git.oblomov.eu Git - git/blob - sha1_name.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "commit.h"
   4 #include "tree.h"
   5 #include "blob.h"
   6 #include "tree-walk.h"
   7 #include "refs.h"
   8 #include "remote.h"
   9 #include "dir.h"
  10
  11 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  12
  13 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
  14
  15 struct disambiguate_state {
  16         disambiguate_hint_fn fn;
  17         void *cb_data;
  18         unsigned char candidate[20];
  19         unsigned candidate_exists:1;
  20         unsigned candidate_checked:1;
  21         unsigned candidate_ok:1;
  22         unsigned disambiguate_fn_used:1;
  23         unsigned ambiguous:1;
  24         unsigned always_call_fn:1;
  25 };
  26
  27 static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
  28 {
  29         if (ds->always_call_fn) {
  30                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  31                 return;
  32         }
  33         if (!ds->candidate_exists) {
  34                 /* this is the first candidate */
  35                 hashcpy(ds->candidate, current);
  36                 ds->candidate_exists = 1;
  37                 return;
  38         } else if (!hashcmp(ds->candidate, current)) {
  39                 /* the same as what we already have seen */
  40                 return;
  41         }
  42
  43         if (!ds->fn) {
  44                 /* cannot disambiguate between ds->candidate and current */
  45                 ds->ambiguous = 1;
  46                 return;
  47         }
  48
  49         if (!ds->candidate_checked) {
  50                 ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
  51                 ds->disambiguate_fn_used = 1;
  52                 ds->candidate_checked = 1;
  53         }
  54
  55         if (!ds->candidate_ok) {
  56                 /* discard the candidate; we know it does not satisfy fn */
  57                 hashcpy(ds->candidate, current);
  58                 ds->candidate_checked = 0;
  59                 return;
  60         }
  61
  62         /* if we reach this point, we know ds->candidate satisfies fn */
  63         if (ds->fn(current, ds->cb_data)) {
  64                 /*
  65                  * if both current and candidate satisfy fn, we cannot
  66                  * disambiguate.
  67                  */
  68                 ds->candidate_ok = 0;
  69                 ds->ambiguous = 1;
  70         }
  71
  72         /* otherwise, current can be discarded and candidate is still good */
  73 }
  74
  75 static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
  76 {
  77         struct alternate_object_database *alt;
  78         char hex[40];
  79         static struct alternate_object_database *fakeent;
  80
  81         if (!fakeent) {
  82                 /*
  83                  * Create a "fake" alternate object database that
  84                  * points to our own object database, to make it
  85                  * easier to get a temporary working space in
  86                  * alt->name/alt->base while iterating over the
  87                  * object databases including our own.
  88                  */
  89                 fakeent = alloc_alt_odb(get_object_directory());
  90         }
  91         fakeent->next = alt_odb_list;
  92
  93         xsnprintf(hex, sizeof(hex), "%.2s", hex_pfx);
  94         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
  95                 struct dirent *de;
  96                 DIR *dir;
  97                 /*
  98                  * every alt_odb struct has 42 extra bytes after the base
  99                  * for exactly this purpose
 100                  */
 101                 xsnprintf(alt->name, 42, "%.2s/", hex_pfx);
 102                 dir = opendir(alt->base);
 103                 if (!dir)
 104                         continue;
 105
 106                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 107                         unsigned char sha1[20];
 108
 109                         if (strlen(de->d_name) != 38)
 110                                 continue;
 111                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 112                                 continue;
 113                         memcpy(hex + 2, de->d_name, 38);
 114                         if (!get_sha1_hex(hex, sha1))
 115                                 update_candidates(ds, sha1);
 116                 }
 117                 closedir(dir);
 118         }
 119 }
 120
 121 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 122 {
 123         do {
 124                 if (*a != *b)
 125                         return 0;
 126                 a++;
 127                 b++;
 128                 len -= 2;
 129         } while (len > 1);
 130         if (len)
 131                 if ((*a ^ *b) & 0xf0)
 132                         return 0;
 133         return 1;
 134 }
 135
 136 static void unique_in_pack(int len,
 137                           const unsigned char *bin_pfx,
 138                            struct packed_git *p,
 139                            struct disambiguate_state *ds)
 140 {
 141         uint32_t num, last, i, first = 0;
 142         const unsigned char *current = NULL;
 143
 144         open_pack_index(p);
 145         num = p->num_objects;
 146         last = num;
 147         while (first < last) {
 148                 uint32_t mid = (first + last) / 2;
 149                 const unsigned char *current;
 150                 int cmp;
 151
 152                 current = nth_packed_object_sha1(p, mid);
 153                 cmp = hashcmp(bin_pfx, current);
 154                 if (!cmp) {
 155                         first = mid;
 156                         break;
 157                 }
 158                 if (cmp > 0) {
 159                         first = mid+1;
 160                         continue;
 161                 }
 162                 last = mid;
 163         }
 164
 165         /*
 166          * At this point, "first" is the location of the lowest object
 167          * with an object name that could match "bin_pfx".  See if we have
 168          * 0, 1 or more objects that actually match(es).
 169          */
 170         for (i = first; i < num && !ds->ambiguous; i++) {
 171                 current = nth_packed_object_sha1(p, i);
 172                 if (!match_sha(len, bin_pfx, current))
 173                         break;
 174                 update_candidates(ds, current);
 175         }
 176 }
 177
 178 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 179                                      struct disambiguate_state *ds)
 180 {
 181         struct packed_git *p;
 182
 183         prepare_packed_git();
 184         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 185                 unique_in_pack(len, bin_pfx, p, ds);
 186 }
 187
 188 #define SHORT_NAME_NOT_FOUND (-1)
 189 #define SHORT_NAME_AMBIGUOUS (-2)
 190
 191 static int finish_object_disambiguation(struct disambiguate_state *ds,
 192                                         unsigned char *sha1)
 193 {
 194         if (ds->ambiguous)
 195                 return SHORT_NAME_AMBIGUOUS;
 196
 197         if (!ds->candidate_exists)
 198                 return SHORT_NAME_NOT_FOUND;
 199
 200         if (!ds->candidate_checked)
 201                 /*
 202                  * If this is the only candidate, there is no point
 203                  * calling the disambiguation hint callback.
 204                  *
 205                  * On the other hand, if the current candidate
 206                  * replaced an earlier candidate that did _not_ pass
 207                  * the disambiguation hint callback, then we do have
 208                  * more than one objects that match the short name
 209                  * given, so we should make sure this one matches;
 210                  * otherwise, if we discovered this one and the one
 211                  * that we previously discarded in the reverse order,
 212                  * we would end up showing different results in the
 213                  * same repository!
 214                  */
 215                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 216                                     ds->fn(ds->candidate, ds->cb_data));
 217
 218         if (!ds->candidate_ok)
 219                 return SHORT_NAME_AMBIGUOUS;
 220
 221         hashcpy(sha1, ds->candidate);
 222         return 0;
 223 }
 224
 225 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 226 {
 227         int kind = sha1_object_info(sha1, NULL);
 228         return kind == OBJ_COMMIT;
 229 }
 230
 231 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 232 {
 233         struct object *obj;
 234         int kind;
 235
 236         kind = sha1_object_info(sha1, NULL);
 237         if (kind == OBJ_COMMIT)
 238                 return 1;
 239         if (kind != OBJ_TAG)
 240                 return 0;
 241
 242         /* We need to do this the hard way... */
 243         obj = deref_tag(parse_object(sha1), NULL, 0);
 244         if (obj && obj->type == OBJ_COMMIT)
 245                 return 1;
 246         return 0;
 247 }
 248
 249 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 250 {
 251         int kind = sha1_object_info(sha1, NULL);
 252         return kind == OBJ_TREE;
 253 }
 254
 255 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 256 {
 257         struct object *obj;
 258         int kind;
 259
 260         kind = sha1_object_info(sha1, NULL);
 261         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 262                 return 1;
 263         if (kind != OBJ_TAG)
 264                 return 0;
 265
 266         /* We need to do this the hard way... */
 267         obj = deref_tag(lookup_object(sha1), NULL, 0);
 268         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 269                 return 1;
 270         return 0;
 271 }
 272
 273 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 274 {
 275         int kind = sha1_object_info(sha1, NULL);
 276         return kind == OBJ_BLOB;
 277 }
 278
 279 static int prepare_prefixes(const char *name, int len,
 280                             unsigned char *bin_pfx,
 281                             char *hex_pfx)
 282 {
 283         int i;
 284
 285         hashclr(bin_pfx);
 286         memset(hex_pfx, 'x', 40);
 287         for (i = 0; i < len ;i++) {
 288                 unsigned char c = name[i];
 289                 unsigned char val;
 290                 if (c >= '0' && c <= '9')
 291                         val = c - '0';
 292                 else if (c >= 'a' && c <= 'f')
 293                         val = c - 'a' + 10;
 294                 else if (c >= 'A' && c <='F') {
 295                         val = c - 'A' + 10;
 296                         c -= 'A' - 'a';
 297                 }
 298                 else
 299                         return -1;
 300                 hex_pfx[i] = c;
 301                 if (!(i & 1))
 302                         val <<= 4;
 303                 bin_pfx[i >> 1] |= val;
 304         }
 305         return 0;
 306 }
 307
 308 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 309                           unsigned flags)
 310 {
 311         int status;
 312         char hex_pfx[40];
 313         unsigned char bin_pfx[20];
 314         struct disambiguate_state ds;
 315         int quietly = !!(flags & GET_SHA1_QUIETLY);
 316
 317         if (len < MINIMUM_ABBREV || len > 40)
 318                 return -1;
 319         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 320                 return -1;
 321
 322         prepare_alt_odb();
 323
 324         memset(&ds, 0, sizeof(ds));
 325         if (flags & GET_SHA1_COMMIT)
 326                 ds.fn = disambiguate_commit_only;
 327         else if (flags & GET_SHA1_COMMITTISH)
 328                 ds.fn = disambiguate_committish_only;
 329         else if (flags & GET_SHA1_TREE)
 330                 ds.fn = disambiguate_tree_only;
 331         else if (flags & GET_SHA1_TREEISH)
 332                 ds.fn = disambiguate_treeish_only;
 333         else if (flags & GET_SHA1_BLOB)
 334                 ds.fn = disambiguate_blob_only;
 335
 336         find_short_object_filename(len, hex_pfx, &ds);
 337         find_short_packed_object(len, bin_pfx, &ds);
 338         status = finish_object_disambiguation(&ds, sha1);
 339
 340         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 341                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 342         return status;
 343 }
 344
 345 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 346 {
 347         char hex_pfx[40];
 348         unsigned char bin_pfx[20];
 349         struct disambiguate_state ds;
 350         int len = strlen(prefix);
 351
 352         if (len < MINIMUM_ABBREV || len > 40)
 353                 return -1;
 354         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 355                 return -1;
 356
 357         prepare_alt_odb();
 358
 359         memset(&ds, 0, sizeof(ds));
 360         ds.always_call_fn = 1;
 361         ds.cb_data = cb_data;
 362         ds.fn = fn;
 363
 364         find_short_object_filename(len, hex_pfx, &ds);
 365         find_short_packed_object(len, bin_pfx, &ds);
 366         return ds.ambiguous;
 367 }
 368
 369 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 370 {
 371         int status, exists;
 372
 373         sha1_to_hex_r(hex, sha1);
 374         if (len == 40 || !len)
 375                 return 40;
 376         exists = has_sha1_file(sha1);
 377         while (len < 40) {
 378                 unsigned char sha1_ret[20];
 379                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 380                 if (exists
 381                     ? !status
 382                     : status == SHORT_NAME_NOT_FOUND) {
 383                         hex[len] = 0;
 384                         return len;
 385                 }
 386                 len++;
 387         }
 388         return len;
 389 }
 390
 391 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 392 {
 393         static char hex[GIT_SHA1_HEXSZ + 1];
 394         find_unique_abbrev_r(hex, sha1, len);
 395         return hex;
 396 }
 397
 398 static int ambiguous_path(const char *path, int len)
 399 {
 400         int slash = 1;
 401         int cnt;
 402
 403         for (cnt = 0; cnt < len; cnt++) {
 404                 switch (*path++) {
 405                 case '\0':
 406                         break;
 407                 case '/':
 408                         if (slash)
 409                                 break;
 410                         slash = 1;
 411                         continue;
 412                 case '.':
 413                         continue;
 414                 default:
 415                         slash = 0;
 416                         continue;
 417                 }
 418                 break;
 419         }
 420         return slash;
 421 }
 422
 423 static inline int at_mark(const char *string, int len,
 424                           const char **suffix, int nr)
 425 {
 426         int i;
 427
 428         for (i = 0; i < nr; i++) {
 429                 int suffix_len = strlen(suffix[i]);
 430                 if (suffix_len <= len
 431                     && !memcmp(string, suffix[i], suffix_len))
 432                         return suffix_len;
 433         }
 434         return 0;
 435 }
 436
 437 static inline int upstream_mark(const char *string, int len)
 438 {
 439         const char *suffix[] = { "@{upstream}", "@{u}" };
 440         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 441 }
 442
 443 static inline int push_mark(const char *string, int len)
 444 {
 445         const char *suffix[] = { "@{push}" };
 446         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 447 }
 448
 449 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 450 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 451
 452 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 453                           unsigned int flags)
 454 {
 455         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 456         static const char *object_name_msg = N_(
 457         "Git normally never creates a ref that ends with 40 hex characters\n"
 458         "because it will be ignored when you just specify 40-hex. These refs\n"
 459         "may be created by mistake. For example,\n"
 460         "\n"
 461         "  git checkout -b $br $(git rev-parse ...)\n"
 462         "\n"
 463         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 464         "examine these refs and maybe delete them. Turn this message off by\n"
 465         "running \"git config advice.objectNameWarning false\"");
 466         unsigned char tmp_sha1[20];
 467         char *real_ref = NULL;
 468         int refs_found = 0;
 469         int at, reflog_len, nth_prior = 0;
 470
 471         if (len == 40 && !get_sha1_hex(str, sha1)) {
 472                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 473                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 474                         if (refs_found > 0) {
 475                                 warning(warn_msg, len, str);
 476                                 if (advice_object_name_warning)
 477                                         fprintf(stderr, "%s\n", _(object_name_msg));
 478                         }
 479                         free(real_ref);
 480                 }
 481                 return 0;
 482         }
 483
 484         /* basic@{time or number or -number} format to query ref-log */
 485         reflog_len = at = 0;
 486         if (len && str[len-1] == '}') {
 487                 for (at = len-4; at >= 0; at--) {
 488                         if (str[at] == '@' && str[at+1] == '{') {
 489                                 if (str[at+2] == '-') {
 490                                         if (at != 0)
 491                                                 /* @{-N} not at start */
 492                                                 return -1;
 493                                         nth_prior = 1;
 494                                         continue;
 495                                 }
 496                                 if (!upstream_mark(str + at, len - at) &&
 497                                     !push_mark(str + at, len - at)) {
 498                                         reflog_len = (len-1) - (at+2);
 499                                         len = at;
 500                                 }
 501                                 break;
 502                         }
 503                 }
 504         }
 505
 506         /* Accept only unambiguous ref paths. */
 507         if (len && ambiguous_path(str, len))
 508                 return -1;
 509
 510         if (nth_prior) {
 511                 struct strbuf buf = STRBUF_INIT;
 512                 int detached;
 513
 514                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 515                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 516                         strbuf_release(&buf);
 517                         if (detached)
 518                                 return 0;
 519                 }
 520         }
 521
 522         if (!len && reflog_len)
 523                 /* allow "@{...}" to mean the current branch reflog */
 524                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 525         else if (reflog_len)
 526                 refs_found = dwim_log(str, len, sha1, &real_ref);
 527         else
 528                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 529
 530         if (!refs_found)
 531                 return -1;
 532
 533         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 534             (refs_found > 1 ||
 535              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 536                 warning(warn_msg, len, str);
 537
 538         if (reflog_len) {
 539                 int nth, i;
 540                 unsigned long at_time;
 541                 unsigned long co_time;
 542                 int co_tz, co_cnt;
 543
 544                 /* Is it asking for N-th entry, or approxidate? */
 545                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 546                         char ch = str[at+2+i];
 547                         if ('0' <= ch && ch <= '9')
 548                                 nth = nth * 10 + ch - '0';
 549                         else
 550                                 nth = -1;
 551                 }
 552                 if (100000000 <= nth) {
 553                         at_time = nth;
 554                         nth = -1;
 555                 } else if (0 <= nth)
 556                         at_time = 0;
 557                 else {
 558                         int errors = 0;
 559                         char *tmp = xstrndup(str + at + 2, reflog_len);
 560                         at_time = approxidate_careful(tmp, &errors);
 561                         free(tmp);
 562                         if (errors) {
 563                                 free(real_ref);
 564                                 return -1;
 565                         }
 566                 }
 567                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 568                                 &co_time, &co_tz, &co_cnt)) {
 569                         if (!len) {
 570                                 if (starts_with(real_ref, "refs/heads/")) {
 571                                         str = real_ref + 11;
 572                                         len = strlen(real_ref + 11);
 573                                 } else {
 574                                         /* detached HEAD */
 575                                         str = "HEAD";
 576                                         len = 4;
 577                                 }
 578                         }
 579                         if (at_time) {
 580                                 if (!(flags & GET_SHA1_QUIETLY)) {
 581                                         warning("Log for '%.*s' only goes "
 582                                                 "back to %s.", len, str,
 583                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 584                                 }
 585                         } else {
 586                                 if (flags & GET_SHA1_QUIETLY) {
 587                                         exit(128);
 588                                 }
 589                                 die("Log for '%.*s' only has %d entries.",
 590                                     len, str, co_cnt);
 591                         }
 592                 }
 593         }
 594
 595         free(real_ref);
 596         return 0;
 597 }
 598
 599 static int get_parent(const char *name, int len,
 600                       unsigned char *result, int idx)
 601 {
 602         unsigned char sha1[20];
 603         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 604         struct commit *commit;
 605         struct commit_list *p;
 606
 607         if (ret)
 608                 return ret;
 609         commit = lookup_commit_reference(sha1);
 610         if (parse_commit(commit))
 611                 return -1;
 612         if (!idx) {
 613                 hashcpy(result, commit->object.oid.hash);
 614                 return 0;
 615         }
 616         p = commit->parents;
 617         while (p) {
 618                 if (!--idx) {
 619                         hashcpy(result, p->item->object.oid.hash);
 620                         return 0;
 621                 }
 622                 p = p->next;
 623         }
 624         return -1;
 625 }
 626
 627 static int get_nth_ancestor(const char *name, int len,
 628                             unsigned char *result, int generation)
 629 {
 630         unsigned char sha1[20];
 631         struct commit *commit;
 632         int ret;
 633
 634         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 635         if (ret)
 636                 return ret;
 637         commit = lookup_commit_reference(sha1);
 638         if (!commit)
 639                 return -1;
 640
 641         while (generation--) {
 642                 if (parse_commit(commit) || !commit->parents)
 643                         return -1;
 644                 commit = commit->parents->item;
 645         }
 646         hashcpy(result, commit->object.oid.hash);
 647         return 0;
 648 }
 649
 650 struct object *peel_to_type(const char *name, int namelen,
 651                             struct object *o, enum object_type expected_type)
 652 {
 653         if (name && !namelen)
 654                 namelen = strlen(name);
 655         while (1) {
 656                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 657                         return NULL;
 658                 if (expected_type == OBJ_ANY || o->type == expected_type)
 659                         return o;
 660                 if (o->type == OBJ_TAG)
 661                         o = ((struct tag*) o)->tagged;
 662                 else if (o->type == OBJ_COMMIT)
 663                         o = &(((struct commit *) o)->tree->object);
 664                 else {
 665                         if (name)
 666                                 error("%.*s: expected %s type, but the object "
 667                                       "dereferences to %s type",
 668                                       namelen, name, typename(expected_type),
 669                                       typename(o->type));
 670                         return NULL;
 671                 }
 672         }
 673 }
 674
 675 static int peel_onion(const char *name, int len, unsigned char *sha1)
 676 {
 677         unsigned char outer[20];
 678         const char *sp;
 679         unsigned int expected_type = 0;
 680         unsigned lookup_flags = 0;
 681         struct object *o;
 682
 683         /*
 684          * "ref^{type}" dereferences ref repeatedly until you cannot
 685          * dereference anymore, or you get an object of given type,
 686          * whichever comes first.  "ref^{}" means just dereference
 687          * tags until you get a non-tag.  "ref^0" is a shorthand for
 688          * "ref^{commit}".  "commit^{tree}" could be used to find the
 689          * top-level tree of the given commit.
 690          */
 691         if (len < 4 || name[len-1] != '}')
 692                 return -1;
 693
 694         for (sp = name + len - 1; name <= sp; sp--) {
 695                 int ch = *sp;
 696                 if (ch == '{' && name < sp && sp[-1] == '^')
 697                         break;
 698         }
 699         if (sp <= name)
 700                 return -1;
 701
 702         sp++; /* beginning of type name, or closing brace for empty */
 703         if (starts_with(sp, "commit}"))
 704                 expected_type = OBJ_COMMIT;
 705         else if (starts_with(sp, "tag}"))
 706                 expected_type = OBJ_TAG;
 707         else if (starts_with(sp, "tree}"))
 708                 expected_type = OBJ_TREE;
 709         else if (starts_with(sp, "blob}"))
 710                 expected_type = OBJ_BLOB;
 711         else if (starts_with(sp, "object}"))
 712                 expected_type = OBJ_ANY;
 713         else if (sp[0] == '}')
 714                 expected_type = OBJ_NONE;
 715         else if (sp[0] == '/')
 716                 expected_type = OBJ_COMMIT;
 717         else
 718                 return -1;
 719
 720         if (expected_type == OBJ_COMMIT)
 721                 lookup_flags = GET_SHA1_COMMITTISH;
 722         else if (expected_type == OBJ_TREE)
 723                 lookup_flags = GET_SHA1_TREEISH;
 724
 725         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 726                 return -1;
 727
 728         o = parse_object(outer);
 729         if (!o)
 730                 return -1;
 731         if (!expected_type) {
 732                 o = deref_tag(o, name, sp - name - 2);
 733                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 734                         return -1;
 735                 hashcpy(sha1, o->oid.hash);
 736                 return 0;
 737         }
 738
 739         /*
 740          * At this point, the syntax look correct, so
 741          * if we do not get the needed object, we should
 742          * barf.
 743          */
 744         o = peel_to_type(name, len, o, expected_type);
 745         if (!o)
 746                 return -1;
 747
 748         hashcpy(sha1, o->oid.hash);
 749         if (sp[0] == '/') {
 750                 /* "$commit^{/foo}" */
 751                 char *prefix;
 752                 int ret;
 753                 struct commit_list *list = NULL;
 754
 755                 /*
 756                  * $commit^{/}. Some regex implementation may reject.
 757                  * We don't need regex anyway. '' pattern always matches.
 758                  */
 759                 if (sp[1] == '}')
 760                         return 0;
 761
 762                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 763                 commit_list_insert((struct commit *)o, &list);
 764                 ret = get_sha1_oneline(prefix, sha1, list);
 765                 free(prefix);
 766                 return ret;
 767         }
 768         return 0;
 769 }
 770
 771 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 772 {
 773         const char *cp;
 774         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 775
 776         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 777                 char ch = *cp;
 778                 if (!isxdigit(ch)) {
 779                         /* We must be looking at g in "SOMETHING-g"
 780                          * for it to be describe output.
 781                          */
 782                         if (ch == 'g' && cp[-1] == '-') {
 783                                 cp++;
 784                                 len -= cp - name;
 785                                 return get_short_sha1(cp, len, sha1, flags);
 786                         }
 787                 }
 788         }
 789         return -1;
 790 }
 791
 792 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 793 {
 794         int ret, has_suffix;
 795         const char *cp;
 796
 797         /*
 798          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 799          */
 800         has_suffix = 0;
 801         for (cp = name + len - 1; name <= cp; cp--) {
 802                 int ch = *cp;
 803                 if ('0' <= ch && ch <= '9')
 804                         continue;
 805                 if (ch == '~' || ch == '^')
 806                         has_suffix = ch;
 807                 break;
 808         }
 809
 810         if (has_suffix) {
 811                 int num = 0;
 812                 int len1 = cp - name;
 813                 cp++;
 814                 while (cp < name + len)
 815                         num = num * 10 + *cp++ - '0';
 816                 if (!num && len1 == len - 1)
 817                         num = 1;
 818                 if (has_suffix == '^')
 819                         return get_parent(name, len1, sha1, num);
 820                 /* else if (has_suffix == '~') -- goes without saying */
 821                 return get_nth_ancestor(name, len1, sha1, num);
 822         }
 823
 824         ret = peel_onion(name, len, sha1);
 825         if (!ret)
 826                 return 0;
 827
 828         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 829         if (!ret)
 830                 return 0;
 831
 832         /* It could be describe output that is "SOMETHING-gXXXX" */
 833         ret = get_describe_name(name, len, sha1);
 834         if (!ret)
 835                 return 0;
 836
 837         return get_short_sha1(name, len, sha1, lookup_flags);
 838 }
 839
 840 /*
 841  * This interprets names like ':/Initial revision of "git"' by searching
 842  * through history and returning the first commit whose message starts
 843  * the given regular expression.
 844  *
 845  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 846  *
 847  * For a literal '!' character at the beginning of a pattern, you have to repeat
 848  * that, like: ':/!!foo'
 849  *
 850  * For future extension, all other sequences beginning with ':/!' are reserved.
 851  */
 852
 853 /* Remember to update object flag allocation in object.h */
 854 #define ONELINE_SEEN (1u<<20)
 855
 856 static int handle_one_ref(const char *path, const struct object_id *oid,
 857                           int flag, void *cb_data)
 858 {
 859         struct commit_list **list = cb_data;
 860         struct object *object = parse_object(oid->hash);
 861         if (!object)
 862                 return 0;
 863         if (object->type == OBJ_TAG) {
 864                 object = deref_tag(object, path, strlen(path));
 865                 if (!object)
 866                         return 0;
 867         }
 868         if (object->type != OBJ_COMMIT)
 869                 return 0;
 870         commit_list_insert((struct commit *)object, list);
 871         return 0;
 872 }
 873
 874 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 875                             struct commit_list *list)
 876 {
 877         struct commit_list *backup = NULL, *l;
 878         int found = 0;
 879         int negative = 0;
 880         regex_t regex;
 881
 882         if (prefix[0] == '!') {
 883                 prefix++;
 884
 885                 if (prefix[0] == '-') {
 886                         prefix++;
 887                         negative = 1;
 888                 } else if (prefix[0] != '!') {
 889                         return -1;
 890                 }
 891         }
 892
 893         if (regcomp(&regex, prefix, REG_EXTENDED))
 894                 return -1;
 895
 896         for (l = list; l; l = l->next) {
 897                 l->item->object.flags |= ONELINE_SEEN;
 898                 commit_list_insert(l->item, &backup);
 899         }
 900         while (list) {
 901                 const char *p, *buf;
 902                 struct commit *commit;
 903                 int matches;
 904
 905                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 906                 if (!parse_object(commit->object.oid.hash))
 907                         continue;
 908                 buf = get_commit_buffer(commit, NULL);
 909                 p = strstr(buf, "\n\n");
 910                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
 911                 unuse_commit_buffer(commit, buf);
 912
 913                 if (matches) {
 914                         hashcpy(sha1, commit->object.oid.hash);
 915                         found = 1;
 916                         break;
 917                 }
 918         }
 919         regfree(&regex);
 920         free_commit_list(list);
 921         for (l = backup; l; l = l->next)
 922                 clear_commit_marks(l->item, ONELINE_SEEN);
 923         free_commit_list(backup);
 924         return found ? 0 : -1;
 925 }
 926
 927 struct grab_nth_branch_switch_cbdata {
 928         int remaining;
 929         struct strbuf buf;
 930 };
 931
 932 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 933                                   const char *email, unsigned long timestamp, int tz,
 934                                   const char *message, void *cb_data)
 935 {
 936         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 937         const char *match = NULL, *target = NULL;
 938         size_t len;
 939
 940         if (skip_prefix(message, "checkout: moving from ", &match))
 941                 target = strstr(match, " to ");
 942
 943         if (!match || !target)
 944                 return 0;
 945         if (--(cb->remaining) == 0) {
 946                 len = target - match;
 947                 strbuf_reset(&cb->buf);
 948                 strbuf_add(&cb->buf, match, len);
 949                 return 1; /* we are done */
 950         }
 951         return 0;
 952 }
 953
 954 /*
 955  * Parse @{-N} syntax, return the number of characters parsed
 956  * if successful; otherwise signal an error with negative value.
 957  */
 958 static int interpret_nth_prior_checkout(const char *name, int namelen,
 959                                         struct strbuf *buf)
 960 {
 961         long nth;
 962         int retval;
 963         struct grab_nth_branch_switch_cbdata cb;
 964         const char *brace;
 965         char *num_end;
 966
 967         if (namelen < 4)
 968                 return -1;
 969         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 970                 return -1;
 971         brace = memchr(name, '}', namelen);
 972         if (!brace)
 973                 return -1;
 974         nth = strtol(name + 3, &num_end, 10);
 975         if (num_end != brace)
 976                 return -1;
 977         if (nth <= 0)
 978                 return -1;
 979         cb.remaining = nth;
 980         strbuf_init(&cb.buf, 20);
 981
 982         retval = 0;
 983         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 984                 strbuf_reset(buf);
 985                 strbuf_addbuf(buf, &cb.buf);
 986                 retval = brace - name + 1;
 987         }
 988
 989         strbuf_release(&cb.buf);
 990         return retval;
 991 }
 992
 993 int get_oid_mb(const char *name, struct object_id *oid)
 994 {
 995         struct commit *one, *two;
 996         struct commit_list *mbs;
 997         struct object_id oid_tmp;
 998         const char *dots;
 999         int st;
1000
1001         dots = strstr(name, "...");
1002         if (!dots)
1003                 return get_oid(name, oid);
1004         if (dots == name)
1005                 st = get_oid("HEAD", &oid_tmp);
1006         else {
1007                 struct strbuf sb;
1008                 strbuf_init(&sb, dots - name);
1009                 strbuf_add(&sb, name, dots - name);
1010                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1011                 strbuf_release(&sb);
1012         }
1013         if (st)
1014                 return st;
1015         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1016         if (!one)
1017                 return -1;
1018
1019         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1020                 return -1;
1021         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1022         if (!two)
1023                 return -1;
1024         mbs = get_merge_bases(one, two);
1025         if (!mbs || mbs->next)
1026                 st = -1;
1027         else {
1028                 st = 0;
1029                 oidcpy(oid, &mbs->item->object.oid);
1030         }
1031         free_commit_list(mbs);
1032         return st;
1033 }
1034
1035 /* parse @something syntax, when 'something' is not {.*} */
1036 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1037 {
1038         const char *next;
1039
1040         if (len || name[1] == '{')
1041                 return -1;
1042
1043         /* make sure it's a single @, or @@{.*}, not @foo */
1044         next = memchr(name + len + 1, '@', namelen - len - 1);
1045         if (next && next[1] != '{')
1046                 return -1;
1047         if (!next)
1048                 next = name + namelen;
1049         if (next != name + 1)
1050                 return -1;
1051
1052         strbuf_reset(buf);
1053         strbuf_add(buf, "HEAD", 4);
1054         return 1;
1055 }
1056
1057 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1058 {
1059         /* we have extra data, which might need further processing */
1060         struct strbuf tmp = STRBUF_INIT;
1061         int used = buf->len;
1062         int ret;
1063
1064         strbuf_add(buf, name + len, namelen - len);
1065         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1066         /* that data was not interpreted, remove our cruft */
1067         if (ret < 0) {
1068                 strbuf_setlen(buf, used);
1069                 return len;
1070         }
1071         strbuf_reset(buf);
1072         strbuf_addbuf(buf, &tmp);
1073         strbuf_release(&tmp);
1074         /* tweak for size of {-N} versus expanded ref name */
1075         return ret - used + len;
1076 }
1077
1078 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1079 {
1080         char *s = shorten_unambiguous_ref(ref, 0);
1081         strbuf_reset(buf);
1082         strbuf_addstr(buf, s);
1083         free(s);
1084 }
1085
1086 static int interpret_branch_mark(const char *name, int namelen,
1087                                  int at, struct strbuf *buf,
1088                                  int (*get_mark)(const char *, int),
1089                                  const char *(*get_data)(struct branch *,
1090                                                          struct strbuf *))
1091 {
1092         int len;
1093         struct branch *branch;
1094         struct strbuf err = STRBUF_INIT;
1095         const char *value;
1096
1097         len = get_mark(name + at, namelen - at);
1098         if (!len)
1099                 return -1;
1100
1101         if (memchr(name, ':', at))
1102                 return -1;
1103
1104         if (at) {
1105                 char *name_str = xmemdupz(name, at);
1106                 branch = branch_get(name_str);
1107                 free(name_str);
1108         } else
1109                 branch = branch_get(NULL);
1110
1111         value = get_data(branch, &err);
1112         if (!value)
1113                 die("%s", err.buf);
1114
1115         set_shortened_ref(buf, value);
1116         return len + at;
1117 }
1118
1119 /*
1120  * This reads short-hand syntax that not only evaluates to a commit
1121  * object name, but also can act as if the end user spelled the name
1122  * of the branch from the command line.
1123  *
1124  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1125  *   places the name of the branch in the given buf and returns the
1126  *   number of characters parsed if successful.
1127  *
1128  * - "<branch>@{upstream}" finds the name of the other ref that
1129  *   <branch> is configured to merge with (missing <branch> defaults
1130  *   to the current branch), and places the name of the branch in the
1131  *   given buf and returns the number of characters parsed if
1132  *   successful.
1133  *
1134  * If the input is not of the accepted format, it returns a negative
1135  * number to signal an error.
1136  *
1137  * If the input was ok but there are not N branch switches in the
1138  * reflog, it returns 0.
1139  */
1140 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1141 {
1142         char *at;
1143         const char *start;
1144         int len = interpret_nth_prior_checkout(name, namelen, buf);
1145
1146         if (!namelen)
1147                 namelen = strlen(name);
1148
1149         if (!len) {
1150                 return len; /* syntax Ok, not enough switches */
1151         } else if (len > 0) {
1152                 if (len == namelen)
1153                         return len; /* consumed all */
1154                 else
1155                         return reinterpret(name, namelen, len, buf);
1156         }
1157
1158         for (start = name;
1159              (at = memchr(start, '@', namelen - (start - name)));
1160              start = at + 1) {
1161
1162                 len = interpret_empty_at(name, namelen, at - name, buf);
1163                 if (len > 0)
1164                         return reinterpret(name, namelen, len, buf);
1165
1166                 len = interpret_branch_mark(name, namelen, at - name, buf,
1167                                             upstream_mark, branch_get_upstream);
1168                 if (len > 0)
1169                         return len;
1170
1171                 len = interpret_branch_mark(name, namelen, at - name, buf,
1172                                             push_mark, branch_get_push);
1173                 if (len > 0)
1174                         return len;
1175         }
1176
1177         return -1;
1178 }
1179
1180 int strbuf_branchname(struct strbuf *sb, const char *name)
1181 {
1182         int len = strlen(name);
1183         int used = interpret_branch_name(name, len, sb);
1184
1185         if (used == len)
1186                 return 0;
1187         if (used < 0)
1188                 used = 0;
1189         strbuf_add(sb, name + used, len - used);
1190         return len;
1191 }
1192
1193 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1194 {
1195         strbuf_branchname(sb, name);
1196         if (name[0] == '-')
1197                 return -1;
1198         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1199         return check_refname_format(sb->buf, 0);
1200 }
1201
1202 /*
1203  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1204  * notably "xyz^" for "parent of xyz"
1205  */
1206 int get_sha1(const char *name, unsigned char *sha1)
1207 {
1208         struct object_context unused;
1209         return get_sha1_with_context(name, 0, sha1, &unused);
1210 }
1211
1212 /*
1213  * This is like "get_sha1()", but for struct object_id.
1214  */
1215 int get_oid(const char *name, struct object_id *oid)
1216 {
1217         return get_sha1(name, oid->hash);
1218 }
1219
1220
1221 /*
1222  * Many callers know that the user meant to name a commit-ish by
1223  * syntactical positions where the object name appears.  Calling this
1224  * function allows the machinery to disambiguate shorter-than-unique
1225  * abbreviated object names between commit-ish and others.
1226  *
1227  * Note that this does NOT error out when the named object is not a
1228  * commit-ish. It is merely to give a hint to the disambiguation
1229  * machinery.
1230  */
1231 int get_sha1_committish(const char *name, unsigned char *sha1)
1232 {
1233         struct object_context unused;
1234         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1235                                      sha1, &unused);
1236 }
1237
1238 int get_sha1_treeish(const char *name, unsigned char *sha1)
1239 {
1240         struct object_context unused;
1241         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1242                                      sha1, &unused);
1243 }
1244
1245 int get_sha1_commit(const char *name, unsigned char *sha1)
1246 {
1247         struct object_context unused;
1248         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1249                                      sha1, &unused);
1250 }
1251
1252 int get_sha1_tree(const char *name, unsigned char *sha1)
1253 {
1254         struct object_context unused;
1255         return get_sha1_with_context(name, GET_SHA1_TREE,
1256                                      sha1, &unused);
1257 }
1258
1259 int get_sha1_blob(const char *name, unsigned char *sha1)
1260 {
1261         struct object_context unused;
1262         return get_sha1_with_context(name, GET_SHA1_BLOB,
1263                                      sha1, &unused);
1264 }
1265
1266 /* Must be called only when object_name:filename doesn't exist. */
1267 static void diagnose_invalid_sha1_path(const char *prefix,
1268                                        const char *filename,
1269                                        const unsigned char *tree_sha1,
1270                                        const char *object_name,
1271                                        int object_name_len)
1272 {
1273         unsigned char sha1[20];
1274         unsigned mode;
1275
1276         if (!prefix)
1277                 prefix = "";
1278
1279         if (file_exists(filename))
1280                 die("Path '%s' exists on disk, but not in '%.*s'.",
1281                     filename, object_name_len, object_name);
1282         if (errno == ENOENT || errno == ENOTDIR) {
1283                 char *fullname = xstrfmt("%s%s", prefix, filename);
1284
1285                 if (!get_tree_entry(tree_sha1, fullname,
1286                                     sha1, &mode)) {
1287                         die("Path '%s' exists, but not '%s'.\n"
1288                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1289                             fullname,
1290                             filename,
1291                             object_name_len, object_name,
1292                             fullname,
1293                             object_name_len, object_name,
1294                             filename);
1295                 }
1296                 die("Path '%s' does not exist in '%.*s'",
1297                     filename, object_name_len, object_name);
1298         }
1299 }
1300
1301 /* Must be called only when :stage:filename doesn't exist. */
1302 static void diagnose_invalid_index_path(int stage,
1303                                         const char *prefix,
1304                                         const char *filename)
1305 {
1306         const struct cache_entry *ce;
1307         int pos;
1308         unsigned namelen = strlen(filename);
1309         struct strbuf fullname = STRBUF_INIT;
1310
1311         if (!prefix)
1312                 prefix = "";
1313
1314         /* Wrong stage number? */
1315         pos = cache_name_pos(filename, namelen);
1316         if (pos < 0)
1317                 pos = -pos - 1;
1318         if (pos < active_nr) {
1319                 ce = active_cache[pos];
1320                 if (ce_namelen(ce) == namelen &&
1321                     !memcmp(ce->name, filename, namelen))
1322                         die("Path '%s' is in the index, but not at stage %d.\n"
1323                             "Did you mean ':%d:%s'?",
1324                             filename, stage,
1325                             ce_stage(ce), filename);
1326         }
1327
1328         /* Confusion between relative and absolute filenames? */
1329         strbuf_addstr(&fullname, prefix);
1330         strbuf_addstr(&fullname, filename);
1331         pos = cache_name_pos(fullname.buf, fullname.len);
1332         if (pos < 0)
1333                 pos = -pos - 1;
1334         if (pos < active_nr) {
1335                 ce = active_cache[pos];
1336                 if (ce_namelen(ce) == fullname.len &&
1337                     !memcmp(ce->name, fullname.buf, fullname.len))
1338                         die("Path '%s' is in the index, but not '%s'.\n"
1339                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1340                             fullname.buf, filename,
1341                             ce_stage(ce), fullname.buf,
1342                             ce_stage(ce), filename);
1343         }
1344
1345         if (file_exists(filename))
1346                 die("Path '%s' exists on disk, but not in the index.", filename);
1347         if (errno == ENOENT || errno == ENOTDIR)
1348                 die("Path '%s' does not exist (neither on disk nor in the index).",
1349                     filename);
1350
1351         strbuf_release(&fullname);
1352 }
1353
1354
1355 static char *resolve_relative_path(const char *rel)
1356 {
1357         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1358                 return NULL;
1359
1360         if (!is_inside_work_tree())
1361                 die("relative path syntax can't be used outside working tree.");
1362
1363         /* die() inside prefix_path() if resolved path is outside worktree */
1364         return prefix_path(startup_info->prefix,
1365                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1366                            rel);
1367 }
1368
1369 static int get_sha1_with_context_1(const char *name,
1370                                    unsigned flags,
1371                                    const char *prefix,
1372                                    unsigned char *sha1,
1373                                    struct object_context *oc)
1374 {
1375         int ret, bracket_depth;
1376         int namelen = strlen(name);
1377         const char *cp;
1378         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1379
1380         memset(oc, 0, sizeof(*oc));
1381         oc->mode = S_IFINVALID;
1382         ret = get_sha1_1(name, namelen, sha1, flags);
1383         if (!ret)
1384                 return ret;
1385         /*
1386          * sha1:path --> object name of path in ent sha1
1387          * :path -> object name of absolute path in index
1388          * :./path -> object name of path relative to cwd in index
1389          * :[0-3]:path -> object name of path in index at stage
1390          * :/foo -> recent commit matching foo
1391          */
1392         if (name[0] == ':') {
1393                 int stage = 0;
1394                 const struct cache_entry *ce;
1395                 char *new_path = NULL;
1396                 int pos;
1397                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1398                         struct commit_list *list = NULL;
1399
1400                         for_each_ref(handle_one_ref, &list);
1401                         commit_list_sort_by_date(&list);
1402                         return get_sha1_oneline(name + 2, sha1, list);
1403                 }
1404                 if (namelen < 3 ||
1405                     name[2] != ':' ||
1406                     name[1] < '0' || '3' < name[1])
1407                         cp = name + 1;
1408                 else {
1409                         stage = name[1] - '0';
1410                         cp = name + 3;
1411                 }
1412                 new_path = resolve_relative_path(cp);
1413                 if (!new_path) {
1414                         namelen = namelen - (cp - name);
1415                 } else {
1416                         cp = new_path;
1417                         namelen = strlen(cp);
1418                 }
1419
1420                 strlcpy(oc->path, cp, sizeof(oc->path));
1421
1422                 if (!active_cache)
1423                         read_cache();
1424                 pos = cache_name_pos(cp, namelen);
1425                 if (pos < 0)
1426                         pos = -pos - 1;
1427                 while (pos < active_nr) {
1428                         ce = active_cache[pos];
1429                         if (ce_namelen(ce) != namelen ||
1430                             memcmp(ce->name, cp, namelen))
1431                                 break;
1432                         if (ce_stage(ce) == stage) {
1433                                 hashcpy(sha1, ce->oid.hash);
1434                                 oc->mode = ce->ce_mode;
1435                                 free(new_path);
1436                                 return 0;
1437                         }
1438                         pos++;
1439                 }
1440                 if (only_to_die && name[1] && name[1] != '/')
1441                         diagnose_invalid_index_path(stage, prefix, cp);
1442                 free(new_path);
1443                 return -1;
1444         }
1445         for (cp = name, bracket_depth = 0; *cp; cp++) {
1446                 if (*cp == '{')
1447                         bracket_depth++;
1448                 else if (bracket_depth && *cp == '}')
1449                         bracket_depth--;
1450                 else if (!bracket_depth && *cp == ':')
1451                         break;
1452         }
1453         if (*cp == ':') {
1454                 unsigned char tree_sha1[20];
1455                 int len = cp - name;
1456                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1457                         const char *filename = cp+1;
1458                         char *new_filename = NULL;
1459
1460                         new_filename = resolve_relative_path(filename);
1461                         if (new_filename)
1462                                 filename = new_filename;
1463                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1464                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1465                                         filename, sha1, &oc->symlink_path,
1466                                         &oc->mode);
1467                         } else {
1468                                 ret = get_tree_entry(tree_sha1, filename,
1469                                                      sha1, &oc->mode);
1470                                 if (ret && only_to_die) {
1471                                         diagnose_invalid_sha1_path(prefix,
1472                                                                    filename,
1473                                                                    tree_sha1,
1474                                                                    name, len);
1475                                 }
1476                         }
1477                         hashcpy(oc->tree, tree_sha1);
1478                         strlcpy(oc->path, filename, sizeof(oc->path));
1479
1480                         free(new_filename);
1481                         return ret;
1482                 } else {
1483                         if (only_to_die)
1484                                 die("Invalid object name '%.*s'.", len, name);
1485                 }
1486         }
1487         return ret;
1488 }
1489
1490 /*
1491  * Call this function when you know "name" given by the end user must
1492  * name an object but it doesn't; the function _may_ die with a better
1493  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1494  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1495  * you have a chance to diagnose the error further.
1496  */
1497 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1498 {
1499         struct object_context oc;
1500         unsigned char sha1[20];
1501         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1502 }
1503
1504 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1505 {
1506         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1507                 die("BUG: incompatible flags for get_sha1_with_context");
1508         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1509 }