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