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