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

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "tag.h"
   4 #include "commit.h"
   5 #include "tree.h"
   6 #include "blob.h"
   7 #include "tree-walk.h"
   8 #include "refs.h"
   9 #include "remote.h"
  10 #include "dir.h"
  11 #include "sha1-array.h"
  12 #include "packfile.h"
  13 #include "object-store.h"
  14 #include "repository.h"
  15 #include "commit-reach.h"
  16
  17 static int get_oid_oneline(const char *, struct object_id *, struct commit_list *);
  18
  19 typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
  20
  21 struct disambiguate_state {
  22         int len; /* length of prefix in hex chars */
  23         char hex_pfx[GIT_MAX_HEXSZ + 1];
  24         struct object_id bin_pfx;
  25
  26         disambiguate_hint_fn fn;
  27         void *cb_data;
  28         struct object_id candidate;
  29         unsigned candidate_exists:1;
  30         unsigned candidate_checked:1;
  31         unsigned candidate_ok:1;
  32         unsigned disambiguate_fn_used:1;
  33         unsigned ambiguous:1;
  34         unsigned always_call_fn:1;
  35 };
  36
  37 static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
  38 {
  39         if (ds->always_call_fn) {
  40                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  41                 return;
  42         }
  43         if (!ds->candidate_exists) {
  44                 /* this is the first candidate */
  45                 oidcpy(&ds->candidate, current);
  46                 ds->candidate_exists = 1;
  47                 return;
  48         } else if (!oidcmp(&ds->candidate, current)) {
  49                 /* the same as what we already have seen */
  50                 return;
  51         }
  52
  53         if (!ds->fn) {
  54                 /* cannot disambiguate between ds->candidate and current */
  55                 ds->ambiguous = 1;
  56                 return;
  57         }
  58
  59         if (!ds->candidate_checked) {
  60                 ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
  61                 ds->disambiguate_fn_used = 1;
  62                 ds->candidate_checked = 1;
  63         }
  64
  65         if (!ds->candidate_ok) {
  66                 /* discard the candidate; we know it does not satisfy fn */
  67                 oidcpy(&ds->candidate, current);
  68                 ds->candidate_checked = 0;
  69                 return;
  70         }
  71
  72         /* if we reach this point, we know ds->candidate satisfies fn */
  73         if (ds->fn(current, ds->cb_data)) {
  74                 /*
  75                  * if both current and candidate satisfy fn, we cannot
  76                  * disambiguate.
  77                  */
  78                 ds->candidate_ok = 0;
  79                 ds->ambiguous = 1;
  80         }
  81
  82         /* otherwise, current can be discarded and candidate is still good */
  83 }
  84
  85 static int append_loose_object(const struct object_id *oid, const char *path,
  86                                void *data)
  87 {
  88         oid_array_append(data, oid);
  89         return 0;
  90 }
  91
  92 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  93
  94 static void find_short_object_filename(struct disambiguate_state *ds)
  95 {
  96         int subdir_nr = ds->bin_pfx.hash[0];
  97         struct alternate_object_database *alt;
  98         static struct alternate_object_database *fakeent;
  99
 100         if (!fakeent) {
 101                 /*
 102                  * Create a "fake" alternate object database that
 103                  * points to our own object database, to make it
 104                  * easier to get a temporary working space in
 105                  * alt->name/alt->base while iterating over the
 106                  * object databases including our own.
 107                  */
 108                 fakeent = alloc_alt_odb(get_object_directory());
 109         }
 110         fakeent->next = the_repository->objects->alt_odb_list;
 111
 112         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 113                 int pos;
 114
 115                 if (!alt->loose_objects_subdir_seen[subdir_nr]) {
 116                         struct strbuf *buf = alt_scratch_buf(alt);
 117                         for_each_file_in_obj_subdir(subdir_nr, buf,
 118                                                     append_loose_object,
 119                                                     NULL, NULL,
 120                                                     &alt->loose_objects_cache);
 121                         alt->loose_objects_subdir_seen[subdir_nr] = 1;
 122                 }
 123
 124                 pos = oid_array_lookup(&alt->loose_objects_cache, &ds->bin_pfx);
 125                 if (pos < 0)
 126                         pos = -1 - pos;
 127                 while (!ds->ambiguous && pos < alt->loose_objects_cache.nr) {
 128                         const struct object_id *oid;
 129                         oid = alt->loose_objects_cache.oid + pos;
 130                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 131                                 break;
 132                         update_candidates(ds, oid);
 133                         pos++;
 134                 }
 135         }
 136 }
 137
 138 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 139 {
 140         do {
 141                 if (*a != *b)
 142                         return 0;
 143                 a++;
 144                 b++;
 145                 len -= 2;
 146         } while (len > 1);
 147         if (len)
 148                 if ((*a ^ *b) & 0xf0)
 149                         return 0;
 150         return 1;
 151 }
 152
 153 static void unique_in_pack(struct packed_git *p,
 154                            struct disambiguate_state *ds)
 155 {
 156         uint32_t num, i, first = 0;
 157         const struct object_id *current = NULL;
 158
 159         if (open_pack_index(p) || !p->num_objects)
 160                 return;
 161
 162         num = p->num_objects;
 163         bsearch_pack(&ds->bin_pfx, p, &first);
 164
 165         /*
 166          * At this point, "first" is the location of the lowest object
 167          * with an object name that could match "bin_pfx".  See if we have
 168          * 0, 1 or more objects that actually match(es).
 169          */
 170         for (i = first; i < num && !ds->ambiguous; i++) {
 171                 struct object_id oid;
 172                 current = nth_packed_object_oid(&oid, p, i);
 173                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 174                         break;
 175                 update_candidates(ds, current);
 176         }
 177 }
 178
 179 static void find_short_packed_object(struct disambiguate_state *ds)
 180 {
 181         struct packed_git *p;
 182
 183         for (p = get_packed_git(the_repository); p && !ds->ambiguous;
 184              p = p->next)
 185                 unique_in_pack(p, ds);
 186 }
 187
 188 #define SHORT_NAME_NOT_FOUND (-1)
 189 #define SHORT_NAME_AMBIGUOUS (-2)
 190
 191 static int finish_object_disambiguation(struct disambiguate_state *ds,
 192                                         struct object_id *oid)
 193 {
 194         if (ds->ambiguous)
 195                 return SHORT_NAME_AMBIGUOUS;
 196
 197         if (!ds->candidate_exists)
 198                 return SHORT_NAME_NOT_FOUND;
 199
 200         if (!ds->candidate_checked)
 201                 /*
 202                  * If this is the only candidate, there is no point
 203                  * calling the disambiguation hint callback.
 204                  *
 205                  * On the other hand, if the current candidate
 206                  * replaced an earlier candidate that did _not_ pass
 207                  * the disambiguation hint callback, then we do have
 208                  * more than one objects that match the short name
 209                  * given, so we should make sure this one matches;
 210                  * otherwise, if we discovered this one and the one
 211                  * that we previously discarded in the reverse order,
 212                  * we would end up showing different results in the
 213                  * same repository!
 214                  */
 215                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 216                                     ds->fn(&ds->candidate, ds->cb_data));
 217
 218         if (!ds->candidate_ok)
 219                 return SHORT_NAME_AMBIGUOUS;
 220
 221         oidcpy(oid, &ds->candidate);
 222         return 0;
 223 }
 224
 225 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 226 {
 227         int kind = oid_object_info(the_repository, oid, NULL);
 228         return kind == OBJ_COMMIT;
 229 }
 230
 231 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 232 {
 233         struct object *obj;
 234         int kind;
 235
 236         kind = oid_object_info(the_repository, oid, NULL);
 237         if (kind == OBJ_COMMIT)
 238                 return 1;
 239         if (kind != OBJ_TAG)
 240                 return 0;
 241
 242         /* We need to do this the hard way... */
 243         obj = deref_tag(the_repository, parse_object(the_repository, oid),
 244                         NULL, 0);
 245         if (obj && obj->type == OBJ_COMMIT)
 246                 return 1;
 247         return 0;
 248 }
 249
 250 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 251 {
 252         int kind = oid_object_info(the_repository, oid, NULL);
 253         return kind == OBJ_TREE;
 254 }
 255
 256 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 257 {
 258         struct object *obj;
 259         int kind;
 260
 261         kind = oid_object_info(the_repository, oid, NULL);
 262         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 263                 return 1;
 264         if (kind != OBJ_TAG)
 265                 return 0;
 266
 267         /* We need to do this the hard way... */
 268         obj = deref_tag(the_repository, parse_object(the_repository, oid),
 269                         NULL, 0);
 270         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 271                 return 1;
 272         return 0;
 273 }
 274
 275 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 276 {
 277         int kind = oid_object_info(the_repository, oid, NULL);
 278         return kind == OBJ_BLOB;
 279 }
 280
 281 static disambiguate_hint_fn default_disambiguate_hint;
 282
 283 int set_disambiguate_hint_config(const char *var, const char *value)
 284 {
 285         static const struct {
 286                 const char *name;
 287                 disambiguate_hint_fn fn;
 288         } hints[] = {
 289                 { "none", NULL },
 290                 { "commit", disambiguate_commit_only },
 291                 { "committish", disambiguate_committish_only },
 292                 { "tree", disambiguate_tree_only },
 293                 { "treeish", disambiguate_treeish_only },
 294                 { "blob", disambiguate_blob_only }
 295         };
 296         int i;
 297
 298         if (!value)
 299                 return config_error_nonbool(var);
 300
 301         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 302                 if (!strcasecmp(value, hints[i].name)) {
 303                         default_disambiguate_hint = hints[i].fn;
 304                         return 0;
 305                 }
 306         }
 307
 308         return error("unknown hint type for '%s': %s", var, value);
 309 }
 310
 311 static int init_object_disambiguation(const char *name, int len,
 312                                       struct disambiguate_state *ds)
 313 {
 314         int i;
 315
 316         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 317                 return -1;
 318
 319         memset(ds, 0, sizeof(*ds));
 320
 321         for (i = 0; i < len ;i++) {
 322                 unsigned char c = name[i];
 323                 unsigned char val;
 324                 if (c >= '0' && c <= '9')
 325                         val = c - '0';
 326                 else if (c >= 'a' && c <= 'f')
 327                         val = c - 'a' + 10;
 328                 else if (c >= 'A' && c <='F') {
 329                         val = c - 'A' + 10;
 330                         c -= 'A' - 'a';
 331                 }
 332                 else
 333                         return -1;
 334                 ds->hex_pfx[i] = c;
 335                 if (!(i & 1))
 336                         val <<= 4;
 337                 ds->bin_pfx.hash[i >> 1] |= val;
 338         }
 339
 340         ds->len = len;
 341         ds->hex_pfx[len] = '\0';
 342         prepare_alt_odb(the_repository);
 343         return 0;
 344 }
 345
 346 static int show_ambiguous_object(const struct object_id *oid, void *data)
 347 {
 348         const struct disambiguate_state *ds = data;
 349         struct strbuf desc = STRBUF_INIT;
 350         int type;
 351
 352         if (ds->fn && !ds->fn(oid, ds->cb_data))
 353                 return 0;
 354
 355         type = oid_object_info(the_repository, oid, NULL);
 356         if (type == OBJ_COMMIT) {
 357                 struct commit *commit = lookup_commit(the_repository, oid);
 358                 if (commit) {
 359                         struct pretty_print_context pp = {0};
 360                         pp.date_mode.type = DATE_SHORT;
 361                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 362                 }
 363         } else if (type == OBJ_TAG) {
 364                 struct tag *tag = lookup_tag(the_repository, oid);
 365                 if (!parse_tag(tag) && tag->tag)
 366                         strbuf_addf(&desc, " %s", tag->tag);
 367         }
 368
 369         advise("  %s %s%s",
 370                find_unique_abbrev(oid, DEFAULT_ABBREV),
 371                type_name(type) ? type_name(type) : "unknown type",
 372                desc.buf);
 373
 374         strbuf_release(&desc);
 375         return 0;
 376 }
 377
 378 static int collect_ambiguous(const struct object_id *oid, void *data)
 379 {
 380         oid_array_append(data, oid);
 381         return 0;
 382 }
 383
 384 static int sort_ambiguous(const void *a, const void *b)
 385 {
 386         int a_type = oid_object_info(the_repository, a, NULL);
 387         int b_type = oid_object_info(the_repository, b, NULL);
 388         int a_type_sort;
 389         int b_type_sort;
 390
 391         /*
 392          * Sorts by hash within the same object type, just as
 393          * oid_array_for_each_unique() would do.
 394          */
 395         if (a_type == b_type)
 396                 return oidcmp(a, b);
 397
 398         /*
 399          * Between object types show tags, then commits, and finally
 400          * trees and blobs.
 401          *
 402          * The object_type enum is commit, tree, blob, tag, but we
 403          * want tag, commit, tree blob. Cleverly (perhaps too
 404          * cleverly) do that with modulus, since the enum assigns 1 to
 405          * commit, so tag becomes 0.
 406          */
 407         a_type_sort = a_type % 4;
 408         b_type_sort = b_type % 4;
 409         return a_type_sort > b_type_sort ? 1 : -1;
 410 }
 411
 412 static int get_short_oid(const char *name, int len, struct object_id *oid,
 413                           unsigned flags)
 414 {
 415         int status;
 416         struct disambiguate_state ds;
 417         int quietly = !!(flags & GET_OID_QUIETLY);
 418
 419         if (init_object_disambiguation(name, len, &ds) < 0)
 420                 return -1;
 421
 422         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 423                 BUG("multiple get_short_oid disambiguator flags");
 424
 425         if (flags & GET_OID_COMMIT)
 426                 ds.fn = disambiguate_commit_only;
 427         else if (flags & GET_OID_COMMITTISH)
 428                 ds.fn = disambiguate_committish_only;
 429         else if (flags & GET_OID_TREE)
 430                 ds.fn = disambiguate_tree_only;
 431         else if (flags & GET_OID_TREEISH)
 432                 ds.fn = disambiguate_treeish_only;
 433         else if (flags & GET_OID_BLOB)
 434                 ds.fn = disambiguate_blob_only;
 435         else
 436                 ds.fn = default_disambiguate_hint;
 437
 438         find_short_object_filename(&ds);
 439         find_short_packed_object(&ds);
 440         status = finish_object_disambiguation(&ds, oid);
 441
 442         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 443                 struct oid_array collect = OID_ARRAY_INIT;
 444
 445                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 446
 447                 /*
 448                  * We may still have ambiguity if we simply saw a series of
 449                  * candidates that did not satisfy our hint function. In
 450                  * that case, we still want to show them, so disable the hint
 451                  * function entirely.
 452                  */
 453                 if (!ds.ambiguous)
 454                         ds.fn = NULL;
 455
 456                 advise(_("The candidates are:"));
 457                 for_each_abbrev(ds.hex_pfx, collect_ambiguous, &collect);
 458                 QSORT(collect.oid, collect.nr, sort_ambiguous);
 459
 460                 if (oid_array_for_each(&collect, show_ambiguous_object, &ds))
 461                         BUG("show_ambiguous_object shouldn't return non-zero");
 462                 oid_array_clear(&collect);
 463         }
 464
 465         return status;
 466 }
 467
 468 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 469 {
 470         struct oid_array collect = OID_ARRAY_INIT;
 471         struct disambiguate_state ds;
 472         int ret;
 473
 474         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 475                 return -1;
 476
 477         ds.always_call_fn = 1;
 478         ds.fn = collect_ambiguous;
 479         ds.cb_data = &collect;
 480         find_short_object_filename(&ds);
 481         find_short_packed_object(&ds);
 482
 483         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 484         oid_array_clear(&collect);
 485         return ret;
 486 }
 487
 488 /*
 489  * Return the slot of the most-significant bit set in "val". There are various
 490  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 491  * probably not a big deal here.
 492  */
 493 static unsigned msb(unsigned long val)
 494 {
 495         unsigned r = 0;
 496         while (val >>= 1)
 497                 r++;
 498         return r;
 499 }
 500
 501 struct min_abbrev_data {
 502         unsigned int init_len;
 503         unsigned int cur_len;
 504         char *hex;
 505         const struct object_id *oid;
 506 };
 507
 508 static inline char get_hex_char_from_oid(const struct object_id *oid,
 509                                          unsigned int pos)
 510 {
 511         static const char hex[] = "0123456789abcdef";
 512
 513         if ((pos & 1) == 0)
 514                 return hex[oid->hash[pos >> 1] >> 4];
 515         else
 516                 return hex[oid->hash[pos >> 1] & 0xf];
 517 }
 518
 519 static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
 520 {
 521         struct min_abbrev_data *mad = cb_data;
 522
 523         unsigned int i = mad->init_len;
 524         while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
 525                 i++;
 526
 527         if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
 528                 mad->cur_len = i + 1;
 529
 530         return 0;
 531 }
 532
 533 static void find_abbrev_len_for_pack(struct packed_git *p,
 534                                      struct min_abbrev_data *mad)
 535 {
 536         int match = 0;
 537         uint32_t num, first = 0;
 538         struct object_id oid;
 539         const struct object_id *mad_oid;
 540
 541         if (open_pack_index(p) || !p->num_objects)
 542                 return;
 543
 544         num = p->num_objects;
 545         mad_oid = mad->oid;
 546         match = bsearch_pack(mad_oid, p, &first);
 547
 548         /*
 549          * first is now the position in the packfile where we would insert
 550          * mad->hash if it does not exist (or the position of mad->hash if
 551          * it does exist). Hence, we consider a maximum of two objects
 552          * nearby for the abbreviation length.
 553          */
 554         mad->init_len = 0;
 555         if (!match) {
 556                 if (nth_packed_object_oid(&oid, p, first))
 557                         extend_abbrev_len(&oid, mad);
 558         } else if (first < num - 1) {
 559                 if (nth_packed_object_oid(&oid, p, first + 1))
 560                         extend_abbrev_len(&oid, mad);
 561         }
 562         if (first > 0) {
 563                 if (nth_packed_object_oid(&oid, p, first - 1))
 564                         extend_abbrev_len(&oid, mad);
 565         }
 566         mad->init_len = mad->cur_len;
 567 }
 568
 569 static void find_abbrev_len_packed(struct min_abbrev_data *mad)
 570 {
 571         struct packed_git *p;
 572
 573         for (p = get_packed_git(the_repository); p; p = p->next)
 574                 find_abbrev_len_for_pack(p, mad);
 575 }
 576
 577 int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 578 {
 579         struct disambiguate_state ds;
 580         struct min_abbrev_data mad;
 581         struct object_id oid_ret;
 582         if (len < 0) {
 583                 unsigned long count = approximate_object_count();
 584                 /*
 585                  * Add one because the MSB only tells us the highest bit set,
 586                  * not including the value of all the _other_ bits (so "15"
 587                  * is only one off of 2^4, but the MSB is the 3rd bit.
 588                  */
 589                 len = msb(count) + 1;
 590                 /*
 591                  * We now know we have on the order of 2^len objects, which
 592                  * expects a collision at 2^(len/2). But we also care about hex
 593                  * chars, not bits, and there are 4 bits per hex. So all
 594                  * together we need to divide by 2 and round up.
 595                  */
 596                 len = DIV_ROUND_UP(len, 2);
 597                 /*
 598                  * For very small repos, we stick with our regular fallback.
 599                  */
 600                 if (len < FALLBACK_DEFAULT_ABBREV)
 601                         len = FALLBACK_DEFAULT_ABBREV;
 602         }
 603
 604         oid_to_hex_r(hex, oid);
 605         if (len == GIT_SHA1_HEXSZ || !len)
 606                 return GIT_SHA1_HEXSZ;
 607
 608         mad.init_len = len;
 609         mad.cur_len = len;
 610         mad.hex = hex;
 611         mad.oid = oid;
 612
 613         find_abbrev_len_packed(&mad);
 614
 615         if (init_object_disambiguation(hex, mad.cur_len, &ds) < 0)
 616                 return -1;
 617
 618         ds.fn = extend_abbrev_len;
 619         ds.always_call_fn = 1;
 620         ds.cb_data = (void *)&mad;
 621
 622         find_short_object_filename(&ds);
 623         (void)finish_object_disambiguation(&ds, &oid_ret);
 624
 625         hex[mad.cur_len] = 0;
 626         return mad.cur_len;
 627 }
 628
 629 const char *find_unique_abbrev(const struct object_id *oid, int len)
 630 {
 631         static int bufno;
 632         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 633         char *hex = hexbuffer[bufno];
 634         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 635         find_unique_abbrev_r(hex, oid, len);
 636         return hex;
 637 }
 638
 639 static int ambiguous_path(const char *path, int len)
 640 {
 641         int slash = 1;
 642         int cnt;
 643
 644         for (cnt = 0; cnt < len; cnt++) {
 645                 switch (*path++) {
 646                 case '\0':
 647                         break;
 648                 case '/':
 649                         if (slash)
 650                                 break;
 651                         slash = 1;
 652                         continue;
 653                 case '.':
 654                         continue;
 655                 default:
 656                         slash = 0;
 657                         continue;
 658                 }
 659                 break;
 660         }
 661         return slash;
 662 }
 663
 664 static inline int at_mark(const char *string, int len,
 665                           const char **suffix, int nr)
 666 {
 667         int i;
 668
 669         for (i = 0; i < nr; i++) {
 670                 int suffix_len = strlen(suffix[i]);
 671                 if (suffix_len <= len
 672                     && !strncasecmp(string, suffix[i], suffix_len))
 673                         return suffix_len;
 674         }
 675         return 0;
 676 }
 677
 678 static inline int upstream_mark(const char *string, int len)
 679 {
 680         const char *suffix[] = { "@{upstream}", "@{u}" };
 681         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 682 }
 683
 684 static inline int push_mark(const char *string, int len)
 685 {
 686         const char *suffix[] = { "@{push}" };
 687         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 688 }
 689
 690 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 691 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 692
 693 static int get_oid_basic(const char *str, int len, struct object_id *oid,
 694                           unsigned int flags)
 695 {
 696         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 697         static const char *object_name_msg = N_(
 698         "Git normally never creates a ref that ends with 40 hex characters\n"
 699         "because it will be ignored when you just specify 40-hex. These refs\n"
 700         "may be created by mistake. For example,\n"
 701         "\n"
 702         "  git checkout -b $br $(git rev-parse ...)\n"
 703         "\n"
 704         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 705         "examine these refs and maybe delete them. Turn this message off by\n"
 706         "running \"git config advice.objectNameWarning false\"");
 707         struct object_id tmp_oid;
 708         char *real_ref = NULL;
 709         int refs_found = 0;
 710         int at, reflog_len, nth_prior = 0;
 711
 712         if (len == GIT_SHA1_HEXSZ && !get_oid_hex(str, oid)) {
 713                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 714                         refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
 715                         if (refs_found > 0) {
 716                                 warning(warn_msg, len, str);
 717                                 if (advice_object_name_warning)
 718                                         fprintf(stderr, "%s\n", _(object_name_msg));
 719                         }
 720                         free(real_ref);
 721                 }
 722                 return 0;
 723         }
 724
 725         /* basic@{time or number or -number} format to query ref-log */
 726         reflog_len = at = 0;
 727         if (len && str[len-1] == '}') {
 728                 for (at = len-4; at >= 0; at--) {
 729                         if (str[at] == '@' && str[at+1] == '{') {
 730                                 if (str[at+2] == '-') {
 731                                         if (at != 0)
 732                                                 /* @{-N} not at start */
 733                                                 return -1;
 734                                         nth_prior = 1;
 735                                         continue;
 736                                 }
 737                                 if (!upstream_mark(str + at, len - at) &&
 738                                     !push_mark(str + at, len - at)) {
 739                                         reflog_len = (len-1) - (at+2);
 740                                         len = at;
 741                                 }
 742                                 break;
 743                         }
 744                 }
 745         }
 746
 747         /* Accept only unambiguous ref paths. */
 748         if (len && ambiguous_path(str, len))
 749                 return -1;
 750
 751         if (nth_prior) {
 752                 struct strbuf buf = STRBUF_INIT;
 753                 int detached;
 754
 755                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 756                         detached = (buf.len == GIT_SHA1_HEXSZ && !get_oid_hex(buf.buf, oid));
 757                         strbuf_release(&buf);
 758                         if (detached)
 759                                 return 0;
 760                 }
 761         }
 762
 763         if (!len && reflog_len)
 764                 /* allow "@{...}" to mean the current branch reflog */
 765                 refs_found = dwim_ref("HEAD", 4, oid, &real_ref);
 766         else if (reflog_len)
 767                 refs_found = dwim_log(str, len, oid, &real_ref);
 768         else
 769                 refs_found = dwim_ref(str, len, oid, &real_ref);
 770
 771         if (!refs_found)
 772                 return -1;
 773
 774         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 775             (refs_found > 1 ||
 776              !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
 777                 warning(warn_msg, len, str);
 778
 779         if (reflog_len) {
 780                 int nth, i;
 781                 timestamp_t at_time;
 782                 timestamp_t co_time;
 783                 int co_tz, co_cnt;
 784
 785                 /* Is it asking for N-th entry, or approxidate? */
 786                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 787                         char ch = str[at+2+i];
 788                         if ('0' <= ch && ch <= '9')
 789                                 nth = nth * 10 + ch - '0';
 790                         else
 791                                 nth = -1;
 792                 }
 793                 if (100000000 <= nth) {
 794                         at_time = nth;
 795                         nth = -1;
 796                 } else if (0 <= nth)
 797                         at_time = 0;
 798                 else {
 799                         int errors = 0;
 800                         char *tmp = xstrndup(str + at + 2, reflog_len);
 801                         at_time = approxidate_careful(tmp, &errors);
 802                         free(tmp);
 803                         if (errors) {
 804                                 free(real_ref);
 805                                 return -1;
 806                         }
 807                 }
 808                 if (read_ref_at(real_ref, flags, at_time, nth, oid, NULL,
 809                                 &co_time, &co_tz, &co_cnt)) {
 810                         if (!len) {
 811                                 if (starts_with(real_ref, "refs/heads/")) {
 812                                         str = real_ref + 11;
 813                                         len = strlen(real_ref + 11);
 814                                 } else {
 815                                         /* detached HEAD */
 816                                         str = "HEAD";
 817                                         len = 4;
 818                                 }
 819                         }
 820                         if (at_time) {
 821                                 if (!(flags & GET_OID_QUIETLY)) {
 822                                         warning("Log for '%.*s' only goes "
 823                                                 "back to %s.", len, str,
 824                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 825                                 }
 826                         } else {
 827                                 if (flags & GET_OID_QUIETLY) {
 828                                         exit(128);
 829                                 }
 830                                 die("Log for '%.*s' only has %d entries.",
 831                                     len, str, co_cnt);
 832                         }
 833                 }
 834         }
 835
 836         free(real_ref);
 837         return 0;
 838 }
 839
 840 static int get_parent(const char *name, int len,
 841                       struct object_id *result, int idx)
 842 {
 843         struct object_id oid;
 844         int ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 845         struct commit *commit;
 846         struct commit_list *p;
 847
 848         if (ret)
 849                 return ret;
 850         commit = lookup_commit_reference(the_repository, &oid);
 851         if (parse_commit(commit))
 852                 return -1;
 853         if (!idx) {
 854                 oidcpy(result, &commit->object.oid);
 855                 return 0;
 856         }
 857         p = commit->parents;
 858         while (p) {
 859                 if (!--idx) {
 860                         oidcpy(result, &p->item->object.oid);
 861                         return 0;
 862                 }
 863                 p = p->next;
 864         }
 865         return -1;
 866 }
 867
 868 static int get_nth_ancestor(const char *name, int len,
 869                             struct object_id *result, int generation)
 870 {
 871         struct object_id oid;
 872         struct commit *commit;
 873         int ret;
 874
 875         ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 876         if (ret)
 877                 return ret;
 878         commit = lookup_commit_reference(the_repository, &oid);
 879         if (!commit)
 880                 return -1;
 881
 882         while (generation--) {
 883                 if (parse_commit(commit) || !commit->parents)
 884                         return -1;
 885                 commit = commit->parents->item;
 886         }
 887         oidcpy(result, &commit->object.oid);
 888         return 0;
 889 }
 890
 891 struct object *peel_to_type(const char *name, int namelen,
 892                             struct object *o, enum object_type expected_type)
 893 {
 894         if (name && !namelen)
 895                 namelen = strlen(name);
 896         while (1) {
 897                 if (!o || (!o->parsed && !parse_object(the_repository, &o->oid)))
 898                         return NULL;
 899                 if (expected_type == OBJ_ANY || o->type == expected_type)
 900                         return o;
 901                 if (o->type == OBJ_TAG)
 902                         o = ((struct tag*) o)->tagged;
 903                 else if (o->type == OBJ_COMMIT)
 904                         o = &(get_commit_tree(((struct commit *)o))->object);
 905                 else {
 906                         if (name)
 907                                 error("%.*s: expected %s type, but the object "
 908                                       "dereferences to %s type",
 909                                       namelen, name, type_name(expected_type),
 910                                       type_name(o->type));
 911                         return NULL;
 912                 }
 913         }
 914 }
 915
 916 static int peel_onion(const char *name, int len, struct object_id *oid,
 917                       unsigned lookup_flags)
 918 {
 919         struct object_id outer;
 920         const char *sp;
 921         unsigned int expected_type = 0;
 922         struct object *o;
 923
 924         /*
 925          * "ref^{type}" dereferences ref repeatedly until you cannot
 926          * dereference anymore, or you get an object of given type,
 927          * whichever comes first.  "ref^{}" means just dereference
 928          * tags until you get a non-tag.  "ref^0" is a shorthand for
 929          * "ref^{commit}".  "commit^{tree}" could be used to find the
 930          * top-level tree of the given commit.
 931          */
 932         if (len < 4 || name[len-1] != '}')
 933                 return -1;
 934
 935         for (sp = name + len - 1; name <= sp; sp--) {
 936                 int ch = *sp;
 937                 if (ch == '{' && name < sp && sp[-1] == '^')
 938                         break;
 939         }
 940         if (sp <= name)
 941                 return -1;
 942
 943         sp++; /* beginning of type name, or closing brace for empty */
 944         if (starts_with(sp, "commit}"))
 945                 expected_type = OBJ_COMMIT;
 946         else if (starts_with(sp, "tag}"))
 947                 expected_type = OBJ_TAG;
 948         else if (starts_with(sp, "tree}"))
 949                 expected_type = OBJ_TREE;
 950         else if (starts_with(sp, "blob}"))
 951                 expected_type = OBJ_BLOB;
 952         else if (starts_with(sp, "object}"))
 953                 expected_type = OBJ_ANY;
 954         else if (sp[0] == '}')
 955                 expected_type = OBJ_NONE;
 956         else if (sp[0] == '/')
 957                 expected_type = OBJ_COMMIT;
 958         else
 959                 return -1;
 960
 961         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
 962         if (expected_type == OBJ_COMMIT)
 963                 lookup_flags |= GET_OID_COMMITTISH;
 964         else if (expected_type == OBJ_TREE)
 965                 lookup_flags |= GET_OID_TREEISH;
 966
 967         if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
 968                 return -1;
 969
 970         o = parse_object(the_repository, &outer);
 971         if (!o)
 972                 return -1;
 973         if (!expected_type) {
 974                 o = deref_tag(the_repository, o, name, sp - name - 2);
 975                 if (!o || (!o->parsed && !parse_object(the_repository, &o->oid)))
 976                         return -1;
 977                 oidcpy(oid, &o->oid);
 978                 return 0;
 979         }
 980
 981         /*
 982          * At this point, the syntax look correct, so
 983          * if we do not get the needed object, we should
 984          * barf.
 985          */
 986         o = peel_to_type(name, len, o, expected_type);
 987         if (!o)
 988                 return -1;
 989
 990         oidcpy(oid, &o->oid);
 991         if (sp[0] == '/') {
 992                 /* "$commit^{/foo}" */
 993                 char *prefix;
 994                 int ret;
 995                 struct commit_list *list = NULL;
 996
 997                 /*
 998                  * $commit^{/}. Some regex implementation may reject.
 999                  * We don't need regex anyway. '' pattern always matches.
1000                  */
1001                 if (sp[1] == '}')
1002                         return 0;
1003
1004                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1005                 commit_list_insert((struct commit *)o, &list);
1006                 ret = get_oid_oneline(prefix, oid, list);
1007                 free(prefix);
1008                 return ret;
1009         }
1010         return 0;
1011 }
1012
1013 static int get_describe_name(const char *name, int len, struct object_id *oid)
1014 {
1015         const char *cp;
1016         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1017
1018         for (cp = name + len - 1; name + 2 <= cp; cp--) {
1019                 char ch = *cp;
1020                 if (!isxdigit(ch)) {
1021                         /* We must be looking at g in "SOMETHING-g"
1022                          * for it to be describe output.
1023                          */
1024                         if (ch == 'g' && cp[-1] == '-') {
1025                                 cp++;
1026                                 len -= cp - name;
1027                                 return get_short_oid(cp, len, oid, flags);
1028                         }
1029                 }
1030         }
1031         return -1;
1032 }
1033
1034 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags)
1035 {
1036         int ret, has_suffix;
1037         const char *cp;
1038
1039         /*
1040          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1041          */
1042         has_suffix = 0;
1043         for (cp = name + len - 1; name <= cp; cp--) {
1044                 int ch = *cp;
1045                 if ('0' <= ch && ch <= '9')
1046                         continue;
1047                 if (ch == '~' || ch == '^')
1048                         has_suffix = ch;
1049                 break;
1050         }
1051
1052         if (has_suffix) {
1053                 int num = 0;
1054                 int len1 = cp - name;
1055                 cp++;
1056                 while (cp < name + len)
1057                         num = num * 10 + *cp++ - '0';
1058                 if (!num && len1 == len - 1)
1059                         num = 1;
1060                 if (has_suffix == '^')
1061                         return get_parent(name, len1, oid, num);
1062                 /* else if (has_suffix == '~') -- goes without saying */
1063                 return get_nth_ancestor(name, len1, oid, num);
1064         }
1065
1066         ret = peel_onion(name, len, oid, lookup_flags);
1067         if (!ret)
1068                 return 0;
1069
1070         ret = get_oid_basic(name, len, oid, lookup_flags);
1071         if (!ret)
1072                 return 0;
1073
1074         /* It could be describe output that is "SOMETHING-gXXXX" */
1075         ret = get_describe_name(name, len, oid);
1076         if (!ret)
1077                 return 0;
1078
1079         return get_short_oid(name, len, oid, lookup_flags);
1080 }
1081
1082 /*
1083  * This interprets names like ':/Initial revision of "git"' by searching
1084  * through history and returning the first commit whose message starts
1085  * the given regular expression.
1086  *
1087  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1088  *
1089  * For a literal '!' character at the beginning of a pattern, you have to repeat
1090  * that, like: ':/!!foo'
1091  *
1092  * For future extension, all other sequences beginning with ':/!' are reserved.
1093  */
1094
1095 /* Remember to update object flag allocation in object.h */
1096 #define ONELINE_SEEN (1u<<20)
1097
1098 static int handle_one_ref(const char *path, const struct object_id *oid,
1099                           int flag, void *cb_data)
1100 {
1101         struct commit_list **list = cb_data;
1102         struct object *object = parse_object(the_repository, oid);
1103         if (!object)
1104                 return 0;
1105         if (object->type == OBJ_TAG) {
1106                 object = deref_tag(the_repository, object, path,
1107                                    strlen(path));
1108                 if (!object)
1109                         return 0;
1110         }
1111         if (object->type != OBJ_COMMIT)
1112                 return 0;
1113         commit_list_insert((struct commit *)object, list);
1114         return 0;
1115 }
1116
1117 static int get_oid_oneline(const char *prefix, struct object_id *oid,
1118                             struct commit_list *list)
1119 {
1120         struct commit_list *backup = NULL, *l;
1121         int found = 0;
1122         int negative = 0;
1123         regex_t regex;
1124
1125         if (prefix[0] == '!') {
1126                 prefix++;
1127
1128                 if (prefix[0] == '-') {
1129                         prefix++;
1130                         negative = 1;
1131                 } else if (prefix[0] != '!') {
1132                         return -1;
1133                 }
1134         }
1135
1136         if (regcomp(&regex, prefix, REG_EXTENDED))
1137                 return -1;
1138
1139         for (l = list; l; l = l->next) {
1140                 l->item->object.flags |= ONELINE_SEEN;
1141                 commit_list_insert(l->item, &backup);
1142         }
1143         while (list) {
1144                 const char *p, *buf;
1145                 struct commit *commit;
1146                 int matches;
1147
1148                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1149                 if (!parse_object(the_repository, &commit->object.oid))
1150                         continue;
1151                 buf = get_commit_buffer(commit, NULL);
1152                 p = strstr(buf, "\n\n");
1153                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1154                 unuse_commit_buffer(commit, buf);
1155
1156                 if (matches) {
1157                         oidcpy(oid, &commit->object.oid);
1158                         found = 1;
1159                         break;
1160                 }
1161         }
1162         regfree(&regex);
1163         free_commit_list(list);
1164         for (l = backup; l; l = l->next)
1165                 clear_commit_marks(l->item, ONELINE_SEEN);
1166         free_commit_list(backup);
1167         return found ? 0 : -1;
1168 }
1169
1170 struct grab_nth_branch_switch_cbdata {
1171         int remaining;
1172         struct strbuf buf;
1173 };
1174
1175 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1176                                   const char *email, timestamp_t timestamp, int tz,
1177                                   const char *message, void *cb_data)
1178 {
1179         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1180         const char *match = NULL, *target = NULL;
1181         size_t len;
1182
1183         if (skip_prefix(message, "checkout: moving from ", &match))
1184                 target = strstr(match, " to ");
1185
1186         if (!match || !target)
1187                 return 0;
1188         if (--(cb->remaining) == 0) {
1189                 len = target - match;
1190                 strbuf_reset(&cb->buf);
1191                 strbuf_add(&cb->buf, match, len);
1192                 return 1; /* we are done */
1193         }
1194         return 0;
1195 }
1196
1197 /*
1198  * Parse @{-N} syntax, return the number of characters parsed
1199  * if successful; otherwise signal an error with negative value.
1200  */
1201 static int interpret_nth_prior_checkout(const char *name, int namelen,
1202                                         struct strbuf *buf)
1203 {
1204         long nth;
1205         int retval;
1206         struct grab_nth_branch_switch_cbdata cb;
1207         const char *brace;
1208         char *num_end;
1209
1210         if (namelen < 4)
1211                 return -1;
1212         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1213                 return -1;
1214         brace = memchr(name, '}', namelen);
1215         if (!brace)
1216                 return -1;
1217         nth = strtol(name + 3, &num_end, 10);
1218         if (num_end != brace)
1219                 return -1;
1220         if (nth <= 0)
1221                 return -1;
1222         cb.remaining = nth;
1223         strbuf_init(&cb.buf, 20);
1224
1225         retval = 0;
1226         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1227                 strbuf_reset(buf);
1228                 strbuf_addbuf(buf, &cb.buf);
1229                 retval = brace - name + 1;
1230         }
1231
1232         strbuf_release(&cb.buf);
1233         return retval;
1234 }
1235
1236 int get_oid_mb(const char *name, struct object_id *oid)
1237 {
1238         struct commit *one, *two;
1239         struct commit_list *mbs;
1240         struct object_id oid_tmp;
1241         const char *dots;
1242         int st;
1243
1244         dots = strstr(name, "...");
1245         if (!dots)
1246                 return get_oid(name, oid);
1247         if (dots == name)
1248                 st = get_oid("HEAD", &oid_tmp);
1249         else {
1250                 struct strbuf sb;
1251                 strbuf_init(&sb, dots - name);
1252                 strbuf_add(&sb, name, dots - name);
1253                 st = get_oid_committish(sb.buf, &oid_tmp);
1254                 strbuf_release(&sb);
1255         }
1256         if (st)
1257                 return st;
1258         one = lookup_commit_reference_gently(the_repository, &oid_tmp, 0);
1259         if (!one)
1260                 return -1;
1261
1262         if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1263                 return -1;
1264         two = lookup_commit_reference_gently(the_repository, &oid_tmp, 0);
1265         if (!two)
1266                 return -1;
1267         mbs = get_merge_bases(one, two);
1268         if (!mbs || mbs->next)
1269                 st = -1;
1270         else {
1271                 st = 0;
1272                 oidcpy(oid, &mbs->item->object.oid);
1273         }
1274         free_commit_list(mbs);
1275         return st;
1276 }
1277
1278 /* parse @something syntax, when 'something' is not {.*} */
1279 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1280 {
1281         const char *next;
1282
1283         if (len || name[1] == '{')
1284                 return -1;
1285
1286         /* make sure it's a single @, or @@{.*}, not @foo */
1287         next = memchr(name + len + 1, '@', namelen - len - 1);
1288         if (next && next[1] != '{')
1289                 return -1;
1290         if (!next)
1291                 next = name + namelen;
1292         if (next != name + 1)
1293                 return -1;
1294
1295         strbuf_reset(buf);
1296         strbuf_add(buf, "HEAD", 4);
1297         return 1;
1298 }
1299
1300 static int reinterpret(const char *name, int namelen, int len,
1301                        struct strbuf *buf, unsigned allowed)
1302 {
1303         /* we have extra data, which might need further processing */
1304         struct strbuf tmp = STRBUF_INIT;
1305         int used = buf->len;
1306         int ret;
1307
1308         strbuf_add(buf, name + len, namelen - len);
1309         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1310         /* that data was not interpreted, remove our cruft */
1311         if (ret < 0) {
1312                 strbuf_setlen(buf, used);
1313                 return len;
1314         }
1315         strbuf_reset(buf);
1316         strbuf_addbuf(buf, &tmp);
1317         strbuf_release(&tmp);
1318         /* tweak for size of {-N} versus expanded ref name */
1319         return ret - used + len;
1320 }
1321
1322 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1323 {
1324         char *s = shorten_unambiguous_ref(ref, 0);
1325         strbuf_reset(buf);
1326         strbuf_addstr(buf, s);
1327         free(s);
1328 }
1329
1330 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1331 {
1332         if (!allowed)
1333                 return 1;
1334
1335         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1336             starts_with(refname, "refs/heads/"))
1337                 return 1;
1338         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1339             starts_with(refname, "refs/remotes/"))
1340                 return 1;
1341
1342         return 0;
1343 }
1344
1345 static int interpret_branch_mark(const char *name, int namelen,
1346                                  int at, struct strbuf *buf,
1347                                  int (*get_mark)(const char *, int),
1348                                  const char *(*get_data)(struct branch *,
1349                                                          struct strbuf *),
1350                                  unsigned allowed)
1351 {
1352         int len;
1353         struct branch *branch;
1354         struct strbuf err = STRBUF_INIT;
1355         const char *value;
1356
1357         len = get_mark(name + at, namelen - at);
1358         if (!len)
1359                 return -1;
1360
1361         if (memchr(name, ':', at))
1362                 return -1;
1363
1364         if (at) {
1365                 char *name_str = xmemdupz(name, at);
1366                 branch = branch_get(name_str);
1367                 free(name_str);
1368         } else
1369                 branch = branch_get(NULL);
1370
1371         value = get_data(branch, &err);
1372         if (!value)
1373                 die("%s", err.buf);
1374
1375         if (!branch_interpret_allowed(value, allowed))
1376                 return -1;
1377
1378         set_shortened_ref(buf, value);
1379         return len + at;
1380 }
1381
1382 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1383                           unsigned allowed)
1384 {
1385         char *at;
1386         const char *start;
1387         int len;
1388
1389         if (!namelen)
1390                 namelen = strlen(name);
1391
1392         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1393                 len = interpret_nth_prior_checkout(name, namelen, buf);
1394                 if (!len) {
1395                         return len; /* syntax Ok, not enough switches */
1396                 } else if (len > 0) {
1397                         if (len == namelen)
1398                                 return len; /* consumed all */
1399                         else
1400                                 return reinterpret(name, namelen, len, buf, allowed);
1401                 }
1402         }
1403
1404         for (start = name;
1405              (at = memchr(start, '@', namelen - (start - name)));
1406              start = at + 1) {
1407
1408                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1409                         len = interpret_empty_at(name, namelen, at - name, buf);
1410                         if (len > 0)
1411                                 return reinterpret(name, namelen, len, buf,
1412                                                    allowed);
1413                 }
1414
1415                 len = interpret_branch_mark(name, namelen, at - name, buf,
1416                                             upstream_mark, branch_get_upstream,
1417                                             allowed);
1418                 if (len > 0)
1419                         return len;
1420
1421                 len = interpret_branch_mark(name, namelen, at - name, buf,
1422                                             push_mark, branch_get_push,
1423                                             allowed);
1424                 if (len > 0)
1425                         return len;
1426         }
1427
1428         return -1;
1429 }
1430
1431 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1432 {
1433         int len = strlen(name);
1434         int used = interpret_branch_name(name, len, sb, allowed);
1435
1436         if (used < 0)
1437                 used = 0;
1438         strbuf_add(sb, name + used, len - used);
1439 }
1440
1441 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1442 {
1443         if (startup_info->have_repository)
1444                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1445         else
1446                 strbuf_addstr(sb, name);
1447
1448         /*
1449          * This splice must be done even if we end up rejecting the
1450          * name; builtin/branch.c::copy_or_rename_branch() still wants
1451          * to see what the name expanded to so that "branch -m" can be
1452          * used as a tool to correct earlier mistakes.
1453          */
1454         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1455
1456         if (*name == '-' ||
1457             !strcmp(sb->buf, "refs/heads/HEAD"))
1458                 return -1;
1459
1460         return check_refname_format(sb->buf, 0);
1461 }
1462
1463 /*
1464  * This is like "get_oid_basic()", except it allows "object ID expressions",
1465  * notably "xyz^" for "parent of xyz"
1466  */
1467 int get_oid(const char *name, struct object_id *oid)
1468 {
1469         struct object_context unused;
1470         return get_oid_with_context(name, 0, oid, &unused);
1471 }
1472
1473
1474 /*
1475  * Many callers know that the user meant to name a commit-ish by
1476  * syntactical positions where the object name appears.  Calling this
1477  * function allows the machinery to disambiguate shorter-than-unique
1478  * abbreviated object names between commit-ish and others.
1479  *
1480  * Note that this does NOT error out when the named object is not a
1481  * commit-ish. It is merely to give a hint to the disambiguation
1482  * machinery.
1483  */
1484 int get_oid_committish(const char *name, struct object_id *oid)
1485 {
1486         struct object_context unused;
1487         return get_oid_with_context(name, GET_OID_COMMITTISH,
1488                                     oid, &unused);
1489 }
1490
1491 int get_oid_treeish(const char *name, struct object_id *oid)
1492 {
1493         struct object_context unused;
1494         return get_oid_with_context(name, GET_OID_TREEISH,
1495                                     oid, &unused);
1496 }
1497
1498 int get_oid_commit(const char *name, struct object_id *oid)
1499 {
1500         struct object_context unused;
1501         return get_oid_with_context(name, GET_OID_COMMIT,
1502                                     oid, &unused);
1503 }
1504
1505 int get_oid_tree(const char *name, struct object_id *oid)
1506 {
1507         struct object_context unused;
1508         return get_oid_with_context(name, GET_OID_TREE,
1509                                     oid, &unused);
1510 }
1511
1512 int get_oid_blob(const char *name, struct object_id *oid)
1513 {
1514         struct object_context unused;
1515         return get_oid_with_context(name, GET_OID_BLOB,
1516                                     oid, &unused);
1517 }
1518
1519 /* Must be called only when object_name:filename doesn't exist. */
1520 static void diagnose_invalid_oid_path(const char *prefix,
1521                                       const char *filename,
1522                                       const struct object_id *tree_oid,
1523                                       const char *object_name,
1524                                       int object_name_len)
1525 {
1526         struct object_id oid;
1527         unsigned mode;
1528
1529         if (!prefix)
1530                 prefix = "";
1531
1532         if (file_exists(filename))
1533                 die("Path '%s' exists on disk, but not in '%.*s'.",
1534                     filename, object_name_len, object_name);
1535         if (is_missing_file_error(errno)) {
1536                 char *fullname = xstrfmt("%s%s", prefix, filename);
1537
1538                 if (!get_tree_entry(tree_oid, fullname, &oid, &mode)) {
1539                         die("Path '%s' exists, but not '%s'.\n"
1540                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1541                             fullname,
1542                             filename,
1543                             object_name_len, object_name,
1544                             fullname,
1545                             object_name_len, object_name,
1546                             filename);
1547                 }
1548                 die("Path '%s' does not exist in '%.*s'",
1549                     filename, object_name_len, object_name);
1550         }
1551 }
1552
1553 /* Must be called only when :stage:filename doesn't exist. */
1554 static void diagnose_invalid_index_path(int stage,
1555                                         const char *prefix,
1556                                         const char *filename)
1557 {
1558         const struct cache_entry *ce;
1559         int pos;
1560         unsigned namelen = strlen(filename);
1561         struct strbuf fullname = STRBUF_INIT;
1562
1563         if (!prefix)
1564                 prefix = "";
1565
1566         /* Wrong stage number? */
1567         pos = cache_name_pos(filename, namelen);
1568         if (pos < 0)
1569                 pos = -pos - 1;
1570         if (pos < active_nr) {
1571                 ce = active_cache[pos];
1572                 if (ce_namelen(ce) == namelen &&
1573                     !memcmp(ce->name, filename, namelen))
1574                         die("Path '%s' is in the index, but not at stage %d.\n"
1575                             "Did you mean ':%d:%s'?",
1576                             filename, stage,
1577                             ce_stage(ce), filename);
1578         }
1579
1580         /* Confusion between relative and absolute filenames? */
1581         strbuf_addstr(&fullname, prefix);
1582         strbuf_addstr(&fullname, filename);
1583         pos = cache_name_pos(fullname.buf, fullname.len);
1584         if (pos < 0)
1585                 pos = -pos - 1;
1586         if (pos < active_nr) {
1587                 ce = active_cache[pos];
1588                 if (ce_namelen(ce) == fullname.len &&
1589                     !memcmp(ce->name, fullname.buf, fullname.len))
1590                         die("Path '%s' is in the index, but not '%s'.\n"
1591                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1592                             fullname.buf, filename,
1593                             ce_stage(ce), fullname.buf,
1594                             ce_stage(ce), filename);
1595         }
1596
1597         if (file_exists(filename))
1598                 die("Path '%s' exists on disk, but not in the index.", filename);
1599         if (is_missing_file_error(errno))
1600                 die("Path '%s' does not exist (neither on disk nor in the index).",
1601                     filename);
1602
1603         strbuf_release(&fullname);
1604 }
1605
1606
1607 static char *resolve_relative_path(const char *rel)
1608 {
1609         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1610                 return NULL;
1611
1612         if (!is_inside_work_tree())
1613                 die("relative path syntax can't be used outside working tree.");
1614
1615         /* die() inside prefix_path() if resolved path is outside worktree */
1616         return prefix_path(startup_info->prefix,
1617                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1618                            rel);
1619 }
1620
1621 static int get_oid_with_context_1(const char *name,
1622                                   unsigned flags,
1623                                   const char *prefix,
1624                                   struct object_id *oid,
1625                                   struct object_context *oc)
1626 {
1627         int ret, bracket_depth;
1628         int namelen = strlen(name);
1629         const char *cp;
1630         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1631
1632         if (only_to_die)
1633                 flags |= GET_OID_QUIETLY;
1634
1635         memset(oc, 0, sizeof(*oc));
1636         oc->mode = S_IFINVALID;
1637         strbuf_init(&oc->symlink_path, 0);
1638         ret = get_oid_1(name, namelen, oid, flags);
1639         if (!ret)
1640                 return ret;
1641         /*
1642          * sha1:path --> object name of path in ent sha1
1643          * :path -> object name of absolute path in index
1644          * :./path -> object name of path relative to cwd in index
1645          * :[0-3]:path -> object name of path in index at stage
1646          * :/foo -> recent commit matching foo
1647          */
1648         if (name[0] == ':') {
1649                 int stage = 0;
1650                 const struct cache_entry *ce;
1651                 char *new_path = NULL;
1652                 int pos;
1653                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1654                         struct commit_list *list = NULL;
1655
1656                         for_each_ref(handle_one_ref, &list);
1657                         commit_list_sort_by_date(&list);
1658                         return get_oid_oneline(name + 2, oid, list);
1659                 }
1660                 if (namelen < 3 ||
1661                     name[2] != ':' ||
1662                     name[1] < '0' || '3' < name[1])
1663                         cp = name + 1;
1664                 else {
1665                         stage = name[1] - '0';
1666                         cp = name + 3;
1667                 }
1668                 new_path = resolve_relative_path(cp);
1669                 if (!new_path) {
1670                         namelen = namelen - (cp - name);
1671                 } else {
1672                         cp = new_path;
1673                         namelen = strlen(cp);
1674                 }
1675
1676                 if (flags & GET_OID_RECORD_PATH)
1677                         oc->path = xstrdup(cp);
1678
1679                 if (!active_cache)
1680                         read_cache();
1681                 pos = cache_name_pos(cp, namelen);
1682                 if (pos < 0)
1683                         pos = -pos - 1;
1684                 while (pos < active_nr) {
1685                         ce = active_cache[pos];
1686                         if (ce_namelen(ce) != namelen ||
1687                             memcmp(ce->name, cp, namelen))
1688                                 break;
1689                         if (ce_stage(ce) == stage) {
1690                                 oidcpy(oid, &ce->oid);
1691                                 oc->mode = ce->ce_mode;
1692                                 free(new_path);
1693                                 return 0;
1694                         }
1695                         pos++;
1696                 }
1697                 if (only_to_die && name[1] && name[1] != '/')
1698                         diagnose_invalid_index_path(stage, prefix, cp);
1699                 free(new_path);
1700                 return -1;
1701         }
1702         for (cp = name, bracket_depth = 0; *cp; cp++) {
1703                 if (*cp == '{')
1704                         bracket_depth++;
1705                 else if (bracket_depth && *cp == '}')
1706                         bracket_depth--;
1707                 else if (!bracket_depth && *cp == ':')
1708                         break;
1709         }
1710         if (*cp == ':') {
1711                 struct object_id tree_oid;
1712                 int len = cp - name;
1713                 unsigned sub_flags = flags;
1714
1715                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1716                 sub_flags |= GET_OID_TREEISH;
1717
1718                 if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1719                         const char *filename = cp+1;
1720                         char *new_filename = NULL;
1721
1722                         new_filename = resolve_relative_path(filename);
1723                         if (new_filename)
1724                                 filename = new_filename;
1725                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1726                                 ret = get_tree_entry_follow_symlinks(&tree_oid,
1727                                         filename, oid, &oc->symlink_path,
1728                                         &oc->mode);
1729                         } else {
1730                                 ret = get_tree_entry(&tree_oid, filename, oid,
1731                                                      &oc->mode);
1732                                 if (ret && only_to_die) {
1733                                         diagnose_invalid_oid_path(prefix,
1734                                                                    filename,
1735                                                                    &tree_oid,
1736                                                                    name, len);
1737                                 }
1738                         }
1739                         if (flags & GET_OID_RECORD_PATH)
1740                                 oc->path = xstrdup(filename);
1741
1742                         free(new_filename);
1743                         return ret;
1744                 } else {
1745                         if (only_to_die)
1746                                 die("Invalid object name '%.*s'.", len, name);
1747                 }
1748         }
1749         return ret;
1750 }
1751
1752 /*
1753  * Call this function when you know "name" given by the end user must
1754  * name an object but it doesn't; the function _may_ die with a better
1755  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1756  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1757  * you have a chance to diagnose the error further.
1758  */
1759 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1760 {
1761         struct object_context oc;
1762         struct object_id oid;
1763         get_oid_with_context_1(name, GET_OID_ONLY_TO_DIE, prefix, &oid, &oc);
1764 }
1765
1766 int get_oid_with_context(const char *str, unsigned flags, struct object_id *oid, struct object_context *oc)
1767 {
1768         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1769                 BUG("incompatible flags for get_sha1_with_context");
1770         return get_oid_with_context_1(str, flags, NULL, oid, oc);
1771 }