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
  10 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  11
  12 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
  13
  14 struct disambiguate_state {
  15         disambiguate_hint_fn fn;
  16         void *cb_data;
  17         unsigned char candidate[20];
  18         unsigned candidate_exists:1;
  19         unsigned candidate_checked:1;
  20         unsigned candidate_ok:1;
  21         unsigned disambiguate_fn_used:1;
  22         unsigned ambiguous:1;
  23         unsigned always_call_fn:1;
  24 };
  25
  26 static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
  27 {
  28         if (ds->always_call_fn) {
  29                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  30                 return;
  31         }
  32         if (!ds->candidate_exists) {
  33                 /* this is the first candidate */
  34                 hashcpy(ds->candidate, current);
  35                 ds->candidate_exists = 1;
  36                 return;
  37         } else if (!hashcmp(ds->candidate, current)) {
  38                 /* the same as what we already have seen */
  39                 return;
  40         }
  41
  42         if (!ds->fn) {
  43                 /* cannot disambiguate between ds->candidate and current */
  44                 ds->ambiguous = 1;
  45                 return;
  46         }
  47
  48         if (!ds->candidate_checked) {
  49                 ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
  50                 ds->disambiguate_fn_used = 1;
  51                 ds->candidate_checked = 1;
  52         }
  53
  54         if (!ds->candidate_ok) {
  55                 /* discard the candidate; we know it does not satisify fn */
  56                 hashcpy(ds->candidate, current);
  57                 ds->candidate_checked = 0;
  58                 return;
  59         }
  60
  61         /* if we reach this point, we know ds->candidate satisfies fn */
  62         if (ds->fn(current, ds->cb_data)) {
  63                 /*
  64                  * if both current and candidate satisfy fn, we cannot
  65                  * disambiguate.
  66                  */
  67                 ds->candidate_ok = 0;
  68                 ds->ambiguous = 1;
  69         }
  70
  71         /* otherwise, current can be discarded and candidate is still good */
  72 }
  73
  74 static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
  75 {
  76         struct alternate_object_database *alt;
  77         char hex[40];
  78         static struct alternate_object_database *fakeent;
  79
  80         if (!fakeent) {
  81                 /*
  82                  * Create a "fake" alternate object database that
  83                  * points to our own object database, to make it
  84                  * easier to get a temporary working space in
  85                  * alt->name/alt->base while iterating over the
  86                  * object databases including our own.
  87                  */
  88                 const char *objdir = get_object_directory();
  89                 int objdir_len = strlen(objdir);
  90                 int entlen = objdir_len + 43;
  91                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
  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         sprintf(hex, "%.2s", hex_pfx);
  99         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 100                 struct dirent *de;
 101                 DIR *dir;
 102                 sprintf(alt->name, "%.2s/", hex_pfx);
 103                 dir = opendir(alt->base);
 104                 if (!dir)
 105                         continue;
 106
 107                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 108                         unsigned char sha1[20];
 109
 110                         if (strlen(de->d_name) != 38)
 111                                 continue;
 112                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 113                                 continue;
 114                         memcpy(hex + 2, de->d_name, 38);
 115                         if (!get_sha1_hex(hex, sha1))
 116                                 update_candidates(ds, sha1);
 117                 }
 118                 closedir(dir);
 119         }
 120 }
 121
 122 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 123 {
 124         do {
 125                 if (*a != *b)
 126                         return 0;
 127                 a++;
 128                 b++;
 129                 len -= 2;
 130         } while (len > 1);
 131         if (len)
 132                 if ((*a ^ *b) & 0xf0)
 133                         return 0;
 134         return 1;
 135 }
 136
 137 static void unique_in_pack(int len,
 138                           const unsigned char *bin_pfx,
 139                            struct packed_git *p,
 140                            struct disambiguate_state *ds)
 141 {
 142         uint32_t num, last, i, first = 0;
 143         const unsigned char *current = NULL;
 144
 145         open_pack_index(p);
 146         num = p->num_objects;
 147         last = num;
 148         while (first < last) {
 149                 uint32_t mid = (first + last) / 2;
 150                 const unsigned char *current;
 151                 int cmp;
 152
 153                 current = nth_packed_object_sha1(p, mid);
 154                 cmp = hashcmp(bin_pfx, current);
 155                 if (!cmp) {
 156                         first = mid;
 157                         break;
 158                 }
 159                 if (cmp > 0) {
 160                         first = mid+1;
 161                         continue;
 162                 }
 163                 last = mid;
 164         }
 165
 166         /*
 167          * At this point, "first" is the location of the lowest object
 168          * with an object name that could match "bin_pfx".  See if we have
 169          * 0, 1 or more objects that actually match(es).
 170          */
 171         for (i = first; i < num && !ds->ambiguous; i++) {
 172                 current = nth_packed_object_sha1(p, i);
 173                 if (!match_sha(len, bin_pfx, current))
 174                         break;
 175                 update_candidates(ds, current);
 176         }
 177 }
 178
 179 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 180                                      struct disambiguate_state *ds)
 181 {
 182         struct packed_git *p;
 183
 184         prepare_packed_git();
 185         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 186                 unique_in_pack(len, bin_pfx, p, ds);
 187 }
 188
 189 #define SHORT_NAME_NOT_FOUND (-1)
 190 #define SHORT_NAME_AMBIGUOUS (-2)
 191
 192 static int finish_object_disambiguation(struct disambiguate_state *ds,
 193                                         unsigned char *sha1)
 194 {
 195         if (ds->ambiguous)
 196                 return SHORT_NAME_AMBIGUOUS;
 197
 198         if (!ds->candidate_exists)
 199                 return SHORT_NAME_NOT_FOUND;
 200
 201         if (!ds->candidate_checked)
 202                 /*
 203                  * If this is the only candidate, there is no point
 204                  * calling the disambiguation hint callback.
 205                  *
 206                  * On the other hand, if the current candidate
 207                  * replaced an earlier candidate that did _not_ pass
 208                  * the disambiguation hint callback, then we do have
 209                  * more than one objects that match the short name
 210                  * given, so we should make sure this one matches;
 211                  * otherwise, if we discovered this one and the one
 212                  * that we previously discarded in the reverse order,
 213                  * we would end up showing different results in the
 214                  * same repository!
 215                  */
 216                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 217                                     ds->fn(ds->candidate, ds->cb_data));
 218
 219         if (!ds->candidate_ok)
 220                 return SHORT_NAME_AMBIGUOUS;
 221
 222         hashcpy(sha1, ds->candidate);
 223         return 0;
 224 }
 225
 226 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 227 {
 228         int kind = sha1_object_info(sha1, NULL);
 229         return kind == OBJ_COMMIT;
 230 }
 231
 232 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 233 {
 234         struct object *obj;
 235         int kind;
 236
 237         kind = sha1_object_info(sha1, NULL);
 238         if (kind == OBJ_COMMIT)
 239                 return 1;
 240         if (kind != OBJ_TAG)
 241                 return 0;
 242
 243         /* We need to do this the hard way... */
 244         obj = deref_tag(parse_object(sha1), NULL, 0);
 245         if (obj && obj->type == OBJ_COMMIT)
 246                 return 1;
 247         return 0;
 248 }
 249
 250 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 251 {
 252         int kind = sha1_object_info(sha1, NULL);
 253         return kind == OBJ_TREE;
 254 }
 255
 256 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 257 {
 258         struct object *obj;
 259         int kind;
 260
 261         kind = sha1_object_info(sha1, NULL);
 262         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 263                 return 1;
 264         if (kind != OBJ_TAG)
 265                 return 0;
 266
 267         /* We need to do this the hard way... */
 268         obj = deref_tag(lookup_object(sha1), NULL, 0);
 269         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 270                 return 1;
 271         return 0;
 272 }
 273
 274 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 275 {
 276         int kind = sha1_object_info(sha1, NULL);
 277         return kind == OBJ_BLOB;
 278 }
 279
 280 static int prepare_prefixes(const char *name, int len,
 281                             unsigned char *bin_pfx,
 282                             char *hex_pfx)
 283 {
 284         int i;
 285
 286         hashclr(bin_pfx);
 287         memset(hex_pfx, 'x', 40);
 288         for (i = 0; i < len ;i++) {
 289                 unsigned char c = name[i];
 290                 unsigned char val;
 291                 if (c >= '0' && c <= '9')
 292                         val = c - '0';
 293                 else if (c >= 'a' && c <= 'f')
 294                         val = c - 'a' + 10;
 295                 else if (c >= 'A' && c <='F') {
 296                         val = c - 'A' + 10;
 297                         c -= 'A' - 'a';
 298                 }
 299                 else
 300                         return -1;
 301                 hex_pfx[i] = c;
 302                 if (!(i & 1))
 303                         val <<= 4;
 304                 bin_pfx[i >> 1] |= val;
 305         }
 306         return 0;
 307 }
 308
 309 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 310                           unsigned flags)
 311 {
 312         int status;
 313         char hex_pfx[40];
 314         unsigned char bin_pfx[20];
 315         struct disambiguate_state ds;
 316         int quietly = !!(flags & GET_SHA1_QUIETLY);
 317
 318         if (len < MINIMUM_ABBREV || len > 40)
 319                 return -1;
 320         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 321                 return -1;
 322
 323         prepare_alt_odb();
 324
 325         memset(&ds, 0, sizeof(ds));
 326         if (flags & GET_SHA1_COMMIT)
 327                 ds.fn = disambiguate_commit_only;
 328         else if (flags & GET_SHA1_COMMITTISH)
 329                 ds.fn = disambiguate_committish_only;
 330         else if (flags & GET_SHA1_TREE)
 331                 ds.fn = disambiguate_tree_only;
 332         else if (flags & GET_SHA1_TREEISH)
 333                 ds.fn = disambiguate_treeish_only;
 334         else if (flags & GET_SHA1_BLOB)
 335                 ds.fn = disambiguate_blob_only;
 336
 337         find_short_object_filename(len, hex_pfx, &ds);
 338         find_short_packed_object(len, bin_pfx, &ds);
 339         status = finish_object_disambiguation(&ds, sha1);
 340
 341         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 342                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 343         return status;
 344 }
 345
 346
 347 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 348 {
 349         char hex_pfx[40];
 350         unsigned char bin_pfx[20];
 351         struct disambiguate_state ds;
 352         int len = strlen(prefix);
 353
 354         if (len < MINIMUM_ABBREV || len > 40)
 355                 return -1;
 356         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 357                 return -1;
 358
 359         prepare_alt_odb();
 360
 361         memset(&ds, 0, sizeof(ds));
 362         ds.always_call_fn = 1;
 363         ds.cb_data = cb_data;
 364         ds.fn = fn;
 365
 366         find_short_object_filename(len, hex_pfx, &ds);
 367         find_short_packed_object(len, bin_pfx, &ds);
 368         return ds.ambiguous;
 369 }
 370
 371 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 372 {
 373         int status, exists;
 374         static char hex[41];
 375
 376         exists = has_sha1_file(sha1);
 377         memcpy(hex, sha1_to_hex(sha1), 40);
 378         if (len == 40 || !len)
 379                 return hex;
 380         while (len < 40) {
 381                 unsigned char sha1_ret[20];
 382                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 383                 if (exists
 384                     ? !status
 385                     : status == SHORT_NAME_NOT_FOUND) {
 386                         hex[len] = 0;
 387                         return hex;
 388                 }
 389                 len++;
 390         }
 391         return hex;
 392 }
 393
 394 static int ambiguous_path(const char *path, int len)
 395 {
 396         int slash = 1;
 397         int cnt;
 398
 399         for (cnt = 0; cnt < len; cnt++) {
 400                 switch (*path++) {
 401                 case '\0':
 402                         break;
 403                 case '/':
 404                         if (slash)
 405                                 break;
 406                         slash = 1;
 407                         continue;
 408                 case '.':
 409                         continue;
 410                 default:
 411                         slash = 0;
 412                         continue;
 413                 }
 414                 break;
 415         }
 416         return slash;
 417 }
 418
 419 static inline int upstream_mark(const char *string, int len)
 420 {
 421         const char *suffix[] = { "@{upstream}", "@{u}" };
 422         int i;
 423
 424         for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 425                 int suffix_len = strlen(suffix[i]);
 426                 if (suffix_len <= len
 427                     && !memcmp(string, suffix[i], suffix_len))
 428                         return suffix_len;
 429         }
 430         return 0;
 431 }
 432
 433 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 434 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf);
 435
 436 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 437 {
 438         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 439         static const char *object_name_msg = N_(
 440         "Git normally never creates a ref that ends with 40 hex characters\n"
 441         "because it will be ignored when you just specify 40-hex. These refs\n"
 442         "may be created by mistake. For example,\n"
 443         "\n"
 444         "  git checkout -b $br $(git rev-parse ...)\n"
 445         "\n"
 446         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 447         "examine these refs and maybe delete them. Turn this message off by\n"
 448         "running \"git config advice.object_name_warning false\"");
 449         unsigned char tmp_sha1[20];
 450         char *real_ref = NULL;
 451         int refs_found = 0;
 452         int at, reflog_len, nth_prior = 0;
 453
 454         if (len == 40 && !get_sha1_hex(str, sha1)) {
 455                 if (warn_on_object_refname_ambiguity) {
 456                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 457                         if (refs_found > 0 && warn_ambiguous_refs) {
 458                                 warning(warn_msg, len, str);
 459                                 if (advice_object_name_warning)
 460                                         fprintf(stderr, "%s\n", _(object_name_msg));
 461                         }
 462                         free(real_ref);
 463                 }
 464                 return 0;
 465         }
 466
 467         /* basic@{time or number or -number} format to query ref-log */
 468         reflog_len = at = 0;
 469         if (len && str[len-1] == '}') {
 470                 for (at = len-4; at >= 0; at--) {
 471                         if (str[at] == '@' && str[at+1] == '{') {
 472                                 if (str[at+2] == '-') {
 473                                         if (at != 0)
 474                                                 /* @{-N} not at start */
 475                                                 return -1;
 476                                         nth_prior = 1;
 477                                         continue;
 478                                 }
 479                                 if (!upstream_mark(str + at, len - at)) {
 480                                         reflog_len = (len-1) - (at+2);
 481                                         len = at;
 482                                 }
 483                                 break;
 484                         }
 485                 }
 486         }
 487
 488         /* Accept only unambiguous ref paths. */
 489         if (len && ambiguous_path(str, len))
 490                 return -1;
 491
 492         if (nth_prior) {
 493                 struct strbuf buf = STRBUF_INIT;
 494                 int detached;
 495
 496                 if (interpret_nth_prior_checkout(str, &buf) > 0) {
 497                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 498                         strbuf_release(&buf);
 499                         if (detached)
 500                                 return 0;
 501                 }
 502         }
 503
 504         if (!len && reflog_len)
 505                 /* allow "@{...}" to mean the current branch reflog */
 506                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 507         else if (reflog_len)
 508                 refs_found = dwim_log(str, len, sha1, &real_ref);
 509         else
 510                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 511
 512         if (!refs_found)
 513                 return -1;
 514
 515         if (warn_ambiguous_refs &&
 516             (refs_found > 1 ||
 517              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 518                 warning(warn_msg, len, str);
 519
 520         if (reflog_len) {
 521                 int nth, i;
 522                 unsigned long at_time;
 523                 unsigned long co_time;
 524                 int co_tz, co_cnt;
 525
 526                 /* Is it asking for N-th entry, or approxidate? */
 527                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 528                         char ch = str[at+2+i];
 529                         if ('0' <= ch && ch <= '9')
 530                                 nth = nth * 10 + ch - '0';
 531                         else
 532                                 nth = -1;
 533                 }
 534                 if (100000000 <= nth) {
 535                         at_time = nth;
 536                         nth = -1;
 537                 } else if (0 <= nth)
 538                         at_time = 0;
 539                 else {
 540                         int errors = 0;
 541                         char *tmp = xstrndup(str + at + 2, reflog_len);
 542                         at_time = approxidate_careful(tmp, &errors);
 543                         free(tmp);
 544                         if (errors)
 545                                 return -1;
 546                 }
 547                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
 548                                 &co_time, &co_tz, &co_cnt)) {
 549                         if (!len) {
 550                                 if (!prefixcmp(real_ref, "refs/heads/")) {
 551                                         str = real_ref + 11;
 552                                         len = strlen(real_ref + 11);
 553                                 } else {
 554                                         /* detached HEAD */
 555                                         str = "HEAD";
 556                                         len = 4;
 557                                 }
 558                         }
 559                         if (at_time)
 560                                 warning("Log for '%.*s' only goes "
 561                                         "back to %s.", len, str,
 562                                         show_date(co_time, co_tz, DATE_RFC2822));
 563                         else {
 564                                 die("Log for '%.*s' only has %d entries.",
 565                                     len, str, co_cnt);
 566                         }
 567                 }
 568         }
 569
 570         free(real_ref);
 571         return 0;
 572 }
 573
 574 static int get_parent(const char *name, int len,
 575                       unsigned char *result, int idx)
 576 {
 577         unsigned char sha1[20];
 578         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 579         struct commit *commit;
 580         struct commit_list *p;
 581
 582         if (ret)
 583                 return ret;
 584         commit = lookup_commit_reference(sha1);
 585         if (!commit)
 586                 return -1;
 587         if (parse_commit(commit))
 588                 return -1;
 589         if (!idx) {
 590                 hashcpy(result, commit->object.sha1);
 591                 return 0;
 592         }
 593         p = commit->parents;
 594         while (p) {
 595                 if (!--idx) {
 596                         hashcpy(result, p->item->object.sha1);
 597                         return 0;
 598                 }
 599                 p = p->next;
 600         }
 601         return -1;
 602 }
 603
 604 static int get_nth_ancestor(const char *name, int len,
 605                             unsigned char *result, int generation)
 606 {
 607         unsigned char sha1[20];
 608         struct commit *commit;
 609         int ret;
 610
 611         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 612         if (ret)
 613                 return ret;
 614         commit = lookup_commit_reference(sha1);
 615         if (!commit)
 616                 return -1;
 617
 618         while (generation--) {
 619                 if (parse_commit(commit) || !commit->parents)
 620                         return -1;
 621                 commit = commit->parents->item;
 622         }
 623         hashcpy(result, commit->object.sha1);
 624         return 0;
 625 }
 626
 627 struct object *peel_to_type(const char *name, int namelen,
 628                             struct object *o, enum object_type expected_type)
 629 {
 630         if (name && !namelen)
 631                 namelen = strlen(name);
 632         while (1) {
 633                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 634                         return NULL;
 635                 if (expected_type == OBJ_ANY || o->type == expected_type)
 636                         return o;
 637                 if (o->type == OBJ_TAG)
 638                         o = ((struct tag*) o)->tagged;
 639                 else if (o->type == OBJ_COMMIT)
 640                         o = &(((struct commit *) o)->tree->object);
 641                 else {
 642                         if (name)
 643                                 error("%.*s: expected %s type, but the object "
 644                                       "dereferences to %s type",
 645                                       namelen, name, typename(expected_type),
 646                                       typename(o->type));
 647                         return NULL;
 648                 }
 649         }
 650 }
 651
 652 static int peel_onion(const char *name, int len, unsigned char *sha1)
 653 {
 654         unsigned char outer[20];
 655         const char *sp;
 656         unsigned int expected_type = 0;
 657         unsigned lookup_flags = 0;
 658         struct object *o;
 659
 660         /*
 661          * "ref^{type}" dereferences ref repeatedly until you cannot
 662          * dereference anymore, or you get an object of given type,
 663          * whichever comes first.  "ref^{}" means just dereference
 664          * tags until you get a non-tag.  "ref^0" is a shorthand for
 665          * "ref^{commit}".  "commit^{tree}" could be used to find the
 666          * top-level tree of the given commit.
 667          */
 668         if (len < 4 || name[len-1] != '}')
 669                 return -1;
 670
 671         for (sp = name + len - 1; name <= sp; sp--) {
 672                 int ch = *sp;
 673                 if (ch == '{' && name < sp && sp[-1] == '^')
 674                         break;
 675         }
 676         if (sp <= name)
 677                 return -1;
 678
 679         sp++; /* beginning of type name, or closing brace for empty */
 680         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 681                 expected_type = OBJ_COMMIT;
 682         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 683                 expected_type = OBJ_TREE;
 684         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 685                 expected_type = OBJ_BLOB;
 686         else if (!prefixcmp(sp, "object}"))
 687                 expected_type = OBJ_ANY;
 688         else if (sp[0] == '}')
 689                 expected_type = OBJ_NONE;
 690         else if (sp[0] == '/')
 691                 expected_type = OBJ_COMMIT;
 692         else
 693                 return -1;
 694
 695         if (expected_type == OBJ_COMMIT)
 696                 lookup_flags = GET_SHA1_COMMITTISH;
 697         else if (expected_type == OBJ_TREE)
 698                 lookup_flags = GET_SHA1_TREEISH;
 699
 700         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 701                 return -1;
 702
 703         o = parse_object(outer);
 704         if (!o)
 705                 return -1;
 706         if (!expected_type) {
 707                 o = deref_tag(o, name, sp - name - 2);
 708                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 709                         return -1;
 710                 hashcpy(sha1, o->sha1);
 711                 return 0;
 712         }
 713
 714         /*
 715          * At this point, the syntax look correct, so
 716          * if we do not get the needed object, we should
 717          * barf.
 718          */
 719         o = peel_to_type(name, len, o, expected_type);
 720         if (!o)
 721                 return -1;
 722
 723         hashcpy(sha1, o->sha1);
 724         if (sp[0] == '/') {
 725                 /* "$commit^{/foo}" */
 726                 char *prefix;
 727                 int ret;
 728                 struct commit_list *list = NULL;
 729
 730                 /*
 731                  * $commit^{/}. Some regex implementation may reject.
 732                  * We don't need regex anyway. '' pattern always matches.
 733                  */
 734                 if (sp[1] == '}')
 735                         return 0;
 736
 737                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 738                 commit_list_insert((struct commit *)o, &list);
 739                 ret = get_sha1_oneline(prefix, sha1, list);
 740                 free(prefix);
 741                 return ret;
 742         }
 743         return 0;
 744 }
 745
 746 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 747 {
 748         const char *cp;
 749         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 750
 751         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 752                 char ch = *cp;
 753                 if (hexval(ch) & ~0377) {
 754                         /* We must be looking at g in "SOMETHING-g"
 755                          * for it to be describe output.
 756                          */
 757                         if (ch == 'g' && cp[-1] == '-') {
 758                                 cp++;
 759                                 len -= cp - name;
 760                                 return get_short_sha1(cp, len, sha1, flags);
 761                         }
 762                 }
 763         }
 764         return -1;
 765 }
 766
 767 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 768 {
 769         int ret, has_suffix;
 770         const char *cp;
 771
 772         /*
 773          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 774          */
 775         has_suffix = 0;
 776         for (cp = name + len - 1; name <= cp; cp--) {
 777                 int ch = *cp;
 778                 if ('0' <= ch && ch <= '9')
 779                         continue;
 780                 if (ch == '~' || ch == '^')
 781                         has_suffix = ch;
 782                 break;
 783         }
 784
 785         if (has_suffix) {
 786                 int num = 0;
 787                 int len1 = cp - name;
 788                 cp++;
 789                 while (cp < name + len)
 790                         num = num * 10 + *cp++ - '0';
 791                 if (!num && len1 == len - 1)
 792                         num = 1;
 793                 if (has_suffix == '^')
 794                         return get_parent(name, len1, sha1, num);
 795                 /* else if (has_suffix == '~') -- goes without saying */
 796                 return get_nth_ancestor(name, len1, sha1, num);
 797         }
 798
 799         ret = peel_onion(name, len, sha1);
 800         if (!ret)
 801                 return 0;
 802
 803         ret = get_sha1_basic(name, len, sha1);
 804         if (!ret)
 805                 return 0;
 806
 807         /* It could be describe output that is "SOMETHING-gXXXX" */
 808         ret = get_describe_name(name, len, sha1);
 809         if (!ret)
 810                 return 0;
 811
 812         return get_short_sha1(name, len, sha1, lookup_flags);
 813 }
 814
 815 /*
 816  * This interprets names like ':/Initial revision of "git"' by searching
 817  * through history and returning the first commit whose message starts
 818  * the given regular expression.
 819  *
 820  * For future extension, ':/!' is reserved. If you want to match a message
 821  * beginning with a '!', you have to repeat the exclamation mark.
 822  */
 823 #define ONELINE_SEEN (1u<<20)
 824
 825 static int handle_one_ref(const char *path,
 826                 const unsigned char *sha1, int flag, void *cb_data)
 827 {
 828         struct commit_list **list = cb_data;
 829         struct object *object = parse_object(sha1);
 830         if (!object)
 831                 return 0;
 832         if (object->type == OBJ_TAG) {
 833                 object = deref_tag(object, path, strlen(path));
 834                 if (!object)
 835                         return 0;
 836         }
 837         if (object->type != OBJ_COMMIT)
 838                 return 0;
 839         commit_list_insert_by_date((struct commit *)object, list);
 840         return 0;
 841 }
 842
 843 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 844                             struct commit_list *list)
 845 {
 846         struct commit_list *backup = NULL, *l;
 847         int found = 0;
 848         regex_t regex;
 849
 850         if (prefix[0] == '!') {
 851                 if (prefix[1] != '!')
 852                         die ("Invalid search pattern: %s", prefix);
 853                 prefix++;
 854         }
 855
 856         if (regcomp(&regex, prefix, REG_EXTENDED))
 857                 die("Invalid search pattern: %s", prefix);
 858
 859         for (l = list; l; l = l->next) {
 860                 l->item->object.flags |= ONELINE_SEEN;
 861                 commit_list_insert(l->item, &backup);
 862         }
 863         while (list) {
 864                 char *p, *to_free = NULL;
 865                 struct commit *commit;
 866                 enum object_type type;
 867                 unsigned long size;
 868                 int matches;
 869
 870                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 871                 if (!parse_object(commit->object.sha1))
 872                         continue;
 873                 if (commit->buffer)
 874                         p = commit->buffer;
 875                 else {
 876                         p = read_sha1_file(commit->object.sha1, &type, &size);
 877                         if (!p)
 878                                 continue;
 879                         to_free = p;
 880                 }
 881
 882                 p = strstr(p, "\n\n");
 883                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 884                 free(to_free);
 885
 886                 if (matches) {
 887                         hashcpy(sha1, commit->object.sha1);
 888                         found = 1;
 889                         break;
 890                 }
 891         }
 892         regfree(&regex);
 893         free_commit_list(list);
 894         for (l = backup; l; l = l->next)
 895                 clear_commit_marks(l->item, ONELINE_SEEN);
 896         free_commit_list(backup);
 897         return found ? 0 : -1;
 898 }
 899
 900 struct grab_nth_branch_switch_cbdata {
 901         int remaining;
 902         struct strbuf buf;
 903 };
 904
 905 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 906                                   const char *email, unsigned long timestamp, int tz,
 907                                   const char *message, void *cb_data)
 908 {
 909         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 910         const char *match = NULL, *target = NULL;
 911         size_t len;
 912
 913         if (!prefixcmp(message, "checkout: moving from ")) {
 914                 match = message + strlen("checkout: moving from ");
 915                 target = strstr(match, " to ");
 916         }
 917
 918         if (!match || !target)
 919                 return 0;
 920         if (--(cb->remaining) == 0) {
 921                 len = target - match;
 922                 strbuf_reset(&cb->buf);
 923                 strbuf_add(&cb->buf, match, len);
 924                 return 1; /* we are done */
 925         }
 926         return 0;
 927 }
 928
 929 /*
 930  * Parse @{-N} syntax, return the number of characters parsed
 931  * if successful; otherwise signal an error with negative value.
 932  */
 933 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 934 {
 935         long nth;
 936         int retval;
 937         struct grab_nth_branch_switch_cbdata cb;
 938         const char *brace;
 939         char *num_end;
 940
 941         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 942                 return -1;
 943         brace = strchr(name, '}');
 944         if (!brace)
 945                 return -1;
 946         nth = strtol(name + 3, &num_end, 10);
 947         if (num_end != brace)
 948                 return -1;
 949         if (nth <= 0)
 950                 return -1;
 951         cb.remaining = nth;
 952         strbuf_init(&cb.buf, 20);
 953
 954         retval = 0;
 955         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 956                 strbuf_reset(buf);
 957                 strbuf_add(buf, cb.buf.buf, cb.buf.len);
 958                 retval = brace - name + 1;
 959         }
 960
 961         strbuf_release(&cb.buf);
 962         return retval;
 963 }
 964
 965 int get_sha1_mb(const char *name, unsigned char *sha1)
 966 {
 967         struct commit *one, *two;
 968         struct commit_list *mbs;
 969         unsigned char sha1_tmp[20];
 970         const char *dots;
 971         int st;
 972
 973         dots = strstr(name, "...");
 974         if (!dots)
 975                 return get_sha1(name, sha1);
 976         if (dots == name)
 977                 st = get_sha1("HEAD", sha1_tmp);
 978         else {
 979                 struct strbuf sb;
 980                 strbuf_init(&sb, dots - name);
 981                 strbuf_add(&sb, name, dots - name);
 982                 st = get_sha1_committish(sb.buf, sha1_tmp);
 983                 strbuf_release(&sb);
 984         }
 985         if (st)
 986                 return st;
 987         one = lookup_commit_reference_gently(sha1_tmp, 0);
 988         if (!one)
 989                 return -1;
 990
 991         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
 992                 return -1;
 993         two = lookup_commit_reference_gently(sha1_tmp, 0);
 994         if (!two)
 995                 return -1;
 996         mbs = get_merge_bases(one, two, 1);
 997         if (!mbs || mbs->next)
 998                 st = -1;
 999         else {
1000                 st = 0;
1001                 hashcpy(sha1, mbs->item->object.sha1);
1002         }
1003         free_commit_list(mbs);
1004         return st;
1005 }
1006
1007 /* parse @something syntax, when 'something' is not {.*} */
1008 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1009 {
1010         if (len || name[1] == '{')
1011                 return -1;
1012
1013         strbuf_reset(buf);
1014         strbuf_add(buf, "HEAD", 4);
1015         return 1;
1016 }
1017
1018 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1019 {
1020         /* we have extra data, which might need further processing */
1021         struct strbuf tmp = STRBUF_INIT;
1022         int used = buf->len;
1023         int ret;
1024
1025         strbuf_add(buf, name + len, namelen - len);
1026         ret = interpret_branch_name(buf->buf, &tmp);
1027         /* that data was not interpreted, remove our cruft */
1028         if (ret < 0) {
1029                 strbuf_setlen(buf, used);
1030                 return len;
1031         }
1032         strbuf_reset(buf);
1033         strbuf_addbuf(buf, &tmp);
1034         strbuf_release(&tmp);
1035         /* tweak for size of {-N} versus expanded ref name */
1036         return ret - used + len;
1037 }
1038
1039 /*
1040  * This reads short-hand syntax that not only evaluates to a commit
1041  * object name, but also can act as if the end user spelled the name
1042  * of the branch from the command line.
1043  *
1044  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1045  *   places the name of the branch in the given buf and returns the
1046  *   number of characters parsed if successful.
1047  *
1048  * - "<branch>@{upstream}" finds the name of the other ref that
1049  *   <branch> is configured to merge with (missing <branch> defaults
1050  *   to the current branch), and places the name of the branch in the
1051  *   given buf and returns the number of characters parsed if
1052  *   successful.
1053  *
1054  * If the input is not of the accepted format, it returns a negative
1055  * number to signal an error.
1056  *
1057  * If the input was ok but there are not N branch switches in the
1058  * reflog, it returns 0.
1059  */
1060 int interpret_branch_name(const char *name, struct strbuf *buf)
1061 {
1062         char *cp;
1063         struct branch *upstream;
1064         int namelen = strlen(name);
1065         int len = interpret_nth_prior_checkout(name, buf);
1066         int tmp_len;
1067
1068         if (!len) {
1069                 return len; /* syntax Ok, not enough switches */
1070         } else if (len > 0) {
1071                 if (len == namelen)
1072                         return len; /* consumed all */
1073                 else
1074                         return reinterpret(name, namelen, len, buf);
1075         }
1076
1077         cp = strchr(name, '@');
1078         if (!cp)
1079                 return -1;
1080
1081         len = interpret_empty_at(name, namelen, cp - name, buf);
1082         if (len > 0)
1083                 return reinterpret(name, namelen, len, buf);
1084
1085         tmp_len = upstream_mark(cp, namelen - (cp - name));
1086         if (!tmp_len)
1087                 return -1;
1088
1089         len = cp + tmp_len - name;
1090         cp = xstrndup(name, cp - name);
1091         upstream = branch_get(*cp ? cp : NULL);
1092         /*
1093          * Upstream can be NULL only if cp refers to HEAD and HEAD
1094          * points to something different than a branch.
1095          */
1096         if (!upstream)
1097                 die(_("HEAD does not point to a branch"));
1098         if (!upstream->merge || !upstream->merge[0]->dst) {
1099                 if (!ref_exists(upstream->refname))
1100                         die(_("No such branch: '%s'"), cp);
1101                 if (!upstream->merge) {
1102                         die(_("No upstream configured for branch '%s'"),
1103                                 upstream->name);
1104                 }
1105                 die(
1106                         _("Upstream branch '%s' not stored as a remote-tracking branch"),
1107                         upstream->merge[0]->src);
1108         }
1109         free(cp);
1110         cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
1111         strbuf_reset(buf);
1112         strbuf_addstr(buf, cp);
1113         free(cp);
1114         return len;
1115 }
1116
1117 int strbuf_branchname(struct strbuf *sb, const char *name)
1118 {
1119         int len = strlen(name);
1120         int used = interpret_branch_name(name, sb);
1121
1122         if (used == len)
1123                 return 0;
1124         if (used < 0)
1125                 used = 0;
1126         strbuf_add(sb, name + used, len - used);
1127         return len;
1128 }
1129
1130 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1131 {
1132         strbuf_branchname(sb, name);
1133         if (name[0] == '-')
1134                 return -1;
1135         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1136         return check_refname_format(sb->buf, 0);
1137 }
1138
1139 /*
1140  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1141  * notably "xyz^" for "parent of xyz"
1142  */
1143 int get_sha1(const char *name, unsigned char *sha1)
1144 {
1145         struct object_context unused;
1146         return get_sha1_with_context(name, 0, sha1, &unused);
1147 }
1148
1149 /*
1150  * Many callers know that the user meant to name a committish by
1151  * syntactical positions where the object name appears.  Calling this
1152  * function allows the machinery to disambiguate shorter-than-unique
1153  * abbreviated object names between committish and others.
1154  *
1155  * Note that this does NOT error out when the named object is not a
1156  * committish. It is merely to give a hint to the disambiguation
1157  * machinery.
1158  */
1159 int get_sha1_committish(const char *name, unsigned char *sha1)
1160 {
1161         struct object_context unused;
1162         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1163                                      sha1, &unused);
1164 }
1165
1166 int get_sha1_treeish(const char *name, unsigned char *sha1)
1167 {
1168         struct object_context unused;
1169         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1170                                      sha1, &unused);
1171 }
1172
1173 int get_sha1_commit(const char *name, unsigned char *sha1)
1174 {
1175         struct object_context unused;
1176         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1177                                      sha1, &unused);
1178 }
1179
1180 int get_sha1_tree(const char *name, unsigned char *sha1)
1181 {
1182         struct object_context unused;
1183         return get_sha1_with_context(name, GET_SHA1_TREE,
1184                                      sha1, &unused);
1185 }
1186
1187 int get_sha1_blob(const char *name, unsigned char *sha1)
1188 {
1189         struct object_context unused;
1190         return get_sha1_with_context(name, GET_SHA1_BLOB,
1191                                      sha1, &unused);
1192 }
1193
1194 /* Must be called only when object_name:filename doesn't exist. */
1195 static void diagnose_invalid_sha1_path(const char *prefix,
1196                                        const char *filename,
1197                                        const unsigned char *tree_sha1,
1198                                        const char *object_name,
1199                                        int object_name_len)
1200 {
1201         struct stat st;
1202         unsigned char sha1[20];
1203         unsigned mode;
1204
1205         if (!prefix)
1206                 prefix = "";
1207
1208         if (!lstat(filename, &st))
1209                 die("Path '%s' exists on disk, but not in '%.*s'.",
1210                     filename, object_name_len, object_name);
1211         if (errno == ENOENT || errno == ENOTDIR) {
1212                 char *fullname = xmalloc(strlen(filename)
1213                                              + strlen(prefix) + 1);
1214                 strcpy(fullname, prefix);
1215                 strcat(fullname, filename);
1216
1217                 if (!get_tree_entry(tree_sha1, fullname,
1218                                     sha1, &mode)) {
1219                         die("Path '%s' exists, but not '%s'.\n"
1220                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1221                             fullname,
1222                             filename,
1223                             object_name_len, object_name,
1224                             fullname,
1225                             object_name_len, object_name,
1226                             filename);
1227                 }
1228                 die("Path '%s' does not exist in '%.*s'",
1229                     filename, object_name_len, object_name);
1230         }
1231 }
1232
1233 /* Must be called only when :stage:filename doesn't exist. */
1234 static void diagnose_invalid_index_path(int stage,
1235                                         const char *prefix,
1236                                         const char *filename)
1237 {
1238         struct stat st;
1239         const struct cache_entry *ce;
1240         int pos;
1241         unsigned namelen = strlen(filename);
1242         unsigned fullnamelen;
1243         char *fullname;
1244
1245         if (!prefix)
1246                 prefix = "";
1247
1248         /* Wrong stage number? */
1249         pos = cache_name_pos(filename, namelen);
1250         if (pos < 0)
1251                 pos = -pos - 1;
1252         if (pos < active_nr) {
1253                 ce = active_cache[pos];
1254                 if (ce_namelen(ce) == namelen &&
1255                     !memcmp(ce->name, filename, namelen))
1256                         die("Path '%s' is in the index, but not at stage %d.\n"
1257                             "Did you mean ':%d:%s'?",
1258                             filename, stage,
1259                             ce_stage(ce), filename);
1260         }
1261
1262         /* Confusion between relative and absolute filenames? */
1263         fullnamelen = namelen + strlen(prefix);
1264         fullname = xmalloc(fullnamelen + 1);
1265         strcpy(fullname, prefix);
1266         strcat(fullname, filename);
1267         pos = cache_name_pos(fullname, fullnamelen);
1268         if (pos < 0)
1269                 pos = -pos - 1;
1270         if (pos < active_nr) {
1271                 ce = active_cache[pos];
1272                 if (ce_namelen(ce) == fullnamelen &&
1273                     !memcmp(ce->name, fullname, fullnamelen))
1274                         die("Path '%s' is in the index, but not '%s'.\n"
1275                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1276                             fullname, filename,
1277                             ce_stage(ce), fullname,
1278                             ce_stage(ce), filename);
1279         }
1280
1281         if (!lstat(filename, &st))
1282                 die("Path '%s' exists on disk, but not in the index.", filename);
1283         if (errno == ENOENT || errno == ENOTDIR)
1284                 die("Path '%s' does not exist (neither on disk nor in the index).",
1285                     filename);
1286
1287         free(fullname);
1288 }
1289
1290
1291 static char *resolve_relative_path(const char *rel)
1292 {
1293         if (prefixcmp(rel, "./") && prefixcmp(rel, "../"))
1294                 return NULL;
1295
1296         if (!startup_info)
1297                 die("BUG: startup_info struct is not initialized.");
1298
1299         if (!is_inside_work_tree())
1300                 die("relative path syntax can't be used outside working tree.");
1301
1302         /* die() inside prefix_path() if resolved path is outside worktree */
1303         return prefix_path(startup_info->prefix,
1304                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1305                            rel);
1306 }
1307
1308 static int get_sha1_with_context_1(const char *name,
1309                                    unsigned flags,
1310                                    const char *prefix,
1311                                    unsigned char *sha1,
1312                                    struct object_context *oc)
1313 {
1314         int ret, bracket_depth;
1315         int namelen = strlen(name);
1316         const char *cp;
1317         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1318
1319         memset(oc, 0, sizeof(*oc));
1320         oc->mode = S_IFINVALID;
1321         ret = get_sha1_1(name, namelen, sha1, flags);
1322         if (!ret)
1323                 return ret;
1324         /*
1325          * sha1:path --> object name of path in ent sha1
1326          * :path -> object name of absolute path in index
1327          * :./path -> object name of path relative to cwd in index
1328          * :[0-3]:path -> object name of path in index at stage
1329          * :/foo -> recent commit matching foo
1330          */
1331         if (name[0] == ':') {
1332                 int stage = 0;
1333                 const struct cache_entry *ce;
1334                 char *new_path = NULL;
1335                 int pos;
1336                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1337                         struct commit_list *list = NULL;
1338                         for_each_ref(handle_one_ref, &list);
1339                         return get_sha1_oneline(name + 2, sha1, list);
1340                 }
1341                 if (namelen < 3 ||
1342                     name[2] != ':' ||
1343                     name[1] < '0' || '3' < name[1])
1344                         cp = name + 1;
1345                 else {
1346                         stage = name[1] - '0';
1347                         cp = name + 3;
1348                 }
1349                 new_path = resolve_relative_path(cp);
1350                 if (!new_path) {
1351                         namelen = namelen - (cp - name);
1352                 } else {
1353                         cp = new_path;
1354                         namelen = strlen(cp);
1355                 }
1356
1357                 strncpy(oc->path, cp,
1358                         sizeof(oc->path));
1359                 oc->path[sizeof(oc->path)-1] = '\0';
1360
1361                 if (!active_cache)
1362                         read_cache();
1363                 pos = cache_name_pos(cp, namelen);
1364                 if (pos < 0)
1365                         pos = -pos - 1;
1366                 while (pos < active_nr) {
1367                         ce = active_cache[pos];
1368                         if (ce_namelen(ce) != namelen ||
1369                             memcmp(ce->name, cp, namelen))
1370                                 break;
1371                         if (ce_stage(ce) == stage) {
1372                                 hashcpy(sha1, ce->sha1);
1373                                 oc->mode = ce->ce_mode;
1374                                 free(new_path);
1375                                 return 0;
1376                         }
1377                         pos++;
1378                 }
1379                 if (only_to_die && name[1] && name[1] != '/')
1380                         diagnose_invalid_index_path(stage, prefix, cp);
1381                 free(new_path);
1382                 return -1;
1383         }
1384         for (cp = name, bracket_depth = 0; *cp; cp++) {
1385                 if (*cp == '{')
1386                         bracket_depth++;
1387                 else if (bracket_depth && *cp == '}')
1388                         bracket_depth--;
1389                 else if (!bracket_depth && *cp == ':')
1390                         break;
1391         }
1392         if (*cp == ':') {
1393                 unsigned char tree_sha1[20];
1394                 int len = cp - name;
1395                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1396                         const char *filename = cp+1;
1397                         char *new_filename = NULL;
1398
1399                         new_filename = resolve_relative_path(filename);
1400                         if (new_filename)
1401                                 filename = new_filename;
1402                         ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1403                         if (ret && only_to_die) {
1404                                 diagnose_invalid_sha1_path(prefix, filename,
1405                                                            tree_sha1,
1406                                                            name, len);
1407                         }
1408                         hashcpy(oc->tree, tree_sha1);
1409                         strncpy(oc->path, filename,
1410                                 sizeof(oc->path));
1411                         oc->path[sizeof(oc->path)-1] = '\0';
1412
1413                         free(new_filename);
1414                         return ret;
1415                 } else {
1416                         if (only_to_die)
1417                                 die("Invalid object name '%.*s'.", len, name);
1418                 }
1419         }
1420         return ret;
1421 }
1422
1423 /*
1424  * Call this function when you know "name" given by the end user must
1425  * name an object but it doesn't; the function _may_ die with a better
1426  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1427  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1428  * you have a chance to diagnose the error further.
1429  */
1430 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1431 {
1432         struct object_context oc;
1433         unsigned char sha1[20];
1434         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1435 }
1436
1437 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1438 {
1439         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1440 }