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[3 & ++bufno];
 478         find_unique_abbrev_r(hex, sha1, len);
 479         return hex;
 480 }
 481
 482 static int ambiguous_path(const char *path, int len)
 483 {
 484         int slash = 1;
 485         int cnt;
 486
 487         for (cnt = 0; cnt < len; cnt++) {
 488                 switch (*path++) {
 489                 case '\0':
 490                         break;
 491                 case '/':
 492                         if (slash)
 493                                 break;
 494                         slash = 1;
 495                         continue;
 496                 case '.':
 497                         continue;
 498                 default:
 499                         slash = 0;
 500                         continue;
 501                 }
 502                 break;
 503         }
 504         return slash;
 505 }
 506
 507 static inline int at_mark(const char *string, int len,
 508                           const char **suffix, int nr)
 509 {
 510         int i;
 511
 512         for (i = 0; i < nr; i++) {
 513                 int suffix_len = strlen(suffix[i]);
 514                 if (suffix_len <= len
 515                     && !memcmp(string, suffix[i], suffix_len))
 516                         return suffix_len;
 517         }
 518         return 0;
 519 }
 520
 521 static inline int upstream_mark(const char *string, int len)
 522 {
 523         const char *suffix[] = { "@{upstream}", "@{u}" };
 524         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 525 }
 526
 527 static inline int push_mark(const char *string, int len)
 528 {
 529         const char *suffix[] = { "@{push}" };
 530         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 531 }
 532
 533 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 534 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 535
 536 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 537                           unsigned int flags)
 538 {
 539         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 540         static const char *object_name_msg = N_(
 541         "Git normally never creates a ref that ends with 40 hex characters\n"
 542         "because it will be ignored when you just specify 40-hex. These refs\n"
 543         "may be created by mistake. For example,\n"
 544         "\n"
 545         "  git checkout -b $br $(git rev-parse ...)\n"
 546         "\n"
 547         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 548         "examine these refs and maybe delete them. Turn this message off by\n"
 549         "running \"git config advice.objectNameWarning false\"");
 550         unsigned char tmp_sha1[20];
 551         char *real_ref = NULL;
 552         int refs_found = 0;
 553         int at, reflog_len, nth_prior = 0;
 554
 555         if (len == 40 && !get_sha1_hex(str, sha1)) {
 556                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 557                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 558                         if (refs_found > 0) {
 559                                 warning(warn_msg, len, str);
 560                                 if (advice_object_name_warning)
 561                                         fprintf(stderr, "%s\n", _(object_name_msg));
 562                         }
 563                         free(real_ref);
 564                 }
 565                 return 0;
 566         }
 567
 568         /* basic@{time or number or -number} format to query ref-log */
 569         reflog_len = at = 0;
 570         if (len && str[len-1] == '}') {
 571                 for (at = len-4; at >= 0; at--) {
 572                         if (str[at] == '@' && str[at+1] == '{') {
 573                                 if (str[at+2] == '-') {
 574                                         if (at != 0)
 575                                                 /* @{-N} not at start */
 576                                                 return -1;
 577                                         nth_prior = 1;
 578                                         continue;
 579                                 }
 580                                 if (!upstream_mark(str + at, len - at) &&
 581                                     !push_mark(str + at, len - at)) {
 582                                         reflog_len = (len-1) - (at+2);
 583                                         len = at;
 584                                 }
 585                                 break;
 586                         }
 587                 }
 588         }
 589
 590         /* Accept only unambiguous ref paths. */
 591         if (len && ambiguous_path(str, len))
 592                 return -1;
 593
 594         if (nth_prior) {
 595                 struct strbuf buf = STRBUF_INIT;
 596                 int detached;
 597
 598                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 599                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 600                         strbuf_release(&buf);
 601                         if (detached)
 602                                 return 0;
 603                 }
 604         }
 605
 606         if (!len && reflog_len)
 607                 /* allow "@{...}" to mean the current branch reflog */
 608                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 609         else if (reflog_len)
 610                 refs_found = dwim_log(str, len, sha1, &real_ref);
 611         else
 612                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 613
 614         if (!refs_found)
 615                 return -1;
 616
 617         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 618             (refs_found > 1 ||
 619              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 620                 warning(warn_msg, len, str);
 621
 622         if (reflog_len) {
 623                 int nth, i;
 624                 unsigned long at_time;
 625                 unsigned long co_time;
 626                 int co_tz, co_cnt;
 627
 628                 /* Is it asking for N-th entry, or approxidate? */
 629                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 630                         char ch = str[at+2+i];
 631                         if ('0' <= ch && ch <= '9')
 632                                 nth = nth * 10 + ch - '0';
 633                         else
 634                                 nth = -1;
 635                 }
 636                 if (100000000 <= nth) {
 637                         at_time = nth;
 638                         nth = -1;
 639                 } else if (0 <= nth)
 640                         at_time = 0;
 641                 else {
 642                         int errors = 0;
 643                         char *tmp = xstrndup(str + at + 2, reflog_len);
 644                         at_time = approxidate_careful(tmp, &errors);
 645                         free(tmp);
 646                         if (errors) {
 647                                 free(real_ref);
 648                                 return -1;
 649                         }
 650                 }
 651                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 652                                 &co_time, &co_tz, &co_cnt)) {
 653                         if (!len) {
 654                                 if (starts_with(real_ref, "refs/heads/")) {
 655                                         str = real_ref + 11;
 656                                         len = strlen(real_ref + 11);
 657                                 } else {
 658                                         /* detached HEAD */
 659                                         str = "HEAD";
 660                                         len = 4;
 661                                 }
 662                         }
 663                         if (at_time) {
 664                                 if (!(flags & GET_SHA1_QUIETLY)) {
 665                                         warning("Log for '%.*s' only goes "
 666                                                 "back to %s.", len, str,
 667                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 668                                 }
 669                         } else {
 670                                 if (flags & GET_SHA1_QUIETLY) {
 671                                         exit(128);
 672                                 }
 673                                 die("Log for '%.*s' only has %d entries.",
 674                                     len, str, co_cnt);
 675                         }
 676                 }
 677         }
 678
 679         free(real_ref);
 680         return 0;
 681 }
 682
 683 static int get_parent(const char *name, int len,
 684                       unsigned char *result, int idx)
 685 {
 686         unsigned char sha1[20];
 687         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 688         struct commit *commit;
 689         struct commit_list *p;
 690
 691         if (ret)
 692                 return ret;
 693         commit = lookup_commit_reference(sha1);
 694         if (parse_commit(commit))
 695                 return -1;
 696         if (!idx) {
 697                 hashcpy(result, commit->object.oid.hash);
 698                 return 0;
 699         }
 700         p = commit->parents;
 701         while (p) {
 702                 if (!--idx) {
 703                         hashcpy(result, p->item->object.oid.hash);
 704                         return 0;
 705                 }
 706                 p = p->next;
 707         }
 708         return -1;
 709 }
 710
 711 static int get_nth_ancestor(const char *name, int len,
 712                             unsigned char *result, int generation)
 713 {
 714         unsigned char sha1[20];
 715         struct commit *commit;
 716         int ret;
 717
 718         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 719         if (ret)
 720                 return ret;
 721         commit = lookup_commit_reference(sha1);
 722         if (!commit)
 723                 return -1;
 724
 725         while (generation--) {
 726                 if (parse_commit(commit) || !commit->parents)
 727                         return -1;
 728                 commit = commit->parents->item;
 729         }
 730         hashcpy(result, commit->object.oid.hash);
 731         return 0;
 732 }
 733
 734 struct object *peel_to_type(const char *name, int namelen,
 735                             struct object *o, enum object_type expected_type)
 736 {
 737         if (name && !namelen)
 738                 namelen = strlen(name);
 739         while (1) {
 740                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 741                         return NULL;
 742                 if (expected_type == OBJ_ANY || o->type == expected_type)
 743                         return o;
 744                 if (o->type == OBJ_TAG)
 745                         o = ((struct tag*) o)->tagged;
 746                 else if (o->type == OBJ_COMMIT)
 747                         o = &(((struct commit *) o)->tree->object);
 748                 else {
 749                         if (name)
 750                                 error("%.*s: expected %s type, but the object "
 751                                       "dereferences to %s type",
 752                                       namelen, name, typename(expected_type),
 753                                       typename(o->type));
 754                         return NULL;
 755                 }
 756         }
 757 }
 758
 759 static int peel_onion(const char *name, int len, unsigned char *sha1,
 760                       unsigned lookup_flags)
 761 {
 762         unsigned char outer[20];
 763         const char *sp;
 764         unsigned int expected_type = 0;
 765         struct object *o;
 766
 767         /*
 768          * "ref^{type}" dereferences ref repeatedly until you cannot
 769          * dereference anymore, or you get an object of given type,
 770          * whichever comes first.  "ref^{}" means just dereference
 771          * tags until you get a non-tag.  "ref^0" is a shorthand for
 772          * "ref^{commit}".  "commit^{tree}" could be used to find the
 773          * top-level tree of the given commit.
 774          */
 775         if (len < 4 || name[len-1] != '}')
 776                 return -1;
 777
 778         for (sp = name + len - 1; name <= sp; sp--) {
 779                 int ch = *sp;
 780                 if (ch == '{' && name < sp && sp[-1] == '^')
 781                         break;
 782         }
 783         if (sp <= name)
 784                 return -1;
 785
 786         sp++; /* beginning of type name, or closing brace for empty */
 787         if (starts_with(sp, "commit}"))
 788                 expected_type = OBJ_COMMIT;
 789         else if (starts_with(sp, "tag}"))
 790                 expected_type = OBJ_TAG;
 791         else if (starts_with(sp, "tree}"))
 792                 expected_type = OBJ_TREE;
 793         else if (starts_with(sp, "blob}"))
 794                 expected_type = OBJ_BLOB;
 795         else if (starts_with(sp, "object}"))
 796                 expected_type = OBJ_ANY;
 797         else if (sp[0] == '}')
 798                 expected_type = OBJ_NONE;
 799         else if (sp[0] == '/')
 800                 expected_type = OBJ_COMMIT;
 801         else
 802                 return -1;
 803
 804         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 805         if (expected_type == OBJ_COMMIT)
 806                 lookup_flags |= GET_SHA1_COMMITTISH;
 807         else if (expected_type == OBJ_TREE)
 808                 lookup_flags |= GET_SHA1_TREEISH;
 809
 810         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 811                 return -1;
 812
 813         o = parse_object(outer);
 814         if (!o)
 815                 return -1;
 816         if (!expected_type) {
 817                 o = deref_tag(o, name, sp - name - 2);
 818                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 819                         return -1;
 820                 hashcpy(sha1, o->oid.hash);
 821                 return 0;
 822         }
 823
 824         /*
 825          * At this point, the syntax look correct, so
 826          * if we do not get the needed object, we should
 827          * barf.
 828          */
 829         o = peel_to_type(name, len, o, expected_type);
 830         if (!o)
 831                 return -1;
 832
 833         hashcpy(sha1, o->oid.hash);
 834         if (sp[0] == '/') {
 835                 /* "$commit^{/foo}" */
 836                 char *prefix;
 837                 int ret;
 838                 struct commit_list *list = NULL;
 839
 840                 /*
 841                  * $commit^{/}. Some regex implementation may reject.
 842                  * We don't need regex anyway. '' pattern always matches.
 843                  */
 844                 if (sp[1] == '}')
 845                         return 0;
 846
 847                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 848                 commit_list_insert((struct commit *)o, &list);
 849                 ret = get_sha1_oneline(prefix, sha1, list);
 850                 free(prefix);
 851                 return ret;
 852         }
 853         return 0;
 854 }
 855
 856 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 857 {
 858         const char *cp;
 859         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 860
 861         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 862                 char ch = *cp;
 863                 if (!isxdigit(ch)) {
 864                         /* We must be looking at g in "SOMETHING-g"
 865                          * for it to be describe output.
 866                          */
 867                         if (ch == 'g' && cp[-1] == '-') {
 868                                 cp++;
 869                                 len -= cp - name;
 870                                 return get_short_sha1(cp, len, sha1, flags);
 871                         }
 872                 }
 873         }
 874         return -1;
 875 }
 876
 877 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 878 {
 879         int ret, has_suffix;
 880         const char *cp;
 881
 882         /*
 883          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 884          */
 885         has_suffix = 0;
 886         for (cp = name + len - 1; name <= cp; cp--) {
 887                 int ch = *cp;
 888                 if ('0' <= ch && ch <= '9')
 889                         continue;
 890                 if (ch == '~' || ch == '^')
 891                         has_suffix = ch;
 892                 break;
 893         }
 894
 895         if (has_suffix) {
 896                 int num = 0;
 897                 int len1 = cp - name;
 898                 cp++;
 899                 while (cp < name + len)
 900                         num = num * 10 + *cp++ - '0';
 901                 if (!num && len1 == len - 1)
 902                         num = 1;
 903                 if (has_suffix == '^')
 904                         return get_parent(name, len1, sha1, num);
 905                 /* else if (has_suffix == '~') -- goes without saying */
 906                 return get_nth_ancestor(name, len1, sha1, num);
 907         }
 908
 909         ret = peel_onion(name, len, sha1, lookup_flags);
 910         if (!ret)
 911                 return 0;
 912
 913         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 914         if (!ret)
 915                 return 0;
 916
 917         /* It could be describe output that is "SOMETHING-gXXXX" */
 918         ret = get_describe_name(name, len, sha1);
 919         if (!ret)
 920                 return 0;
 921
 922         return get_short_sha1(name, len, sha1, lookup_flags);
 923 }
 924
 925 /*
 926  * This interprets names like ':/Initial revision of "git"' by searching
 927  * through history and returning the first commit whose message starts
 928  * the given regular expression.
 929  *
 930  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 931  *
 932  * For a literal '!' character at the beginning of a pattern, you have to repeat
 933  * that, like: ':/!!foo'
 934  *
 935  * For future extension, all other sequences beginning with ':/!' are reserved.
 936  */
 937
 938 /* Remember to update object flag allocation in object.h */
 939 #define ONELINE_SEEN (1u<<20)
 940
 941 static int handle_one_ref(const char *path, const struct object_id *oid,
 942                           int flag, void *cb_data)
 943 {
 944         struct commit_list **list = cb_data;
 945         struct object *object = parse_object(oid->hash);
 946         if (!object)
 947                 return 0;
 948         if (object->type == OBJ_TAG) {
 949                 object = deref_tag(object, path, strlen(path));
 950                 if (!object)
 951                         return 0;
 952         }
 953         if (object->type != OBJ_COMMIT)
 954                 return 0;
 955         commit_list_insert((struct commit *)object, list);
 956         return 0;
 957 }
 958
 959 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 960                             struct commit_list *list)
 961 {
 962         struct commit_list *backup = NULL, *l;
 963         int found = 0;
 964         int negative = 0;
 965         regex_t regex;
 966
 967         if (prefix[0] == '!') {
 968                 prefix++;
 969
 970                 if (prefix[0] == '-') {
 971                         prefix++;
 972                         negative = 1;
 973                 } else if (prefix[0] != '!') {
 974                         return -1;
 975                 }
 976         }
 977
 978         if (regcomp(&regex, prefix, REG_EXTENDED))
 979                 return -1;
 980
 981         for (l = list; l; l = l->next) {
 982                 l->item->object.flags |= ONELINE_SEEN;
 983                 commit_list_insert(l->item, &backup);
 984         }
 985         while (list) {
 986                 const char *p, *buf;
 987                 struct commit *commit;
 988                 int matches;
 989
 990                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 991                 if (!parse_object(commit->object.oid.hash))
 992                         continue;
 993                 buf = get_commit_buffer(commit, NULL);
 994                 p = strstr(buf, "\n\n");
 995                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
 996                 unuse_commit_buffer(commit, buf);
 997
 998                 if (matches) {
 999                         hashcpy(sha1, commit->object.oid.hash);
1000                         found = 1;
1001                         break;
1002                 }
1003         }
1004         regfree(&regex);
1005         free_commit_list(list);
1006         for (l = backup; l; l = l->next)
1007                 clear_commit_marks(l->item, ONELINE_SEEN);
1008         free_commit_list(backup);
1009         return found ? 0 : -1;
1010 }
1011
1012 struct grab_nth_branch_switch_cbdata {
1013         int remaining;
1014         struct strbuf buf;
1015 };
1016
1017 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
1018                                   const char *email, unsigned long timestamp, int tz,
1019                                   const char *message, void *cb_data)
1020 {
1021         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1022         const char *match = NULL, *target = NULL;
1023         size_t len;
1024
1025         if (skip_prefix(message, "checkout: moving from ", &match))
1026                 target = strstr(match, " to ");
1027
1028         if (!match || !target)
1029                 return 0;
1030         if (--(cb->remaining) == 0) {
1031                 len = target - match;
1032                 strbuf_reset(&cb->buf);
1033                 strbuf_add(&cb->buf, match, len);
1034                 return 1; /* we are done */
1035         }
1036         return 0;
1037 }
1038
1039 /*
1040  * Parse @{-N} syntax, return the number of characters parsed
1041  * if successful; otherwise signal an error with negative value.
1042  */
1043 static int interpret_nth_prior_checkout(const char *name, int namelen,
1044                                         struct strbuf *buf)
1045 {
1046         long nth;
1047         int retval;
1048         struct grab_nth_branch_switch_cbdata cb;
1049         const char *brace;
1050         char *num_end;
1051
1052         if (namelen < 4)
1053                 return -1;
1054         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1055                 return -1;
1056         brace = memchr(name, '}', namelen);
1057         if (!brace)
1058                 return -1;
1059         nth = strtol(name + 3, &num_end, 10);
1060         if (num_end != brace)
1061                 return -1;
1062         if (nth <= 0)
1063                 return -1;
1064         cb.remaining = nth;
1065         strbuf_init(&cb.buf, 20);
1066
1067         retval = 0;
1068         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1069                 strbuf_reset(buf);
1070                 strbuf_addbuf(buf, &cb.buf);
1071                 retval = brace - name + 1;
1072         }
1073
1074         strbuf_release(&cb.buf);
1075         return retval;
1076 }
1077
1078 int get_oid_mb(const char *name, struct object_id *oid)
1079 {
1080         struct commit *one, *two;
1081         struct commit_list *mbs;
1082         struct object_id oid_tmp;
1083         const char *dots;
1084         int st;
1085
1086         dots = strstr(name, "...");
1087         if (!dots)
1088                 return get_oid(name, oid);
1089         if (dots == name)
1090                 st = get_oid("HEAD", &oid_tmp);
1091         else {
1092                 struct strbuf sb;
1093                 strbuf_init(&sb, dots - name);
1094                 strbuf_add(&sb, name, dots - name);
1095                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1096                 strbuf_release(&sb);
1097         }
1098         if (st)
1099                 return st;
1100         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1101         if (!one)
1102                 return -1;
1103
1104         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1105                 return -1;
1106         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1107         if (!two)
1108                 return -1;
1109         mbs = get_merge_bases(one, two);
1110         if (!mbs || mbs->next)
1111                 st = -1;
1112         else {
1113                 st = 0;
1114                 oidcpy(oid, &mbs->item->object.oid);
1115         }
1116         free_commit_list(mbs);
1117         return st;
1118 }
1119
1120 /* parse @something syntax, when 'something' is not {.*} */
1121 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1122 {
1123         const char *next;
1124
1125         if (len || name[1] == '{')
1126                 return -1;
1127
1128         /* make sure it's a single @, or @@{.*}, not @foo */
1129         next = memchr(name + len + 1, '@', namelen - len - 1);
1130         if (next && next[1] != '{')
1131                 return -1;
1132         if (!next)
1133                 next = name + namelen;
1134         if (next != name + 1)
1135                 return -1;
1136
1137         strbuf_reset(buf);
1138         strbuf_add(buf, "HEAD", 4);
1139         return 1;
1140 }
1141
1142 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1143 {
1144         /* we have extra data, which might need further processing */
1145         struct strbuf tmp = STRBUF_INIT;
1146         int used = buf->len;
1147         int ret;
1148
1149         strbuf_add(buf, name + len, namelen - len);
1150         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1151         /* that data was not interpreted, remove our cruft */
1152         if (ret < 0) {
1153                 strbuf_setlen(buf, used);
1154                 return len;
1155         }
1156         strbuf_reset(buf);
1157         strbuf_addbuf(buf, &tmp);
1158         strbuf_release(&tmp);
1159         /* tweak for size of {-N} versus expanded ref name */
1160         return ret - used + len;
1161 }
1162
1163 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1164 {
1165         char *s = shorten_unambiguous_ref(ref, 0);
1166         strbuf_reset(buf);
1167         strbuf_addstr(buf, s);
1168         free(s);
1169 }
1170
1171 static int interpret_branch_mark(const char *name, int namelen,
1172                                  int at, struct strbuf *buf,
1173                                  int (*get_mark)(const char *, int),
1174                                  const char *(*get_data)(struct branch *,
1175                                                          struct strbuf *))
1176 {
1177         int len;
1178         struct branch *branch;
1179         struct strbuf err = STRBUF_INIT;
1180         const char *value;
1181
1182         len = get_mark(name + at, namelen - at);
1183         if (!len)
1184                 return -1;
1185
1186         if (memchr(name, ':', at))
1187                 return -1;
1188
1189         if (at) {
1190                 char *name_str = xmemdupz(name, at);
1191                 branch = branch_get(name_str);
1192                 free(name_str);
1193         } else
1194                 branch = branch_get(NULL);
1195
1196         value = get_data(branch, &err);
1197         if (!value)
1198                 die("%s", err.buf);
1199
1200         set_shortened_ref(buf, value);
1201         return len + at;
1202 }
1203
1204 /*
1205  * This reads short-hand syntax that not only evaluates to a commit
1206  * object name, but also can act as if the end user spelled the name
1207  * of the branch from the command line.
1208  *
1209  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1210  *   places the name of the branch in the given buf and returns the
1211  *   number of characters parsed if successful.
1212  *
1213  * - "<branch>@{upstream}" finds the name of the other ref that
1214  *   <branch> is configured to merge with (missing <branch> defaults
1215  *   to the current branch), and places the name of the branch in the
1216  *   given buf and returns the number of characters parsed if
1217  *   successful.
1218  *
1219  * If the input is not of the accepted format, it returns a negative
1220  * number to signal an error.
1221  *
1222  * If the input was ok but there are not N branch switches in the
1223  * reflog, it returns 0.
1224  */
1225 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1226 {
1227         char *at;
1228         const char *start;
1229         int len = interpret_nth_prior_checkout(name, namelen, buf);
1230
1231         if (!namelen)
1232                 namelen = strlen(name);
1233
1234         if (!len) {
1235                 return len; /* syntax Ok, not enough switches */
1236         } else if (len > 0) {
1237                 if (len == namelen)
1238                         return len; /* consumed all */
1239                 else
1240                         return reinterpret(name, namelen, len, buf);
1241         }
1242
1243         for (start = name;
1244              (at = memchr(start, '@', namelen - (start - name)));
1245              start = at + 1) {
1246
1247                 len = interpret_empty_at(name, namelen, at - name, buf);
1248                 if (len > 0)
1249                         return reinterpret(name, namelen, len, buf);
1250
1251                 len = interpret_branch_mark(name, namelen, at - name, buf,
1252                                             upstream_mark, branch_get_upstream);
1253                 if (len > 0)
1254                         return len;
1255
1256                 len = interpret_branch_mark(name, namelen, at - name, buf,
1257                                             push_mark, branch_get_push);
1258                 if (len > 0)
1259                         return len;
1260         }
1261
1262         return -1;
1263 }
1264
1265 int strbuf_branchname(struct strbuf *sb, const char *name)
1266 {
1267         int len = strlen(name);
1268         int used = interpret_branch_name(name, len, sb);
1269
1270         if (used == len)
1271                 return 0;
1272         if (used < 0)
1273                 used = 0;
1274         strbuf_add(sb, name + used, len - used);
1275         return len;
1276 }
1277
1278 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1279 {
1280         strbuf_branchname(sb, name);
1281         if (name[0] == '-')
1282                 return -1;
1283         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1284         return check_refname_format(sb->buf, 0);
1285 }
1286
1287 /*
1288  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1289  * notably "xyz^" for "parent of xyz"
1290  */
1291 int get_sha1(const char *name, unsigned char *sha1)
1292 {
1293         struct object_context unused;
1294         return get_sha1_with_context(name, 0, sha1, &unused);
1295 }
1296
1297 /*
1298  * This is like "get_sha1()", but for struct object_id.
1299  */
1300 int get_oid(const char *name, struct object_id *oid)
1301 {
1302         return get_sha1(name, oid->hash);
1303 }
1304
1305
1306 /*
1307  * Many callers know that the user meant to name a commit-ish by
1308  * syntactical positions where the object name appears.  Calling this
1309  * function allows the machinery to disambiguate shorter-than-unique
1310  * abbreviated object names between commit-ish and others.
1311  *
1312  * Note that this does NOT error out when the named object is not a
1313  * commit-ish. It is merely to give a hint to the disambiguation
1314  * machinery.
1315  */
1316 int get_sha1_committish(const char *name, unsigned char *sha1)
1317 {
1318         struct object_context unused;
1319         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1320                                      sha1, &unused);
1321 }
1322
1323 int get_sha1_treeish(const char *name, unsigned char *sha1)
1324 {
1325         struct object_context unused;
1326         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1327                                      sha1, &unused);
1328 }
1329
1330 int get_sha1_commit(const char *name, unsigned char *sha1)
1331 {
1332         struct object_context unused;
1333         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1334                                      sha1, &unused);
1335 }
1336
1337 int get_sha1_tree(const char *name, unsigned char *sha1)
1338 {
1339         struct object_context unused;
1340         return get_sha1_with_context(name, GET_SHA1_TREE,
1341                                      sha1, &unused);
1342 }
1343
1344 int get_sha1_blob(const char *name, unsigned char *sha1)
1345 {
1346         struct object_context unused;
1347         return get_sha1_with_context(name, GET_SHA1_BLOB,
1348                                      sha1, &unused);
1349 }
1350
1351 /* Must be called only when object_name:filename doesn't exist. */
1352 static void diagnose_invalid_sha1_path(const char *prefix,
1353                                        const char *filename,
1354                                        const unsigned char *tree_sha1,
1355                                        const char *object_name,
1356                                        int object_name_len)
1357 {
1358         unsigned char sha1[20];
1359         unsigned mode;
1360
1361         if (!prefix)
1362                 prefix = "";
1363
1364         if (file_exists(filename))
1365                 die("Path '%s' exists on disk, but not in '%.*s'.",
1366                     filename, object_name_len, object_name);
1367         if (errno == ENOENT || errno == ENOTDIR) {
1368                 char *fullname = xstrfmt("%s%s", prefix, filename);
1369
1370                 if (!get_tree_entry(tree_sha1, fullname,
1371                                     sha1, &mode)) {
1372                         die("Path '%s' exists, but not '%s'.\n"
1373                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1374                             fullname,
1375                             filename,
1376                             object_name_len, object_name,
1377                             fullname,
1378                             object_name_len, object_name,
1379                             filename);
1380                 }
1381                 die("Path '%s' does not exist in '%.*s'",
1382                     filename, object_name_len, object_name);
1383         }
1384 }
1385
1386 /* Must be called only when :stage:filename doesn't exist. */
1387 static void diagnose_invalid_index_path(int stage,
1388                                         const char *prefix,
1389                                         const char *filename)
1390 {
1391         const struct cache_entry *ce;
1392         int pos;
1393         unsigned namelen = strlen(filename);
1394         struct strbuf fullname = STRBUF_INIT;
1395
1396         if (!prefix)
1397                 prefix = "";
1398
1399         /* Wrong stage number? */
1400         pos = cache_name_pos(filename, namelen);
1401         if (pos < 0)
1402                 pos = -pos - 1;
1403         if (pos < active_nr) {
1404                 ce = active_cache[pos];
1405                 if (ce_namelen(ce) == namelen &&
1406                     !memcmp(ce->name, filename, namelen))
1407                         die("Path '%s' is in the index, but not at stage %d.\n"
1408                             "Did you mean ':%d:%s'?",
1409                             filename, stage,
1410                             ce_stage(ce), filename);
1411         }
1412
1413         /* Confusion between relative and absolute filenames? */
1414         strbuf_addstr(&fullname, prefix);
1415         strbuf_addstr(&fullname, filename);
1416         pos = cache_name_pos(fullname.buf, fullname.len);
1417         if (pos < 0)
1418                 pos = -pos - 1;
1419         if (pos < active_nr) {
1420                 ce = active_cache[pos];
1421                 if (ce_namelen(ce) == fullname.len &&
1422                     !memcmp(ce->name, fullname.buf, fullname.len))
1423                         die("Path '%s' is in the index, but not '%s'.\n"
1424                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1425                             fullname.buf, filename,
1426                             ce_stage(ce), fullname.buf,
1427                             ce_stage(ce), filename);
1428         }
1429
1430         if (file_exists(filename))
1431                 die("Path '%s' exists on disk, but not in the index.", filename);
1432         if (errno == ENOENT || errno == ENOTDIR)
1433                 die("Path '%s' does not exist (neither on disk nor in the index).",
1434                     filename);
1435
1436         strbuf_release(&fullname);
1437 }
1438
1439
1440 static char *resolve_relative_path(const char *rel)
1441 {
1442         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1443                 return NULL;
1444
1445         if (!is_inside_work_tree())
1446                 die("relative path syntax can't be used outside working tree.");
1447
1448         /* die() inside prefix_path() if resolved path is outside worktree */
1449         return prefix_path(startup_info->prefix,
1450                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1451                            rel);
1452 }
1453
1454 static int get_sha1_with_context_1(const char *name,
1455                                    unsigned flags,
1456                                    const char *prefix,
1457                                    unsigned char *sha1,
1458                                    struct object_context *oc)
1459 {
1460         int ret, bracket_depth;
1461         int namelen = strlen(name);
1462         const char *cp;
1463         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1464
1465         if (only_to_die)
1466                 flags |= GET_SHA1_QUIETLY;
1467
1468         memset(oc, 0, sizeof(*oc));
1469         oc->mode = S_IFINVALID;
1470         ret = get_sha1_1(name, namelen, sha1, flags);
1471         if (!ret)
1472                 return ret;
1473         /*
1474          * sha1:path --> object name of path in ent sha1
1475          * :path -> object name of absolute path in index
1476          * :./path -> object name of path relative to cwd in index
1477          * :[0-3]:path -> object name of path in index at stage
1478          * :/foo -> recent commit matching foo
1479          */
1480         if (name[0] == ':') {
1481                 int stage = 0;
1482                 const struct cache_entry *ce;
1483                 char *new_path = NULL;
1484                 int pos;
1485                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1486                         struct commit_list *list = NULL;
1487
1488                         for_each_ref(handle_one_ref, &list);
1489                         commit_list_sort_by_date(&list);
1490                         return get_sha1_oneline(name + 2, sha1, list);
1491                 }
1492                 if (namelen < 3 ||
1493                     name[2] != ':' ||
1494                     name[1] < '0' || '3' < name[1])
1495                         cp = name + 1;
1496                 else {
1497                         stage = name[1] - '0';
1498                         cp = name + 3;
1499                 }
1500                 new_path = resolve_relative_path(cp);
1501                 if (!new_path) {
1502                         namelen = namelen - (cp - name);
1503                 } else {
1504                         cp = new_path;
1505                         namelen = strlen(cp);
1506                 }
1507
1508                 strlcpy(oc->path, cp, sizeof(oc->path));
1509
1510                 if (!active_cache)
1511                         read_cache();
1512                 pos = cache_name_pos(cp, namelen);
1513                 if (pos < 0)
1514                         pos = -pos - 1;
1515                 while (pos < active_nr) {
1516                         ce = active_cache[pos];
1517                         if (ce_namelen(ce) != namelen ||
1518                             memcmp(ce->name, cp, namelen))
1519                                 break;
1520                         if (ce_stage(ce) == stage) {
1521                                 hashcpy(sha1, ce->oid.hash);
1522                                 oc->mode = ce->ce_mode;
1523                                 free(new_path);
1524                                 return 0;
1525                         }
1526                         pos++;
1527                 }
1528                 if (only_to_die && name[1] && name[1] != '/')
1529                         diagnose_invalid_index_path(stage, prefix, cp);
1530                 free(new_path);
1531                 return -1;
1532         }
1533         for (cp = name, bracket_depth = 0; *cp; cp++) {
1534                 if (*cp == '{')
1535                         bracket_depth++;
1536                 else if (bracket_depth && *cp == '}')
1537                         bracket_depth--;
1538                 else if (!bracket_depth && *cp == ':')
1539                         break;
1540         }
1541         if (*cp == ':') {
1542                 unsigned char tree_sha1[20];
1543                 int len = cp - name;
1544                 unsigned sub_flags = flags;
1545
1546                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1547                 sub_flags |= GET_SHA1_TREEISH;
1548
1549                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1550                         const char *filename = cp+1;
1551                         char *new_filename = NULL;
1552
1553                         new_filename = resolve_relative_path(filename);
1554                         if (new_filename)
1555                                 filename = new_filename;
1556                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1557                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1558                                         filename, sha1, &oc->symlink_path,
1559                                         &oc->mode);
1560                         } else {
1561                                 ret = get_tree_entry(tree_sha1, filename,
1562                                                      sha1, &oc->mode);
1563                                 if (ret && only_to_die) {
1564                                         diagnose_invalid_sha1_path(prefix,
1565                                                                    filename,
1566                                                                    tree_sha1,
1567                                                                    name, len);
1568                                 }
1569                         }
1570                         hashcpy(oc->tree, tree_sha1);
1571                         strlcpy(oc->path, filename, sizeof(oc->path));
1572
1573                         free(new_filename);
1574                         return ret;
1575                 } else {
1576                         if (only_to_die)
1577                                 die("Invalid object name '%.*s'.", len, name);
1578                 }
1579         }
1580         return ret;
1581 }
1582
1583 /*
1584  * Call this function when you know "name" given by the end user must
1585  * name an object but it doesn't; the function _may_ die with a better
1586  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1587  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1588  * you have a chance to diagnose the error further.
1589  */
1590 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1591 {
1592         struct object_context oc;
1593         unsigned char sha1[20];
1594         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1595 }
1596
1597 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1598 {
1599         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1600                 die("BUG: incompatible flags for get_sha1_with_context");
1601         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1602 }