
2064                        *source = p;
2065                        source = &p->next;
2066                        p = *source;
2067                }
2068        }
2069        *small = oldsmall;
2070        *source = NULL;
2071        return small;
2072}
2073
2074/*
2075 * See if lines currently target is suspected for can be attributed to
2076 * parent.
2077 */
2078static void find_move_in_parent(struct blame_scoreboard *sb,
2079                                struct blame_entry ***blamed,
2080                                struct blame_entry **toosmall,
2081                                struct blame_origin *target,
2082                                struct blame_origin *parent)
2083{
2084        struct blame_entry *e, split[3];
2085        struct blame_entry *unblamed = target->suspects;
2086        struct blame_entry *leftover = NULL;
2087        mmfile_t file_p;
2088
2089        if (!unblamed)
2090                return; /* nothing remains for this target */
2091
2092        fill_origin_blob(&sb->revs->diffopt, parent, &file_p,
2093                         &sb->num_read_blob, 0);
2094        if (!file_p.ptr)
2095                return;
2096
2097        /* At each iteration, unblamed has a NULL-terminated list of
2098         * entries that have not yet been tested for blame.  leftover
2099         * contains the reversed list of entries that have been tested
2100         * without being assignable to the parent.
2101         */
2102        do {
2103                struct blame_entry **unblamedtail = &unblamed;
2104                struct blame_entry *next;
2105                for (e = unblamed; e; e = next) {
2106                        next = e->next;
2107                        find_copy_in_blob(sb, e, parent, split, &file_p);
2108                        if (split[1].suspect &&
2109                            sb->move_score < blame_entry_score(sb, &split[1])) {
2110                                split_blame(blamed, &unblamedtail, split, e);
2111                        } else {
2112                                e->next = leftover;
2113                                leftover = e;
2114                        }
2115                        decref_split(split);
2116                }
2117                *unblamedtail = NULL;
2118                toosmall = filter_small(sb, toosmall, &unblamed, sb->move_score);
2119        } while (unblamed);
2120        target->suspects = reverse_blame(leftover, NULL);
2121}
2122
2123struct blame_list {
2124        struct blame_entry *ent;
2125        struct blame_entry split[3];
2126};
2127
2128/*
2129 * Count the number of entries the target is suspected for,
2130 * and prepare a list of entry and the best split.
2131 */
2132static struct blame_list *setup_blame_list(struct blame_entry *unblamed,
2133                                           int *num_ents_p)
2134{
2135        struct blame_entry *e;
2136        int num_ents, i;
2137        struct blame_list *blame_list = NULL;
2138
2139        for (e = unblamed, num_ents = 0; e; e = e->next)
2140                num_ents++;
2141        if (num_ents) {
2142                blame_list = xcalloc(num_ents, sizeof(struct blame_list));
2143                for (e = unblamed, i = 0; e; e = e->next)
2144                        blame_list[i++].ent = e;
2145        }
2146        *num_ents_p = num_ents;
2147        return blame_list;
2148}
2149
2150/*
2151 * For lines target is suspected for, see if we can find code movement
2152 * across file boundary from the parent commit.  porigin is the path
2153 * in the parent we already tried.
2154 */
2155static void find_copy_in_parent(struct blame_scoreboard *sb,
2156                                struct blame_entry ***blamed,
2157                                struct blame_entry **toosmall,
2158                                struct blame_origin *target,
2159                                struct commit *parent,
2160                                struct blame_origin *porigin,
2161                                int opt)
2162{
2163        struct diff_options diff_opts;
2164        int i, j;
2165        struct blame_list *blame_list;
2166        int num_ents;
2167        struct blame_entry *unblamed = target->suspects;
2168        struct blame_entry *leftover = NULL;
2169
2170        if (!unblamed)
2171                return; /* nothing remains for this target */
2172
2173        repo_diff_setup(sb->repo, &diff_opts);
2174        diff_opts.flags.recursive = 1;
2175        diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
2176
2177        diff_setup_done(&diff_opts);
2178
2179        /* Try "find copies harder" on new path if requested;
2180         * we do not want to use diffcore_rename() actually to
2181         * match things up; find_copies_harder is set only to
2182         * force diff_tree_oid() to feed all filepairs to diff_queue,
2183         * and this code needs to be after diff_setup_done(), which
2184         * usually makes find-copies-harder imply copy detection.
2185         */
2186        if ((opt & PICKAXE_BLAME_COPY_HARDEST)
2187            || ((opt & PICKAXE_BLAME_COPY_HARDER)
2188                && (!porigin || strcmp(target->path, porigin->path))))
2189                diff_opts.flags.find_copies_harder = 1;
2190
2191        if (is_null_oid(&target->commit->object.oid))
2192                do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
2193        else
2194                diff_tree_oid(get_commit_tree_oid(parent),
2195                              get_commit_tree_oid(target->commit),
2196                              "", &diff_opts);
2197
2198        if (!diff_opts.flags.find_copies_harder)
2199                diffcore_std(&diff_opts);
2200
2201        do {
2202                struct blame_entry **unblamedtail = &unblamed;
2203                blame_list = setup_blame_list(unblamed, &num_ents);
2204
2205                for (i = 0; i < diff_queued_diff.nr; i++) {
2206                        struct diff_filepair *p = diff_queued_diff.queue[i];
2207                        struct blame_origin *norigin;
2208                        mmfile_t file_p;
2209                        struct blame_entry potential[3];
2210
2211                        if (!DIFF_FILE_VALID(p->one))
2212                                continue; /* does not exist in parent */
2213                        if (S_ISGITLINK(p->one->mode))
2214                                continue; /* ignore git links */
2215                        if (porigin && !strcmp(p->one->path, porigin->path))
2216                                /* find_move already dealt with this path */
2217                                continue;
2218
2219                        norigin = get_origin(parent, p->one->path);
2220                        oidcpy(&norigin->blob_oid, &p->one->oid);
2221                        norigin->mode = p->one->mode;
2222                        fill_origin_blob(&sb->revs->diffopt, norigin, &file_p,
2223                                         &sb->num_read_blob, 0);
2224                        if (!file_p.ptr)
2225                                continue;
2226
2227                        for (j = 0; j < num_ents; j++) {
2228                                find_copy_in_blob(sb, blame_list[j].ent,
2229                                                  norigin, potential, &file_p);
2230                                copy_split_if_better(sb, blame_list[j].split,
2231                                                     potential);
2232                                decref_split(potential);
2233                        }
2234                        blame_origin_decref(norigin);
2235                }
2236
2237                for (j = 0; j < num_ents; j++) {
2238                        struct blame_entry *split = blame_list[j].split;
2239                        if (split[1].suspect &&
2240                            sb->copy_score < blame_entry_score(sb, &split[1])) {
2241                                split_blame(blamed, &unblamedtail, split,
2242                                            blame_list[j].ent);
2243                        } else {
2244                                blame_list[j].ent->next = leftover;
2245                                leftover = blame_list[j].ent;
2246                        }
2247                        decref_split(split);
2248                }
2249                free(blame_list);
2250                *unblamedtail = NULL;
2251                toosmall = filter_small(sb, toosmall, &unblamed, sb->copy_score);
2252        } while (unblamed);
2253        target->suspects = reverse_blame(leftover, NULL);
2254        diff_flush(&diff_opts);
2255        clear_pathspec(&diff_opts.pathspec);
2256}
2257
2258/*
2259 * The blobs of origin and porigin exactly match, so everything
2260 * origin is suspected for can be blamed on the parent.
2261 */
2262static void pass_whole_blame(struct blame_scoreboard *sb,
2263                             struct blame_origin *origin, struct blame_origin *porigin)
2264{
2265        struct blame_entry *e, *suspects;
2266
2267        if (!porigin->file.ptr && origin->file.ptr) {
2268                /* Steal its file */
2269                porigin->file = origin->file;
2270                origin->file.ptr = NULL;
2271        }
2272        suspects = origin->suspects;
2273        origin->suspects = NULL;
2274        for (e = suspects; e; e = e->next) {
2275                blame_origin_incref(porigin);
2276                blame_origin_decref(e->suspect);
2277                e->suspect = porigin;
2278        }
2279        queue_blames(sb, porigin, suspects);
2280}
2281
2282/*
2283 * We pass blame from the current commit to its parents.  We keep saying
2284 * "parent" (and "porigin"), but what we mean is to find scapegoat to
2285 * exonerate ourselves.
2286 */
2287static struct commit_list *first_scapegoat(struct rev_info *revs, struct commit *commit,
2288                                        int reverse)
2289{
2290        if (!reverse) {
2291                if (revs->first_parent_only &&
2292                    commit->parents &&
2293                    commit->parents->next) {
2294                        free_commit_list(commit->parents->next);
2295                        commit->parents->next = NULL;
2296                }
2297                return commit->parents;
2298        }
2299        return lookup_decoration(&revs->children, &commit->object);
2300}
2301
2302static int num_scapegoats(struct rev_info *revs, struct commit *commit, int reverse)
2303{
2304        struct commit_list *l = first_scapegoat(revs, commit, reverse);
2305        return commit_list_count(l);
2306}
2307
2308/* Distribute collected unsorted blames to the respected sorted lists
2309 * in the various origins.
2310 */
2311static void distribute_blame(struct blame_scoreboard *sb, struct blame_entry *blamed)
2312{
2313        blamed = llist_mergesort(blamed, get_next_blame, set_next_blame,
2314                                 compare_blame_suspect);
2315        while (blamed)
2316        {
2317                struct blame_origin *porigin = blamed->suspect;
2318                struct blame_entry *suspects = NULL;
2319                do {
2320                        struct blame_entry *next = blamed->next;
2321                        blamed->next = suspects;
2322                        suspects = blamed;
2323                        blamed = next;
2324                } while (blamed && blamed->suspect == porigin);
2325                suspects = reverse_blame(suspects, NULL);
2326                queue_blames(sb, porigin, suspects);
2327        }
2328}
2329
2330#define MAXSG 16
2331
2332static void pass_blame(struct blame_scoreboard *sb, struct blame_origin *origin, int opt)
2333{
2334        struct rev_info *revs = sb->revs;
2335        int i, pass, num_sg;
2336        struct commit *commit = origin->commit;
2337        struct commit_list *sg;
2338        struct blame_origin *sg_buf[MAXSG];
2339        struct blame_origin *porigin, **sg_origin = sg_buf;
2340        struct blame_entry *toosmall = NULL;
2341        struct blame_entry *blames, **blametail = &blames;
2342
2343        num_sg = num_scapegoats(revs, commit, sb->reverse);
2344        if (!num_sg)
2345                goto finish;
2346        else if (num_sg < ARRAY_SIZE(sg_buf))
2347                memset(sg_buf, 0, sizeof(sg_buf));
2348        else
2349                sg_origin = xcalloc(num_sg, sizeof(*sg_origin));
2350
2351        /*
2352         * The first pass looks for unrenamed path to optimize for
2353         * common cases, then we look for renames in the second pass.
2354         */
2355        for (pass = 0; pass < 2 - sb->no_whole_file_rename; pass++) {
2356                struct blame_origin *(*find)(struct repository *, struct commit *, struct blame_origin *);
2357                find = pass ? find_rename : find_origin;
2358
2359                for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2360                     i < num_sg && sg;
2361                     sg = sg->next, i++) {
2362                        struct commit *p = sg->item;
2363                        int j, same;
2364
2365                        if (sg_origin[i])
2366                                continue;
2367                        if (parse_commit(p))
2368                                continue;
2369                        porigin = find(sb->repo, p, origin);
2370                        if (!porigin)
2371                                continue;
2372                        if (oideq(&porigin->blob_oid, &origin->blob_oid)) {
2373                                pass_whole_blame(sb, origin, porigin);
2374                                blame_origin_decref(porigin);
2375                                goto finish;
2376                        }
2377                        for (j = same = 0; j < i; j++)
2378                                if (sg_origin[j] &&
2379                                    oideq(&sg_origin[j]->blob_oid, &porigin->blob_oid)) {
2380                                        same = 1;
2381                                        break;
2382                                }
2383                        if (!same)
2384                                sg_origin[i] = porigin;
2385                        else
2386                                blame_origin_decref(porigin);
2387                }
2388        }
2389
2390        sb->num_commits++;
2391        for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2392             i < num_sg && sg;
2393             sg = sg->next, i++) {
2394                struct blame_origin *porigin = sg_origin[i];
2395                if (!porigin)
2396                        continue;
2397                if (!origin->previous) {
2398                        blame_origin_incref(porigin);
2399                        origin->previous = porigin;
2400                }
2401                pass_blame_to_parent(sb, origin, porigin, 0);
2402                if (!origin->suspects)
2403                        goto finish;
2404        }
2405
2406        /*
2407         * Pass remaining suspects for ignored commits to their parents.
2408         */
2409        if (oidset_contains(&sb->ignore_list, &commit->object.oid)) {
2410                for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2411                     i < num_sg && sg;
2412                     sg = sg->next, i++) {
2413                        struct blame_origin *porigin = sg_origin[i];
2414
2415                        if (!porigin)
2416                                continue;
2417                        pass_blame_to_parent(sb, origin, porigin, 1);
2418                        /*
2419                         * Preemptively drop porigin so we can refresh the
2420                         * fingerprints if we use the parent again, which can
2421                         * occur if you ignore back-to-back commits.
2422                         */
2423                        drop_origin_blob(porigin);
2424                        if (!origin->suspects)
2425                                goto finish;
2426                }
2427        }
2428
2429        /*
2430         * Optionally find moves in parents' files.
2431         */
2432        if (opt & PICKAXE_BLAME_MOVE) {
2433                filter_small(sb, &toosmall, &origin->suspects, sb->move_score);
2434                if (origin->suspects) {
2435                        for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2436                             i < num_sg && sg;
2437                             sg = sg->next, i++) {
2438                                struct blame_origin *porigin = sg_origin[i];
2439                                if (!porigin)
2440                                        continue;
2441                                find_move_in_parent(sb, &blametail, &toosmall, origin, porigin);
2442                                if (!origin->suspects)
2443                                        break;
2444                        }
2445                }
2446        }
2447
2448        /*
2449         * Optionally find copies from parents' files.
2450         */
2451        if (opt & PICKAXE_BLAME_COPY) {
2452                if (sb->copy_score > sb->move_score)
2453                        filter_small(sb, &toosmall, &origin->suspects, sb->copy_score);
2454                else if (sb->copy_score < sb->move_score) {
2455                        origin->suspects = blame_merge(origin->suspects, toosmall);
2456                        toosmall = NULL;
2457                        filter_small(sb, &toosmall, &origin->suspects, sb->copy_score);
2458                }
2459                if (!origin->suspects)
2460                        goto finish;
2461
2462                for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2463                     i < num_sg && sg;
2464                     sg = sg->next, i++) {
2465                        struct blame_origin *porigin = sg_origin[i];
2466                        find_copy_in_parent(sb, &blametail, &toosmall,
2467                                            origin, sg->item, porigin, opt);
2468                        if (!origin->suspects)
2469                                goto finish;
2470                }
2471        }
2472
2473finish:
2474        *blametail = NULL;
2475        distribute_blame(sb, blames);
2476        /*
2477         * prepend toosmall to origin->suspects
2478         *
2479         * There is no point in sorting: this ends up on a big
2480         * unsorted list in the caller anyway.
2481         */
2482        if (toosmall) {
2483                struct blame_entry **tail = &toosmall;
2484                while (*tail)
2485                        tail = &(*tail)->next;
2486                *tail = origin->suspects;
2487                origin->suspects = toosmall;
2488        }
2489        for (i = 0; i < num_sg; i++) {
2490                if (sg_origin[i]) {
2491                        if (!sg_origin[i]->suspects)
2492                                drop_origin_blob(sg_origin[i]);
2493                        blame_origin_decref(sg_origin[i]);
2494                }
2495        }
2496        drop_origin_blob(origin);
2497        if (sg_buf != sg_origin)
2498                free(sg_origin);
2499}
2500
2501/*
2502 * The main loop -- while we have blobs with lines whose true origin
2503 * is still unknown, pick one blob, and allow its lines to pass blames
2504 * to its parents. */
2505void assign_blame(struct blame_scoreboard *sb, int opt)
2506{
2507        struct rev_info *revs = sb->revs;
2508        struct commit *commit = prio_queue_get(&sb->commits);
2509
2510        while (commit) {
2511                struct blame_entry *ent;
2512                struct blame_origin *suspect = get_blame_suspects(commit);
2513
2514                /* find one suspect to break down */
2515                while (suspect && !suspect->suspects)
2516                        suspect = suspect->next;
2517
2518                if (!suspect) {
2519                        commit = prio_queue_get(&sb->commits);
2520                        continue;
2521                }
2522
2523                assert(commit == suspect->commit);
2524
2525                /*
2526                 * We will use this suspect later in the loop,
2527                 * so hold onto it in the meantime.
2528                 */
2529                blame_origin_incref(suspect);
2530                parse_commit(commit);
2531                if (sb->reverse ||
2532                    (!(commit->object.flags & UNINTERESTING) &&
2533                     !(revs->max_age != -1 && commit->date < revs->max_age)))
2534                        pass_blame(sb, suspect, opt);
2535                else {
2536                        commit->object.flags |= UNINTERESTING;
2537                        if (commit->object.parsed)
2538                                mark_parents_uninteresting(commit);
2539                }
2540                /* treat root commit as boundary */
2541                if (!commit->parents && !sb->show_root)
2542                        commit->object.flags |= UNINTERESTING;
2543
2544                /* Take responsibility for the remaining entries */
2545                ent = suspect->suspects;
2546                if (ent) {
2547                        suspect->guilty = 1;
2548                        for (;;) {
2549                                struct blame_entry *next = ent->next;
2550                                if (sb->found_guilty_entry)
2551                                        sb->found_guilty_entry(ent, sb->found_guilty_entry_data);
2552                                if (next) {
2553                                        ent = next;
2554                                        continue;
2555                                }
2556                                ent->next = sb->ent;
2557                                sb->ent = suspect->suspects;
2558                                suspect->suspects = NULL;
2559                                break;
2560                        }
2561                }
2562                blame_origin_decref(suspect);
2563
2564                if (sb->debug) /* sanity */
2565                        sanity_check_refcnt(sb);
2566        }
2567}
2568
2569/*
2570 * To allow quick access to the contents of nth line in the
2571 * final image, prepare an index in the scoreboard.
2572 */
2573static int prepare_lines(struct blame_scoreboard *sb)
2574{
2575        sb->num_lines = find_line_starts(&sb->lineno, sb->final_buf,
2576                                         sb->final_buf_size);
2577        return sb->num_lines;
2578}
2579
2580static struct commit *find_single_final(struct rev_info *revs,
2581                                        const char **name_p)
2582{
2583        int i;
2584        struct commit *found = NULL;
2585        const char *name = NULL;
2586
2587        for (i = 0; i < revs->pending.nr; i++) {
2588                struct object *obj = revs->pending.objects[i].item;
2589                if (obj->flags & UNINTERESTING)
2590                        continue;
2591                obj = deref_tag(revs->repo, obj, NULL, 0);
2592                if (obj->type != OBJ_COMMIT)
2593                        die("Non commit %s?", revs->pending.objects[i].name);
2594                if (found)
2595                        die("More than one commit to dig from %s and %s?",
2596                            revs->pending.objects[i].name, name);
2597                found = (struct commit *)obj;
2598                name = revs->pending.objects[i].name;
2599        }
2600        if (name_p)
2601                *name_p = xstrdup_or_null(name);
2602        return found;
2603}
2604
2605static struct commit *dwim_reverse_initial(struct rev_info *revs,
2606                                           const char **name_p)
2607{
2608        /*
2609         * DWIM "git blame --reverse ONE -- PATH" as
2610         * "git blame --reverse ONE..HEAD -- PATH" but only do so
2611         * when it makes sense.
2612         */
2613        struct object *obj;
2614        struct commit *head_commit;
2615        struct object_id head_oid;
2616
2617        if (revs->pending.nr != 1)
2618                return NULL;
2619
2620        /* Is that sole rev a committish? */
2621        obj = revs->pending.objects[0].item;
2622        obj = deref_tag(revs->repo, obj, NULL, 0);
2623        if (obj->type != OBJ_COMMIT)
2624                return NULL;
2625
2626        /* Do we have HEAD? */
2627        if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL))
2628                return NULL;
2629        head_commit = lookup_commit_reference_gently(revs->repo,
2630                                                     &head_oid, 1);
2631        if (!head_commit)
2632                return NULL;
2633
2634        /* Turn "ONE" into "ONE..HEAD" then */
2635        obj->flags |= UNINTERESTING;
2636        add_pending_object(revs, &head_commit->object, "HEAD");
2637
2638        if (name_p)
2639                *name_p = revs->pending.objects[0].name;
2640        return (struct commit *)obj;
2641}
2642
2643static struct commit *find_single_initial(struct rev_info *revs,
2644                                          const char **name_p)
2645{
2646        int i;
2647        struct commit *found = NULL;
2648        const char *name = NULL;
2649
2650        /*
2651         * There must be one and only one negative commit, and it must be
2652         * the boundary.
2653         */
2654        for (i = 0; i < revs->pending.nr; i++) {
2655                struct object *obj = revs->pending.objects[i].item;
2656                if (!(obj->flags & UNINTERESTING))
2657                        continue;
2658                obj = deref_tag(revs->repo, obj, NULL, 0);
2659                if (obj->type != OBJ_COMMIT)
2660                        die("Non commit %s?", revs->pending.objects[i].name);
2661                if (found)
2662                        die("More than one commit to dig up from, %s and %s?",
2663                            revs->pending.objects[i].name, name);
2664                found = (struct commit *) obj;
2665                name = revs->pending.objects[i].name;
2666        }
2667
2668        if (!name)
2669                found = dwim_reverse_initial(revs, &name);
2670        if (!name)
2671                die("No commit to dig up from?");
2672
2673        if (name_p)
2674                *name_p = xstrdup(name);
2675        return found;
2676}
2677
2678void init_scoreboard(struct blame_scoreboard *sb)
2679{
2680        memset(sb, 0, sizeof(struct blame_scoreboard));
2681        sb->move_score = BLAME_DEFAULT_MOVE_SCORE;
2682        sb->copy_score = BLAME_DEFAULT_COPY_SCORE;
2683}
2684
2685void setup_scoreboard(struct blame_scoreboard *sb,
2686                      const char *path,
2687                      struct blame_origin **orig)
2688{
2689        const char *final_commit_name = NULL;
2690        struct blame_origin *o;
2691        struct commit *final_commit = NULL;
2692        enum object_type type;
2693
2694        init_blame_suspects(&blame_suspects);
2695
2696        if (sb->reverse && sb->contents_from)
2697                die(_("--contents and --reverse do not blend well."));
2698
2699        if (!sb->repo)
2700                BUG("repo is NULL");
2701
2702        if (!sb->reverse) {
2703                sb->final = find_single_final(sb->revs, &final_commit_name);
2704                sb->commits.compare = compare_commits_by_commit_date;
2705        } else {
2706                sb->final = find_single_initial(sb->revs, &final_commit_name);
2707                sb->commits.compare = compare_commits_by_reverse_commit_date;
2708        }
2709
2710        if (sb->final && sb->contents_from)
2711                die(_("cannot use --contents with final commit object name"));
2712
2713        if (sb->reverse && sb->revs->first_parent_only)
2714                sb->revs->children.name = NULL;
2715
2716        if (!sb->final) {
2717                /*
2718                 * "--not A B -- path" without anything positive;
2719                 * do not default to HEAD, but use the working tree
2720                 * or "--contents".
2721                 */
2722                setup_work_tree();
2723                sb->final = fake_working_tree_commit(sb->repo,
2724                                                     &sb->revs->diffopt,
2725                                                     path, sb->contents_from);
2726                add_pending_object(sb->revs, &(sb->final->object), ":");
2727        }
2728
2729        if (sb->reverse && sb->revs->first_parent_only) {
2730                final_commit = find_single_final(sb->revs, NULL);
2731                if (!final_commit)
2732                        die(_("--reverse and --first-parent together require specified latest commit"));
2733        }
2734
2735        /*
2736         * If we have bottom, this will mark the ancestors of the
2737         * bottom commits we would reach while traversing as
2738         * uninteresting.
2739         */
2740        if (prepare_revision_walk(sb->revs))
2741                die(_("revision walk setup failed"));
2742
2743        if (sb->reverse && sb->revs->first_parent_only) {
2744                struct commit *c = final_commit;
2745
2746                sb->revs->children.name = "children";
2747                while (c->parents &&
2748                       !oideq(&c->object.oid, &sb->final->object.oid)) {
2749                        struct commit_list *l = xcalloc(1, sizeof(*l));
2750
2751                        l->item = c;
2752                        if (add_decoration(&sb->revs->children,
2753                                           &c->parents->item->object, l))
2754                                BUG("not unique item in first-parent chain");
2755                        c = c->parents->item;
2756                }
2757
2758                if (!oideq(&c->object.oid, &sb->final->object.oid))
2759                        die(_("--reverse --first-parent together require range along first-parent chain"));
2760        }
2761
2762        if (is_null_oid(&sb->final->object.oid)) {
2763                o = get_blame_suspects(sb->final);
2764                sb->final_buf = xmemdupz(o->file.ptr, o->file.size);
2765                sb->final_buf_size = o->file.size;
2766        }
2767        else {
2768                o = get_origin(sb->final, path);
2769                if (fill_blob_sha1_and_mode(sb->repo, o))
2770                        die(_("no such path %s in %s"), path, final_commit_name);
2771
2772                if (sb->revs->diffopt.flags.allow_textconv &&
2773                    textconv_object(sb->repo, path, o->mode, &o->blob_oid, 1, (char **) &sb->final_buf,
2774                                    &sb->final_buf_size))
2775                        ;
2776                else
2777                        sb->final_buf = read_object_file(&o->blob_oid, &type,
2778                                                         &sb->final_buf_size);
2779
2780                if (!sb->final_buf)
2781                        die(_("cannot read blob %s for path %s"),
2782                            oid_to_hex(&o->blob_oid),
2783                            path);
2784        }
2785        sb->num_read_blob++;
2786        prepare_lines(sb);
2787
2788        if (orig)
2789                *orig = o;
2790
2791        free((char *)final_commit_name);
2792}
2793
2794
2795
2796struct blame_entry *blame_entry_prepend(struct blame_entry *head,
2797                                        long start, long end,
2798                                        struct blame_origin *o)
2799{
2800        struct blame_entry *new_head = xcalloc(1, sizeof(struct blame_entry));
2801        new_head->lno = start;
2802        new_head->num_lines = end - start;
2803        new_head->suspect = o;
2804        new_head->s_lno = start;
2805        new_head->next = head;
2806        blame_origin_incref(o);
2807        return new_head;
2808}