Merge branch 'lr/doc-fix-cet'
[git] / diffcore-rename.c
1 /*
2  * Copyright (C) 2005 Junio C Hamano
3  */
4 #include "cache.h"
5 #include "diff.h"
6 #include "diffcore.h"
7 #include "hashmap.h"
8 #include "progress.h"
9
10 /* Table of rename/copy destinations */
11
12 static struct diff_rename_dst {
13         struct diff_filespec *two;
14         struct diff_filepair *pair;
15 } *rename_dst;
16 static int rename_dst_nr, rename_dst_alloc;
17
18 static int find_rename_dst(struct diff_filespec *two)
19 {
20         int first, last;
21
22         first = 0;
23         last = rename_dst_nr;
24         while (last > first) {
25                 int next = (last + first) >> 1;
26                 struct diff_rename_dst *dst = &(rename_dst[next]);
27                 int cmp = strcmp(two->path, dst->two->path);
28                 if (!cmp)
29                         return next;
30                 if (cmp < 0) {
31                         last = next;
32                         continue;
33                 }
34                 first = next+1;
35         }
36         return -first - 1;
37 }
38
39 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two)
40 {
41         int ofs = find_rename_dst(two);
42         return ofs < 0 ? NULL : &rename_dst[ofs];
43 }
44
45 /*
46  * Returns 0 on success, -1 if we found a duplicate.
47  */
48 static int add_rename_dst(struct diff_filespec *two)
49 {
50         int first = find_rename_dst(two);
51
52         if (first >= 0)
53                 return -1;
54         first = -first - 1;
55
56         /* insert to make it at "first" */
57         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
58         rename_dst_nr++;
59         if (first < rename_dst_nr)
60                 memmove(rename_dst + first + 1, rename_dst + first,
61                         (rename_dst_nr - first - 1) * sizeof(*rename_dst));
62         rename_dst[first].two = alloc_filespec(two->path);
63         fill_filespec(rename_dst[first].two, two->oid.hash, two->oid_valid,
64                       two->mode);
65         rename_dst[first].pair = NULL;
66         return 0;
67 }
68
69 /* Table of rename/copy src files */
70 static struct diff_rename_src {
71         struct diff_filepair *p;
72         unsigned short score; /* to remember the break score */
73 } *rename_src;
74 static int rename_src_nr, rename_src_alloc;
75
76 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
77 {
78         int first, last;
79         struct diff_filespec *one = p->one;
80         unsigned short score = p->score;
81
82         first = 0;
83         last = rename_src_nr;
84         while (last > first) {
85                 int next = (last + first) >> 1;
86                 struct diff_rename_src *src = &(rename_src[next]);
87                 int cmp = strcmp(one->path, src->p->one->path);
88                 if (!cmp)
89                         return src;
90                 if (cmp < 0) {
91                         last = next;
92                         continue;
93                 }
94                 first = next+1;
95         }
96
97         /* insert to make it at "first" */
98         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
99         rename_src_nr++;
100         if (first < rename_src_nr)
101                 memmove(rename_src + first + 1, rename_src + first,
102                         (rename_src_nr - first - 1) * sizeof(*rename_src));
103         rename_src[first].p = p;
104         rename_src[first].score = score;
105         return &(rename_src[first]);
106 }
107
108 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
109 {
110         int src_len = strlen(src->path), dst_len = strlen(dst->path);
111         while (src_len && dst_len) {
112                 char c1 = src->path[--src_len];
113                 char c2 = dst->path[--dst_len];
114                 if (c1 != c2)
115                         return 0;
116                 if (c1 == '/')
117                         return 1;
118         }
119         return (!src_len || src->path[src_len - 1] == '/') &&
120                 (!dst_len || dst->path[dst_len - 1] == '/');
121 }
122
123 struct diff_score {
124         int src; /* index in rename_src */
125         int dst; /* index in rename_dst */
126         unsigned short score;
127         short name_score;
128 };
129
130 static int estimate_similarity(struct diff_filespec *src,
131                                struct diff_filespec *dst,
132                                int minimum_score)
133 {
134         /* src points at a file that existed in the original tree (or
135          * optionally a file in the destination tree) and dst points
136          * at a newly created file.  They may be quite similar, in which
137          * case we want to say src is renamed to dst or src is copied into
138          * dst, and then some edit has been applied to dst.
139          *
140          * Compare them and return how similar they are, representing
141          * the score as an integer between 0 and MAX_SCORE.
142          *
143          * When there is an exact match, it is considered a better
144          * match than anything else; the destination does not even
145          * call into this function in that case.
146          */
147         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
148         int score;
149
150         /* We deal only with regular files.  Symlink renames are handled
151          * only when they are exact matches --- in other words, no edits
152          * after renaming.
153          */
154         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
155                 return 0;
156
157         /*
158          * Need to check that source and destination sizes are
159          * filled in before comparing them.
160          *
161          * If we already have "cnt_data" filled in, we know it's
162          * all good (avoid checking the size for zero, as that
163          * is a possible size - we really should have a flag to
164          * say whether the size is valid or not!)
165          */
166         if (!src->cnt_data &&
167             diff_populate_filespec(src, CHECK_SIZE_ONLY))
168                 return 0;
169         if (!dst->cnt_data &&
170             diff_populate_filespec(dst, CHECK_SIZE_ONLY))
171                 return 0;
172
173         max_size = ((src->size > dst->size) ? src->size : dst->size);
174         base_size = ((src->size < dst->size) ? src->size : dst->size);
175         delta_size = max_size - base_size;
176
177         /* We would not consider edits that change the file size so
178          * drastically.  delta_size must be smaller than
179          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
180          *
181          * Note that base_size == 0 case is handled here already
182          * and the final score computation below would not have a
183          * divide-by-zero issue.
184          */
185         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
186                 return 0;
187
188         if (!src->cnt_data && diff_populate_filespec(src, 0))
189                 return 0;
190         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
191                 return 0;
192
193         if (diffcore_count_changes(src, dst,
194                                    &src->cnt_data, &dst->cnt_data,
195                                    &src_copied, &literal_added))
196                 return 0;
197
198         /* How similar are they?
199          * what percentage of material in dst are from source?
200          */
201         if (!dst->size)
202                 score = 0; /* should not happen */
203         else
204                 score = (int)(src_copied * MAX_SCORE / max_size);
205         return score;
206 }
207
208 static void record_rename_pair(int dst_index, int src_index, int score)
209 {
210         struct diff_filespec *src, *dst;
211         struct diff_filepair *dp;
212
213         if (rename_dst[dst_index].pair)
214                 die("internal error: dst already matched.");
215
216         src = rename_src[src_index].p->one;
217         src->rename_used++;
218         src->count++;
219
220         dst = rename_dst[dst_index].two;
221         dst->count++;
222
223         dp = diff_queue(NULL, src, dst);
224         dp->renamed_pair = 1;
225         if (!strcmp(src->path, dst->path))
226                 dp->score = rename_src[src_index].score;
227         else
228                 dp->score = score;
229         rename_dst[dst_index].pair = dp;
230 }
231
232 /*
233  * We sort the rename similarity matrix with the score, in descending
234  * order (the most similar first).
235  */
236 static int score_compare(const void *a_, const void *b_)
237 {
238         const struct diff_score *a = a_, *b = b_;
239
240         /* sink the unused ones to the bottom */
241         if (a->dst < 0)
242                 return (0 <= b->dst);
243         else if (b->dst < 0)
244                 return -1;
245
246         if (a->score == b->score)
247                 return b->name_score - a->name_score;
248
249         return b->score - a->score;
250 }
251
252 struct file_similarity {
253         struct hashmap_entry entry;
254         int index;
255         struct diff_filespec *filespec;
256 };
257
258 static unsigned int hash_filespec(struct diff_filespec *filespec)
259 {
260         if (!filespec->oid_valid) {
261                 if (diff_populate_filespec(filespec, 0))
262                         return 0;
263                 hash_sha1_file(filespec->data, filespec->size, "blob",
264                                filespec->oid.hash);
265         }
266         return sha1hash(filespec->oid.hash);
267 }
268
269 static int find_identical_files(struct hashmap *srcs,
270                                 int dst_index,
271                                 struct diff_options *options)
272 {
273         int renames = 0;
274
275         struct diff_filespec *target = rename_dst[dst_index].two;
276         struct file_similarity *p, *best = NULL;
277         int i = 100, best_score = -1;
278
279         /*
280          * Find the best source match for specified destination.
281          */
282         p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
283         for (; p; p = hashmap_get_next(srcs, p)) {
284                 int score;
285                 struct diff_filespec *source = p->filespec;
286
287                 /* False hash collision? */
288                 if (oidcmp(&source->oid, &target->oid))
289                         continue;
290                 /* Non-regular files? If so, the modes must match! */
291                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
292                         if (source->mode != target->mode)
293                                 continue;
294                 }
295                 /* Give higher scores to sources that haven't been used already */
296                 score = !source->rename_used;
297                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
298                         continue;
299                 score += basename_same(source, target);
300                 if (score > best_score) {
301                         best = p;
302                         best_score = score;
303                         if (score == 2)
304                                 break;
305                 }
306
307                 /* Too many identical alternatives? Pick one */
308                 if (!--i)
309                         break;
310         }
311         if (best) {
312                 record_rename_pair(dst_index, best->index, MAX_SCORE);
313                 renames++;
314         }
315         return renames;
316 }
317
318 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
319 {
320         struct file_similarity *entry = xmalloc(sizeof(*entry));
321
322         entry->index = index;
323         entry->filespec = filespec;
324
325         hashmap_entry_init(entry, hash_filespec(filespec));
326         hashmap_add(table, entry);
327 }
328
329 /*
330  * Find exact renames first.
331  *
332  * The first round matches up the up-to-date entries,
333  * and then during the second round we try to match
334  * cache-dirty entries as well.
335  */
336 static int find_exact_renames(struct diff_options *options)
337 {
338         int i, renames = 0;
339         struct hashmap file_table;
340
341         /* Add all sources to the hash table in reverse order, because
342          * later on they will be retrieved in LIFO order.
343          */
344         hashmap_init(&file_table, NULL, rename_src_nr);
345         for (i = rename_src_nr-1; i >= 0; i--)
346                 insert_file_table(&file_table, i, rename_src[i].p->one);
347
348         /* Walk the destinations and find best source match */
349         for (i = 0; i < rename_dst_nr; i++)
350                 renames += find_identical_files(&file_table, i, options);
351
352         /* Free the hash data structure and entries */
353         hashmap_free(&file_table, 1);
354
355         return renames;
356 }
357
358 #define NUM_CANDIDATE_PER_DST 4
359 static void record_if_better(struct diff_score m[], struct diff_score *o)
360 {
361         int i, worst;
362
363         /* find the worst one */
364         worst = 0;
365         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
366                 if (score_compare(&m[i], &m[worst]) > 0)
367                         worst = i;
368
369         /* is it better than the worst one? */
370         if (score_compare(&m[worst], o) > 0)
371                 m[worst] = *o;
372 }
373
374 /*
375  * Returns:
376  * 0 if we are under the limit;
377  * 1 if we need to disable inexact rename detection;
378  * 2 if we would be under the limit if we were given -C instead of -C -C.
379  */
380 static int too_many_rename_candidates(int num_create,
381                                       struct diff_options *options)
382 {
383         int rename_limit = options->rename_limit;
384         int num_src = rename_src_nr;
385         int i;
386
387         options->needed_rename_limit = 0;
388
389         /*
390          * This basically does a test for the rename matrix not
391          * growing larger than a "rename_limit" square matrix, ie:
392          *
393          *    num_create * num_src > rename_limit * rename_limit
394          *
395          * but handles the potential overflow case specially (and we
396          * assume at least 32-bit integers)
397          */
398         if (rename_limit <= 0 || rename_limit > 32767)
399                 rename_limit = 32767;
400         if ((num_create <= rename_limit || num_src <= rename_limit) &&
401             (num_create * num_src <= rename_limit * rename_limit))
402                 return 0;
403
404         options->needed_rename_limit =
405                 num_src > num_create ? num_src : num_create;
406
407         /* Are we running under -C -C? */
408         if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
409                 return 1;
410
411         /* Would we bust the limit if we were running under -C? */
412         for (num_src = i = 0; i < rename_src_nr; i++) {
413                 if (diff_unmodified_pair(rename_src[i].p))
414                         continue;
415                 num_src++;
416         }
417         if ((num_create <= rename_limit || num_src <= rename_limit) &&
418             (num_create * num_src <= rename_limit * rename_limit))
419                 return 2;
420         return 1;
421 }
422
423 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
424 {
425         int count = 0, i;
426
427         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
428                 struct diff_rename_dst *dst;
429
430                 if ((mx[i].dst < 0) ||
431                     (mx[i].score < minimum_score))
432                         break; /* there is no more usable pair. */
433                 dst = &rename_dst[mx[i].dst];
434                 if (dst->pair)
435                         continue; /* already done, either exact or fuzzy. */
436                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
437                         continue;
438                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
439                 count++;
440         }
441         return count;
442 }
443
444 void diffcore_rename(struct diff_options *options)
445 {
446         int detect_rename = options->detect_rename;
447         int minimum_score = options->rename_score;
448         struct diff_queue_struct *q = &diff_queued_diff;
449         struct diff_queue_struct outq;
450         struct diff_score *mx;
451         int i, j, rename_count, skip_unmodified = 0;
452         int num_create, dst_cnt;
453         struct progress *progress = NULL;
454
455         if (!minimum_score)
456                 minimum_score = DEFAULT_RENAME_SCORE;
457
458         for (i = 0; i < q->nr; i++) {
459                 struct diff_filepair *p = q->queue[i];
460                 if (!DIFF_FILE_VALID(p->one)) {
461                         if (!DIFF_FILE_VALID(p->two))
462                                 continue; /* unmerged */
463                         else if (options->single_follow &&
464                                  strcmp(options->single_follow, p->two->path))
465                                 continue; /* not interested */
466                         else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
467                                  is_empty_blob_sha1(p->two->oid.hash))
468                                 continue;
469                         else if (add_rename_dst(p->two) < 0) {
470                                 warning("skipping rename detection, detected"
471                                         " duplicate destination '%s'",
472                                         p->two->path);
473                                 goto cleanup;
474                         }
475                 }
476                 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
477                          is_empty_blob_sha1(p->one->oid.hash))
478                         continue;
479                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
480                         /*
481                          * If the source is a broken "delete", and
482                          * they did not really want to get broken,
483                          * that means the source actually stays.
484                          * So we increment the "rename_used" score
485                          * by one, to indicate ourselves as a user
486                          */
487                         if (p->broken_pair && !p->score)
488                                 p->one->rename_used++;
489                         register_rename_src(p);
490                 }
491                 else if (detect_rename == DIFF_DETECT_COPY) {
492                         /*
493                          * Increment the "rename_used" score by
494                          * one, to indicate ourselves as a user.
495                          */
496                         p->one->rename_used++;
497                         register_rename_src(p);
498                 }
499         }
500         if (rename_dst_nr == 0 || rename_src_nr == 0)
501                 goto cleanup; /* nothing to do */
502
503         /*
504          * We really want to cull the candidates list early
505          * with cheap tests in order to avoid doing deltas.
506          */
507         rename_count = find_exact_renames(options);
508
509         /* Did we only want exact renames? */
510         if (minimum_score == MAX_SCORE)
511                 goto cleanup;
512
513         /*
514          * Calculate how many renames are left (but all the source
515          * files still remain as options for rename/copies!)
516          */
517         num_create = (rename_dst_nr - rename_count);
518
519         /* All done? */
520         if (!num_create)
521                 goto cleanup;
522
523         switch (too_many_rename_candidates(num_create, options)) {
524         case 1:
525                 goto cleanup;
526         case 2:
527                 options->degraded_cc_to_c = 1;
528                 skip_unmodified = 1;
529                 break;
530         default:
531                 break;
532         }
533
534         if (options->show_rename_progress) {
535                 progress = start_progress_delay(
536                                 _("Performing inexact rename detection"),
537                                 rename_dst_nr * rename_src_nr, 50, 1);
538         }
539
540         mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
541         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
542                 struct diff_filespec *two = rename_dst[i].two;
543                 struct diff_score *m;
544
545                 if (rename_dst[i].pair)
546                         continue; /* dealt with exact match already. */
547
548                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
549                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
550                         m[j].dst = -1;
551
552                 for (j = 0; j < rename_src_nr; j++) {
553                         struct diff_filespec *one = rename_src[j].p->one;
554                         struct diff_score this_src;
555
556                         if (skip_unmodified &&
557                             diff_unmodified_pair(rename_src[j].p))
558                                 continue;
559
560                         this_src.score = estimate_similarity(one, two,
561                                                              minimum_score);
562                         this_src.name_score = basename_same(one, two);
563                         this_src.dst = i;
564                         this_src.src = j;
565                         record_if_better(m, &this_src);
566                         /*
567                          * Once we run estimate_similarity,
568                          * We do not need the text anymore.
569                          */
570                         diff_free_filespec_blob(one);
571                         diff_free_filespec_blob(two);
572                 }
573                 dst_cnt++;
574                 display_progress(progress, (i+1)*rename_src_nr);
575         }
576         stop_progress(&progress);
577
578         /* cost matrix sorted by most to least similar pair */
579         QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
580
581         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
582         if (detect_rename == DIFF_DETECT_COPY)
583                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
584         free(mx);
585
586  cleanup:
587         /* At this point, we have found some renames and copies and they
588          * are recorded in rename_dst.  The original list is still in *q.
589          */
590         DIFF_QUEUE_CLEAR(&outq);
591         for (i = 0; i < q->nr; i++) {
592                 struct diff_filepair *p = q->queue[i];
593                 struct diff_filepair *pair_to_free = NULL;
594
595                 if (DIFF_PAIR_UNMERGED(p)) {
596                         diff_q(&outq, p);
597                 }
598                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
599                         /*
600                          * Creation
601                          *
602                          * We would output this create record if it has
603                          * not been turned into a rename/copy already.
604                          */
605                         struct diff_rename_dst *dst = locate_rename_dst(p->two);
606                         if (dst && dst->pair) {
607                                 diff_q(&outq, dst->pair);
608                                 pair_to_free = p;
609                         }
610                         else
611                                 /* no matching rename/copy source, so
612                                  * record this as a creation.
613                                  */
614                                 diff_q(&outq, p);
615                 }
616                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
617                         /*
618                          * Deletion
619                          *
620                          * We would output this delete record if:
621                          *
622                          * (1) this is a broken delete and the counterpart
623                          *     broken create remains in the output; or
624                          * (2) this is not a broken delete, and rename_dst
625                          *     does not have a rename/copy to move p->one->path
626                          *     out of existence.
627                          *
628                          * Otherwise, the counterpart broken create
629                          * has been turned into a rename-edit; or
630                          * delete did not have a matching create to
631                          * begin with.
632                          */
633                         if (DIFF_PAIR_BROKEN(p)) {
634                                 /* broken delete */
635                                 struct diff_rename_dst *dst = locate_rename_dst(p->one);
636                                 if (dst && dst->pair)
637                                         /* counterpart is now rename/copy */
638                                         pair_to_free = p;
639                         }
640                         else {
641                                 if (p->one->rename_used)
642                                         /* this path remains */
643                                         pair_to_free = p;
644                         }
645
646                         if (pair_to_free)
647                                 ;
648                         else
649                                 diff_q(&outq, p);
650                 }
651                 else if (!diff_unmodified_pair(p))
652                         /* all the usual ones need to be kept */
653                         diff_q(&outq, p);
654                 else
655                         /* no need to keep unmodified pairs */
656                         pair_to_free = p;
657
658                 if (pair_to_free)
659                         diff_free_filepair(pair_to_free);
660         }
661         diff_debug_queue("done copying original", &outq);
662
663         free(q->queue);
664         *q = outq;
665         diff_debug_queue("done collapsing", q);
666
667         for (i = 0; i < rename_dst_nr; i++)
668                 free_filespec(rename_dst[i].two);
669
670         free(rename_dst);
671         rename_dst = NULL;
672         rename_dst_nr = rename_dst_alloc = 0;
673         free(rename_src);
674         rename_src = NULL;
675         rename_src_nr = rename_src_alloc = 0;
676         return;
677 }