Merge branch 'ep/shell-assign-and-export-vars'
[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 struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
19                                                  int insert_ok)
20 {
21         int first, last;
22
23         first = 0;
24         last = rename_dst_nr;
25         while (last > first) {
26                 int next = (last + first) >> 1;
27                 struct diff_rename_dst *dst = &(rename_dst[next]);
28                 int cmp = strcmp(two->path, dst->two->path);
29                 if (!cmp)
30                         return dst;
31                 if (cmp < 0) {
32                         last = next;
33                         continue;
34                 }
35                 first = next+1;
36         }
37         /* not found */
38         if (!insert_ok)
39                 return NULL;
40         /* insert to make it at "first" */
41         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
42         rename_dst_nr++;
43         if (first < rename_dst_nr)
44                 memmove(rename_dst + first + 1, rename_dst + first,
45                         (rename_dst_nr - first - 1) * sizeof(*rename_dst));
46         rename_dst[first].two = alloc_filespec(two->path);
47         fill_filespec(rename_dst[first].two, two->sha1, two->sha1_valid, two->mode);
48         rename_dst[first].pair = NULL;
49         return &(rename_dst[first]);
50 }
51
52 /* Table of rename/copy src files */
53 static struct diff_rename_src {
54         struct diff_filepair *p;
55         unsigned short score; /* to remember the break score */
56 } *rename_src;
57 static int rename_src_nr, rename_src_alloc;
58
59 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
60 {
61         int first, last;
62         struct diff_filespec *one = p->one;
63         unsigned short score = p->score;
64
65         first = 0;
66         last = rename_src_nr;
67         while (last > first) {
68                 int next = (last + first) >> 1;
69                 struct diff_rename_src *src = &(rename_src[next]);
70                 int cmp = strcmp(one->path, src->p->one->path);
71                 if (!cmp)
72                         return src;
73                 if (cmp < 0) {
74                         last = next;
75                         continue;
76                 }
77                 first = next+1;
78         }
79
80         /* insert to make it at "first" */
81         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
82         rename_src_nr++;
83         if (first < rename_src_nr)
84                 memmove(rename_src + first + 1, rename_src + first,
85                         (rename_src_nr - first - 1) * sizeof(*rename_src));
86         rename_src[first].p = p;
87         rename_src[first].score = score;
88         return &(rename_src[first]);
89 }
90
91 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
92 {
93         int src_len = strlen(src->path), dst_len = strlen(dst->path);
94         while (src_len && dst_len) {
95                 char c1 = src->path[--src_len];
96                 char c2 = dst->path[--dst_len];
97                 if (c1 != c2)
98                         return 0;
99                 if (c1 == '/')
100                         return 1;
101         }
102         return (!src_len || src->path[src_len - 1] == '/') &&
103                 (!dst_len || dst->path[dst_len - 1] == '/');
104 }
105
106 struct diff_score {
107         int src; /* index in rename_src */
108         int dst; /* index in rename_dst */
109         unsigned short score;
110         short name_score;
111 };
112
113 static int estimate_similarity(struct diff_filespec *src,
114                                struct diff_filespec *dst,
115                                int minimum_score)
116 {
117         /* src points at a file that existed in the original tree (or
118          * optionally a file in the destination tree) and dst points
119          * at a newly created file.  They may be quite similar, in which
120          * case we want to say src is renamed to dst or src is copied into
121          * dst, and then some edit has been applied to dst.
122          *
123          * Compare them and return how similar they are, representing
124          * the score as an integer between 0 and MAX_SCORE.
125          *
126          * When there is an exact match, it is considered a better
127          * match than anything else; the destination does not even
128          * call into this function in that case.
129          */
130         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
131         unsigned long delta_limit;
132         int score;
133
134         /* We deal only with regular files.  Symlink renames are handled
135          * only when they are exact matches --- in other words, no edits
136          * after renaming.
137          */
138         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
139                 return 0;
140
141         /*
142          * Need to check that source and destination sizes are
143          * filled in before comparing them.
144          *
145          * If we already have "cnt_data" filled in, we know it's
146          * all good (avoid checking the size for zero, as that
147          * is a possible size - we really should have a flag to
148          * say whether the size is valid or not!)
149          */
150         if (!src->cnt_data && diff_populate_filespec(src, 1))
151                 return 0;
152         if (!dst->cnt_data && diff_populate_filespec(dst, 1))
153                 return 0;
154
155         max_size = ((src->size > dst->size) ? src->size : dst->size);
156         base_size = ((src->size < dst->size) ? src->size : dst->size);
157         delta_size = max_size - base_size;
158
159         /* We would not consider edits that change the file size so
160          * drastically.  delta_size must be smaller than
161          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
162          *
163          * Note that base_size == 0 case is handled here already
164          * and the final score computation below would not have a
165          * divide-by-zero issue.
166          */
167         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
168                 return 0;
169
170         if (!src->cnt_data && diff_populate_filespec(src, 0))
171                 return 0;
172         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
173                 return 0;
174
175         delta_limit = (unsigned long)
176                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
177         if (diffcore_count_changes(src, dst,
178                                    &src->cnt_data, &dst->cnt_data,
179                                    delta_limit,
180                                    &src_copied, &literal_added))
181                 return 0;
182
183         /* How similar are they?
184          * what percentage of material in dst are from source?
185          */
186         if (!dst->size)
187                 score = 0; /* should not happen */
188         else
189                 score = (int)(src_copied * MAX_SCORE / max_size);
190         return score;
191 }
192
193 static void record_rename_pair(int dst_index, int src_index, int score)
194 {
195         struct diff_filespec *src, *dst;
196         struct diff_filepair *dp;
197
198         if (rename_dst[dst_index].pair)
199                 die("internal error: dst already matched.");
200
201         src = rename_src[src_index].p->one;
202         src->rename_used++;
203         src->count++;
204
205         dst = rename_dst[dst_index].two;
206         dst->count++;
207
208         dp = diff_queue(NULL, src, dst);
209         dp->renamed_pair = 1;
210         if (!strcmp(src->path, dst->path))
211                 dp->score = rename_src[src_index].score;
212         else
213                 dp->score = score;
214         rename_dst[dst_index].pair = dp;
215 }
216
217 /*
218  * We sort the rename similarity matrix with the score, in descending
219  * order (the most similar first).
220  */
221 static int score_compare(const void *a_, const void *b_)
222 {
223         const struct diff_score *a = a_, *b = b_;
224
225         /* sink the unused ones to the bottom */
226         if (a->dst < 0)
227                 return (0 <= b->dst);
228         else if (b->dst < 0)
229                 return -1;
230
231         if (a->score == b->score)
232                 return b->name_score - a->name_score;
233
234         return b->score - a->score;
235 }
236
237 struct file_similarity {
238         struct hashmap_entry entry;
239         int index;
240         struct diff_filespec *filespec;
241 };
242
243 static unsigned int hash_filespec(struct diff_filespec *filespec)
244 {
245         unsigned int hash;
246         if (!filespec->sha1_valid) {
247                 if (diff_populate_filespec(filespec, 0))
248                         return 0;
249                 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
250         }
251         memcpy(&hash, filespec->sha1, sizeof(hash));
252         return hash;
253 }
254
255 static int find_identical_files(struct hashmap *srcs,
256                                 int dst_index,
257                                 struct diff_options *options)
258 {
259         int renames = 0;
260
261         struct diff_filespec *target = rename_dst[dst_index].two;
262         struct file_similarity *p, *best, dst;
263         int i = 100, best_score = -1;
264
265         /*
266          * Find the best source match for specified destination.
267          */
268         best = NULL;
269         hashmap_entry_init(&dst, hash_filespec(target));
270         for (p = hashmap_get(srcs, &dst, NULL); p; p = hashmap_get_next(srcs, p)) {
271                 int score;
272                 struct diff_filespec *source = p->filespec;
273
274                 /* False hash collision? */
275                 if (hashcmp(source->sha1, target->sha1))
276                         continue;
277                 /* Non-regular files? If so, the modes must match! */
278                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
279                         if (source->mode != target->mode)
280                                 continue;
281                 }
282                 /* Give higher scores to sources that haven't been used already */
283                 score = !source->rename_used;
284                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
285                         continue;
286                 score += basename_same(source, target);
287                 if (score > best_score) {
288                         best = p;
289                         best_score = score;
290                         if (score == 2)
291                                 break;
292                 }
293
294                 /* Too many identical alternatives? Pick one */
295                 if (!--i)
296                         break;
297         }
298         if (best) {
299                 record_rename_pair(dst_index, best->index, MAX_SCORE);
300                 renames++;
301         }
302         return renames;
303 }
304
305 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
306 {
307         struct file_similarity *entry = xmalloc(sizeof(*entry));
308
309         entry->index = index;
310         entry->filespec = filespec;
311
312         hashmap_entry_init(entry, hash_filespec(filespec));
313         hashmap_add(table, entry);
314 }
315
316 /*
317  * Find exact renames first.
318  *
319  * The first round matches up the up-to-date entries,
320  * and then during the second round we try to match
321  * cache-dirty entries as well.
322  */
323 static int find_exact_renames(struct diff_options *options)
324 {
325         int i, renames = 0;
326         struct hashmap file_table;
327
328         /* Add all sources to the hash table */
329         hashmap_init(&file_table, NULL, rename_src_nr);
330         for (i = 0; i < rename_src_nr; i++)
331                 insert_file_table(&file_table, i, rename_src[i].p->one);
332
333         /* Walk the destinations and find best source match */
334         for (i = 0; i < rename_dst_nr; i++)
335                 renames += find_identical_files(&file_table, i, options);
336
337         /* Free the hash data structure and entries */
338         hashmap_free(&file_table, 1);
339
340         return renames;
341 }
342
343 #define NUM_CANDIDATE_PER_DST 4
344 static void record_if_better(struct diff_score m[], struct diff_score *o)
345 {
346         int i, worst;
347
348         /* find the worst one */
349         worst = 0;
350         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
351                 if (score_compare(&m[i], &m[worst]) > 0)
352                         worst = i;
353
354         /* is it better than the worst one? */
355         if (score_compare(&m[worst], o) > 0)
356                 m[worst] = *o;
357 }
358
359 /*
360  * Returns:
361  * 0 if we are under the limit;
362  * 1 if we need to disable inexact rename detection;
363  * 2 if we would be under the limit if we were given -C instead of -C -C.
364  */
365 static int too_many_rename_candidates(int num_create,
366                                       struct diff_options *options)
367 {
368         int rename_limit = options->rename_limit;
369         int num_src = rename_src_nr;
370         int i;
371
372         options->needed_rename_limit = 0;
373
374         /*
375          * This basically does a test for the rename matrix not
376          * growing larger than a "rename_limit" square matrix, ie:
377          *
378          *    num_create * num_src > rename_limit * rename_limit
379          *
380          * but handles the potential overflow case specially (and we
381          * assume at least 32-bit integers)
382          */
383         if (rename_limit <= 0 || rename_limit > 32767)
384                 rename_limit = 32767;
385         if ((num_create <= rename_limit || num_src <= rename_limit) &&
386             (num_create * num_src <= rename_limit * rename_limit))
387                 return 0;
388
389         options->needed_rename_limit =
390                 num_src > num_create ? num_src : num_create;
391
392         /* Are we running under -C -C? */
393         if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
394                 return 1;
395
396         /* Would we bust the limit if we were running under -C? */
397         for (num_src = i = 0; i < rename_src_nr; i++) {
398                 if (diff_unmodified_pair(rename_src[i].p))
399                         continue;
400                 num_src++;
401         }
402         if ((num_create <= rename_limit || num_src <= rename_limit) &&
403             (num_create * num_src <= rename_limit * rename_limit))
404                 return 2;
405         return 1;
406 }
407
408 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
409 {
410         int count = 0, i;
411
412         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
413                 struct diff_rename_dst *dst;
414
415                 if ((mx[i].dst < 0) ||
416                     (mx[i].score < minimum_score))
417                         break; /* there is no more usable pair. */
418                 dst = &rename_dst[mx[i].dst];
419                 if (dst->pair)
420                         continue; /* already done, either exact or fuzzy. */
421                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
422                         continue;
423                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
424                 count++;
425         }
426         return count;
427 }
428
429 void diffcore_rename(struct diff_options *options)
430 {
431         int detect_rename = options->detect_rename;
432         int minimum_score = options->rename_score;
433         struct diff_queue_struct *q = &diff_queued_diff;
434         struct diff_queue_struct outq;
435         struct diff_score *mx;
436         int i, j, rename_count, skip_unmodified = 0;
437         int num_create, dst_cnt;
438         struct progress *progress = NULL;
439
440         if (!minimum_score)
441                 minimum_score = DEFAULT_RENAME_SCORE;
442
443         for (i = 0; i < q->nr; i++) {
444                 struct diff_filepair *p = q->queue[i];
445                 if (!DIFF_FILE_VALID(p->one)) {
446                         if (!DIFF_FILE_VALID(p->two))
447                                 continue; /* unmerged */
448                         else if (options->single_follow &&
449                                  strcmp(options->single_follow, p->two->path))
450                                 continue; /* not interested */
451                         else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
452                                  is_empty_blob_sha1(p->two->sha1))
453                                 continue;
454                         else
455                                 locate_rename_dst(p->two, 1);
456                 }
457                 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
458                          is_empty_blob_sha1(p->one->sha1))
459                         continue;
460                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
461                         /*
462                          * If the source is a broken "delete", and
463                          * they did not really want to get broken,
464                          * that means the source actually stays.
465                          * So we increment the "rename_used" score
466                          * by one, to indicate ourselves as a user
467                          */
468                         if (p->broken_pair && !p->score)
469                                 p->one->rename_used++;
470                         register_rename_src(p);
471                 }
472                 else if (detect_rename == DIFF_DETECT_COPY) {
473                         /*
474                          * Increment the "rename_used" score by
475                          * one, to indicate ourselves as a user.
476                          */
477                         p->one->rename_used++;
478                         register_rename_src(p);
479                 }
480         }
481         if (rename_dst_nr == 0 || rename_src_nr == 0)
482                 goto cleanup; /* nothing to do */
483
484         /*
485          * We really want to cull the candidates list early
486          * with cheap tests in order to avoid doing deltas.
487          */
488         rename_count = find_exact_renames(options);
489
490         /* Did we only want exact renames? */
491         if (minimum_score == MAX_SCORE)
492                 goto cleanup;
493
494         /*
495          * Calculate how many renames are left (but all the source
496          * files still remain as options for rename/copies!)
497          */
498         num_create = (rename_dst_nr - rename_count);
499
500         /* All done? */
501         if (!num_create)
502                 goto cleanup;
503
504         switch (too_many_rename_candidates(num_create, options)) {
505         case 1:
506                 goto cleanup;
507         case 2:
508                 options->degraded_cc_to_c = 1;
509                 skip_unmodified = 1;
510                 break;
511         default:
512                 break;
513         }
514
515         if (options->show_rename_progress) {
516                 progress = start_progress_delay(
517                                 _("Performing inexact rename detection"),
518                                 rename_dst_nr * rename_src_nr, 50, 1);
519         }
520
521         mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, sizeof(*mx));
522         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
523                 struct diff_filespec *two = rename_dst[i].two;
524                 struct diff_score *m;
525
526                 if (rename_dst[i].pair)
527                         continue; /* dealt with exact match already. */
528
529                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
530                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
531                         m[j].dst = -1;
532
533                 for (j = 0; j < rename_src_nr; j++) {
534                         struct diff_filespec *one = rename_src[j].p->one;
535                         struct diff_score this_src;
536
537                         if (skip_unmodified &&
538                             diff_unmodified_pair(rename_src[j].p))
539                                 continue;
540
541                         this_src.score = estimate_similarity(one, two,
542                                                              minimum_score);
543                         this_src.name_score = basename_same(one, two);
544                         this_src.dst = i;
545                         this_src.src = j;
546                         record_if_better(m, &this_src);
547                         /*
548                          * Once we run estimate_similarity,
549                          * We do not need the text anymore.
550                          */
551                         diff_free_filespec_blob(one);
552                         diff_free_filespec_blob(two);
553                 }
554                 dst_cnt++;
555                 display_progress(progress, (i+1)*rename_src_nr);
556         }
557         stop_progress(&progress);
558
559         /* cost matrix sorted by most to least similar pair */
560         qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
561
562         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
563         if (detect_rename == DIFF_DETECT_COPY)
564                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
565         free(mx);
566
567  cleanup:
568         /* At this point, we have found some renames and copies and they
569          * are recorded in rename_dst.  The original list is still in *q.
570          */
571         DIFF_QUEUE_CLEAR(&outq);
572         for (i = 0; i < q->nr; i++) {
573                 struct diff_filepair *p = q->queue[i];
574                 struct diff_filepair *pair_to_free = NULL;
575
576                 if (DIFF_PAIR_UNMERGED(p)) {
577                         diff_q(&outq, p);
578                 }
579                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
580                         /*
581                          * Creation
582                          *
583                          * We would output this create record if it has
584                          * not been turned into a rename/copy already.
585                          */
586                         struct diff_rename_dst *dst =
587                                 locate_rename_dst(p->two, 0);
588                         if (dst && dst->pair) {
589                                 diff_q(&outq, dst->pair);
590                                 pair_to_free = p;
591                         }
592                         else
593                                 /* no matching rename/copy source, so
594                                  * record this as a creation.
595                                  */
596                                 diff_q(&outq, p);
597                 }
598                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
599                         /*
600                          * Deletion
601                          *
602                          * We would output this delete record if:
603                          *
604                          * (1) this is a broken delete and the counterpart
605                          *     broken create remains in the output; or
606                          * (2) this is not a broken delete, and rename_dst
607                          *     does not have a rename/copy to move p->one->path
608                          *     out of existence.
609                          *
610                          * Otherwise, the counterpart broken create
611                          * has been turned into a rename-edit; or
612                          * delete did not have a matching create to
613                          * begin with.
614                          */
615                         if (DIFF_PAIR_BROKEN(p)) {
616                                 /* broken delete */
617                                 struct diff_rename_dst *dst =
618                                         locate_rename_dst(p->one, 0);
619                                 if (dst && dst->pair)
620                                         /* counterpart is now rename/copy */
621                                         pair_to_free = p;
622                         }
623                         else {
624                                 if (p->one->rename_used)
625                                         /* this path remains */
626                                         pair_to_free = p;
627                         }
628
629                         if (pair_to_free)
630                                 ;
631                         else
632                                 diff_q(&outq, p);
633                 }
634                 else if (!diff_unmodified_pair(p))
635                         /* all the usual ones need to be kept */
636                         diff_q(&outq, p);
637                 else
638                         /* no need to keep unmodified pairs */
639                         pair_to_free = p;
640
641                 if (pair_to_free)
642                         diff_free_filepair(pair_to_free);
643         }
644         diff_debug_queue("done copying original", &outq);
645
646         free(q->queue);
647         *q = outq;
648         diff_debug_queue("done collapsing", q);
649
650         for (i = 0; i < rename_dst_nr; i++)
651                 free_filespec(rename_dst[i].two);
652
653         free(rename_dst);
654         rename_dst = NULL;
655         rename_dst_nr = rename_dst_alloc = 0;
656         free(rename_src);
657         rename_src = NULL;
658         rename_src_nr = rename_src_alloc = 0;
659         return;
660 }