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 /* How similar are they? 174 * what percentage of material in dst are from source? 175 */ 176 if (dst->size < src_copied) 177 score = MAX_SCORE; 178 else if (!dst->size) 179 score = 0; /* should not happen */ 180 else 181 score = src_copied * MAX_SCORE / dst->size; 182 return score; 183} 184 185static void record_rename_pair(int dst_index, int src_index, int score) 186{ 187 struct diff_filespec *one, *two, *src, *dst; 188 struct diff_filepair *dp; 189 190 if (rename_dst[dst_index].pair) 191 die("internal error: dst already matched."); 192 193 src = rename_src[src_index].one; 194 one = alloc_filespec(src->path); 195 fill_filespec(one, src->sha1, src->mode); 196 197 dst = rename_dst[dst_index].two; 198 two = alloc_filespec(dst->path); 199 fill_filespec(two, dst->sha1, dst->mode); 200 201 dp = diff_queue(NULL, one, two); 202 dp->score = score; 203 dp->source_stays = rename_src[src_index].src_path_left; 204 rename_dst[dst_index].pair = dp; 205} 206 207/* 208 * We sort the rename similarity matrix with the score, in descending 209 * order (the most similar first). 210 */ 211static int score_compare(const void *a_, const void *b_) 212{ 213 const struct diff_score *a = a_, *b = b_; 214 return b->score - a->score; 215} 216 217static int compute_stays(struct diff_queue_struct *q, 218 struct diff_filespec *one) 219{ 220 int i; 221 for (i = 0; i < q->nr; i++) { 222 struct diff_filepair *p = q->queue[i]; 223 if (strcmp(one->path, p->two->path)) 224 continue; 225 if (DIFF_PAIR_RENAME(p)) { 226 return 0; /* something else is renamed into this */ 227 } 228 } 229 return 1; 230} 231 232void diffcore_rename(struct diff_options *options) 233{ 234 int detect_rename = options->detect_rename; 235 int minimum_score = options->rename_score; 236 int rename_limit = options->rename_limit; 237 struct diff_queue_struct *q = &diff_queued_diff; 238 struct diff_queue_struct outq; 239 struct diff_score *mx; 240 int i, j, rename_count; 241 int num_create, num_src, dst_cnt; 242 243 if (!minimum_score) 244 minimum_score = DEFAULT_RENAME_SCORE; 245 rename_count = 0; 246 247 for (i = 0; i < q->nr; i++) { 248 struct diff_filepair *p = q->queue[i]; 249 if (!DIFF_FILE_VALID(p->one)) 250 if (!DIFF_FILE_VALID(p->two)) 251 continue; /* unmerged */ 252 else 253 locate_rename_dst(p->two, 1); 254 else if (!DIFF_FILE_VALID(p->two)) { 255 /* If the source is a broken "delete", and 256 * they did not really want to get broken, 257 * that means the source actually stays. 258 */ 259 int stays = (p->broken_pair && !p->score); 260 register_rename_src(p->one, stays); 261 } 262 else if (detect_rename == DIFF_DETECT_COPY) 263 register_rename_src(p->one, 1); 264 } 265 if (rename_dst_nr == 0 || rename_src_nr == 0 || 266 (0 < rename_limit && rename_limit < rename_dst_nr)) 267 goto cleanup; /* nothing to do */ 268 269 /* We really want to cull the candidates list early 270 * with cheap tests in order to avoid doing deltas. 271 */ 272 for (i = 0; i < rename_dst_nr; i++) { 273 struct diff_filespec *two = rename_dst[i].two; 274 for (j = 0; j < rename_src_nr; j++) { 275 struct diff_filespec *one = rename_src[j].one; 276 if (!is_exact_match(one, two)) 277 continue; 278 record_rename_pair(i, j, MAX_SCORE); 279 rename_count++; 280 break; /* we are done with this entry */ 281 } 282 } 283 284 /* Have we run out the created file pool? If so we can avoid 285 * doing the delta matrix altogether. 286 */ 287 if (rename_count == rename_dst_nr) 288 goto cleanup; 289 290 if (minimum_score == MAX_SCORE) 291 goto cleanup; 292 293 num_create = (rename_dst_nr - rename_count); 294 num_src = rename_src_nr; 295 mx = xmalloc(sizeof(*mx) * num_create * num_src); 296 for (dst_cnt = i = 0; i < rename_dst_nr; i++) { 297 int base = dst_cnt * num_src; 298 struct diff_filespec *two = rename_dst[i].two; 299 if (rename_dst[i].pair) 300 continue; /* dealt with exact match already. */ 301 for (j = 0; j < rename_src_nr; j++) { 302 struct diff_filespec *one = rename_src[j].one; 303 struct diff_score *m = &mx[base+j]; 304 m->src = j; 305 m->dst = i; 306 m->score = estimate_similarity(one, two, 307 minimum_score); 308 } 309 dst_cnt++; 310 } 311 /* cost matrix sorted by most to least similar pair */ 312 qsort(mx, num_create * num_src, sizeof(*mx), score_compare); 313 for (i = 0; i < num_create * num_src; i++) { 314 struct diff_rename_dst *dst = &rename_dst[mx[i].dst]; 315 if (dst->pair) 316 continue; /* already done, either exact or fuzzy. */ 317 if (mx[i].score < minimum_score) 318 break; /* there is no more usable pair. */ 319 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score); 320 rename_count++; 321 } 322 free(mx); 323 324 cleanup: 325 /* At this point, we have found some renames and copies and they 326 * are recorded in rename_dst. The original list is still in *q. 327 */ 328 outq.queue = NULL; 329 outq.nr = outq.alloc = 0; 330 for (i = 0; i < q->nr; i++) { 331 struct diff_filepair *p = q->queue[i]; 332 struct diff_filepair *pair_to_free = NULL; 333 334 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) { 335 /* 336 * Creation 337 * 338 * We would output this create record if it has 339 * not been turned into a rename/copy already. 340 */ 341 struct diff_rename_dst *dst = 342 locate_rename_dst(p->two, 0); 343 if (dst && dst->pair) { 344 diff_q(&outq, dst->pair); 345 pair_to_free = p; 346 } 347 else 348 /* no matching rename/copy source, so 349 * record this as a creation. 350 */ 351 diff_q(&outq, p); 352 } 353 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) { 354 /* 355 * Deletion 356 * 357 * We would output this delete record if: 358 * 359 * (1) this is a broken delete and the counterpart 360 * broken create remains in the output; or 361 * (2) this is not a broken delete, and rename_dst 362 * does not have a rename/copy to move p->one->path 363 * out of existence. 364 * 365 * Otherwise, the counterpart broken create 366 * has been turned into a rename-edit; or 367 * delete did not have a matching create to 368 * begin with. 369 */ 370 if (DIFF_PAIR_BROKEN(p)) { 371 /* broken delete */ 372 struct diff_rename_dst *dst = 373 locate_rename_dst(p->one, 0); 374 if (dst && dst->pair) 375 /* counterpart is now rename/copy */ 376 pair_to_free = p; 377 } 378 else { 379 for (j = 0; j < rename_dst_nr; j++) { 380 if (!rename_dst[j].pair) 381 continue; 382 if (strcmp(rename_dst[j].pair-> 383 one->path, 384 p->one->path)) 385 continue; 386 break; 387 } 388 if (j < rename_dst_nr) 389 /* this path remains */ 390 pair_to_free = p; 391 } 392 393 if (pair_to_free) 394 ; 395 else 396 diff_q(&outq, p); 397 } 398 else if (!diff_unmodified_pair(p)) 399 /* all the usual ones need to be kept */ 400 diff_q(&outq, p); 401 else 402 /* no need to keep unmodified pairs */ 403 pair_to_free = p; 404 405 if (pair_to_free) 406 diff_free_filepair(pair_to_free); 407 } 408 diff_debug_queue("done copying original", &outq); 409 410 free(q->queue); 411 *q = outq; 412 diff_debug_queue("done collapsing", q); 413 414 /* We need to see which rename source really stays here; 415 * earlier we only checked if the path is left in the result, 416 * but even if a path remains in the result, if that is coming 417 * from copying something else on top of it, then the original 418 * source is lost and does not stay. 419 */ 420 for (i = 0; i < q->nr; i++) { 421 struct diff_filepair *p = q->queue[i]; 422 if (DIFF_PAIR_RENAME(p) && p->source_stays) { 423 /* If one appears as the target of a rename-copy, 424 * then mark p->source_stays = 0; otherwise 425 * leave it as is. 426 */ 427 p->source_stays = compute_stays(q, p->one); 428 } 429 } 430 431 for (i = 0; i < rename_dst_nr; i++) { 432 diff_free_filespec_data(rename_dst[i].two); 433 free(rename_dst[i].two); 434 } 435 436 free(rename_dst); 437 rename_dst = NULL; 438 rename_dst_nr = rename_dst_alloc = 0; 439 free(rename_src); 440 rename_src = NULL; 441 rename_src_nr = rename_src_alloc = 0; 442 return; 443}