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 char hex[GIT_SHA1_HEXSZ + 1];
 476         find_unique_abbrev_r(hex, sha1, len);
 477         return hex;
 478 }
 479
 480 static int ambiguous_path(const char *path, int len)
 481 {
 482         int slash = 1;
 483         int cnt;
 484
 485         for (cnt = 0; cnt < len; cnt++) {
 486                 switch (*path++) {
 487                 case '\0':
 488                         break;
 489                 case '/':
 490                         if (slash)
 491                                 break;
 492                         slash = 1;
 493                         continue;
 494                 case '.':
 495                         continue;
 496                 default:
 497                         slash = 0;
 498                         continue;
 499                 }
 500                 break;
 501         }
 502         return slash;
 503 }
 504
 505 static inline int at_mark(const char *string, int len,
 506                           const char **suffix, int nr)
 507 {
 508         int i;
 509
 510         for (i = 0; i < nr; i++) {
 511                 int suffix_len = strlen(suffix[i]);
 512                 if (suffix_len <= len
 513                     && !memcmp(string, suffix[i], suffix_len))
 514                         return suffix_len;
 515         }
 516         return 0;
 517 }
 518
 519 static inline int upstream_mark(const char *string, int len)
 520 {
 521         const char *suffix[] = { "@{upstream}", "@{u}" };
 522         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 523 }
 524
 525 static inline int push_mark(const char *string, int len)
 526 {
 527         const char *suffix[] = { "@{push}" };
 528         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 529 }
 530
 531 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 532 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 533
 534 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 535                           unsigned int flags)
 536 {
 537         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 538         static const char *object_name_msg = N_(
 539         "Git normally never creates a ref that ends with 40 hex characters\n"
 540         "because it will be ignored when you just specify 40-hex. These refs\n"
 541         "may be created by mistake. For example,\n"
 542         "\n"
 543         "  git checkout -b $br $(git rev-parse ...)\n"
 544         "\n"
 545         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 546         "examine these refs and maybe delete them. Turn this message off by\n"
 547         "running \"git config advice.objectNameWarning false\"");
 548         unsigned char tmp_sha1[20];
 549         char *real_ref = NULL;
 550         int refs_found = 0;
 551         int at, reflog_len, nth_prior = 0;
 552
 553         if (len == 40 && !get_sha1_hex(str, sha1)) {
 554                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 555                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 556                         if (refs_found > 0) {
 557                                 warning(warn_msg, len, str);
 558                                 if (advice_object_name_warning)
 559                                         fprintf(stderr, "%s\n", _(object_name_msg));
 560                         }
 561                         free(real_ref);
 562                 }
 563                 return 0;
 564         }
 565
 566         /* basic@{time or number or -number} format to query ref-log */
 567         reflog_len = at = 0;
 568         if (len && str[len-1] == '}') {
 569                 for (at = len-4; at >= 0; at--) {
 570                         if (str[at] == '@' && str[at+1] == '{') {
 571                                 if (str[at+2] == '-') {
 572                                         if (at != 0)
 573                                                 /* @{-N} not at start */
 574                                                 return -1;
 575                                         nth_prior = 1;
 576                                         continue;
 577                                 }
 578                                 if (!upstream_mark(str + at, len - at) &&
 579                                     !push_mark(str + at, len - at)) {
 580                                         reflog_len = (len-1) - (at+2);
 581                                         len = at;
 582                                 }
 583                                 break;
 584                         }
 585                 }
 586         }
 587
 588         /* Accept only unambiguous ref paths. */
 589         if (len && ambiguous_path(str, len))
 590                 return -1;
 591
 592         if (nth_prior) {
 593                 struct strbuf buf = STRBUF_INIT;
 594                 int detached;
 595
 596                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 597                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 598                         strbuf_release(&buf);
 599                         if (detached)
 600                                 return 0;
 601                 }
 602         }
 603
 604         if (!len && reflog_len)
 605                 /* allow "@{...}" to mean the current branch reflog */
 606                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 607         else if (reflog_len)
 608                 refs_found = dwim_log(str, len, sha1, &real_ref);
 609         else
 610                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 611
 612         if (!refs_found)
 613                 return -1;
 614
 615         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 616             (refs_found > 1 ||
 617              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 618                 warning(warn_msg, len, str);
 619
 620         if (reflog_len) {
 621                 int nth, i;
 622                 unsigned long at_time;
 623                 unsigned long co_time;
 624                 int co_tz, co_cnt;
 625
 626                 /* Is it asking for N-th entry, or approxidate? */
 627                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 628                         char ch = str[at+2+i];
 629                         if ('0' <= ch && ch <= '9')
 630                                 nth = nth * 10 + ch - '0';
 631                         else
 632                                 nth = -1;
 633                 }
 634                 if (100000000 <= nth) {
 635                         at_time = nth;
 636                         nth = -1;
 637                 } else if (0 <= nth)
 638                         at_time = 0;
 639                 else {
 640                         int errors = 0;
 641                         char *tmp = xstrndup(str + at + 2, reflog_len);
 642                         at_time = approxidate_careful(tmp, &errors);
 643                         free(tmp);
 644                         if (errors) {
 645                                 free(real_ref);
 646                                 return -1;
 647                         }
 648                 }
 649                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 650                                 &co_time, &co_tz, &co_cnt)) {
 651                         if (!len) {
 652                                 if (starts_with(real_ref, "refs/heads/")) {
 653                                         str = real_ref + 11;
 654                                         len = strlen(real_ref + 11);
 655                                 } else {
 656                                         /* detached HEAD */
 657                                         str = "HEAD";
 658                                         len = 4;
 659                                 }
 660                         }
 661                         if (at_time) {
 662                                 if (!(flags & GET_SHA1_QUIETLY)) {
 663                                         warning("Log for '%.*s' only goes "
 664                                                 "back to %s.", len, str,
 665                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 666                                 }
 667                         } else {
 668                                 if (flags & GET_SHA1_QUIETLY) {
 669                                         exit(128);
 670                                 }
 671                                 die("Log for '%.*s' only has %d entries.",
 672                                     len, str, co_cnt);
 673                         }
 674                 }
 675         }
 676
 677         free(real_ref);
 678         return 0;
 679 }
 680
 681 static int get_parent(const char *name, int len,
 682                       unsigned char *result, int idx)
 683 {
 684         unsigned char sha1[20];
 685         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 686         struct commit *commit;
 687         struct commit_list *p;
 688
 689         if (ret)
 690                 return ret;
 691         commit = lookup_commit_reference(sha1);
 692         if (parse_commit(commit))
 693                 return -1;
 694         if (!idx) {
 695                 hashcpy(result, commit->object.oid.hash);
 696                 return 0;
 697         }
 698         p = commit->parents;
 699         while (p) {
 700                 if (!--idx) {
 701                         hashcpy(result, p->item->object.oid.hash);
 702                         return 0;
 703                 }
 704                 p = p->next;
 705         }
 706         return -1;
 707 }
 708
 709 static int get_nth_ancestor(const char *name, int len,
 710                             unsigned char *result, int generation)
 711 {
 712         unsigned char sha1[20];
 713         struct commit *commit;
 714         int ret;
 715
 716         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 717         if (ret)
 718                 return ret;
 719         commit = lookup_commit_reference(sha1);
 720         if (!commit)
 721                 return -1;
 722
 723         while (generation--) {
 724                 if (parse_commit(commit) || !commit->parents)
 725                         return -1;
 726                 commit = commit->parents->item;
 727         }
 728         hashcpy(result, commit->object.oid.hash);
 729         return 0;
 730 }
 731
 732 struct object *peel_to_type(const char *name, int namelen,
 733                             struct object *o, enum object_type expected_type)
 734 {
 735         if (name && !namelen)
 736                 namelen = strlen(name);
 737         while (1) {
 738                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 739                         return NULL;
 740                 if (expected_type == OBJ_ANY || o->type == expected_type)
 741                         return o;
 742                 if (o->type == OBJ_TAG)
 743                         o = ((struct tag*) o)->tagged;
 744                 else if (o->type == OBJ_COMMIT)
 745                         o = &(((struct commit *) o)->tree->object);
 746                 else {
 747                         if (name)
 748                                 error("%.*s: expected %s type, but the object "
 749                                       "dereferences to %s type",
 750                                       namelen, name, typename(expected_type),
 751                                       typename(o->type));
 752                         return NULL;
 753                 }
 754         }
 755 }
 756
 757 static int peel_onion(const char *name, int len, unsigned char *sha1,
 758                       unsigned lookup_flags)
 759 {
 760         unsigned char outer[20];
 761         const char *sp;
 762         unsigned int expected_type = 0;
 763         struct object *o;
 764
 765         /*
 766          * "ref^{type}" dereferences ref repeatedly until you cannot
 767          * dereference anymore, or you get an object of given type,
 768          * whichever comes first.  "ref^{}" means just dereference
 769          * tags until you get a non-tag.  "ref^0" is a shorthand for
 770          * "ref^{commit}".  "commit^{tree}" could be used to find the
 771          * top-level tree of the given commit.
 772          */
 773         if (len < 4 || name[len-1] != '}')
 774                 return -1;
 775
 776         for (sp = name + len - 1; name <= sp; sp--) {
 777                 int ch = *sp;
 778                 if (ch == '{' && name < sp && sp[-1] == '^')
 779                         break;
 780         }
 781         if (sp <= name)
 782                 return -1;
 783
 784         sp++; /* beginning of type name, or closing brace for empty */
 785         if (starts_with(sp, "commit}"))
 786                 expected_type = OBJ_COMMIT;
 787         else if (starts_with(sp, "tag}"))
 788                 expected_type = OBJ_TAG;
 789         else if (starts_with(sp, "tree}"))
 790                 expected_type = OBJ_TREE;
 791         else if (starts_with(sp, "blob}"))
 792                 expected_type = OBJ_BLOB;
 793         else if (starts_with(sp, "object}"))
 794                 expected_type = OBJ_ANY;
 795         else if (sp[0] == '}')
 796                 expected_type = OBJ_NONE;
 797         else if (sp[0] == '/')
 798                 expected_type = OBJ_COMMIT;
 799         else
 800                 return -1;
 801
 802         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 803         if (expected_type == OBJ_COMMIT)
 804                 lookup_flags |= GET_SHA1_COMMITTISH;
 805         else if (expected_type == OBJ_TREE)
 806                 lookup_flags |= GET_SHA1_TREEISH;
 807
 808         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 809                 return -1;
 810
 811         o = parse_object(outer);
 812         if (!o)
 813                 return -1;
 814         if (!expected_type) {
 815                 o = deref_tag(o, name, sp - name - 2);
 816                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 817                         return -1;
 818                 hashcpy(sha1, o->oid.hash);
 819                 return 0;
 820         }
 821
 822         /*
 823          * At this point, the syntax look correct, so
 824          * if we do not get the needed object, we should
 825          * barf.
 826          */
 827         o = peel_to_type(name, len, o, expected_type);
 828         if (!o)
 829                 return -1;
 830
 831         hashcpy(sha1, o->oid.hash);
 832         if (sp[0] == '/') {
 833                 /* "$commit^{/foo}" */
 834                 char *prefix;
 835                 int ret;
 836                 struct commit_list *list = NULL;
 837
 838                 /*
 839                  * $commit^{/}. Some regex implementation may reject.
 840                  * We don't need regex anyway. '' pattern always matches.
 841                  */
 842                 if (sp[1] == '}')
 843                         return 0;
 844
 845                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 846                 commit_list_insert((struct commit *)o, &list);
 847                 ret = get_sha1_oneline(prefix, sha1, list);
 848                 free(prefix);
 849                 return ret;
 850         }
 851         return 0;
 852 }
 853
 854 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 855 {
 856         const char *cp;
 857         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 858
 859         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 860                 char ch = *cp;
 861                 if (!isxdigit(ch)) {
 862                         /* We must be looking at g in "SOMETHING-g"
 863                          * for it to be describe output.
 864                          */
 865                         if (ch == 'g' && cp[-1] == '-') {
 866                                 cp++;
 867                                 len -= cp - name;
 868                                 return get_short_sha1(cp, len, sha1, flags);
 869                         }
 870                 }
 871         }
 872         return -1;
 873 }
 874
 875 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 876 {
 877         int ret, has_suffix;
 878         const char *cp;
 879
 880         /*
 881          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 882          */
 883         has_suffix = 0;
 884         for (cp = name + len - 1; name <= cp; cp--) {
 885                 int ch = *cp;
 886                 if ('0' <= ch && ch <= '9')
 887                         continue;
 888                 if (ch == '~' || ch == '^')
 889                         has_suffix = ch;
 890                 break;
 891         }
 892
 893         if (has_suffix) {
 894                 int num = 0;
 895                 int len1 = cp - name;
 896                 cp++;
 897                 while (cp < name + len)
 898                         num = num * 10 + *cp++ - '0';
 899                 if (!num && len1 == len - 1)
 900                         num = 1;
 901                 if (has_suffix == '^')
 902                         return get_parent(name, len1, sha1, num);
 903                 /* else if (has_suffix == '~') -- goes without saying */
 904                 return get_nth_ancestor(name, len1, sha1, num);
 905         }
 906
 907         ret = peel_onion(name, len, sha1, lookup_flags);
 908         if (!ret)
 909                 return 0;
 910
 911         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 912         if (!ret)
 913                 return 0;
 914
 915         /* It could be describe output that is "SOMETHING-gXXXX" */
 916         ret = get_describe_name(name, len, sha1);
 917         if (!ret)
 918                 return 0;
 919
 920         return get_short_sha1(name, len, sha1, lookup_flags);
 921 }
 922
 923 /*
 924  * This interprets names like ':/Initial revision of "git"' by searching
 925  * through history and returning the first commit whose message starts
 926  * the given regular expression.
 927  *
 928  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 929  *
 930  * For a literal '!' character at the beginning of a pattern, you have to repeat
 931  * that, like: ':/!!foo'
 932  *
 933  * For future extension, all other sequences beginning with ':/!' are reserved.
 934  */
 935
 936 /* Remember to update object flag allocation in object.h */
 937 #define ONELINE_SEEN (1u<<20)
 938
 939 static int handle_one_ref(const char *path, const struct object_id *oid,
 940                           int flag, void *cb_data)
 941 {
 942         struct commit_list **list = cb_data;
 943         struct object *object = parse_object(oid->hash);
 944         if (!object)
 945                 return 0;
 946         if (object->type == OBJ_TAG) {
 947                 object = deref_tag(object, path, strlen(path));
 948                 if (!object)
 949                         return 0;
 950         }
 951         if (object->type != OBJ_COMMIT)
 952                 return 0;
 953         commit_list_insert((struct commit *)object, list);
 954         return 0;
 955 }
 956
 957 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 958                             struct commit_list *list)
 959 {
 960         struct commit_list *backup = NULL, *l;
 961         int found = 0;
 962         int negative = 0;
 963         regex_t regex;
 964
 965         if (prefix[0] == '!') {
 966                 prefix++;
 967
 968                 if (prefix[0] == '-') {
 969                         prefix++;
 970                         negative = 1;
 971                 } else if (prefix[0] != '!') {
 972                         return -1;
 973                 }
 974         }
 975
 976         if (regcomp(&regex, prefix, REG_EXTENDED))
 977                 return -1;
 978
 979         for (l = list; l; l = l->next) {
 980                 l->item->object.flags |= ONELINE_SEEN;
 981                 commit_list_insert(l->item, &backup);
 982         }
 983         while (list) {
 984                 const char *p, *buf;
 985                 struct commit *commit;
 986                 int matches;
 987
 988                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 989                 if (!parse_object(commit->object.oid.hash))
 990                         continue;
 991                 buf = get_commit_buffer(commit, NULL);
 992                 p = strstr(buf, "\n\n");
 993                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
 994                 unuse_commit_buffer(commit, buf);
 995
 996                 if (matches) {
 997                         hashcpy(sha1, commit->object.oid.hash);
 998                         found = 1;
 999                         break;
1000                 }
1001         }
1002         regfree(&regex);
1003         free_commit_list(list);
1004         for (l = backup; l; l = l->next)
1005                 clear_commit_marks(l->item, ONELINE_SEEN);
1006         free_commit_list(backup);
1007         return found ? 0 : -1;
1008 }
1009
1010 struct grab_nth_branch_switch_cbdata {
1011         int remaining;
1012         struct strbuf buf;
1013 };
1014
1015 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
1016                                   const char *email, unsigned long timestamp, int tz,
1017                                   const char *message, void *cb_data)
1018 {
1019         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1020         const char *match = NULL, *target = NULL;
1021         size_t len;
1022
1023         if (skip_prefix(message, "checkout: moving from ", &match))
1024                 target = strstr(match, " to ");
1025
1026         if (!match || !target)
1027                 return 0;
1028         if (--(cb->remaining) == 0) {
1029                 len = target - match;
1030                 strbuf_reset(&cb->buf);
1031                 strbuf_add(&cb->buf, match, len);
1032                 return 1; /* we are done */
1033         }
1034         return 0;
1035 }
1036
1037 /*
1038  * Parse @{-N} syntax, return the number of characters parsed
1039  * if successful; otherwise signal an error with negative value.
1040  */
1041 static int interpret_nth_prior_checkout(const char *name, int namelen,
1042                                         struct strbuf *buf)
1043 {
1044         long nth;
1045         int retval;
1046         struct grab_nth_branch_switch_cbdata cb;
1047         const char *brace;
1048         char *num_end;
1049
1050         if (namelen < 4)
1051                 return -1;
1052         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1053                 return -1;
1054         brace = memchr(name, '}', namelen);
1055         if (!brace)
1056                 return -1;
1057         nth = strtol(name + 3, &num_end, 10);
1058         if (num_end != brace)
1059                 return -1;
1060         if (nth <= 0)
1061                 return -1;
1062         cb.remaining = nth;
1063         strbuf_init(&cb.buf, 20);
1064
1065         retval = 0;
1066         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1067                 strbuf_reset(buf);
1068                 strbuf_addbuf(buf, &cb.buf);
1069                 retval = brace - name + 1;
1070         }
1071
1072         strbuf_release(&cb.buf);
1073         return retval;
1074 }
1075
1076 int get_oid_mb(const char *name, struct object_id *oid)
1077 {
1078         struct commit *one, *two;
1079         struct commit_list *mbs;
1080         struct object_id oid_tmp;
1081         const char *dots;
1082         int st;
1083
1084         dots = strstr(name, "...");
1085         if (!dots)
1086                 return get_oid(name, oid);
1087         if (dots == name)
1088                 st = get_oid("HEAD", &oid_tmp);
1089         else {
1090                 struct strbuf sb;
1091                 strbuf_init(&sb, dots - name);
1092                 strbuf_add(&sb, name, dots - name);
1093                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1094                 strbuf_release(&sb);
1095         }
1096         if (st)
1097                 return st;
1098         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1099         if (!one)
1100                 return -1;
1101
1102         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1103                 return -1;
1104         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1105         if (!two)
1106                 return -1;
1107         mbs = get_merge_bases(one, two);
1108         if (!mbs || mbs->next)
1109                 st = -1;
1110         else {
1111                 st = 0;
1112                 oidcpy(oid, &mbs->item->object.oid);
1113         }
1114         free_commit_list(mbs);
1115         return st;
1116 }
1117
1118 /* parse @something syntax, when 'something' is not {.*} */
1119 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1120 {
1121         const char *next;
1122
1123         if (len || name[1] == '{')
1124                 return -1;
1125
1126         /* make sure it's a single @, or @@{.*}, not @foo */
1127         next = memchr(name + len + 1, '@', namelen - len - 1);
1128         if (next && next[1] != '{')
1129                 return -1;
1130         if (!next)
1131                 next = name + namelen;
1132         if (next != name + 1)
1133                 return -1;
1134
1135         strbuf_reset(buf);
1136         strbuf_add(buf, "HEAD", 4);
1137         return 1;
1138 }
1139
1140 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1141 {
1142         /* we have extra data, which might need further processing */
1143         struct strbuf tmp = STRBUF_INIT;
1144         int used = buf->len;
1145         int ret;
1146
1147         strbuf_add(buf, name + len, namelen - len);
1148         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1149         /* that data was not interpreted, remove our cruft */
1150         if (ret < 0) {
1151                 strbuf_setlen(buf, used);
1152                 return len;
1153         }
1154         strbuf_reset(buf);
1155         strbuf_addbuf(buf, &tmp);
1156         strbuf_release(&tmp);
1157         /* tweak for size of {-N} versus expanded ref name */
1158         return ret - used + len;
1159 }
1160
1161 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1162 {
1163         char *s = shorten_unambiguous_ref(ref, 0);
1164         strbuf_reset(buf);
1165         strbuf_addstr(buf, s);
1166         free(s);
1167 }
1168
1169 static int interpret_branch_mark(const char *name, int namelen,
1170                                  int at, struct strbuf *buf,
1171                                  int (*get_mark)(const char *, int),
1172                                  const char *(*get_data)(struct branch *,
1173                                                          struct strbuf *))
1174 {
1175         int len;
1176         struct branch *branch;
1177         struct strbuf err = STRBUF_INIT;
1178         const char *value;
1179
1180         len = get_mark(name + at, namelen - at);
1181         if (!len)
1182                 return -1;
1183
1184         if (memchr(name, ':', at))
1185                 return -1;
1186
1187         if (at) {
1188                 char *name_str = xmemdupz(name, at);
1189                 branch = branch_get(name_str);
1190                 free(name_str);
1191         } else
1192                 branch = branch_get(NULL);
1193
1194         value = get_data(branch, &err);
1195         if (!value)
1196                 die("%s", err.buf);
1197
1198         set_shortened_ref(buf, value);
1199         return len + at;
1200 }
1201
1202 /*
1203  * This reads short-hand syntax that not only evaluates to a commit
1204  * object name, but also can act as if the end user spelled the name
1205  * of the branch from the command line.
1206  *
1207  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1208  *   places the name of the branch in the given buf and returns the
1209  *   number of characters parsed if successful.
1210  *
1211  * - "<branch>@{upstream}" finds the name of the other ref that
1212  *   <branch> is configured to merge with (missing <branch> defaults
1213  *   to the current branch), and places the name of the branch in the
1214  *   given buf and returns the number of characters parsed if
1215  *   successful.
1216  *
1217  * If the input is not of the accepted format, it returns a negative
1218  * number to signal an error.
1219  *
1220  * If the input was ok but there are not N branch switches in the
1221  * reflog, it returns 0.
1222  */
1223 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1224 {
1225         char *at;
1226         const char *start;
1227         int len = interpret_nth_prior_checkout(name, namelen, buf);
1228
1229         if (!namelen)
1230                 namelen = strlen(name);
1231
1232         if (!len) {
1233                 return len; /* syntax Ok, not enough switches */
1234         } else if (len > 0) {
1235                 if (len == namelen)
1236                         return len; /* consumed all */
1237                 else
1238                         return reinterpret(name, namelen, len, buf);
1239         }
1240
1241         for (start = name;
1242              (at = memchr(start, '@', namelen - (start - name)));
1243              start = at + 1) {
1244
1245                 len = interpret_empty_at(name, namelen, at - name, buf);
1246                 if (len > 0)
1247                         return reinterpret(name, namelen, len, buf);
1248
1249                 len = interpret_branch_mark(name, namelen, at - name, buf,
1250                                             upstream_mark, branch_get_upstream);
1251                 if (len > 0)
1252                         return len;
1253
1254                 len = interpret_branch_mark(name, namelen, at - name, buf,
1255                                             push_mark, branch_get_push);
1256                 if (len > 0)
1257                         return len;
1258         }
1259
1260         return -1;
1261 }
1262
1263 int strbuf_branchname(struct strbuf *sb, const char *name)
1264 {
1265         int len = strlen(name);
1266         int used = interpret_branch_name(name, len, sb);
1267
1268         if (used == len)
1269                 return 0;
1270         if (used < 0)
1271                 used = 0;
1272         strbuf_add(sb, name + used, len - used);
1273         return len;
1274 }
1275
1276 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1277 {
1278         strbuf_branchname(sb, name);
1279         if (name[0] == '-')
1280                 return -1;
1281         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1282         return check_refname_format(sb->buf, 0);
1283 }
1284
1285 /*
1286  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1287  * notably "xyz^" for "parent of xyz"
1288  */
1289 int get_sha1(const char *name, unsigned char *sha1)
1290 {
1291         struct object_context unused;
1292         return get_sha1_with_context(name, 0, sha1, &unused);
1293 }
1294
1295 /*
1296  * This is like "get_sha1()", but for struct object_id.
1297  */
1298 int get_oid(const char *name, struct object_id *oid)
1299 {
1300         return get_sha1(name, oid->hash);
1301 }
1302
1303
1304 /*
1305  * Many callers know that the user meant to name a commit-ish by
1306  * syntactical positions where the object name appears.  Calling this
1307  * function allows the machinery to disambiguate shorter-than-unique
1308  * abbreviated object names between commit-ish and others.
1309  *
1310  * Note that this does NOT error out when the named object is not a
1311  * commit-ish. It is merely to give a hint to the disambiguation
1312  * machinery.
1313  */
1314 int get_sha1_committish(const char *name, unsigned char *sha1)
1315 {
1316         struct object_context unused;
1317         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1318                                      sha1, &unused);
1319 }
1320
1321 int get_sha1_treeish(const char *name, unsigned char *sha1)
1322 {
1323         struct object_context unused;
1324         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1325                                      sha1, &unused);
1326 }
1327
1328 int get_sha1_commit(const char *name, unsigned char *sha1)
1329 {
1330         struct object_context unused;
1331         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1332                                      sha1, &unused);
1333 }
1334
1335 int get_sha1_tree(const char *name, unsigned char *sha1)
1336 {
1337         struct object_context unused;
1338         return get_sha1_with_context(name, GET_SHA1_TREE,
1339                                      sha1, &unused);
1340 }
1341
1342 int get_sha1_blob(const char *name, unsigned char *sha1)
1343 {
1344         struct object_context unused;
1345         return get_sha1_with_context(name, GET_SHA1_BLOB,
1346                                      sha1, &unused);
1347 }
1348
1349 /* Must be called only when object_name:filename doesn't exist. */
1350 static void diagnose_invalid_sha1_path(const char *prefix,
1351                                        const char *filename,
1352                                        const unsigned char *tree_sha1,
1353                                        const char *object_name,
1354                                        int object_name_len)
1355 {
1356         unsigned char sha1[20];
1357         unsigned mode;
1358
1359         if (!prefix)
1360                 prefix = "";
1361
1362         if (file_exists(filename))
1363                 die("Path '%s' exists on disk, but not in '%.*s'.",
1364                     filename, object_name_len, object_name);
1365         if (errno == ENOENT || errno == ENOTDIR) {
1366                 char *fullname = xstrfmt("%s%s", prefix, filename);
1367
1368                 if (!get_tree_entry(tree_sha1, fullname,
1369                                     sha1, &mode)) {
1370                         die("Path '%s' exists, but not '%s'.\n"
1371                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1372                             fullname,
1373                             filename,
1374                             object_name_len, object_name,
1375                             fullname,
1376                             object_name_len, object_name,
1377                             filename);
1378                 }
1379                 die("Path '%s' does not exist in '%.*s'",
1380                     filename, object_name_len, object_name);
1381         }
1382 }
1383
1384 /* Must be called only when :stage:filename doesn't exist. */
1385 static void diagnose_invalid_index_path(int stage,
1386                                         const char *prefix,
1387                                         const char *filename)
1388 {
1389         const struct cache_entry *ce;
1390         int pos;
1391         unsigned namelen = strlen(filename);
1392         struct strbuf fullname = STRBUF_INIT;
1393
1394         if (!prefix)
1395                 prefix = "";
1396
1397         /* Wrong stage number? */
1398         pos = cache_name_pos(filename, namelen);
1399         if (pos < 0)
1400                 pos = -pos - 1;
1401         if (pos < active_nr) {
1402                 ce = active_cache[pos];
1403                 if (ce_namelen(ce) == namelen &&
1404                     !memcmp(ce->name, filename, namelen))
1405                         die("Path '%s' is in the index, but not at stage %d.\n"
1406                             "Did you mean ':%d:%s'?",
1407                             filename, stage,
1408                             ce_stage(ce), filename);
1409         }
1410
1411         /* Confusion between relative and absolute filenames? */
1412         strbuf_addstr(&fullname, prefix);
1413         strbuf_addstr(&fullname, filename);
1414         pos = cache_name_pos(fullname.buf, fullname.len);
1415         if (pos < 0)
1416                 pos = -pos - 1;
1417         if (pos < active_nr) {
1418                 ce = active_cache[pos];
1419                 if (ce_namelen(ce) == fullname.len &&
1420                     !memcmp(ce->name, fullname.buf, fullname.len))
1421                         die("Path '%s' is in the index, but not '%s'.\n"
1422                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1423                             fullname.buf, filename,
1424                             ce_stage(ce), fullname.buf,
1425                             ce_stage(ce), filename);
1426         }
1427
1428         if (file_exists(filename))
1429                 die("Path '%s' exists on disk, but not in the index.", filename);
1430         if (errno == ENOENT || errno == ENOTDIR)
1431                 die("Path '%s' does not exist (neither on disk nor in the index).",
1432                     filename);
1433
1434         strbuf_release(&fullname);
1435 }
1436
1437
1438 static char *resolve_relative_path(const char *rel)
1439 {
1440         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1441                 return NULL;
1442
1443         if (!is_inside_work_tree())
1444                 die("relative path syntax can't be used outside working tree.");
1445
1446         /* die() inside prefix_path() if resolved path is outside worktree */
1447         return prefix_path(startup_info->prefix,
1448                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1449                            rel);
1450 }
1451
1452 static int get_sha1_with_context_1(const char *name,
1453                                    unsigned flags,
1454                                    const char *prefix,
1455                                    unsigned char *sha1,
1456                                    struct object_context *oc)
1457 {
1458         int ret, bracket_depth;
1459         int namelen = strlen(name);
1460         const char *cp;
1461         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1462
1463         if (only_to_die)
1464                 flags |= GET_SHA1_QUIETLY;
1465
1466         memset(oc, 0, sizeof(*oc));
1467         oc->mode = S_IFINVALID;
1468         ret = get_sha1_1(name, namelen, sha1, flags);
1469         if (!ret)
1470                 return ret;
1471         /*
1472          * sha1:path --> object name of path in ent sha1
1473          * :path -> object name of absolute path in index
1474          * :./path -> object name of path relative to cwd in index
1475          * :[0-3]:path -> object name of path in index at stage
1476          * :/foo -> recent commit matching foo
1477          */
1478         if (name[0] == ':') {
1479                 int stage = 0;
1480                 const struct cache_entry *ce;
1481                 char *new_path = NULL;
1482                 int pos;
1483                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1484                         struct commit_list *list = NULL;
1485
1486                         for_each_ref(handle_one_ref, &list);
1487                         commit_list_sort_by_date(&list);
1488                         return get_sha1_oneline(name + 2, sha1, list);
1489                 }
1490                 if (namelen < 3 ||
1491                     name[2] != ':' ||
1492                     name[1] < '0' || '3' < name[1])
1493                         cp = name + 1;
1494                 else {
1495                         stage = name[1] - '0';
1496                         cp = name + 3;
1497                 }
1498                 new_path = resolve_relative_path(cp);
1499                 if (!new_path) {
1500                         namelen = namelen - (cp - name);
1501                 } else {
1502                         cp = new_path;
1503                         namelen = strlen(cp);
1504                 }
1505
1506                 strlcpy(oc->path, cp, sizeof(oc->path));
1507
1508                 if (!active_cache)
1509                         read_cache();
1510                 pos = cache_name_pos(cp, namelen);
1511                 if (pos < 0)
1512                         pos = -pos - 1;
1513                 while (pos < active_nr) {
1514                         ce = active_cache[pos];
1515                         if (ce_namelen(ce) != namelen ||
1516                             memcmp(ce->name, cp, namelen))
1517                                 break;
1518                         if (ce_stage(ce) == stage) {
1519                                 hashcpy(sha1, ce->oid.hash);
1520                                 oc->mode = ce->ce_mode;
1521                                 free(new_path);
1522                                 return 0;
1523                         }
1524                         pos++;
1525                 }
1526                 if (only_to_die && name[1] && name[1] != '/')
1527                         diagnose_invalid_index_path(stage, prefix, cp);
1528                 free(new_path);
1529                 return -1;
1530         }
1531         for (cp = name, bracket_depth = 0; *cp; cp++) {
1532                 if (*cp == '{')
1533                         bracket_depth++;
1534                 else if (bracket_depth && *cp == '}')
1535                         bracket_depth--;
1536                 else if (!bracket_depth && *cp == ':')
1537                         break;
1538         }
1539         if (*cp == ':') {
1540                 unsigned char tree_sha1[20];
1541                 int len = cp - name;
1542                 unsigned sub_flags = flags;
1543
1544                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1545                 sub_flags |= GET_SHA1_TREEISH;
1546
1547                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1548                         const char *filename = cp+1;
1549                         char *new_filename = NULL;
1550
1551                         new_filename = resolve_relative_path(filename);
1552                         if (new_filename)
1553                                 filename = new_filename;
1554                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1555                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1556                                         filename, sha1, &oc->symlink_path,
1557                                         &oc->mode);
1558                         } else {
1559                                 ret = get_tree_entry(tree_sha1, filename,
1560                                                      sha1, &oc->mode);
1561                                 if (ret && only_to_die) {
1562                                         diagnose_invalid_sha1_path(prefix,
1563                                                                    filename,
1564                                                                    tree_sha1,
1565                                                                    name, len);
1566                                 }
1567                         }
1568                         hashcpy(oc->tree, tree_sha1);
1569                         strlcpy(oc->path, filename, sizeof(oc->path));
1570
1571                         free(new_filename);
1572                         return ret;
1573                 } else {
1574                         if (only_to_die)
1575                                 die("Invalid object name '%.*s'.", len, name);
1576                 }
1577         }
1578         return ret;
1579 }
1580
1581 /*
1582  * Call this function when you know "name" given by the end user must
1583  * name an object but it doesn't; the function _may_ die with a better
1584  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1585  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1586  * you have a chance to diagnose the error further.
1587  */
1588 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1589 {
1590         struct object_context oc;
1591         unsigned char sha1[20];
1592         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1593 }
1594
1595 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1596 {
1597         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1598                 die("BUG: incompatible flags for get_sha1_with_context");
1599         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1600 }