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
  16 static int get_oid_oneline(const char *, struct object_id *, struct commit_list *);
  17
  18 typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
  19
  20 struct disambiguate_state {
  21         int len; /* length of prefix in hex chars */
  22         char hex_pfx[GIT_MAX_HEXSZ + 1];
  23         struct object_id bin_pfx;
  24
  25         disambiguate_hint_fn fn;
  26         void *cb_data;
  27         struct object_id candidate;
  28         unsigned candidate_exists:1;
  29         unsigned candidate_checked:1;
  30         unsigned candidate_ok:1;
  31         unsigned disambiguate_fn_used:1;
  32         unsigned ambiguous:1;
  33         unsigned always_call_fn:1;
  34 };
  35
  36 static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
  37 {
  38         if (ds->always_call_fn) {
  39                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  40                 return;
  41         }
  42         if (!ds->candidate_exists) {
  43                 /* this is the first candidate */
  44                 oidcpy(&ds->candidate, current);
  45                 ds->candidate_exists = 1;
  46                 return;
  47         } else if (!oidcmp(&ds->candidate, current)) {
  48                 /* the same as what we already have seen */
  49                 return;
  50         }
  51
  52         if (!ds->fn) {
  53                 /* cannot disambiguate between ds->candidate and current */
  54                 ds->ambiguous = 1;
  55                 return;
  56         }
  57
  58         if (!ds->candidate_checked) {
  59                 ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
  60                 ds->disambiguate_fn_used = 1;
  61                 ds->candidate_checked = 1;
  62         }
  63
  64         if (!ds->candidate_ok) {
  65                 /* discard the candidate; we know it does not satisfy fn */
  66                 oidcpy(&ds->candidate, current);
  67                 ds->candidate_checked = 0;
  68                 return;
  69         }
  70
  71         /* if we reach this point, we know ds->candidate satisfies fn */
  72         if (ds->fn(current, ds->cb_data)) {
  73                 /*
  74                  * if both current and candidate satisfy fn, we cannot
  75                  * disambiguate.
  76                  */
  77                 ds->candidate_ok = 0;
  78                 ds->ambiguous = 1;
  79         }
  80
  81         /* otherwise, current can be discarded and candidate is still good */
  82 }
  83
  84 static int append_loose_object(const struct object_id *oid, const char *path,
  85                                void *data)
  86 {
  87         oid_array_append(data, oid);
  88         return 0;
  89 }
  90
  91 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  92
  93 static void find_short_object_filename(struct disambiguate_state *ds)
  94 {
  95         int subdir_nr = ds->bin_pfx.hash[0];
  96         struct alternate_object_database *alt;
  97         static struct alternate_object_database *fakeent;
  98
  99         if (!fakeent) {
 100                 /*
 101                  * Create a "fake" alternate object database that
 102                  * points to our own object database, to make it
 103                  * easier to get a temporary working space in
 104                  * alt->name/alt->base while iterating over the
 105                  * object databases including our own.
 106                  */
 107                 fakeent = alloc_alt_odb(get_object_directory());
 108         }
 109         fakeent->next = the_repository->objects->alt_odb_list;
 110
 111         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 112                 int pos;
 113
 114                 if (!alt->loose_objects_subdir_seen[subdir_nr]) {
 115                         struct strbuf *buf = alt_scratch_buf(alt);
 116                         for_each_file_in_obj_subdir(subdir_nr, buf,
 117                                                     append_loose_object,
 118                                                     NULL, NULL,
 119                                                     &alt->loose_objects_cache);
 120                         alt->loose_objects_subdir_seen[subdir_nr] = 1;
 121                 }
 122
 123                 pos = oid_array_lookup(&alt->loose_objects_cache, &ds->bin_pfx);
 124                 if (pos < 0)
 125                         pos = -1 - pos;
 126                 while (!ds->ambiguous && pos < alt->loose_objects_cache.nr) {
 127                         const struct object_id *oid;
 128                         oid = alt->loose_objects_cache.oid + pos;
 129                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 130                                 break;
 131                         update_candidates(ds, oid);
 132                         pos++;
 133                 }
 134         }
 135 }
 136
 137 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 138 {
 139         do {
 140                 if (*a != *b)
 141                         return 0;
 142                 a++;
 143                 b++;
 144                 len -= 2;
 145         } while (len > 1);
 146         if (len)
 147                 if ((*a ^ *b) & 0xf0)
 148                         return 0;
 149         return 1;
 150 }
 151
 152 static void unique_in_pack(struct packed_git *p,
 153                            struct disambiguate_state *ds)
 154 {
 155         uint32_t num, i, first = 0;
 156         const struct object_id *current = NULL;
 157
 158         if (open_pack_index(p) || !p->num_objects)
 159                 return;
 160
 161         num = p->num_objects;
 162         bsearch_pack(&ds->bin_pfx, p, &first);
 163
 164         /*
 165          * At this point, "first" is the location of the lowest object
 166          * with an object name that could match "bin_pfx".  See if we have
 167          * 0, 1 or more objects that actually match(es).
 168          */
 169         for (i = first; i < num && !ds->ambiguous; i++) {
 170                 struct object_id oid;
 171                 current = nth_packed_object_oid(&oid, p, i);
 172                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 173                         break;
 174                 update_candidates(ds, current);
 175         }
 176 }
 177
 178 static void find_short_packed_object(struct disambiguate_state *ds)
 179 {
 180         struct packed_git *p;
 181
 182         for (p = get_packed_git(the_repository); p && !ds->ambiguous;
 183              p = p->next)
 184                 unique_in_pack(p, ds);
 185 }
 186
 187 #define SHORT_NAME_NOT_FOUND (-1)
 188 #define SHORT_NAME_AMBIGUOUS (-2)
 189
 190 static int finish_object_disambiguation(struct disambiguate_state *ds,
 191                                         struct object_id *oid)
 192 {
 193         if (ds->ambiguous)
 194                 return SHORT_NAME_AMBIGUOUS;
 195
 196         if (!ds->candidate_exists)
 197                 return SHORT_NAME_NOT_FOUND;
 198
 199         if (!ds->candidate_checked)
 200                 /*
 201                  * If this is the only candidate, there is no point
 202                  * calling the disambiguation hint callback.
 203                  *
 204                  * On the other hand, if the current candidate
 205                  * replaced an earlier candidate that did _not_ pass
 206                  * the disambiguation hint callback, then we do have
 207                  * more than one objects that match the short name
 208                  * given, so we should make sure this one matches;
 209                  * otherwise, if we discovered this one and the one
 210                  * that we previously discarded in the reverse order,
 211                  * we would end up showing different results in the
 212                  * same repository!
 213                  */
 214                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 215                                     ds->fn(&ds->candidate, ds->cb_data));
 216
 217         if (!ds->candidate_ok)
 218                 return SHORT_NAME_AMBIGUOUS;
 219
 220         oidcpy(oid, &ds->candidate);
 221         return 0;
 222 }
 223
 224 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 225 {
 226         int kind = oid_object_info(the_repository, oid, NULL);
 227         return kind == OBJ_COMMIT;
 228 }
 229
 230 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 231 {
 232         struct object *obj;
 233         int kind;
 234
 235         kind = oid_object_info(the_repository, oid, NULL);
 236         if (kind == OBJ_COMMIT)
 237                 return 1;
 238         if (kind != OBJ_TAG)
 239                 return 0;
 240
 241         /* We need to do this the hard way... */
 242         obj = deref_tag(parse_object(oid), NULL, 0);
 243         if (obj && obj->type == OBJ_COMMIT)
 244                 return 1;
 245         return 0;
 246 }
 247
 248 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 249 {
 250         int kind = oid_object_info(the_repository, oid, NULL);
 251         return kind == OBJ_TREE;
 252 }
 253
 254 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 255 {
 256         struct object *obj;
 257         int kind;
 258
 259         kind = oid_object_info(the_repository, oid, NULL);
 260         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 261                 return 1;
 262         if (kind != OBJ_TAG)
 263                 return 0;
 264
 265         /* We need to do this the hard way... */
 266         obj = deref_tag(parse_object(oid), NULL, 0);
 267         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 268                 return 1;
 269         return 0;
 270 }
 271
 272 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 273 {
 274         int kind = oid_object_info(the_repository, oid, NULL);
 275         return kind == OBJ_BLOB;
 276 }
 277
 278 static disambiguate_hint_fn default_disambiguate_hint;
 279
 280 int set_disambiguate_hint_config(const char *var, const char *value)
 281 {
 282         static const struct {
 283                 const char *name;
 284                 disambiguate_hint_fn fn;
 285         } hints[] = {
 286                 { "none", NULL },
 287                 { "commit", disambiguate_commit_only },
 288                 { "committish", disambiguate_committish_only },
 289                 { "tree", disambiguate_tree_only },
 290                 { "treeish", disambiguate_treeish_only },
 291                 { "blob", disambiguate_blob_only }
 292         };
 293         int i;
 294
 295         if (!value)
 296                 return config_error_nonbool(var);
 297
 298         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 299                 if (!strcasecmp(value, hints[i].name)) {
 300                         default_disambiguate_hint = hints[i].fn;
 301                         return 0;
 302                 }
 303         }
 304
 305         return error("unknown hint type for '%s': %s", var, value);
 306 }
 307
 308 static int init_object_disambiguation(const char *name, int len,
 309                                       struct disambiguate_state *ds)
 310 {
 311         int i;
 312
 313         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 314                 return -1;
 315
 316         memset(ds, 0, sizeof(*ds));
 317
 318         for (i = 0; i < len ;i++) {
 319                 unsigned char c = name[i];
 320                 unsigned char val;
 321                 if (c >= '0' && c <= '9')
 322                         val = c - '0';
 323                 else if (c >= 'a' && c <= 'f')
 324                         val = c - 'a' + 10;
 325                 else if (c >= 'A' && c <='F') {
 326                         val = c - 'A' + 10;
 327                         c -= 'A' - 'a';
 328                 }
 329                 else
 330                         return -1;
 331                 ds->hex_pfx[i] = c;
 332                 if (!(i & 1))
 333                         val <<= 4;
 334                 ds->bin_pfx.hash[i >> 1] |= val;
 335         }
 336
 337         ds->len = len;
 338         ds->hex_pfx[len] = '\0';
 339         prepare_alt_odb(the_repository);
 340         return 0;
 341 }
 342
 343 static int show_ambiguous_object(const struct object_id *oid, void *data)
 344 {
 345         const struct disambiguate_state *ds = data;
 346         struct strbuf desc = STRBUF_INIT;
 347         int type;
 348
 349         if (ds->fn && !ds->fn(oid, ds->cb_data))
 350                 return 0;
 351
 352         type = oid_object_info(the_repository, oid, NULL);
 353         if (type == OBJ_COMMIT) {
 354                 struct commit *commit = lookup_commit(oid);
 355                 if (commit) {
 356                         struct pretty_print_context pp = {0};
 357                         pp.date_mode.type = DATE_SHORT;
 358                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 359                 }
 360         } else if (type == OBJ_TAG) {
 361                 struct tag *tag = lookup_tag(oid);
 362                 if (!parse_tag(tag) && tag->tag)
 363                         strbuf_addf(&desc, " %s", tag->tag);
 364         }
 365
 366         advise("  %s %s%s",
 367                find_unique_abbrev(oid, DEFAULT_ABBREV),
 368                type_name(type) ? type_name(type) : "unknown type",
 369                desc.buf);
 370
 371         strbuf_release(&desc);
 372         return 0;
 373 }
 374
 375 static int collect_ambiguous(const struct object_id *oid, void *data)
 376 {
 377         oid_array_append(data, oid);
 378         return 0;
 379 }
 380
 381 static int sort_ambiguous(const void *a, const void *b)
 382 {
 383         int a_type = oid_object_info(the_repository, a, NULL);
 384         int b_type = oid_object_info(the_repository, b, NULL);
 385         int a_type_sort;
 386         int b_type_sort;
 387
 388         /*
 389          * Sorts by hash within the same object type, just as
 390          * oid_array_for_each_unique() would do.
 391          */
 392         if (a_type == b_type)
 393                 return oidcmp(a, b);
 394
 395         /*
 396          * Between object types show tags, then commits, and finally
 397          * trees and blobs.
 398          *
 399          * The object_type enum is commit, tree, blob, tag, but we
 400          * want tag, commit, tree blob. Cleverly (perhaps too
 401          * cleverly) do that with modulus, since the enum assigns 1 to
 402          * commit, so tag becomes 0.
 403          */
 404         a_type_sort = a_type % 4;
 405         b_type_sort = b_type % 4;
 406         return a_type_sort > b_type_sort ? 1 : -1;
 407 }
 408
 409 static int get_short_oid(const char *name, int len, struct object_id *oid,
 410                           unsigned flags)
 411 {
 412         int status;
 413         struct disambiguate_state ds;
 414         int quietly = !!(flags & GET_OID_QUIETLY);
 415
 416         if (init_object_disambiguation(name, len, &ds) < 0)
 417                 return -1;
 418
 419         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 420                 BUG("multiple get_short_oid disambiguator flags");
 421
 422         if (flags & GET_OID_COMMIT)
 423                 ds.fn = disambiguate_commit_only;
 424         else if (flags & GET_OID_COMMITTISH)
 425                 ds.fn = disambiguate_committish_only;
 426         else if (flags & GET_OID_TREE)
 427                 ds.fn = disambiguate_tree_only;
 428         else if (flags & GET_OID_TREEISH)
 429                 ds.fn = disambiguate_treeish_only;
 430         else if (flags & GET_OID_BLOB)
 431                 ds.fn = disambiguate_blob_only;
 432         else
 433                 ds.fn = default_disambiguate_hint;
 434
 435         find_short_object_filename(&ds);
 436         find_short_packed_object(&ds);
 437         status = finish_object_disambiguation(&ds, oid);
 438
 439         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 440                 struct oid_array collect = OID_ARRAY_INIT;
 441
 442                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 443
 444                 /*
 445                  * We may still have ambiguity if we simply saw a series of
 446                  * candidates that did not satisfy our hint function. In
 447                  * that case, we still want to show them, so disable the hint
 448                  * function entirely.
 449                  */
 450                 if (!ds.ambiguous)
 451                         ds.fn = NULL;
 452
 453                 advise(_("The candidates are:"));
 454                 for_each_abbrev(ds.hex_pfx, collect_ambiguous, &collect);
 455                 QSORT(collect.oid, collect.nr, sort_ambiguous);
 456
 457                 if (oid_array_for_each(&collect, show_ambiguous_object, &ds))
 458                         BUG("show_ambiguous_object shouldn't return non-zero");
 459                 oid_array_clear(&collect);
 460         }
 461
 462         return status;
 463 }
 464
 465 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 466 {
 467         struct oid_array collect = OID_ARRAY_INIT;
 468         struct disambiguate_state ds;
 469         int ret;
 470
 471         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 472                 return -1;
 473
 474         ds.always_call_fn = 1;
 475         ds.fn = collect_ambiguous;
 476         ds.cb_data = &collect;
 477         find_short_object_filename(&ds);
 478         find_short_packed_object(&ds);
 479
 480         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 481         oid_array_clear(&collect);
 482         return ret;
 483 }
 484
 485 /*
 486  * Return the slot of the most-significant bit set in "val". There are various
 487  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 488  * probably not a big deal here.
 489  */
 490 static unsigned msb(unsigned long val)
 491 {
 492         unsigned r = 0;
 493         while (val >>= 1)
 494                 r++;
 495         return r;
 496 }
 497
 498 struct min_abbrev_data {
 499         unsigned int init_len;
 500         unsigned int cur_len;
 501         char *hex;
 502         const struct object_id *oid;
 503 };
 504
 505 static inline char get_hex_char_from_oid(const struct object_id *oid,
 506                                          unsigned int pos)
 507 {
 508         static const char hex[] = "0123456789abcdef";
 509
 510         if ((pos & 1) == 0)
 511                 return hex[oid->hash[pos >> 1] >> 4];
 512         else
 513                 return hex[oid->hash[pos >> 1] & 0xf];
 514 }
 515
 516 static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
 517 {
 518         struct min_abbrev_data *mad = cb_data;
 519
 520         unsigned int i = mad->init_len;
 521         while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
 522                 i++;
 523
 524         if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
 525                 mad->cur_len = i + 1;
 526
 527         return 0;
 528 }
 529
 530 static void find_abbrev_len_for_pack(struct packed_git *p,
 531                                      struct min_abbrev_data *mad)
 532 {
 533         int match = 0;
 534         uint32_t num, first = 0;
 535         struct object_id oid;
 536         const struct object_id *mad_oid;
 537
 538         if (open_pack_index(p) || !p->num_objects)
 539                 return;
 540
 541         num = p->num_objects;
 542         mad_oid = mad->oid;
 543         match = bsearch_pack(mad_oid, p, &first);
 544
 545         /*
 546          * first is now the position in the packfile where we would insert
 547          * mad->hash if it does not exist (or the position of mad->hash if
 548          * it does exist). Hence, we consider a maximum of two objects
 549          * nearby for the abbreviation length.
 550          */
 551         mad->init_len = 0;
 552         if (!match) {
 553                 if (nth_packed_object_oid(&oid, p, first))
 554                         extend_abbrev_len(&oid, mad);
 555         } else if (first < num - 1) {
 556                 if (nth_packed_object_oid(&oid, p, first + 1))
 557                         extend_abbrev_len(&oid, mad);
 558         }
 559         if (first > 0) {
 560                 if (nth_packed_object_oid(&oid, p, first - 1))
 561                         extend_abbrev_len(&oid, mad);
 562         }
 563         mad->init_len = mad->cur_len;
 564 }
 565
 566 static void find_abbrev_len_packed(struct min_abbrev_data *mad)
 567 {
 568         struct packed_git *p;
 569
 570         for (p = get_packed_git(the_repository); p; p = p->next)
 571                 find_abbrev_len_for_pack(p, mad);
 572 }
 573
 574 int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 575 {
 576         struct disambiguate_state ds;
 577         struct min_abbrev_data mad;
 578         struct object_id oid_ret;
 579         if (len < 0) {
 580                 unsigned long count = approximate_object_count();
 581                 /*
 582                  * Add one because the MSB only tells us the highest bit set,
 583                  * not including the value of all the _other_ bits (so "15"
 584                  * is only one off of 2^4, but the MSB is the 3rd bit.
 585                  */
 586                 len = msb(count) + 1;
 587                 /*
 588                  * We now know we have on the order of 2^len objects, which
 589                  * expects a collision at 2^(len/2). But we also care about hex
 590                  * chars, not bits, and there are 4 bits per hex. So all
 591                  * together we need to divide by 2 and round up.
 592                  */
 593                 len = DIV_ROUND_UP(len, 2);
 594                 /*
 595                  * For very small repos, we stick with our regular fallback.
 596                  */
 597                 if (len < FALLBACK_DEFAULT_ABBREV)
 598                         len = FALLBACK_DEFAULT_ABBREV;
 599         }
 600
 601         oid_to_hex_r(hex, oid);
 602         if (len == GIT_SHA1_HEXSZ || !len)
 603                 return GIT_SHA1_HEXSZ;
 604
 605         mad.init_len = len;
 606         mad.cur_len = len;
 607         mad.hex = hex;
 608         mad.oid = oid;
 609
 610         find_abbrev_len_packed(&mad);
 611
 612         if (init_object_disambiguation(hex, mad.cur_len, &ds) < 0)
 613                 return -1;
 614
 615         ds.fn = extend_abbrev_len;
 616         ds.always_call_fn = 1;
 617         ds.cb_data = (void *)&mad;
 618
 619         find_short_object_filename(&ds);
 620         (void)finish_object_disambiguation(&ds, &oid_ret);
 621
 622         hex[mad.cur_len] = 0;
 623         return mad.cur_len;
 624 }
 625
 626 const char *find_unique_abbrev(const struct object_id *oid, int len)
 627 {
 628         static int bufno;
 629         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 630         char *hex = hexbuffer[bufno];
 631         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 632         find_unique_abbrev_r(hex, oid, len);
 633         return hex;
 634 }
 635
 636 static int ambiguous_path(const char *path, int len)
 637 {
 638         int slash = 1;
 639         int cnt;
 640
 641         for (cnt = 0; cnt < len; cnt++) {
 642                 switch (*path++) {
 643                 case '\0':
 644                         break;
 645                 case '/':
 646                         if (slash)
 647                                 break;
 648                         slash = 1;
 649                         continue;
 650                 case '.':
 651                         continue;
 652                 default:
 653                         slash = 0;
 654                         continue;
 655                 }
 656                 break;
 657         }
 658         return slash;
 659 }
 660
 661 static inline int at_mark(const char *string, int len,
 662                           const char **suffix, int nr)
 663 {
 664         int i;
 665
 666         for (i = 0; i < nr; i++) {
 667                 int suffix_len = strlen(suffix[i]);
 668                 if (suffix_len <= len
 669                     && !strncasecmp(string, suffix[i], suffix_len))
 670                         return suffix_len;
 671         }
 672         return 0;
 673 }
 674
 675 static inline int upstream_mark(const char *string, int len)
 676 {
 677         const char *suffix[] = { "@{upstream}", "@{u}" };
 678         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 679 }
 680
 681 static inline int push_mark(const char *string, int len)
 682 {
 683         const char *suffix[] = { "@{push}" };
 684         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 685 }
 686
 687 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 688 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 689
 690 static int get_oid_basic(const char *str, int len, struct object_id *oid,
 691                           unsigned int flags)
 692 {
 693         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 694         static const char *object_name_msg = N_(
 695         "Git normally never creates a ref that ends with 40 hex characters\n"
 696         "because it will be ignored when you just specify 40-hex. These refs\n"
 697         "may be created by mistake. For example,\n"
 698         "\n"
 699         "  git checkout -b $br $(git rev-parse ...)\n"
 700         "\n"
 701         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 702         "examine these refs and maybe delete them. Turn this message off by\n"
 703         "running \"git config advice.objectNameWarning false\"");
 704         struct object_id tmp_oid;
 705         char *real_ref = NULL;
 706         int refs_found = 0;
 707         int at, reflog_len, nth_prior = 0;
 708
 709         if (len == GIT_SHA1_HEXSZ && !get_oid_hex(str, oid)) {
 710                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 711                         refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
 712                         if (refs_found > 0) {
 713                                 warning(warn_msg, len, str);
 714                                 if (advice_object_name_warning)
 715                                         fprintf(stderr, "%s\n", _(object_name_msg));
 716                         }
 717                         free(real_ref);
 718                 }
 719                 return 0;
 720         }
 721
 722         /* basic@{time or number or -number} format to query ref-log */
 723         reflog_len = at = 0;
 724         if (len && str[len-1] == '}') {
 725                 for (at = len-4; at >= 0; at--) {
 726                         if (str[at] == '@' && str[at+1] == '{') {
 727                                 if (str[at+2] == '-') {
 728                                         if (at != 0)
 729                                                 /* @{-N} not at start */
 730                                                 return -1;
 731                                         nth_prior = 1;
 732                                         continue;
 733                                 }
 734                                 if (!upstream_mark(str + at, len - at) &&
 735                                     !push_mark(str + at, len - at)) {
 736                                         reflog_len = (len-1) - (at+2);
 737                                         len = at;
 738                                 }
 739                                 break;
 740                         }
 741                 }
 742         }
 743
 744         /* Accept only unambiguous ref paths. */
 745         if (len && ambiguous_path(str, len))
 746                 return -1;
 747
 748         if (nth_prior) {
 749                 struct strbuf buf = STRBUF_INIT;
 750                 int detached;
 751
 752                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 753                         detached = (buf.len == GIT_SHA1_HEXSZ && !get_oid_hex(buf.buf, oid));
 754                         strbuf_release(&buf);
 755                         if (detached)
 756                                 return 0;
 757                 }
 758         }
 759
 760         if (!len && reflog_len)
 761                 /* allow "@{...}" to mean the current branch reflog */
 762                 refs_found = dwim_ref("HEAD", 4, oid, &real_ref);
 763         else if (reflog_len)
 764                 refs_found = dwim_log(str, len, oid, &real_ref);
 765         else
 766                 refs_found = dwim_ref(str, len, oid, &real_ref);
 767
 768         if (!refs_found)
 769                 return -1;
 770
 771         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 772             (refs_found > 1 ||
 773              !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
 774                 warning(warn_msg, len, str);
 775
 776         if (reflog_len) {
 777                 int nth, i;
 778                 timestamp_t at_time;
 779                 timestamp_t co_time;
 780                 int co_tz, co_cnt;
 781
 782                 /* Is it asking for N-th entry, or approxidate? */
 783                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 784                         char ch = str[at+2+i];
 785                         if ('0' <= ch && ch <= '9')
 786                                 nth = nth * 10 + ch - '0';
 787                         else
 788                                 nth = -1;
 789                 }
 790                 if (100000000 <= nth) {
 791                         at_time = nth;
 792                         nth = -1;
 793                 } else if (0 <= nth)
 794                         at_time = 0;
 795                 else {
 796                         int errors = 0;
 797                         char *tmp = xstrndup(str + at + 2, reflog_len);
 798                         at_time = approxidate_careful(tmp, &errors);
 799                         free(tmp);
 800                         if (errors) {
 801                                 free(real_ref);
 802                                 return -1;
 803                         }
 804                 }
 805                 if (read_ref_at(real_ref, flags, at_time, nth, oid, NULL,
 806                                 &co_time, &co_tz, &co_cnt)) {
 807                         if (!len) {
 808                                 if (starts_with(real_ref, "refs/heads/")) {
 809                                         str = real_ref + 11;
 810                                         len = strlen(real_ref + 11);
 811                                 } else {
 812                                         /* detached HEAD */
 813                                         str = "HEAD";
 814                                         len = 4;
 815                                 }
 816                         }
 817                         if (at_time) {
 818                                 if (!(flags & GET_OID_QUIETLY)) {
 819                                         warning("Log for '%.*s' only goes "
 820                                                 "back to %s.", len, str,
 821                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 822                                 }
 823                         } else {
 824                                 if (flags & GET_OID_QUIETLY) {
 825                                         exit(128);
 826                                 }
 827                                 die("Log for '%.*s' only has %d entries.",
 828                                     len, str, co_cnt);
 829                         }
 830                 }
 831         }
 832
 833         free(real_ref);
 834         return 0;
 835 }
 836
 837 static int get_parent(const char *name, int len,
 838                       struct object_id *result, int idx)
 839 {
 840         struct object_id oid;
 841         int ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 842         struct commit *commit;
 843         struct commit_list *p;
 844
 845         if (ret)
 846                 return ret;
 847         commit = lookup_commit_reference(&oid);
 848         if (parse_commit(commit))
 849                 return -1;
 850         if (!idx) {
 851                 oidcpy(result, &commit->object.oid);
 852                 return 0;
 853         }
 854         p = commit->parents;
 855         while (p) {
 856                 if (!--idx) {
 857                         oidcpy(result, &p->item->object.oid);
 858                         return 0;
 859                 }
 860                 p = p->next;
 861         }
 862         return -1;
 863 }
 864
 865 static int get_nth_ancestor(const char *name, int len,
 866                             struct object_id *result, int generation)
 867 {
 868         struct object_id oid;
 869         struct commit *commit;
 870         int ret;
 871
 872         ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 873         if (ret)
 874                 return ret;
 875         commit = lookup_commit_reference(&oid);
 876         if (!commit)
 877                 return -1;
 878
 879         while (generation--) {
 880                 if (parse_commit(commit) || !commit->parents)
 881                         return -1;
 882                 commit = commit->parents->item;
 883         }
 884         oidcpy(result, &commit->object.oid);
 885         return 0;
 886 }
 887
 888 struct object *peel_to_type(const char *name, int namelen,
 889                             struct object *o, enum object_type expected_type)
 890 {
 891         if (name && !namelen)
 892                 namelen = strlen(name);
 893         while (1) {
 894                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 895                         return NULL;
 896                 if (expected_type == OBJ_ANY || o->type == expected_type)
 897                         return o;
 898                 if (o->type == OBJ_TAG)
 899                         o = ((struct tag*) o)->tagged;
 900                 else if (o->type == OBJ_COMMIT)
 901                         o = &(get_commit_tree(((struct commit *)o))->object);
 902                 else {
 903                         if (name)
 904                                 error("%.*s: expected %s type, but the object "
 905                                       "dereferences to %s type",
 906                                       namelen, name, type_name(expected_type),
 907                                       type_name(o->type));
 908                         return NULL;
 909                 }
 910         }
 911 }
 912
 913 static int peel_onion(const char *name, int len, struct object_id *oid,
 914                       unsigned lookup_flags)
 915 {
 916         struct object_id outer;
 917         const char *sp;
 918         unsigned int expected_type = 0;
 919         struct object *o;
 920
 921         /*
 922          * "ref^{type}" dereferences ref repeatedly until you cannot
 923          * dereference anymore, or you get an object of given type,
 924          * whichever comes first.  "ref^{}" means just dereference
 925          * tags until you get a non-tag.  "ref^0" is a shorthand for
 926          * "ref^{commit}".  "commit^{tree}" could be used to find the
 927          * top-level tree of the given commit.
 928          */
 929         if (len < 4 || name[len-1] != '}')
 930                 return -1;
 931
 932         for (sp = name + len - 1; name <= sp; sp--) {
 933                 int ch = *sp;
 934                 if (ch == '{' && name < sp && sp[-1] == '^')
 935                         break;
 936         }
 937         if (sp <= name)
 938                 return -1;
 939
 940         sp++; /* beginning of type name, or closing brace for empty */
 941         if (starts_with(sp, "commit}"))
 942                 expected_type = OBJ_COMMIT;
 943         else if (starts_with(sp, "tag}"))
 944                 expected_type = OBJ_TAG;
 945         else if (starts_with(sp, "tree}"))
 946                 expected_type = OBJ_TREE;
 947         else if (starts_with(sp, "blob}"))
 948                 expected_type = OBJ_BLOB;
 949         else if (starts_with(sp, "object}"))
 950                 expected_type = OBJ_ANY;
 951         else if (sp[0] == '}')
 952                 expected_type = OBJ_NONE;
 953         else if (sp[0] == '/')
 954                 expected_type = OBJ_COMMIT;
 955         else
 956                 return -1;
 957
 958         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
 959         if (expected_type == OBJ_COMMIT)
 960                 lookup_flags |= GET_OID_COMMITTISH;
 961         else if (expected_type == OBJ_TREE)
 962                 lookup_flags |= GET_OID_TREEISH;
 963
 964         if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
 965                 return -1;
 966
 967         o = parse_object(&outer);
 968         if (!o)
 969                 return -1;
 970         if (!expected_type) {
 971                 o = deref_tag(o, name, sp - name - 2);
 972                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 973                         return -1;
 974                 oidcpy(oid, &o->oid);
 975                 return 0;
 976         }
 977
 978         /*
 979          * At this point, the syntax look correct, so
 980          * if we do not get the needed object, we should
 981          * barf.
 982          */
 983         o = peel_to_type(name, len, o, expected_type);
 984         if (!o)
 985                 return -1;
 986
 987         oidcpy(oid, &o->oid);
 988         if (sp[0] == '/') {
 989                 /* "$commit^{/foo}" */
 990                 char *prefix;
 991                 int ret;
 992                 struct commit_list *list = NULL;
 993
 994                 /*
 995                  * $commit^{/}. Some regex implementation may reject.
 996                  * We don't need regex anyway. '' pattern always matches.
 997                  */
 998                 if (sp[1] == '}')
 999                         return 0;
1000
1001                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1002                 commit_list_insert((struct commit *)o, &list);
1003                 ret = get_oid_oneline(prefix, oid, list);
1004                 free(prefix);
1005                 return ret;
1006         }
1007         return 0;
1008 }
1009
1010 static int get_describe_name(const char *name, int len, struct object_id *oid)
1011 {
1012         const char *cp;
1013         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1014
1015         for (cp = name + len - 1; name + 2 <= cp; cp--) {
1016                 char ch = *cp;
1017                 if (!isxdigit(ch)) {
1018                         /* We must be looking at g in "SOMETHING-g"
1019                          * for it to be describe output.
1020                          */
1021                         if (ch == 'g' && cp[-1] == '-') {
1022                                 cp++;
1023                                 len -= cp - name;
1024                                 return get_short_oid(cp, len, oid, flags);
1025                         }
1026                 }
1027         }
1028         return -1;
1029 }
1030
1031 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags)
1032 {
1033         int ret, has_suffix;
1034         const char *cp;
1035
1036         /*
1037          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1038          */
1039         has_suffix = 0;
1040         for (cp = name + len - 1; name <= cp; cp--) {
1041                 int ch = *cp;
1042                 if ('0' <= ch && ch <= '9')
1043                         continue;
1044                 if (ch == '~' || ch == '^')
1045                         has_suffix = ch;
1046                 break;
1047         }
1048
1049         if (has_suffix) {
1050                 int num = 0;
1051                 int len1 = cp - name;
1052                 cp++;
1053                 while (cp < name + len)
1054                         num = num * 10 + *cp++ - '0';
1055                 if (!num && len1 == len - 1)
1056                         num = 1;
1057                 if (has_suffix == '^')
1058                         return get_parent(name, len1, oid, num);
1059                 /* else if (has_suffix == '~') -- goes without saying */
1060                 return get_nth_ancestor(name, len1, oid, num);
1061         }
1062
1063         ret = peel_onion(name, len, oid, lookup_flags);
1064         if (!ret)
1065                 return 0;
1066
1067         ret = get_oid_basic(name, len, oid, lookup_flags);
1068         if (!ret)
1069                 return 0;
1070
1071         /* It could be describe output that is "SOMETHING-gXXXX" */
1072         ret = get_describe_name(name, len, oid);
1073         if (!ret)
1074                 return 0;
1075
1076         return get_short_oid(name, len, oid, lookup_flags);
1077 }
1078
1079 /*
1080  * This interprets names like ':/Initial revision of "git"' by searching
1081  * through history and returning the first commit whose message starts
1082  * the given regular expression.
1083  *
1084  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1085  *
1086  * For a literal '!' character at the beginning of a pattern, you have to repeat
1087  * that, like: ':/!!foo'
1088  *
1089  * For future extension, all other sequences beginning with ':/!' are reserved.
1090  */
1091
1092 /* Remember to update object flag allocation in object.h */
1093 #define ONELINE_SEEN (1u<<20)
1094
1095 static int handle_one_ref(const char *path, const struct object_id *oid,
1096                           int flag, void *cb_data)
1097 {
1098         struct commit_list **list = cb_data;
1099         struct object *object = parse_object(oid);
1100         if (!object)
1101                 return 0;
1102         if (object->type == OBJ_TAG) {
1103                 object = deref_tag(object, path, strlen(path));
1104                 if (!object)
1105                         return 0;
1106         }
1107         if (object->type != OBJ_COMMIT)
1108                 return 0;
1109         commit_list_insert((struct commit *)object, list);
1110         return 0;
1111 }
1112
1113 static int get_oid_oneline(const char *prefix, struct object_id *oid,
1114                             struct commit_list *list)
1115 {
1116         struct commit_list *backup = NULL, *l;
1117         int found = 0;
1118         int negative = 0;
1119         regex_t regex;
1120
1121         if (prefix[0] == '!') {
1122                 prefix++;
1123
1124                 if (prefix[0] == '-') {
1125                         prefix++;
1126                         negative = 1;
1127                 } else if (prefix[0] != '!') {
1128                         return -1;
1129                 }
1130         }
1131
1132         if (regcomp(&regex, prefix, REG_EXTENDED))
1133                 return -1;
1134
1135         for (l = list; l; l = l->next) {
1136                 l->item->object.flags |= ONELINE_SEEN;
1137                 commit_list_insert(l->item, &backup);
1138         }
1139         while (list) {
1140                 const char *p, *buf;
1141                 struct commit *commit;
1142                 int matches;
1143
1144                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1145                 if (!parse_object(&commit->object.oid))
1146                         continue;
1147                 buf = get_commit_buffer(commit, NULL);
1148                 p = strstr(buf, "\n\n");
1149                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1150                 unuse_commit_buffer(commit, buf);
1151
1152                 if (matches) {
1153                         oidcpy(oid, &commit->object.oid);
1154                         found = 1;
1155                         break;
1156                 }
1157         }
1158         regfree(&regex);
1159         free_commit_list(list);
1160         for (l = backup; l; l = l->next)
1161                 clear_commit_marks(l->item, ONELINE_SEEN);
1162         free_commit_list(backup);
1163         return found ? 0 : -1;
1164 }
1165
1166 struct grab_nth_branch_switch_cbdata {
1167         int remaining;
1168         struct strbuf buf;
1169 };
1170
1171 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1172                                   const char *email, timestamp_t timestamp, int tz,
1173                                   const char *message, void *cb_data)
1174 {
1175         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1176         const char *match = NULL, *target = NULL;
1177         size_t len;
1178
1179         if (skip_prefix(message, "checkout: moving from ", &match))
1180                 target = strstr(match, " to ");
1181
1182         if (!match || !target)
1183                 return 0;
1184         if (--(cb->remaining) == 0) {
1185                 len = target - match;
1186                 strbuf_reset(&cb->buf);
1187                 strbuf_add(&cb->buf, match, len);
1188                 return 1; /* we are done */
1189         }
1190         return 0;
1191 }
1192
1193 /*
1194  * Parse @{-N} syntax, return the number of characters parsed
1195  * if successful; otherwise signal an error with negative value.
1196  */
1197 static int interpret_nth_prior_checkout(const char *name, int namelen,
1198                                         struct strbuf *buf)
1199 {
1200         long nth;
1201         int retval;
1202         struct grab_nth_branch_switch_cbdata cb;
1203         const char *brace;
1204         char *num_end;
1205
1206         if (namelen < 4)
1207                 return -1;
1208         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1209                 return -1;
1210         brace = memchr(name, '}', namelen);
1211         if (!brace)
1212                 return -1;
1213         nth = strtol(name + 3, &num_end, 10);
1214         if (num_end != brace)
1215                 return -1;
1216         if (nth <= 0)
1217                 return -1;
1218         cb.remaining = nth;
1219         strbuf_init(&cb.buf, 20);
1220
1221         retval = 0;
1222         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1223                 strbuf_reset(buf);
1224                 strbuf_addbuf(buf, &cb.buf);
1225                 retval = brace - name + 1;
1226         }
1227
1228         strbuf_release(&cb.buf);
1229         return retval;
1230 }
1231
1232 int get_oid_mb(const char *name, struct object_id *oid)
1233 {
1234         struct commit *one, *two;
1235         struct commit_list *mbs;
1236         struct object_id oid_tmp;
1237         const char *dots;
1238         int st;
1239
1240         dots = strstr(name, "...");
1241         if (!dots)
1242                 return get_oid(name, oid);
1243         if (dots == name)
1244                 st = get_oid("HEAD", &oid_tmp);
1245         else {
1246                 struct strbuf sb;
1247                 strbuf_init(&sb, dots - name);
1248                 strbuf_add(&sb, name, dots - name);
1249                 st = get_oid_committish(sb.buf, &oid_tmp);
1250                 strbuf_release(&sb);
1251         }
1252         if (st)
1253                 return st;
1254         one = lookup_commit_reference_gently(&oid_tmp, 0);
1255         if (!one)
1256                 return -1;
1257
1258         if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1259                 return -1;
1260         two = lookup_commit_reference_gently(&oid_tmp, 0);
1261         if (!two)
1262                 return -1;
1263         mbs = get_merge_bases(one, two);
1264         if (!mbs || mbs->next)
1265                 st = -1;
1266         else {
1267                 st = 0;
1268                 oidcpy(oid, &mbs->item->object.oid);
1269         }
1270         free_commit_list(mbs);
1271         return st;
1272 }
1273
1274 /* parse @something syntax, when 'something' is not {.*} */
1275 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1276 {
1277         const char *next;
1278
1279         if (len || name[1] == '{')
1280                 return -1;
1281
1282         /* make sure it's a single @, or @@{.*}, not @foo */
1283         next = memchr(name + len + 1, '@', namelen - len - 1);
1284         if (next && next[1] != '{')
1285                 return -1;
1286         if (!next)
1287                 next = name + namelen;
1288         if (next != name + 1)
1289                 return -1;
1290
1291         strbuf_reset(buf);
1292         strbuf_add(buf, "HEAD", 4);
1293         return 1;
1294 }
1295
1296 static int reinterpret(const char *name, int namelen, int len,
1297                        struct strbuf *buf, unsigned allowed)
1298 {
1299         /* we have extra data, which might need further processing */
1300         struct strbuf tmp = STRBUF_INIT;
1301         int used = buf->len;
1302         int ret;
1303
1304         strbuf_add(buf, name + len, namelen - len);
1305         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1306         /* that data was not interpreted, remove our cruft */
1307         if (ret < 0) {
1308                 strbuf_setlen(buf, used);
1309                 return len;
1310         }
1311         strbuf_reset(buf);
1312         strbuf_addbuf(buf, &tmp);
1313         strbuf_release(&tmp);
1314         /* tweak for size of {-N} versus expanded ref name */
1315         return ret - used + len;
1316 }
1317
1318 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1319 {
1320         char *s = shorten_unambiguous_ref(ref, 0);
1321         strbuf_reset(buf);
1322         strbuf_addstr(buf, s);
1323         free(s);
1324 }
1325
1326 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1327 {
1328         if (!allowed)
1329                 return 1;
1330
1331         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1332             starts_with(refname, "refs/heads/"))
1333                 return 1;
1334         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1335             starts_with(refname, "refs/remotes/"))
1336                 return 1;
1337
1338         return 0;
1339 }
1340
1341 static int interpret_branch_mark(const char *name, int namelen,
1342                                  int at, struct strbuf *buf,
1343                                  int (*get_mark)(const char *, int),
1344                                  const char *(*get_data)(struct branch *,
1345                                                          struct strbuf *),
1346                                  unsigned allowed)
1347 {
1348         int len;
1349         struct branch *branch;
1350         struct strbuf err = STRBUF_INIT;
1351         const char *value;
1352
1353         len = get_mark(name + at, namelen - at);
1354         if (!len)
1355                 return -1;
1356
1357         if (memchr(name, ':', at))
1358                 return -1;
1359
1360         if (at) {
1361                 char *name_str = xmemdupz(name, at);
1362                 branch = branch_get(name_str);
1363                 free(name_str);
1364         } else
1365                 branch = branch_get(NULL);
1366
1367         value = get_data(branch, &err);
1368         if (!value)
1369                 die("%s", err.buf);
1370
1371         if (!branch_interpret_allowed(value, allowed))
1372                 return -1;
1373
1374         set_shortened_ref(buf, value);
1375         return len + at;
1376 }
1377
1378 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1379                           unsigned allowed)
1380 {
1381         char *at;
1382         const char *start;
1383         int len;
1384
1385         if (!namelen)
1386                 namelen = strlen(name);
1387
1388         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1389                 len = interpret_nth_prior_checkout(name, namelen, buf);
1390                 if (!len) {
1391                         return len; /* syntax Ok, not enough switches */
1392                 } else if (len > 0) {
1393                         if (len == namelen)
1394                                 return len; /* consumed all */
1395                         else
1396                                 return reinterpret(name, namelen, len, buf, allowed);
1397                 }
1398         }
1399
1400         for (start = name;
1401              (at = memchr(start, '@', namelen - (start - name)));
1402              start = at + 1) {
1403
1404                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1405                         len = interpret_empty_at(name, namelen, at - name, buf);
1406                         if (len > 0)
1407                                 return reinterpret(name, namelen, len, buf,
1408                                                    allowed);
1409                 }
1410
1411                 len = interpret_branch_mark(name, namelen, at - name, buf,
1412                                             upstream_mark, branch_get_upstream,
1413                                             allowed);
1414                 if (len > 0)
1415                         return len;
1416
1417                 len = interpret_branch_mark(name, namelen, at - name, buf,
1418                                             push_mark, branch_get_push,
1419                                             allowed);
1420                 if (len > 0)
1421                         return len;
1422         }
1423
1424         return -1;
1425 }
1426
1427 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1428 {
1429         int len = strlen(name);
1430         int used = interpret_branch_name(name, len, sb, allowed);
1431
1432         if (used < 0)
1433                 used = 0;
1434         strbuf_add(sb, name + used, len - used);
1435 }
1436
1437 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1438 {
1439         if (startup_info->have_repository)
1440                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1441         else
1442                 strbuf_addstr(sb, name);
1443
1444         /*
1445          * This splice must be done even if we end up rejecting the
1446          * name; builtin/branch.c::copy_or_rename_branch() still wants
1447          * to see what the name expanded to so that "branch -m" can be
1448          * used as a tool to correct earlier mistakes.
1449          */
1450         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1451
1452         if (*name == '-' ||
1453             !strcmp(sb->buf, "refs/heads/HEAD"))
1454                 return -1;
1455
1456         return check_refname_format(sb->buf, 0);
1457 }
1458
1459 /*
1460  * This is like "get_oid_basic()", except it allows "object ID expressions",
1461  * notably "xyz^" for "parent of xyz"
1462  */
1463 int get_oid(const char *name, struct object_id *oid)
1464 {
1465         struct object_context unused;
1466         return get_oid_with_context(name, 0, oid, &unused);
1467 }
1468
1469
1470 /*
1471  * Many callers know that the user meant to name a commit-ish by
1472  * syntactical positions where the object name appears.  Calling this
1473  * function allows the machinery to disambiguate shorter-than-unique
1474  * abbreviated object names between commit-ish and others.
1475  *
1476  * Note that this does NOT error out when the named object is not a
1477  * commit-ish. It is merely to give a hint to the disambiguation
1478  * machinery.
1479  */
1480 int get_oid_committish(const char *name, struct object_id *oid)
1481 {
1482         struct object_context unused;
1483         return get_oid_with_context(name, GET_OID_COMMITTISH,
1484                                     oid, &unused);
1485 }
1486
1487 int get_oid_treeish(const char *name, struct object_id *oid)
1488 {
1489         struct object_context unused;
1490         return get_oid_with_context(name, GET_OID_TREEISH,
1491                                     oid, &unused);
1492 }
1493
1494 int get_oid_commit(const char *name, struct object_id *oid)
1495 {
1496         struct object_context unused;
1497         return get_oid_with_context(name, GET_OID_COMMIT,
1498                                     oid, &unused);
1499 }
1500
1501 int get_oid_tree(const char *name, struct object_id *oid)
1502 {
1503         struct object_context unused;
1504         return get_oid_with_context(name, GET_OID_TREE,
1505                                     oid, &unused);
1506 }
1507
1508 int get_oid_blob(const char *name, struct object_id *oid)
1509 {
1510         struct object_context unused;
1511         return get_oid_with_context(name, GET_OID_BLOB,
1512                                     oid, &unused);
1513 }
1514
1515 /* Must be called only when object_name:filename doesn't exist. */
1516 static void diagnose_invalid_oid_path(const char *prefix,
1517                                       const char *filename,
1518                                       const struct object_id *tree_oid,
1519                                       const char *object_name,
1520                                       int object_name_len)
1521 {
1522         struct object_id oid;
1523         unsigned mode;
1524
1525         if (!prefix)
1526                 prefix = "";
1527
1528         if (file_exists(filename))
1529                 die("Path '%s' exists on disk, but not in '%.*s'.",
1530                     filename, object_name_len, object_name);
1531         if (is_missing_file_error(errno)) {
1532                 char *fullname = xstrfmt("%s%s", prefix, filename);
1533
1534                 if (!get_tree_entry(tree_oid, fullname, &oid, &mode)) {
1535                         die("Path '%s' exists, but not '%s'.\n"
1536                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1537                             fullname,
1538                             filename,
1539                             object_name_len, object_name,
1540                             fullname,
1541                             object_name_len, object_name,
1542                             filename);
1543                 }
1544                 die("Path '%s' does not exist in '%.*s'",
1545                     filename, object_name_len, object_name);
1546         }
1547 }
1548
1549 /* Must be called only when :stage:filename doesn't exist. */
1550 static void diagnose_invalid_index_path(int stage,
1551                                         const char *prefix,
1552                                         const char *filename)
1553 {
1554         const struct cache_entry *ce;
1555         int pos;
1556         unsigned namelen = strlen(filename);
1557         struct strbuf fullname = STRBUF_INIT;
1558
1559         if (!prefix)
1560                 prefix = "";
1561
1562         /* Wrong stage number? */
1563         pos = cache_name_pos(filename, namelen);
1564         if (pos < 0)
1565                 pos = -pos - 1;
1566         if (pos < active_nr) {
1567                 ce = active_cache[pos];
1568                 if (ce_namelen(ce) == namelen &&
1569                     !memcmp(ce->name, filename, namelen))
1570                         die("Path '%s' is in the index, but not at stage %d.\n"
1571                             "Did you mean ':%d:%s'?",
1572                             filename, stage,
1573                             ce_stage(ce), filename);
1574         }
1575
1576         /* Confusion between relative and absolute filenames? */
1577         strbuf_addstr(&fullname, prefix);
1578         strbuf_addstr(&fullname, filename);
1579         pos = cache_name_pos(fullname.buf, fullname.len);
1580         if (pos < 0)
1581                 pos = -pos - 1;
1582         if (pos < active_nr) {
1583                 ce = active_cache[pos];
1584                 if (ce_namelen(ce) == fullname.len &&
1585                     !memcmp(ce->name, fullname.buf, fullname.len))
1586                         die("Path '%s' is in the index, but not '%s'.\n"
1587                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1588                             fullname.buf, filename,
1589                             ce_stage(ce), fullname.buf,
1590                             ce_stage(ce), filename);
1591         }
1592
1593         if (file_exists(filename))
1594                 die("Path '%s' exists on disk, but not in the index.", filename);
1595         if (is_missing_file_error(errno))
1596                 die("Path '%s' does not exist (neither on disk nor in the index).",
1597                     filename);
1598
1599         strbuf_release(&fullname);
1600 }
1601
1602
1603 static char *resolve_relative_path(const char *rel)
1604 {
1605         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1606                 return NULL;
1607
1608         if (!is_inside_work_tree())
1609                 die("relative path syntax can't be used outside working tree.");
1610
1611         /* die() inside prefix_path() if resolved path is outside worktree */
1612         return prefix_path(startup_info->prefix,
1613                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1614                            rel);
1615 }
1616
1617 static int get_oid_with_context_1(const char *name,
1618                                   unsigned flags,
1619                                   const char *prefix,
1620                                   struct object_id *oid,
1621                                   struct object_context *oc)
1622 {
1623         int ret, bracket_depth;
1624         int namelen = strlen(name);
1625         const char *cp;
1626         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1627
1628         if (only_to_die)
1629                 flags |= GET_OID_QUIETLY;
1630
1631         memset(oc, 0, sizeof(*oc));
1632         oc->mode = S_IFINVALID;
1633         strbuf_init(&oc->symlink_path, 0);
1634         ret = get_oid_1(name, namelen, oid, flags);
1635         if (!ret)
1636                 return ret;
1637         /*
1638          * sha1:path --> object name of path in ent sha1
1639          * :path -> object name of absolute path in index
1640          * :./path -> object name of path relative to cwd in index
1641          * :[0-3]:path -> object name of path in index at stage
1642          * :/foo -> recent commit matching foo
1643          */
1644         if (name[0] == ':') {
1645                 int stage = 0;
1646                 const struct cache_entry *ce;
1647                 char *new_path = NULL;
1648                 int pos;
1649                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1650                         struct commit_list *list = NULL;
1651
1652                         for_each_ref(handle_one_ref, &list);
1653                         commit_list_sort_by_date(&list);
1654                         return get_oid_oneline(name + 2, oid, list);
1655                 }
1656                 if (namelen < 3 ||
1657                     name[2] != ':' ||
1658                     name[1] < '0' || '3' < name[1])
1659                         cp = name + 1;
1660                 else {
1661                         stage = name[1] - '0';
1662                         cp = name + 3;
1663                 }
1664                 new_path = resolve_relative_path(cp);
1665                 if (!new_path) {
1666                         namelen = namelen - (cp - name);
1667                 } else {
1668                         cp = new_path;
1669                         namelen = strlen(cp);
1670                 }
1671
1672                 if (flags & GET_OID_RECORD_PATH)
1673                         oc->path = xstrdup(cp);
1674
1675                 if (!active_cache)
1676                         read_cache();
1677                 pos = cache_name_pos(cp, namelen);
1678                 if (pos < 0)
1679                         pos = -pos - 1;
1680                 while (pos < active_nr) {
1681                         ce = active_cache[pos];
1682                         if (ce_namelen(ce) != namelen ||
1683                             memcmp(ce->name, cp, namelen))
1684                                 break;
1685                         if (ce_stage(ce) == stage) {
1686                                 oidcpy(oid, &ce->oid);
1687                                 oc->mode = ce->ce_mode;
1688                                 free(new_path);
1689                                 return 0;
1690                         }
1691                         pos++;
1692                 }
1693                 if (only_to_die && name[1] && name[1] != '/')
1694                         diagnose_invalid_index_path(stage, prefix, cp);
1695                 free(new_path);
1696                 return -1;
1697         }
1698         for (cp = name, bracket_depth = 0; *cp; cp++) {
1699                 if (*cp == '{')
1700                         bracket_depth++;
1701                 else if (bracket_depth && *cp == '}')
1702                         bracket_depth--;
1703                 else if (!bracket_depth && *cp == ':')
1704                         break;
1705         }
1706         if (*cp == ':') {
1707                 struct object_id tree_oid;
1708                 int len = cp - name;
1709                 unsigned sub_flags = flags;
1710
1711                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1712                 sub_flags |= GET_OID_TREEISH;
1713
1714                 if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1715                         const char *filename = cp+1;
1716                         char *new_filename = NULL;
1717
1718                         new_filename = resolve_relative_path(filename);
1719                         if (new_filename)
1720                                 filename = new_filename;
1721                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1722                                 ret = get_tree_entry_follow_symlinks(&tree_oid,
1723                                         filename, oid, &oc->symlink_path,
1724                                         &oc->mode);
1725                         } else {
1726                                 ret = get_tree_entry(&tree_oid, filename, oid,
1727                                                      &oc->mode);
1728                                 if (ret && only_to_die) {
1729                                         diagnose_invalid_oid_path(prefix,
1730                                                                    filename,
1731                                                                    &tree_oid,
1732                                                                    name, len);
1733                                 }
1734                         }
1735                         if (flags & GET_OID_RECORD_PATH)
1736                                 oc->path = xstrdup(filename);
1737
1738                         free(new_filename);
1739                         return ret;
1740                 } else {
1741                         if (only_to_die)
1742                                 die("Invalid object name '%.*s'.", len, name);
1743                 }
1744         }
1745         return ret;
1746 }
1747
1748 /*
1749  * Call this function when you know "name" given by the end user must
1750  * name an object but it doesn't; the function _may_ die with a better
1751  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1752  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1753  * you have a chance to diagnose the error further.
1754  */
1755 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1756 {
1757         struct object_context oc;
1758         struct object_id oid;
1759         get_oid_with_context_1(name, GET_OID_ONLY_TO_DIE, prefix, &oid, &oc);
1760 }
1761
1762 int get_oid_with_context(const char *str, unsigned flags, struct object_id *oid, struct object_context *oc)
1763 {
1764         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1765                 BUG("incompatible flags for get_sha1_with_context");
1766         return get_oid_with_context_1(str, flags, NULL, oid, oc);
1767 }