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

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "tag.h"
   4 #include "commit.h"
   5 #include "tree.h"
   6 #include "blob.h"
   7 #include "tree-walk.h"
   8 #include "refs.h"
   9 #include "remote.h"
  10 #include "dir.h"
  11 #include "sha1-array.h"
  12 #include "packfile.h"
  13 #include "object-store.h"
  14 #include "repository.h"
  15 #include "midx.h"
  16 #include "commit-reach.h"
  17
  18 static int get_oid_oneline(const char *, struct object_id *, struct commit_list *);
  19
  20 typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
  21
  22 struct disambiguate_state {
  23         int len; /* length of prefix in hex chars */
  24         char hex_pfx[GIT_MAX_HEXSZ + 1];
  25         struct object_id bin_pfx;
  26
  27         disambiguate_hint_fn fn;
  28         void *cb_data;
  29         struct object_id candidate;
  30         unsigned candidate_exists:1;
  31         unsigned candidate_checked:1;
  32         unsigned candidate_ok:1;
  33         unsigned disambiguate_fn_used:1;
  34         unsigned ambiguous:1;
  35         unsigned always_call_fn:1;
  36 };
  37
  38 static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
  39 {
  40         if (ds->always_call_fn) {
  41                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  42                 return;
  43         }
  44         if (!ds->candidate_exists) {
  45                 /* this is the first candidate */
  46                 oidcpy(&ds->candidate, current);
  47                 ds->candidate_exists = 1;
  48                 return;
  49         } else if (oideq(&ds->candidate, current)) {
  50                 /* the same as what we already have seen */
  51                 return;
  52         }
  53
  54         if (!ds->fn) {
  55                 /* cannot disambiguate between ds->candidate and current */
  56                 ds->ambiguous = 1;
  57                 return;
  58         }
  59
  60         if (!ds->candidate_checked) {
  61                 ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
  62                 ds->disambiguate_fn_used = 1;
  63                 ds->candidate_checked = 1;
  64         }
  65
  66         if (!ds->candidate_ok) {
  67                 /* discard the candidate; we know it does not satisfy fn */
  68                 oidcpy(&ds->candidate, current);
  69                 ds->candidate_checked = 0;
  70                 return;
  71         }
  72
  73         /* if we reach this point, we know ds->candidate satisfies fn */
  74         if (ds->fn(current, ds->cb_data)) {
  75                 /*
  76                  * if both current and candidate satisfy fn, we cannot
  77                  * disambiguate.
  78                  */
  79                 ds->candidate_ok = 0;
  80                 ds->ambiguous = 1;
  81         }
  82
  83         /* otherwise, current can be discarded and candidate is still good */
  84 }
  85
  86 static int append_loose_object(const struct object_id *oid, const char *path,
  87                                void *data)
  88 {
  89         oid_array_append(data, oid);
  90         return 0;
  91 }
  92
  93 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  94
  95 static void find_short_object_filename(struct disambiguate_state *ds)
  96 {
  97         int subdir_nr = ds->bin_pfx.hash[0];
  98         struct alternate_object_database *alt;
  99         static struct alternate_object_database *fakeent;
 100
 101         if (!fakeent) {
 102                 /*
 103                  * Create a "fake" alternate object database that
 104                  * points to our own object database, to make it
 105                  * easier to get a temporary working space in
 106                  * alt->name/alt->base while iterating over the
 107                  * object databases including our own.
 108                  */
 109                 fakeent = alloc_alt_odb(get_object_directory());
 110         }
 111         fakeent->next = the_repository->objects->alt_odb_list;
 112
 113         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 114                 int pos;
 115
 116                 if (!alt->loose_objects_subdir_seen[subdir_nr]) {
 117                         struct strbuf *buf = alt_scratch_buf(alt);
 118                         for_each_file_in_obj_subdir(subdir_nr, buf,
 119                                                     append_loose_object,
 120                                                     NULL, NULL,
 121                                                     &alt->loose_objects_cache);
 122                         alt->loose_objects_subdir_seen[subdir_nr] = 1;
 123                 }
 124
 125                 pos = oid_array_lookup(&alt->loose_objects_cache, &ds->bin_pfx);
 126                 if (pos < 0)
 127                         pos = -1 - pos;
 128                 while (!ds->ambiguous && pos < alt->loose_objects_cache.nr) {
 129                         const struct object_id *oid;
 130                         oid = alt->loose_objects_cache.oid + pos;
 131                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 132                                 break;
 133                         update_candidates(ds, oid);
 134                         pos++;
 135                 }
 136         }
 137 }
 138
 139 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 140 {
 141         do {
 142                 if (*a != *b)
 143                         return 0;
 144                 a++;
 145                 b++;
 146                 len -= 2;
 147         } while (len > 1);
 148         if (len)
 149                 if ((*a ^ *b) & 0xf0)
 150                         return 0;
 151         return 1;
 152 }
 153
 154 static void unique_in_midx(struct multi_pack_index *m,
 155                            struct disambiguate_state *ds)
 156 {
 157         uint32_t num, i, first = 0;
 158         const struct object_id *current = NULL;
 159         num = m->num_objects;
 160
 161         if (!num)
 162                 return;
 163
 164         bsearch_midx(&ds->bin_pfx, m, &first);
 165
 166         /*
 167          * At this point, "first" is the location of the lowest object
 168          * with an object name that could match "bin_pfx".  See if we have
 169          * 0, 1 or more objects that actually match(es).
 170          */
 171         for (i = first; i < num && !ds->ambiguous; i++) {
 172                 struct object_id oid;
 173                 current = nth_midxed_object_oid(&oid, m, i);
 174                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 175                         break;
 176                 update_candidates(ds, current);
 177         }
 178 }
 179
 180 static void unique_in_pack(struct packed_git *p,
 181                            struct disambiguate_state *ds)
 182 {
 183         uint32_t num, i, first = 0;
 184         const struct object_id *current = NULL;
 185
 186         if (open_pack_index(p) || !p->num_objects)
 187                 return;
 188
 189         num = p->num_objects;
 190         bsearch_pack(&ds->bin_pfx, p, &first);
 191
 192         /*
 193          * At this point, "first" is the location of the lowest object
 194          * with an object name that could match "bin_pfx".  See if we have
 195          * 0, 1 or more objects that actually match(es).
 196          */
 197         for (i = first; i < num && !ds->ambiguous; i++) {
 198                 struct object_id oid;
 199                 current = nth_packed_object_oid(&oid, p, i);
 200                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 201                         break;
 202                 update_candidates(ds, current);
 203         }
 204 }
 205
 206 static void find_short_packed_object(struct disambiguate_state *ds)
 207 {
 208         struct multi_pack_index *m;
 209         struct packed_git *p;
 210
 211         for (m = get_multi_pack_index(the_repository); m && !ds->ambiguous;
 212              m = m->next)
 213                 unique_in_midx(m, ds);
 214         for (p = get_packed_git(the_repository); p && !ds->ambiguous;
 215              p = p->next)
 216                 unique_in_pack(p, ds);
 217 }
 218
 219 #define SHORT_NAME_NOT_FOUND (-1)
 220 #define SHORT_NAME_AMBIGUOUS (-2)
 221
 222 static int finish_object_disambiguation(struct disambiguate_state *ds,
 223                                         struct object_id *oid)
 224 {
 225         if (ds->ambiguous)
 226                 return SHORT_NAME_AMBIGUOUS;
 227
 228         if (!ds->candidate_exists)
 229                 return SHORT_NAME_NOT_FOUND;
 230
 231         if (!ds->candidate_checked)
 232                 /*
 233                  * If this is the only candidate, there is no point
 234                  * calling the disambiguation hint callback.
 235                  *
 236                  * On the other hand, if the current candidate
 237                  * replaced an earlier candidate that did _not_ pass
 238                  * the disambiguation hint callback, then we do have
 239                  * more than one objects that match the short name
 240                  * given, so we should make sure this one matches;
 241                  * otherwise, if we discovered this one and the one
 242                  * that we previously discarded in the reverse order,
 243                  * we would end up showing different results in the
 244                  * same repository!
 245                  */
 246                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 247                                     ds->fn(&ds->candidate, ds->cb_data));
 248
 249         if (!ds->candidate_ok)
 250                 return SHORT_NAME_AMBIGUOUS;
 251
 252         oidcpy(oid, &ds->candidate);
 253         return 0;
 254 }
 255
 256 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 257 {
 258         int kind = oid_object_info(the_repository, oid, NULL);
 259         return kind == OBJ_COMMIT;
 260 }
 261
 262 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 263 {
 264         struct object *obj;
 265         int kind;
 266
 267         kind = oid_object_info(the_repository, oid, NULL);
 268         if (kind == OBJ_COMMIT)
 269                 return 1;
 270         if (kind != OBJ_TAG)
 271                 return 0;
 272
 273         /* We need to do this the hard way... */
 274         obj = deref_tag(the_repository, parse_object(the_repository, oid),
 275                         NULL, 0);
 276         if (obj && obj->type == OBJ_COMMIT)
 277                 return 1;
 278         return 0;
 279 }
 280
 281 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 282 {
 283         int kind = oid_object_info(the_repository, oid, NULL);
 284         return kind == OBJ_TREE;
 285 }
 286
 287 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 288 {
 289         struct object *obj;
 290         int kind;
 291
 292         kind = oid_object_info(the_repository, oid, NULL);
 293         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 294                 return 1;
 295         if (kind != OBJ_TAG)
 296                 return 0;
 297
 298         /* We need to do this the hard way... */
 299         obj = deref_tag(the_repository, parse_object(the_repository, oid),
 300                         NULL, 0);
 301         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 302                 return 1;
 303         return 0;
 304 }
 305
 306 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 307 {
 308         int kind = oid_object_info(the_repository, oid, NULL);
 309         return kind == OBJ_BLOB;
 310 }
 311
 312 static disambiguate_hint_fn default_disambiguate_hint;
 313
 314 int set_disambiguate_hint_config(const char *var, const char *value)
 315 {
 316         static const struct {
 317                 const char *name;
 318                 disambiguate_hint_fn fn;
 319         } hints[] = {
 320                 { "none", NULL },
 321                 { "commit", disambiguate_commit_only },
 322                 { "committish", disambiguate_committish_only },
 323                 { "tree", disambiguate_tree_only },
 324                 { "treeish", disambiguate_treeish_only },
 325                 { "blob", disambiguate_blob_only }
 326         };
 327         int i;
 328
 329         if (!value)
 330                 return config_error_nonbool(var);
 331
 332         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 333                 if (!strcasecmp(value, hints[i].name)) {
 334                         default_disambiguate_hint = hints[i].fn;
 335                         return 0;
 336                 }
 337         }
 338
 339         return error("unknown hint type for '%s': %s", var, value);
 340 }
 341
 342 static int init_object_disambiguation(const char *name, int len,
 343                                       struct disambiguate_state *ds)
 344 {
 345         int i;
 346
 347         if (len < MINIMUM_ABBREV || len > the_hash_algo->hexsz)
 348                 return -1;
 349
 350         memset(ds, 0, sizeof(*ds));
 351
 352         for (i = 0; i < len ;i++) {
 353                 unsigned char c = name[i];
 354                 unsigned char val;
 355                 if (c >= '0' && c <= '9')
 356                         val = c - '0';
 357                 else if (c >= 'a' && c <= 'f')
 358                         val = c - 'a' + 10;
 359                 else if (c >= 'A' && c <='F') {
 360                         val = c - 'A' + 10;
 361                         c -= 'A' - 'a';
 362                 }
 363                 else
 364                         return -1;
 365                 ds->hex_pfx[i] = c;
 366                 if (!(i & 1))
 367                         val <<= 4;
 368                 ds->bin_pfx.hash[i >> 1] |= val;
 369         }
 370
 371         ds->len = len;
 372         ds->hex_pfx[len] = '\0';
 373         prepare_alt_odb(the_repository);
 374         return 0;
 375 }
 376
 377 static int show_ambiguous_object(const struct object_id *oid, void *data)
 378 {
 379         const struct disambiguate_state *ds = data;
 380         struct strbuf desc = STRBUF_INIT;
 381         int type;
 382
 383         if (ds->fn && !ds->fn(oid, ds->cb_data))
 384                 return 0;
 385
 386         type = oid_object_info(the_repository, oid, NULL);
 387         if (type == OBJ_COMMIT) {
 388                 struct commit *commit = lookup_commit(the_repository, oid);
 389                 if (commit) {
 390                         struct pretty_print_context pp = {0};
 391                         pp.date_mode.type = DATE_SHORT;
 392                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 393                 }
 394         } else if (type == OBJ_TAG) {
 395                 struct tag *tag = lookup_tag(the_repository, oid);
 396                 if (!parse_tag(tag) && tag->tag)
 397                         strbuf_addf(&desc, " %s", tag->tag);
 398         }
 399
 400         advise("  %s %s%s",
 401                find_unique_abbrev(oid, DEFAULT_ABBREV),
 402                type_name(type) ? type_name(type) : "unknown type",
 403                desc.buf);
 404
 405         strbuf_release(&desc);
 406         return 0;
 407 }
 408
 409 static int collect_ambiguous(const struct object_id *oid, void *data)
 410 {
 411         oid_array_append(data, oid);
 412         return 0;
 413 }
 414
 415 static int sort_ambiguous(const void *a, const void *b)
 416 {
 417         int a_type = oid_object_info(the_repository, a, NULL);
 418         int b_type = oid_object_info(the_repository, b, NULL);
 419         int a_type_sort;
 420         int b_type_sort;
 421
 422         /*
 423          * Sorts by hash within the same object type, just as
 424          * oid_array_for_each_unique() would do.
 425          */
 426         if (a_type == b_type)
 427                 return oidcmp(a, b);
 428
 429         /*
 430          * Between object types show tags, then commits, and finally
 431          * trees and blobs.
 432          *
 433          * The object_type enum is commit, tree, blob, tag, but we
 434          * want tag, commit, tree blob. Cleverly (perhaps too
 435          * cleverly) do that with modulus, since the enum assigns 1 to
 436          * commit, so tag becomes 0.
 437          */
 438         a_type_sort = a_type % 4;
 439         b_type_sort = b_type % 4;
 440         return a_type_sort > b_type_sort ? 1 : -1;
 441 }
 442
 443 static int get_short_oid(const char *name, int len, struct object_id *oid,
 444                           unsigned flags)
 445 {
 446         int status;
 447         struct disambiguate_state ds;
 448         int quietly = !!(flags & GET_OID_QUIETLY);
 449
 450         if (init_object_disambiguation(name, len, &ds) < 0)
 451                 return -1;
 452
 453         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 454                 BUG("multiple get_short_oid disambiguator flags");
 455
 456         if (flags & GET_OID_COMMIT)
 457                 ds.fn = disambiguate_commit_only;
 458         else if (flags & GET_OID_COMMITTISH)
 459                 ds.fn = disambiguate_committish_only;
 460         else if (flags & GET_OID_TREE)
 461                 ds.fn = disambiguate_tree_only;
 462         else if (flags & GET_OID_TREEISH)
 463                 ds.fn = disambiguate_treeish_only;
 464         else if (flags & GET_OID_BLOB)
 465                 ds.fn = disambiguate_blob_only;
 466         else
 467                 ds.fn = default_disambiguate_hint;
 468
 469         find_short_object_filename(&ds);
 470         find_short_packed_object(&ds);
 471         status = finish_object_disambiguation(&ds, oid);
 472
 473         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 474                 struct oid_array collect = OID_ARRAY_INIT;
 475
 476                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 477
 478                 /*
 479                  * We may still have ambiguity if we simply saw a series of
 480                  * candidates that did not satisfy our hint function. In
 481                  * that case, we still want to show them, so disable the hint
 482                  * function entirely.
 483                  */
 484                 if (!ds.ambiguous)
 485                         ds.fn = NULL;
 486
 487                 advise(_("The candidates are:"));
 488                 for_each_abbrev(ds.hex_pfx, collect_ambiguous, &collect);
 489                 QSORT(collect.oid, collect.nr, sort_ambiguous);
 490
 491                 if (oid_array_for_each(&collect, show_ambiguous_object, &ds))
 492                         BUG("show_ambiguous_object shouldn't return non-zero");
 493                 oid_array_clear(&collect);
 494         }
 495
 496         return status;
 497 }
 498
 499 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 500 {
 501         struct oid_array collect = OID_ARRAY_INIT;
 502         struct disambiguate_state ds;
 503         int ret;
 504
 505         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 506                 return -1;
 507
 508         ds.always_call_fn = 1;
 509         ds.fn = collect_ambiguous;
 510         ds.cb_data = &collect;
 511         find_short_object_filename(&ds);
 512         find_short_packed_object(&ds);
 513
 514         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 515         oid_array_clear(&collect);
 516         return ret;
 517 }
 518
 519 /*
 520  * Return the slot of the most-significant bit set in "val". There are various
 521  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 522  * probably not a big deal here.
 523  */
 524 static unsigned msb(unsigned long val)
 525 {
 526         unsigned r = 0;
 527         while (val >>= 1)
 528                 r++;
 529         return r;
 530 }
 531
 532 struct min_abbrev_data {
 533         unsigned int init_len;
 534         unsigned int cur_len;
 535         char *hex;
 536         const struct object_id *oid;
 537 };
 538
 539 static inline char get_hex_char_from_oid(const struct object_id *oid,
 540                                          unsigned int pos)
 541 {
 542         static const char hex[] = "0123456789abcdef";
 543
 544         if ((pos & 1) == 0)
 545                 return hex[oid->hash[pos >> 1] >> 4];
 546         else
 547                 return hex[oid->hash[pos >> 1] & 0xf];
 548 }
 549
 550 static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
 551 {
 552         struct min_abbrev_data *mad = cb_data;
 553
 554         unsigned int i = mad->init_len;
 555         while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
 556                 i++;
 557
 558         if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
 559                 mad->cur_len = i + 1;
 560
 561         return 0;
 562 }
 563
 564 static void find_abbrev_len_for_midx(struct multi_pack_index *m,
 565                                      struct min_abbrev_data *mad)
 566 {
 567         int match = 0;
 568         uint32_t num, first = 0;
 569         struct object_id oid;
 570         const struct object_id *mad_oid;
 571
 572         if (!m->num_objects)
 573                 return;
 574
 575         num = m->num_objects;
 576         mad_oid = mad->oid;
 577         match = bsearch_midx(mad_oid, m, &first);
 578
 579         /*
 580          * first is now the position in the packfile where we would insert
 581          * mad->hash if it does not exist (or the position of mad->hash if
 582          * it does exist). Hence, we consider a maximum of two objects
 583          * nearby for the abbreviation length.
 584          */
 585         mad->init_len = 0;
 586         if (!match) {
 587                 if (nth_midxed_object_oid(&oid, m, first))
 588                         extend_abbrev_len(&oid, mad);
 589         } else if (first < num - 1) {
 590                 if (nth_midxed_object_oid(&oid, m, first + 1))
 591                         extend_abbrev_len(&oid, mad);
 592         }
 593         if (first > 0) {
 594                 if (nth_midxed_object_oid(&oid, m, first - 1))
 595                         extend_abbrev_len(&oid, mad);
 596         }
 597         mad->init_len = mad->cur_len;
 598 }
 599
 600 static void find_abbrev_len_for_pack(struct packed_git *p,
 601                                      struct min_abbrev_data *mad)
 602 {
 603         int match = 0;
 604         uint32_t num, first = 0;
 605         struct object_id oid;
 606         const struct object_id *mad_oid;
 607
 608         if (open_pack_index(p) || !p->num_objects)
 609                 return;
 610
 611         num = p->num_objects;
 612         mad_oid = mad->oid;
 613         match = bsearch_pack(mad_oid, p, &first);
 614
 615         /*
 616          * first is now the position in the packfile where we would insert
 617          * mad->hash if it does not exist (or the position of mad->hash if
 618          * it does exist). Hence, we consider a maximum of two objects
 619          * nearby for the abbreviation length.
 620          */
 621         mad->init_len = 0;
 622         if (!match) {
 623                 if (nth_packed_object_oid(&oid, p, first))
 624                         extend_abbrev_len(&oid, mad);
 625         } else if (first < num - 1) {
 626                 if (nth_packed_object_oid(&oid, p, first + 1))
 627                         extend_abbrev_len(&oid, mad);
 628         }
 629         if (first > 0) {
 630                 if (nth_packed_object_oid(&oid, p, first - 1))
 631                         extend_abbrev_len(&oid, mad);
 632         }
 633         mad->init_len = mad->cur_len;
 634 }
 635
 636 static void find_abbrev_len_packed(struct min_abbrev_data *mad)
 637 {
 638         struct multi_pack_index *m;
 639         struct packed_git *p;
 640
 641         for (m = get_multi_pack_index(the_repository); m; m = m->next)
 642                 find_abbrev_len_for_midx(m, mad);
 643         for (p = get_packed_git(the_repository); p; p = p->next)
 644                 find_abbrev_len_for_pack(p, mad);
 645 }
 646
 647 int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 648 {
 649         struct disambiguate_state ds;
 650         struct min_abbrev_data mad;
 651         struct object_id oid_ret;
 652         const unsigned hexsz = the_hash_algo->hexsz;
 653
 654         if (len < 0) {
 655                 unsigned long count = approximate_object_count();
 656                 /*
 657                  * Add one because the MSB only tells us the highest bit set,
 658                  * not including the value of all the _other_ bits (so "15"
 659                  * is only one off of 2^4, but the MSB is the 3rd bit.
 660                  */
 661                 len = msb(count) + 1;
 662                 /*
 663                  * We now know we have on the order of 2^len objects, which
 664                  * expects a collision at 2^(len/2). But we also care about hex
 665                  * chars, not bits, and there are 4 bits per hex. So all
 666                  * together we need to divide by 2 and round up.
 667                  */
 668                 len = DIV_ROUND_UP(len, 2);
 669                 /*
 670                  * For very small repos, we stick with our regular fallback.
 671                  */
 672                 if (len < FALLBACK_DEFAULT_ABBREV)
 673                         len = FALLBACK_DEFAULT_ABBREV;
 674         }
 675
 676         oid_to_hex_r(hex, oid);
 677         if (len == hexsz || !len)
 678                 return hexsz;
 679
 680         mad.init_len = len;
 681         mad.cur_len = len;
 682         mad.hex = hex;
 683         mad.oid = oid;
 684
 685         find_abbrev_len_packed(&mad);
 686
 687         if (init_object_disambiguation(hex, mad.cur_len, &ds) < 0)
 688                 return -1;
 689
 690         ds.fn = extend_abbrev_len;
 691         ds.always_call_fn = 1;
 692         ds.cb_data = (void *)&mad;
 693
 694         find_short_object_filename(&ds);
 695         (void)finish_object_disambiguation(&ds, &oid_ret);
 696
 697         hex[mad.cur_len] = 0;
 698         return mad.cur_len;
 699 }
 700
 701 const char *find_unique_abbrev(const struct object_id *oid, int len)
 702 {
 703         static int bufno;
 704         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 705         char *hex = hexbuffer[bufno];
 706         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 707         find_unique_abbrev_r(hex, oid, len);
 708         return hex;
 709 }
 710
 711 static int ambiguous_path(const char *path, int len)
 712 {
 713         int slash = 1;
 714         int cnt;
 715
 716         for (cnt = 0; cnt < len; cnt++) {
 717                 switch (*path++) {
 718                 case '\0':
 719                         break;
 720                 case '/':
 721                         if (slash)
 722                                 break;
 723                         slash = 1;
 724                         continue;
 725                 case '.':
 726                         continue;
 727                 default:
 728                         slash = 0;
 729                         continue;
 730                 }
 731                 break;
 732         }
 733         return slash;
 734 }
 735
 736 static inline int at_mark(const char *string, int len,
 737                           const char **suffix, int nr)
 738 {
 739         int i;
 740
 741         for (i = 0; i < nr; i++) {
 742                 int suffix_len = strlen(suffix[i]);
 743                 if (suffix_len <= len
 744                     && !strncasecmp(string, suffix[i], suffix_len))
 745                         return suffix_len;
 746         }
 747         return 0;
 748 }
 749
 750 static inline int upstream_mark(const char *string, int len)
 751 {
 752         const char *suffix[] = { "@{upstream}", "@{u}" };
 753         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 754 }
 755
 756 static inline int push_mark(const char *string, int len)
 757 {
 758         const char *suffix[] = { "@{push}" };
 759         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 760 }
 761
 762 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 763 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 764
 765 static int get_oid_basic(const char *str, int len, struct object_id *oid,
 766                           unsigned int flags)
 767 {
 768         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 769         static const char *object_name_msg = N_(
 770         "Git normally never creates a ref that ends with 40 hex characters\n"
 771         "because it will be ignored when you just specify 40-hex. These refs\n"
 772         "may be created by mistake. For example,\n"
 773         "\n"
 774         "  git checkout -b $br $(git rev-parse ...)\n"
 775         "\n"
 776         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 777         "examine these refs and maybe delete them. Turn this message off by\n"
 778         "running \"git config advice.objectNameWarning false\"");
 779         struct object_id tmp_oid;
 780         char *real_ref = NULL;
 781         int refs_found = 0;
 782         int at, reflog_len, nth_prior = 0;
 783
 784         if (len == the_hash_algo->hexsz && !get_oid_hex(str, oid)) {
 785                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 786                         refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
 787                         if (refs_found > 0) {
 788                                 warning(warn_msg, len, str);
 789                                 if (advice_object_name_warning)
 790                                         fprintf(stderr, "%s\n", _(object_name_msg));
 791                         }
 792                         free(real_ref);
 793                 }
 794                 return 0;
 795         }
 796
 797         /* basic@{time or number or -number} format to query ref-log */
 798         reflog_len = at = 0;
 799         if (len && str[len-1] == '}') {
 800                 for (at = len-4; at >= 0; at--) {
 801                         if (str[at] == '@' && str[at+1] == '{') {
 802                                 if (str[at+2] == '-') {
 803                                         if (at != 0)
 804                                                 /* @{-N} not at start */
 805                                                 return -1;
 806                                         nth_prior = 1;
 807                                         continue;
 808                                 }
 809                                 if (!upstream_mark(str + at, len - at) &&
 810                                     !push_mark(str + at, len - at)) {
 811                                         reflog_len = (len-1) - (at+2);
 812                                         len = at;
 813                                 }
 814                                 break;
 815                         }
 816                 }
 817         }
 818
 819         /* Accept only unambiguous ref paths. */
 820         if (len && ambiguous_path(str, len))
 821                 return -1;
 822
 823         if (nth_prior) {
 824                 struct strbuf buf = STRBUF_INIT;
 825                 int detached;
 826
 827                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 828                         detached = (buf.len == the_hash_algo->hexsz && !get_oid_hex(buf.buf, oid));
 829                         strbuf_release(&buf);
 830                         if (detached)
 831                                 return 0;
 832                 }
 833         }
 834
 835         if (!len && reflog_len)
 836                 /* allow "@{...}" to mean the current branch reflog */
 837                 refs_found = dwim_ref("HEAD", 4, oid, &real_ref);
 838         else if (reflog_len)
 839                 refs_found = dwim_log(str, len, oid, &real_ref);
 840         else
 841                 refs_found = dwim_ref(str, len, oid, &real_ref);
 842
 843         if (!refs_found)
 844                 return -1;
 845
 846         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 847             (refs_found > 1 ||
 848              !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
 849                 warning(warn_msg, len, str);
 850
 851         if (reflog_len) {
 852                 int nth, i;
 853                 timestamp_t at_time;
 854                 timestamp_t co_time;
 855                 int co_tz, co_cnt;
 856
 857                 /* Is it asking for N-th entry, or approxidate? */
 858                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 859                         char ch = str[at+2+i];
 860                         if ('0' <= ch && ch <= '9')
 861                                 nth = nth * 10 + ch - '0';
 862                         else
 863                                 nth = -1;
 864                 }
 865                 if (100000000 <= nth) {
 866                         at_time = nth;
 867                         nth = -1;
 868                 } else if (0 <= nth)
 869                         at_time = 0;
 870                 else {
 871                         int errors = 0;
 872                         char *tmp = xstrndup(str + at + 2, reflog_len);
 873                         at_time = approxidate_careful(tmp, &errors);
 874                         free(tmp);
 875                         if (errors) {
 876                                 free(real_ref);
 877                                 return -1;
 878                         }
 879                 }
 880                 if (read_ref_at(real_ref, flags, at_time, nth, oid, NULL,
 881                                 &co_time, &co_tz, &co_cnt)) {
 882                         if (!len) {
 883                                 if (starts_with(real_ref, "refs/heads/")) {
 884                                         str = real_ref + 11;
 885                                         len = strlen(real_ref + 11);
 886                                 } else {
 887                                         /* detached HEAD */
 888                                         str = "HEAD";
 889                                         len = 4;
 890                                 }
 891                         }
 892                         if (at_time) {
 893                                 if (!(flags & GET_OID_QUIETLY)) {
 894                                         warning("Log for '%.*s' only goes "
 895                                                 "back to %s.", len, str,
 896                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 897                                 }
 898                         } else {
 899                                 if (flags & GET_OID_QUIETLY) {
 900                                         exit(128);
 901                                 }
 902                                 die("Log for '%.*s' only has %d entries.",
 903                                     len, str, co_cnt);
 904                         }
 905                 }
 906         }
 907
 908         free(real_ref);
 909         return 0;
 910 }
 911
 912 static int get_parent(const char *name, int len,
 913                       struct object_id *result, int idx)
 914 {
 915         struct object_id oid;
 916         int ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 917         struct commit *commit;
 918         struct commit_list *p;
 919
 920         if (ret)
 921                 return ret;
 922         commit = lookup_commit_reference(the_repository, &oid);
 923         if (parse_commit(commit))
 924                 return -1;
 925         if (!idx) {
 926                 oidcpy(result, &commit->object.oid);
 927                 return 0;
 928         }
 929         p = commit->parents;
 930         while (p) {
 931                 if (!--idx) {
 932                         oidcpy(result, &p->item->object.oid);
 933                         return 0;
 934                 }
 935                 p = p->next;
 936         }
 937         return -1;
 938 }
 939
 940 static int get_nth_ancestor(const char *name, int len,
 941                             struct object_id *result, int generation)
 942 {
 943         struct object_id oid;
 944         struct commit *commit;
 945         int ret;
 946
 947         ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 948         if (ret)
 949                 return ret;
 950         commit = lookup_commit_reference(the_repository, &oid);
 951         if (!commit)
 952                 return -1;
 953
 954         while (generation--) {
 955                 if (parse_commit(commit) || !commit->parents)
 956                         return -1;
 957                 commit = commit->parents->item;
 958         }
 959         oidcpy(result, &commit->object.oid);
 960         return 0;
 961 }
 962
 963 struct object *peel_to_type(const char *name, int namelen,
 964                             struct object *o, enum object_type expected_type)
 965 {
 966         if (name && !namelen)
 967                 namelen = strlen(name);
 968         while (1) {
 969                 if (!o || (!o->parsed && !parse_object(the_repository, &o->oid)))
 970                         return NULL;
 971                 if (expected_type == OBJ_ANY || o->type == expected_type)
 972                         return o;
 973                 if (o->type == OBJ_TAG)
 974                         o = ((struct tag*) o)->tagged;
 975                 else if (o->type == OBJ_COMMIT)
 976                         o = &(get_commit_tree(((struct commit *)o))->object);
 977                 else {
 978                         if (name)
 979                                 error("%.*s: expected %s type, but the object "
 980                                       "dereferences to %s type",
 981                                       namelen, name, type_name(expected_type),
 982                                       type_name(o->type));
 983                         return NULL;
 984                 }
 985         }
 986 }
 987
 988 static int peel_onion(const char *name, int len, struct object_id *oid,
 989                       unsigned lookup_flags)
 990 {
 991         struct object_id outer;
 992         const char *sp;
 993         unsigned int expected_type = 0;
 994         struct object *o;
 995
 996         /*
 997          * "ref^{type}" dereferences ref repeatedly until you cannot
 998          * dereference anymore, or you get an object of given type,
 999          * whichever comes first.  "ref^{}" means just dereference
1000          * tags until you get a non-tag.  "ref^0" is a shorthand for
1001          * "ref^{commit}".  "commit^{tree}" could be used to find the
1002          * top-level tree of the given commit.
1003          */
1004         if (len < 4 || name[len-1] != '}')
1005                 return -1;
1006
1007         for (sp = name + len - 1; name <= sp; sp--) {
1008                 int ch = *sp;
1009                 if (ch == '{' && name < sp && sp[-1] == '^')
1010                         break;
1011         }
1012         if (sp <= name)
1013                 return -1;
1014
1015         sp++; /* beginning of type name, or closing brace for empty */
1016         if (starts_with(sp, "commit}"))
1017                 expected_type = OBJ_COMMIT;
1018         else if (starts_with(sp, "tag}"))
1019                 expected_type = OBJ_TAG;
1020         else if (starts_with(sp, "tree}"))
1021                 expected_type = OBJ_TREE;
1022         else if (starts_with(sp, "blob}"))
1023                 expected_type = OBJ_BLOB;
1024         else if (starts_with(sp, "object}"))
1025                 expected_type = OBJ_ANY;
1026         else if (sp[0] == '}')
1027                 expected_type = OBJ_NONE;
1028         else if (sp[0] == '/')
1029                 expected_type = OBJ_COMMIT;
1030         else
1031                 return -1;
1032
1033         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
1034         if (expected_type == OBJ_COMMIT)
1035                 lookup_flags |= GET_OID_COMMITTISH;
1036         else if (expected_type == OBJ_TREE)
1037                 lookup_flags |= GET_OID_TREEISH;
1038
1039         if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
1040                 return -1;
1041
1042         o = parse_object(the_repository, &outer);
1043         if (!o)
1044                 return -1;
1045         if (!expected_type) {
1046                 o = deref_tag(the_repository, o, name, sp - name - 2);
1047                 if (!o || (!o->parsed && !parse_object(the_repository, &o->oid)))
1048                         return -1;
1049                 oidcpy(oid, &o->oid);
1050                 return 0;
1051         }
1052
1053         /*
1054          * At this point, the syntax look correct, so
1055          * if we do not get the needed object, we should
1056          * barf.
1057          */
1058         o = peel_to_type(name, len, o, expected_type);
1059         if (!o)
1060                 return -1;
1061
1062         oidcpy(oid, &o->oid);
1063         if (sp[0] == '/') {
1064                 /* "$commit^{/foo}" */
1065                 char *prefix;
1066                 int ret;
1067                 struct commit_list *list = NULL;
1068
1069                 /*
1070                  * $commit^{/}. Some regex implementation may reject.
1071                  * We don't need regex anyway. '' pattern always matches.
1072                  */
1073                 if (sp[1] == '}')
1074                         return 0;
1075
1076                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1077                 commit_list_insert((struct commit *)o, &list);
1078                 ret = get_oid_oneline(prefix, oid, list);
1079                 free(prefix);
1080                 return ret;
1081         }
1082         return 0;
1083 }
1084
1085 static int get_describe_name(const char *name, int len, struct object_id *oid)
1086 {
1087         const char *cp;
1088         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1089
1090         for (cp = name + len - 1; name + 2 <= cp; cp--) {
1091                 char ch = *cp;
1092                 if (!isxdigit(ch)) {
1093                         /* We must be looking at g in "SOMETHING-g"
1094                          * for it to be describe output.
1095                          */
1096                         if (ch == 'g' && cp[-1] == '-') {
1097                                 cp++;
1098                                 len -= cp - name;
1099                                 return get_short_oid(cp, len, oid, flags);
1100                         }
1101                 }
1102         }
1103         return -1;
1104 }
1105
1106 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags)
1107 {
1108         int ret, has_suffix;
1109         const char *cp;
1110
1111         /*
1112          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1113          */
1114         has_suffix = 0;
1115         for (cp = name + len - 1; name <= cp; cp--) {
1116                 int ch = *cp;
1117                 if ('0' <= ch && ch <= '9')
1118                         continue;
1119                 if (ch == '~' || ch == '^')
1120                         has_suffix = ch;
1121                 break;
1122         }
1123
1124         if (has_suffix) {
1125                 int num = 0;
1126                 int len1 = cp - name;
1127                 cp++;
1128                 while (cp < name + len)
1129                         num = num * 10 + *cp++ - '0';
1130                 if (!num && len1 == len - 1)
1131                         num = 1;
1132                 if (has_suffix == '^')
1133                         return get_parent(name, len1, oid, num);
1134                 /* else if (has_suffix == '~') -- goes without saying */
1135                 return get_nth_ancestor(name, len1, oid, num);
1136         }
1137
1138         ret = peel_onion(name, len, oid, lookup_flags);
1139         if (!ret)
1140                 return 0;
1141
1142         ret = get_oid_basic(name, len, oid, lookup_flags);
1143         if (!ret)
1144                 return 0;
1145
1146         /* It could be describe output that is "SOMETHING-gXXXX" */
1147         ret = get_describe_name(name, len, oid);
1148         if (!ret)
1149                 return 0;
1150
1151         return get_short_oid(name, len, oid, lookup_flags);
1152 }
1153
1154 /*
1155  * This interprets names like ':/Initial revision of "git"' by searching
1156  * through history and returning the first commit whose message starts
1157  * the given regular expression.
1158  *
1159  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1160  *
1161  * For a literal '!' character at the beginning of a pattern, you have to repeat
1162  * that, like: ':/!!foo'
1163  *
1164  * For future extension, all other sequences beginning with ':/!' are reserved.
1165  */
1166
1167 /* Remember to update object flag allocation in object.h */
1168 #define ONELINE_SEEN (1u<<20)
1169
1170 static int handle_one_ref(const char *path, const struct object_id *oid,
1171                           int flag, void *cb_data)
1172 {
1173         struct commit_list **list = cb_data;
1174         struct object *object = parse_object(the_repository, oid);
1175         if (!object)
1176                 return 0;
1177         if (object->type == OBJ_TAG) {
1178                 object = deref_tag(the_repository, object, path,
1179                                    strlen(path));
1180                 if (!object)
1181                         return 0;
1182         }
1183         if (object->type != OBJ_COMMIT)
1184                 return 0;
1185         commit_list_insert((struct commit *)object, list);
1186         return 0;
1187 }
1188
1189 static int get_oid_oneline(const char *prefix, struct object_id *oid,
1190                             struct commit_list *list)
1191 {
1192         struct commit_list *backup = NULL, *l;
1193         int found = 0;
1194         int negative = 0;
1195         regex_t regex;
1196
1197         if (prefix[0] == '!') {
1198                 prefix++;
1199
1200                 if (prefix[0] == '-') {
1201                         prefix++;
1202                         negative = 1;
1203                 } else if (prefix[0] != '!') {
1204                         return -1;
1205                 }
1206         }
1207
1208         if (regcomp(&regex, prefix, REG_EXTENDED))
1209                 return -1;
1210
1211         for (l = list; l; l = l->next) {
1212                 l->item->object.flags |= ONELINE_SEEN;
1213                 commit_list_insert(l->item, &backup);
1214         }
1215         while (list) {
1216                 const char *p, *buf;
1217                 struct commit *commit;
1218                 int matches;
1219
1220                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1221                 if (!parse_object(the_repository, &commit->object.oid))
1222                         continue;
1223                 buf = get_commit_buffer(commit, NULL);
1224                 p = strstr(buf, "\n\n");
1225                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1226                 unuse_commit_buffer(commit, buf);
1227
1228                 if (matches) {
1229                         oidcpy(oid, &commit->object.oid);
1230                         found = 1;
1231                         break;
1232                 }
1233         }
1234         regfree(&regex);
1235         free_commit_list(list);
1236         for (l = backup; l; l = l->next)
1237                 clear_commit_marks(l->item, ONELINE_SEEN);
1238         free_commit_list(backup);
1239         return found ? 0 : -1;
1240 }
1241
1242 struct grab_nth_branch_switch_cbdata {
1243         int remaining;
1244         struct strbuf buf;
1245 };
1246
1247 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1248                                   const char *email, timestamp_t timestamp, int tz,
1249                                   const char *message, void *cb_data)
1250 {
1251         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1252         const char *match = NULL, *target = NULL;
1253         size_t len;
1254
1255         if (skip_prefix(message, "checkout: moving from ", &match))
1256                 target = strstr(match, " to ");
1257
1258         if (!match || !target)
1259                 return 0;
1260         if (--(cb->remaining) == 0) {
1261                 len = target - match;
1262                 strbuf_reset(&cb->buf);
1263                 strbuf_add(&cb->buf, match, len);
1264                 return 1; /* we are done */
1265         }
1266         return 0;
1267 }
1268
1269 /*
1270  * Parse @{-N} syntax, return the number of characters parsed
1271  * if successful; otherwise signal an error with negative value.
1272  */
1273 static int interpret_nth_prior_checkout(const char *name, int namelen,
1274                                         struct strbuf *buf)
1275 {
1276         long nth;
1277         int retval;
1278         struct grab_nth_branch_switch_cbdata cb;
1279         const char *brace;
1280         char *num_end;
1281
1282         if (namelen < 4)
1283                 return -1;
1284         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1285                 return -1;
1286         brace = memchr(name, '}', namelen);
1287         if (!brace)
1288                 return -1;
1289         nth = strtol(name + 3, &num_end, 10);
1290         if (num_end != brace)
1291                 return -1;
1292         if (nth <= 0)
1293                 return -1;
1294         cb.remaining = nth;
1295         strbuf_init(&cb.buf, 20);
1296
1297         retval = 0;
1298         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1299                 strbuf_reset(buf);
1300                 strbuf_addbuf(buf, &cb.buf);
1301                 retval = brace - name + 1;
1302         }
1303
1304         strbuf_release(&cb.buf);
1305         return retval;
1306 }
1307
1308 int get_oid_mb(const char *name, struct object_id *oid)
1309 {
1310         struct commit *one, *two;
1311         struct commit_list *mbs;
1312         struct object_id oid_tmp;
1313         const char *dots;
1314         int st;
1315
1316         dots = strstr(name, "...");
1317         if (!dots)
1318                 return get_oid(name, oid);
1319         if (dots == name)
1320                 st = get_oid("HEAD", &oid_tmp);
1321         else {
1322                 struct strbuf sb;
1323                 strbuf_init(&sb, dots - name);
1324                 strbuf_add(&sb, name, dots - name);
1325                 st = get_oid_committish(sb.buf, &oid_tmp);
1326                 strbuf_release(&sb);
1327         }
1328         if (st)
1329                 return st;
1330         one = lookup_commit_reference_gently(the_repository, &oid_tmp, 0);
1331         if (!one)
1332                 return -1;
1333
1334         if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1335                 return -1;
1336         two = lookup_commit_reference_gently(the_repository, &oid_tmp, 0);
1337         if (!two)
1338                 return -1;
1339         mbs = get_merge_bases(one, two);
1340         if (!mbs || mbs->next)
1341                 st = -1;
1342         else {
1343                 st = 0;
1344                 oidcpy(oid, &mbs->item->object.oid);
1345         }
1346         free_commit_list(mbs);
1347         return st;
1348 }
1349
1350 /* parse @something syntax, when 'something' is not {.*} */
1351 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1352 {
1353         const char *next;
1354
1355         if (len || name[1] == '{')
1356                 return -1;
1357
1358         /* make sure it's a single @, or @@{.*}, not @foo */
1359         next = memchr(name + len + 1, '@', namelen - len - 1);
1360         if (next && next[1] != '{')
1361                 return -1;
1362         if (!next)
1363                 next = name + namelen;
1364         if (next != name + 1)
1365                 return -1;
1366
1367         strbuf_reset(buf);
1368         strbuf_add(buf, "HEAD", 4);
1369         return 1;
1370 }
1371
1372 static int reinterpret(const char *name, int namelen, int len,
1373                        struct strbuf *buf, unsigned allowed)
1374 {
1375         /* we have extra data, which might need further processing */
1376         struct strbuf tmp = STRBUF_INIT;
1377         int used = buf->len;
1378         int ret;
1379
1380         strbuf_add(buf, name + len, namelen - len);
1381         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1382         /* that data was not interpreted, remove our cruft */
1383         if (ret < 0) {
1384                 strbuf_setlen(buf, used);
1385                 return len;
1386         }
1387         strbuf_reset(buf);
1388         strbuf_addbuf(buf, &tmp);
1389         strbuf_release(&tmp);
1390         /* tweak for size of {-N} versus expanded ref name */
1391         return ret - used + len;
1392 }
1393
1394 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1395 {
1396         char *s = shorten_unambiguous_ref(ref, 0);
1397         strbuf_reset(buf);
1398         strbuf_addstr(buf, s);
1399         free(s);
1400 }
1401
1402 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1403 {
1404         if (!allowed)
1405                 return 1;
1406
1407         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1408             starts_with(refname, "refs/heads/"))
1409                 return 1;
1410         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1411             starts_with(refname, "refs/remotes/"))
1412                 return 1;
1413
1414         return 0;
1415 }
1416
1417 static int interpret_branch_mark(const char *name, int namelen,
1418                                  int at, struct strbuf *buf,
1419                                  int (*get_mark)(const char *, int),
1420                                  const char *(*get_data)(struct branch *,
1421                                                          struct strbuf *),
1422                                  unsigned allowed)
1423 {
1424         int len;
1425         struct branch *branch;
1426         struct strbuf err = STRBUF_INIT;
1427         const char *value;
1428
1429         len = get_mark(name + at, namelen - at);
1430         if (!len)
1431                 return -1;
1432
1433         if (memchr(name, ':', at))
1434                 return -1;
1435
1436         if (at) {
1437                 char *name_str = xmemdupz(name, at);
1438                 branch = branch_get(name_str);
1439                 free(name_str);
1440         } else
1441                 branch = branch_get(NULL);
1442
1443         value = get_data(branch, &err);
1444         if (!value)
1445                 die("%s", err.buf);
1446
1447         if (!branch_interpret_allowed(value, allowed))
1448                 return -1;
1449
1450         set_shortened_ref(buf, value);
1451         return len + at;
1452 }
1453
1454 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1455                           unsigned allowed)
1456 {
1457         char *at;
1458         const char *start;
1459         int len;
1460
1461         if (!namelen)
1462                 namelen = strlen(name);
1463
1464         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1465                 len = interpret_nth_prior_checkout(name, namelen, buf);
1466                 if (!len) {
1467                         return len; /* syntax Ok, not enough switches */
1468                 } else if (len > 0) {
1469                         if (len == namelen)
1470                                 return len; /* consumed all */
1471                         else
1472                                 return reinterpret(name, namelen, len, buf, allowed);
1473                 }
1474         }
1475
1476         for (start = name;
1477              (at = memchr(start, '@', namelen - (start - name)));
1478              start = at + 1) {
1479
1480                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1481                         len = interpret_empty_at(name, namelen, at - name, buf);
1482                         if (len > 0)
1483                                 return reinterpret(name, namelen, len, buf,
1484                                                    allowed);
1485                 }
1486
1487                 len = interpret_branch_mark(name, namelen, at - name, buf,
1488                                             upstream_mark, branch_get_upstream,
1489                                             allowed);
1490                 if (len > 0)
1491                         return len;
1492
1493                 len = interpret_branch_mark(name, namelen, at - name, buf,
1494                                             push_mark, branch_get_push,
1495                                             allowed);
1496                 if (len > 0)
1497                         return len;
1498         }
1499
1500         return -1;
1501 }
1502
1503 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1504 {
1505         int len = strlen(name);
1506         int used = interpret_branch_name(name, len, sb, allowed);
1507
1508         if (used < 0)
1509                 used = 0;
1510         strbuf_add(sb, name + used, len - used);
1511 }
1512
1513 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1514 {
1515         if (startup_info->have_repository)
1516                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1517         else
1518                 strbuf_addstr(sb, name);
1519
1520         /*
1521          * This splice must be done even if we end up rejecting the
1522          * name; builtin/branch.c::copy_or_rename_branch() still wants
1523          * to see what the name expanded to so that "branch -m" can be
1524          * used as a tool to correct earlier mistakes.
1525          */
1526         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1527
1528         if (*name == '-' ||
1529             !strcmp(sb->buf, "refs/heads/HEAD"))
1530                 return -1;
1531
1532         return check_refname_format(sb->buf, 0);
1533 }
1534
1535 /*
1536  * This is like "get_oid_basic()", except it allows "object ID expressions",
1537  * notably "xyz^" for "parent of xyz"
1538  */
1539 int get_oid(const char *name, struct object_id *oid)
1540 {
1541         struct object_context unused;
1542         return get_oid_with_context(name, 0, oid, &unused);
1543 }
1544
1545
1546 /*
1547  * Many callers know that the user meant to name a commit-ish by
1548  * syntactical positions where the object name appears.  Calling this
1549  * function allows the machinery to disambiguate shorter-than-unique
1550  * abbreviated object names between commit-ish and others.
1551  *
1552  * Note that this does NOT error out when the named object is not a
1553  * commit-ish. It is merely to give a hint to the disambiguation
1554  * machinery.
1555  */
1556 int get_oid_committish(const char *name, struct object_id *oid)
1557 {
1558         struct object_context unused;
1559         return get_oid_with_context(name, GET_OID_COMMITTISH,
1560                                     oid, &unused);
1561 }
1562
1563 int get_oid_treeish(const char *name, struct object_id *oid)
1564 {
1565         struct object_context unused;
1566         return get_oid_with_context(name, GET_OID_TREEISH,
1567                                     oid, &unused);
1568 }
1569
1570 int get_oid_commit(const char *name, struct object_id *oid)
1571 {
1572         struct object_context unused;
1573         return get_oid_with_context(name, GET_OID_COMMIT,
1574                                     oid, &unused);
1575 }
1576
1577 int get_oid_tree(const char *name, struct object_id *oid)
1578 {
1579         struct object_context unused;
1580         return get_oid_with_context(name, GET_OID_TREE,
1581                                     oid, &unused);
1582 }
1583
1584 int get_oid_blob(const char *name, struct object_id *oid)
1585 {
1586         struct object_context unused;
1587         return get_oid_with_context(name, GET_OID_BLOB,
1588                                     oid, &unused);
1589 }
1590
1591 /* Must be called only when object_name:filename doesn't exist. */
1592 static void diagnose_invalid_oid_path(const char *prefix,
1593                                       const char *filename,
1594                                       const struct object_id *tree_oid,
1595                                       const char *object_name,
1596                                       int object_name_len)
1597 {
1598         struct object_id oid;
1599         unsigned mode;
1600
1601         if (!prefix)
1602                 prefix = "";
1603
1604         if (file_exists(filename))
1605                 die("Path '%s' exists on disk, but not in '%.*s'.",
1606                     filename, object_name_len, object_name);
1607         if (is_missing_file_error(errno)) {
1608                 char *fullname = xstrfmt("%s%s", prefix, filename);
1609
1610                 if (!get_tree_entry(tree_oid, fullname, &oid, &mode)) {
1611                         die("Path '%s' exists, but not '%s'.\n"
1612                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1613                             fullname,
1614                             filename,
1615                             object_name_len, object_name,
1616                             fullname,
1617                             object_name_len, object_name,
1618                             filename);
1619                 }
1620                 die("Path '%s' does not exist in '%.*s'",
1621                     filename, object_name_len, object_name);
1622         }
1623 }
1624
1625 /* Must be called only when :stage:filename doesn't exist. */
1626 static void diagnose_invalid_index_path(int stage,
1627                                         const char *prefix,
1628                                         const char *filename)
1629 {
1630         const struct cache_entry *ce;
1631         int pos;
1632         unsigned namelen = strlen(filename);
1633         struct strbuf fullname = STRBUF_INIT;
1634
1635         if (!prefix)
1636                 prefix = "";
1637
1638         /* Wrong stage number? */
1639         pos = cache_name_pos(filename, namelen);
1640         if (pos < 0)
1641                 pos = -pos - 1;
1642         if (pos < active_nr) {
1643                 ce = active_cache[pos];
1644                 if (ce_namelen(ce) == namelen &&
1645                     !memcmp(ce->name, filename, namelen))
1646                         die("Path '%s' is in the index, but not at stage %d.\n"
1647                             "Did you mean ':%d:%s'?",
1648                             filename, stage,
1649                             ce_stage(ce), filename);
1650         }
1651
1652         /* Confusion between relative and absolute filenames? */
1653         strbuf_addstr(&fullname, prefix);
1654         strbuf_addstr(&fullname, filename);
1655         pos = cache_name_pos(fullname.buf, fullname.len);
1656         if (pos < 0)
1657                 pos = -pos - 1;
1658         if (pos < active_nr) {
1659                 ce = active_cache[pos];
1660                 if (ce_namelen(ce) == fullname.len &&
1661                     !memcmp(ce->name, fullname.buf, fullname.len))
1662                         die("Path '%s' is in the index, but not '%s'.\n"
1663                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1664                             fullname.buf, filename,
1665                             ce_stage(ce), fullname.buf,
1666                             ce_stage(ce), filename);
1667         }
1668
1669         if (file_exists(filename))
1670                 die("Path '%s' exists on disk, but not in the index.", filename);
1671         if (is_missing_file_error(errno))
1672                 die("Path '%s' does not exist (neither on disk nor in the index).",
1673                     filename);
1674
1675         strbuf_release(&fullname);
1676 }
1677
1678
1679 static char *resolve_relative_path(const char *rel)
1680 {
1681         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1682                 return NULL;
1683
1684         if (!is_inside_work_tree())
1685                 die("relative path syntax can't be used outside working tree.");
1686
1687         /* die() inside prefix_path() if resolved path is outside worktree */
1688         return prefix_path(startup_info->prefix,
1689                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1690                            rel);
1691 }
1692
1693 static int get_oid_with_context_1(const char *name,
1694                                   unsigned flags,
1695                                   const char *prefix,
1696                                   struct object_id *oid,
1697                                   struct object_context *oc)
1698 {
1699         int ret, bracket_depth;
1700         int namelen = strlen(name);
1701         const char *cp;
1702         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1703
1704         if (only_to_die)
1705                 flags |= GET_OID_QUIETLY;
1706
1707         memset(oc, 0, sizeof(*oc));
1708         oc->mode = S_IFINVALID;
1709         strbuf_init(&oc->symlink_path, 0);
1710         ret = get_oid_1(name, namelen, oid, flags);
1711         if (!ret)
1712                 return ret;
1713         /*
1714          * sha1:path --> object name of path in ent sha1
1715          * :path -> object name of absolute path in index
1716          * :./path -> object name of path relative to cwd in index
1717          * :[0-3]:path -> object name of path in index at stage
1718          * :/foo -> recent commit matching foo
1719          */
1720         if (name[0] == ':') {
1721                 int stage = 0;
1722                 const struct cache_entry *ce;
1723                 char *new_path = NULL;
1724                 int pos;
1725                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1726                         struct commit_list *list = NULL;
1727
1728                         for_each_ref(handle_one_ref, &list);
1729                         head_ref(handle_one_ref, &list);
1730                         commit_list_sort_by_date(&list);
1731                         return get_oid_oneline(name + 2, oid, list);
1732                 }
1733                 if (namelen < 3 ||
1734                     name[2] != ':' ||
1735                     name[1] < '0' || '3' < name[1])
1736                         cp = name + 1;
1737                 else {
1738                         stage = name[1] - '0';
1739                         cp = name + 3;
1740                 }
1741                 new_path = resolve_relative_path(cp);
1742                 if (!new_path) {
1743                         namelen = namelen - (cp - name);
1744                 } else {
1745                         cp = new_path;
1746                         namelen = strlen(cp);
1747                 }
1748
1749                 if (flags & GET_OID_RECORD_PATH)
1750                         oc->path = xstrdup(cp);
1751
1752                 if (!active_cache)
1753                         read_cache();
1754                 pos = cache_name_pos(cp, namelen);
1755                 if (pos < 0)
1756                         pos = -pos - 1;
1757                 while (pos < active_nr) {
1758                         ce = active_cache[pos];
1759                         if (ce_namelen(ce) != namelen ||
1760                             memcmp(ce->name, cp, namelen))
1761                                 break;
1762                         if (ce_stage(ce) == stage) {
1763                                 oidcpy(oid, &ce->oid);
1764                                 oc->mode = ce->ce_mode;
1765                                 free(new_path);
1766                                 return 0;
1767                         }
1768                         pos++;
1769                 }
1770                 if (only_to_die && name[1] && name[1] != '/')
1771                         diagnose_invalid_index_path(stage, prefix, cp);
1772                 free(new_path);
1773                 return -1;
1774         }
1775         for (cp = name, bracket_depth = 0; *cp; cp++) {
1776                 if (*cp == '{')
1777                         bracket_depth++;
1778                 else if (bracket_depth && *cp == '}')
1779                         bracket_depth--;
1780                 else if (!bracket_depth && *cp == ':')
1781                         break;
1782         }
1783         if (*cp == ':') {
1784                 struct object_id tree_oid;
1785                 int len = cp - name;
1786                 unsigned sub_flags = flags;
1787
1788                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1789                 sub_flags |= GET_OID_TREEISH;
1790
1791                 if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1792                         const char *filename = cp+1;
1793                         char *new_filename = NULL;
1794
1795                         new_filename = resolve_relative_path(filename);
1796                         if (new_filename)
1797                                 filename = new_filename;
1798                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1799                                 ret = get_tree_entry_follow_symlinks(&tree_oid,
1800                                         filename, oid, &oc->symlink_path,
1801                                         &oc->mode);
1802                         } else {
1803                                 ret = get_tree_entry(&tree_oid, filename, oid,
1804                                                      &oc->mode);
1805                                 if (ret && only_to_die) {
1806                                         diagnose_invalid_oid_path(prefix,
1807                                                                    filename,
1808                                                                    &tree_oid,
1809                                                                    name, len);
1810                                 }
1811                         }
1812                         if (flags & GET_OID_RECORD_PATH)
1813                                 oc->path = xstrdup(filename);
1814
1815                         free(new_filename);
1816                         return ret;
1817                 } else {
1818                         if (only_to_die)
1819                                 die("Invalid object name '%.*s'.", len, name);
1820                 }
1821         }
1822         return ret;
1823 }
1824
1825 /*
1826  * Call this function when you know "name" given by the end user must
1827  * name an object but it doesn't; the function _may_ die with a better
1828  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1829  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1830  * you have a chance to diagnose the error further.
1831  */
1832 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1833 {
1834         struct object_context oc;
1835         struct object_id oid;
1836         get_oid_with_context_1(name, GET_OID_ONLY_TO_DIE, prefix, &oid, &oc);
1837 }
1838
1839 int get_oid_with_context(const char *str, unsigned flags, struct object_id *oid, struct object_context *oc)
1840 {
1841         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1842                 BUG("incompatible flags for get_sha1_with_context");
1843         return get_oid_with_context_1(str, flags, NULL, oid, oc);
1844 }