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 "submodule.h"
  16 #include "midx.h"
  17 #include "commit-reach.h"
  18
  19 static int get_oid_oneline(struct repository *r, const char *, struct object_id *, struct commit_list *);
  20
  21 typedef int (*disambiguate_hint_fn)(struct repository *, const struct object_id *, void *);
  22
  23 struct disambiguate_state {
  24         int len; /* length of prefix in hex chars */
  25         char hex_pfx[GIT_MAX_HEXSZ + 1];
  26         struct object_id bin_pfx;
  27
  28         struct repository *repo;
  29         disambiguate_hint_fn fn;
  30         void *cb_data;
  31         struct object_id candidate;
  32         unsigned candidate_exists:1;
  33         unsigned candidate_checked:1;
  34         unsigned candidate_ok:1;
  35         unsigned disambiguate_fn_used:1;
  36         unsigned ambiguous:1;
  37         unsigned always_call_fn:1;
  38 };
  39
  40 static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
  41 {
  42         if (ds->always_call_fn) {
  43                 ds->ambiguous = ds->fn(ds->repo, current, ds->cb_data) ? 1 : 0;
  44                 return;
  45         }
  46         if (!ds->candidate_exists) {
  47                 /* this is the first candidate */
  48                 oidcpy(&ds->candidate, current);
  49                 ds->candidate_exists = 1;
  50                 return;
  51         } else if (oideq(&ds->candidate, current)) {
  52                 /* the same as what we already have seen */
  53                 return;
  54         }
  55
  56         if (!ds->fn) {
  57                 /* cannot disambiguate between ds->candidate and current */
  58                 ds->ambiguous = 1;
  59                 return;
  60         }
  61
  62         if (!ds->candidate_checked) {
  63                 ds->candidate_ok = ds->fn(ds->repo, &ds->candidate, ds->cb_data);
  64                 ds->disambiguate_fn_used = 1;
  65                 ds->candidate_checked = 1;
  66         }
  67
  68         if (!ds->candidate_ok) {
  69                 /* discard the candidate; we know it does not satisfy fn */
  70                 oidcpy(&ds->candidate, current);
  71                 ds->candidate_checked = 0;
  72                 return;
  73         }
  74
  75         /* if we reach this point, we know ds->candidate satisfies fn */
  76         if (ds->fn(ds->repo, current, ds->cb_data)) {
  77                 /*
  78                  * if both current and candidate satisfy fn, we cannot
  79                  * disambiguate.
  80                  */
  81                 ds->candidate_ok = 0;
  82                 ds->ambiguous = 1;
  83         }
  84
  85         /* otherwise, current can be discarded and candidate is still good */
  86 }
  87
  88 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  89
  90 static void find_short_object_filename(struct disambiguate_state *ds)
  91 {
  92         struct object_directory *odb;
  93
  94         for (odb = ds->repo->objects->odb; odb && !ds->ambiguous; odb = odb->next) {
  95                 int pos;
  96                 struct oid_array *loose_objects;
  97
  98                 loose_objects = odb_loose_cache(odb, &ds->bin_pfx);
  99                 pos = oid_array_lookup(loose_objects, &ds->bin_pfx);
 100                 if (pos < 0)
 101                         pos = -1 - pos;
 102                 while (!ds->ambiguous && pos < loose_objects->nr) {
 103                         const struct object_id *oid;
 104                         oid = loose_objects->oid + pos;
 105                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 106                                 break;
 107                         update_candidates(ds, oid);
 108                         pos++;
 109                 }
 110         }
 111 }
 112
 113 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 114 {
 115         do {
 116                 if (*a != *b)
 117                         return 0;
 118                 a++;
 119                 b++;
 120                 len -= 2;
 121         } while (len > 1);
 122         if (len)
 123                 if ((*a ^ *b) & 0xf0)
 124                         return 0;
 125         return 1;
 126 }
 127
 128 static void unique_in_midx(struct multi_pack_index *m,
 129                            struct disambiguate_state *ds)
 130 {
 131         uint32_t num, i, first = 0;
 132         const struct object_id *current = NULL;
 133         num = m->num_objects;
 134
 135         if (!num)
 136                 return;
 137
 138         bsearch_midx(&ds->bin_pfx, m, &first);
 139
 140         /*
 141          * At this point, "first" is the location of the lowest object
 142          * with an object name that could match "bin_pfx".  See if we have
 143          * 0, 1 or more objects that actually match(es).
 144          */
 145         for (i = first; i < num && !ds->ambiguous; i++) {
 146                 struct object_id oid;
 147                 current = nth_midxed_object_oid(&oid, m, i);
 148                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 149                         break;
 150                 update_candidates(ds, current);
 151         }
 152 }
 153
 154 static void unique_in_pack(struct packed_git *p,
 155                            struct disambiguate_state *ds)
 156 {
 157         uint32_t num, i, first = 0;
 158         const struct object_id *current = NULL;
 159
 160         if (open_pack_index(p) || !p->num_objects)
 161                 return;
 162
 163         num = p->num_objects;
 164         bsearch_pack(&ds->bin_pfx, p, &first);
 165
 166         /*
 167          * At this point, "first" is the location of the lowest object
 168          * with an object name that could match "bin_pfx".  See if we have
 169          * 0, 1 or more objects that actually match(es).
 170          */
 171         for (i = first; i < num && !ds->ambiguous; i++) {
 172                 struct object_id oid;
 173                 current = nth_packed_object_oid(&oid, p, i);
 174                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 175                         break;
 176                 update_candidates(ds, current);
 177         }
 178 }
 179
 180 static void find_short_packed_object(struct disambiguate_state *ds)
 181 {
 182         struct multi_pack_index *m;
 183         struct packed_git *p;
 184
 185         for (m = get_multi_pack_index(ds->repo); m && !ds->ambiguous;
 186              m = m->next)
 187                 unique_in_midx(m, ds);
 188         for (p = get_packed_git(ds->repo); p && !ds->ambiguous;
 189              p = p->next)
 190                 unique_in_pack(p, ds);
 191 }
 192
 193 static int finish_object_disambiguation(struct disambiguate_state *ds,
 194                                         struct object_id *oid)
 195 {
 196         if (ds->ambiguous)
 197                 return SHORT_NAME_AMBIGUOUS;
 198
 199         if (!ds->candidate_exists)
 200                 return MISSING_OBJECT;
 201
 202         if (!ds->candidate_checked)
 203                 /*
 204                  * If this is the only candidate, there is no point
 205                  * calling the disambiguation hint callback.
 206                  *
 207                  * On the other hand, if the current candidate
 208                  * replaced an earlier candidate that did _not_ pass
 209                  * the disambiguation hint callback, then we do have
 210                  * more than one objects that match the short name
 211                  * given, so we should make sure this one matches;
 212                  * otherwise, if we discovered this one and the one
 213                  * that we previously discarded in the reverse order,
 214                  * we would end up showing different results in the
 215                  * same repository!
 216                  */
 217                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 218                                     ds->fn(ds->repo, &ds->candidate, ds->cb_data));
 219
 220         if (!ds->candidate_ok)
 221                 return SHORT_NAME_AMBIGUOUS;
 222
 223         oidcpy(oid, &ds->candidate);
 224         return 0;
 225 }
 226
 227 static int disambiguate_commit_only(struct repository *r,
 228                                     const struct object_id *oid,
 229                                     void *cb_data_unused)
 230 {
 231         int kind = oid_object_info(r, oid, NULL);
 232         return kind == OBJ_COMMIT;
 233 }
 234
 235 static int disambiguate_committish_only(struct repository *r,
 236                                         const struct object_id *oid,
 237                                         void *cb_data_unused)
 238 {
 239         struct object *obj;
 240         int kind;
 241
 242         kind = oid_object_info(r, oid, NULL);
 243         if (kind == OBJ_COMMIT)
 244                 return 1;
 245         if (kind != OBJ_TAG)
 246                 return 0;
 247
 248         /* We need to do this the hard way... */
 249         obj = deref_tag(r, parse_object(r, oid), NULL, 0);
 250         if (obj && obj->type == OBJ_COMMIT)
 251                 return 1;
 252         return 0;
 253 }
 254
 255 static int disambiguate_tree_only(struct repository *r,
 256                                   const struct object_id *oid,
 257                                   void *cb_data_unused)
 258 {
 259         int kind = oid_object_info(r, oid, NULL);
 260         return kind == OBJ_TREE;
 261 }
 262
 263 static int disambiguate_treeish_only(struct repository *r,
 264                                      const struct object_id *oid,
 265                                      void *cb_data_unused)
 266 {
 267         struct object *obj;
 268         int kind;
 269
 270         kind = oid_object_info(r, oid, NULL);
 271         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 272                 return 1;
 273         if (kind != OBJ_TAG)
 274                 return 0;
 275
 276         /* We need to do this the hard way... */
 277         obj = deref_tag(r, parse_object(r, oid), NULL, 0);
 278         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 279                 return 1;
 280         return 0;
 281 }
 282
 283 static int disambiguate_blob_only(struct repository *r,
 284                                   const struct object_id *oid,
 285                                   void *cb_data_unused)
 286 {
 287         int kind = oid_object_info(r, oid, NULL);
 288         return kind == OBJ_BLOB;
 289 }
 290
 291 static disambiguate_hint_fn default_disambiguate_hint;
 292
 293 int set_disambiguate_hint_config(const char *var, const char *value)
 294 {
 295         static const struct {
 296                 const char *name;
 297                 disambiguate_hint_fn fn;
 298         } hints[] = {
 299                 { "none", NULL },
 300                 { "commit", disambiguate_commit_only },
 301                 { "committish", disambiguate_committish_only },
 302                 { "tree", disambiguate_tree_only },
 303                 { "treeish", disambiguate_treeish_only },
 304                 { "blob", disambiguate_blob_only }
 305         };
 306         int i;
 307
 308         if (!value)
 309                 return config_error_nonbool(var);
 310
 311         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 312                 if (!strcasecmp(value, hints[i].name)) {
 313                         default_disambiguate_hint = hints[i].fn;
 314                         return 0;
 315                 }
 316         }
 317
 318         return error("unknown hint type for '%s': %s", var, value);
 319 }
 320
 321 static int init_object_disambiguation(struct repository *r,
 322                                       const char *name, int len,
 323                                       struct disambiguate_state *ds)
 324 {
 325         int i;
 326
 327         if (len < MINIMUM_ABBREV || len > the_hash_algo->hexsz)
 328                 return -1;
 329
 330         memset(ds, 0, sizeof(*ds));
 331
 332         for (i = 0; i < len ;i++) {
 333                 unsigned char c = name[i];
 334                 unsigned char val;
 335                 if (c >= '0' && c <= '9')
 336                         val = c - '0';
 337                 else if (c >= 'a' && c <= 'f')
 338                         val = c - 'a' + 10;
 339                 else if (c >= 'A' && c <='F') {
 340                         val = c - 'A' + 10;
 341                         c -= 'A' - 'a';
 342                 }
 343                 else
 344                         return -1;
 345                 ds->hex_pfx[i] = c;
 346                 if (!(i & 1))
 347                         val <<= 4;
 348                 ds->bin_pfx.hash[i >> 1] |= val;
 349         }
 350
 351         ds->len = len;
 352         ds->hex_pfx[len] = '\0';
 353         ds->repo = r;
 354         prepare_alt_odb(r);
 355         return 0;
 356 }
 357
 358 static int show_ambiguous_object(const struct object_id *oid, void *data)
 359 {
 360         const struct disambiguate_state *ds = data;
 361         struct strbuf desc = STRBUF_INIT;
 362         int type;
 363
 364         if (ds->fn && !ds->fn(ds->repo, oid, ds->cb_data))
 365                 return 0;
 366
 367         type = oid_object_info(ds->repo, oid, NULL);
 368         if (type == OBJ_COMMIT) {
 369                 struct commit *commit = lookup_commit(ds->repo, oid);
 370                 if (commit) {
 371                         struct pretty_print_context pp = {0};
 372                         pp.date_mode.type = DATE_SHORT;
 373                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 374                 }
 375         } else if (type == OBJ_TAG) {
 376                 struct tag *tag = lookup_tag(ds->repo, oid);
 377                 if (!parse_tag(tag) && tag->tag)
 378                         strbuf_addf(&desc, " %s", tag->tag);
 379         }
 380
 381         advise("  %s %s%s",
 382                repo_find_unique_abbrev(ds->repo, oid, DEFAULT_ABBREV),
 383                type_name(type) ? type_name(type) : "unknown type",
 384                desc.buf);
 385
 386         strbuf_release(&desc);
 387         return 0;
 388 }
 389
 390 static int collect_ambiguous(const struct object_id *oid, void *data)
 391 {
 392         oid_array_append(data, oid);
 393         return 0;
 394 }
 395
 396 static int repo_collect_ambiguous(struct repository *r,
 397                                   const struct object_id *oid,
 398                                   void *data)
 399 {
 400         return collect_ambiguous(oid, data);
 401 }
 402
 403 static struct repository *sort_ambiguous_repo;
 404 static int sort_ambiguous(const void *a, const void *b)
 405 {
 406         int a_type = oid_object_info(sort_ambiguous_repo, a, NULL);
 407         int b_type = oid_object_info(sort_ambiguous_repo, b, NULL);
 408         int a_type_sort;
 409         int b_type_sort;
 410
 411         /*
 412          * Sorts by hash within the same object type, just as
 413          * oid_array_for_each_unique() would do.
 414          */
 415         if (a_type == b_type)
 416                 return oidcmp(a, b);
 417
 418         /*
 419          * Between object types show tags, then commits, and finally
 420          * trees and blobs.
 421          *
 422          * The object_type enum is commit, tree, blob, tag, but we
 423          * want tag, commit, tree blob. Cleverly (perhaps too
 424          * cleverly) do that with modulus, since the enum assigns 1 to
 425          * commit, so tag becomes 0.
 426          */
 427         a_type_sort = a_type % 4;
 428         b_type_sort = b_type % 4;
 429         return a_type_sort > b_type_sort ? 1 : -1;
 430 }
 431
 432 static void sort_ambiguous_oid_array(struct repository *r, struct oid_array *a)
 433 {
 434         /* mutex will be needed if this code is to be made thread safe */
 435         sort_ambiguous_repo = r;
 436         QSORT(a->oid, a->nr, sort_ambiguous);
 437         sort_ambiguous_repo = NULL;
 438 }
 439
 440 static enum get_oid_result get_short_oid(struct repository *r,
 441                                          const char *name, int len,
 442                                          struct object_id *oid,
 443                                          unsigned flags)
 444 {
 445         int status;
 446         struct disambiguate_state ds;
 447         int quietly = !!(flags & GET_OID_QUIETLY);
 448
 449         if (init_object_disambiguation(r, name, len, &ds) < 0)
 450                 return -1;
 451
 452         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 453                 BUG("multiple get_short_oid disambiguator flags");
 454
 455         if (flags & GET_OID_COMMIT)
 456                 ds.fn = disambiguate_commit_only;
 457         else if (flags & GET_OID_COMMITTISH)
 458                 ds.fn = disambiguate_committish_only;
 459         else if (flags & GET_OID_TREE)
 460                 ds.fn = disambiguate_tree_only;
 461         else if (flags & GET_OID_TREEISH)
 462                 ds.fn = disambiguate_treeish_only;
 463         else if (flags & GET_OID_BLOB)
 464                 ds.fn = disambiguate_blob_only;
 465         else
 466                 ds.fn = default_disambiguate_hint;
 467
 468         find_short_object_filename(&ds);
 469         find_short_packed_object(&ds);
 470         status = finish_object_disambiguation(&ds, oid);
 471
 472         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 473                 struct oid_array collect = OID_ARRAY_INIT;
 474
 475                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 476
 477                 /*
 478                  * We may still have ambiguity if we simply saw a series of
 479                  * candidates that did not satisfy our hint function. In
 480                  * that case, we still want to show them, so disable the hint
 481                  * function entirely.
 482                  */
 483                 if (!ds.ambiguous)
 484                         ds.fn = NULL;
 485
 486                 advise(_("The candidates are:"));
 487                 repo_for_each_abbrev(r, ds.hex_pfx, collect_ambiguous, &collect);
 488                 sort_ambiguous_oid_array(r, &collect);
 489
 490                 if (oid_array_for_each(&collect, show_ambiguous_object, &ds))
 491                         BUG("show_ambiguous_object shouldn't return non-zero");
 492                 oid_array_clear(&collect);
 493         }
 494
 495         return status;
 496 }
 497
 498 int repo_for_each_abbrev(struct repository *r, const char *prefix,
 499                          each_abbrev_fn fn, void *cb_data)
 500 {
 501         struct oid_array collect = OID_ARRAY_INIT;
 502         struct disambiguate_state ds;
 503         int ret;
 504
 505         if (init_object_disambiguation(r, prefix, strlen(prefix), &ds) < 0)
 506                 return -1;
 507
 508         ds.always_call_fn = 1;
 509         ds.fn = repo_collect_ambiguous;
 510         ds.cb_data = &collect;
 511         find_short_object_filename(&ds);
 512         find_short_packed_object(&ds);
 513
 514         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 515         oid_array_clear(&collect);
 516         return ret;
 517 }
 518
 519 /*
 520  * Return the slot of the most-significant bit set in "val". There are various
 521  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 522  * probably not a big deal here.
 523  */
 524 static unsigned msb(unsigned long val)
 525 {
 526         unsigned r = 0;
 527         while (val >>= 1)
 528                 r++;
 529         return r;
 530 }
 531
 532 struct min_abbrev_data {
 533         unsigned int init_len;
 534         unsigned int cur_len;
 535         char *hex;
 536         struct repository *repo;
 537         const struct object_id *oid;
 538 };
 539
 540 static inline char get_hex_char_from_oid(const struct object_id *oid,
 541                                          unsigned int pos)
 542 {
 543         static const char hex[] = "0123456789abcdef";
 544
 545         if ((pos & 1) == 0)
 546                 return hex[oid->hash[pos >> 1] >> 4];
 547         else
 548                 return hex[oid->hash[pos >> 1] & 0xf];
 549 }
 550
 551 static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
 552 {
 553         struct min_abbrev_data *mad = cb_data;
 554
 555         unsigned int i = mad->init_len;
 556         while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
 557                 i++;
 558
 559         if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
 560                 mad->cur_len = i + 1;
 561
 562         return 0;
 563 }
 564
 565 static int repo_extend_abbrev_len(struct repository *r,
 566                                   const struct object_id *oid,
 567                                   void *cb_data)
 568 {
 569         return extend_abbrev_len(oid, cb_data);
 570 }
 571
 572 static void find_abbrev_len_for_midx(struct multi_pack_index *m,
 573                                      struct min_abbrev_data *mad)
 574 {
 575         int match = 0;
 576         uint32_t num, first = 0;
 577         struct object_id oid;
 578         const struct object_id *mad_oid;
 579
 580         if (!m->num_objects)
 581                 return;
 582
 583         num = m->num_objects;
 584         mad_oid = mad->oid;
 585         match = bsearch_midx(mad_oid, m, &first);
 586
 587         /*
 588          * first is now the position in the packfile where we would insert
 589          * mad->hash if it does not exist (or the position of mad->hash if
 590          * it does exist). Hence, we consider a maximum of two objects
 591          * nearby for the abbreviation length.
 592          */
 593         mad->init_len = 0;
 594         if (!match) {
 595                 if (nth_midxed_object_oid(&oid, m, first))
 596                         extend_abbrev_len(&oid, mad);
 597         } else if (first < num - 1) {
 598                 if (nth_midxed_object_oid(&oid, m, first + 1))
 599                         extend_abbrev_len(&oid, mad);
 600         }
 601         if (first > 0) {
 602                 if (nth_midxed_object_oid(&oid, m, first - 1))
 603                         extend_abbrev_len(&oid, mad);
 604         }
 605         mad->init_len = mad->cur_len;
 606 }
 607
 608 static void find_abbrev_len_for_pack(struct packed_git *p,
 609                                      struct min_abbrev_data *mad)
 610 {
 611         int match = 0;
 612         uint32_t num, first = 0;
 613         struct object_id oid;
 614         const struct object_id *mad_oid;
 615
 616         if (open_pack_index(p) || !p->num_objects)
 617                 return;
 618
 619         num = p->num_objects;
 620         mad_oid = mad->oid;
 621         match = bsearch_pack(mad_oid, p, &first);
 622
 623         /*
 624          * first is now the position in the packfile where we would insert
 625          * mad->hash if it does not exist (or the position of mad->hash if
 626          * it does exist). Hence, we consider a maximum of two objects
 627          * nearby for the abbreviation length.
 628          */
 629         mad->init_len = 0;
 630         if (!match) {
 631                 if (nth_packed_object_oid(&oid, p, first))
 632                         extend_abbrev_len(&oid, mad);
 633         } else if (first < num - 1) {
 634                 if (nth_packed_object_oid(&oid, p, first + 1))
 635                         extend_abbrev_len(&oid, mad);
 636         }
 637         if (first > 0) {
 638                 if (nth_packed_object_oid(&oid, p, first - 1))
 639                         extend_abbrev_len(&oid, mad);
 640         }
 641         mad->init_len = mad->cur_len;
 642 }
 643
 644 static void find_abbrev_len_packed(struct min_abbrev_data *mad)
 645 {
 646         struct multi_pack_index *m;
 647         struct packed_git *p;
 648
 649         for (m = get_multi_pack_index(mad->repo); m; m = m->next)
 650                 find_abbrev_len_for_midx(m, mad);
 651         for (p = get_packed_git(mad->repo); p; p = p->next)
 652                 find_abbrev_len_for_pack(p, mad);
 653 }
 654
 655 int repo_find_unique_abbrev_r(struct repository *r, char *hex,
 656                               const struct object_id *oid, int len)
 657 {
 658         struct disambiguate_state ds;
 659         struct min_abbrev_data mad;
 660         struct object_id oid_ret;
 661         const unsigned hexsz = r->hash_algo->hexsz;
 662
 663         if (len < 0) {
 664                 unsigned long count = repo_approximate_object_count(r);
 665                 /*
 666                  * Add one because the MSB only tells us the highest bit set,
 667                  * not including the value of all the _other_ bits (so "15"
 668                  * is only one off of 2^4, but the MSB is the 3rd bit.
 669                  */
 670                 len = msb(count) + 1;
 671                 /*
 672                  * We now know we have on the order of 2^len objects, which
 673                  * expects a collision at 2^(len/2). But we also care about hex
 674                  * chars, not bits, and there are 4 bits per hex. So all
 675                  * together we need to divide by 2 and round up.
 676                  */
 677                 len = DIV_ROUND_UP(len, 2);
 678                 /*
 679                  * For very small repos, we stick with our regular fallback.
 680                  */
 681                 if (len < FALLBACK_DEFAULT_ABBREV)
 682                         len = FALLBACK_DEFAULT_ABBREV;
 683         }
 684
 685         oid_to_hex_r(hex, oid);
 686         if (len == hexsz || !len)
 687                 return hexsz;
 688
 689         mad.repo = r;
 690         mad.init_len = len;
 691         mad.cur_len = len;
 692         mad.hex = hex;
 693         mad.oid = oid;
 694
 695         find_abbrev_len_packed(&mad);
 696
 697         if (init_object_disambiguation(r, hex, mad.cur_len, &ds) < 0)
 698                 return -1;
 699
 700         ds.fn = repo_extend_abbrev_len;
 701         ds.always_call_fn = 1;
 702         ds.cb_data = (void *)&mad;
 703
 704         find_short_object_filename(&ds);
 705         (void)finish_object_disambiguation(&ds, &oid_ret);
 706
 707         hex[mad.cur_len] = 0;
 708         return mad.cur_len;
 709 }
 710
 711 const char *repo_find_unique_abbrev(struct repository *r,
 712                                     const struct object_id *oid,
 713                                     int len)
 714 {
 715         static int bufno;
 716         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 717         char *hex = hexbuffer[bufno];
 718         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 719         repo_find_unique_abbrev_r(r, hex, oid, len);
 720         return hex;
 721 }
 722
 723 static int ambiguous_path(const char *path, int len)
 724 {
 725         int slash = 1;
 726         int cnt;
 727
 728         for (cnt = 0; cnt < len; cnt++) {
 729                 switch (*path++) {
 730                 case '\0':
 731                         break;
 732                 case '/':
 733                         if (slash)
 734                                 break;
 735                         slash = 1;
 736                         continue;
 737                 case '.':
 738                         continue;
 739                 default:
 740                         slash = 0;
 741                         continue;
 742                 }
 743                 break;
 744         }
 745         return slash;
 746 }
 747
 748 static inline int at_mark(const char *string, int len,
 749                           const char **suffix, int nr)
 750 {
 751         int i;
 752
 753         for (i = 0; i < nr; i++) {
 754                 int suffix_len = strlen(suffix[i]);
 755                 if (suffix_len <= len
 756                     && !strncasecmp(string, suffix[i], suffix_len))
 757                         return suffix_len;
 758         }
 759         return 0;
 760 }
 761
 762 static inline int upstream_mark(const char *string, int len)
 763 {
 764         const char *suffix[] = { "@{upstream}", "@{u}" };
 765         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 766 }
 767
 768 static inline int push_mark(const char *string, int len)
 769 {
 770         const char *suffix[] = { "@{push}" };
 771         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 772 }
 773
 774 static enum get_oid_result get_oid_1(struct repository *r, const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 775 static int interpret_nth_prior_checkout(struct repository *r, const char *name, int namelen, struct strbuf *buf);
 776
 777 static int get_oid_basic(struct repository *r, const char *str, int len,
 778                          struct object_id *oid, unsigned int flags)
 779 {
 780         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 781         static const char *object_name_msg = N_(
 782         "Git normally never creates a ref that ends with 40 hex characters\n"
 783         "because it will be ignored when you just specify 40-hex. These refs\n"
 784         "may be created by mistake. For example,\n"
 785         "\n"
 786         "  git checkout -b $br $(git rev-parse ...)\n"
 787         "\n"
 788         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 789         "examine these refs and maybe delete them. Turn this message off by\n"
 790         "running \"git config advice.objectNameWarning false\"");
 791         struct object_id tmp_oid;
 792         char *real_ref = NULL;
 793         int refs_found = 0;
 794         int at, reflog_len, nth_prior = 0;
 795
 796         if (len == r->hash_algo->hexsz && !get_oid_hex(str, oid)) {
 797                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 798                         refs_found = repo_dwim_ref(r, str, len, &tmp_oid, &real_ref);
 799                         if (refs_found > 0) {
 800                                 warning(warn_msg, len, str);
 801                                 if (advice_object_name_warning)
 802                                         fprintf(stderr, "%s\n", _(object_name_msg));
 803                         }
 804                         free(real_ref);
 805                 }
 806                 return 0;
 807         }
 808
 809         /* basic@{time or number or -number} format to query ref-log */
 810         reflog_len = at = 0;
 811         if (len && str[len-1] == '}') {
 812                 for (at = len-4; at >= 0; at--) {
 813                         if (str[at] == '@' && str[at+1] == '{') {
 814                                 if (str[at+2] == '-') {
 815                                         if (at != 0)
 816                                                 /* @{-N} not at start */
 817                                                 return -1;
 818                                         nth_prior = 1;
 819                                         continue;
 820                                 }
 821                                 if (!upstream_mark(str + at, len - at) &&
 822                                     !push_mark(str + at, len - at)) {
 823                                         reflog_len = (len-1) - (at+2);
 824                                         len = at;
 825                                 }
 826                                 break;
 827                         }
 828                 }
 829         }
 830
 831         /* Accept only unambiguous ref paths. */
 832         if (len && ambiguous_path(str, len))
 833                 return -1;
 834
 835         if (nth_prior) {
 836                 struct strbuf buf = STRBUF_INIT;
 837                 int detached;
 838
 839                 if (interpret_nth_prior_checkout(r, str, len, &buf) > 0) {
 840                         detached = (buf.len == r->hash_algo->hexsz && !get_oid_hex(buf.buf, oid));
 841                         strbuf_release(&buf);
 842                         if (detached)
 843                                 return 0;
 844                 }
 845         }
 846
 847         if (!len && reflog_len)
 848                 /* allow "@{...}" to mean the current branch reflog */
 849                 refs_found = repo_dwim_ref(r, "HEAD", 4, oid, &real_ref);
 850         else if (reflog_len)
 851                 refs_found = repo_dwim_log(r, str, len, oid, &real_ref);
 852         else
 853                 refs_found = repo_dwim_ref(r, str, len, oid, &real_ref);
 854
 855         if (!refs_found)
 856                 return -1;
 857
 858         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 859             (refs_found > 1 ||
 860              !get_short_oid(r, str, len, &tmp_oid, GET_OID_QUIETLY)))
 861                 warning(warn_msg, len, str);
 862
 863         if (reflog_len) {
 864                 int nth, i;
 865                 timestamp_t at_time;
 866                 timestamp_t co_time;
 867                 int co_tz, co_cnt;
 868
 869                 /* Is it asking for N-th entry, or approxidate? */
 870                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 871                         char ch = str[at+2+i];
 872                         if ('0' <= ch && ch <= '9')
 873                                 nth = nth * 10 + ch - '0';
 874                         else
 875                                 nth = -1;
 876                 }
 877                 if (100000000 <= nth) {
 878                         at_time = nth;
 879                         nth = -1;
 880                 } else if (0 <= nth)
 881                         at_time = 0;
 882                 else {
 883                         int errors = 0;
 884                         char *tmp = xstrndup(str + at + 2, reflog_len);
 885                         at_time = approxidate_careful(tmp, &errors);
 886                         free(tmp);
 887                         if (errors) {
 888                                 free(real_ref);
 889                                 return -1;
 890                         }
 891                 }
 892                 if (read_ref_at(get_main_ref_store(r),
 893                                 real_ref, flags, at_time, nth, oid, NULL,
 894                                 &co_time, &co_tz, &co_cnt)) {
 895                         if (!len) {
 896                                 if (starts_with(real_ref, "refs/heads/")) {
 897                                         str = real_ref + 11;
 898                                         len = strlen(real_ref + 11);
 899                                 } else {
 900                                         /* detached HEAD */
 901                                         str = "HEAD";
 902                                         len = 4;
 903                                 }
 904                         }
 905                         if (at_time) {
 906                                 if (!(flags & GET_OID_QUIETLY)) {
 907                                         warning("Log for '%.*s' only goes "
 908                                                 "back to %s.", len, str,
 909                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 910                                 }
 911                         } else {
 912                                 if (flags & GET_OID_QUIETLY) {
 913                                         exit(128);
 914                                 }
 915                                 die("Log for '%.*s' only has %d entries.",
 916                                     len, str, co_cnt);
 917                         }
 918                 }
 919         }
 920
 921         free(real_ref);
 922         return 0;
 923 }
 924
 925 static enum get_oid_result get_parent(struct repository *r,
 926                                       const char *name, int len,
 927                                       struct object_id *result, int idx)
 928 {
 929         struct object_id oid;
 930         enum get_oid_result ret = get_oid_1(r, name, len, &oid,
 931                                             GET_OID_COMMITTISH);
 932         struct commit *commit;
 933         struct commit_list *p;
 934
 935         if (ret)
 936                 return ret;
 937         commit = lookup_commit_reference(r, &oid);
 938         if (parse_commit(commit))
 939                 return MISSING_OBJECT;
 940         if (!idx) {
 941                 oidcpy(result, &commit->object.oid);
 942                 return FOUND;
 943         }
 944         p = commit->parents;
 945         while (p) {
 946                 if (!--idx) {
 947                         oidcpy(result, &p->item->object.oid);
 948                         return FOUND;
 949                 }
 950                 p = p->next;
 951         }
 952         return MISSING_OBJECT;
 953 }
 954
 955 static enum get_oid_result get_nth_ancestor(struct repository *r,
 956                                             const char *name, int len,
 957                                             struct object_id *result,
 958                                             int generation)
 959 {
 960         struct object_id oid;
 961         struct commit *commit;
 962         int ret;
 963
 964         ret = get_oid_1(r, name, len, &oid, GET_OID_COMMITTISH);
 965         if (ret)
 966                 return ret;
 967         commit = lookup_commit_reference(r, &oid);
 968         if (!commit)
 969                 return MISSING_OBJECT;
 970
 971         while (generation--) {
 972                 if (parse_commit(commit) || !commit->parents)
 973                         return MISSING_OBJECT;
 974                 commit = commit->parents->item;
 975         }
 976         oidcpy(result, &commit->object.oid);
 977         return FOUND;
 978 }
 979
 980 struct object *repo_peel_to_type(struct repository *r, const char *name, int namelen,
 981                                  struct object *o, enum object_type expected_type)
 982 {
 983         if (name && !namelen)
 984                 namelen = strlen(name);
 985         while (1) {
 986                 if (!o || (!o->parsed && !parse_object(r, &o->oid)))
 987                         return NULL;
 988                 if (expected_type == OBJ_ANY || o->type == expected_type)
 989                         return o;
 990                 if (o->type == OBJ_TAG)
 991                         o = ((struct tag*) o)->tagged;
 992                 else if (o->type == OBJ_COMMIT)
 993                         o = &(repo_get_commit_tree(r, ((struct commit *)o))->object);
 994                 else {
 995                         if (name)
 996                                 error("%.*s: expected %s type, but the object "
 997                                       "dereferences to %s type",
 998                                       namelen, name, type_name(expected_type),
 999                                       type_name(o->type));
1000                         return NULL;
1001                 }
1002         }
1003 }
1004
1005 static int peel_onion(struct repository *r, const char *name, int len,
1006                       struct object_id *oid, unsigned lookup_flags)
1007 {
1008         struct object_id outer;
1009         const char *sp;
1010         unsigned int expected_type = 0;
1011         struct object *o;
1012
1013         /*
1014          * "ref^{type}" dereferences ref repeatedly until you cannot
1015          * dereference anymore, or you get an object of given type,
1016          * whichever comes first.  "ref^{}" means just dereference
1017          * tags until you get a non-tag.  "ref^0" is a shorthand for
1018          * "ref^{commit}".  "commit^{tree}" could be used to find the
1019          * top-level tree of the given commit.
1020          */
1021         if (len < 4 || name[len-1] != '}')
1022                 return -1;
1023
1024         for (sp = name + len - 1; name <= sp; sp--) {
1025                 int ch = *sp;
1026                 if (ch == '{' && name < sp && sp[-1] == '^')
1027                         break;
1028         }
1029         if (sp <= name)
1030                 return -1;
1031
1032         sp++; /* beginning of type name, or closing brace for empty */
1033         if (starts_with(sp, "commit}"))
1034                 expected_type = OBJ_COMMIT;
1035         else if (starts_with(sp, "tag}"))
1036                 expected_type = OBJ_TAG;
1037         else if (starts_with(sp, "tree}"))
1038                 expected_type = OBJ_TREE;
1039         else if (starts_with(sp, "blob}"))
1040                 expected_type = OBJ_BLOB;
1041         else if (starts_with(sp, "object}"))
1042                 expected_type = OBJ_ANY;
1043         else if (sp[0] == '}')
1044                 expected_type = OBJ_NONE;
1045         else if (sp[0] == '/')
1046                 expected_type = OBJ_COMMIT;
1047         else
1048                 return -1;
1049
1050         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
1051         if (expected_type == OBJ_COMMIT)
1052                 lookup_flags |= GET_OID_COMMITTISH;
1053         else if (expected_type == OBJ_TREE)
1054                 lookup_flags |= GET_OID_TREEISH;
1055
1056         if (get_oid_1(r, name, sp - name - 2, &outer, lookup_flags))
1057                 return -1;
1058
1059         o = parse_object(r, &outer);
1060         if (!o)
1061                 return -1;
1062         if (!expected_type) {
1063                 o = deref_tag(r, o, name, sp - name - 2);
1064                 if (!o || (!o->parsed && !parse_object(r, &o->oid)))
1065                         return -1;
1066                 oidcpy(oid, &o->oid);
1067                 return 0;
1068         }
1069
1070         /*
1071          * At this point, the syntax look correct, so
1072          * if we do not get the needed object, we should
1073          * barf.
1074          */
1075         o = repo_peel_to_type(r, name, len, o, expected_type);
1076         if (!o)
1077                 return -1;
1078
1079         oidcpy(oid, &o->oid);
1080         if (sp[0] == '/') {
1081                 /* "$commit^{/foo}" */
1082                 char *prefix;
1083                 int ret;
1084                 struct commit_list *list = NULL;
1085
1086                 /*
1087                  * $commit^{/}. Some regex implementation may reject.
1088                  * We don't need regex anyway. '' pattern always matches.
1089                  */
1090                 if (sp[1] == '}')
1091                         return 0;
1092
1093                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1094                 commit_list_insert((struct commit *)o, &list);
1095                 ret = get_oid_oneline(r, prefix, oid, list);
1096                 free(prefix);
1097                 return ret;
1098         }
1099         return 0;
1100 }
1101
1102 static int get_describe_name(struct repository *r,
1103                              const char *name, int len,
1104                              struct object_id *oid)
1105 {
1106         const char *cp;
1107         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1108
1109         for (cp = name + len - 1; name + 2 <= cp; cp--) {
1110                 char ch = *cp;
1111                 if (!isxdigit(ch)) {
1112                         /* We must be looking at g in "SOMETHING-g"
1113                          * for it to be describe output.
1114                          */
1115                         if (ch == 'g' && cp[-1] == '-') {
1116                                 cp++;
1117                                 len -= cp - name;
1118                                 return get_short_oid(r,
1119                                                      cp, len, oid, flags);
1120                         }
1121                 }
1122         }
1123         return -1;
1124 }
1125
1126 static enum get_oid_result get_oid_1(struct repository *r,
1127                                      const char *name, int len,
1128                                      struct object_id *oid,
1129                                      unsigned lookup_flags)
1130 {
1131         int ret, has_suffix;
1132         const char *cp;
1133
1134         /*
1135          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1136          */
1137         has_suffix = 0;
1138         for (cp = name + len - 1; name <= cp; cp--) {
1139                 int ch = *cp;
1140                 if ('0' <= ch && ch <= '9')
1141                         continue;
1142                 if (ch == '~' || ch == '^')
1143                         has_suffix = ch;
1144                 break;
1145         }
1146
1147         if (has_suffix) {
1148                 int num = 0;
1149                 int len1 = cp - name;
1150                 cp++;
1151                 while (cp < name + len)
1152                         num = num * 10 + *cp++ - '0';
1153                 if (!num && len1 == len - 1)
1154                         num = 1;
1155                 if (has_suffix == '^')
1156                         return get_parent(r, name, len1, oid, num);
1157                 /* else if (has_suffix == '~') -- goes without saying */
1158                 return get_nth_ancestor(r, name, len1, oid, num);
1159         }
1160
1161         ret = peel_onion(r, name, len, oid, lookup_flags);
1162         if (!ret)
1163                 return FOUND;
1164
1165         ret = get_oid_basic(r, name, len, oid, lookup_flags);
1166         if (!ret)
1167                 return FOUND;
1168
1169         /* It could be describe output that is "SOMETHING-gXXXX" */
1170         ret = get_describe_name(r, name, len, oid);
1171         if (!ret)
1172                 return FOUND;
1173
1174         return get_short_oid(r, name, len, oid, lookup_flags);
1175 }
1176
1177 /*
1178  * This interprets names like ':/Initial revision of "git"' by searching
1179  * through history and returning the first commit whose message starts
1180  * the given regular expression.
1181  *
1182  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1183  *
1184  * For a literal '!' character at the beginning of a pattern, you have to repeat
1185  * that, like: ':/!!foo'
1186  *
1187  * For future extension, all other sequences beginning with ':/!' are reserved.
1188  */
1189
1190 /* Remember to update object flag allocation in object.h */
1191 #define ONELINE_SEEN (1u<<20)
1192
1193 struct handle_one_ref_cb {
1194         struct repository *repo;
1195         struct commit_list **list;
1196 };
1197
1198 static int handle_one_ref(const char *path, const struct object_id *oid,
1199                           int flag, void *cb_data)
1200 {
1201         struct handle_one_ref_cb *cb = cb_data;
1202         struct commit_list **list = cb->list;
1203         struct object *object = parse_object(cb->repo, oid);
1204         if (!object)
1205                 return 0;
1206         if (object->type == OBJ_TAG) {
1207                 object = deref_tag(cb->repo, object, path,
1208                                    strlen(path));
1209                 if (!object)
1210                         return 0;
1211         }
1212         if (object->type != OBJ_COMMIT)
1213                 return 0;
1214         commit_list_insert((struct commit *)object, list);
1215         return 0;
1216 }
1217
1218 static int get_oid_oneline(struct repository *r,
1219                            const char *prefix, struct object_id *oid,
1220                            struct commit_list *list)
1221 {
1222         struct commit_list *backup = NULL, *l;
1223         int found = 0;
1224         int negative = 0;
1225         regex_t regex;
1226
1227         if (prefix[0] == '!') {
1228                 prefix++;
1229
1230                 if (prefix[0] == '-') {
1231                         prefix++;
1232                         negative = 1;
1233                 } else if (prefix[0] != '!') {
1234                         return -1;
1235                 }
1236         }
1237
1238         if (regcomp(&regex, prefix, REG_EXTENDED))
1239                 return -1;
1240
1241         for (l = list; l; l = l->next) {
1242                 l->item->object.flags |= ONELINE_SEEN;
1243                 commit_list_insert(l->item, &backup);
1244         }
1245         while (list) {
1246                 const char *p, *buf;
1247                 struct commit *commit;
1248                 int matches;
1249
1250                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1251                 if (!parse_object(r, &commit->object.oid))
1252                         continue;
1253                 buf = get_commit_buffer(commit, NULL);
1254                 p = strstr(buf, "\n\n");
1255                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1256                 unuse_commit_buffer(commit, buf);
1257
1258                 if (matches) {
1259                         oidcpy(oid, &commit->object.oid);
1260                         found = 1;
1261                         break;
1262                 }
1263         }
1264         regfree(&regex);
1265         free_commit_list(list);
1266         for (l = backup; l; l = l->next)
1267                 clear_commit_marks(l->item, ONELINE_SEEN);
1268         free_commit_list(backup);
1269         return found ? 0 : -1;
1270 }
1271
1272 struct grab_nth_branch_switch_cbdata {
1273         int remaining;
1274         struct strbuf buf;
1275 };
1276
1277 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1278                                   const char *email, timestamp_t timestamp, int tz,
1279                                   const char *message, void *cb_data)
1280 {
1281         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1282         const char *match = NULL, *target = NULL;
1283         size_t len;
1284
1285         if (skip_prefix(message, "checkout: moving from ", &match))
1286                 target = strstr(match, " to ");
1287
1288         if (!match || !target)
1289                 return 0;
1290         if (--(cb->remaining) == 0) {
1291                 len = target - match;
1292                 strbuf_reset(&cb->buf);
1293                 strbuf_add(&cb->buf, match, len);
1294                 return 1; /* we are done */
1295         }
1296         return 0;
1297 }
1298
1299 /*
1300  * Parse @{-N} syntax, return the number of characters parsed
1301  * if successful; otherwise signal an error with negative value.
1302  */
1303 static int interpret_nth_prior_checkout(struct repository *r,
1304                                         const char *name, int namelen,
1305                                         struct strbuf *buf)
1306 {
1307         long nth;
1308         int retval;
1309         struct grab_nth_branch_switch_cbdata cb;
1310         const char *brace;
1311         char *num_end;
1312
1313         if (namelen < 4)
1314                 return -1;
1315         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1316                 return -1;
1317         brace = memchr(name, '}', namelen);
1318         if (!brace)
1319                 return -1;
1320         nth = strtol(name + 3, &num_end, 10);
1321         if (num_end != brace)
1322                 return -1;
1323         if (nth <= 0)
1324                 return -1;
1325         cb.remaining = nth;
1326         strbuf_init(&cb.buf, 20);
1327
1328         retval = refs_for_each_reflog_ent_reverse(get_main_ref_store(r),
1329                         "HEAD", grab_nth_branch_switch, &cb);
1330         if (0 < retval) {
1331                 strbuf_reset(buf);
1332                 strbuf_addbuf(buf, &cb.buf);
1333                 retval = brace - name + 1;
1334         } else
1335                 retval = 0;
1336
1337         strbuf_release(&cb.buf);
1338         return retval;
1339 }
1340
1341 int repo_get_oid_mb(struct repository *r,
1342                     const char *name,
1343                     struct object_id *oid)
1344 {
1345         struct commit *one, *two;
1346         struct commit_list *mbs;
1347         struct object_id oid_tmp;
1348         const char *dots;
1349         int st;
1350
1351         dots = strstr(name, "...");
1352         if (!dots)
1353                 return repo_get_oid(r, name, oid);
1354         if (dots == name)
1355                 st = repo_get_oid(r, "HEAD", &oid_tmp);
1356         else {
1357                 struct strbuf sb;
1358                 strbuf_init(&sb, dots - name);
1359                 strbuf_add(&sb, name, dots - name);
1360                 st = repo_get_oid_committish(r, sb.buf, &oid_tmp);
1361                 strbuf_release(&sb);
1362         }
1363         if (st)
1364                 return st;
1365         one = lookup_commit_reference_gently(r, &oid_tmp, 0);
1366         if (!one)
1367                 return -1;
1368
1369         if (repo_get_oid_committish(r, dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1370                 return -1;
1371         two = lookup_commit_reference_gently(r, &oid_tmp, 0);
1372         if (!two)
1373                 return -1;
1374         if (r != the_repository)
1375                 BUG("sorry get_merge_bases() can't take struct repository yet");
1376         mbs = get_merge_bases(one, two);
1377         if (!mbs || mbs->next)
1378                 st = -1;
1379         else {
1380                 st = 0;
1381                 oidcpy(oid, &mbs->item->object.oid);
1382         }
1383         free_commit_list(mbs);
1384         return st;
1385 }
1386
1387 /* parse @something syntax, when 'something' is not {.*} */
1388 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1389 {
1390         const char *next;
1391
1392         if (len || name[1] == '{')
1393                 return -1;
1394
1395         /* make sure it's a single @, or @@{.*}, not @foo */
1396         next = memchr(name + len + 1, '@', namelen - len - 1);
1397         if (next && next[1] != '{')
1398                 return -1;
1399         if (!next)
1400                 next = name + namelen;
1401         if (next != name + 1)
1402                 return -1;
1403
1404         strbuf_reset(buf);
1405         strbuf_add(buf, "HEAD", 4);
1406         return 1;
1407 }
1408
1409 static int reinterpret(struct repository *r,
1410                        const char *name, int namelen, int len,
1411                        struct strbuf *buf, unsigned allowed)
1412 {
1413         /* we have extra data, which might need further processing */
1414         struct strbuf tmp = STRBUF_INIT;
1415         int used = buf->len;
1416         int ret;
1417
1418         strbuf_add(buf, name + len, namelen - len);
1419         ret = repo_interpret_branch_name(r, buf->buf, buf->len, &tmp, allowed);
1420         /* that data was not interpreted, remove our cruft */
1421         if (ret < 0) {
1422                 strbuf_setlen(buf, used);
1423                 return len;
1424         }
1425         strbuf_reset(buf);
1426         strbuf_addbuf(buf, &tmp);
1427         strbuf_release(&tmp);
1428         /* tweak for size of {-N} versus expanded ref name */
1429         return ret - used + len;
1430 }
1431
1432 static void set_shortened_ref(struct repository *r, struct strbuf *buf, const char *ref)
1433 {
1434         char *s = refs_shorten_unambiguous_ref(get_main_ref_store(r), ref, 0);
1435         strbuf_reset(buf);
1436         strbuf_addstr(buf, s);
1437         free(s);
1438 }
1439
1440 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1441 {
1442         if (!allowed)
1443                 return 1;
1444
1445         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1446             starts_with(refname, "refs/heads/"))
1447                 return 1;
1448         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1449             starts_with(refname, "refs/remotes/"))
1450                 return 1;
1451
1452         return 0;
1453 }
1454
1455 static int interpret_branch_mark(struct repository *r,
1456                                  const char *name, int namelen,
1457                                  int at, struct strbuf *buf,
1458                                  int (*get_mark)(const char *, int),
1459                                  const char *(*get_data)(struct branch *,
1460                                                          struct strbuf *),
1461                                  unsigned allowed)
1462 {
1463         int len;
1464         struct branch *branch;
1465         struct strbuf err = STRBUF_INIT;
1466         const char *value;
1467
1468         len = get_mark(name + at, namelen - at);
1469         if (!len)
1470                 return -1;
1471
1472         if (memchr(name, ':', at))
1473                 return -1;
1474
1475         if (at) {
1476                 char *name_str = xmemdupz(name, at);
1477                 branch = branch_get(name_str);
1478                 free(name_str);
1479         } else
1480                 branch = branch_get(NULL);
1481
1482         value = get_data(branch, &err);
1483         if (!value)
1484                 die("%s", err.buf);
1485
1486         if (!branch_interpret_allowed(value, allowed))
1487                 return -1;
1488
1489         set_shortened_ref(r, buf, value);
1490         return len + at;
1491 }
1492
1493 int repo_interpret_branch_name(struct repository *r,
1494                                const char *name, int namelen,
1495                                struct strbuf *buf,
1496                                unsigned allowed)
1497 {
1498         char *at;
1499         const char *start;
1500         int len;
1501
1502         if (!namelen)
1503                 namelen = strlen(name);
1504
1505         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1506                 len = interpret_nth_prior_checkout(r, name, namelen, buf);
1507                 if (!len) {
1508                         return len; /* syntax Ok, not enough switches */
1509                 } else if (len > 0) {
1510                         if (len == namelen)
1511                                 return len; /* consumed all */
1512                         else
1513                                 return reinterpret(r, name, namelen, len, buf, allowed);
1514                 }
1515         }
1516
1517         for (start = name;
1518              (at = memchr(start, '@', namelen - (start - name)));
1519              start = at + 1) {
1520
1521                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1522                         len = interpret_empty_at(name, namelen, at - name, buf);
1523                         if (len > 0)
1524                                 return reinterpret(r, name, namelen, len, buf,
1525                                                    allowed);
1526                 }
1527
1528                 len = interpret_branch_mark(r, name, namelen, at - name, buf,
1529                                             upstream_mark, branch_get_upstream,
1530                                             allowed);
1531                 if (len > 0)
1532                         return len;
1533
1534                 len = interpret_branch_mark(r, name, namelen, at - name, buf,
1535                                             push_mark, branch_get_push,
1536                                             allowed);
1537                 if (len > 0)
1538                         return len;
1539         }
1540
1541         return -1;
1542 }
1543
1544 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1545 {
1546         int len = strlen(name);
1547         int used = interpret_branch_name(name, len, sb, allowed);
1548
1549         if (used < 0)
1550                 used = 0;
1551         strbuf_add(sb, name + used, len - used);
1552 }
1553
1554 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1555 {
1556         if (startup_info->have_repository)
1557                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1558         else
1559                 strbuf_addstr(sb, name);
1560
1561         /*
1562          * This splice must be done even if we end up rejecting the
1563          * name; builtin/branch.c::copy_or_rename_branch() still wants
1564          * to see what the name expanded to so that "branch -m" can be
1565          * used as a tool to correct earlier mistakes.
1566          */
1567         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1568
1569         if (*name == '-' ||
1570             !strcmp(sb->buf, "refs/heads/HEAD"))
1571                 return -1;
1572
1573         return check_refname_format(sb->buf, 0);
1574 }
1575
1576 /*
1577  * This is like "get_oid_basic()", except it allows "object ID expressions",
1578  * notably "xyz^" for "parent of xyz"
1579  */
1580 int repo_get_oid(struct repository *r, const char *name, struct object_id *oid)
1581 {
1582         struct object_context unused;
1583         return get_oid_with_context(r, name, 0, oid, &unused);
1584 }
1585
1586
1587 /*
1588  * Many callers know that the user meant to name a commit-ish by
1589  * syntactical positions where the object name appears.  Calling this
1590  * function allows the machinery to disambiguate shorter-than-unique
1591  * abbreviated object names between commit-ish and others.
1592  *
1593  * Note that this does NOT error out when the named object is not a
1594  * commit-ish. It is merely to give a hint to the disambiguation
1595  * machinery.
1596  */
1597 int repo_get_oid_committish(struct repository *r,
1598                             const char *name,
1599                             struct object_id *oid)
1600 {
1601         struct object_context unused;
1602         return get_oid_with_context(r, name, GET_OID_COMMITTISH,
1603                                     oid, &unused);
1604 }
1605
1606 int repo_get_oid_treeish(struct repository *r,
1607                          const char *name,
1608                          struct object_id *oid)
1609 {
1610         struct object_context unused;
1611         return get_oid_with_context(r, name, GET_OID_TREEISH,
1612                                     oid, &unused);
1613 }
1614
1615 int repo_get_oid_commit(struct repository *r,
1616                         const char *name,
1617                         struct object_id *oid)
1618 {
1619         struct object_context unused;
1620         return get_oid_with_context(r, name, GET_OID_COMMIT,
1621                                     oid, &unused);
1622 }
1623
1624 int repo_get_oid_tree(struct repository *r,
1625                       const char *name,
1626                       struct object_id *oid)
1627 {
1628         struct object_context unused;
1629         return get_oid_with_context(r, name, GET_OID_TREE,
1630                                     oid, &unused);
1631 }
1632
1633 int repo_get_oid_blob(struct repository *r,
1634                       const char *name,
1635                       struct object_id *oid)
1636 {
1637         struct object_context unused;
1638         return get_oid_with_context(r, name, GET_OID_BLOB,
1639                                     oid, &unused);
1640 }
1641
1642 /* Must be called only when object_name:filename doesn't exist. */
1643 static void diagnose_invalid_oid_path(const char *prefix,
1644                                       const char *filename,
1645                                       const struct object_id *tree_oid,
1646                                       const char *object_name,
1647                                       int object_name_len)
1648 {
1649         struct object_id oid;
1650         unsigned mode;
1651
1652         if (!prefix)
1653                 prefix = "";
1654
1655         if (file_exists(filename))
1656                 die("Path '%s' exists on disk, but not in '%.*s'.",
1657                     filename, object_name_len, object_name);
1658         if (is_missing_file_error(errno)) {
1659                 char *fullname = xstrfmt("%s%s", prefix, filename);
1660
1661                 if (!get_tree_entry(tree_oid, fullname, &oid, &mode)) {
1662                         die("Path '%s' exists, but not '%s'.\n"
1663                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1664                             fullname,
1665                             filename,
1666                             object_name_len, object_name,
1667                             fullname,
1668                             object_name_len, object_name,
1669                             filename);
1670                 }
1671                 die("Path '%s' does not exist in '%.*s'",
1672                     filename, object_name_len, object_name);
1673         }
1674 }
1675
1676 /* Must be called only when :stage:filename doesn't exist. */
1677 static void diagnose_invalid_index_path(struct repository *r,
1678                                         int stage,
1679                                         const char *prefix,
1680                                         const char *filename)
1681 {
1682         struct index_state *istate = r->index;
1683         const struct cache_entry *ce;
1684         int pos;
1685         unsigned namelen = strlen(filename);
1686         struct strbuf fullname = STRBUF_INIT;
1687
1688         if (!prefix)
1689                 prefix = "";
1690
1691         /* Wrong stage number? */
1692         pos = index_name_pos(istate, filename, namelen);
1693         if (pos < 0)
1694                 pos = -pos - 1;
1695         if (pos < istate->cache_nr) {
1696                 ce = istate->cache[pos];
1697                 if (ce_namelen(ce) == namelen &&
1698                     !memcmp(ce->name, filename, namelen))
1699                         die("Path '%s' is in the index, but not at stage %d.\n"
1700                             "Did you mean ':%d:%s'?",
1701                             filename, stage,
1702                             ce_stage(ce), filename);
1703         }
1704
1705         /* Confusion between relative and absolute filenames? */
1706         strbuf_addstr(&fullname, prefix);
1707         strbuf_addstr(&fullname, filename);
1708         pos = index_name_pos(istate, fullname.buf, fullname.len);
1709         if (pos < 0)
1710                 pos = -pos - 1;
1711         if (pos < istate->cache_nr) {
1712                 ce = istate->cache[pos];
1713                 if (ce_namelen(ce) == fullname.len &&
1714                     !memcmp(ce->name, fullname.buf, fullname.len))
1715                         die("Path '%s' is in the index, but not '%s'.\n"
1716                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1717                             fullname.buf, filename,
1718                             ce_stage(ce), fullname.buf,
1719                             ce_stage(ce), filename);
1720         }
1721
1722         if (repo_file_exists(r, filename))
1723                 die("Path '%s' exists on disk, but not in the index.", filename);
1724         if (is_missing_file_error(errno))
1725                 die("Path '%s' does not exist (neither on disk nor in the index).",
1726                     filename);
1727
1728         strbuf_release(&fullname);
1729 }
1730
1731
1732 static char *resolve_relative_path(struct repository *r, const char *rel)
1733 {
1734         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1735                 return NULL;
1736
1737         if (r != the_repository || !is_inside_work_tree())
1738                 die("relative path syntax can't be used outside working tree.");
1739
1740         /* die() inside prefix_path() if resolved path is outside worktree */
1741         return prefix_path(startup_info->prefix,
1742                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1743                            rel);
1744 }
1745
1746 static enum get_oid_result get_oid_with_context_1(struct repository *repo,
1747                                   const char *name,
1748                                   unsigned flags,
1749                                   const char *prefix,
1750                                   struct object_id *oid,
1751                                   struct object_context *oc)
1752 {
1753         int ret, bracket_depth;
1754         int namelen = strlen(name);
1755         const char *cp;
1756         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1757
1758         if (only_to_die)
1759                 flags |= GET_OID_QUIETLY;
1760
1761         memset(oc, 0, sizeof(*oc));
1762         oc->mode = S_IFINVALID;
1763         strbuf_init(&oc->symlink_path, 0);
1764         ret = get_oid_1(repo, name, namelen, oid, flags);
1765         if (!ret)
1766                 return ret;
1767         /*
1768          * sha1:path --> object name of path in ent sha1
1769          * :path -> object name of absolute path in index
1770          * :./path -> object name of path relative to cwd in index
1771          * :[0-3]:path -> object name of path in index at stage
1772          * :/foo -> recent commit matching foo
1773          */
1774         if (name[0] == ':') {
1775                 int stage = 0;
1776                 const struct cache_entry *ce;
1777                 char *new_path = NULL;
1778                 int pos;
1779                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1780                         struct handle_one_ref_cb cb;
1781                         struct commit_list *list = NULL;
1782
1783                         cb.repo = repo;
1784                         cb.list = &list;
1785                         refs_for_each_ref(repo->refs, handle_one_ref, &cb);
1786                         refs_head_ref(repo->refs, handle_one_ref, &cb);
1787                         commit_list_sort_by_date(&list);
1788                         return get_oid_oneline(repo, name + 2, oid, list);
1789                 }
1790                 if (namelen < 3 ||
1791                     name[2] != ':' ||
1792                     name[1] < '0' || '3' < name[1])
1793                         cp = name + 1;
1794                 else {
1795                         stage = name[1] - '0';
1796                         cp = name + 3;
1797                 }
1798                 new_path = resolve_relative_path(repo, cp);
1799                 if (!new_path) {
1800                         namelen = namelen - (cp - name);
1801                 } else {
1802                         cp = new_path;
1803                         namelen = strlen(cp);
1804                 }
1805
1806                 if (flags & GET_OID_RECORD_PATH)
1807                         oc->path = xstrdup(cp);
1808
1809                 if (!repo->index->cache)
1810                         repo_read_index(repo);
1811                 pos = index_name_pos(repo->index, cp, namelen);
1812                 if (pos < 0)
1813                         pos = -pos - 1;
1814                 while (pos < repo->index->cache_nr) {
1815                         ce = repo->index->cache[pos];
1816                         if (ce_namelen(ce) != namelen ||
1817                             memcmp(ce->name, cp, namelen))
1818                                 break;
1819                         if (ce_stage(ce) == stage) {
1820                                 oidcpy(oid, &ce->oid);
1821                                 oc->mode = ce->ce_mode;
1822                                 free(new_path);
1823                                 return 0;
1824                         }
1825                         pos++;
1826                 }
1827                 if (only_to_die && name[1] && name[1] != '/')
1828                         diagnose_invalid_index_path(repo, stage, prefix, cp);
1829                 free(new_path);
1830                 return -1;
1831         }
1832         for (cp = name, bracket_depth = 0; *cp; cp++) {
1833                 if (*cp == '{')
1834                         bracket_depth++;
1835                 else if (bracket_depth && *cp == '}')
1836                         bracket_depth--;
1837                 else if (!bracket_depth && *cp == ':')
1838                         break;
1839         }
1840         if (*cp == ':') {
1841                 struct object_id tree_oid;
1842                 int len = cp - name;
1843                 unsigned sub_flags = flags;
1844
1845                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1846                 sub_flags |= GET_OID_TREEISH;
1847
1848                 if (!get_oid_1(repo, name, len, &tree_oid, sub_flags)) {
1849                         const char *filename = cp+1;
1850                         char *new_filename = NULL;
1851
1852                         new_filename = resolve_relative_path(repo, filename);
1853                         if (new_filename)
1854                                 filename = new_filename;
1855                         /*
1856                          * NEEDSWORK: Eventually get_tree_entry*() should
1857                          * learn to take struct repository directly and we
1858                          * would not need to inject submodule odb to the
1859                          * in-core odb.
1860                          */
1861                         if (repo != the_repository)
1862                                 add_to_alternates_memory(repo->objects->odb->path);
1863                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1864                                 ret = get_tree_entry_follow_symlinks(&tree_oid,
1865                                         filename, oid, &oc->symlink_path,
1866                                         &oc->mode);
1867                         } else {
1868                                 ret = get_tree_entry(&tree_oid, filename, oid,
1869                                                      &oc->mode);
1870                                 if (ret && only_to_die) {
1871                                         diagnose_invalid_oid_path(prefix,
1872                                                                    filename,
1873                                                                    &tree_oid,
1874                                                                    name, len);
1875                                 }
1876                         }
1877                         if (flags & GET_OID_RECORD_PATH)
1878                                 oc->path = xstrdup(filename);
1879
1880                         free(new_filename);
1881                         return ret;
1882                 } else {
1883                         if (only_to_die)
1884                                 die("Invalid object name '%.*s'.", len, name);
1885                 }
1886         }
1887         return ret;
1888 }
1889
1890 /*
1891  * Call this function when you know "name" given by the end user must
1892  * name an object but it doesn't; the function _may_ die with a better
1893  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1894  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1895  * you have a chance to diagnose the error further.
1896  */
1897 void maybe_die_on_misspelt_object_name(struct repository *r,
1898                                        const char *name,
1899                                        const char *prefix)
1900 {
1901         struct object_context oc;
1902         struct object_id oid;
1903         get_oid_with_context_1(r, name, GET_OID_ONLY_TO_DIE,
1904                                prefix, &oid, &oc);
1905 }
1906
1907 enum get_oid_result get_oid_with_context(struct repository *repo,
1908                                          const char *str,
1909                                          unsigned flags,
1910                                          struct object_id *oid,
1911                                          struct object_context *oc)
1912 {
1913         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1914                 BUG("incompatible flags for get_sha1_with_context");
1915         return get_oid_with_context_1(repo, str, flags, NULL, oid, oc);
1916 }