git.oblomov.eu Git - git/blob - sha1-name.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "tag.h"
   4 #include "commit.h"
   5 #include "tree.h"
   6 #include "blob.h"
   7 #include "tree-walk.h"
   8 #include "refs.h"
   9 #include "remote.h"
  10 #include "dir.h"
  11 #include "sha1-array.h"
  12 #include "packfile.h"
  13 #include "object-store.h"
  14 #include "repository.h"
  15 #include "midx.h"
  16 #include "commit-reach.h"
  17
  18 static int get_oid_oneline(const char *, struct object_id *, struct commit_list *);
  19
  20 typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
  21
  22 struct disambiguate_state {
  23         int len; /* length of prefix in hex chars */
  24         char hex_pfx[GIT_MAX_HEXSZ + 1];
  25         struct object_id bin_pfx;
  26
  27         disambiguate_hint_fn fn;
  28         void *cb_data;
  29         struct object_id candidate;
  30         unsigned candidate_exists:1;
  31         unsigned candidate_checked:1;
  32         unsigned candidate_ok:1;
  33         unsigned disambiguate_fn_used:1;
  34         unsigned ambiguous:1;
  35         unsigned always_call_fn:1;
  36 };
  37
  38 static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
  39 {
  40         if (ds->always_call_fn) {
  41                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  42                 return;
  43         }
  44         if (!ds->candidate_exists) {
  45                 /* this is the first candidate */
  46                 oidcpy(&ds->candidate, current);
  47                 ds->candidate_exists = 1;
  48                 return;
  49         } else if (oideq(&ds->candidate, current)) {
  50                 /* the same as what we already have seen */
  51                 return;
  52         }
  53
  54         if (!ds->fn) {
  55                 /* cannot disambiguate between ds->candidate and current */
  56                 ds->ambiguous = 1;
  57                 return;
  58         }
  59
  60         if (!ds->candidate_checked) {
  61                 ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
  62                 ds->disambiguate_fn_used = 1;
  63                 ds->candidate_checked = 1;
  64         }
  65
  66         if (!ds->candidate_ok) {
  67                 /* discard the candidate; we know it does not satisfy fn */
  68                 oidcpy(&ds->candidate, current);
  69                 ds->candidate_checked = 0;
  70                 return;
  71         }
  72
  73         /* if we reach this point, we know ds->candidate satisfies fn */
  74         if (ds->fn(current, ds->cb_data)) {
  75                 /*
  76                  * if both current and candidate satisfy fn, we cannot
  77                  * disambiguate.
  78                  */
  79                 ds->candidate_ok = 0;
  80                 ds->ambiguous = 1;
  81         }
  82
  83         /* otherwise, current can be discarded and candidate is still good */
  84 }
  85
  86 static int append_loose_object(const struct object_id *oid, const char *path,
  87                                void *data)
  88 {
  89         oid_array_append(data, oid);
  90         return 0;
  91 }
  92
  93 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  94
  95 static void find_short_object_filename(struct disambiguate_state *ds)
  96 {
  97         int subdir_nr = ds->bin_pfx.hash[0];
  98         struct object_directory *odb;
  99         static struct object_directory *fakeent;
 100         struct strbuf buf = STRBUF_INIT;
 101
 102         if (!fakeent) {
 103                 /*
 104                  * Create a "fake" alternate object database that
 105                  * points to our own object database, to make it
 106                  * easier to get a temporary working space in
 107                  * alt->name/alt->base while iterating over the
 108                  * object databases including our own.
 109                  */
 110                 fakeent = alloc_alt_odb(get_object_directory());
 111         }
 112         fakeent->next = the_repository->objects->alt_odb_list;
 113
 114         for (odb = fakeent; odb && !ds->ambiguous; odb = odb->next) {
 115                 int pos;
 116
 117                 if (!odb->loose_objects_subdir_seen[subdir_nr]) {
 118                         strbuf_reset(&buf);
 119                         strbuf_addstr(&buf, odb->path);
 120                         for_each_file_in_obj_subdir(subdir_nr, &buf,
 121                                                     append_loose_object,
 122                                                     NULL, NULL,
 123                                                     &odb->loose_objects_cache);
 124                         odb->loose_objects_subdir_seen[subdir_nr] = 1;
 125                 }
 126
 127                 pos = oid_array_lookup(&odb->loose_objects_cache, &ds->bin_pfx);
 128                 if (pos < 0)
 129                         pos = -1 - pos;
 130                 while (!ds->ambiguous && pos < odb->loose_objects_cache.nr) {
 131                         const struct object_id *oid;
 132                         oid = odb->loose_objects_cache.oid + pos;
 133                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 134                                 break;
 135                         update_candidates(ds, oid);
 136                         pos++;
 137                 }
 138         }
 139
 140         strbuf_release(&buf);
 141 }
 142
 143 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 144 {
 145         do {
 146                 if (*a != *b)
 147                         return 0;
 148                 a++;
 149                 b++;
 150                 len -= 2;
 151         } while (len > 1);
 152         if (len)
 153                 if ((*a ^ *b) & 0xf0)
 154                         return 0;
 155         return 1;
 156 }
 157
 158 static void unique_in_midx(struct multi_pack_index *m,
 159                            struct disambiguate_state *ds)
 160 {
 161         uint32_t num, i, first = 0;
 162         const struct object_id *current = NULL;
 163         num = m->num_objects;
 164
 165         if (!num)
 166                 return;
 167
 168         bsearch_midx(&ds->bin_pfx, m, &first);
 169
 170         /*
 171          * At this point, "first" is the location of the lowest object
 172          * with an object name that could match "bin_pfx".  See if we have
 173          * 0, 1 or more objects that actually match(es).
 174          */
 175         for (i = first; i < num && !ds->ambiguous; i++) {
 176                 struct object_id oid;
 177                 current = nth_midxed_object_oid(&oid, m, i);
 178                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 179                         break;
 180                 update_candidates(ds, current);
 181         }
 182 }
 183
 184 static void unique_in_pack(struct packed_git *p,
 185                            struct disambiguate_state *ds)
 186 {
 187         uint32_t num, i, first = 0;
 188         const struct object_id *current = NULL;
 189
 190         if (open_pack_index(p) || !p->num_objects)
 191                 return;
 192
 193         num = p->num_objects;
 194         bsearch_pack(&ds->bin_pfx, p, &first);
 195
 196         /*
 197          * At this point, "first" is the location of the lowest object
 198          * with an object name that could match "bin_pfx".  See if we have
 199          * 0, 1 or more objects that actually match(es).
 200          */
 201         for (i = first; i < num && !ds->ambiguous; i++) {
 202                 struct object_id oid;
 203                 current = nth_packed_object_oid(&oid, p, i);
 204                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 205                         break;
 206                 update_candidates(ds, current);
 207         }
 208 }
 209
 210 static void find_short_packed_object(struct disambiguate_state *ds)
 211 {
 212         struct multi_pack_index *m;
 213         struct packed_git *p;
 214
 215         for (m = get_multi_pack_index(the_repository); m && !ds->ambiguous;
 216              m = m->next)
 217                 unique_in_midx(m, ds);
 218         for (p = get_packed_git(the_repository); p && !ds->ambiguous;
 219              p = p->next)
 220                 unique_in_pack(p, ds);
 221 }
 222
 223 #define SHORT_NAME_NOT_FOUND (-1)
 224 #define SHORT_NAME_AMBIGUOUS (-2)
 225
 226 static int finish_object_disambiguation(struct disambiguate_state *ds,
 227                                         struct object_id *oid)
 228 {
 229         if (ds->ambiguous)
 230                 return SHORT_NAME_AMBIGUOUS;
 231
 232         if (!ds->candidate_exists)
 233                 return SHORT_NAME_NOT_FOUND;
 234
 235         if (!ds->candidate_checked)
 236                 /*
 237                  * If this is the only candidate, there is no point
 238                  * calling the disambiguation hint callback.
 239                  *
 240                  * On the other hand, if the current candidate
 241                  * replaced an earlier candidate that did _not_ pass
 242                  * the disambiguation hint callback, then we do have
 243                  * more than one objects that match the short name
 244                  * given, so we should make sure this one matches;
 245                  * otherwise, if we discovered this one and the one
 246                  * that we previously discarded in the reverse order,
 247                  * we would end up showing different results in the
 248                  * same repository!
 249                  */
 250                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 251                                     ds->fn(&ds->candidate, ds->cb_data));
 252
 253         if (!ds->candidate_ok)
 254                 return SHORT_NAME_AMBIGUOUS;
 255
 256         oidcpy(oid, &ds->candidate);
 257         return 0;
 258 }
 259
 260 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 261 {
 262         int kind = oid_object_info(the_repository, oid, NULL);
 263         return kind == OBJ_COMMIT;
 264 }
 265
 266 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 267 {
 268         struct object *obj;
 269         int kind;
 270
 271         kind = oid_object_info(the_repository, oid, NULL);
 272         if (kind == OBJ_COMMIT)
 273                 return 1;
 274         if (kind != OBJ_TAG)
 275                 return 0;
 276
 277         /* We need to do this the hard way... */
 278         obj = deref_tag(the_repository, parse_object(the_repository, oid),
 279                         NULL, 0);
 280         if (obj && obj->type == OBJ_COMMIT)
 281                 return 1;
 282         return 0;
 283 }
 284
 285 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 286 {
 287         int kind = oid_object_info(the_repository, oid, NULL);
 288         return kind == OBJ_TREE;
 289 }
 290
 291 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 292 {
 293         struct object *obj;
 294         int kind;
 295
 296         kind = oid_object_info(the_repository, oid, NULL);
 297         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 298                 return 1;
 299         if (kind != OBJ_TAG)
 300                 return 0;
 301
 302         /* We need to do this the hard way... */
 303         obj = deref_tag(the_repository, parse_object(the_repository, oid),
 304                         NULL, 0);
 305         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 306                 return 1;
 307         return 0;
 308 }
 309
 310 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 311 {
 312         int kind = oid_object_info(the_repository, oid, NULL);
 313         return kind == OBJ_BLOB;
 314 }
 315
 316 static disambiguate_hint_fn default_disambiguate_hint;
 317
 318 int set_disambiguate_hint_config(const char *var, const char *value)
 319 {
 320         static const struct {
 321                 const char *name;
 322                 disambiguate_hint_fn fn;
 323         } hints[] = {
 324                 { "none", NULL },
 325                 { "commit", disambiguate_commit_only },
 326                 { "committish", disambiguate_committish_only },
 327                 { "tree", disambiguate_tree_only },
 328                 { "treeish", disambiguate_treeish_only },
 329                 { "blob", disambiguate_blob_only }
 330         };
 331         int i;
 332
 333         if (!value)
 334                 return config_error_nonbool(var);
 335
 336         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 337                 if (!strcasecmp(value, hints[i].name)) {
 338                         default_disambiguate_hint = hints[i].fn;
 339                         return 0;
 340                 }
 341         }
 342
 343         return error("unknown hint type for '%s': %s", var, value);
 344 }
 345
 346 static int init_object_disambiguation(const char *name, int len,
 347                                       struct disambiguate_state *ds)
 348 {
 349         int i;
 350
 351         if (len < MINIMUM_ABBREV || len > the_hash_algo->hexsz)
 352                 return -1;
 353
 354         memset(ds, 0, sizeof(*ds));
 355
 356         for (i = 0; i < len ;i++) {
 357                 unsigned char c = name[i];
 358                 unsigned char val;
 359                 if (c >= '0' && c <= '9')
 360                         val = c - '0';
 361                 else if (c >= 'a' && c <= 'f')
 362                         val = c - 'a' + 10;
 363                 else if (c >= 'A' && c <='F') {
 364                         val = c - 'A' + 10;
 365                         c -= 'A' - 'a';
 366                 }
 367                 else
 368                         return -1;
 369                 ds->hex_pfx[i] = c;
 370                 if (!(i & 1))
 371                         val <<= 4;
 372                 ds->bin_pfx.hash[i >> 1] |= val;
 373         }
 374
 375         ds->len = len;
 376         ds->hex_pfx[len] = '\0';
 377         prepare_alt_odb(the_repository);
 378         return 0;
 379 }
 380
 381 static int show_ambiguous_object(const struct object_id *oid, void *data)
 382 {
 383         const struct disambiguate_state *ds = data;
 384         struct strbuf desc = STRBUF_INIT;
 385         int type;
 386
 387         if (ds->fn && !ds->fn(oid, ds->cb_data))
 388                 return 0;
 389
 390         type = oid_object_info(the_repository, oid, NULL);
 391         if (type == OBJ_COMMIT) {
 392                 struct commit *commit = lookup_commit(the_repository, oid);
 393                 if (commit) {
 394                         struct pretty_print_context pp = {0};
 395                         pp.date_mode.type = DATE_SHORT;
 396                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 397                 }
 398         } else if (type == OBJ_TAG) {
 399                 struct tag *tag = lookup_tag(the_repository, oid);
 400                 if (!parse_tag(tag) && tag->tag)
 401                         strbuf_addf(&desc, " %s", tag->tag);
 402         }
 403
 404         advise("  %s %s%s",
 405                find_unique_abbrev(oid, DEFAULT_ABBREV),
 406                type_name(type) ? type_name(type) : "unknown type",
 407                desc.buf);
 408
 409         strbuf_release(&desc);
 410         return 0;
 411 }
 412
 413 static int collect_ambiguous(const struct object_id *oid, void *data)
 414 {
 415         oid_array_append(data, oid);
 416         return 0;
 417 }
 418
 419 static int sort_ambiguous(const void *a, const void *b)
 420 {
 421         int a_type = oid_object_info(the_repository, a, NULL);
 422         int b_type = oid_object_info(the_repository, b, NULL);
 423         int a_type_sort;
 424         int b_type_sort;
 425
 426         /*
 427          * Sorts by hash within the same object type, just as
 428          * oid_array_for_each_unique() would do.
 429          */
 430         if (a_type == b_type)
 431                 return oidcmp(a, b);
 432
 433         /*
 434          * Between object types show tags, then commits, and finally
 435          * trees and blobs.
 436          *
 437          * The object_type enum is commit, tree, blob, tag, but we
 438          * want tag, commit, tree blob. Cleverly (perhaps too
 439          * cleverly) do that with modulus, since the enum assigns 1 to
 440          * commit, so tag becomes 0.
 441          */
 442         a_type_sort = a_type % 4;
 443         b_type_sort = b_type % 4;
 444         return a_type_sort > b_type_sort ? 1 : -1;
 445 }
 446
 447 static int get_short_oid(const char *name, int len, struct object_id *oid,
 448                           unsigned flags)
 449 {
 450         int status;
 451         struct disambiguate_state ds;
 452         int quietly = !!(flags & GET_OID_QUIETLY);
 453
 454         if (init_object_disambiguation(name, len, &ds) < 0)
 455                 return -1;
 456
 457         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 458                 BUG("multiple get_short_oid disambiguator flags");
 459
 460         if (flags & GET_OID_COMMIT)
 461                 ds.fn = disambiguate_commit_only;
 462         else if (flags & GET_OID_COMMITTISH)
 463                 ds.fn = disambiguate_committish_only;
 464         else if (flags & GET_OID_TREE)
 465                 ds.fn = disambiguate_tree_only;
 466         else if (flags & GET_OID_TREEISH)
 467                 ds.fn = disambiguate_treeish_only;
 468         else if (flags & GET_OID_BLOB)
 469                 ds.fn = disambiguate_blob_only;
 470         else
 471                 ds.fn = default_disambiguate_hint;
 472
 473         find_short_object_filename(&ds);
 474         find_short_packed_object(&ds);
 475         status = finish_object_disambiguation(&ds, oid);
 476
 477         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 478                 struct oid_array collect = OID_ARRAY_INIT;
 479
 480                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 481
 482                 /*
 483                  * We may still have ambiguity if we simply saw a series of
 484                  * candidates that did not satisfy our hint function. In
 485                  * that case, we still want to show them, so disable the hint
 486                  * function entirely.
 487                  */
 488                 if (!ds.ambiguous)
 489                         ds.fn = NULL;
 490
 491                 advise(_("The candidates are:"));
 492                 for_each_abbrev(ds.hex_pfx, collect_ambiguous, &collect);
 493                 QSORT(collect.oid, collect.nr, sort_ambiguous);
 494
 495                 if (oid_array_for_each(&collect, show_ambiguous_object, &ds))
 496                         BUG("show_ambiguous_object shouldn't return non-zero");
 497                 oid_array_clear(&collect);
 498         }
 499
 500         return status;
 501 }
 502
 503 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 504 {
 505         struct oid_array collect = OID_ARRAY_INIT;
 506         struct disambiguate_state ds;
 507         int ret;
 508
 509         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 510                 return -1;
 511
 512         ds.always_call_fn = 1;
 513         ds.fn = collect_ambiguous;
 514         ds.cb_data = &collect;
 515         find_short_object_filename(&ds);
 516         find_short_packed_object(&ds);
 517
 518         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 519         oid_array_clear(&collect);
 520         return ret;
 521 }
 522
 523 /*
 524  * Return the slot of the most-significant bit set in "val". There are various
 525  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 526  * probably not a big deal here.
 527  */
 528 static unsigned msb(unsigned long val)
 529 {
 530         unsigned r = 0;
 531         while (val >>= 1)
 532                 r++;
 533         return r;
 534 }
 535
 536 struct min_abbrev_data {
 537         unsigned int init_len;
 538         unsigned int cur_len;
 539         char *hex;
 540         const struct object_id *oid;
 541 };
 542
 543 static inline char get_hex_char_from_oid(const struct object_id *oid,
 544                                          unsigned int pos)
 545 {
 546         static const char hex[] = "0123456789abcdef";
 547
 548         if ((pos & 1) == 0)
 549                 return hex[oid->hash[pos >> 1] >> 4];
 550         else
 551                 return hex[oid->hash[pos >> 1] & 0xf];
 552 }
 553
 554 static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
 555 {
 556         struct min_abbrev_data *mad = cb_data;
 557
 558         unsigned int i = mad->init_len;
 559         while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
 560                 i++;
 561
 562         if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
 563                 mad->cur_len = i + 1;
 564
 565         return 0;
 566 }
 567
 568 static void find_abbrev_len_for_midx(struct multi_pack_index *m,
 569                                      struct min_abbrev_data *mad)
 570 {
 571         int match = 0;
 572         uint32_t num, first = 0;
 573         struct object_id oid;
 574         const struct object_id *mad_oid;
 575
 576         if (!m->num_objects)
 577                 return;
 578
 579         num = m->num_objects;
 580         mad_oid = mad->oid;
 581         match = bsearch_midx(mad_oid, m, &first);
 582
 583         /*
 584          * first is now the position in the packfile where we would insert
 585          * mad->hash if it does not exist (or the position of mad->hash if
 586          * it does exist). Hence, we consider a maximum of two objects
 587          * nearby for the abbreviation length.
 588          */
 589         mad->init_len = 0;
 590         if (!match) {
 591                 if (nth_midxed_object_oid(&oid, m, first))
 592                         extend_abbrev_len(&oid, mad);
 593         } else if (first < num - 1) {
 594                 if (nth_midxed_object_oid(&oid, m, first + 1))
 595                         extend_abbrev_len(&oid, mad);
 596         }
 597         if (first > 0) {
 598                 if (nth_midxed_object_oid(&oid, m, first - 1))
 599                         extend_abbrev_len(&oid, mad);
 600         }
 601         mad->init_len = mad->cur_len;
 602 }
 603
 604 static void find_abbrev_len_for_pack(struct packed_git *p,
 605                                      struct min_abbrev_data *mad)
 606 {
 607         int match = 0;
 608         uint32_t num, first = 0;
 609         struct object_id oid;
 610         const struct object_id *mad_oid;
 611
 612         if (open_pack_index(p) || !p->num_objects)
 613                 return;
 614
 615         num = p->num_objects;
 616         mad_oid = mad->oid;
 617         match = bsearch_pack(mad_oid, p, &first);
 618
 619         /*
 620          * first is now the position in the packfile where we would insert
 621          * mad->hash if it does not exist (or the position of mad->hash if
 622          * it does exist). Hence, we consider a maximum of two objects
 623          * nearby for the abbreviation length.
 624          */
 625         mad->init_len = 0;
 626         if (!match) {
 627                 if (nth_packed_object_oid(&oid, p, first))
 628                         extend_abbrev_len(&oid, mad);
 629         } else if (first < num - 1) {
 630                 if (nth_packed_object_oid(&oid, p, first + 1))
 631                         extend_abbrev_len(&oid, mad);
 632         }
 633         if (first > 0) {
 634                 if (nth_packed_object_oid(&oid, p, first - 1))
 635                         extend_abbrev_len(&oid, mad);
 636         }
 637         mad->init_len = mad->cur_len;
 638 }
 639
 640 static void find_abbrev_len_packed(struct min_abbrev_data *mad)
 641 {
 642         struct multi_pack_index *m;
 643         struct packed_git *p;
 644
 645         for (m = get_multi_pack_index(the_repository); m; m = m->next)
 646                 find_abbrev_len_for_midx(m, mad);
 647         for (p = get_packed_git(the_repository); p; p = p->next)
 648                 find_abbrev_len_for_pack(p, mad);
 649 }
 650
 651 int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 652 {
 653         struct disambiguate_state ds;
 654         struct min_abbrev_data mad;
 655         struct object_id oid_ret;
 656         const unsigned hexsz = the_hash_algo->hexsz;
 657
 658         if (len < 0) {
 659                 unsigned long count = approximate_object_count();
 660                 /*
 661                  * Add one because the MSB only tells us the highest bit set,
 662                  * not including the value of all the _other_ bits (so "15"
 663                  * is only one off of 2^4, but the MSB is the 3rd bit.
 664                  */
 665                 len = msb(count) + 1;
 666                 /*
 667                  * We now know we have on the order of 2^len objects, which
 668                  * expects a collision at 2^(len/2). But we also care about hex
 669                  * chars, not bits, and there are 4 bits per hex. So all
 670                  * together we need to divide by 2 and round up.
 671                  */
 672                 len = DIV_ROUND_UP(len, 2);
 673                 /*
 674                  * For very small repos, we stick with our regular fallback.
 675                  */
 676                 if (len < FALLBACK_DEFAULT_ABBREV)
 677                         len = FALLBACK_DEFAULT_ABBREV;
 678         }
 679
 680         oid_to_hex_r(hex, oid);
 681         if (len == hexsz || !len)
 682                 return hexsz;
 683
 684         mad.init_len = len;
 685         mad.cur_len = len;
 686         mad.hex = hex;
 687         mad.oid = oid;
 688
 689         find_abbrev_len_packed(&mad);
 690
 691         if (init_object_disambiguation(hex, mad.cur_len, &ds) < 0)
 692                 return -1;
 693
 694         ds.fn = extend_abbrev_len;
 695         ds.always_call_fn = 1;
 696         ds.cb_data = (void *)&mad;
 697
 698         find_short_object_filename(&ds);
 699         (void)finish_object_disambiguation(&ds, &oid_ret);
 700
 701         hex[mad.cur_len] = 0;
 702         return mad.cur_len;
 703 }
 704
 705 const char *find_unique_abbrev(const struct object_id *oid, int len)
 706 {
 707         static int bufno;
 708         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 709         char *hex = hexbuffer[bufno];
 710         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 711         find_unique_abbrev_r(hex, oid, len);
 712         return hex;
 713 }
 714
 715 static int ambiguous_path(const char *path, int len)
 716 {
 717         int slash = 1;
 718         int cnt;
 719
 720         for (cnt = 0; cnt < len; cnt++) {
 721                 switch (*path++) {
 722                 case '\0':
 723                         break;
 724                 case '/':
 725                         if (slash)
 726                                 break;
 727                         slash = 1;
 728                         continue;
 729                 case '.':
 730                         continue;
 731                 default:
 732                         slash = 0;
 733                         continue;
 734                 }
 735                 break;
 736         }
 737         return slash;
 738 }
 739
 740 static inline int at_mark(const char *string, int len,
 741                           const char **suffix, int nr)
 742 {
 743         int i;
 744
 745         for (i = 0; i < nr; i++) {
 746                 int suffix_len = strlen(suffix[i]);
 747                 if (suffix_len <= len
 748                     && !strncasecmp(string, suffix[i], suffix_len))
 749                         return suffix_len;
 750         }
 751         return 0;
 752 }
 753
 754 static inline int upstream_mark(const char *string, int len)
 755 {
 756         const char *suffix[] = { "@{upstream}", "@{u}" };
 757         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 758 }
 759
 760 static inline int push_mark(const char *string, int len)
 761 {
 762         const char *suffix[] = { "@{push}" };
 763         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 764 }
 765
 766 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 767 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 768
 769 static int get_oid_basic(const char *str, int len, struct object_id *oid,
 770                           unsigned int flags)
 771 {
 772         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 773         static const char *object_name_msg = N_(
 774         "Git normally never creates a ref that ends with 40 hex characters\n"
 775         "because it will be ignored when you just specify 40-hex. These refs\n"
 776         "may be created by mistake. For example,\n"
 777         "\n"
 778         "  git checkout -b $br $(git rev-parse ...)\n"
 779         "\n"
 780         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 781         "examine these refs and maybe delete them. Turn this message off by\n"
 782         "running \"git config advice.objectNameWarning false\"");
 783         struct object_id tmp_oid;
 784         char *real_ref = NULL;
 785         int refs_found = 0;
 786         int at, reflog_len, nth_prior = 0;
 787
 788         if (len == the_hash_algo->hexsz && !get_oid_hex(str, oid)) {
 789                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 790                         refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
 791                         if (refs_found > 0) {
 792                                 warning(warn_msg, len, str);
 793                                 if (advice_object_name_warning)
 794                                         fprintf(stderr, "%s\n", _(object_name_msg));
 795                         }
 796                         free(real_ref);
 797                 }
 798                 return 0;
 799         }
 800
 801         /* basic@{time or number or -number} format to query ref-log */
 802         reflog_len = at = 0;
 803         if (len && str[len-1] == '}') {
 804                 for (at = len-4; at >= 0; at--) {
 805                         if (str[at] == '@' && str[at+1] == '{') {
 806                                 if (str[at+2] == '-') {
 807                                         if (at != 0)
 808                                                 /* @{-N} not at start */
 809                                                 return -1;
 810                                         nth_prior = 1;
 811                                         continue;
 812                                 }
 813                                 if (!upstream_mark(str + at, len - at) &&
 814                                     !push_mark(str + at, len - at)) {
 815                                         reflog_len = (len-1) - (at+2);
 816                                         len = at;
 817                                 }
 818                                 break;
 819                         }
 820                 }
 821         }
 822
 823         /* Accept only unambiguous ref paths. */
 824         if (len && ambiguous_path(str, len))
 825                 return -1;
 826
 827         if (nth_prior) {
 828                 struct strbuf buf = STRBUF_INIT;
 829                 int detached;
 830
 831                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 832                         detached = (buf.len == the_hash_algo->hexsz && !get_oid_hex(buf.buf, oid));
 833                         strbuf_release(&buf);
 834                         if (detached)
 835                                 return 0;
 836                 }
 837         }
 838
 839         if (!len && reflog_len)
 840                 /* allow "@{...}" to mean the current branch reflog */
 841                 refs_found = dwim_ref("HEAD", 4, oid, &real_ref);
 842         else if (reflog_len)
 843                 refs_found = dwim_log(str, len, oid, &real_ref);
 844         else
 845                 refs_found = dwim_ref(str, len, oid, &real_ref);
 846
 847         if (!refs_found)
 848                 return -1;
 849
 850         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 851             (refs_found > 1 ||
 852              !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
 853                 warning(warn_msg, len, str);
 854
 855         if (reflog_len) {
 856                 int nth, i;
 857                 timestamp_t at_time;
 858                 timestamp_t co_time;
 859                 int co_tz, co_cnt;
 860
 861                 /* Is it asking for N-th entry, or approxidate? */
 862                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 863                         char ch = str[at+2+i];
 864                         if ('0' <= ch && ch <= '9')
 865                                 nth = nth * 10 + ch - '0';
 866                         else
 867                                 nth = -1;
 868                 }
 869                 if (100000000 <= nth) {
 870                         at_time = nth;
 871                         nth = -1;
 872                 } else if (0 <= nth)
 873                         at_time = 0;
 874                 else {
 875                         int errors = 0;
 876                         char *tmp = xstrndup(str + at + 2, reflog_len);
 877                         at_time = approxidate_careful(tmp, &errors);
 878                         free(tmp);
 879                         if (errors) {
 880                                 free(real_ref);
 881                                 return -1;
 882                         }
 883                 }
 884                 if (read_ref_at(real_ref, flags, at_time, nth, oid, NULL,
 885                                 &co_time, &co_tz, &co_cnt)) {
 886                         if (!len) {
 887                                 if (starts_with(real_ref, "refs/heads/")) {
 888                                         str = real_ref + 11;
 889                                         len = strlen(real_ref + 11);
 890                                 } else {
 891                                         /* detached HEAD */
 892                                         str = "HEAD";
 893                                         len = 4;
 894                                 }
 895                         }
 896                         if (at_time) {
 897                                 if (!(flags & GET_OID_QUIETLY)) {
 898                                         warning("Log for '%.*s' only goes "
 899                                                 "back to %s.", len, str,
 900                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 901                                 }
 902                         } else {
 903                                 if (flags & GET_OID_QUIETLY) {
 904                                         exit(128);
 905                                 }
 906                                 die("Log for '%.*s' only has %d entries.",
 907                                     len, str, co_cnt);
 908                         }
 909                 }
 910         }
 911
 912         free(real_ref);
 913         return 0;
 914 }
 915
 916 static int get_parent(const char *name, int len,
 917                       struct object_id *result, int idx)
 918 {
 919         struct object_id oid;
 920         int ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 921         struct commit *commit;
 922         struct commit_list *p;
 923
 924         if (ret)
 925                 return ret;
 926         commit = lookup_commit_reference(the_repository, &oid);
 927         if (parse_commit(commit))
 928                 return -1;
 929         if (!idx) {
 930                 oidcpy(result, &commit->object.oid);
 931                 return 0;
 932         }
 933         p = commit->parents;
 934         while (p) {
 935                 if (!--idx) {
 936                         oidcpy(result, &p->item->object.oid);
 937                         return 0;
 938                 }
 939                 p = p->next;
 940         }
 941         return -1;
 942 }
 943
 944 static int get_nth_ancestor(const char *name, int len,
 945                             struct object_id *result, int generation)
 946 {
 947         struct object_id oid;
 948         struct commit *commit;
 949         int ret;
 950
 951         ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 952         if (ret)
 953                 return ret;
 954         commit = lookup_commit_reference(the_repository, &oid);
 955         if (!commit)
 956                 return -1;
 957
 958         while (generation--) {
 959                 if (parse_commit(commit) || !commit->parents)
 960                         return -1;
 961                 commit = commit->parents->item;
 962         }
 963         oidcpy(result, &commit->object.oid);
 964         return 0;
 965 }
 966
 967 struct object *peel_to_type(const char *name, int namelen,
 968                             struct object *o, enum object_type expected_type)
 969 {
 970         if (name && !namelen)
 971                 namelen = strlen(name);
 972         while (1) {
 973                 if (!o || (!o->parsed && !parse_object(the_repository, &o->oid)))
 974                         return NULL;
 975                 if (expected_type == OBJ_ANY || o->type == expected_type)
 976                         return o;
 977                 if (o->type == OBJ_TAG)
 978                         o = ((struct tag*) o)->tagged;
 979                 else if (o->type == OBJ_COMMIT)
 980                         o = &(get_commit_tree(((struct commit *)o))->object);
 981                 else {
 982                         if (name)
 983                                 error("%.*s: expected %s type, but the object "
 984                                       "dereferences to %s type",
 985                                       namelen, name, type_name(expected_type),
 986                                       type_name(o->type));
 987                         return NULL;
 988                 }
 989         }
 990 }
 991
 992 static int peel_onion(const char *name, int len, struct object_id *oid,
 993                       unsigned lookup_flags)
 994 {
 995         struct object_id outer;
 996         const char *sp;
 997         unsigned int expected_type = 0;
 998         struct object *o;
 999
1000         /*
1001          * "ref^{type}" dereferences ref repeatedly until you cannot
1002          * dereference anymore, or you get an object of given type,
1003          * whichever comes first.  "ref^{}" means just dereference
1004          * tags until you get a non-tag.  "ref^0" is a shorthand for
1005          * "ref^{commit}".  "commit^{tree}" could be used to find the
1006          * top-level tree of the given commit.
1007          */
1008         if (len < 4 || name[len-1] != '}')
1009                 return -1;
1010
1011         for (sp = name + len - 1; name <= sp; sp--) {
1012                 int ch = *sp;
1013                 if (ch == '{' && name < sp && sp[-1] == '^')
1014                         break;
1015         }
1016         if (sp <= name)
1017                 return -1;
1018
1019         sp++; /* beginning of type name, or closing brace for empty */
1020         if (starts_with(sp, "commit}"))
1021                 expected_type = OBJ_COMMIT;
1022         else if (starts_with(sp, "tag}"))
1023                 expected_type = OBJ_TAG;
1024         else if (starts_with(sp, "tree}"))
1025                 expected_type = OBJ_TREE;
1026         else if (starts_with(sp, "blob}"))
1027                 expected_type = OBJ_BLOB;
1028         else if (starts_with(sp, "object}"))
1029                 expected_type = OBJ_ANY;
1030         else if (sp[0] == '}')
1031                 expected_type = OBJ_NONE;
1032         else if (sp[0] == '/')
1033                 expected_type = OBJ_COMMIT;
1034         else
1035                 return -1;
1036
1037         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
1038         if (expected_type == OBJ_COMMIT)
1039                 lookup_flags |= GET_OID_COMMITTISH;
1040         else if (expected_type == OBJ_TREE)
1041                 lookup_flags |= GET_OID_TREEISH;
1042
1043         if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
1044                 return -1;
1045
1046         o = parse_object(the_repository, &outer);
1047         if (!o)
1048                 return -1;
1049         if (!expected_type) {
1050                 o = deref_tag(the_repository, o, name, sp - name - 2);
1051                 if (!o || (!o->parsed && !parse_object(the_repository, &o->oid)))
1052                         return -1;
1053                 oidcpy(oid, &o->oid);
1054                 return 0;
1055         }
1056
1057         /*
1058          * At this point, the syntax look correct, so
1059          * if we do not get the needed object, we should
1060          * barf.
1061          */
1062         o = peel_to_type(name, len, o, expected_type);
1063         if (!o)
1064                 return -1;
1065
1066         oidcpy(oid, &o->oid);
1067         if (sp[0] == '/') {
1068                 /* "$commit^{/foo}" */
1069                 char *prefix;
1070                 int ret;
1071                 struct commit_list *list = NULL;
1072
1073                 /*
1074                  * $commit^{/}. Some regex implementation may reject.
1075                  * We don't need regex anyway. '' pattern always matches.
1076                  */
1077                 if (sp[1] == '}')
1078                         return 0;
1079
1080                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1081                 commit_list_insert((struct commit *)o, &list);
1082                 ret = get_oid_oneline(prefix, oid, list);
1083                 free(prefix);
1084                 return ret;
1085         }
1086         return 0;
1087 }
1088
1089 static int get_describe_name(const char *name, int len, struct object_id *oid)
1090 {
1091         const char *cp;
1092         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1093
1094         for (cp = name + len - 1; name + 2 <= cp; cp--) {
1095                 char ch = *cp;
1096                 if (!isxdigit(ch)) {
1097                         /* We must be looking at g in "SOMETHING-g"
1098                          * for it to be describe output.
1099                          */
1100                         if (ch == 'g' && cp[-1] == '-') {
1101                                 cp++;
1102                                 len -= cp - name;
1103                                 return get_short_oid(cp, len, oid, flags);
1104                         }
1105                 }
1106         }
1107         return -1;
1108 }
1109
1110 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags)
1111 {
1112         int ret, has_suffix;
1113         const char *cp;
1114
1115         /*
1116          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1117          */
1118         has_suffix = 0;
1119         for (cp = name + len - 1; name <= cp; cp--) {
1120                 int ch = *cp;
1121                 if ('0' <= ch && ch <= '9')
1122                         continue;
1123                 if (ch == '~' || ch == '^')
1124                         has_suffix = ch;
1125                 break;
1126         }
1127
1128         if (has_suffix) {
1129                 int num = 0;
1130                 int len1 = cp - name;
1131                 cp++;
1132                 while (cp < name + len)
1133                         num = num * 10 + *cp++ - '0';
1134                 if (!num && len1 == len - 1)
1135                         num = 1;
1136                 if (has_suffix == '^')
1137                         return get_parent(name, len1, oid, num);
1138                 /* else if (has_suffix == '~') -- goes without saying */
1139                 return get_nth_ancestor(name, len1, oid, num);
1140         }
1141
1142         ret = peel_onion(name, len, oid, lookup_flags);
1143         if (!ret)
1144                 return 0;
1145
1146         ret = get_oid_basic(name, len, oid, lookup_flags);
1147         if (!ret)
1148                 return 0;
1149
1150         /* It could be describe output that is "SOMETHING-gXXXX" */
1151         ret = get_describe_name(name, len, oid);
1152         if (!ret)
1153                 return 0;
1154
1155         return get_short_oid(name, len, oid, lookup_flags);
1156 }
1157
1158 /*
1159  * This interprets names like ':/Initial revision of "git"' by searching
1160  * through history and returning the first commit whose message starts
1161  * the given regular expression.
1162  *
1163  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1164  *
1165  * For a literal '!' character at the beginning of a pattern, you have to repeat
1166  * that, like: ':/!!foo'
1167  *
1168  * For future extension, all other sequences beginning with ':/!' are reserved.
1169  */
1170
1171 /* Remember to update object flag allocation in object.h */
1172 #define ONELINE_SEEN (1u<<20)
1173
1174 static int handle_one_ref(const char *path, const struct object_id *oid,
1175                           int flag, void *cb_data)
1176 {
1177         struct commit_list **list = cb_data;
1178         struct object *object = parse_object(the_repository, oid);
1179         if (!object)
1180                 return 0;
1181         if (object->type == OBJ_TAG) {
1182                 object = deref_tag(the_repository, object, path,
1183                                    strlen(path));
1184                 if (!object)
1185                         return 0;
1186         }
1187         if (object->type != OBJ_COMMIT)
1188                 return 0;
1189         commit_list_insert((struct commit *)object, list);
1190         return 0;
1191 }
1192
1193 static int get_oid_oneline(const char *prefix, struct object_id *oid,
1194                             struct commit_list *list)
1195 {
1196         struct commit_list *backup = NULL, *l;
1197         int found = 0;
1198         int negative = 0;
1199         regex_t regex;
1200
1201         if (prefix[0] == '!') {
1202                 prefix++;
1203
1204                 if (prefix[0] == '-') {
1205                         prefix++;
1206                         negative = 1;
1207                 } else if (prefix[0] != '!') {
1208                         return -1;
1209                 }
1210         }
1211
1212         if (regcomp(&regex, prefix, REG_EXTENDED))
1213                 return -1;
1214
1215         for (l = list; l; l = l->next) {
1216                 l->item->object.flags |= ONELINE_SEEN;
1217                 commit_list_insert(l->item, &backup);
1218         }
1219         while (list) {
1220                 const char *p, *buf;
1221                 struct commit *commit;
1222                 int matches;
1223
1224                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1225                 if (!parse_object(the_repository, &commit->object.oid))
1226                         continue;
1227                 buf = get_commit_buffer(commit, NULL);
1228                 p = strstr(buf, "\n\n");
1229                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1230                 unuse_commit_buffer(commit, buf);
1231
1232                 if (matches) {
1233                         oidcpy(oid, &commit->object.oid);
1234                         found = 1;
1235                         break;
1236                 }
1237         }
1238         regfree(&regex);
1239         free_commit_list(list);
1240         for (l = backup; l; l = l->next)
1241                 clear_commit_marks(l->item, ONELINE_SEEN);
1242         free_commit_list(backup);
1243         return found ? 0 : -1;
1244 }
1245
1246 struct grab_nth_branch_switch_cbdata {
1247         int remaining;
1248         struct strbuf buf;
1249 };
1250
1251 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1252                                   const char *email, timestamp_t timestamp, int tz,
1253                                   const char *message, void *cb_data)
1254 {
1255         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1256         const char *match = NULL, *target = NULL;
1257         size_t len;
1258
1259         if (skip_prefix(message, "checkout: moving from ", &match))
1260                 target = strstr(match, " to ");
1261
1262         if (!match || !target)
1263                 return 0;
1264         if (--(cb->remaining) == 0) {
1265                 len = target - match;
1266                 strbuf_reset(&cb->buf);
1267                 strbuf_add(&cb->buf, match, len);
1268                 return 1; /* we are done */
1269         }
1270         return 0;
1271 }
1272
1273 /*
1274  * Parse @{-N} syntax, return the number of characters parsed
1275  * if successful; otherwise signal an error with negative value.
1276  */
1277 static int interpret_nth_prior_checkout(const char *name, int namelen,
1278                                         struct strbuf *buf)
1279 {
1280         long nth;
1281         int retval;
1282         struct grab_nth_branch_switch_cbdata cb;
1283         const char *brace;
1284         char *num_end;
1285
1286         if (namelen < 4)
1287                 return -1;
1288         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1289                 return -1;
1290         brace = memchr(name, '}', namelen);
1291         if (!brace)
1292                 return -1;
1293         nth = strtol(name + 3, &num_end, 10);
1294         if (num_end != brace)
1295                 return -1;
1296         if (nth <= 0)
1297                 return -1;
1298         cb.remaining = nth;
1299         strbuf_init(&cb.buf, 20);
1300
1301         retval = 0;
1302         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1303                 strbuf_reset(buf);
1304                 strbuf_addbuf(buf, &cb.buf);
1305                 retval = brace - name + 1;
1306         }
1307
1308         strbuf_release(&cb.buf);
1309         return retval;
1310 }
1311
1312 int get_oid_mb(const char *name, struct object_id *oid)
1313 {
1314         struct commit *one, *two;
1315         struct commit_list *mbs;
1316         struct object_id oid_tmp;
1317         const char *dots;
1318         int st;
1319
1320         dots = strstr(name, "...");
1321         if (!dots)
1322                 return get_oid(name, oid);
1323         if (dots == name)
1324                 st = get_oid("HEAD", &oid_tmp);
1325         else {
1326                 struct strbuf sb;
1327                 strbuf_init(&sb, dots - name);
1328                 strbuf_add(&sb, name, dots - name);
1329                 st = get_oid_committish(sb.buf, &oid_tmp);
1330                 strbuf_release(&sb);
1331         }
1332         if (st)
1333                 return st;
1334         one = lookup_commit_reference_gently(the_repository, &oid_tmp, 0);
1335         if (!one)
1336                 return -1;
1337
1338         if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1339                 return -1;
1340         two = lookup_commit_reference_gently(the_repository, &oid_tmp, 0);
1341         if (!two)
1342                 return -1;
1343         mbs = get_merge_bases(one, two);
1344         if (!mbs || mbs->next)
1345                 st = -1;
1346         else {
1347                 st = 0;
1348                 oidcpy(oid, &mbs->item->object.oid);
1349         }
1350         free_commit_list(mbs);
1351         return st;
1352 }
1353
1354 /* parse @something syntax, when 'something' is not {.*} */
1355 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1356 {
1357         const char *next;
1358
1359         if (len || name[1] == '{')
1360                 return -1;
1361
1362         /* make sure it's a single @, or @@{.*}, not @foo */
1363         next = memchr(name + len + 1, '@', namelen - len - 1);
1364         if (next && next[1] != '{')
1365                 return -1;
1366         if (!next)
1367                 next = name + namelen;
1368         if (next != name + 1)
1369                 return -1;
1370
1371         strbuf_reset(buf);
1372         strbuf_add(buf, "HEAD", 4);
1373         return 1;
1374 }
1375
1376 static int reinterpret(const char *name, int namelen, int len,
1377                        struct strbuf *buf, unsigned allowed)
1378 {
1379         /* we have extra data, which might need further processing */
1380         struct strbuf tmp = STRBUF_INIT;
1381         int used = buf->len;
1382         int ret;
1383
1384         strbuf_add(buf, name + len, namelen - len);
1385         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1386         /* that data was not interpreted, remove our cruft */
1387         if (ret < 0) {
1388                 strbuf_setlen(buf, used);
1389                 return len;
1390         }
1391         strbuf_reset(buf);
1392         strbuf_addbuf(buf, &tmp);
1393         strbuf_release(&tmp);
1394         /* tweak for size of {-N} versus expanded ref name */
1395         return ret - used + len;
1396 }
1397
1398 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1399 {
1400         char *s = shorten_unambiguous_ref(ref, 0);
1401         strbuf_reset(buf);
1402         strbuf_addstr(buf, s);
1403         free(s);
1404 }
1405
1406 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1407 {
1408         if (!allowed)
1409                 return 1;
1410
1411         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1412             starts_with(refname, "refs/heads/"))
1413                 return 1;
1414         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1415             starts_with(refname, "refs/remotes/"))
1416                 return 1;
1417
1418         return 0;
1419 }
1420
1421 static int interpret_branch_mark(const char *name, int namelen,
1422                                  int at, struct strbuf *buf,
1423                                  int (*get_mark)(const char *, int),
1424                                  const char *(*get_data)(struct branch *,
1425                                                          struct strbuf *),
1426                                  unsigned allowed)
1427 {
1428         int len;
1429         struct branch *branch;
1430         struct strbuf err = STRBUF_INIT;
1431         const char *value;
1432
1433         len = get_mark(name + at, namelen - at);
1434         if (!len)
1435                 return -1;
1436
1437         if (memchr(name, ':', at))
1438                 return -1;
1439
1440         if (at) {
1441                 char *name_str = xmemdupz(name, at);
1442                 branch = branch_get(name_str);
1443                 free(name_str);
1444         } else
1445                 branch = branch_get(NULL);
1446
1447         value = get_data(branch, &err);
1448         if (!value)
1449                 die("%s", err.buf);
1450
1451         if (!branch_interpret_allowed(value, allowed))
1452                 return -1;
1453
1454         set_shortened_ref(buf, value);
1455         return len + at;
1456 }
1457
1458 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1459                           unsigned allowed)
1460 {
1461         char *at;
1462         const char *start;
1463         int len;
1464
1465         if (!namelen)
1466                 namelen = strlen(name);
1467
1468         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1469                 len = interpret_nth_prior_checkout(name, namelen, buf);
1470                 if (!len) {
1471                         return len; /* syntax Ok, not enough switches */
1472                 } else if (len > 0) {
1473                         if (len == namelen)
1474                                 return len; /* consumed all */
1475                         else
1476                                 return reinterpret(name, namelen, len, buf, allowed);
1477                 }
1478         }
1479
1480         for (start = name;
1481              (at = memchr(start, '@', namelen - (start - name)));
1482              start = at + 1) {
1483
1484                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1485                         len = interpret_empty_at(name, namelen, at - name, buf);
1486                         if (len > 0)
1487                                 return reinterpret(name, namelen, len, buf,
1488                                                    allowed);
1489                 }
1490
1491                 len = interpret_branch_mark(name, namelen, at - name, buf,
1492                                             upstream_mark, branch_get_upstream,
1493                                             allowed);
1494                 if (len > 0)
1495                         return len;
1496
1497                 len = interpret_branch_mark(name, namelen, at - name, buf,
1498                                             push_mark, branch_get_push,
1499                                             allowed);
1500                 if (len > 0)
1501                         return len;
1502         }
1503
1504         return -1;
1505 }
1506
1507 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1508 {
1509         int len = strlen(name);
1510         int used = interpret_branch_name(name, len, sb, allowed);
1511
1512         if (used < 0)
1513                 used = 0;
1514         strbuf_add(sb, name + used, len - used);
1515 }
1516
1517 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1518 {
1519         if (startup_info->have_repository)
1520                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1521         else
1522                 strbuf_addstr(sb, name);
1523
1524         /*
1525          * This splice must be done even if we end up rejecting the
1526          * name; builtin/branch.c::copy_or_rename_branch() still wants
1527          * to see what the name expanded to so that "branch -m" can be
1528          * used as a tool to correct earlier mistakes.
1529          */
1530         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1531
1532         if (*name == '-' ||
1533             !strcmp(sb->buf, "refs/heads/HEAD"))
1534                 return -1;
1535
1536         return check_refname_format(sb->buf, 0);
1537 }
1538
1539 /*
1540  * This is like "get_oid_basic()", except it allows "object ID expressions",
1541  * notably "xyz^" for "parent of xyz"
1542  */
1543 int get_oid(const char *name, struct object_id *oid)
1544 {
1545         struct object_context unused;
1546         return get_oid_with_context(name, 0, oid, &unused);
1547 }
1548
1549
1550 /*
1551  * Many callers know that the user meant to name a commit-ish by
1552  * syntactical positions where the object name appears.  Calling this
1553  * function allows the machinery to disambiguate shorter-than-unique
1554  * abbreviated object names between commit-ish and others.
1555  *
1556  * Note that this does NOT error out when the named object is not a
1557  * commit-ish. It is merely to give a hint to the disambiguation
1558  * machinery.
1559  */
1560 int get_oid_committish(const char *name, struct object_id *oid)
1561 {
1562         struct object_context unused;
1563         return get_oid_with_context(name, GET_OID_COMMITTISH,
1564                                     oid, &unused);
1565 }
1566
1567 int get_oid_treeish(const char *name, struct object_id *oid)
1568 {
1569         struct object_context unused;
1570         return get_oid_with_context(name, GET_OID_TREEISH,
1571                                     oid, &unused);
1572 }
1573
1574 int get_oid_commit(const char *name, struct object_id *oid)
1575 {
1576         struct object_context unused;
1577         return get_oid_with_context(name, GET_OID_COMMIT,
1578                                     oid, &unused);
1579 }
1580
1581 int get_oid_tree(const char *name, struct object_id *oid)
1582 {
1583         struct object_context unused;
1584         return get_oid_with_context(name, GET_OID_TREE,
1585                                     oid, &unused);
1586 }
1587
1588 int get_oid_blob(const char *name, struct object_id *oid)
1589 {
1590         struct object_context unused;
1591         return get_oid_with_context(name, GET_OID_BLOB,
1592                                     oid, &unused);
1593 }
1594
1595 /* Must be called only when object_name:filename doesn't exist. */
1596 static void diagnose_invalid_oid_path(const char *prefix,
1597                                       const char *filename,
1598                                       const struct object_id *tree_oid,
1599                                       const char *object_name,
1600                                       int object_name_len)
1601 {
1602         struct object_id oid;
1603         unsigned mode;
1604
1605         if (!prefix)
1606                 prefix = "";
1607
1608         if (file_exists(filename))
1609                 die("Path '%s' exists on disk, but not in '%.*s'.",
1610                     filename, object_name_len, object_name);
1611         if (is_missing_file_error(errno)) {
1612                 char *fullname = xstrfmt("%s%s", prefix, filename);
1613
1614                 if (!get_tree_entry(tree_oid, fullname, &oid, &mode)) {
1615                         die("Path '%s' exists, but not '%s'.\n"
1616                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1617                             fullname,
1618                             filename,
1619                             object_name_len, object_name,
1620                             fullname,
1621                             object_name_len, object_name,
1622                             filename);
1623                 }
1624                 die("Path '%s' does not exist in '%.*s'",
1625                     filename, object_name_len, object_name);
1626         }
1627 }
1628
1629 /* Must be called only when :stage:filename doesn't exist. */
1630 static void diagnose_invalid_index_path(int stage,
1631                                         const char *prefix,
1632                                         const char *filename)
1633 {
1634         const struct cache_entry *ce;
1635         int pos;
1636         unsigned namelen = strlen(filename);
1637         struct strbuf fullname = STRBUF_INIT;
1638
1639         if (!prefix)
1640                 prefix = "";
1641
1642         /* Wrong stage number? */
1643         pos = cache_name_pos(filename, namelen);
1644         if (pos < 0)
1645                 pos = -pos - 1;
1646         if (pos < active_nr) {
1647                 ce = active_cache[pos];
1648                 if (ce_namelen(ce) == namelen &&
1649                     !memcmp(ce->name, filename, namelen))
1650                         die("Path '%s' is in the index, but not at stage %d.\n"
1651                             "Did you mean ':%d:%s'?",
1652                             filename, stage,
1653                             ce_stage(ce), filename);
1654         }
1655
1656         /* Confusion between relative and absolute filenames? */
1657         strbuf_addstr(&fullname, prefix);
1658         strbuf_addstr(&fullname, filename);
1659         pos = cache_name_pos(fullname.buf, fullname.len);
1660         if (pos < 0)
1661                 pos = -pos - 1;
1662         if (pos < active_nr) {
1663                 ce = active_cache[pos];
1664                 if (ce_namelen(ce) == fullname.len &&
1665                     !memcmp(ce->name, fullname.buf, fullname.len))
1666                         die("Path '%s' is in the index, but not '%s'.\n"
1667                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1668                             fullname.buf, filename,
1669                             ce_stage(ce), fullname.buf,
1670                             ce_stage(ce), filename);
1671         }
1672
1673         if (file_exists(filename))
1674                 die("Path '%s' exists on disk, but not in the index.", filename);
1675         if (is_missing_file_error(errno))
1676                 die("Path '%s' does not exist (neither on disk nor in the index).",
1677                     filename);
1678
1679         strbuf_release(&fullname);
1680 }
1681
1682
1683 static char *resolve_relative_path(const char *rel)
1684 {
1685         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1686                 return NULL;
1687
1688         if (!is_inside_work_tree())
1689                 die("relative path syntax can't be used outside working tree.");
1690
1691         /* die() inside prefix_path() if resolved path is outside worktree */
1692         return prefix_path(startup_info->prefix,
1693                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1694                            rel);
1695 }
1696
1697 static int get_oid_with_context_1(const char *name,
1698                                   unsigned flags,
1699                                   const char *prefix,
1700                                   struct object_id *oid,
1701                                   struct object_context *oc)
1702 {
1703         int ret, bracket_depth;
1704         int namelen = strlen(name);
1705         const char *cp;
1706         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1707
1708         if (only_to_die)
1709                 flags |= GET_OID_QUIETLY;
1710
1711         memset(oc, 0, sizeof(*oc));
1712         oc->mode = S_IFINVALID;
1713         strbuf_init(&oc->symlink_path, 0);
1714         ret = get_oid_1(name, namelen, oid, flags);
1715         if (!ret)
1716                 return ret;
1717         /*
1718          * sha1:path --> object name of path in ent sha1
1719          * :path -> object name of absolute path in index
1720          * :./path -> object name of path relative to cwd in index
1721          * :[0-3]:path -> object name of path in index at stage
1722          * :/foo -> recent commit matching foo
1723          */
1724         if (name[0] == ':') {
1725                 int stage = 0;
1726                 const struct cache_entry *ce;
1727                 char *new_path = NULL;
1728                 int pos;
1729                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1730                         struct commit_list *list = NULL;
1731
1732                         for_each_ref(handle_one_ref, &list);
1733                         head_ref(handle_one_ref, &list);
1734                         commit_list_sort_by_date(&list);
1735                         return get_oid_oneline(name + 2, oid, list);
1736                 }
1737                 if (namelen < 3 ||
1738                     name[2] != ':' ||
1739                     name[1] < '0' || '3' < name[1])
1740                         cp = name + 1;
1741                 else {
1742                         stage = name[1] - '0';
1743                         cp = name + 3;
1744                 }
1745                 new_path = resolve_relative_path(cp);
1746                 if (!new_path) {
1747                         namelen = namelen - (cp - name);
1748                 } else {
1749                         cp = new_path;
1750                         namelen = strlen(cp);
1751                 }
1752
1753                 if (flags & GET_OID_RECORD_PATH)
1754                         oc->path = xstrdup(cp);
1755
1756                 if (!active_cache)
1757                         read_cache();
1758                 pos = cache_name_pos(cp, namelen);
1759                 if (pos < 0)
1760                         pos = -pos - 1;
1761                 while (pos < active_nr) {
1762                         ce = active_cache[pos];
1763                         if (ce_namelen(ce) != namelen ||
1764                             memcmp(ce->name, cp, namelen))
1765                                 break;
1766                         if (ce_stage(ce) == stage) {
1767                                 oidcpy(oid, &ce->oid);
1768                                 oc->mode = ce->ce_mode;
1769                                 free(new_path);
1770                                 return 0;
1771                         }
1772                         pos++;
1773                 }
1774                 if (only_to_die && name[1] && name[1] != '/')
1775                         diagnose_invalid_index_path(stage, prefix, cp);
1776                 free(new_path);
1777                 return -1;
1778         }
1779         for (cp = name, bracket_depth = 0; *cp; cp++) {
1780                 if (*cp == '{')
1781                         bracket_depth++;
1782                 else if (bracket_depth && *cp == '}')
1783                         bracket_depth--;
1784                 else if (!bracket_depth && *cp == ':')
1785                         break;
1786         }
1787         if (*cp == ':') {
1788                 struct object_id tree_oid;
1789                 int len = cp - name;
1790                 unsigned sub_flags = flags;
1791
1792                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1793                 sub_flags |= GET_OID_TREEISH;
1794
1795                 if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1796                         const char *filename = cp+1;
1797                         char *new_filename = NULL;
1798
1799                         new_filename = resolve_relative_path(filename);
1800                         if (new_filename)
1801                                 filename = new_filename;
1802                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1803                                 ret = get_tree_entry_follow_symlinks(&tree_oid,
1804                                         filename, oid, &oc->symlink_path,
1805                                         &oc->mode);
1806                         } else {
1807                                 ret = get_tree_entry(&tree_oid, filename, oid,
1808                                                      &oc->mode);
1809                                 if (ret && only_to_die) {
1810                                         diagnose_invalid_oid_path(prefix,
1811                                                                    filename,
1812                                                                    &tree_oid,
1813                                                                    name, len);
1814                                 }
1815                         }
1816                         if (flags & GET_OID_RECORD_PATH)
1817                                 oc->path = xstrdup(filename);
1818
1819                         free(new_filename);
1820                         return ret;
1821                 } else {
1822                         if (only_to_die)
1823                                 die("Invalid object name '%.*s'.", len, name);
1824                 }
1825         }
1826         return ret;
1827 }
1828
1829 /*
1830  * Call this function when you know "name" given by the end user must
1831  * name an object but it doesn't; the function _may_ die with a better
1832  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1833  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1834  * you have a chance to diagnose the error further.
1835  */
1836 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1837 {
1838         struct object_context oc;
1839         struct object_id oid;
1840         get_oid_with_context_1(name, GET_OID_ONLY_TO_DIE, prefix, &oid, &oc);
1841 }
1842
1843 int get_oid_with_context(const char *str, unsigned flags, struct object_id *oid, struct object_context *oc)
1844 {
1845         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1846                 BUG("incompatible flags for get_sha1_with_context");
1847         return get_oid_with_context_1(str, flags, NULL, oid, oc);
1848 }