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                 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 inline int publish_mark(const char *string, int len)
 455 {
 456         const char *suffix[] = { "publish", "p" };
 457         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 458 }
 459
 460 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 461 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 462
 463 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 464                           unsigned int flags)
 465 {
 466         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 467         static const char *object_name_msg = N_(
 468         "Git normally never creates a ref that ends with 40 hex characters\n"
 469         "because it will be ignored when you just specify 40-hex. These refs\n"
 470         "may be created by mistake. For example,\n"
 471         "\n"
 472         "  git checkout -b $br $(git rev-parse ...)\n"
 473         "\n"
 474         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 475         "examine these refs and maybe delete them. Turn this message off by\n"
 476         "running \"git config advice.objectNameWarning false\"");
 477         unsigned char tmp_sha1[20];
 478         char *real_ref = NULL;
 479         int refs_found = 0;
 480         int at, reflog_len, nth_prior = 0;
 481
 482         if (len == 40 && !get_sha1_hex(str, sha1)) {
 483                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 484                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 485                         if (refs_found > 0) {
 486                                 warning(warn_msg, len, str);
 487                                 if (advice_object_name_warning)
 488                                         fprintf(stderr, "%s\n", _(object_name_msg));
 489                         }
 490                         free(real_ref);
 491                 }
 492                 return 0;
 493         }
 494
 495         /* basic@{time or number or -number} format to query ref-log */
 496         reflog_len = at = 0;
 497         if (len && str[len-1] == '}') {
 498                 for (at = len-4; at >= 0; at--) {
 499                         if (str[at] == '@' && str[at+1] == '{') {
 500                                 if (str[at+2] == '-') {
 501                                         if (at != 0)
 502                                                 /* @{-N} not at start */
 503                                                 return -1;
 504                                         nth_prior = 1;
 505                                         continue;
 506                                 }
 507                                 if (!upstream_mark(str + at + 2, len - at - 3) &&
 508                                     !push_mark(str + at + 2, len - at - 3) &&
 509                                     !publish_mark(str + at + 2, len - at - 3)) {
 510                                         reflog_len = (len-1) - (at+2);
 511                                         len = at;
 512                                 }
 513                                 break;
 514                         }
 515                 }
 516         }
 517
 518         /* Accept only unambiguous ref paths. */
 519         if (len && ambiguous_path(str, len))
 520                 return -1;
 521
 522         if (nth_prior) {
 523                 struct strbuf buf = STRBUF_INIT;
 524                 int detached;
 525
 526                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 527                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 528                         strbuf_release(&buf);
 529                         if (detached)
 530                                 return 0;
 531                 }
 532         }
 533
 534         if (!len && reflog_len)
 535                 /* allow "@{...}" to mean the current branch reflog */
 536                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 537         else if (reflog_len)
 538                 refs_found = dwim_log(str, len, sha1, &real_ref);
 539         else
 540                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 541
 542         if (!refs_found)
 543                 return -1;
 544
 545         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 546             (refs_found > 1 ||
 547              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 548                 warning(warn_msg, len, str);
 549
 550         if (reflog_len) {
 551                 int nth, i;
 552                 unsigned long at_time;
 553                 unsigned long co_time;
 554                 int co_tz, co_cnt;
 555
 556                 /* Is it asking for N-th entry, or approxidate? */
 557                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 558                         char ch = str[at+2+i];
 559                         if ('0' <= ch && ch <= '9')
 560                                 nth = nth * 10 + ch - '0';
 561                         else
 562                                 nth = -1;
 563                 }
 564                 if (100000000 <= nth) {
 565                         at_time = nth;
 566                         nth = -1;
 567                 } else if (0 <= nth)
 568                         at_time = 0;
 569                 else {
 570                         int errors = 0;
 571                         char *tmp = xstrndup(str + at + 2, reflog_len);
 572                         at_time = approxidate_careful(tmp, &errors);
 573                         free(tmp);
 574                         if (errors) {
 575                                 free(real_ref);
 576                                 return -1;
 577                         }
 578                 }
 579                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 580                                 &co_time, &co_tz, &co_cnt)) {
 581                         if (!len) {
 582                                 if (starts_with(real_ref, "refs/heads/")) {
 583                                         str = real_ref + 11;
 584                                         len = strlen(real_ref + 11);
 585                                 } else {
 586                                         /* detached HEAD */
 587                                         str = "HEAD";
 588                                         len = 4;
 589                                 }
 590                         }
 591                         if (at_time) {
 592                                 if (!(flags & GET_SHA1_QUIETLY)) {
 593                                         warning("Log for '%.*s' only goes "
 594                                                 "back to %s.", len, str,
 595                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 596                                 }
 597                         } else {
 598                                 if (flags & GET_SHA1_QUIETLY) {
 599                                         exit(128);
 600                                 }
 601                                 die("Log for '%.*s' only has %d entries.",
 602                                     len, str, co_cnt);
 603                         }
 604                 }
 605         }
 606
 607         free(real_ref);
 608         return 0;
 609 }
 610
 611 static int get_parent(const char *name, int len,
 612                       unsigned char *result, int idx)
 613 {
 614         unsigned char sha1[20];
 615         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 616         struct commit *commit;
 617         struct commit_list *p;
 618
 619         if (ret)
 620                 return ret;
 621         commit = lookup_commit_reference(sha1);
 622         if (parse_commit(commit))
 623                 return -1;
 624         if (!idx) {
 625                 hashcpy(result, commit->object.oid.hash);
 626                 return 0;
 627         }
 628         p = commit->parents;
 629         while (p) {
 630                 if (!--idx) {
 631                         hashcpy(result, p->item->object.oid.hash);
 632                         return 0;
 633                 }
 634                 p = p->next;
 635         }
 636         return -1;
 637 }
 638
 639 static int get_nth_ancestor(const char *name, int len,
 640                             unsigned char *result, int generation)
 641 {
 642         unsigned char sha1[20];
 643         struct commit *commit;
 644         int ret;
 645
 646         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 647         if (ret)
 648                 return ret;
 649         commit = lookup_commit_reference(sha1);
 650         if (!commit)
 651                 return -1;
 652
 653         while (generation--) {
 654                 if (parse_commit(commit) || !commit->parents)
 655                         return -1;
 656                 commit = commit->parents->item;
 657         }
 658         hashcpy(result, commit->object.oid.hash);
 659         return 0;
 660 }
 661
 662 struct object *peel_to_type(const char *name, int namelen,
 663                             struct object *o, enum object_type expected_type)
 664 {
 665         if (name && !namelen)
 666                 namelen = strlen(name);
 667         while (1) {
 668                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 669                         return NULL;
 670                 if (expected_type == OBJ_ANY || o->type == expected_type)
 671                         return o;
 672                 if (o->type == OBJ_TAG)
 673                         o = ((struct tag*) o)->tagged;
 674                 else if (o->type == OBJ_COMMIT)
 675                         o = &(((struct commit *) o)->tree->object);
 676                 else {
 677                         if (name)
 678                                 error("%.*s: expected %s type, but the object "
 679                                       "dereferences to %s type",
 680                                       namelen, name, typename(expected_type),
 681                                       typename(o->type));
 682                         return NULL;
 683                 }
 684         }
 685 }
 686
 687 static int peel_onion(const char *name, int len, unsigned char *sha1)
 688 {
 689         unsigned char outer[20];
 690         const char *sp;
 691         unsigned int expected_type = 0;
 692         unsigned lookup_flags = 0;
 693         struct object *o;
 694
 695         /*
 696          * "ref^{type}" dereferences ref repeatedly until you cannot
 697          * dereference anymore, or you get an object of given type,
 698          * whichever comes first.  "ref^{}" means just dereference
 699          * tags until you get a non-tag.  "ref^0" is a shorthand for
 700          * "ref^{commit}".  "commit^{tree}" could be used to find the
 701          * top-level tree of the given commit.
 702          */
 703         if (len < 4 || name[len-1] != '}')
 704                 return -1;
 705
 706         for (sp = name + len - 1; name <= sp; sp--) {
 707                 int ch = *sp;
 708                 if (ch == '{' && name < sp && sp[-1] == '^')
 709                         break;
 710         }
 711         if (sp <= name)
 712                 return -1;
 713
 714         sp++; /* beginning of type name, or closing brace for empty */
 715         if (starts_with(sp, "commit}"))
 716                 expected_type = OBJ_COMMIT;
 717         else if (starts_with(sp, "tag}"))
 718                 expected_type = OBJ_TAG;
 719         else if (starts_with(sp, "tree}"))
 720                 expected_type = OBJ_TREE;
 721         else if (starts_with(sp, "blob}"))
 722                 expected_type = OBJ_BLOB;
 723         else if (starts_with(sp, "object}"))
 724                 expected_type = OBJ_ANY;
 725         else if (sp[0] == '}')
 726                 expected_type = OBJ_NONE;
 727         else if (sp[0] == '/')
 728                 expected_type = OBJ_COMMIT;
 729         else
 730                 return -1;
 731
 732         if (expected_type == OBJ_COMMIT)
 733                 lookup_flags = GET_SHA1_COMMITTISH;
 734         else if (expected_type == OBJ_TREE)
 735                 lookup_flags = GET_SHA1_TREEISH;
 736
 737         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 738                 return -1;
 739
 740         o = parse_object(outer);
 741         if (!o)
 742                 return -1;
 743         if (!expected_type) {
 744                 o = deref_tag(o, name, sp - name - 2);
 745                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 746                         return -1;
 747                 hashcpy(sha1, o->oid.hash);
 748                 return 0;
 749         }
 750
 751         /*
 752          * At this point, the syntax look correct, so
 753          * if we do not get the needed object, we should
 754          * barf.
 755          */
 756         o = peel_to_type(name, len, o, expected_type);
 757         if (!o)
 758                 return -1;
 759
 760         hashcpy(sha1, o->oid.hash);
 761         if (sp[0] == '/') {
 762                 /* "$commit^{/foo}" */
 763                 char *prefix;
 764                 int ret;
 765                 struct commit_list *list = NULL;
 766
 767                 /*
 768                  * $commit^{/}. Some regex implementation may reject.
 769                  * We don't need regex anyway. '' pattern always matches.
 770                  */
 771                 if (sp[1] == '}')
 772                         return 0;
 773
 774                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 775                 commit_list_insert((struct commit *)o, &list);
 776                 ret = get_sha1_oneline(prefix, sha1, list);
 777                 free(prefix);
 778                 return ret;
 779         }
 780         return 0;
 781 }
 782
 783 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 784 {
 785         const char *cp;
 786         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 787
 788         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 789                 char ch = *cp;
 790                 if (!isxdigit(ch)) {
 791                         /* We must be looking at g in "SOMETHING-g"
 792                          * for it to be describe output.
 793                          */
 794                         if (ch == 'g' && cp[-1] == '-') {
 795                                 cp++;
 796                                 len -= cp - name;
 797                                 return get_short_sha1(cp, len, sha1, flags);
 798                         }
 799                 }
 800         }
 801         return -1;
 802 }
 803
 804 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 805 {
 806         int ret, has_suffix;
 807         const char *cp;
 808
 809         /*
 810          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 811          */
 812         has_suffix = 0;
 813         for (cp = name + len - 1; name <= cp; cp--) {
 814                 int ch = *cp;
 815                 if ('0' <= ch && ch <= '9')
 816                         continue;
 817                 if (ch == '~' || ch == '^')
 818                         has_suffix = ch;
 819                 break;
 820         }
 821
 822         if (has_suffix) {
 823                 int num = 0;
 824                 int len1 = cp - name;
 825                 cp++;
 826                 while (cp < name + len)
 827                         num = num * 10 + *cp++ - '0';
 828                 if (!num && len1 == len - 1)
 829                         num = 1;
 830                 if (has_suffix == '^')
 831                         return get_parent(name, len1, sha1, num);
 832                 /* else if (has_suffix == '~') -- goes without saying */
 833                 return get_nth_ancestor(name, len1, sha1, num);
 834         }
 835
 836         ret = peel_onion(name, len, sha1);
 837         if (!ret)
 838                 return 0;
 839
 840         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 841         if (!ret)
 842                 return 0;
 843
 844         /* It could be describe output that is "SOMETHING-gXXXX" */
 845         ret = get_describe_name(name, len, sha1);
 846         if (!ret)
 847                 return 0;
 848
 849         return get_short_sha1(name, len, sha1, lookup_flags);
 850 }
 851
 852 /*
 853  * This interprets names like ':/Initial revision of "git"' by searching
 854  * through history and returning the first commit whose message starts
 855  * the given regular expression.
 856  *
 857  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 858  *
 859  * For a literal '!' character at the beginning of a pattern, you have to repeat
 860  * that, like: ':/!!foo'
 861  *
 862  * For future extension, all other sequences beginning with ':/!' are reserved.
 863  */
 864
 865 /* Remember to update object flag allocation in object.h */
 866 #define ONELINE_SEEN (1u<<20)
 867
 868 static int handle_one_ref(const char *path, const struct object_id *oid,
 869                           int flag, void *cb_data)
 870 {
 871         struct commit_list **list = cb_data;
 872         struct object *object = parse_object(oid->hash);
 873         if (!object)
 874                 return 0;
 875         if (object->type == OBJ_TAG) {
 876                 object = deref_tag(object, path, strlen(path));
 877                 if (!object)
 878                         return 0;
 879         }
 880         if (object->type != OBJ_COMMIT)
 881                 return 0;
 882         commit_list_insert((struct commit *)object, list);
 883         return 0;
 884 }
 885
 886 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 887                             struct commit_list *list)
 888 {
 889         struct commit_list *backup = NULL, *l;
 890         int found = 0;
 891         int negative = 0;
 892         regex_t regex;
 893
 894         if (prefix[0] == '!') {
 895                 prefix++;
 896
 897                 if (prefix[0] == '-') {
 898                         prefix++;
 899                         negative = 1;
 900                 } else if (prefix[0] != '!') {
 901                         return -1;
 902                 }
 903         }
 904
 905         if (regcomp(&regex, prefix, REG_EXTENDED))
 906                 return -1;
 907
 908         for (l = list; l; l = l->next) {
 909                 l->item->object.flags |= ONELINE_SEEN;
 910                 commit_list_insert(l->item, &backup);
 911         }
 912         while (list) {
 913                 const char *p, *buf;
 914                 struct commit *commit;
 915                 int matches;
 916
 917                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 918                 if (!parse_object(commit->object.oid.hash))
 919                         continue;
 920                 buf = get_commit_buffer(commit, NULL);
 921                 p = strstr(buf, "\n\n");
 922                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
 923                 unuse_commit_buffer(commit, buf);
 924
 925                 if (matches) {
 926                         hashcpy(sha1, commit->object.oid.hash);
 927                         found = 1;
 928                         break;
 929                 }
 930         }
 931         regfree(&regex);
 932         free_commit_list(list);
 933         for (l = backup; l; l = l->next)
 934                 clear_commit_marks(l->item, ONELINE_SEEN);
 935         free_commit_list(backup);
 936         return found ? 0 : -1;
 937 }
 938
 939 struct grab_nth_branch_switch_cbdata {
 940         int remaining;
 941         struct strbuf buf;
 942 };
 943
 944 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 945                                   const char *email, unsigned long timestamp, int tz,
 946                                   const char *message, void *cb_data)
 947 {
 948         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 949         const char *match = NULL, *target = NULL;
 950         size_t len;
 951
 952         if (skip_prefix(message, "checkout: moving from ", &match))
 953                 target = strstr(match, " to ");
 954
 955         if (!match || !target)
 956                 return 0;
 957         if (--(cb->remaining) == 0) {
 958                 len = target - match;
 959                 strbuf_reset(&cb->buf);
 960                 strbuf_add(&cb->buf, match, len);
 961                 return 1; /* we are done */
 962         }
 963         return 0;
 964 }
 965
 966 /*
 967  * Parse @{-N} syntax, return the number of characters parsed
 968  * if successful; otherwise signal an error with negative value.
 969  */
 970 static int interpret_nth_prior_checkout(const char *name, int namelen,
 971                                         struct strbuf *buf)
 972 {
 973         long nth;
 974         int retval;
 975         struct grab_nth_branch_switch_cbdata cb;
 976         const char *brace;
 977         char *num_end;
 978
 979         if (namelen < 4)
 980                 return -1;
 981         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 982                 return -1;
 983         brace = memchr(name, '}', namelen);
 984         if (!brace)
 985                 return -1;
 986         nth = strtol(name + 3, &num_end, 10);
 987         if (num_end != brace)
 988                 return -1;
 989         if (nth <= 0)
 990                 return -1;
 991         cb.remaining = nth;
 992         strbuf_init(&cb.buf, 20);
 993
 994         retval = 0;
 995         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 996                 strbuf_reset(buf);
 997                 strbuf_addbuf(buf, &cb.buf);
 998                 retval = brace - name + 1;
 999         }
1000
1001         strbuf_release(&cb.buf);
1002         return retval;
1003 }
1004
1005 int get_sha1_mb(const char *name, unsigned char *sha1)
1006 {
1007         struct commit *one, *two;
1008         struct commit_list *mbs;
1009         unsigned char sha1_tmp[20];
1010         const char *dots;
1011         int st;
1012
1013         dots = strstr(name, "...");
1014         if (!dots)
1015                 return get_sha1(name, sha1);
1016         if (dots == name)
1017                 st = get_sha1("HEAD", sha1_tmp);
1018         else {
1019                 struct strbuf sb;
1020                 strbuf_init(&sb, dots - name);
1021                 strbuf_add(&sb, name, dots - name);
1022                 st = get_sha1_committish(sb.buf, sha1_tmp);
1023                 strbuf_release(&sb);
1024         }
1025         if (st)
1026                 return st;
1027         one = lookup_commit_reference_gently(sha1_tmp, 0);
1028         if (!one)
1029                 return -1;
1030
1031         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
1032                 return -1;
1033         two = lookup_commit_reference_gently(sha1_tmp, 0);
1034         if (!two)
1035                 return -1;
1036         mbs = get_merge_bases(one, two);
1037         if (!mbs || mbs->next)
1038                 st = -1;
1039         else {
1040                 st = 0;
1041                 hashcpy(sha1, mbs->item->object.oid.hash);
1042         }
1043         free_commit_list(mbs);
1044         return st;
1045 }
1046
1047 /* parse @something syntax, when 'something' is not {.*} */
1048 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1049 {
1050         const char *next;
1051
1052         if (len || name[1] == '{')
1053                 return -1;
1054
1055         /* make sure it's a single @, or @@{.*}, not @foo */
1056         next = memchr(name + len + 1, '@', namelen - len - 1);
1057         if (next && next[1] != '{')
1058                 return -1;
1059         if (!next)
1060                 next = name + namelen;
1061         if (next != name + 1)
1062                 return -1;
1063
1064         strbuf_reset(buf);
1065         strbuf_add(buf, "HEAD", 4);
1066         return 1;
1067 }
1068
1069 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1070 {
1071         /* we have extra data, which might need further processing */
1072         struct strbuf tmp = STRBUF_INIT;
1073         int used = buf->len;
1074         int ret;
1075
1076         strbuf_add(buf, name + len, namelen - len);
1077         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1078         /* that data was not interpreted, remove our cruft */
1079         if (ret < 0) {
1080                 strbuf_setlen(buf, used);
1081                 return len;
1082         }
1083         strbuf_reset(buf);
1084         strbuf_addbuf(buf, &tmp);
1085         strbuf_release(&tmp);
1086         /* tweak for size of {-N} versus expanded ref name */
1087         return ret - used + len;
1088 }
1089
1090 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1091 {
1092         char *s = shorten_unambiguous_ref(ref, 0);
1093         strbuf_reset(buf);
1094         strbuf_addstr(buf, s);
1095         free(s);
1096 }
1097
1098 static int interpret_branch_mark(const char *name, int namelen,
1099                                  int at, struct strbuf *buf,
1100                                  int (*get_mark)(const char *, int),
1101                                  const char *(*get_data)(struct branch *,
1102                                                          struct strbuf *))
1103 {
1104         int len;
1105         struct branch *branch;
1106         struct strbuf err = STRBUF_INIT;
1107         const char *value;
1108
1109         if (name[at + 1] != '{' || name[namelen - 1] != '}')
1110                 return -1;
1111
1112         len = get_mark(name + at + 2, namelen - at - 3);
1113         if (!len)
1114                 return -1;
1115
1116         if (memchr(name, ':', at))
1117                 return -1;
1118
1119         if (at) {
1120                 char *name_str = xmemdupz(name, at);
1121                 branch = branch_get(name_str);
1122                 free(name_str);
1123         } else
1124                 branch = branch_get(NULL);
1125
1126         value = get_data(branch, &err);
1127         if (!value)
1128                 die("%s", err.buf);
1129
1130         set_shortened_ref(buf, value);
1131         return len + at + 3;
1132 }
1133
1134 /*
1135  * This reads short-hand syntax that not only evaluates to a commit
1136  * object name, but also can act as if the end user spelled the name
1137  * of the branch from the command line.
1138  *
1139  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1140  *   places the name of the branch in the given buf and returns the
1141  *   number of characters parsed if successful.
1142  *
1143  * - "<branch>@{upstream}" finds the name of the other ref that
1144  *   <branch> is configured to merge with (missing <branch> defaults
1145  *   to the current branch), and places the name of the branch in the
1146  *   given buf and returns the number of characters parsed if
1147  *   successful.
1148  *
1149  * If the input is not of the accepted format, it returns a negative
1150  * number to signal an error.
1151  *
1152  * If the input was ok but there are not N branch switches in the
1153  * reflog, it returns 0.
1154  */
1155 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1156 {
1157         char *at;
1158         const char *start;
1159         int len = interpret_nth_prior_checkout(name, namelen, buf);
1160
1161         if (!namelen)
1162                 namelen = strlen(name);
1163
1164         if (!len) {
1165                 return len; /* syntax Ok, not enough switches */
1166         } else if (len > 0) {
1167                 if (len == namelen)
1168                         return len; /* consumed all */
1169                 else
1170                         return reinterpret(name, namelen, len, buf);
1171         }
1172
1173         for (start = name;
1174              (at = memchr(start, '@', namelen - (start - name)));
1175              start = at + 1) {
1176
1177                 len = interpret_empty_at(name, namelen, at - name, buf);
1178                 if (len > 0)
1179                         return reinterpret(name, namelen, len, buf);
1180
1181                 len = interpret_branch_mark(name, namelen, at - name, buf,
1182                                             upstream_mark, branch_get_upstream);
1183                 if (len > 0)
1184                         return len;
1185
1186                 len = interpret_branch_mark(name, namelen, at - name, buf,
1187                                             push_mark, branch_get_push);
1188                 if (len > 0)
1189                         return len;
1190
1191                 len = interpret_branch_mark(name, namelen, at - name, buf,
1192                                             publish_mark, branch_get_publish);
1193                 if (len > 0)
1194                         return len;
1195         }
1196
1197         return -1;
1198 }
1199
1200 int strbuf_branchname(struct strbuf *sb, const char *name)
1201 {
1202         int len = strlen(name);
1203         int used = interpret_branch_name(name, len, sb);
1204
1205         if (used == len)
1206                 return 0;
1207         if (used < 0)
1208                 used = 0;
1209         strbuf_add(sb, name + used, len - used);
1210         return len;
1211 }
1212
1213 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1214 {
1215         strbuf_branchname(sb, name);
1216         if (name[0] == '-')
1217                 return -1;
1218         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1219         return check_refname_format(sb->buf, 0);
1220 }
1221
1222 /*
1223  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1224  * notably "xyz^" for "parent of xyz"
1225  */
1226 int get_sha1(const char *name, unsigned char *sha1)
1227 {
1228         struct object_context unused;
1229         return get_sha1_with_context(name, 0, sha1, &unused);
1230 }
1231
1232 /*
1233  * Many callers know that the user meant to name a commit-ish by
1234  * syntactical positions where the object name appears.  Calling this
1235  * function allows the machinery to disambiguate shorter-than-unique
1236  * abbreviated object names between commit-ish and others.
1237  *
1238  * Note that this does NOT error out when the named object is not a
1239  * commit-ish. It is merely to give a hint to the disambiguation
1240  * machinery.
1241  */
1242 int get_sha1_committish(const char *name, unsigned char *sha1)
1243 {
1244         struct object_context unused;
1245         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1246                                      sha1, &unused);
1247 }
1248
1249 int get_sha1_treeish(const char *name, unsigned char *sha1)
1250 {
1251         struct object_context unused;
1252         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1253                                      sha1, &unused);
1254 }
1255
1256 int get_sha1_commit(const char *name, unsigned char *sha1)
1257 {
1258         struct object_context unused;
1259         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1260                                      sha1, &unused);
1261 }
1262
1263 int get_sha1_tree(const char *name, unsigned char *sha1)
1264 {
1265         struct object_context unused;
1266         return get_sha1_with_context(name, GET_SHA1_TREE,
1267                                      sha1, &unused);
1268 }
1269
1270 int get_sha1_blob(const char *name, unsigned char *sha1)
1271 {
1272         struct object_context unused;
1273         return get_sha1_with_context(name, GET_SHA1_BLOB,
1274                                      sha1, &unused);
1275 }
1276
1277 /* Must be called only when object_name:filename doesn't exist. */
1278 static void diagnose_invalid_sha1_path(const char *prefix,
1279                                        const char *filename,
1280                                        const unsigned char *tree_sha1,
1281                                        const char *object_name,
1282                                        int object_name_len)
1283 {
1284         unsigned char sha1[20];
1285         unsigned mode;
1286
1287         if (!prefix)
1288                 prefix = "";
1289
1290         if (file_exists(filename))
1291                 die("Path '%s' exists on disk, but not in '%.*s'.",
1292                     filename, object_name_len, object_name);
1293         if (errno == ENOENT || errno == ENOTDIR) {
1294                 char *fullname = xstrfmt("%s%s", prefix, filename);
1295
1296                 if (!get_tree_entry(tree_sha1, fullname,
1297                                     sha1, &mode)) {
1298                         die("Path '%s' exists, but not '%s'.\n"
1299                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1300                             fullname,
1301                             filename,
1302                             object_name_len, object_name,
1303                             fullname,
1304                             object_name_len, object_name,
1305                             filename);
1306                 }
1307                 die("Path '%s' does not exist in '%.*s'",
1308                     filename, object_name_len, object_name);
1309         }
1310 }
1311
1312 /* Must be called only when :stage:filename doesn't exist. */
1313 static void diagnose_invalid_index_path(int stage,
1314                                         const char *prefix,
1315                                         const char *filename)
1316 {
1317         const struct cache_entry *ce;
1318         int pos;
1319         unsigned namelen = strlen(filename);
1320         struct strbuf fullname = STRBUF_INIT;
1321
1322         if (!prefix)
1323                 prefix = "";
1324
1325         /* Wrong stage number? */
1326         pos = cache_name_pos(filename, namelen);
1327         if (pos < 0)
1328                 pos = -pos - 1;
1329         if (pos < active_nr) {
1330                 ce = active_cache[pos];
1331                 if (ce_namelen(ce) == namelen &&
1332                     !memcmp(ce->name, filename, namelen))
1333                         die("Path '%s' is in the index, but not at stage %d.\n"
1334                             "Did you mean ':%d:%s'?",
1335                             filename, stage,
1336                             ce_stage(ce), filename);
1337         }
1338
1339         /* Confusion between relative and absolute filenames? */
1340         strbuf_addstr(&fullname, prefix);
1341         strbuf_addstr(&fullname, filename);
1342         pos = cache_name_pos(fullname.buf, fullname.len);
1343         if (pos < 0)
1344                 pos = -pos - 1;
1345         if (pos < active_nr) {
1346                 ce = active_cache[pos];
1347                 if (ce_namelen(ce) == fullname.len &&
1348                     !memcmp(ce->name, fullname.buf, fullname.len))
1349                         die("Path '%s' is in the index, but not '%s'.\n"
1350                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1351                             fullname.buf, filename,
1352                             ce_stage(ce), fullname.buf,
1353                             ce_stage(ce), filename);
1354         }
1355
1356         if (file_exists(filename))
1357                 die("Path '%s' exists on disk, but not in the index.", filename);
1358         if (errno == ENOENT || errno == ENOTDIR)
1359                 die("Path '%s' does not exist (neither on disk nor in the index).",
1360                     filename);
1361
1362         strbuf_release(&fullname);
1363 }
1364
1365
1366 static char *resolve_relative_path(const char *rel)
1367 {
1368         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1369                 return NULL;
1370
1371         if (!startup_info)
1372                 die("BUG: startup_info struct is not initialized.");
1373
1374         if (!is_inside_work_tree())
1375                 die("relative path syntax can't be used outside working tree.");
1376
1377         /* die() inside prefix_path() if resolved path is outside worktree */
1378         return prefix_path(startup_info->prefix,
1379                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1380                            rel);
1381 }
1382
1383 static int get_sha1_with_context_1(const char *name,
1384                                    unsigned flags,
1385                                    const char *prefix,
1386                                    unsigned char *sha1,
1387                                    struct object_context *oc)
1388 {
1389         int ret, bracket_depth;
1390         int namelen = strlen(name);
1391         const char *cp;
1392         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1393
1394         memset(oc, 0, sizeof(*oc));
1395         oc->mode = S_IFINVALID;
1396         ret = get_sha1_1(name, namelen, sha1, flags);
1397         if (!ret)
1398                 return ret;
1399         /*
1400          * sha1:path --> object name of path in ent sha1
1401          * :path -> object name of absolute path in index
1402          * :./path -> object name of path relative to cwd in index
1403          * :[0-3]:path -> object name of path in index at stage
1404          * :/foo -> recent commit matching foo
1405          */
1406         if (name[0] == ':') {
1407                 int stage = 0;
1408                 const struct cache_entry *ce;
1409                 char *new_path = NULL;
1410                 int pos;
1411                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1412                         struct commit_list *list = NULL;
1413
1414                         for_each_ref(handle_one_ref, &list);
1415                         commit_list_sort_by_date(&list);
1416                         return get_sha1_oneline(name + 2, sha1, list);
1417                 }
1418                 if (namelen < 3 ||
1419                     name[2] != ':' ||
1420                     name[1] < '0' || '3' < name[1])
1421                         cp = name + 1;
1422                 else {
1423                         stage = name[1] - '0';
1424                         cp = name + 3;
1425                 }
1426                 new_path = resolve_relative_path(cp);
1427                 if (!new_path) {
1428                         namelen = namelen - (cp - name);
1429                 } else {
1430                         cp = new_path;
1431                         namelen = strlen(cp);
1432                 }
1433
1434                 strlcpy(oc->path, cp, sizeof(oc->path));
1435
1436                 if (!active_cache)
1437                         read_cache();
1438                 pos = cache_name_pos(cp, namelen);
1439                 if (pos < 0)
1440                         pos = -pos - 1;
1441                 while (pos < active_nr) {
1442                         ce = active_cache[pos];
1443                         if (ce_namelen(ce) != namelen ||
1444                             memcmp(ce->name, cp, namelen))
1445                                 break;
1446                         if (ce_stage(ce) == stage) {
1447                                 hashcpy(sha1, ce->sha1);
1448                                 oc->mode = ce->ce_mode;
1449                                 free(new_path);
1450                                 return 0;
1451                         }
1452                         pos++;
1453                 }
1454                 if (only_to_die && name[1] && name[1] != '/')
1455                         diagnose_invalid_index_path(stage, prefix, cp);
1456                 free(new_path);
1457                 return -1;
1458         }
1459         for (cp = name, bracket_depth = 0; *cp; cp++) {
1460                 if (*cp == '{')
1461                         bracket_depth++;
1462                 else if (bracket_depth && *cp == '}')
1463                         bracket_depth--;
1464                 else if (!bracket_depth && *cp == ':')
1465                         break;
1466         }
1467         if (*cp == ':') {
1468                 unsigned char tree_sha1[20];
1469                 int len = cp - name;
1470                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1471                         const char *filename = cp+1;
1472                         char *new_filename = NULL;
1473
1474                         new_filename = resolve_relative_path(filename);
1475                         if (new_filename)
1476                                 filename = new_filename;
1477                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1478                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1479                                         filename, sha1, &oc->symlink_path,
1480                                         &oc->mode);
1481                         } else {
1482                                 ret = get_tree_entry(tree_sha1, filename,
1483                                                      sha1, &oc->mode);
1484                                 if (ret && only_to_die) {
1485                                         diagnose_invalid_sha1_path(prefix,
1486                                                                    filename,
1487                                                                    tree_sha1,
1488                                                                    name, len);
1489                                 }
1490                         }
1491                         hashcpy(oc->tree, tree_sha1);
1492                         strlcpy(oc->path, filename, sizeof(oc->path));
1493
1494                         free(new_filename);
1495                         return ret;
1496                 } else {
1497                         if (only_to_die)
1498                                 die("Invalid object name '%.*s'.", len, name);
1499                 }
1500         }
1501         return ret;
1502 }
1503
1504 /*
1505  * Call this function when you know "name" given by the end user must
1506  * name an object but it doesn't; the function _may_ die with a better
1507  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1508  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1509  * you have a chance to diagnose the error further.
1510  */
1511 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1512 {
1513         struct object_context oc;
1514         unsigned char sha1[20];
1515         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1516 }
1517
1518 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1519 {
1520         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1521                 die("BUG: incompatible flags for get_sha1_with_context");
1522         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1523 }