diffcore-rename.con commit Cast 64 bit off_t to 32 bit size_t (dc49cd7)
   1/*
   2 * Copyright (C) 2005 Junio C Hamano
   3 */
   4#include "cache.h"
   5#include "diff.h"
   6#include "diffcore.h"
   7
   8/* Table of rename/copy destinations */
   9
  10static struct diff_rename_dst {
  11        struct diff_filespec *two;
  12        struct diff_filepair *pair;
  13} *rename_dst;
  14static int rename_dst_nr, rename_dst_alloc;
  15
  16static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
  17                                                 int insert_ok)
  18{
  19        int first, last;
  20
  21        first = 0;
  22        last = rename_dst_nr;
  23        while (last > first) {
  24                int next = (last + first) >> 1;
  25                struct diff_rename_dst *dst = &(rename_dst[next]);
  26                int cmp = strcmp(two->path, dst->two->path);
  27                if (!cmp)
  28                        return dst;
  29                if (cmp < 0) {
  30                        last = next;
  31                        continue;
  32                }
  33                first = next+1;
  34        }
  35        /* not found */
  36        if (!insert_ok)
  37                return NULL;
  38        /* insert to make it at "first" */
  39        if (rename_dst_alloc <= rename_dst_nr) {
  40                rename_dst_alloc = alloc_nr(rename_dst_alloc);
  41                rename_dst = xrealloc(rename_dst,
  42                                      rename_dst_alloc * sizeof(*rename_dst));
  43        }
  44        rename_dst_nr++;
  45        if (first < rename_dst_nr)
  46                memmove(rename_dst + first + 1, rename_dst + first,
  47                        (rename_dst_nr - first - 1) * sizeof(*rename_dst));
  48        rename_dst[first].two = alloc_filespec(two->path);
  49        fill_filespec(rename_dst[first].two, two->sha1, two->mode);
  50        rename_dst[first].pair = NULL;
  51        return &(rename_dst[first]);
  52}
  53
  54/* Table of rename/copy src files */
  55static struct diff_rename_src {
  56        struct diff_filespec *one;
  57        unsigned short score; /* to remember the break score */
  58        unsigned src_path_left : 1;
  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                                                   int src_path_left,
  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        rename_src[first].src_path_left = src_path_left;
  96        return &(rename_src[first]);
  97}
  98
  99static int is_exact_match(struct diff_filespec *src,
 100                          struct diff_filespec *dst,
 101                          int contents_too)
 102{
 103        if (src->sha1_valid && dst->sha1_valid &&
 104            !hashcmp(src->sha1, dst->sha1))
 105                return 1;
 106        if (!contents_too)
 107                return 0;
 108        if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
 109                return 0;
 110        if (src->size != dst->size)
 111                return 0;
 112        if (src->sha1_valid && dst->sha1_valid)
 113            return !hashcmp(src->sha1, dst->sha1);
 114        if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
 115                return 0;
 116        if (src->size == dst->size &&
 117            !memcmp(src->data, dst->data, src->size))
 118                return 1;
 119        return 0;
 120}
 121
 122struct diff_score {
 123        int src; /* index in rename_src */
 124        int dst; /* index in rename_dst */
 125        int score;
 126};
 127
 128static int estimate_similarity(struct diff_filespec *src,
 129                               struct diff_filespec *dst,
 130                               int minimum_score)
 131{
 132        /* src points at a file that existed in the original tree (or
 133         * optionally a file in the destination tree) and dst points
 134         * at a newly created file.  They may be quite similar, in which
 135         * case we want to say src is renamed to dst or src is copied into
 136         * dst, and then some edit has been applied to dst.
 137         *
 138         * Compare them and return how similar they are, representing
 139         * the score as an integer between 0 and MAX_SCORE.
 140         *
 141         * When there is an exact match, it is considered a better
 142         * match than anything else; the destination does not even
 143         * call into this function in that case.
 144         */
 145        unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 146        unsigned long delta_limit;
 147        int score;
 148
 149        /* We deal only with regular files.  Symlink renames are handled
 150         * only when they are exact matches --- in other words, no edits
 151         * after renaming.
 152         */
 153        if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 154                return 0;
 155
 156        max_size = ((src->size > dst->size) ? src->size : dst->size);
 157        base_size = ((src->size < dst->size) ? src->size : dst->size);
 158        delta_size = max_size - base_size;
 159
 160        /* We would not consider edits that change the file size so
 161         * drastically.  delta_size must be smaller than
 162         * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 163         *
 164         * Note that base_size == 0 case is handled here already
 165         * and the final score computation below would not have a
 166         * divide-by-zero issue.
 167         */
 168        if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 169                return 0;
 170
 171        if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
 172                return 0; /* error but caught downstream */
 173
 174
 175        delta_limit = (unsigned long)
 176                (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
 177        if (diffcore_count_changes(src->data, src->size,
 178                                   dst->data, dst->size,
 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
 194static void record_rename_pair(int dst_index, int src_index, int score)
 195{
 196        struct diff_filespec *one, *two, *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        one = alloc_filespec(src->path);
 204        fill_filespec(one, src->sha1, src->mode);
 205
 206        dst = rename_dst[dst_index].two;
 207        two = alloc_filespec(dst->path);
 208        fill_filespec(two, dst->sha1, dst->mode);
 209
 210        dp = diff_queue(NULL, one, two);
 211        dp->renamed_pair = 1;
 212        if (!strcmp(src->path, dst->path))
 213                dp->score = rename_src[src_index].score;
 214        else
 215                dp->score = score;
 216        dp->source_stays = rename_src[src_index].src_path_left;
 217        rename_dst[dst_index].pair = dp;
 218}
 219
 220/*
 221 * We sort the rename similarity matrix with the score, in descending
 222 * order (the most similar first).
 223 */
 224static int score_compare(const void *a_, const void *b_)
 225{
 226        const struct diff_score *a = a_, *b = b_;
 227        return b->score - a->score;
 228}
 229
 230static int compute_stays(struct diff_queue_struct *q,
 231                         struct diff_filespec *one)
 232{
 233        int i;
 234        for (i = 0; i < q->nr; i++) {
 235                struct diff_filepair *p = q->queue[i];
 236                if (strcmp(one->path, p->two->path))
 237                        continue;
 238                if (DIFF_PAIR_RENAME(p)) {
 239                        return 0; /* something else is renamed into this */
 240                }
 241        }
 242        return 1;
 243}
 244
 245void diffcore_rename(struct diff_options *options)
 246{
 247        int detect_rename = options->detect_rename;
 248        int minimum_score = options->rename_score;
 249        int rename_limit = options->rename_limit;
 250        struct diff_queue_struct *q = &diff_queued_diff;
 251        struct diff_queue_struct outq;
 252        struct diff_score *mx;
 253        int i, j, rename_count, contents_too;
 254        int num_create, num_src, dst_cnt;
 255
 256        if (!minimum_score)
 257                minimum_score = DEFAULT_RENAME_SCORE;
 258        rename_count = 0;
 259
 260        for (i = 0; i < q->nr; i++) {
 261                struct diff_filepair *p = q->queue[i];
 262                if (!DIFF_FILE_VALID(p->one)) {
 263                        if (!DIFF_FILE_VALID(p->two))
 264                                continue; /* unmerged */
 265                        else if (options->single_follow &&
 266                                 strcmp(options->single_follow, p->two->path))
 267                                continue; /* not interested */
 268                        else
 269                                locate_rename_dst(p->two, 1);
 270                }
 271                else if (!DIFF_FILE_VALID(p->two)) {
 272                        /* If the source is a broken "delete", and
 273                         * they did not really want to get broken,
 274                         * that means the source actually stays.
 275                         */
 276                        int stays = (p->broken_pair && !p->score);
 277                        register_rename_src(p->one, stays, p->score);
 278                }
 279                else if (detect_rename == DIFF_DETECT_COPY)
 280                        register_rename_src(p->one, 1, p->score);
 281        }
 282        if (rename_dst_nr == 0 || rename_src_nr == 0 ||
 283            (0 < rename_limit && rename_limit < rename_dst_nr))
 284                goto cleanup; /* nothing to do */
 285
 286        /* We really want to cull the candidates list early
 287         * with cheap tests in order to avoid doing deltas.
 288         * The first round matches up the up-to-date entries,
 289         * and then during the second round we try to match
 290         * cache-dirty entries as well.
 291         */
 292        for (contents_too = 0; contents_too < 2; contents_too++) {
 293                for (i = 0; i < rename_dst_nr; i++) {
 294                        struct diff_filespec *two = rename_dst[i].two;
 295                        if (rename_dst[i].pair)
 296                                continue; /* dealt with an earlier round */
 297                        for (j = 0; j < rename_src_nr; j++) {
 298                                struct diff_filespec *one = rename_src[j].one;
 299                                if (!is_exact_match(one, two, contents_too))
 300                                        continue;
 301                                record_rename_pair(i, j, (int)MAX_SCORE);
 302                                rename_count++;
 303                                break; /* we are done with this entry */
 304                        }
 305                }
 306        }
 307
 308        /* Have we run out the created file pool?  If so we can avoid
 309         * doing the delta matrix altogether.
 310         */
 311        if (rename_count == rename_dst_nr)
 312                goto cleanup;
 313
 314        if (minimum_score == MAX_SCORE)
 315                goto cleanup;
 316
 317        num_create = (rename_dst_nr - rename_count);
 318        num_src = rename_src_nr;
 319        mx = xmalloc(sizeof(*mx) * num_create * num_src);
 320        for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 321                int base = dst_cnt * num_src;
 322                struct diff_filespec *two = rename_dst[i].two;
 323                if (rename_dst[i].pair)
 324                        continue; /* dealt with exact match already. */
 325                for (j = 0; j < rename_src_nr; j++) {
 326                        struct diff_filespec *one = rename_src[j].one;
 327                        struct diff_score *m = &mx[base+j];
 328                        m->src = j;
 329                        m->dst = i;
 330                        m->score = estimate_similarity(one, two,
 331                                                       minimum_score);
 332                }
 333                /* We do not need the text anymore */
 334                diff_free_filespec_data(two);
 335                dst_cnt++;
 336        }
 337        /* cost matrix sorted by most to least similar pair */
 338        qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
 339        for (i = 0; i < num_create * num_src; i++) {
 340                struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
 341                if (dst->pair)
 342                        continue; /* already done, either exact or fuzzy. */
 343                if (mx[i].score < minimum_score)
 344                        break; /* there is no more usable pair. */
 345                record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 346                rename_count++;
 347        }
 348        free(mx);
 349
 350 cleanup:
 351        /* At this point, we have found some renames and copies and they
 352         * are recorded in rename_dst.  The original list is still in *q.
 353         */
 354        outq.queue = NULL;
 355        outq.nr = outq.alloc = 0;
 356        for (i = 0; i < q->nr; i++) {
 357                struct diff_filepair *p = q->queue[i];
 358                struct diff_filepair *pair_to_free = NULL;
 359
 360                if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 361                        /*
 362                         * Creation
 363                         *
 364                         * We would output this create record if it has
 365                         * not been turned into a rename/copy already.
 366                         */
 367                        struct diff_rename_dst *dst =
 368                                locate_rename_dst(p->two, 0);
 369                        if (dst && dst->pair) {
 370                                diff_q(&outq, dst->pair);
 371                                pair_to_free = p;
 372                        }
 373                        else
 374                                /* no matching rename/copy source, so
 375                                 * record this as a creation.
 376                                 */
 377                                diff_q(&outq, p);
 378                }
 379                else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 380                        /*
 381                         * Deletion
 382                         *
 383                         * We would output this delete record if:
 384                         *
 385                         * (1) this is a broken delete and the counterpart
 386                         *     broken create remains in the output; or
 387                         * (2) this is not a broken delete, and rename_dst
 388                         *     does not have a rename/copy to move p->one->path
 389                         *     out of existence.
 390                         *
 391                         * Otherwise, the counterpart broken create
 392                         * has been turned into a rename-edit; or
 393                         * delete did not have a matching create to
 394                         * begin with.
 395                         */
 396                        if (DIFF_PAIR_BROKEN(p)) {
 397                                /* broken delete */
 398                                struct diff_rename_dst *dst =
 399                                        locate_rename_dst(p->one, 0);
 400                                if (dst && dst->pair)
 401                                        /* counterpart is now rename/copy */
 402                                        pair_to_free = p;
 403                        }
 404                        else {
 405                                for (j = 0; j < rename_dst_nr; j++) {
 406                                        if (!rename_dst[j].pair)
 407                                                continue;
 408                                        if (strcmp(rename_dst[j].pair->
 409                                                   one->path,
 410                                                   p->one->path))
 411                                                continue;
 412                                        break;
 413                                }
 414                                if (j < rename_dst_nr)
 415                                        /* this path remains */
 416                                        pair_to_free = p;
 417                        }
 418
 419                        if (pair_to_free)
 420                                ;
 421                        else
 422                                diff_q(&outq, p);
 423                }
 424                else if (!diff_unmodified_pair(p))
 425                        /* all the usual ones need to be kept */
 426                        diff_q(&outq, p);
 427                else
 428                        /* no need to keep unmodified pairs */
 429                        pair_to_free = p;
 430
 431                if (pair_to_free)
 432                        diff_free_filepair(pair_to_free);
 433        }
 434        diff_debug_queue("done copying original", &outq);
 435
 436        free(q->queue);
 437        *q = outq;
 438        diff_debug_queue("done collapsing", q);
 439
 440        /* We need to see which rename source really stays here;
 441         * earlier we only checked if the path is left in the result,
 442         * but even if a path remains in the result, if that is coming
 443         * from copying something else on top of it, then the original
 444         * source is lost and does not stay.
 445         */
 446        for (i = 0; i < q->nr; i++) {
 447                struct diff_filepair *p = q->queue[i];
 448                if (DIFF_PAIR_RENAME(p) && p->source_stays) {
 449                        /* If one appears as the target of a rename-copy,
 450                         * then mark p->source_stays = 0; otherwise
 451                         * leave it as is.
 452                         */
 453                        p->source_stays = compute_stays(q, p->one);
 454                }
 455        }
 456
 457        for (i = 0; i < rename_dst_nr; i++) {
 458                diff_free_filespec_data(rename_dst[i].two);
 459                free(rename_dst[i].two);
 460        }
 461
 462        free(rename_dst);
 463        rename_dst = NULL;
 464        rename_dst_nr = rename_dst_alloc = 0;
 465        free(rename_src);
 466        rename_src = NULL;
 467        rename_src_nr = rename_src_alloc = 0;
 468        return;
 469}