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