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
  14 static int get_oid_oneline(const char *, struct object_id *, struct commit_list *);
  15
  16 typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
  17
  18 struct disambiguate_state {
  19         int len; /* length of prefix in hex chars */
  20         char hex_pfx[GIT_MAX_HEXSZ + 1];
  21         struct object_id bin_pfx;
  22
  23         disambiguate_hint_fn fn;
  24         void *cb_data;
  25         struct object_id candidate;
  26         unsigned candidate_exists:1;
  27         unsigned candidate_checked:1;
  28         unsigned candidate_ok:1;
  29         unsigned disambiguate_fn_used:1;
  30         unsigned ambiguous:1;
  31         unsigned always_call_fn:1;
  32 };
  33
  34 static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
  35 {
  36         if (ds->always_call_fn) {
  37                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  38                 return;
  39         }
  40         if (!ds->candidate_exists) {
  41                 /* this is the first candidate */
  42                 oidcpy(&ds->candidate, current);
  43                 ds->candidate_exists = 1;
  44                 return;
  45         } else if (!oidcmp(&ds->candidate, current)) {
  46                 /* the same as what we already have seen */
  47                 return;
  48         }
  49
  50         if (!ds->fn) {
  51                 /* cannot disambiguate between ds->candidate and current */
  52                 ds->ambiguous = 1;
  53                 return;
  54         }
  55
  56         if (!ds->candidate_checked) {
  57                 ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
  58                 ds->disambiguate_fn_used = 1;
  59                 ds->candidate_checked = 1;
  60         }
  61
  62         if (!ds->candidate_ok) {
  63                 /* discard the candidate; we know it does not satisfy fn */
  64                 oidcpy(&ds->candidate, current);
  65                 ds->candidate_checked = 0;
  66                 return;
  67         }
  68
  69         /* if we reach this point, we know ds->candidate satisfies fn */
  70         if (ds->fn(current, ds->cb_data)) {
  71                 /*
  72                  * if both current and candidate satisfy fn, we cannot
  73                  * disambiguate.
  74                  */
  75                 ds->candidate_ok = 0;
  76                 ds->ambiguous = 1;
  77         }
  78
  79         /* otherwise, current can be discarded and candidate is still good */
  80 }
  81
  82 static int append_loose_object(const struct object_id *oid, const char *path,
  83                                void *data)
  84 {
  85         oid_array_append(data, oid);
  86         return 0;
  87 }
  88
  89 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  90
  91 static void find_short_object_filename(struct disambiguate_state *ds)
  92 {
  93         int subdir_nr = ds->bin_pfx.hash[0];
  94         struct alternate_object_database *alt;
  95         static struct alternate_object_database *fakeent;
  96
  97         if (!fakeent) {
  98                 /*
  99                  * Create a "fake" alternate object database that
 100                  * points to our own object database, to make it
 101                  * easier to get a temporary working space in
 102                  * alt->name/alt->base while iterating over the
 103                  * object databases including our own.
 104                  */
 105                 fakeent = alloc_alt_odb(get_object_directory());
 106         }
 107         fakeent->next = alt_odb_list;
 108
 109         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 110                 int pos;
 111
 112                 if (!alt->loose_objects_subdir_seen[subdir_nr]) {
 113                         struct strbuf *buf = alt_scratch_buf(alt);
 114                         for_each_file_in_obj_subdir(subdir_nr, buf,
 115                                                     append_loose_object,
 116                                                     NULL, NULL,
 117                                                     &alt->loose_objects_cache);
 118                         alt->loose_objects_subdir_seen[subdir_nr] = 1;
 119                 }
 120
 121                 pos = oid_array_lookup(&alt->loose_objects_cache, &ds->bin_pfx);
 122                 if (pos < 0)
 123                         pos = -1 - pos;
 124                 while (!ds->ambiguous && pos < alt->loose_objects_cache.nr) {
 125                         const struct object_id *oid;
 126                         oid = alt->loose_objects_cache.oid + pos;
 127                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 128                                 break;
 129                         update_candidates(ds, oid);
 130                         pos++;
 131                 }
 132         }
 133 }
 134
 135 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 136 {
 137         do {
 138                 if (*a != *b)
 139                         return 0;
 140                 a++;
 141                 b++;
 142                 len -= 2;
 143         } while (len > 1);
 144         if (len)
 145                 if ((*a ^ *b) & 0xf0)
 146                         return 0;
 147         return 1;
 148 }
 149
 150 static void unique_in_pack(struct packed_git *p,
 151                            struct disambiguate_state *ds)
 152 {
 153         uint32_t num, last, i, first = 0;
 154         const struct object_id *current = NULL;
 155
 156         open_pack_index(p);
 157         num = p->num_objects;
 158         last = num;
 159         while (first < last) {
 160                 uint32_t mid = first + (last - first) / 2;
 161                 const unsigned char *current;
 162                 int cmp;
 163
 164                 current = nth_packed_object_sha1(p, mid);
 165                 cmp = hashcmp(ds->bin_pfx.hash, current);
 166                 if (!cmp) {
 167                         first = mid;
 168                         break;
 169                 }
 170                 if (cmp > 0) {
 171                         first = mid+1;
 172                         continue;
 173                 }
 174                 last = mid;
 175         }
 176
 177         /*
 178          * At this point, "first" is the location of the lowest object
 179          * with an object name that could match "bin_pfx".  See if we have
 180          * 0, 1 or more objects that actually match(es).
 181          */
 182         for (i = first; i < num && !ds->ambiguous; i++) {
 183                 struct object_id oid;
 184                 current = nth_packed_object_oid(&oid, p, i);
 185                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 186                         break;
 187                 update_candidates(ds, current);
 188         }
 189 }
 190
 191 static void find_short_packed_object(struct disambiguate_state *ds)
 192 {
 193         struct packed_git *p;
 194
 195         prepare_packed_git();
 196         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 197                 unique_in_pack(p, ds);
 198 }
 199
 200 #define SHORT_NAME_NOT_FOUND (-1)
 201 #define SHORT_NAME_AMBIGUOUS (-2)
 202
 203 static int finish_object_disambiguation(struct disambiguate_state *ds,
 204                                         struct object_id *oid)
 205 {
 206         if (ds->ambiguous)
 207                 return SHORT_NAME_AMBIGUOUS;
 208
 209         if (!ds->candidate_exists)
 210                 return SHORT_NAME_NOT_FOUND;
 211
 212         if (!ds->candidate_checked)
 213                 /*
 214                  * If this is the only candidate, there is no point
 215                  * calling the disambiguation hint callback.
 216                  *
 217                  * On the other hand, if the current candidate
 218                  * replaced an earlier candidate that did _not_ pass
 219                  * the disambiguation hint callback, then we do have
 220                  * more than one objects that match the short name
 221                  * given, so we should make sure this one matches;
 222                  * otherwise, if we discovered this one and the one
 223                  * that we previously discarded in the reverse order,
 224                  * we would end up showing different results in the
 225                  * same repository!
 226                  */
 227                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 228                                     ds->fn(&ds->candidate, ds->cb_data));
 229
 230         if (!ds->candidate_ok)
 231                 return SHORT_NAME_AMBIGUOUS;
 232
 233         oidcpy(oid, &ds->candidate);
 234         return 0;
 235 }
 236
 237 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 238 {
 239         int kind = sha1_object_info(oid->hash, NULL);
 240         return kind == OBJ_COMMIT;
 241 }
 242
 243 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 244 {
 245         struct object *obj;
 246         int kind;
 247
 248         kind = sha1_object_info(oid->hash, NULL);
 249         if (kind == OBJ_COMMIT)
 250                 return 1;
 251         if (kind != OBJ_TAG)
 252                 return 0;
 253
 254         /* We need to do this the hard way... */
 255         obj = deref_tag(parse_object(oid), NULL, 0);
 256         if (obj && obj->type == OBJ_COMMIT)
 257                 return 1;
 258         return 0;
 259 }
 260
 261 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 262 {
 263         int kind = sha1_object_info(oid->hash, NULL);
 264         return kind == OBJ_TREE;
 265 }
 266
 267 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 268 {
 269         struct object *obj;
 270         int kind;
 271
 272         kind = sha1_object_info(oid->hash, NULL);
 273         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 274                 return 1;
 275         if (kind != OBJ_TAG)
 276                 return 0;
 277
 278         /* We need to do this the hard way... */
 279         obj = deref_tag(parse_object(oid), NULL, 0);
 280         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 281                 return 1;
 282         return 0;
 283 }
 284
 285 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 286 {
 287         int kind = sha1_object_info(oid->hash, NULL);
 288         return kind == OBJ_BLOB;
 289 }
 290
 291 static disambiguate_hint_fn default_disambiguate_hint;
 292
 293 int set_disambiguate_hint_config(const char *var, const char *value)
 294 {
 295         static const struct {
 296                 const char *name;
 297                 disambiguate_hint_fn fn;
 298         } hints[] = {
 299                 { "none", NULL },
 300                 { "commit", disambiguate_commit_only },
 301                 { "committish", disambiguate_committish_only },
 302                 { "tree", disambiguate_tree_only },
 303                 { "treeish", disambiguate_treeish_only },
 304                 { "blob", disambiguate_blob_only }
 305         };
 306         int i;
 307
 308         if (!value)
 309                 return config_error_nonbool(var);
 310
 311         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 312                 if (!strcasecmp(value, hints[i].name)) {
 313                         default_disambiguate_hint = hints[i].fn;
 314                         return 0;
 315                 }
 316         }
 317
 318         return error("unknown hint type for '%s': %s", var, value);
 319 }
 320
 321 static int init_object_disambiguation(const char *name, int len,
 322                                       struct disambiguate_state *ds)
 323 {
 324         int i;
 325
 326         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 327                 return -1;
 328
 329         memset(ds, 0, sizeof(*ds));
 330
 331         for (i = 0; i < len ;i++) {
 332                 unsigned char c = name[i];
 333                 unsigned char val;
 334                 if (c >= '0' && c <= '9')
 335                         val = c - '0';
 336                 else if (c >= 'a' && c <= 'f')
 337                         val = c - 'a' + 10;
 338                 else if (c >= 'A' && c <='F') {
 339                         val = c - 'A' + 10;
 340                         c -= 'A' - 'a';
 341                 }
 342                 else
 343                         return -1;
 344                 ds->hex_pfx[i] = c;
 345                 if (!(i & 1))
 346                         val <<= 4;
 347                 ds->bin_pfx.hash[i >> 1] |= val;
 348         }
 349
 350         ds->len = len;
 351         ds->hex_pfx[len] = '\0';
 352         prepare_alt_odb();
 353         return 0;
 354 }
 355
 356 static int show_ambiguous_object(const struct object_id *oid, void *data)
 357 {
 358         const struct disambiguate_state *ds = data;
 359         struct strbuf desc = STRBUF_INIT;
 360         int type;
 361
 362
 363         if (ds->fn && !ds->fn(oid, ds->cb_data))
 364                 return 0;
 365
 366         type = sha1_object_info(oid->hash, NULL);
 367         if (type == OBJ_COMMIT) {
 368                 struct commit *commit = lookup_commit(oid);
 369                 if (commit) {
 370                         struct pretty_print_context pp = {0};
 371                         pp.date_mode.type = DATE_SHORT;
 372                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 373                 }
 374         } else if (type == OBJ_TAG) {
 375                 struct tag *tag = lookup_tag(oid);
 376                 if (!parse_tag(tag) && tag->tag)
 377                         strbuf_addf(&desc, " %s", tag->tag);
 378         }
 379
 380         advise("  %s %s%s",
 381                find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
 382                typename(type) ? typename(type) : "unknown type",
 383                desc.buf);
 384
 385         strbuf_release(&desc);
 386         return 0;
 387 }
 388
 389 static int get_short_oid(const char *name, int len, struct object_id *oid,
 390                           unsigned flags)
 391 {
 392         int status;
 393         struct disambiguate_state ds;
 394         int quietly = !!(flags & GET_OID_QUIETLY);
 395
 396         if (init_object_disambiguation(name, len, &ds) < 0)
 397                 return -1;
 398
 399         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 400                 die("BUG: multiple get_short_oid disambiguator flags");
 401
 402         if (flags & GET_OID_COMMIT)
 403                 ds.fn = disambiguate_commit_only;
 404         else if (flags & GET_OID_COMMITTISH)
 405                 ds.fn = disambiguate_committish_only;
 406         else if (flags & GET_OID_TREE)
 407                 ds.fn = disambiguate_tree_only;
 408         else if (flags & GET_OID_TREEISH)
 409                 ds.fn = disambiguate_treeish_only;
 410         else if (flags & GET_OID_BLOB)
 411                 ds.fn = disambiguate_blob_only;
 412         else
 413                 ds.fn = default_disambiguate_hint;
 414
 415         find_short_object_filename(&ds);
 416         find_short_packed_object(&ds);
 417         status = finish_object_disambiguation(&ds, oid);
 418
 419         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 420                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 421
 422                 /*
 423                  * We may still have ambiguity if we simply saw a series of
 424                  * candidates that did not satisfy our hint function. In
 425                  * that case, we still want to show them, so disable the hint
 426                  * function entirely.
 427                  */
 428                 if (!ds.ambiguous)
 429                         ds.fn = NULL;
 430
 431                 advise(_("The candidates are:"));
 432                 for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
 433         }
 434
 435         return status;
 436 }
 437
 438 static int collect_ambiguous(const struct object_id *oid, void *data)
 439 {
 440         oid_array_append(data, oid);
 441         return 0;
 442 }
 443
 444 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 445 {
 446         struct oid_array collect = OID_ARRAY_INIT;
 447         struct disambiguate_state ds;
 448         int ret;
 449
 450         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 451                 return -1;
 452
 453         ds.always_call_fn = 1;
 454         ds.fn = collect_ambiguous;
 455         ds.cb_data = &collect;
 456         find_short_object_filename(&ds);
 457         find_short_packed_object(&ds);
 458
 459         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 460         oid_array_clear(&collect);
 461         return ret;
 462 }
 463
 464 /*
 465  * Return the slot of the most-significant bit set in "val". There are various
 466  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 467  * probably not a big deal here.
 468  */
 469 static unsigned msb(unsigned long val)
 470 {
 471         unsigned r = 0;
 472         while (val >>= 1)
 473                 r++;
 474         return r;
 475 }
 476
 477 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 478 {
 479         int status, exists;
 480
 481         if (len < 0) {
 482                 unsigned long count = approximate_object_count();
 483                 /*
 484                  * Add one because the MSB only tells us the highest bit set,
 485                  * not including the value of all the _other_ bits (so "15"
 486                  * is only one off of 2^4, but the MSB is the 3rd bit.
 487                  */
 488                 len = msb(count) + 1;
 489                 /*
 490                  * We now know we have on the order of 2^len objects, which
 491                  * expects a collision at 2^(len/2). But we also care about hex
 492                  * chars, not bits, and there are 4 bits per hex. So all
 493                  * together we need to divide by 2 and round up.
 494                  */
 495                 len = DIV_ROUND_UP(len, 2);
 496                 /*
 497                  * For very small repos, we stick with our regular fallback.
 498                  */
 499                 if (len < FALLBACK_DEFAULT_ABBREV)
 500                         len = FALLBACK_DEFAULT_ABBREV;
 501         }
 502
 503         sha1_to_hex_r(hex, sha1);
 504         if (len == GIT_SHA1_HEXSZ || !len)
 505                 return GIT_SHA1_HEXSZ;
 506         exists = has_sha1_file(sha1);
 507         while (len < GIT_SHA1_HEXSZ) {
 508                 struct object_id oid_ret;
 509                 status = get_short_oid(hex, len, &oid_ret, GET_OID_QUIETLY);
 510                 if (exists
 511                     ? !status
 512                     : status == SHORT_NAME_NOT_FOUND) {
 513                         hex[len] = 0;
 514                         return len;
 515                 }
 516                 len++;
 517         }
 518         return len;
 519 }
 520
 521 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 522 {
 523         static int bufno;
 524         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 525         char *hex = hexbuffer[bufno];
 526         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 527         find_unique_abbrev_r(hex, sha1, len);
 528         return hex;
 529 }
 530
 531 static int ambiguous_path(const char *path, int len)
 532 {
 533         int slash = 1;
 534         int cnt;
 535
 536         for (cnt = 0; cnt < len; cnt++) {
 537                 switch (*path++) {
 538                 case '\0':
 539                         break;
 540                 case '/':
 541                         if (slash)
 542                                 break;
 543                         slash = 1;
 544                         continue;
 545                 case '.':
 546                         continue;
 547                 default:
 548                         slash = 0;
 549                         continue;
 550                 }
 551                 break;
 552         }
 553         return slash;
 554 }
 555
 556 static inline int at_mark(const char *string, int len,
 557                           const char **suffix, int nr)
 558 {
 559         int i;
 560
 561         for (i = 0; i < nr; i++) {
 562                 int suffix_len = strlen(suffix[i]);
 563                 if (suffix_len <= len
 564                     && !strncasecmp(string, suffix[i], suffix_len))
 565                         return suffix_len;
 566         }
 567         return 0;
 568 }
 569
 570 static inline int upstream_mark(const char *string, int len)
 571 {
 572         const char *suffix[] = { "@{upstream}", "@{u}" };
 573         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 574 }
 575
 576 static inline int push_mark(const char *string, int len)
 577 {
 578         const char *suffix[] = { "@{push}" };
 579         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 580 }
 581
 582 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 583 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 584
 585 static int get_oid_basic(const char *str, int len, struct object_id *oid,
 586                           unsigned int flags)
 587 {
 588         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 589         static const char *object_name_msg = N_(
 590         "Git normally never creates a ref that ends with 40 hex characters\n"
 591         "because it will be ignored when you just specify 40-hex. These refs\n"
 592         "may be created by mistake. For example,\n"
 593         "\n"
 594         "  git checkout -b $br $(git rev-parse ...)\n"
 595         "\n"
 596         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 597         "examine these refs and maybe delete them. Turn this message off by\n"
 598         "running \"git config advice.objectNameWarning false\"");
 599         struct object_id tmp_oid;
 600         char *real_ref = NULL;
 601         int refs_found = 0;
 602         int at, reflog_len, nth_prior = 0;
 603
 604         if (len == GIT_SHA1_HEXSZ && !get_oid_hex(str, oid)) {
 605                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 606                         refs_found = dwim_ref(str, len, tmp_oid.hash, &real_ref);
 607                         if (refs_found > 0) {
 608                                 warning(warn_msg, len, str);
 609                                 if (advice_object_name_warning)
 610                                         fprintf(stderr, "%s\n", _(object_name_msg));
 611                         }
 612                         free(real_ref);
 613                 }
 614                 return 0;
 615         }
 616
 617         /* basic@{time or number or -number} format to query ref-log */
 618         reflog_len = at = 0;
 619         if (len && str[len-1] == '}') {
 620                 for (at = len-4; at >= 0; at--) {
 621                         if (str[at] == '@' && str[at+1] == '{') {
 622                                 if (str[at+2] == '-') {
 623                                         if (at != 0)
 624                                                 /* @{-N} not at start */
 625                                                 return -1;
 626                                         nth_prior = 1;
 627                                         continue;
 628                                 }
 629                                 if (!upstream_mark(str + at, len - at) &&
 630                                     !push_mark(str + at, len - at)) {
 631                                         reflog_len = (len-1) - (at+2);
 632                                         len = at;
 633                                 }
 634                                 break;
 635                         }
 636                 }
 637         }
 638
 639         /* Accept only unambiguous ref paths. */
 640         if (len && ambiguous_path(str, len))
 641                 return -1;
 642
 643         if (nth_prior) {
 644                 struct strbuf buf = STRBUF_INIT;
 645                 int detached;
 646
 647                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 648                         detached = (buf.len == GIT_SHA1_HEXSZ && !get_oid_hex(buf.buf, oid));
 649                         strbuf_release(&buf);
 650                         if (detached)
 651                                 return 0;
 652                 }
 653         }
 654
 655         if (!len && reflog_len)
 656                 /* allow "@{...}" to mean the current branch reflog */
 657                 refs_found = dwim_ref("HEAD", 4, oid->hash, &real_ref);
 658         else if (reflog_len)
 659                 refs_found = dwim_log(str, len, oid->hash, &real_ref);
 660         else
 661                 refs_found = dwim_ref(str, len, oid->hash, &real_ref);
 662
 663         if (!refs_found)
 664                 return -1;
 665
 666         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 667             (refs_found > 1 ||
 668              !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
 669                 warning(warn_msg, len, str);
 670
 671         if (reflog_len) {
 672                 int nth, i;
 673                 timestamp_t at_time;
 674                 timestamp_t co_time;
 675                 int co_tz, co_cnt;
 676
 677                 /* Is it asking for N-th entry, or approxidate? */
 678                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 679                         char ch = str[at+2+i];
 680                         if ('0' <= ch && ch <= '9')
 681                                 nth = nth * 10 + ch - '0';
 682                         else
 683                                 nth = -1;
 684                 }
 685                 if (100000000 <= nth) {
 686                         at_time = nth;
 687                         nth = -1;
 688                 } else if (0 <= nth)
 689                         at_time = 0;
 690                 else {
 691                         int errors = 0;
 692                         char *tmp = xstrndup(str + at + 2, reflog_len);
 693                         at_time = approxidate_careful(tmp, &errors);
 694                         free(tmp);
 695                         if (errors) {
 696                                 free(real_ref);
 697                                 return -1;
 698                         }
 699                 }
 700                 if (read_ref_at(real_ref, flags, at_time, nth, oid->hash, NULL,
 701                                 &co_time, &co_tz, &co_cnt)) {
 702                         if (!len) {
 703                                 if (starts_with(real_ref, "refs/heads/")) {
 704                                         str = real_ref + 11;
 705                                         len = strlen(real_ref + 11);
 706                                 } else {
 707                                         /* detached HEAD */
 708                                         str = "HEAD";
 709                                         len = 4;
 710                                 }
 711                         }
 712                         if (at_time) {
 713                                 if (!(flags & GET_OID_QUIETLY)) {
 714                                         warning("Log for '%.*s' only goes "
 715                                                 "back to %s.", len, str,
 716                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 717                                 }
 718                         } else {
 719                                 if (flags & GET_OID_QUIETLY) {
 720                                         exit(128);
 721                                 }
 722                                 die("Log for '%.*s' only has %d entries.",
 723                                     len, str, co_cnt);
 724                         }
 725                 }
 726         }
 727
 728         free(real_ref);
 729         return 0;
 730 }
 731
 732 static int get_parent(const char *name, int len,
 733                       struct object_id *result, int idx)
 734 {
 735         struct object_id oid;
 736         int ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 737         struct commit *commit;
 738         struct commit_list *p;
 739
 740         if (ret)
 741                 return ret;
 742         commit = lookup_commit_reference(&oid);
 743         if (parse_commit(commit))
 744                 return -1;
 745         if (!idx) {
 746                 oidcpy(result, &commit->object.oid);
 747                 return 0;
 748         }
 749         p = commit->parents;
 750         while (p) {
 751                 if (!--idx) {
 752                         oidcpy(result, &p->item->object.oid);
 753                         return 0;
 754                 }
 755                 p = p->next;
 756         }
 757         return -1;
 758 }
 759
 760 static int get_nth_ancestor(const char *name, int len,
 761                             struct object_id *result, int generation)
 762 {
 763         struct object_id oid;
 764         struct commit *commit;
 765         int ret;
 766
 767         ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 768         if (ret)
 769                 return ret;
 770         commit = lookup_commit_reference(&oid);
 771         if (!commit)
 772                 return -1;
 773
 774         while (generation--) {
 775                 if (parse_commit(commit) || !commit->parents)
 776                         return -1;
 777                 commit = commit->parents->item;
 778         }
 779         oidcpy(result, &commit->object.oid);
 780         return 0;
 781 }
 782
 783 struct object *peel_to_type(const char *name, int namelen,
 784                             struct object *o, enum object_type expected_type)
 785 {
 786         if (name && !namelen)
 787                 namelen = strlen(name);
 788         while (1) {
 789                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 790                         return NULL;
 791                 if (expected_type == OBJ_ANY || o->type == expected_type)
 792                         return o;
 793                 if (o->type == OBJ_TAG)
 794                         o = ((struct tag*) o)->tagged;
 795                 else if (o->type == OBJ_COMMIT)
 796                         o = &(((struct commit *) o)->tree->object);
 797                 else {
 798                         if (name)
 799                                 error("%.*s: expected %s type, but the object "
 800                                       "dereferences to %s type",
 801                                       namelen, name, typename(expected_type),
 802                                       typename(o->type));
 803                         return NULL;
 804                 }
 805         }
 806 }
 807
 808 static int peel_onion(const char *name, int len, struct object_id *oid,
 809                       unsigned lookup_flags)
 810 {
 811         struct object_id outer;
 812         const char *sp;
 813         unsigned int expected_type = 0;
 814         struct object *o;
 815
 816         /*
 817          * "ref^{type}" dereferences ref repeatedly until you cannot
 818          * dereference anymore, or you get an object of given type,
 819          * whichever comes first.  "ref^{}" means just dereference
 820          * tags until you get a non-tag.  "ref^0" is a shorthand for
 821          * "ref^{commit}".  "commit^{tree}" could be used to find the
 822          * top-level tree of the given commit.
 823          */
 824         if (len < 4 || name[len-1] != '}')
 825                 return -1;
 826
 827         for (sp = name + len - 1; name <= sp; sp--) {
 828                 int ch = *sp;
 829                 if (ch == '{' && name < sp && sp[-1] == '^')
 830                         break;
 831         }
 832         if (sp <= name)
 833                 return -1;
 834
 835         sp++; /* beginning of type name, or closing brace for empty */
 836         if (starts_with(sp, "commit}"))
 837                 expected_type = OBJ_COMMIT;
 838         else if (starts_with(sp, "tag}"))
 839                 expected_type = OBJ_TAG;
 840         else if (starts_with(sp, "tree}"))
 841                 expected_type = OBJ_TREE;
 842         else if (starts_with(sp, "blob}"))
 843                 expected_type = OBJ_BLOB;
 844         else if (starts_with(sp, "object}"))
 845                 expected_type = OBJ_ANY;
 846         else if (sp[0] == '}')
 847                 expected_type = OBJ_NONE;
 848         else if (sp[0] == '/')
 849                 expected_type = OBJ_COMMIT;
 850         else
 851                 return -1;
 852
 853         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
 854         if (expected_type == OBJ_COMMIT)
 855                 lookup_flags |= GET_OID_COMMITTISH;
 856         else if (expected_type == OBJ_TREE)
 857                 lookup_flags |= GET_OID_TREEISH;
 858
 859         if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
 860                 return -1;
 861
 862         o = parse_object(&outer);
 863         if (!o)
 864                 return -1;
 865         if (!expected_type) {
 866                 o = deref_tag(o, name, sp - name - 2);
 867                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 868                         return -1;
 869                 oidcpy(oid, &o->oid);
 870                 return 0;
 871         }
 872
 873         /*
 874          * At this point, the syntax look correct, so
 875          * if we do not get the needed object, we should
 876          * barf.
 877          */
 878         o = peel_to_type(name, len, o, expected_type);
 879         if (!o)
 880                 return -1;
 881
 882         oidcpy(oid, &o->oid);
 883         if (sp[0] == '/') {
 884                 /* "$commit^{/foo}" */
 885                 char *prefix;
 886                 int ret;
 887                 struct commit_list *list = NULL;
 888
 889                 /*
 890                  * $commit^{/}. Some regex implementation may reject.
 891                  * We don't need regex anyway. '' pattern always matches.
 892                  */
 893                 if (sp[1] == '}')
 894                         return 0;
 895
 896                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 897                 commit_list_insert((struct commit *)o, &list);
 898                 ret = get_oid_oneline(prefix, oid, list);
 899                 free(prefix);
 900                 return ret;
 901         }
 902         return 0;
 903 }
 904
 905 static int get_describe_name(const char *name, int len, struct object_id *oid)
 906 {
 907         const char *cp;
 908         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
 909
 910         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 911                 char ch = *cp;
 912                 if (!isxdigit(ch)) {
 913                         /* We must be looking at g in "SOMETHING-g"
 914                          * for it to be describe output.
 915                          */
 916                         if (ch == 'g' && cp[-1] == '-') {
 917                                 cp++;
 918                                 len -= cp - name;
 919                                 return get_short_oid(cp, len, oid, flags);
 920                         }
 921                 }
 922         }
 923         return -1;
 924 }
 925
 926 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags)
 927 {
 928         int ret, has_suffix;
 929         const char *cp;
 930
 931         /*
 932          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 933          */
 934         has_suffix = 0;
 935         for (cp = name + len - 1; name <= cp; cp--) {
 936                 int ch = *cp;
 937                 if ('0' <= ch && ch <= '9')
 938                         continue;
 939                 if (ch == '~' || ch == '^')
 940                         has_suffix = ch;
 941                 break;
 942         }
 943
 944         if (has_suffix) {
 945                 int num = 0;
 946                 int len1 = cp - name;
 947                 cp++;
 948                 while (cp < name + len)
 949                         num = num * 10 + *cp++ - '0';
 950                 if (!num && len1 == len - 1)
 951                         num = 1;
 952                 if (has_suffix == '^')
 953                         return get_parent(name, len1, oid, num);
 954                 /* else if (has_suffix == '~') -- goes without saying */
 955                 return get_nth_ancestor(name, len1, oid, num);
 956         }
 957
 958         ret = peel_onion(name, len, oid, lookup_flags);
 959         if (!ret)
 960                 return 0;
 961
 962         ret = get_oid_basic(name, len, oid, lookup_flags);
 963         if (!ret)
 964                 return 0;
 965
 966         /* It could be describe output that is "SOMETHING-gXXXX" */
 967         ret = get_describe_name(name, len, oid);
 968         if (!ret)
 969                 return 0;
 970
 971         return get_short_oid(name, len, oid, lookup_flags);
 972 }
 973
 974 /*
 975  * This interprets names like ':/Initial revision of "git"' by searching
 976  * through history and returning the first commit whose message starts
 977  * the given regular expression.
 978  *
 979  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 980  *
 981  * For a literal '!' character at the beginning of a pattern, you have to repeat
 982  * that, like: ':/!!foo'
 983  *
 984  * For future extension, all other sequences beginning with ':/!' are reserved.
 985  */
 986
 987 /* Remember to update object flag allocation in object.h */
 988 #define ONELINE_SEEN (1u<<20)
 989
 990 static int handle_one_ref(const char *path, const struct object_id *oid,
 991                           int flag, void *cb_data)
 992 {
 993         struct commit_list **list = cb_data;
 994         struct object *object = parse_object(oid);
 995         if (!object)
 996                 return 0;
 997         if (object->type == OBJ_TAG) {
 998                 object = deref_tag(object, path, strlen(path));
 999                 if (!object)
1000                         return 0;
1001         }
1002         if (object->type != OBJ_COMMIT)
1003                 return 0;
1004         commit_list_insert((struct commit *)object, list);
1005         return 0;
1006 }
1007
1008 static int get_oid_oneline(const char *prefix, struct object_id *oid,
1009                             struct commit_list *list)
1010 {
1011         struct commit_list *backup = NULL, *l;
1012         int found = 0;
1013         int negative = 0;
1014         regex_t regex;
1015
1016         if (prefix[0] == '!') {
1017                 prefix++;
1018
1019                 if (prefix[0] == '-') {
1020                         prefix++;
1021                         negative = 1;
1022                 } else if (prefix[0] != '!') {
1023                         return -1;
1024                 }
1025         }
1026
1027         if (regcomp(&regex, prefix, REG_EXTENDED))
1028                 return -1;
1029
1030         for (l = list; l; l = l->next) {
1031                 l->item->object.flags |= ONELINE_SEEN;
1032                 commit_list_insert(l->item, &backup);
1033         }
1034         while (list) {
1035                 const char *p, *buf;
1036                 struct commit *commit;
1037                 int matches;
1038
1039                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1040                 if (!parse_object(&commit->object.oid))
1041                         continue;
1042                 buf = get_commit_buffer(commit, NULL);
1043                 p = strstr(buf, "\n\n");
1044                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1045                 unuse_commit_buffer(commit, buf);
1046
1047                 if (matches) {
1048                         oidcpy(oid, &commit->object.oid);
1049                         found = 1;
1050                         break;
1051                 }
1052         }
1053         regfree(&regex);
1054         free_commit_list(list);
1055         for (l = backup; l; l = l->next)
1056                 clear_commit_marks(l->item, ONELINE_SEEN);
1057         free_commit_list(backup);
1058         return found ? 0 : -1;
1059 }
1060
1061 struct grab_nth_branch_switch_cbdata {
1062         int remaining;
1063         struct strbuf buf;
1064 };
1065
1066 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1067                                   const char *email, timestamp_t timestamp, int tz,
1068                                   const char *message, void *cb_data)
1069 {
1070         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1071         const char *match = NULL, *target = NULL;
1072         size_t len;
1073
1074         if (skip_prefix(message, "checkout: moving from ", &match))
1075                 target = strstr(match, " to ");
1076
1077         if (!match || !target)
1078                 return 0;
1079         if (--(cb->remaining) == 0) {
1080                 len = target - match;
1081                 strbuf_reset(&cb->buf);
1082                 strbuf_add(&cb->buf, match, len);
1083                 return 1; /* we are done */
1084         }
1085         return 0;
1086 }
1087
1088 /*
1089  * Parse @{-N} syntax, return the number of characters parsed
1090  * if successful; otherwise signal an error with negative value.
1091  */
1092 static int interpret_nth_prior_checkout(const char *name, int namelen,
1093                                         struct strbuf *buf)
1094 {
1095         long nth;
1096         int retval;
1097         struct grab_nth_branch_switch_cbdata cb;
1098         const char *brace;
1099         char *num_end;
1100
1101         if (namelen < 4)
1102                 return -1;
1103         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1104                 return -1;
1105         brace = memchr(name, '}', namelen);
1106         if (!brace)
1107                 return -1;
1108         nth = strtol(name + 3, &num_end, 10);
1109         if (num_end != brace)
1110                 return -1;
1111         if (nth <= 0)
1112                 return -1;
1113         cb.remaining = nth;
1114         strbuf_init(&cb.buf, 20);
1115
1116         retval = 0;
1117         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1118                 strbuf_reset(buf);
1119                 strbuf_addbuf(buf, &cb.buf);
1120                 retval = brace - name + 1;
1121         }
1122
1123         strbuf_release(&cb.buf);
1124         return retval;
1125 }
1126
1127 int get_oid_mb(const char *name, struct object_id *oid)
1128 {
1129         struct commit *one, *two;
1130         struct commit_list *mbs;
1131         struct object_id oid_tmp;
1132         const char *dots;
1133         int st;
1134
1135         dots = strstr(name, "...");
1136         if (!dots)
1137                 return get_oid(name, oid);
1138         if (dots == name)
1139                 st = get_oid("HEAD", &oid_tmp);
1140         else {
1141                 struct strbuf sb;
1142                 strbuf_init(&sb, dots - name);
1143                 strbuf_add(&sb, name, dots - name);
1144                 st = get_oid_committish(sb.buf, &oid_tmp);
1145                 strbuf_release(&sb);
1146         }
1147         if (st)
1148                 return st;
1149         one = lookup_commit_reference_gently(&oid_tmp, 0);
1150         if (!one)
1151                 return -1;
1152
1153         if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1154                 return -1;
1155         two = lookup_commit_reference_gently(&oid_tmp, 0);
1156         if (!two)
1157                 return -1;
1158         mbs = get_merge_bases(one, two);
1159         if (!mbs || mbs->next)
1160                 st = -1;
1161         else {
1162                 st = 0;
1163                 oidcpy(oid, &mbs->item->object.oid);
1164         }
1165         free_commit_list(mbs);
1166         return st;
1167 }
1168
1169 /* parse @something syntax, when 'something' is not {.*} */
1170 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1171 {
1172         const char *next;
1173
1174         if (len || name[1] == '{')
1175                 return -1;
1176
1177         /* make sure it's a single @, or @@{.*}, not @foo */
1178         next = memchr(name + len + 1, '@', namelen - len - 1);
1179         if (next && next[1] != '{')
1180                 return -1;
1181         if (!next)
1182                 next = name + namelen;
1183         if (next != name + 1)
1184                 return -1;
1185
1186         strbuf_reset(buf);
1187         strbuf_add(buf, "HEAD", 4);
1188         return 1;
1189 }
1190
1191 static int reinterpret(const char *name, int namelen, int len,
1192                        struct strbuf *buf, unsigned allowed)
1193 {
1194         /* we have extra data, which might need further processing */
1195         struct strbuf tmp = STRBUF_INIT;
1196         int used = buf->len;
1197         int ret;
1198
1199         strbuf_add(buf, name + len, namelen - len);
1200         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1201         /* that data was not interpreted, remove our cruft */
1202         if (ret < 0) {
1203                 strbuf_setlen(buf, used);
1204                 return len;
1205         }
1206         strbuf_reset(buf);
1207         strbuf_addbuf(buf, &tmp);
1208         strbuf_release(&tmp);
1209         /* tweak for size of {-N} versus expanded ref name */
1210         return ret - used + len;
1211 }
1212
1213 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1214 {
1215         char *s = shorten_unambiguous_ref(ref, 0);
1216         strbuf_reset(buf);
1217         strbuf_addstr(buf, s);
1218         free(s);
1219 }
1220
1221 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1222 {
1223         if (!allowed)
1224                 return 1;
1225
1226         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1227             starts_with(refname, "refs/heads/"))
1228                 return 1;
1229         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1230             starts_with(refname, "refs/remotes/"))
1231                 return 1;
1232
1233         return 0;
1234 }
1235
1236 static int interpret_branch_mark(const char *name, int namelen,
1237                                  int at, struct strbuf *buf,
1238                                  int (*get_mark)(const char *, int),
1239                                  const char *(*get_data)(struct branch *,
1240                                                          struct strbuf *),
1241                                  unsigned allowed)
1242 {
1243         int len;
1244         struct branch *branch;
1245         struct strbuf err = STRBUF_INIT;
1246         const char *value;
1247
1248         len = get_mark(name + at, namelen - at);
1249         if (!len)
1250                 return -1;
1251
1252         if (memchr(name, ':', at))
1253                 return -1;
1254
1255         if (at) {
1256                 char *name_str = xmemdupz(name, at);
1257                 branch = branch_get(name_str);
1258                 free(name_str);
1259         } else
1260                 branch = branch_get(NULL);
1261
1262         value = get_data(branch, &err);
1263         if (!value)
1264                 die("%s", err.buf);
1265
1266         if (!branch_interpret_allowed(value, allowed))
1267                 return -1;
1268
1269         set_shortened_ref(buf, value);
1270         return len + at;
1271 }
1272
1273 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1274                           unsigned allowed)
1275 {
1276         char *at;
1277         const char *start;
1278         int len;
1279
1280         if (!namelen)
1281                 namelen = strlen(name);
1282
1283         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1284                 len = interpret_nth_prior_checkout(name, namelen, buf);
1285                 if (!len) {
1286                         return len; /* syntax Ok, not enough switches */
1287                 } else if (len > 0) {
1288                         if (len == namelen)
1289                                 return len; /* consumed all */
1290                         else
1291                                 return reinterpret(name, namelen, len, buf, allowed);
1292                 }
1293         }
1294
1295         for (start = name;
1296              (at = memchr(start, '@', namelen - (start - name)));
1297              start = at + 1) {
1298
1299                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1300                         len = interpret_empty_at(name, namelen, at - name, buf);
1301                         if (len > 0)
1302                                 return reinterpret(name, namelen, len, buf,
1303                                                    allowed);
1304                 }
1305
1306                 len = interpret_branch_mark(name, namelen, at - name, buf,
1307                                             upstream_mark, branch_get_upstream,
1308                                             allowed);
1309                 if (len > 0)
1310                         return len;
1311
1312                 len = interpret_branch_mark(name, namelen, at - name, buf,
1313                                             push_mark, branch_get_push,
1314                                             allowed);
1315                 if (len > 0)
1316                         return len;
1317         }
1318
1319         return -1;
1320 }
1321
1322 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1323 {
1324         int len = strlen(name);
1325         int used = interpret_branch_name(name, len, sb, allowed);
1326
1327         if (used < 0)
1328                 used = 0;
1329         strbuf_add(sb, name + used, len - used);
1330 }
1331
1332 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1333 {
1334         if (startup_info->have_repository)
1335                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1336         else
1337                 strbuf_addstr(sb, name);
1338         if (name[0] == '-')
1339                 return -1;
1340         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1341         return check_refname_format(sb->buf, 0);
1342 }
1343
1344 /*
1345  * This is like "get_oid_basic()", except it allows "object ID expressions",
1346  * notably "xyz^" for "parent of xyz"
1347  */
1348 int get_oid(const char *name, struct object_id *oid)
1349 {
1350         struct object_context unused;
1351         return get_oid_with_context(name, 0, oid, &unused);
1352 }
1353
1354
1355 /*
1356  * Many callers know that the user meant to name a commit-ish by
1357  * syntactical positions where the object name appears.  Calling this
1358  * function allows the machinery to disambiguate shorter-than-unique
1359  * abbreviated object names between commit-ish and others.
1360  *
1361  * Note that this does NOT error out when the named object is not a
1362  * commit-ish. It is merely to give a hint to the disambiguation
1363  * machinery.
1364  */
1365 int get_oid_committish(const char *name, struct object_id *oid)
1366 {
1367         struct object_context unused;
1368         return get_oid_with_context(name, GET_OID_COMMITTISH,
1369                                     oid, &unused);
1370 }
1371
1372 int get_oid_treeish(const char *name, struct object_id *oid)
1373 {
1374         struct object_context unused;
1375         return get_oid_with_context(name, GET_OID_TREEISH,
1376                                     oid, &unused);
1377 }
1378
1379 int get_oid_commit(const char *name, struct object_id *oid)
1380 {
1381         struct object_context unused;
1382         return get_oid_with_context(name, GET_OID_COMMIT,
1383                                     oid, &unused);
1384 }
1385
1386 int get_oid_tree(const char *name, struct object_id *oid)
1387 {
1388         struct object_context unused;
1389         return get_oid_with_context(name, GET_OID_TREE,
1390                                     oid, &unused);
1391 }
1392
1393 int get_oid_blob(const char *name, struct object_id *oid)
1394 {
1395         struct object_context unused;
1396         return get_oid_with_context(name, GET_OID_BLOB,
1397                                     oid, &unused);
1398 }
1399
1400 /* Must be called only when object_name:filename doesn't exist. */
1401 static void diagnose_invalid_oid_path(const char *prefix,
1402                                       const char *filename,
1403                                       const struct object_id *tree_oid,
1404                                       const char *object_name,
1405                                       int object_name_len)
1406 {
1407         struct object_id oid;
1408         unsigned mode;
1409
1410         if (!prefix)
1411                 prefix = "";
1412
1413         if (file_exists(filename))
1414                 die("Path '%s' exists on disk, but not in '%.*s'.",
1415                     filename, object_name_len, object_name);
1416         if (is_missing_file_error(errno)) {
1417                 char *fullname = xstrfmt("%s%s", prefix, filename);
1418
1419                 if (!get_tree_entry(tree_oid->hash, fullname,
1420                                     oid.hash, &mode)) {
1421                         die("Path '%s' exists, but not '%s'.\n"
1422                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1423                             fullname,
1424                             filename,
1425                             object_name_len, object_name,
1426                             fullname,
1427                             object_name_len, object_name,
1428                             filename);
1429                 }
1430                 die("Path '%s' does not exist in '%.*s'",
1431                     filename, object_name_len, object_name);
1432         }
1433 }
1434
1435 /* Must be called only when :stage:filename doesn't exist. */
1436 static void diagnose_invalid_index_path(int stage,
1437                                         const char *prefix,
1438                                         const char *filename)
1439 {
1440         const struct cache_entry *ce;
1441         int pos;
1442         unsigned namelen = strlen(filename);
1443         struct strbuf fullname = STRBUF_INIT;
1444
1445         if (!prefix)
1446                 prefix = "";
1447
1448         /* Wrong stage number? */
1449         pos = cache_name_pos(filename, namelen);
1450         if (pos < 0)
1451                 pos = -pos - 1;
1452         if (pos < active_nr) {
1453                 ce = active_cache[pos];
1454                 if (ce_namelen(ce) == namelen &&
1455                     !memcmp(ce->name, filename, namelen))
1456                         die("Path '%s' is in the index, but not at stage %d.\n"
1457                             "Did you mean ':%d:%s'?",
1458                             filename, stage,
1459                             ce_stage(ce), filename);
1460         }
1461
1462         /* Confusion between relative and absolute filenames? */
1463         strbuf_addstr(&fullname, prefix);
1464         strbuf_addstr(&fullname, filename);
1465         pos = cache_name_pos(fullname.buf, fullname.len);
1466         if (pos < 0)
1467                 pos = -pos - 1;
1468         if (pos < active_nr) {
1469                 ce = active_cache[pos];
1470                 if (ce_namelen(ce) == fullname.len &&
1471                     !memcmp(ce->name, fullname.buf, fullname.len))
1472                         die("Path '%s' is in the index, but not '%s'.\n"
1473                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1474                             fullname.buf, filename,
1475                             ce_stage(ce), fullname.buf,
1476                             ce_stage(ce), filename);
1477         }
1478
1479         if (file_exists(filename))
1480                 die("Path '%s' exists on disk, but not in the index.", filename);
1481         if (is_missing_file_error(errno))
1482                 die("Path '%s' does not exist (neither on disk nor in the index).",
1483                     filename);
1484
1485         strbuf_release(&fullname);
1486 }
1487
1488
1489 static char *resolve_relative_path(const char *rel)
1490 {
1491         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1492                 return NULL;
1493
1494         if (!is_inside_work_tree())
1495                 die("relative path syntax can't be used outside working tree.");
1496
1497         /* die() inside prefix_path() if resolved path is outside worktree */
1498         return prefix_path(startup_info->prefix,
1499                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1500                            rel);
1501 }
1502
1503 static int get_oid_with_context_1(const char *name,
1504                                   unsigned flags,
1505                                   const char *prefix,
1506                                   struct object_id *oid,
1507                                   struct object_context *oc)
1508 {
1509         int ret, bracket_depth;
1510         int namelen = strlen(name);
1511         const char *cp;
1512         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1513
1514         if (only_to_die)
1515                 flags |= GET_OID_QUIETLY;
1516
1517         memset(oc, 0, sizeof(*oc));
1518         oc->mode = S_IFINVALID;
1519         strbuf_init(&oc->symlink_path, 0);
1520         ret = get_oid_1(name, namelen, oid, flags);
1521         if (!ret)
1522                 return ret;
1523         /*
1524          * sha1:path --> object name of path in ent sha1
1525          * :path -> object name of absolute path in index
1526          * :./path -> object name of path relative to cwd in index
1527          * :[0-3]:path -> object name of path in index at stage
1528          * :/foo -> recent commit matching foo
1529          */
1530         if (name[0] == ':') {
1531                 int stage = 0;
1532                 const struct cache_entry *ce;
1533                 char *new_path = NULL;
1534                 int pos;
1535                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1536                         struct commit_list *list = NULL;
1537
1538                         for_each_ref(handle_one_ref, &list);
1539                         commit_list_sort_by_date(&list);
1540                         return get_oid_oneline(name + 2, oid, list);
1541                 }
1542                 if (namelen < 3 ||
1543                     name[2] != ':' ||
1544                     name[1] < '0' || '3' < name[1])
1545                         cp = name + 1;
1546                 else {
1547                         stage = name[1] - '0';
1548                         cp = name + 3;
1549                 }
1550                 new_path = resolve_relative_path(cp);
1551                 if (!new_path) {
1552                         namelen = namelen - (cp - name);
1553                 } else {
1554                         cp = new_path;
1555                         namelen = strlen(cp);
1556                 }
1557
1558                 if (flags & GET_OID_RECORD_PATH)
1559                         oc->path = xstrdup(cp);
1560
1561                 if (!active_cache)
1562                         read_cache();
1563                 pos = cache_name_pos(cp, namelen);
1564                 if (pos < 0)
1565                         pos = -pos - 1;
1566                 while (pos < active_nr) {
1567                         ce = active_cache[pos];
1568                         if (ce_namelen(ce) != namelen ||
1569                             memcmp(ce->name, cp, namelen))
1570                                 break;
1571                         if (ce_stage(ce) == stage) {
1572                                 oidcpy(oid, &ce->oid);
1573                                 oc->mode = ce->ce_mode;
1574                                 free(new_path);
1575                                 return 0;
1576                         }
1577                         pos++;
1578                 }
1579                 if (only_to_die && name[1] && name[1] != '/')
1580                         diagnose_invalid_index_path(stage, prefix, cp);
1581                 free(new_path);
1582                 return -1;
1583         }
1584         for (cp = name, bracket_depth = 0; *cp; cp++) {
1585                 if (*cp == '{')
1586                         bracket_depth++;
1587                 else if (bracket_depth && *cp == '}')
1588                         bracket_depth--;
1589                 else if (!bracket_depth && *cp == ':')
1590                         break;
1591         }
1592         if (*cp == ':') {
1593                 struct object_id tree_oid;
1594                 int len = cp - name;
1595                 unsigned sub_flags = flags;
1596
1597                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1598                 sub_flags |= GET_OID_TREEISH;
1599
1600                 if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1601                         const char *filename = cp+1;
1602                         char *new_filename = NULL;
1603
1604                         new_filename = resolve_relative_path(filename);
1605                         if (new_filename)
1606                                 filename = new_filename;
1607                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1608                                 ret = get_tree_entry_follow_symlinks(tree_oid.hash,
1609                                         filename, oid->hash, &oc->symlink_path,
1610                                         &oc->mode);
1611                         } else {
1612                                 ret = get_tree_entry(tree_oid.hash, filename,
1613                                                      oid->hash, &oc->mode);
1614                                 if (ret && only_to_die) {
1615                                         diagnose_invalid_oid_path(prefix,
1616                                                                    filename,
1617                                                                    &tree_oid,
1618                                                                    name, len);
1619                                 }
1620                         }
1621                         hashcpy(oc->tree, tree_oid.hash);
1622                         if (flags & GET_OID_RECORD_PATH)
1623                                 oc->path = xstrdup(filename);
1624
1625                         free(new_filename);
1626                         return ret;
1627                 } else {
1628                         if (only_to_die)
1629                                 die("Invalid object name '%.*s'.", len, name);
1630                 }
1631         }
1632         return ret;
1633 }
1634
1635 /*
1636  * Call this function when you know "name" given by the end user must
1637  * name an object but it doesn't; the function _may_ die with a better
1638  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1639  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1640  * you have a chance to diagnose the error further.
1641  */
1642 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1643 {
1644         struct object_context oc;
1645         struct object_id oid;
1646         get_oid_with_context_1(name, GET_OID_ONLY_TO_DIE, prefix, &oid, &oc);
1647 }
1648
1649 int get_oid_with_context(const char *str, unsigned flags, struct object_id *oid, struct object_context *oc)
1650 {
1651         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1652                 die("BUG: incompatible flags for get_sha1_with_context");
1653         return get_oid_with_context_1(str, flags, NULL, oid, oc);
1654 }