Merge branch 'rs/commit-export-env-simplify'
[git] / blame.c
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
13 define_commit_slab(blame_suspects, struct blame_origin *);
14 static struct blame_suspects blame_suspects;
15
16 struct 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
25 static void set_blame_suspects(struct commit *commit, struct blame_origin *origin)
26 {
27         *blame_suspects_at(&blame_suspects, commit) = origin;
28 }
29
30 void 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  */
58 static 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  */
73 static 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
93 static 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
119 static 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
131 static 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 (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  */
161 static 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  */
174 static 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
301 static 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
314 static 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
321 static 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
343 struct 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  */
364 struct 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  */
376 struct 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  */
393 static 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->entry, hash);
421
422                 found_entry = hashmap_get_entry(&result->map, entry,
423                                                 /* member name */ entry, NULL);
424                 if (found_entry) {
425                         found_entry->count += 1;
426                 } else {
427                         entry->count = 1;
428                         hashmap_add(&result->map, &entry->entry);
429                         ++entry;
430                 }
431         }
432 }
433
434 static void free_fingerprint(struct fingerprint *f)
435 {
436         hashmap_free(&f->map);
437         free(f->entries);
438 }
439
440 /* Calculates the similarity between two fingerprints as the size of the
441  * intersection of their multisets, including repeated elements. See
442  * `struct fingerprint` for an explanation of the fingerprint representation.
443  * The similarity between "cat mat" and "father rather" is 2 because "at" is
444  * present twice in both strings while the similarity between "tim" and "mit"
445  * is 0.
446  */
447 static int fingerprint_similarity(struct fingerprint *a, struct fingerprint *b)
448 {
449         int intersection = 0;
450         struct hashmap_iter iter;
451         const struct fingerprint_entry *entry_a, *entry_b;
452
453         hashmap_for_each_entry(&b->map, &iter, entry_b,
454                                 entry /* member name */) {
455                 entry_a = hashmap_get_entry(&a->map, entry_b, entry, NULL);
456                 if (entry_a) {
457                         intersection += entry_a->count < entry_b->count ?
458                                         entry_a->count : entry_b->count;
459                 }
460         }
461         return intersection;
462 }
463
464 /* Subtracts byte-pair elements in B from A, modifying A in place.
465  */
466 static void fingerprint_subtract(struct fingerprint *a, struct fingerprint *b)
467 {
468         struct hashmap_iter iter;
469         struct fingerprint_entry *entry_a;
470         const struct fingerprint_entry *entry_b;
471
472         hashmap_iter_init(&b->map, &iter);
473
474         hashmap_for_each_entry(&b->map, &iter, entry_b,
475                                 entry /* member name */) {
476                 entry_a = hashmap_get_entry(&a->map, entry_b, entry, NULL);
477                 if (entry_a) {
478                         if (entry_a->count <= entry_b->count)
479                                 hashmap_remove(&a->map, &entry_b->entry, NULL);
480                         else
481                                 entry_a->count -= entry_b->count;
482                 }
483         }
484 }
485
486 /* Calculate fingerprints for a series of lines.
487  * Puts the fingerprints in the fingerprints array, which must have been
488  * preallocated to allow storing line_count elements.
489  */
490 static void get_line_fingerprints(struct fingerprint *fingerprints,
491                                   const char *content, const int *line_starts,
492                                   long first_line, long line_count)
493 {
494         int i;
495         const char *linestart, *lineend;
496
497         line_starts += first_line;
498         for (i = 0; i < line_count; ++i) {
499                 linestart = content + line_starts[i];
500                 lineend = content + line_starts[i + 1];
501                 get_fingerprint(fingerprints + i, linestart, lineend);
502         }
503 }
504
505 static void free_line_fingerprints(struct fingerprint *fingerprints,
506                                    int nr_fingerprints)
507 {
508         int i;
509
510         for (i = 0; i < nr_fingerprints; i++)
511                 free_fingerprint(&fingerprints[i]);
512 }
513
514 /* This contains the data necessary to linearly map a line number in one half
515  * of a diff chunk to the line in the other half of the diff chunk that is
516  * closest in terms of its position as a fraction of the length of the chunk.
517  */
518 struct line_number_mapping {
519         int destination_start, destination_length,
520                 source_start, source_length;
521 };
522
523 /* Given a line number in one range, offset and scale it to map it onto the
524  * other range.
525  * Essentially this mapping is a simple linear equation but the calculation is
526  * more complicated to allow performing it with integer operations.
527  * Another complication is that if a line could map onto many lines in the
528  * destination range then we want to choose the line at the center of those
529  * possibilities.
530  * Example: if the chunk is 2 lines long in A and 10 lines long in B then the
531  * first 5 lines in B will map onto the first line in the A chunk, while the
532  * last 5 lines will all map onto the second line in the A chunk.
533  * Example: if the chunk is 10 lines long in A and 2 lines long in B then line
534  * 0 in B will map onto line 2 in A, and line 1 in B will map onto line 7 in A.
535  */
536 static int map_line_number(int line_number,
537         const struct line_number_mapping *mapping)
538 {
539         return ((line_number - mapping->source_start) * 2 + 1) *
540                mapping->destination_length /
541                (mapping->source_length * 2) +
542                mapping->destination_start;
543 }
544
545 /* Get a pointer to the element storing the similarity between a line in A
546  * and a line in B.
547  *
548  * The similarities are stored in a 2-dimensional array. Each "row" in the
549  * array contains the similarities for a line in B. The similarities stored in
550  * a row are the similarities between the line in B and the nearby lines in A.
551  * To keep the length of each row the same, it is padded out with values of -1
552  * where the search range extends beyond the lines in A.
553  * For example, if max_search_distance_a is 2 and the two sides of a diff chunk
554  * look like this:
555  * a | m
556  * b | n
557  * c | o
558  * d | p
559  * e | q
560  * Then the similarity array will contain:
561  * [-1, -1, am, bm, cm,
562  *  -1, an, bn, cn, dn,
563  *  ao, bo, co, do, eo,
564  *  bp, cp, dp, ep, -1,
565  *  cq, dq, eq, -1, -1]
566  * Where similarities are denoted either by -1 for invalid, or the
567  * concatenation of the two lines in the diff being compared.
568  *
569  * \param similarities array of similarities between lines in A and B
570  * \param line_a the index of the line in A, in the same frame of reference as
571  *      closest_line_a.
572  * \param local_line_b the index of the line in B, relative to the first line
573  *                     in B that similarities represents.
574  * \param closest_line_a the index of the line in A that is deemed to be
575  *                       closest to local_line_b. This must be in the same
576  *                       frame of reference as line_a. This value defines
577  *                       where similarities is centered for the line in B.
578  * \param max_search_distance_a maximum distance in lines from the closest line
579  *                              in A for other lines in A for which
580  *                              similarities may be calculated.
581  */
582 static int *get_similarity(int *similarities,
583                            int line_a, int local_line_b,
584                            int closest_line_a, int max_search_distance_a)
585 {
586         assert(abs(line_a - closest_line_a) <=
587                max_search_distance_a);
588         return similarities + line_a - closest_line_a +
589                max_search_distance_a +
590                local_line_b * (max_search_distance_a * 2 + 1);
591 }
592
593 #define CERTAIN_NOTHING_MATCHES -2
594 #define CERTAINTY_NOT_CALCULATED -1
595
596 /* Given a line in B, first calculate its similarities with nearby lines in A
597  * if not already calculated, then identify the most similar and second most
598  * similar lines. The "certainty" is calculated based on those two
599  * similarities.
600  *
601  * \param start_a the index of the first line of the chunk in A
602  * \param length_a the length in lines of the chunk in A
603  * \param local_line_b the index of the line in B, relative to the first line
604  *                     in the chunk.
605  * \param fingerprints_a array of fingerprints for the chunk in A
606  * \param fingerprints_b array of fingerprints for the chunk in B
607  * \param similarities 2-dimensional array of similarities between lines in A
608  *                     and B. See get_similarity() for more details.
609  * \param certainties array of values indicating how strongly a line in B is
610  *                    matched with some line in A.
611  * \param second_best_result array of absolute indices in A for the second
612  *                           closest match of a line in B.
613  * \param result array of absolute indices in A for the closest match of a line
614  *               in B.
615  * \param max_search_distance_a maximum distance in lines from the closest line
616  *                              in A for other lines in A for which
617  *                              similarities may be calculated.
618  * \param map_line_number_in_b_to_a parameter to map_line_number().
619  */
620 static void find_best_line_matches(
621         int start_a,
622         int length_a,
623         int start_b,
624         int local_line_b,
625         struct fingerprint *fingerprints_a,
626         struct fingerprint *fingerprints_b,
627         int *similarities,
628         int *certainties,
629         int *second_best_result,
630         int *result,
631         const int max_search_distance_a,
632         const struct line_number_mapping *map_line_number_in_b_to_a)
633 {
634
635         int i, search_start, search_end, closest_local_line_a, *similarity,
636                 best_similarity = 0, second_best_similarity = 0,
637                 best_similarity_index = 0, second_best_similarity_index = 0;
638
639         /* certainty has already been calculated so no need to redo the work */
640         if (certainties[local_line_b] != CERTAINTY_NOT_CALCULATED)
641                 return;
642
643         closest_local_line_a = map_line_number(
644                 local_line_b + start_b, map_line_number_in_b_to_a) - start_a;
645
646         search_start = closest_local_line_a - max_search_distance_a;
647         if (search_start < 0)
648                 search_start = 0;
649
650         search_end = closest_local_line_a + max_search_distance_a + 1;
651         if (search_end > length_a)
652                 search_end = length_a;
653
654         for (i = search_start; i < search_end; ++i) {
655                 similarity = get_similarity(similarities,
656                                             i, local_line_b,
657                                             closest_local_line_a,
658                                             max_search_distance_a);
659                 if (*similarity == -1) {
660                         /* This value will never exceed 10 but assert just in
661                          * case
662                          */
663                         assert(abs(i - closest_local_line_a) < 1000);
664                         /* scale the similarity by (1000 - distance from
665                          * closest line) to act as a tie break between lines
666                          * that otherwise are equally similar.
667                          */
668                         *similarity = fingerprint_similarity(
669                                 fingerprints_b + local_line_b,
670                                 fingerprints_a + i) *
671                                 (1000 - abs(i - closest_local_line_a));
672                 }
673                 if (*similarity > best_similarity) {
674                         second_best_similarity = best_similarity;
675                         second_best_similarity_index = best_similarity_index;
676                         best_similarity = *similarity;
677                         best_similarity_index = i;
678                 } else if (*similarity > second_best_similarity) {
679                         second_best_similarity = *similarity;
680                         second_best_similarity_index = i;
681                 }
682         }
683
684         if (best_similarity == 0) {
685                 /* this line definitely doesn't match with anything. Mark it
686                  * with this special value so it doesn't get invalidated and
687                  * won't be recalculated.
688                  */
689                 certainties[local_line_b] = CERTAIN_NOTHING_MATCHES;
690                 result[local_line_b] = -1;
691         } else {
692                 /* Calculate the certainty with which this line matches.
693                  * If the line matches well with two lines then that reduces
694                  * the certainty. However we still want to prioritise matching
695                  * a line that matches very well with two lines over matching a
696                  * line that matches poorly with one line, hence doubling
697                  * best_similarity.
698                  * This means that if we have
699                  * line X that matches only one line with a score of 3,
700                  * line Y that matches two lines equally with a score of 5,
701                  * and line Z that matches only one line with a score or 2,
702                  * then the lines in order of certainty are X, Y, Z.
703                  */
704                 certainties[local_line_b] = best_similarity * 2 -
705                         second_best_similarity;
706
707                 /* We keep both the best and second best results to allow us to
708                  * check at a later stage of the matching process whether the
709                  * result needs to be invalidated.
710                  */
711                 result[local_line_b] = start_a + best_similarity_index;
712                 second_best_result[local_line_b] =
713                         start_a + second_best_similarity_index;
714         }
715 }
716
717 /*
718  * This finds the line that we can match with the most confidence, and
719  * uses it as a partition. It then calls itself on the lines on either side of
720  * that partition. In this way we avoid lines appearing out of order, and
721  * retain a sensible line ordering.
722  * \param start_a index of the first line in A with which lines in B may be
723  *                compared.
724  * \param start_b index of the first line in B for which matching should be
725  *                done.
726  * \param length_a number of lines in A with which lines in B may be compared.
727  * \param length_b number of lines in B for which matching should be done.
728  * \param fingerprints_a mutable array of fingerprints in A. The first element
729  *                       corresponds to the line at start_a.
730  * \param fingerprints_b array of fingerprints in B. The first element
731  *                       corresponds to the line at start_b.
732  * \param similarities 2-dimensional array of similarities between lines in A
733  *                     and B. See get_similarity() for more details.
734  * \param certainties array of values indicating how strongly a line in B is
735  *                    matched with some line in A.
736  * \param second_best_result array of absolute indices in A for the second
737  *                           closest match of a line in B.
738  * \param result array of absolute indices in A for the closest match of a line
739  *               in B.
740  * \param max_search_distance_a maximum distance in lines from the closest line
741  *                            in A for other lines in A for which
742  *                            similarities may be calculated.
743  * \param max_search_distance_b an upper bound on the greatest possible
744  *                            distance between lines in B such that they will
745  *                              both be compared with the same line in A
746  *                            according to max_search_distance_a.
747  * \param map_line_number_in_b_to_a parameter to map_line_number().
748  */
749 static void fuzzy_find_matching_lines_recurse(
750         int start_a, int start_b,
751         int length_a, int length_b,
752         struct fingerprint *fingerprints_a,
753         struct fingerprint *fingerprints_b,
754         int *similarities,
755         int *certainties,
756         int *second_best_result,
757         int *result,
758         int max_search_distance_a,
759         int max_search_distance_b,
760         const struct line_number_mapping *map_line_number_in_b_to_a)
761 {
762         int i, invalidate_min, invalidate_max, offset_b,
763                 second_half_start_a, second_half_start_b,
764                 second_half_length_a, second_half_length_b,
765                 most_certain_line_a, most_certain_local_line_b = -1,
766                 most_certain_line_certainty = -1,
767                 closest_local_line_a;
768
769         for (i = 0; i < length_b; ++i) {
770                 find_best_line_matches(start_a,
771                                        length_a,
772                                        start_b,
773                                        i,
774                                        fingerprints_a,
775                                        fingerprints_b,
776                                        similarities,
777                                        certainties,
778                                        second_best_result,
779                                        result,
780                                        max_search_distance_a,
781                                        map_line_number_in_b_to_a);
782
783                 if (certainties[i] > most_certain_line_certainty) {
784                         most_certain_line_certainty = certainties[i];
785                         most_certain_local_line_b = i;
786                 }
787         }
788
789         /* No matches. */
790         if (most_certain_local_line_b == -1)
791                 return;
792
793         most_certain_line_a = result[most_certain_local_line_b];
794
795         /*
796          * Subtract the most certain line's fingerprint in B from the matched
797          * fingerprint in A. This means that other lines in B can't also match
798          * the same parts of the line in A.
799          */
800         fingerprint_subtract(fingerprints_a + most_certain_line_a - start_a,
801                              fingerprints_b + most_certain_local_line_b);
802
803         /* Invalidate results that may be affected by the choice of most
804          * certain line.
805          */
806         invalidate_min = most_certain_local_line_b - max_search_distance_b;
807         invalidate_max = most_certain_local_line_b + max_search_distance_b + 1;
808         if (invalidate_min < 0)
809                 invalidate_min = 0;
810         if (invalidate_max > length_b)
811                 invalidate_max = length_b;
812
813         /* As the fingerprint in A has changed, discard previously calculated
814          * similarity values with that fingerprint.
815          */
816         for (i = invalidate_min; i < invalidate_max; ++i) {
817                 closest_local_line_a = map_line_number(
818                         i + start_b, map_line_number_in_b_to_a) - start_a;
819
820                 /* Check that the lines in A and B are close enough that there
821                  * is a similarity value for them.
822                  */
823                 if (abs(most_certain_line_a - start_a - closest_local_line_a) >
824                         max_search_distance_a) {
825                         continue;
826                 }
827
828                 *get_similarity(similarities, most_certain_line_a - start_a,
829                                 i, closest_local_line_a,
830                                 max_search_distance_a) = -1;
831         }
832
833         /* More invalidating of results that may be affected by the choice of
834          * most certain line.
835          * Discard the matches for lines in B that are currently matched with a
836          * line in A such that their ordering contradicts the ordering imposed
837          * by the choice of most certain line.
838          */
839         for (i = most_certain_local_line_b - 1; i >= invalidate_min; --i) {
840                 /* In this loop we discard results for lines in B that are
841                  * before most-certain-line-B but are matched with a line in A
842                  * that is after most-certain-line-A.
843                  */
844                 if (certainties[i] >= 0 &&
845                     (result[i] >= most_certain_line_a ||
846                      second_best_result[i] >= most_certain_line_a)) {
847                         certainties[i] = CERTAINTY_NOT_CALCULATED;
848                 }
849         }
850         for (i = most_certain_local_line_b + 1; i < invalidate_max; ++i) {
851                 /* In this loop we discard results for lines in B that are
852                  * after most-certain-line-B but are matched with a line in A
853                  * that is before most-certain-line-A.
854                  */
855                 if (certainties[i] >= 0 &&
856                     (result[i] <= most_certain_line_a ||
857                      second_best_result[i] <= most_certain_line_a)) {
858                         certainties[i] = CERTAINTY_NOT_CALCULATED;
859                 }
860         }
861
862         /* Repeat the matching process for lines before the most certain line.
863          */
864         if (most_certain_local_line_b > 0) {
865                 fuzzy_find_matching_lines_recurse(
866                         start_a, start_b,
867                         most_certain_line_a + 1 - start_a,
868                         most_certain_local_line_b,
869                         fingerprints_a, fingerprints_b, similarities,
870                         certainties, second_best_result, result,
871                         max_search_distance_a,
872                         max_search_distance_b,
873                         map_line_number_in_b_to_a);
874         }
875         /* Repeat the matching process for lines after the most certain line.
876          */
877         if (most_certain_local_line_b + 1 < length_b) {
878                 second_half_start_a = most_certain_line_a;
879                 offset_b = most_certain_local_line_b + 1;
880                 second_half_start_b = start_b + offset_b;
881                 second_half_length_a =
882                         length_a + start_a - second_half_start_a;
883                 second_half_length_b =
884                         length_b + start_b - second_half_start_b;
885                 fuzzy_find_matching_lines_recurse(
886                         second_half_start_a, second_half_start_b,
887                         second_half_length_a, second_half_length_b,
888                         fingerprints_a + second_half_start_a - start_a,
889                         fingerprints_b + offset_b,
890                         similarities +
891                                 offset_b * (max_search_distance_a * 2 + 1),
892                         certainties + offset_b,
893                         second_best_result + offset_b, result + offset_b,
894                         max_search_distance_a,
895                         max_search_distance_b,
896                         map_line_number_in_b_to_a);
897         }
898 }
899
900 /* Find the lines in the parent line range that most closely match the lines in
901  * the target line range. This is accomplished by matching fingerprints in each
902  * blame_origin, and choosing the best matches that preserve the line ordering.
903  * See struct fingerprint for details of fingerprint matching, and
904  * fuzzy_find_matching_lines_recurse for details of preserving line ordering.
905  *
906  * The performance is believed to be O(n log n) in the typical case and O(n^2)
907  * in a pathological case, where n is the number of lines in the target range.
908  */
909 static int *fuzzy_find_matching_lines(struct blame_origin *parent,
910                                       struct blame_origin *target,
911                                       int tlno, int parent_slno, int same,
912                                       int parent_len)
913 {
914         /* We use the terminology "A" for the left hand side of the diff AKA
915          * parent, and "B" for the right hand side of the diff AKA target. */
916         int start_a = parent_slno;
917         int length_a = parent_len;
918         int start_b = tlno;
919         int length_b = same - tlno;
920
921         struct line_number_mapping map_line_number_in_b_to_a = {
922                 start_a, length_a, start_b, length_b
923         };
924
925         struct fingerprint *fingerprints_a = parent->fingerprints;
926         struct fingerprint *fingerprints_b = target->fingerprints;
927
928         int i, *result, *second_best_result,
929                 *certainties, *similarities, similarity_count;
930
931         /*
932          * max_search_distance_a means that given a line in B, compare it to
933          * the line in A that is closest to its position, and the lines in A
934          * that are no greater than max_search_distance_a lines away from the
935          * closest line in A.
936          *
937          * max_search_distance_b is an upper bound on the greatest possible
938          * distance between lines in B such that they will both be compared
939          * with the same line in A according to max_search_distance_a.
940          */
941         int max_search_distance_a = 10, max_search_distance_b;
942
943         if (length_a <= 0)
944                 return NULL;
945
946         if (max_search_distance_a >= length_a)
947                 max_search_distance_a = length_a ? length_a - 1 : 0;
948
949         max_search_distance_b = ((2 * max_search_distance_a + 1) * length_b
950                                  - 1) / length_a;
951
952         result = xcalloc(sizeof(int), length_b);
953         second_best_result = xcalloc(sizeof(int), length_b);
954         certainties = xcalloc(sizeof(int), length_b);
955
956         /* See get_similarity() for details of similarities. */
957         similarity_count = length_b * (max_search_distance_a * 2 + 1);
958         similarities = xcalloc(sizeof(int), similarity_count);
959
960         for (i = 0; i < length_b; ++i) {
961                 result[i] = -1;
962                 second_best_result[i] = -1;
963                 certainties[i] = CERTAINTY_NOT_CALCULATED;
964         }
965
966         for (i = 0; i < similarity_count; ++i)
967                 similarities[i] = -1;
968
969         fuzzy_find_matching_lines_recurse(start_a, start_b,
970                                           length_a, length_b,
971                                           fingerprints_a + start_a,
972                                           fingerprints_b + start_b,
973                                           similarities,
974                                           certainties,
975                                           second_best_result,
976                                           result,
977                                           max_search_distance_a,
978                                           max_search_distance_b,
979                                           &map_line_number_in_b_to_a);
980
981         free(similarities);
982         free(certainties);
983         free(second_best_result);
984
985         return result;
986 }
987
988 static void fill_origin_fingerprints(struct blame_origin *o)
989 {
990         int *line_starts;
991
992         if (o->fingerprints)
993                 return;
994         o->num_lines = find_line_starts(&line_starts, o->file.ptr,
995                                         o->file.size);
996         o->fingerprints = xcalloc(sizeof(struct fingerprint), o->num_lines);
997         get_line_fingerprints(o->fingerprints, o->file.ptr, line_starts,
998                               0, o->num_lines);
999         free(line_starts);
1000 }
1001
1002 static void drop_origin_fingerprints(struct blame_origin *o)
1003 {
1004         if (o->fingerprints) {
1005                 free_line_fingerprints(o->fingerprints, o->num_lines);
1006                 o->num_lines = 0;
1007                 FREE_AND_NULL(o->fingerprints);
1008         }
1009 }
1010
1011 /*
1012  * Given an origin, prepare mmfile_t structure to be used by the
1013  * diff machinery
1014  */
1015 static void fill_origin_blob(struct diff_options *opt,
1016                              struct blame_origin *o, mmfile_t *file,
1017                              int *num_read_blob, int fill_fingerprints)
1018 {
1019         if (!o->file.ptr) {
1020                 enum object_type type;
1021                 unsigned long file_size;
1022
1023                 (*num_read_blob)++;
1024                 if (opt->flags.allow_textconv &&
1025                     textconv_object(opt->repo, o->path, o->mode,
1026                                     &o->blob_oid, 1, &file->ptr, &file_size))
1027                         ;
1028                 else
1029                         file->ptr = read_object_file(&o->blob_oid, &type,
1030                                                      &file_size);
1031                 file->size = file_size;
1032
1033                 if (!file->ptr)
1034                         die("Cannot read blob %s for path %s",
1035                             oid_to_hex(&o->blob_oid),
1036                             o->path);
1037                 o->file = *file;
1038         }
1039         else
1040                 *file = o->file;
1041         if (fill_fingerprints)
1042                 fill_origin_fingerprints(o);
1043 }
1044
1045 static void drop_origin_blob(struct blame_origin *o)
1046 {
1047         FREE_AND_NULL(o->file.ptr);
1048         drop_origin_fingerprints(o);
1049 }
1050
1051 /*
1052  * Any merge of blames happens on lists of blames that arrived via
1053  * different parents in a single suspect.  In this case, we want to
1054  * sort according to the suspect line numbers as opposed to the final
1055  * image line numbers.  The function body is somewhat longish because
1056  * it avoids unnecessary writes.
1057  */
1058
1059 static struct blame_entry *blame_merge(struct blame_entry *list1,
1060                                        struct blame_entry *list2)
1061 {
1062         struct blame_entry *p1 = list1, *p2 = list2,
1063                 **tail = &list1;
1064
1065         if (!p1)
1066                 return p2;
1067         if (!p2)
1068                 return p1;
1069
1070         if (p1->s_lno <= p2->s_lno) {
1071                 do {
1072                         tail = &p1->next;
1073                         if ((p1 = *tail) == NULL) {
1074                                 *tail = p2;
1075                                 return list1;
1076                         }
1077                 } while (p1->s_lno <= p2->s_lno);
1078         }
1079         for (;;) {
1080                 *tail = p2;
1081                 do {
1082                         tail = &p2->next;
1083                         if ((p2 = *tail) == NULL)  {
1084                                 *tail = p1;
1085                                 return list1;
1086                         }
1087                 } while (p1->s_lno > p2->s_lno);
1088                 *tail = p1;
1089                 do {
1090                         tail = &p1->next;
1091                         if ((p1 = *tail) == NULL) {
1092                                 *tail = p2;
1093                                 return list1;
1094                         }
1095                 } while (p1->s_lno <= p2->s_lno);
1096         }
1097 }
1098
1099 static void *get_next_blame(const void *p)
1100 {
1101         return ((struct blame_entry *)p)->next;
1102 }
1103
1104 static void set_next_blame(void *p1, void *p2)
1105 {
1106         ((struct blame_entry *)p1)->next = p2;
1107 }
1108
1109 /*
1110  * Final image line numbers are all different, so we don't need a
1111  * three-way comparison here.
1112  */
1113
1114 static int compare_blame_final(const void *p1, const void *p2)
1115 {
1116         return ((struct blame_entry *)p1)->lno > ((struct blame_entry *)p2)->lno
1117                 ? 1 : -1;
1118 }
1119
1120 static int compare_blame_suspect(const void *p1, const void *p2)
1121 {
1122         const struct blame_entry *s1 = p1, *s2 = p2;
1123         /*
1124          * to allow for collating suspects, we sort according to the
1125          * respective pointer value as the primary sorting criterion.
1126          * The actual relation is pretty unimportant as long as it
1127          * establishes a total order.  Comparing as integers gives us
1128          * that.
1129          */
1130         if (s1->suspect != s2->suspect)
1131                 return (intptr_t)s1->suspect > (intptr_t)s2->suspect ? 1 : -1;
1132         if (s1->s_lno == s2->s_lno)
1133                 return 0;
1134         return s1->s_lno > s2->s_lno ? 1 : -1;
1135 }
1136
1137 void blame_sort_final(struct blame_scoreboard *sb)
1138 {
1139         sb->ent = llist_mergesort(sb->ent, get_next_blame, set_next_blame,
1140                                   compare_blame_final);
1141 }
1142
1143 static int compare_commits_by_reverse_commit_date(const void *a,
1144                                                   const void *b,
1145                                                   void *c)
1146 {
1147         return -compare_commits_by_commit_date(a, b, c);
1148 }
1149
1150 /*
1151  * For debugging -- origin is refcounted, and this asserts that
1152  * we do not underflow.
1153  */
1154 static void sanity_check_refcnt(struct blame_scoreboard *sb)
1155 {
1156         int baa = 0;
1157         struct blame_entry *ent;
1158
1159         for (ent = sb->ent; ent; ent = ent->next) {
1160                 /* Nobody should have zero or negative refcnt */
1161                 if (ent->suspect->refcnt <= 0) {
1162                         fprintf(stderr, "%s in %s has negative refcnt %d\n",
1163                                 ent->suspect->path,
1164                                 oid_to_hex(&ent->suspect->commit->object.oid),
1165                                 ent->suspect->refcnt);
1166                         baa = 1;
1167                 }
1168         }
1169         if (baa)
1170                 sb->on_sanity_fail(sb, baa);
1171 }
1172
1173 /*
1174  * If two blame entries that are next to each other came from
1175  * contiguous lines in the same origin (i.e. <commit, path> pair),
1176  * merge them together.
1177  */
1178 void blame_coalesce(struct blame_scoreboard *sb)
1179 {
1180         struct blame_entry *ent, *next;
1181
1182         for (ent = sb->ent; ent && (next = ent->next); ent = next) {
1183                 if (ent->suspect == next->suspect &&
1184                     ent->s_lno + ent->num_lines == next->s_lno &&
1185                     ent->ignored == next->ignored &&
1186                     ent->unblamable == next->unblamable) {
1187                         ent->num_lines += next->num_lines;
1188                         ent->next = next->next;
1189                         blame_origin_decref(next->suspect);
1190                         free(next);
1191                         ent->score = 0;
1192                         next = ent; /* again */
1193                 }
1194         }
1195
1196         if (sb->debug) /* sanity */
1197                 sanity_check_refcnt(sb);
1198 }
1199
1200 /*
1201  * Merge the given sorted list of blames into a preexisting origin.
1202  * If there were no previous blames to that commit, it is entered into
1203  * the commit priority queue of the score board.
1204  */
1205
1206 static void queue_blames(struct blame_scoreboard *sb, struct blame_origin *porigin,
1207                          struct blame_entry *sorted)
1208 {
1209         if (porigin->suspects)
1210                 porigin->suspects = blame_merge(porigin->suspects, sorted);
1211         else {
1212                 struct blame_origin *o;
1213                 for (o = get_blame_suspects(porigin->commit); o; o = o->next) {
1214                         if (o->suspects) {
1215                                 porigin->suspects = sorted;
1216                                 return;
1217                         }
1218                 }
1219                 porigin->suspects = sorted;
1220                 prio_queue_put(&sb->commits, porigin->commit);
1221         }
1222 }
1223
1224 /*
1225  * Fill the blob_sha1 field of an origin if it hasn't, so that later
1226  * call to fill_origin_blob() can use it to locate the data.  blob_sha1
1227  * for an origin is also used to pass the blame for the entire file to
1228  * the parent to detect the case where a child's blob is identical to
1229  * that of its parent's.
1230  *
1231  * This also fills origin->mode for corresponding tree path.
1232  */
1233 static int fill_blob_sha1_and_mode(struct repository *r,
1234                                    struct blame_origin *origin)
1235 {
1236         if (!is_null_oid(&origin->blob_oid))
1237                 return 0;
1238         if (get_tree_entry(r, &origin->commit->object.oid, origin->path, &origin->blob_oid, &origin->mode))
1239                 goto error_out;
1240         if (oid_object_info(r, &origin->blob_oid, NULL) != OBJ_BLOB)
1241                 goto error_out;
1242         return 0;
1243  error_out:
1244         oidclr(&origin->blob_oid);
1245         origin->mode = S_IFINVALID;
1246         return -1;
1247 }
1248
1249 /*
1250  * We have an origin -- check if the same path exists in the
1251  * parent and return an origin structure to represent it.
1252  */
1253 static struct blame_origin *find_origin(struct repository *r,
1254                                         struct commit *parent,
1255                                         struct blame_origin *origin)
1256 {
1257         struct blame_origin *porigin;
1258         struct diff_options diff_opts;
1259         const char *paths[2];
1260
1261         /* First check any existing origins */
1262         for (porigin = get_blame_suspects(parent); porigin; porigin = porigin->next)
1263                 if (!strcmp(porigin->path, origin->path)) {
1264                         /*
1265                          * The same path between origin and its parent
1266                          * without renaming -- the most common case.
1267                          */
1268                         return blame_origin_incref (porigin);
1269                 }
1270
1271         /* See if the origin->path is different between parent
1272          * and origin first.  Most of the time they are the
1273          * same and diff-tree is fairly efficient about this.
1274          */
1275         repo_diff_setup(r, &diff_opts);
1276         diff_opts.flags.recursive = 1;
1277         diff_opts.detect_rename = 0;
1278         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1279         paths[0] = origin->path;
1280         paths[1] = NULL;
1281
1282         parse_pathspec(&diff_opts.pathspec,
1283                        PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
1284                        PATHSPEC_LITERAL_PATH, "", paths);
1285         diff_setup_done(&diff_opts);
1286
1287         if (is_null_oid(&origin->commit->object.oid))
1288                 do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
1289         else
1290                 diff_tree_oid(get_commit_tree_oid(parent),
1291                               get_commit_tree_oid(origin->commit),
1292                               "", &diff_opts);
1293         diffcore_std(&diff_opts);
1294
1295         if (!diff_queued_diff.nr) {
1296                 /* The path is the same as parent */
1297                 porigin = get_origin(parent, origin->path);
1298                 oidcpy(&porigin->blob_oid, &origin->blob_oid);
1299                 porigin->mode = origin->mode;
1300         } else {
1301                 /*
1302                  * Since origin->path is a pathspec, if the parent
1303                  * commit had it as a directory, we will see a whole
1304                  * bunch of deletion of files in the directory that we
1305                  * do not care about.
1306                  */
1307                 int i;
1308                 struct diff_filepair *p = NULL;
1309                 for (i = 0; i < diff_queued_diff.nr; i++) {
1310                         const char *name;
1311                         p = diff_queued_diff.queue[i];
1312                         name = p->one->path ? p->one->path : p->two->path;
1313                         if (!strcmp(name, origin->path))
1314                                 break;
1315                 }
1316                 if (!p)
1317                         die("internal error in blame::find_origin");
1318                 switch (p->status) {
1319                 default:
1320                         die("internal error in blame::find_origin (%c)",
1321                             p->status);
1322                 case 'M':
1323                         porigin = get_origin(parent, origin->path);
1324                         oidcpy(&porigin->blob_oid, &p->one->oid);
1325                         porigin->mode = p->one->mode;
1326                         break;
1327                 case 'A':
1328                 case 'T':
1329                         /* Did not exist in parent, or type changed */
1330                         break;
1331                 }
1332         }
1333         diff_flush(&diff_opts);
1334         clear_pathspec(&diff_opts.pathspec);
1335         return porigin;
1336 }
1337
1338 /*
1339  * We have an origin -- find the path that corresponds to it in its
1340  * parent and return an origin structure to represent it.
1341  */
1342 static struct blame_origin *find_rename(struct repository *r,
1343                                         struct commit *parent,
1344                                         struct blame_origin *origin)
1345 {
1346         struct blame_origin *porigin = NULL;
1347         struct diff_options diff_opts;
1348         int i;
1349
1350         repo_diff_setup(r, &diff_opts);
1351         diff_opts.flags.recursive = 1;
1352         diff_opts.detect_rename = DIFF_DETECT_RENAME;
1353         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1354         diff_opts.single_follow = origin->path;
1355         diff_setup_done(&diff_opts);
1356
1357         if (is_null_oid(&origin->commit->object.oid))
1358                 do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
1359         else
1360                 diff_tree_oid(get_commit_tree_oid(parent),
1361                               get_commit_tree_oid(origin->commit),
1362                               "", &diff_opts);
1363         diffcore_std(&diff_opts);
1364
1365         for (i = 0; i < diff_queued_diff.nr; i++) {
1366                 struct diff_filepair *p = diff_queued_diff.queue[i];
1367                 if ((p->status == 'R' || p->status == 'C') &&
1368                     !strcmp(p->two->path, origin->path)) {
1369                         porigin = get_origin(parent, p->one->path);
1370                         oidcpy(&porigin->blob_oid, &p->one->oid);
1371                         porigin->mode = p->one->mode;
1372                         break;
1373                 }
1374         }
1375         diff_flush(&diff_opts);
1376         clear_pathspec(&diff_opts.pathspec);
1377         return porigin;
1378 }
1379
1380 /*
1381  * Append a new blame entry to a given output queue.
1382  */
1383 static void add_blame_entry(struct blame_entry ***queue,
1384                             const struct blame_entry *src)
1385 {
1386         struct blame_entry *e = xmalloc(sizeof(*e));
1387         memcpy(e, src, sizeof(*e));
1388         blame_origin_incref(e->suspect);
1389
1390         e->next = **queue;
1391         **queue = e;
1392         *queue = &e->next;
1393 }
1394
1395 /*
1396  * src typically is on-stack; we want to copy the information in it to
1397  * a malloced blame_entry that gets added to the given queue.  The
1398  * origin of dst loses a refcnt.
1399  */
1400 static void dup_entry(struct blame_entry ***queue,
1401                       struct blame_entry *dst, struct blame_entry *src)
1402 {
1403         blame_origin_incref(src->suspect);
1404         blame_origin_decref(dst->suspect);
1405         memcpy(dst, src, sizeof(*src));
1406         dst->next = **queue;
1407         **queue = dst;
1408         *queue = &dst->next;
1409 }
1410
1411 const char *blame_nth_line(struct blame_scoreboard *sb, long lno)
1412 {
1413         return sb->final_buf + sb->lineno[lno];
1414 }
1415
1416 /*
1417  * It is known that lines between tlno to same came from parent, and e
1418  * has an overlap with that range.  it also is known that parent's
1419  * line plno corresponds to e's line tlno.
1420  *
1421  *                <---- e ----->
1422  *                   <------>
1423  *                   <------------>
1424  *             <------------>
1425  *             <------------------>
1426  *
1427  * Split e into potentially three parts; before this chunk, the chunk
1428  * to be blamed for the parent, and after that portion.
1429  */
1430 static void split_overlap(struct blame_entry *split,
1431                           struct blame_entry *e,
1432                           int tlno, int plno, int same,
1433                           struct blame_origin *parent)
1434 {
1435         int chunk_end_lno;
1436         int i;
1437         memset(split, 0, sizeof(struct blame_entry [3]));
1438
1439         for (i = 0; i < 3; i++) {
1440                 split[i].ignored = e->ignored;
1441                 split[i].unblamable = e->unblamable;
1442         }
1443
1444         if (e->s_lno < tlno) {
1445                 /* there is a pre-chunk part not blamed on parent */
1446                 split[0].suspect = blame_origin_incref(e->suspect);
1447                 split[0].lno = e->lno;
1448                 split[0].s_lno = e->s_lno;
1449                 split[0].num_lines = tlno - e->s_lno;
1450                 split[1].lno = e->lno + tlno - e->s_lno;
1451                 split[1].s_lno = plno;
1452         }
1453         else {
1454                 split[1].lno = e->lno;
1455                 split[1].s_lno = plno + (e->s_lno - tlno);
1456         }
1457
1458         if (same < e->s_lno + e->num_lines) {
1459                 /* there is a post-chunk part not blamed on parent */
1460                 split[2].suspect = blame_origin_incref(e->suspect);
1461                 split[2].lno = e->lno + (same - e->s_lno);
1462                 split[2].s_lno = e->s_lno + (same - e->s_lno);
1463                 split[2].num_lines = e->s_lno + e->num_lines - same;
1464                 chunk_end_lno = split[2].lno;
1465         }
1466         else
1467                 chunk_end_lno = e->lno + e->num_lines;
1468         split[1].num_lines = chunk_end_lno - split[1].lno;
1469
1470         /*
1471          * if it turns out there is nothing to blame the parent for,
1472          * forget about the splitting.  !split[1].suspect signals this.
1473          */
1474         if (split[1].num_lines < 1)
1475                 return;
1476         split[1].suspect = blame_origin_incref(parent);
1477 }
1478
1479 /*
1480  * split_overlap() divided an existing blame e into up to three parts
1481  * in split.  Any assigned blame is moved to queue to
1482  * reflect the split.
1483  */
1484 static void split_blame(struct blame_entry ***blamed,
1485                         struct blame_entry ***unblamed,
1486                         struct blame_entry *split,
1487                         struct blame_entry *e)
1488 {
1489         if (split[0].suspect && split[2].suspect) {
1490                 /* The first part (reuse storage for the existing entry e) */
1491                 dup_entry(unblamed, e, &split[0]);
1492
1493                 /* The last part -- me */
1494                 add_blame_entry(unblamed, &split[2]);
1495
1496                 /* ... and the middle part -- parent */
1497                 add_blame_entry(blamed, &split[1]);
1498         }
1499         else if (!split[0].suspect && !split[2].suspect)
1500                 /*
1501                  * The parent covers the entire area; reuse storage for
1502                  * e and replace it with the parent.
1503                  */
1504                 dup_entry(blamed, e, &split[1]);
1505         else if (split[0].suspect) {
1506                 /* me and then parent */
1507                 dup_entry(unblamed, e, &split[0]);
1508                 add_blame_entry(blamed, &split[1]);
1509         }
1510         else {
1511                 /* parent and then me */
1512                 dup_entry(blamed, e, &split[1]);
1513                 add_blame_entry(unblamed, &split[2]);
1514         }
1515 }
1516
1517 /*
1518  * After splitting the blame, the origins used by the
1519  * on-stack blame_entry should lose one refcnt each.
1520  */
1521 static void decref_split(struct blame_entry *split)
1522 {
1523         int i;
1524
1525         for (i = 0; i < 3; i++)
1526                 blame_origin_decref(split[i].suspect);
1527 }
1528
1529 /*
1530  * reverse_blame reverses the list given in head, appending tail.
1531  * That allows us to build lists in reverse order, then reverse them
1532  * afterwards.  This can be faster than building the list in proper
1533  * order right away.  The reason is that building in proper order
1534  * requires writing a link in the _previous_ element, while building
1535  * in reverse order just requires placing the list head into the
1536  * _current_ element.
1537  */
1538
1539 static struct blame_entry *reverse_blame(struct blame_entry *head,
1540                                          struct blame_entry *tail)
1541 {
1542         while (head) {
1543                 struct blame_entry *next = head->next;
1544                 head->next = tail;
1545                 tail = head;
1546                 head = next;
1547         }
1548         return tail;
1549 }
1550
1551 /*
1552  * Splits a blame entry into two entries at 'len' lines.  The original 'e'
1553  * consists of len lines, i.e. [e->lno, e->lno + len), and the second part,
1554  * which is returned, consists of the remainder: [e->lno + len, e->lno +
1555  * e->num_lines).  The caller needs to sort out the reference counting for the
1556  * new entry's suspect.
1557  */
1558 static struct blame_entry *split_blame_at(struct blame_entry *e, int len,
1559                                           struct blame_origin *new_suspect)
1560 {
1561         struct blame_entry *n = xcalloc(1, sizeof(struct blame_entry));
1562
1563         n->suspect = new_suspect;
1564         n->ignored = e->ignored;
1565         n->unblamable = e->unblamable;
1566         n->lno = e->lno + len;
1567         n->s_lno = e->s_lno + len;
1568         n->num_lines = e->num_lines - len;
1569         e->num_lines = len;
1570         e->score = 0;
1571         return n;
1572 }
1573
1574 struct blame_line_tracker {
1575         int is_parent;
1576         int s_lno;
1577 };
1578
1579 static int are_lines_adjacent(struct blame_line_tracker *first,
1580                               struct blame_line_tracker *second)
1581 {
1582         return first->is_parent == second->is_parent &&
1583                first->s_lno + 1 == second->s_lno;
1584 }
1585
1586 static int scan_parent_range(struct fingerprint *p_fps,
1587                              struct fingerprint *t_fps, int t_idx,
1588                              int from, int nr_lines)
1589 {
1590         int sim, p_idx;
1591         #define FINGERPRINT_FILE_THRESHOLD      10
1592         int best_sim_val = FINGERPRINT_FILE_THRESHOLD;
1593         int best_sim_idx = -1;
1594
1595         for (p_idx = from; p_idx < from + nr_lines; p_idx++) {
1596                 sim = fingerprint_similarity(&t_fps[t_idx], &p_fps[p_idx]);
1597                 if (sim < best_sim_val)
1598                         continue;
1599                 /* Break ties with the closest-to-target line number */
1600                 if (sim == best_sim_val && best_sim_idx != -1 &&
1601                     abs(best_sim_idx - t_idx) < abs(p_idx - t_idx))
1602                         continue;
1603                 best_sim_val = sim;
1604                 best_sim_idx = p_idx;
1605         }
1606         return best_sim_idx;
1607 }
1608
1609 /*
1610  * The first pass checks the blame entry (from the target) against the parent's
1611  * diff chunk.  If that fails for a line, the second pass tries to match that
1612  * line to any part of parent file.  That catches cases where a change was
1613  * broken into two chunks by 'context.'
1614  */
1615 static void guess_line_blames(struct blame_origin *parent,
1616                               struct blame_origin *target,
1617                               int tlno, int offset, int same, int parent_len,
1618                               struct blame_line_tracker *line_blames)
1619 {
1620         int i, best_idx, target_idx;
1621         int parent_slno = tlno + offset;
1622         int *fuzzy_matches;
1623
1624         fuzzy_matches = fuzzy_find_matching_lines(parent, target,
1625                                                   tlno, parent_slno, same,
1626                                                   parent_len);
1627         for (i = 0; i < same - tlno; i++) {
1628                 target_idx = tlno + i;
1629                 if (fuzzy_matches && fuzzy_matches[i] >= 0) {
1630                         best_idx = fuzzy_matches[i];
1631                 } else {
1632                         best_idx = scan_parent_range(parent->fingerprints,
1633                                                      target->fingerprints,
1634                                                      target_idx, 0,
1635                                                      parent->num_lines);
1636                 }
1637                 if (best_idx >= 0) {
1638                         line_blames[i].is_parent = 1;
1639                         line_blames[i].s_lno = best_idx;
1640                 } else {
1641                         line_blames[i].is_parent = 0;
1642                         line_blames[i].s_lno = target_idx;
1643                 }
1644         }
1645         free(fuzzy_matches);
1646 }
1647
1648 /*
1649  * This decides which parts of a blame entry go to the parent (added to the
1650  * ignoredp list) and which stay with the target (added to the diffp list).  The
1651  * actual decision was made in a separate heuristic function, and those answers
1652  * for the lines in 'e' are in line_blames.  This consumes e, essentially
1653  * putting it on a list.
1654  *
1655  * Note that the blame entries on the ignoredp list are not necessarily sorted
1656  * with respect to the parent's line numbers yet.
1657  */
1658 static void ignore_blame_entry(struct blame_entry *e,
1659                                struct blame_origin *parent,
1660                                struct blame_entry **diffp,
1661                                struct blame_entry **ignoredp,
1662                                struct blame_line_tracker *line_blames)
1663 {
1664         int entry_len, nr_lines, i;
1665
1666         /*
1667          * We carve new entries off the front of e.  Each entry comes from a
1668          * contiguous chunk of lines: adjacent lines from the same origin
1669          * (either the parent or the target).
1670          */
1671         entry_len = 1;
1672         nr_lines = e->num_lines;        /* e changes in the loop */
1673         for (i = 0; i < nr_lines; i++) {
1674                 struct blame_entry *next = NULL;
1675
1676                 /*
1677                  * We are often adjacent to the next line - only split the blame
1678                  * entry when we have to.
1679                  */
1680                 if (i + 1 < nr_lines) {
1681                         if (are_lines_adjacent(&line_blames[i],
1682                                                &line_blames[i + 1])) {
1683                                 entry_len++;
1684                                 continue;
1685                         }
1686                         next = split_blame_at(e, entry_len,
1687                                               blame_origin_incref(e->suspect));
1688                 }
1689                 if (line_blames[i].is_parent) {
1690                         e->ignored = 1;
1691                         blame_origin_decref(e->suspect);
1692                         e->suspect = blame_origin_incref(parent);
1693                         e->s_lno = line_blames[i - entry_len + 1].s_lno;
1694                         e->next = *ignoredp;
1695                         *ignoredp = e;
1696                 } else {
1697                         e->unblamable = 1;
1698                         /* e->s_lno is already in the target's address space. */
1699                         e->next = *diffp;
1700                         *diffp = e;
1701                 }
1702                 assert(e->num_lines == entry_len);
1703                 e = next;
1704                 entry_len = 1;
1705         }
1706         assert(!e);
1707 }
1708
1709 /*
1710  * Process one hunk from the patch between the current suspect for
1711  * blame_entry e and its parent.  This first blames any unfinished
1712  * entries before the chunk (which is where target and parent start
1713  * differing) on the parent, and then splits blame entries at the
1714  * start and at the end of the difference region.  Since use of -M and
1715  * -C options may lead to overlapping/duplicate source line number
1716  * ranges, all we can rely on from sorting/merging is the order of the
1717  * first suspect line number.
1718  *
1719  * tlno: line number in the target where this chunk begins
1720  * same: line number in the target where this chunk ends
1721  * offset: add to tlno to get the chunk starting point in the parent
1722  * parent_len: number of lines in the parent chunk
1723  */
1724 static void blame_chunk(struct blame_entry ***dstq, struct blame_entry ***srcq,
1725                         int tlno, int offset, int same, int parent_len,
1726                         struct blame_origin *parent,
1727                         struct blame_origin *target, int ignore_diffs)
1728 {
1729         struct blame_entry *e = **srcq;
1730         struct blame_entry *samep = NULL, *diffp = NULL, *ignoredp = NULL;
1731         struct blame_line_tracker *line_blames = NULL;
1732
1733         while (e && e->s_lno < tlno) {
1734                 struct blame_entry *next = e->next;
1735                 /*
1736                  * current record starts before differing portion.  If
1737                  * it reaches into it, we need to split it up and
1738                  * examine the second part separately.
1739                  */
1740                 if (e->s_lno + e->num_lines > tlno) {
1741                         /* Move second half to a new record */
1742                         struct blame_entry *n;
1743
1744                         n = split_blame_at(e, tlno - e->s_lno, e->suspect);
1745                         /* Push new record to diffp */
1746                         n->next = diffp;
1747                         diffp = n;
1748                 } else
1749                         blame_origin_decref(e->suspect);
1750                 /* Pass blame for everything before the differing
1751                  * chunk to the parent */
1752                 e->suspect = blame_origin_incref(parent);
1753                 e->s_lno += offset;
1754                 e->next = samep;
1755                 samep = e;
1756                 e = next;
1757         }
1758         /*
1759          * As we don't know how much of a common stretch after this
1760          * diff will occur, the currently blamed parts are all that we
1761          * can assign to the parent for now.
1762          */
1763
1764         if (samep) {
1765                 **dstq = reverse_blame(samep, **dstq);
1766                 *dstq = &samep->next;
1767         }
1768         /*
1769          * Prepend the split off portions: everything after e starts
1770          * after the blameable portion.
1771          */
1772         e = reverse_blame(diffp, e);
1773
1774         /*
1775          * Now retain records on the target while parts are different
1776          * from the parent.
1777          */
1778         samep = NULL;
1779         diffp = NULL;
1780
1781         if (ignore_diffs && same - tlno > 0) {
1782                 line_blames = xcalloc(sizeof(struct blame_line_tracker),
1783                                       same - tlno);
1784                 guess_line_blames(parent, target, tlno, offset, same,
1785                                   parent_len, line_blames);
1786         }
1787
1788         while (e && e->s_lno < same) {
1789                 struct blame_entry *next = e->next;
1790
1791                 /*
1792                  * If current record extends into sameness, need to split.
1793                  */
1794                 if (e->s_lno + e->num_lines > same) {
1795                         /*
1796                          * Move second half to a new record to be
1797                          * processed by later chunks
1798                          */
1799                         struct blame_entry *n;
1800
1801                         n = split_blame_at(e, same - e->s_lno,
1802                                            blame_origin_incref(e->suspect));
1803                         /* Push new record to samep */
1804                         n->next = samep;
1805                         samep = n;
1806                 }
1807                 if (ignore_diffs) {
1808                         ignore_blame_entry(e, parent, &diffp, &ignoredp,
1809                                            line_blames + e->s_lno - tlno);
1810                 } else {
1811                         e->next = diffp;
1812                         diffp = e;
1813                 }
1814                 e = next;
1815         }
1816         free(line_blames);
1817         if (ignoredp) {
1818                 /*
1819                  * Note ignoredp is not sorted yet, and thus neither is dstq.
1820                  * That list must be sorted before we queue_blames().  We defer
1821                  * sorting until after all diff hunks are processed, so that
1822                  * guess_line_blames() can pick *any* line in the parent.  The
1823                  * slight drawback is that we end up sorting all blame entries
1824                  * passed to the parent, including those that are unrelated to
1825                  * changes made by the ignored commit.
1826                  */
1827                 **dstq = reverse_blame(ignoredp, **dstq);
1828                 *dstq = &ignoredp->next;
1829         }
1830         **srcq = reverse_blame(diffp, reverse_blame(samep, e));
1831         /* Move across elements that are in the unblamable portion */
1832         if (diffp)
1833                 *srcq = &diffp->next;
1834 }
1835
1836 struct blame_chunk_cb_data {
1837         struct blame_origin *parent;
1838         struct blame_origin *target;
1839         long offset;
1840         int ignore_diffs;
1841         struct blame_entry **dstq;
1842         struct blame_entry **srcq;
1843 };
1844
1845 /* diff chunks are from parent to target */
1846 static int blame_chunk_cb(long start_a, long count_a,
1847                           long start_b, long count_b, void *data)
1848 {
1849         struct blame_chunk_cb_data *d = data;
1850         if (start_a - start_b != d->offset)
1851                 die("internal error in blame::blame_chunk_cb");
1852         blame_chunk(&d->dstq, &d->srcq, start_b, start_a - start_b,
1853                     start_b + count_b, count_a, d->parent, d->target,
1854                     d->ignore_diffs);
1855         d->offset = start_a + count_a - (start_b + count_b);
1856         return 0;
1857 }
1858
1859 /*
1860  * We are looking at the origin 'target' and aiming to pass blame
1861  * for the lines it is suspected to its parent.  Run diff to find
1862  * which lines came from parent and pass blame for them.
1863  */
1864 static void pass_blame_to_parent(struct blame_scoreboard *sb,
1865                                  struct blame_origin *target,
1866                                  struct blame_origin *parent, int ignore_diffs)
1867 {
1868         mmfile_t file_p, file_o;
1869         struct blame_chunk_cb_data d;
1870         struct blame_entry *newdest = NULL;
1871
1872         if (!target->suspects)
1873                 return; /* nothing remains for this target */
1874
1875         d.parent = parent;
1876         d.target = target;
1877         d.offset = 0;
1878         d.ignore_diffs = ignore_diffs;
1879         d.dstq = &newdest; d.srcq = &target->suspects;
1880
1881         fill_origin_blob(&sb->revs->diffopt, parent, &file_p,
1882                          &sb->num_read_blob, ignore_diffs);
1883         fill_origin_blob(&sb->revs->diffopt, target, &file_o,
1884                          &sb->num_read_blob, ignore_diffs);
1885         sb->num_get_patch++;
1886
1887         if (diff_hunks(&file_p, &file_o, blame_chunk_cb, &d, sb->xdl_opts))
1888                 die("unable to generate diff (%s -> %s)",
1889                     oid_to_hex(&parent->commit->object.oid),
1890                     oid_to_hex(&target->commit->object.oid));
1891         /* The rest are the same as the parent */
1892         blame_chunk(&d.dstq, &d.srcq, INT_MAX, d.offset, INT_MAX, 0,
1893                     parent, target, 0);
1894         *d.dstq = NULL;
1895         if (ignore_diffs)
1896                 newdest = llist_mergesort(newdest, get_next_blame,
1897                                           set_next_blame,
1898                                           compare_blame_suspect);
1899         queue_blames(sb, parent, newdest);
1900
1901         return;
1902 }
1903
1904 /*
1905  * The lines in blame_entry after splitting blames many times can become
1906  * very small and trivial, and at some point it becomes pointless to
1907  * blame the parents.  E.g. "\t\t}\n\t}\n\n" appears everywhere in any
1908  * ordinary C program, and it is not worth to say it was copied from
1909  * totally unrelated file in the parent.
1910  *
1911  * Compute how trivial the lines in the blame_entry are.
1912  */
1913 unsigned blame_entry_score(struct blame_scoreboard *sb, struct blame_entry *e)
1914 {
1915         unsigned score;
1916         const char *cp, *ep;
1917
1918         if (e->score)
1919                 return e->score;
1920
1921         score = 1;
1922         cp = blame_nth_line(sb, e->lno);
1923         ep = blame_nth_line(sb, e->lno + e->num_lines);
1924         while (cp < ep) {
1925                 unsigned ch = *((unsigned char *)cp);
1926                 if (isalnum(ch))
1927                         score++;
1928                 cp++;
1929         }
1930         e->score = score;
1931         return score;
1932 }
1933
1934 /*
1935  * best_so_far[] and potential[] are both a split of an existing blame_entry
1936  * that passes blame to the parent.  Maintain best_so_far the best split so
1937  * far, by comparing potential and best_so_far and copying potential into
1938  * bst_so_far as needed.
1939  */
1940 static void copy_split_if_better(struct blame_scoreboard *sb,
1941                                  struct blame_entry *best_so_far,
1942                                  struct blame_entry *potential)
1943 {
1944         int i;
1945
1946         if (!potential[1].suspect)
1947                 return;
1948         if (best_so_far[1].suspect) {
1949                 if (blame_entry_score(sb, &potential[1]) <
1950                     blame_entry_score(sb, &best_so_far[1]))
1951                         return;
1952         }
1953
1954         for (i = 0; i < 3; i++)
1955                 blame_origin_incref(potential[i].suspect);
1956         decref_split(best_so_far);
1957         memcpy(best_so_far, potential, sizeof(struct blame_entry[3]));
1958 }
1959
1960 /*
1961  * We are looking at a part of the final image represented by
1962  * ent (tlno and same are offset by ent->s_lno).
1963  * tlno is where we are looking at in the final image.
1964  * up to (but not including) same match preimage.
1965  * plno is where we are looking at in the preimage.
1966  *
1967  * <-------------- final image ---------------------->
1968  *       <------ent------>
1969  *         ^tlno ^same
1970  *    <---------preimage----->
1971  *         ^plno
1972  *
1973  * All line numbers are 0-based.
1974  */
1975 static void handle_split(struct blame_scoreboard *sb,
1976                          struct blame_entry *ent,
1977                          int tlno, int plno, int same,
1978                          struct blame_origin *parent,
1979                          struct blame_entry *split)
1980 {
1981         if (ent->num_lines <= tlno)
1982                 return;
1983         if (tlno < same) {
1984                 struct blame_entry potential[3];
1985                 tlno += ent->s_lno;
1986                 same += ent->s_lno;
1987                 split_overlap(potential, ent, tlno, plno, same, parent);
1988                 copy_split_if_better(sb, split, potential);
1989                 decref_split(potential);
1990         }
1991 }
1992
1993 struct handle_split_cb_data {
1994         struct blame_scoreboard *sb;
1995         struct blame_entry *ent;
1996         struct blame_origin *parent;
1997         struct blame_entry *split;
1998         long plno;
1999         long tlno;
2000 };
2001
2002 static int handle_split_cb(long start_a, long count_a,
2003                            long start_b, long count_b, void *data)
2004 {
2005         struct handle_split_cb_data *d = data;
2006         handle_split(d->sb, d->ent, d->tlno, d->plno, start_b, d->parent,
2007                      d->split);
2008         d->plno = start_a + count_a;
2009         d->tlno = start_b + count_b;
2010         return 0;
2011 }
2012
2013 /*
2014  * Find the lines from parent that are the same as ent so that
2015  * we can pass blames to it.  file_p has the blob contents for
2016  * the parent.
2017  */
2018 static void find_copy_in_blob(struct blame_scoreboard *sb,
2019                               struct blame_entry *ent,
2020                               struct blame_origin *parent,
2021                               struct blame_entry *split,
2022                               mmfile_t *file_p)
2023 {
2024         const char *cp;
2025         mmfile_t file_o;
2026         struct handle_split_cb_data d;
2027
2028         memset(&d, 0, sizeof(d));
2029         d.sb = sb; d.ent = ent; d.parent = parent; d.split = split;
2030         /*
2031          * Prepare mmfile that contains only the lines in ent.
2032          */
2033         cp = blame_nth_line(sb, ent->lno);
2034         file_o.ptr = (char *) cp;
2035         file_o.size = blame_nth_line(sb, ent->lno + ent->num_lines) - cp;
2036
2037         /*
2038          * file_o is a part of final image we are annotating.
2039          * file_p partially may match that image.
2040          */
2041         memset(split, 0, sizeof(struct blame_entry [3]));
2042         if (diff_hunks(file_p, &file_o, handle_split_cb, &d, sb->xdl_opts))
2043                 die("unable to generate diff (%s)",
2044                     oid_to_hex(&parent->commit->object.oid));
2045         /* remainder, if any, all match the preimage */
2046         handle_split(sb, ent, d.tlno, d.plno, ent->num_lines, parent, split);
2047 }
2048
2049 /* Move all blame entries from list *source that have a score smaller
2050  * than score_min to the front of list *small.
2051  * Returns a pointer to the link pointing to the old head of the small list.
2052  */
2053
2054 static struct blame_entry **filter_small(struct blame_scoreboard *sb,
2055                                          struct blame_entry **small,
2056                                          struct blame_entry **source,
2057                                          unsigned score_min)
2058 {
2059         struct blame_entry *p = *source;
2060         struct blame_entry *oldsmall = *small;
2061         while (p) {
2062                 if (blame_entry_score(sb, p) <= score_min) {
2063                         *small = p;
2064                         small = &p->next;
2065                         p = *small;
2066                 } else {
2067                         *source = p;
2068                         source = &p->next;
2069                         p = *source;
2070                 }
2071         }
2072         *small = oldsmall;
2073         *source = NULL;
2074         return small;
2075 }
2076
2077 /*
2078  * See if lines currently target is suspected for can be attributed to
2079  * parent.
2080  */
2081 static void find_move_in_parent(struct blame_scoreboard *sb,
2082                                 struct blame_entry ***blamed,
2083                                 struct blame_entry **toosmall,
2084                                 struct blame_origin *target,
2085                                 struct blame_origin *parent)
2086 {
2087         struct blame_entry *e, split[3];
2088         struct blame_entry *unblamed = target->suspects;
2089         struct blame_entry *leftover = NULL;
2090         mmfile_t file_p;
2091
2092         if (!unblamed)
2093                 return; /* nothing remains for this target */
2094
2095         fill_origin_blob(&sb->revs->diffopt, parent, &file_p,
2096                          &sb->num_read_blob, 0);
2097         if (!file_p.ptr)
2098                 return;
2099
2100         /* At each iteration, unblamed has a NULL-terminated list of
2101          * entries that have not yet been tested for blame.  leftover
2102          * contains the reversed list of entries that have been tested
2103          * without being assignable to the parent.
2104          */
2105         do {
2106                 struct blame_entry **unblamedtail = &unblamed;
2107                 struct blame_entry *next;
2108                 for (e = unblamed; e; e = next) {
2109                         next = e->next;
2110                         find_copy_in_blob(sb, e, parent, split, &file_p);
2111                         if (split[1].suspect &&
2112                             sb->move_score < blame_entry_score(sb, &split[1])) {
2113                                 split_blame(blamed, &unblamedtail, split, e);
2114                         } else {
2115                                 e->next = leftover;
2116                                 leftover = e;
2117                         }
2118                         decref_split(split);
2119                 }
2120                 *unblamedtail = NULL;
2121                 toosmall = filter_small(sb, toosmall, &unblamed, sb->move_score);
2122         } while (unblamed);
2123         target->suspects = reverse_blame(leftover, NULL);
2124 }
2125
2126 struct blame_list {
2127         struct blame_entry *ent;
2128         struct blame_entry split[3];
2129 };
2130
2131 /*
2132  * Count the number of entries the target is suspected for,
2133  * and prepare a list of entry and the best split.
2134  */
2135 static struct blame_list *setup_blame_list(struct blame_entry *unblamed,
2136                                            int *num_ents_p)
2137 {
2138         struct blame_entry *e;
2139         int num_ents, i;
2140         struct blame_list *blame_list = NULL;
2141
2142         for (e = unblamed, num_ents = 0; e; e = e->next)
2143                 num_ents++;
2144         if (num_ents) {
2145                 blame_list = xcalloc(num_ents, sizeof(struct blame_list));
2146                 for (e = unblamed, i = 0; e; e = e->next)
2147                         blame_list[i++].ent = e;
2148         }
2149         *num_ents_p = num_ents;
2150         return blame_list;
2151 }
2152
2153 /*
2154  * For lines target is suspected for, see if we can find code movement
2155  * across file boundary from the parent commit.  porigin is the path
2156  * in the parent we already tried.
2157  */
2158 static void find_copy_in_parent(struct blame_scoreboard *sb,
2159                                 struct blame_entry ***blamed,
2160                                 struct blame_entry **toosmall,
2161                                 struct blame_origin *target,
2162                                 struct commit *parent,
2163                                 struct blame_origin *porigin,
2164                                 int opt)
2165 {
2166         struct diff_options diff_opts;
2167         int i, j;
2168         struct blame_list *blame_list;
2169         int num_ents;
2170         struct blame_entry *unblamed = target->suspects;
2171         struct blame_entry *leftover = NULL;
2172
2173         if (!unblamed)
2174                 return; /* nothing remains for this target */
2175
2176         repo_diff_setup(sb->repo, &diff_opts);
2177         diff_opts.flags.recursive = 1;
2178         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
2179
2180         diff_setup_done(&diff_opts);
2181
2182         /* Try "find copies harder" on new path if requested;
2183          * we do not want to use diffcore_rename() actually to
2184          * match things up; find_copies_harder is set only to
2185          * force diff_tree_oid() to feed all filepairs to diff_queue,
2186          * and this code needs to be after diff_setup_done(), which
2187          * usually makes find-copies-harder imply copy detection.
2188          */
2189         if ((opt & PICKAXE_BLAME_COPY_HARDEST)
2190             || ((opt & PICKAXE_BLAME_COPY_HARDER)
2191                 && (!porigin || strcmp(target->path, porigin->path))))
2192                 diff_opts.flags.find_copies_harder = 1;
2193
2194         if (is_null_oid(&target->commit->object.oid))
2195                 do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
2196         else
2197                 diff_tree_oid(get_commit_tree_oid(parent),
2198                               get_commit_tree_oid(target->commit),
2199                               "", &diff_opts);
2200
2201         if (!diff_opts.flags.find_copies_harder)
2202                 diffcore_std(&diff_opts);
2203
2204         do {
2205                 struct blame_entry **unblamedtail = &unblamed;
2206                 blame_list = setup_blame_list(unblamed, &num_ents);
2207
2208                 for (i = 0; i < diff_queued_diff.nr; i++) {
2209                         struct diff_filepair *p = diff_queued_diff.queue[i];
2210                         struct blame_origin *norigin;
2211                         mmfile_t file_p;
2212                         struct blame_entry potential[3];
2213
2214                         if (!DIFF_FILE_VALID(p->one))
2215                                 continue; /* does not exist in parent */
2216                         if (S_ISGITLINK(p->one->mode))
2217                                 continue; /* ignore git links */
2218                         if (porigin && !strcmp(p->one->path, porigin->path))
2219                                 /* find_move already dealt with this path */
2220                                 continue;
2221
2222                         norigin = get_origin(parent, p->one->path);
2223                         oidcpy(&norigin->blob_oid, &p->one->oid);
2224                         norigin->mode = p->one->mode;
2225                         fill_origin_blob(&sb->revs->diffopt, norigin, &file_p,
2226                                          &sb->num_read_blob, 0);
2227                         if (!file_p.ptr)
2228                                 continue;
2229
2230                         for (j = 0; j < num_ents; j++) {
2231                                 find_copy_in_blob(sb, blame_list[j].ent,
2232                                                   norigin, potential, &file_p);
2233                                 copy_split_if_better(sb, blame_list[j].split,
2234                                                      potential);
2235                                 decref_split(potential);
2236                         }
2237                         blame_origin_decref(norigin);
2238                 }
2239
2240                 for (j = 0; j < num_ents; j++) {
2241                         struct blame_entry *split = blame_list[j].split;
2242                         if (split[1].suspect &&
2243                             sb->copy_score < blame_entry_score(sb, &split[1])) {
2244                                 split_blame(blamed, &unblamedtail, split,
2245                                             blame_list[j].ent);
2246                         } else {
2247                                 blame_list[j].ent->next = leftover;
2248                                 leftover = blame_list[j].ent;
2249                         }
2250                         decref_split(split);
2251                 }
2252                 free(blame_list);
2253                 *unblamedtail = NULL;
2254                 toosmall = filter_small(sb, toosmall, &unblamed, sb->copy_score);
2255         } while (unblamed);
2256         target->suspects = reverse_blame(leftover, NULL);
2257         diff_flush(&diff_opts);
2258         clear_pathspec(&diff_opts.pathspec);
2259 }
2260
2261 /*
2262  * The blobs of origin and porigin exactly match, so everything
2263  * origin is suspected for can be blamed on the parent.
2264  */
2265 static void pass_whole_blame(struct blame_scoreboard *sb,
2266                              struct blame_origin *origin, struct blame_origin *porigin)
2267 {
2268         struct blame_entry *e, *suspects;
2269
2270         if (!porigin->file.ptr && origin->file.ptr) {
2271                 /* Steal its file */
2272                 porigin->file = origin->file;
2273                 origin->file.ptr = NULL;
2274         }
2275         suspects = origin->suspects;
2276         origin->suspects = NULL;
2277         for (e = suspects; e; e = e->next) {
2278                 blame_origin_incref(porigin);
2279                 blame_origin_decref(e->suspect);
2280                 e->suspect = porigin;
2281         }
2282         queue_blames(sb, porigin, suspects);
2283 }
2284
2285 /*
2286  * We pass blame from the current commit to its parents.  We keep saying
2287  * "parent" (and "porigin"), but what we mean is to find scapegoat to
2288  * exonerate ourselves.
2289  */
2290 static struct commit_list *first_scapegoat(struct rev_info *revs, struct commit *commit,
2291                                         int reverse)
2292 {
2293         if (!reverse) {
2294                 if (revs->first_parent_only &&
2295                     commit->parents &&
2296                     commit->parents->next) {
2297                         free_commit_list(commit->parents->next);
2298                         commit->parents->next = NULL;
2299                 }
2300                 return commit->parents;
2301         }
2302         return lookup_decoration(&revs->children, &commit->object);
2303 }
2304
2305 static int num_scapegoats(struct rev_info *revs, struct commit *commit, int reverse)
2306 {
2307         struct commit_list *l = first_scapegoat(revs, commit, reverse);
2308         return commit_list_count(l);
2309 }
2310
2311 /* Distribute collected unsorted blames to the respected sorted lists
2312  * in the various origins.
2313  */
2314 static void distribute_blame(struct blame_scoreboard *sb, struct blame_entry *blamed)
2315 {
2316         blamed = llist_mergesort(blamed, get_next_blame, set_next_blame,
2317                                  compare_blame_suspect);
2318         while (blamed)
2319         {
2320                 struct blame_origin *porigin = blamed->suspect;
2321                 struct blame_entry *suspects = NULL;
2322                 do {
2323                         struct blame_entry *next = blamed->next;
2324                         blamed->next = suspects;
2325                         suspects = blamed;
2326                         blamed = next;
2327                 } while (blamed && blamed->suspect == porigin);
2328                 suspects = reverse_blame(suspects, NULL);
2329                 queue_blames(sb, porigin, suspects);
2330         }
2331 }
2332
2333 #define MAXSG 16
2334
2335 static void pass_blame(struct blame_scoreboard *sb, struct blame_origin *origin, int opt)
2336 {
2337         struct rev_info *revs = sb->revs;
2338         int i, pass, num_sg;
2339         struct commit *commit = origin->commit;
2340         struct commit_list *sg;
2341         struct blame_origin *sg_buf[MAXSG];
2342         struct blame_origin *porigin, **sg_origin = sg_buf;
2343         struct blame_entry *toosmall = NULL;
2344         struct blame_entry *blames, **blametail = &blames;
2345
2346         num_sg = num_scapegoats(revs, commit, sb->reverse);
2347         if (!num_sg)
2348                 goto finish;
2349         else if (num_sg < ARRAY_SIZE(sg_buf))
2350                 memset(sg_buf, 0, sizeof(sg_buf));
2351         else
2352                 sg_origin = xcalloc(num_sg, sizeof(*sg_origin));
2353
2354         /*
2355          * The first pass looks for unrenamed path to optimize for
2356          * common cases, then we look for renames in the second pass.
2357          */
2358         for (pass = 0; pass < 2 - sb->no_whole_file_rename; pass++) {
2359                 struct blame_origin *(*find)(struct repository *, struct commit *, struct blame_origin *);
2360                 find = pass ? find_rename : find_origin;
2361
2362                 for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2363                      i < num_sg && sg;
2364                      sg = sg->next, i++) {
2365                         struct commit *p = sg->item;
2366                         int j, same;
2367
2368                         if (sg_origin[i])
2369                                 continue;
2370                         if (parse_commit(p))
2371                                 continue;
2372                         porigin = find(sb->repo, p, origin);
2373                         if (!porigin)
2374                                 continue;
2375                         if (oideq(&porigin->blob_oid, &origin->blob_oid)) {
2376                                 pass_whole_blame(sb, origin, porigin);
2377                                 blame_origin_decref(porigin);
2378                                 goto finish;
2379                         }
2380                         for (j = same = 0; j < i; j++)
2381                                 if (sg_origin[j] &&
2382                                     oideq(&sg_origin[j]->blob_oid, &porigin->blob_oid)) {
2383                                         same = 1;
2384                                         break;
2385                                 }
2386                         if (!same)
2387                                 sg_origin[i] = porigin;
2388                         else
2389                                 blame_origin_decref(porigin);
2390                 }
2391         }
2392
2393         sb->num_commits++;
2394         for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2395              i < num_sg && sg;
2396              sg = sg->next, i++) {
2397                 struct blame_origin *porigin = sg_origin[i];
2398                 if (!porigin)
2399                         continue;
2400                 if (!origin->previous) {
2401                         blame_origin_incref(porigin);
2402                         origin->previous = porigin;
2403                 }
2404                 pass_blame_to_parent(sb, origin, porigin, 0);
2405                 if (!origin->suspects)
2406                         goto finish;
2407         }
2408
2409         /*
2410          * Pass remaining suspects for ignored commits to their parents.
2411          */
2412         if (oidset_contains(&sb->ignore_list, &commit->object.oid)) {
2413                 for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2414                      i < num_sg && sg;
2415                      sg = sg->next, i++) {
2416                         struct blame_origin *porigin = sg_origin[i];
2417
2418                         if (!porigin)
2419                                 continue;
2420                         pass_blame_to_parent(sb, origin, porigin, 1);
2421                         /*
2422                          * Preemptively drop porigin so we can refresh the
2423                          * fingerprints if we use the parent again, which can
2424                          * occur if you ignore back-to-back commits.
2425                          */
2426                         drop_origin_blob(porigin);
2427                         if (!origin->suspects)
2428                                 goto finish;
2429                 }
2430         }
2431
2432         /*
2433          * Optionally find moves in parents' files.
2434          */
2435         if (opt & PICKAXE_BLAME_MOVE) {
2436                 filter_small(sb, &toosmall, &origin->suspects, sb->move_score);
2437                 if (origin->suspects) {
2438                         for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2439                              i < num_sg && sg;
2440                              sg = sg->next, i++) {
2441                                 struct blame_origin *porigin = sg_origin[i];
2442                                 if (!porigin)
2443                                         continue;
2444                                 find_move_in_parent(sb, &blametail, &toosmall, origin, porigin);
2445                                 if (!origin->suspects)
2446                                         break;
2447                         }
2448                 }
2449         }
2450
2451         /*
2452          * Optionally find copies from parents' files.
2453          */
2454         if (opt & PICKAXE_BLAME_COPY) {
2455                 if (sb->copy_score > sb->move_score)
2456                         filter_small(sb, &toosmall, &origin->suspects, sb->copy_score);
2457                 else if (sb->copy_score < sb->move_score) {
2458                         origin->suspects = blame_merge(origin->suspects, toosmall);
2459                         toosmall = NULL;
2460                         filter_small(sb, &toosmall, &origin->suspects, sb->copy_score);
2461                 }
2462                 if (!origin->suspects)
2463                         goto finish;
2464
2465                 for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse);
2466                      i < num_sg && sg;
2467                      sg = sg->next, i++) {
2468                         struct blame_origin *porigin = sg_origin[i];
2469                         find_copy_in_parent(sb, &blametail, &toosmall,
2470                                             origin, sg->item, porigin, opt);
2471                         if (!origin->suspects)
2472                                 goto finish;
2473                 }
2474         }
2475
2476 finish:
2477         *blametail = NULL;
2478         distribute_blame(sb, blames);
2479         /*
2480          * prepend toosmall to origin->suspects
2481          *
2482          * There is no point in sorting: this ends up on a big
2483          * unsorted list in the caller anyway.
2484          */
2485         if (toosmall) {
2486                 struct blame_entry **tail = &toosmall;
2487                 while (*tail)
2488                         tail = &(*tail)->next;
2489                 *tail = origin->suspects;
2490                 origin->suspects = toosmall;
2491         }
2492         for (i = 0; i < num_sg; i++) {
2493                 if (sg_origin[i]) {
2494                         if (!sg_origin[i]->suspects)
2495                                 drop_origin_blob(sg_origin[i]);
2496                         blame_origin_decref(sg_origin[i]);
2497                 }
2498         }
2499         drop_origin_blob(origin);
2500         if (sg_buf != sg_origin)
2501                 free(sg_origin);
2502 }
2503
2504 /*
2505  * The main loop -- while we have blobs with lines whose true origin
2506  * is still unknown, pick one blob, and allow its lines to pass blames
2507  * to its parents. */
2508 void assign_blame(struct blame_scoreboard *sb, int opt)
2509 {
2510         struct rev_info *revs = sb->revs;
2511         struct commit *commit = prio_queue_get(&sb->commits);
2512
2513         while (commit) {
2514                 struct blame_entry *ent;
2515                 struct blame_origin *suspect = get_blame_suspects(commit);
2516
2517                 /* find one suspect to break down */
2518                 while (suspect && !suspect->suspects)
2519                         suspect = suspect->next;
2520
2521                 if (!suspect) {
2522                         commit = prio_queue_get(&sb->commits);
2523                         continue;
2524                 }
2525
2526                 assert(commit == suspect->commit);
2527
2528                 /*
2529                  * We will use this suspect later in the loop,
2530                  * so hold onto it in the meantime.
2531                  */
2532                 blame_origin_incref(suspect);
2533                 parse_commit(commit);
2534                 if (sb->reverse ||
2535                     (!(commit->object.flags & UNINTERESTING) &&
2536                      !(revs->max_age != -1 && commit->date < revs->max_age)))
2537                         pass_blame(sb, suspect, opt);
2538                 else {
2539                         commit->object.flags |= UNINTERESTING;
2540                         if (commit->object.parsed)
2541                                 mark_parents_uninteresting(commit);
2542                 }
2543                 /* treat root commit as boundary */
2544                 if (!commit->parents && !sb->show_root)
2545                         commit->object.flags |= UNINTERESTING;
2546
2547                 /* Take responsibility for the remaining entries */
2548                 ent = suspect->suspects;
2549                 if (ent) {
2550                         suspect->guilty = 1;
2551                         for (;;) {
2552                                 struct blame_entry *next = ent->next;
2553                                 if (sb->found_guilty_entry)
2554                                         sb->found_guilty_entry(ent, sb->found_guilty_entry_data);
2555                                 if (next) {
2556                                         ent = next;
2557                                         continue;
2558                                 }
2559                                 ent->next = sb->ent;
2560                                 sb->ent = suspect->suspects;
2561                                 suspect->suspects = NULL;
2562                                 break;
2563                         }
2564                 }
2565                 blame_origin_decref(suspect);
2566
2567                 if (sb->debug) /* sanity */
2568                         sanity_check_refcnt(sb);
2569         }
2570 }
2571
2572 /*
2573  * To allow quick access to the contents of nth line in the
2574  * final image, prepare an index in the scoreboard.
2575  */
2576 static int prepare_lines(struct blame_scoreboard *sb)
2577 {
2578         sb->num_lines = find_line_starts(&sb->lineno, sb->final_buf,
2579                                          sb->final_buf_size);
2580         return sb->num_lines;
2581 }
2582
2583 static struct commit *find_single_final(struct rev_info *revs,
2584                                         const char **name_p)
2585 {
2586         int i;
2587         struct commit *found = NULL;
2588         const char *name = NULL;
2589
2590         for (i = 0; i < revs->pending.nr; i++) {
2591                 struct object *obj = revs->pending.objects[i].item;
2592                 if (obj->flags & UNINTERESTING)
2593                         continue;
2594                 obj = deref_tag(revs->repo, obj, NULL, 0);
2595                 if (obj->type != OBJ_COMMIT)
2596                         die("Non commit %s?", revs->pending.objects[i].name);
2597                 if (found)
2598                         die("More than one commit to dig from %s and %s?",
2599                             revs->pending.objects[i].name, name);
2600                 found = (struct commit *)obj;
2601                 name = revs->pending.objects[i].name;
2602         }
2603         if (name_p)
2604                 *name_p = xstrdup_or_null(name);
2605         return found;
2606 }
2607
2608 static struct commit *dwim_reverse_initial(struct rev_info *revs,
2609                                            const char **name_p)
2610 {
2611         /*
2612          * DWIM "git blame --reverse ONE -- PATH" as
2613          * "git blame --reverse ONE..HEAD -- PATH" but only do so
2614          * when it makes sense.
2615          */
2616         struct object *obj;
2617         struct commit *head_commit;
2618         struct object_id head_oid;
2619
2620         if (revs->pending.nr != 1)
2621                 return NULL;
2622
2623         /* Is that sole rev a committish? */
2624         obj = revs->pending.objects[0].item;
2625         obj = deref_tag(revs->repo, obj, NULL, 0);
2626         if (obj->type != OBJ_COMMIT)
2627                 return NULL;
2628
2629         /* Do we have HEAD? */
2630         if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL))
2631                 return NULL;
2632         head_commit = lookup_commit_reference_gently(revs->repo,
2633                                                      &head_oid, 1);
2634         if (!head_commit)
2635                 return NULL;
2636
2637         /* Turn "ONE" into "ONE..HEAD" then */
2638         obj->flags |= UNINTERESTING;
2639         add_pending_object(revs, &head_commit->object, "HEAD");
2640
2641         if (name_p)
2642                 *name_p = revs->pending.objects[0].name;
2643         return (struct commit *)obj;
2644 }
2645
2646 static struct commit *find_single_initial(struct rev_info *revs,
2647                                           const char **name_p)
2648 {
2649         int i;
2650         struct commit *found = NULL;
2651         const char *name = NULL;
2652
2653         /*
2654          * There must be one and only one negative commit, and it must be
2655          * the boundary.
2656          */
2657         for (i = 0; i < revs->pending.nr; i++) {
2658                 struct object *obj = revs->pending.objects[i].item;
2659                 if (!(obj->flags & UNINTERESTING))
2660                         continue;
2661                 obj = deref_tag(revs->repo, obj, NULL, 0);
2662                 if (obj->type != OBJ_COMMIT)
2663                         die("Non commit %s?", revs->pending.objects[i].name);
2664                 if (found)
2665                         die("More than one commit to dig up from, %s and %s?",
2666                             revs->pending.objects[i].name, name);
2667                 found = (struct commit *) obj;
2668                 name = revs->pending.objects[i].name;
2669         }
2670
2671         if (!name)
2672                 found = dwim_reverse_initial(revs, &name);
2673         if (!name)
2674                 die("No commit to dig up from?");
2675
2676         if (name_p)
2677                 *name_p = xstrdup(name);
2678         return found;
2679 }
2680
2681 void init_scoreboard(struct blame_scoreboard *sb)
2682 {
2683         memset(sb, 0, sizeof(struct blame_scoreboard));
2684         sb->move_score = BLAME_DEFAULT_MOVE_SCORE;
2685         sb->copy_score = BLAME_DEFAULT_COPY_SCORE;
2686 }
2687
2688 void setup_scoreboard(struct blame_scoreboard *sb,
2689                       const char *path,
2690                       struct blame_origin **orig)
2691 {
2692         const char *final_commit_name = NULL;
2693         struct blame_origin *o;
2694         struct commit *final_commit = NULL;
2695         enum object_type type;
2696
2697         init_blame_suspects(&blame_suspects);
2698
2699         if (sb->reverse && sb->contents_from)
2700                 die(_("--contents and --reverse do not blend well."));
2701
2702         if (!sb->repo)
2703                 BUG("repo is NULL");
2704
2705         if (!sb->reverse) {
2706                 sb->final = find_single_final(sb->revs, &final_commit_name);
2707                 sb->commits.compare = compare_commits_by_commit_date;
2708         } else {
2709                 sb->final = find_single_initial(sb->revs, &final_commit_name);
2710                 sb->commits.compare = compare_commits_by_reverse_commit_date;
2711         }
2712
2713         if (sb->final && sb->contents_from)
2714                 die(_("cannot use --contents with final commit object name"));
2715
2716         if (sb->reverse && sb->revs->first_parent_only)
2717                 sb->revs->children.name = NULL;
2718
2719         if (!sb->final) {
2720                 /*
2721                  * "--not A B -- path" without anything positive;
2722                  * do not default to HEAD, but use the working tree
2723                  * or "--contents".
2724                  */
2725                 setup_work_tree();
2726                 sb->final = fake_working_tree_commit(sb->repo,
2727                                                      &sb->revs->diffopt,
2728                                                      path, sb->contents_from);
2729                 add_pending_object(sb->revs, &(sb->final->object), ":");
2730         }
2731
2732         if (sb->reverse && sb->revs->first_parent_only) {
2733                 final_commit = find_single_final(sb->revs, NULL);
2734                 if (!final_commit)
2735                         die(_("--reverse and --first-parent together require specified latest commit"));
2736         }
2737
2738         /*
2739          * If we have bottom, this will mark the ancestors of the
2740          * bottom commits we would reach while traversing as
2741          * uninteresting.
2742          */
2743         if (prepare_revision_walk(sb->revs))
2744                 die(_("revision walk setup failed"));
2745
2746         if (sb->reverse && sb->revs->first_parent_only) {
2747                 struct commit *c = final_commit;
2748
2749                 sb->revs->children.name = "children";
2750                 while (c->parents &&
2751                        !oideq(&c->object.oid, &sb->final->object.oid)) {
2752                         struct commit_list *l = xcalloc(1, sizeof(*l));
2753
2754                         l->item = c;
2755                         if (add_decoration(&sb->revs->children,
2756                                            &c->parents->item->object, l))
2757                                 BUG("not unique item in first-parent chain");
2758                         c = c->parents->item;
2759                 }
2760
2761                 if (!oideq(&c->object.oid, &sb->final->object.oid))
2762                         die(_("--reverse --first-parent together require range along first-parent chain"));
2763         }
2764
2765         if (is_null_oid(&sb->final->object.oid)) {
2766                 o = get_blame_suspects(sb->final);
2767                 sb->final_buf = xmemdupz(o->file.ptr, o->file.size);
2768                 sb->final_buf_size = o->file.size;
2769         }
2770         else {
2771                 o = get_origin(sb->final, path);
2772                 if (fill_blob_sha1_and_mode(sb->repo, o))
2773                         die(_("no such path %s in %s"), path, final_commit_name);
2774
2775                 if (sb->revs->diffopt.flags.allow_textconv &&
2776                     textconv_object(sb->repo, path, o->mode, &o->blob_oid, 1, (char **) &sb->final_buf,
2777                                     &sb->final_buf_size))
2778                         ;
2779                 else
2780                         sb->final_buf = read_object_file(&o->blob_oid, &type,
2781                                                          &sb->final_buf_size);
2782
2783                 if (!sb->final_buf)
2784                         die(_("cannot read blob %s for path %s"),
2785                             oid_to_hex(&o->blob_oid),
2786                             path);
2787         }
2788         sb->num_read_blob++;
2789         prepare_lines(sb);
2790
2791         if (orig)
2792                 *orig = o;
2793
2794         free((char *)final_commit_name);
2795 }
2796
2797
2798
2799 struct blame_entry *blame_entry_prepend(struct blame_entry *head,
2800                                         long start, long end,
2801                                         struct blame_origin *o)
2802 {
2803         struct blame_entry *new_head = xcalloc(1, sizeof(struct blame_entry));
2804         new_head->lno = start;
2805         new_head->num_lines = end - start;
2806         new_head->suspect = o;
2807         new_head->s_lno = start;
2808         new_head->next = head;
2809         blame_origin_incref(o);
2810         return new_head;
2811 }