refs.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "tag.h"
   5 #include "dir.h"
   6
   7 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
   8 #define REF_KNOWS_PEELED 04
   9 #define REF_BROKEN 010
  10
  11 struct ref_list {
  12         struct ref_list *next;
  13         unsigned char flag; /* ISSYMREF? ISPACKED? */
  14         unsigned char sha1[20];
  15         unsigned char peeled[20];
  16         char name[FLEX_ARRAY];
  17 };
  18
  19 static const char *parse_ref_line(char *line, unsigned char *sha1)
  20 {
  21         /*
  22          * 42: the answer to everything.
  23          *
  24          * In this case, it happens to be the answer to
  25          *  40 (length of sha1 hex representation)
  26          *  +1 (space in between hex and name)
  27          *  +1 (newline at the end of the line)
  28          */
  29         int len = strlen(line) - 42;
  30
  31         if (len <= 0)
  32                 return NULL;
  33         if (get_sha1_hex(line, sha1) < 0)
  34                 return NULL;
  35         if (!isspace(line[40]))
  36                 return NULL;
  37         line += 41;
  38         if (isspace(*line))
  39                 return NULL;
  40         if (line[len] != '\n')
  41                 return NULL;
  42         line[len] = 0;
  43
  44         return line;
  45 }
  46
  47 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  48                                 int flag, struct ref_list *list,
  49                                 struct ref_list **new_entry)
  50 {
  51         int len;
  52         struct ref_list *entry;
  53
  54         /* Allocate it and add it in.. */
  55         len = strlen(name) + 1;
  56         entry = xmalloc(sizeof(struct ref_list) + len);
  57         hashcpy(entry->sha1, sha1);
  58         hashclr(entry->peeled);
  59         if (check_refname_format(name, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
  60                 die("Reference has invalid format: '%s'", name);
  61         memcpy(entry->name, name, len);
  62         entry->flag = flag;
  63         entry->next = list;
  64         if (new_entry)
  65                 *new_entry = entry;
  66         return entry;
  67 }
  68
  69 /* merge sort the ref list */
  70 static struct ref_list *sort_ref_list(struct ref_list *list)
  71 {
  72         int psize, qsize, last_merge_count, cmp;
  73         struct ref_list *p, *q, *l, *e;
  74         struct ref_list *new_list = list;
  75         int k = 1;
  76         int merge_count = 0;
  77
  78         if (!list)
  79                 return list;
  80
  81         do {
  82                 last_merge_count = merge_count;
  83                 merge_count = 0;
  84
  85                 psize = 0;
  86
  87                 p = new_list;
  88                 q = new_list;
  89                 new_list = NULL;
  90                 l = NULL;
  91
  92                 while (p) {
  93                         merge_count++;
  94
  95                         while (psize < k && q->next) {
  96                                 q = q->next;
  97                                 psize++;
  98                         }
  99                         qsize = k;
 100
 101                         while ((psize > 0) || (qsize > 0 && q)) {
 102                                 if (qsize == 0 || !q) {
 103                                         e = p;
 104                                         p = p->next;
 105                                         psize--;
 106                                 } else if (psize == 0) {
 107                                         e = q;
 108                                         q = q->next;
 109                                         qsize--;
 110                                 } else {
 111                                         cmp = strcmp(q->name, p->name);
 112                                         if (cmp < 0) {
 113                                                 e = q;
 114                                                 q = q->next;
 115                                                 qsize--;
 116                                         } else if (cmp > 0) {
 117                                                 e = p;
 118                                                 p = p->next;
 119                                                 psize--;
 120                                         } else {
 121                                                 if (hashcmp(q->sha1, p->sha1))
 122                                                         die("Duplicated ref, and SHA1s don't match: %s",
 123                                                             q->name);
 124                                                 warning("Duplicated ref: %s", q->name);
 125                                                 e = q;
 126                                                 q = q->next;
 127                                                 qsize--;
 128                                                 free(e);
 129                                                 e = p;
 130                                                 p = p->next;
 131                                                 psize--;
 132                                         }
 133                                 }
 134
 135                                 e->next = NULL;
 136
 137                                 if (l)
 138                                         l->next = e;
 139                                 if (!new_list)
 140                                         new_list = e;
 141                                 l = e;
 142                         }
 143
 144                         p = q;
 145                 };
 146
 147                 k = k * 2;
 148         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
 149
 150         return new_list;
 151 }
 152
 153 /*
 154  * Future: need to be in "struct repository"
 155  * when doing a full libification.
 156  */
 157 static struct cached_refs {
 158         char did_loose;
 159         char did_packed;
 160         struct ref_list *loose;
 161         struct ref_list *packed;
 162 } cached_refs, submodule_refs;
 163 static struct ref_list *current_ref;
 164
 165 static struct ref_list *extra_refs;
 166
 167 static void free_ref_list(struct ref_list *list)
 168 {
 169         struct ref_list *next;
 170         for ( ; list; list = next) {
 171                 next = list->next;
 172                 free(list);
 173         }
 174 }
 175
 176 static void invalidate_cached_refs(void)
 177 {
 178         struct cached_refs *ca = &cached_refs;
 179
 180         if (ca->did_loose && ca->loose)
 181                 free_ref_list(ca->loose);
 182         if (ca->did_packed && ca->packed)
 183                 free_ref_list(ca->packed);
 184         ca->loose = ca->packed = NULL;
 185         ca->did_loose = ca->did_packed = 0;
 186 }
 187
 188 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 189 {
 190         struct ref_list *list = NULL;
 191         struct ref_list *last = NULL;
 192         char refline[PATH_MAX];
 193         int flag = REF_ISPACKED;
 194
 195         while (fgets(refline, sizeof(refline), f)) {
 196                 unsigned char sha1[20];
 197                 const char *name;
 198                 static const char header[] = "# pack-refs with:";
 199
 200                 if (!strncmp(refline, header, sizeof(header)-1)) {
 201                         const char *traits = refline + sizeof(header) - 1;
 202                         if (strstr(traits, " peeled "))
 203                                 flag |= REF_KNOWS_PEELED;
 204                         /* perhaps other traits later as well */
 205                         continue;
 206                 }
 207
 208                 name = parse_ref_line(refline, sha1);
 209                 if (name) {
 210                         list = add_ref(name, sha1, flag, list, &last);
 211                         continue;
 212                 }
 213                 if (last &&
 214                     refline[0] == '^' &&
 215                     strlen(refline) == 42 &&
 216                     refline[41] == '\n' &&
 217                     !get_sha1_hex(refline + 1, sha1))
 218                         hashcpy(last->peeled, sha1);
 219         }
 220         cached_refs->packed = sort_ref_list(list);
 221 }
 222
 223 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 224 {
 225         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
 226 }
 227
 228 void clear_extra_refs(void)
 229 {
 230         free_ref_list(extra_refs);
 231         extra_refs = NULL;
 232 }
 233
 234 static struct ref_list *get_packed_refs(const char *submodule)
 235 {
 236         const char *packed_refs_file;
 237         struct cached_refs *refs;
 238
 239         if (submodule) {
 240                 packed_refs_file = git_path_submodule(submodule, "packed-refs");
 241                 refs = &submodule_refs;
 242                 free_ref_list(refs->packed);
 243         } else {
 244                 packed_refs_file = git_path("packed-refs");
 245                 refs = &cached_refs;
 246         }
 247
 248         if (!refs->did_packed || submodule) {
 249                 FILE *f = fopen(packed_refs_file, "r");
 250                 refs->packed = NULL;
 251                 if (f) {
 252                         read_packed_refs(f, refs);
 253                         fclose(f);
 254                 }
 255                 refs->did_packed = 1;
 256         }
 257         return refs->packed;
 258 }
 259
 260 static struct ref_list *get_ref_dir(const char *submodule, const char *base,
 261                                     struct ref_list *list)
 262 {
 263         DIR *dir;
 264         const char *path;
 265
 266         if (submodule)
 267                 path = git_path_submodule(submodule, "%s", base);
 268         else
 269                 path = git_path("%s", base);
 270
 271
 272         dir = opendir(path);
 273
 274         if (dir) {
 275                 struct dirent *de;
 276                 int baselen = strlen(base);
 277                 char *ref = xmalloc(baselen + 257);
 278
 279                 memcpy(ref, base, baselen);
 280                 if (baselen && base[baselen-1] != '/')
 281                         ref[baselen++] = '/';
 282
 283                 while ((de = readdir(dir)) != NULL) {
 284                         unsigned char sha1[20];
 285                         struct stat st;
 286                         int flag;
 287                         int namelen;
 288                         const char *refdir;
 289
 290                         if (de->d_name[0] == '.')
 291                                 continue;
 292                         namelen = strlen(de->d_name);
 293                         if (namelen > 255)
 294                                 continue;
 295                         if (has_extension(de->d_name, ".lock"))
 296                                 continue;
 297                         memcpy(ref + baselen, de->d_name, namelen+1);
 298                         refdir = submodule
 299                                 ? git_path_submodule(submodule, "%s", ref)
 300                                 : git_path("%s", ref);
 301                         if (stat(refdir, &st) < 0)
 302                                 continue;
 303                         if (S_ISDIR(st.st_mode)) {
 304                                 list = get_ref_dir(submodule, ref, list);
 305                                 continue;
 306                         }
 307                         if (submodule) {
 308                                 hashclr(sha1);
 309                                 flag = 0;
 310                                 if (resolve_gitlink_ref(submodule, ref, sha1) < 0) {
 311                                         hashclr(sha1);
 312                                         flag |= REF_BROKEN;
 313                                 }
 314                         } else
 315                                 if (!resolve_ref(ref, sha1, 1, &flag)) {
 316                                         hashclr(sha1);
 317                                         flag |= REF_BROKEN;
 318                                 }
 319                         list = add_ref(ref, sha1, flag, list, NULL);
 320                 }
 321                 free(ref);
 322                 closedir(dir);
 323         }
 324         return sort_ref_list(list);
 325 }
 326
 327 struct warn_if_dangling_data {
 328         FILE *fp;
 329         const char *refname;
 330         const char *msg_fmt;
 331 };
 332
 333 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 334                                    int flags, void *cb_data)
 335 {
 336         struct warn_if_dangling_data *d = cb_data;
 337         const char *resolves_to;
 338         unsigned char junk[20];
 339
 340         if (!(flags & REF_ISSYMREF))
 341                 return 0;
 342
 343         resolves_to = resolve_ref(refname, junk, 0, NULL);
 344         if (!resolves_to || strcmp(resolves_to, d->refname))
 345                 return 0;
 346
 347         fprintf(d->fp, d->msg_fmt, refname);
 348         return 0;
 349 }
 350
 351 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 352 {
 353         struct warn_if_dangling_data data;
 354
 355         data.fp = fp;
 356         data.refname = refname;
 357         data.msg_fmt = msg_fmt;
 358         for_each_rawref(warn_if_dangling_symref, &data);
 359 }
 360
 361 static struct ref_list *get_loose_refs(const char *submodule)
 362 {
 363         if (submodule) {
 364                 free_ref_list(submodule_refs.loose);
 365                 submodule_refs.loose = get_ref_dir(submodule, "refs", NULL);
 366                 return submodule_refs.loose;
 367         }
 368
 369         if (!cached_refs.did_loose) {
 370                 cached_refs.loose = get_ref_dir(NULL, "refs", NULL);
 371                 cached_refs.did_loose = 1;
 372         }
 373         return cached_refs.loose;
 374 }
 375
 376 /* We allow "recursive" symbolic refs. Only within reason, though */
 377 #define MAXDEPTH 5
 378 #define MAXREFLEN (1024)
 379
 380 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 381 {
 382         FILE *f;
 383         struct cached_refs refs;
 384         struct ref_list *ref;
 385         int retval;
 386
 387         strcpy(name + pathlen, "packed-refs");
 388         f = fopen(name, "r");
 389         if (!f)
 390                 return -1;
 391         read_packed_refs(f, &refs);
 392         fclose(f);
 393         ref = refs.packed;
 394         retval = -1;
 395         while (ref) {
 396                 if (!strcmp(ref->name, refname)) {
 397                         retval = 0;
 398                         memcpy(result, ref->sha1, 20);
 399                         break;
 400                 }
 401                 ref = ref->next;
 402         }
 403         free_ref_list(refs.packed);
 404         return retval;
 405 }
 406
 407 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 408 {
 409         int fd, len = strlen(refname);
 410         char buffer[128], *p;
 411
 412         if (recursion > MAXDEPTH || len > MAXREFLEN)
 413                 return -1;
 414         memcpy(name + pathlen, refname, len+1);
 415         fd = open(name, O_RDONLY);
 416         if (fd < 0)
 417                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 418
 419         len = read(fd, buffer, sizeof(buffer)-1);
 420         close(fd);
 421         if (len < 0)
 422                 return -1;
 423         while (len && isspace(buffer[len-1]))
 424                 len--;
 425         buffer[len] = 0;
 426
 427         /* Was it a detached head or an old-fashioned symlink? */
 428         if (!get_sha1_hex(buffer, result))
 429                 return 0;
 430
 431         /* Symref? */
 432         if (strncmp(buffer, "ref:", 4))
 433                 return -1;
 434         p = buffer + 4;
 435         while (isspace(*p))
 436                 p++;
 437
 438         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 439 }
 440
 441 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 442 {
 443         int len = strlen(path), retval;
 444         char *gitdir;
 445         const char *tmp;
 446
 447         while (len && path[len-1] == '/')
 448                 len--;
 449         if (!len)
 450                 return -1;
 451         gitdir = xmalloc(len + MAXREFLEN + 8);
 452         memcpy(gitdir, path, len);
 453         memcpy(gitdir + len, "/.git", 6);
 454         len += 5;
 455
 456         tmp = read_gitfile(gitdir);
 457         if (tmp) {
 458                 free(gitdir);
 459                 len = strlen(tmp);
 460                 gitdir = xmalloc(len + MAXREFLEN + 3);
 461                 memcpy(gitdir, tmp, len);
 462         }
 463         gitdir[len] = '/';
 464         gitdir[++len] = '\0';
 465         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 466         free(gitdir);
 467         return retval;
 468 }
 469
 470 /*
 471  * Try to read ref from the packed references.  On success, set sha1
 472  * and return 0; otherwise, return -1.
 473  */
 474 static int get_packed_ref(const char *ref, unsigned char *sha1)
 475 {
 476         struct ref_list *list = get_packed_refs(NULL);
 477         while (list) {
 478                 if (!strcmp(ref, list->name)) {
 479                         hashcpy(sha1, list->sha1);
 480                         return 0;
 481                 }
 482                 list = list->next;
 483         }
 484         return -1;
 485 }
 486
 487 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 488 {
 489         int depth = MAXDEPTH;
 490         ssize_t len;
 491         char buffer[256];
 492         static char ref_buffer[256];
 493         char path[PATH_MAX];
 494
 495         if (flag)
 496                 *flag = 0;
 497
 498         if (check_refname_format(ref, REFNAME_ALLOW_ONELEVEL))
 499                 return NULL;
 500
 501         for (;;) {
 502                 struct stat st;
 503                 char *buf;
 504                 int fd;
 505
 506                 if (--depth < 0)
 507                         return NULL;
 508
 509                 git_snpath(path, sizeof(path), "%s", ref);
 510
 511                 if (lstat(path, &st) < 0) {
 512                         if (errno != ENOENT)
 513                                 return NULL;
 514                         /*
 515                          * The loose reference file does not exist;
 516                          * check for a packed reference.
 517                          */
 518                         if (!get_packed_ref(ref, sha1)) {
 519                                 if (flag)
 520                                         *flag |= REF_ISPACKED;
 521                                 return ref;
 522                         }
 523                         /* The reference is not a packed reference, either. */
 524                         if (reading) {
 525                                 return NULL;
 526                         } else {
 527                                 hashclr(sha1);
 528                                 return ref;
 529                         }
 530                 }
 531
 532                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 533                 if (S_ISLNK(st.st_mode)) {
 534                         len = readlink(path, buffer, sizeof(buffer)-1);
 535                         if (len < 0)
 536                                 return NULL;
 537                         buffer[len] = 0;
 538                         if (!prefixcmp(buffer, "refs/") &&
 539                                         !check_refname_format(buffer, 0)) {
 540                                 strcpy(ref_buffer, buffer);
 541                                 ref = ref_buffer;
 542                                 if (flag)
 543                                         *flag |= REF_ISSYMREF;
 544                                 continue;
 545                         }
 546                 }
 547
 548                 /* Is it a directory? */
 549                 if (S_ISDIR(st.st_mode)) {
 550                         errno = EISDIR;
 551                         return NULL;
 552                 }
 553
 554                 /*
 555                  * Anything else, just open it and try to use it as
 556                  * a ref
 557                  */
 558                 fd = open(path, O_RDONLY);
 559                 if (fd < 0)
 560                         return NULL;
 561                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 562                 close(fd);
 563                 if (len < 0)
 564                         return NULL;
 565                 while (len && isspace(buffer[len-1]))
 566                         len--;
 567                 buffer[len] = '\0';
 568
 569                 /*
 570                  * Is it a symbolic ref?
 571                  */
 572                 if (prefixcmp(buffer, "ref:"))
 573                         break;
 574                 buf = buffer + 4;
 575                 while (isspace(*buf))
 576                         buf++;
 577                 if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
 578                         warning("symbolic reference in %s is formatted incorrectly",
 579                                 path);
 580                         return NULL;
 581                 }
 582                 ref = strcpy(ref_buffer, buf);
 583                 if (flag)
 584                         *flag |= REF_ISSYMREF;
 585         }
 586         /* Please note that FETCH_HEAD has a second line containing other data. */
 587         if (get_sha1_hex(buffer, sha1) || (buffer[40] != '\0' && !isspace(buffer[40]))) {
 588                 warning("reference in %s is formatted incorrectly", path);
 589                 return NULL;
 590         }
 591         return ref;
 592 }
 593
 594 /* The argument to filter_refs */
 595 struct ref_filter {
 596         const char *pattern;
 597         each_ref_fn *fn;
 598         void *cb_data;
 599 };
 600
 601 int read_ref(const char *ref, unsigned char *sha1)
 602 {
 603         if (resolve_ref(ref, sha1, 1, NULL))
 604                 return 0;
 605         return -1;
 606 }
 607
 608 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 609 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 610                       int flags, void *cb_data, struct ref_list *entry)
 611 {
 612         if (prefixcmp(entry->name, base))
 613                 return 0;
 614
 615         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 616                 if (entry->flag & REF_BROKEN)
 617                         return 0; /* ignore dangling symref */
 618                 if (!has_sha1_file(entry->sha1)) {
 619                         error("%s does not point to a valid object!", entry->name);
 620                         return 0;
 621                 }
 622         }
 623         current_ref = entry;
 624         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 625 }
 626
 627 static int filter_refs(const char *ref, const unsigned char *sha, int flags,
 628         void *data)
 629 {
 630         struct ref_filter *filter = (struct ref_filter *)data;
 631         if (fnmatch(filter->pattern, ref, 0))
 632                 return 0;
 633         return filter->fn(ref, sha, flags, filter->cb_data);
 634 }
 635
 636 int peel_ref(const char *ref, unsigned char *sha1)
 637 {
 638         int flag;
 639         unsigned char base[20];
 640         struct object *o;
 641
 642         if (current_ref && (current_ref->name == ref
 643                 || !strcmp(current_ref->name, ref))) {
 644                 if (current_ref->flag & REF_KNOWS_PEELED) {
 645                         hashcpy(sha1, current_ref->peeled);
 646                         return 0;
 647                 }
 648                 hashcpy(base, current_ref->sha1);
 649                 goto fallback;
 650         }
 651
 652         if (!resolve_ref(ref, base, 1, &flag))
 653                 return -1;
 654
 655         if ((flag & REF_ISPACKED)) {
 656                 struct ref_list *list = get_packed_refs(NULL);
 657
 658                 while (list) {
 659                         if (!strcmp(list->name, ref)) {
 660                                 if (list->flag & REF_KNOWS_PEELED) {
 661                                         hashcpy(sha1, list->peeled);
 662                                         return 0;
 663                                 }
 664                                 /* older pack-refs did not leave peeled ones */
 665                                 break;
 666                         }
 667                         list = list->next;
 668                 }
 669         }
 670
 671 fallback:
 672         o = parse_object(base);
 673         if (o && o->type == OBJ_TAG) {
 674                 o = deref_tag(o, ref, 0);
 675                 if (o) {
 676                         hashcpy(sha1, o->sha1);
 677                         return 0;
 678                 }
 679         }
 680         return -1;
 681 }
 682
 683 static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
 684                            int trim, int flags, void *cb_data)
 685 {
 686         int retval = 0;
 687         struct ref_list *packed = get_packed_refs(submodule);
 688         struct ref_list *loose = get_loose_refs(submodule);
 689
 690         struct ref_list *extra;
 691
 692         for (extra = extra_refs; extra; extra = extra->next)
 693                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 694
 695         while (packed && loose) {
 696                 struct ref_list *entry;
 697                 int cmp = strcmp(packed->name, loose->name);
 698                 if (!cmp) {
 699                         packed = packed->next;
 700                         continue;
 701                 }
 702                 if (cmp > 0) {
 703                         entry = loose;
 704                         loose = loose->next;
 705                 } else {
 706                         entry = packed;
 707                         packed = packed->next;
 708                 }
 709                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 710                 if (retval)
 711                         goto end_each;
 712         }
 713
 714         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 715                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 716                 if (retval)
 717                         goto end_each;
 718         }
 719
 720 end_each:
 721         current_ref = NULL;
 722         return retval;
 723 }
 724
 725
 726 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 727 {
 728         unsigned char sha1[20];
 729         int flag;
 730
 731         if (submodule) {
 732                 if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
 733                         return fn("HEAD", sha1, 0, cb_data);
 734
 735                 return 0;
 736         }
 737
 738         if (resolve_ref("HEAD", sha1, 1, &flag))
 739                 return fn("HEAD", sha1, flag, cb_data);
 740
 741         return 0;
 742 }
 743
 744 int head_ref(each_ref_fn fn, void *cb_data)
 745 {
 746         return do_head_ref(NULL, fn, cb_data);
 747 }
 748
 749 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 750 {
 751         return do_head_ref(submodule, fn, cb_data);
 752 }
 753
 754 int for_each_ref(each_ref_fn fn, void *cb_data)
 755 {
 756         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
 757 }
 758
 759 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 760 {
 761         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
 762 }
 763
 764 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 765 {
 766         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
 767 }
 768
 769 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 770                 each_ref_fn fn, void *cb_data)
 771 {
 772         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
 773 }
 774
 775 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 776 {
 777         return for_each_ref_in("refs/tags/", fn, cb_data);
 778 }
 779
 780 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 781 {
 782         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 783 }
 784
 785 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 786 {
 787         return for_each_ref_in("refs/heads/", fn, cb_data);
 788 }
 789
 790 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 791 {
 792         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 793 }
 794
 795 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 796 {
 797         return for_each_ref_in("refs/remotes/", fn, cb_data);
 798 }
 799
 800 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 801 {
 802         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 803 }
 804
 805 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 806 {
 807         return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
 808 }
 809
 810 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 811 {
 812         struct strbuf buf = STRBUF_INIT;
 813         int ret = 0;
 814         unsigned char sha1[20];
 815         int flag;
 816
 817         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 818         if (resolve_ref(buf.buf, sha1, 1, &flag))
 819                 ret = fn(buf.buf, sha1, flag, cb_data);
 820         strbuf_release(&buf);
 821
 822         return ret;
 823 }
 824
 825 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
 826 {
 827         struct strbuf buf = STRBUF_INIT;
 828         int ret;
 829         strbuf_addf(&buf, "%srefs/", get_git_namespace());
 830         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
 831         strbuf_release(&buf);
 832         return ret;
 833 }
 834
 835 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 836         const char *prefix, void *cb_data)
 837 {
 838         struct strbuf real_pattern = STRBUF_INIT;
 839         struct ref_filter filter;
 840         int ret;
 841
 842         if (!prefix && prefixcmp(pattern, "refs/"))
 843                 strbuf_addstr(&real_pattern, "refs/");
 844         else if (prefix)
 845                 strbuf_addstr(&real_pattern, prefix);
 846         strbuf_addstr(&real_pattern, pattern);
 847
 848         if (!has_glob_specials(pattern)) {
 849                 /* Append implied '/' '*' if not present. */
 850                 if (real_pattern.buf[real_pattern.len - 1] != '/')
 851                         strbuf_addch(&real_pattern, '/');
 852                 /* No need to check for '*', there is none. */
 853                 strbuf_addch(&real_pattern, '*');
 854         }
 855
 856         filter.pattern = real_pattern.buf;
 857         filter.fn = fn;
 858         filter.cb_data = cb_data;
 859         ret = for_each_ref(filter_refs, &filter);
 860
 861         strbuf_release(&real_pattern);
 862         return ret;
 863 }
 864
 865 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 866 {
 867         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 868 }
 869
 870 int for_each_rawref(each_ref_fn fn, void *cb_data)
 871 {
 872         return do_for_each_ref(NULL, "", fn, 0,
 873                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 874 }
 875
 876 /*
 877  * Make sure "ref" is something reasonable to have under ".git/refs/";
 878  * We do not like it if:
 879  *
 880  * - any path component of it begins with ".", or
 881  * - it has double dots "..", or
 882  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 883  * - it ends with a "/".
 884  * - it ends with ".lock"
 885  * - it contains a "\" (backslash)
 886  */
 887
 888 /* Return true iff ch is not allowed in reference names. */
 889 static inline int bad_ref_char(int ch)
 890 {
 891         if (((unsigned) ch) <= ' ' || ch == 0x7f ||
 892             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 893                 return 1;
 894         /* 2.13 Pattern Matching Notation */
 895         if (ch == '*' || ch == '?' || ch == '[') /* Unsupported */
 896                 return 1;
 897         return 0;
 898 }
 899
 900 /*
 901  * Try to read one refname component from the front of ref.  Return
 902  * the length of the component found, or -1 if the component is not
 903  * legal.
 904  */
 905 static int check_refname_component(const char *ref, int flags)
 906 {
 907         const char *cp;
 908         char last = '\0';
 909
 910         for (cp = ref; ; cp++) {
 911                 char ch = *cp;
 912                 if (ch == '\0' || ch == '/')
 913                         break;
 914                 if (bad_ref_char(ch))
 915                         return -1; /* Illegal character in refname. */
 916                 if (last == '.' && ch == '.')
 917                         return -1; /* Refname contains "..". */
 918                 if (last == '@' && ch == '{')
 919                         return -1; /* Refname contains "@{". */
 920                 last = ch;
 921         }
 922         if (cp == ref)
 923                 return -1; /* Component has zero length. */
 924         if (ref[0] == '.') {
 925                 if (!(flags & REFNAME_DOT_COMPONENT))
 926                         return -1; /* Component starts with '.'. */
 927                 /*
 928                  * Even if leading dots are allowed, don't allow "."
 929                  * as a component (".." is prevented by a rule above).
 930                  */
 931                 if (ref[1] == '\0')
 932                         return -1; /* Component equals ".". */
 933         }
 934         if (cp - ref >= 5 && !memcmp(cp - 5, ".lock", 5))
 935                 return -1; /* Refname ends with ".lock". */
 936         return cp - ref;
 937 }
 938
 939 int check_refname_format(const char *ref, int flags)
 940 {
 941         int component_len, component_count = 0;
 942
 943         while (1) {
 944                 /* We are at the start of a path component. */
 945                 component_len = check_refname_component(ref, flags);
 946                 if (component_len < 0) {
 947                         if ((flags & REFNAME_REFSPEC_PATTERN) &&
 948                                         ref[0] == '*' &&
 949                                         (ref[1] == '\0' || ref[1] == '/')) {
 950                                 /* Accept one wildcard as a full refname component. */
 951                                 flags &= ~REFNAME_REFSPEC_PATTERN;
 952                                 component_len = 1;
 953                         } else {
 954                                 return -1;
 955                         }
 956                 }
 957                 component_count++;
 958                 if (ref[component_len] == '\0')
 959                         break;
 960                 /* Skip to next component. */
 961                 ref += component_len + 1;
 962         }
 963
 964         if (ref[component_len - 1] == '.')
 965                 return -1; /* Refname ends with '.'. */
 966         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 967                 return -1; /* Refname has only one component. */
 968         return 0;
 969 }
 970
 971 const char *prettify_refname(const char *name)
 972 {
 973         return name + (
 974                 !prefixcmp(name, "refs/heads/") ? 11 :
 975                 !prefixcmp(name, "refs/tags/") ? 10 :
 976                 !prefixcmp(name, "refs/remotes/") ? 13 :
 977                 0);
 978 }
 979
 980 const char *ref_rev_parse_rules[] = {
 981         "%.*s",
 982         "refs/%.*s",
 983         "refs/tags/%.*s",
 984         "refs/heads/%.*s",
 985         "refs/remotes/%.*s",
 986         "refs/remotes/%.*s/HEAD",
 987         NULL
 988 };
 989
 990 const char *ref_fetch_rules[] = {
 991         "%.*s",
 992         "refs/%.*s",
 993         "refs/heads/%.*s",
 994         NULL
 995 };
 996
 997 static int refname_ok_at_root_level(const char *str, int len)
 998 {
 999         if (len >= 5 && !memcmp(str, "refs/", 5))
1000                 return 1;
1001
1002         while (len--) {
1003                 char ch = *str++;
1004
1005                 /*
1006                  * Only accept likes of .git/HEAD, .git/MERGE_HEAD at
1007                  * the root level as a ref.
1008                  */
1009                 if (ch != '_' && (ch < 'A' || 'Z' < ch))
1010                         return 0;
1011         }
1012         return 1;
1013 }
1014
1015 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
1016 {
1017         const char **p;
1018         const int abbrev_name_len = strlen(abbrev_name);
1019
1020         for (p = rules; *p; p++) {
1021                 if (p == rules &&
1022                     !refname_ok_at_root_level(abbrev_name, abbrev_name_len))
1023                         continue;
1024                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1025                         return 1;
1026                 }
1027         }
1028
1029         return 0;
1030 }
1031
1032 static struct ref_lock *verify_lock(struct ref_lock *lock,
1033         const unsigned char *old_sha1, int mustexist)
1034 {
1035         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1036                 error("Can't verify ref %s", lock->ref_name);
1037                 unlock_ref(lock);
1038                 return NULL;
1039         }
1040         if (hashcmp(lock->old_sha1, old_sha1)) {
1041                 error("Ref %s is at %s but expected %s", lock->ref_name,
1042                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1043                 unlock_ref(lock);
1044                 return NULL;
1045         }
1046         return lock;
1047 }
1048
1049 static int remove_empty_directories(const char *file)
1050 {
1051         /* we want to create a file but there is a directory there;
1052          * if that is an empty directory (or a directory that contains
1053          * only empty directories), remove them.
1054          */
1055         struct strbuf path;
1056         int result;
1057
1058         strbuf_init(&path, 20);
1059         strbuf_addstr(&path, file);
1060
1061         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1062
1063         strbuf_release(&path);
1064
1065         return result;
1066 }
1067
1068 static int is_refname_available(const char *ref, const char *oldref,
1069                                 struct ref_list *list, int quiet)
1070 {
1071         int namlen = strlen(ref); /* e.g. 'foo/bar' */
1072         while (list) {
1073                 /* list->name could be 'foo' or 'foo/bar/baz' */
1074                 if (!oldref || strcmp(oldref, list->name)) {
1075                         int len = strlen(list->name);
1076                         int cmplen = (namlen < len) ? namlen : len;
1077                         const char *lead = (namlen < len) ? list->name : ref;
1078                         if (!strncmp(ref, list->name, cmplen) &&
1079                             lead[cmplen] == '/') {
1080                                 if (!quiet)
1081                                         error("'%s' exists; cannot create '%s'",
1082                                               list->name, ref);
1083                                 return 0;
1084                         }
1085                 }
1086                 list = list->next;
1087         }
1088         return 1;
1089 }
1090
1091 /*
1092  * *string and *len will only be substituted, and *string returned (for
1093  * later free()ing) if the string passed in is a magic short-hand form
1094  * to name a branch.
1095  */
1096 static char *substitute_branch_name(const char **string, int *len)
1097 {
1098         struct strbuf buf = STRBUF_INIT;
1099         int ret = interpret_branch_name(*string, &buf);
1100
1101         if (ret == *len) {
1102                 size_t size;
1103                 *string = strbuf_detach(&buf, &size);
1104                 *len = size;
1105                 return (char *)*string;
1106         }
1107
1108         return NULL;
1109 }
1110
1111 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
1112 {
1113         char *last_branch = substitute_branch_name(&str, &len);
1114         const char **p, *r;
1115         int refs_found = 0;
1116
1117         *ref = NULL;
1118         for (p = ref_rev_parse_rules; *p; p++) {
1119                 char fullref[PATH_MAX];
1120                 unsigned char sha1_from_ref[20];
1121                 unsigned char *this_result;
1122                 int flag;
1123
1124                 if (p == ref_rev_parse_rules && !refname_ok_at_root_level(str, len))
1125                         continue;
1126                 this_result = refs_found ? sha1_from_ref : sha1;
1127                 mksnpath(fullref, sizeof(fullref), *p, len, str);
1128                 r = resolve_ref(fullref, this_result, 1, &flag);
1129                 if (r) {
1130                         if (!refs_found++)
1131                                 *ref = xstrdup(r);
1132                         if (!warn_ambiguous_refs)
1133                                 break;
1134                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD"))
1135                         warning("ignoring dangling symref %s.", fullref);
1136         }
1137         free(last_branch);
1138         return refs_found;
1139 }
1140
1141 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
1142 {
1143         char *last_branch = substitute_branch_name(&str, &len);
1144         const char **p;
1145         int logs_found = 0;
1146
1147         *log = NULL;
1148         for (p = ref_rev_parse_rules; *p; p++) {
1149                 struct stat st;
1150                 unsigned char hash[20];
1151                 char path[PATH_MAX];
1152                 const char *ref, *it;
1153
1154                 if (p == ref_rev_parse_rules && !refname_ok_at_root_level(str, len))
1155                         continue;
1156                 mksnpath(path, sizeof(path), *p, len, str);
1157                 ref = resolve_ref(path, hash, 1, NULL);
1158                 if (!ref)
1159                         continue;
1160                 if (!stat(git_path("logs/%s", path), &st) &&
1161                     S_ISREG(st.st_mode))
1162                         it = path;
1163                 else if (strcmp(ref, path) &&
1164                          !stat(git_path("logs/%s", ref), &st) &&
1165                          S_ISREG(st.st_mode))
1166                         it = ref;
1167                 else
1168                         continue;
1169                 if (!logs_found++) {
1170                         *log = xstrdup(it);
1171                         hashcpy(sha1, hash);
1172                 }
1173                 if (!warn_ambiguous_refs)
1174                         break;
1175         }
1176         free(last_branch);
1177         return logs_found;
1178 }
1179
1180 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
1181 {
1182         char *ref_file;
1183         const char *orig_ref = ref;
1184         struct ref_lock *lock;
1185         int last_errno = 0;
1186         int type, lflags;
1187         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1188         int missing = 0;
1189
1190         lock = xcalloc(1, sizeof(struct ref_lock));
1191         lock->lock_fd = -1;
1192
1193         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
1194         if (!ref && errno == EISDIR) {
1195                 /* we are trying to lock foo but we used to
1196                  * have foo/bar which now does not exist;
1197                  * it is normal for the empty directory 'foo'
1198                  * to remain.
1199                  */
1200                 ref_file = git_path("%s", orig_ref);
1201                 if (remove_empty_directories(ref_file)) {
1202                         last_errno = errno;
1203                         error("there are still refs under '%s'", orig_ref);
1204                         goto error_return;
1205                 }
1206                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
1207         }
1208         if (type_p)
1209             *type_p = type;
1210         if (!ref) {
1211                 last_errno = errno;
1212                 error("unable to resolve reference %s: %s",
1213                         orig_ref, strerror(errno));
1214                 goto error_return;
1215         }
1216         missing = is_null_sha1(lock->old_sha1);
1217         /* When the ref did not exist and we are creating it,
1218          * make sure there is no existing ref that is packed
1219          * whose name begins with our refname, nor a ref whose
1220          * name is a proper prefix of our refname.
1221          */
1222         if (missing &&
1223              !is_refname_available(ref, NULL, get_packed_refs(NULL), 0)) {
1224                 last_errno = ENOTDIR;
1225                 goto error_return;
1226         }
1227
1228         lock->lk = xcalloc(1, sizeof(struct lock_file));
1229
1230         lflags = LOCK_DIE_ON_ERROR;
1231         if (flags & REF_NODEREF) {
1232                 ref = orig_ref;
1233                 lflags |= LOCK_NODEREF;
1234         }
1235         lock->ref_name = xstrdup(ref);
1236         lock->orig_ref_name = xstrdup(orig_ref);
1237         ref_file = git_path("%s", ref);
1238         if (missing)
1239                 lock->force_write = 1;
1240         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1241                 lock->force_write = 1;
1242
1243         if (safe_create_leading_directories(ref_file)) {
1244                 last_errno = errno;
1245                 error("unable to create directory for %s", ref_file);
1246                 goto error_return;
1247         }
1248
1249         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1250         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1251
1252  error_return:
1253         unlock_ref(lock);
1254         errno = last_errno;
1255         return NULL;
1256 }
1257
1258 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
1259 {
1260         char refpath[PATH_MAX];
1261         if (check_refname_format(ref, 0))
1262                 return NULL;
1263         strcpy(refpath, mkpath("refs/%s", ref));
1264         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1265 }
1266
1267 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
1268 {
1269         if (check_refname_format(ref, REFNAME_ALLOW_ONELEVEL))
1270                 return NULL;
1271         return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
1272 }
1273
1274 static struct lock_file packlock;
1275
1276 static int repack_without_ref(const char *refname)
1277 {
1278         struct ref_list *list, *packed_ref_list;
1279         int fd;
1280         int found = 0;
1281
1282         packed_ref_list = get_packed_refs(NULL);
1283         for (list = packed_ref_list; list; list = list->next) {
1284                 if (!strcmp(refname, list->name)) {
1285                         found = 1;
1286                         break;
1287                 }
1288         }
1289         if (!found)
1290                 return 0;
1291         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1292         if (fd < 0) {
1293                 unable_to_lock_error(git_path("packed-refs"), errno);
1294                 return error("cannot delete '%s' from packed refs", refname);
1295         }
1296
1297         for (list = packed_ref_list; list; list = list->next) {
1298                 char line[PATH_MAX + 100];
1299                 int len;
1300
1301                 if (!strcmp(refname, list->name))
1302                         continue;
1303                 len = snprintf(line, sizeof(line), "%s %s\n",
1304                                sha1_to_hex(list->sha1), list->name);
1305                 /* this should not happen but just being defensive */
1306                 if (len > sizeof(line))
1307                         die("too long a refname '%s'", list->name);
1308                 write_or_die(fd, line, len);
1309         }
1310         return commit_lock_file(&packlock);
1311 }
1312
1313 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1314 {
1315         struct ref_lock *lock;
1316         int err, i = 0, ret = 0, flag = 0;
1317
1318         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1319         if (!lock)
1320                 return 1;
1321         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1322                 /* loose */
1323                 const char *path;
1324
1325                 if (!(delopt & REF_NODEREF)) {
1326                         i = strlen(lock->lk->filename) - 5; /* .lock */
1327                         lock->lk->filename[i] = 0;
1328                         path = lock->lk->filename;
1329                 } else {
1330                         path = git_path("%s", refname);
1331                 }
1332                 err = unlink_or_warn(path);
1333                 if (err && errno != ENOENT)
1334                         ret = 1;
1335
1336                 if (!(delopt & REF_NODEREF))
1337                         lock->lk->filename[i] = '.';
1338         }
1339         /* removing the loose one could have resurrected an earlier
1340          * packed one.  Also, if it was not loose we need to repack
1341          * without it.
1342          */
1343         ret |= repack_without_ref(refname);
1344
1345         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1346         invalidate_cached_refs();
1347         unlock_ref(lock);
1348         return ret;
1349 }
1350
1351 /*
1352  * People using contrib's git-new-workdir have .git/logs/refs ->
1353  * /some/other/path/.git/logs/refs, and that may live on another device.
1354  *
1355  * IOW, to avoid cross device rename errors, the temporary renamed log must
1356  * live into logs/refs.
1357  */
1358 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1359
1360 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1361 {
1362         static const char renamed_ref[] = "RENAMED-REF";
1363         unsigned char sha1[20], orig_sha1[20];
1364         int flag = 0, logmoved = 0;
1365         struct ref_lock *lock;
1366         struct stat loginfo;
1367         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1368         const char *symref = NULL;
1369
1370         if (log && S_ISLNK(loginfo.st_mode))
1371                 return error("reflog for %s is a symlink", oldref);
1372
1373         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1374         if (flag & REF_ISSYMREF)
1375                 return error("refname %s is a symbolic ref, renaming it is not supported",
1376                         oldref);
1377         if (!symref)
1378                 return error("refname %s not found", oldref);
1379
1380         if (!is_refname_available(newref, oldref, get_packed_refs(NULL), 0))
1381                 return 1;
1382
1383         if (!is_refname_available(newref, oldref, get_loose_refs(NULL), 0))
1384                 return 1;
1385
1386         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1387         if (!lock)
1388                 return error("unable to lock %s", renamed_ref);
1389         lock->force_write = 1;
1390         if (write_ref_sha1(lock, orig_sha1, logmsg))
1391                 return error("unable to save current sha1 in %s", renamed_ref);
1392
1393         if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
1394                 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1395                         oldref, strerror(errno));
1396
1397         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1398                 error("unable to delete old %s", oldref);
1399                 goto rollback;
1400         }
1401
1402         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1403                 if (errno==EISDIR) {
1404                         if (remove_empty_directories(git_path("%s", newref))) {
1405                                 error("Directory not empty: %s", newref);
1406                                 goto rollback;
1407                         }
1408                 } else {
1409                         error("unable to delete existing %s", newref);
1410                         goto rollback;
1411                 }
1412         }
1413
1414         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1415                 error("unable to create directory for %s", newref);
1416                 goto rollback;
1417         }
1418
1419  retry:
1420         if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
1421                 if (errno==EISDIR || errno==ENOTDIR) {
1422                         /*
1423                          * rename(a, b) when b is an existing
1424                          * directory ought to result in ISDIR, but
1425                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1426                          */
1427                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1428                                 error("Directory not empty: logs/%s", newref);
1429                                 goto rollback;
1430                         }
1431                         goto retry;
1432                 } else {
1433                         error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1434                                 newref, strerror(errno));
1435                         goto rollback;
1436                 }
1437         }
1438         logmoved = log;
1439
1440         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1441         if (!lock) {
1442                 error("unable to lock %s for update", newref);
1443                 goto rollback;
1444         }
1445         lock->force_write = 1;
1446         hashcpy(lock->old_sha1, orig_sha1);
1447         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1448                 error("unable to write current sha1 into %s", newref);
1449                 goto rollback;
1450         }
1451
1452         return 0;
1453
1454  rollback:
1455         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1456         if (!lock) {
1457                 error("unable to lock %s for rollback", oldref);
1458                 goto rollbacklog;
1459         }
1460
1461         lock->force_write = 1;
1462         flag = log_all_ref_updates;
1463         log_all_ref_updates = 0;
1464         if (write_ref_sha1(lock, orig_sha1, NULL))
1465                 error("unable to write current sha1 into %s", oldref);
1466         log_all_ref_updates = flag;
1467
1468  rollbacklog:
1469         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1470                 error("unable to restore logfile %s from %s: %s",
1471                         oldref, newref, strerror(errno));
1472         if (!logmoved && log &&
1473             rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
1474                 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1475                         oldref, strerror(errno));
1476
1477         return 1;
1478 }
1479
1480 int close_ref(struct ref_lock *lock)
1481 {
1482         if (close_lock_file(lock->lk))
1483                 return -1;
1484         lock->lock_fd = -1;
1485         return 0;
1486 }
1487
1488 int commit_ref(struct ref_lock *lock)
1489 {
1490         if (commit_lock_file(lock->lk))
1491                 return -1;
1492         lock->lock_fd = -1;
1493         return 0;
1494 }
1495
1496 void unlock_ref(struct ref_lock *lock)
1497 {
1498         /* Do not free lock->lk -- atexit() still looks at them */
1499         if (lock->lk)
1500                 rollback_lock_file(lock->lk);
1501         free(lock->ref_name);
1502         free(lock->orig_ref_name);
1503         free(lock);
1504 }
1505
1506 /*
1507  * copy the reflog message msg to buf, which has been allocated sufficiently
1508  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1509  * because reflog file is one line per entry.
1510  */
1511 static int copy_msg(char *buf, const char *msg)
1512 {
1513         char *cp = buf;
1514         char c;
1515         int wasspace = 1;
1516
1517         *cp++ = '\t';
1518         while ((c = *msg++)) {
1519                 if (wasspace && isspace(c))
1520                         continue;
1521                 wasspace = isspace(c);
1522                 if (wasspace)
1523                         c = ' ';
1524                 *cp++ = c;
1525         }
1526         while (buf < cp && isspace(cp[-1]))
1527                 cp--;
1528         *cp++ = '\n';
1529         return cp - buf;
1530 }
1531
1532 int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
1533 {
1534         int logfd, oflags = O_APPEND | O_WRONLY;
1535
1536         git_snpath(logfile, bufsize, "logs/%s", ref_name);
1537         if (log_all_ref_updates &&
1538             (!prefixcmp(ref_name, "refs/heads/") ||
1539              !prefixcmp(ref_name, "refs/remotes/") ||
1540              !prefixcmp(ref_name, "refs/notes/") ||
1541              !strcmp(ref_name, "HEAD"))) {
1542                 if (safe_create_leading_directories(logfile) < 0)
1543                         return error("unable to create directory for %s",
1544                                      logfile);
1545                 oflags |= O_CREAT;
1546         }
1547
1548         logfd = open(logfile, oflags, 0666);
1549         if (logfd < 0) {
1550                 if (!(oflags & O_CREAT) && errno == ENOENT)
1551                         return 0;
1552
1553                 if ((oflags & O_CREAT) && errno == EISDIR) {
1554                         if (remove_empty_directories(logfile)) {
1555                                 return error("There are still logs under '%s'",
1556                                              logfile);
1557                         }
1558                         logfd = open(logfile, oflags, 0666);
1559                 }
1560
1561                 if (logfd < 0)
1562                         return error("Unable to append to %s: %s",
1563                                      logfile, strerror(errno));
1564         }
1565
1566         adjust_shared_perm(logfile);
1567         close(logfd);
1568         return 0;
1569 }
1570
1571 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1572                          const unsigned char *new_sha1, const char *msg)
1573 {
1574         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1575         unsigned maxlen, len;
1576         int msglen;
1577         char log_file[PATH_MAX];
1578         char *logrec;
1579         const char *committer;
1580
1581         if (log_all_ref_updates < 0)
1582                 log_all_ref_updates = !is_bare_repository();
1583
1584         result = log_ref_setup(ref_name, log_file, sizeof(log_file));
1585         if (result)
1586                 return result;
1587
1588         logfd = open(log_file, oflags);
1589         if (logfd < 0)
1590                 return 0;
1591         msglen = msg ? strlen(msg) : 0;
1592         committer = git_committer_info(0);
1593         maxlen = strlen(committer) + msglen + 100;
1594         logrec = xmalloc(maxlen);
1595         len = sprintf(logrec, "%s %s %s\n",
1596                       sha1_to_hex(old_sha1),
1597                       sha1_to_hex(new_sha1),
1598                       committer);
1599         if (msglen)
1600                 len += copy_msg(logrec + len - 1, msg) - 1;
1601         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1602         free(logrec);
1603         if (close(logfd) != 0 || written != len)
1604                 return error("Unable to append to %s", log_file);
1605         return 0;
1606 }
1607
1608 static int is_branch(const char *refname)
1609 {
1610         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1611 }
1612
1613 int write_ref_sha1(struct ref_lock *lock,
1614         const unsigned char *sha1, const char *logmsg)
1615 {
1616         static char term = '\n';
1617         struct object *o;
1618
1619         if (!lock)
1620                 return -1;
1621         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1622                 unlock_ref(lock);
1623                 return 0;
1624         }
1625         o = parse_object(sha1);
1626         if (!o) {
1627                 error("Trying to write ref %s with nonexistent object %s",
1628                         lock->ref_name, sha1_to_hex(sha1));
1629                 unlock_ref(lock);
1630                 return -1;
1631         }
1632         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1633                 error("Trying to write non-commit object %s to branch %s",
1634                         sha1_to_hex(sha1), lock->ref_name);
1635                 unlock_ref(lock);
1636                 return -1;
1637         }
1638         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1639             write_in_full(lock->lock_fd, &term, 1) != 1
1640                 || close_ref(lock) < 0) {
1641                 error("Couldn't write %s", lock->lk->filename);
1642                 unlock_ref(lock);
1643                 return -1;
1644         }
1645         invalidate_cached_refs();
1646         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1647             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1648              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1649                 unlock_ref(lock);
1650                 return -1;
1651         }
1652         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1653                 /*
1654                  * Special hack: If a branch is updated directly and HEAD
1655                  * points to it (may happen on the remote side of a push
1656                  * for example) then logically the HEAD reflog should be
1657                  * updated too.
1658                  * A generic solution implies reverse symref information,
1659                  * but finding all symrefs pointing to the given branch
1660                  * would be rather costly for this rare event (the direct
1661                  * update of a branch) to be worth it.  So let's cheat and
1662                  * check with HEAD only which should cover 99% of all usage
1663                  * scenarios (even 100% of the default ones).
1664                  */
1665                 unsigned char head_sha1[20];
1666                 int head_flag;
1667                 const char *head_ref;
1668                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1669                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1670                     !strcmp(head_ref, lock->ref_name))
1671                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1672         }
1673         if (commit_ref(lock)) {
1674                 error("Couldn't set %s", lock->ref_name);
1675                 unlock_ref(lock);
1676                 return -1;
1677         }
1678         unlock_ref(lock);
1679         return 0;
1680 }
1681
1682 int create_symref(const char *ref_target, const char *refs_heads_master,
1683                   const char *logmsg)
1684 {
1685         const char *lockpath;
1686         char ref[1000];
1687         int fd, len, written;
1688         char *git_HEAD = git_pathdup("%s", ref_target);
1689         unsigned char old_sha1[20], new_sha1[20];
1690
1691         if (logmsg && read_ref(ref_target, old_sha1))
1692                 hashclr(old_sha1);
1693
1694         if (safe_create_leading_directories(git_HEAD) < 0)
1695                 return error("unable to create directory for %s", git_HEAD);
1696
1697 #ifndef NO_SYMLINK_HEAD
1698         if (prefer_symlink_refs) {
1699                 unlink(git_HEAD);
1700                 if (!symlink(refs_heads_master, git_HEAD))
1701                         goto done;
1702                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1703         }
1704 #endif
1705
1706         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1707         if (sizeof(ref) <= len) {
1708                 error("refname too long: %s", refs_heads_master);
1709                 goto error_free_return;
1710         }
1711         lockpath = mkpath("%s.lock", git_HEAD);
1712         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1713         if (fd < 0) {
1714                 error("Unable to open %s for writing", lockpath);
1715                 goto error_free_return;
1716         }
1717         written = write_in_full(fd, ref, len);
1718         if (close(fd) != 0 || written != len) {
1719                 error("Unable to write to %s", lockpath);
1720                 goto error_unlink_return;
1721         }
1722         if (rename(lockpath, git_HEAD) < 0) {
1723                 error("Unable to create %s", git_HEAD);
1724                 goto error_unlink_return;
1725         }
1726         if (adjust_shared_perm(git_HEAD)) {
1727                 error("Unable to fix permissions on %s", lockpath);
1728         error_unlink_return:
1729                 unlink_or_warn(lockpath);
1730         error_free_return:
1731                 free(git_HEAD);
1732                 return -1;
1733         }
1734
1735 #ifndef NO_SYMLINK_HEAD
1736         done:
1737 #endif
1738         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1739                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1740
1741         free(git_HEAD);
1742         return 0;
1743 }
1744
1745 static char *ref_msg(const char *line, const char *endp)
1746 {
1747         const char *ep;
1748         line += 82;
1749         ep = memchr(line, '\n', endp - line);
1750         if (!ep)
1751                 ep = endp;
1752         return xmemdupz(line, ep - line);
1753 }
1754
1755 int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1, char **msg, unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
1756 {
1757         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1758         char *tz_c;
1759         int logfd, tz, reccnt = 0;
1760         struct stat st;
1761         unsigned long date;
1762         unsigned char logged_sha1[20];
1763         void *log_mapped;
1764         size_t mapsz;
1765
1766         logfile = git_path("logs/%s", ref);
1767         logfd = open(logfile, O_RDONLY, 0);
1768         if (logfd < 0)
1769                 die_errno("Unable to read log '%s'", logfile);
1770         fstat(logfd, &st);
1771         if (!st.st_size)
1772                 die("Log %s is empty.", logfile);
1773         mapsz = xsize_t(st.st_size);
1774         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1775         logdata = log_mapped;
1776         close(logfd);
1777
1778         lastrec = NULL;
1779         rec = logend = logdata + st.st_size;
1780         while (logdata < rec) {
1781                 reccnt++;
1782                 if (logdata < rec && *(rec-1) == '\n')
1783                         rec--;
1784                 lastgt = NULL;
1785                 while (logdata < rec && *(rec-1) != '\n') {
1786                         rec--;
1787                         if (*rec == '>')
1788                                 lastgt = rec;
1789                 }
1790                 if (!lastgt)
1791                         die("Log %s is corrupt.", logfile);
1792                 date = strtoul(lastgt + 1, &tz_c, 10);
1793                 if (date <= at_time || cnt == 0) {
1794                         tz = strtoul(tz_c, NULL, 10);
1795                         if (msg)
1796                                 *msg = ref_msg(rec, logend);
1797                         if (cutoff_time)
1798                                 *cutoff_time = date;
1799                         if (cutoff_tz)
1800                                 *cutoff_tz = tz;
1801                         if (cutoff_cnt)
1802                                 *cutoff_cnt = reccnt - 1;
1803                         if (lastrec) {
1804                                 if (get_sha1_hex(lastrec, logged_sha1))
1805                                         die("Log %s is corrupt.", logfile);
1806                                 if (get_sha1_hex(rec + 41, sha1))
1807                                         die("Log %s is corrupt.", logfile);
1808                                 if (hashcmp(logged_sha1, sha1)) {
1809                                         warning("Log %s has gap after %s.",
1810                                                 logfile, show_date(date, tz, DATE_RFC2822));
1811                                 }
1812                         }
1813                         else if (date == at_time) {
1814                                 if (get_sha1_hex(rec + 41, sha1))
1815                                         die("Log %s is corrupt.", logfile);
1816                         }
1817                         else {
1818                                 if (get_sha1_hex(rec + 41, logged_sha1))
1819                                         die("Log %s is corrupt.", logfile);
1820                                 if (hashcmp(logged_sha1, sha1)) {
1821                                         warning("Log %s unexpectedly ended on %s.",
1822                                                 logfile, show_date(date, tz, DATE_RFC2822));
1823                                 }
1824                         }
1825                         munmap(log_mapped, mapsz);
1826                         return 0;
1827                 }
1828                 lastrec = rec;
1829                 if (cnt > 0)
1830                         cnt--;
1831         }
1832
1833         rec = logdata;
1834         while (rec < logend && *rec != '>' && *rec != '\n')
1835                 rec++;
1836         if (rec == logend || *rec == '\n')
1837                 die("Log %s is corrupt.", logfile);
1838         date = strtoul(rec + 1, &tz_c, 10);
1839         tz = strtoul(tz_c, NULL, 10);
1840         if (get_sha1_hex(logdata, sha1))
1841                 die("Log %s is corrupt.", logfile);
1842         if (is_null_sha1(sha1)) {
1843                 if (get_sha1_hex(logdata + 41, sha1))
1844                         die("Log %s is corrupt.", logfile);
1845         }
1846         if (msg)
1847                 *msg = ref_msg(logdata, logend);
1848         munmap(log_mapped, mapsz);
1849
1850         if (cutoff_time)
1851                 *cutoff_time = date;
1852         if (cutoff_tz)
1853                 *cutoff_tz = tz;
1854         if (cutoff_cnt)
1855                 *cutoff_cnt = reccnt;
1856         return 1;
1857 }
1858
1859 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1860 {
1861         const char *logfile;
1862         FILE *logfp;
1863         struct strbuf sb = STRBUF_INIT;
1864         int ret = 0;
1865
1866         logfile = git_path("logs/%s", ref);
1867         logfp = fopen(logfile, "r");
1868         if (!logfp)
1869                 return -1;
1870
1871         if (ofs) {
1872                 struct stat statbuf;
1873                 if (fstat(fileno(logfp), &statbuf) ||
1874                     statbuf.st_size < ofs ||
1875                     fseek(logfp, -ofs, SEEK_END) ||
1876                     strbuf_getwholeline(&sb, logfp, '\n')) {
1877                         fclose(logfp);
1878                         strbuf_release(&sb);
1879                         return -1;
1880                 }
1881         }
1882
1883         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1884                 unsigned char osha1[20], nsha1[20];
1885                 char *email_end, *message;
1886                 unsigned long timestamp;
1887                 int tz;
1888
1889                 /* old SP new SP name <email> SP time TAB msg LF */
1890                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1891                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1892                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1893                     !(email_end = strchr(sb.buf + 82, '>')) ||
1894                     email_end[1] != ' ' ||
1895                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1896                     !message || message[0] != ' ' ||
1897                     (message[1] != '+' && message[1] != '-') ||
1898                     !isdigit(message[2]) || !isdigit(message[3]) ||
1899                     !isdigit(message[4]) || !isdigit(message[5]))
1900                         continue; /* corrupt? */
1901                 email_end[1] = '\0';
1902                 tz = strtol(message + 1, NULL, 10);
1903                 if (message[6] != '\t')
1904                         message += 6;
1905                 else
1906                         message += 7;
1907                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1908                          cb_data);
1909                 if (ret)
1910                         break;
1911         }
1912         fclose(logfp);
1913         strbuf_release(&sb);
1914         return ret;
1915 }
1916
1917 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1918 {
1919         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1920 }
1921
1922 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1923 {
1924         DIR *dir = opendir(git_path("logs/%s", base));
1925         int retval = 0;
1926
1927         if (dir) {
1928                 struct dirent *de;
1929                 int baselen = strlen(base);
1930                 char *log = xmalloc(baselen + 257);
1931
1932                 memcpy(log, base, baselen);
1933                 if (baselen && base[baselen-1] != '/')
1934                         log[baselen++] = '/';
1935
1936                 while ((de = readdir(dir)) != NULL) {
1937                         struct stat st;
1938                         int namelen;
1939
1940                         if (de->d_name[0] == '.')
1941                                 continue;
1942                         namelen = strlen(de->d_name);
1943                         if (namelen > 255)
1944                                 continue;
1945                         if (has_extension(de->d_name, ".lock"))
1946                                 continue;
1947                         memcpy(log + baselen, de->d_name, namelen+1);
1948                         if (stat(git_path("logs/%s", log), &st) < 0)
1949                                 continue;
1950                         if (S_ISDIR(st.st_mode)) {
1951                                 retval = do_for_each_reflog(log, fn, cb_data);
1952                         } else {
1953                                 unsigned char sha1[20];
1954                                 if (!resolve_ref(log, sha1, 0, NULL))
1955                                         retval = error("bad ref for %s", log);
1956                                 else
1957                                         retval = fn(log, sha1, 0, cb_data);
1958                         }
1959                         if (retval)
1960                                 break;
1961                 }
1962                 free(log);
1963                 closedir(dir);
1964         }
1965         else if (*base)
1966                 return errno;
1967         return retval;
1968 }
1969
1970 int for_each_reflog(each_ref_fn fn, void *cb_data)
1971 {
1972         return do_for_each_reflog("", fn, cb_data);
1973 }
1974
1975 int update_ref(const char *action, const char *refname,
1976                 const unsigned char *sha1, const unsigned char *oldval,
1977                 int flags, enum action_on_err onerr)
1978 {
1979         static struct ref_lock *lock;
1980         lock = lock_any_ref_for_update(refname, oldval, flags);
1981         if (!lock) {
1982                 const char *str = "Cannot lock the ref '%s'.";
1983                 switch (onerr) {
1984                 case MSG_ON_ERR: error(str, refname); break;
1985                 case DIE_ON_ERR: die(str, refname); break;
1986                 case QUIET_ON_ERR: break;
1987                 }
1988                 return 1;
1989         }
1990         if (write_ref_sha1(lock, sha1, action) < 0) {
1991                 const char *str = "Cannot update the ref '%s'.";
1992                 switch (onerr) {
1993                 case MSG_ON_ERR: error(str, refname); break;
1994                 case DIE_ON_ERR: die(str, refname); break;
1995                 case QUIET_ON_ERR: break;
1996                 }
1997                 return 1;
1998         }
1999         return 0;
2000 }
2001
2002 int ref_exists(char *refname)
2003 {
2004         unsigned char sha1[20];
2005         return !!resolve_ref(refname, sha1, 1, NULL);
2006 }
2007
2008 struct ref *find_ref_by_name(const struct ref *list, const char *name)
2009 {
2010         for ( ; list; list = list->next)
2011                 if (!strcmp(list->name, name))
2012                         return (struct ref *)list;
2013         return NULL;
2014 }
2015
2016 /*
2017  * generate a format suitable for scanf from a ref_rev_parse_rules
2018  * rule, that is replace the "%.*s" spec with a "%s" spec
2019  */
2020 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
2021 {
2022         char *spec;
2023
2024         spec = strstr(rule, "%.*s");
2025         if (!spec || strstr(spec + 4, "%.*s"))
2026                 die("invalid rule in ref_rev_parse_rules: %s", rule);
2027
2028         /* copy all until spec */
2029         strncpy(scanf_fmt, rule, spec - rule);
2030         scanf_fmt[spec - rule] = '\0';
2031         /* copy new spec */
2032         strcat(scanf_fmt, "%s");
2033         /* copy remaining rule */
2034         strcat(scanf_fmt, spec + 4);
2035
2036         return;
2037 }
2038
2039 char *shorten_unambiguous_ref(const char *ref, int strict)
2040 {
2041         int i;
2042         static char **scanf_fmts;
2043         static int nr_rules;
2044         char *short_name;
2045
2046         /* pre generate scanf formats from ref_rev_parse_rules[] */
2047         if (!nr_rules) {
2048                 size_t total_len = 0;
2049
2050                 /* the rule list is NULL terminated, count them first */
2051                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
2052                         /* no +1 because strlen("%s") < strlen("%.*s") */
2053                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
2054
2055                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
2056
2057                 total_len = 0;
2058                 for (i = 0; i < nr_rules; i++) {
2059                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
2060                                         + total_len;
2061                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
2062                         total_len += strlen(ref_rev_parse_rules[i]);
2063                 }
2064         }
2065
2066         /* bail out if there are no rules */
2067         if (!nr_rules)
2068                 return xstrdup(ref);
2069
2070         /* buffer for scanf result, at most ref must fit */
2071         short_name = xstrdup(ref);
2072
2073         for (i = nr_rules - 1; i >= 0; i--) {
2074                 int j;
2075                 int rules_to_fail = i;
2076                 int short_name_len;
2077
2078                 if (!i && !refname_ok_at_root_level(ref, strlen(ref)))
2079                         continue;
2080
2081                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
2082                         continue;
2083
2084                 short_name_len = strlen(short_name);
2085
2086                 /*
2087                  * in strict mode, all (except the matched one) rules
2088                  * must fail to resolve to a valid non-ambiguous ref
2089                  */
2090                 if (strict)
2091                         rules_to_fail = nr_rules;
2092
2093                 /*
2094                  * check if the short name resolves to a valid ref,
2095                  * but use only rules prior to the matched one
2096                  */
2097                 for (j = 0; j < rules_to_fail; j++) {
2098                         const char *rule = ref_rev_parse_rules[j];
2099                         unsigned char short_objectname[20];
2100                         char refname[PATH_MAX];
2101
2102                         /* skip matched rule */
2103                         if (i == j)
2104                                 continue;
2105
2106                         if (!j &&
2107                             !refname_ok_at_root_level(short_name, short_name_len))
2108                                 continue;
2109
2110                         /*
2111                          * the short name is ambiguous, if it resolves
2112                          * (with this previous rule) to a valid ref
2113                          * read_ref() returns 0 on success
2114                          */
2115                         mksnpath(refname, sizeof(refname),
2116                                  rule, short_name_len, short_name);
2117                         if (!read_ref(refname, short_objectname))
2118                                 break;
2119                 }
2120
2121                 /*
2122                  * short name is non-ambiguous if all previous rules
2123                  * haven't resolved to a valid ref
2124                  */
2125                 if (j == rules_to_fail)
2126                         return short_name;
2127         }
2128
2129         free(short_name);
2130         return xstrdup(ref);
2131 }