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                 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         sprintf(hex, "%.2s", hex_pfx);
 100         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 101                 struct dirent *de;
 102                 DIR *dir;
 103                 sprintf(alt->name, "%.2s/", hex_pfx);
 104                 dir = opendir(alt->base);
 105                 if (!dir)
 106                         continue;
 107
 108                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 109                         unsigned char sha1[20];
 110
 111                         if (strlen(de->d_name) != 38)
 112                                 continue;
 113                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 114                                 continue;
 115                         memcpy(hex + 2, de->d_name, 38);
 116                         if (!get_sha1_hex(hex, sha1))
 117                                 update_candidates(ds, sha1);
 118                 }
 119                 closedir(dir);
 120         }
 121 }
 122
 123 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 124 {
 125         do {
 126                 if (*a != *b)
 127                         return 0;
 128                 a++;
 129                 b++;
 130                 len -= 2;
 131         } while (len > 1);
 132         if (len)
 133                 if ((*a ^ *b) & 0xf0)
 134                         return 0;
 135         return 1;
 136 }
 137
 138 static void unique_in_pack(int len,
 139                           const unsigned char *bin_pfx,
 140                            struct packed_git *p,
 141                            struct disambiguate_state *ds)
 142 {
 143         uint32_t num, last, i, first = 0;
 144         const unsigned char *current = NULL;
 145
 146         open_pack_index(p);
 147         num = p->num_objects;
 148         last = num;
 149         while (first < last) {
 150                 uint32_t mid = (first + last) / 2;
 151                 const unsigned char *current;
 152                 int cmp;
 153
 154                 current = nth_packed_object_sha1(p, mid);
 155                 cmp = hashcmp(bin_pfx, current);
 156                 if (!cmp) {
 157                         first = mid;
 158                         break;
 159                 }
 160                 if (cmp > 0) {
 161                         first = mid+1;
 162                         continue;
 163                 }
 164                 last = mid;
 165         }
 166
 167         /*
 168          * At this point, "first" is the location of the lowest object
 169          * with an object name that could match "bin_pfx".  See if we have
 170          * 0, 1 or more objects that actually match(es).
 171          */
 172         for (i = first; i < num && !ds->ambiguous; i++) {
 173                 current = nth_packed_object_sha1(p, i);
 174                 if (!match_sha(len, bin_pfx, current))
 175                         break;
 176                 update_candidates(ds, current);
 177         }
 178 }
 179
 180 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 181                                      struct disambiguate_state *ds)
 182 {
 183         struct packed_git *p;
 184
 185         prepare_packed_git();
 186         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 187                 unique_in_pack(len, bin_pfx, p, ds);
 188 }
 189
 190 #define SHORT_NAME_NOT_FOUND (-1)
 191 #define SHORT_NAME_AMBIGUOUS (-2)
 192
 193 static int finish_object_disambiguation(struct disambiguate_state *ds,
 194                                         unsigned char *sha1)
 195 {
 196         if (ds->ambiguous)
 197                 return SHORT_NAME_AMBIGUOUS;
 198
 199         if (!ds->candidate_exists)
 200                 return SHORT_NAME_NOT_FOUND;
 201
 202         if (!ds->candidate_checked)
 203                 /*
 204                  * If this is the only candidate, there is no point
 205                  * calling the disambiguation hint callback.
 206                  *
 207                  * On the other hand, if the current candidate
 208                  * replaced an earlier candidate that did _not_ pass
 209                  * the disambiguation hint callback, then we do have
 210                  * more than one objects that match the short name
 211                  * given, so we should make sure this one matches;
 212                  * otherwise, if we discovered this one and the one
 213                  * that we previously discarded in the reverse order,
 214                  * we would end up showing different results in the
 215                  * same repository!
 216                  */
 217                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 218                                     ds->fn(ds->candidate, ds->cb_data));
 219
 220         if (!ds->candidate_ok)
 221                 return SHORT_NAME_AMBIGUOUS;
 222
 223         hashcpy(sha1, ds->candidate);
 224         return 0;
 225 }
 226
 227 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 228 {
 229         int kind = sha1_object_info(sha1, NULL);
 230         return kind == OBJ_COMMIT;
 231 }
 232
 233 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 234 {
 235         struct object *obj;
 236         int kind;
 237
 238         kind = sha1_object_info(sha1, NULL);
 239         if (kind == OBJ_COMMIT)
 240                 return 1;
 241         if (kind != OBJ_TAG)
 242                 return 0;
 243
 244         /* We need to do this the hard way... */
 245         obj = deref_tag(parse_object(sha1), NULL, 0);
 246         if (obj && obj->type == OBJ_COMMIT)
 247                 return 1;
 248         return 0;
 249 }
 250
 251 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 252 {
 253         int kind = sha1_object_info(sha1, NULL);
 254         return kind == OBJ_TREE;
 255 }
 256
 257 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 258 {
 259         struct object *obj;
 260         int kind;
 261
 262         kind = sha1_object_info(sha1, NULL);
 263         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 264                 return 1;
 265         if (kind != OBJ_TAG)
 266                 return 0;
 267
 268         /* We need to do this the hard way... */
 269         obj = deref_tag(lookup_object(sha1), NULL, 0);
 270         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 271                 return 1;
 272         return 0;
 273 }
 274
 275 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 276 {
 277         int kind = sha1_object_info(sha1, NULL);
 278         return kind == OBJ_BLOB;
 279 }
 280
 281 static int prepare_prefixes(const char *name, int len,
 282                             unsigned char *bin_pfx,
 283                             char *hex_pfx)
 284 {
 285         int i;
 286
 287         hashclr(bin_pfx);
 288         memset(hex_pfx, 'x', 40);
 289         for (i = 0; i < len ;i++) {
 290                 unsigned char c = name[i];
 291                 unsigned char val;
 292                 if (c >= '0' && c <= '9')
 293                         val = c - '0';
 294                 else if (c >= 'a' && c <= 'f')
 295                         val = c - 'a' + 10;
 296                 else if (c >= 'A' && c <='F') {
 297                         val = c - 'A' + 10;
 298                         c -= 'A' - 'a';
 299                 }
 300                 else
 301                         return -1;
 302                 hex_pfx[i] = c;
 303                 if (!(i & 1))
 304                         val <<= 4;
 305                 bin_pfx[i >> 1] |= val;
 306         }
 307         return 0;
 308 }
 309
 310 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 311                           unsigned flags)
 312 {
 313         int status;
 314         char hex_pfx[40];
 315         unsigned char bin_pfx[20];
 316         struct disambiguate_state ds;
 317         int quietly = !!(flags & GET_SHA1_QUIETLY);
 318
 319         if (len < MINIMUM_ABBREV || len > 40)
 320                 return -1;
 321         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 322                 return -1;
 323
 324         prepare_alt_odb();
 325
 326         memset(&ds, 0, sizeof(ds));
 327         if (flags & GET_SHA1_COMMIT)
 328                 ds.fn = disambiguate_commit_only;
 329         else if (flags & GET_SHA1_COMMITTISH)
 330                 ds.fn = disambiguate_committish_only;
 331         else if (flags & GET_SHA1_TREE)
 332                 ds.fn = disambiguate_tree_only;
 333         else if (flags & GET_SHA1_TREEISH)
 334                 ds.fn = disambiguate_treeish_only;
 335         else if (flags & GET_SHA1_BLOB)
 336                 ds.fn = disambiguate_blob_only;
 337
 338         find_short_object_filename(len, hex_pfx, &ds);
 339         find_short_packed_object(len, bin_pfx, &ds);
 340         status = finish_object_disambiguation(&ds, sha1);
 341
 342         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 343                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 344         return status;
 345 }
 346
 347 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 348 {
 349         char hex_pfx[40];
 350         unsigned char bin_pfx[20];
 351         struct disambiguate_state ds;
 352         int len = strlen(prefix);
 353
 354         if (len < MINIMUM_ABBREV || len > 40)
 355                 return -1;
 356         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 357                 return -1;
 358
 359         prepare_alt_odb();
 360
 361         memset(&ds, 0, sizeof(ds));
 362         ds.always_call_fn = 1;
 363         ds.cb_data = cb_data;
 364         ds.fn = fn;
 365
 366         find_short_object_filename(len, hex_pfx, &ds);
 367         find_short_packed_object(len, bin_pfx, &ds);
 368         return ds.ambiguous;
 369 }
 370
 371 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 372 {
 373         int status, exists;
 374         static char hex[41];
 375
 376         memcpy(hex, sha1_to_hex(sha1), 40);
 377         if (len == 40 || !len)
 378                 return hex;
 379         exists = has_sha1_file(sha1);
 380         while (len < 40) {
 381                 unsigned char sha1_ret[20];
 382                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 383                 if (exists
 384                     ? !status
 385                     : status == SHORT_NAME_NOT_FOUND) {
 386                         hex[len] = 0;
 387                         return hex;
 388                 }
 389                 len++;
 390         }
 391         return hex;
 392 }
 393
 394 static int ambiguous_path(const char *path, int len)
 395 {
 396         int slash = 1;
 397         int cnt;
 398
 399         for (cnt = 0; cnt < len; cnt++) {
 400                 switch (*path++) {
 401                 case '\0':
 402                         break;
 403                 case '/':
 404                         if (slash)
 405                                 break;
 406                         slash = 1;
 407                         continue;
 408                 case '.':
 409                         continue;
 410                 default:
 411                         slash = 0;
 412                         continue;
 413                 }
 414                 break;
 415         }
 416         return slash;
 417 }
 418
 419 static inline int at_mark(const char *string, int len,
 420                           const char **suffix, int nr)
 421 {
 422         int i;
 423
 424         for (i = 0; i < nr; i++) {
 425                 int suffix_len = strlen(suffix[i]);
 426                 if (suffix_len <= len
 427                     && !memcmp(string, suffix[i], suffix_len))
 428                         return suffix_len;
 429         }
 430         return 0;
 431 }
 432
 433 static inline int upstream_mark(const char *string, int len)
 434 {
 435         const char *suffix[] = { "upstream", "u" };
 436         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 437 }
 438
 439 static inline int push_mark(const char *string, int len)
 440 {
 441         const char *suffix[] = { "push" };
 442         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 443 }
 444
 445 static inline int publish_mark(const char *string, int len)
 446 {
 447         const char *suffix[] = { "publish", "p" };
 448         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 449 }
 450
 451 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 452 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 453
 454 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 455                           unsigned int flags)
 456 {
 457         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 458         static const char *object_name_msg = N_(
 459         "Git normally never creates a ref that ends with 40 hex characters\n"
 460         "because it will be ignored when you just specify 40-hex. These refs\n"
 461         "may be created by mistake. For example,\n"
 462         "\n"
 463         "  git checkout -b $br $(git rev-parse ...)\n"
 464         "\n"
 465         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 466         "examine these refs and maybe delete them. Turn this message off by\n"
 467         "running \"git config advice.objectNameWarning false\"");
 468         unsigned char tmp_sha1[20];
 469         char *real_ref = NULL;
 470         int refs_found = 0;
 471         int at, reflog_len, nth_prior = 0;
 472
 473         if (len == 40 && !get_sha1_hex(str, sha1)) {
 474                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 475                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 476                         if (refs_found > 0) {
 477                                 warning(warn_msg, len, str);
 478                                 if (advice_object_name_warning)
 479                                         fprintf(stderr, "%s\n", _(object_name_msg));
 480                         }
 481                         free(real_ref);
 482                 }
 483                 return 0;
 484         }
 485
 486         /* basic@{time or number or -number} format to query ref-log */
 487         reflog_len = at = 0;
 488         if (len && str[len-1] == '}') {
 489                 for (at = len-4; at >= 0; at--) {
 490                         if (str[at] == '@' && str[at+1] == '{') {
 491                                 if (str[at+2] == '-') {
 492                                         if (at != 0)
 493                                                 /* @{-N} not at start */
 494                                                 return -1;
 495                                         nth_prior = 1;
 496                                         continue;
 497                                 }
 498                                 if (!upstream_mark(str + at + 2, len - at - 3) &&
 499                                     !push_mark(str + at + 2, len - at - 3) &&
 500                                     !publish_mark(str + at + 2, len - at - 3)) {
 501                                         reflog_len = (len-1) - (at+2);
 502                                         len = at;
 503                                 }
 504                                 break;
 505                         }
 506                 }
 507         }
 508
 509         /* Accept only unambiguous ref paths. */
 510         if (len && ambiguous_path(str, len))
 511                 return -1;
 512
 513         if (nth_prior) {
 514                 struct strbuf buf = STRBUF_INIT;
 515                 int detached;
 516
 517                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 518                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 519                         strbuf_release(&buf);
 520                         if (detached)
 521                                 return 0;
 522                 }
 523         }
 524
 525         if (!len && reflog_len)
 526                 /* allow "@{...}" to mean the current branch reflog */
 527                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 528         else if (reflog_len)
 529                 refs_found = dwim_log(str, len, sha1, &real_ref);
 530         else
 531                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 532
 533         if (!refs_found)
 534                 return -1;
 535
 536         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 537             (refs_found > 1 ||
 538              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 539                 warning(warn_msg, len, str);
 540
 541         if (reflog_len) {
 542                 int nth, i;
 543                 unsigned long at_time;
 544                 unsigned long co_time;
 545                 int co_tz, co_cnt;
 546
 547                 /* Is it asking for N-th entry, or approxidate? */
 548                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 549                         char ch = str[at+2+i];
 550                         if ('0' <= ch && ch <= '9')
 551                                 nth = nth * 10 + ch - '0';
 552                         else
 553                                 nth = -1;
 554                 }
 555                 if (100000000 <= nth) {
 556                         at_time = nth;
 557                         nth = -1;
 558                 } else if (0 <= nth)
 559                         at_time = 0;
 560                 else {
 561                         int errors = 0;
 562                         char *tmp = xstrndup(str + at + 2, reflog_len);
 563                         at_time = approxidate_careful(tmp, &errors);
 564                         free(tmp);
 565                         if (errors) {
 566                                 free(real_ref);
 567                                 return -1;
 568                         }
 569                 }
 570                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 571                                 &co_time, &co_tz, &co_cnt)) {
 572                         if (!len) {
 573                                 if (starts_with(real_ref, "refs/heads/")) {
 574                                         str = real_ref + 11;
 575                                         len = strlen(real_ref + 11);
 576                                 } else {
 577                                         /* detached HEAD */
 578                                         str = "HEAD";
 579                                         len = 4;
 580                                 }
 581                         }
 582                         if (at_time) {
 583                                 if (!(flags & GET_SHA1_QUIETLY)) {
 584                                         warning("Log for '%.*s' only goes "
 585                                                 "back to %s.", len, str,
 586                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 587                                 }
 588                         } else {
 589                                 if (flags & GET_SHA1_QUIETLY) {
 590                                         exit(128);
 591                                 }
 592                                 die("Log for '%.*s' only has %d entries.",
 593                                     len, str, co_cnt);
 594                         }
 595                 }
 596         }
 597
 598         free(real_ref);
 599         return 0;
 600 }
 601
 602 static int get_parent(const char *name, int len,
 603                       unsigned char *result, int idx)
 604 {
 605         unsigned char sha1[20];
 606         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 607         struct commit *commit;
 608         struct commit_list *p;
 609
 610         if (ret)
 611                 return ret;
 612         commit = lookup_commit_reference(sha1);
 613         if (parse_commit(commit))
 614                 return -1;
 615         if (!idx) {
 616                 hashcpy(result, commit->object.sha1);
 617                 return 0;
 618         }
 619         p = commit->parents;
 620         while (p) {
 621                 if (!--idx) {
 622                         hashcpy(result, p->item->object.sha1);
 623                         return 0;
 624                 }
 625                 p = p->next;
 626         }
 627         return -1;
 628 }
 629
 630 static int get_nth_ancestor(const char *name, int len,
 631                             unsigned char *result, int generation)
 632 {
 633         unsigned char sha1[20];
 634         struct commit *commit;
 635         int ret;
 636
 637         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 638         if (ret)
 639                 return ret;
 640         commit = lookup_commit_reference(sha1);
 641         if (!commit)
 642                 return -1;
 643
 644         while (generation--) {
 645                 if (parse_commit(commit) || !commit->parents)
 646                         return -1;
 647                 commit = commit->parents->item;
 648         }
 649         hashcpy(result, commit->object.sha1);
 650         return 0;
 651 }
 652
 653 struct object *peel_to_type(const char *name, int namelen,
 654                             struct object *o, enum object_type expected_type)
 655 {
 656         if (name && !namelen)
 657                 namelen = strlen(name);
 658         while (1) {
 659                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 660                         return NULL;
 661                 if (expected_type == OBJ_ANY || o->type == expected_type)
 662                         return o;
 663                 if (o->type == OBJ_TAG)
 664                         o = ((struct tag*) o)->tagged;
 665                 else if (o->type == OBJ_COMMIT)
 666                         o = &(((struct commit *) o)->tree->object);
 667                 else {
 668                         if (name)
 669                                 error("%.*s: expected %s type, but the object "
 670                                       "dereferences to %s type",
 671                                       namelen, name, typename(expected_type),
 672                                       typename(o->type));
 673                         return NULL;
 674                 }
 675         }
 676 }
 677
 678 static int peel_onion(const char *name, int len, unsigned char *sha1)
 679 {
 680         unsigned char outer[20];
 681         const char *sp;
 682         unsigned int expected_type = 0;
 683         unsigned lookup_flags = 0;
 684         struct object *o;
 685
 686         /*
 687          * "ref^{type}" dereferences ref repeatedly until you cannot
 688          * dereference anymore, or you get an object of given type,
 689          * whichever comes first.  "ref^{}" means just dereference
 690          * tags until you get a non-tag.  "ref^0" is a shorthand for
 691          * "ref^{commit}".  "commit^{tree}" could be used to find the
 692          * top-level tree of the given commit.
 693          */
 694         if (len < 4 || name[len-1] != '}')
 695                 return -1;
 696
 697         for (sp = name + len - 1; name <= sp; sp--) {
 698                 int ch = *sp;
 699                 if (ch == '{' && name < sp && sp[-1] == '^')
 700                         break;
 701         }
 702         if (sp <= name)
 703                 return -1;
 704
 705         sp++; /* beginning of type name, or closing brace for empty */
 706         if (starts_with(sp, "commit}"))
 707                 expected_type = OBJ_COMMIT;
 708         else if (starts_with(sp, "tag}"))
 709                 expected_type = OBJ_TAG;
 710         else if (starts_with(sp, "tree}"))
 711                 expected_type = OBJ_TREE;
 712         else if (starts_with(sp, "blob}"))
 713                 expected_type = OBJ_BLOB;
 714         else if (starts_with(sp, "object}"))
 715                 expected_type = OBJ_ANY;
 716         else if (sp[0] == '}')
 717                 expected_type = OBJ_NONE;
 718         else if (sp[0] == '/')
 719                 expected_type = OBJ_COMMIT;
 720         else
 721                 return -1;
 722
 723         if (expected_type == OBJ_COMMIT)
 724                 lookup_flags = GET_SHA1_COMMITTISH;
 725         else if (expected_type == OBJ_TREE)
 726                 lookup_flags = GET_SHA1_TREEISH;
 727
 728         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 729                 return -1;
 730
 731         o = parse_object(outer);
 732         if (!o)
 733                 return -1;
 734         if (!expected_type) {
 735                 o = deref_tag(o, name, sp - name - 2);
 736                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 737                         return -1;
 738                 hashcpy(sha1, o->sha1);
 739                 return 0;
 740         }
 741
 742         /*
 743          * At this point, the syntax look correct, so
 744          * if we do not get the needed object, we should
 745          * barf.
 746          */
 747         o = peel_to_type(name, len, o, expected_type);
 748         if (!o)
 749                 return -1;
 750
 751         hashcpy(sha1, o->sha1);
 752         if (sp[0] == '/') {
 753                 /* "$commit^{/foo}" */
 754                 char *prefix;
 755                 int ret;
 756                 struct commit_list *list = NULL;
 757
 758                 /*
 759                  * $commit^{/}. Some regex implementation may reject.
 760                  * We don't need regex anyway. '' pattern always matches.
 761                  */
 762                 if (sp[1] == '}')
 763                         return 0;
 764
 765                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 766                 commit_list_insert((struct commit *)o, &list);
 767                 ret = get_sha1_oneline(prefix, sha1, list);
 768                 free(prefix);
 769                 return ret;
 770         }
 771         return 0;
 772 }
 773
 774 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 775 {
 776         const char *cp;
 777         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 778
 779         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 780                 char ch = *cp;
 781                 if (!isxdigit(ch)) {
 782                         /* We must be looking at g in "SOMETHING-g"
 783                          * for it to be describe output.
 784                          */
 785                         if (ch == 'g' && cp[-1] == '-') {
 786                                 cp++;
 787                                 len -= cp - name;
 788                                 return get_short_sha1(cp, len, sha1, flags);
 789                         }
 790                 }
 791         }
 792         return -1;
 793 }
 794
 795 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 796 {
 797         int ret, has_suffix;
 798         const char *cp;
 799
 800         /*
 801          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 802          */
 803         has_suffix = 0;
 804         for (cp = name + len - 1; name <= cp; cp--) {
 805                 int ch = *cp;
 806                 if ('0' <= ch && ch <= '9')
 807                         continue;
 808                 if (ch == '~' || ch == '^')
 809                         has_suffix = ch;
 810                 break;
 811         }
 812
 813         if (has_suffix) {
 814                 int num = 0;
 815                 int len1 = cp - name;
 816                 cp++;
 817                 while (cp < name + len)
 818                         num = num * 10 + *cp++ - '0';
 819                 if (!num && len1 == len - 1)
 820                         num = 1;
 821                 if (has_suffix == '^')
 822                         return get_parent(name, len1, sha1, num);
 823                 /* else if (has_suffix == '~') -- goes without saying */
 824                 return get_nth_ancestor(name, len1, sha1, num);
 825         }
 826
 827         ret = peel_onion(name, len, sha1);
 828         if (!ret)
 829                 return 0;
 830
 831         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 832         if (!ret)
 833                 return 0;
 834
 835         /* It could be describe output that is "SOMETHING-gXXXX" */
 836         ret = get_describe_name(name, len, sha1);
 837         if (!ret)
 838                 return 0;
 839
 840         return get_short_sha1(name, len, sha1, lookup_flags);
 841 }
 842
 843 /*
 844  * This interprets names like ':/Initial revision of "git"' by searching
 845  * through history and returning the first commit whose message starts
 846  * the given regular expression.
 847  *
 848  * For future extension, ':/!' is reserved. If you want to match a message
 849  * beginning with a '!', you have to repeat the exclamation mark.
 850  */
 851
 852 /* Remember to update object flag allocation in object.h */
 853 #define ONELINE_SEEN (1u<<20)
 854
 855 static int handle_one_ref(const char *path, const struct object_id *oid,
 856                           int flag, void *cb_data)
 857 {
 858         struct commit_list **list = cb_data;
 859         struct object *object = parse_object(oid->hash);
 860         if (!object)
 861                 return 0;
 862         if (object->type == OBJ_TAG) {
 863                 object = deref_tag(object, path, strlen(path));
 864                 if (!object)
 865                         return 0;
 866         }
 867         if (object->type != OBJ_COMMIT)
 868                 return 0;
 869         commit_list_insert((struct commit *)object, list);
 870         return 0;
 871 }
 872
 873 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 874                             struct commit_list *list)
 875 {
 876         struct commit_list *backup = NULL, *l;
 877         int found = 0;
 878         regex_t regex;
 879
 880         if (prefix[0] == '!') {
 881                 if (prefix[1] != '!')
 882                         die ("Invalid search pattern: %s", prefix);
 883                 prefix++;
 884         }
 885
 886         if (regcomp(&regex, prefix, REG_EXTENDED))
 887                 die("Invalid search pattern: %s", prefix);
 888
 889         for (l = list; l; l = l->next) {
 890                 l->item->object.flags |= ONELINE_SEEN;
 891                 commit_list_insert(l->item, &backup);
 892         }
 893         while (list) {
 894                 const char *p, *buf;
 895                 struct commit *commit;
 896                 int matches;
 897
 898                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 899                 if (!parse_object(commit->object.sha1))
 900                         continue;
 901                 buf = get_commit_buffer(commit, NULL);
 902                 p = strstr(buf, "\n\n");
 903                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 904                 unuse_commit_buffer(commit, buf);
 905
 906                 if (matches) {
 907                         hashcpy(sha1, commit->object.sha1);
 908                         found = 1;
 909                         break;
 910                 }
 911         }
 912         regfree(&regex);
 913         free_commit_list(list);
 914         for (l = backup; l; l = l->next)
 915                 clear_commit_marks(l->item, ONELINE_SEEN);
 916         free_commit_list(backup);
 917         return found ? 0 : -1;
 918 }
 919
 920 struct grab_nth_branch_switch_cbdata {
 921         int remaining;
 922         struct strbuf buf;
 923 };
 924
 925 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 926                                   const char *email, unsigned long timestamp, int tz,
 927                                   const char *message, void *cb_data)
 928 {
 929         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 930         const char *match = NULL, *target = NULL;
 931         size_t len;
 932
 933         if (skip_prefix(message, "checkout: moving from ", &match))
 934                 target = strstr(match, " to ");
 935
 936         if (!match || !target)
 937                 return 0;
 938         if (--(cb->remaining) == 0) {
 939                 len = target - match;
 940                 strbuf_reset(&cb->buf);
 941                 strbuf_add(&cb->buf, match, len);
 942                 return 1; /* we are done */
 943         }
 944         return 0;
 945 }
 946
 947 /*
 948  * Parse @{-N} syntax, return the number of characters parsed
 949  * if successful; otherwise signal an error with negative value.
 950  */
 951 static int interpret_nth_prior_checkout(const char *name, int namelen,
 952                                         struct strbuf *buf)
 953 {
 954         long nth;
 955         int retval;
 956         struct grab_nth_branch_switch_cbdata cb;
 957         const char *brace;
 958         char *num_end;
 959
 960         if (namelen < 4)
 961                 return -1;
 962         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 963                 return -1;
 964         brace = memchr(name, '}', namelen);
 965         if (!brace)
 966                 return -1;
 967         nth = strtol(name + 3, &num_end, 10);
 968         if (num_end != brace)
 969                 return -1;
 970         if (nth <= 0)
 971                 return -1;
 972         cb.remaining = nth;
 973         strbuf_init(&cb.buf, 20);
 974
 975         retval = 0;
 976         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 977                 strbuf_reset(buf);
 978                 strbuf_addbuf(buf, &cb.buf);
 979                 retval = brace - name + 1;
 980         }
 981
 982         strbuf_release(&cb.buf);
 983         return retval;
 984 }
 985
 986 int get_sha1_mb(const char *name, unsigned char *sha1)
 987 {
 988         struct commit *one, *two;
 989         struct commit_list *mbs;
 990         unsigned char sha1_tmp[20];
 991         const char *dots;
 992         int st;
 993
 994         dots = strstr(name, "...");
 995         if (!dots)
 996                 return get_sha1(name, sha1);
 997         if (dots == name)
 998                 st = get_sha1("HEAD", sha1_tmp);
 999         else {
1000                 struct strbuf sb;
1001                 strbuf_init(&sb, dots - name);
1002                 strbuf_add(&sb, name, dots - name);
1003                 st = get_sha1_committish(sb.buf, sha1_tmp);
1004                 strbuf_release(&sb);
1005         }
1006         if (st)
1007                 return st;
1008         one = lookup_commit_reference_gently(sha1_tmp, 0);
1009         if (!one)
1010                 return -1;
1011
1012         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
1013                 return -1;
1014         two = lookup_commit_reference_gently(sha1_tmp, 0);
1015         if (!two)
1016                 return -1;
1017         mbs = get_merge_bases(one, two);
1018         if (!mbs || mbs->next)
1019                 st = -1;
1020         else {
1021                 st = 0;
1022                 hashcpy(sha1, mbs->item->object.sha1);
1023         }
1024         free_commit_list(mbs);
1025         return st;
1026 }
1027
1028 /* parse @something syntax, when 'something' is not {.*} */
1029 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1030 {
1031         const char *next;
1032
1033         if (len || name[1] == '{')
1034                 return -1;
1035
1036         /* make sure it's a single @, or @@{.*}, not @foo */
1037         next = memchr(name + len + 1, '@', namelen - len - 1);
1038         if (next && next[1] != '{')
1039                 return -1;
1040         if (!next)
1041                 next = name + namelen;
1042         if (next != name + 1)
1043                 return -1;
1044
1045         strbuf_reset(buf);
1046         strbuf_add(buf, "HEAD", 4);
1047         return 1;
1048 }
1049
1050 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1051 {
1052         /* we have extra data, which might need further processing */
1053         struct strbuf tmp = STRBUF_INIT;
1054         int used = buf->len;
1055         int ret;
1056
1057         strbuf_add(buf, name + len, namelen - len);
1058         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1059         /* that data was not interpreted, remove our cruft */
1060         if (ret < 0) {
1061                 strbuf_setlen(buf, used);
1062                 return len;
1063         }
1064         strbuf_reset(buf);
1065         strbuf_addbuf(buf, &tmp);
1066         strbuf_release(&tmp);
1067         /* tweak for size of {-N} versus expanded ref name */
1068         return ret - used + len;
1069 }
1070
1071 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1072 {
1073         char *s = shorten_unambiguous_ref(ref, 0);
1074         strbuf_reset(buf);
1075         strbuf_addstr(buf, s);
1076         free(s);
1077 }
1078
1079 static int interpret_branch_mark(const char *name, int namelen,
1080                                  int at, struct strbuf *buf,
1081                                  int (*get_mark)(const char *, int),
1082                                  const char *(*get_data)(struct branch *,
1083                                                          struct strbuf *))
1084 {
1085         int len;
1086         struct branch *branch;
1087         struct strbuf err = STRBUF_INIT;
1088         const char *value;
1089
1090         if (name[at + 1] != '{' || name[namelen - 1] != '}')
1091                 return -1;
1092
1093         len = get_mark(name + at + 2, namelen - at - 3);
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 + 3;
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                 len = interpret_branch_mark(name, namelen, at - name, buf,
1173                                             publish_mark, branch_get_publish);
1174                 if (len > 0)
1175                         return len;
1176         }
1177
1178         return -1;
1179 }
1180
1181 int strbuf_branchname(struct strbuf *sb, const char *name)
1182 {
1183         int len = strlen(name);
1184         int used = interpret_branch_name(name, len, sb);
1185
1186         if (used == len)
1187                 return 0;
1188         if (used < 0)
1189                 used = 0;
1190         strbuf_add(sb, name + used, len - used);
1191         return len;
1192 }
1193
1194 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1195 {
1196         strbuf_branchname(sb, name);
1197         if (name[0] == '-')
1198                 return -1;
1199         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1200         return check_refname_format(sb->buf, 0);
1201 }
1202
1203 /*
1204  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1205  * notably "xyz^" for "parent of xyz"
1206  */
1207 int get_sha1(const char *name, unsigned char *sha1)
1208 {
1209         struct object_context unused;
1210         return get_sha1_with_context(name, 0, sha1, &unused);
1211 }
1212
1213 /*
1214  * Many callers know that the user meant to name a commit-ish by
1215  * syntactical positions where the object name appears.  Calling this
1216  * function allows the machinery to disambiguate shorter-than-unique
1217  * abbreviated object names between commit-ish and others.
1218  *
1219  * Note that this does NOT error out when the named object is not a
1220  * commit-ish. It is merely to give a hint to the disambiguation
1221  * machinery.
1222  */
1223 int get_sha1_committish(const char *name, unsigned char *sha1)
1224 {
1225         struct object_context unused;
1226         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1227                                      sha1, &unused);
1228 }
1229
1230 int get_sha1_treeish(const char *name, unsigned char *sha1)
1231 {
1232         struct object_context unused;
1233         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1234                                      sha1, &unused);
1235 }
1236
1237 int get_sha1_commit(const char *name, unsigned char *sha1)
1238 {
1239         struct object_context unused;
1240         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1241                                      sha1, &unused);
1242 }
1243
1244 int get_sha1_tree(const char *name, unsigned char *sha1)
1245 {
1246         struct object_context unused;
1247         return get_sha1_with_context(name, GET_SHA1_TREE,
1248                                      sha1, &unused);
1249 }
1250
1251 int get_sha1_blob(const char *name, unsigned char *sha1)
1252 {
1253         struct object_context unused;
1254         return get_sha1_with_context(name, GET_SHA1_BLOB,
1255                                      sha1, &unused);
1256 }
1257
1258 /* Must be called only when object_name:filename doesn't exist. */
1259 static void diagnose_invalid_sha1_path(const char *prefix,
1260                                        const char *filename,
1261                                        const unsigned char *tree_sha1,
1262                                        const char *object_name,
1263                                        int object_name_len)
1264 {
1265         unsigned char sha1[20];
1266         unsigned mode;
1267
1268         if (!prefix)
1269                 prefix = "";
1270
1271         if (file_exists(filename))
1272                 die("Path '%s' exists on disk, but not in '%.*s'.",
1273                     filename, object_name_len, object_name);
1274         if (errno == ENOENT || errno == ENOTDIR) {
1275                 char *fullname = xstrfmt("%s%s", prefix, filename);
1276
1277                 if (!get_tree_entry(tree_sha1, fullname,
1278                                     sha1, &mode)) {
1279                         die("Path '%s' exists, but not '%s'.\n"
1280                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1281                             fullname,
1282                             filename,
1283                             object_name_len, object_name,
1284                             fullname,
1285                             object_name_len, object_name,
1286                             filename);
1287                 }
1288                 die("Path '%s' does not exist in '%.*s'",
1289                     filename, object_name_len, object_name);
1290         }
1291 }
1292
1293 /* Must be called only when :stage:filename doesn't exist. */
1294 static void diagnose_invalid_index_path(int stage,
1295                                         const char *prefix,
1296                                         const char *filename)
1297 {
1298         const struct cache_entry *ce;
1299         int pos;
1300         unsigned namelen = strlen(filename);
1301         unsigned fullnamelen;
1302         char *fullname;
1303
1304         if (!prefix)
1305                 prefix = "";
1306
1307         /* Wrong stage number? */
1308         pos = cache_name_pos(filename, namelen);
1309         if (pos < 0)
1310                 pos = -pos - 1;
1311         if (pos < active_nr) {
1312                 ce = active_cache[pos];
1313                 if (ce_namelen(ce) == namelen &&
1314                     !memcmp(ce->name, filename, namelen))
1315                         die("Path '%s' is in the index, but not at stage %d.\n"
1316                             "Did you mean ':%d:%s'?",
1317                             filename, stage,
1318                             ce_stage(ce), filename);
1319         }
1320
1321         /* Confusion between relative and absolute filenames? */
1322         fullnamelen = namelen + strlen(prefix);
1323         fullname = xmalloc(fullnamelen + 1);
1324         strcpy(fullname, prefix);
1325         strcat(fullname, filename);
1326         pos = cache_name_pos(fullname, fullnamelen);
1327         if (pos < 0)
1328                 pos = -pos - 1;
1329         if (pos < active_nr) {
1330                 ce = active_cache[pos];
1331                 if (ce_namelen(ce) == fullnamelen &&
1332                     !memcmp(ce->name, fullname, fullnamelen))
1333                         die("Path '%s' is in the index, but not '%s'.\n"
1334                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1335                             fullname, filename,
1336                             ce_stage(ce), fullname,
1337                             ce_stage(ce), filename);
1338         }
1339
1340         if (file_exists(filename))
1341                 die("Path '%s' exists on disk, but not in the index.", filename);
1342         if (errno == ENOENT || errno == ENOTDIR)
1343                 die("Path '%s' does not exist (neither on disk nor in the index).",
1344                     filename);
1345
1346         free(fullname);
1347 }
1348
1349
1350 static char *resolve_relative_path(const char *rel)
1351 {
1352         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1353                 return NULL;
1354
1355         if (!startup_info)
1356                 die("BUG: startup_info struct is not initialized.");
1357
1358         if (!is_inside_work_tree())
1359                 die("relative path syntax can't be used outside working tree.");
1360
1361         /* die() inside prefix_path() if resolved path is outside worktree */
1362         return prefix_path(startup_info->prefix,
1363                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1364                            rel);
1365 }
1366
1367 static int get_sha1_with_context_1(const char *name,
1368                                    unsigned flags,
1369                                    const char *prefix,
1370                                    unsigned char *sha1,
1371                                    struct object_context *oc)
1372 {
1373         int ret, bracket_depth;
1374         int namelen = strlen(name);
1375         const char *cp;
1376         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1377
1378         memset(oc, 0, sizeof(*oc));
1379         oc->mode = S_IFINVALID;
1380         ret = get_sha1_1(name, namelen, sha1, flags);
1381         if (!ret)
1382                 return ret;
1383         /*
1384          * sha1:path --> object name of path in ent sha1
1385          * :path -> object name of absolute path in index
1386          * :./path -> object name of path relative to cwd in index
1387          * :[0-3]:path -> object name of path in index at stage
1388          * :/foo -> recent commit matching foo
1389          */
1390         if (name[0] == ':') {
1391                 int stage = 0;
1392                 const struct cache_entry *ce;
1393                 char *new_path = NULL;
1394                 int pos;
1395                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1396                         struct commit_list *list = NULL;
1397
1398                         for_each_ref(handle_one_ref, &list);
1399                         commit_list_sort_by_date(&list);
1400                         return get_sha1_oneline(name + 2, sha1, list);
1401                 }
1402                 if (namelen < 3 ||
1403                     name[2] != ':' ||
1404                     name[1] < '0' || '3' < name[1])
1405                         cp = name + 1;
1406                 else {
1407                         stage = name[1] - '0';
1408                         cp = name + 3;
1409                 }
1410                 new_path = resolve_relative_path(cp);
1411                 if (!new_path) {
1412                         namelen = namelen - (cp - name);
1413                 } else {
1414                         cp = new_path;
1415                         namelen = strlen(cp);
1416                 }
1417
1418                 strlcpy(oc->path, cp, sizeof(oc->path));
1419
1420                 if (!active_cache)
1421                         read_cache();
1422                 pos = cache_name_pos(cp, namelen);
1423                 if (pos < 0)
1424                         pos = -pos - 1;
1425                 while (pos < active_nr) {
1426                         ce = active_cache[pos];
1427                         if (ce_namelen(ce) != namelen ||
1428                             memcmp(ce->name, cp, namelen))
1429                                 break;
1430                         if (ce_stage(ce) == stage) {
1431                                 hashcpy(sha1, ce->sha1);
1432                                 oc->mode = ce->ce_mode;
1433                                 free(new_path);
1434                                 return 0;
1435                         }
1436                         pos++;
1437                 }
1438                 if (only_to_die && name[1] && name[1] != '/')
1439                         diagnose_invalid_index_path(stage, prefix, cp);
1440                 free(new_path);
1441                 return -1;
1442         }
1443         for (cp = name, bracket_depth = 0; *cp; cp++) {
1444                 if (*cp == '{')
1445                         bracket_depth++;
1446                 else if (bracket_depth && *cp == '}')
1447                         bracket_depth--;
1448                 else if (!bracket_depth && *cp == ':')
1449                         break;
1450         }
1451         if (*cp == ':') {
1452                 unsigned char tree_sha1[20];
1453                 int len = cp - name;
1454                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1455                         const char *filename = cp+1;
1456                         char *new_filename = NULL;
1457
1458                         new_filename = resolve_relative_path(filename);
1459                         if (new_filename)
1460                                 filename = new_filename;
1461                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1462                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1463                                         filename, sha1, &oc->symlink_path,
1464                                         &oc->mode);
1465                         } else {
1466                                 ret = get_tree_entry(tree_sha1, filename,
1467                                                      sha1, &oc->mode);
1468                                 if (ret && only_to_die) {
1469                                         diagnose_invalid_sha1_path(prefix,
1470                                                                    filename,
1471                                                                    tree_sha1,
1472                                                                    name, len);
1473                                 }
1474                         }
1475                         hashcpy(oc->tree, tree_sha1);
1476                         strlcpy(oc->path, filename, sizeof(oc->path));
1477
1478                         free(new_filename);
1479                         return ret;
1480                 } else {
1481                         if (only_to_die)
1482                                 die("Invalid object name '%.*s'.", len, name);
1483                 }
1484         }
1485         return ret;
1486 }
1487
1488 /*
1489  * Call this function when you know "name" given by the end user must
1490  * name an object but it doesn't; the function _may_ die with a better
1491  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1492  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1493  * you have a chance to diagnose the error further.
1494  */
1495 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1496 {
1497         struct object_context oc;
1498         unsigned char sha1[20];
1499         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1500 }
1501
1502 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1503 {
1504         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1505                 die("BUG: incompatible flags for get_sha1_with_context");
1506         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1507 }