refs/packed-backend.c

   1 #include "../cache.h"
   2 #include "../refs.h"
   3 #include "refs-internal.h"
   4 #include "ref-cache.h"
   5 #include "packed-backend.h"
   6 #include "../iterator.h"
   7 #include "../lockfile.h"
   8
   9 struct packed_ref_cache {
  10         struct ref_cache *cache;
  11
  12         /*
  13          * Count of references to the data structure in this instance,
  14          * including the pointer from files_ref_store::packed if any.
  15          * The data will not be freed as long as the reference count
  16          * is nonzero.
  17          */
  18         unsigned int referrers;
  19
  20         /* The metadata from when this packed-refs cache was read */
  21         struct stat_validity validity;
  22 };
  23
  24 /*
  25  * Increment the reference count of *packed_refs.
  26  */
  27 static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
  28 {
  29         packed_refs->referrers++;
  30 }
  31
  32 /*
  33  * Decrease the reference count of *packed_refs.  If it goes to zero,
  34  * free *packed_refs and return true; otherwise return false.
  35  */
  36 static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
  37 {
  38         if (!--packed_refs->referrers) {
  39                 free_ref_cache(packed_refs->cache);
  40                 stat_validity_clear(&packed_refs->validity);
  41                 free(packed_refs);
  42                 return 1;
  43         } else {
  44                 return 0;
  45         }
  46 }
  47
  48 /*
  49  * A container for `packed-refs`-related data. It is not (yet) a
  50  * `ref_store`.
  51  */
  52 struct packed_ref_store {
  53         struct ref_store base;
  54
  55         unsigned int store_flags;
  56
  57         /* The path of the "packed-refs" file: */
  58         char *path;
  59
  60         /*
  61          * A cache of the values read from the `packed-refs` file, if
  62          * it might still be current; otherwise, NULL.
  63          */
  64         struct packed_ref_cache *cache;
  65
  66         /*
  67          * Lock used for the "packed-refs" file. Note that this (and
  68          * thus the enclosing `packed_ref_store`) must not be freed.
  69          */
  70         struct lock_file lock;
  71
  72         /*
  73          * Temporary file used when rewriting new contents to the
  74          * "packed-refs" file. Note that this (and thus the enclosing
  75          * `packed_ref_store`) must not be freed.
  76          */
  77         struct tempfile tempfile;
  78 };
  79
  80 struct ref_store *packed_ref_store_create(const char *path,
  81                                           unsigned int store_flags)
  82 {
  83         struct packed_ref_store *refs = xcalloc(1, sizeof(*refs));
  84         struct ref_store *ref_store = (struct ref_store *)refs;
  85
  86         base_ref_store_init(ref_store, &refs_be_packed);
  87         refs->store_flags = store_flags;
  88
  89         refs->path = xstrdup(path);
  90         return ref_store;
  91 }
  92
  93 /*
  94  * Die if refs is not the main ref store. caller is used in any
  95  * necessary error messages.
  96  */
  97 static void packed_assert_main_repository(struct packed_ref_store *refs,
  98                                           const char *caller)
  99 {
 100         if (refs->store_flags & REF_STORE_MAIN)
 101                 return;
 102
 103         die("BUG: operation %s only allowed for main ref store", caller);
 104 }
 105
 106 /*
 107  * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
 108  * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
 109  * support at least the flags specified in `required_flags`. `caller`
 110  * is used in any necessary error messages.
 111  */
 112 static struct packed_ref_store *packed_downcast(struct ref_store *ref_store,
 113                                                 unsigned int required_flags,
 114                                                 const char *caller)
 115 {
 116         struct packed_ref_store *refs;
 117
 118         if (ref_store->be != &refs_be_packed)
 119                 die("BUG: ref_store is type \"%s\" not \"packed\" in %s",
 120                     ref_store->be->name, caller);
 121
 122         refs = (struct packed_ref_store *)ref_store;
 123
 124         if ((refs->store_flags & required_flags) != required_flags)
 125                 die("BUG: unallowed operation (%s), requires %x, has %x\n",
 126                     caller, required_flags, refs->store_flags);
 127
 128         return refs;
 129 }
 130
 131 static void clear_packed_ref_cache(struct packed_ref_store *refs)
 132 {
 133         if (refs->cache) {
 134                 struct packed_ref_cache *cache = refs->cache;
 135
 136                 refs->cache = NULL;
 137                 release_packed_ref_cache(cache);
 138         }
 139 }
 140
 141 /* The length of a peeled reference line in packed-refs, including EOL: */
 142 #define PEELED_LINE_LENGTH 42
 143
 144 /*
 145  * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
 146  * Return a pointer to the refname within the line (null-terminated),
 147  * or NULL if there was a problem.
 148  */
 149 static const char *parse_ref_line(struct strbuf *line, struct object_id *oid)
 150 {
 151         const char *ref;
 152
 153         if (parse_oid_hex(line->buf, oid, &ref) < 0)
 154                 return NULL;
 155         if (!isspace(*ref++))
 156                 return NULL;
 157
 158         if (isspace(*ref))
 159                 return NULL;
 160
 161         if (line->buf[line->len - 1] != '\n')
 162                 return NULL;
 163         line->buf[--line->len] = 0;
 164
 165         return ref;
 166 }
 167
 168 /*
 169  * Read from `packed_refs_file` into a newly-allocated
 170  * `packed_ref_cache` and return it. The return value will already
 171  * have its reference count incremented.
 172  *
 173  * A comment line of the form "# pack-refs with: " may contain zero or
 174  * more traits. We interpret the traits as follows:
 175  *
 176  *   No traits:
 177  *
 178  *      Probably no references are peeled. But if the file contains a
 179  *      peeled value for a reference, we will use it.
 180  *
 181  *   peeled:
 182  *
 183  *      References under "refs/tags/", if they *can* be peeled, *are*
 184  *      peeled in this file. References outside of "refs/tags/" are
 185  *      probably not peeled even if they could have been, but if we find
 186  *      a peeled value for such a reference we will use it.
 187  *
 188  *   fully-peeled:
 189  *
 190  *      All references in the file that can be peeled are peeled.
 191  *      Inversely (and this is more important), any references in the
 192  *      file for which no peeled value is recorded is not peelable. This
 193  *      trait should typically be written alongside "peeled" for
 194  *      compatibility with older clients, but we do not require it
 195  *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
 196  */
 197 static struct packed_ref_cache *read_packed_refs(const char *packed_refs_file)
 198 {
 199         FILE *f;
 200         struct packed_ref_cache *packed_refs = xcalloc(1, sizeof(*packed_refs));
 201         struct ref_entry *last = NULL;
 202         struct strbuf line = STRBUF_INIT;
 203         enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
 204         struct ref_dir *dir;
 205
 206         acquire_packed_ref_cache(packed_refs);
 207         packed_refs->cache = create_ref_cache(NULL, NULL);
 208         packed_refs->cache->root->flag &= ~REF_INCOMPLETE;
 209
 210         f = fopen(packed_refs_file, "r");
 211         if (!f) {
 212                 if (errno == ENOENT) {
 213                         /*
 214                          * This is OK; it just means that no
 215                          * "packed-refs" file has been written yet,
 216                          * which is equivalent to it being empty.
 217                          */
 218                         return packed_refs;
 219                 } else {
 220                         die_errno("couldn't read %s", packed_refs_file);
 221                 }
 222         }
 223
 224         stat_validity_update(&packed_refs->validity, fileno(f));
 225
 226         dir = get_ref_dir(packed_refs->cache->root);
 227         while (strbuf_getwholeline(&line, f, '\n') != EOF) {
 228                 struct object_id oid;
 229                 const char *refname;
 230                 const char *traits;
 231
 232                 if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
 233                         if (strstr(traits, " fully-peeled "))
 234                                 peeled = PEELED_FULLY;
 235                         else if (strstr(traits, " peeled "))
 236                                 peeled = PEELED_TAGS;
 237                         /* perhaps other traits later as well */
 238                         continue;
 239                 }
 240
 241                 refname = parse_ref_line(&line, &oid);
 242                 if (refname) {
 243                         int flag = REF_ISPACKED;
 244
 245                         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
 246                                 if (!refname_is_safe(refname))
 247                                         die("packed refname is dangerous: %s", refname);
 248                                 oidclr(&oid);
 249                                 flag |= REF_BAD_NAME | REF_ISBROKEN;
 250                         }
 251                         last = create_ref_entry(refname, &oid, flag);
 252                         if (peeled == PEELED_FULLY ||
 253                             (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
 254                                 last->flag |= REF_KNOWS_PEELED;
 255                         add_ref_entry(dir, last);
 256                         continue;
 257                 }
 258                 if (last &&
 259                     line.buf[0] == '^' &&
 260                     line.len == PEELED_LINE_LENGTH &&
 261                     line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
 262                     !get_oid_hex(line.buf + 1, &oid)) {
 263                         oidcpy(&last->u.value.peeled, &oid);
 264                         /*
 265                          * Regardless of what the file header said,
 266                          * we definitely know the value of *this*
 267                          * reference:
 268                          */
 269                         last->flag |= REF_KNOWS_PEELED;
 270                 }
 271         }
 272
 273         fclose(f);
 274         strbuf_release(&line);
 275
 276         return packed_refs;
 277 }
 278
 279 /*
 280  * Check that the packed refs cache (if any) still reflects the
 281  * contents of the file. If not, clear the cache.
 282  */
 283 static void validate_packed_ref_cache(struct packed_ref_store *refs)
 284 {
 285         if (refs->cache &&
 286             !stat_validity_check(&refs->cache->validity, refs->path))
 287                 clear_packed_ref_cache(refs);
 288 }
 289
 290 /*
 291  * Get the packed_ref_cache for the specified packed_ref_store,
 292  * creating and populating it if it hasn't been read before or if the
 293  * file has been changed (according to its `validity` field) since it
 294  * was last read. On the other hand, if we hold the lock, then assume
 295  * that the file hasn't been changed out from under us, so skip the
 296  * extra `stat()` call in `stat_validity_check()`.
 297  */
 298 static struct packed_ref_cache *get_packed_ref_cache(struct packed_ref_store *refs)
 299 {
 300         if (!is_lock_file_locked(&refs->lock))
 301                 validate_packed_ref_cache(refs);
 302
 303         if (!refs->cache)
 304                 refs->cache = read_packed_refs(refs->path);
 305
 306         return refs->cache;
 307 }
 308
 309 static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
 310 {
 311         return get_ref_dir(packed_ref_cache->cache->root);
 312 }
 313
 314 static struct ref_dir *get_packed_refs(struct packed_ref_store *refs)
 315 {
 316         return get_packed_ref_dir(get_packed_ref_cache(refs));
 317 }
 318
 319 /*
 320  * Add or overwrite a reference in the in-memory packed reference
 321  * cache. This may only be called while the packed-refs file is locked
 322  * (see packed_refs_lock()). To actually write the packed-refs file,
 323  * call commit_packed_refs().
 324  */
 325 void add_packed_ref(struct ref_store *ref_store,
 326                     const char *refname, const struct object_id *oid)
 327 {
 328         struct packed_ref_store *refs =
 329                 packed_downcast(ref_store, REF_STORE_WRITE,
 330                                 "add_packed_ref");
 331         struct ref_dir *packed_refs;
 332         struct ref_entry *packed_entry;
 333
 334         if (!is_lock_file_locked(&refs->lock))
 335                 die("BUG: packed refs not locked");
 336
 337         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
 338                 die("Reference has invalid format: '%s'", refname);
 339
 340         packed_refs = get_packed_refs(refs);
 341         packed_entry = find_ref_entry(packed_refs, refname);
 342         if (packed_entry) {
 343                 /* Overwrite the existing entry: */
 344                 oidcpy(&packed_entry->u.value.oid, oid);
 345                 packed_entry->flag = REF_ISPACKED;
 346                 oidclr(&packed_entry->u.value.peeled);
 347         } else {
 348                 packed_entry = create_ref_entry(refname, oid, REF_ISPACKED);
 349                 add_ref_entry(packed_refs, packed_entry);
 350         }
 351 }
 352
 353 /*
 354  * Return the ref_entry for the given refname from the packed
 355  * references.  If it does not exist, return NULL.
 356  */
 357 static struct ref_entry *get_packed_ref(struct packed_ref_store *refs,
 358                                         const char *refname)
 359 {
 360         return find_ref_entry(get_packed_refs(refs), refname);
 361 }
 362
 363 static int packed_read_raw_ref(struct ref_store *ref_store,
 364                                const char *refname, unsigned char *sha1,
 365                                struct strbuf *referent, unsigned int *type)
 366 {
 367         struct packed_ref_store *refs =
 368                 packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
 369
 370         struct ref_entry *entry;
 371
 372         *type = 0;
 373
 374         entry = get_packed_ref(refs, refname);
 375         if (!entry) {
 376                 errno = ENOENT;
 377                 return -1;
 378         }
 379
 380         hashcpy(sha1, entry->u.value.oid.hash);
 381         *type = REF_ISPACKED;
 382         return 0;
 383 }
 384
 385 static int packed_peel_ref(struct ref_store *ref_store,
 386                            const char *refname, unsigned char *sha1)
 387 {
 388         struct packed_ref_store *refs =
 389                 packed_downcast(ref_store, REF_STORE_READ | REF_STORE_ODB,
 390                                 "peel_ref");
 391         struct ref_entry *r = get_packed_ref(refs, refname);
 392
 393         if (!r || peel_entry(r, 0))
 394                 return -1;
 395
 396         hashcpy(sha1, r->u.value.peeled.hash);
 397         return 0;
 398 }
 399
 400 struct packed_ref_iterator {
 401         struct ref_iterator base;
 402
 403         struct packed_ref_cache *cache;
 404         struct ref_iterator *iter0;
 405         unsigned int flags;
 406 };
 407
 408 static int packed_ref_iterator_advance(struct ref_iterator *ref_iterator)
 409 {
 410         struct packed_ref_iterator *iter =
 411                 (struct packed_ref_iterator *)ref_iterator;
 412         int ok;
 413
 414         while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
 415                 if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
 416                     ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
 417                         continue;
 418
 419                 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 420                     !ref_resolves_to_object(iter->iter0->refname,
 421                                             iter->iter0->oid,
 422                                             iter->iter0->flags))
 423                         continue;
 424
 425                 iter->base.refname = iter->iter0->refname;
 426                 iter->base.oid = iter->iter0->oid;
 427                 iter->base.flags = iter->iter0->flags;
 428                 return ITER_OK;
 429         }
 430
 431         iter->iter0 = NULL;
 432         if (ref_iterator_abort(ref_iterator) != ITER_DONE)
 433                 ok = ITER_ERROR;
 434
 435         return ok;
 436 }
 437
 438 static int packed_ref_iterator_peel(struct ref_iterator *ref_iterator,
 439                                    struct object_id *peeled)
 440 {
 441         struct packed_ref_iterator *iter =
 442                 (struct packed_ref_iterator *)ref_iterator;
 443
 444         return ref_iterator_peel(iter->iter0, peeled);
 445 }
 446
 447 static int packed_ref_iterator_abort(struct ref_iterator *ref_iterator)
 448 {
 449         struct packed_ref_iterator *iter =
 450                 (struct packed_ref_iterator *)ref_iterator;
 451         int ok = ITER_DONE;
 452
 453         if (iter->iter0)
 454                 ok = ref_iterator_abort(iter->iter0);
 455
 456         release_packed_ref_cache(iter->cache);
 457         base_ref_iterator_free(ref_iterator);
 458         return ok;
 459 }
 460
 461 static struct ref_iterator_vtable packed_ref_iterator_vtable = {
 462         packed_ref_iterator_advance,
 463         packed_ref_iterator_peel,
 464         packed_ref_iterator_abort
 465 };
 466
 467 static struct ref_iterator *packed_ref_iterator_begin(
 468                 struct ref_store *ref_store,
 469                 const char *prefix, unsigned int flags)
 470 {
 471         struct packed_ref_store *refs;
 472         struct packed_ref_iterator *iter;
 473         struct ref_iterator *ref_iterator;
 474         unsigned int required_flags = REF_STORE_READ;
 475
 476         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
 477                 required_flags |= REF_STORE_ODB;
 478         refs = packed_downcast(ref_store, required_flags, "ref_iterator_begin");
 479
 480         iter = xcalloc(1, sizeof(*iter));
 481         ref_iterator = &iter->base;
 482         base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable);
 483
 484         /*
 485          * Note that get_packed_ref_cache() internally checks whether
 486          * the packed-ref cache is up to date with what is on disk,
 487          * and re-reads it if not.
 488          */
 489
 490         iter->cache = get_packed_ref_cache(refs);
 491         acquire_packed_ref_cache(iter->cache);
 492         iter->iter0 = cache_ref_iterator_begin(iter->cache->cache, prefix, 0);
 493
 494         iter->flags = flags;
 495
 496         return ref_iterator;
 497 }
 498
 499 /*
 500  * Write an entry to the packed-refs file for the specified refname.
 501  * If peeled is non-NULL, write it as the entry's peeled value. On
 502  * error, return a nonzero value and leave errno set at the value left
 503  * by the failing call to `fprintf()`.
 504  */
 505 static int write_packed_entry(FILE *fh, const char *refname,
 506                               const unsigned char *sha1,
 507                               const unsigned char *peeled)
 508 {
 509         if (fprintf(fh, "%s %s\n", sha1_to_hex(sha1), refname) < 0 ||
 510             (peeled && fprintf(fh, "^%s\n", sha1_to_hex(peeled)) < 0))
 511                 return -1;
 512
 513         return 0;
 514 }
 515
 516 int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)
 517 {
 518         struct packed_ref_store *refs =
 519                 packed_downcast(ref_store, REF_STORE_WRITE | REF_STORE_MAIN,
 520                                 "packed_refs_lock");
 521         static int timeout_configured = 0;
 522         static int timeout_value = 1000;
 523         struct packed_ref_cache *packed_ref_cache;
 524
 525         if (!timeout_configured) {
 526                 git_config_get_int("core.packedrefstimeout", &timeout_value);
 527                 timeout_configured = 1;
 528         }
 529
 530         /*
 531          * Note that we close the lockfile immediately because we
 532          * don't write new content to it, but rather to a separate
 533          * tempfile.
 534          */
 535         if (hold_lock_file_for_update_timeout(
 536                             &refs->lock,
 537                             refs->path,
 538                             flags, timeout_value) < 0) {
 539                 unable_to_lock_message(refs->path, errno, err);
 540                 return -1;
 541         }
 542
 543         if (close_lock_file(&refs->lock)) {
 544                 strbuf_addf(err, "unable to close %s: %s", refs->path, strerror(errno));
 545                 return -1;
 546         }
 547
 548         /*
 549          * Now that we hold the `packed-refs` lock, make sure that our
 550          * cache matches the current version of the file. Normally
 551          * `get_packed_ref_cache()` does that for us, but that
 552          * function assumes that when the file is locked, any existing
 553          * cache is still valid. We've just locked the file, but it
 554          * might have changed the moment *before* we locked it.
 555          */
 556         validate_packed_ref_cache(refs);
 557
 558         packed_ref_cache = get_packed_ref_cache(refs);
 559         /* Increment the reference count to prevent it from being freed: */
 560         acquire_packed_ref_cache(packed_ref_cache);
 561         return 0;
 562 }
 563
 564 void packed_refs_unlock(struct ref_store *ref_store)
 565 {
 566         struct packed_ref_store *refs = packed_downcast(
 567                         ref_store,
 568                         REF_STORE_READ | REF_STORE_WRITE,
 569                         "packed_refs_unlock");
 570
 571         if (!is_lock_file_locked(&refs->lock))
 572                 die("BUG: packed_refs_unlock() called when not locked");
 573         rollback_lock_file(&refs->lock);
 574         release_packed_ref_cache(refs->cache);
 575 }
 576
 577 int packed_refs_is_locked(struct ref_store *ref_store)
 578 {
 579         struct packed_ref_store *refs = packed_downcast(
 580                         ref_store,
 581                         REF_STORE_READ | REF_STORE_WRITE,
 582                         "packed_refs_is_locked");
 583
 584         return is_lock_file_locked(&refs->lock);
 585 }
 586
 587 /*
 588  * The packed-refs header line that we write out.  Perhaps other
 589  * traits will be added later.  The trailing space is required.
 590  */
 591 static const char PACKED_REFS_HEADER[] =
 592         "# pack-refs with: peeled fully-peeled \n";
 593
 594 /*
 595  * Write the current version of the packed refs cache from memory to
 596  * disk. The packed-refs file must already be locked for writing (see
 597  * packed_refs_lock()). Return zero on success. On errors, rollback
 598  * the lockfile, write an error message to `err`, and return a nonzero
 599  * value.
 600  */
 601 int commit_packed_refs(struct ref_store *ref_store, struct strbuf *err)
 602 {
 603         struct packed_ref_store *refs =
 604                 packed_downcast(ref_store, REF_STORE_WRITE | REF_STORE_MAIN,
 605                                 "commit_packed_refs");
 606         struct packed_ref_cache *packed_ref_cache =
 607                 get_packed_ref_cache(refs);
 608         int ok;
 609         struct strbuf sb = STRBUF_INIT;
 610         FILE *out;
 611         struct ref_iterator *iter;
 612
 613         if (!is_lock_file_locked(&refs->lock))
 614                 die("BUG: commit_packed_refs() called when unlocked");
 615
 616         strbuf_addf(&sb, "%s.new", refs->path);
 617         if (create_tempfile(&refs->tempfile, sb.buf) < 0) {
 618                 strbuf_addf(err, "unable to create file %s: %s",
 619                             sb.buf, strerror(errno));
 620                 strbuf_release(&sb);
 621                 return -1;
 622         }
 623         strbuf_release(&sb);
 624
 625         out = fdopen_tempfile(&refs->tempfile, "w");
 626         if (!out) {
 627                 strbuf_addf(err, "unable to fdopen packed-refs tempfile: %s",
 628                             strerror(errno));
 629                 goto error;
 630         }
 631
 632         if (fprintf(out, "%s", PACKED_REFS_HEADER) < 0) {
 633                 strbuf_addf(err, "error writing to %s: %s",
 634                             get_tempfile_path(&refs->tempfile), strerror(errno));
 635                 goto error;
 636         }
 637
 638         iter = cache_ref_iterator_begin(packed_ref_cache->cache, NULL, 0);
 639         while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
 640                 struct object_id peeled;
 641                 int peel_error = ref_iterator_peel(iter, &peeled);
 642
 643                 if (write_packed_entry(out, iter->refname, iter->oid->hash,
 644                                        peel_error ? NULL : peeled.hash)) {
 645                         strbuf_addf(err, "error writing to %s: %s",
 646                                     get_tempfile_path(&refs->tempfile),
 647                                     strerror(errno));
 648                         ref_iterator_abort(iter);
 649                         goto error;
 650                 }
 651         }
 652
 653         if (ok != ITER_DONE) {
 654                 strbuf_addf(err, "unable to rewrite packed-refs file: "
 655                             "error iterating over old contents");
 656                 goto error;
 657         }
 658
 659         if (rename_tempfile(&refs->tempfile, refs->path)) {
 660                 strbuf_addf(err, "error replacing %s: %s",
 661                             refs->path, strerror(errno));
 662                 return -1;
 663         }
 664
 665         return 0;
 666
 667 error:
 668         delete_tempfile(&refs->tempfile);
 669         return -1;
 670 }
 671
 672 /*
 673  * Rewrite the packed-refs file, omitting any refs listed in
 674  * 'refnames'. On error, leave packed-refs unchanged, write an error
 675  * message to 'err', and return a nonzero value. The packed refs lock
 676  * must be held when calling this function; it will still be held when
 677  * the function returns.
 678  *
 679  * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
 680  */
 681 int repack_without_refs(struct ref_store *ref_store,
 682                         struct string_list *refnames, struct strbuf *err)
 683 {
 684         struct packed_ref_store *refs =
 685                 packed_downcast(ref_store, REF_STORE_WRITE | REF_STORE_MAIN,
 686                                 "repack_without_refs");
 687         struct ref_dir *packed;
 688         struct string_list_item *refname;
 689         int needs_repacking = 0, removed = 0;
 690
 691         packed_assert_main_repository(refs, "repack_without_refs");
 692         assert(err);
 693
 694         if (!is_lock_file_locked(&refs->lock))
 695                 die("BUG: repack_without_refs called without holding lock");
 696
 697         /* Look for a packed ref */
 698         for_each_string_list_item(refname, refnames) {
 699                 if (get_packed_ref(refs, refname->string)) {
 700                         needs_repacking = 1;
 701                         break;
 702                 }
 703         }
 704
 705         /* Avoid locking if we have nothing to do */
 706         if (!needs_repacking)
 707                 return 0; /* no refname exists in packed refs */
 708
 709         packed = get_packed_refs(refs);
 710
 711         /* Remove refnames from the cache */
 712         for_each_string_list_item(refname, refnames)
 713                 if (remove_entry_from_dir(packed, refname->string) != -1)
 714                         removed = 1;
 715         if (!removed) {
 716                 /*
 717                  * All packed entries disappeared while we were
 718                  * acquiring the lock.
 719                  */
 720                 clear_packed_ref_cache(refs);
 721                 return 0;
 722         }
 723
 724         /* Write what remains */
 725         return commit_packed_refs(&refs->base, err);
 726 }
 727
 728 static int packed_init_db(struct ref_store *ref_store, struct strbuf *err)
 729 {
 730         /* Nothing to do. */
 731         return 0;
 732 }
 733
 734 static int packed_transaction_prepare(struct ref_store *ref_store,
 735                                       struct ref_transaction *transaction,
 736                                       struct strbuf *err)
 737 {
 738         die("BUG: not implemented yet");
 739 }
 740
 741 static int packed_transaction_abort(struct ref_store *ref_store,
 742                                     struct ref_transaction *transaction,
 743                                     struct strbuf *err)
 744 {
 745         die("BUG: not implemented yet");
 746 }
 747
 748 static int packed_transaction_finish(struct ref_store *ref_store,
 749                                      struct ref_transaction *transaction,
 750                                      struct strbuf *err)
 751 {
 752         die("BUG: not implemented yet");
 753 }
 754
 755 static int packed_initial_transaction_commit(struct ref_store *ref_store,
 756                                             struct ref_transaction *transaction,
 757                                             struct strbuf *err)
 758 {
 759         return ref_transaction_commit(transaction, err);
 760 }
 761
 762 static int packed_delete_refs(struct ref_store *ref_store, const char *msg,
 763                              struct string_list *refnames, unsigned int flags)
 764 {
 765         die("BUG: not implemented yet");
 766 }
 767
 768 static int packed_pack_refs(struct ref_store *ref_store, unsigned int flags)
 769 {
 770         /*
 771          * Packed refs are already packed. It might be that loose refs
 772          * are packed *into* a packed refs store, but that is done by
 773          * updating the packed references via a transaction.
 774          */
 775         return 0;
 776 }
 777
 778 static int packed_create_symref(struct ref_store *ref_store,
 779                                const char *refname, const char *target,
 780                                const char *logmsg)
 781 {
 782         die("BUG: packed reference store does not support symrefs");
 783 }
 784
 785 static int packed_rename_ref(struct ref_store *ref_store,
 786                             const char *oldrefname, const char *newrefname,
 787                             const char *logmsg)
 788 {
 789         die("BUG: packed reference store does not support renaming references");
 790 }
 791
 792 static struct ref_iterator *packed_reflog_iterator_begin(struct ref_store *ref_store)
 793 {
 794         return empty_ref_iterator_begin();
 795 }
 796
 797 static int packed_for_each_reflog_ent(struct ref_store *ref_store,
 798                                       const char *refname,
 799                                       each_reflog_ent_fn fn, void *cb_data)
 800 {
 801         return 0;
 802 }
 803
 804 static int packed_for_each_reflog_ent_reverse(struct ref_store *ref_store,
 805                                               const char *refname,
 806                                               each_reflog_ent_fn fn,
 807                                               void *cb_data)
 808 {
 809         return 0;
 810 }
 811
 812 static int packed_reflog_exists(struct ref_store *ref_store,
 813                                const char *refname)
 814 {
 815         return 0;
 816 }
 817
 818 static int packed_create_reflog(struct ref_store *ref_store,
 819                                const char *refname, int force_create,
 820                                struct strbuf *err)
 821 {
 822         die("BUG: packed reference store does not support reflogs");
 823 }
 824
 825 static int packed_delete_reflog(struct ref_store *ref_store,
 826                                const char *refname)
 827 {
 828         return 0;
 829 }
 830
 831 static int packed_reflog_expire(struct ref_store *ref_store,
 832                                 const char *refname, const unsigned char *sha1,
 833                                 unsigned int flags,
 834                                 reflog_expiry_prepare_fn prepare_fn,
 835                                 reflog_expiry_should_prune_fn should_prune_fn,
 836                                 reflog_expiry_cleanup_fn cleanup_fn,
 837                                 void *policy_cb_data)
 838 {
 839         return 0;
 840 }
 841
 842 struct ref_storage_be refs_be_packed = {
 843         NULL,
 844         "packed",
 845         packed_ref_store_create,
 846         packed_init_db,
 847         packed_transaction_prepare,
 848         packed_transaction_finish,
 849         packed_transaction_abort,
 850         packed_initial_transaction_commit,
 851
 852         packed_pack_refs,
 853         packed_peel_ref,
 854         packed_create_symref,
 855         packed_delete_refs,
 856         packed_rename_ref,
 857
 858         packed_ref_iterator_begin,
 859         packed_read_raw_ref,
 860
 861         packed_reflog_iterator_begin,
 862         packed_for_each_reflog_ent,
 863         packed_for_each_reflog_ent_reverse,
 864         packed_reflog_exists,
 865         packed_create_reflog,
 866         packed_delete_reflog,
 867         packed_reflog_expire
 868 };