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

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