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 #include "levenshtein.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         if (rename_dst_alloc <= rename_dst_nr) {
  42                 rename_dst_alloc = alloc_nr(rename_dst_alloc);
  43                 rename_dst = xrealloc(rename_dst,
  44                                       rename_dst_alloc * sizeof(*rename_dst));
  45         }
  46         rename_dst_nr++;
  47         if (first < rename_dst_nr)
  48                 memmove(rename_dst + first + 1, rename_dst + first,
  49                         (rename_dst_nr - first - 1) * sizeof(*rename_dst));
  50         rename_dst[first].two = alloc_filespec(two->path);
  51         fill_filespec(rename_dst[first].two, two->sha1, two->mode);
  52         rename_dst[first].pair = NULL;
  53         return &(rename_dst[first]);
  54 }
  55
  56 /* Table of rename/copy src files */
  57 static struct diff_rename_src {
  58         struct diff_filespec *one;
  59         unsigned short score; /* to remember the break score */
  60 } *rename_src;
  61 static int rename_src_nr, rename_src_alloc;
  62
  63 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
  64                                                    unsigned short score)
  65 {
  66         int first, last;
  67
  68         first = 0;
  69         last = rename_src_nr;
  70         while (last > first) {
  71                 int next = (last + first) >> 1;
  72                 struct diff_rename_src *src = &(rename_src[next]);
  73                 int cmp = strcmp(one->path, src->one->path);
  74                 if (!cmp)
  75                         return src;
  76                 if (cmp < 0) {
  77                         last = next;
  78                         continue;
  79                 }
  80                 first = next+1;
  81         }
  82
  83         /* insert to make it at "first" */
  84         if (rename_src_alloc <= rename_src_nr) {
  85                 rename_src_alloc = alloc_nr(rename_src_alloc);
  86                 rename_src = xrealloc(rename_src,
  87                                       rename_src_alloc * sizeof(*rename_src));
  88         }
  89         rename_src_nr++;
  90         if (first < rename_src_nr)
  91                 memmove(rename_src + first + 1, rename_src + first,
  92                         (rename_src_nr - first - 1) * sizeof(*rename_src));
  93         rename_src[first].one = one;
  94         rename_src[first].score = score;
  95         return &(rename_src[first]);
  96 }
  97
  98 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
  99 {
 100         int src_len = strlen(src->path), dst_len = strlen(dst->path);
 101         while (src_len && dst_len) {
 102                 char c1 = src->path[--src_len];
 103                 char c2 = dst->path[--dst_len];
 104                 if (c1 != c2)
 105                         return 0;
 106                 if (c1 == '/')
 107                         return 1;
 108         }
 109         return (!src_len || src->path[src_len - 1] == '/') &&
 110                 (!dst_len || dst->path[dst_len - 1] == '/');
 111 }
 112
 113 struct diff_score {
 114         int src; /* index in rename_src */
 115         int dst; /* index in rename_dst */
 116         unsigned short score;
 117         short name_score;
 118 };
 119
 120 static int estimate_similarity(struct diff_filespec *src,
 121                                struct diff_filespec *dst,
 122                                int minimum_score)
 123 {
 124         /* src points at a file that existed in the original tree (or
 125          * optionally a file in the destination tree) and dst points
 126          * at a newly created file.  They may be quite similar, in which
 127          * case we want to say src is renamed to dst or src is copied into
 128          * dst, and then some edit has been applied to dst.
 129          *
 130          * Compare them and return how similar they are, representing
 131          * the score as an integer between 0 and MAX_SCORE.
 132          *
 133          * When there is an exact match, it is considered a better
 134          * match than anything else; the destination does not even
 135          * call into this function in that case.
 136          */
 137         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 138         unsigned long delta_limit;
 139         int score;
 140
 141         /* We deal only with regular files.  Symlink renames are handled
 142          * only when they are exact matches --- in other words, no edits
 143          * after renaming.
 144          */
 145         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 146                 return 0;
 147
 148         /*
 149          * Need to check that source and destination sizes are
 150          * filled in before comparing them.
 151          *
 152          * If we already have "cnt_data" filled in, we know it's
 153          * all good (avoid checking the size for zero, as that
 154          * is a possible size - we really should have a flag to
 155          * say whether the size is valid or not!)
 156          */
 157         if (!src->cnt_data && diff_populate_filespec(src, 1))
 158                 return 0;
 159         if (!dst->cnt_data && diff_populate_filespec(dst, 1))
 160                 return 0;
 161
 162         max_size = ((src->size > dst->size) ? src->size : dst->size);
 163         base_size = ((src->size < dst->size) ? src->size : dst->size);
 164         delta_size = max_size - base_size;
 165
 166         /* We would not consider edits that change the file size so
 167          * drastically.  delta_size must be smaller than
 168          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 169          *
 170          * Note that base_size == 0 case is handled here already
 171          * and the final score computation below would not have a
 172          * divide-by-zero issue.
 173          */
 174         if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 175                 return 0;
 176
 177         if (!src->cnt_data && diff_populate_filespec(src, 0))
 178                 return 0;
 179         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
 180                 return 0;
 181
 182         delta_limit = (unsigned long)
 183                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
 184         if (diffcore_count_changes(src, dst,
 185                                    &src->cnt_data, &dst->cnt_data,
 186                                    delta_limit,
 187                                    &src_copied, &literal_added))
 188                 return 0;
 189
 190         /* How similar are they?
 191          * what percentage of material in dst are from source?
 192          */
 193         if (!dst->size)
 194                 score = 0; /* should not happen */
 195         else
 196                 score = (int)(src_copied * MAX_SCORE / max_size)
 197                         - (getenv("GIT_USE_LEVENSHTEIN") ?
 198                            levenshtein(src->path, dst->path, 1, 1, 1, 1) : 0);
 199         return score;
 200 }
 201
 202 static void record_rename_pair(int dst_index, int src_index, int score)
 203 {
 204         struct diff_filespec *src, *dst;
 205         struct diff_filepair *dp;
 206
 207         if (rename_dst[dst_index].pair)
 208                 die("internal error: dst already matched.");
 209
 210         src = rename_src[src_index].one;
 211         src->rename_used++;
 212         src->count++;
 213
 214         dst = rename_dst[dst_index].two;
 215         dst->count++;
 216
 217         dp = diff_queue(NULL, src, dst);
 218         dp->renamed_pair = 1;
 219         if (!strcmp(src->path, dst->path))
 220                 dp->score = rename_src[src_index].score;
 221         else
 222                 dp->score = score;
 223         rename_dst[dst_index].pair = dp;
 224 }
 225
 226 /*
 227  * We sort the rename similarity matrix with the score, in descending
 228  * order (the most similar first).
 229  */
 230 static int score_compare(const void *a_, const void *b_)
 231 {
 232         const struct diff_score *a = a_, *b = b_;
 233
 234         /* sink the unused ones to the bottom */
 235         if (a->dst < 0)
 236                 return (0 <= b->dst);
 237         else if (b->dst < 0)
 238                 return -1;
 239
 240         if (a->score == b->score)
 241                 return b->name_score - a->name_score;
 242
 243         return b->score - a->score;
 244 }
 245
 246 struct file_similarity {
 247         int src_dst, index;
 248         struct diff_filespec *filespec;
 249         struct file_similarity *next;
 250 };
 251
 252 static int find_identical_files(struct file_similarity *src,
 253                                 struct file_similarity *dst)
 254 {
 255         int renames = 0;
 256
 257         /*
 258          * Walk over all the destinations ...
 259          */
 260         do {
 261                 struct diff_filespec *target = dst->filespec;
 262                 struct file_similarity *p, *best;
 263                 int i = 100, best_score = -1;
 264
 265                 /*
 266                  * .. to find the best source match
 267                  */
 268                 best = NULL;
 269                 for (p = src; p; p = p->next) {
 270                         int score;
 271                         struct diff_filespec *source = p->filespec;
 272
 273                         /* False hash collision? */
 274                         if (hashcmp(source->sha1, target->sha1))
 275                                 continue;
 276                         /* Non-regular files? If so, the modes must match! */
 277                         if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 278                                 if (source->mode != target->mode)
 279                                         continue;
 280                         }
 281                         /* Give higher scores to sources that haven't been used already */
 282                         score = !source->rename_used;
 283                         score += basename_same(source, target);
 284                         if (score > best_score) {
 285                                 best = p;
 286                                 best_score = score;
 287                                 if (score == 2)
 288                                         break;
 289                         }
 290
 291                         /* Too many identical alternatives? Pick one */
 292                         if (!--i)
 293                                 break;
 294                 }
 295                 if (best) {
 296                         record_rename_pair(dst->index, best->index, MAX_SCORE);
 297                         renames++;
 298                 }
 299         } while ((dst = dst->next) != NULL);
 300         return renames;
 301 }
 302
 303 static void free_similarity_list(struct file_similarity *p)
 304 {
 305         while (p) {
 306                 struct file_similarity *entry = p;
 307                 p = p->next;
 308                 free(entry);
 309         }
 310 }
 311
 312 static int find_same_files(void *ptr)
 313 {
 314         int ret;
 315         struct file_similarity *p = ptr;
 316         struct file_similarity *src = NULL, *dst = NULL;
 317
 318         /* Split the hash list up into sources and destinations */
 319         do {
 320                 struct file_similarity *entry = p;
 321                 p = p->next;
 322                 if (entry->src_dst < 0) {
 323                         entry->next = src;
 324                         src = entry;
 325                 } else {
 326                         entry->next = dst;
 327                         dst = entry;
 328                 }
 329         } while (p);
 330
 331         /*
 332          * If we have both sources *and* destinations, see if
 333          * we can match them up
 334          */
 335         ret = (src && dst) ? find_identical_files(src, dst) : 0;
 336
 337         /* Free the hashes and return the number of renames found */
 338         free_similarity_list(src);
 339         free_similarity_list(dst);
 340         return ret;
 341 }
 342
 343 static unsigned int hash_filespec(struct diff_filespec *filespec)
 344 {
 345         unsigned int hash;
 346         if (!filespec->sha1_valid) {
 347                 if (diff_populate_filespec(filespec, 0))
 348                         return 0;
 349                 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
 350         }
 351         memcpy(&hash, filespec->sha1, sizeof(hash));
 352         return hash;
 353 }
 354
 355 static void insert_file_table(struct hash_table *table, int src_dst, int index, struct diff_filespec *filespec)
 356 {
 357         void **pos;
 358         unsigned int hash;
 359         struct file_similarity *entry = xmalloc(sizeof(*entry));
 360
 361         entry->src_dst = src_dst;
 362         entry->index = index;
 363         entry->filespec = filespec;
 364         entry->next = NULL;
 365
 366         hash = hash_filespec(filespec);
 367         pos = insert_hash(hash, entry, table);
 368
 369         /* We already had an entry there? */
 370         if (pos) {
 371                 entry->next = *pos;
 372                 *pos = entry;
 373         }
 374 }
 375
 376 /*
 377  * Find exact renames first.
 378  *
 379  * The first round matches up the up-to-date entries,
 380  * and then during the second round we try to match
 381  * cache-dirty entries as well.
 382  */
 383 static int find_exact_renames(void)
 384 {
 385         int i;
 386         struct hash_table file_table;
 387
 388         init_hash(&file_table);
 389         for (i = 0; i < rename_src_nr; i++)
 390                 insert_file_table(&file_table, -1, i, rename_src[i].one);
 391
 392         for (i = 0; i < rename_dst_nr; i++)
 393                 insert_file_table(&file_table, 1, i, rename_dst[i].two);
 394
 395         /* Find the renames */
 396         i = for_each_hash(&file_table, find_same_files);
 397
 398         /* .. and free the hash data structure */
 399         free_hash(&file_table);
 400
 401         return i;
 402 }
 403
 404 #define NUM_CANDIDATE_PER_DST 4
 405 static void record_if_better(struct diff_score m[], struct diff_score *o)
 406 {
 407         int i, worst;
 408
 409         /* find the worst one */
 410         worst = 0;
 411         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 412                 if (score_compare(&m[i], &m[worst]) > 0)
 413                         worst = i;
 414
 415         /* is it better than the worst one? */
 416         if (score_compare(&m[worst], o) > 0)
 417                 m[worst] = *o;
 418 }
 419
 420 void diffcore_rename(struct diff_options *options)
 421 {
 422         int detect_rename = options->detect_rename;
 423         int minimum_score = options->rename_score;
 424         int rename_limit = options->rename_limit;
 425         struct diff_queue_struct *q = &diff_queued_diff;
 426         struct diff_queue_struct outq;
 427         struct diff_score *mx;
 428         int i, j, rename_count;
 429         int num_create, num_src, dst_cnt;
 430
 431         if (!minimum_score)
 432                 minimum_score = DEFAULT_RENAME_SCORE;
 433
 434         for (i = 0; i < q->nr; i++) {
 435                 struct diff_filepair *p = q->queue[i];
 436                 if (!DIFF_FILE_VALID(p->one)) {
 437                         if (!DIFF_FILE_VALID(p->two))
 438                                 continue; /* unmerged */
 439                         else if (options->single_follow &&
 440                                  strcmp(options->single_follow, p->two->path))
 441                                 continue; /* not interested */
 442                         else
 443                                 locate_rename_dst(p->two, 1);
 444                 }
 445                 else if (!DIFF_FILE_VALID(p->two)) {
 446                         /*
 447                          * If the source is a broken "delete", and
 448                          * they did not really want to get broken,
 449                          * that means the source actually stays.
 450                          * So we increment the "rename_used" score
 451                          * by one, to indicate ourselves as a user
 452                          */
 453                         if (p->broken_pair && !p->score)
 454                                 p->one->rename_used++;
 455                         register_rename_src(p->one, p->score);
 456                 }
 457                 else if (detect_rename == DIFF_DETECT_COPY) {
 458                         /*
 459                          * Increment the "rename_used" score by
 460                          * one, to indicate ourselves as a user.
 461                          */
 462                         p->one->rename_used++;
 463                         register_rename_src(p->one, p->score);
 464                 }
 465         }
 466         if (rename_dst_nr == 0 || rename_src_nr == 0)
 467                 goto cleanup; /* nothing to do */
 468
 469         /*
 470          * We really want to cull the candidates list early
 471          * with cheap tests in order to avoid doing deltas.
 472          */
 473         rename_count = find_exact_renames();
 474
 475         /* Did we only want exact renames? */
 476         if (minimum_score == MAX_SCORE)
 477                 goto cleanup;
 478
 479         /*
 480          * Calculate how many renames are left (but all the source
 481          * files still remain as options for rename/copies!)
 482          */
 483         num_create = (rename_dst_nr - rename_count);
 484         num_src = rename_src_nr;
 485
 486         /* All done? */
 487         if (!num_create)
 488                 goto cleanup;
 489
 490         /*
 491          * This basically does a test for the rename matrix not
 492          * growing larger than a "rename_limit" square matrix, ie:
 493          *
 494          *    num_create * num_src > rename_limit * rename_limit
 495          *
 496          * but handles the potential overflow case specially (and we
 497          * assume at least 32-bit integers)
 498          */
 499         if (rename_limit <= 0 || rename_limit > 32767)
 500                 rename_limit = 32767;
 501         if ((num_create > rename_limit && num_src > rename_limit) ||
 502             (num_create * num_src > rename_limit * rename_limit)) {
 503                 if (options->warn_on_too_large_rename)
 504                         warning("too many files (created: %d deleted: %d), skipping inexact rename detection", num_create, num_src);
 505                 goto cleanup;
 506         }
 507
 508         mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, sizeof(*mx));
 509         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 510                 struct diff_filespec *two = rename_dst[i].two;
 511                 struct diff_score *m;
 512
 513                 if (rename_dst[i].pair)
 514                         continue; /* dealt with exact match already. */
 515
 516                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 517                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 518                         m[j].dst = -1;
 519
 520                 for (j = 0; j < rename_src_nr; j++) {
 521                         struct diff_filespec *one = rename_src[j].one;
 522                         struct diff_score this_src;
 523                         this_src.score = estimate_similarity(one, two,
 524                                                              minimum_score);
 525                         this_src.name_score = basename_same(one, two);
 526                         this_src.dst = i;
 527                         this_src.src = j;
 528                         record_if_better(m, &this_src);
 529                         /*
 530                          * Once we run estimate_similarity,
 531                          * We do not need the text anymore.
 532                          */
 533                         diff_free_filespec_blob(one);
 534                         diff_free_filespec_blob(two);
 535                 }
 536                 dst_cnt++;
 537         }
 538
 539         /* cost matrix sorted by most to least similar pair */
 540         qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
 541
 542         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 543                 struct diff_rename_dst *dst;
 544
 545                 if ((mx[i].dst < 0) ||
 546                     (mx[i].score < minimum_score))
 547                         break; /* there is no more usable pair. */
 548                 dst = &rename_dst[mx[i].dst];
 549                 if (dst->pair)
 550                         continue; /* already done, either exact or fuzzy. */
 551                 if (rename_src[mx[i].src].one->rename_used)
 552                         continue;
 553                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 554                 rename_count++;
 555         }
 556
 557         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 558                 struct diff_rename_dst *dst;
 559
 560                 if ((mx[i].dst < 0) ||
 561                     (mx[i].score < minimum_score))
 562                         break; /* there is no more usable pair. */
 563                 dst = &rename_dst[mx[i].dst];
 564                 if (dst->pair)
 565                         continue; /* already done, either exact or fuzzy. */
 566                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 567                 rename_count++;
 568         }
 569         free(mx);
 570
 571  cleanup:
 572         /* At this point, we have found some renames and copies and they
 573          * are recorded in rename_dst.  The original list is still in *q.
 574          */
 575         outq.queue = NULL;
 576         outq.nr = outq.alloc = 0;
 577         for (i = 0; i < q->nr; i++) {
 578                 struct diff_filepair *p = q->queue[i];
 579                 struct diff_filepair *pair_to_free = NULL;
 580
 581                 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 582                         /*
 583                          * Creation
 584                          *
 585                          * We would output this create record if it has
 586                          * not been turned into a rename/copy already.
 587                          */
 588                         struct diff_rename_dst *dst =
 589                                 locate_rename_dst(p->two, 0);
 590                         if (dst && dst->pair) {
 591                                 diff_q(&outq, dst->pair);
 592                                 pair_to_free = p;
 593                         }
 594                         else
 595                                 /* no matching rename/copy source, so
 596                                  * record this as a creation.
 597                                  */
 598                                 diff_q(&outq, p);
 599                 }
 600                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 601                         /*
 602                          * Deletion
 603                          *
 604                          * We would output this delete record if:
 605                          *
 606                          * (1) this is a broken delete and the counterpart
 607                          *     broken create remains in the output; or
 608                          * (2) this is not a broken delete, and rename_dst
 609                          *     does not have a rename/copy to move p->one->path
 610                          *     out of existence.
 611                          *
 612                          * Otherwise, the counterpart broken create
 613                          * has been turned into a rename-edit; or
 614                          * delete did not have a matching create to
 615                          * begin with.
 616                          */
 617                         if (DIFF_PAIR_BROKEN(p)) {
 618                                 /* broken delete */
 619                                 struct diff_rename_dst *dst =
 620                                         locate_rename_dst(p->one, 0);
 621                                 if (dst && dst->pair)
 622                                         /* counterpart is now rename/copy */
 623                                         pair_to_free = p;
 624                         }
 625                         else {
 626                                 if (p->one->rename_used)
 627                                         /* this path remains */
 628                                         pair_to_free = p;
 629                         }
 630
 631                         if (pair_to_free)
 632                                 ;
 633                         else
 634                                 diff_q(&outq, p);
 635                 }
 636                 else if (!diff_unmodified_pair(p))
 637                         /* all the usual ones need to be kept */
 638                         diff_q(&outq, p);
 639                 else
 640                         /* no need to keep unmodified pairs */
 641                         pair_to_free = p;
 642
 643                 if (pair_to_free)
 644                         diff_free_filepair(pair_to_free);
 645         }
 646         diff_debug_queue("done copying original", &outq);
 647
 648         free(q->queue);
 649         *q = outq;
 650         diff_debug_queue("done collapsing", q);
 651
 652         for (i = 0; i < rename_dst_nr; i++)
 653                 free_filespec(rename_dst[i].two);
 654
 655         free(rename_dst);
 656         rename_dst = NULL;
 657         rename_dst_nr = rename_dst_alloc = 0;
 658         free(rename_src);
 659         rename_src = NULL;
 660         rename_src_nr = rename_src_alloc = 0;
 661         return;
 662 }