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                 size_t objdir_len = strlen(objdir);
  91                 fakeent = xmalloc(st_add3(sizeof(*fakeent), objdir_len, 43));
  92                 memcpy(fakeent->base, objdir, objdir_len);
  93                 fakeent->name = fakeent->base + objdir_len + 1;
  94                 fakeent->name[-1] = '/';
  95         }
  96         fakeent->next = alt_odb_list;
  97
  98         xsnprintf(hex, sizeof(hex), "%.2s", hex_pfx);
  99         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 100                 struct dirent *de;
 101                 DIR *dir;
 102                 /*
 103                  * every alt_odb struct has 42 extra bytes after the base
 104                  * for exactly this purpose
 105                  */
 106                 xsnprintf(alt->name, 42, "%.2s/", hex_pfx);
 107                 dir = opendir(alt->base);
 108                 if (!dir)
 109                         continue;
 110
 111                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 112                         unsigned char sha1[20];
 113
 114                         if (strlen(de->d_name) != 38)
 115                                 continue;
 116                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 117                                 continue;
 118                         memcpy(hex + 2, de->d_name, 38);
 119                         if (!get_sha1_hex(hex, sha1))
 120                                 update_candidates(ds, sha1);
 121                 }
 122                 closedir(dir);
 123         }
 124 }
 125
 126 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 127 {
 128         do {
 129                 if (*a != *b)
 130                         return 0;
 131                 a++;
 132                 b++;
 133                 len -= 2;
 134         } while (len > 1);
 135         if (len)
 136                 if ((*a ^ *b) & 0xf0)
 137                         return 0;
 138         return 1;
 139 }
 140
 141 static void unique_in_pack(int len,
 142                           const unsigned char *bin_pfx,
 143                            struct packed_git *p,
 144                            struct disambiguate_state *ds)
 145 {
 146         uint32_t num, last, i, first = 0;
 147         const unsigned char *current = NULL;
 148
 149         open_pack_index(p);
 150         num = p->num_objects;
 151         last = num;
 152         while (first < last) {
 153                 uint32_t mid = (first + last) / 2;
 154                 const unsigned char *current;
 155                 int cmp;
 156
 157                 current = nth_packed_object_sha1(p, mid);
 158                 cmp = hashcmp(bin_pfx, current);
 159                 if (!cmp) {
 160                         first = mid;
 161                         break;
 162                 }
 163                 if (cmp > 0) {
 164                         first = mid+1;
 165                         continue;
 166                 }
 167                 last = mid;
 168         }
 169
 170         /*
 171          * At this point, "first" is the location of the lowest object
 172          * with an object name that could match "bin_pfx".  See if we have
 173          * 0, 1 or more objects that actually match(es).
 174          */
 175         for (i = first; i < num && !ds->ambiguous; i++) {
 176                 current = nth_packed_object_sha1(p, i);
 177                 if (!match_sha(len, bin_pfx, current))
 178                         break;
 179                 update_candidates(ds, current);
 180         }
 181 }
 182
 183 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 184                                      struct disambiguate_state *ds)
 185 {
 186         struct packed_git *p;
 187
 188         prepare_packed_git();
 189         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 190                 unique_in_pack(len, bin_pfx, p, ds);
 191 }
 192
 193 #define SHORT_NAME_NOT_FOUND (-1)
 194 #define SHORT_NAME_AMBIGUOUS (-2)
 195
 196 static int finish_object_disambiguation(struct disambiguate_state *ds,
 197                                         unsigned char *sha1)
 198 {
 199         if (ds->ambiguous)
 200                 return SHORT_NAME_AMBIGUOUS;
 201
 202         if (!ds->candidate_exists)
 203                 return SHORT_NAME_NOT_FOUND;
 204
 205         if (!ds->candidate_checked)
 206                 /*
 207                  * If this is the only candidate, there is no point
 208                  * calling the disambiguation hint callback.
 209                  *
 210                  * On the other hand, if the current candidate
 211                  * replaced an earlier candidate that did _not_ pass
 212                  * the disambiguation hint callback, then we do have
 213                  * more than one objects that match the short name
 214                  * given, so we should make sure this one matches;
 215                  * otherwise, if we discovered this one and the one
 216                  * that we previously discarded in the reverse order,
 217                  * we would end up showing different results in the
 218                  * same repository!
 219                  */
 220                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 221                                     ds->fn(ds->candidate, ds->cb_data));
 222
 223         if (!ds->candidate_ok)
 224                 return SHORT_NAME_AMBIGUOUS;
 225
 226         hashcpy(sha1, ds->candidate);
 227         return 0;
 228 }
 229
 230 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 231 {
 232         int kind = sha1_object_info(sha1, NULL);
 233         return kind == OBJ_COMMIT;
 234 }
 235
 236 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 237 {
 238         struct object *obj;
 239         int kind;
 240
 241         kind = sha1_object_info(sha1, NULL);
 242         if (kind == OBJ_COMMIT)
 243                 return 1;
 244         if (kind != OBJ_TAG)
 245                 return 0;
 246
 247         /* We need to do this the hard way... */
 248         obj = deref_tag(parse_object(sha1), NULL, 0);
 249         if (obj && obj->type == OBJ_COMMIT)
 250                 return 1;
 251         return 0;
 252 }
 253
 254 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 255 {
 256         int kind = sha1_object_info(sha1, NULL);
 257         return kind == OBJ_TREE;
 258 }
 259
 260 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 261 {
 262         struct object *obj;
 263         int kind;
 264
 265         kind = sha1_object_info(sha1, NULL);
 266         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 267                 return 1;
 268         if (kind != OBJ_TAG)
 269                 return 0;
 270
 271         /* We need to do this the hard way... */
 272         obj = deref_tag(lookup_object(sha1), NULL, 0);
 273         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 274                 return 1;
 275         return 0;
 276 }
 277
 278 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 279 {
 280         int kind = sha1_object_info(sha1, NULL);
 281         return kind == OBJ_BLOB;
 282 }
 283
 284 static int prepare_prefixes(const char *name, int len,
 285                             unsigned char *bin_pfx,
 286                             char *hex_pfx)
 287 {
 288         int i;
 289
 290         hashclr(bin_pfx);
 291         memset(hex_pfx, 'x', 40);
 292         for (i = 0; i < len ;i++) {
 293                 unsigned char c = name[i];
 294                 unsigned char val;
 295                 if (c >= '0' && c <= '9')
 296                         val = c - '0';
 297                 else if (c >= 'a' && c <= 'f')
 298                         val = c - 'a' + 10;
 299                 else if (c >= 'A' && c <='F') {
 300                         val = c - 'A' + 10;
 301                         c -= 'A' - 'a';
 302                 }
 303                 else
 304                         return -1;
 305                 hex_pfx[i] = c;
 306                 if (!(i & 1))
 307                         val <<= 4;
 308                 bin_pfx[i >> 1] |= val;
 309         }
 310         return 0;
 311 }
 312
 313 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 314                           unsigned flags)
 315 {
 316         int status;
 317         char hex_pfx[40];
 318         unsigned char bin_pfx[20];
 319         struct disambiguate_state ds;
 320         int quietly = !!(flags & GET_SHA1_QUIETLY);
 321
 322         if (len < MINIMUM_ABBREV || len > 40)
 323                 return -1;
 324         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 325                 return -1;
 326
 327         prepare_alt_odb();
 328
 329         memset(&ds, 0, sizeof(ds));
 330         if (flags & GET_SHA1_COMMIT)
 331                 ds.fn = disambiguate_commit_only;
 332         else if (flags & GET_SHA1_COMMITTISH)
 333                 ds.fn = disambiguate_committish_only;
 334         else if (flags & GET_SHA1_TREE)
 335                 ds.fn = disambiguate_tree_only;
 336         else if (flags & GET_SHA1_TREEISH)
 337                 ds.fn = disambiguate_treeish_only;
 338         else if (flags & GET_SHA1_BLOB)
 339                 ds.fn = disambiguate_blob_only;
 340
 341         find_short_object_filename(len, hex_pfx, &ds);
 342         find_short_packed_object(len, bin_pfx, &ds);
 343         status = finish_object_disambiguation(&ds, sha1);
 344
 345         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 346                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 347         return status;
 348 }
 349
 350 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 351 {
 352         char hex_pfx[40];
 353         unsigned char bin_pfx[20];
 354         struct disambiguate_state ds;
 355         int len = strlen(prefix);
 356
 357         if (len < MINIMUM_ABBREV || len > 40)
 358                 return -1;
 359         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 360                 return -1;
 361
 362         prepare_alt_odb();
 363
 364         memset(&ds, 0, sizeof(ds));
 365         ds.always_call_fn = 1;
 366         ds.cb_data = cb_data;
 367         ds.fn = fn;
 368
 369         find_short_object_filename(len, hex_pfx, &ds);
 370         find_short_packed_object(len, bin_pfx, &ds);
 371         return ds.ambiguous;
 372 }
 373
 374 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 375 {
 376         int status, exists;
 377
 378         sha1_to_hex_r(hex, sha1);
 379         if (len == 40 || !len)
 380                 return 40;
 381         exists = has_sha1_file(sha1);
 382         while (len < 40) {
 383                 unsigned char sha1_ret[20];
 384                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 385                 if (exists
 386                     ? !status
 387                     : status == SHORT_NAME_NOT_FOUND) {
 388                         hex[len] = 0;
 389                         return len;
 390                 }
 391                 len++;
 392         }
 393         return len;
 394 }
 395
 396 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 397 {
 398         static char hex[GIT_SHA1_HEXSZ + 1];
 399         find_unique_abbrev_r(hex, sha1, len);
 400         return hex;
 401 }
 402
 403 static int ambiguous_path(const char *path, int len)
 404 {
 405         int slash = 1;
 406         int cnt;
 407
 408         for (cnt = 0; cnt < len; cnt++) {
 409                 switch (*path++) {
 410                 case '\0':
 411                         break;
 412                 case '/':
 413                         if (slash)
 414                                 break;
 415                         slash = 1;
 416                         continue;
 417                 case '.':
 418                         continue;
 419                 default:
 420                         slash = 0;
 421                         continue;
 422                 }
 423                 break;
 424         }
 425         return slash;
 426 }
 427
 428 static inline int at_mark(const char *string, int len,
 429                           const char **suffix, int nr)
 430 {
 431         int i;
 432
 433         for (i = 0; i < nr; i++) {
 434                 int suffix_len = strlen(suffix[i]);
 435                 if (suffix_len <= len
 436                     && !memcmp(string, suffix[i], suffix_len))
 437                         return suffix_len;
 438         }
 439         return 0;
 440 }
 441
 442 static inline int upstream_mark(const char *string, int len)
 443 {
 444         const char *suffix[] = { "@{upstream}", "@{u}" };
 445         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 446 }
 447
 448 static inline int push_mark(const char *string, int len)
 449 {
 450         const char *suffix[] = { "@{push}" };
 451         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 452 }
 453
 454 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 455 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 456
 457 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 458                           unsigned int flags)
 459 {
 460         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 461         static const char *object_name_msg = N_(
 462         "Git normally never creates a ref that ends with 40 hex characters\n"
 463         "because it will be ignored when you just specify 40-hex. These refs\n"
 464         "may be created by mistake. For example,\n"
 465         "\n"
 466         "  git checkout -b $br $(git rev-parse ...)\n"
 467         "\n"
 468         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 469         "examine these refs and maybe delete them. Turn this message off by\n"
 470         "running \"git config advice.objectNameWarning false\"");
 471         unsigned char tmp_sha1[20];
 472         char *real_ref = NULL;
 473         int refs_found = 0;
 474         int at, reflog_len, nth_prior = 0;
 475
 476         if (len == 40 && !get_sha1_hex(str, sha1)) {
 477                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 478                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 479                         if (refs_found > 0) {
 480                                 warning(warn_msg, len, str);
 481                                 if (advice_object_name_warning)
 482                                         fprintf(stderr, "%s\n", _(object_name_msg));
 483                         }
 484                         free(real_ref);
 485                 }
 486                 return 0;
 487         }
 488
 489         /* basic@{time or number or -number} format to query ref-log */
 490         reflog_len = at = 0;
 491         if (len && str[len-1] == '}') {
 492                 for (at = len-4; at >= 0; at--) {
 493                         if (str[at] == '@' && str[at+1] == '{') {
 494                                 if (str[at+2] == '-') {
 495                                         if (at != 0)
 496                                                 /* @{-N} not at start */
 497                                                 return -1;
 498                                         nth_prior = 1;
 499                                         continue;
 500                                 }
 501                                 if (!upstream_mark(str + at, len - at) &&
 502                                     !push_mark(str + at, len - at)) {
 503                                         reflog_len = (len-1) - (at+2);
 504                                         len = at;
 505                                 }
 506                                 break;
 507                         }
 508                 }
 509         }
 510
 511         /* Accept only unambiguous ref paths. */
 512         if (len && ambiguous_path(str, len))
 513                 return -1;
 514
 515         if (nth_prior) {
 516                 struct strbuf buf = STRBUF_INIT;
 517                 int detached;
 518
 519                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 520                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 521                         strbuf_release(&buf);
 522                         if (detached)
 523                                 return 0;
 524                 }
 525         }
 526
 527         if (!len && reflog_len)
 528                 /* allow "@{...}" to mean the current branch reflog */
 529                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 530         else if (reflog_len)
 531                 refs_found = dwim_log(str, len, sha1, &real_ref);
 532         else
 533                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 534
 535         if (!refs_found)
 536                 return -1;
 537
 538         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 539             (refs_found > 1 ||
 540              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 541                 warning(warn_msg, len, str);
 542
 543         if (reflog_len) {
 544                 int nth, i;
 545                 unsigned long at_time;
 546                 unsigned long co_time;
 547                 int co_tz, co_cnt;
 548
 549                 /* Is it asking for N-th entry, or approxidate? */
 550                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 551                         char ch = str[at+2+i];
 552                         if ('0' <= ch && ch <= '9')
 553                                 nth = nth * 10 + ch - '0';
 554                         else
 555                                 nth = -1;
 556                 }
 557                 if (100000000 <= nth) {
 558                         at_time = nth;
 559                         nth = -1;
 560                 } else if (0 <= nth)
 561                         at_time = 0;
 562                 else {
 563                         int errors = 0;
 564                         char *tmp = xstrndup(str + at + 2, reflog_len);
 565                         at_time = approxidate_careful(tmp, &errors);
 566                         free(tmp);
 567                         if (errors) {
 568                                 free(real_ref);
 569                                 return -1;
 570                         }
 571                 }
 572                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 573                                 &co_time, &co_tz, &co_cnt)) {
 574                         if (!len) {
 575                                 if (starts_with(real_ref, "refs/heads/")) {
 576                                         str = real_ref + 11;
 577                                         len = strlen(real_ref + 11);
 578                                 } else {
 579                                         /* detached HEAD */
 580                                         str = "HEAD";
 581                                         len = 4;
 582                                 }
 583                         }
 584                         if (at_time) {
 585                                 if (!(flags & GET_SHA1_QUIETLY)) {
 586                                         warning("Log for '%.*s' only goes "
 587                                                 "back to %s.", len, str,
 588                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 589                                 }
 590                         } else {
 591                                 if (flags & GET_SHA1_QUIETLY) {
 592                                         exit(128);
 593                                 }
 594                                 die("Log for '%.*s' only has %d entries.",
 595                                     len, str, co_cnt);
 596                         }
 597                 }
 598         }
 599
 600         free(real_ref);
 601         return 0;
 602 }
 603
 604 static int get_parent(const char *name, int len,
 605                       unsigned char *result, int idx)
 606 {
 607         unsigned char sha1[20];
 608         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 609         struct commit *commit;
 610         struct commit_list *p;
 611
 612         if (ret)
 613                 return ret;
 614         commit = lookup_commit_reference(sha1);
 615         if (parse_commit(commit))
 616                 return -1;
 617         if (!idx) {
 618                 hashcpy(result, commit->object.oid.hash);
 619                 return 0;
 620         }
 621         p = commit->parents;
 622         while (p) {
 623                 if (!--idx) {
 624                         hashcpy(result, p->item->object.oid.hash);
 625                         return 0;
 626                 }
 627                 p = p->next;
 628         }
 629         return -1;
 630 }
 631
 632 static int get_nth_ancestor(const char *name, int len,
 633                             unsigned char *result, int generation)
 634 {
 635         unsigned char sha1[20];
 636         struct commit *commit;
 637         int ret;
 638
 639         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 640         if (ret)
 641                 return ret;
 642         commit = lookup_commit_reference(sha1);
 643         if (!commit)
 644                 return -1;
 645
 646         while (generation--) {
 647                 if (parse_commit(commit) || !commit->parents)
 648                         return -1;
 649                 commit = commit->parents->item;
 650         }
 651         hashcpy(result, commit->object.oid.hash);
 652         return 0;
 653 }
 654
 655 struct object *peel_to_type(const char *name, int namelen,
 656                             struct object *o, enum object_type expected_type)
 657 {
 658         if (name && !namelen)
 659                 namelen = strlen(name);
 660         while (1) {
 661                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 662                         return NULL;
 663                 if (expected_type == OBJ_ANY || o->type == expected_type)
 664                         return o;
 665                 if (o->type == OBJ_TAG)
 666                         o = ((struct tag*) o)->tagged;
 667                 else if (o->type == OBJ_COMMIT)
 668                         o = &(((struct commit *) o)->tree->object);
 669                 else {
 670                         if (name)
 671                                 error("%.*s: expected %s type, but the object "
 672                                       "dereferences to %s type",
 673                                       namelen, name, typename(expected_type),
 674                                       typename(o->type));
 675                         return NULL;
 676                 }
 677         }
 678 }
 679
 680 static int peel_onion(const char *name, int len, unsigned char *sha1)
 681 {
 682         unsigned char outer[20];
 683         const char *sp;
 684         unsigned int expected_type = 0;
 685         unsigned lookup_flags = 0;
 686         struct object *o;
 687
 688         /*
 689          * "ref^{type}" dereferences ref repeatedly until you cannot
 690          * dereference anymore, or you get an object of given type,
 691          * whichever comes first.  "ref^{}" means just dereference
 692          * tags until you get a non-tag.  "ref^0" is a shorthand for
 693          * "ref^{commit}".  "commit^{tree}" could be used to find the
 694          * top-level tree of the given commit.
 695          */
 696         if (len < 4 || name[len-1] != '}')
 697                 return -1;
 698
 699         for (sp = name + len - 1; name <= sp; sp--) {
 700                 int ch = *sp;
 701                 if (ch == '{' && name < sp && sp[-1] == '^')
 702                         break;
 703         }
 704         if (sp <= name)
 705                 return -1;
 706
 707         sp++; /* beginning of type name, or closing brace for empty */
 708         if (starts_with(sp, "commit}"))
 709                 expected_type = OBJ_COMMIT;
 710         else if (starts_with(sp, "tag}"))
 711                 expected_type = OBJ_TAG;
 712         else if (starts_with(sp, "tree}"))
 713                 expected_type = OBJ_TREE;
 714         else if (starts_with(sp, "blob}"))
 715                 expected_type = OBJ_BLOB;
 716         else if (starts_with(sp, "object}"))
 717                 expected_type = OBJ_ANY;
 718         else if (sp[0] == '}')
 719                 expected_type = OBJ_NONE;
 720         else if (sp[0] == '/')
 721                 expected_type = OBJ_COMMIT;
 722         else
 723                 return -1;
 724
 725         if (expected_type == OBJ_COMMIT)
 726                 lookup_flags = GET_SHA1_COMMITTISH;
 727         else if (expected_type == OBJ_TREE)
 728                 lookup_flags = GET_SHA1_TREEISH;
 729
 730         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 731                 return -1;
 732
 733         o = parse_object(outer);
 734         if (!o)
 735                 return -1;
 736         if (!expected_type) {
 737                 o = deref_tag(o, name, sp - name - 2);
 738                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 739                         return -1;
 740                 hashcpy(sha1, o->oid.hash);
 741                 return 0;
 742         }
 743
 744         /*
 745          * At this point, the syntax look correct, so
 746          * if we do not get the needed object, we should
 747          * barf.
 748          */
 749         o = peel_to_type(name, len, o, expected_type);
 750         if (!o)
 751                 return -1;
 752
 753         hashcpy(sha1, o->oid.hash);
 754         if (sp[0] == '/') {
 755                 /* "$commit^{/foo}" */
 756                 char *prefix;
 757                 int ret;
 758                 struct commit_list *list = NULL;
 759
 760                 /*
 761                  * $commit^{/}. Some regex implementation may reject.
 762                  * We don't need regex anyway. '' pattern always matches.
 763                  */
 764                 if (sp[1] == '}')
 765                         return 0;
 766
 767                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 768                 commit_list_insert((struct commit *)o, &list);
 769                 ret = get_sha1_oneline(prefix, sha1, list);
 770                 free(prefix);
 771                 return ret;
 772         }
 773         return 0;
 774 }
 775
 776 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 777 {
 778         const char *cp;
 779         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 780
 781         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 782                 char ch = *cp;
 783                 if (!isxdigit(ch)) {
 784                         /* We must be looking at g in "SOMETHING-g"
 785                          * for it to be describe output.
 786                          */
 787                         if (ch == 'g' && cp[-1] == '-') {
 788                                 cp++;
 789                                 len -= cp - name;
 790                                 return get_short_sha1(cp, len, sha1, flags);
 791                         }
 792                 }
 793         }
 794         return -1;
 795 }
 796
 797 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 798 {
 799         int ret, has_suffix;
 800         const char *cp;
 801
 802         /*
 803          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 804          */
 805         has_suffix = 0;
 806         for (cp = name + len - 1; name <= cp; cp--) {
 807                 int ch = *cp;
 808                 if ('0' <= ch && ch <= '9')
 809                         continue;
 810                 if (ch == '~' || ch == '^')
 811                         has_suffix = ch;
 812                 break;
 813         }
 814
 815         if (has_suffix) {
 816                 int num = 0;
 817                 int len1 = cp - name;
 818                 cp++;
 819                 while (cp < name + len)
 820                         num = num * 10 + *cp++ - '0';
 821                 if (!num && len1 == len - 1)
 822                         num = 1;
 823                 if (has_suffix == '^')
 824                         return get_parent(name, len1, sha1, num);
 825                 /* else if (has_suffix == '~') -- goes without saying */
 826                 return get_nth_ancestor(name, len1, sha1, num);
 827         }
 828
 829         ret = peel_onion(name, len, sha1);
 830         if (!ret)
 831                 return 0;
 832
 833         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 834         if (!ret)
 835                 return 0;
 836
 837         /* It could be describe output that is "SOMETHING-gXXXX" */
 838         ret = get_describe_name(name, len, sha1);
 839         if (!ret)
 840                 return 0;
 841
 842         return get_short_sha1(name, len, sha1, lookup_flags);
 843 }
 844
 845 /*
 846  * This interprets names like ':/Initial revision of "git"' by searching
 847  * through history and returning the first commit whose message starts
 848  * the given regular expression.
 849  *
 850  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 851  *
 852  * For a literal '!' character at the beginning of a pattern, you have to repeat
 853  * that, like: ':/!!foo'
 854  *
 855  * For future extension, all other sequences beginning with ':/!' are reserved.
 856  */
 857
 858 /* Remember to update object flag allocation in object.h */
 859 #define ONELINE_SEEN (1u<<20)
 860
 861 static int handle_one_ref(const char *path, const struct object_id *oid,
 862                           int flag, void *cb_data)
 863 {
 864         struct commit_list **list = cb_data;
 865         struct object *object = parse_object(oid->hash);
 866         if (!object)
 867                 return 0;
 868         if (object->type == OBJ_TAG) {
 869                 object = deref_tag(object, path, strlen(path));
 870                 if (!object)
 871                         return 0;
 872         }
 873         if (object->type != OBJ_COMMIT)
 874                 return 0;
 875         commit_list_insert((struct commit *)object, list);
 876         return 0;
 877 }
 878
 879 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 880                             struct commit_list *list)
 881 {
 882         struct commit_list *backup = NULL, *l;
 883         int found = 0;
 884         int negative = 0;
 885         regex_t regex;
 886
 887         if (prefix[0] == '!') {
 888                 prefix++;
 889
 890                 if (prefix[0] == '-') {
 891                         prefix++;
 892                         negative = 1;
 893                 } else if (prefix[0] != '!') {
 894                         return -1;
 895                 }
 896         }
 897
 898         if (regcomp(&regex, prefix, REG_EXTENDED))
 899                 return -1;
 900
 901         for (l = list; l; l = l->next) {
 902                 l->item->object.flags |= ONELINE_SEEN;
 903                 commit_list_insert(l->item, &backup);
 904         }
 905         while (list) {
 906                 const char *p, *buf;
 907                 struct commit *commit;
 908                 int matches;
 909
 910                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 911                 if (!parse_object(commit->object.oid.hash))
 912                         continue;
 913                 buf = get_commit_buffer(commit, NULL);
 914                 p = strstr(buf, "\n\n");
 915                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
 916                 unuse_commit_buffer(commit, buf);
 917
 918                 if (matches) {
 919                         hashcpy(sha1, commit->object.oid.hash);
 920                         found = 1;
 921                         break;
 922                 }
 923         }
 924         regfree(&regex);
 925         free_commit_list(list);
 926         for (l = backup; l; l = l->next)
 927                 clear_commit_marks(l->item, ONELINE_SEEN);
 928         free_commit_list(backup);
 929         return found ? 0 : -1;
 930 }
 931
 932 struct grab_nth_branch_switch_cbdata {
 933         int remaining;
 934         struct strbuf buf;
 935 };
 936
 937 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 938                                   const char *email, unsigned long timestamp, int tz,
 939                                   const char *message, void *cb_data)
 940 {
 941         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 942         const char *match = NULL, *target = NULL;
 943         size_t len;
 944
 945         if (skip_prefix(message, "checkout: moving from ", &match))
 946                 target = strstr(match, " to ");
 947
 948         if (!match || !target)
 949                 return 0;
 950         if (--(cb->remaining) == 0) {
 951                 len = target - match;
 952                 strbuf_reset(&cb->buf);
 953                 strbuf_add(&cb->buf, match, len);
 954                 return 1; /* we are done */
 955         }
 956         return 0;
 957 }
 958
 959 /*
 960  * Parse @{-N} syntax, return the number of characters parsed
 961  * if successful; otherwise signal an error with negative value.
 962  */
 963 static int interpret_nth_prior_checkout(const char *name, int namelen,
 964                                         struct strbuf *buf)
 965 {
 966         long nth;
 967         int retval;
 968         struct grab_nth_branch_switch_cbdata cb;
 969         const char *brace;
 970         char *num_end;
 971
 972         if (namelen < 4)
 973                 return -1;
 974         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 975                 return -1;
 976         brace = memchr(name, '}', namelen);
 977         if (!brace)
 978                 return -1;
 979         nth = strtol(name + 3, &num_end, 10);
 980         if (num_end != brace)
 981                 return -1;
 982         if (nth <= 0)
 983                 return -1;
 984         cb.remaining = nth;
 985         strbuf_init(&cb.buf, 20);
 986
 987         retval = 0;
 988         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 989                 strbuf_reset(buf);
 990                 strbuf_addbuf(buf, &cb.buf);
 991                 retval = brace - name + 1;
 992         }
 993
 994         strbuf_release(&cb.buf);
 995         return retval;
 996 }
 997
 998 int get_sha1_mb(const char *name, unsigned char *sha1)
 999 {
1000         struct commit *one, *two;
1001         struct commit_list *mbs;
1002         unsigned char sha1_tmp[20];
1003         const char *dots;
1004         int st;
1005
1006         dots = strstr(name, "...");
1007         if (!dots)
1008                 return get_sha1(name, sha1);
1009         if (dots == name)
1010                 st = get_sha1("HEAD", sha1_tmp);
1011         else {
1012                 struct strbuf sb;
1013                 strbuf_init(&sb, dots - name);
1014                 strbuf_add(&sb, name, dots - name);
1015                 st = get_sha1_committish(sb.buf, sha1_tmp);
1016                 strbuf_release(&sb);
1017         }
1018         if (st)
1019                 return st;
1020         one = lookup_commit_reference_gently(sha1_tmp, 0);
1021         if (!one)
1022                 return -1;
1023
1024         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
1025                 return -1;
1026         two = lookup_commit_reference_gently(sha1_tmp, 0);
1027         if (!two)
1028                 return -1;
1029         mbs = get_merge_bases(one, two);
1030         if (!mbs || mbs->next)
1031                 st = -1;
1032         else {
1033                 st = 0;
1034                 hashcpy(sha1, mbs->item->object.oid.hash);
1035         }
1036         free_commit_list(mbs);
1037         return st;
1038 }
1039
1040 /* parse @something syntax, when 'something' is not {.*} */
1041 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1042 {
1043         const char *next;
1044
1045         if (len || name[1] == '{')
1046                 return -1;
1047
1048         /* make sure it's a single @, or @@{.*}, not @foo */
1049         next = memchr(name + len + 1, '@', namelen - len - 1);
1050         if (next && next[1] != '{')
1051                 return -1;
1052         if (!next)
1053                 next = name + namelen;
1054         if (next != name + 1)
1055                 return -1;
1056
1057         strbuf_reset(buf);
1058         strbuf_add(buf, "HEAD", 4);
1059         return 1;
1060 }
1061
1062 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1063 {
1064         /* we have extra data, which might need further processing */
1065         struct strbuf tmp = STRBUF_INIT;
1066         int used = buf->len;
1067         int ret;
1068
1069         strbuf_add(buf, name + len, namelen - len);
1070         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1071         /* that data was not interpreted, remove our cruft */
1072         if (ret < 0) {
1073                 strbuf_setlen(buf, used);
1074                 return len;
1075         }
1076         strbuf_reset(buf);
1077         strbuf_addbuf(buf, &tmp);
1078         strbuf_release(&tmp);
1079         /* tweak for size of {-N} versus expanded ref name */
1080         return ret - used + len;
1081 }
1082
1083 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1084 {
1085         char *s = shorten_unambiguous_ref(ref, 0);
1086         strbuf_reset(buf);
1087         strbuf_addstr(buf, s);
1088         free(s);
1089 }
1090
1091 static int interpret_branch_mark(const char *name, int namelen,
1092                                  int at, struct strbuf *buf,
1093                                  int (*get_mark)(const char *, int),
1094                                  const char *(*get_data)(struct branch *,
1095                                                          struct strbuf *))
1096 {
1097         int len;
1098         struct branch *branch;
1099         struct strbuf err = STRBUF_INIT;
1100         const char *value;
1101
1102         len = get_mark(name + at, namelen - at);
1103         if (!len)
1104                 return -1;
1105
1106         if (memchr(name, ':', at))
1107                 return -1;
1108
1109         if (at) {
1110                 char *name_str = xmemdupz(name, at);
1111                 branch = branch_get(name_str);
1112                 free(name_str);
1113         } else
1114                 branch = branch_get(NULL);
1115
1116         value = get_data(branch, &err);
1117         if (!value)
1118                 die("%s", err.buf);
1119
1120         set_shortened_ref(buf, value);
1121         return len + at;
1122 }
1123
1124 /*
1125  * This reads short-hand syntax that not only evaluates to a commit
1126  * object name, but also can act as if the end user spelled the name
1127  * of the branch from the command line.
1128  *
1129  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1130  *   places the name of the branch in the given buf and returns the
1131  *   number of characters parsed if successful.
1132  *
1133  * - "<branch>@{upstream}" finds the name of the other ref that
1134  *   <branch> is configured to merge with (missing <branch> defaults
1135  *   to the current branch), and places the name of the branch in the
1136  *   given buf and returns the number of characters parsed if
1137  *   successful.
1138  *
1139  * If the input is not of the accepted format, it returns a negative
1140  * number to signal an error.
1141  *
1142  * If the input was ok but there are not N branch switches in the
1143  * reflog, it returns 0.
1144  */
1145 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1146 {
1147         char *at;
1148         const char *start;
1149         int len = interpret_nth_prior_checkout(name, namelen, buf);
1150
1151         if (!namelen)
1152                 namelen = strlen(name);
1153
1154         if (!len) {
1155                 return len; /* syntax Ok, not enough switches */
1156         } else if (len > 0) {
1157                 if (len == namelen)
1158                         return len; /* consumed all */
1159                 else
1160                         return reinterpret(name, namelen, len, buf);
1161         }
1162
1163         for (start = name;
1164              (at = memchr(start, '@', namelen - (start - name)));
1165              start = at + 1) {
1166
1167                 len = interpret_empty_at(name, namelen, at - name, buf);
1168                 if (len > 0)
1169                         return reinterpret(name, namelen, len, buf);
1170
1171                 len = interpret_branch_mark(name, namelen, at - name, buf,
1172                                             upstream_mark, branch_get_upstream);
1173                 if (len > 0)
1174                         return len;
1175
1176                 len = interpret_branch_mark(name, namelen, at - name, buf,
1177                                             push_mark, branch_get_push);
1178                 if (len > 0)
1179                         return len;
1180         }
1181
1182         return -1;
1183 }
1184
1185 int strbuf_branchname(struct strbuf *sb, const char *name)
1186 {
1187         int len = strlen(name);
1188         int used = interpret_branch_name(name, len, sb);
1189
1190         if (used == len)
1191                 return 0;
1192         if (used < 0)
1193                 used = 0;
1194         strbuf_add(sb, name + used, len - used);
1195         return len;
1196 }
1197
1198 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1199 {
1200         strbuf_branchname(sb, name);
1201         if (name[0] == '-')
1202                 return -1;
1203         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1204         return check_refname_format(sb->buf, 0);
1205 }
1206
1207 /*
1208  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1209  * notably "xyz^" for "parent of xyz"
1210  */
1211 int get_sha1(const char *name, unsigned char *sha1)
1212 {
1213         struct object_context unused;
1214         return get_sha1_with_context(name, 0, sha1, &unused);
1215 }
1216
1217 /*
1218  * Many callers know that the user meant to name a commit-ish by
1219  * syntactical positions where the object name appears.  Calling this
1220  * function allows the machinery to disambiguate shorter-than-unique
1221  * abbreviated object names between commit-ish and others.
1222  *
1223  * Note that this does NOT error out when the named object is not a
1224  * commit-ish. It is merely to give a hint to the disambiguation
1225  * machinery.
1226  */
1227 int get_sha1_committish(const char *name, unsigned char *sha1)
1228 {
1229         struct object_context unused;
1230         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1231                                      sha1, &unused);
1232 }
1233
1234 int get_sha1_treeish(const char *name, unsigned char *sha1)
1235 {
1236         struct object_context unused;
1237         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1238                                      sha1, &unused);
1239 }
1240
1241 int get_sha1_commit(const char *name, unsigned char *sha1)
1242 {
1243         struct object_context unused;
1244         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1245                                      sha1, &unused);
1246 }
1247
1248 int get_sha1_tree(const char *name, unsigned char *sha1)
1249 {
1250         struct object_context unused;
1251         return get_sha1_with_context(name, GET_SHA1_TREE,
1252                                      sha1, &unused);
1253 }
1254
1255 int get_sha1_blob(const char *name, unsigned char *sha1)
1256 {
1257         struct object_context unused;
1258         return get_sha1_with_context(name, GET_SHA1_BLOB,
1259                                      sha1, &unused);
1260 }
1261
1262 /* Must be called only when object_name:filename doesn't exist. */
1263 static void diagnose_invalid_sha1_path(const char *prefix,
1264                                        const char *filename,
1265                                        const unsigned char *tree_sha1,
1266                                        const char *object_name,
1267                                        int object_name_len)
1268 {
1269         unsigned char sha1[20];
1270         unsigned mode;
1271
1272         if (!prefix)
1273                 prefix = "";
1274
1275         if (file_exists(filename))
1276                 die("Path '%s' exists on disk, but not in '%.*s'.",
1277                     filename, object_name_len, object_name);
1278         if (errno == ENOENT || errno == ENOTDIR) {
1279                 char *fullname = xstrfmt("%s%s", prefix, filename);
1280
1281                 if (!get_tree_entry(tree_sha1, fullname,
1282                                     sha1, &mode)) {
1283                         die("Path '%s' exists, but not '%s'.\n"
1284                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1285                             fullname,
1286                             filename,
1287                             object_name_len, object_name,
1288                             fullname,
1289                             object_name_len, object_name,
1290                             filename);
1291                 }
1292                 die("Path '%s' does not exist in '%.*s'",
1293                     filename, object_name_len, object_name);
1294         }
1295 }
1296
1297 /* Must be called only when :stage:filename doesn't exist. */
1298 static void diagnose_invalid_index_path(int stage,
1299                                         const char *prefix,
1300                                         const char *filename)
1301 {
1302         const struct cache_entry *ce;
1303         int pos;
1304         unsigned namelen = strlen(filename);
1305         struct strbuf fullname = STRBUF_INIT;
1306
1307         if (!prefix)
1308                 prefix = "";
1309
1310         /* Wrong stage number? */
1311         pos = cache_name_pos(filename, namelen);
1312         if (pos < 0)
1313                 pos = -pos - 1;
1314         if (pos < active_nr) {
1315                 ce = active_cache[pos];
1316                 if (ce_namelen(ce) == namelen &&
1317                     !memcmp(ce->name, filename, namelen))
1318                         die("Path '%s' is in the index, but not at stage %d.\n"
1319                             "Did you mean ':%d:%s'?",
1320                             filename, stage,
1321                             ce_stage(ce), filename);
1322         }
1323
1324         /* Confusion between relative and absolute filenames? */
1325         strbuf_addstr(&fullname, prefix);
1326         strbuf_addstr(&fullname, filename);
1327         pos = cache_name_pos(fullname.buf, fullname.len);
1328         if (pos < 0)
1329                 pos = -pos - 1;
1330         if (pos < active_nr) {
1331                 ce = active_cache[pos];
1332                 if (ce_namelen(ce) == fullname.len &&
1333                     !memcmp(ce->name, fullname.buf, fullname.len))
1334                         die("Path '%s' is in the index, but not '%s'.\n"
1335                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1336                             fullname.buf, filename,
1337                             ce_stage(ce), fullname.buf,
1338                             ce_stage(ce), filename);
1339         }
1340
1341         if (file_exists(filename))
1342                 die("Path '%s' exists on disk, but not in the index.", filename);
1343         if (errno == ENOENT || errno == ENOTDIR)
1344                 die("Path '%s' does not exist (neither on disk nor in the index).",
1345                     filename);
1346
1347         strbuf_release(&fullname);
1348 }
1349
1350
1351 static char *resolve_relative_path(const char *rel)
1352 {
1353         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1354                 return NULL;
1355
1356         if (!startup_info)
1357                 die("BUG: startup_info struct is not initialized.");
1358
1359         if (!is_inside_work_tree())
1360                 die("relative path syntax can't be used outside working tree.");
1361
1362         /* die() inside prefix_path() if resolved path is outside worktree */
1363         return prefix_path(startup_info->prefix,
1364                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1365                            rel);
1366 }
1367
1368 static int get_sha1_with_context_1(const char *name,
1369                                    unsigned flags,
1370                                    const char *prefix,
1371                                    unsigned char *sha1,
1372                                    struct object_context *oc)
1373 {
1374         int ret, bracket_depth;
1375         int namelen = strlen(name);
1376         const char *cp;
1377         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1378
1379         memset(oc, 0, sizeof(*oc));
1380         oc->mode = S_IFINVALID;
1381         ret = get_sha1_1(name, namelen, sha1, flags);
1382         if (!ret)
1383                 return ret;
1384         /*
1385          * sha1:path --> object name of path in ent sha1
1386          * :path -> object name of absolute path in index
1387          * :./path -> object name of path relative to cwd in index
1388          * :[0-3]:path -> object name of path in index at stage
1389          * :/foo -> recent commit matching foo
1390          */
1391         if (name[0] == ':') {
1392                 int stage = 0;
1393                 const struct cache_entry *ce;
1394                 char *new_path = NULL;
1395                 int pos;
1396                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1397                         struct commit_list *list = NULL;
1398
1399                         for_each_ref(handle_one_ref, &list);
1400                         commit_list_sort_by_date(&list);
1401                         return get_sha1_oneline(name + 2, sha1, list);
1402                 }
1403                 if (namelen < 3 ||
1404                     name[2] != ':' ||
1405                     name[1] < '0' || '3' < name[1])
1406                         cp = name + 1;
1407                 else {
1408                         stage = name[1] - '0';
1409                         cp = name + 3;
1410                 }
1411                 new_path = resolve_relative_path(cp);
1412                 if (!new_path) {
1413                         namelen = namelen - (cp - name);
1414                 } else {
1415                         cp = new_path;
1416                         namelen = strlen(cp);
1417                 }
1418
1419                 strlcpy(oc->path, cp, sizeof(oc->path));
1420
1421                 if (!active_cache)
1422                         read_cache();
1423                 pos = cache_name_pos(cp, namelen);
1424                 if (pos < 0)
1425                         pos = -pos - 1;
1426                 while (pos < active_nr) {
1427                         ce = active_cache[pos];
1428                         if (ce_namelen(ce) != namelen ||
1429                             memcmp(ce->name, cp, namelen))
1430                                 break;
1431                         if (ce_stage(ce) == stage) {
1432                                 hashcpy(sha1, ce->sha1);
1433                                 oc->mode = ce->ce_mode;
1434                                 free(new_path);
1435                                 return 0;
1436                         }
1437                         pos++;
1438                 }
1439                 if (only_to_die && name[1] && name[1] != '/')
1440                         diagnose_invalid_index_path(stage, prefix, cp);
1441                 free(new_path);
1442                 return -1;
1443         }
1444         for (cp = name, bracket_depth = 0; *cp; cp++) {
1445                 if (*cp == '{')
1446                         bracket_depth++;
1447                 else if (bracket_depth && *cp == '}')
1448                         bracket_depth--;
1449                 else if (!bracket_depth && *cp == ':')
1450                         break;
1451         }
1452         if (*cp == ':') {
1453                 unsigned char tree_sha1[20];
1454                 int len = cp - name;
1455                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1456                         const char *filename = cp+1;
1457                         char *new_filename = NULL;
1458
1459                         new_filename = resolve_relative_path(filename);
1460                         if (new_filename)
1461                                 filename = new_filename;
1462                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1463                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1464                                         filename, sha1, &oc->symlink_path,
1465                                         &oc->mode);
1466                         } else {
1467                                 ret = get_tree_entry(tree_sha1, filename,
1468                                                      sha1, &oc->mode);
1469                                 if (ret && only_to_die) {
1470                                         diagnose_invalid_sha1_path(prefix,
1471                                                                    filename,
1472                                                                    tree_sha1,
1473                                                                    name, len);
1474                                 }
1475                         }
1476                         hashcpy(oc->tree, tree_sha1);
1477                         strlcpy(oc->path, filename, sizeof(oc->path));
1478
1479                         free(new_filename);
1480                         return ret;
1481                 } else {
1482                         if (only_to_die)
1483                                 die("Invalid object name '%.*s'.", len, name);
1484                 }
1485         }
1486         return ret;
1487 }
1488
1489 /*
1490  * Call this function when you know "name" given by the end user must
1491  * name an object but it doesn't; the function _may_ die with a better
1492  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1493  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1494  * you have a chance to diagnose the error further.
1495  */
1496 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1497 {
1498         struct object_context oc;
1499         unsigned char sha1[20];
1500         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1501 }
1502
1503 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1504 {
1505         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1506                 die("BUG: incompatible flags for get_sha1_with_context");
1507         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1508 }