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