git.oblomov.eu Git - git/blob - 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
  10 struct ref_list {
  11         struct ref_list *next;
  12         unsigned char flag; /* ISSYMREF? ISPACKED? */
  13         unsigned char sha1[20];
  14         unsigned char peeled[20];
  15         char name[FLEX_ARRAY];
  16 };
  17
  18 static const char *parse_ref_line(char *line, unsigned char *sha1)
  19 {
  20         /*
  21          * 42: the answer to everything.
  22          *
  23          * In this case, it happens to be the answer to
  24          *  40 (length of sha1 hex representation)
  25          *  +1 (space in between hex and name)
  26          *  +1 (newline at the end of the line)
  27          */
  28         int len = strlen(line) - 42;
  29
  30         if (len <= 0)
  31                 return NULL;
  32         if (get_sha1_hex(line, sha1) < 0)
  33                 return NULL;
  34         if (!isspace(line[40]))
  35                 return NULL;
  36         line += 41;
  37         if (isspace(*line))
  38                 return NULL;
  39         if (line[len] != '\n')
  40                 return NULL;
  41         line[len] = 0;
  42
  43         return line;
  44 }
  45
  46 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  47                                 int flag, struct ref_list *list,
  48                                 struct ref_list **new_entry)
  49 {
  50         int len;
  51         struct ref_list *entry;
  52
  53         /* Allocate it and add it in.. */
  54         len = strlen(name) + 1;
  55         entry = xmalloc(sizeof(struct ref_list) + len);
  56         hashcpy(entry->sha1, sha1);
  57         hashclr(entry->peeled);
  58         memcpy(entry->name, name, len);
  59         entry->flag = flag;
  60         entry->next = list;
  61         if (new_entry)
  62                 *new_entry = entry;
  63         return entry;
  64 }
  65
  66 /* merge sort the ref list */
  67 static struct ref_list *sort_ref_list(struct ref_list *list)
  68 {
  69         int psize, qsize, last_merge_count, cmp;
  70         struct ref_list *p, *q, *l, *e;
  71         struct ref_list *new_list = list;
  72         int k = 1;
  73         int merge_count = 0;
  74
  75         if (!list)
  76                 return list;
  77
  78         do {
  79                 last_merge_count = merge_count;
  80                 merge_count = 0;
  81
  82                 psize = 0;
  83
  84                 p = new_list;
  85                 q = new_list;
  86                 new_list = NULL;
  87                 l = NULL;
  88
  89                 while (p) {
  90                         merge_count++;
  91
  92                         while (psize < k && q->next) {
  93                                 q = q->next;
  94                                 psize++;
  95                         }
  96                         qsize = k;
  97
  98                         while ((psize > 0) || (qsize > 0 && q)) {
  99                                 if (qsize == 0 || !q) {
 100                                         e = p;
 101                                         p = p->next;
 102                                         psize--;
 103                                 } else if (psize == 0) {
 104                                         e = q;
 105                                         q = q->next;
 106                                         qsize--;
 107                                 } else {
 108                                         cmp = strcmp(q->name, p->name);
 109                                         if (cmp < 0) {
 110                                                 e = q;
 111                                                 q = q->next;
 112                                                 qsize--;
 113                                         } else if (cmp > 0) {
 114                                                 e = p;
 115                                                 p = p->next;
 116                                                 psize--;
 117                                         } else {
 118                                                 if (hashcmp(q->sha1, p->sha1))
 119                                                         die("Duplicated ref, and SHA1s don't match: %s",
 120                                                             q->name);
 121                                                 warning("Duplicated ref: %s", q->name);
 122                                                 e = q;
 123                                                 q = q->next;
 124                                                 qsize--;
 125                                                 free(e);
 126                                                 e = p;
 127                                                 p = p->next;
 128                                                 psize--;
 129                                         }
 130                                 }
 131
 132                                 e->next = NULL;
 133
 134                                 if (l)
 135                                         l->next = e;
 136                                 if (!new_list)
 137                                         new_list = e;
 138                                 l = e;
 139                         }
 140
 141                         p = q;
 142                 };
 143
 144                 k = k * 2;
 145         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
 146
 147         return new_list;
 148 }
 149
 150 /*
 151  * Future: need to be in "struct repository"
 152  * when doing a full libification.
 153  */
 154 static struct cached_refs {
 155         char did_loose;
 156         char did_packed;
 157         struct ref_list *loose;
 158         struct ref_list *packed;
 159 } cached_refs;
 160
 161 static void free_ref_list(struct ref_list *list)
 162 {
 163         struct ref_list *next;
 164         for ( ; list; list = next) {
 165                 next = list->next;
 166                 free(list);
 167         }
 168 }
 169
 170 static void invalidate_cached_refs(void)
 171 {
 172         struct cached_refs *ca = &cached_refs;
 173
 174         if (ca->did_loose && ca->loose)
 175                 free_ref_list(ca->loose);
 176         if (ca->did_packed && ca->packed)
 177                 free_ref_list(ca->packed);
 178         ca->loose = ca->packed = NULL;
 179         ca->did_loose = ca->did_packed = 0;
 180 }
 181
 182 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 183 {
 184         struct ref_list *list = NULL;
 185         struct ref_list *last = NULL;
 186         char refline[PATH_MAX];
 187         int flag = REF_ISPACKED;
 188
 189         while (fgets(refline, sizeof(refline), f)) {
 190                 unsigned char sha1[20];
 191                 const char *name;
 192                 static const char header[] = "# pack-refs with:";
 193
 194                 if (!strncmp(refline, header, sizeof(header)-1)) {
 195                         const char *traits = refline + sizeof(header) - 1;
 196                         if (strstr(traits, " peeled "))
 197                                 flag |= REF_KNOWS_PEELED;
 198                         /* perhaps other traits later as well */
 199                         continue;
 200                 }
 201
 202                 name = parse_ref_line(refline, sha1);
 203                 if (name) {
 204                         list = add_ref(name, sha1, flag, list, &last);
 205                         continue;
 206                 }
 207                 if (last &&
 208                     refline[0] == '^' &&
 209                     strlen(refline) == 42 &&
 210                     refline[41] == '\n' &&
 211                     !get_sha1_hex(refline + 1, sha1))
 212                         hashcpy(last->peeled, sha1);
 213         }
 214         cached_refs->packed = sort_ref_list(list);
 215 }
 216
 217 static struct ref_list *get_packed_refs(void)
 218 {
 219         if (!cached_refs.did_packed) {
 220                 FILE *f = fopen(git_path("packed-refs"), "r");
 221                 cached_refs.packed = NULL;
 222                 if (f) {
 223                         read_packed_refs(f, &cached_refs);
 224                         fclose(f);
 225                 }
 226                 cached_refs.did_packed = 1;
 227         }
 228         return cached_refs.packed;
 229 }
 230
 231 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 232 {
 233         DIR *dir = opendir(git_path("%s", base));
 234
 235         if (dir) {
 236                 struct dirent *de;
 237                 int baselen = strlen(base);
 238                 char *ref = xmalloc(baselen + 257);
 239
 240                 memcpy(ref, base, baselen);
 241                 if (baselen && base[baselen-1] != '/')
 242                         ref[baselen++] = '/';
 243
 244                 while ((de = readdir(dir)) != NULL) {
 245                         unsigned char sha1[20];
 246                         struct stat st;
 247                         int flag;
 248                         int namelen;
 249
 250                         if (de->d_name[0] == '.')
 251                                 continue;
 252                         namelen = strlen(de->d_name);
 253                         if (namelen > 255)
 254                                 continue;
 255                         if (has_extension(de->d_name, ".lock"))
 256                                 continue;
 257                         memcpy(ref + baselen, de->d_name, namelen+1);
 258                         if (stat(git_path("%s", ref), &st) < 0)
 259                                 continue;
 260                         if (S_ISDIR(st.st_mode)) {
 261                                 list = get_ref_dir(ref, list);
 262                                 continue;
 263                         }
 264                         if (!resolve_ref(ref, sha1, 1, &flag)) {
 265                                 error("%s points nowhere!", ref);
 266                                 continue;
 267                         }
 268                         list = add_ref(ref, sha1, flag, list, NULL);
 269                 }
 270                 free(ref);
 271                 closedir(dir);
 272         }
 273         return sort_ref_list(list);
 274 }
 275
 276 static struct ref_list *get_loose_refs(void)
 277 {
 278         if (!cached_refs.did_loose) {
 279                 cached_refs.loose = get_ref_dir("refs", NULL);
 280                 cached_refs.did_loose = 1;
 281         }
 282         return cached_refs.loose;
 283 }
 284
 285 /* We allow "recursive" symbolic refs. Only within reason, though */
 286 #define MAXDEPTH 5
 287 #define MAXREFLEN (1024)
 288
 289 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 290 {
 291         FILE *f;
 292         struct cached_refs refs;
 293         struct ref_list *ref;
 294         int retval;
 295
 296         strcpy(name + pathlen, "packed-refs");
 297         f = fopen(name, "r");
 298         if (!f)
 299                 return -1;
 300         read_packed_refs(f, &refs);
 301         fclose(f);
 302         ref = refs.packed;
 303         retval = -1;
 304         while (ref) {
 305                 if (!strcmp(ref->name, refname)) {
 306                         retval = 0;
 307                         memcpy(result, ref->sha1, 20);
 308                         break;
 309                 }
 310                 ref = ref->next;
 311         }
 312         free_ref_list(refs.packed);
 313         return retval;
 314 }
 315
 316 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 317 {
 318         int fd, len = strlen(refname);
 319         char buffer[128], *p;
 320
 321         if (recursion > MAXDEPTH || len > MAXREFLEN)
 322                 return -1;
 323         memcpy(name + pathlen, refname, len+1);
 324         fd = open(name, O_RDONLY);
 325         if (fd < 0)
 326                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 327
 328         len = read(fd, buffer, sizeof(buffer)-1);
 329         close(fd);
 330         if (len < 0)
 331                 return -1;
 332         while (len && isspace(buffer[len-1]))
 333                 len--;
 334         buffer[len] = 0;
 335
 336         /* Was it a detached head or an old-fashioned symlink? */
 337         if (!get_sha1_hex(buffer, result))
 338                 return 0;
 339
 340         /* Symref? */
 341         if (strncmp(buffer, "ref:", 4))
 342                 return -1;
 343         p = buffer + 4;
 344         while (isspace(*p))
 345                 p++;
 346
 347         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 348 }
 349
 350 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 351 {
 352         int len = strlen(path), retval;
 353         char *gitdir;
 354
 355         while (len && path[len-1] == '/')
 356                 len--;
 357         if (!len)
 358                 return -1;
 359         gitdir = xmalloc(len + MAXREFLEN + 8);
 360         memcpy(gitdir, path, len);
 361         memcpy(gitdir + len, "/.git/", 7);
 362
 363         retval = resolve_gitlink_ref_recursive(gitdir, len+6, refname, result, 0);
 364         free(gitdir);
 365         return retval;
 366 }
 367
 368 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 369 {
 370         int depth = MAXDEPTH, len;
 371         char buffer[256];
 372         static char ref_buffer[256];
 373
 374         if (flag)
 375                 *flag = 0;
 376
 377         for (;;) {
 378                 const char *path = git_path("%s", ref);
 379                 struct stat st;
 380                 char *buf;
 381                 int fd;
 382
 383                 if (--depth < 0)
 384                         return NULL;
 385
 386                 /* Special case: non-existing file.
 387                  * Not having the refs/heads/new-branch is OK
 388                  * if we are writing into it, so is .git/HEAD
 389                  * that points at refs/heads/master still to be
 390                  * born.  It is NOT OK if we are resolving for
 391                  * reading.
 392                  */
 393                 if (lstat(path, &st) < 0) {
 394                         struct ref_list *list = get_packed_refs();
 395                         while (list) {
 396                                 if (!strcmp(ref, list->name)) {
 397                                         hashcpy(sha1, list->sha1);
 398                                         if (flag)
 399                                                 *flag |= REF_ISPACKED;
 400                                         return ref;
 401                                 }
 402                                 list = list->next;
 403                         }
 404                         if (reading || errno != ENOENT)
 405                                 return NULL;
 406                         hashclr(sha1);
 407                         return ref;
 408                 }
 409
 410                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 411                 if (S_ISLNK(st.st_mode)) {
 412                         len = readlink(path, buffer, sizeof(buffer)-1);
 413                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 414                                 buffer[len] = 0;
 415                                 strcpy(ref_buffer, buffer);
 416                                 ref = ref_buffer;
 417                                 if (flag)
 418                                         *flag |= REF_ISSYMREF;
 419                                 continue;
 420                         }
 421                 }
 422
 423                 /* Is it a directory? */
 424                 if (S_ISDIR(st.st_mode)) {
 425                         errno = EISDIR;
 426                         return NULL;
 427                 }
 428
 429                 /*
 430                  * Anything else, just open it and try to use it as
 431                  * a ref
 432                  */
 433                 fd = open(path, O_RDONLY);
 434                 if (fd < 0)
 435                         return NULL;
 436                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 437                 close(fd);
 438
 439                 /*
 440                  * Is it a symbolic ref?
 441                  */
 442                 if (len < 4 || memcmp("ref:", buffer, 4))
 443                         break;
 444                 buf = buffer + 4;
 445                 len -= 4;
 446                 while (len && isspace(*buf))
 447                         buf++, len--;
 448                 while (len && isspace(buf[len-1]))
 449                         len--;
 450                 buf[len] = 0;
 451                 memcpy(ref_buffer, buf, len + 1);
 452                 ref = ref_buffer;
 453                 if (flag)
 454                         *flag |= REF_ISSYMREF;
 455         }
 456         if (len < 40 || get_sha1_hex(buffer, sha1))
 457                 return NULL;
 458         return ref;
 459 }
 460
 461 int read_ref(const char *ref, unsigned char *sha1)
 462 {
 463         if (resolve_ref(ref, sha1, 1, NULL))
 464                 return 0;
 465         return -1;
 466 }
 467
 468 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 469                       void *cb_data, struct ref_list *entry)
 470 {
 471         if (strncmp(base, entry->name, trim))
 472                 return 0;
 473         if (is_null_sha1(entry->sha1))
 474                 return 0;
 475         if (!has_sha1_file(entry->sha1)) {
 476                 error("%s does not point to a valid object!", entry->name);
 477                 return 0;
 478         }
 479         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 480 }
 481
 482 int peel_ref(const char *ref, unsigned char *sha1)
 483 {
 484         int flag;
 485         unsigned char base[20];
 486         struct object *o;
 487
 488         if (!resolve_ref(ref, base, 1, &flag))
 489                 return -1;
 490
 491         if ((flag & REF_ISPACKED)) {
 492                 struct ref_list *list = get_packed_refs();
 493
 494                 while (list) {
 495                         if (!strcmp(list->name, ref)) {
 496                                 if (list->flag & REF_KNOWS_PEELED) {
 497                                         hashcpy(sha1, list->peeled);
 498                                         return 0;
 499                                 }
 500                                 /* older pack-refs did not leave peeled ones */
 501                                 break;
 502                         }
 503                         list = list->next;
 504                 }
 505         }
 506
 507         /* fallback - callers should not call this for unpacked refs */
 508         o = parse_object(base);
 509         if (o->type == OBJ_TAG) {
 510                 o = deref_tag(o, ref, 0);
 511                 if (o) {
 512                         hashcpy(sha1, o->sha1);
 513                         return 0;
 514                 }
 515         }
 516         return -1;
 517 }
 518
 519 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 520                            void *cb_data)
 521 {
 522         int retval;
 523         struct ref_list *packed = get_packed_refs();
 524         struct ref_list *loose = get_loose_refs();
 525
 526         while (packed && loose) {
 527                 struct ref_list *entry;
 528                 int cmp = strcmp(packed->name, loose->name);
 529                 if (!cmp) {
 530                         packed = packed->next;
 531                         continue;
 532                 }
 533                 if (cmp > 0) {
 534                         entry = loose;
 535                         loose = loose->next;
 536                 } else {
 537                         entry = packed;
 538                         packed = packed->next;
 539                 }
 540                 retval = do_one_ref(base, fn, trim, cb_data, entry);
 541                 if (retval)
 542                         return retval;
 543         }
 544
 545         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 546                 retval = do_one_ref(base, fn, trim, cb_data, packed);
 547                 if (retval)
 548                         return retval;
 549         }
 550         return 0;
 551 }
 552
 553 int head_ref(each_ref_fn fn, void *cb_data)
 554 {
 555         unsigned char sha1[20];
 556         int flag;
 557
 558         if (resolve_ref("HEAD", sha1, 1, &flag))
 559                 return fn("HEAD", sha1, flag, cb_data);
 560         return 0;
 561 }
 562
 563 int for_each_ref(each_ref_fn fn, void *cb_data)
 564 {
 565         return do_for_each_ref("refs/", fn, 0, cb_data);
 566 }
 567
 568 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 569 {
 570         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 571 }
 572
 573 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 574 {
 575         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 576 }
 577
 578 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 579 {
 580         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 581 }
 582
 583 /*
 584  * Make sure "ref" is something reasonable to have under ".git/refs/";
 585  * We do not like it if:
 586  *
 587  * - any path component of it begins with ".", or
 588  * - it has double dots "..", or
 589  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 590  * - it ends with a "/".
 591  */
 592
 593 static inline int bad_ref_char(int ch)
 594 {
 595         if (((unsigned) ch) <= ' ' ||
 596             ch == '~' || ch == '^' || ch == ':')
 597                 return 1;
 598         /* 2.13 Pattern Matching Notation */
 599         if (ch == '?' || ch == '[') /* Unsupported */
 600                 return 1;
 601         if (ch == '*') /* Supported at the end */
 602                 return 2;
 603         return 0;
 604 }
 605
 606 int check_ref_format(const char *ref)
 607 {
 608         int ch, level, bad_type;
 609         const char *cp = ref;
 610
 611         level = 0;
 612         while (1) {
 613                 while ((ch = *cp++) == '/')
 614                         ; /* tolerate duplicated slashes */
 615                 if (!ch)
 616                         return -1; /* should not end with slashes */
 617
 618                 /* we are at the beginning of the path component */
 619                 if (ch == '.')
 620                         return -1;
 621                 bad_type = bad_ref_char(ch);
 622                 if (bad_type) {
 623                         return (bad_type == 2 && !*cp) ? -3 : -1;
 624                 }
 625
 626                 /* scan the rest of the path component */
 627                 while ((ch = *cp++) != 0) {
 628                         bad_type = bad_ref_char(ch);
 629                         if (bad_type) {
 630                                 return (bad_type == 2 && !*cp) ? -3 : -1;
 631                         }
 632                         if (ch == '/')
 633                                 break;
 634                         if (ch == '.' && *cp == '.')
 635                                 return -1;
 636                 }
 637                 level++;
 638                 if (!ch) {
 639                         if (level < 2)
 640                                 return -2; /* at least of form "heads/blah" */
 641                         return 0;
 642                 }
 643         }
 644 }
 645
 646 static struct ref_lock *verify_lock(struct ref_lock *lock,
 647         const unsigned char *old_sha1, int mustexist)
 648 {
 649         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 650                 error("Can't verify ref %s", lock->ref_name);
 651                 unlock_ref(lock);
 652                 return NULL;
 653         }
 654         if (hashcmp(lock->old_sha1, old_sha1)) {
 655                 error("Ref %s is at %s but expected %s", lock->ref_name,
 656                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 657                 unlock_ref(lock);
 658                 return NULL;
 659         }
 660         return lock;
 661 }
 662
 663 static int remove_empty_directories(const char *file)
 664 {
 665         /* we want to create a file but there is a directory there;
 666          * if that is an empty directory (or a directory that contains
 667          * only empty directories), remove them.
 668          */
 669         struct strbuf path;
 670         int result;
 671
 672         strbuf_init(&path, 20);
 673         strbuf_addstr(&path, file);
 674
 675         result = remove_dir_recursively(&path, 1);
 676
 677         strbuf_release(&path);
 678
 679         return result;
 680 }
 681
 682 static int is_refname_available(const char *ref, const char *oldref,
 683                                 struct ref_list *list, int quiet)
 684 {
 685         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 686         while (list) {
 687                 /* list->name could be 'foo' or 'foo/bar/baz' */
 688                 if (!oldref || strcmp(oldref, list->name)) {
 689                         int len = strlen(list->name);
 690                         int cmplen = (namlen < len) ? namlen : len;
 691                         const char *lead = (namlen < len) ? list->name : ref;
 692                         if (!strncmp(ref, list->name, cmplen) &&
 693                             lead[cmplen] == '/') {
 694                                 if (!quiet)
 695                                         error("'%s' exists; cannot create '%s'",
 696                                               list->name, ref);
 697                                 return 0;
 698                         }
 699                 }
 700                 list = list->next;
 701         }
 702         return 1;
 703 }
 704
 705 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 706 {
 707         char *ref_file;
 708         const char *orig_ref = ref;
 709         struct ref_lock *lock;
 710         struct stat st;
 711         int last_errno = 0;
 712         int type;
 713         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 714
 715         lock = xcalloc(1, sizeof(struct ref_lock));
 716         lock->lock_fd = -1;
 717
 718         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
 719         if (!ref && errno == EISDIR) {
 720                 /* we are trying to lock foo but we used to
 721                  * have foo/bar which now does not exist;
 722                  * it is normal for the empty directory 'foo'
 723                  * to remain.
 724                  */
 725                 ref_file = git_path("%s", orig_ref);
 726                 if (remove_empty_directories(ref_file)) {
 727                         last_errno = errno;
 728                         error("there are still refs under '%s'", orig_ref);
 729                         goto error_return;
 730                 }
 731                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
 732         }
 733         if (type_p)
 734             *type_p = type;
 735         if (!ref) {
 736                 last_errno = errno;
 737                 error("unable to resolve reference %s: %s",
 738                         orig_ref, strerror(errno));
 739                 goto error_return;
 740         }
 741         /* When the ref did not exist and we are creating it,
 742          * make sure there is no existing ref that is packed
 743          * whose name begins with our refname, nor a ref whose
 744          * name is a proper prefix of our refname.
 745          */
 746         if (is_null_sha1(lock->old_sha1) &&
 747             !is_refname_available(ref, NULL, get_packed_refs(), 0))
 748                 goto error_return;
 749
 750         lock->lk = xcalloc(1, sizeof(struct lock_file));
 751
 752         if (flags & REF_NODEREF)
 753                 ref = orig_ref;
 754         lock->ref_name = xstrdup(ref);
 755         lock->orig_ref_name = xstrdup(orig_ref);
 756         ref_file = git_path("%s", ref);
 757         if (lstat(ref_file, &st) && errno == ENOENT)
 758                 lock->force_write = 1;
 759         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
 760                 lock->force_write = 1;
 761
 762         if (safe_create_leading_directories(ref_file)) {
 763                 last_errno = errno;
 764                 error("unable to create directory for %s", ref_file);
 765                 goto error_return;
 766         }
 767         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 768
 769         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 770
 771  error_return:
 772         unlock_ref(lock);
 773         errno = last_errno;
 774         return NULL;
 775 }
 776
 777 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 778 {
 779         char refpath[PATH_MAX];
 780         if (check_ref_format(ref))
 781                 return NULL;
 782         strcpy(refpath, mkpath("refs/%s", ref));
 783         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
 784 }
 785
 786 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
 787 {
 788         if (check_ref_format(ref) == -1)
 789                 return NULL;
 790         return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
 791 }
 792
 793 static struct lock_file packlock;
 794
 795 static int repack_without_ref(const char *refname)
 796 {
 797         struct ref_list *list, *packed_ref_list;
 798         int fd;
 799         int found = 0;
 800
 801         packed_ref_list = get_packed_refs();
 802         for (list = packed_ref_list; list; list = list->next) {
 803                 if (!strcmp(refname, list->name)) {
 804                         found = 1;
 805                         break;
 806                 }
 807         }
 808         if (!found)
 809                 return 0;
 810         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 811         if (fd < 0)
 812                 return error("cannot delete '%s' from packed refs", refname);
 813
 814         for (list = packed_ref_list; list; list = list->next) {
 815                 char line[PATH_MAX + 100];
 816                 int len;
 817
 818                 if (!strcmp(refname, list->name))
 819                         continue;
 820                 len = snprintf(line, sizeof(line), "%s %s\n",
 821                                sha1_to_hex(list->sha1), list->name);
 822                 /* this should not happen but just being defensive */
 823                 if (len > sizeof(line))
 824                         die("too long a refname '%s'", list->name);
 825                 write_or_die(fd, line, len);
 826         }
 827         close(fd);
 828         return commit_lock_file(&packlock);
 829 }
 830
 831 int delete_ref(const char *refname, const unsigned char *sha1)
 832 {
 833         struct ref_lock *lock;
 834         int err, i, ret = 0, flag = 0;
 835
 836         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
 837         if (!lock)
 838                 return 1;
 839         if (!(flag & REF_ISPACKED)) {
 840                 /* loose */
 841                 i = strlen(lock->lk->filename) - 5; /* .lock */
 842                 lock->lk->filename[i] = 0;
 843                 err = unlink(lock->lk->filename);
 844                 if (err) {
 845                         ret = 1;
 846                         error("unlink(%s) failed: %s",
 847                               lock->lk->filename, strerror(errno));
 848                 }
 849                 lock->lk->filename[i] = '.';
 850         }
 851         /* removing the loose one could have resurrected an earlier
 852          * packed one.  Also, if it was not loose we need to repack
 853          * without it.
 854          */
 855         ret |= repack_without_ref(refname);
 856
 857         err = unlink(git_path("logs/%s", lock->ref_name));
 858         if (err && errno != ENOENT)
 859                 fprintf(stderr, "warning: unlink(%s) failed: %s",
 860                         git_path("logs/%s", lock->ref_name), strerror(errno));
 861         invalidate_cached_refs();
 862         unlock_ref(lock);
 863         return ret;
 864 }
 865
 866 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 867 {
 868         static const char renamed_ref[] = "RENAMED-REF";
 869         unsigned char sha1[20], orig_sha1[20];
 870         int flag = 0, logmoved = 0;
 871         struct ref_lock *lock;
 872         struct stat loginfo;
 873         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
 874
 875         if (S_ISLNK(loginfo.st_mode))
 876                 return error("reflog for %s is a symlink", oldref);
 877
 878         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
 879                 return error("refname %s not found", oldref);
 880
 881         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
 882                 return 1;
 883
 884         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
 885                 return 1;
 886
 887         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
 888         if (!lock)
 889                 return error("unable to lock %s", renamed_ref);
 890         lock->force_write = 1;
 891         if (write_ref_sha1(lock, orig_sha1, logmsg))
 892                 return error("unable to save current sha1 in %s", renamed_ref);
 893
 894         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
 895                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
 896                         oldref, strerror(errno));
 897
 898         if (delete_ref(oldref, orig_sha1)) {
 899                 error("unable to delete old %s", oldref);
 900                 goto rollback;
 901         }
 902
 903         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
 904                 if (errno==EISDIR) {
 905                         if (remove_empty_directories(git_path("%s", newref))) {
 906                                 error("Directory not empty: %s", newref);
 907                                 goto rollback;
 908                         }
 909                 } else {
 910                         error("unable to delete existing %s", newref);
 911                         goto rollback;
 912                 }
 913         }
 914
 915         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
 916                 error("unable to create directory for %s", newref);
 917                 goto rollback;
 918         }
 919
 920  retry:
 921         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
 922                 if (errno==EISDIR || errno==ENOTDIR) {
 923                         /*
 924                          * rename(a, b) when b is an existing
 925                          * directory ought to result in ISDIR, but
 926                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
 927                          */
 928                         if (remove_empty_directories(git_path("logs/%s", newref))) {
 929                                 error("Directory not empty: logs/%s", newref);
 930                                 goto rollback;
 931                         }
 932                         goto retry;
 933                 } else {
 934                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
 935                                 newref, strerror(errno));
 936                         goto rollback;
 937                 }
 938         }
 939         logmoved = log;
 940
 941         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
 942         if (!lock) {
 943                 error("unable to lock %s for update", newref);
 944                 goto rollback;
 945         }
 946
 947         lock->force_write = 1;
 948         hashcpy(lock->old_sha1, orig_sha1);
 949         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
 950                 error("unable to write current sha1 into %s", newref);
 951                 goto rollback;
 952         }
 953
 954         return 0;
 955
 956  rollback:
 957         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
 958         if (!lock) {
 959                 error("unable to lock %s for rollback", oldref);
 960                 goto rollbacklog;
 961         }
 962
 963         lock->force_write = 1;
 964         flag = log_all_ref_updates;
 965         log_all_ref_updates = 0;
 966         if (write_ref_sha1(lock, orig_sha1, NULL))
 967                 error("unable to write current sha1 into %s", oldref);
 968         log_all_ref_updates = flag;
 969
 970  rollbacklog:
 971         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
 972                 error("unable to restore logfile %s from %s: %s",
 973                         oldref, newref, strerror(errno));
 974         if (!logmoved && log &&
 975             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
 976                 error("unable to restore logfile %s from tmp-renamed-log: %s",
 977                         oldref, strerror(errno));
 978
 979         return 1;
 980 }
 981
 982 void unlock_ref(struct ref_lock *lock)
 983 {
 984         if (lock->lock_fd >= 0) {
 985                 close(lock->lock_fd);
 986                 /* Do not free lock->lk -- atexit() still looks at them */
 987                 if (lock->lk)
 988                         rollback_lock_file(lock->lk);
 989         }
 990         free(lock->ref_name);
 991         free(lock->orig_ref_name);
 992         free(lock);
 993 }
 994
 995 /*
 996  * copy the reflog message msg to buf, which has been allocated sufficiently
 997  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
 998  * because reflog file is one line per entry.
 999  */
1000 static int copy_msg(char *buf, const char *msg)
1001 {
1002         char *cp = buf;
1003         char c;
1004         int wasspace = 1;
1005
1006         *cp++ = '\t';
1007         while ((c = *msg++)) {
1008                 if (wasspace && isspace(c))
1009                         continue;
1010                 wasspace = isspace(c);
1011                 if (wasspace)
1012                         c = ' ';
1013                 *cp++ = c;
1014         }
1015         while (buf < cp && isspace(cp[-1]))
1016                 cp--;
1017         *cp++ = '\n';
1018         return cp - buf;
1019 }
1020
1021 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1022                          const unsigned char *new_sha1, const char *msg)
1023 {
1024         int logfd, written, oflags = O_APPEND | O_WRONLY;
1025         unsigned maxlen, len;
1026         int msglen;
1027         char *log_file, *logrec;
1028         const char *committer;
1029
1030         if (log_all_ref_updates < 0)
1031                 log_all_ref_updates = !is_bare_repository();
1032
1033         log_file = git_path("logs/%s", ref_name);
1034
1035         if (log_all_ref_updates &&
1036             (!prefixcmp(ref_name, "refs/heads/") ||
1037              !prefixcmp(ref_name, "refs/remotes/") ||
1038              !strcmp(ref_name, "HEAD"))) {
1039                 if (safe_create_leading_directories(log_file) < 0)
1040                         return error("unable to create directory for %s",
1041                                      log_file);
1042                 oflags |= O_CREAT;
1043         }
1044
1045         logfd = open(log_file, oflags, 0666);
1046         if (logfd < 0) {
1047                 if (!(oflags & O_CREAT) && errno == ENOENT)
1048                         return 0;
1049
1050                 if ((oflags & O_CREAT) && errno == EISDIR) {
1051                         if (remove_empty_directories(log_file)) {
1052                                 return error("There are still logs under '%s'",
1053                                              log_file);
1054                         }
1055                         logfd = open(log_file, oflags, 0666);
1056                 }
1057
1058                 if (logfd < 0)
1059                         return error("Unable to append to %s: %s",
1060                                      log_file, strerror(errno));
1061         }
1062
1063         adjust_shared_perm(log_file);
1064
1065         msglen = msg ? strlen(msg) : 0;
1066         committer = git_committer_info(-1);
1067         maxlen = strlen(committer) + msglen + 100;
1068         logrec = xmalloc(maxlen);
1069         len = sprintf(logrec, "%s %s %s\n",
1070                       sha1_to_hex(old_sha1),
1071                       sha1_to_hex(new_sha1),
1072                       committer);
1073         if (msglen)
1074                 len += copy_msg(logrec + len - 1, msg) - 1;
1075         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1076         free(logrec);
1077         if (close(logfd) != 0 || written != len)
1078                 return error("Unable to append to %s", log_file);
1079         return 0;
1080 }
1081
1082 int write_ref_sha1(struct ref_lock *lock,
1083         const unsigned char *sha1, const char *logmsg)
1084 {
1085         static char term = '\n';
1086
1087         if (!lock)
1088                 return -1;
1089         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1090                 unlock_ref(lock);
1091                 return 0;
1092         }
1093         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1094             write_in_full(lock->lock_fd, &term, 1) != 1
1095                 || close(lock->lock_fd) < 0) {
1096                 error("Couldn't write %s", lock->lk->filename);
1097                 unlock_ref(lock);
1098                 return -1;
1099         }
1100         invalidate_cached_refs();
1101         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1102             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1103              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1104                 unlock_ref(lock);
1105                 return -1;
1106         }
1107         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1108                 /*
1109                  * Special hack: If a branch is updated directly and HEAD
1110                  * points to it (may happen on the remote side of a push
1111                  * for example) then logically the HEAD reflog should be
1112                  * updated too.
1113                  * A generic solution implies reverse symref information,
1114                  * but finding all symrefs pointing to the given branch
1115                  * would be rather costly for this rare event (the direct
1116                  * update of a branch) to be worth it.  So let's cheat and
1117                  * check with HEAD only which should cover 99% of all usage
1118                  * scenarios (even 100% of the default ones).
1119                  */
1120                 unsigned char head_sha1[20];
1121                 int head_flag;
1122                 const char *head_ref;
1123                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1124                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1125                     !strcmp(head_ref, lock->ref_name))
1126                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1127         }
1128         if (commit_lock_file(lock->lk)) {
1129                 error("Couldn't set %s", lock->ref_name);
1130                 unlock_ref(lock);
1131                 return -1;
1132         }
1133         lock->lock_fd = -1;
1134         unlock_ref(lock);
1135         return 0;
1136 }
1137
1138 int create_symref(const char *ref_target, const char *refs_heads_master,
1139                   const char *logmsg)
1140 {
1141         const char *lockpath;
1142         char ref[1000];
1143         int fd, len, written;
1144         char *git_HEAD = xstrdup(git_path("%s", ref_target));
1145         unsigned char old_sha1[20], new_sha1[20];
1146
1147         if (logmsg && read_ref(ref_target, old_sha1))
1148                 hashclr(old_sha1);
1149
1150         if (safe_create_leading_directories(git_HEAD) < 0)
1151                 return error("unable to create directory for %s", git_HEAD);
1152
1153 #ifndef NO_SYMLINK_HEAD
1154         if (prefer_symlink_refs) {
1155                 unlink(git_HEAD);
1156                 if (!symlink(refs_heads_master, git_HEAD))
1157                         goto done;
1158                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1159         }
1160 #endif
1161
1162         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1163         if (sizeof(ref) <= len) {
1164                 error("refname too long: %s", refs_heads_master);
1165                 goto error_free_return;
1166         }
1167         lockpath = mkpath("%s.lock", git_HEAD);
1168         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1169         if (fd < 0) {
1170                 error("Unable to open %s for writing", lockpath);
1171                 goto error_free_return;
1172         }
1173         written = write_in_full(fd, ref, len);
1174         if (close(fd) != 0 || written != len) {
1175                 error("Unable to write to %s", lockpath);
1176                 goto error_unlink_return;
1177         }
1178         if (rename(lockpath, git_HEAD) < 0) {
1179                 error("Unable to create %s", git_HEAD);
1180                 goto error_unlink_return;
1181         }
1182         if (adjust_shared_perm(git_HEAD)) {
1183                 error("Unable to fix permissions on %s", lockpath);
1184         error_unlink_return:
1185                 unlink(lockpath);
1186         error_free_return:
1187                 free(git_HEAD);
1188                 return -1;
1189         }
1190
1191 #ifndef NO_SYMLINK_HEAD
1192         done:
1193 #endif
1194         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1195                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1196
1197         free(git_HEAD);
1198         return 0;
1199 }
1200
1201 static char *ref_msg(const char *line, const char *endp)
1202 {
1203         const char *ep;
1204         line += 82;
1205         ep = memchr(line, '\n', endp - line);
1206         if (!ep)
1207                 ep = endp;
1208         return xmemdupz(line, ep - line);
1209 }
1210
1211 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)
1212 {
1213         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1214         char *tz_c;
1215         int logfd, tz, reccnt = 0;
1216         struct stat st;
1217         unsigned long date;
1218         unsigned char logged_sha1[20];
1219         void *log_mapped;
1220         size_t mapsz;
1221
1222         logfile = git_path("logs/%s", ref);
1223         logfd = open(logfile, O_RDONLY, 0);
1224         if (logfd < 0)
1225                 die("Unable to read log %s: %s", logfile, strerror(errno));
1226         fstat(logfd, &st);
1227         if (!st.st_size)
1228                 die("Log %s is empty.", logfile);
1229         mapsz = xsize_t(st.st_size);
1230         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1231         logdata = log_mapped;
1232         close(logfd);
1233
1234         lastrec = NULL;
1235         rec = logend = logdata + st.st_size;
1236         while (logdata < rec) {
1237                 reccnt++;
1238                 if (logdata < rec && *(rec-1) == '\n')
1239                         rec--;
1240                 lastgt = NULL;
1241                 while (logdata < rec && *(rec-1) != '\n') {
1242                         rec--;
1243                         if (*rec == '>')
1244                                 lastgt = rec;
1245                 }
1246                 if (!lastgt)
1247                         die("Log %s is corrupt.", logfile);
1248                 date = strtoul(lastgt + 1, &tz_c, 10);
1249                 if (date <= at_time || cnt == 0) {
1250                         tz = strtoul(tz_c, NULL, 10);
1251                         if (msg)
1252                                 *msg = ref_msg(rec, logend);
1253                         if (cutoff_time)
1254                                 *cutoff_time = date;
1255                         if (cutoff_tz)
1256                                 *cutoff_tz = tz;
1257                         if (cutoff_cnt)
1258                                 *cutoff_cnt = reccnt - 1;
1259                         if (lastrec) {
1260                                 if (get_sha1_hex(lastrec, logged_sha1))
1261                                         die("Log %s is corrupt.", logfile);
1262                                 if (get_sha1_hex(rec + 41, sha1))
1263                                         die("Log %s is corrupt.", logfile);
1264                                 if (hashcmp(logged_sha1, sha1)) {
1265                                         fprintf(stderr,
1266                                                 "warning: Log %s has gap after %s.\n",
1267                                                 logfile, show_date(date, tz, DATE_RFC2822));
1268                                 }
1269                         }
1270                         else if (date == at_time) {
1271                                 if (get_sha1_hex(rec + 41, sha1))
1272                                         die("Log %s is corrupt.", logfile);
1273                         }
1274                         else {
1275                                 if (get_sha1_hex(rec + 41, logged_sha1))
1276                                         die("Log %s is corrupt.", logfile);
1277                                 if (hashcmp(logged_sha1, sha1)) {
1278                                         fprintf(stderr,
1279                                                 "warning: Log %s unexpectedly ended on %s.\n",
1280                                                 logfile, show_date(date, tz, DATE_RFC2822));
1281                                 }
1282                         }
1283                         munmap(log_mapped, mapsz);
1284                         return 0;
1285                 }
1286                 lastrec = rec;
1287                 if (cnt > 0)
1288                         cnt--;
1289         }
1290
1291         rec = logdata;
1292         while (rec < logend && *rec != '>' && *rec != '\n')
1293                 rec++;
1294         if (rec == logend || *rec == '\n')
1295                 die("Log %s is corrupt.", logfile);
1296         date = strtoul(rec + 1, &tz_c, 10);
1297         tz = strtoul(tz_c, NULL, 10);
1298         if (get_sha1_hex(logdata, sha1))
1299                 die("Log %s is corrupt.", logfile);
1300         if (msg)
1301                 *msg = ref_msg(logdata, logend);
1302         munmap(log_mapped, mapsz);
1303
1304         if (cutoff_time)
1305                 *cutoff_time = date;
1306         if (cutoff_tz)
1307                 *cutoff_tz = tz;
1308         if (cutoff_cnt)
1309                 *cutoff_cnt = reccnt;
1310         return 1;
1311 }
1312
1313 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1314 {
1315         const char *logfile;
1316         FILE *logfp;
1317         char buf[1024];
1318         int ret = 0;
1319
1320         logfile = git_path("logs/%s", ref);
1321         logfp = fopen(logfile, "r");
1322         if (!logfp)
1323                 return -1;
1324         while (fgets(buf, sizeof(buf), logfp)) {
1325                 unsigned char osha1[20], nsha1[20];
1326                 char *email_end, *message;
1327                 unsigned long timestamp;
1328                 int len, tz;
1329
1330                 /* old SP new SP name <email> SP time TAB msg LF */
1331                 len = strlen(buf);
1332                 if (len < 83 || buf[len-1] != '\n' ||
1333                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1334                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1335                     !(email_end = strchr(buf + 82, '>')) ||
1336                     email_end[1] != ' ' ||
1337                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1338                     !message || message[0] != ' ' ||
1339                     (message[1] != '+' && message[1] != '-') ||
1340                     !isdigit(message[2]) || !isdigit(message[3]) ||
1341                     !isdigit(message[4]) || !isdigit(message[5]))
1342                         continue; /* corrupt? */
1343                 email_end[1] = '\0';
1344                 tz = strtol(message + 1, NULL, 10);
1345                 if (message[6] != '\t')
1346                         message += 6;
1347                 else
1348                         message += 7;
1349                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1350                 if (ret)
1351                         break;
1352         }
1353         fclose(logfp);
1354         return ret;
1355 }
1356
1357 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1358 {
1359         DIR *dir = opendir(git_path("logs/%s", base));
1360         int retval = 0;
1361
1362         if (dir) {
1363                 struct dirent *de;
1364                 int baselen = strlen(base);
1365                 char *log = xmalloc(baselen + 257);
1366
1367                 memcpy(log, base, baselen);
1368                 if (baselen && base[baselen-1] != '/')
1369                         log[baselen++] = '/';
1370
1371                 while ((de = readdir(dir)) != NULL) {
1372                         struct stat st;
1373                         int namelen;
1374
1375                         if (de->d_name[0] == '.')
1376                                 continue;
1377                         namelen = strlen(de->d_name);
1378                         if (namelen > 255)
1379                                 continue;
1380                         if (has_extension(de->d_name, ".lock"))
1381                                 continue;
1382                         memcpy(log + baselen, de->d_name, namelen+1);
1383                         if (stat(git_path("logs/%s", log), &st) < 0)
1384                                 continue;
1385                         if (S_ISDIR(st.st_mode)) {
1386                                 retval = do_for_each_reflog(log, fn, cb_data);
1387                         } else {
1388                                 unsigned char sha1[20];
1389                                 if (!resolve_ref(log, sha1, 0, NULL))
1390                                         retval = error("bad ref for %s", log);
1391                                 else
1392                                         retval = fn(log, sha1, 0, cb_data);
1393                         }
1394                         if (retval)
1395                                 break;
1396                 }
1397                 free(log);
1398                 closedir(dir);
1399         }
1400         else if (*base)
1401                 return errno;
1402         return retval;
1403 }
1404
1405 int for_each_reflog(each_ref_fn fn, void *cb_data)
1406 {
1407         return do_for_each_reflog("", fn, cb_data);
1408 }
1409
1410 int update_ref(const char *action, const char *refname,
1411                 const unsigned char *sha1, const unsigned char *oldval,
1412                 int flags, enum action_on_err onerr)
1413 {
1414         static struct ref_lock *lock;
1415         lock = lock_any_ref_for_update(refname, oldval, flags);
1416         if (!lock) {
1417                 const char *str = "Cannot lock the ref '%s'.";
1418                 switch (onerr) {
1419                 case MSG_ON_ERR: error(str, refname); break;
1420                 case DIE_ON_ERR: die(str, refname); break;
1421                 case QUIET_ON_ERR: break;
1422                 }
1423                 return 1;
1424         }
1425         if (write_ref_sha1(lock, sha1, action) < 0) {
1426                 const char *str = "Cannot update the ref '%s'.";
1427                 switch (onerr) {
1428                 case MSG_ON_ERR: error(str, refname); break;
1429                 case DIE_ON_ERR: die(str, refname); break;
1430                 case QUIET_ON_ERR: break;
1431                 }
1432                 return 1;
1433         }
1434         return 0;
1435 }
1436
1437 struct ref *find_ref_by_name(struct ref *list, const char *name)
1438 {
1439         for ( ; list; list = list->next)
1440                 if (!strcmp(list->name, name))
1441                         return list;
1442         return NULL;
1443 }