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 match_sha(unsigned, const unsigned char *, const unsigned char *);
  87
  88 static void find_short_object_filename(struct disambiguate_state *ds)
  89 {
  90         struct object_directory *odb;
  91
  92         for (odb = the_repository->objects->odb;
  93              odb && !ds->ambiguous;
  94              odb = odb->next) {
  95                 int pos;
  96                 struct oid_array *loose_objects;
  97
  98                 loose_objects = odb_loose_cache(odb, &ds->bin_pfx);
  99                 pos = oid_array_lookup(loose_objects, &ds->bin_pfx);
 100                 if (pos < 0)
 101                         pos = -1 - pos;
 102                 while (!ds->ambiguous && pos < loose_objects->nr) {
 103                         const struct object_id *oid;
 104                         oid = loose_objects->oid + pos;
 105                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 106                                 break;
 107                         update_candidates(ds, oid);
 108                         pos++;
 109                 }
 110         }
 111 }
 112
 113 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 114 {
 115         do {
 116                 if (*a != *b)
 117                         return 0;
 118                 a++;
 119                 b++;
 120                 len -= 2;
 121         } while (len > 1);
 122         if (len)
 123                 if ((*a ^ *b) & 0xf0)
 124                         return 0;
 125         return 1;
 126 }
 127
 128 static void unique_in_midx(struct multi_pack_index *m,
 129                            struct disambiguate_state *ds)
 130 {
 131         uint32_t num, i, first = 0;
 132         const struct object_id *current = NULL;
 133         num = m->num_objects;
 134
 135         if (!num)
 136                 return;
 137
 138         bsearch_midx(&ds->bin_pfx, m, &first);
 139
 140         /*
 141          * At this point, "first" is the location of the lowest object
 142          * with an object name that could match "bin_pfx".  See if we have
 143          * 0, 1 or more objects that actually match(es).
 144          */
 145         for (i = first; i < num && !ds->ambiguous; i++) {
 146                 struct object_id oid;
 147                 current = nth_midxed_object_oid(&oid, m, i);
 148                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 149                         break;
 150                 update_candidates(ds, current);
 151         }
 152 }
 153
 154 static void unique_in_pack(struct packed_git *p,
 155                            struct disambiguate_state *ds)
 156 {
 157         uint32_t num, i, first = 0;
 158         const struct object_id *current = NULL;
 159
 160         if (open_pack_index(p) || !p->num_objects)
 161                 return;
 162
 163         num = p->num_objects;
 164         bsearch_pack(&ds->bin_pfx, p, &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_packed_object_oid(&oid, p, 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 find_short_packed_object(struct disambiguate_state *ds)
 181 {
 182         struct multi_pack_index *m;
 183         struct packed_git *p;
 184
 185         for (m = get_multi_pack_index(the_repository); m && !ds->ambiguous;
 186              m = m->next)
 187                 unique_in_midx(m, ds);
 188         for (p = get_packed_git(the_repository); p && !ds->ambiguous;
 189              p = p->next)
 190                 unique_in_pack(p, ds);
 191 }
 192
 193 static int finish_object_disambiguation(struct disambiguate_state *ds,
 194                                         struct object_id *oid)
 195 {
 196         if (ds->ambiguous)
 197                 return SHORT_NAME_AMBIGUOUS;
 198
 199         if (!ds->candidate_exists)
 200                 return MISSING_OBJECT;
 201
 202         if (!ds->candidate_checked)
 203                 /*
 204                  * If this is the only candidate, there is no point
 205                  * calling the disambiguation hint callback.
 206                  *
 207                  * On the other hand, if the current candidate
 208                  * replaced an earlier candidate that did _not_ pass
 209                  * the disambiguation hint callback, then we do have
 210                  * more than one objects that match the short name
 211                  * given, so we should make sure this one matches;
 212                  * otherwise, if we discovered this one and the one
 213                  * that we previously discarded in the reverse order,
 214                  * we would end up showing different results in the
 215                  * same repository!
 216                  */
 217                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 218                                     ds->fn(&ds->candidate, ds->cb_data));
 219
 220         if (!ds->candidate_ok)
 221                 return SHORT_NAME_AMBIGUOUS;
 222
 223         oidcpy(oid, &ds->candidate);
 224         return 0;
 225 }
 226
 227 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 228 {
 229         int kind = oid_object_info(the_repository, oid, NULL);
 230         return kind == OBJ_COMMIT;
 231 }
 232
 233 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 234 {
 235         struct object *obj;
 236         int kind;
 237
 238         kind = oid_object_info(the_repository, oid, NULL);
 239         if (kind == OBJ_COMMIT)
 240                 return 1;
 241         if (kind != OBJ_TAG)
 242                 return 0;
 243
 244         /* We need to do this the hard way... */
 245         obj = deref_tag(the_repository, parse_object(the_repository, oid),
 246                         NULL, 0);
 247         if (obj && obj->type == OBJ_COMMIT)
 248                 return 1;
 249         return 0;
 250 }
 251
 252 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 253 {
 254         int kind = oid_object_info(the_repository, oid, NULL);
 255         return kind == OBJ_TREE;
 256 }
 257
 258 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 259 {
 260         struct object *obj;
 261         int kind;
 262
 263         kind = oid_object_info(the_repository, oid, NULL);
 264         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 265                 return 1;
 266         if (kind != OBJ_TAG)
 267                 return 0;
 268
 269         /* We need to do this the hard way... */
 270         obj = deref_tag(the_repository, parse_object(the_repository, oid),
 271                         NULL, 0);
 272         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 273                 return 1;
 274         return 0;
 275 }
 276
 277 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 278 {
 279         int kind = oid_object_info(the_repository, oid, NULL);
 280         return kind == OBJ_BLOB;
 281 }
 282
 283 static disambiguate_hint_fn default_disambiguate_hint;
 284
 285 int set_disambiguate_hint_config(const char *var, const char *value)
 286 {
 287         static const struct {
 288                 const char *name;
 289                 disambiguate_hint_fn fn;
 290         } hints[] = {
 291                 { "none", NULL },
 292                 { "commit", disambiguate_commit_only },
 293                 { "committish", disambiguate_committish_only },
 294                 { "tree", disambiguate_tree_only },
 295                 { "treeish", disambiguate_treeish_only },
 296                 { "blob", disambiguate_blob_only }
 297         };
 298         int i;
 299
 300         if (!value)
 301                 return config_error_nonbool(var);
 302
 303         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 304                 if (!strcasecmp(value, hints[i].name)) {
 305                         default_disambiguate_hint = hints[i].fn;
 306                         return 0;
 307                 }
 308         }
 309
 310         return error("unknown hint type for '%s': %s", var, value);
 311 }
 312
 313 static int init_object_disambiguation(const char *name, int len,
 314                                       struct disambiguate_state *ds)
 315 {
 316         int i;
 317
 318         if (len < MINIMUM_ABBREV || len > the_hash_algo->hexsz)
 319                 return -1;
 320
 321         memset(ds, 0, sizeof(*ds));
 322
 323         for (i = 0; i < len ;i++) {
 324                 unsigned char c = name[i];
 325                 unsigned char val;
 326                 if (c >= '0' && c <= '9')
 327                         val = c - '0';
 328                 else if (c >= 'a' && c <= 'f')
 329                         val = c - 'a' + 10;
 330                 else if (c >= 'A' && c <='F') {
 331                         val = c - 'A' + 10;
 332                         c -= 'A' - 'a';
 333                 }
 334                 else
 335                         return -1;
 336                 ds->hex_pfx[i] = c;
 337                 if (!(i & 1))
 338                         val <<= 4;
 339                 ds->bin_pfx.hash[i >> 1] |= val;
 340         }
 341
 342         ds->len = len;
 343         ds->hex_pfx[len] = '\0';
 344         prepare_alt_odb(the_repository);
 345         return 0;
 346 }
 347
 348 static int show_ambiguous_object(const struct object_id *oid, void *data)
 349 {
 350         const struct disambiguate_state *ds = data;
 351         struct strbuf desc = STRBUF_INIT;
 352         int type;
 353
 354         if (ds->fn && !ds->fn(oid, ds->cb_data))
 355                 return 0;
 356
 357         type = oid_object_info(the_repository, oid, NULL);
 358         if (type == OBJ_COMMIT) {
 359                 struct commit *commit = lookup_commit(the_repository, oid);
 360                 if (commit) {
 361                         struct pretty_print_context pp = {0};
 362                         pp.date_mode.type = DATE_SHORT;
 363                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 364                 }
 365         } else if (type == OBJ_TAG) {
 366                 struct tag *tag = lookup_tag(the_repository, oid);
 367                 if (!parse_tag(tag) && tag->tag)
 368                         strbuf_addf(&desc, " %s", tag->tag);
 369         }
 370
 371         advise("  %s %s%s",
 372                find_unique_abbrev(oid, DEFAULT_ABBREV),
 373                type_name(type) ? type_name(type) : "unknown type",
 374                desc.buf);
 375
 376         strbuf_release(&desc);
 377         return 0;
 378 }
 379
 380 static int collect_ambiguous(const struct object_id *oid, void *data)
 381 {
 382         oid_array_append(data, oid);
 383         return 0;
 384 }
 385
 386 static int sort_ambiguous(const void *a, const void *b)
 387 {
 388         int a_type = oid_object_info(the_repository, a, NULL);
 389         int b_type = oid_object_info(the_repository, b, NULL);
 390         int a_type_sort;
 391         int b_type_sort;
 392
 393         /*
 394          * Sorts by hash within the same object type, just as
 395          * oid_array_for_each_unique() would do.
 396          */
 397         if (a_type == b_type)
 398                 return oidcmp(a, b);
 399
 400         /*
 401          * Between object types show tags, then commits, and finally
 402          * trees and blobs.
 403          *
 404          * The object_type enum is commit, tree, blob, tag, but we
 405          * want tag, commit, tree blob. Cleverly (perhaps too
 406          * cleverly) do that with modulus, since the enum assigns 1 to
 407          * commit, so tag becomes 0.
 408          */
 409         a_type_sort = a_type % 4;
 410         b_type_sort = b_type % 4;
 411         return a_type_sort > b_type_sort ? 1 : -1;
 412 }
 413
 414 static enum get_oid_result get_short_oid(const char *name, int len,
 415                                          struct object_id *oid,
 416                                          unsigned flags)
 417 {
 418         int status;
 419         struct disambiguate_state ds;
 420         int quietly = !!(flags & GET_OID_QUIETLY);
 421
 422         if (init_object_disambiguation(name, len, &ds) < 0)
 423                 return -1;
 424
 425         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 426                 BUG("multiple get_short_oid disambiguator flags");
 427
 428         if (flags & GET_OID_COMMIT)
 429                 ds.fn = disambiguate_commit_only;
 430         else if (flags & GET_OID_COMMITTISH)
 431                 ds.fn = disambiguate_committish_only;
 432         else if (flags & GET_OID_TREE)
 433                 ds.fn = disambiguate_tree_only;
 434         else if (flags & GET_OID_TREEISH)
 435                 ds.fn = disambiguate_treeish_only;
 436         else if (flags & GET_OID_BLOB)
 437                 ds.fn = disambiguate_blob_only;
 438         else
 439                 ds.fn = default_disambiguate_hint;
 440
 441         find_short_object_filename(&ds);
 442         find_short_packed_object(&ds);
 443         status = finish_object_disambiguation(&ds, oid);
 444
 445         /*
 446          * If we didn't find it, do the usual reprepare() slow-path,
 447          * since the object may have recently been added to the repository
 448          * or migrated from loose to packed.
 449          */
 450         if (status == MISSING_OBJECT) {
 451                 reprepare_packed_git(the_repository);
 452                 find_short_object_filename(&ds);
 453                 find_short_packed_object(&ds);
 454                 status = finish_object_disambiguation(&ds, oid);
 455         }
 456
 457         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 458                 struct oid_array collect = OID_ARRAY_INIT;
 459
 460                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 461
 462                 /*
 463                  * We may still have ambiguity if we simply saw a series of
 464                  * candidates that did not satisfy our hint function. In
 465                  * that case, we still want to show them, so disable the hint
 466                  * function entirely.
 467                  */
 468                 if (!ds.ambiguous)
 469                         ds.fn = NULL;
 470
 471                 advise(_("The candidates are:"));
 472                 for_each_abbrev(ds.hex_pfx, collect_ambiguous, &collect);
 473                 QSORT(collect.oid, collect.nr, sort_ambiguous);
 474
 475                 if (oid_array_for_each(&collect, show_ambiguous_object, &ds))
 476                         BUG("show_ambiguous_object shouldn't return non-zero");
 477                 oid_array_clear(&collect);
 478         }
 479
 480         return status;
 481 }
 482
 483 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 484 {
 485         struct oid_array collect = OID_ARRAY_INIT;
 486         struct disambiguate_state ds;
 487         int ret;
 488
 489         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 490                 return -1;
 491
 492         ds.always_call_fn = 1;
 493         ds.fn = collect_ambiguous;
 494         ds.cb_data = &collect;
 495         find_short_object_filename(&ds);
 496         find_short_packed_object(&ds);
 497
 498         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 499         oid_array_clear(&collect);
 500         return ret;
 501 }
 502
 503 /*
 504  * Return the slot of the most-significant bit set in "val". There are various
 505  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 506  * probably not a big deal here.
 507  */
 508 static unsigned msb(unsigned long val)
 509 {
 510         unsigned r = 0;
 511         while (val >>= 1)
 512                 r++;
 513         return r;
 514 }
 515
 516 struct min_abbrev_data {
 517         unsigned int init_len;
 518         unsigned int cur_len;
 519         char *hex;
 520         const struct object_id *oid;
 521 };
 522
 523 static inline char get_hex_char_from_oid(const struct object_id *oid,
 524                                          unsigned int pos)
 525 {
 526         static const char hex[] = "0123456789abcdef";
 527
 528         if ((pos & 1) == 0)
 529                 return hex[oid->hash[pos >> 1] >> 4];
 530         else
 531                 return hex[oid->hash[pos >> 1] & 0xf];
 532 }
 533
 534 static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
 535 {
 536         struct min_abbrev_data *mad = cb_data;
 537
 538         unsigned int i = mad->init_len;
 539         while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
 540                 i++;
 541
 542         if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
 543                 mad->cur_len = i + 1;
 544
 545         return 0;
 546 }
 547
 548 static void find_abbrev_len_for_midx(struct multi_pack_index *m,
 549                                      struct min_abbrev_data *mad)
 550 {
 551         int match = 0;
 552         uint32_t num, first = 0;
 553         struct object_id oid;
 554         const struct object_id *mad_oid;
 555
 556         if (!m->num_objects)
 557                 return;
 558
 559         num = m->num_objects;
 560         mad_oid = mad->oid;
 561         match = bsearch_midx(mad_oid, m, &first);
 562
 563         /*
 564          * first is now the position in the packfile where we would insert
 565          * mad->hash if it does not exist (or the position of mad->hash if
 566          * it does exist). Hence, we consider a maximum of two objects
 567          * nearby for the abbreviation length.
 568          */
 569         mad->init_len = 0;
 570         if (!match) {
 571                 if (nth_midxed_object_oid(&oid, m, first))
 572                         extend_abbrev_len(&oid, mad);
 573         } else if (first < num - 1) {
 574                 if (nth_midxed_object_oid(&oid, m, first + 1))
 575                         extend_abbrev_len(&oid, mad);
 576         }
 577         if (first > 0) {
 578                 if (nth_midxed_object_oid(&oid, m, first - 1))
 579                         extend_abbrev_len(&oid, mad);
 580         }
 581         mad->init_len = mad->cur_len;
 582 }
 583
 584 static void find_abbrev_len_for_pack(struct packed_git *p,
 585                                      struct min_abbrev_data *mad)
 586 {
 587         int match = 0;
 588         uint32_t num, first = 0;
 589         struct object_id oid;
 590         const struct object_id *mad_oid;
 591
 592         if (open_pack_index(p) || !p->num_objects)
 593                 return;
 594
 595         num = p->num_objects;
 596         mad_oid = mad->oid;
 597         match = bsearch_pack(mad_oid, p, &first);
 598
 599         /*
 600          * first is now the position in the packfile where we would insert
 601          * mad->hash if it does not exist (or the position of mad->hash if
 602          * it does exist). Hence, we consider a maximum of two objects
 603          * nearby for the abbreviation length.
 604          */
 605         mad->init_len = 0;
 606         if (!match) {
 607                 if (nth_packed_object_oid(&oid, p, first))
 608                         extend_abbrev_len(&oid, mad);
 609         } else if (first < num - 1) {
 610                 if (nth_packed_object_oid(&oid, p, first + 1))
 611                         extend_abbrev_len(&oid, mad);
 612         }
 613         if (first > 0) {
 614                 if (nth_packed_object_oid(&oid, p, first - 1))
 615                         extend_abbrev_len(&oid, mad);
 616         }
 617         mad->init_len = mad->cur_len;
 618 }
 619
 620 static void find_abbrev_len_packed(struct min_abbrev_data *mad)
 621 {
 622         struct multi_pack_index *m;
 623         struct packed_git *p;
 624
 625         for (m = get_multi_pack_index(the_repository); m; m = m->next)
 626                 find_abbrev_len_for_midx(m, mad);
 627         for (p = get_packed_git(the_repository); p; p = p->next)
 628                 find_abbrev_len_for_pack(p, mad);
 629 }
 630
 631 int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 632 {
 633         struct disambiguate_state ds;
 634         struct min_abbrev_data mad;
 635         struct object_id oid_ret;
 636         const unsigned hexsz = the_hash_algo->hexsz;
 637
 638         if (len < 0) {
 639                 unsigned long count = approximate_object_count();
 640                 /*
 641                  * Add one because the MSB only tells us the highest bit set,
 642                  * not including the value of all the _other_ bits (so "15"
 643                  * is only one off of 2^4, but the MSB is the 3rd bit.
 644                  */
 645                 len = msb(count) + 1;
 646                 /*
 647                  * We now know we have on the order of 2^len objects, which
 648                  * expects a collision at 2^(len/2). But we also care about hex
 649                  * chars, not bits, and there are 4 bits per hex. So all
 650                  * together we need to divide by 2 and round up.
 651                  */
 652                 len = DIV_ROUND_UP(len, 2);
 653                 /*
 654                  * For very small repos, we stick with our regular fallback.
 655                  */
 656                 if (len < FALLBACK_DEFAULT_ABBREV)
 657                         len = FALLBACK_DEFAULT_ABBREV;
 658         }
 659
 660         oid_to_hex_r(hex, oid);
 661         if (len == hexsz || !len)
 662                 return hexsz;
 663
 664         mad.init_len = len;
 665         mad.cur_len = len;
 666         mad.hex = hex;
 667         mad.oid = oid;
 668
 669         find_abbrev_len_packed(&mad);
 670
 671         if (init_object_disambiguation(hex, mad.cur_len, &ds) < 0)
 672                 return -1;
 673
 674         ds.fn = extend_abbrev_len;
 675         ds.always_call_fn = 1;
 676         ds.cb_data = (void *)&mad;
 677
 678         find_short_object_filename(&ds);
 679         (void)finish_object_disambiguation(&ds, &oid_ret);
 680
 681         hex[mad.cur_len] = 0;
 682         return mad.cur_len;
 683 }
 684
 685 const char *find_unique_abbrev(const struct object_id *oid, int len)
 686 {
 687         static int bufno;
 688         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 689         char *hex = hexbuffer[bufno];
 690         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 691         find_unique_abbrev_r(hex, oid, len);
 692         return hex;
 693 }
 694
 695 static int ambiguous_path(const char *path, int len)
 696 {
 697         int slash = 1;
 698         int cnt;
 699
 700         for (cnt = 0; cnt < len; cnt++) {
 701                 switch (*path++) {
 702                 case '\0':
 703                         break;
 704                 case '/':
 705                         if (slash)
 706                                 break;
 707                         slash = 1;
 708                         continue;
 709                 case '.':
 710                         continue;
 711                 default:
 712                         slash = 0;
 713                         continue;
 714                 }
 715                 break;
 716         }
 717         return slash;
 718 }
 719
 720 static inline int at_mark(const char *string, int len,
 721                           const char **suffix, int nr)
 722 {
 723         int i;
 724
 725         for (i = 0; i < nr; i++) {
 726                 int suffix_len = strlen(suffix[i]);
 727                 if (suffix_len <= len
 728                     && !strncasecmp(string, suffix[i], suffix_len))
 729                         return suffix_len;
 730         }
 731         return 0;
 732 }
 733
 734 static inline int upstream_mark(const char *string, int len)
 735 {
 736         const char *suffix[] = { "@{upstream}", "@{u}" };
 737         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 738 }
 739
 740 static inline int push_mark(const char *string, int len)
 741 {
 742         const char *suffix[] = { "@{push}" };
 743         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 744 }
 745
 746 static enum get_oid_result get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 747 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 748
 749 static int get_oid_basic(const char *str, int len, struct object_id *oid,
 750                           unsigned int flags)
 751 {
 752         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 753         static const char *object_name_msg = N_(
 754         "Git normally never creates a ref that ends with 40 hex characters\n"
 755         "because it will be ignored when you just specify 40-hex. These refs\n"
 756         "may be created by mistake. For example,\n"
 757         "\n"
 758         "  git checkout -b $br $(git rev-parse ...)\n"
 759         "\n"
 760         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 761         "examine these refs and maybe delete them. Turn this message off by\n"
 762         "running \"git config advice.objectNameWarning false\"");
 763         struct object_id tmp_oid;
 764         char *real_ref = NULL;
 765         int refs_found = 0;
 766         int at, reflog_len, nth_prior = 0;
 767
 768         if (len == the_hash_algo->hexsz && !get_oid_hex(str, oid)) {
 769                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 770                         refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
 771                         if (refs_found > 0) {
 772                                 warning(warn_msg, len, str);
 773                                 if (advice_object_name_warning)
 774                                         fprintf(stderr, "%s\n", _(object_name_msg));
 775                         }
 776                         free(real_ref);
 777                 }
 778                 return 0;
 779         }
 780
 781         /* basic@{time or number or -number} format to query ref-log */
 782         reflog_len = at = 0;
 783         if (len && str[len-1] == '}') {
 784                 for (at = len-4; at >= 0; at--) {
 785                         if (str[at] == '@' && str[at+1] == '{') {
 786                                 if (str[at+2] == '-') {
 787                                         if (at != 0)
 788                                                 /* @{-N} not at start */
 789                                                 return -1;
 790                                         nth_prior = 1;
 791                                         continue;
 792                                 }
 793                                 if (!upstream_mark(str + at, len - at) &&
 794                                     !push_mark(str + at, len - at)) {
 795                                         reflog_len = (len-1) - (at+2);
 796                                         len = at;
 797                                 }
 798                                 break;
 799                         }
 800                 }
 801         }
 802
 803         /* Accept only unambiguous ref paths. */
 804         if (len && ambiguous_path(str, len))
 805                 return -1;
 806
 807         if (nth_prior) {
 808                 struct strbuf buf = STRBUF_INIT;
 809                 int detached;
 810
 811                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 812                         detached = (buf.len == the_hash_algo->hexsz && !get_oid_hex(buf.buf, oid));
 813                         strbuf_release(&buf);
 814                         if (detached)
 815                                 return 0;
 816                 }
 817         }
 818
 819         if (!len && reflog_len)
 820                 /* allow "@{...}" to mean the current branch reflog */
 821                 refs_found = dwim_ref("HEAD", 4, oid, &real_ref);
 822         else if (reflog_len)
 823                 refs_found = dwim_log(str, len, oid, &real_ref);
 824         else
 825                 refs_found = dwim_ref(str, len, oid, &real_ref);
 826
 827         if (!refs_found)
 828                 return -1;
 829
 830         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 831             (refs_found > 1 ||
 832              !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
 833                 warning(warn_msg, len, str);
 834
 835         if (reflog_len) {
 836                 int nth, i;
 837                 timestamp_t at_time;
 838                 timestamp_t co_time;
 839                 int co_tz, co_cnt;
 840
 841                 /* Is it asking for N-th entry, or approxidate? */
 842                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 843                         char ch = str[at+2+i];
 844                         if ('0' <= ch && ch <= '9')
 845                                 nth = nth * 10 + ch - '0';
 846                         else
 847                                 nth = -1;
 848                 }
 849                 if (100000000 <= nth) {
 850                         at_time = nth;
 851                         nth = -1;
 852                 } else if (0 <= nth)
 853                         at_time = 0;
 854                 else {
 855                         int errors = 0;
 856                         char *tmp = xstrndup(str + at + 2, reflog_len);
 857                         at_time = approxidate_careful(tmp, &errors);
 858                         free(tmp);
 859                         if (errors) {
 860                                 free(real_ref);
 861                                 return -1;
 862                         }
 863                 }
 864                 if (read_ref_at(real_ref, flags, at_time, nth, oid, NULL,
 865                                 &co_time, &co_tz, &co_cnt)) {
 866                         if (!len) {
 867                                 if (starts_with(real_ref, "refs/heads/")) {
 868                                         str = real_ref + 11;
 869                                         len = strlen(real_ref + 11);
 870                                 } else {
 871                                         /* detached HEAD */
 872                                         str = "HEAD";
 873                                         len = 4;
 874                                 }
 875                         }
 876                         if (at_time) {
 877                                 if (!(flags & GET_OID_QUIETLY)) {
 878                                         warning("Log for '%.*s' only goes "
 879                                                 "back to %s.", len, str,
 880                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 881                                 }
 882                         } else {
 883                                 if (flags & GET_OID_QUIETLY) {
 884                                         exit(128);
 885                                 }
 886                                 die("Log for '%.*s' only has %d entries.",
 887                                     len, str, co_cnt);
 888                         }
 889                 }
 890         }
 891
 892         free(real_ref);
 893         return 0;
 894 }
 895
 896 static enum get_oid_result get_parent(const char *name, int len,
 897                                       struct object_id *result, int idx)
 898 {
 899         struct object_id oid;
 900         enum get_oid_result ret = get_oid_1(name, len, &oid,
 901                                             GET_OID_COMMITTISH);
 902         struct commit *commit;
 903         struct commit_list *p;
 904
 905         if (ret)
 906                 return ret;
 907         commit = lookup_commit_reference(the_repository, &oid);
 908         if (parse_commit(commit))
 909                 return MISSING_OBJECT;
 910         if (!idx) {
 911                 oidcpy(result, &commit->object.oid);
 912                 return FOUND;
 913         }
 914         p = commit->parents;
 915         while (p) {
 916                 if (!--idx) {
 917                         oidcpy(result, &p->item->object.oid);
 918                         return FOUND;
 919                 }
 920                 p = p->next;
 921         }
 922         return MISSING_OBJECT;
 923 }
 924
 925 static enum get_oid_result get_nth_ancestor(const char *name, int len,
 926                                             struct object_id *result,
 927                                             int generation)
 928 {
 929         struct object_id oid;
 930         struct commit *commit;
 931         int ret;
 932
 933         ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 934         if (ret)
 935                 return ret;
 936         commit = lookup_commit_reference(the_repository, &oid);
 937         if (!commit)
 938                 return MISSING_OBJECT;
 939
 940         while (generation--) {
 941                 if (parse_commit(commit) || !commit->parents)
 942                         return MISSING_OBJECT;
 943                 commit = commit->parents->item;
 944         }
 945         oidcpy(result, &commit->object.oid);
 946         return FOUND;
 947 }
 948
 949 struct object *peel_to_type(const char *name, int namelen,
 950                             struct object *o, enum object_type expected_type)
 951 {
 952         if (name && !namelen)
 953                 namelen = strlen(name);
 954         while (1) {
 955                 if (!o || (!o->parsed && !parse_object(the_repository, &o->oid)))
 956                         return NULL;
 957                 if (expected_type == OBJ_ANY || o->type == expected_type)
 958                         return o;
 959                 if (o->type == OBJ_TAG)
 960                         o = ((struct tag*) o)->tagged;
 961                 else if (o->type == OBJ_COMMIT)
 962                         o = &(get_commit_tree(((struct commit *)o))->object);
 963                 else {
 964                         if (name)
 965                                 error("%.*s: expected %s type, but the object "
 966                                       "dereferences to %s type",
 967                                       namelen, name, type_name(expected_type),
 968                                       type_name(o->type));
 969                         return NULL;
 970                 }
 971         }
 972 }
 973
 974 static int peel_onion(const char *name, int len, struct object_id *oid,
 975                       unsigned lookup_flags)
 976 {
 977         struct object_id outer;
 978         const char *sp;
 979         unsigned int expected_type = 0;
 980         struct object *o;
 981
 982         /*
 983          * "ref^{type}" dereferences ref repeatedly until you cannot
 984          * dereference anymore, or you get an object of given type,
 985          * whichever comes first.  "ref^{}" means just dereference
 986          * tags until you get a non-tag.  "ref^0" is a shorthand for
 987          * "ref^{commit}".  "commit^{tree}" could be used to find the
 988          * top-level tree of the given commit.
 989          */
 990         if (len < 4 || name[len-1] != '}')
 991                 return -1;
 992
 993         for (sp = name + len - 1; name <= sp; sp--) {
 994                 int ch = *sp;
 995                 if (ch == '{' && name < sp && sp[-1] == '^')
 996                         break;
 997         }
 998         if (sp <= name)
 999                 return -1;
1000
1001         sp++; /* beginning of type name, or closing brace for empty */
1002         if (starts_with(sp, "commit}"))
1003                 expected_type = OBJ_COMMIT;
1004         else if (starts_with(sp, "tag}"))
1005                 expected_type = OBJ_TAG;
1006         else if (starts_with(sp, "tree}"))
1007                 expected_type = OBJ_TREE;
1008         else if (starts_with(sp, "blob}"))
1009                 expected_type = OBJ_BLOB;
1010         else if (starts_with(sp, "object}"))
1011                 expected_type = OBJ_ANY;
1012         else if (sp[0] == '}')
1013                 expected_type = OBJ_NONE;
1014         else if (sp[0] == '/')
1015                 expected_type = OBJ_COMMIT;
1016         else
1017                 return -1;
1018
1019         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
1020         if (expected_type == OBJ_COMMIT)
1021                 lookup_flags |= GET_OID_COMMITTISH;
1022         else if (expected_type == OBJ_TREE)
1023                 lookup_flags |= GET_OID_TREEISH;
1024
1025         if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
1026                 return -1;
1027
1028         o = parse_object(the_repository, &outer);
1029         if (!o)
1030                 return -1;
1031         if (!expected_type) {
1032                 o = deref_tag(the_repository, o, name, sp - name - 2);
1033                 if (!o || (!o->parsed && !parse_object(the_repository, &o->oid)))
1034                         return -1;
1035                 oidcpy(oid, &o->oid);
1036                 return 0;
1037         }
1038
1039         /*
1040          * At this point, the syntax look correct, so
1041          * if we do not get the needed object, we should
1042          * barf.
1043          */
1044         o = peel_to_type(name, len, o, expected_type);
1045         if (!o)
1046                 return -1;
1047
1048         oidcpy(oid, &o->oid);
1049         if (sp[0] == '/') {
1050                 /* "$commit^{/foo}" */
1051                 char *prefix;
1052                 int ret;
1053                 struct commit_list *list = NULL;
1054
1055                 /*
1056                  * $commit^{/}. Some regex implementation may reject.
1057                  * We don't need regex anyway. '' pattern always matches.
1058                  */
1059                 if (sp[1] == '}')
1060                         return 0;
1061
1062                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1063                 commit_list_insert((struct commit *)o, &list);
1064                 ret = get_oid_oneline(prefix, oid, list);
1065                 free(prefix);
1066                 return ret;
1067         }
1068         return 0;
1069 }
1070
1071 static int get_describe_name(const char *name, int len, struct object_id *oid)
1072 {
1073         const char *cp;
1074         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1075
1076         for (cp = name + len - 1; name + 2 <= cp; cp--) {
1077                 char ch = *cp;
1078                 if (!isxdigit(ch)) {
1079                         /* We must be looking at g in "SOMETHING-g"
1080                          * for it to be describe output.
1081                          */
1082                         if (ch == 'g' && cp[-1] == '-') {
1083                                 cp++;
1084                                 len -= cp - name;
1085                                 return get_short_oid(cp, len, oid, flags);
1086                         }
1087                 }
1088         }
1089         return -1;
1090 }
1091
1092 static enum get_oid_result get_oid_1(const char *name, int len,
1093                                      struct object_id *oid,
1094                                      unsigned lookup_flags)
1095 {
1096         int ret, has_suffix;
1097         const char *cp;
1098
1099         /*
1100          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1101          */
1102         has_suffix = 0;
1103         for (cp = name + len - 1; name <= cp; cp--) {
1104                 int ch = *cp;
1105                 if ('0' <= ch && ch <= '9')
1106                         continue;
1107                 if (ch == '~' || ch == '^')
1108                         has_suffix = ch;
1109                 break;
1110         }
1111
1112         if (has_suffix) {
1113                 int num = 0;
1114                 int len1 = cp - name;
1115                 cp++;
1116                 while (cp < name + len)
1117                         num = num * 10 + *cp++ - '0';
1118                 if (!num && len1 == len - 1)
1119                         num = 1;
1120                 if (has_suffix == '^')
1121                         return get_parent(name, len1, oid, num);
1122                 /* else if (has_suffix == '~') -- goes without saying */
1123                 return get_nth_ancestor(name, len1, oid, num);
1124         }
1125
1126         ret = peel_onion(name, len, oid, lookup_flags);
1127         if (!ret)
1128                 return FOUND;
1129
1130         ret = get_oid_basic(name, len, oid, lookup_flags);
1131         if (!ret)
1132                 return FOUND;
1133
1134         /* It could be describe output that is "SOMETHING-gXXXX" */
1135         ret = get_describe_name(name, len, oid);
1136         if (!ret)
1137                 return FOUND;
1138
1139         return get_short_oid(name, len, oid, lookup_flags);
1140 }
1141
1142 /*
1143  * This interprets names like ':/Initial revision of "git"' by searching
1144  * through history and returning the first commit whose message starts
1145  * the given regular expression.
1146  *
1147  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1148  *
1149  * For a literal '!' character at the beginning of a pattern, you have to repeat
1150  * that, like: ':/!!foo'
1151  *
1152  * For future extension, all other sequences beginning with ':/!' are reserved.
1153  */
1154
1155 /* Remember to update object flag allocation in object.h */
1156 #define ONELINE_SEEN (1u<<20)
1157
1158 static int handle_one_ref(const char *path, const struct object_id *oid,
1159                           int flag, void *cb_data)
1160 {
1161         struct commit_list **list = cb_data;
1162         struct object *object = parse_object(the_repository, oid);
1163         if (!object)
1164                 return 0;
1165         if (object->type == OBJ_TAG) {
1166                 object = deref_tag(the_repository, object, path,
1167                                    strlen(path));
1168                 if (!object)
1169                         return 0;
1170         }
1171         if (object->type != OBJ_COMMIT)
1172                 return 0;
1173         commit_list_insert((struct commit *)object, list);
1174         return 0;
1175 }
1176
1177 static int get_oid_oneline(const char *prefix, struct object_id *oid,
1178                             struct commit_list *list)
1179 {
1180         struct commit_list *backup = NULL, *l;
1181         int found = 0;
1182         int negative = 0;
1183         regex_t regex;
1184
1185         if (prefix[0] == '!') {
1186                 prefix++;
1187
1188                 if (prefix[0] == '-') {
1189                         prefix++;
1190                         negative = 1;
1191                 } else if (prefix[0] != '!') {
1192                         return -1;
1193                 }
1194         }
1195
1196         if (regcomp(&regex, prefix, REG_EXTENDED))
1197                 return -1;
1198
1199         for (l = list; l; l = l->next) {
1200                 l->item->object.flags |= ONELINE_SEEN;
1201                 commit_list_insert(l->item, &backup);
1202         }
1203         while (list) {
1204                 const char *p, *buf;
1205                 struct commit *commit;
1206                 int matches;
1207
1208                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1209                 if (!parse_object(the_repository, &commit->object.oid))
1210                         continue;
1211                 buf = get_commit_buffer(commit, NULL);
1212                 p = strstr(buf, "\n\n");
1213                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1214                 unuse_commit_buffer(commit, buf);
1215
1216                 if (matches) {
1217                         oidcpy(oid, &commit->object.oid);
1218                         found = 1;
1219                         break;
1220                 }
1221         }
1222         regfree(&regex);
1223         free_commit_list(list);
1224         for (l = backup; l; l = l->next)
1225                 clear_commit_marks(l->item, ONELINE_SEEN);
1226         free_commit_list(backup);
1227         return found ? 0 : -1;
1228 }
1229
1230 struct grab_nth_branch_switch_cbdata {
1231         int remaining;
1232         struct strbuf buf;
1233 };
1234
1235 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1236                                   const char *email, timestamp_t timestamp, int tz,
1237                                   const char *message, void *cb_data)
1238 {
1239         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1240         const char *match = NULL, *target = NULL;
1241         size_t len;
1242
1243         if (skip_prefix(message, "checkout: moving from ", &match))
1244                 target = strstr(match, " to ");
1245
1246         if (!match || !target)
1247                 return 0;
1248         if (--(cb->remaining) == 0) {
1249                 len = target - match;
1250                 strbuf_reset(&cb->buf);
1251                 strbuf_add(&cb->buf, match, len);
1252                 return 1; /* we are done */
1253         }
1254         return 0;
1255 }
1256
1257 /*
1258  * Parse @{-N} syntax, return the number of characters parsed
1259  * if successful; otherwise signal an error with negative value.
1260  */
1261 static int interpret_nth_prior_checkout(const char *name, int namelen,
1262                                         struct strbuf *buf)
1263 {
1264         long nth;
1265         int retval;
1266         struct grab_nth_branch_switch_cbdata cb;
1267         const char *brace;
1268         char *num_end;
1269
1270         if (namelen < 4)
1271                 return -1;
1272         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1273                 return -1;
1274         brace = memchr(name, '}', namelen);
1275         if (!brace)
1276                 return -1;
1277         nth = strtol(name + 3, &num_end, 10);
1278         if (num_end != brace)
1279                 return -1;
1280         if (nth <= 0)
1281                 return -1;
1282         cb.remaining = nth;
1283         strbuf_init(&cb.buf, 20);
1284
1285         retval = 0;
1286         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1287                 strbuf_reset(buf);
1288                 strbuf_addbuf(buf, &cb.buf);
1289                 retval = brace - name + 1;
1290         }
1291
1292         strbuf_release(&cb.buf);
1293         return retval;
1294 }
1295
1296 int get_oid_mb(const char *name, struct object_id *oid)
1297 {
1298         struct commit *one, *two;
1299         struct commit_list *mbs;
1300         struct object_id oid_tmp;
1301         const char *dots;
1302         int st;
1303
1304         dots = strstr(name, "...");
1305         if (!dots)
1306                 return get_oid(name, oid);
1307         if (dots == name)
1308                 st = get_oid("HEAD", &oid_tmp);
1309         else {
1310                 struct strbuf sb;
1311                 strbuf_init(&sb, dots - name);
1312                 strbuf_add(&sb, name, dots - name);
1313                 st = get_oid_committish(sb.buf, &oid_tmp);
1314                 strbuf_release(&sb);
1315         }
1316         if (st)
1317                 return st;
1318         one = lookup_commit_reference_gently(the_repository, &oid_tmp, 0);
1319         if (!one)
1320                 return -1;
1321
1322         if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1323                 return -1;
1324         two = lookup_commit_reference_gently(the_repository, &oid_tmp, 0);
1325         if (!two)
1326                 return -1;
1327         mbs = get_merge_bases(one, two);
1328         if (!mbs || mbs->next)
1329                 st = -1;
1330         else {
1331                 st = 0;
1332                 oidcpy(oid, &mbs->item->object.oid);
1333         }
1334         free_commit_list(mbs);
1335         return st;
1336 }
1337
1338 /* parse @something syntax, when 'something' is not {.*} */
1339 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1340 {
1341         const char *next;
1342
1343         if (len || name[1] == '{')
1344                 return -1;
1345
1346         /* make sure it's a single @, or @@{.*}, not @foo */
1347         next = memchr(name + len + 1, '@', namelen - len - 1);
1348         if (next && next[1] != '{')
1349                 return -1;
1350         if (!next)
1351                 next = name + namelen;
1352         if (next != name + 1)
1353                 return -1;
1354
1355         strbuf_reset(buf);
1356         strbuf_add(buf, "HEAD", 4);
1357         return 1;
1358 }
1359
1360 static int reinterpret(const char *name, int namelen, int len,
1361                        struct strbuf *buf, unsigned allowed)
1362 {
1363         /* we have extra data, which might need further processing */
1364         struct strbuf tmp = STRBUF_INIT;
1365         int used = buf->len;
1366         int ret;
1367
1368         strbuf_add(buf, name + len, namelen - len);
1369         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1370         /* that data was not interpreted, remove our cruft */
1371         if (ret < 0) {
1372                 strbuf_setlen(buf, used);
1373                 return len;
1374         }
1375         strbuf_reset(buf);
1376         strbuf_addbuf(buf, &tmp);
1377         strbuf_release(&tmp);
1378         /* tweak for size of {-N} versus expanded ref name */
1379         return ret - used + len;
1380 }
1381
1382 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1383 {
1384         char *s = shorten_unambiguous_ref(ref, 0);
1385         strbuf_reset(buf);
1386         strbuf_addstr(buf, s);
1387         free(s);
1388 }
1389
1390 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1391 {
1392         if (!allowed)
1393                 return 1;
1394
1395         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1396             starts_with(refname, "refs/heads/"))
1397                 return 1;
1398         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1399             starts_with(refname, "refs/remotes/"))
1400                 return 1;
1401
1402         return 0;
1403 }
1404
1405 static int interpret_branch_mark(const char *name, int namelen,
1406                                  int at, struct strbuf *buf,
1407                                  int (*get_mark)(const char *, int),
1408                                  const char *(*get_data)(struct branch *,
1409                                                          struct strbuf *),
1410                                  unsigned allowed)
1411 {
1412         int len;
1413         struct branch *branch;
1414         struct strbuf err = STRBUF_INIT;
1415         const char *value;
1416
1417         len = get_mark(name + at, namelen - at);
1418         if (!len)
1419                 return -1;
1420
1421         if (memchr(name, ':', at))
1422                 return -1;
1423
1424         if (at) {
1425                 char *name_str = xmemdupz(name, at);
1426                 branch = branch_get(name_str);
1427                 free(name_str);
1428         } else
1429                 branch = branch_get(NULL);
1430
1431         value = get_data(branch, &err);
1432         if (!value)
1433                 die("%s", err.buf);
1434
1435         if (!branch_interpret_allowed(value, allowed))
1436                 return -1;
1437
1438         set_shortened_ref(buf, value);
1439         return len + at;
1440 }
1441
1442 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1443                           unsigned allowed)
1444 {
1445         char *at;
1446         const char *start;
1447         int len;
1448
1449         if (!namelen)
1450                 namelen = strlen(name);
1451
1452         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1453                 len = interpret_nth_prior_checkout(name, namelen, buf);
1454                 if (!len) {
1455                         return len; /* syntax Ok, not enough switches */
1456                 } else if (len > 0) {
1457                         if (len == namelen)
1458                                 return len; /* consumed all */
1459                         else
1460                                 return reinterpret(name, namelen, len, buf, allowed);
1461                 }
1462         }
1463
1464         for (start = name;
1465              (at = memchr(start, '@', namelen - (start - name)));
1466              start = at + 1) {
1467
1468                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1469                         len = interpret_empty_at(name, namelen, at - name, buf);
1470                         if (len > 0)
1471                                 return reinterpret(name, namelen, len, buf,
1472                                                    allowed);
1473                 }
1474
1475                 len = interpret_branch_mark(name, namelen, at - name, buf,
1476                                             upstream_mark, branch_get_upstream,
1477                                             allowed);
1478                 if (len > 0)
1479                         return len;
1480
1481                 len = interpret_branch_mark(name, namelen, at - name, buf,
1482                                             push_mark, branch_get_push,
1483                                             allowed);
1484                 if (len > 0)
1485                         return len;
1486         }
1487
1488         return -1;
1489 }
1490
1491 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1492 {
1493         int len = strlen(name);
1494         int used = interpret_branch_name(name, len, sb, allowed);
1495
1496         if (used < 0)
1497                 used = 0;
1498         strbuf_add(sb, name + used, len - used);
1499 }
1500
1501 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1502 {
1503         if (startup_info->have_repository)
1504                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1505         else
1506                 strbuf_addstr(sb, name);
1507
1508         /*
1509          * This splice must be done even if we end up rejecting the
1510          * name; builtin/branch.c::copy_or_rename_branch() still wants
1511          * to see what the name expanded to so that "branch -m" can be
1512          * used as a tool to correct earlier mistakes.
1513          */
1514         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1515
1516         if (*name == '-' ||
1517             !strcmp(sb->buf, "refs/heads/HEAD"))
1518                 return -1;
1519
1520         return check_refname_format(sb->buf, 0);
1521 }
1522
1523 /*
1524  * This is like "get_oid_basic()", except it allows "object ID expressions",
1525  * notably "xyz^" for "parent of xyz"
1526  */
1527 int get_oid(const char *name, struct object_id *oid)
1528 {
1529         struct object_context unused;
1530         return get_oid_with_context(the_repository, name, 0, oid, &unused);
1531 }
1532
1533 /*
1534  * This returns a non-zero value if the string (built using printf
1535  * format and the given arguments) is not a valid object.
1536  */
1537 int get_oidf(struct object_id *oid, const char *fmt, ...)
1538 {
1539         va_list ap;
1540         int ret;
1541         struct strbuf sb = STRBUF_INIT;
1542
1543         va_start(ap, fmt);
1544         strbuf_vaddf(&sb, fmt, ap);
1545         va_end(ap);
1546
1547         ret = get_oid(sb.buf, oid);
1548         strbuf_release(&sb);
1549
1550         return ret;
1551 }
1552
1553 /*
1554  * Many callers know that the user meant to name a commit-ish by
1555  * syntactical positions where the object name appears.  Calling this
1556  * function allows the machinery to disambiguate shorter-than-unique
1557  * abbreviated object names between commit-ish and others.
1558  *
1559  * Note that this does NOT error out when the named object is not a
1560  * commit-ish. It is merely to give a hint to the disambiguation
1561  * machinery.
1562  */
1563 int get_oid_committish(const char *name, struct object_id *oid)
1564 {
1565         struct object_context unused;
1566         return get_oid_with_context(the_repository,
1567                                     name, GET_OID_COMMITTISH,
1568                                     oid, &unused);
1569 }
1570
1571 int get_oid_treeish(const char *name, struct object_id *oid)
1572 {
1573         struct object_context unused;
1574         return get_oid_with_context(the_repository,
1575                                     name, GET_OID_TREEISH,
1576                                     oid, &unused);
1577 }
1578
1579 int get_oid_commit(const char *name, struct object_id *oid)
1580 {
1581         struct object_context unused;
1582         return get_oid_with_context(the_repository,
1583                                     name, GET_OID_COMMIT,
1584                                     oid, &unused);
1585 }
1586
1587 int get_oid_tree(const char *name, struct object_id *oid)
1588 {
1589         struct object_context unused;
1590         return get_oid_with_context(the_repository,
1591                                     name, GET_OID_TREE,
1592                                     oid, &unused);
1593 }
1594
1595 int get_oid_blob(const char *name, struct object_id *oid)
1596 {
1597         struct object_context unused;
1598         return get_oid_with_context(the_repository,
1599                                     name, GET_OID_BLOB,
1600                                     oid, &unused);
1601 }
1602
1603 /* Must be called only when object_name:filename doesn't exist. */
1604 static void diagnose_invalid_oid_path(const char *prefix,
1605                                       const char *filename,
1606                                       const struct object_id *tree_oid,
1607                                       const char *object_name,
1608                                       int object_name_len)
1609 {
1610         struct object_id oid;
1611         unsigned mode;
1612
1613         if (!prefix)
1614                 prefix = "";
1615
1616         if (file_exists(filename))
1617                 die("Path '%s' exists on disk, but not in '%.*s'.",
1618                     filename, object_name_len, object_name);
1619         if (is_missing_file_error(errno)) {
1620                 char *fullname = xstrfmt("%s%s", prefix, filename);
1621
1622                 if (!get_tree_entry(tree_oid, fullname, &oid, &mode)) {
1623                         die("Path '%s' exists, but not '%s'.\n"
1624                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1625                             fullname,
1626                             filename,
1627                             object_name_len, object_name,
1628                             fullname,
1629                             object_name_len, object_name,
1630                             filename);
1631                 }
1632                 die("Path '%s' does not exist in '%.*s'",
1633                     filename, object_name_len, object_name);
1634         }
1635 }
1636
1637 /* Must be called only when :stage:filename doesn't exist. */
1638 static void diagnose_invalid_index_path(struct index_state *istate,
1639                                         int stage,
1640                                         const char *prefix,
1641                                         const char *filename)
1642 {
1643         const struct cache_entry *ce;
1644         int pos;
1645         unsigned namelen = strlen(filename);
1646         struct strbuf fullname = STRBUF_INIT;
1647
1648         if (!prefix)
1649                 prefix = "";
1650
1651         /* Wrong stage number? */
1652         pos = index_name_pos(istate, filename, namelen);
1653         if (pos < 0)
1654                 pos = -pos - 1;
1655         if (pos < istate->cache_nr) {
1656                 ce = istate->cache[pos];
1657                 if (ce_namelen(ce) == namelen &&
1658                     !memcmp(ce->name, filename, namelen))
1659                         die("Path '%s' is in the index, but not at stage %d.\n"
1660                             "Did you mean ':%d:%s'?",
1661                             filename, stage,
1662                             ce_stage(ce), filename);
1663         }
1664
1665         /* Confusion between relative and absolute filenames? */
1666         strbuf_addstr(&fullname, prefix);
1667         strbuf_addstr(&fullname, filename);
1668         pos = index_name_pos(istate, fullname.buf, fullname.len);
1669         if (pos < 0)
1670                 pos = -pos - 1;
1671         if (pos < istate->cache_nr) {
1672                 ce = istate->cache[pos];
1673                 if (ce_namelen(ce) == fullname.len &&
1674                     !memcmp(ce->name, fullname.buf, fullname.len))
1675                         die("Path '%s' is in the index, but not '%s'.\n"
1676                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1677                             fullname.buf, filename,
1678                             ce_stage(ce), fullname.buf,
1679                             ce_stage(ce), filename);
1680         }
1681
1682         if (file_exists(filename))
1683                 die("Path '%s' exists on disk, but not in the index.", filename);
1684         if (is_missing_file_error(errno))
1685                 die("Path '%s' does not exist (neither on disk nor in the index).",
1686                     filename);
1687
1688         strbuf_release(&fullname);
1689 }
1690
1691
1692 static char *resolve_relative_path(const char *rel)
1693 {
1694         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1695                 return NULL;
1696
1697         if (!is_inside_work_tree())
1698                 die("relative path syntax can't be used outside working tree.");
1699
1700         /* die() inside prefix_path() if resolved path is outside worktree */
1701         return prefix_path(startup_info->prefix,
1702                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1703                            rel);
1704 }
1705
1706 static enum get_oid_result get_oid_with_context_1(struct repository *repo,
1707                                   const char *name,
1708                                   unsigned flags,
1709                                   const char *prefix,
1710                                   struct object_id *oid,
1711                                   struct object_context *oc)
1712 {
1713         int ret, bracket_depth;
1714         int namelen = strlen(name);
1715         const char *cp;
1716         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1717
1718         if (only_to_die)
1719                 flags |= GET_OID_QUIETLY;
1720
1721         memset(oc, 0, sizeof(*oc));
1722         oc->mode = S_IFINVALID;
1723         strbuf_init(&oc->symlink_path, 0);
1724         ret = get_oid_1(name, namelen, oid, flags);
1725         if (!ret)
1726                 return ret;
1727         /*
1728          * sha1:path --> object name of path in ent sha1
1729          * :path -> object name of absolute path in index
1730          * :./path -> object name of path relative to cwd in index
1731          * :[0-3]:path -> object name of path in index at stage
1732          * :/foo -> recent commit matching foo
1733          */
1734         if (name[0] == ':') {
1735                 int stage = 0;
1736                 const struct cache_entry *ce;
1737                 char *new_path = NULL;
1738                 int pos;
1739                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1740                         struct commit_list *list = NULL;
1741
1742                         for_each_ref(handle_one_ref, &list);
1743                         head_ref(handle_one_ref, &list);
1744                         commit_list_sort_by_date(&list);
1745                         return get_oid_oneline(name + 2, oid, list);
1746                 }
1747                 if (namelen < 3 ||
1748                     name[2] != ':' ||
1749                     name[1] < '0' || '3' < name[1])
1750                         cp = name + 1;
1751                 else {
1752                         stage = name[1] - '0';
1753                         cp = name + 3;
1754                 }
1755                 new_path = resolve_relative_path(cp);
1756                 if (!new_path) {
1757                         namelen = namelen - (cp - name);
1758                 } else {
1759                         cp = new_path;
1760                         namelen = strlen(cp);
1761                 }
1762
1763                 if (flags & GET_OID_RECORD_PATH)
1764                         oc->path = xstrdup(cp);
1765
1766                 if (!repo->index->cache)
1767                         repo_read_index(the_repository);
1768                 pos = index_name_pos(repo->index, cp, namelen);
1769                 if (pos < 0)
1770                         pos = -pos - 1;
1771                 while (pos < repo->index->cache_nr) {
1772                         ce = repo->index->cache[pos];
1773                         if (ce_namelen(ce) != namelen ||
1774                             memcmp(ce->name, cp, namelen))
1775                                 break;
1776                         if (ce_stage(ce) == stage) {
1777                                 oidcpy(oid, &ce->oid);
1778                                 oc->mode = ce->ce_mode;
1779                                 free(new_path);
1780                                 return 0;
1781                         }
1782                         pos++;
1783                 }
1784                 if (only_to_die && name[1] && name[1] != '/')
1785                         diagnose_invalid_index_path(repo->index, stage, prefix, cp);
1786                 free(new_path);
1787                 return -1;
1788         }
1789         for (cp = name, bracket_depth = 0; *cp; cp++) {
1790                 if (*cp == '{')
1791                         bracket_depth++;
1792                 else if (bracket_depth && *cp == '}')
1793                         bracket_depth--;
1794                 else if (!bracket_depth && *cp == ':')
1795                         break;
1796         }
1797         if (*cp == ':') {
1798                 struct object_id tree_oid;
1799                 int len = cp - name;
1800                 unsigned sub_flags = flags;
1801
1802                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1803                 sub_flags |= GET_OID_TREEISH;
1804
1805                 if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1806                         const char *filename = cp+1;
1807                         char *new_filename = NULL;
1808
1809                         new_filename = resolve_relative_path(filename);
1810                         if (new_filename)
1811                                 filename = new_filename;
1812                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1813                                 ret = get_tree_entry_follow_symlinks(&tree_oid,
1814                                         filename, oid, &oc->symlink_path,
1815                                         &oc->mode);
1816                         } else {
1817                                 ret = get_tree_entry(&tree_oid, filename, oid,
1818                                                      &oc->mode);
1819                                 if (ret && only_to_die) {
1820                                         diagnose_invalid_oid_path(prefix,
1821                                                                    filename,
1822                                                                    &tree_oid,
1823                                                                    name, len);
1824                                 }
1825                         }
1826                         if (flags & GET_OID_RECORD_PATH)
1827                                 oc->path = xstrdup(filename);
1828
1829                         free(new_filename);
1830                         return ret;
1831                 } else {
1832                         if (only_to_die)
1833                                 die("Invalid object name '%.*s'.", len, name);
1834                 }
1835         }
1836         return ret;
1837 }
1838
1839 /*
1840  * Call this function when you know "name" given by the end user must
1841  * name an object but it doesn't; the function _may_ die with a better
1842  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1843  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1844  * you have a chance to diagnose the error further.
1845  */
1846 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1847 {
1848         struct object_context oc;
1849         struct object_id oid;
1850         get_oid_with_context_1(the_repository, name, GET_OID_ONLY_TO_DIE,
1851                                prefix, &oid, &oc);
1852 }
1853
1854 enum get_oid_result get_oid_with_context(struct repository *repo,
1855                                          const char *str,
1856                                          unsigned flags,
1857                                          struct object_id *oid,
1858                                          struct object_context *oc)
1859 {
1860         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1861                 BUG("incompatible flags for get_sha1_with_context");
1862         return get_oid_with_context_1(repo, str, flags, NULL, oid, oc);
1863 }