| 1 | /* |
| 2 | * Generic reference iterator infrastructure. See refs-internal.h for |
| 3 | * documentation about the design and use of reference iterators. |
| 4 | */ |
| 5 | |
| 6 | #define DISABLE_SIGN_COMPARE_WARNINGS |
| 7 | |
| 8 | #include "git-compat-util.h" |
| 9 | #include "refs.h" |
| 10 | #include "refs/refs-internal.h" |
| 11 | #include "iterator.h" |
| 12 | |
| 13 | int ref_iterator_advance(struct ref_iterator *ref_iterator) |
| 14 | { |
| 15 | return ref_iterator->vtable->advance(ref_iterator); |
| 16 | } |
| 17 | |
| 18 | int ref_iterator_seek(struct ref_iterator *ref_iterator, const char *refname, |
| 19 | unsigned int flags) |
| 20 | { |
| 21 | return ref_iterator->vtable->seek(ref_iterator, refname, flags); |
| 22 | } |
| 23 | |
| 24 | void ref_iterator_free(struct ref_iterator *ref_iterator) |
| 25 | { |
| 26 | if (ref_iterator) { |
| 27 | ref_iterator->vtable->release(ref_iterator); |
| 28 | /* Help make use-after-free bugs fail quickly: */ |
| 29 | ref_iterator->vtable = NULL; |
| 30 | free(ref_iterator); |
| 31 | } |
| 32 | } |
| 33 | |
| 34 | void base_ref_iterator_init(struct ref_iterator *iter, |
| 35 | struct ref_iterator_vtable *vtable) |
| 36 | { |
| 37 | iter->vtable = vtable; |
| 38 | memset(&iter->ref, 0, sizeof(iter->ref)); |
| 39 | } |
| 40 | |
| 41 | struct empty_ref_iterator { |
| 42 | struct ref_iterator base; |
| 43 | }; |
| 44 | |
| 45 | static int empty_ref_iterator_advance(struct ref_iterator *ref_iterator UNUSED) |
| 46 | { |
| 47 | return ITER_DONE; |
| 48 | } |
| 49 | |
| 50 | static int empty_ref_iterator_seek(struct ref_iterator *ref_iterator UNUSED, |
| 51 | const char *refname UNUSED, |
| 52 | unsigned int flags UNUSED) |
| 53 | { |
| 54 | return 0; |
| 55 | } |
| 56 | |
| 57 | static void empty_ref_iterator_release(struct ref_iterator *ref_iterator UNUSED) |
| 58 | { |
| 59 | } |
| 60 | |
| 61 | static struct ref_iterator_vtable empty_ref_iterator_vtable = { |
| 62 | .advance = empty_ref_iterator_advance, |
| 63 | .seek = empty_ref_iterator_seek, |
| 64 | .release = empty_ref_iterator_release, |
| 65 | }; |
| 66 | |
| 67 | struct ref_iterator *empty_ref_iterator_begin(void) |
| 68 | { |
| 69 | struct empty_ref_iterator *iter = xcalloc(1, sizeof(*iter)); |
| 70 | struct ref_iterator *ref_iterator = &iter->base; |
| 71 | |
| 72 | base_ref_iterator_init(ref_iterator, &empty_ref_iterator_vtable); |
| 73 | return ref_iterator; |
| 74 | } |
| 75 | |
| 76 | int is_empty_ref_iterator(struct ref_iterator *ref_iterator) |
| 77 | { |
| 78 | return ref_iterator->vtable == &empty_ref_iterator_vtable; |
| 79 | } |
| 80 | |
| 81 | struct merge_ref_iterator { |
| 82 | struct ref_iterator base; |
| 83 | |
| 84 | struct ref_iterator *iter0, *iter0_owned; |
| 85 | struct ref_iterator *iter1, *iter1_owned; |
| 86 | |
| 87 | ref_iterator_select_fn *select; |
| 88 | void *cb_data; |
| 89 | |
| 90 | /* |
| 91 | * A pointer to iter0 or iter1 (whichever is supplying the |
| 92 | * current value), or NULL if advance has not yet been called. |
| 93 | */ |
| 94 | struct ref_iterator **current; |
| 95 | }; |
| 96 | |
| 97 | enum iterator_selection ref_iterator_select(struct ref_iterator *iter_worktree, |
| 98 | struct ref_iterator *iter_common, |
| 99 | void *cb_data UNUSED) |
| 100 | { |
| 101 | if (iter_worktree && !iter_common) { |
| 102 | /* |
| 103 | * Return the worktree ref if there are no more common refs. |
| 104 | */ |
| 105 | return ITER_SELECT_0; |
| 106 | } else if (iter_common) { |
| 107 | /* |
| 108 | * In case we have pending worktree and common refs we need to |
| 109 | * yield them based on their lexicographical order. Worktree |
| 110 | * refs that have the same name as common refs shadow the |
| 111 | * latter. |
| 112 | */ |
| 113 | if (iter_worktree) { |
| 114 | int cmp = strcmp(iter_worktree->ref.name, |
| 115 | iter_common->ref.name); |
| 116 | if (cmp < 0) |
| 117 | return ITER_SELECT_0; |
| 118 | else if (!cmp) |
| 119 | return ITER_SELECT_0_SKIP_1; |
| 120 | } |
| 121 | |
| 122 | /* |
| 123 | * We now know that the lexicographically-next ref is a common |
| 124 | * ref. When the common ref is a shared one we return it. |
| 125 | */ |
| 126 | if (parse_worktree_ref(iter_common->ref.name, NULL, NULL, |
| 127 | NULL) == REF_WORKTREE_SHARED) |
| 128 | return ITER_SELECT_1; |
| 129 | |
| 130 | /* |
| 131 | * Otherwise, if the common ref is a per-worktree ref we skip |
| 132 | * it because it would belong to the main worktree, not ours. |
| 133 | */ |
| 134 | return ITER_SKIP_1; |
| 135 | } else { |
| 136 | return ITER_DONE; |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | static int merge_ref_iterator_advance(struct ref_iterator *ref_iterator) |
| 141 | { |
| 142 | struct merge_ref_iterator *iter = |
| 143 | (struct merge_ref_iterator *)ref_iterator; |
| 144 | int ok; |
| 145 | |
| 146 | if (!iter->current) { |
| 147 | /* Initialize: advance both iterators to their first entries */ |
| 148 | if ((ok = ref_iterator_advance(iter->iter0)) != ITER_OK) { |
| 149 | iter->iter0 = NULL; |
| 150 | if (ok == ITER_ERROR) |
| 151 | goto error; |
| 152 | } |
| 153 | if ((ok = ref_iterator_advance(iter->iter1)) != ITER_OK) { |
| 154 | iter->iter1 = NULL; |
| 155 | if (ok == ITER_ERROR) |
| 156 | goto error; |
| 157 | } |
| 158 | } else { |
| 159 | /* |
| 160 | * Advance the current iterator past the just-used |
| 161 | * entry: |
| 162 | */ |
| 163 | if ((ok = ref_iterator_advance(*iter->current)) != ITER_OK) { |
| 164 | *iter->current = NULL; |
| 165 | if (ok == ITER_ERROR) |
| 166 | goto error; |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | /* Loop until we find an entry that we can yield. */ |
| 171 | while (1) { |
| 172 | struct ref_iterator **secondary; |
| 173 | enum iterator_selection selection = |
| 174 | iter->select(iter->iter0, iter->iter1, iter->cb_data); |
| 175 | |
| 176 | if (selection == ITER_SELECT_DONE) { |
| 177 | return ITER_DONE; |
| 178 | } else if (selection == ITER_SELECT_ERROR) { |
| 179 | return ITER_ERROR; |
| 180 | } |
| 181 | |
| 182 | if ((selection & ITER_CURRENT_SELECTION_MASK) == 0) { |
| 183 | iter->current = &iter->iter0; |
| 184 | secondary = &iter->iter1; |
| 185 | } else { |
| 186 | iter->current = &iter->iter1; |
| 187 | secondary = &iter->iter0; |
| 188 | } |
| 189 | |
| 190 | if (selection & ITER_SKIP_SECONDARY) { |
| 191 | if ((ok = ref_iterator_advance(*secondary)) != ITER_OK) { |
| 192 | *secondary = NULL; |
| 193 | if (ok == ITER_ERROR) |
| 194 | goto error; |
| 195 | } |
| 196 | } |
| 197 | |
| 198 | if (selection & ITER_YIELD_CURRENT) { |
| 199 | iter->base.ref = (*iter->current)->ref; |
| 200 | return ITER_OK; |
| 201 | } |
| 202 | } |
| 203 | |
| 204 | error: |
| 205 | return ITER_ERROR; |
| 206 | } |
| 207 | |
| 208 | static int merge_ref_iterator_seek(struct ref_iterator *ref_iterator, |
| 209 | const char *refname, unsigned int flags) |
| 210 | { |
| 211 | struct merge_ref_iterator *iter = |
| 212 | (struct merge_ref_iterator *)ref_iterator; |
| 213 | int ret; |
| 214 | |
| 215 | iter->current = NULL; |
| 216 | iter->iter0 = iter->iter0_owned; |
| 217 | iter->iter1 = iter->iter1_owned; |
| 218 | |
| 219 | ret = ref_iterator_seek(iter->iter0, refname, flags); |
| 220 | if (ret < 0) |
| 221 | return ret; |
| 222 | |
| 223 | ret = ref_iterator_seek(iter->iter1, refname, flags); |
| 224 | if (ret < 0) |
| 225 | return ret; |
| 226 | |
| 227 | return 0; |
| 228 | } |
| 229 | |
| 230 | static void merge_ref_iterator_release(struct ref_iterator *ref_iterator) |
| 231 | { |
| 232 | struct merge_ref_iterator *iter = |
| 233 | (struct merge_ref_iterator *)ref_iterator; |
| 234 | ref_iterator_free(iter->iter0_owned); |
| 235 | ref_iterator_free(iter->iter1_owned); |
| 236 | } |
| 237 | |
| 238 | static struct ref_iterator_vtable merge_ref_iterator_vtable = { |
| 239 | .advance = merge_ref_iterator_advance, |
| 240 | .seek = merge_ref_iterator_seek, |
| 241 | .release = merge_ref_iterator_release, |
| 242 | }; |
| 243 | |
| 244 | struct ref_iterator *merge_ref_iterator_begin( |
| 245 | struct ref_iterator *iter0, struct ref_iterator *iter1, |
| 246 | ref_iterator_select_fn *select, void *cb_data) |
| 247 | { |
| 248 | struct merge_ref_iterator *iter = xcalloc(1, sizeof(*iter)); |
| 249 | struct ref_iterator *ref_iterator = &iter->base; |
| 250 | |
| 251 | /* |
| 252 | * We can't do the same kind of is_empty_ref_iterator()-style |
| 253 | * optimization here as overlay_ref_iterator_begin() does, |
| 254 | * because we don't know the semantics of the select function. |
| 255 | * It might, for example, implement "intersect" by passing |
| 256 | * references through only if they exist in both iterators. |
| 257 | */ |
| 258 | |
| 259 | base_ref_iterator_init(ref_iterator, &merge_ref_iterator_vtable); |
| 260 | iter->iter0 = iter->iter0_owned = iter0; |
| 261 | iter->iter1 = iter->iter1_owned = iter1; |
| 262 | iter->select = select; |
| 263 | iter->cb_data = cb_data; |
| 264 | iter->current = NULL; |
| 265 | return ref_iterator; |
| 266 | } |
| 267 | |
| 268 | /* |
| 269 | * A ref_iterator_select_fn that overlays the items from front on top |
| 270 | * of those from back (like loose refs over packed refs). See |
| 271 | * overlay_ref_iterator_begin(). |
| 272 | */ |
| 273 | static enum iterator_selection overlay_iterator_select( |
| 274 | struct ref_iterator *front, struct ref_iterator *back, |
| 275 | void *cb_data UNUSED) |
| 276 | { |
| 277 | int cmp; |
| 278 | |
| 279 | if (!back) |
| 280 | return front ? ITER_SELECT_0 : ITER_SELECT_DONE; |
| 281 | else if (!front) |
| 282 | return ITER_SELECT_1; |
| 283 | |
| 284 | cmp = strcmp(front->ref.name, back->ref.name); |
| 285 | |
| 286 | if (cmp < 0) |
| 287 | return ITER_SELECT_0; |
| 288 | else if (cmp > 0) |
| 289 | return ITER_SELECT_1; |
| 290 | else |
| 291 | return ITER_SELECT_0_SKIP_1; |
| 292 | } |
| 293 | |
| 294 | struct ref_iterator *overlay_ref_iterator_begin( |
| 295 | struct ref_iterator *front, struct ref_iterator *back) |
| 296 | { |
| 297 | /* |
| 298 | * Optimization: if one of the iterators is empty, return the |
| 299 | * other one rather than incurring the overhead of wrapping |
| 300 | * them. |
| 301 | */ |
| 302 | if (is_empty_ref_iterator(front)) { |
| 303 | ref_iterator_free(front); |
| 304 | return back; |
| 305 | } else if (is_empty_ref_iterator(back)) { |
| 306 | ref_iterator_free(back); |
| 307 | return front; |
| 308 | } |
| 309 | |
| 310 | return merge_ref_iterator_begin(front, back, overlay_iterator_select, NULL); |
| 311 | } |
| 312 | |
| 313 | struct prefix_ref_iterator { |
| 314 | struct ref_iterator base; |
| 315 | |
| 316 | struct ref_iterator *iter0; |
| 317 | char *prefix; |
| 318 | int trim; |
| 319 | }; |
| 320 | |
| 321 | /* Return -1, 0, 1 if refname is before, inside, or after the prefix. */ |
| 322 | static int compare_prefix(const char *refname, const char *prefix) |
| 323 | { |
| 324 | while (*prefix) { |
| 325 | if (*refname != *prefix) |
| 326 | return ((unsigned char)*refname < (unsigned char)*prefix) ? -1 : +1; |
| 327 | |
| 328 | refname++; |
| 329 | prefix++; |
| 330 | } |
| 331 | |
| 332 | return 0; |
| 333 | } |
| 334 | |
| 335 | static int prefix_ref_iterator_advance(struct ref_iterator *ref_iterator) |
| 336 | { |
| 337 | struct prefix_ref_iterator *iter = |
| 338 | (struct prefix_ref_iterator *)ref_iterator; |
| 339 | int ok; |
| 340 | |
| 341 | while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) { |
| 342 | int cmp = compare_prefix(iter->iter0->ref.name, iter->prefix); |
| 343 | if (cmp < 0) |
| 344 | continue; |
| 345 | /* |
| 346 | * As the source iterator is ordered, we |
| 347 | * can stop the iteration as soon as we see a |
| 348 | * refname that comes after the prefix: |
| 349 | */ |
| 350 | if (cmp > 0) |
| 351 | return ITER_DONE; |
| 352 | |
| 353 | iter->base.ref = iter->iter0->ref; |
| 354 | |
| 355 | if (iter->trim) { |
| 356 | /* |
| 357 | * It is nonsense to trim off characters that |
| 358 | * you haven't already checked for via a |
| 359 | * prefix check, whether via this |
| 360 | * `prefix_ref_iterator` or upstream in |
| 361 | * `iter0`). So if there wouldn't be at least |
| 362 | * one character left in the refname after |
| 363 | * trimming, report it as a bug: |
| 364 | */ |
| 365 | if (strlen(iter->base.ref.name) <= iter->trim) |
| 366 | BUG("attempt to trim too many characters"); |
| 367 | iter->base.ref.name += iter->trim; |
| 368 | } |
| 369 | |
| 370 | return ITER_OK; |
| 371 | } |
| 372 | |
| 373 | return ok; |
| 374 | } |
| 375 | |
| 376 | static int prefix_ref_iterator_seek(struct ref_iterator *ref_iterator, |
| 377 | const char *refname, unsigned int flags) |
| 378 | { |
| 379 | struct prefix_ref_iterator *iter = |
| 380 | (struct prefix_ref_iterator *)ref_iterator; |
| 381 | |
| 382 | if (flags & REF_ITERATOR_SEEK_SET_PREFIX) { |
| 383 | free(iter->prefix); |
| 384 | iter->prefix = xstrdup_or_null(refname); |
| 385 | } |
| 386 | return ref_iterator_seek(iter->iter0, refname, flags); |
| 387 | } |
| 388 | |
| 389 | static void prefix_ref_iterator_release(struct ref_iterator *ref_iterator) |
| 390 | { |
| 391 | struct prefix_ref_iterator *iter = |
| 392 | (struct prefix_ref_iterator *)ref_iterator; |
| 393 | ref_iterator_free(iter->iter0); |
| 394 | free(iter->prefix); |
| 395 | } |
| 396 | |
| 397 | static struct ref_iterator_vtable prefix_ref_iterator_vtable = { |
| 398 | .advance = prefix_ref_iterator_advance, |
| 399 | .seek = prefix_ref_iterator_seek, |
| 400 | .release = prefix_ref_iterator_release, |
| 401 | }; |
| 402 | |
| 403 | struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0, |
| 404 | const char *prefix, |
| 405 | int trim) |
| 406 | { |
| 407 | struct prefix_ref_iterator *iter; |
| 408 | struct ref_iterator *ref_iterator; |
| 409 | |
| 410 | if (!*prefix && !trim) |
| 411 | return iter0; /* optimization: no need to wrap iterator */ |
| 412 | |
| 413 | CALLOC_ARRAY(iter, 1); |
| 414 | ref_iterator = &iter->base; |
| 415 | |
| 416 | base_ref_iterator_init(ref_iterator, &prefix_ref_iterator_vtable); |
| 417 | |
| 418 | iter->iter0 = iter0; |
| 419 | iter->prefix = xstrdup(prefix); |
| 420 | iter->trim = trim; |
| 421 | |
| 422 | return ref_iterator; |
| 423 | } |
| 424 | |
| 425 | int do_for_each_ref_iterator(struct ref_iterator *iter, |
| 426 | refs_for_each_cb fn, void *cb_data) |
| 427 | { |
| 428 | int retval = 0, ok; |
| 429 | |
| 430 | while ((ok = ref_iterator_advance(iter)) == ITER_OK) { |
| 431 | retval = fn(&iter->ref, cb_data); |
| 432 | if (retval) |
| 433 | goto out; |
| 434 | } |
| 435 | |
| 436 | out: |
| 437 | if (ok == ITER_ERROR) |
| 438 | retval = -1; |
| 439 | ref_iterator_free(iter); |
| 440 | return retval; |
| 441 | } |