src/revparse.c

   1 /*
   2  * Copyright (C) the libgit2 contributors. All rights reserved.
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7
   8 #include <assert.h>
   9
  10 #include "common.h"
  11 #include "buffer.h"
  12 #include "tree.h"
  13 #include "refdb.h"
  14
  15 #include "git2.h"
  16
  17 static int maybe_sha_or_abbrev(git_object** out, git_repository *repo, const char *spec, size_t speclen)
  18 {
  19         git_oid oid;
  20
  21         if (git_oid_fromstrn(&oid, spec, speclen) < 0)
  22                 return GIT_ENOTFOUND;
  23
  24         return git_object_lookup_prefix(out, repo, &oid, speclen, GIT_OBJ_ANY);
  25 }
  26
  27 static int maybe_sha(git_object** out, git_repository *repo, const char *spec)
  28 {
  29         size_t speclen = strlen(spec);
  30
  31         if (speclen != GIT_OID_HEXSZ)
  32                 return GIT_ENOTFOUND;
  33
  34         return maybe_sha_or_abbrev(out, repo, spec, speclen);
  35 }
  36
  37 static int maybe_abbrev(git_object** out, git_repository *repo, const char *spec)
  38 {
  39         size_t speclen = strlen(spec);
  40
  41         return maybe_sha_or_abbrev(out, repo, spec, speclen);
  42 }
  43
  44 static int build_regex(regex_t *regex, const char *pattern)
  45 {
  46         int error;
  47
  48         if (*pattern == '\0') {
  49                 giterr_set(GITERR_REGEX, "Empty pattern");
  50                 return GIT_EINVALIDSPEC;
  51         }
  52
  53         error = regcomp(regex, pattern, REG_EXTENDED);
  54         if (!error)
  55                 return 0;
  56
  57         error = giterr_set_regex(regex, error);
  58
  59         regfree(regex);
  60
  61         return error;
  62 }
  63
  64 static int maybe_describe(git_object**out, git_repository *repo, const char *spec)
  65 {
  66         const char *substr;
  67         int error;
  68         regex_t regex;
  69
  70         substr = strstr(spec, "-g");
  71
  72         if (substr == NULL)
  73                 return GIT_ENOTFOUND;
  74
  75         if (build_regex(&regex, ".+-[0-9]+-g[0-9a-fA-F]+") < 0)
  76                 return -1;
  77
  78         error = regexec(&regex, spec, 0, NULL, 0);
  79         regfree(&regex);
  80
  81         if (error)
  82                 return GIT_ENOTFOUND;
  83
  84         return maybe_abbrev(out, repo, substr+2);
  85 }
  86
  87 static int revparse_lookup_object(
  88         git_object **object_out,
  89         git_reference **reference_out,
  90         git_repository *repo,
  91         const char *spec)
  92 {
  93         int error;
  94         git_reference *ref;
  95
  96         if ((error = maybe_sha(object_out, repo, spec)) != GIT_ENOTFOUND)
  97                 return error;
  98
  99         error = git_reference_dwim(&ref, repo, spec);
 100         if (!error) {
 101
 102                 error = git_object_lookup(
 103                         object_out, repo, git_reference_target(ref), GIT_OBJ_ANY);
 104
 105                 if (!error)
 106                         *reference_out = ref;
 107
 108                 return error;
 109         }
 110
 111         if (error != GIT_ENOTFOUND)
 112                 return error;
 113
 114         if ((strlen(spec) < GIT_OID_HEXSZ) &&
 115                 ((error = maybe_abbrev(object_out, repo, spec)) != GIT_ENOTFOUND))
 116                         return error;
 117
 118         if ((error = maybe_describe(object_out, repo, spec)) != GIT_ENOTFOUND)
 119                 return error;
 120
 121         giterr_set(GITERR_REFERENCE, "Revspec '%s' not found.", spec);
 122         return GIT_ENOTFOUND;
 123 }
 124
 125 static int try_parse_numeric(int *n, const char *curly_braces_content)
 126 {
 127         int32_t content;
 128         const char *end_ptr;
 129
 130         if (git__strtol32(&content, curly_braces_content, &end_ptr, 10) < 0)
 131                 return -1;
 132
 133         if (*end_ptr != '\0')
 134                 return -1;
 135
 136         *n = (int)content;
 137         return 0;
 138 }
 139
 140 static int retrieve_previously_checked_out_branch_or_revision(git_object **out, git_reference **base_ref, git_repository *repo, const char *identifier, size_t position)
 141 {
 142         git_reference *ref = NULL;
 143         git_reflog *reflog = NULL;
 144         regex_t preg;
 145         int error = -1;
 146         size_t i, numentries, cur;
 147         const git_reflog_entry *entry;
 148         const char *msg;
 149         regmatch_t regexmatches[2];
 150         git_buf buf = GIT_BUF_INIT;
 151
 152         cur = position;
 153
 154         if (*identifier != '\0' || *base_ref != NULL)
 155                 return GIT_EINVALIDSPEC;
 156
 157         if (build_regex(&preg, "checkout: moving from (.*) to .*") < 0)
 158                 return -1;
 159
 160         if (git_reference_lookup(&ref, repo, GIT_HEAD_FILE) < 0)
 161                 goto cleanup;
 162
 163         if (git_reflog_read(&reflog, repo, GIT_HEAD_FILE) < 0)
 164                 goto cleanup;
 165
 166         numentries  = git_reflog_entrycount(reflog);
 167
 168         for (i = 0; i < numentries; i++) {
 169                 entry = git_reflog_entry_byindex(reflog, i);
 170                 msg = git_reflog_entry_message(entry);
 171
 172                 if (regexec(&preg, msg, 2, regexmatches, 0))
 173                         continue;
 174
 175                 cur--;
 176
 177                 if (cur > 0)
 178                         continue;
 179
 180                 git_buf_put(&buf, msg+regexmatches[1].rm_so, regexmatches[1].rm_eo - regexmatches[1].rm_so);
 181
 182                 if ((error = git_reference_dwim(base_ref, repo, git_buf_cstr(&buf))) == 0)
 183                         goto cleanup;
 184
 185                 if (error < 0 && error != GIT_ENOTFOUND)
 186                         goto cleanup;
 187
 188                 error = maybe_abbrev(out, repo, git_buf_cstr(&buf));
 189
 190                 goto cleanup;
 191         }
 192
 193         error = GIT_ENOTFOUND;
 194
 195 cleanup:
 196         git_reference_free(ref);
 197         git_buf_free(&buf);
 198         regfree(&preg);
 199         git_reflog_free(reflog);
 200         return error;
 201 }
 202
 203 static int retrieve_oid_from_reflog(git_oid *oid, git_reference *ref, size_t identifier)
 204 {
 205         git_reflog *reflog;
 206         int error = -1;
 207         size_t numentries;
 208         const git_reflog_entry *entry;
 209         bool search_by_pos = (identifier <= 100000000);
 210
 211         if (git_reflog_read(&reflog, git_reference_owner(ref), git_reference_name(ref)) < 0)
 212                 return -1;
 213
 214         numentries = git_reflog_entrycount(reflog);
 215
 216         if (search_by_pos) {
 217                 if (numentries < identifier + 1) {
 218                         giterr_set(
 219                                 GITERR_REFERENCE,
 220                                 "Reflog for '%s' has only %"PRIuZ" entries, asked for %"PRIuZ,
 221                                 git_reference_name(ref), numentries, identifier);
 222
 223                         error = GIT_ENOTFOUND;
 224                         goto cleanup;
 225                 }
 226
 227                 entry = git_reflog_entry_byindex(reflog, identifier);
 228                 git_oid_cpy(oid, git_reflog_entry_id_new(entry));
 229                 error = 0;
 230                 goto cleanup;
 231
 232         } else {
 233                 size_t i;
 234                 git_time commit_time;
 235
 236                 for (i = 0; i < numentries; i++) {
 237                         entry = git_reflog_entry_byindex(reflog, i);
 238                         commit_time = git_reflog_entry_committer(entry)->when;
 239
 240                         if (commit_time.time > (git_time_t)identifier)
 241                                 continue;
 242
 243                         git_oid_cpy(oid, git_reflog_entry_id_new(entry));
 244                         error = 0;
 245                         goto cleanup;
 246                 }
 247
 248                 error = GIT_ENOTFOUND;
 249         }
 250
 251 cleanup:
 252         git_reflog_free(reflog);
 253         return error;
 254 }
 255
 256 static int retrieve_revobject_from_reflog(git_object **out, git_reference **base_ref, git_repository *repo, const char *identifier, size_t position)
 257 {
 258         git_reference *ref;
 259         git_oid oid;
 260         int error = -1;
 261
 262         if (*base_ref == NULL) {
 263                 if ((error = git_reference_dwim(&ref, repo, identifier)) < 0)
 264                         return error;
 265         } else {
 266                 ref = *base_ref;
 267                 *base_ref = NULL;
 268         }
 269
 270         if (position == 0) {
 271                 error = git_object_lookup(out, repo, git_reference_target(ref), GIT_OBJ_ANY);
 272                 goto cleanup;
 273         }
 274
 275         if ((error = retrieve_oid_from_reflog(&oid, ref, position)) < 0)
 276                 goto cleanup;
 277
 278         error = git_object_lookup(out, repo, &oid, GIT_OBJ_ANY);
 279
 280 cleanup:
 281         git_reference_free(ref);
 282         return error;
 283 }
 284
 285 static int retrieve_remote_tracking_reference(git_reference **base_ref, const char *identifier, git_repository *repo)
 286 {
 287         git_reference *tracking, *ref;
 288         int error = -1;
 289
 290         if (*base_ref == NULL) {
 291                 if ((error = git_reference_dwim(&ref, repo, identifier)) < 0)
 292                         return error;
 293         } else {
 294                 ref = *base_ref;
 295                 *base_ref = NULL;
 296         }
 297
 298         if (!git_reference_is_branch(ref)) {
 299                 error = GIT_EINVALIDSPEC;
 300                 goto cleanup;
 301         }
 302
 303         if ((error = git_branch_upstream(&tracking, ref)) < 0)
 304                 goto cleanup;
 305
 306         *base_ref = tracking;
 307
 308 cleanup:
 309         git_reference_free(ref);
 310         return error;
 311 }
 312
 313 static int handle_at_syntax(git_object **out, git_reference **ref, const char *spec, size_t identifier_len, git_repository* repo, const char *curly_braces_content)
 314 {
 315         bool is_numeric;
 316         int parsed = 0, error = -1;
 317         git_buf identifier = GIT_BUF_INIT;
 318         git_time_t timestamp;
 319
 320         assert(*out == NULL);
 321
 322         if (git_buf_put(&identifier, spec, identifier_len) < 0)
 323                 return -1;
 324
 325         is_numeric = !try_parse_numeric(&parsed, curly_braces_content);
 326
 327         if (*curly_braces_content == '-' && (!is_numeric || parsed == 0)) {
 328                 error = GIT_EINVALIDSPEC;
 329                 goto cleanup;
 330         }
 331
 332         if (is_numeric) {
 333                 if (parsed < 0)
 334                         error = retrieve_previously_checked_out_branch_or_revision(out, ref, repo, git_buf_cstr(&identifier), -parsed);
 335                 else
 336                         error = retrieve_revobject_from_reflog(out, ref, repo, git_buf_cstr(&identifier), parsed);
 337
 338                 goto cleanup;
 339         }
 340
 341         if (!strcmp(curly_braces_content, "u") || !strcmp(curly_braces_content, "upstream")) {
 342                 error = retrieve_remote_tracking_reference(ref, git_buf_cstr(&identifier), repo);
 343
 344                 goto cleanup;
 345         }
 346
 347         if (git__date_parse(&timestamp, curly_braces_content) < 0)
 348                 goto cleanup;
 349
 350         error = retrieve_revobject_from_reflog(out, ref, repo, git_buf_cstr(&identifier), (size_t)timestamp);
 351
 352 cleanup:
 353         git_buf_free(&identifier);
 354         return error;
 355 }
 356
 357 static git_otype parse_obj_type(const char *str)
 358 {
 359         if (!strcmp(str, "commit"))
 360                 return GIT_OBJ_COMMIT;
 361
 362         if (!strcmp(str, "tree"))
 363                 return GIT_OBJ_TREE;
 364
 365         if (!strcmp(str, "blob"))
 366                 return GIT_OBJ_BLOB;
 367
 368         if (!strcmp(str, "tag"))
 369                 return GIT_OBJ_TAG;
 370
 371         return GIT_OBJ_BAD;
 372 }
 373
 374 static int dereference_to_non_tag(git_object **out, git_object *obj)
 375 {
 376         if (git_object_type(obj) == GIT_OBJ_TAG)
 377                 return git_tag_peel(out, (git_tag *)obj);
 378
 379         return git_object_dup(out, obj);
 380 }
 381
 382 static int handle_caret_parent_syntax(git_object **out, git_object *obj, int n)
 383 {
 384         git_object *temp_commit = NULL;
 385         int error;
 386
 387         if ((error = git_object_peel(&temp_commit, obj, GIT_OBJ_COMMIT)) < 0)
 388                 return (error == GIT_EAMBIGUOUS || error == GIT_ENOTFOUND) ?
 389                         GIT_EINVALIDSPEC : error;
 390
 391         if (n == 0) {
 392                 *out = temp_commit;
 393                 return 0;
 394         }
 395
 396         error = git_commit_parent((git_commit **)out, (git_commit*)temp_commit, n - 1);
 397
 398         git_object_free(temp_commit);
 399         return error;
 400 }
 401
 402 static int handle_linear_syntax(git_object **out, git_object *obj, int n)
 403 {
 404         git_object *temp_commit = NULL;
 405         int error;
 406
 407         if ((error = git_object_peel(&temp_commit, obj, GIT_OBJ_COMMIT)) < 0)
 408                 return (error == GIT_EAMBIGUOUS || error == GIT_ENOTFOUND) ?
 409                         GIT_EINVALIDSPEC : error;
 410
 411         error = git_commit_nth_gen_ancestor((git_commit **)out, (git_commit*)temp_commit, n);
 412
 413         git_object_free(temp_commit);
 414         return error;
 415 }
 416
 417 static int handle_colon_syntax(
 418         git_object **out,
 419         git_object *obj,
 420         const char *path)
 421 {
 422         git_object *tree;
 423         int error = -1;
 424         git_tree_entry *entry = NULL;
 425
 426         if ((error = git_object_peel(&tree, obj, GIT_OBJ_TREE)) < 0)
 427                 return error == GIT_ENOTFOUND ? GIT_EINVALIDSPEC : error;
 428
 429         if (*path == '\0') {
 430                 *out = tree;
 431                 return 0;
 432         }
 433
 434         /*
 435          * TODO: Handle the relative path syntax
 436          * (:./relative/path and :../relative/path)
 437          */
 438         if ((error = git_tree_entry_bypath(&entry, (git_tree *)tree, path)) < 0)
 439                 goto cleanup;
 440
 441         error = git_tree_entry_to_object(out, git_object_owner(tree), entry);
 442
 443 cleanup:
 444         git_tree_entry_free(entry);
 445         git_object_free(tree);
 446
 447         return error;
 448 }
 449
 450 static int walk_and_search(git_object **out, git_revwalk *walk, regex_t *regex)
 451 {
 452         int error;
 453         git_oid oid;
 454         git_object *obj;
 455
 456         while (!(error = git_revwalk_next(&oid, walk))) {
 457
 458                 error = git_object_lookup(&obj, git_revwalk_repository(walk), &oid, GIT_OBJ_COMMIT);
 459                 if ((error < 0) && (error != GIT_ENOTFOUND))
 460                         return -1;
 461
 462                 if (!regexec(regex, git_commit_message((git_commit*)obj), 0, NULL, 0)) {
 463                         *out = obj;
 464                         return 0;
 465                 }
 466
 467                 git_object_free(obj);
 468         }
 469
 470         if (error < 0 && error == GIT_ITEROVER)
 471                 error = GIT_ENOTFOUND;
 472
 473         return error;
 474 }
 475
 476 static int handle_grep_syntax(git_object **out, git_repository *repo, const git_oid *spec_oid, const char *pattern)
 477 {
 478         regex_t preg;
 479         git_revwalk *walk = NULL;
 480         int error;
 481
 482         if ((error = build_regex(&preg, pattern)) < 0)
 483                 return error;
 484
 485         if ((error = git_revwalk_new(&walk, repo)) < 0)
 486                 goto cleanup;
 487
 488         git_revwalk_sorting(walk, GIT_SORT_TIME);
 489
 490         if (spec_oid == NULL) {
 491                 // TODO: @carlosmn: The glob should be refs/* but this makes git_revwalk_next() fails
 492                 if ((error = git_revwalk_push_glob(walk, GIT_REFS_HEADS_DIR "*")) < 0)
 493                         goto cleanup;
 494         } else if ((error = git_revwalk_push(walk, spec_oid)) < 0)
 495                         goto cleanup;
 496
 497         error = walk_and_search(out, walk, &preg);
 498
 499 cleanup:
 500         regfree(&preg);
 501         git_revwalk_free(walk);
 502
 503         return error;
 504 }
 505
 506 static int handle_caret_curly_syntax(git_object **out, git_object *obj, const char *curly_braces_content)
 507 {
 508         git_otype expected_type;
 509
 510         if (*curly_braces_content == '\0')
 511                 return dereference_to_non_tag(out, obj);
 512
 513         if (*curly_braces_content == '/')
 514                 return handle_grep_syntax(out, git_object_owner(obj), git_object_id(obj), curly_braces_content + 1);
 515
 516         expected_type = parse_obj_type(curly_braces_content);
 517
 518         if (expected_type == GIT_OBJ_BAD)
 519                 return GIT_EINVALIDSPEC;
 520
 521         return git_object_peel(out, obj, expected_type);
 522 }
 523
 524 static int extract_curly_braces_content(git_buf *buf, const char *spec, size_t *pos)
 525 {
 526         git_buf_clear(buf);
 527
 528         assert(spec[*pos] == '^' || spec[*pos] == '@');
 529
 530         (*pos)++;
 531
 532         if (spec[*pos] == '\0' || spec[*pos] != '{')
 533                 return GIT_EINVALIDSPEC;
 534
 535         (*pos)++;
 536
 537         while (spec[*pos] != '}') {
 538                 if (spec[*pos] == '\0')
 539                         return GIT_EINVALIDSPEC;
 540
 541                 git_buf_putc(buf, spec[(*pos)++]);
 542         }
 543
 544         (*pos)++;
 545
 546         return 0;
 547 }
 548
 549 static int extract_path(git_buf *buf, const char *spec, size_t *pos)
 550 {
 551         git_buf_clear(buf);
 552
 553         assert(spec[*pos] == ':');
 554
 555         (*pos)++;
 556
 557         if (git_buf_puts(buf, spec + *pos) < 0)
 558                 return -1;
 559
 560         *pos += git_buf_len(buf);
 561
 562         return 0;
 563 }
 564
 565 static int extract_how_many(int *n, const char *spec, size_t *pos)
 566 {
 567         const char *end_ptr;
 568         int parsed, accumulated;
 569         char kind = spec[*pos];
 570
 571         assert(spec[*pos] == '^' || spec[*pos] == '~');
 572
 573         accumulated = 0;
 574
 575         do {
 576                 do {
 577                         (*pos)++;
 578                         accumulated++;
 579                 } while (spec[(*pos)] == kind && kind == '~');
 580
 581                 if (git__isdigit(spec[*pos])) {
 582                         if (git__strtol32(&parsed, spec + *pos, &end_ptr, 10) < 0)
 583                                 return GIT_EINVALIDSPEC;
 584
 585                         accumulated += (parsed - 1);
 586                         *pos = end_ptr - spec;
 587                 }
 588
 589         }       while (spec[(*pos)] == kind && kind == '~');
 590
 591         *n = accumulated;
 592
 593         return 0;
 594 }
 595
 596 static int object_from_reference(git_object **object, git_reference *reference)
 597 {
 598         git_reference *resolved = NULL;
 599         int error;
 600
 601         if (git_reference_resolve(&resolved, reference) < 0)
 602                 return -1;
 603
 604         error = git_object_lookup(object, reference->db->repo, git_reference_target(resolved), GIT_OBJ_ANY);
 605         git_reference_free(resolved);
 606
 607         return error;
 608 }
 609
 610 static int ensure_base_rev_loaded(git_object **object, git_reference **reference, const char *spec, size_t identifier_len, git_repository *repo, bool allow_empty_identifier)
 611 {
 612         int error;
 613         git_buf identifier = GIT_BUF_INIT;
 614
 615         if (*object != NULL)
 616                 return 0;
 617
 618         if (*reference != NULL)
 619                 return object_from_reference(object, *reference);
 620
 621         if (!allow_empty_identifier && identifier_len == 0)
 622                 return GIT_EINVALIDSPEC;
 623
 624         if (git_buf_put(&identifier, spec, identifier_len) < 0)
 625                 return -1;
 626
 627         error = revparse_lookup_object(object, reference, repo, git_buf_cstr(&identifier));
 628         git_buf_free(&identifier);
 629
 630         return error;
 631 }
 632
 633 static int ensure_base_rev_is_not_known_yet(git_object *object)
 634 {
 635         if (object == NULL)
 636                 return 0;
 637
 638         return GIT_EINVALIDSPEC;
 639 }
 640
 641 static bool any_left_hand_identifier(git_object *object, git_reference *reference, size_t identifier_len)
 642 {
 643         if (object != NULL)
 644                 return true;
 645
 646         if (reference != NULL)
 647                 return true;
 648
 649         if (identifier_len > 0)
 650                 return true;
 651
 652         return false;
 653 }
 654
 655 static int ensure_left_hand_identifier_is_not_known_yet(git_object *object, git_reference *reference)
 656 {
 657         if (!ensure_base_rev_is_not_known_yet(object) && reference == NULL)
 658                 return 0;
 659
 660         return GIT_EINVALIDSPEC;
 661 }
 662
 663 int revparse__ext(
 664         git_object **object_out,
 665         git_reference **reference_out,
 666         size_t *identifier_len_out,
 667         git_repository *repo,
 668         const char *spec)
 669 {
 670         size_t pos = 0, identifier_len = 0;
 671         int error = -1, n;
 672         git_buf buf = GIT_BUF_INIT;
 673
 674         git_reference *reference = NULL;
 675         git_object *base_rev = NULL;
 676
 677         bool should_return_reference = true;
 678
 679         assert(object_out && reference_out && repo && spec);
 680
 681         *object_out = NULL;
 682         *reference_out = NULL;
 683
 684         while (spec[pos]) {
 685                 switch (spec[pos]) {
 686                 case '^':
 687                         should_return_reference = false;
 688
 689                         if ((error = ensure_base_rev_loaded(&base_rev, &reference, spec, identifier_len, repo, false)) < 0)
 690                                 goto cleanup;
 691
 692                         if (spec[pos+1] == '{') {
 693                                 git_object *temp_object = NULL;
 694
 695                                 if ((error = extract_curly_braces_content(&buf, spec, &pos)) < 0)
 696                                         goto cleanup;
 697
 698                                 if ((error = handle_caret_curly_syntax(&temp_object, base_rev, git_buf_cstr(&buf))) < 0)
 699                                         goto cleanup;
 700
 701                                 git_object_free(base_rev);
 702                                 base_rev = temp_object;
 703                         } else {
 704                                 git_object *temp_object = NULL;
 705
 706                                 if ((error = extract_how_many(&n, spec, &pos)) < 0)
 707                                         goto cleanup;
 708
 709                                 if ((error = handle_caret_parent_syntax(&temp_object, base_rev, n)) < 0)
 710                                         goto cleanup;
 711
 712                                 git_object_free(base_rev);
 713                                 base_rev = temp_object;
 714                         }
 715                         break;
 716
 717                 case '~':
 718                 {
 719                         git_object *temp_object = NULL;
 720
 721                         should_return_reference = false;
 722
 723                         if ((error = extract_how_many(&n, spec, &pos)) < 0)
 724                                 goto cleanup;
 725
 726                         if ((error = ensure_base_rev_loaded(&base_rev, &reference, spec, identifier_len, repo, false)) < 0)
 727                                 goto cleanup;
 728
 729                         if ((error = handle_linear_syntax(&temp_object, base_rev, n)) < 0)
 730                                 goto cleanup;
 731
 732                         git_object_free(base_rev);
 733                         base_rev = temp_object;
 734                         break;
 735                 }
 736
 737                 case ':':
 738                 {
 739                         git_object *temp_object = NULL;
 740
 741                         should_return_reference = false;
 742
 743                         if ((error = extract_path(&buf, spec, &pos)) < 0)
 744                                 goto cleanup;
 745
 746                         if (any_left_hand_identifier(base_rev, reference, identifier_len)) {
 747                                 if ((error = ensure_base_rev_loaded(&base_rev, &reference, spec, identifier_len, repo, true)) < 0)
 748                                         goto cleanup;
 749
 750                                 if ((error = handle_colon_syntax(&temp_object, base_rev, git_buf_cstr(&buf))) < 0)
 751                                         goto cleanup;
 752                         } else {
 753                                 if (*git_buf_cstr(&buf) == '/') {
 754                                         if ((error = handle_grep_syntax(&temp_object, repo, NULL, git_buf_cstr(&buf) + 1)) < 0)
 755                                                 goto cleanup;
 756                                 } else {
 757
 758                                         /*
 759                                          * TODO: support merge-stage path lookup (":2:Makefile")
 760                                          * and plain index blob lookup (:i-am/a/blob)
 761                                          */
 762                                         giterr_set(GITERR_INVALID, "Unimplemented");
 763                                         error = GIT_ERROR;
 764                                         goto cleanup;
 765                                 }
 766                         }
 767
 768                         git_object_free(base_rev);
 769                         base_rev = temp_object;
 770                         break;
 771                 }
 772
 773                 case '@':
 774                 {
 775                         if (spec[pos+1] == '{') {
 776                                 git_object *temp_object = NULL;
 777
 778                                 if ((error = extract_curly_braces_content(&buf, spec, &pos)) < 0)
 779                                         goto cleanup;
 780
 781                                 if ((error = ensure_base_rev_is_not_known_yet(base_rev)) < 0)
 782                                         goto cleanup;
 783
 784                                 if ((error = handle_at_syntax(&temp_object, &reference, spec, identifier_len, repo, git_buf_cstr(&buf))) < 0)
 785                                         goto cleanup;
 786
 787                                 if (temp_object != NULL)
 788                                         base_rev = temp_object;
 789                                 break;
 790                         } else {
 791                                 /* Fall through */
 792                         }
 793                 }
 794
 795                 default:
 796                         if ((error = ensure_left_hand_identifier_is_not_known_yet(base_rev, reference)) < 0)
 797                                 goto cleanup;
 798
 799                         pos++;
 800                         identifier_len++;
 801                 }
 802         }
 803
 804         if ((error = ensure_base_rev_loaded(&base_rev, &reference, spec, identifier_len, repo, false)) < 0)
 805                 goto cleanup;
 806
 807         if (!should_return_reference) {
 808                 git_reference_free(reference);
 809                 reference = NULL;
 810         }
 811
 812         *object_out = base_rev;
 813         *reference_out = reference;
 814         *identifier_len_out = identifier_len;
 815         error = 0;
 816
 817 cleanup:
 818         if (error) {
 819                 if (error == GIT_EINVALIDSPEC)
 820                         giterr_set(GITERR_INVALID,
 821                                 "Failed to parse revision specifier - Invalid pattern '%s'", spec);
 822
 823                 git_object_free(base_rev);
 824                 git_reference_free(reference);
 825         }
 826
 827         git_buf_free(&buf);
 828         return error;
 829 }
 830
 831 int git_revparse_ext(
 832         git_object **object_out,
 833         git_reference **reference_out,
 834         git_repository *repo,
 835         const char *spec)
 836 {
 837         int error;
 838         size_t identifier_len;
 839         git_object *obj = NULL;
 840         git_reference *ref = NULL;
 841
 842         if ((error = revparse__ext(&obj, &ref, &identifier_len, repo, spec)) < 0)
 843                 goto cleanup;
 844
 845         *object_out = obj;
 846         *reference_out = ref;
 847         GIT_UNUSED(identifier_len);
 848
 849         return 0;
 850
 851 cleanup:
 852         git_object_free(obj);
 853         git_reference_free(ref);
 854         return error;
 855 }
 856
 857 int git_revparse_single(git_object **out, git_repository *repo, const char *spec)
 858 {
 859         int error;
 860         git_object *obj = NULL;
 861         git_reference *ref = NULL;
 862
 863         *out = NULL;
 864
 865         if ((error = git_revparse_ext(&obj, &ref, repo, spec)) < 0)
 866                 goto cleanup;
 867
 868         git_reference_free(ref);
 869
 870         *out = obj;
 871
 872         return 0;
 873
 874 cleanup:
 875         git_object_free(obj);
 876         git_reference_free(ref);
 877         return error;
 878 }
 879
 880 int git_revparse(
 881         git_revspec *revspec,
 882         git_repository *repo,
 883         const char *spec)
 884 {
 885         const char *dotdot;
 886         int error = 0;
 887
 888         assert(revspec && repo && spec);
 889
 890         memset(revspec, 0x0, sizeof(*revspec));
 891
 892         if ((dotdot = strstr(spec, "..")) != NULL) {
 893                 char *lstr;
 894                 const char *rstr;
 895                 revspec->flags = GIT_REVPARSE_RANGE;
 896
 897                 lstr = git__substrdup(spec, dotdot - spec);
 898                 rstr = dotdot + 2;
 899                 if (dotdot[2] == '.') {
 900                         revspec->flags |= GIT_REVPARSE_MERGE_BASE;
 901                         rstr++;
 902                 }
 903
 904                 error = git_revparse_single(&revspec->from, repo, lstr);
 905                 if (!error)
 906                         error = git_revparse_single(&revspec->to, repo, rstr);
 907
 908                 git__free((void*)lstr);
 909         } else {
 910                 revspec->flags = GIT_REVPARSE_SINGLE;
 911                 error = git_revparse_single(&revspec->from, repo, spec);
 912         }
 913
 914         return error;
 915 }