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 src_path_left : 1; 58} *rename_src; 59static int rename_src_nr, rename_src_alloc; 60 61static struct diff_rename_src *register_rename_src(struct diff_filespec *one, 62 int src_path_left) 63{ 64 int first, last; 65 66 first = 0; 67 last = rename_src_nr; 68 while (last > first) { 69 int next = (last + first) >> 1; 70 struct diff_rename_src *src = &(rename_src[next]); 71 int cmp = strcmp(one->path, src->one->path); 72 if (!cmp) 73 return src; 74 if (cmp < 0) { 75 last = next; 76 continue; 77 } 78 first = next+1; 79 } 80 81 /* insert to make it at "first" */ 82 if (rename_src_alloc <= rename_src_nr) { 83 rename_src_alloc = alloc_nr(rename_src_alloc); 84 rename_src = xrealloc(rename_src, 85 rename_src_alloc * sizeof(*rename_src)); 86 } 87 rename_src_nr++; 88 if (first < rename_src_nr) 89 memmove(rename_src + first + 1, rename_src + first, 90 (rename_src_nr - first - 1) * sizeof(*rename_src)); 91 rename_src[first].one = one; 92 rename_src[first].src_path_left = src_path_left; 93 return &(rename_src[first]); 94} 95 96static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst) 97{ 98 if (src->sha1_valid && dst->sha1_valid && 99 !memcmp(src->sha1, dst->sha1, 20)) 100 return 1; 101 if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1)) 102 return 0; 103 if (src->size != dst->size) 104 return 0; 105 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0)) 106 return 0; 107 if (src->size == dst->size && 108 !memcmp(src->data, dst->data, src->size)) 109 return 1; 110 return 0; 111} 112 113struct diff_score { 114 int src; /* index in rename_src */ 115 int dst; /* index in rename_dst */ 116 int 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 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 delta_size = ((src->size < dst->size) ? 148 (dst->size - src->size) : (src->size - dst->size)); 149 base_size = ((src->size < dst->size) ? src->size : dst->size); 150 151 /* We would not consider edits that change the file size so 152 * drastically. delta_size must be smaller than 153 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size). 154 * 155 * Note that base_size == 0 case is handled here already 156 * and the final score computation below would not have a 157 * divide-by-zero issue. 158 */ 159 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE) 160 return 0; 161 162 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0)) 163 return 0; /* error but caught downstream */ 164 165 166 delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE; 167 if (diffcore_count_changes(src->data, src->size, 168 dst->data, dst->size, 169 delta_limit, 170 &src_copied, &literal_added)) 171 return 0; 172 173 /* Extent of damage */ 174 if (src->size + literal_added < src_copied) 175 delta_size = 0; 176 else 177 delta_size = (src->size - src_copied) + literal_added; 178 179 /* 180 * Now we will give some score to it. 100% edit gets 0 points 181 * and 0% edit gets MAX_SCORE points. 182 */ 183 score = MAX_SCORE - (MAX_SCORE * delta_size / base_size); 184 if (score < 0) return 0; 185 if (MAX_SCORE < score) return MAX_SCORE; 186 return score; 187} 188 189static void record_rename_pair(int dst_index, int src_index, int score) 190{ 191 struct diff_filespec *one, *two, *src, *dst; 192 struct diff_filepair *dp; 193 194 if (rename_dst[dst_index].pair) 195 die("internal error: dst already matched."); 196 197 src = rename_src[src_index].one; 198 one = alloc_filespec(src->path); 199 fill_filespec(one, src->sha1, src->mode); 200 201 dst = rename_dst[dst_index].two; 202 two = alloc_filespec(dst->path); 203 fill_filespec(two, dst->sha1, dst->mode); 204 205 dp = diff_queue(NULL, one, two); 206 dp->score = score; 207 dp->source_stays = rename_src[src_index].src_path_left; 208 rename_dst[dst_index].pair = dp; 209} 210 211/* 212 * We sort the rename similarity matrix with the score, in descending 213 * order (the most similar first). 214 */ 215static int score_compare(const void *a_, const void *b_) 216{ 217 const struct diff_score *a = a_, *b = b_; 218 return b->score - a->score; 219} 220 221static int compute_stays(struct diff_queue_struct *q, 222 struct diff_filespec *one) 223{ 224 int i; 225 for (i = 0; i < q->nr; i++) { 226 struct diff_filepair *p = q->queue[i]; 227 if (strcmp(one->path, p->two->path)) 228 continue; 229 if (DIFF_PAIR_RENAME(p)) { 230 return 0; /* something else is renamed into this */ 231 } 232 } 233 return 1; 234} 235 236void diffcore_rename(struct diff_options *options) 237{ 238 int detect_rename = options->detect_rename; 239 int minimum_score = options->rename_score; 240 int rename_limit = options->rename_limit; 241 struct diff_queue_struct *q = &diff_queued_diff; 242 struct diff_queue_struct outq; 243 struct diff_score *mx; 244 int i, j, rename_count; 245 int num_create, num_src, dst_cnt; 246 247 if (!minimum_score) 248 minimum_score = DEFAULT_RENAME_SCORE; 249 rename_count = 0; 250 251 for (i = 0; i < q->nr; i++) { 252 struct diff_filepair *p = q->queue[i]; 253 if (!DIFF_FILE_VALID(p->one)) 254 if (!DIFF_FILE_VALID(p->two)) 255 continue; /* unmerged */ 256 else 257 locate_rename_dst(p->two, 1); 258 else if (!DIFF_FILE_VALID(p->two)) { 259 /* If the source is a broken "delete", and 260 * they did not really want to get broken, 261 * that means the source actually stays. 262 */ 263 int stays = (p->broken_pair && !p->score); 264 register_rename_src(p->one, stays); 265 } 266 else if (detect_rename == DIFF_DETECT_COPY) 267 register_rename_src(p->one, 1); 268 } 269 if (rename_dst_nr == 0 || rename_src_nr == 0 || 270 (0 < rename_limit && rename_limit < rename_dst_nr)) 271 goto cleanup; /* nothing to do */ 272 273 /* We really want to cull the candidates list early 274 * with cheap tests in order to avoid doing deltas. 275 */ 276 for (i = 0; i < rename_dst_nr; i++) { 277 struct diff_filespec *two = rename_dst[i].two; 278 for (j = 0; j < rename_src_nr; j++) { 279 struct diff_filespec *one = rename_src[j].one; 280 if (!is_exact_match(one, two)) 281 continue; 282 record_rename_pair(i, j, MAX_SCORE); 283 rename_count++; 284 break; /* we are done with this entry */ 285 } 286 } 287 288 /* Have we run out the created file pool? If so we can avoid 289 * doing the delta matrix altogether. 290 */ 291 if (rename_count == rename_dst_nr) 292 goto cleanup; 293 294 if (minimum_score == MAX_SCORE) 295 goto cleanup; 296 297 num_create = (rename_dst_nr - rename_count); 298 num_src = rename_src_nr; 299 mx = xmalloc(sizeof(*mx) * num_create * num_src); 300 for (dst_cnt = i = 0; i < rename_dst_nr; i++) { 301 int base = dst_cnt * num_src; 302 struct diff_filespec *two = rename_dst[i].two; 303 if (rename_dst[i].pair) 304 continue; /* dealt with exact match already. */ 305 for (j = 0; j < rename_src_nr; j++) { 306 struct diff_filespec *one = rename_src[j].one; 307 struct diff_score *m = &mx[base+j]; 308 m->src = j; 309 m->dst = i; 310 m->score = estimate_similarity(one, two, 311 minimum_score); 312 } 313 dst_cnt++; 314 } 315 /* cost matrix sorted by most to least similar pair */ 316 qsort(mx, num_create * num_src, sizeof(*mx), score_compare); 317 for (i = 0; i < num_create * num_src; i++) { 318 struct diff_rename_dst *dst = &rename_dst[mx[i].dst]; 319 if (dst->pair) 320 continue; /* already done, either exact or fuzzy. */ 321 if (mx[i].score < minimum_score) 322 break; /* there is no more usable pair. */ 323 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score); 324 rename_count++; 325 } 326 free(mx); 327 328 cleanup: 329 /* At this point, we have found some renames and copies and they 330 * are recorded in rename_dst. The original list is still in *q. 331 */ 332 outq.queue = NULL; 333 outq.nr = outq.alloc = 0; 334 for (i = 0; i < q->nr; i++) { 335 struct diff_filepair *p = q->queue[i]; 336 struct diff_filepair *pair_to_free = NULL; 337 338 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) { 339 /* 340 * Creation 341 * 342 * We would output this create record if it has 343 * not been turned into a rename/copy already. 344 */ 345 struct diff_rename_dst *dst = 346 locate_rename_dst(p->two, 0); 347 if (dst && dst->pair) { 348 diff_q(&outq, dst->pair); 349 pair_to_free = p; 350 } 351 else 352 /* no matching rename/copy source, so 353 * record this as a creation. 354 */ 355 diff_q(&outq, p); 356 } 357 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) { 358 /* 359 * Deletion 360 * 361 * We would output this delete record if: 362 * 363 * (1) this is a broken delete and the counterpart 364 * broken create remains in the output; or 365 * (2) this is not a broken delete, and rename_dst 366 * does not have a rename/copy to move p->one->path 367 * out of existence. 368 * 369 * Otherwise, the counterpart broken create 370 * has been turned into a rename-edit; or 371 * delete did not have a matching create to 372 * begin with. 373 */ 374 if (DIFF_PAIR_BROKEN(p)) { 375 /* broken delete */ 376 struct diff_rename_dst *dst = 377 locate_rename_dst(p->one, 0); 378 if (dst && dst->pair) 379 /* counterpart is now rename/copy */ 380 pair_to_free = p; 381 } 382 else { 383 for (j = 0; j < rename_dst_nr; j++) { 384 if (!rename_dst[j].pair) 385 continue; 386 if (strcmp(rename_dst[j].pair-> 387 one->path, 388 p->one->path)) 389 continue; 390 break; 391 } 392 if (j < rename_dst_nr) 393 /* this path remains */ 394 pair_to_free = p; 395 } 396 397 if (pair_to_free) 398 ; 399 else 400 diff_q(&outq, p); 401 } 402 else if (!diff_unmodified_pair(p)) 403 /* all the usual ones need to be kept */ 404 diff_q(&outq, p); 405 else 406 /* no need to keep unmodified pairs */ 407 pair_to_free = p; 408 409 if (pair_to_free) 410 diff_free_filepair(pair_to_free); 411 } 412 diff_debug_queue("done copying original", &outq); 413 414 free(q->queue); 415 *q = outq; 416 diff_debug_queue("done collapsing", q); 417 418 /* We need to see which rename source really stays here; 419 * earlier we only checked if the path is left in the result, 420 * but even if a path remains in the result, if that is coming 421 * from copying something else on top of it, then the original 422 * source is lost and does not stay. 423 */ 424 for (i = 0; i < q->nr; i++) { 425 struct diff_filepair *p = q->queue[i]; 426 if (DIFF_PAIR_RENAME(p) && p->source_stays) { 427 /* If one appears as the target of a rename-copy, 428 * then mark p->source_stays = 0; otherwise 429 * leave it as is. 430 */ 431 p->source_stays = compute_stays(q, p->one); 432 } 433 } 434 435 for (i = 0; i < rename_dst_nr; i++) { 436 diff_free_filespec_data(rename_dst[i].two); 437 free(rename_dst[i].two); 438 } 439 440 free(rename_dst); 441 rename_dst = NULL; 442 rename_dst_nr = rename_dst_alloc = 0; 443 free(rename_src); 444 rename_src = NULL; 445 rename_src_nr = rename_src_alloc = 0; 446 return; 447}