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 #include "sha1-array.h"
  11
  12 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  13
  14 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
  15
  16 struct disambiguate_state {
  17         int len; /* length of prefix in hex chars */
  18         unsigned int nrobjects;
  19         char hex_pfx[GIT_SHA1_HEXSZ + 1];
  20         unsigned char bin_pfx[GIT_SHA1_RAWSZ];
  21
  22         disambiguate_hint_fn fn;
  23         void *cb_data;
  24         unsigned char candidate[GIT_SHA1_RAWSZ];
  25         unsigned candidate_exists:1;
  26         unsigned candidate_checked:1;
  27         unsigned candidate_ok:1;
  28         unsigned disambiguate_fn_used:1;
  29         unsigned ambiguous:1;
  30         unsigned always_call_fn:1;
  31 };
  32
  33 static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
  34 {
  35         if (ds->always_call_fn) {
  36                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  37                 return;
  38         }
  39         if (!ds->candidate_exists) {
  40                 /* this is the first candidate */
  41                 hashcpy(ds->candidate, current);
  42                 ds->candidate_exists = 1;
  43                 return;
  44         } else if (!hashcmp(ds->candidate, current)) {
  45                 /* the same as what we already have seen */
  46                 return;
  47         }
  48
  49         if (!ds->fn) {
  50                 /* cannot disambiguate between ds->candidate and current */
  51                 ds->ambiguous = 1;
  52                 return;
  53         }
  54
  55         if (!ds->candidate_checked) {
  56                 ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
  57                 ds->disambiguate_fn_used = 1;
  58                 ds->candidate_checked = 1;
  59         }
  60
  61         if (!ds->candidate_ok) {
  62                 /* discard the candidate; we know it does not satisfy fn */
  63                 hashcpy(ds->candidate, current);
  64                 ds->candidate_checked = 0;
  65                 return;
  66         }
  67
  68         /* if we reach this point, we know ds->candidate satisfies fn */
  69         if (ds->fn(current, ds->cb_data)) {
  70                 /*
  71                  * if both current and candidate satisfy fn, we cannot
  72                  * disambiguate.
  73                  */
  74                 ds->candidate_ok = 0;
  75                 ds->ambiguous = 1;
  76         }
  77
  78         /* otherwise, current can be discarded and candidate is still good */
  79 }
  80
  81 static void find_short_object_filename(struct disambiguate_state *ds)
  82 {
  83         struct alternate_object_database *alt;
  84         char hex[GIT_SHA1_HEXSZ];
  85         static struct alternate_object_database *fakeent;
  86
  87         if (!fakeent) {
  88                 /*
  89                  * Create a "fake" alternate object database that
  90                  * points to our own object database, to make it
  91                  * easier to get a temporary working space in
  92                  * alt->name/alt->base while iterating over the
  93                  * object databases including our own.
  94                  */
  95                 const char *objdir = get_object_directory();
  96                 size_t objdir_len = strlen(objdir);
  97                 fakeent = xmalloc(st_add3(sizeof(*fakeent), objdir_len, 43));
  98                 memcpy(fakeent->base, objdir, objdir_len);
  99                 fakeent->name = fakeent->base + objdir_len + 1;
 100                 fakeent->name[-1] = '/';
 101         }
 102         fakeent->next = alt_odb_list;
 103
 104         xsnprintf(hex, sizeof(hex), "%.2s", ds->hex_pfx);
 105         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 106                 struct dirent *de;
 107                 DIR *dir;
 108                 /*
 109                  * every alt_odb struct has 42 extra bytes after the base
 110                  * for exactly this purpose
 111                  */
 112                 xsnprintf(alt->name, 42, "%.2s/", ds->hex_pfx);
 113                 dir = opendir(alt->base);
 114                 if (!dir)
 115                         continue;
 116
 117                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 118                         unsigned char sha1[20];
 119
 120                         if (strlen(de->d_name) != 38)
 121                                 continue;
 122
 123                         /*
 124                          * We only look at the one subdirectory, and we assume
 125                          * each subdirectory is roughly similar, so each
 126                          * object we find probably has 255 other objects in
 127                          * the other fan-out directories.
 128                          */
 129                         ds->nrobjects += 256;
 130                         if (memcmp(de->d_name, ds->hex_pfx + 2, ds->len - 2))
 131                                 continue;
 132                         memcpy(hex + 2, de->d_name, 38);
 133                         if (!get_sha1_hex(hex, sha1))
 134                                 update_candidates(ds, sha1);
 135                 }
 136                 closedir(dir);
 137         }
 138 }
 139
 140 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 141 {
 142         do {
 143                 if (*a != *b)
 144                         return 0;
 145                 a++;
 146                 b++;
 147                 len -= 2;
 148         } while (len > 1);
 149         if (len)
 150                 if ((*a ^ *b) & 0xf0)
 151                         return 0;
 152         return 1;
 153 }
 154
 155 static void unique_in_pack(struct packed_git *p,
 156                            struct disambiguate_state *ds)
 157 {
 158         uint32_t num, last, i, first = 0;
 159         const unsigned char *current = NULL;
 160
 161         open_pack_index(p);
 162         num = p->num_objects;
 163         ds->nrobjects += num;
 164         last = num;
 165         while (first < last) {
 166                 uint32_t mid = (first + last) / 2;
 167                 const unsigned char *current;
 168                 int cmp;
 169
 170                 current = nth_packed_object_sha1(p, mid);
 171                 cmp = hashcmp(ds->bin_pfx, current);
 172                 if (!cmp) {
 173                         first = mid;
 174                         break;
 175                 }
 176                 if (cmp > 0) {
 177                         first = mid+1;
 178                         continue;
 179                 }
 180                 last = mid;
 181         }
 182
 183         /*
 184          * At this point, "first" is the location of the lowest object
 185          * with an object name that could match "bin_pfx".  See if we have
 186          * 0, 1 or more objects that actually match(es).
 187          */
 188         for (i = first; i < num && !ds->ambiguous; i++) {
 189                 current = nth_packed_object_sha1(p, i);
 190                 if (!match_sha(ds->len, ds->bin_pfx, current))
 191                         break;
 192                 update_candidates(ds, current);
 193         }
 194 }
 195
 196 static void find_short_packed_object(struct disambiguate_state *ds)
 197 {
 198         struct packed_git *p;
 199
 200         prepare_packed_git();
 201         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 202                 unique_in_pack(p, ds);
 203 }
 204
 205 #define SHORT_NAME_NOT_FOUND (-1)
 206 #define SHORT_NAME_AMBIGUOUS (-2)
 207
 208 static int finish_object_disambiguation(struct disambiguate_state *ds,
 209                                         unsigned char *sha1)
 210 {
 211         if (ds->ambiguous)
 212                 return SHORT_NAME_AMBIGUOUS;
 213
 214         if (!ds->candidate_exists)
 215                 return SHORT_NAME_NOT_FOUND;
 216
 217         if (!ds->candidate_checked)
 218                 /*
 219                  * If this is the only candidate, there is no point
 220                  * calling the disambiguation hint callback.
 221                  *
 222                  * On the other hand, if the current candidate
 223                  * replaced an earlier candidate that did _not_ pass
 224                  * the disambiguation hint callback, then we do have
 225                  * more than one objects that match the short name
 226                  * given, so we should make sure this one matches;
 227                  * otherwise, if we discovered this one and the one
 228                  * that we previously discarded in the reverse order,
 229                  * we would end up showing different results in the
 230                  * same repository!
 231                  */
 232                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 233                                     ds->fn(ds->candidate, ds->cb_data));
 234
 235         if (!ds->candidate_ok)
 236                 return SHORT_NAME_AMBIGUOUS;
 237
 238         hashcpy(sha1, ds->candidate);
 239         return 0;
 240 }
 241
 242 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 243 {
 244         int kind = sha1_object_info(sha1, NULL);
 245         return kind == OBJ_COMMIT;
 246 }
 247
 248 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 249 {
 250         struct object *obj;
 251         int kind;
 252
 253         kind = sha1_object_info(sha1, NULL);
 254         if (kind == OBJ_COMMIT)
 255                 return 1;
 256         if (kind != OBJ_TAG)
 257                 return 0;
 258
 259         /* We need to do this the hard way... */
 260         obj = deref_tag(parse_object(sha1), NULL, 0);
 261         if (obj && obj->type == OBJ_COMMIT)
 262                 return 1;
 263         return 0;
 264 }
 265
 266 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 267 {
 268         int kind = sha1_object_info(sha1, NULL);
 269         return kind == OBJ_TREE;
 270 }
 271
 272 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 273 {
 274         struct object *obj;
 275         int kind;
 276
 277         kind = sha1_object_info(sha1, NULL);
 278         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 279                 return 1;
 280         if (kind != OBJ_TAG)
 281                 return 0;
 282
 283         /* We need to do this the hard way... */
 284         obj = deref_tag(parse_object(sha1), NULL, 0);
 285         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 286                 return 1;
 287         return 0;
 288 }
 289
 290 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 291 {
 292         int kind = sha1_object_info(sha1, NULL);
 293         return kind == OBJ_BLOB;
 294 }
 295
 296 static disambiguate_hint_fn default_disambiguate_hint;
 297
 298 int set_disambiguate_hint_config(const char *var, const char *value)
 299 {
 300         static const struct {
 301                 const char *name;
 302                 disambiguate_hint_fn fn;
 303         } hints[] = {
 304                 { "none", NULL },
 305                 { "commit", disambiguate_commit_only },
 306                 { "committish", disambiguate_committish_only },
 307                 { "tree", disambiguate_tree_only },
 308                 { "treeish", disambiguate_treeish_only },
 309                 { "blob", disambiguate_blob_only }
 310         };
 311         int i;
 312
 313         if (!value)
 314                 return config_error_nonbool(var);
 315
 316         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 317                 if (!strcasecmp(value, hints[i].name)) {
 318                         default_disambiguate_hint = hints[i].fn;
 319                         return 0;
 320                 }
 321         }
 322
 323         return error("unknown hint type for '%s': %s", var, value);
 324 }
 325
 326 static int init_object_disambiguation(const char *name, int len,
 327                                       struct disambiguate_state *ds)
 328 {
 329         int i;
 330
 331         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 332                 return -1;
 333
 334         memset(ds, 0, sizeof(*ds));
 335
 336         for (i = 0; i < len ;i++) {
 337                 unsigned char c = name[i];
 338                 unsigned char val;
 339                 if (c >= '0' && c <= '9')
 340                         val = c - '0';
 341                 else if (c >= 'a' && c <= 'f')
 342                         val = c - 'a' + 10;
 343                 else if (c >= 'A' && c <='F') {
 344                         val = c - 'A' + 10;
 345                         c -= 'A' - 'a';
 346                 }
 347                 else
 348                         return -1;
 349                 ds->hex_pfx[i] = c;
 350                 if (!(i & 1))
 351                         val <<= 4;
 352                 ds->bin_pfx[i >> 1] |= val;
 353         }
 354
 355         ds->len = len;
 356         ds->hex_pfx[len] = '\0';
 357         prepare_alt_odb();
 358         return 0;
 359 }
 360
 361 static int show_ambiguous_object(const unsigned char *sha1, void *data)
 362 {
 363         const struct disambiguate_state *ds = data;
 364         struct strbuf desc = STRBUF_INIT;
 365         int type;
 366
 367         if (ds->fn && !ds->fn(sha1, ds->cb_data))
 368                 return 0;
 369
 370         type = sha1_object_info(sha1, NULL);
 371         if (type == OBJ_COMMIT) {
 372                 struct commit *commit = lookup_commit(sha1);
 373                 if (commit) {
 374                         struct pretty_print_context pp = {0};
 375                         pp.date_mode.type = DATE_SHORT;
 376                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 377                 }
 378         } else if (type == OBJ_TAG) {
 379                 struct tag *tag = lookup_tag(sha1);
 380                 if (!parse_tag(tag) && tag->tag)
 381                         strbuf_addf(&desc, " %s", tag->tag);
 382         }
 383
 384         advise("  %s %s%s",
 385                find_unique_abbrev(sha1, DEFAULT_ABBREV),
 386                typename(type) ? typename(type) : "unknown type",
 387                desc.buf);
 388
 389         strbuf_release(&desc);
 390         return 0;
 391 }
 392
 393 /* start from our historical default before the automatic abbreviation */
 394 static int default_automatic_abbrev = FALLBACK_DEFAULT_ABBREV;
 395
 396 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 397                           unsigned flags)
 398 {
 399         int status;
 400         struct disambiguate_state ds;
 401         int quietly = !!(flags & GET_SHA1_QUIETLY);
 402
 403         if (init_object_disambiguation(name, len, &ds) < 0)
 404                 return -1;
 405
 406         if (HAS_MULTI_BITS(flags & GET_SHA1_DISAMBIGUATORS))
 407                 die("BUG: multiple get_short_sha1 disambiguator flags");
 408
 409         if (flags & GET_SHA1_COMMIT)
 410                 ds.fn = disambiguate_commit_only;
 411         else if (flags & GET_SHA1_COMMITTISH)
 412                 ds.fn = disambiguate_committish_only;
 413         else if (flags & GET_SHA1_TREE)
 414                 ds.fn = disambiguate_tree_only;
 415         else if (flags & GET_SHA1_TREEISH)
 416                 ds.fn = disambiguate_treeish_only;
 417         else if (flags & GET_SHA1_BLOB)
 418                 ds.fn = disambiguate_blob_only;
 419         else
 420                 ds.fn = default_disambiguate_hint;
 421
 422         find_short_object_filename(&ds);
 423         find_short_packed_object(&ds);
 424         status = finish_object_disambiguation(&ds, sha1);
 425
 426         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 427                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 428
 429                 /*
 430                  * We may still have ambiguity if we simply saw a series of
 431                  * candidates that did not satisfy our hint function. In
 432                  * that case, we still want to show them, so disable the hint
 433                  * function entirely.
 434                  */
 435                 if (!ds.ambiguous)
 436                         ds.fn = NULL;
 437
 438                 advise(_("The candidates are:"));
 439                 for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
 440         }
 441
 442         if (len < 16 && !status && (flags & GET_SHA1_AUTOMATIC)) {
 443                 unsigned int expect_collision = 1 << (len * 2);
 444                 if (ds.nrobjects > expect_collision) {
 445                         default_automatic_abbrev = len+1;
 446                         return SHORT_NAME_AMBIGUOUS;
 447                 }
 448         }
 449
 450         return status;
 451 }
 452
 453 static int collect_ambiguous(const unsigned char *sha1, void *data)
 454 {
 455         sha1_array_append(data, sha1);
 456         return 0;
 457 }
 458
 459 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 460 {
 461         struct sha1_array collect = SHA1_ARRAY_INIT;
 462         struct disambiguate_state ds;
 463         int ret;
 464
 465         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 466                 return -1;
 467
 468         ds.always_call_fn = 1;
 469         ds.fn = collect_ambiguous;
 470         ds.cb_data = &collect;
 471         find_short_object_filename(&ds);
 472         find_short_packed_object(&ds);
 473
 474         ret = sha1_array_for_each_unique(&collect, fn, cb_data);
 475         sha1_array_clear(&collect);
 476         return ret;
 477 }
 478
 479 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 480 {
 481         int status, exists;
 482         int flags = GET_SHA1_QUIETLY;
 483
 484         if (len < 0) {
 485                 flags |= GET_SHA1_AUTOMATIC;
 486                 len = default_automatic_abbrev;
 487         }
 488         sha1_to_hex_r(hex, sha1);
 489         if (len == 40 || !len)
 490                 return 40;
 491         exists = has_sha1_file(sha1);
 492         while (len < 40) {
 493                 unsigned char sha1_ret[20];
 494                 status = get_short_sha1(hex, len, sha1_ret, flags);
 495                 if (exists
 496                     ? !status
 497                     : status == SHORT_NAME_NOT_FOUND) {
 498                         hex[len] = 0;
 499                         return len;
 500                 }
 501                 len++;
 502         }
 503         return len;
 504 }
 505
 506 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 507 {
 508         static char hex[GIT_SHA1_HEXSZ + 1];
 509         find_unique_abbrev_r(hex, sha1, len);
 510         return hex;
 511 }
 512
 513 static int ambiguous_path(const char *path, int len)
 514 {
 515         int slash = 1;
 516         int cnt;
 517
 518         for (cnt = 0; cnt < len; cnt++) {
 519                 switch (*path++) {
 520                 case '\0':
 521                         break;
 522                 case '/':
 523                         if (slash)
 524                                 break;
 525                         slash = 1;
 526                         continue;
 527                 case '.':
 528                         continue;
 529                 default:
 530                         slash = 0;
 531                         continue;
 532                 }
 533                 break;
 534         }
 535         return slash;
 536 }
 537
 538 static inline int at_mark(const char *string, int len,
 539                           const char **suffix, int nr)
 540 {
 541         int i;
 542
 543         for (i = 0; i < nr; i++) {
 544                 int suffix_len = strlen(suffix[i]);
 545                 if (suffix_len <= len
 546                     && !memcmp(string, suffix[i], suffix_len))
 547                         return suffix_len;
 548         }
 549         return 0;
 550 }
 551
 552 static inline int upstream_mark(const char *string, int len)
 553 {
 554         const char *suffix[] = { "@{upstream}", "@{u}" };
 555         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 556 }
 557
 558 static inline int push_mark(const char *string, int len)
 559 {
 560         const char *suffix[] = { "@{push}" };
 561         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 562 }
 563
 564 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 565 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 566
 567 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 568                           unsigned int flags)
 569 {
 570         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 571         static const char *object_name_msg = N_(
 572         "Git normally never creates a ref that ends with 40 hex characters\n"
 573         "because it will be ignored when you just specify 40-hex. These refs\n"
 574         "may be created by mistake. For example,\n"
 575         "\n"
 576         "  git checkout -b $br $(git rev-parse ...)\n"
 577         "\n"
 578         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 579         "examine these refs and maybe delete them. Turn this message off by\n"
 580         "running \"git config advice.objectNameWarning false\"");
 581         unsigned char tmp_sha1[20];
 582         char *real_ref = NULL;
 583         int refs_found = 0;
 584         int at, reflog_len, nth_prior = 0;
 585
 586         if (len == 40 && !get_sha1_hex(str, sha1)) {
 587                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 588                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 589                         if (refs_found > 0) {
 590                                 warning(warn_msg, len, str);
 591                                 if (advice_object_name_warning)
 592                                         fprintf(stderr, "%s\n", _(object_name_msg));
 593                         }
 594                         free(real_ref);
 595                 }
 596                 return 0;
 597         }
 598
 599         /* basic@{time or number or -number} format to query ref-log */
 600         reflog_len = at = 0;
 601         if (len && str[len-1] == '}') {
 602                 for (at = len-4; at >= 0; at--) {
 603                         if (str[at] == '@' && str[at+1] == '{') {
 604                                 if (str[at+2] == '-') {
 605                                         if (at != 0)
 606                                                 /* @{-N} not at start */
 607                                                 return -1;
 608                                         nth_prior = 1;
 609                                         continue;
 610                                 }
 611                                 if (!upstream_mark(str + at, len - at) &&
 612                                     !push_mark(str + at, len - at)) {
 613                                         reflog_len = (len-1) - (at+2);
 614                                         len = at;
 615                                 }
 616                                 break;
 617                         }
 618                 }
 619         }
 620
 621         /* Accept only unambiguous ref paths. */
 622         if (len && ambiguous_path(str, len))
 623                 return -1;
 624
 625         if (nth_prior) {
 626                 struct strbuf buf = STRBUF_INIT;
 627                 int detached;
 628
 629                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 630                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 631                         strbuf_release(&buf);
 632                         if (detached)
 633                                 return 0;
 634                 }
 635         }
 636
 637         if (!len && reflog_len)
 638                 /* allow "@{...}" to mean the current branch reflog */
 639                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 640         else if (reflog_len)
 641                 refs_found = dwim_log(str, len, sha1, &real_ref);
 642         else
 643                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 644
 645         if (!refs_found)
 646                 return -1;
 647
 648         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 649             (refs_found > 1 ||
 650              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 651                 warning(warn_msg, len, str);
 652
 653         if (reflog_len) {
 654                 int nth, i;
 655                 unsigned long at_time;
 656                 unsigned long co_time;
 657                 int co_tz, co_cnt;
 658
 659                 /* Is it asking for N-th entry, or approxidate? */
 660                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 661                         char ch = str[at+2+i];
 662                         if ('0' <= ch && ch <= '9')
 663                                 nth = nth * 10 + ch - '0';
 664                         else
 665                                 nth = -1;
 666                 }
 667                 if (100000000 <= nth) {
 668                         at_time = nth;
 669                         nth = -1;
 670                 } else if (0 <= nth)
 671                         at_time = 0;
 672                 else {
 673                         int errors = 0;
 674                         char *tmp = xstrndup(str + at + 2, reflog_len);
 675                         at_time = approxidate_careful(tmp, &errors);
 676                         free(tmp);
 677                         if (errors) {
 678                                 free(real_ref);
 679                                 return -1;
 680                         }
 681                 }
 682                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 683                                 &co_time, &co_tz, &co_cnt)) {
 684                         if (!len) {
 685                                 if (starts_with(real_ref, "refs/heads/")) {
 686                                         str = real_ref + 11;
 687                                         len = strlen(real_ref + 11);
 688                                 } else {
 689                                         /* detached HEAD */
 690                                         str = "HEAD";
 691                                         len = 4;
 692                                 }
 693                         }
 694                         if (at_time) {
 695                                 if (!(flags & GET_SHA1_QUIETLY)) {
 696                                         warning("Log for '%.*s' only goes "
 697                                                 "back to %s.", len, str,
 698                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 699                                 }
 700                         } else {
 701                                 if (flags & GET_SHA1_QUIETLY) {
 702                                         exit(128);
 703                                 }
 704                                 die("Log for '%.*s' only has %d entries.",
 705                                     len, str, co_cnt);
 706                         }
 707                 }
 708         }
 709
 710         free(real_ref);
 711         return 0;
 712 }
 713
 714 static int get_parent(const char *name, int len,
 715                       unsigned char *result, int idx)
 716 {
 717         unsigned char sha1[20];
 718         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 719         struct commit *commit;
 720         struct commit_list *p;
 721
 722         if (ret)
 723                 return ret;
 724         commit = lookup_commit_reference(sha1);
 725         if (parse_commit(commit))
 726                 return -1;
 727         if (!idx) {
 728                 hashcpy(result, commit->object.oid.hash);
 729                 return 0;
 730         }
 731         p = commit->parents;
 732         while (p) {
 733                 if (!--idx) {
 734                         hashcpy(result, p->item->object.oid.hash);
 735                         return 0;
 736                 }
 737                 p = p->next;
 738         }
 739         return -1;
 740 }
 741
 742 static int get_nth_ancestor(const char *name, int len,
 743                             unsigned char *result, int generation)
 744 {
 745         unsigned char sha1[20];
 746         struct commit *commit;
 747         int ret;
 748
 749         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 750         if (ret)
 751                 return ret;
 752         commit = lookup_commit_reference(sha1);
 753         if (!commit)
 754                 return -1;
 755
 756         while (generation--) {
 757                 if (parse_commit(commit) || !commit->parents)
 758                         return -1;
 759                 commit = commit->parents->item;
 760         }
 761         hashcpy(result, commit->object.oid.hash);
 762         return 0;
 763 }
 764
 765 struct object *peel_to_type(const char *name, int namelen,
 766                             struct object *o, enum object_type expected_type)
 767 {
 768         if (name && !namelen)
 769                 namelen = strlen(name);
 770         while (1) {
 771                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 772                         return NULL;
 773                 if (expected_type == OBJ_ANY || o->type == expected_type)
 774                         return o;
 775                 if (o->type == OBJ_TAG)
 776                         o = ((struct tag*) o)->tagged;
 777                 else if (o->type == OBJ_COMMIT)
 778                         o = &(((struct commit *) o)->tree->object);
 779                 else {
 780                         if (name)
 781                                 error("%.*s: expected %s type, but the object "
 782                                       "dereferences to %s type",
 783                                       namelen, name, typename(expected_type),
 784                                       typename(o->type));
 785                         return NULL;
 786                 }
 787         }
 788 }
 789
 790 static int peel_onion(const char *name, int len, unsigned char *sha1,
 791                       unsigned lookup_flags)
 792 {
 793         unsigned char outer[20];
 794         const char *sp;
 795         unsigned int expected_type = 0;
 796         struct object *o;
 797
 798         /*
 799          * "ref^{type}" dereferences ref repeatedly until you cannot
 800          * dereference anymore, or you get an object of given type,
 801          * whichever comes first.  "ref^{}" means just dereference
 802          * tags until you get a non-tag.  "ref^0" is a shorthand for
 803          * "ref^{commit}".  "commit^{tree}" could be used to find the
 804          * top-level tree of the given commit.
 805          */
 806         if (len < 4 || name[len-1] != '}')
 807                 return -1;
 808
 809         for (sp = name + len - 1; name <= sp; sp--) {
 810                 int ch = *sp;
 811                 if (ch == '{' && name < sp && sp[-1] == '^')
 812                         break;
 813         }
 814         if (sp <= name)
 815                 return -1;
 816
 817         sp++; /* beginning of type name, or closing brace for empty */
 818         if (starts_with(sp, "commit}"))
 819                 expected_type = OBJ_COMMIT;
 820         else if (starts_with(sp, "tag}"))
 821                 expected_type = OBJ_TAG;
 822         else if (starts_with(sp, "tree}"))
 823                 expected_type = OBJ_TREE;
 824         else if (starts_with(sp, "blob}"))
 825                 expected_type = OBJ_BLOB;
 826         else if (starts_with(sp, "object}"))
 827                 expected_type = OBJ_ANY;
 828         else if (sp[0] == '}')
 829                 expected_type = OBJ_NONE;
 830         else if (sp[0] == '/')
 831                 expected_type = OBJ_COMMIT;
 832         else
 833                 return -1;
 834
 835         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 836         if (expected_type == OBJ_COMMIT)
 837                 lookup_flags |= GET_SHA1_COMMITTISH;
 838         else if (expected_type == OBJ_TREE)
 839                 lookup_flags |= GET_SHA1_TREEISH;
 840
 841         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 842                 return -1;
 843
 844         o = parse_object(outer);
 845         if (!o)
 846                 return -1;
 847         if (!expected_type) {
 848                 o = deref_tag(o, name, sp - name - 2);
 849                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 850                         return -1;
 851                 hashcpy(sha1, o->oid.hash);
 852                 return 0;
 853         }
 854
 855         /*
 856          * At this point, the syntax look correct, so
 857          * if we do not get the needed object, we should
 858          * barf.
 859          */
 860         o = peel_to_type(name, len, o, expected_type);
 861         if (!o)
 862                 return -1;
 863
 864         hashcpy(sha1, o->oid.hash);
 865         if (sp[0] == '/') {
 866                 /* "$commit^{/foo}" */
 867                 char *prefix;
 868                 int ret;
 869                 struct commit_list *list = NULL;
 870
 871                 /*
 872                  * $commit^{/}. Some regex implementation may reject.
 873                  * We don't need regex anyway. '' pattern always matches.
 874                  */
 875                 if (sp[1] == '}')
 876                         return 0;
 877
 878                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 879                 commit_list_insert((struct commit *)o, &list);
 880                 ret = get_sha1_oneline(prefix, sha1, list);
 881                 free(prefix);
 882                 return ret;
 883         }
 884         return 0;
 885 }
 886
 887 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 888 {
 889         const char *cp;
 890         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 891
 892         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 893                 char ch = *cp;
 894                 if (!isxdigit(ch)) {
 895                         /* We must be looking at g in "SOMETHING-g"
 896                          * for it to be describe output.
 897                          */
 898                         if (ch == 'g' && cp[-1] == '-') {
 899                                 cp++;
 900                                 len -= cp - name;
 901                                 return get_short_sha1(cp, len, sha1, flags);
 902                         }
 903                 }
 904         }
 905         return -1;
 906 }
 907
 908 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 909 {
 910         int ret, has_suffix;
 911         const char *cp;
 912
 913         /*
 914          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 915          */
 916         has_suffix = 0;
 917         for (cp = name + len - 1; name <= cp; cp--) {
 918                 int ch = *cp;
 919                 if ('0' <= ch && ch <= '9')
 920                         continue;
 921                 if (ch == '~' || ch == '^')
 922                         has_suffix = ch;
 923                 break;
 924         }
 925
 926         if (has_suffix) {
 927                 int num = 0;
 928                 int len1 = cp - name;
 929                 cp++;
 930                 while (cp < name + len)
 931                         num = num * 10 + *cp++ - '0';
 932                 if (!num && len1 == len - 1)
 933                         num = 1;
 934                 if (has_suffix == '^')
 935                         return get_parent(name, len1, sha1, num);
 936                 /* else if (has_suffix == '~') -- goes without saying */
 937                 return get_nth_ancestor(name, len1, sha1, num);
 938         }
 939
 940         ret = peel_onion(name, len, sha1, lookup_flags);
 941         if (!ret)
 942                 return 0;
 943
 944         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 945         if (!ret)
 946                 return 0;
 947
 948         /* It could be describe output that is "SOMETHING-gXXXX" */
 949         ret = get_describe_name(name, len, sha1);
 950         if (!ret)
 951                 return 0;
 952
 953         return get_short_sha1(name, len, sha1, lookup_flags);
 954 }
 955
 956 /*
 957  * This interprets names like ':/Initial revision of "git"' by searching
 958  * through history and returning the first commit whose message starts
 959  * the given regular expression.
 960  *
 961  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 962  *
 963  * For a literal '!' character at the beginning of a pattern, you have to repeat
 964  * that, like: ':/!!foo'
 965  *
 966  * For future extension, all other sequences beginning with ':/!' are reserved.
 967  */
 968
 969 /* Remember to update object flag allocation in object.h */
 970 #define ONELINE_SEEN (1u<<20)
 971
 972 static int handle_one_ref(const char *path, const struct object_id *oid,
 973                           int flag, void *cb_data)
 974 {
 975         struct commit_list **list = cb_data;
 976         struct object *object = parse_object(oid->hash);
 977         if (!object)
 978                 return 0;
 979         if (object->type == OBJ_TAG) {
 980                 object = deref_tag(object, path, strlen(path));
 981                 if (!object)
 982                         return 0;
 983         }
 984         if (object->type != OBJ_COMMIT)
 985                 return 0;
 986         commit_list_insert((struct commit *)object, list);
 987         return 0;
 988 }
 989
 990 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 991                             struct commit_list *list)
 992 {
 993         struct commit_list *backup = NULL, *l;
 994         int found = 0;
 995         int negative = 0;
 996         regex_t regex;
 997
 998         if (prefix[0] == '!') {
 999                 prefix++;
1000
1001                 if (prefix[0] == '-') {
1002                         prefix++;
1003                         negative = 1;
1004                 } else if (prefix[0] != '!') {
1005                         return -1;
1006                 }
1007         }
1008
1009         if (regcomp(&regex, prefix, REG_EXTENDED))
1010                 return -1;
1011
1012         for (l = list; l; l = l->next) {
1013                 l->item->object.flags |= ONELINE_SEEN;
1014                 commit_list_insert(l->item, &backup);
1015         }
1016         while (list) {
1017                 const char *p, *buf;
1018                 struct commit *commit;
1019                 int matches;
1020
1021                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1022                 if (!parse_object(commit->object.oid.hash))
1023                         continue;
1024                 buf = get_commit_buffer(commit, NULL);
1025                 p = strstr(buf, "\n\n");
1026                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1027                 unuse_commit_buffer(commit, buf);
1028
1029                 if (matches) {
1030                         hashcpy(sha1, commit->object.oid.hash);
1031                         found = 1;
1032                         break;
1033                 }
1034         }
1035         regfree(&regex);
1036         free_commit_list(list);
1037         for (l = backup; l; l = l->next)
1038                 clear_commit_marks(l->item, ONELINE_SEEN);
1039         free_commit_list(backup);
1040         return found ? 0 : -1;
1041 }
1042
1043 struct grab_nth_branch_switch_cbdata {
1044         int remaining;
1045         struct strbuf buf;
1046 };
1047
1048 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
1049                                   const char *email, unsigned long timestamp, int tz,
1050                                   const char *message, void *cb_data)
1051 {
1052         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1053         const char *match = NULL, *target = NULL;
1054         size_t len;
1055
1056         if (skip_prefix(message, "checkout: moving from ", &match))
1057                 target = strstr(match, " to ");
1058
1059         if (!match || !target)
1060                 return 0;
1061         if (--(cb->remaining) == 0) {
1062                 len = target - match;
1063                 strbuf_reset(&cb->buf);
1064                 strbuf_add(&cb->buf, match, len);
1065                 return 1; /* we are done */
1066         }
1067         return 0;
1068 }
1069
1070 /*
1071  * Parse @{-N} syntax, return the number of characters parsed
1072  * if successful; otherwise signal an error with negative value.
1073  */
1074 static int interpret_nth_prior_checkout(const char *name, int namelen,
1075                                         struct strbuf *buf)
1076 {
1077         long nth;
1078         int retval;
1079         struct grab_nth_branch_switch_cbdata cb;
1080         const char *brace;
1081         char *num_end;
1082
1083         if (namelen < 4)
1084                 return -1;
1085         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1086                 return -1;
1087         brace = memchr(name, '}', namelen);
1088         if (!brace)
1089                 return -1;
1090         nth = strtol(name + 3, &num_end, 10);
1091         if (num_end != brace)
1092                 return -1;
1093         if (nth <= 0)
1094                 return -1;
1095         cb.remaining = nth;
1096         strbuf_init(&cb.buf, 20);
1097
1098         retval = 0;
1099         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1100                 strbuf_reset(buf);
1101                 strbuf_addbuf(buf, &cb.buf);
1102                 retval = brace - name + 1;
1103         }
1104
1105         strbuf_release(&cb.buf);
1106         return retval;
1107 }
1108
1109 int get_oid_mb(const char *name, struct object_id *oid)
1110 {
1111         struct commit *one, *two;
1112         struct commit_list *mbs;
1113         struct object_id oid_tmp;
1114         const char *dots;
1115         int st;
1116
1117         dots = strstr(name, "...");
1118         if (!dots)
1119                 return get_oid(name, oid);
1120         if (dots == name)
1121                 st = get_oid("HEAD", &oid_tmp);
1122         else {
1123                 struct strbuf sb;
1124                 strbuf_init(&sb, dots - name);
1125                 strbuf_add(&sb, name, dots - name);
1126                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1127                 strbuf_release(&sb);
1128         }
1129         if (st)
1130                 return st;
1131         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1132         if (!one)
1133                 return -1;
1134
1135         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1136                 return -1;
1137         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1138         if (!two)
1139                 return -1;
1140         mbs = get_merge_bases(one, two);
1141         if (!mbs || mbs->next)
1142                 st = -1;
1143         else {
1144                 st = 0;
1145                 oidcpy(oid, &mbs->item->object.oid);
1146         }
1147         free_commit_list(mbs);
1148         return st;
1149 }
1150
1151 /* parse @something syntax, when 'something' is not {.*} */
1152 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1153 {
1154         const char *next;
1155
1156         if (len || name[1] == '{')
1157                 return -1;
1158
1159         /* make sure it's a single @, or @@{.*}, not @foo */
1160         next = memchr(name + len + 1, '@', namelen - len - 1);
1161         if (next && next[1] != '{')
1162                 return -1;
1163         if (!next)
1164                 next = name + namelen;
1165         if (next != name + 1)
1166                 return -1;
1167
1168         strbuf_reset(buf);
1169         strbuf_add(buf, "HEAD", 4);
1170         return 1;
1171 }
1172
1173 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1174 {
1175         /* we have extra data, which might need further processing */
1176         struct strbuf tmp = STRBUF_INIT;
1177         int used = buf->len;
1178         int ret;
1179
1180         strbuf_add(buf, name + len, namelen - len);
1181         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1182         /* that data was not interpreted, remove our cruft */
1183         if (ret < 0) {
1184                 strbuf_setlen(buf, used);
1185                 return len;
1186         }
1187         strbuf_reset(buf);
1188         strbuf_addbuf(buf, &tmp);
1189         strbuf_release(&tmp);
1190         /* tweak for size of {-N} versus expanded ref name */
1191         return ret - used + len;
1192 }
1193
1194 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1195 {
1196         char *s = shorten_unambiguous_ref(ref, 0);
1197         strbuf_reset(buf);
1198         strbuf_addstr(buf, s);
1199         free(s);
1200 }
1201
1202 static int interpret_branch_mark(const char *name, int namelen,
1203                                  int at, struct strbuf *buf,
1204                                  int (*get_mark)(const char *, int),
1205                                  const char *(*get_data)(struct branch *,
1206                                                          struct strbuf *))
1207 {
1208         int len;
1209         struct branch *branch;
1210         struct strbuf err = STRBUF_INIT;
1211         const char *value;
1212
1213         len = get_mark(name + at, namelen - at);
1214         if (!len)
1215                 return -1;
1216
1217         if (memchr(name, ':', at))
1218                 return -1;
1219
1220         if (at) {
1221                 char *name_str = xmemdupz(name, at);
1222                 branch = branch_get(name_str);
1223                 free(name_str);
1224         } else
1225                 branch = branch_get(NULL);
1226
1227         value = get_data(branch, &err);
1228         if (!value)
1229                 die("%s", err.buf);
1230
1231         set_shortened_ref(buf, value);
1232         return len + at;
1233 }
1234
1235 /*
1236  * This reads short-hand syntax that not only evaluates to a commit
1237  * object name, but also can act as if the end user spelled the name
1238  * of the branch from the command line.
1239  *
1240  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1241  *   places the name of the branch in the given buf and returns the
1242  *   number of characters parsed if successful.
1243  *
1244  * - "<branch>@{upstream}" finds the name of the other ref that
1245  *   <branch> is configured to merge with (missing <branch> defaults
1246  *   to the current branch), and places the name of the branch in the
1247  *   given buf and returns the number of characters parsed if
1248  *   successful.
1249  *
1250  * If the input is not of the accepted format, it returns a negative
1251  * number to signal an error.
1252  *
1253  * If the input was ok but there are not N branch switches in the
1254  * reflog, it returns 0.
1255  */
1256 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1257 {
1258         char *at;
1259         const char *start;
1260         int len = interpret_nth_prior_checkout(name, namelen, buf);
1261
1262         if (!namelen)
1263                 namelen = strlen(name);
1264
1265         if (!len) {
1266                 return len; /* syntax Ok, not enough switches */
1267         } else if (len > 0) {
1268                 if (len == namelen)
1269                         return len; /* consumed all */
1270                 else
1271                         return reinterpret(name, namelen, len, buf);
1272         }
1273
1274         for (start = name;
1275              (at = memchr(start, '@', namelen - (start - name)));
1276              start = at + 1) {
1277
1278                 len = interpret_empty_at(name, namelen, at - name, buf);
1279                 if (len > 0)
1280                         return reinterpret(name, namelen, len, buf);
1281
1282                 len = interpret_branch_mark(name, namelen, at - name, buf,
1283                                             upstream_mark, branch_get_upstream);
1284                 if (len > 0)
1285                         return len;
1286
1287                 len = interpret_branch_mark(name, namelen, at - name, buf,
1288                                             push_mark, branch_get_push);
1289                 if (len > 0)
1290                         return len;
1291         }
1292
1293         return -1;
1294 }
1295
1296 int strbuf_branchname(struct strbuf *sb, const char *name)
1297 {
1298         int len = strlen(name);
1299         int used = interpret_branch_name(name, len, sb);
1300
1301         if (used == len)
1302                 return 0;
1303         if (used < 0)
1304                 used = 0;
1305         strbuf_add(sb, name + used, len - used);
1306         return len;
1307 }
1308
1309 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1310 {
1311         strbuf_branchname(sb, name);
1312         if (name[0] == '-')
1313                 return -1;
1314         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1315         return check_refname_format(sb->buf, 0);
1316 }
1317
1318 /*
1319  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1320  * notably "xyz^" for "parent of xyz"
1321  */
1322 int get_sha1(const char *name, unsigned char *sha1)
1323 {
1324         struct object_context unused;
1325         return get_sha1_with_context(name, 0, sha1, &unused);
1326 }
1327
1328 /*
1329  * This is like "get_sha1()", but for struct object_id.
1330  */
1331 int get_oid(const char *name, struct object_id *oid)
1332 {
1333         return get_sha1(name, oid->hash);
1334 }
1335
1336
1337 /*
1338  * Many callers know that the user meant to name a commit-ish by
1339  * syntactical positions where the object name appears.  Calling this
1340  * function allows the machinery to disambiguate shorter-than-unique
1341  * abbreviated object names between commit-ish and others.
1342  *
1343  * Note that this does NOT error out when the named object is not a
1344  * commit-ish. It is merely to give a hint to the disambiguation
1345  * machinery.
1346  */
1347 int get_sha1_committish(const char *name, unsigned char *sha1)
1348 {
1349         struct object_context unused;
1350         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1351                                      sha1, &unused);
1352 }
1353
1354 int get_sha1_treeish(const char *name, unsigned char *sha1)
1355 {
1356         struct object_context unused;
1357         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1358                                      sha1, &unused);
1359 }
1360
1361 int get_sha1_commit(const char *name, unsigned char *sha1)
1362 {
1363         struct object_context unused;
1364         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1365                                      sha1, &unused);
1366 }
1367
1368 int get_sha1_tree(const char *name, unsigned char *sha1)
1369 {
1370         struct object_context unused;
1371         return get_sha1_with_context(name, GET_SHA1_TREE,
1372                                      sha1, &unused);
1373 }
1374
1375 int get_sha1_blob(const char *name, unsigned char *sha1)
1376 {
1377         struct object_context unused;
1378         return get_sha1_with_context(name, GET_SHA1_BLOB,
1379                                      sha1, &unused);
1380 }
1381
1382 /* Must be called only when object_name:filename doesn't exist. */
1383 static void diagnose_invalid_sha1_path(const char *prefix,
1384                                        const char *filename,
1385                                        const unsigned char *tree_sha1,
1386                                        const char *object_name,
1387                                        int object_name_len)
1388 {
1389         unsigned char sha1[20];
1390         unsigned mode;
1391
1392         if (!prefix)
1393                 prefix = "";
1394
1395         if (file_exists(filename))
1396                 die("Path '%s' exists on disk, but not in '%.*s'.",
1397                     filename, object_name_len, object_name);
1398         if (errno == ENOENT || errno == ENOTDIR) {
1399                 char *fullname = xstrfmt("%s%s", prefix, filename);
1400
1401                 if (!get_tree_entry(tree_sha1, fullname,
1402                                     sha1, &mode)) {
1403                         die("Path '%s' exists, but not '%s'.\n"
1404                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1405                             fullname,
1406                             filename,
1407                             object_name_len, object_name,
1408                             fullname,
1409                             object_name_len, object_name,
1410                             filename);
1411                 }
1412                 die("Path '%s' does not exist in '%.*s'",
1413                     filename, object_name_len, object_name);
1414         }
1415 }
1416
1417 /* Must be called only when :stage:filename doesn't exist. */
1418 static void diagnose_invalid_index_path(int stage,
1419                                         const char *prefix,
1420                                         const char *filename)
1421 {
1422         const struct cache_entry *ce;
1423         int pos;
1424         unsigned namelen = strlen(filename);
1425         struct strbuf fullname = STRBUF_INIT;
1426
1427         if (!prefix)
1428                 prefix = "";
1429
1430         /* Wrong stage number? */
1431         pos = cache_name_pos(filename, namelen);
1432         if (pos < 0)
1433                 pos = -pos - 1;
1434         if (pos < active_nr) {
1435                 ce = active_cache[pos];
1436                 if (ce_namelen(ce) == namelen &&
1437                     !memcmp(ce->name, filename, namelen))
1438                         die("Path '%s' is in the index, but not at stage %d.\n"
1439                             "Did you mean ':%d:%s'?",
1440                             filename, stage,
1441                             ce_stage(ce), filename);
1442         }
1443
1444         /* Confusion between relative and absolute filenames? */
1445         strbuf_addstr(&fullname, prefix);
1446         strbuf_addstr(&fullname, filename);
1447         pos = cache_name_pos(fullname.buf, fullname.len);
1448         if (pos < 0)
1449                 pos = -pos - 1;
1450         if (pos < active_nr) {
1451                 ce = active_cache[pos];
1452                 if (ce_namelen(ce) == fullname.len &&
1453                     !memcmp(ce->name, fullname.buf, fullname.len))
1454                         die("Path '%s' is in the index, but not '%s'.\n"
1455                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1456                             fullname.buf, filename,
1457                             ce_stage(ce), fullname.buf,
1458                             ce_stage(ce), filename);
1459         }
1460
1461         if (file_exists(filename))
1462                 die("Path '%s' exists on disk, but not in the index.", filename);
1463         if (errno == ENOENT || errno == ENOTDIR)
1464                 die("Path '%s' does not exist (neither on disk nor in the index).",
1465                     filename);
1466
1467         strbuf_release(&fullname);
1468 }
1469
1470
1471 static char *resolve_relative_path(const char *rel)
1472 {
1473         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1474                 return NULL;
1475
1476         if (!is_inside_work_tree())
1477                 die("relative path syntax can't be used outside working tree.");
1478
1479         /* die() inside prefix_path() if resolved path is outside worktree */
1480         return prefix_path(startup_info->prefix,
1481                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1482                            rel);
1483 }
1484
1485 static int get_sha1_with_context_1(const char *name,
1486                                    unsigned flags,
1487                                    const char *prefix,
1488                                    unsigned char *sha1,
1489                                    struct object_context *oc)
1490 {
1491         int ret, bracket_depth;
1492         int namelen = strlen(name);
1493         const char *cp;
1494         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1495
1496         if (only_to_die)
1497                 flags |= GET_SHA1_QUIETLY;
1498
1499         memset(oc, 0, sizeof(*oc));
1500         oc->mode = S_IFINVALID;
1501         ret = get_sha1_1(name, namelen, sha1, flags);
1502         if (!ret)
1503                 return ret;
1504         /*
1505          * sha1:path --> object name of path in ent sha1
1506          * :path -> object name of absolute path in index
1507          * :./path -> object name of path relative to cwd in index
1508          * :[0-3]:path -> object name of path in index at stage
1509          * :/foo -> recent commit matching foo
1510          */
1511         if (name[0] == ':') {
1512                 int stage = 0;
1513                 const struct cache_entry *ce;
1514                 char *new_path = NULL;
1515                 int pos;
1516                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1517                         struct commit_list *list = NULL;
1518
1519                         for_each_ref(handle_one_ref, &list);
1520                         commit_list_sort_by_date(&list);
1521                         return get_sha1_oneline(name + 2, sha1, list);
1522                 }
1523                 if (namelen < 3 ||
1524                     name[2] != ':' ||
1525                     name[1] < '0' || '3' < name[1])
1526                         cp = name + 1;
1527                 else {
1528                         stage = name[1] - '0';
1529                         cp = name + 3;
1530                 }
1531                 new_path = resolve_relative_path(cp);
1532                 if (!new_path) {
1533                         namelen = namelen - (cp - name);
1534                 } else {
1535                         cp = new_path;
1536                         namelen = strlen(cp);
1537                 }
1538
1539                 strlcpy(oc->path, cp, sizeof(oc->path));
1540
1541                 if (!active_cache)
1542                         read_cache();
1543                 pos = cache_name_pos(cp, namelen);
1544                 if (pos < 0)
1545                         pos = -pos - 1;
1546                 while (pos < active_nr) {
1547                         ce = active_cache[pos];
1548                         if (ce_namelen(ce) != namelen ||
1549                             memcmp(ce->name, cp, namelen))
1550                                 break;
1551                         if (ce_stage(ce) == stage) {
1552                                 hashcpy(sha1, ce->oid.hash);
1553                                 oc->mode = ce->ce_mode;
1554                                 free(new_path);
1555                                 return 0;
1556                         }
1557                         pos++;
1558                 }
1559                 if (only_to_die && name[1] && name[1] != '/')
1560                         diagnose_invalid_index_path(stage, prefix, cp);
1561                 free(new_path);
1562                 return -1;
1563         }
1564         for (cp = name, bracket_depth = 0; *cp; cp++) {
1565                 if (*cp == '{')
1566                         bracket_depth++;
1567                 else if (bracket_depth && *cp == '}')
1568                         bracket_depth--;
1569                 else if (!bracket_depth && *cp == ':')
1570                         break;
1571         }
1572         if (*cp == ':') {
1573                 unsigned char tree_sha1[20];
1574                 int len = cp - name;
1575                 unsigned sub_flags = flags;
1576
1577                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1578                 sub_flags |= GET_SHA1_TREEISH;
1579
1580                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1581                         const char *filename = cp+1;
1582                         char *new_filename = NULL;
1583
1584                         new_filename = resolve_relative_path(filename);
1585                         if (new_filename)
1586                                 filename = new_filename;
1587                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1588                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1589                                         filename, sha1, &oc->symlink_path,
1590                                         &oc->mode);
1591                         } else {
1592                                 ret = get_tree_entry(tree_sha1, filename,
1593                                                      sha1, &oc->mode);
1594                                 if (ret && only_to_die) {
1595                                         diagnose_invalid_sha1_path(prefix,
1596                                                                    filename,
1597                                                                    tree_sha1,
1598                                                                    name, len);
1599                                 }
1600                         }
1601                         hashcpy(oc->tree, tree_sha1);
1602                         strlcpy(oc->path, filename, sizeof(oc->path));
1603
1604                         free(new_filename);
1605                         return ret;
1606                 } else {
1607                         if (only_to_die)
1608                                 die("Invalid object name '%.*s'.", len, name);
1609                 }
1610         }
1611         return ret;
1612 }
1613
1614 /*
1615  * Call this function when you know "name" given by the end user must
1616  * name an object but it doesn't; the function _may_ die with a better
1617  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1618  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1619  * you have a chance to diagnose the error further.
1620  */
1621 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1622 {
1623         struct object_context oc;
1624         unsigned char sha1[20];
1625         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1626 }
1627
1628 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1629 {
1630         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1631                 die("BUG: incompatible flags for get_sha1_with_context");
1632         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1633 }