sha1_name.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "tag.h"
   4 #include "commit.h"
   5 #include "tree.h"
   6 #include "blob.h"
   7 #include "tree-walk.h"
   8 #include "refs.h"
   9 #include "remote.h"
  10 #include "dir.h"
  11 #include "sha1-array.h"
  12
  13 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  14
  15 typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
  16
  17 struct disambiguate_state {
  18         int len; /* length of prefix in hex chars */
  19         char hex_pfx[GIT_MAX_HEXSZ + 1];
  20         struct object_id bin_pfx;
  21
  22         disambiguate_hint_fn fn;
  23         void *cb_data;
  24         struct object_id candidate;
  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 struct object_id *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                 oidcpy(&ds->candidate, current);
  42                 ds->candidate_exists = 1;
  43                 return;
  44         } else if (!oidcmp(&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                 oidcpy(&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 int append_loose_object(const struct object_id *oid, const char *path,
  82                                void *data)
  83 {
  84         oid_array_append(data, oid);
  85         return 0;
  86 }
  87
  88 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  89
  90 static void find_short_object_filename(struct disambiguate_state *ds)
  91 {
  92         int subdir_nr = ds->bin_pfx.hash[0];
  93         struct alternate_object_database *alt;
  94         static struct alternate_object_database *fakeent;
  95
  96         if (!fakeent) {
  97                 /*
  98                  * Create a "fake" alternate object database that
  99                  * points to our own object database, to make it
 100                  * easier to get a temporary working space in
 101                  * alt->name/alt->base while iterating over the
 102                  * object databases including our own.
 103                  */
 104                 fakeent = alloc_alt_odb(get_object_directory());
 105         }
 106         fakeent->next = alt_odb_list;
 107
 108         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 109                 int pos;
 110
 111                 if (!alt->loose_objects_subdir_seen[subdir_nr]) {
 112                         struct strbuf *buf = alt_scratch_buf(alt);
 113                         for_each_file_in_obj_subdir(subdir_nr, buf,
 114                                                     append_loose_object,
 115                                                     NULL, NULL,
 116                                                     &alt->loose_objects_cache);
 117                         alt->loose_objects_subdir_seen[subdir_nr] = 1;
 118                 }
 119
 120                 pos = oid_array_lookup(&alt->loose_objects_cache, &ds->bin_pfx);
 121                 if (pos < 0)
 122                         pos = -1 - pos;
 123                 while (!ds->ambiguous && pos < alt->loose_objects_cache.nr) {
 124                         const struct object_id *oid;
 125                         oid = alt->loose_objects_cache.oid + pos;
 126                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 127                                 break;
 128                         update_candidates(ds, oid);
 129                         pos++;
 130                 }
 131         }
 132 }
 133
 134 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 135 {
 136         do {
 137                 if (*a != *b)
 138                         return 0;
 139                 a++;
 140                 b++;
 141                 len -= 2;
 142         } while (len > 1);
 143         if (len)
 144                 if ((*a ^ *b) & 0xf0)
 145                         return 0;
 146         return 1;
 147 }
 148
 149 static void unique_in_pack(struct packed_git *p,
 150                            struct disambiguate_state *ds)
 151 {
 152         uint32_t num, last, i, first = 0;
 153         const struct object_id *current = NULL;
 154
 155         open_pack_index(p);
 156         num = p->num_objects;
 157         last = num;
 158         while (first < last) {
 159                 uint32_t mid = (first + last) / 2;
 160                 const unsigned char *current;
 161                 int cmp;
 162
 163                 current = nth_packed_object_sha1(p, mid);
 164                 cmp = hashcmp(ds->bin_pfx.hash, current);
 165                 if (!cmp) {
 166                         first = mid;
 167                         break;
 168                 }
 169                 if (cmp > 0) {
 170                         first = mid+1;
 171                         continue;
 172                 }
 173                 last = mid;
 174         }
 175
 176         /*
 177          * At this point, "first" is the location of the lowest object
 178          * with an object name that could match "bin_pfx".  See if we have
 179          * 0, 1 or more objects that actually match(es).
 180          */
 181         for (i = first; i < num && !ds->ambiguous; i++) {
 182                 struct object_id oid;
 183                 current = nth_packed_object_oid(&oid, p, i);
 184                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 185                         break;
 186                 update_candidates(ds, current);
 187         }
 188 }
 189
 190 static void find_short_packed_object(struct disambiguate_state *ds)
 191 {
 192         struct packed_git *p;
 193
 194         prepare_packed_git();
 195         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 196                 unique_in_pack(p, ds);
 197 }
 198
 199 #define SHORT_NAME_NOT_FOUND (-1)
 200 #define SHORT_NAME_AMBIGUOUS (-2)
 201
 202 static int finish_object_disambiguation(struct disambiguate_state *ds,
 203                                         unsigned char *sha1)
 204 {
 205         if (ds->ambiguous)
 206                 return SHORT_NAME_AMBIGUOUS;
 207
 208         if (!ds->candidate_exists)
 209                 return SHORT_NAME_NOT_FOUND;
 210
 211         if (!ds->candidate_checked)
 212                 /*
 213                  * If this is the only candidate, there is no point
 214                  * calling the disambiguation hint callback.
 215                  *
 216                  * On the other hand, if the current candidate
 217                  * replaced an earlier candidate that did _not_ pass
 218                  * the disambiguation hint callback, then we do have
 219                  * more than one objects that match the short name
 220                  * given, so we should make sure this one matches;
 221                  * otherwise, if we discovered this one and the one
 222                  * that we previously discarded in the reverse order,
 223                  * we would end up showing different results in the
 224                  * same repository!
 225                  */
 226                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 227                                     ds->fn(&ds->candidate, ds->cb_data));
 228
 229         if (!ds->candidate_ok)
 230                 return SHORT_NAME_AMBIGUOUS;
 231
 232         hashcpy(sha1, ds->candidate.hash);
 233         return 0;
 234 }
 235
 236 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 237 {
 238         int kind = sha1_object_info(oid->hash, NULL);
 239         return kind == OBJ_COMMIT;
 240 }
 241
 242 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 243 {
 244         struct object *obj;
 245         int kind;
 246
 247         kind = sha1_object_info(oid->hash, NULL);
 248         if (kind == OBJ_COMMIT)
 249                 return 1;
 250         if (kind != OBJ_TAG)
 251                 return 0;
 252
 253         /* We need to do this the hard way... */
 254         obj = deref_tag(parse_object(oid), NULL, 0);
 255         if (obj && obj->type == OBJ_COMMIT)
 256                 return 1;
 257         return 0;
 258 }
 259
 260 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 261 {
 262         int kind = sha1_object_info(oid->hash, NULL);
 263         return kind == OBJ_TREE;
 264 }
 265
 266 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 267 {
 268         struct object *obj;
 269         int kind;
 270
 271         kind = sha1_object_info(oid->hash, NULL);
 272         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 273                 return 1;
 274         if (kind != OBJ_TAG)
 275                 return 0;
 276
 277         /* We need to do this the hard way... */
 278         obj = deref_tag(parse_object(oid), NULL, 0);
 279         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 280                 return 1;
 281         return 0;
 282 }
 283
 284 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 285 {
 286         int kind = sha1_object_info(oid->hash, NULL);
 287         return kind == OBJ_BLOB;
 288 }
 289
 290 static disambiguate_hint_fn default_disambiguate_hint;
 291
 292 int set_disambiguate_hint_config(const char *var, const char *value)
 293 {
 294         static const struct {
 295                 const char *name;
 296                 disambiguate_hint_fn fn;
 297         } hints[] = {
 298                 { "none", NULL },
 299                 { "commit", disambiguate_commit_only },
 300                 { "committish", disambiguate_committish_only },
 301                 { "tree", disambiguate_tree_only },
 302                 { "treeish", disambiguate_treeish_only },
 303                 { "blob", disambiguate_blob_only }
 304         };
 305         int i;
 306
 307         if (!value)
 308                 return config_error_nonbool(var);
 309
 310         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 311                 if (!strcasecmp(value, hints[i].name)) {
 312                         default_disambiguate_hint = hints[i].fn;
 313                         return 0;
 314                 }
 315         }
 316
 317         return error("unknown hint type for '%s': %s", var, value);
 318 }
 319
 320 static int init_object_disambiguation(const char *name, int len,
 321                                       struct disambiguate_state *ds)
 322 {
 323         int i;
 324
 325         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 326                 return -1;
 327
 328         memset(ds, 0, sizeof(*ds));
 329
 330         for (i = 0; i < len ;i++) {
 331                 unsigned char c = name[i];
 332                 unsigned char val;
 333                 if (c >= '0' && c <= '9')
 334                         val = c - '0';
 335                 else if (c >= 'a' && c <= 'f')
 336                         val = c - 'a' + 10;
 337                 else if (c >= 'A' && c <='F') {
 338                         val = c - 'A' + 10;
 339                         c -= 'A' - 'a';
 340                 }
 341                 else
 342                         return -1;
 343                 ds->hex_pfx[i] = c;
 344                 if (!(i & 1))
 345                         val <<= 4;
 346                 ds->bin_pfx.hash[i >> 1] |= val;
 347         }
 348
 349         ds->len = len;
 350         ds->hex_pfx[len] = '\0';
 351         prepare_alt_odb();
 352         return 0;
 353 }
 354
 355 static int show_ambiguous_object(const struct object_id *oid, void *data)
 356 {
 357         const struct disambiguate_state *ds = data;
 358         struct strbuf desc = STRBUF_INIT;
 359         int type;
 360
 361
 362         if (ds->fn && !ds->fn(oid, ds->cb_data))
 363                 return 0;
 364
 365         type = sha1_object_info(oid->hash, NULL);
 366         if (type == OBJ_COMMIT) {
 367                 struct commit *commit = lookup_commit(oid);
 368                 if (commit) {
 369                         struct pretty_print_context pp = {0};
 370                         pp.date_mode.type = DATE_SHORT;
 371                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 372                 }
 373         } else if (type == OBJ_TAG) {
 374                 struct tag *tag = lookup_tag(oid);
 375                 if (!parse_tag(tag) && tag->tag)
 376                         strbuf_addf(&desc, " %s", tag->tag);
 377         }
 378
 379         advise("  %s %s%s",
 380                find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
 381                typename(type) ? typename(type) : "unknown type",
 382                desc.buf);
 383
 384         strbuf_release(&desc);
 385         return 0;
 386 }
 387
 388 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 389                           unsigned flags)
 390 {
 391         int status;
 392         struct disambiguate_state ds;
 393         int quietly = !!(flags & GET_SHA1_QUIETLY);
 394
 395         if (init_object_disambiguation(name, len, &ds) < 0)
 396                 return -1;
 397
 398         if (HAS_MULTI_BITS(flags & GET_SHA1_DISAMBIGUATORS))
 399                 die("BUG: multiple get_short_sha1 disambiguator flags");
 400
 401         if (flags & GET_SHA1_COMMIT)
 402                 ds.fn = disambiguate_commit_only;
 403         else if (flags & GET_SHA1_COMMITTISH)
 404                 ds.fn = disambiguate_committish_only;
 405         else if (flags & GET_SHA1_TREE)
 406                 ds.fn = disambiguate_tree_only;
 407         else if (flags & GET_SHA1_TREEISH)
 408                 ds.fn = disambiguate_treeish_only;
 409         else if (flags & GET_SHA1_BLOB)
 410                 ds.fn = disambiguate_blob_only;
 411         else
 412                 ds.fn = default_disambiguate_hint;
 413
 414         find_short_object_filename(&ds);
 415         find_short_packed_object(&ds);
 416         status = finish_object_disambiguation(&ds, sha1);
 417
 418         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 419                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 420
 421                 /*
 422                  * We may still have ambiguity if we simply saw a series of
 423                  * candidates that did not satisfy our hint function. In
 424                  * that case, we still want to show them, so disable the hint
 425                  * function entirely.
 426                  */
 427                 if (!ds.ambiguous)
 428                         ds.fn = NULL;
 429
 430                 advise(_("The candidates are:"));
 431                 for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
 432         }
 433
 434         return status;
 435 }
 436
 437 static int collect_ambiguous(const struct object_id *oid, void *data)
 438 {
 439         oid_array_append(data, oid);
 440         return 0;
 441 }
 442
 443 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 444 {
 445         struct oid_array collect = OID_ARRAY_INIT;
 446         struct disambiguate_state ds;
 447         int ret;
 448
 449         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 450                 return -1;
 451
 452         ds.always_call_fn = 1;
 453         ds.fn = collect_ambiguous;
 454         ds.cb_data = &collect;
 455         find_short_object_filename(&ds);
 456         find_short_packed_object(&ds);
 457
 458         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 459         oid_array_clear(&collect);
 460         return ret;
 461 }
 462
 463 /*
 464  * Return the slot of the most-significant bit set in "val". There are various
 465  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 466  * probably not a big deal here.
 467  */
 468 static unsigned msb(unsigned long val)
 469 {
 470         unsigned r = 0;
 471         while (val >>= 1)
 472                 r++;
 473         return r;
 474 }
 475
 476 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 477 {
 478         int status, exists;
 479
 480         if (len < 0) {
 481                 unsigned long count = approximate_object_count();
 482                 /*
 483                  * Add one because the MSB only tells us the highest bit set,
 484                  * not including the value of all the _other_ bits (so "15"
 485                  * is only one off of 2^4, but the MSB is the 3rd bit.
 486                  */
 487                 len = msb(count) + 1;
 488                 /*
 489                  * We now know we have on the order of 2^len objects, which
 490                  * expects a collision at 2^(len/2). But we also care about hex
 491                  * chars, not bits, and there are 4 bits per hex. So all
 492                  * together we need to divide by 2; but we also want to round
 493                  * odd numbers up, hence adding one before dividing.
 494                  */
 495                 len = (len + 1) / 2;
 496                 /*
 497                  * For very small repos, we stick with our regular fallback.
 498                  */
 499                 if (len < FALLBACK_DEFAULT_ABBREV)
 500                         len = FALLBACK_DEFAULT_ABBREV;
 501         }
 502
 503         sha1_to_hex_r(hex, sha1);
 504         if (len == 40 || !len)
 505                 return 40;
 506         exists = has_sha1_file(sha1);
 507         while (len < 40) {
 508                 unsigned char sha1_ret[20];
 509                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 510                 if (exists
 511                     ? !status
 512                     : status == SHORT_NAME_NOT_FOUND) {
 513                         hex[len] = 0;
 514                         return len;
 515                 }
 516                 len++;
 517         }
 518         return len;
 519 }
 520
 521 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 522 {
 523         static int bufno;
 524         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 525         char *hex = hexbuffer[bufno];
 526         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 527         find_unique_abbrev_r(hex, sha1, len);
 528         return hex;
 529 }
 530
 531 static int ambiguous_path(const char *path, int len)
 532 {
 533         int slash = 1;
 534         int cnt;
 535
 536         for (cnt = 0; cnt < len; cnt++) {
 537                 switch (*path++) {
 538                 case '\0':
 539                         break;
 540                 case '/':
 541                         if (slash)
 542                                 break;
 543                         slash = 1;
 544                         continue;
 545                 case '.':
 546                         continue;
 547                 default:
 548                         slash = 0;
 549                         continue;
 550                 }
 551                 break;
 552         }
 553         return slash;
 554 }
 555
 556 static inline int at_mark(const char *string, int len,
 557                           const char **suffix, int nr)
 558 {
 559         int i;
 560
 561         for (i = 0; i < nr; i++) {
 562                 int suffix_len = strlen(suffix[i]);
 563                 if (suffix_len <= len
 564                     && !strncasecmp(string, suffix[i], suffix_len))
 565                         return suffix_len;
 566         }
 567         return 0;
 568 }
 569
 570 static inline int upstream_mark(const char *string, int len)
 571 {
 572         const char *suffix[] = { "@{upstream}", "@{u}" };
 573         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 574 }
 575
 576 static inline int push_mark(const char *string, int len)
 577 {
 578         const char *suffix[] = { "@{push}" };
 579         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 580 }
 581
 582 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 583 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 584
 585 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 586                           unsigned int flags)
 587 {
 588         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 589         static const char *object_name_msg = N_(
 590         "Git normally never creates a ref that ends with 40 hex characters\n"
 591         "because it will be ignored when you just specify 40-hex. These refs\n"
 592         "may be created by mistake. For example,\n"
 593         "\n"
 594         "  git checkout -b $br $(git rev-parse ...)\n"
 595         "\n"
 596         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 597         "examine these refs and maybe delete them. Turn this message off by\n"
 598         "running \"git config advice.objectNameWarning false\"");
 599         unsigned char tmp_sha1[20];
 600         char *real_ref = NULL;
 601         int refs_found = 0;
 602         int at, reflog_len, nth_prior = 0;
 603
 604         if (len == 40 && !get_sha1_hex(str, sha1)) {
 605                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 606                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 607                         if (refs_found > 0) {
 608                                 warning(warn_msg, len, str);
 609                                 if (advice_object_name_warning)
 610                                         fprintf(stderr, "%s\n", _(object_name_msg));
 611                         }
 612                         free(real_ref);
 613                 }
 614                 return 0;
 615         }
 616
 617         /* basic@{time or number or -number} format to query ref-log */
 618         reflog_len = at = 0;
 619         if (len && str[len-1] == '}') {
 620                 for (at = len-4; at >= 0; at--) {
 621                         if (str[at] == '@' && str[at+1] == '{') {
 622                                 if (str[at+2] == '-') {
 623                                         if (at != 0)
 624                                                 /* @{-N} not at start */
 625                                                 return -1;
 626                                         nth_prior = 1;
 627                                         continue;
 628                                 }
 629                                 if (!upstream_mark(str + at, len - at) &&
 630                                     !push_mark(str + at, len - at)) {
 631                                         reflog_len = (len-1) - (at+2);
 632                                         len = at;
 633                                 }
 634                                 break;
 635                         }
 636                 }
 637         }
 638
 639         /* Accept only unambiguous ref paths. */
 640         if (len && ambiguous_path(str, len))
 641                 return -1;
 642
 643         if (nth_prior) {
 644                 struct strbuf buf = STRBUF_INIT;
 645                 int detached;
 646
 647                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 648                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 649                         strbuf_release(&buf);
 650                         if (detached)
 651                                 return 0;
 652                 }
 653         }
 654
 655         if (!len && reflog_len)
 656                 /* allow "@{...}" to mean the current branch reflog */
 657                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 658         else if (reflog_len)
 659                 refs_found = dwim_log(str, len, sha1, &real_ref);
 660         else
 661                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 662
 663         if (!refs_found)
 664                 return -1;
 665
 666         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 667             (refs_found > 1 ||
 668              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 669                 warning(warn_msg, len, str);
 670
 671         if (reflog_len) {
 672                 int nth, i;
 673                 timestamp_t at_time;
 674                 timestamp_t co_time;
 675                 int co_tz, co_cnt;
 676
 677                 /* Is it asking for N-th entry, or approxidate? */
 678                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 679                         char ch = str[at+2+i];
 680                         if ('0' <= ch && ch <= '9')
 681                                 nth = nth * 10 + ch - '0';
 682                         else
 683                                 nth = -1;
 684                 }
 685                 if (100000000 <= nth) {
 686                         at_time = nth;
 687                         nth = -1;
 688                 } else if (0 <= nth)
 689                         at_time = 0;
 690                 else {
 691                         int errors = 0;
 692                         char *tmp = xstrndup(str + at + 2, reflog_len);
 693                         at_time = approxidate_careful(tmp, &errors);
 694                         free(tmp);
 695                         if (errors) {
 696                                 free(real_ref);
 697                                 return -1;
 698                         }
 699                 }
 700                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 701                                 &co_time, &co_tz, &co_cnt)) {
 702                         if (!len) {
 703                                 if (starts_with(real_ref, "refs/heads/")) {
 704                                         str = real_ref + 11;
 705                                         len = strlen(real_ref + 11);
 706                                 } else {
 707                                         /* detached HEAD */
 708                                         str = "HEAD";
 709                                         len = 4;
 710                                 }
 711                         }
 712                         if (at_time) {
 713                                 if (!(flags & GET_SHA1_QUIETLY)) {
 714                                         warning("Log for '%.*s' only goes "
 715                                                 "back to %s.", len, str,
 716                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 717                                 }
 718                         } else {
 719                                 if (flags & GET_SHA1_QUIETLY) {
 720                                         exit(128);
 721                                 }
 722                                 die("Log for '%.*s' only has %d entries.",
 723                                     len, str, co_cnt);
 724                         }
 725                 }
 726         }
 727
 728         free(real_ref);
 729         return 0;
 730 }
 731
 732 static int get_parent(const char *name, int len,
 733                       unsigned char *result, int idx)
 734 {
 735         struct object_id oid;
 736         int ret = get_sha1_1(name, len, oid.hash, GET_SHA1_COMMITTISH);
 737         struct commit *commit;
 738         struct commit_list *p;
 739
 740         if (ret)
 741                 return ret;
 742         commit = lookup_commit_reference(&oid);
 743         if (parse_commit(commit))
 744                 return -1;
 745         if (!idx) {
 746                 hashcpy(result, commit->object.oid.hash);
 747                 return 0;
 748         }
 749         p = commit->parents;
 750         while (p) {
 751                 if (!--idx) {
 752                         hashcpy(result, p->item->object.oid.hash);
 753                         return 0;
 754                 }
 755                 p = p->next;
 756         }
 757         return -1;
 758 }
 759
 760 static int get_nth_ancestor(const char *name, int len,
 761                             unsigned char *result, int generation)
 762 {
 763         struct object_id oid;
 764         struct commit *commit;
 765         int ret;
 766
 767         ret = get_sha1_1(name, len, oid.hash, GET_SHA1_COMMITTISH);
 768         if (ret)
 769                 return ret;
 770         commit = lookup_commit_reference(&oid);
 771         if (!commit)
 772                 return -1;
 773
 774         while (generation--) {
 775                 if (parse_commit(commit) || !commit->parents)
 776                         return -1;
 777                 commit = commit->parents->item;
 778         }
 779         hashcpy(result, commit->object.oid.hash);
 780         return 0;
 781 }
 782
 783 struct object *peel_to_type(const char *name, int namelen,
 784                             struct object *o, enum object_type expected_type)
 785 {
 786         if (name && !namelen)
 787                 namelen = strlen(name);
 788         while (1) {
 789                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 790                         return NULL;
 791                 if (expected_type == OBJ_ANY || o->type == expected_type)
 792                         return o;
 793                 if (o->type == OBJ_TAG)
 794                         o = ((struct tag*) o)->tagged;
 795                 else if (o->type == OBJ_COMMIT)
 796                         o = &(((struct commit *) o)->tree->object);
 797                 else {
 798                         if (name)
 799                                 error("%.*s: expected %s type, but the object "
 800                                       "dereferences to %s type",
 801                                       namelen, name, typename(expected_type),
 802                                       typename(o->type));
 803                         return NULL;
 804                 }
 805         }
 806 }
 807
 808 static int peel_onion(const char *name, int len, unsigned char *sha1,
 809                       unsigned lookup_flags)
 810 {
 811         struct object_id outer;
 812         const char *sp;
 813         unsigned int expected_type = 0;
 814         struct object *o;
 815
 816         /*
 817          * "ref^{type}" dereferences ref repeatedly until you cannot
 818          * dereference anymore, or you get an object of given type,
 819          * whichever comes first.  "ref^{}" means just dereference
 820          * tags until you get a non-tag.  "ref^0" is a shorthand for
 821          * "ref^{commit}".  "commit^{tree}" could be used to find the
 822          * top-level tree of the given commit.
 823          */
 824         if (len < 4 || name[len-1] != '}')
 825                 return -1;
 826
 827         for (sp = name + len - 1; name <= sp; sp--) {
 828                 int ch = *sp;
 829                 if (ch == '{' && name < sp && sp[-1] == '^')
 830                         break;
 831         }
 832         if (sp <= name)
 833                 return -1;
 834
 835         sp++; /* beginning of type name, or closing brace for empty */
 836         if (starts_with(sp, "commit}"))
 837                 expected_type = OBJ_COMMIT;
 838         else if (starts_with(sp, "tag}"))
 839                 expected_type = OBJ_TAG;
 840         else if (starts_with(sp, "tree}"))
 841                 expected_type = OBJ_TREE;
 842         else if (starts_with(sp, "blob}"))
 843                 expected_type = OBJ_BLOB;
 844         else if (starts_with(sp, "object}"))
 845                 expected_type = OBJ_ANY;
 846         else if (sp[0] == '}')
 847                 expected_type = OBJ_NONE;
 848         else if (sp[0] == '/')
 849                 expected_type = OBJ_COMMIT;
 850         else
 851                 return -1;
 852
 853         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 854         if (expected_type == OBJ_COMMIT)
 855                 lookup_flags |= GET_SHA1_COMMITTISH;
 856         else if (expected_type == OBJ_TREE)
 857                 lookup_flags |= GET_SHA1_TREEISH;
 858
 859         if (get_sha1_1(name, sp - name - 2, outer.hash, lookup_flags))
 860                 return -1;
 861
 862         o = parse_object(&outer);
 863         if (!o)
 864                 return -1;
 865         if (!expected_type) {
 866                 o = deref_tag(o, name, sp - name - 2);
 867                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 868                         return -1;
 869                 hashcpy(sha1, o->oid.hash);
 870                 return 0;
 871         }
 872
 873         /*
 874          * At this point, the syntax look correct, so
 875          * if we do not get the needed object, we should
 876          * barf.
 877          */
 878         o = peel_to_type(name, len, o, expected_type);
 879         if (!o)
 880                 return -1;
 881
 882         hashcpy(sha1, o->oid.hash);
 883         if (sp[0] == '/') {
 884                 /* "$commit^{/foo}" */
 885                 char *prefix;
 886                 int ret;
 887                 struct commit_list *list = NULL;
 888
 889                 /*
 890                  * $commit^{/}. Some regex implementation may reject.
 891                  * We don't need regex anyway. '' pattern always matches.
 892                  */
 893                 if (sp[1] == '}')
 894                         return 0;
 895
 896                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 897                 commit_list_insert((struct commit *)o, &list);
 898                 ret = get_sha1_oneline(prefix, sha1, list);
 899                 free(prefix);
 900                 return ret;
 901         }
 902         return 0;
 903 }
 904
 905 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 906 {
 907         const char *cp;
 908         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 909
 910         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 911                 char ch = *cp;
 912                 if (!isxdigit(ch)) {
 913                         /* We must be looking at g in "SOMETHING-g"
 914                          * for it to be describe output.
 915                          */
 916                         if (ch == 'g' && cp[-1] == '-') {
 917                                 cp++;
 918                                 len -= cp - name;
 919                                 return get_short_sha1(cp, len, sha1, flags);
 920                         }
 921                 }
 922         }
 923         return -1;
 924 }
 925
 926 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 927 {
 928         int ret, has_suffix;
 929         const char *cp;
 930
 931         /*
 932          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 933          */
 934         has_suffix = 0;
 935         for (cp = name + len - 1; name <= cp; cp--) {
 936                 int ch = *cp;
 937                 if ('0' <= ch && ch <= '9')
 938                         continue;
 939                 if (ch == '~' || ch == '^')
 940                         has_suffix = ch;
 941                 break;
 942         }
 943
 944         if (has_suffix) {
 945                 int num = 0;
 946                 int len1 = cp - name;
 947                 cp++;
 948                 while (cp < name + len)
 949                         num = num * 10 + *cp++ - '0';
 950                 if (!num && len1 == len - 1)
 951                         num = 1;
 952                 if (has_suffix == '^')
 953                         return get_parent(name, len1, sha1, num);
 954                 /* else if (has_suffix == '~') -- goes without saying */
 955                 return get_nth_ancestor(name, len1, sha1, num);
 956         }
 957
 958         ret = peel_onion(name, len, sha1, lookup_flags);
 959         if (!ret)
 960                 return 0;
 961
 962         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 963         if (!ret)
 964                 return 0;
 965
 966         /* It could be describe output that is "SOMETHING-gXXXX" */
 967         ret = get_describe_name(name, len, sha1);
 968         if (!ret)
 969                 return 0;
 970
 971         return get_short_sha1(name, len, sha1, lookup_flags);
 972 }
 973
 974 /*
 975  * This interprets names like ':/Initial revision of "git"' by searching
 976  * through history and returning the first commit whose message starts
 977  * the given regular expression.
 978  *
 979  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 980  *
 981  * For a literal '!' character at the beginning of a pattern, you have to repeat
 982  * that, like: ':/!!foo'
 983  *
 984  * For future extension, all other sequences beginning with ':/!' are reserved.
 985  */
 986
 987 /* Remember to update object flag allocation in object.h */
 988 #define ONELINE_SEEN (1u<<20)
 989
 990 static int handle_one_ref(const char *path, const struct object_id *oid,
 991                           int flag, void *cb_data)
 992 {
 993         struct commit_list **list = cb_data;
 994         struct object *object = parse_object(oid);
 995         if (!object)
 996                 return 0;
 997         if (object->type == OBJ_TAG) {
 998                 object = deref_tag(object, path, strlen(path));
 999                 if (!object)
1000                         return 0;
1001         }
1002         if (object->type != OBJ_COMMIT)
1003                 return 0;
1004         commit_list_insert((struct commit *)object, list);
1005         return 0;
1006 }
1007
1008 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
1009                             struct commit_list *list)
1010 {
1011         struct commit_list *backup = NULL, *l;
1012         int found = 0;
1013         int negative = 0;
1014         regex_t regex;
1015
1016         if (prefix[0] == '!') {
1017                 prefix++;
1018
1019                 if (prefix[0] == '-') {
1020                         prefix++;
1021                         negative = 1;
1022                 } else if (prefix[0] != '!') {
1023                         return -1;
1024                 }
1025         }
1026
1027         if (regcomp(&regex, prefix, REG_EXTENDED))
1028                 return -1;
1029
1030         for (l = list; l; l = l->next) {
1031                 l->item->object.flags |= ONELINE_SEEN;
1032                 commit_list_insert(l->item, &backup);
1033         }
1034         while (list) {
1035                 const char *p, *buf;
1036                 struct commit *commit;
1037                 int matches;
1038
1039                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1040                 if (!parse_object(&commit->object.oid))
1041                         continue;
1042                 buf = get_commit_buffer(commit, NULL);
1043                 p = strstr(buf, "\n\n");
1044                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1045                 unuse_commit_buffer(commit, buf);
1046
1047                 if (matches) {
1048                         hashcpy(sha1, commit->object.oid.hash);
1049                         found = 1;
1050                         break;
1051                 }
1052         }
1053         regfree(&regex);
1054         free_commit_list(list);
1055         for (l = backup; l; l = l->next)
1056                 clear_commit_marks(l->item, ONELINE_SEEN);
1057         free_commit_list(backup);
1058         return found ? 0 : -1;
1059 }
1060
1061 struct grab_nth_branch_switch_cbdata {
1062         int remaining;
1063         struct strbuf buf;
1064 };
1065
1066 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1067                                   const char *email, timestamp_t timestamp, int tz,
1068                                   const char *message, void *cb_data)
1069 {
1070         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1071         const char *match = NULL, *target = NULL;
1072         size_t len;
1073
1074         if (skip_prefix(message, "checkout: moving from ", &match))
1075                 target = strstr(match, " to ");
1076
1077         if (!match || !target)
1078                 return 0;
1079         if (--(cb->remaining) == 0) {
1080                 len = target - match;
1081                 strbuf_reset(&cb->buf);
1082                 strbuf_add(&cb->buf, match, len);
1083                 return 1; /* we are done */
1084         }
1085         return 0;
1086 }
1087
1088 /*
1089  * Parse @{-N} syntax, return the number of characters parsed
1090  * if successful; otherwise signal an error with negative value.
1091  */
1092 static int interpret_nth_prior_checkout(const char *name, int namelen,
1093                                         struct strbuf *buf)
1094 {
1095         long nth;
1096         int retval;
1097         struct grab_nth_branch_switch_cbdata cb;
1098         const char *brace;
1099         char *num_end;
1100
1101         if (namelen < 4)
1102                 return -1;
1103         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1104                 return -1;
1105         brace = memchr(name, '}', namelen);
1106         if (!brace)
1107                 return -1;
1108         nth = strtol(name + 3, &num_end, 10);
1109         if (num_end != brace)
1110                 return -1;
1111         if (nth <= 0)
1112                 return -1;
1113         cb.remaining = nth;
1114         strbuf_init(&cb.buf, 20);
1115
1116         retval = 0;
1117         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1118                 strbuf_reset(buf);
1119                 strbuf_addbuf(buf, &cb.buf);
1120                 retval = brace - name + 1;
1121         }
1122
1123         strbuf_release(&cb.buf);
1124         return retval;
1125 }
1126
1127 int get_oid_mb(const char *name, struct object_id *oid)
1128 {
1129         struct commit *one, *two;
1130         struct commit_list *mbs;
1131         struct object_id oid_tmp;
1132         const char *dots;
1133         int st;
1134
1135         dots = strstr(name, "...");
1136         if (!dots)
1137                 return get_oid(name, oid);
1138         if (dots == name)
1139                 st = get_oid("HEAD", &oid_tmp);
1140         else {
1141                 struct strbuf sb;
1142                 strbuf_init(&sb, dots - name);
1143                 strbuf_add(&sb, name, dots - name);
1144                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1145                 strbuf_release(&sb);
1146         }
1147         if (st)
1148                 return st;
1149         one = lookup_commit_reference_gently(&oid_tmp, 0);
1150         if (!one)
1151                 return -1;
1152
1153         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1154                 return -1;
1155         two = lookup_commit_reference_gently(&oid_tmp, 0);
1156         if (!two)
1157                 return -1;
1158         mbs = get_merge_bases(one, two);
1159         if (!mbs || mbs->next)
1160                 st = -1;
1161         else {
1162                 st = 0;
1163                 oidcpy(oid, &mbs->item->object.oid);
1164         }
1165         free_commit_list(mbs);
1166         return st;
1167 }
1168
1169 /* parse @something syntax, when 'something' is not {.*} */
1170 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1171 {
1172         const char *next;
1173
1174         if (len || name[1] == '{')
1175                 return -1;
1176
1177         /* make sure it's a single @, or @@{.*}, not @foo */
1178         next = memchr(name + len + 1, '@', namelen - len - 1);
1179         if (next && next[1] != '{')
1180                 return -1;
1181         if (!next)
1182                 next = name + namelen;
1183         if (next != name + 1)
1184                 return -1;
1185
1186         strbuf_reset(buf);
1187         strbuf_add(buf, "HEAD", 4);
1188         return 1;
1189 }
1190
1191 static int reinterpret(const char *name, int namelen, int len,
1192                        struct strbuf *buf, unsigned allowed)
1193 {
1194         /* we have extra data, which might need further processing */
1195         struct strbuf tmp = STRBUF_INIT;
1196         int used = buf->len;
1197         int ret;
1198
1199         strbuf_add(buf, name + len, namelen - len);
1200         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1201         /* that data was not interpreted, remove our cruft */
1202         if (ret < 0) {
1203                 strbuf_setlen(buf, used);
1204                 return len;
1205         }
1206         strbuf_reset(buf);
1207         strbuf_addbuf(buf, &tmp);
1208         strbuf_release(&tmp);
1209         /* tweak for size of {-N} versus expanded ref name */
1210         return ret - used + len;
1211 }
1212
1213 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1214 {
1215         char *s = shorten_unambiguous_ref(ref, 0);
1216         strbuf_reset(buf);
1217         strbuf_addstr(buf, s);
1218         free(s);
1219 }
1220
1221 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1222 {
1223         if (!allowed)
1224                 return 1;
1225
1226         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1227             starts_with(refname, "refs/heads/"))
1228                 return 1;
1229         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1230             starts_with(refname, "refs/remotes/"))
1231                 return 1;
1232
1233         return 0;
1234 }
1235
1236 static int interpret_branch_mark(const char *name, int namelen,
1237                                  int at, struct strbuf *buf,
1238                                  int (*get_mark)(const char *, int),
1239                                  const char *(*get_data)(struct branch *,
1240                                                          struct strbuf *),
1241                                  unsigned allowed)
1242 {
1243         int len;
1244         struct branch *branch;
1245         struct strbuf err = STRBUF_INIT;
1246         const char *value;
1247
1248         len = get_mark(name + at, namelen - at);
1249         if (!len)
1250                 return -1;
1251
1252         if (memchr(name, ':', at))
1253                 return -1;
1254
1255         if (at) {
1256                 char *name_str = xmemdupz(name, at);
1257                 branch = branch_get(name_str);
1258                 free(name_str);
1259         } else
1260                 branch = branch_get(NULL);
1261
1262         value = get_data(branch, &err);
1263         if (!value)
1264                 die("%s", err.buf);
1265
1266         if (!branch_interpret_allowed(value, allowed))
1267                 return -1;
1268
1269         set_shortened_ref(buf, value);
1270         return len + at;
1271 }
1272
1273 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1274                           unsigned allowed)
1275 {
1276         char *at;
1277         const char *start;
1278         int len;
1279
1280         if (!namelen)
1281                 namelen = strlen(name);
1282
1283         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1284                 len = interpret_nth_prior_checkout(name, namelen, buf);
1285                 if (!len) {
1286                         return len; /* syntax Ok, not enough switches */
1287                 } else if (len > 0) {
1288                         if (len == namelen)
1289                                 return len; /* consumed all */
1290                         else
1291                                 return reinterpret(name, namelen, len, buf, allowed);
1292                 }
1293         }
1294
1295         for (start = name;
1296              (at = memchr(start, '@', namelen - (start - name)));
1297              start = at + 1) {
1298
1299                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1300                         len = interpret_empty_at(name, namelen, at - name, buf);
1301                         if (len > 0)
1302                                 return reinterpret(name, namelen, len, buf,
1303                                                    allowed);
1304                 }
1305
1306                 len = interpret_branch_mark(name, namelen, at - name, buf,
1307                                             upstream_mark, branch_get_upstream,
1308                                             allowed);
1309                 if (len > 0)
1310                         return len;
1311
1312                 len = interpret_branch_mark(name, namelen, at - name, buf,
1313                                             push_mark, branch_get_push,
1314                                             allowed);
1315                 if (len > 0)
1316                         return len;
1317         }
1318
1319         return -1;
1320 }
1321
1322 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1323 {
1324         int len = strlen(name);
1325         int used = interpret_branch_name(name, len, sb, allowed);
1326
1327         if (used < 0)
1328                 used = 0;
1329         strbuf_add(sb, name + used, len - used);
1330 }
1331
1332 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1333 {
1334         strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1335         if (name[0] == '-')
1336                 return -1;
1337         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1338         return check_refname_format(sb->buf, 0);
1339 }
1340
1341 /*
1342  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1343  * notably "xyz^" for "parent of xyz"
1344  */
1345 int get_sha1(const char *name, unsigned char *sha1)
1346 {
1347         struct object_context unused;
1348         return get_sha1_with_context(name, 0, sha1, &unused);
1349 }
1350
1351 /*
1352  * This is like "get_sha1()", but for struct object_id.
1353  */
1354 int get_oid(const char *name, struct object_id *oid)
1355 {
1356         return get_sha1(name, oid->hash);
1357 }
1358
1359
1360 /*
1361  * Many callers know that the user meant to name a commit-ish by
1362  * syntactical positions where the object name appears.  Calling this
1363  * function allows the machinery to disambiguate shorter-than-unique
1364  * abbreviated object names between commit-ish and others.
1365  *
1366  * Note that this does NOT error out when the named object is not a
1367  * commit-ish. It is merely to give a hint to the disambiguation
1368  * machinery.
1369  */
1370 int get_sha1_committish(const char *name, unsigned char *sha1)
1371 {
1372         struct object_context unused;
1373         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1374                                      sha1, &unused);
1375 }
1376
1377 int get_sha1_treeish(const char *name, unsigned char *sha1)
1378 {
1379         struct object_context unused;
1380         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1381                                      sha1, &unused);
1382 }
1383
1384 int get_sha1_commit(const char *name, unsigned char *sha1)
1385 {
1386         struct object_context unused;
1387         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1388                                      sha1, &unused);
1389 }
1390
1391 int get_sha1_tree(const char *name, unsigned char *sha1)
1392 {
1393         struct object_context unused;
1394         return get_sha1_with_context(name, GET_SHA1_TREE,
1395                                      sha1, &unused);
1396 }
1397
1398 int get_sha1_blob(const char *name, unsigned char *sha1)
1399 {
1400         struct object_context unused;
1401         return get_sha1_with_context(name, GET_SHA1_BLOB,
1402                                      sha1, &unused);
1403 }
1404
1405 /* Must be called only when object_name:filename doesn't exist. */
1406 static void diagnose_invalid_sha1_path(const char *prefix,
1407                                        const char *filename,
1408                                        const unsigned char *tree_sha1,
1409                                        const char *object_name,
1410                                        int object_name_len)
1411 {
1412         unsigned char sha1[20];
1413         unsigned mode;
1414
1415         if (!prefix)
1416                 prefix = "";
1417
1418         if (file_exists(filename))
1419                 die("Path '%s' exists on disk, but not in '%.*s'.",
1420                     filename, object_name_len, object_name);
1421         if (is_missing_file_error(errno)) {
1422                 char *fullname = xstrfmt("%s%s", prefix, filename);
1423
1424                 if (!get_tree_entry(tree_sha1, fullname,
1425                                     sha1, &mode)) {
1426                         die("Path '%s' exists, but not '%s'.\n"
1427                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1428                             fullname,
1429                             filename,
1430                             object_name_len, object_name,
1431                             fullname,
1432                             object_name_len, object_name,
1433                             filename);
1434                 }
1435                 die("Path '%s' does not exist in '%.*s'",
1436                     filename, object_name_len, object_name);
1437         }
1438 }
1439
1440 /* Must be called only when :stage:filename doesn't exist. */
1441 static void diagnose_invalid_index_path(int stage,
1442                                         const char *prefix,
1443                                         const char *filename)
1444 {
1445         const struct cache_entry *ce;
1446         int pos;
1447         unsigned namelen = strlen(filename);
1448         struct strbuf fullname = STRBUF_INIT;
1449
1450         if (!prefix)
1451                 prefix = "";
1452
1453         /* Wrong stage number? */
1454         pos = cache_name_pos(filename, namelen);
1455         if (pos < 0)
1456                 pos = -pos - 1;
1457         if (pos < active_nr) {
1458                 ce = active_cache[pos];
1459                 if (ce_namelen(ce) == namelen &&
1460                     !memcmp(ce->name, filename, namelen))
1461                         die("Path '%s' is in the index, but not at stage %d.\n"
1462                             "Did you mean ':%d:%s'?",
1463                             filename, stage,
1464                             ce_stage(ce), filename);
1465         }
1466
1467         /* Confusion between relative and absolute filenames? */
1468         strbuf_addstr(&fullname, prefix);
1469         strbuf_addstr(&fullname, filename);
1470         pos = cache_name_pos(fullname.buf, fullname.len);
1471         if (pos < 0)
1472                 pos = -pos - 1;
1473         if (pos < active_nr) {
1474                 ce = active_cache[pos];
1475                 if (ce_namelen(ce) == fullname.len &&
1476                     !memcmp(ce->name, fullname.buf, fullname.len))
1477                         die("Path '%s' is in the index, but not '%s'.\n"
1478                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1479                             fullname.buf, filename,
1480                             ce_stage(ce), fullname.buf,
1481                             ce_stage(ce), filename);
1482         }
1483
1484         if (file_exists(filename))
1485                 die("Path '%s' exists on disk, but not in the index.", filename);
1486         if (is_missing_file_error(errno))
1487                 die("Path '%s' does not exist (neither on disk nor in the index).",
1488                     filename);
1489
1490         strbuf_release(&fullname);
1491 }
1492
1493
1494 static char *resolve_relative_path(const char *rel)
1495 {
1496         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1497                 return NULL;
1498
1499         if (!is_inside_work_tree())
1500                 die("relative path syntax can't be used outside working tree.");
1501
1502         /* die() inside prefix_path() if resolved path is outside worktree */
1503         return prefix_path(startup_info->prefix,
1504                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1505                            rel);
1506 }
1507
1508 static int get_sha1_with_context_1(const char *name,
1509                                    unsigned flags,
1510                                    const char *prefix,
1511                                    unsigned char *sha1,
1512                                    struct object_context *oc)
1513 {
1514         int ret, bracket_depth;
1515         int namelen = strlen(name);
1516         const char *cp;
1517         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1518
1519         if (only_to_die)
1520                 flags |= GET_SHA1_QUIETLY;
1521
1522         memset(oc, 0, sizeof(*oc));
1523         oc->mode = S_IFINVALID;
1524         strbuf_init(&oc->symlink_path, 0);
1525         ret = get_sha1_1(name, namelen, sha1, flags);
1526         if (!ret)
1527                 return ret;
1528         /*
1529          * sha1:path --> object name of path in ent sha1
1530          * :path -> object name of absolute path in index
1531          * :./path -> object name of path relative to cwd in index
1532          * :[0-3]:path -> object name of path in index at stage
1533          * :/foo -> recent commit matching foo
1534          */
1535         if (name[0] == ':') {
1536                 int stage = 0;
1537                 const struct cache_entry *ce;
1538                 char *new_path = NULL;
1539                 int pos;
1540                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1541                         struct commit_list *list = NULL;
1542
1543                         for_each_ref(handle_one_ref, &list);
1544                         commit_list_sort_by_date(&list);
1545                         return get_sha1_oneline(name + 2, sha1, list);
1546                 }
1547                 if (namelen < 3 ||
1548                     name[2] != ':' ||
1549                     name[1] < '0' || '3' < name[1])
1550                         cp = name + 1;
1551                 else {
1552                         stage = name[1] - '0';
1553                         cp = name + 3;
1554                 }
1555                 new_path = resolve_relative_path(cp);
1556                 if (!new_path) {
1557                         namelen = namelen - (cp - name);
1558                 } else {
1559                         cp = new_path;
1560                         namelen = strlen(cp);
1561                 }
1562
1563                 if (flags & GET_SHA1_RECORD_PATH)
1564                         oc->path = xstrdup(cp);
1565
1566                 if (!active_cache)
1567                         read_cache();
1568                 pos = cache_name_pos(cp, namelen);
1569                 if (pos < 0)
1570                         pos = -pos - 1;
1571                 while (pos < active_nr) {
1572                         ce = active_cache[pos];
1573                         if (ce_namelen(ce) != namelen ||
1574                             memcmp(ce->name, cp, namelen))
1575                                 break;
1576                         if (ce_stage(ce) == stage) {
1577                                 hashcpy(sha1, ce->oid.hash);
1578                                 oc->mode = ce->ce_mode;
1579                                 free(new_path);
1580                                 return 0;
1581                         }
1582                         pos++;
1583                 }
1584                 if (only_to_die && name[1] && name[1] != '/')
1585                         diagnose_invalid_index_path(stage, prefix, cp);
1586                 free(new_path);
1587                 return -1;
1588         }
1589         for (cp = name, bracket_depth = 0; *cp; cp++) {
1590                 if (*cp == '{')
1591                         bracket_depth++;
1592                 else if (bracket_depth && *cp == '}')
1593                         bracket_depth--;
1594                 else if (!bracket_depth && *cp == ':')
1595                         break;
1596         }
1597         if (*cp == ':') {
1598                 unsigned char tree_sha1[20];
1599                 int len = cp - name;
1600                 unsigned sub_flags = flags;
1601
1602                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1603                 sub_flags |= GET_SHA1_TREEISH;
1604
1605                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1606                         const char *filename = cp+1;
1607                         char *new_filename = NULL;
1608
1609                         new_filename = resolve_relative_path(filename);
1610                         if (new_filename)
1611                                 filename = new_filename;
1612                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1613                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1614                                         filename, sha1, &oc->symlink_path,
1615                                         &oc->mode);
1616                         } else {
1617                                 ret = get_tree_entry(tree_sha1, filename,
1618                                                      sha1, &oc->mode);
1619                                 if (ret && only_to_die) {
1620                                         diagnose_invalid_sha1_path(prefix,
1621                                                                    filename,
1622                                                                    tree_sha1,
1623                                                                    name, len);
1624                                 }
1625                         }
1626                         hashcpy(oc->tree, tree_sha1);
1627                         if (flags & GET_SHA1_RECORD_PATH)
1628                                 oc->path = xstrdup(filename);
1629
1630                         free(new_filename);
1631                         return ret;
1632                 } else {
1633                         if (only_to_die)
1634                                 die("Invalid object name '%.*s'.", len, name);
1635                 }
1636         }
1637         return ret;
1638 }
1639
1640 /*
1641  * Call this function when you know "name" given by the end user must
1642  * name an object but it doesn't; the function _may_ die with a better
1643  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1644  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1645  * you have a chance to diagnose the error further.
1646  */
1647 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1648 {
1649         struct object_context oc;
1650         unsigned char sha1[20];
1651         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1652 }
1653
1654 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *oc)
1655 {
1656         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1657                 die("BUG: incompatible flags for get_sha1_with_context");
1658         return get_sha1_with_context_1(str, flags, NULL, sha1, oc);
1659 }