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                 const char *objdir = get_object_directory();
  90                 int objdir_len = strlen(objdir);
  91                 int entlen = objdir_len + 43;
  92                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
  93                 memcpy(fakeent->base, objdir, objdir_len);
  94                 fakeent->name = fakeent->base + objdir_len + 1;
  95                 fakeent->name[-1] = '/';
  96         }
  97         fakeent->next = alt_odb_list;
  98
  99         xsnprintf(hex, sizeof(hex), "%.2s", hex_pfx);
 100         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 101                 struct dirent *de;
 102                 DIR *dir;
 103                 /*
 104                  * every alt_odb struct has 42 extra bytes after the base
 105                  * for exactly this purpose
 106                  */
 107                 xsnprintf(alt->name, 42, "%.2s/", hex_pfx);
 108                 dir = opendir(alt->base);
 109                 if (!dir)
 110                         continue;
 111
 112                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 113                         unsigned char sha1[20];
 114
 115                         if (strlen(de->d_name) != 38)
 116                                 continue;
 117                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 118                                 continue;
 119                         memcpy(hex + 2, de->d_name, 38);
 120                         if (!get_sha1_hex(hex, sha1))
 121                                 update_candidates(ds, sha1);
 122                 }
 123                 closedir(dir);
 124         }
 125 }
 126
 127 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 128 {
 129         do {
 130                 if (*a != *b)
 131                         return 0;
 132                 a++;
 133                 b++;
 134                 len -= 2;
 135         } while (len > 1);
 136         if (len)
 137                 if ((*a ^ *b) & 0xf0)
 138                         return 0;
 139         return 1;
 140 }
 141
 142 static void unique_in_pack(int len,
 143                           const unsigned char *bin_pfx,
 144                            struct packed_git *p,
 145                            struct disambiguate_state *ds)
 146 {
 147         uint32_t num, last, i, first = 0;
 148         const unsigned char *current = NULL;
 149
 150         open_pack_index(p);
 151         num = p->num_objects;
 152         last = num;
 153         while (first < last) {
 154                 uint32_t mid = (first + last) / 2;
 155                 const unsigned char *current;
 156                 int cmp;
 157
 158                 current = nth_packed_object_sha1(p, mid);
 159                 cmp = hashcmp(bin_pfx, current);
 160                 if (!cmp) {
 161                         first = mid;
 162                         break;
 163                 }
 164                 if (cmp > 0) {
 165                         first = mid+1;
 166                         continue;
 167                 }
 168                 last = mid;
 169         }
 170
 171         /*
 172          * At this point, "first" is the location of the lowest object
 173          * with an object name that could match "bin_pfx".  See if we have
 174          * 0, 1 or more objects that actually match(es).
 175          */
 176         for (i = first; i < num && !ds->ambiguous; i++) {
 177                 current = nth_packed_object_sha1(p, i);
 178                 if (!match_sha(len, bin_pfx, current))
 179                         break;
 180                 update_candidates(ds, current);
 181         }
 182 }
 183
 184 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 185                                      struct disambiguate_state *ds)
 186 {
 187         struct packed_git *p;
 188
 189         prepare_packed_git();
 190         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 191                 unique_in_pack(len, bin_pfx, p, ds);
 192 }
 193
 194 #define SHORT_NAME_NOT_FOUND (-1)
 195 #define SHORT_NAME_AMBIGUOUS (-2)
 196
 197 static int finish_object_disambiguation(struct disambiguate_state *ds,
 198                                         unsigned char *sha1)
 199 {
 200         if (ds->ambiguous)
 201                 return SHORT_NAME_AMBIGUOUS;
 202
 203         if (!ds->candidate_exists)
 204                 return SHORT_NAME_NOT_FOUND;
 205
 206         if (!ds->candidate_checked)
 207                 /*
 208                  * If this is the only candidate, there is no point
 209                  * calling the disambiguation hint callback.
 210                  *
 211                  * On the other hand, if the current candidate
 212                  * replaced an earlier candidate that did _not_ pass
 213                  * the disambiguation hint callback, then we do have
 214                  * more than one objects that match the short name
 215                  * given, so we should make sure this one matches;
 216                  * otherwise, if we discovered this one and the one
 217                  * that we previously discarded in the reverse order,
 218                  * we would end up showing different results in the
 219                  * same repository!
 220                  */
 221                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 222                                     ds->fn(ds->candidate, ds->cb_data));
 223
 224         if (!ds->candidate_ok)
 225                 return SHORT_NAME_AMBIGUOUS;
 226
 227         hashcpy(sha1, ds->candidate);
 228         return 0;
 229 }
 230
 231 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 232 {
 233         int kind = sha1_object_info(sha1, NULL);
 234         return kind == OBJ_COMMIT;
 235 }
 236
 237 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 238 {
 239         struct object *obj;
 240         int kind;
 241
 242         kind = sha1_object_info(sha1, NULL);
 243         if (kind == OBJ_COMMIT)
 244                 return 1;
 245         if (kind != OBJ_TAG)
 246                 return 0;
 247
 248         /* We need to do this the hard way... */
 249         obj = deref_tag(parse_object(sha1), NULL, 0);
 250         if (obj && obj->type == OBJ_COMMIT)
 251                 return 1;
 252         return 0;
 253 }
 254
 255 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 256 {
 257         int kind = sha1_object_info(sha1, NULL);
 258         return kind == OBJ_TREE;
 259 }
 260
 261 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 262 {
 263         struct object *obj;
 264         int kind;
 265
 266         kind = sha1_object_info(sha1, NULL);
 267         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 268                 return 1;
 269         if (kind != OBJ_TAG)
 270                 return 0;
 271
 272         /* We need to do this the hard way... */
 273         obj = deref_tag(lookup_object(sha1), NULL, 0);
 274         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 275                 return 1;
 276         return 0;
 277 }
 278
 279 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 280 {
 281         int kind = sha1_object_info(sha1, NULL);
 282         return kind == OBJ_BLOB;
 283 }
 284
 285 static int prepare_prefixes(const char *name, int len,
 286                             unsigned char *bin_pfx,
 287                             char *hex_pfx)
 288 {
 289         int i;
 290
 291         hashclr(bin_pfx);
 292         memset(hex_pfx, 'x', 40);
 293         for (i = 0; i < len ;i++) {
 294                 unsigned char c = name[i];
 295                 unsigned char val;
 296                 if (c >= '0' && c <= '9')
 297                         val = c - '0';
 298                 else if (c >= 'a' && c <= 'f')
 299                         val = c - 'a' + 10;
 300                 else if (c >= 'A' && c <='F') {
 301                         val = c - 'A' + 10;
 302                         c -= 'A' - 'a';
 303                 }
 304                 else
 305                         return -1;
 306                 hex_pfx[i] = c;
 307                 if (!(i & 1))
 308                         val <<= 4;
 309                 bin_pfx[i >> 1] |= val;
 310         }
 311         return 0;
 312 }
 313
 314 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 315                           unsigned flags)
 316 {
 317         int status;
 318         char hex_pfx[40];
 319         unsigned char bin_pfx[20];
 320         struct disambiguate_state ds;
 321         int quietly = !!(flags & GET_SHA1_QUIETLY);
 322
 323         if (len < MINIMUM_ABBREV || len > 40)
 324                 return -1;
 325         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 326                 return -1;
 327
 328         prepare_alt_odb();
 329
 330         memset(&ds, 0, sizeof(ds));
 331         if (flags & GET_SHA1_COMMIT)
 332                 ds.fn = disambiguate_commit_only;
 333         else if (flags & GET_SHA1_COMMITTISH)
 334                 ds.fn = disambiguate_committish_only;
 335         else if (flags & GET_SHA1_TREE)
 336                 ds.fn = disambiguate_tree_only;
 337         else if (flags & GET_SHA1_TREEISH)
 338                 ds.fn = disambiguate_treeish_only;
 339         else if (flags & GET_SHA1_BLOB)
 340                 ds.fn = disambiguate_blob_only;
 341
 342         find_short_object_filename(len, hex_pfx, &ds);
 343         find_short_packed_object(len, bin_pfx, &ds);
 344         status = finish_object_disambiguation(&ds, sha1);
 345
 346         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 347                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 348         return status;
 349 }
 350
 351 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 352 {
 353         char hex_pfx[40];
 354         unsigned char bin_pfx[20];
 355         struct disambiguate_state ds;
 356         int len = strlen(prefix);
 357
 358         if (len < MINIMUM_ABBREV || len > 40)
 359                 return -1;
 360         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 361                 return -1;
 362
 363         prepare_alt_odb();
 364
 365         memset(&ds, 0, sizeof(ds));
 366         ds.always_call_fn = 1;
 367         ds.cb_data = cb_data;
 368         ds.fn = fn;
 369
 370         find_short_object_filename(len, hex_pfx, &ds);
 371         find_short_packed_object(len, bin_pfx, &ds);
 372         return ds.ambiguous;
 373 }
 374
 375 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 376 {
 377         int status, exists;
 378
 379         sha1_to_hex_r(hex, sha1);
 380         if (len == 40 || !len)
 381                 return 40;
 382         exists = has_sha1_file(sha1);
 383         while (len < 40) {
 384                 unsigned char sha1_ret[20];
 385                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 386                 if (exists
 387                     ? !status
 388                     : status == SHORT_NAME_NOT_FOUND) {
 389                         hex[len] = 0;
 390                         return len;
 391                 }
 392                 len++;
 393         }
 394         return len;
 395 }
 396
 397 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 398 {
 399         static char hex[GIT_SHA1_HEXSZ + 1];
 400         find_unique_abbrev_r(hex, sha1, len);
 401         return hex;
 402 }
 403
 404 static int ambiguous_path(const char *path, int len)
 405 {
 406         int slash = 1;
 407         int cnt;
 408
 409         for (cnt = 0; cnt < len; cnt++) {
 410                 switch (*path++) {
 411                 case '\0':
 412                         break;
 413                 case '/':
 414                         if (slash)
 415                                 break;
 416                         slash = 1;
 417                         continue;
 418                 case '.':
 419                         continue;
 420                 default:
 421                         slash = 0;
 422                         continue;
 423                 }
 424                 break;
 425         }
 426         return slash;
 427 }
 428
 429 static inline int at_mark(const char *string, int len,
 430                           const char **suffix, int nr)
 431 {
 432         int i;
 433
 434         for (i = 0; i < nr; i++) {
 435                 int suffix_len = strlen(suffix[i]);
 436                 if (suffix_len <= len
 437                     && !memcmp(string, suffix[i], suffix_len))
 438                         return suffix_len;
 439         }
 440         return 0;
 441 }
 442
 443 static inline int upstream_mark(const char *string, int len)
 444 {
 445         const char *suffix[] = { "@{upstream}", "@{u}" };
 446         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 447 }
 448
 449 static inline int push_mark(const char *string, int len)
 450 {
 451         const char *suffix[] = { "@{push}" };
 452         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 453 }
 454
 455 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 456 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 457
 458 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 459                           unsigned int flags)
 460 {
 461         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 462         static const char *object_name_msg = N_(
 463         "Git normally never creates a ref that ends with 40 hex characters\n"
 464         "because it will be ignored when you just specify 40-hex. These refs\n"
 465         "may be created by mistake. For example,\n"
 466         "\n"
 467         "  git checkout -b $br $(git rev-parse ...)\n"
 468         "\n"
 469         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 470         "examine these refs and maybe delete them. Turn this message off by\n"
 471         "running \"git config advice.objectNameWarning false\"");
 472         unsigned char tmp_sha1[20];
 473         char *real_ref = NULL;
 474         int refs_found = 0;
 475         int at, reflog_len, nth_prior = 0;
 476
 477         if (len == 40 && !get_sha1_hex(str, sha1)) {
 478                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 479                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 480                         if (refs_found > 0) {
 481                                 warning(warn_msg, len, str);
 482                                 if (advice_object_name_warning)
 483                                         fprintf(stderr, "%s\n", _(object_name_msg));
 484                         }
 485                         free(real_ref);
 486                 }
 487                 return 0;
 488         }
 489
 490         /* basic@{time or number or -number} format to query ref-log */
 491         reflog_len = at = 0;
 492         if (len && str[len-1] == '}') {
 493                 for (at = len-4; at >= 0; at--) {
 494                         if (str[at] == '@' && str[at+1] == '{') {
 495                                 if (str[at+2] == '-') {
 496                                         if (at != 0)
 497                                                 /* @{-N} not at start */
 498                                                 return -1;
 499                                         nth_prior = 1;
 500                                         continue;
 501                                 }
 502                                 if (!upstream_mark(str + at, len - at) &&
 503                                     !push_mark(str + at, len - at)) {
 504                                         reflog_len = (len-1) - (at+2);
 505                                         len = at;
 506                                 }
 507                                 break;
 508                         }
 509                 }
 510         }
 511
 512         /* Accept only unambiguous ref paths. */
 513         if (len && ambiguous_path(str, len))
 514                 return -1;
 515
 516         if (nth_prior) {
 517                 struct strbuf buf = STRBUF_INIT;
 518                 int detached;
 519
 520                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 521                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 522                         strbuf_release(&buf);
 523                         if (detached)
 524                                 return 0;
 525                 }
 526         }
 527
 528         if (!len && reflog_len)
 529                 /* allow "@{...}" to mean the current branch reflog */
 530                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 531         else if (reflog_len)
 532                 refs_found = dwim_log(str, len, sha1, &real_ref);
 533         else
 534                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 535
 536         if (!refs_found)
 537                 return -1;
 538
 539         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 540             (refs_found > 1 ||
 541              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 542                 warning(warn_msg, len, str);
 543
 544         if (reflog_len) {
 545                 int nth, i;
 546                 unsigned long at_time;
 547                 unsigned long co_time;
 548                 int co_tz, co_cnt;
 549
 550                 /* Is it asking for N-th entry, or approxidate? */
 551                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 552                         char ch = str[at+2+i];
 553                         if ('0' <= ch && ch <= '9')
 554                                 nth = nth * 10 + ch - '0';
 555                         else
 556                                 nth = -1;
 557                 }
 558                 if (100000000 <= nth) {
 559                         at_time = nth;
 560                         nth = -1;
 561                 } else if (0 <= nth)
 562                         at_time = 0;
 563                 else {
 564                         int errors = 0;
 565                         char *tmp = xstrndup(str + at + 2, reflog_len);
 566                         at_time = approxidate_careful(tmp, &errors);
 567                         free(tmp);
 568                         if (errors) {
 569                                 free(real_ref);
 570                                 return -1;
 571                         }
 572                 }
 573                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 574                                 &co_time, &co_tz, &co_cnt)) {
 575                         if (!len) {
 576                                 if (starts_with(real_ref, "refs/heads/")) {
 577                                         str = real_ref + 11;
 578                                         len = strlen(real_ref + 11);
 579                                 } else {
 580                                         /* detached HEAD */
 581                                         str = "HEAD";
 582                                         len = 4;
 583                                 }
 584                         }
 585                         if (at_time) {
 586                                 if (!(flags & GET_SHA1_QUIETLY)) {
 587                                         warning("Log for '%.*s' only goes "
 588                                                 "back to %s.", len, str,
 589                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 590                                 }
 591                         } else {
 592                                 if (flags & GET_SHA1_QUIETLY) {
 593                                         exit(128);
 594                                 }
 595                                 die("Log for '%.*s' only has %d entries.",
 596                                     len, str, co_cnt);
 597                         }
 598                 }
 599         }
 600
 601         free(real_ref);
 602         return 0;
 603 }
 604
 605 static int get_parent(const char *name, int len,
 606                       unsigned char *result, int idx)
 607 {
 608         unsigned char sha1[20];
 609         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 610         struct commit *commit;
 611         struct commit_list *p;
 612
 613         if (ret)
 614                 return ret;
 615         commit = lookup_commit_reference(sha1);
 616         if (parse_commit(commit))
 617                 return -1;
 618         if (!idx) {
 619                 hashcpy(result, commit->object.sha1);
 620                 return 0;
 621         }
 622         p = commit->parents;
 623         while (p) {
 624                 if (!--idx) {
 625                         hashcpy(result, p->item->object.sha1);
 626                         return 0;
 627                 }
 628                 p = p->next;
 629         }
 630         return -1;
 631 }
 632
 633 static int get_nth_ancestor(const char *name, int len,
 634                             unsigned char *result, int generation)
 635 {
 636         unsigned char sha1[20];
 637         struct commit *commit;
 638         int ret;
 639
 640         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 641         if (ret)
 642                 return ret;
 643         commit = lookup_commit_reference(sha1);
 644         if (!commit)
 645                 return -1;
 646
 647         while (generation--) {
 648                 if (parse_commit(commit) || !commit->parents)
 649                         return -1;
 650                 commit = commit->parents->item;
 651         }
 652         hashcpy(result, commit->object.sha1);
 653         return 0;
 654 }
 655
 656 struct object *peel_to_type(const char *name, int namelen,
 657                             struct object *o, enum object_type expected_type)
 658 {
 659         if (name && !namelen)
 660                 namelen = strlen(name);
 661         while (1) {
 662                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 663                         return NULL;
 664                 if (expected_type == OBJ_ANY || o->type == expected_type)
 665                         return o;
 666                 if (o->type == OBJ_TAG)
 667                         o = ((struct tag*) o)->tagged;
 668                 else if (o->type == OBJ_COMMIT)
 669                         o = &(((struct commit *) o)->tree->object);
 670                 else {
 671                         if (name)
 672                                 error("%.*s: expected %s type, but the object "
 673                                       "dereferences to %s type",
 674                                       namelen, name, typename(expected_type),
 675                                       typename(o->type));
 676                         return NULL;
 677                 }
 678         }
 679 }
 680
 681 static int peel_onion(const char *name, int len, unsigned char *sha1)
 682 {
 683         unsigned char outer[20];
 684         const char *sp;
 685         unsigned int expected_type = 0;
 686         unsigned lookup_flags = 0;
 687         struct object *o;
 688
 689         /*
 690          * "ref^{type}" dereferences ref repeatedly until you cannot
 691          * dereference anymore, or you get an object of given type,
 692          * whichever comes first.  "ref^{}" means just dereference
 693          * tags until you get a non-tag.  "ref^0" is a shorthand for
 694          * "ref^{commit}".  "commit^{tree}" could be used to find the
 695          * top-level tree of the given commit.
 696          */
 697         if (len < 4 || name[len-1] != '}')
 698                 return -1;
 699
 700         for (sp = name + len - 1; name <= sp; sp--) {
 701                 int ch = *sp;
 702                 if (ch == '{' && name < sp && sp[-1] == '^')
 703                         break;
 704         }
 705         if (sp <= name)
 706                 return -1;
 707
 708         sp++; /* beginning of type name, or closing brace for empty */
 709         if (starts_with(sp, "commit}"))
 710                 expected_type = OBJ_COMMIT;
 711         else if (starts_with(sp, "tag}"))
 712                 expected_type = OBJ_TAG;
 713         else if (starts_with(sp, "tree}"))
 714                 expected_type = OBJ_TREE;
 715         else if (starts_with(sp, "blob}"))
 716                 expected_type = OBJ_BLOB;
 717         else if (starts_with(sp, "object}"))
 718                 expected_type = OBJ_ANY;
 719         else if (sp[0] == '}')
 720                 expected_type = OBJ_NONE;
 721         else if (sp[0] == '/')
 722                 expected_type = OBJ_COMMIT;
 723         else
 724                 return -1;
 725
 726         if (expected_type == OBJ_COMMIT)
 727                 lookup_flags = GET_SHA1_COMMITTISH;
 728         else if (expected_type == OBJ_TREE)
 729                 lookup_flags = GET_SHA1_TREEISH;
 730
 731         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 732                 return -1;
 733
 734         o = parse_object(outer);
 735         if (!o)
 736                 return -1;
 737         if (!expected_type) {
 738                 o = deref_tag(o, name, sp - name - 2);
 739                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 740                         return -1;
 741                 hashcpy(sha1, o->sha1);
 742                 return 0;
 743         }
 744
 745         /*
 746          * At this point, the syntax look correct, so
 747          * if we do not get the needed object, we should
 748          * barf.
 749          */
 750         o = peel_to_type(name, len, o, expected_type);
 751         if (!o)
 752                 return -1;
 753
 754         hashcpy(sha1, o->sha1);
 755         if (sp[0] == '/') {
 756                 /* "$commit^{/foo}" */
 757                 char *prefix;
 758                 int ret;
 759                 struct commit_list *list = NULL;
 760
 761                 /*
 762                  * $commit^{/}. Some regex implementation may reject.
 763                  * We don't need regex anyway. '' pattern always matches.
 764                  */
 765                 if (sp[1] == '}')
 766                         return 0;
 767
 768                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 769                 commit_list_insert((struct commit *)o, &list);
 770                 ret = get_sha1_oneline(prefix, sha1, list);
 771                 free(prefix);
 772                 return ret;
 773         }
 774         return 0;
 775 }
 776
 777 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 778 {
 779         const char *cp;
 780         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 781
 782         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 783                 char ch = *cp;
 784                 if (!isxdigit(ch)) {
 785                         /* We must be looking at g in "SOMETHING-g"
 786                          * for it to be describe output.
 787                          */
 788                         if (ch == 'g' && cp[-1] == '-') {
 789                                 cp++;
 790                                 len -= cp - name;
 791                                 return get_short_sha1(cp, len, sha1, flags);
 792                         }
 793                 }
 794         }
 795         return -1;
 796 }
 797
 798 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 799 {
 800         int ret, has_suffix;
 801         const char *cp;
 802
 803         /*
 804          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 805          */
 806         has_suffix = 0;
 807         for (cp = name + len - 1; name <= cp; cp--) {
 808                 int ch = *cp;
 809                 if ('0' <= ch && ch <= '9')
 810                         continue;
 811                 if (ch == '~' || ch == '^')
 812                         has_suffix = ch;
 813                 break;
 814         }
 815
 816         if (has_suffix) {
 817                 int num = 0;
 818                 int len1 = cp - name;
 819                 cp++;
 820                 while (cp < name + len)
 821                         num = num * 10 + *cp++ - '0';
 822                 if (!num && len1 == len - 1)
 823                         num = 1;
 824                 if (has_suffix == '^')
 825                         return get_parent(name, len1, sha1, num);
 826                 /* else if (has_suffix == '~') -- goes without saying */
 827                 return get_nth_ancestor(name, len1, sha1, num);
 828         }
 829
 830         ret = peel_onion(name, len, sha1);
 831         if (!ret)
 832                 return 0;
 833
 834         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 835         if (!ret)
 836                 return 0;
 837
 838         /* It could be describe output that is "SOMETHING-gXXXX" */
 839         ret = get_describe_name(name, len, sha1);
 840         if (!ret)
 841                 return 0;
 842
 843         return get_short_sha1(name, len, sha1, lookup_flags);
 844 }
 845
 846 /*
 847  * This interprets names like ':/Initial revision of "git"' by searching
 848  * through history and returning the first commit whose message starts
 849  * the given regular expression.
 850  *
 851  * For future extension, ':/!' is reserved. If you want to match a message
 852  * beginning with a '!', you have to repeat the exclamation mark.
 853  */
 854
 855 /* Remember to update object flag allocation in object.h */
 856 #define ONELINE_SEEN (1u<<20)
 857
 858 static int handle_one_ref(const char *path, const struct object_id *oid,
 859                           int flag, void *cb_data)
 860 {
 861         struct commit_list **list = cb_data;
 862         struct object *object = parse_object(oid->hash);
 863         if (!object)
 864                 return 0;
 865         if (object->type == OBJ_TAG) {
 866                 object = deref_tag(object, path, strlen(path));
 867                 if (!object)
 868                         return 0;
 869         }
 870         if (object->type != OBJ_COMMIT)
 871                 return 0;
 872         commit_list_insert((struct commit *)object, list);
 873         return 0;
 874 }
 875
 876 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 877                             struct commit_list *list)
 878 {
 879         struct commit_list *backup = NULL, *l;
 880         int found = 0;
 881         regex_t regex;
 882
 883         if (prefix[0] == '!') {
 884                 if (prefix[1] != '!')
 885                         die ("Invalid search pattern: %s", prefix);
 886                 prefix++;
 887         }
 888
 889         if (regcomp(&regex, prefix, REG_EXTENDED))
 890                 die("Invalid search pattern: %s", prefix);
 891
 892         for (l = list; l; l = l->next) {
 893                 l->item->object.flags |= ONELINE_SEEN;
 894                 commit_list_insert(l->item, &backup);
 895         }
 896         while (list) {
 897                 const char *p, *buf;
 898                 struct commit *commit;
 899                 int matches;
 900
 901                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 902                 if (!parse_object(commit->object.sha1))
 903                         continue;
 904                 buf = get_commit_buffer(commit, NULL);
 905                 p = strstr(buf, "\n\n");
 906                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 907                 unuse_commit_buffer(commit, buf);
 908
 909                 if (matches) {
 910                         hashcpy(sha1, commit->object.sha1);
 911                         found = 1;
 912                         break;
 913                 }
 914         }
 915         regfree(&regex);
 916         free_commit_list(list);
 917         for (l = backup; l; l = l->next)
 918                 clear_commit_marks(l->item, ONELINE_SEEN);
 919         free_commit_list(backup);
 920         return found ? 0 : -1;
 921 }
 922
 923 struct grab_nth_branch_switch_cbdata {
 924         int remaining;
 925         struct strbuf buf;
 926 };
 927
 928 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 929                                   const char *email, unsigned long timestamp, int tz,
 930                                   const char *message, void *cb_data)
 931 {
 932         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 933         const char *match = NULL, *target = NULL;
 934         size_t len;
 935
 936         if (skip_prefix(message, "checkout: moving from ", &match))
 937                 target = strstr(match, " to ");
 938
 939         if (!match || !target)
 940                 return 0;
 941         if (--(cb->remaining) == 0) {
 942                 len = target - match;
 943                 strbuf_reset(&cb->buf);
 944                 strbuf_add(&cb->buf, match, len);
 945                 return 1; /* we are done */
 946         }
 947         return 0;
 948 }
 949
 950 /*
 951  * Parse @{-N} syntax, return the number of characters parsed
 952  * if successful; otherwise signal an error with negative value.
 953  */
 954 static int interpret_nth_prior_checkout(const char *name, int namelen,
 955                                         struct strbuf *buf)
 956 {
 957         long nth;
 958         int retval;
 959         struct grab_nth_branch_switch_cbdata cb;
 960         const char *brace;
 961         char *num_end;
 962
 963         if (namelen < 4)
 964                 return -1;
 965         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 966                 return -1;
 967         brace = memchr(name, '}', namelen);
 968         if (!brace)
 969                 return -1;
 970         nth = strtol(name + 3, &num_end, 10);
 971         if (num_end != brace)
 972                 return -1;
 973         if (nth <= 0)
 974                 return -1;
 975         cb.remaining = nth;
 976         strbuf_init(&cb.buf, 20);
 977
 978         retval = 0;
 979         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 980                 strbuf_reset(buf);
 981                 strbuf_addbuf(buf, &cb.buf);
 982                 retval = brace - name + 1;
 983         }
 984
 985         strbuf_release(&cb.buf);
 986         return retval;
 987 }
 988
 989 int get_sha1_mb(const char *name, unsigned char *sha1)
 990 {
 991         struct commit *one, *two;
 992         struct commit_list *mbs;
 993         unsigned char sha1_tmp[20];
 994         const char *dots;
 995         int st;
 996
 997         dots = strstr(name, "...");
 998         if (!dots)
 999                 return get_sha1(name, sha1);
1000         if (dots == name)
1001                 st = get_sha1("HEAD", sha1_tmp);
1002         else {
1003                 struct strbuf sb;
1004                 strbuf_init(&sb, dots - name);
1005                 strbuf_add(&sb, name, dots - name);
1006                 st = get_sha1_committish(sb.buf, sha1_tmp);
1007                 strbuf_release(&sb);
1008         }
1009         if (st)
1010                 return st;
1011         one = lookup_commit_reference_gently(sha1_tmp, 0);
1012         if (!one)
1013                 return -1;
1014
1015         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
1016                 return -1;
1017         two = lookup_commit_reference_gently(sha1_tmp, 0);
1018         if (!two)
1019                 return -1;
1020         mbs = get_merge_bases(one, two);
1021         if (!mbs || mbs->next)
1022                 st = -1;
1023         else {
1024                 st = 0;
1025                 hashcpy(sha1, mbs->item->object.sha1);
1026         }
1027         free_commit_list(mbs);
1028         return st;
1029 }
1030
1031 /* parse @something syntax, when 'something' is not {.*} */
1032 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1033 {
1034         const char *next;
1035
1036         if (len || name[1] == '{')
1037                 return -1;
1038
1039         /* make sure it's a single @, or @@{.*}, not @foo */
1040         next = memchr(name + len + 1, '@', namelen - len - 1);
1041         if (next && next[1] != '{')
1042                 return -1;
1043         if (!next)
1044                 next = name + namelen;
1045         if (next != name + 1)
1046                 return -1;
1047
1048         strbuf_reset(buf);
1049         strbuf_add(buf, "HEAD", 4);
1050         return 1;
1051 }
1052
1053 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1054 {
1055         /* we have extra data, which might need further processing */
1056         struct strbuf tmp = STRBUF_INIT;
1057         int used = buf->len;
1058         int ret;
1059
1060         strbuf_add(buf, name + len, namelen - len);
1061         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1062         /* that data was not interpreted, remove our cruft */
1063         if (ret < 0) {
1064                 strbuf_setlen(buf, used);
1065                 return len;
1066         }
1067         strbuf_reset(buf);
1068         strbuf_addbuf(buf, &tmp);
1069         strbuf_release(&tmp);
1070         /* tweak for size of {-N} versus expanded ref name */
1071         return ret - used + len;
1072 }
1073
1074 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1075 {
1076         char *s = shorten_unambiguous_ref(ref, 0);
1077         strbuf_reset(buf);
1078         strbuf_addstr(buf, s);
1079         free(s);
1080 }
1081
1082 static int interpret_branch_mark(const char *name, int namelen,
1083                                  int at, struct strbuf *buf,
1084                                  int (*get_mark)(const char *, int),
1085                                  const char *(*get_data)(struct branch *,
1086                                                          struct strbuf *))
1087 {
1088         int len;
1089         struct branch *branch;
1090         struct strbuf err = STRBUF_INIT;
1091         const char *value;
1092
1093         len = get_mark(name + at, namelen - at);
1094         if (!len)
1095                 return -1;
1096
1097         if (memchr(name, ':', at))
1098                 return -1;
1099
1100         if (at) {
1101                 char *name_str = xmemdupz(name, at);
1102                 branch = branch_get(name_str);
1103                 free(name_str);
1104         } else
1105                 branch = branch_get(NULL);
1106
1107         value = get_data(branch, &err);
1108         if (!value)
1109                 die("%s", err.buf);
1110
1111         set_shortened_ref(buf, value);
1112         return len + at;
1113 }
1114
1115 /*
1116  * This reads short-hand syntax that not only evaluates to a commit
1117  * object name, but also can act as if the end user spelled the name
1118  * of the branch from the command line.
1119  *
1120  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1121  *   places the name of the branch in the given buf and returns the
1122  *   number of characters parsed if successful.
1123  *
1124  * - "<branch>@{upstream}" finds the name of the other ref that
1125  *   <branch> is configured to merge with (missing <branch> defaults
1126  *   to the current branch), and places the name of the branch in the
1127  *   given buf and returns the number of characters parsed if
1128  *   successful.
1129  *
1130  * If the input is not of the accepted format, it returns a negative
1131  * number to signal an error.
1132  *
1133  * If the input was ok but there are not N branch switches in the
1134  * reflog, it returns 0.
1135  */
1136 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1137 {
1138         char *at;
1139         const char *start;
1140         int len = interpret_nth_prior_checkout(name, namelen, buf);
1141
1142         if (!namelen)
1143                 namelen = strlen(name);
1144
1145         if (!len) {
1146                 return len; /* syntax Ok, not enough switches */
1147         } else if (len > 0) {
1148                 if (len == namelen)
1149                         return len; /* consumed all */
1150                 else
1151                         return reinterpret(name, namelen, len, buf);
1152         }
1153
1154         for (start = name;
1155              (at = memchr(start, '@', namelen - (start - name)));
1156              start = at + 1) {
1157
1158                 len = interpret_empty_at(name, namelen, at - name, buf);
1159                 if (len > 0)
1160                         return reinterpret(name, namelen, len, buf);
1161
1162                 len = interpret_branch_mark(name, namelen, at - name, buf,
1163                                             upstream_mark, branch_get_upstream);
1164                 if (len > 0)
1165                         return len;
1166
1167                 len = interpret_branch_mark(name, namelen, at - name, buf,
1168                                             push_mark, branch_get_push);
1169                 if (len > 0)
1170                         return len;
1171         }
1172
1173         return -1;
1174 }
1175
1176 int strbuf_branchname(struct strbuf *sb, const char *name)
1177 {
1178         int len = strlen(name);
1179         int used = interpret_branch_name(name, len, sb);
1180
1181         if (used == len)
1182                 return 0;
1183         if (used < 0)
1184                 used = 0;
1185         strbuf_add(sb, name + used, len - used);
1186         return len;
1187 }
1188
1189 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1190 {
1191         strbuf_branchname(sb, name);
1192         if (name[0] == '-')
1193                 return -1;
1194         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1195         return check_refname_format(sb->buf, 0);
1196 }
1197
1198 /*
1199  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1200  * notably "xyz^" for "parent of xyz"
1201  */
1202 int get_sha1(const char *name, unsigned char *sha1)
1203 {
1204         struct object_context unused;
1205         return get_sha1_with_context(name, 0, sha1, &unused);
1206 }
1207
1208 /*
1209  * Many callers know that the user meant to name a commit-ish by
1210  * syntactical positions where the object name appears.  Calling this
1211  * function allows the machinery to disambiguate shorter-than-unique
1212  * abbreviated object names between commit-ish and others.
1213  *
1214  * Note that this does NOT error out when the named object is not a
1215  * commit-ish. It is merely to give a hint to the disambiguation
1216  * machinery.
1217  */
1218 int get_sha1_committish(const char *name, unsigned char *sha1)
1219 {
1220         struct object_context unused;
1221         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1222                                      sha1, &unused);
1223 }
1224
1225 int get_sha1_treeish(const char *name, unsigned char *sha1)
1226 {
1227         struct object_context unused;
1228         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1229                                      sha1, &unused);
1230 }
1231
1232 int get_sha1_commit(const char *name, unsigned char *sha1)
1233 {
1234         struct object_context unused;
1235         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1236                                      sha1, &unused);
1237 }
1238
1239 int get_sha1_tree(const char *name, unsigned char *sha1)
1240 {
1241         struct object_context unused;
1242         return get_sha1_with_context(name, GET_SHA1_TREE,
1243                                      sha1, &unused);
1244 }
1245
1246 int get_sha1_blob(const char *name, unsigned char *sha1)
1247 {
1248         struct object_context unused;
1249         return get_sha1_with_context(name, GET_SHA1_BLOB,
1250                                      sha1, &unused);
1251 }
1252
1253 /* Must be called only when object_name:filename doesn't exist. */
1254 static void diagnose_invalid_sha1_path(const char *prefix,
1255                                        const char *filename,
1256                                        const unsigned char *tree_sha1,
1257                                        const char *object_name,
1258                                        int object_name_len)
1259 {
1260         unsigned char sha1[20];
1261         unsigned mode;
1262
1263         if (!prefix)
1264                 prefix = "";
1265
1266         if (file_exists(filename))
1267                 die("Path '%s' exists on disk, but not in '%.*s'.",
1268                     filename, object_name_len, object_name);
1269         if (errno == ENOENT || errno == ENOTDIR) {
1270                 char *fullname = xstrfmt("%s%s", prefix, filename);
1271
1272                 if (!get_tree_entry(tree_sha1, fullname,
1273                                     sha1, &mode)) {
1274                         die("Path '%s' exists, but not '%s'.\n"
1275                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1276                             fullname,
1277                             filename,
1278                             object_name_len, object_name,
1279                             fullname,
1280                             object_name_len, object_name,
1281                             filename);
1282                 }
1283                 die("Path '%s' does not exist in '%.*s'",
1284                     filename, object_name_len, object_name);
1285         }
1286 }
1287
1288 /* Must be called only when :stage:filename doesn't exist. */
1289 static void diagnose_invalid_index_path(int stage,
1290                                         const char *prefix,
1291                                         const char *filename)
1292 {
1293         const struct cache_entry *ce;
1294         int pos;
1295         unsigned namelen = strlen(filename);
1296         struct strbuf fullname = STRBUF_INIT;
1297
1298         if (!prefix)
1299                 prefix = "";
1300
1301         /* Wrong stage number? */
1302         pos = cache_name_pos(filename, namelen);
1303         if (pos < 0)
1304                 pos = -pos - 1;
1305         if (pos < active_nr) {
1306                 ce = active_cache[pos];
1307                 if (ce_namelen(ce) == namelen &&
1308                     !memcmp(ce->name, filename, namelen))
1309                         die("Path '%s' is in the index, but not at stage %d.\n"
1310                             "Did you mean ':%d:%s'?",
1311                             filename, stage,
1312                             ce_stage(ce), filename);
1313         }
1314
1315         /* Confusion between relative and absolute filenames? */
1316         strbuf_addstr(&fullname, prefix);
1317         strbuf_addstr(&fullname, filename);
1318         pos = cache_name_pos(fullname.buf, fullname.len);
1319         if (pos < 0)
1320                 pos = -pos - 1;
1321         if (pos < active_nr) {
1322                 ce = active_cache[pos];
1323                 if (ce_namelen(ce) == fullname.len &&
1324                     !memcmp(ce->name, fullname.buf, fullname.len))
1325                         die("Path '%s' is in the index, but not '%s'.\n"
1326                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1327                             fullname.buf, filename,
1328                             ce_stage(ce), fullname.buf,
1329                             ce_stage(ce), filename);
1330         }
1331
1332         if (file_exists(filename))
1333                 die("Path '%s' exists on disk, but not in the index.", filename);
1334         if (errno == ENOENT || errno == ENOTDIR)
1335                 die("Path '%s' does not exist (neither on disk nor in the index).",
1336                     filename);
1337
1338         strbuf_release(&fullname);
1339 }
1340
1341
1342 static char *resolve_relative_path(const char *rel)
1343 {
1344         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1345                 return NULL;
1346
1347         if (!startup_info)
1348                 die("BUG: startup_info struct is not initialized.");
1349
1350         if (!is_inside_work_tree())
1351                 die("relative path syntax can't be used outside working tree.");
1352
1353         /* die() inside prefix_path() if resolved path is outside worktree */
1354         return prefix_path(startup_info->prefix,
1355                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1356                            rel);
1357 }
1358
1359 static int get_sha1_with_context_1(const char *name,
1360                                    unsigned flags,
1361                                    const char *prefix,
1362                                    unsigned char *sha1,
1363                                    struct object_context *oc)
1364 {
1365         int ret, bracket_depth;
1366         int namelen = strlen(name);
1367         const char *cp;
1368         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1369
1370         memset(oc, 0, sizeof(*oc));
1371         oc->mode = S_IFINVALID;
1372         ret = get_sha1_1(name, namelen, sha1, flags);
1373         if (!ret)
1374                 return ret;
1375         /*
1376          * sha1:path --> object name of path in ent sha1
1377          * :path -> object name of absolute path in index
1378          * :./path -> object name of path relative to cwd in index
1379          * :[0-3]:path -> object name of path in index at stage
1380          * :/foo -> recent commit matching foo
1381          */
1382         if (name[0] == ':') {
1383                 int stage = 0;
1384                 const struct cache_entry *ce;
1385                 char *new_path = NULL;
1386                 int pos;
1387                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1388                         struct commit_list *list = NULL;
1389
1390                         for_each_ref(handle_one_ref, &list);
1391                         commit_list_sort_by_date(&list);
1392                         return get_sha1_oneline(name + 2, sha1, list);
1393                 }
1394                 if (namelen < 3 ||
1395                     name[2] != ':' ||
1396                     name[1] < '0' || '3' < name[1])
1397                         cp = name + 1;
1398                 else {
1399                         stage = name[1] - '0';
1400                         cp = name + 3;
1401                 }
1402                 new_path = resolve_relative_path(cp);
1403                 if (!new_path) {
1404                         namelen = namelen - (cp - name);
1405                 } else {
1406                         cp = new_path;
1407                         namelen = strlen(cp);
1408                 }
1409
1410                 strlcpy(oc->path, cp, sizeof(oc->path));
1411
1412                 if (!active_cache)
1413                         read_cache();
1414                 pos = cache_name_pos(cp, namelen);
1415                 if (pos < 0)
1416                         pos = -pos - 1;
1417                 while (pos < active_nr) {
1418                         ce = active_cache[pos];
1419                         if (ce_namelen(ce) != namelen ||
1420                             memcmp(ce->name, cp, namelen))
1421                                 break;
1422                         if (ce_stage(ce) == stage) {
1423                                 hashcpy(sha1, ce->sha1);
1424                                 oc->mode = ce->ce_mode;
1425                                 free(new_path);
1426                                 return 0;
1427                         }
1428                         pos++;
1429                 }
1430                 if (only_to_die && name[1] && name[1] != '/')
1431                         diagnose_invalid_index_path(stage, prefix, cp);
1432                 free(new_path);
1433                 return -1;
1434         }
1435         for (cp = name, bracket_depth = 0; *cp; cp++) {
1436                 if (*cp == '{')
1437                         bracket_depth++;
1438                 else if (bracket_depth && *cp == '}')
1439                         bracket_depth--;
1440                 else if (!bracket_depth && *cp == ':')
1441                         break;
1442         }
1443         if (*cp == ':') {
1444                 unsigned char tree_sha1[20];
1445                 int len = cp - name;
1446                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1447                         const char *filename = cp+1;
1448                         char *new_filename = NULL;
1449
1450                         new_filename = resolve_relative_path(filename);
1451                         if (new_filename)
1452                                 filename = new_filename;
1453                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1454                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1455                                         filename, sha1, &oc->symlink_path,
1456                                         &oc->mode);
1457                         } else {
1458                                 ret = get_tree_entry(tree_sha1, filename,
1459                                                      sha1, &oc->mode);
1460                                 if (ret && only_to_die) {
1461                                         diagnose_invalid_sha1_path(prefix,
1462                                                                    filename,
1463                                                                    tree_sha1,
1464                                                                    name, len);
1465                                 }
1466                         }
1467                         hashcpy(oc->tree, tree_sha1);
1468                         strlcpy(oc->path, filename, sizeof(oc->path));
1469
1470                         free(new_filename);
1471                         return ret;
1472                 } else {
1473                         if (only_to_die)
1474                                 die("Invalid object name '%.*s'.", len, name);
1475                 }
1476         }
1477         return ret;
1478 }
1479
1480 /*
1481  * Call this function when you know "name" given by the end user must
1482  * name an object but it doesn't; the function _may_ die with a better
1483  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1484  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1485  * you have a chance to diagnose the error further.
1486  */
1487 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1488 {
1489         struct object_context oc;
1490         unsigned char sha1[20];
1491         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1492 }
1493
1494 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1495 {
1496         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1497                 die("BUG: incompatible flags for get_sha1_with_context");
1498         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1499 }