1/* 2 * Copyright (C) 2005 Junio C Hamano 3 */ 4#include "cache.h" 5#include "diff.h" 6#include "diffcore.h" 7#include "delta.h" 8#include "count-delta.h" 9 10/* Table of rename/copy destinations */ 11 12static struct diff_rename_dst { 13 struct diff_filespec *two; 14 struct diff_filepair *pair; 15} *rename_dst; 16static int rename_dst_nr, rename_dst_alloc; 17 18static 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 = two; 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 src_stays : 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_stays) 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].src_stays = src_stays; 94 return &(rename_src[first]); 95} 96 97static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst) 98{ 99 if (src->sha1_valid && dst->sha1_valid && 100 !memcmp(src->sha1, dst->sha1, 20)) 101 return 1; 102 if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1)) 103 return 0; 104 if (src->size != dst->size) 105 return 0; 106 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0)) 107 return 0; 108 if (src->size == dst->size && 109 !memcmp(src->data, dst->data, src->size)) 110 return 1; 111 return 0; 112} 113 114struct diff_score { 115 int src; /* index in rename_src */ 116 int dst; /* index in rename_dst */ 117 int score; 118}; 119 120static 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 void *delta; 138 unsigned long delta_size, base_size, src_copied, literal_added; 139 unsigned long delta_limit; 140 int score; 141 142 /* We deal only with regular files. Symlink renames are handled 143 * only when they are exact matches --- in other words, no edits 144 * after renaming. 145 */ 146 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode)) 147 return 0; 148 149 delta_size = ((src->size < dst->size) ? 150 (dst->size - src->size) : (src->size - dst->size)); 151 base_size = ((src->size < dst->size) ? src->size : dst->size); 152 153 /* We would not consider edits that change the file size so 154 * drastically. delta_size must be smaller than 155 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size). 156 * 157 * Note that base_size == 0 case is handled here already 158 * and the final score computation below would not have a 159 * divide-by-zero issue. 160 */ 161 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE) 162 return 0; 163 164 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0)) 165 return 0; /* error but caught downstream */ 166 167 delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE; 168 delta = diff_delta(src->data, src->size, 169 dst->data, dst->size, 170 &delta_size, delta_limit); 171 if (!delta) 172 /* If delta_limit is exceeded, we have too much differences */ 173 return 0; 174 175 /* A delta that has a lot of literal additions would have 176 * big delta_size no matter what else it does. 177 */ 178 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE) 179 return 0; 180 181 /* Estimate the edit size by interpreting delta. */ 182 if (count_delta(delta, delta_size, &src_copied, &literal_added)) { 183 free(delta); 184 return 0; 185 } 186 free(delta); 187 188 /* Extent of damage */ 189 if (src->size + literal_added < src_copied) 190 delta_size = 0; 191 else 192 delta_size = (src->size - src_copied) + literal_added; 193 194 /* 195 * Now we will give some score to it. 100% edit gets 0 points 196 * and 0% edit gets MAX_SCORE points. 197 */ 198 score = MAX_SCORE - (MAX_SCORE * delta_size / base_size); 199 if (score < 0) return 0; 200 if (MAX_SCORE < score) return MAX_SCORE; 201 return score; 202} 203 204static void record_rename_pair(struct diff_queue_struct *renq, 205 int dst_index, int src_index, int score) 206{ 207 struct diff_filespec *one, *two, *src, *dst; 208 struct diff_filepair *dp; 209 210 if (rename_dst[dst_index].pair) 211 die("internal error: dst already matched."); 212 213 src = rename_src[src_index].one; 214 one = alloc_filespec(src->path); 215 fill_filespec(one, src->sha1, src->mode); 216 217 dst = rename_dst[dst_index].two; 218 two = alloc_filespec(dst->path); 219 fill_filespec(two, dst->sha1, dst->mode); 220 221 dp = diff_queue(renq, one, two); 222 dp->score = score; 223 dp->source_stays = rename_src[src_index].src_stays; 224 rename_dst[dst_index].pair = dp; 225} 226 227/* 228 * We sort the rename similarity matrix with the score, in descending 229 * order (the most similar first). 230 */ 231static int score_compare(const void *a_, const void *b_) 232{ 233 const struct diff_score *a = a_, *b = b_; 234 return b->score - a->score; 235} 236 237void diffcore_rename(int detect_rename, int minimum_score) 238{ 239 struct diff_queue_struct *q = &diff_queued_diff; 240 struct diff_queue_struct renq, outq; 241 struct diff_score *mx; 242 int i, j; 243 int num_create, num_src, dst_cnt; 244 245 if (!minimum_score) 246 minimum_score = DEFAULT_RENAME_SCORE; 247 renq.queue = NULL; 248 renq.nr = renq.alloc = 0; 249 250 for (i = 0; i < q->nr; i++) { 251 struct diff_filepair *p = q->queue[i]; 252 if (!DIFF_FILE_VALID(p->one)) 253 if (!DIFF_FILE_VALID(p->two)) 254 continue; /* unmerged */ 255 else 256 locate_rename_dst(p->two, 1); 257 else if (!DIFF_FILE_VALID(p->two)) { 258 /* If the source is a broken "delete", and 259 * they did not really want to get broken, 260 * that means the source actually stays. 261 */ 262 int stays = (p->broken_pair && !p->score); 263 register_rename_src(p->one, stays); 264 } 265 else if (detect_rename == DIFF_DETECT_COPY) 266 register_rename_src(p->one, 1); 267 } 268 if (rename_dst_nr == 0) 269 goto cleanup; /* nothing to do */ 270 271 /* We really want to cull the candidates list early 272 * with cheap tests in order to avoid doing deltas. 273 */ 274 for (i = 0; i < rename_dst_nr; i++) { 275 struct diff_filespec *two = rename_dst[i].two; 276 for (j = 0; j < rename_src_nr; j++) { 277 struct diff_filespec *one = rename_src[j].one; 278 if (!is_exact_match(one, two)) 279 continue; 280 record_rename_pair(&renq, i, j, MAX_SCORE); 281 break; /* we are done with this entry */ 282 } 283 } 284 diff_debug_queue("done detecting exact", &renq); 285 286 /* Have we run out the created file pool? If so we can avoid 287 * doing the delta matrix altogether. 288 */ 289 if (renq.nr == rename_dst_nr) 290 goto cleanup; 291 292 num_create = (rename_dst_nr - renq.nr); 293 num_src = rename_src_nr; 294 mx = xmalloc(sizeof(*mx) * num_create * num_src); 295 for (dst_cnt = i = 0; i < rename_dst_nr; i++) { 296 int base = dst_cnt * num_src; 297 struct diff_filespec *two = rename_dst[i].two; 298 if (rename_dst[i].pair) 299 continue; /* dealt with exact match already. */ 300 for (j = 0; j < rename_src_nr; j++) { 301 struct diff_filespec *one = rename_src[j].one; 302 struct diff_score *m = &mx[base+j]; 303 m->src = j; 304 m->dst = i; 305 m->score = estimate_similarity(one, two, 306 minimum_score); 307 } 308 dst_cnt++; 309 } 310 /* cost matrix sorted by most to least similar pair */ 311 qsort(mx, num_create * num_src, sizeof(*mx), score_compare); 312 for (i = 0; i < num_create * num_src; i++) { 313 struct diff_rename_dst *dst = &rename_dst[mx[i].dst]; 314 if (dst->pair) 315 continue; /* already done, either exact or fuzzy. */ 316 if (mx[i].score < minimum_score) 317 break; /* there is no more usable pair. */ 318 record_rename_pair(&renq, mx[i].dst, mx[i].src, mx[i].score); 319 } 320 free(mx); 321 diff_debug_queue("done detecting fuzzy", &renq); 322 323 cleanup: 324 /* At this point, we have found some renames and copies and they 325 * are kept in renq. The original list is still in *q. 326 */ 327 outq.queue = NULL; 328 outq.nr = outq.alloc = 0; 329 for (i = 0; i < q->nr; i++) { 330 struct diff_filepair *p = q->queue[i]; 331 struct diff_filepair *pair_to_free = NULL; 332 333 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) { 334 /* 335 * Creation 336 * 337 * We would output this create record if it has 338 * not been turned into a rename/copy already. 339 */ 340 struct diff_rename_dst *dst = 341 locate_rename_dst(p->two, 0); 342 if (dst && dst->pair) { 343 diff_q(&outq, dst->pair); 344 pair_to_free = p; 345 } 346 else 347 /* no matching rename/copy source, so 348 * record this as a creation. 349 */ 350 diff_q(&outq, p); 351 } 352 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) { 353 /* 354 * Deletion 355 * 356 * We would output this delete record if: 357 * 358 * (1) this is a broken delete and the counterpart 359 * broken create remains in the output; or 360 * (2) this is not a broken delete, and renq does 361 * not have a rename/copy to move p->one->path 362 * out. 363 * 364 * Otherwise, the counterpart broken create 365 * has been turned into a rename-edit; or 366 * delete did not have a matching create to 367 * begin with. 368 */ 369 if (DIFF_PAIR_BROKEN(p)) { 370 /* broken delete */ 371 struct diff_rename_dst *dst = 372 locate_rename_dst(p->one, 0); 373 if (dst && dst->pair) 374 /* counterpart is now rename/copy */ 375 pair_to_free = p; 376 } 377 else { 378 for (j = 0; j < renq.nr; j++) 379 if (!strcmp(renq.queue[j]->one->path, 380 p->one->path)) 381 break; 382 if (j < renq.nr) 383 /* this path remains */ 384 pair_to_free = p; 385 } 386 387 if (pair_to_free) 388 ; 389 else 390 diff_q(&outq, p); 391 } 392 else if (!diff_unmodified_pair(p)) 393 /* all the usual ones need to be kept */ 394 diff_q(&outq, p); 395 else 396 /* no need to keep unmodified pairs */ 397 pair_to_free = p; 398 399 if (pair_to_free) 400 diff_free_filepair(pair_to_free); 401 } 402 diff_debug_queue("done copying original", &outq); 403 404 free(renq.queue); 405 free(q->queue); 406 *q = outq; 407 diff_debug_queue("done collapsing", q); 408 409 free(rename_dst); 410 rename_dst = NULL; 411 rename_dst_nr = rename_dst_alloc = 0; 412 free(rename_src); 413 rename_src = NULL; 414 rename_src_nr = rename_src_alloc = 0; 415 return; 416}