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
  10 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  11
  12 static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
  13 {
  14         struct alternate_object_database *alt;
  15         char hex[40];
  16         int found = 0;
  17         static struct alternate_object_database *fakeent;
  18
  19         if (!fakeent) {
  20                 const char *objdir = get_object_directory();
  21                 int objdir_len = strlen(objdir);
  22                 int entlen = objdir_len + 43;
  23                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
  24                 memcpy(fakeent->base, objdir, objdir_len);
  25                 fakeent->name = fakeent->base + objdir_len + 1;
  26                 fakeent->name[-1] = '/';
  27         }
  28         fakeent->next = alt_odb_list;
  29
  30         sprintf(hex, "%.2s", name);
  31         for (alt = fakeent; alt && found < 2; alt = alt->next) {
  32                 struct dirent *de;
  33                 DIR *dir;
  34                 sprintf(alt->name, "%.2s/", name);
  35                 dir = opendir(alt->base);
  36                 if (!dir)
  37                         continue;
  38                 while ((de = readdir(dir)) != NULL) {
  39                         if (strlen(de->d_name) != 38)
  40                                 continue;
  41                         if (memcmp(de->d_name, name + 2, len - 2))
  42                                 continue;
  43                         if (!found) {
  44                                 memcpy(hex + 2, de->d_name, 38);
  45                                 found++;
  46                         }
  47                         else if (memcmp(hex + 2, de->d_name, 38)) {
  48                                 found = 2;
  49                                 break;
  50                         }
  51                 }
  52                 closedir(dir);
  53         }
  54         if (found == 1)
  55                 return get_sha1_hex(hex, sha1) == 0;
  56         return found;
  57 }
  58
  59 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
  60 {
  61         do {
  62                 if (*a != *b)
  63                         return 0;
  64                 a++;
  65                 b++;
  66                 len -= 2;
  67         } while (len > 1);
  68         if (len)
  69                 if ((*a ^ *b) & 0xf0)
  70                         return 0;
  71         return 1;
  72 }
  73
  74 static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
  75 {
  76         struct packed_git *p;
  77         const unsigned char *found_sha1 = NULL;
  78         int found = 0;
  79
  80         prepare_packed_git();
  81         for (p = packed_git; p && found < 2; p = p->next) {
  82                 uint32_t num, last;
  83                 uint32_t first = 0;
  84                 open_pack_index(p);
  85                 num = p->num_objects;
  86                 last = num;
  87                 while (first < last) {
  88                         uint32_t mid = (first + last) / 2;
  89                         const unsigned char *now;
  90                         int cmp;
  91
  92                         now = nth_packed_object_sha1(p, mid);
  93                         cmp = hashcmp(match, now);
  94                         if (!cmp) {
  95                                 first = mid;
  96                                 break;
  97                         }
  98                         if (cmp > 0) {
  99                                 first = mid+1;
 100                                 continue;
 101                         }
 102                         last = mid;
 103                 }
 104                 if (first < num) {
 105                         const unsigned char *now, *next;
 106                        now = nth_packed_object_sha1(p, first);
 107                         if (match_sha(len, match, now)) {
 108                                 next = nth_packed_object_sha1(p, first+1);
 109                                if (!next|| !match_sha(len, match, next)) {
 110                                         /* unique within this pack */
 111                                         if (!found) {
 112                                                 found_sha1 = now;
 113                                                 found++;
 114                                         }
 115                                         else if (hashcmp(found_sha1, now)) {
 116                                                 found = 2;
 117                                                 break;
 118                                         }
 119                                 }
 120                                 else {
 121                                         /* not even unique within this pack */
 122                                         found = 2;
 123                                         break;
 124                                 }
 125                         }
 126                 }
 127         }
 128         if (found == 1)
 129                 hashcpy(sha1, found_sha1);
 130         return found;
 131 }
 132
 133 #define SHORT_NAME_NOT_FOUND (-1)
 134 #define SHORT_NAME_AMBIGUOUS (-2)
 135
 136 static int find_unique_short_object(int len, char *canonical,
 137                                     unsigned char *res, unsigned char *sha1)
 138 {
 139         int has_unpacked, has_packed;
 140         unsigned char unpacked_sha1[20], packed_sha1[20];
 141
 142         prepare_alt_odb();
 143         has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
 144         has_packed = find_short_packed_object(len, res, packed_sha1);
 145         if (!has_unpacked && !has_packed)
 146                 return SHORT_NAME_NOT_FOUND;
 147         if (1 < has_unpacked || 1 < has_packed)
 148                 return SHORT_NAME_AMBIGUOUS;
 149         if (has_unpacked != has_packed) {
 150                 hashcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1));
 151                 return 0;
 152         }
 153         /* Both have unique ones -- do they match? */
 154         if (hashcmp(packed_sha1, unpacked_sha1))
 155                 return SHORT_NAME_AMBIGUOUS;
 156         hashcpy(sha1, packed_sha1);
 157         return 0;
 158 }
 159
 160 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 161                           int quietly)
 162 {
 163         int i, status;
 164         char canonical[40];
 165         unsigned char res[20];
 166
 167         if (len < MINIMUM_ABBREV || len > 40)
 168                 return -1;
 169         hashclr(res);
 170         memset(canonical, 'x', 40);
 171         for (i = 0; i < len ;i++) {
 172                 unsigned char c = name[i];
 173                 unsigned char val;
 174                 if (c >= '0' && c <= '9')
 175                         val = c - '0';
 176                 else if (c >= 'a' && c <= 'f')
 177                         val = c - 'a' + 10;
 178                 else if (c >= 'A' && c <='F') {
 179                         val = c - 'A' + 10;
 180                         c -= 'A' - 'a';
 181                 }
 182                 else
 183                         return -1;
 184                 canonical[i] = c;
 185                 if (!(i & 1))
 186                         val <<= 4;
 187                 res[i >> 1] |= val;
 188         }
 189
 190         status = find_unique_short_object(i, canonical, res, sha1);
 191         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 192                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
 193         return status;
 194 }
 195
 196 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 197 {
 198         int status, exists;
 199         static char hex[41];
 200
 201         exists = has_sha1_file(sha1);
 202         memcpy(hex, sha1_to_hex(sha1), 40);
 203         if (len == 40 || !len)
 204                 return hex;
 205         while (len < 40) {
 206                 unsigned char sha1_ret[20];
 207                 status = get_short_sha1(hex, len, sha1_ret, 1);
 208                 if (exists
 209                     ? !status
 210                     : status == SHORT_NAME_NOT_FOUND) {
 211                         int cut_at = len + unique_abbrev_extra_length;
 212                         cut_at = (cut_at < 40) ? cut_at : 40;
 213                         hex[cut_at] = 0;
 214                         return hex;
 215                 }
 216                 len++;
 217         }
 218         return hex;
 219 }
 220
 221 static int ambiguous_path(const char *path, int len)
 222 {
 223         int slash = 1;
 224         int cnt;
 225
 226         for (cnt = 0; cnt < len; cnt++) {
 227                 switch (*path++) {
 228                 case '\0':
 229                         break;
 230                 case '/':
 231                         if (slash)
 232                                 break;
 233                         slash = 1;
 234                         continue;
 235                 case '.':
 236                         continue;
 237                 default:
 238                         slash = 0;
 239                         continue;
 240                 }
 241                 break;
 242         }
 243         return slash;
 244 }
 245
 246 /*
 247  * *string and *len will only be substituted, and *string returned (for
 248  * later free()ing) if the string passed in is a magic short-hand form
 249  * to name a branch.
 250  */
 251 static char *substitute_branch_name(const char **string, int *len)
 252 {
 253         struct strbuf buf = STRBUF_INIT;
 254         int ret = interpret_branch_name(*string, &buf);
 255
 256         if (ret == *len) {
 257                 size_t size;
 258                 *string = strbuf_detach(&buf, &size);
 259                 *len = size;
 260                 return (char *)*string;
 261         }
 262
 263         return NULL;
 264 }
 265
 266 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 267 {
 268         char *last_branch = substitute_branch_name(&str, &len);
 269         const char **p, *r;
 270         int refs_found = 0;
 271
 272         *ref = NULL;
 273         for (p = ref_rev_parse_rules; *p; p++) {
 274                 char fullref[PATH_MAX];
 275                 unsigned char sha1_from_ref[20];
 276                 unsigned char *this_result;
 277                 int flag;
 278
 279                 this_result = refs_found ? sha1_from_ref : sha1;
 280                 mksnpath(fullref, sizeof(fullref), *p, len, str);
 281                 r = resolve_ref(fullref, this_result, 1, &flag);
 282                 if (r) {
 283                         if (!refs_found++)
 284                                 *ref = xstrdup(r);
 285                         if (!warn_ambiguous_refs)
 286                                 break;
 287                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD"))
 288                         warning("ignoring dangling symref %s.", fullref);
 289         }
 290         free(last_branch);
 291         return refs_found;
 292 }
 293
 294 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 295 {
 296         char *last_branch = substitute_branch_name(&str, &len);
 297         const char **p;
 298         int logs_found = 0;
 299
 300         *log = NULL;
 301         for (p = ref_rev_parse_rules; *p; p++) {
 302                 struct stat st;
 303                 unsigned char hash[20];
 304                 char path[PATH_MAX];
 305                 const char *ref, *it;
 306
 307                 mksnpath(path, sizeof(path), *p, len, str);
 308                 ref = resolve_ref(path, hash, 1, NULL);
 309                 if (!ref)
 310                         continue;
 311                 if (!stat(git_path("logs/%s", path), &st) &&
 312                     S_ISREG(st.st_mode))
 313                         it = path;
 314                 else if (strcmp(ref, path) &&
 315                          !stat(git_path("logs/%s", ref), &st) &&
 316                          S_ISREG(st.st_mode))
 317                         it = ref;
 318                 else
 319                         continue;
 320                 if (!logs_found++) {
 321                         *log = xstrdup(it);
 322                         hashcpy(sha1, hash);
 323                 }
 324                 if (!warn_ambiguous_refs)
 325                         break;
 326         }
 327         free(last_branch);
 328         return logs_found;
 329 }
 330
 331 static inline int upstream_mark(const char *string, int len)
 332 {
 333         const char *suffix[] = { "@{upstream}", "@{u}" };
 334         int i;
 335
 336         for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 337                 int suffix_len = strlen(suffix[i]);
 338                 if (suffix_len <= len
 339                     && !memcmp(string, suffix[i], suffix_len))
 340                         return suffix_len;
 341         }
 342         return 0;
 343 }
 344
 345 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 346
 347 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 348 {
 349         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 350         char *real_ref = NULL;
 351         int refs_found = 0;
 352         int at, reflog_len;
 353
 354         if (len == 40 && !get_sha1_hex(str, sha1))
 355                 return 0;
 356
 357         /* basic@{time or number or -number} format to query ref-log */
 358         reflog_len = at = 0;
 359         if (len && str[len-1] == '}') {
 360                 for (at = len-2; at >= 0; at--) {
 361                         if (str[at] == '@' && str[at+1] == '{') {
 362                                 if (!upstream_mark(str + at, len - at)) {
 363                                         reflog_len = (len-1) - (at+2);
 364                                         len = at;
 365                                 }
 366                                 break;
 367                         }
 368                 }
 369         }
 370
 371         /* Accept only unambiguous ref paths. */
 372         if (len && ambiguous_path(str, len))
 373                 return -1;
 374
 375         if (!len && reflog_len) {
 376                 struct strbuf buf = STRBUF_INIT;
 377                 int ret;
 378                 /* try the @{-N} syntax for n-th checkout */
 379                 ret = interpret_branch_name(str+at, &buf);
 380                 if (ret > 0) {
 381                         /* substitute this branch name and restart */
 382                         return get_sha1_1(buf.buf, buf.len, sha1);
 383                 } else if (ret == 0) {
 384                         return -1;
 385                 }
 386                 /* allow "@{...}" to mean the current branch reflog */
 387                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 388         } else if (reflog_len)
 389                 refs_found = dwim_log(str, len, sha1, &real_ref);
 390         else
 391                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 392
 393         if (!refs_found)
 394                 return -1;
 395
 396         if (warn_ambiguous_refs && refs_found > 1)
 397                 warning(warn_msg, len, str);
 398
 399         if (reflog_len) {
 400                 int nth, i;
 401                 unsigned long at_time;
 402                 unsigned long co_time;
 403                 int co_tz, co_cnt;
 404
 405                 /* a @{-N} placed anywhere except the start is an error */
 406                 if (str[at+2] == '-')
 407                         return -1;
 408
 409                 /* Is it asking for N-th entry, or approxidate? */
 410                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 411                         char ch = str[at+2+i];
 412                         if ('0' <= ch && ch <= '9')
 413                                 nth = nth * 10 + ch - '0';
 414                         else
 415                                 nth = -1;
 416                 }
 417                 if (100000000 <= nth) {
 418                         at_time = nth;
 419                         nth = -1;
 420                 } else if (0 <= nth)
 421                         at_time = 0;
 422                 else {
 423                         int errors = 0;
 424                         char *tmp = xstrndup(str + at + 2, reflog_len);
 425                         at_time = approxidate_careful(tmp, &errors);
 426                         free(tmp);
 427                         if (errors)
 428                                 return -1;
 429                 }
 430                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
 431                                 &co_time, &co_tz, &co_cnt)) {
 432                         if (at_time)
 433                                 warning("Log for '%.*s' only goes "
 434                                         "back to %s.", len, str,
 435                                         show_date(co_time, co_tz, DATE_RFC2822));
 436                         else {
 437                                 free(real_ref);
 438                                 die("Log for '%.*s' only has %d entries.",
 439                                     len, str, co_cnt);
 440                         }
 441                 }
 442         }
 443
 444         free(real_ref);
 445         return 0;
 446 }
 447
 448 static int get_parent(const char *name, int len,
 449                       unsigned char *result, int idx)
 450 {
 451         unsigned char sha1[20];
 452         int ret = get_sha1_1(name, len, sha1);
 453         struct commit *commit;
 454         struct commit_list *p;
 455
 456         if (ret)
 457                 return ret;
 458         commit = lookup_commit_reference(sha1);
 459         if (!commit)
 460                 return -1;
 461         if (parse_commit(commit))
 462                 return -1;
 463         if (!idx) {
 464                 hashcpy(result, commit->object.sha1);
 465                 return 0;
 466         }
 467         p = commit->parents;
 468         while (p) {
 469                 if (!--idx) {
 470                         hashcpy(result, p->item->object.sha1);
 471                         return 0;
 472                 }
 473                 p = p->next;
 474         }
 475         return -1;
 476 }
 477
 478 static int get_nth_ancestor(const char *name, int len,
 479                             unsigned char *result, int generation)
 480 {
 481         unsigned char sha1[20];
 482         struct commit *commit;
 483         int ret;
 484
 485         ret = get_sha1_1(name, len, sha1);
 486         if (ret)
 487                 return ret;
 488         commit = lookup_commit_reference(sha1);
 489         if (!commit)
 490                 return -1;
 491
 492         while (generation--) {
 493                 if (parse_commit(commit) || !commit->parents)
 494                         return -1;
 495                 commit = commit->parents->item;
 496         }
 497         hashcpy(result, commit->object.sha1);
 498         return 0;
 499 }
 500
 501 struct object *peel_to_type(const char *name, int namelen,
 502                             struct object *o, enum object_type expected_type)
 503 {
 504         if (name && !namelen)
 505                 namelen = strlen(name);
 506         if (!o) {
 507                 unsigned char sha1[20];
 508                 if (get_sha1_1(name, namelen, sha1))
 509                         return NULL;
 510                 o = parse_object(sha1);
 511         }
 512         while (1) {
 513                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 514                         return NULL;
 515                 if (o->type == expected_type)
 516                         return o;
 517                 if (o->type == OBJ_TAG)
 518                         o = ((struct tag*) o)->tagged;
 519                 else if (o->type == OBJ_COMMIT)
 520                         o = &(((struct commit *) o)->tree->object);
 521                 else {
 522                         if (name)
 523                                 error("%.*s: expected %s type, but the object "
 524                                       "dereferences to %s type",
 525                                       namelen, name, typename(expected_type),
 526                                       typename(o->type));
 527                         return NULL;
 528                 }
 529         }
 530 }
 531
 532 static int peel_onion(const char *name, int len, unsigned char *sha1)
 533 {
 534         unsigned char outer[20];
 535         const char *sp;
 536         unsigned int expected_type = 0;
 537         struct object *o;
 538
 539         /*
 540          * "ref^{type}" dereferences ref repeatedly until you cannot
 541          * dereference anymore, or you get an object of given type,
 542          * whichever comes first.  "ref^{}" means just dereference
 543          * tags until you get a non-tag.  "ref^0" is a shorthand for
 544          * "ref^{commit}".  "commit^{tree}" could be used to find the
 545          * top-level tree of the given commit.
 546          */
 547         if (len < 4 || name[len-1] != '}')
 548                 return -1;
 549
 550         for (sp = name + len - 1; name <= sp; sp--) {
 551                 int ch = *sp;
 552                 if (ch == '{' && name < sp && sp[-1] == '^')
 553                         break;
 554         }
 555         if (sp <= name)
 556                 return -1;
 557
 558         sp++; /* beginning of type name, or closing brace for empty */
 559         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 560                 expected_type = OBJ_COMMIT;
 561         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 562                 expected_type = OBJ_TREE;
 563         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 564                 expected_type = OBJ_BLOB;
 565         else if (sp[0] == '}')
 566                 expected_type = OBJ_NONE;
 567         else if (sp[0] == '/')
 568                 expected_type = OBJ_COMMIT;
 569         else
 570                 return -1;
 571
 572         if (get_sha1_1(name, sp - name - 2, outer))
 573                 return -1;
 574
 575         o = parse_object(outer);
 576         if (!o)
 577                 return -1;
 578         if (!expected_type) {
 579                 o = deref_tag(o, name, sp - name - 2);
 580                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 581                         return -1;
 582                 hashcpy(sha1, o->sha1);
 583                 return 0;
 584         }
 585
 586         /*
 587          * At this point, the syntax look correct, so
 588          * if we do not get the needed object, we should
 589          * barf.
 590          */
 591         o = peel_to_type(name, len, o, expected_type);
 592         if (!o)
 593                 return -1;
 594
 595         hashcpy(sha1, o->sha1);
 596         if (sp[0] == '/') {
 597                 /* "$commit^{/foo}" */
 598                 char *prefix;
 599                 int ret;
 600                 struct commit_list *list = NULL;
 601
 602                 /*
 603                  * $commit^{/}. Some regex implementation may reject.
 604                  * We don't need regex anyway. '' pattern always matches.
 605                  */
 606                 if (sp[1] == '}')
 607                         return 0;
 608
 609                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 610                 commit_list_insert((struct commit *)o, &list);
 611                 ret = get_sha1_oneline(prefix, sha1, list);
 612                 free(prefix);
 613                 return ret;
 614         }
 615         return 0;
 616 }
 617
 618 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 619 {
 620         const char *cp;
 621
 622         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 623                 char ch = *cp;
 624                 if (hexval(ch) & ~0377) {
 625                         /* We must be looking at g in "SOMETHING-g"
 626                          * for it to be describe output.
 627                          */
 628                         if (ch == 'g' && cp[-1] == '-') {
 629                                 cp++;
 630                                 len -= cp - name;
 631                                 return get_short_sha1(cp, len, sha1, 1);
 632                         }
 633                 }
 634         }
 635         return -1;
 636 }
 637
 638 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 639 {
 640         int ret, has_suffix;
 641         const char *cp;
 642
 643         /*
 644          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 645          */
 646         has_suffix = 0;
 647         for (cp = name + len - 1; name <= cp; cp--) {
 648                 int ch = *cp;
 649                 if ('0' <= ch && ch <= '9')
 650                         continue;
 651                 if (ch == '~' || ch == '^')
 652                         has_suffix = ch;
 653                 break;
 654         }
 655
 656         if (has_suffix) {
 657                 int num = 0;
 658                 int len1 = cp - name;
 659                 cp++;
 660                 while (cp < name + len)
 661                         num = num * 10 + *cp++ - '0';
 662                 if (!num && len1 == len - 1)
 663                         num = 1;
 664                 if (has_suffix == '^')
 665                         return get_parent(name, len1, sha1, num);
 666                 /* else if (has_suffix == '~') -- goes without saying */
 667                 return get_nth_ancestor(name, len1, sha1, num);
 668         }
 669
 670         ret = peel_onion(name, len, sha1);
 671         if (!ret)
 672                 return 0;
 673
 674         ret = get_sha1_basic(name, len, sha1);
 675         if (!ret)
 676                 return 0;
 677
 678         /* It could be describe output that is "SOMETHING-gXXXX" */
 679         ret = get_describe_name(name, len, sha1);
 680         if (!ret)
 681                 return 0;
 682
 683         return get_short_sha1(name, len, sha1, 0);
 684 }
 685
 686 /*
 687  * This interprets names like ':/Initial revision of "git"' by searching
 688  * through history and returning the first commit whose message starts
 689  * the given regular expression.
 690  *
 691  * For future extension, ':/!' is reserved. If you want to match a message
 692  * beginning with a '!', you have to repeat the exclamation mark.
 693  */
 694 #define ONELINE_SEEN (1u<<20)
 695
 696 static int handle_one_ref(const char *path,
 697                 const unsigned char *sha1, int flag, void *cb_data)
 698 {
 699         struct commit_list **list = cb_data;
 700         struct object *object = parse_object(sha1);
 701         if (!object)
 702                 return 0;
 703         if (object->type == OBJ_TAG) {
 704                 object = deref_tag(object, path, strlen(path));
 705                 if (!object)
 706                         return 0;
 707         }
 708         if (object->type != OBJ_COMMIT)
 709                 return 0;
 710         commit_list_insert_by_date((struct commit *)object, list);
 711         return 0;
 712 }
 713
 714 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 715                             struct commit_list *list)
 716 {
 717         struct commit_list *backup = NULL, *l;
 718         int found = 0;
 719         regex_t regex;
 720
 721         if (prefix[0] == '!') {
 722                 if (prefix[1] != '!')
 723                         die ("Invalid search pattern: %s", prefix);
 724                 prefix++;
 725         }
 726
 727         if (regcomp(&regex, prefix, REG_EXTENDED))
 728                 die("Invalid search pattern: %s", prefix);
 729
 730         for (l = list; l; l = l->next) {
 731                 l->item->object.flags |= ONELINE_SEEN;
 732                 commit_list_insert(l->item, &backup);
 733         }
 734         while (list) {
 735                 char *p, *to_free = NULL;
 736                 struct commit *commit;
 737                 enum object_type type;
 738                 unsigned long size;
 739                 int matches;
 740
 741                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 742                 if (!parse_object(commit->object.sha1))
 743                         continue;
 744                 if (commit->buffer)
 745                         p = commit->buffer;
 746                 else {
 747                         p = read_sha1_file(commit->object.sha1, &type, &size);
 748                         if (!p)
 749                                 continue;
 750                         to_free = p;
 751                 }
 752
 753                 p = strstr(p, "\n\n");
 754                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 755                 free(to_free);
 756
 757                 if (matches) {
 758                         hashcpy(sha1, commit->object.sha1);
 759                         found = 1;
 760                         break;
 761                 }
 762         }
 763         regfree(&regex);
 764         free_commit_list(list);
 765         for (l = backup; l; l = l->next)
 766                 clear_commit_marks(l->item, ONELINE_SEEN);
 767         free_commit_list(backup);
 768         return found ? 0 : -1;
 769 }
 770
 771 struct grab_nth_branch_switch_cbdata {
 772         long cnt, alloc;
 773         struct strbuf *buf;
 774 };
 775
 776 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 777                                   const char *email, unsigned long timestamp, int tz,
 778                                   const char *message, void *cb_data)
 779 {
 780         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 781         const char *match = NULL, *target = NULL;
 782         size_t len;
 783         int nth;
 784
 785         if (!prefixcmp(message, "checkout: moving from ")) {
 786                 match = message + strlen("checkout: moving from ");
 787                 target = strstr(match, " to ");
 788         }
 789
 790         if (!match || !target)
 791                 return 0;
 792
 793         len = target - match;
 794         nth = cb->cnt++ % cb->alloc;
 795         strbuf_reset(&cb->buf[nth]);
 796         strbuf_add(&cb->buf[nth], match, len);
 797         return 0;
 798 }
 799
 800 /*
 801  * Parse @{-N} syntax, return the number of characters parsed
 802  * if successful; otherwise signal an error with negative value.
 803  */
 804 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 805 {
 806         long nth;
 807         int i, retval;
 808         struct grab_nth_branch_switch_cbdata cb;
 809         const char *brace;
 810         char *num_end;
 811
 812         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 813                 return -1;
 814         brace = strchr(name, '}');
 815         if (!brace)
 816                 return -1;
 817         nth = strtol(name+3, &num_end, 10);
 818         if (num_end != brace)
 819                 return -1;
 820         if (nth <= 0)
 821                 return -1;
 822         cb.alloc = nth;
 823         cb.buf = xmalloc(nth * sizeof(struct strbuf));
 824         for (i = 0; i < nth; i++)
 825                 strbuf_init(&cb.buf[i], 20);
 826         cb.cnt = 0;
 827         retval = 0;
 828         for_each_recent_reflog_ent("HEAD", grab_nth_branch_switch, 40960, &cb);
 829         if (cb.cnt < nth) {
 830                 cb.cnt = 0;
 831                 for_each_reflog_ent("HEAD", grab_nth_branch_switch, &cb);
 832         }
 833         if (cb.cnt < nth)
 834                 goto release_return;
 835         i = cb.cnt % nth;
 836         strbuf_reset(buf);
 837         strbuf_add(buf, cb.buf[i].buf, cb.buf[i].len);
 838         retval = brace-name+1;
 839
 840 release_return:
 841         for (i = 0; i < nth; i++)
 842                 strbuf_release(&cb.buf[i]);
 843         free(cb.buf);
 844
 845         return retval;
 846 }
 847
 848 int get_sha1_mb(const char *name, unsigned char *sha1)
 849 {
 850         struct commit *one, *two;
 851         struct commit_list *mbs;
 852         unsigned char sha1_tmp[20];
 853         const char *dots;
 854         int st;
 855
 856         dots = strstr(name, "...");
 857         if (!dots)
 858                 return get_sha1(name, sha1);
 859         if (dots == name)
 860                 st = get_sha1("HEAD", sha1_tmp);
 861         else {
 862                 struct strbuf sb;
 863                 strbuf_init(&sb, dots - name);
 864                 strbuf_add(&sb, name, dots - name);
 865                 st = get_sha1(sb.buf, sha1_tmp);
 866                 strbuf_release(&sb);
 867         }
 868         if (st)
 869                 return st;
 870         one = lookup_commit_reference_gently(sha1_tmp, 0);
 871         if (!one)
 872                 return -1;
 873
 874         if (get_sha1(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
 875                 return -1;
 876         two = lookup_commit_reference_gently(sha1_tmp, 0);
 877         if (!two)
 878                 return -1;
 879         mbs = get_merge_bases(one, two, 1);
 880         if (!mbs || mbs->next)
 881                 st = -1;
 882         else {
 883                 st = 0;
 884                 hashcpy(sha1, mbs->item->object.sha1);
 885         }
 886         free_commit_list(mbs);
 887         return st;
 888 }
 889
 890 /*
 891  * This reads short-hand syntax that not only evaluates to a commit
 892  * object name, but also can act as if the end user spelled the name
 893  * of the branch from the command line.
 894  *
 895  * - "@{-N}" finds the name of the Nth previous branch we were on, and
 896  *   places the name of the branch in the given buf and returns the
 897  *   number of characters parsed if successful.
 898  *
 899  * - "<branch>@{upstream}" finds the name of the other ref that
 900  *   <branch> is configured to merge with (missing <branch> defaults
 901  *   to the current branch), and places the name of the branch in the
 902  *   given buf and returns the number of characters parsed if
 903  *   successful.
 904  *
 905  * If the input is not of the accepted format, it returns a negative
 906  * number to signal an error.
 907  *
 908  * If the input was ok but there are not N branch switches in the
 909  * reflog, it returns 0.
 910  */
 911 int interpret_branch_name(const char *name, struct strbuf *buf)
 912 {
 913         char *cp;
 914         struct branch *upstream;
 915         int namelen = strlen(name);
 916         int len = interpret_nth_prior_checkout(name, buf);
 917         int tmp_len;
 918
 919         if (!len)
 920                 return len; /* syntax Ok, not enough switches */
 921         if (0 < len && len == namelen)
 922                 return len; /* consumed all */
 923         else if (0 < len) {
 924                 /* we have extra data, which might need further processing */
 925                 struct strbuf tmp = STRBUF_INIT;
 926                 int used = buf->len;
 927                 int ret;
 928
 929                 strbuf_add(buf, name + len, namelen - len);
 930                 ret = interpret_branch_name(buf->buf, &tmp);
 931                 /* that data was not interpreted, remove our cruft */
 932                 if (ret < 0) {
 933                         strbuf_setlen(buf, used);
 934                         return len;
 935                 }
 936                 strbuf_reset(buf);
 937                 strbuf_addbuf(buf, &tmp);
 938                 strbuf_release(&tmp);
 939                 /* tweak for size of {-N} versus expanded ref name */
 940                 return ret - used + len;
 941         }
 942
 943         cp = strchr(name, '@');
 944         if (!cp)
 945                 return -1;
 946         tmp_len = upstream_mark(cp, namelen - (cp - name));
 947         if (!tmp_len)
 948                 return -1;
 949         len = cp + tmp_len - name;
 950         cp = xstrndup(name, cp - name);
 951         upstream = branch_get(*cp ? cp : NULL);
 952         if (!upstream
 953             || !upstream->merge
 954             || !upstream->merge[0]->dst)
 955                 return error("No upstream branch found for '%s'", cp);
 956         free(cp);
 957         cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
 958         strbuf_reset(buf);
 959         strbuf_addstr(buf, cp);
 960         free(cp);
 961         return len;
 962 }
 963
 964 int strbuf_branchname(struct strbuf *sb, const char *name)
 965 {
 966         int len = strlen(name);
 967         if (interpret_branch_name(name, sb) == len)
 968                 return 0;
 969         strbuf_add(sb, name, len);
 970         return len;
 971 }
 972
 973 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
 974 {
 975         strbuf_branchname(sb, name);
 976         if (name[0] == '-')
 977                 return CHECK_REF_FORMAT_ERROR;
 978         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
 979         return check_ref_format(sb->buf);
 980 }
 981
 982 /*
 983  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 984  * notably "xyz^" for "parent of xyz"
 985  */
 986 int get_sha1(const char *name, unsigned char *sha1)
 987 {
 988         struct object_context unused;
 989         return get_sha1_with_context(name, sha1, &unused);
 990 }
 991
 992 /* Must be called only when object_name:filename doesn't exist. */
 993 static void diagnose_invalid_sha1_path(const char *prefix,
 994                                        const char *filename,
 995                                        const unsigned char *tree_sha1,
 996                                        const char *object_name)
 997 {
 998         struct stat st;
 999         unsigned char sha1[20];
1000         unsigned mode;
1001
1002         if (!prefix)
1003                 prefix = "";
1004
1005         if (!lstat(filename, &st))
1006                 die("Path '%s' exists on disk, but not in '%s'.",
1007                     filename, object_name);
1008         if (errno == ENOENT || errno == ENOTDIR) {
1009                 char *fullname = xmalloc(strlen(filename)
1010                                              + strlen(prefix) + 1);
1011                 strcpy(fullname, prefix);
1012                 strcat(fullname, filename);
1013
1014                 if (!get_tree_entry(tree_sha1, fullname,
1015                                     sha1, &mode)) {
1016                         die("Path '%s' exists, but not '%s'.\n"
1017                             "Did you mean '%s:%s'?",
1018                             fullname,
1019                             filename,
1020                             object_name,
1021                             fullname);
1022                 }
1023                 die("Path '%s' does not exist in '%s'",
1024                     filename, object_name);
1025         }
1026 }
1027
1028 /* Must be called only when :stage:filename doesn't exist. */
1029 static void diagnose_invalid_index_path(int stage,
1030                                         const char *prefix,
1031                                         const char *filename)
1032 {
1033         struct stat st;
1034         struct cache_entry *ce;
1035         int pos;
1036         unsigned namelen = strlen(filename);
1037         unsigned fullnamelen;
1038         char *fullname;
1039
1040         if (!prefix)
1041                 prefix = "";
1042
1043         /* Wrong stage number? */
1044         pos = cache_name_pos(filename, namelen);
1045         if (pos < 0)
1046                 pos = -pos - 1;
1047         if (pos < active_nr) {
1048                 ce = active_cache[pos];
1049                 if (ce_namelen(ce) == namelen &&
1050                     !memcmp(ce->name, filename, namelen))
1051                         die("Path '%s' is in the index, but not at stage %d.\n"
1052                             "Did you mean ':%d:%s'?",
1053                             filename, stage,
1054                             ce_stage(ce), filename);
1055         }
1056
1057         /* Confusion between relative and absolute filenames? */
1058         fullnamelen = namelen + strlen(prefix);
1059         fullname = xmalloc(fullnamelen + 1);
1060         strcpy(fullname, prefix);
1061         strcat(fullname, filename);
1062         pos = cache_name_pos(fullname, fullnamelen);
1063         if (pos < 0)
1064                 pos = -pos - 1;
1065         if (pos < active_nr) {
1066                 ce = active_cache[pos];
1067                 if (ce_namelen(ce) == fullnamelen &&
1068                     !memcmp(ce->name, fullname, fullnamelen))
1069                         die("Path '%s' is in the index, but not '%s'.\n"
1070                             "Did you mean ':%d:%s'?",
1071                             fullname, filename,
1072                             ce_stage(ce), fullname);
1073         }
1074
1075         if (!lstat(filename, &st))
1076                 die("Path '%s' exists on disk, but not in the index.", filename);
1077         if (errno == ENOENT || errno == ENOTDIR)
1078                 die("Path '%s' does not exist (neither on disk nor in the index).",
1079                     filename);
1080
1081         free(fullname);
1082 }
1083
1084
1085 int get_sha1_with_mode_1(const char *name, unsigned char *sha1, unsigned *mode, int gently, const char *prefix)
1086 {
1087         struct object_context oc;
1088         int ret;
1089         ret = get_sha1_with_context_1(name, sha1, &oc, gently, prefix);
1090         *mode = oc.mode;
1091         return ret;
1092 }
1093
1094 static char *resolve_relative_path(const char *rel)
1095 {
1096         if (prefixcmp(rel, "./") && prefixcmp(rel, "../"))
1097                 return NULL;
1098
1099         if (!startup_info)
1100                 die("BUG: startup_info struct is not initialized.");
1101
1102         if (!is_inside_work_tree())
1103                 die("relative path syntax can't be used outside working tree.");
1104
1105         /* die() inside prefix_path() if resolved path is outside worktree */
1106         return prefix_path(startup_info->prefix,
1107                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1108                            rel);
1109 }
1110
1111 int get_sha1_with_context_1(const char *name, unsigned char *sha1,
1112                             struct object_context *oc,
1113                             int gently, const char *prefix)
1114 {
1115         int ret, bracket_depth;
1116         int namelen = strlen(name);
1117         const char *cp;
1118
1119         memset(oc, 0, sizeof(*oc));
1120         oc->mode = S_IFINVALID;
1121         ret = get_sha1_1(name, namelen, sha1);
1122         if (!ret)
1123                 return ret;
1124         /* sha1:path --> object name of path in ent sha1
1125          * :path -> object name of absolute path in index
1126          * :./path -> object name of path relative to cwd in index
1127          * :[0-3]:path -> object name of path in index at stage
1128          * :/foo -> recent commit matching foo
1129          */
1130         if (name[0] == ':') {
1131                 int stage = 0;
1132                 struct cache_entry *ce;
1133                 char *new_path = NULL;
1134                 int pos;
1135                 if (namelen > 2 && name[1] == '/') {
1136                         struct commit_list *list = NULL;
1137                         for_each_ref(handle_one_ref, &list);
1138                         return get_sha1_oneline(name + 2, sha1, list);
1139                 }
1140                 if (namelen < 3 ||
1141                     name[2] != ':' ||
1142                     name[1] < '0' || '3' < name[1])
1143                         cp = name + 1;
1144                 else {
1145                         stage = name[1] - '0';
1146                         cp = name + 3;
1147                 }
1148                 new_path = resolve_relative_path(cp);
1149                 if (!new_path) {
1150                         namelen = namelen - (cp - name);
1151                 } else {
1152                         cp = new_path;
1153                         namelen = strlen(cp);
1154                 }
1155
1156                 strncpy(oc->path, cp,
1157                         sizeof(oc->path));
1158                 oc->path[sizeof(oc->path)-1] = '\0';
1159
1160                 if (!active_cache)
1161                         read_cache();
1162                 pos = cache_name_pos(cp, namelen);
1163                 if (pos < 0)
1164                         pos = -pos - 1;
1165                 while (pos < active_nr) {
1166                         ce = active_cache[pos];
1167                         if (ce_namelen(ce) != namelen ||
1168                             memcmp(ce->name, cp, namelen))
1169                                 break;
1170                         if (ce_stage(ce) == stage) {
1171                                 hashcpy(sha1, ce->sha1);
1172                                 oc->mode = ce->ce_mode;
1173                                 free(new_path);
1174                                 return 0;
1175                         }
1176                         pos++;
1177                 }
1178                 if (!gently)
1179                         diagnose_invalid_index_path(stage, prefix, cp);
1180                 free(new_path);
1181                 return -1;
1182         }
1183         for (cp = name, bracket_depth = 0; *cp; cp++) {
1184                 if (*cp == '{')
1185                         bracket_depth++;
1186                 else if (bracket_depth && *cp == '}')
1187                         bracket_depth--;
1188                 else if (!bracket_depth && *cp == ':')
1189                         break;
1190         }
1191         if (*cp == ':') {
1192                 unsigned char tree_sha1[20];
1193                 char *object_name = NULL;
1194                 if (!gently) {
1195                         object_name = xmalloc(cp-name+1);
1196                         strncpy(object_name, name, cp-name);
1197                         object_name[cp-name] = '\0';
1198                 }
1199                 if (!get_sha1_1(name, cp-name, tree_sha1)) {
1200                         const char *filename = cp+1;
1201                         char *new_filename = NULL;
1202
1203                         new_filename = resolve_relative_path(filename);
1204                         if (new_filename)
1205                                 filename = new_filename;
1206                         ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1207                         if (!gently) {
1208                                 diagnose_invalid_sha1_path(prefix, filename,
1209                                                            tree_sha1, object_name);
1210                                 free(object_name);
1211                         }
1212                         hashcpy(oc->tree, tree_sha1);
1213                         strncpy(oc->path, filename,
1214                                 sizeof(oc->path));
1215                         oc->path[sizeof(oc->path)-1] = '\0';
1216
1217                         free(new_filename);
1218                         return ret;
1219                 } else {
1220                         if (!gently)
1221                                 die("Invalid object name '%s'.", object_name);
1222                 }
1223         }
1224         return ret;
1225 }