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, last, 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         last = num;
 163         while (first < last) {
 164                 uint32_t mid = first + (last - first) / 2;
 165                 const unsigned char *current;
 166                 int cmp;
 167
 168                 current = nth_packed_object_sha1(p, mid);
 169                 cmp = hashcmp(ds->bin_pfx.hash, current);
 170                 if (!cmp) {
 171                         first = mid;
 172                         break;
 173                 }
 174                 if (cmp > 0) {
 175                         first = mid+1;
 176                         continue;
 177                 }
 178                 last = mid;
 179         }
 180
 181         /*
 182          * At this point, "first" is the location of the lowest object
 183          * with an object name that could match "bin_pfx".  See if we have
 184          * 0, 1 or more objects that actually match(es).
 185          */
 186         for (i = first; i < num && !ds->ambiguous; i++) {
 187                 struct object_id oid;
 188                 current = nth_packed_object_oid(&oid, p, i);
 189                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 190                         break;
 191                 update_candidates(ds, current);
 192         }
 193 }
 194
 195 static void find_short_packed_object(struct disambiguate_state *ds)
 196 {
 197         struct packed_git *p;
 198
 199         prepare_packed_git(the_repository);
 200         for (p = get_packed_git(the_repository); p && !ds->ambiguous;
 201              p = p->next)
 202                 unique_in_pack(p, ds);
 203 }
 204
 205 #define SHORT_NAME_NOT_FOUND (-1)
 206 #define SHORT_NAME_AMBIGUOUS (-2)
 207
 208 static int finish_object_disambiguation(struct disambiguate_state *ds,
 209                                         struct object_id *oid)
 210 {
 211         if (ds->ambiguous)
 212                 return SHORT_NAME_AMBIGUOUS;
 213
 214         if (!ds->candidate_exists)
 215                 return SHORT_NAME_NOT_FOUND;
 216
 217         if (!ds->candidate_checked)
 218                 /*
 219                  * If this is the only candidate, there is no point
 220                  * calling the disambiguation hint callback.
 221                  *
 222                  * On the other hand, if the current candidate
 223                  * replaced an earlier candidate that did _not_ pass
 224                  * the disambiguation hint callback, then we do have
 225                  * more than one objects that match the short name
 226                  * given, so we should make sure this one matches;
 227                  * otherwise, if we discovered this one and the one
 228                  * that we previously discarded in the reverse order,
 229                  * we would end up showing different results in the
 230                  * same repository!
 231                  */
 232                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 233                                     ds->fn(&ds->candidate, ds->cb_data));
 234
 235         if (!ds->candidate_ok)
 236                 return SHORT_NAME_AMBIGUOUS;
 237
 238         oidcpy(oid, &ds->candidate);
 239         return 0;
 240 }
 241
 242 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 243 {
 244         int kind = sha1_object_info(oid->hash, NULL);
 245         return kind == OBJ_COMMIT;
 246 }
 247
 248 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 249 {
 250         struct object *obj;
 251         int kind;
 252
 253         kind = sha1_object_info(oid->hash, NULL);
 254         if (kind == OBJ_COMMIT)
 255                 return 1;
 256         if (kind != OBJ_TAG)
 257                 return 0;
 258
 259         /* We need to do this the hard way... */
 260         obj = deref_tag(parse_object(oid), NULL, 0);
 261         if (obj && obj->type == OBJ_COMMIT)
 262                 return 1;
 263         return 0;
 264 }
 265
 266 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 267 {
 268         int kind = sha1_object_info(oid->hash, NULL);
 269         return kind == OBJ_TREE;
 270 }
 271
 272 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 273 {
 274         struct object *obj;
 275         int kind;
 276
 277         kind = sha1_object_info(oid->hash, NULL);
 278         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 279                 return 1;
 280         if (kind != OBJ_TAG)
 281                 return 0;
 282
 283         /* We need to do this the hard way... */
 284         obj = deref_tag(parse_object(oid), NULL, 0);
 285         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 286                 return 1;
 287         return 0;
 288 }
 289
 290 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 291 {
 292         int kind = sha1_object_info(oid->hash, NULL);
 293         return kind == OBJ_BLOB;
 294 }
 295
 296 static disambiguate_hint_fn default_disambiguate_hint;
 297
 298 int set_disambiguate_hint_config(const char *var, const char *value)
 299 {
 300         static const struct {
 301                 const char *name;
 302                 disambiguate_hint_fn fn;
 303         } hints[] = {
 304                 { "none", NULL },
 305                 { "commit", disambiguate_commit_only },
 306                 { "committish", disambiguate_committish_only },
 307                 { "tree", disambiguate_tree_only },
 308                 { "treeish", disambiguate_treeish_only },
 309                 { "blob", disambiguate_blob_only }
 310         };
 311         int i;
 312
 313         if (!value)
 314                 return config_error_nonbool(var);
 315
 316         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 317                 if (!strcasecmp(value, hints[i].name)) {
 318                         default_disambiguate_hint = hints[i].fn;
 319                         return 0;
 320                 }
 321         }
 322
 323         return error("unknown hint type for '%s': %s", var, value);
 324 }
 325
 326 static int init_object_disambiguation(const char *name, int len,
 327                                       struct disambiguate_state *ds)
 328 {
 329         int i;
 330
 331         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 332                 return -1;
 333
 334         memset(ds, 0, sizeof(*ds));
 335
 336         for (i = 0; i < len ;i++) {
 337                 unsigned char c = name[i];
 338                 unsigned char val;
 339                 if (c >= '0' && c <= '9')
 340                         val = c - '0';
 341                 else if (c >= 'a' && c <= 'f')
 342                         val = c - 'a' + 10;
 343                 else if (c >= 'A' && c <='F') {
 344                         val = c - 'A' + 10;
 345                         c -= 'A' - 'a';
 346                 }
 347                 else
 348                         return -1;
 349                 ds->hex_pfx[i] = c;
 350                 if (!(i & 1))
 351                         val <<= 4;
 352                 ds->bin_pfx.hash[i >> 1] |= val;
 353         }
 354
 355         ds->len = len;
 356         ds->hex_pfx[len] = '\0';
 357         prepare_alt_odb(the_repository);
 358         return 0;
 359 }
 360
 361 static int show_ambiguous_object(const struct object_id *oid, void *data)
 362 {
 363         const struct disambiguate_state *ds = data;
 364         struct strbuf desc = STRBUF_INIT;
 365         int type;
 366
 367
 368         if (ds->fn && !ds->fn(oid, ds->cb_data))
 369                 return 0;
 370
 371         type = sha1_object_info(oid->hash, NULL);
 372         if (type == OBJ_COMMIT) {
 373                 struct commit *commit = lookup_commit(oid);
 374                 if (commit) {
 375                         struct pretty_print_context pp = {0};
 376                         pp.date_mode.type = DATE_SHORT;
 377                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 378                 }
 379         } else if (type == OBJ_TAG) {
 380                 struct tag *tag = lookup_tag(oid);
 381                 if (!parse_tag(tag) && tag->tag)
 382                         strbuf_addf(&desc, " %s", tag->tag);
 383         }
 384
 385         advise("  %s %s%s",
 386                find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
 387                typename(type) ? typename(type) : "unknown type",
 388                desc.buf);
 389
 390         strbuf_release(&desc);
 391         return 0;
 392 }
 393
 394 static int get_short_oid(const char *name, int len, struct object_id *oid,
 395                           unsigned flags)
 396 {
 397         int status;
 398         struct disambiguate_state ds;
 399         int quietly = !!(flags & GET_OID_QUIETLY);
 400
 401         if (init_object_disambiguation(name, len, &ds) < 0)
 402                 return -1;
 403
 404         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 405                 die("BUG: multiple get_short_oid disambiguator flags");
 406
 407         if (flags & GET_OID_COMMIT)
 408                 ds.fn = disambiguate_commit_only;
 409         else if (flags & GET_OID_COMMITTISH)
 410                 ds.fn = disambiguate_committish_only;
 411         else if (flags & GET_OID_TREE)
 412                 ds.fn = disambiguate_tree_only;
 413         else if (flags & GET_OID_TREEISH)
 414                 ds.fn = disambiguate_treeish_only;
 415         else if (flags & GET_OID_BLOB)
 416                 ds.fn = disambiguate_blob_only;
 417         else
 418                 ds.fn = default_disambiguate_hint;
 419
 420         find_short_object_filename(&ds);
 421         find_short_packed_object(&ds);
 422         status = finish_object_disambiguation(&ds, oid);
 423
 424         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 425                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 426
 427                 /*
 428                  * We may still have ambiguity if we simply saw a series of
 429                  * candidates that did not satisfy our hint function. In
 430                  * that case, we still want to show them, so disable the hint
 431                  * function entirely.
 432                  */
 433                 if (!ds.ambiguous)
 434                         ds.fn = NULL;
 435
 436                 advise(_("The candidates are:"));
 437                 for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
 438         }
 439
 440         return status;
 441 }
 442
 443 static int collect_ambiguous(const struct object_id *oid, void *data)
 444 {
 445         oid_array_append(data, oid);
 446         return 0;
 447 }
 448
 449 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 450 {
 451         struct oid_array collect = OID_ARRAY_INIT;
 452         struct disambiguate_state ds;
 453         int ret;
 454
 455         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 456                 return -1;
 457
 458         ds.always_call_fn = 1;
 459         ds.fn = collect_ambiguous;
 460         ds.cb_data = &collect;
 461         find_short_object_filename(&ds);
 462         find_short_packed_object(&ds);
 463
 464         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 465         oid_array_clear(&collect);
 466         return ret;
 467 }
 468
 469 /*
 470  * Return the slot of the most-significant bit set in "val". There are various
 471  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 472  * probably not a big deal here.
 473  */
 474 static unsigned msb(unsigned long val)
 475 {
 476         unsigned r = 0;
 477         while (val >>= 1)
 478                 r++;
 479         return r;
 480 }
 481
 482 struct min_abbrev_data {
 483         unsigned int init_len;
 484         unsigned int cur_len;
 485         char *hex;
 486         const unsigned char *hash;
 487 };
 488
 489 static inline char get_hex_char_from_oid(const struct object_id *oid,
 490                                          unsigned int pos)
 491 {
 492         static const char hex[] = "0123456789abcdef";
 493
 494         if ((pos & 1) == 0)
 495                 return hex[oid->hash[pos >> 1] >> 4];
 496         else
 497                 return hex[oid->hash[pos >> 1] & 0xf];
 498 }
 499
 500 static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
 501 {
 502         struct min_abbrev_data *mad = cb_data;
 503
 504         unsigned int i = mad->init_len;
 505         while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
 506                 i++;
 507
 508         if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
 509                 mad->cur_len = i + 1;
 510
 511         return 0;
 512 }
 513
 514 static void find_abbrev_len_for_pack(struct packed_git *p,
 515                                      struct min_abbrev_data *mad)
 516 {
 517         int match = 0;
 518         uint32_t num, last, first = 0;
 519         struct object_id oid;
 520
 521         if (open_pack_index(p) || !p->num_objects)
 522                 return;
 523
 524         num = p->num_objects;
 525         last = num;
 526         while (first < last) {
 527                 uint32_t mid = first + (last - first) / 2;
 528                 const unsigned char *current;
 529                 int cmp;
 530
 531                 current = nth_packed_object_sha1(p, mid);
 532                 cmp = hashcmp(mad->hash, current);
 533                 if (!cmp) {
 534                         match = 1;
 535                         first = mid;
 536                         break;
 537                 }
 538                 if (cmp > 0) {
 539                         first = mid + 1;
 540                         continue;
 541                 }
 542                 last = mid;
 543         }
 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 three objects
 549          * nearby for the abbreviation length.
 550          */
 551         mad->init_len = 0;
 552         if (!match) {
 553                 nth_packed_object_oid(&oid, p, first);
 554                 extend_abbrev_len(&oid, mad);
 555         } else if (first < num - 1) {
 556                 nth_packed_object_oid(&oid, p, first + 1);
 557                 extend_abbrev_len(&oid, mad);
 558         }
 559         if (first > 0) {
 560                 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         prepare_packed_git(the_repository);
 571         for (p = get_packed_git(the_repository); p; p = p->next)
 572                 find_abbrev_len_for_pack(p, mad);
 573 }
 574
 575 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 576 {
 577         struct disambiguate_state ds;
 578         struct min_abbrev_data mad;
 579         struct object_id oid_ret;
 580         if (len < 0) {
 581                 unsigned long count = approximate_object_count();
 582                 /*
 583                  * Add one because the MSB only tells us the highest bit set,
 584                  * not including the value of all the _other_ bits (so "15"
 585                  * is only one off of 2^4, but the MSB is the 3rd bit.
 586                  */
 587                 len = msb(count) + 1;
 588                 /*
 589                  * We now know we have on the order of 2^len objects, which
 590                  * expects a collision at 2^(len/2). But we also care about hex
 591                  * chars, not bits, and there are 4 bits per hex. So all
 592                  * together we need to divide by 2 and round up.
 593                  */
 594                 len = DIV_ROUND_UP(len, 2);
 595                 /*
 596                  * For very small repos, we stick with our regular fallback.
 597                  */
 598                 if (len < FALLBACK_DEFAULT_ABBREV)
 599                         len = FALLBACK_DEFAULT_ABBREV;
 600         }
 601
 602         sha1_to_hex_r(hex, sha1);
 603         if (len == GIT_SHA1_HEXSZ || !len)
 604                 return GIT_SHA1_HEXSZ;
 605
 606         mad.init_len = len;
 607         mad.cur_len = len;
 608         mad.hex = hex;
 609         mad.hash = sha1;
 610
 611         find_abbrev_len_packed(&mad);
 612
 613         if (init_object_disambiguation(hex, mad.cur_len, &ds) < 0)
 614                 return -1;
 615
 616         ds.fn = extend_abbrev_len;
 617         ds.always_call_fn = 1;
 618         ds.cb_data = (void *)&mad;
 619
 620         find_short_object_filename(&ds);
 621         (void)finish_object_disambiguation(&ds, &oid_ret);
 622
 623         hex[mad.cur_len] = 0;
 624         return mad.cur_len;
 625 }
 626
 627 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 628 {
 629         static int bufno;
 630         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 631         char *hex = hexbuffer[bufno];
 632         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 633         find_unique_abbrev_r(hex, sha1, len);
 634         return hex;
 635 }
 636
 637 static int ambiguous_path(const char *path, int len)
 638 {
 639         int slash = 1;
 640         int cnt;
 641
 642         for (cnt = 0; cnt < len; cnt++) {
 643                 switch (*path++) {
 644                 case '\0':
 645                         break;
 646                 case '/':
 647                         if (slash)
 648                                 break;
 649                         slash = 1;
 650                         continue;
 651                 case '.':
 652                         continue;
 653                 default:
 654                         slash = 0;
 655                         continue;
 656                 }
 657                 break;
 658         }
 659         return slash;
 660 }
 661
 662 static inline int at_mark(const char *string, int len,
 663                           const char **suffix, int nr)
 664 {
 665         int i;
 666
 667         for (i = 0; i < nr; i++) {
 668                 int suffix_len = strlen(suffix[i]);
 669                 if (suffix_len <= len
 670                     && !strncasecmp(string, suffix[i], suffix_len))
 671                         return suffix_len;
 672         }
 673         return 0;
 674 }
 675
 676 static inline int upstream_mark(const char *string, int len)
 677 {
 678         const char *suffix[] = { "@{upstream}", "@{u}" };
 679         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 680 }
 681
 682 static inline int push_mark(const char *string, int len)
 683 {
 684         const char *suffix[] = { "@{push}" };
 685         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 686 }
 687
 688 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 689 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 690
 691 static int get_oid_basic(const char *str, int len, struct object_id *oid,
 692                           unsigned int flags)
 693 {
 694         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 695         static const char *object_name_msg = N_(
 696         "Git normally never creates a ref that ends with 40 hex characters\n"
 697         "because it will be ignored when you just specify 40-hex. These refs\n"
 698         "may be created by mistake. For example,\n"
 699         "\n"
 700         "  git checkout -b $br $(git rev-parse ...)\n"
 701         "\n"
 702         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 703         "examine these refs and maybe delete them. Turn this message off by\n"
 704         "running \"git config advice.objectNameWarning false\"");
 705         struct object_id tmp_oid;
 706         char *real_ref = NULL;
 707         int refs_found = 0;
 708         int at, reflog_len, nth_prior = 0;
 709
 710         if (len == GIT_SHA1_HEXSZ && !get_oid_hex(str, oid)) {
 711                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 712                         refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
 713                         if (refs_found > 0) {
 714                                 warning(warn_msg, len, str);
 715                                 if (advice_object_name_warning)
 716                                         fprintf(stderr, "%s\n", _(object_name_msg));
 717                         }
 718                         free(real_ref);
 719                 }
 720                 return 0;
 721         }
 722
 723         /* basic@{time or number or -number} format to query ref-log */
 724         reflog_len = at = 0;
 725         if (len && str[len-1] == '}') {
 726                 for (at = len-4; at >= 0; at--) {
 727                         if (str[at] == '@' && str[at+1] == '{') {
 728                                 if (str[at+2] == '-') {
 729                                         if (at != 0)
 730                                                 /* @{-N} not at start */
 731                                                 return -1;
 732                                         nth_prior = 1;
 733                                         continue;
 734                                 }
 735                                 if (!upstream_mark(str + at, len - at) &&
 736                                     !push_mark(str + at, len - at)) {
 737                                         reflog_len = (len-1) - (at+2);
 738                                         len = at;
 739                                 }
 740                                 break;
 741                         }
 742                 }
 743         }
 744
 745         /* Accept only unambiguous ref paths. */
 746         if (len && ambiguous_path(str, len))
 747                 return -1;
 748
 749         if (nth_prior) {
 750                 struct strbuf buf = STRBUF_INIT;
 751                 int detached;
 752
 753                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 754                         detached = (buf.len == GIT_SHA1_HEXSZ && !get_oid_hex(buf.buf, oid));
 755                         strbuf_release(&buf);
 756                         if (detached)
 757                                 return 0;
 758                 }
 759         }
 760
 761         if (!len && reflog_len)
 762                 /* allow "@{...}" to mean the current branch reflog */
 763                 refs_found = dwim_ref("HEAD", 4, oid, &real_ref);
 764         else if (reflog_len)
 765                 refs_found = dwim_log(str, len, oid, &real_ref);
 766         else
 767                 refs_found = dwim_ref(str, len, oid, &real_ref);
 768
 769         if (!refs_found)
 770                 return -1;
 771
 772         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 773             (refs_found > 1 ||
 774              !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
 775                 warning(warn_msg, len, str);
 776
 777         if (reflog_len) {
 778                 int nth, i;
 779                 timestamp_t at_time;
 780                 timestamp_t co_time;
 781                 int co_tz, co_cnt;
 782
 783                 /* Is it asking for N-th entry, or approxidate? */
 784                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 785                         char ch = str[at+2+i];
 786                         if ('0' <= ch && ch <= '9')
 787                                 nth = nth * 10 + ch - '0';
 788                         else
 789                                 nth = -1;
 790                 }
 791                 if (100000000 <= nth) {
 792                         at_time = nth;
 793                         nth = -1;
 794                 } else if (0 <= nth)
 795                         at_time = 0;
 796                 else {
 797                         int errors = 0;
 798                         char *tmp = xstrndup(str + at + 2, reflog_len);
 799                         at_time = approxidate_careful(tmp, &errors);
 800                         free(tmp);
 801                         if (errors) {
 802                                 free(real_ref);
 803                                 return -1;
 804                         }
 805                 }
 806                 if (read_ref_at(real_ref, flags, at_time, nth, oid, NULL,
 807                                 &co_time, &co_tz, &co_cnt)) {
 808                         if (!len) {
 809                                 if (starts_with(real_ref, "refs/heads/")) {
 810                                         str = real_ref + 11;
 811                                         len = strlen(real_ref + 11);
 812                                 } else {
 813                                         /* detached HEAD */
 814                                         str = "HEAD";
 815                                         len = 4;
 816                                 }
 817                         }
 818                         if (at_time) {
 819                                 if (!(flags & GET_OID_QUIETLY)) {
 820                                         warning("Log for '%.*s' only goes "
 821                                                 "back to %s.", len, str,
 822                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 823                                 }
 824                         } else {
 825                                 if (flags & GET_OID_QUIETLY) {
 826                                         exit(128);
 827                                 }
 828                                 die("Log for '%.*s' only has %d entries.",
 829                                     len, str, co_cnt);
 830                         }
 831                 }
 832         }
 833
 834         free(real_ref);
 835         return 0;
 836 }
 837
 838 static int get_parent(const char *name, int len,
 839                       struct object_id *result, int idx)
 840 {
 841         struct object_id oid;
 842         int ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 843         struct commit *commit;
 844         struct commit_list *p;
 845
 846         if (ret)
 847                 return ret;
 848         commit = lookup_commit_reference(&oid);
 849         if (parse_commit(commit))
 850                 return -1;
 851         if (!idx) {
 852                 oidcpy(result, &commit->object.oid);
 853                 return 0;
 854         }
 855         p = commit->parents;
 856         while (p) {
 857                 if (!--idx) {
 858                         oidcpy(result, &p->item->object.oid);
 859                         return 0;
 860                 }
 861                 p = p->next;
 862         }
 863         return -1;
 864 }
 865
 866 static int get_nth_ancestor(const char *name, int len,
 867                             struct object_id *result, int generation)
 868 {
 869         struct object_id oid;
 870         struct commit *commit;
 871         int ret;
 872
 873         ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 874         if (ret)
 875                 return ret;
 876         commit = lookup_commit_reference(&oid);
 877         if (!commit)
 878                 return -1;
 879
 880         while (generation--) {
 881                 if (parse_commit(commit) || !commit->parents)
 882                         return -1;
 883                 commit = commit->parents->item;
 884         }
 885         oidcpy(result, &commit->object.oid);
 886         return 0;
 887 }
 888
 889 struct object *peel_to_type(const char *name, int namelen,
 890                             struct object *o, enum object_type expected_type)
 891 {
 892         if (name && !namelen)
 893                 namelen = strlen(name);
 894         while (1) {
 895                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 896                         return NULL;
 897                 if (expected_type == OBJ_ANY || o->type == expected_type)
 898                         return o;
 899                 if (o->type == OBJ_TAG)
 900                         o = ((struct tag*) o)->tagged;
 901                 else if (o->type == OBJ_COMMIT)
 902                         o = &(((struct commit *) o)->tree->object);
 903                 else {
 904                         if (name)
 905                                 error("%.*s: expected %s type, but the object "
 906                                       "dereferences to %s type",
 907                                       namelen, name, typename(expected_type),
 908                                       typename(o->type));
 909                         return NULL;
 910                 }
 911         }
 912 }
 913
 914 static int peel_onion(const char *name, int len, struct object_id *oid,
 915                       unsigned lookup_flags)
 916 {
 917         struct object_id outer;
 918         const char *sp;
 919         unsigned int expected_type = 0;
 920         struct object *o;
 921
 922         /*
 923          * "ref^{type}" dereferences ref repeatedly until you cannot
 924          * dereference anymore, or you get an object of given type,
 925          * whichever comes first.  "ref^{}" means just dereference
 926          * tags until you get a non-tag.  "ref^0" is a shorthand for
 927          * "ref^{commit}".  "commit^{tree}" could be used to find the
 928          * top-level tree of the given commit.
 929          */
 930         if (len < 4 || name[len-1] != '}')
 931                 return -1;
 932
 933         for (sp = name + len - 1; name <= sp; sp--) {
 934                 int ch = *sp;
 935                 if (ch == '{' && name < sp && sp[-1] == '^')
 936                         break;
 937         }
 938         if (sp <= name)
 939                 return -1;
 940
 941         sp++; /* beginning of type name, or closing brace for empty */
 942         if (starts_with(sp, "commit}"))
 943                 expected_type = OBJ_COMMIT;
 944         else if (starts_with(sp, "tag}"))
 945                 expected_type = OBJ_TAG;
 946         else if (starts_with(sp, "tree}"))
 947                 expected_type = OBJ_TREE;
 948         else if (starts_with(sp, "blob}"))
 949                 expected_type = OBJ_BLOB;
 950         else if (starts_with(sp, "object}"))
 951                 expected_type = OBJ_ANY;
 952         else if (sp[0] == '}')
 953                 expected_type = OBJ_NONE;
 954         else if (sp[0] == '/')
 955                 expected_type = OBJ_COMMIT;
 956         else
 957                 return -1;
 958
 959         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
 960         if (expected_type == OBJ_COMMIT)
 961                 lookup_flags |= GET_OID_COMMITTISH;
 962         else if (expected_type == OBJ_TREE)
 963                 lookup_flags |= GET_OID_TREEISH;
 964
 965         if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
 966                 return -1;
 967
 968         o = parse_object(&outer);
 969         if (!o)
 970                 return -1;
 971         if (!expected_type) {
 972                 o = deref_tag(o, name, sp - name - 2);
 973                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 974                         return -1;
 975                 oidcpy(oid, &o->oid);
 976                 return 0;
 977         }
 978
 979         /*
 980          * At this point, the syntax look correct, so
 981          * if we do not get the needed object, we should
 982          * barf.
 983          */
 984         o = peel_to_type(name, len, o, expected_type);
 985         if (!o)
 986                 return -1;
 987
 988         oidcpy(oid, &o->oid);
 989         if (sp[0] == '/') {
 990                 /* "$commit^{/foo}" */
 991                 char *prefix;
 992                 int ret;
 993                 struct commit_list *list = NULL;
 994
 995                 /*
 996                  * $commit^{/}. Some regex implementation may reject.
 997                  * We don't need regex anyway. '' pattern always matches.
 998                  */
 999                 if (sp[1] == '}')
1000                         return 0;
1001
1002                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1003                 commit_list_insert((struct commit *)o, &list);
1004                 ret = get_oid_oneline(prefix, oid, list);
1005                 free(prefix);
1006                 return ret;
1007         }
1008         return 0;
1009 }
1010
1011 static int get_describe_name(const char *name, int len, struct object_id *oid)
1012 {
1013         const char *cp;
1014         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1015
1016         for (cp = name + len - 1; name + 2 <= cp; cp--) {
1017                 char ch = *cp;
1018                 if (!isxdigit(ch)) {
1019                         /* We must be looking at g in "SOMETHING-g"
1020                          * for it to be describe output.
1021                          */
1022                         if (ch == 'g' && cp[-1] == '-') {
1023                                 cp++;
1024                                 len -= cp - name;
1025                                 return get_short_oid(cp, len, oid, flags);
1026                         }
1027                 }
1028         }
1029         return -1;
1030 }
1031
1032 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags)
1033 {
1034         int ret, has_suffix;
1035         const char *cp;
1036
1037         /*
1038          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1039          */
1040         has_suffix = 0;
1041         for (cp = name + len - 1; name <= cp; cp--) {
1042                 int ch = *cp;
1043                 if ('0' <= ch && ch <= '9')
1044                         continue;
1045                 if (ch == '~' || ch == '^')
1046                         has_suffix = ch;
1047                 break;
1048         }
1049
1050         if (has_suffix) {
1051                 int num = 0;
1052                 int len1 = cp - name;
1053                 cp++;
1054                 while (cp < name + len)
1055                         num = num * 10 + *cp++ - '0';
1056                 if (!num && len1 == len - 1)
1057                         num = 1;
1058                 if (has_suffix == '^')
1059                         return get_parent(name, len1, oid, num);
1060                 /* else if (has_suffix == '~') -- goes without saying */
1061                 return get_nth_ancestor(name, len1, oid, num);
1062         }
1063
1064         ret = peel_onion(name, len, oid, lookup_flags);
1065         if (!ret)
1066                 return 0;
1067
1068         ret = get_oid_basic(name, len, oid, lookup_flags);
1069         if (!ret)
1070                 return 0;
1071
1072         /* It could be describe output that is "SOMETHING-gXXXX" */
1073         ret = get_describe_name(name, len, oid);
1074         if (!ret)
1075                 return 0;
1076
1077         return get_short_oid(name, len, oid, lookup_flags);
1078 }
1079
1080 /*
1081  * This interprets names like ':/Initial revision of "git"' by searching
1082  * through history and returning the first commit whose message starts
1083  * the given regular expression.
1084  *
1085  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1086  *
1087  * For a literal '!' character at the beginning of a pattern, you have to repeat
1088  * that, like: ':/!!foo'
1089  *
1090  * For future extension, all other sequences beginning with ':/!' are reserved.
1091  */
1092
1093 /* Remember to update object flag allocation in object.h */
1094 #define ONELINE_SEEN (1u<<20)
1095
1096 static int handle_one_ref(const char *path, const struct object_id *oid,
1097                           int flag, void *cb_data)
1098 {
1099         struct commit_list **list = cb_data;
1100         struct object *object = parse_object(oid);
1101         if (!object)
1102                 return 0;
1103         if (object->type == OBJ_TAG) {
1104                 object = deref_tag(object, path, strlen(path));
1105                 if (!object)
1106                         return 0;
1107         }
1108         if (object->type != OBJ_COMMIT)
1109                 return 0;
1110         commit_list_insert((struct commit *)object, list);
1111         return 0;
1112 }
1113
1114 static int get_oid_oneline(const char *prefix, struct object_id *oid,
1115                             struct commit_list *list)
1116 {
1117         struct commit_list *backup = NULL, *l;
1118         int found = 0;
1119         int negative = 0;
1120         regex_t regex;
1121
1122         if (prefix[0] == '!') {
1123                 prefix++;
1124
1125                 if (prefix[0] == '-') {
1126                         prefix++;
1127                         negative = 1;
1128                 } else if (prefix[0] != '!') {
1129                         return -1;
1130                 }
1131         }
1132
1133         if (regcomp(&regex, prefix, REG_EXTENDED))
1134                 return -1;
1135
1136         for (l = list; l; l = l->next) {
1137                 l->item->object.flags |= ONELINE_SEEN;
1138                 commit_list_insert(l->item, &backup);
1139         }
1140         while (list) {
1141                 const char *p, *buf;
1142                 struct commit *commit;
1143                 int matches;
1144
1145                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1146                 if (!parse_object(&commit->object.oid))
1147                         continue;
1148                 buf = get_commit_buffer(commit, NULL);
1149                 p = strstr(buf, "\n\n");
1150                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1151                 unuse_commit_buffer(commit, buf);
1152
1153                 if (matches) {
1154                         oidcpy(oid, &commit->object.oid);
1155                         found = 1;
1156                         break;
1157                 }
1158         }
1159         regfree(&regex);
1160         free_commit_list(list);
1161         for (l = backup; l; l = l->next)
1162                 clear_commit_marks(l->item, ONELINE_SEEN);
1163         free_commit_list(backup);
1164         return found ? 0 : -1;
1165 }
1166
1167 struct grab_nth_branch_switch_cbdata {
1168         int remaining;
1169         struct strbuf buf;
1170 };
1171
1172 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1173                                   const char *email, timestamp_t timestamp, int tz,
1174                                   const char *message, void *cb_data)
1175 {
1176         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1177         const char *match = NULL, *target = NULL;
1178         size_t len;
1179
1180         if (skip_prefix(message, "checkout: moving from ", &match))
1181                 target = strstr(match, " to ");
1182
1183         if (!match || !target)
1184                 return 0;
1185         if (--(cb->remaining) == 0) {
1186                 len = target - match;
1187                 strbuf_reset(&cb->buf);
1188                 strbuf_add(&cb->buf, match, len);
1189                 return 1; /* we are done */
1190         }
1191         return 0;
1192 }
1193
1194 /*
1195  * Parse @{-N} syntax, return the number of characters parsed
1196  * if successful; otherwise signal an error with negative value.
1197  */
1198 static int interpret_nth_prior_checkout(const char *name, int namelen,
1199                                         struct strbuf *buf)
1200 {
1201         long nth;
1202         int retval;
1203         struct grab_nth_branch_switch_cbdata cb;
1204         const char *brace;
1205         char *num_end;
1206
1207         if (namelen < 4)
1208                 return -1;
1209         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1210                 return -1;
1211         brace = memchr(name, '}', namelen);
1212         if (!brace)
1213                 return -1;
1214         nth = strtol(name + 3, &num_end, 10);
1215         if (num_end != brace)
1216                 return -1;
1217         if (nth <= 0)
1218                 return -1;
1219         cb.remaining = nth;
1220         strbuf_init(&cb.buf, 20);
1221
1222         retval = 0;
1223         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1224                 strbuf_reset(buf);
1225                 strbuf_addbuf(buf, &cb.buf);
1226                 retval = brace - name + 1;
1227         }
1228
1229         strbuf_release(&cb.buf);
1230         return retval;
1231 }
1232
1233 int get_oid_mb(const char *name, struct object_id *oid)
1234 {
1235         struct commit *one, *two;
1236         struct commit_list *mbs;
1237         struct object_id oid_tmp;
1238         const char *dots;
1239         int st;
1240
1241         dots = strstr(name, "...");
1242         if (!dots)
1243                 return get_oid(name, oid);
1244         if (dots == name)
1245                 st = get_oid("HEAD", &oid_tmp);
1246         else {
1247                 struct strbuf sb;
1248                 strbuf_init(&sb, dots - name);
1249                 strbuf_add(&sb, name, dots - name);
1250                 st = get_oid_committish(sb.buf, &oid_tmp);
1251                 strbuf_release(&sb);
1252         }
1253         if (st)
1254                 return st;
1255         one = lookup_commit_reference_gently(&oid_tmp, 0);
1256         if (!one)
1257                 return -1;
1258
1259         if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1260                 return -1;
1261         two = lookup_commit_reference_gently(&oid_tmp, 0);
1262         if (!two)
1263                 return -1;
1264         mbs = get_merge_bases(one, two);
1265         if (!mbs || mbs->next)
1266                 st = -1;
1267         else {
1268                 st = 0;
1269                 oidcpy(oid, &mbs->item->object.oid);
1270         }
1271         free_commit_list(mbs);
1272         return st;
1273 }
1274
1275 /* parse @something syntax, when 'something' is not {.*} */
1276 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1277 {
1278         const char *next;
1279
1280         if (len || name[1] == '{')
1281                 return -1;
1282
1283         /* make sure it's a single @, or @@{.*}, not @foo */
1284         next = memchr(name + len + 1, '@', namelen - len - 1);
1285         if (next && next[1] != '{')
1286                 return -1;
1287         if (!next)
1288                 next = name + namelen;
1289         if (next != name + 1)
1290                 return -1;
1291
1292         strbuf_reset(buf);
1293         strbuf_add(buf, "HEAD", 4);
1294         return 1;
1295 }
1296
1297 static int reinterpret(const char *name, int namelen, int len,
1298                        struct strbuf *buf, unsigned allowed)
1299 {
1300         /* we have extra data, which might need further processing */
1301         struct strbuf tmp = STRBUF_INIT;
1302         int used = buf->len;
1303         int ret;
1304
1305         strbuf_add(buf, name + len, namelen - len);
1306         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1307         /* that data was not interpreted, remove our cruft */
1308         if (ret < 0) {
1309                 strbuf_setlen(buf, used);
1310                 return len;
1311         }
1312         strbuf_reset(buf);
1313         strbuf_addbuf(buf, &tmp);
1314         strbuf_release(&tmp);
1315         /* tweak for size of {-N} versus expanded ref name */
1316         return ret - used + len;
1317 }
1318
1319 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1320 {
1321         char *s = shorten_unambiguous_ref(ref, 0);
1322         strbuf_reset(buf);
1323         strbuf_addstr(buf, s);
1324         free(s);
1325 }
1326
1327 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1328 {
1329         if (!allowed)
1330                 return 1;
1331
1332         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1333             starts_with(refname, "refs/heads/"))
1334                 return 1;
1335         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1336             starts_with(refname, "refs/remotes/"))
1337                 return 1;
1338
1339         return 0;
1340 }
1341
1342 static int interpret_branch_mark(const char *name, int namelen,
1343                                  int at, struct strbuf *buf,
1344                                  int (*get_mark)(const char *, int),
1345                                  const char *(*get_data)(struct branch *,
1346                                                          struct strbuf *),
1347                                  unsigned allowed)
1348 {
1349         int len;
1350         struct branch *branch;
1351         struct strbuf err = STRBUF_INIT;
1352         const char *value;
1353
1354         len = get_mark(name + at, namelen - at);
1355         if (!len)
1356                 return -1;
1357
1358         if (memchr(name, ':', at))
1359                 return -1;
1360
1361         if (at) {
1362                 char *name_str = xmemdupz(name, at);
1363                 branch = branch_get(name_str);
1364                 free(name_str);
1365         } else
1366                 branch = branch_get(NULL);
1367
1368         value = get_data(branch, &err);
1369         if (!value)
1370                 die("%s", err.buf);
1371
1372         if (!branch_interpret_allowed(value, allowed))
1373                 return -1;
1374
1375         set_shortened_ref(buf, value);
1376         return len + at;
1377 }
1378
1379 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1380                           unsigned allowed)
1381 {
1382         char *at;
1383         const char *start;
1384         int len;
1385
1386         if (!namelen)
1387                 namelen = strlen(name);
1388
1389         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1390                 len = interpret_nth_prior_checkout(name, namelen, buf);
1391                 if (!len) {
1392                         return len; /* syntax Ok, not enough switches */
1393                 } else if (len > 0) {
1394                         if (len == namelen)
1395                                 return len; /* consumed all */
1396                         else
1397                                 return reinterpret(name, namelen, len, buf, allowed);
1398                 }
1399         }
1400
1401         for (start = name;
1402              (at = memchr(start, '@', namelen - (start - name)));
1403              start = at + 1) {
1404
1405                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1406                         len = interpret_empty_at(name, namelen, at - name, buf);
1407                         if (len > 0)
1408                                 return reinterpret(name, namelen, len, buf,
1409                                                    allowed);
1410                 }
1411
1412                 len = interpret_branch_mark(name, namelen, at - name, buf,
1413                                             upstream_mark, branch_get_upstream,
1414                                             allowed);
1415                 if (len > 0)
1416                         return len;
1417
1418                 len = interpret_branch_mark(name, namelen, at - name, buf,
1419                                             push_mark, branch_get_push,
1420                                             allowed);
1421                 if (len > 0)
1422                         return len;
1423         }
1424
1425         return -1;
1426 }
1427
1428 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1429 {
1430         int len = strlen(name);
1431         int used = interpret_branch_name(name, len, sb, allowed);
1432
1433         if (used < 0)
1434                 used = 0;
1435         strbuf_add(sb, name + used, len - used);
1436 }
1437
1438 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1439 {
1440         if (startup_info->have_repository)
1441                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1442         else
1443                 strbuf_addstr(sb, name);
1444
1445         /*
1446          * This splice must be done even if we end up rejecting the
1447          * name; builtin/branch.c::copy_or_rename_branch() still wants
1448          * to see what the name expanded to so that "branch -m" can be
1449          * used as a tool to correct earlier mistakes.
1450          */
1451         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1452
1453         if (*name == '-' ||
1454             !strcmp(sb->buf, "refs/heads/HEAD"))
1455                 return -1;
1456
1457         return check_refname_format(sb->buf, 0);
1458 }
1459
1460 /*
1461  * This is like "get_oid_basic()", except it allows "object ID expressions",
1462  * notably "xyz^" for "parent of xyz"
1463  */
1464 int get_oid(const char *name, struct object_id *oid)
1465 {
1466         struct object_context unused;
1467         return get_oid_with_context(name, 0, oid, &unused);
1468 }
1469
1470
1471 /*
1472  * Many callers know that the user meant to name a commit-ish by
1473  * syntactical positions where the object name appears.  Calling this
1474  * function allows the machinery to disambiguate shorter-than-unique
1475  * abbreviated object names between commit-ish and others.
1476  *
1477  * Note that this does NOT error out when the named object is not a
1478  * commit-ish. It is merely to give a hint to the disambiguation
1479  * machinery.
1480  */
1481 int get_oid_committish(const char *name, struct object_id *oid)
1482 {
1483         struct object_context unused;
1484         return get_oid_with_context(name, GET_OID_COMMITTISH,
1485                                     oid, &unused);
1486 }
1487
1488 int get_oid_treeish(const char *name, struct object_id *oid)
1489 {
1490         struct object_context unused;
1491         return get_oid_with_context(name, GET_OID_TREEISH,
1492                                     oid, &unused);
1493 }
1494
1495 int get_oid_commit(const char *name, struct object_id *oid)
1496 {
1497         struct object_context unused;
1498         return get_oid_with_context(name, GET_OID_COMMIT,
1499                                     oid, &unused);
1500 }
1501
1502 int get_oid_tree(const char *name, struct object_id *oid)
1503 {
1504         struct object_context unused;
1505         return get_oid_with_context(name, GET_OID_TREE,
1506                                     oid, &unused);
1507 }
1508
1509 int get_oid_blob(const char *name, struct object_id *oid)
1510 {
1511         struct object_context unused;
1512         return get_oid_with_context(name, GET_OID_BLOB,
1513                                     oid, &unused);
1514 }
1515
1516 /* Must be called only when object_name:filename doesn't exist. */
1517 static void diagnose_invalid_oid_path(const char *prefix,
1518                                       const char *filename,
1519                                       const struct object_id *tree_oid,
1520                                       const char *object_name,
1521                                       int object_name_len)
1522 {
1523         struct object_id oid;
1524         unsigned mode;
1525
1526         if (!prefix)
1527                 prefix = "";
1528
1529         if (file_exists(filename))
1530                 die("Path '%s' exists on disk, but not in '%.*s'.",
1531                     filename, object_name_len, object_name);
1532         if (is_missing_file_error(errno)) {
1533                 char *fullname = xstrfmt("%s%s", prefix, filename);
1534
1535                 if (!get_tree_entry(tree_oid->hash, fullname,
1536                                     oid.hash, &mode)) {
1537                         die("Path '%s' exists, but not '%s'.\n"
1538                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1539                             fullname,
1540                             filename,
1541                             object_name_len, object_name,
1542                             fullname,
1543                             object_name_len, object_name,
1544                             filename);
1545                 }
1546                 die("Path '%s' does not exist in '%.*s'",
1547                     filename, object_name_len, object_name);
1548         }
1549 }
1550
1551 /* Must be called only when :stage:filename doesn't exist. */
1552 static void diagnose_invalid_index_path(int stage,
1553                                         const char *prefix,
1554                                         const char *filename)
1555 {
1556         const struct cache_entry *ce;
1557         int pos;
1558         unsigned namelen = strlen(filename);
1559         struct strbuf fullname = STRBUF_INIT;
1560
1561         if (!prefix)
1562                 prefix = "";
1563
1564         /* Wrong stage number? */
1565         pos = cache_name_pos(filename, namelen);
1566         if (pos < 0)
1567                 pos = -pos - 1;
1568         if (pos < active_nr) {
1569                 ce = active_cache[pos];
1570                 if (ce_namelen(ce) == namelen &&
1571                     !memcmp(ce->name, filename, namelen))
1572                         die("Path '%s' is in the index, but not at stage %d.\n"
1573                             "Did you mean ':%d:%s'?",
1574                             filename, stage,
1575                             ce_stage(ce), filename);
1576         }
1577
1578         /* Confusion between relative and absolute filenames? */
1579         strbuf_addstr(&fullname, prefix);
1580         strbuf_addstr(&fullname, filename);
1581         pos = cache_name_pos(fullname.buf, fullname.len);
1582         if (pos < 0)
1583                 pos = -pos - 1;
1584         if (pos < active_nr) {
1585                 ce = active_cache[pos];
1586                 if (ce_namelen(ce) == fullname.len &&
1587                     !memcmp(ce->name, fullname.buf, fullname.len))
1588                         die("Path '%s' is in the index, but not '%s'.\n"
1589                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1590                             fullname.buf, filename,
1591                             ce_stage(ce), fullname.buf,
1592                             ce_stage(ce), filename);
1593         }
1594
1595         if (file_exists(filename))
1596                 die("Path '%s' exists on disk, but not in the index.", filename);
1597         if (is_missing_file_error(errno))
1598                 die("Path '%s' does not exist (neither on disk nor in the index).",
1599                     filename);
1600
1601         strbuf_release(&fullname);
1602 }
1603
1604
1605 static char *resolve_relative_path(const char *rel)
1606 {
1607         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1608                 return NULL;
1609
1610         if (!is_inside_work_tree())
1611                 die("relative path syntax can't be used outside working tree.");
1612
1613         /* die() inside prefix_path() if resolved path is outside worktree */
1614         return prefix_path(startup_info->prefix,
1615                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1616                            rel);
1617 }
1618
1619 static int get_oid_with_context_1(const char *name,
1620                                   unsigned flags,
1621                                   const char *prefix,
1622                                   struct object_id *oid,
1623                                   struct object_context *oc)
1624 {
1625         int ret, bracket_depth;
1626         int namelen = strlen(name);
1627         const char *cp;
1628         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1629
1630         if (only_to_die)
1631                 flags |= GET_OID_QUIETLY;
1632
1633         memset(oc, 0, sizeof(*oc));
1634         oc->mode = S_IFINVALID;
1635         strbuf_init(&oc->symlink_path, 0);
1636         ret = get_oid_1(name, namelen, oid, flags);
1637         if (!ret)
1638                 return ret;
1639         /*
1640          * sha1:path --> object name of path in ent sha1
1641          * :path -> object name of absolute path in index
1642          * :./path -> object name of path relative to cwd in index
1643          * :[0-3]:path -> object name of path in index at stage
1644          * :/foo -> recent commit matching foo
1645          */
1646         if (name[0] == ':') {
1647                 int stage = 0;
1648                 const struct cache_entry *ce;
1649                 char *new_path = NULL;
1650                 int pos;
1651                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1652                         struct commit_list *list = NULL;
1653
1654                         for_each_ref(handle_one_ref, &list);
1655                         commit_list_sort_by_date(&list);
1656                         return get_oid_oneline(name + 2, oid, list);
1657                 }
1658                 if (namelen < 3 ||
1659                     name[2] != ':' ||
1660                     name[1] < '0' || '3' < name[1])
1661                         cp = name + 1;
1662                 else {
1663                         stage = name[1] - '0';
1664                         cp = name + 3;
1665                 }
1666                 new_path = resolve_relative_path(cp);
1667                 if (!new_path) {
1668                         namelen = namelen - (cp - name);
1669                 } else {
1670                         cp = new_path;
1671                         namelen = strlen(cp);
1672                 }
1673
1674                 if (flags & GET_OID_RECORD_PATH)
1675                         oc->path = xstrdup(cp);
1676
1677                 if (!active_cache)
1678                         read_cache();
1679                 pos = cache_name_pos(cp, namelen);
1680                 if (pos < 0)
1681                         pos = -pos - 1;
1682                 while (pos < active_nr) {
1683                         ce = active_cache[pos];
1684                         if (ce_namelen(ce) != namelen ||
1685                             memcmp(ce->name, cp, namelen))
1686                                 break;
1687                         if (ce_stage(ce) == stage) {
1688                                 oidcpy(oid, &ce->oid);
1689                                 oc->mode = ce->ce_mode;
1690                                 free(new_path);
1691                                 return 0;
1692                         }
1693                         pos++;
1694                 }
1695                 if (only_to_die && name[1] && name[1] != '/')
1696                         diagnose_invalid_index_path(stage, prefix, cp);
1697                 free(new_path);
1698                 return -1;
1699         }
1700         for (cp = name, bracket_depth = 0; *cp; cp++) {
1701                 if (*cp == '{')
1702                         bracket_depth++;
1703                 else if (bracket_depth && *cp == '}')
1704                         bracket_depth--;
1705                 else if (!bracket_depth && *cp == ':')
1706                         break;
1707         }
1708         if (*cp == ':') {
1709                 struct object_id tree_oid;
1710                 int len = cp - name;
1711                 unsigned sub_flags = flags;
1712
1713                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1714                 sub_flags |= GET_OID_TREEISH;
1715
1716                 if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1717                         const char *filename = cp+1;
1718                         char *new_filename = NULL;
1719
1720                         new_filename = resolve_relative_path(filename);
1721                         if (new_filename)
1722                                 filename = new_filename;
1723                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1724                                 ret = get_tree_entry_follow_symlinks(tree_oid.hash,
1725                                         filename, oid->hash, &oc->symlink_path,
1726                                         &oc->mode);
1727                         } else {
1728                                 ret = get_tree_entry(tree_oid.hash, filename,
1729                                                      oid->hash, &oc->mode);
1730                                 if (ret && only_to_die) {
1731                                         diagnose_invalid_oid_path(prefix,
1732                                                                    filename,
1733                                                                    &tree_oid,
1734                                                                    name, len);
1735                                 }
1736                         }
1737                         hashcpy(oc->tree, tree_oid.hash);
1738                         if (flags & GET_OID_RECORD_PATH)
1739                                 oc->path = xstrdup(filename);
1740
1741                         free(new_filename);
1742                         return ret;
1743                 } else {
1744                         if (only_to_die)
1745                                 die("Invalid object name '%.*s'.", len, name);
1746                 }
1747         }
1748         return ret;
1749 }
1750
1751 /*
1752  * Call this function when you know "name" given by the end user must
1753  * name an object but it doesn't; the function _may_ die with a better
1754  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1755  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1756  * you have a chance to diagnose the error further.
1757  */
1758 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1759 {
1760         struct object_context oc;
1761         struct object_id oid;
1762         get_oid_with_context_1(name, GET_OID_ONLY_TO_DIE, prefix, &oid, &oc);
1763 }
1764
1765 int get_oid_with_context(const char *str, unsigned flags, struct object_id *oid, struct object_context *oc)
1766 {
1767         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1768                 die("BUG: incompatible flags for get_sha1_with_context");
1769         return get_oid_with_context_1(str, flags, NULL, oid, oc);
1770 }