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 11static struct diff_rename_dst { 12 struct diff_filespec *two; 13 struct diff_filepair *pair; 14} *rename_dst; 15static int rename_dst_nr, rename_dst_alloc; 16 17static 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 */ 56static struct diff_rename_src { 57 struct diff_filespec *one; 58 unsigned short score; /* to remember the break score */ 59} *rename_src; 60static int rename_src_nr, rename_src_alloc; 61 62static 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 97static 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 112struct diff_score { 113 int src; /* index in rename_src */ 114 int dst; /* index in rename_dst */ 115 unsigned short score; 116 short name_score; 117}; 118 119static 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, 1)) 157 return 0; 158 if (!dst->cnt_data && diff_populate_filespec(dst, 1)) 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 if (!src->cnt_data && diff_populate_filespec(src, 0)) 177 return 0; 178 if (!dst->cnt_data && diff_populate_filespec(dst, 0)) 179 return 0; 180 181 delta_limit = (unsigned long) 182 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE); 183 if (diffcore_count_changes(src, dst, 184 &src->cnt_data, &dst->cnt_data, 185 delta_limit, 186 &src_copied, &literal_added)) 187 return 0; 188 189 /* How similar are they? 190 * what percentage of material in dst are from source? 191 */ 192 if (!dst->size) 193 score = 0; /* should not happen */ 194 else 195 score = (int)(src_copied * MAX_SCORE / max_size); 196 return score; 197} 198 199static void record_rename_pair(int dst_index, int src_index, int score) 200{ 201 struct diff_filespec *src, *dst; 202 struct diff_filepair *dp; 203 204 if (rename_dst[dst_index].pair) 205 die("internal error: dst already matched."); 206 207 src = rename_src[src_index].one; 208 src->rename_used++; 209 src->count++; 210 211 dst = rename_dst[dst_index].two; 212 dst->count++; 213 214 dp = diff_queue(NULL, src, dst); 215 dp->renamed_pair = 1; 216 if (!strcmp(src->path, dst->path)) 217 dp->score = rename_src[src_index].score; 218 else 219 dp->score = score; 220 rename_dst[dst_index].pair = dp; 221} 222 223/* 224 * We sort the rename similarity matrix with the score, in descending 225 * order (the most similar first). 226 */ 227static int score_compare(const void *a_, const void *b_) 228{ 229 const struct diff_score *a = a_, *b = b_; 230 231 /* sink the unused ones to the bottom */ 232 if (a->dst < 0) 233 return (0 <= b->dst); 234 else if (b->dst < 0) 235 return -1; 236 237 if (a->score == b->score) 238 return b->name_score - a->name_score; 239 240 return b->score - a->score; 241} 242 243struct file_similarity { 244 int src_dst, index; 245 struct diff_filespec *filespec; 246 struct file_similarity *next; 247}; 248 249static int find_identical_files(struct file_similarity *src, 250 struct file_similarity *dst) 251{ 252 int renames = 0; 253 254 /* 255 * Walk over all the destinations ... 256 */ 257 do { 258 struct diff_filespec *target = dst->filespec; 259 struct file_similarity *p, *best; 260 int i = 100, best_score = -1; 261 262 /* 263 * .. to find the best source match 264 */ 265 best = NULL; 266 for (p = src; p; p = p->next) { 267 int score; 268 struct diff_filespec *source = p->filespec; 269 270 /* False hash collision? */ 271 if (hashcmp(source->sha1, target->sha1)) 272 continue; 273 /* Non-regular files? If so, the modes must match! */ 274 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) { 275 if (source->mode != target->mode) 276 continue; 277 } 278 /* Give higher scores to sources that haven't been used already */ 279 score = !source->rename_used; 280 score += basename_same(source, target); 281 if (score > best_score) { 282 best = p; 283 best_score = score; 284 if (score == 2) 285 break; 286 } 287 288 /* Too many identical alternatives? Pick one */ 289 if (!--i) 290 break; 291 } 292 if (best) { 293 record_rename_pair(dst->index, best->index, MAX_SCORE); 294 renames++; 295 } 296 } while ((dst = dst->next) != NULL); 297 return renames; 298} 299 300static void free_similarity_list(struct file_similarity *p) 301{ 302 while (p) { 303 struct file_similarity *entry = p; 304 p = p->next; 305 free(entry); 306 } 307} 308 309static int find_same_files(void *ptr) 310{ 311 int ret; 312 struct file_similarity *p = ptr; 313 struct file_similarity *src = NULL, *dst = NULL; 314 315 /* Split the hash list up into sources and destinations */ 316 do { 317 struct file_similarity *entry = p; 318 p = p->next; 319 if (entry->src_dst < 0) { 320 entry->next = src; 321 src = entry; 322 } else { 323 entry->next = dst; 324 dst = entry; 325 } 326 } while (p); 327 328 /* 329 * If we have both sources *and* destinations, see if 330 * we can match them up 331 */ 332 ret = (src && dst) ? find_identical_files(src, dst) : 0; 333 334 /* Free the hashes and return the number of renames found */ 335 free_similarity_list(src); 336 free_similarity_list(dst); 337 return ret; 338} 339 340static unsigned int hash_filespec(struct diff_filespec *filespec) 341{ 342 unsigned int hash; 343 if (!filespec->sha1_valid) { 344 if (diff_populate_filespec(filespec, 0)) 345 return 0; 346 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1); 347 } 348 memcpy(&hash, filespec->sha1, sizeof(hash)); 349 return hash; 350} 351 352static void insert_file_table(struct hash_table *table, int src_dst, int index, struct diff_filespec *filespec) 353{ 354 void **pos; 355 unsigned int hash; 356 struct file_similarity *entry = xmalloc(sizeof(*entry)); 357 358 entry->src_dst = src_dst; 359 entry->index = index; 360 entry->filespec = filespec; 361 entry->next = NULL; 362 363 hash = hash_filespec(filespec); 364 pos = insert_hash(hash, entry, table); 365 366 /* We already had an entry there? */ 367 if (pos) { 368 entry->next = *pos; 369 *pos = entry; 370 } 371} 372 373/* 374 * Find exact renames first. 375 * 376 * The first round matches up the up-to-date entries, 377 * and then during the second round we try to match 378 * cache-dirty entries as well. 379 */ 380static int find_exact_renames(void) 381{ 382 int i; 383 struct hash_table file_table; 384 385 init_hash(&file_table); 386 for (i = 0; i < rename_src_nr; i++) 387 insert_file_table(&file_table, -1, i, rename_src[i].one); 388 389 for (i = 0; i < rename_dst_nr; i++) 390 insert_file_table(&file_table, 1, i, rename_dst[i].two); 391 392 /* Find the renames */ 393 i = for_each_hash(&file_table, find_same_files); 394 395 /* .. and free the hash data structure */ 396 free_hash(&file_table); 397 398 return i; 399} 400 401#define NUM_CANDIDATE_PER_DST 4 402static void record_if_better(struct diff_score m[], struct diff_score *o) 403{ 404 int i, worst; 405 406 /* find the worst one */ 407 worst = 0; 408 for (i = 1; i < NUM_CANDIDATE_PER_DST; i++) 409 if (score_compare(&m[i], &m[worst]) > 0) 410 worst = i; 411 412 /* is it better than the worst one? */ 413 if (score_compare(&m[worst], o) > 0) 414 m[worst] = *o; 415} 416 417void diffcore_rename(struct diff_options *options) 418{ 419 int detect_rename = options->detect_rename; 420 int minimum_score = options->rename_score; 421 int rename_limit = options->rename_limit; 422 struct diff_queue_struct *q = &diff_queued_diff; 423 struct diff_queue_struct outq; 424 struct diff_score *mx; 425 int i, j, rename_count; 426 int num_create, num_src, dst_cnt; 427 428 if (!minimum_score) 429 minimum_score = DEFAULT_RENAME_SCORE; 430 431 for (i = 0; i < q->nr; i++) { 432 struct diff_filepair *p = q->queue[i]; 433 if (!DIFF_FILE_VALID(p->one)) { 434 if (!DIFF_FILE_VALID(p->two)) 435 continue; /* unmerged */ 436 else if (options->single_follow && 437 strcmp(options->single_follow, p->two->path)) 438 continue; /* not interested */ 439 else 440 locate_rename_dst(p->two, 1); 441 } 442 else if (!DIFF_FILE_VALID(p->two)) { 443 /* 444 * If the source is a broken "delete", and 445 * they did not really want to get broken, 446 * that means the source actually stays. 447 * So we increment the "rename_used" score 448 * by one, to indicate ourselves as a user 449 */ 450 if (p->broken_pair && !p->score) 451 p->one->rename_used++; 452 register_rename_src(p->one, p->score); 453 } 454 else if (detect_rename == DIFF_DETECT_COPY) { 455 /* 456 * Increment the "rename_used" score by 457 * one, to indicate ourselves as a user. 458 */ 459 p->one->rename_used++; 460 register_rename_src(p->one, p->score); 461 } 462 } 463 if (rename_dst_nr == 0 || rename_src_nr == 0) 464 goto cleanup; /* nothing to do */ 465 466 /* 467 * We really want to cull the candidates list early 468 * with cheap tests in order to avoid doing deltas. 469 */ 470 rename_count = find_exact_renames(); 471 472 /* Did we only want exact renames? */ 473 if (minimum_score == MAX_SCORE) 474 goto cleanup; 475 476 /* 477 * Calculate how many renames are left (but all the source 478 * files still remain as options for rename/copies!) 479 */ 480 num_create = (rename_dst_nr - rename_count); 481 num_src = rename_src_nr; 482 483 /* All done? */ 484 if (!num_create) 485 goto cleanup; 486 487 /* 488 * This basically does a test for the rename matrix not 489 * growing larger than a "rename_limit" square matrix, ie: 490 * 491 * num_create * num_src > rename_limit * rename_limit 492 * 493 * but handles the potential overflow case specially (and we 494 * assume at least 32-bit integers) 495 */ 496 if (rename_limit <= 0 || rename_limit > 32767) 497 rename_limit = 32767; 498 if ((num_create > rename_limit && num_src > rename_limit) || 499 (num_create * num_src > rename_limit * rename_limit)) { 500 if (options->warn_on_too_large_rename) 501 warning("too many files (created: %d deleted: %d), skipping inexact rename detection", num_create, num_src); 502 goto cleanup; 503 } 504 505 mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, sizeof(*mx)); 506 for (dst_cnt = i = 0; i < rename_dst_nr; i++) { 507 struct diff_filespec *two = rename_dst[i].two; 508 struct diff_score *m; 509 510 if (rename_dst[i].pair) 511 continue; /* dealt with exact match already. */ 512 513 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST]; 514 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++) 515 m[j].dst = -1; 516 517 for (j = 0; j < rename_src_nr; j++) { 518 struct diff_filespec *one = rename_src[j].one; 519 struct diff_score this_src; 520 this_src.score = estimate_similarity(one, two, 521 minimum_score); 522 this_src.name_score = basename_same(one, two); 523 this_src.dst = i; 524 this_src.src = j; 525 record_if_better(m, &this_src); 526 /* 527 * Once we run estimate_similarity, 528 * We do not need the text anymore. 529 */ 530 diff_free_filespec_blob(one); 531 diff_free_filespec_blob(two); 532 } 533 dst_cnt++; 534 } 535 536 /* cost matrix sorted by most to least similar pair */ 537 qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare); 538 539 for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) { 540 struct diff_rename_dst *dst; 541 542 if ((mx[i].dst < 0) || 543 (mx[i].score < minimum_score)) 544 break; /* there is no more usable pair. */ 545 dst = &rename_dst[mx[i].dst]; 546 if (dst->pair) 547 continue; /* already done, either exact or fuzzy. */ 548 if (rename_src[mx[i].src].one->rename_used) 549 continue; 550 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score); 551 rename_count++; 552 } 553 554 for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) { 555 struct diff_rename_dst *dst; 556 557 if ((mx[i].dst < 0) || 558 (mx[i].score < minimum_score)) 559 break; /* there is no more usable pair. */ 560 dst = &rename_dst[mx[i].dst]; 561 if (dst->pair) 562 continue; /* already done, either exact or fuzzy. */ 563 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score); 564 rename_count++; 565 } 566 free(mx); 567 568 cleanup: 569 /* At this point, we have found some renames and copies and they 570 * are recorded in rename_dst. The original list is still in *q. 571 */ 572 DIFF_QUEUE_CLEAR(&outq); 573 for (i = 0; i < q->nr; i++) { 574 struct diff_filepair *p = q->queue[i]; 575 struct diff_filepair *pair_to_free = NULL; 576 577 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) { 578 /* 579 * Creation 580 * 581 * We would output this create record if it has 582 * not been turned into a rename/copy already. 583 */ 584 struct diff_rename_dst *dst = 585 locate_rename_dst(p->two, 0); 586 if (dst && dst->pair) { 587 diff_q(&outq, dst->pair); 588 pair_to_free = p; 589 } 590 else 591 /* no matching rename/copy source, so 592 * record this as a creation. 593 */ 594 diff_q(&outq, p); 595 } 596 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) { 597 /* 598 * Deletion 599 * 600 * We would output this delete record if: 601 * 602 * (1) this is a broken delete and the counterpart 603 * broken create remains in the output; or 604 * (2) this is not a broken delete, and rename_dst 605 * does not have a rename/copy to move p->one->path 606 * out of existence. 607 * 608 * Otherwise, the counterpart broken create 609 * has been turned into a rename-edit; or 610 * delete did not have a matching create to 611 * begin with. 612 */ 613 if (DIFF_PAIR_BROKEN(p)) { 614 /* broken delete */ 615 struct diff_rename_dst *dst = 616 locate_rename_dst(p->one, 0); 617 if (dst && dst->pair) 618 /* counterpart is now rename/copy */ 619 pair_to_free = p; 620 } 621 else { 622 if (p->one->rename_used) 623 /* this path remains */ 624 pair_to_free = p; 625 } 626 627 if (pair_to_free) 628 ; 629 else 630 diff_q(&outq, p); 631 } 632 else if (!diff_unmodified_pair(p)) 633 /* all the usual ones need to be kept */ 634 diff_q(&outq, p); 635 else 636 /* no need to keep unmodified pairs */ 637 pair_to_free = p; 638 639 if (pair_to_free) 640 diff_free_filepair(pair_to_free); 641 } 642 diff_debug_queue("done copying original", &outq); 643 644 free(q->queue); 645 *q = outq; 646 diff_debug_queue("done collapsing", q); 647 648 for (i = 0; i < rename_dst_nr; i++) 649 free_filespec(rename_dst[i].two); 650 651 free(rename_dst); 652 rename_dst = NULL; 653 rename_dst_nr = rename_dst_alloc = 0; 654 free(rename_src); 655 rename_src = NULL; 656 rename_src_nr = rename_src_alloc = 0; 657 return; 658}