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