Merge branch 'jn/gitweb-grep'
[git/git.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 "hash.h"
8
9 /* Table of rename/copy destinations */
10
11 static struct diff_rename_dst {
12 struct diff_filespec *two;
13 struct diff_filepair *pair;
14 } *rename_dst;
15 static int rename_dst_nr, rename_dst_alloc;
16
17 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
18 int insert_ok)
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 dst;
30 if (cmp < 0) {
31 last = next;
32 continue;
33 }
34 first = next+1;
35 }
36 /* not found */
37 if (!insert_ok)
38 return NULL;
39 /* insert to make it at "first" */
40 if (rename_dst_alloc <= rename_dst_nr) {
41 rename_dst_alloc = alloc_nr(rename_dst_alloc);
42 rename_dst = xrealloc(rename_dst,
43 rename_dst_alloc * sizeof(*rename_dst));
44 }
45 rename_dst_nr++;
46 if (first < rename_dst_nr)
47 memmove(rename_dst + first + 1, rename_dst + first,
48 (rename_dst_nr - first - 1) * sizeof(*rename_dst));
49 rename_dst[first].two = alloc_filespec(two->path);
50 fill_filespec(rename_dst[first].two, two->sha1, two->mode);
51 rename_dst[first].pair = NULL;
52 return &(rename_dst[first]);
53 }
54
55 /* Table of rename/copy src files */
56 static struct diff_rename_src {
57 struct diff_filespec *one;
58 unsigned short score; /* to remember the break score */
59 } *rename_src;
60 static int rename_src_nr, rename_src_alloc;
61
62 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
63 unsigned short score)
64 {
65 int first, last;
66
67 first = 0;
68 last = rename_src_nr;
69 while (last > first) {
70 int next = (last + first) >> 1;
71 struct diff_rename_src *src = &(rename_src[next]);
72 int cmp = strcmp(one->path, src->one->path);
73 if (!cmp)
74 return src;
75 if (cmp < 0) {
76 last = next;
77 continue;
78 }
79 first = next+1;
80 }
81
82 /* insert to make it at "first" */
83 if (rename_src_alloc <= rename_src_nr) {
84 rename_src_alloc = alloc_nr(rename_src_alloc);
85 rename_src = xrealloc(rename_src,
86 rename_src_alloc * sizeof(*rename_src));
87 }
88 rename_src_nr++;
89 if (first < rename_src_nr)
90 memmove(rename_src + first + 1, rename_src + first,
91 (rename_src_nr - first - 1) * sizeof(*rename_src));
92 rename_src[first].one = one;
93 rename_src[first].score = score;
94 return &(rename_src[first]);
95 }
96
97 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
98 {
99 int src_len = strlen(src->path), dst_len = strlen(dst->path);
100 while (src_len && dst_len) {
101 char c1 = src->path[--src_len];
102 char c2 = dst->path[--dst_len];
103 if (c1 != c2)
104 return 0;
105 if (c1 == '/')
106 return 1;
107 }
108 return (!src_len || src->path[src_len - 1] == '/') &&
109 (!dst_len || dst->path[dst_len - 1] == '/');
110 }
111
112 struct diff_score {
113 int src; /* index in rename_src */
114 int dst; /* index in rename_dst */
115 int score;
116 int name_score;
117 };
118
119 static int estimate_similarity(struct diff_filespec *src,
120 struct diff_filespec *dst,
121 int minimum_score)
122 {
123 /* src points at a file that existed in the original tree (or
124 * optionally a file in the destination tree) and dst points
125 * at a newly created file. They may be quite similar, in which
126 * case we want to say src is renamed to dst or src is copied into
127 * dst, and then some edit has been applied to dst.
128 *
129 * Compare them and return how similar they are, representing
130 * the score as an integer between 0 and MAX_SCORE.
131 *
132 * When there is an exact match, it is considered a better
133 * match than anything else; the destination does not even
134 * call into this function in that case.
135 */
136 unsigned long max_size, delta_size, base_size, src_copied, literal_added;
137 unsigned long delta_limit;
138 int score;
139
140 /* We deal only with regular files. Symlink renames are handled
141 * only when they are exact matches --- in other words, no edits
142 * after renaming.
143 */
144 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
145 return 0;
146
147 /*
148 * Need to check that source and destination sizes are
149 * filled in before comparing them.
150 *
151 * If we already have "cnt_data" filled in, we know it's
152 * all good (avoid checking the size for zero, as that
153 * is a possible size - we really should have a flag to
154 * say whether the size is valid or not!)
155 */
156 if (!src->cnt_data && diff_populate_filespec(src, 0))
157 return 0;
158 if (!dst->cnt_data && diff_populate_filespec(dst, 0))
159 return 0;
160
161 max_size = ((src->size > dst->size) ? src->size : dst->size);
162 base_size = ((src->size < dst->size) ? src->size : dst->size);
163 delta_size = max_size - base_size;
164
165 /* We would not consider edits that change the file size so
166 * drastically. delta_size must be smaller than
167 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
168 *
169 * Note that base_size == 0 case is handled here already
170 * and the final score computation below would not have a
171 * divide-by-zero issue.
172 */
173 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
174 return 0;
175
176 delta_limit = (unsigned long)
177 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
178 if (diffcore_count_changes(src, dst,
179 &src->cnt_data, &dst->cnt_data,
180 delta_limit,
181 &src_copied, &literal_added))
182 return 0;
183
184 /* How similar are they?
185 * what percentage of material in dst are from source?
186 */
187 if (!dst->size)
188 score = 0; /* should not happen */
189 else
190 score = (int)(src_copied * MAX_SCORE / max_size);
191 return score;
192 }
193
194 static void record_rename_pair(int dst_index, int src_index, int score)
195 {
196 struct diff_filespec *src, *dst;
197 struct diff_filepair *dp;
198
199 if (rename_dst[dst_index].pair)
200 die("internal error: dst already matched.");
201
202 src = rename_src[src_index].one;
203 src->rename_used++;
204 src->count++;
205
206 dst = rename_dst[dst_index].two;
207 dst->count++;
208
209 dp = diff_queue(NULL, src, dst);
210 dp->renamed_pair = 1;
211 if (!strcmp(src->path, dst->path))
212 dp->score = rename_src[src_index].score;
213 else
214 dp->score = score;
215 rename_dst[dst_index].pair = dp;
216 }
217
218 /*
219 * We sort the rename similarity matrix with the score, in descending
220 * order (the most similar first).
221 */
222 static int score_compare(const void *a_, const void *b_)
223 {
224 const struct diff_score *a = a_, *b = b_;
225
226 if (a->score == b->score)
227 return b->name_score - a->name_score;
228
229 return b->score - a->score;
230 }
231
232 struct file_similarity {
233 int src_dst, index;
234 struct diff_filespec *filespec;
235 struct file_similarity *next;
236 };
237
238 static int find_identical_files(struct file_similarity *src,
239 struct file_similarity *dst)
240 {
241 int renames = 0;
242
243 /*
244 * Walk over all the destinations ...
245 */
246 do {
247 struct diff_filespec *target = dst->filespec;
248 struct file_similarity *p, *best;
249 int i = 100, best_score = -1;
250
251 /*
252 * .. to find the best source match
253 */
254 best = NULL;
255 for (p = src; p; p = p->next) {
256 int score;
257 struct diff_filespec *source = p->filespec;
258
259 /* False hash collission? */
260 if (hashcmp(source->sha1, target->sha1))
261 continue;
262 /* Non-regular files? If so, the modes must match! */
263 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
264 if (source->mode != target->mode)
265 continue;
266 }
267 /* Give higher scores to sources that haven't been used already */
268 score = !source->rename_used;
269 score += basename_same(source, target);
270 if (score > best_score) {
271 best = p;
272 best_score = score;
273 if (score == 2)
274 break;
275 }
276
277 /* Too many identical alternatives? Pick one */
278 if (!--i)
279 break;
280 }
281 if (best) {
282 record_rename_pair(dst->index, best->index, MAX_SCORE);
283 renames++;
284 }
285 } while ((dst = dst->next) != NULL);
286 return renames;
287 }
288
289 static void free_similarity_list(struct file_similarity *p)
290 {
291 while (p) {
292 struct file_similarity *entry = p;
293 p = p->next;
294 free(entry);
295 }
296 }
297
298 static int find_same_files(void *ptr)
299 {
300 int ret;
301 struct file_similarity *p = ptr;
302 struct file_similarity *src = NULL, *dst = NULL;
303
304 /* Split the hash list up into sources and destinations */
305 do {
306 struct file_similarity *entry = p;
307 p = p->next;
308 if (entry->src_dst < 0) {
309 entry->next = src;
310 src = entry;
311 } else {
312 entry->next = dst;
313 dst = entry;
314 }
315 } while (p);
316
317 /*
318 * If we have both sources *and* destinations, see if
319 * we can match them up
320 */
321 ret = (src && dst) ? find_identical_files(src, dst) : 0;
322
323 /* Free the hashes and return the number of renames found */
324 free_similarity_list(src);
325 free_similarity_list(dst);
326 return ret;
327 }
328
329 static unsigned int hash_filespec(struct diff_filespec *filespec)
330 {
331 unsigned int hash;
332 if (!filespec->sha1_valid) {
333 if (diff_populate_filespec(filespec, 0))
334 return 0;
335 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
336 }
337 memcpy(&hash, filespec->sha1, sizeof(hash));
338 return hash;
339 }
340
341 static void insert_file_table(struct hash_table *table, int src_dst, int index, struct diff_filespec *filespec)
342 {
343 void **pos;
344 unsigned int hash;
345 struct file_similarity *entry = xmalloc(sizeof(*entry));
346
347 entry->src_dst = src_dst;
348 entry->index = index;
349 entry->filespec = filespec;
350 entry->next = NULL;
351
352 hash = hash_filespec(filespec);
353 pos = insert_hash(hash, entry, table);
354
355 /* We already had an entry there? */
356 if (pos) {
357 entry->next = *pos;
358 *pos = entry;
359 }
360 }
361
362 /*
363 * Find exact renames first.
364 *
365 * The first round matches up the up-to-date entries,
366 * and then during the second round we try to match
367 * cache-dirty entries as well.
368 */
369 static int find_exact_renames(void)
370 {
371 int i;
372 struct hash_table file_table;
373
374 init_hash(&file_table);
375 for (i = 0; i < rename_src_nr; i++)
376 insert_file_table(&file_table, -1, i, rename_src[i].one);
377
378 for (i = 0; i < rename_dst_nr; i++)
379 insert_file_table(&file_table, 1, i, rename_dst[i].two);
380
381 /* Find the renames */
382 i = for_each_hash(&file_table, find_same_files);
383
384 /* .. and free the hash data structure */
385 free_hash(&file_table);
386
387 return i;
388 }
389
390 void diffcore_rename(struct diff_options *options)
391 {
392 int detect_rename = options->detect_rename;
393 int minimum_score = options->rename_score;
394 int rename_limit = options->rename_limit;
395 struct diff_queue_struct *q = &diff_queued_diff;
396 struct diff_queue_struct outq;
397 struct diff_score *mx;
398 int i, j, rename_count;
399 int num_create, num_src, dst_cnt;
400
401 if (!minimum_score)
402 minimum_score = DEFAULT_RENAME_SCORE;
403
404 for (i = 0; i < q->nr; i++) {
405 struct diff_filepair *p = q->queue[i];
406 if (!DIFF_FILE_VALID(p->one)) {
407 if (!DIFF_FILE_VALID(p->two))
408 continue; /* unmerged */
409 else if (options->single_follow &&
410 strcmp(options->single_follow, p->two->path))
411 continue; /* not interested */
412 else
413 locate_rename_dst(p->two, 1);
414 }
415 else if (!DIFF_FILE_VALID(p->two)) {
416 /*
417 * If the source is a broken "delete", and
418 * they did not really want to get broken,
419 * that means the source actually stays.
420 * So we increment the "rename_used" score
421 * by one, to indicate ourselves as a user
422 */
423 if (p->broken_pair && !p->score)
424 p->one->rename_used++;
425 register_rename_src(p->one, p->score);
426 }
427 else if (detect_rename == DIFF_DETECT_COPY) {
428 /*
429 * Increment the "rename_used" score by
430 * one, to indicate ourselves as a user.
431 */
432 p->one->rename_used++;
433 register_rename_src(p->one, p->score);
434 }
435 }
436 if (rename_dst_nr == 0 || rename_src_nr == 0)
437 goto cleanup; /* nothing to do */
438
439 /*
440 * We really want to cull the candidates list early
441 * with cheap tests in order to avoid doing deltas.
442 */
443 rename_count = find_exact_renames();
444
445 /* Did we only want exact renames? */
446 if (minimum_score == MAX_SCORE)
447 goto cleanup;
448
449 /*
450 * Calculate how many renames are left (but all the source
451 * files still remain as options for rename/copies!)
452 */
453 num_create = (rename_dst_nr - rename_count);
454 num_src = rename_src_nr;
455
456 /* All done? */
457 if (!num_create)
458 goto cleanup;
459
460 /*
461 * This basically does a test for the rename matrix not
462 * growing larger than a "rename_limit" square matrix, ie:
463 *
464 * num_create * num_src > rename_limit * rename_limit
465 *
466 * but handles the potential overflow case specially (and we
467 * assume at least 32-bit integers)
468 */
469 if (rename_limit <= 0 || rename_limit > 32767)
470 rename_limit = 32767;
471 if ((num_create > rename_limit && num_src > rename_limit) ||
472 (num_create * num_src > rename_limit * rename_limit)) {
473 warning("too many files, skipping inexact rename detection");
474 goto cleanup;
475 }
476
477 mx = xmalloc(sizeof(*mx) * num_create * num_src);
478 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
479 int base = dst_cnt * num_src;
480 struct diff_filespec *two = rename_dst[i].two;
481 if (rename_dst[i].pair)
482 continue; /* dealt with exact match already. */
483 for (j = 0; j < rename_src_nr; j++) {
484 struct diff_filespec *one = rename_src[j].one;
485 struct diff_score *m = &mx[base+j];
486 m->src = j;
487 m->dst = i;
488 m->score = estimate_similarity(one, two,
489 minimum_score);
490 m->name_score = basename_same(one, two);
491 diff_free_filespec_blob(one);
492 }
493 /* We do not need the text anymore */
494 diff_free_filespec_blob(two);
495 dst_cnt++;
496 }
497 /* cost matrix sorted by most to least similar pair */
498 qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
499 for (i = 0; i < num_create * num_src; i++) {
500 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
501 struct diff_filespec *src;
502 if (dst->pair)
503 continue; /* already done, either exact or fuzzy. */
504 if (mx[i].score < minimum_score)
505 break; /* there is no more usable pair. */
506 src = rename_src[mx[i].src].one;
507 if (src->rename_used)
508 continue;
509 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
510 rename_count++;
511 }
512 for (i = 0; i < num_create * num_src; i++) {
513 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
514 if (dst->pair)
515 continue; /* already done, either exact or fuzzy. */
516 if (mx[i].score < minimum_score)
517 break; /* there is no more usable pair. */
518 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
519 rename_count++;
520 }
521 free(mx);
522
523 cleanup:
524 /* At this point, we have found some renames and copies and they
525 * are recorded in rename_dst. The original list is still in *q.
526 */
527 outq.queue = NULL;
528 outq.nr = outq.alloc = 0;
529 for (i = 0; i < q->nr; i++) {
530 struct diff_filepair *p = q->queue[i];
531 struct diff_filepair *pair_to_free = NULL;
532
533 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
534 /*
535 * Creation
536 *
537 * We would output this create record if it has
538 * not been turned into a rename/copy already.
539 */
540 struct diff_rename_dst *dst =
541 locate_rename_dst(p->two, 0);
542 if (dst && dst->pair) {
543 diff_q(&outq, dst->pair);
544 pair_to_free = p;
545 }
546 else
547 /* no matching rename/copy source, so
548 * record this as a creation.
549 */
550 diff_q(&outq, p);
551 }
552 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
553 /*
554 * Deletion
555 *
556 * We would output this delete record if:
557 *
558 * (1) this is a broken delete and the counterpart
559 * broken create remains in the output; or
560 * (2) this is not a broken delete, and rename_dst
561 * does not have a rename/copy to move p->one->path
562 * out of existence.
563 *
564 * Otherwise, the counterpart broken create
565 * has been turned into a rename-edit; or
566 * delete did not have a matching create to
567 * begin with.
568 */
569 if (DIFF_PAIR_BROKEN(p)) {
570 /* broken delete */
571 struct diff_rename_dst *dst =
572 locate_rename_dst(p->one, 0);
573 if (dst && dst->pair)
574 /* counterpart is now rename/copy */
575 pair_to_free = p;
576 }
577 else {
578 if (p->one->rename_used)
579 /* this path remains */
580 pair_to_free = p;
581 }
582
583 if (pair_to_free)
584 ;
585 else
586 diff_q(&outq, p);
587 }
588 else if (!diff_unmodified_pair(p))
589 /* all the usual ones need to be kept */
590 diff_q(&outq, p);
591 else
592 /* no need to keep unmodified pairs */
593 pair_to_free = p;
594
595 if (pair_to_free)
596 diff_free_filepair(pair_to_free);
597 }
598 diff_debug_queue("done copying original", &outq);
599
600 free(q->queue);
601 *q = outq;
602 diff_debug_queue("done collapsing", q);
603
604 for (i = 0; i < rename_dst_nr; i++)
605 free_filespec(rename_dst[i].two);
606
607 free(rename_dst);
608 rename_dst = NULL;
609 rename_dst_nr = rename_dst_alloc = 0;
610 free(rename_src);
611 rename_src = NULL;
612 rename_src_nr = rename_src_alloc = 0;
613 return;
614 }