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 static struct ref_list *current_ref;
 161
 162 static struct ref_list *extra_refs;
 163
 164 static void free_ref_list(struct ref_list *list)
 165 {
 166         struct ref_list *next;
 167         for ( ; list; list = next) {
 168                 next = list->next;
 169                 free(list);
 170         }
 171 }
 172
 173 static void invalidate_cached_refs(void)
 174 {
 175         struct cached_refs *ca = &cached_refs;
 176
 177         if (ca->did_loose && ca->loose)
 178                 free_ref_list(ca->loose);
 179         if (ca->did_packed && ca->packed)
 180                 free_ref_list(ca->packed);
 181         ca->loose = ca->packed = NULL;
 182         ca->did_loose = ca->did_packed = 0;
 183 }
 184
 185 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 186 {
 187         struct ref_list *list = NULL;
 188         struct ref_list *last = NULL;
 189         char refline[PATH_MAX];
 190         int flag = REF_ISPACKED;
 191
 192         while (fgets(refline, sizeof(refline), f)) {
 193                 unsigned char sha1[20];
 194                 const char *name;
 195                 static const char header[] = "# pack-refs with:";
 196
 197                 if (!strncmp(refline, header, sizeof(header)-1)) {
 198                         const char *traits = refline + sizeof(header) - 1;
 199                         if (strstr(traits, " peeled "))
 200                                 flag |= REF_KNOWS_PEELED;
 201                         /* perhaps other traits later as well */
 202                         continue;
 203                 }
 204
 205                 name = parse_ref_line(refline, sha1);
 206                 if (name) {
 207                         list = add_ref(name, sha1, flag, list, &last);
 208                         continue;
 209                 }
 210                 if (last &&
 211                     refline[0] == '^' &&
 212                     strlen(refline) == 42 &&
 213                     refline[41] == '\n' &&
 214                     !get_sha1_hex(refline + 1, sha1))
 215                         hashcpy(last->peeled, sha1);
 216         }
 217         cached_refs->packed = sort_ref_list(list);
 218 }
 219
 220 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 221 {
 222         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
 223 }
 224
 225 void clear_extra_refs(void)
 226 {
 227         free_ref_list(extra_refs);
 228         extra_refs = NULL;
 229 }
 230
 231 static struct ref_list *get_packed_refs(void)
 232 {
 233         if (!cached_refs.did_packed) {
 234                 FILE *f = fopen(git_path("packed-refs"), "r");
 235                 cached_refs.packed = NULL;
 236                 if (f) {
 237                         read_packed_refs(f, &cached_refs);
 238                         fclose(f);
 239                 }
 240                 cached_refs.did_packed = 1;
 241         }
 242         return cached_refs.packed;
 243 }
 244
 245 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 246 {
 247         DIR *dir = opendir(git_path("%s", base));
 248
 249         if (dir) {
 250                 struct dirent *de;
 251                 int baselen = strlen(base);
 252                 char *ref = xmalloc(baselen + 257);
 253
 254                 memcpy(ref, base, baselen);
 255                 if (baselen && base[baselen-1] != '/')
 256                         ref[baselen++] = '/';
 257
 258                 while ((de = readdir(dir)) != NULL) {
 259                         unsigned char sha1[20];
 260                         struct stat st;
 261                         int flag;
 262                         int namelen;
 263
 264                         if (de->d_name[0] == '.')
 265                                 continue;
 266                         namelen = strlen(de->d_name);
 267                         if (namelen > 255)
 268                                 continue;
 269                         if (has_extension(de->d_name, ".lock"))
 270                                 continue;
 271                         memcpy(ref + baselen, de->d_name, namelen+1);
 272                         if (stat(git_path("%s", ref), &st) < 0)
 273                                 continue;
 274                         if (S_ISDIR(st.st_mode)) {
 275                                 list = get_ref_dir(ref, list);
 276                                 continue;
 277                         }
 278                         if (!resolve_ref(ref, sha1, 1, &flag)) {
 279                                 error("%s points nowhere!", ref);
 280                                 continue;
 281                         }
 282                         list = add_ref(ref, sha1, flag, list, NULL);
 283                 }
 284                 free(ref);
 285                 closedir(dir);
 286         }
 287         return sort_ref_list(list);
 288 }
 289
 290 static struct ref_list *get_loose_refs(void)
 291 {
 292         if (!cached_refs.did_loose) {
 293                 cached_refs.loose = get_ref_dir("refs", NULL);
 294                 cached_refs.did_loose = 1;
 295         }
 296         return cached_refs.loose;
 297 }
 298
 299 /* We allow "recursive" symbolic refs. Only within reason, though */
 300 #define MAXDEPTH 5
 301 #define MAXREFLEN (1024)
 302
 303 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 304 {
 305         FILE *f;
 306         struct cached_refs refs;
 307         struct ref_list *ref;
 308         int retval;
 309
 310         strcpy(name + pathlen, "packed-refs");
 311         f = fopen(name, "r");
 312         if (!f)
 313                 return -1;
 314         read_packed_refs(f, &refs);
 315         fclose(f);
 316         ref = refs.packed;
 317         retval = -1;
 318         while (ref) {
 319                 if (!strcmp(ref->name, refname)) {
 320                         retval = 0;
 321                         memcpy(result, ref->sha1, 20);
 322                         break;
 323                 }
 324                 ref = ref->next;
 325         }
 326         free_ref_list(refs.packed);
 327         return retval;
 328 }
 329
 330 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 331 {
 332         int fd, len = strlen(refname);
 333         char buffer[128], *p;
 334
 335         if (recursion > MAXDEPTH || len > MAXREFLEN)
 336                 return -1;
 337         memcpy(name + pathlen, refname, len+1);
 338         fd = open(name, O_RDONLY);
 339         if (fd < 0)
 340                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 341
 342         len = read(fd, buffer, sizeof(buffer)-1);
 343         close(fd);
 344         if (len < 0)
 345                 return -1;
 346         while (len && isspace(buffer[len-1]))
 347                 len--;
 348         buffer[len] = 0;
 349
 350         /* Was it a detached head or an old-fashioned symlink? */
 351         if (!get_sha1_hex(buffer, result))
 352                 return 0;
 353
 354         /* Symref? */
 355         if (strncmp(buffer, "ref:", 4))
 356                 return -1;
 357         p = buffer + 4;
 358         while (isspace(*p))
 359                 p++;
 360
 361         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 362 }
 363
 364 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 365 {
 366         int len = strlen(path), retval;
 367         char *gitdir;
 368         const char *tmp;
 369
 370         while (len && path[len-1] == '/')
 371                 len--;
 372         if (!len)
 373                 return -1;
 374         gitdir = xmalloc(len + MAXREFLEN + 8);
 375         memcpy(gitdir, path, len);
 376         memcpy(gitdir + len, "/.git", 6);
 377         len += 5;
 378
 379         tmp = read_gitfile_gently(gitdir);
 380         if (tmp) {
 381                 free(gitdir);
 382                 len = strlen(tmp);
 383                 gitdir = xmalloc(len + MAXREFLEN + 3);
 384                 memcpy(gitdir, tmp, len);
 385         }
 386         gitdir[len] = '/';
 387         gitdir[++len] = '\0';
 388         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 389         free(gitdir);
 390         return retval;
 391 }
 392
 393 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 394 {
 395         int depth = MAXDEPTH;
 396         ssize_t len;
 397         char buffer[256];
 398         static char ref_buffer[256];
 399
 400         if (flag)
 401                 *flag = 0;
 402
 403         for (;;) {
 404                 const char *path = git_path("%s", ref);
 405                 struct stat st;
 406                 char *buf;
 407                 int fd;
 408
 409                 if (--depth < 0)
 410                         return NULL;
 411
 412                 /* Special case: non-existing file.
 413                  * Not having the refs/heads/new-branch is OK
 414                  * if we are writing into it, so is .git/HEAD
 415                  * that points at refs/heads/master still to be
 416                  * born.  It is NOT OK if we are resolving for
 417                  * reading.
 418                  */
 419                 if (lstat(path, &st) < 0) {
 420                         struct ref_list *list = get_packed_refs();
 421                         while (list) {
 422                                 if (!strcmp(ref, list->name)) {
 423                                         hashcpy(sha1, list->sha1);
 424                                         if (flag)
 425                                                 *flag |= REF_ISPACKED;
 426                                         return ref;
 427                                 }
 428                                 list = list->next;
 429                         }
 430                         if (reading || errno != ENOENT)
 431                                 return NULL;
 432                         hashclr(sha1);
 433                         return ref;
 434                 }
 435
 436                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 437                 if (S_ISLNK(st.st_mode)) {
 438                         len = readlink(path, buffer, sizeof(buffer)-1);
 439                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 440                                 buffer[len] = 0;
 441                                 strcpy(ref_buffer, buffer);
 442                                 ref = ref_buffer;
 443                                 if (flag)
 444                                         *flag |= REF_ISSYMREF;
 445                                 continue;
 446                         }
 447                 }
 448
 449                 /* Is it a directory? */
 450                 if (S_ISDIR(st.st_mode)) {
 451                         errno = EISDIR;
 452                         return NULL;
 453                 }
 454
 455                 /*
 456                  * Anything else, just open it and try to use it as
 457                  * a ref
 458                  */
 459                 fd = open(path, O_RDONLY);
 460                 if (fd < 0)
 461                         return NULL;
 462                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 463                 close(fd);
 464
 465                 /*
 466                  * Is it a symbolic ref?
 467                  */
 468                 if (len < 4 || memcmp("ref:", buffer, 4))
 469                         break;
 470                 buf = buffer + 4;
 471                 len -= 4;
 472                 while (len && isspace(*buf))
 473                         buf++, len--;
 474                 while (len && isspace(buf[len-1]))
 475                         len--;
 476                 buf[len] = 0;
 477                 memcpy(ref_buffer, buf, len + 1);
 478                 ref = ref_buffer;
 479                 if (flag)
 480                         *flag |= REF_ISSYMREF;
 481         }
 482         if (len < 40 || get_sha1_hex(buffer, sha1))
 483                 return NULL;
 484         return ref;
 485 }
 486
 487 int read_ref(const char *ref, unsigned char *sha1)
 488 {
 489         if (resolve_ref(ref, sha1, 1, NULL))
 490                 return 0;
 491         return -1;
 492 }
 493
 494 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 495                       void *cb_data, struct ref_list *entry)
 496 {
 497         if (strncmp(base, entry->name, trim))
 498                 return 0;
 499         if (is_null_sha1(entry->sha1))
 500                 return 0;
 501         if (!has_sha1_file(entry->sha1)) {
 502                 error("%s does not point to a valid object!", entry->name);
 503                 return 0;
 504         }
 505         current_ref = entry;
 506         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 507 }
 508
 509 int peel_ref(const char *ref, unsigned char *sha1)
 510 {
 511         int flag;
 512         unsigned char base[20];
 513         struct object *o;
 514
 515         if (current_ref && (current_ref->name == ref
 516                 || !strcmp(current_ref->name, ref))) {
 517                 if (current_ref->flag & REF_KNOWS_PEELED) {
 518                         hashcpy(sha1, current_ref->peeled);
 519                         return 0;
 520                 }
 521                 hashcpy(base, current_ref->sha1);
 522                 goto fallback;
 523         }
 524
 525         if (!resolve_ref(ref, base, 1, &flag))
 526                 return -1;
 527
 528         if ((flag & REF_ISPACKED)) {
 529                 struct ref_list *list = get_packed_refs();
 530
 531                 while (list) {
 532                         if (!strcmp(list->name, ref)) {
 533                                 if (list->flag & REF_KNOWS_PEELED) {
 534                                         hashcpy(sha1, list->peeled);
 535                                         return 0;
 536                                 }
 537                                 /* older pack-refs did not leave peeled ones */
 538                                 break;
 539                         }
 540                         list = list->next;
 541                 }
 542         }
 543
 544 fallback:
 545         o = parse_object(base);
 546         if (o && o->type == OBJ_TAG) {
 547                 o = deref_tag(o, ref, 0);
 548                 if (o) {
 549                         hashcpy(sha1, o->sha1);
 550                         return 0;
 551                 }
 552         }
 553         return -1;
 554 }
 555
 556 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 557                            void *cb_data)
 558 {
 559         int retval = 0;
 560         struct ref_list *packed = get_packed_refs();
 561         struct ref_list *loose = get_loose_refs();
 562
 563         struct ref_list *extra;
 564
 565         for (extra = extra_refs; extra; extra = extra->next)
 566                 retval = do_one_ref(base, fn, trim, cb_data, extra);
 567
 568         while (packed && loose) {
 569                 struct ref_list *entry;
 570                 int cmp = strcmp(packed->name, loose->name);
 571                 if (!cmp) {
 572                         packed = packed->next;
 573                         continue;
 574                 }
 575                 if (cmp > 0) {
 576                         entry = loose;
 577                         loose = loose->next;
 578                 } else {
 579                         entry = packed;
 580                         packed = packed->next;
 581                 }
 582                 retval = do_one_ref(base, fn, trim, cb_data, entry);
 583                 if (retval)
 584                         goto end_each;
 585         }
 586
 587         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 588                 retval = do_one_ref(base, fn, trim, cb_data, packed);
 589                 if (retval)
 590                         goto end_each;
 591         }
 592
 593 end_each:
 594         current_ref = NULL;
 595         return retval;
 596 }
 597
 598 int head_ref(each_ref_fn fn, void *cb_data)
 599 {
 600         unsigned char sha1[20];
 601         int flag;
 602
 603         if (resolve_ref("HEAD", sha1, 1, &flag))
 604                 return fn("HEAD", sha1, flag, cb_data);
 605         return 0;
 606 }
 607
 608 int for_each_ref(each_ref_fn fn, void *cb_data)
 609 {
 610         return do_for_each_ref("refs/", fn, 0, cb_data);
 611 }
 612
 613 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 614 {
 615         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 616 }
 617
 618 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 619 {
 620         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 621 }
 622
 623 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 624 {
 625         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 626 }
 627
 628 /*
 629  * Make sure "ref" is something reasonable to have under ".git/refs/";
 630  * We do not like it if:
 631  *
 632  * - any path component of it begins with ".", or
 633  * - it has double dots "..", or
 634  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 635  * - it ends with a "/".
 636  */
 637
 638 static inline int bad_ref_char(int ch)
 639 {
 640         if (((unsigned) ch) <= ' ' ||
 641             ch == '~' || ch == '^' || ch == ':')
 642                 return 1;
 643         /* 2.13 Pattern Matching Notation */
 644         if (ch == '?' || ch == '[') /* Unsupported */
 645                 return 1;
 646         if (ch == '*') /* Supported at the end */
 647                 return 2;
 648         return 0;
 649 }
 650
 651 int check_ref_format(const char *ref)
 652 {
 653         int ch, level, bad_type;
 654         const char *cp = ref;
 655
 656         level = 0;
 657         while (1) {
 658                 while ((ch = *cp++) == '/')
 659                         ; /* tolerate duplicated slashes */
 660                 if (!ch)
 661                         /* should not end with slashes */
 662                         return CHECK_REF_FORMAT_ERROR;
 663
 664                 /* we are at the beginning of the path component */
 665                 if (ch == '.')
 666                         return CHECK_REF_FORMAT_ERROR;
 667                 bad_type = bad_ref_char(ch);
 668                 if (bad_type) {
 669                         return (bad_type == 2 && !*cp)
 670                                 ? CHECK_REF_FORMAT_WILDCARD
 671                                 : CHECK_REF_FORMAT_ERROR;
 672                 }
 673
 674                 /* scan the rest of the path component */
 675                 while ((ch = *cp++) != 0) {
 676                         bad_type = bad_ref_char(ch);
 677                         if (bad_type) {
 678                                 return (bad_type == 2 && !*cp)
 679                                         ? CHECK_REF_FORMAT_WILDCARD
 680                                         : CHECK_REF_FORMAT_ERROR;
 681                         }
 682                         if (ch == '/')
 683                                 break;
 684                         if (ch == '.' && *cp == '.')
 685                                 return CHECK_REF_FORMAT_ERROR;
 686                 }
 687                 level++;
 688                 if (!ch) {
 689                         if (level < 2)
 690                                 return CHECK_REF_FORMAT_ONELEVEL;
 691                         return CHECK_REF_FORMAT_OK;
 692                 }
 693         }
 694 }
 695
 696 const char *ref_rev_parse_rules[] = {
 697         "%.*s",
 698         "refs/%.*s",
 699         "refs/tags/%.*s",
 700         "refs/heads/%.*s",
 701         "refs/remotes/%.*s",
 702         "refs/remotes/%.*s/HEAD",
 703         NULL
 704 };
 705
 706 const char *ref_fetch_rules[] = {
 707         "%.*s",
 708         "refs/%.*s",
 709         "refs/heads/%.*s",
 710         NULL
 711 };
 712
 713 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 714 {
 715         const char **p;
 716         const int abbrev_name_len = strlen(abbrev_name);
 717
 718         for (p = rules; *p; p++) {
 719                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 720                         return 1;
 721                 }
 722         }
 723
 724         return 0;
 725 }
 726
 727 static struct ref_lock *verify_lock(struct ref_lock *lock,
 728         const unsigned char *old_sha1, int mustexist)
 729 {
 730         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 731                 error("Can't verify ref %s", lock->ref_name);
 732                 unlock_ref(lock);
 733                 return NULL;
 734         }
 735         if (hashcmp(lock->old_sha1, old_sha1)) {
 736                 error("Ref %s is at %s but expected %s", lock->ref_name,
 737                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 738                 unlock_ref(lock);
 739                 return NULL;
 740         }
 741         return lock;
 742 }
 743
 744 static int remove_empty_directories(const char *file)
 745 {
 746         /* we want to create a file but there is a directory there;
 747          * if that is an empty directory (or a directory that contains
 748          * only empty directories), remove them.
 749          */
 750         struct strbuf path;
 751         int result;
 752
 753         strbuf_init(&path, 20);
 754         strbuf_addstr(&path, file);
 755
 756         result = remove_dir_recursively(&path, 1);
 757
 758         strbuf_release(&path);
 759
 760         return result;
 761 }
 762
 763 static int is_refname_available(const char *ref, const char *oldref,
 764                                 struct ref_list *list, int quiet)
 765 {
 766         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 767         while (list) {
 768                 /* list->name could be 'foo' or 'foo/bar/baz' */
 769                 if (!oldref || strcmp(oldref, list->name)) {
 770                         int len = strlen(list->name);
 771                         int cmplen = (namlen < len) ? namlen : len;
 772                         const char *lead = (namlen < len) ? list->name : ref;
 773                         if (!strncmp(ref, list->name, cmplen) &&
 774                             lead[cmplen] == '/') {
 775                                 if (!quiet)
 776                                         error("'%s' exists; cannot create '%s'",
 777                                               list->name, ref);
 778                                 return 0;
 779                         }
 780                 }
 781                 list = list->next;
 782         }
 783         return 1;
 784 }
 785
 786 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 787 {
 788         char *ref_file;
 789         const char *orig_ref = ref;
 790         struct ref_lock *lock;
 791         struct stat st;
 792         int last_errno = 0;
 793         int type, lflags;
 794         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 795
 796         lock = xcalloc(1, sizeof(struct ref_lock));
 797         lock->lock_fd = -1;
 798
 799         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
 800         if (!ref && errno == EISDIR) {
 801                 /* we are trying to lock foo but we used to
 802                  * have foo/bar which now does not exist;
 803                  * it is normal for the empty directory 'foo'
 804                  * to remain.
 805                  */
 806                 ref_file = git_path("%s", orig_ref);
 807                 if (remove_empty_directories(ref_file)) {
 808                         last_errno = errno;
 809                         error("there are still refs under '%s'", orig_ref);
 810                         goto error_return;
 811                 }
 812                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
 813         }
 814         if (type_p)
 815             *type_p = type;
 816         if (!ref) {
 817                 last_errno = errno;
 818                 error("unable to resolve reference %s: %s",
 819                         orig_ref, strerror(errno));
 820                 goto error_return;
 821         }
 822         /* When the ref did not exist and we are creating it,
 823          * make sure there is no existing ref that is packed
 824          * whose name begins with our refname, nor a ref whose
 825          * name is a proper prefix of our refname.
 826          */
 827         if (is_null_sha1(lock->old_sha1) &&
 828             !is_refname_available(ref, NULL, get_packed_refs(), 0))
 829                 goto error_return;
 830
 831         lock->lk = xcalloc(1, sizeof(struct lock_file));
 832
 833         lflags = LOCK_DIE_ON_ERROR;
 834         if (flags & REF_NODEREF) {
 835                 ref = orig_ref;
 836                 lflags |= LOCK_NODEREF;
 837         }
 838         lock->ref_name = xstrdup(ref);
 839         lock->orig_ref_name = xstrdup(orig_ref);
 840         ref_file = git_path("%s", ref);
 841         if (lstat(ref_file, &st) && errno == ENOENT)
 842                 lock->force_write = 1;
 843         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
 844                 lock->force_write = 1;
 845
 846         if (safe_create_leading_directories(ref_file)) {
 847                 last_errno = errno;
 848                 error("unable to create directory for %s", ref_file);
 849                 goto error_return;
 850         }
 851
 852         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 853         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 854
 855  error_return:
 856         unlock_ref(lock);
 857         errno = last_errno;
 858         return NULL;
 859 }
 860
 861 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 862 {
 863         char refpath[PATH_MAX];
 864         if (check_ref_format(ref))
 865                 return NULL;
 866         strcpy(refpath, mkpath("refs/%s", ref));
 867         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
 868 }
 869
 870 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
 871 {
 872         switch (check_ref_format(ref)) {
 873         default:
 874                 return NULL;
 875         case 0:
 876         case CHECK_REF_FORMAT_ONELEVEL:
 877                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
 878         }
 879 }
 880
 881 static struct lock_file packlock;
 882
 883 static int repack_without_ref(const char *refname)
 884 {
 885         struct ref_list *list, *packed_ref_list;
 886         int fd;
 887         int found = 0;
 888
 889         packed_ref_list = get_packed_refs();
 890         for (list = packed_ref_list; list; list = list->next) {
 891                 if (!strcmp(refname, list->name)) {
 892                         found = 1;
 893                         break;
 894                 }
 895         }
 896         if (!found)
 897                 return 0;
 898         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 899         if (fd < 0)
 900                 return error("cannot delete '%s' from packed refs", refname);
 901
 902         for (list = packed_ref_list; list; list = list->next) {
 903                 char line[PATH_MAX + 100];
 904                 int len;
 905
 906                 if (!strcmp(refname, list->name))
 907                         continue;
 908                 len = snprintf(line, sizeof(line), "%s %s\n",
 909                                sha1_to_hex(list->sha1), list->name);
 910                 /* this should not happen but just being defensive */
 911                 if (len > sizeof(line))
 912                         die("too long a refname '%s'", list->name);
 913                 write_or_die(fd, line, len);
 914         }
 915         return commit_lock_file(&packlock);
 916 }
 917
 918 int delete_ref(const char *refname, const unsigned char *sha1)
 919 {
 920         struct ref_lock *lock;
 921         int err, i, ret = 0, flag = 0;
 922
 923         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
 924         if (!lock)
 925                 return 1;
 926         if (!(flag & REF_ISPACKED)) {
 927                 /* loose */
 928                 i = strlen(lock->lk->filename) - 5; /* .lock */
 929                 lock->lk->filename[i] = 0;
 930                 err = unlink(lock->lk->filename);
 931                 if (err && errno != ENOENT) {
 932                         ret = 1;
 933                         error("unlink(%s) failed: %s",
 934                               lock->lk->filename, strerror(errno));
 935                 }
 936                 lock->lk->filename[i] = '.';
 937         }
 938         /* removing the loose one could have resurrected an earlier
 939          * packed one.  Also, if it was not loose we need to repack
 940          * without it.
 941          */
 942         ret |= repack_without_ref(refname);
 943
 944         err = unlink(git_path("logs/%s", lock->ref_name));
 945         if (err && errno != ENOENT)
 946                 fprintf(stderr, "warning: unlink(%s) failed: %s",
 947                         git_path("logs/%s", lock->ref_name), strerror(errno));
 948         invalidate_cached_refs();
 949         unlock_ref(lock);
 950         return ret;
 951 }
 952
 953 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 954 {
 955         static const char renamed_ref[] = "RENAMED-REF";
 956         unsigned char sha1[20], orig_sha1[20];
 957         int flag = 0, logmoved = 0;
 958         struct ref_lock *lock;
 959         struct stat loginfo;
 960         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
 961
 962         if (S_ISLNK(loginfo.st_mode))
 963                 return error("reflog for %s is a symlink", oldref);
 964
 965         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
 966                 return error("refname %s not found", oldref);
 967
 968         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
 969                 return 1;
 970
 971         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
 972                 return 1;
 973
 974         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
 975         if (!lock)
 976                 return error("unable to lock %s", renamed_ref);
 977         lock->force_write = 1;
 978         if (write_ref_sha1(lock, orig_sha1, logmsg))
 979                 return error("unable to save current sha1 in %s", renamed_ref);
 980
 981         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
 982                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
 983                         oldref, strerror(errno));
 984
 985         if (delete_ref(oldref, orig_sha1)) {
 986                 error("unable to delete old %s", oldref);
 987                 goto rollback;
 988         }
 989
 990         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
 991                 if (errno==EISDIR) {
 992                         if (remove_empty_directories(git_path("%s", newref))) {
 993                                 error("Directory not empty: %s", newref);
 994                                 goto rollback;
 995                         }
 996                 } else {
 997                         error("unable to delete existing %s", newref);
 998                         goto rollback;
 999                 }
1000         }
1001
1002         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1003                 error("unable to create directory for %s", newref);
1004                 goto rollback;
1005         }
1006
1007  retry:
1008         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
1009                 if (errno==EISDIR || errno==ENOTDIR) {
1010                         /*
1011                          * rename(a, b) when b is an existing
1012                          * directory ought to result in ISDIR, but
1013                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1014                          */
1015                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1016                                 error("Directory not empty: logs/%s", newref);
1017                                 goto rollback;
1018                         }
1019                         goto retry;
1020                 } else {
1021                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
1022                                 newref, strerror(errno));
1023                         goto rollback;
1024                 }
1025         }
1026         logmoved = log;
1027
1028         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1029         if (!lock) {
1030                 error("unable to lock %s for update", newref);
1031                 goto rollback;
1032         }
1033
1034         lock->force_write = 1;
1035         hashcpy(lock->old_sha1, orig_sha1);
1036         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1037                 error("unable to write current sha1 into %s", newref);
1038                 goto rollback;
1039         }
1040
1041         return 0;
1042
1043  rollback:
1044         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1045         if (!lock) {
1046                 error("unable to lock %s for rollback", oldref);
1047                 goto rollbacklog;
1048         }
1049
1050         lock->force_write = 1;
1051         flag = log_all_ref_updates;
1052         log_all_ref_updates = 0;
1053         if (write_ref_sha1(lock, orig_sha1, NULL))
1054                 error("unable to write current sha1 into %s", oldref);
1055         log_all_ref_updates = flag;
1056
1057  rollbacklog:
1058         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1059                 error("unable to restore logfile %s from %s: %s",
1060                         oldref, newref, strerror(errno));
1061         if (!logmoved && log &&
1062             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1063                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1064                         oldref, strerror(errno));
1065
1066         return 1;
1067 }
1068
1069 int close_ref(struct ref_lock *lock)
1070 {
1071         if (close_lock_file(lock->lk))
1072                 return -1;
1073         lock->lock_fd = -1;
1074         return 0;
1075 }
1076
1077 int commit_ref(struct ref_lock *lock)
1078 {
1079         if (commit_lock_file(lock->lk))
1080                 return -1;
1081         lock->lock_fd = -1;
1082         return 0;
1083 }
1084
1085 void unlock_ref(struct ref_lock *lock)
1086 {
1087         /* Do not free lock->lk -- atexit() still looks at them */
1088         if (lock->lk)
1089                 rollback_lock_file(lock->lk);
1090         free(lock->ref_name);
1091         free(lock->orig_ref_name);
1092         free(lock);
1093 }
1094
1095 /*
1096  * copy the reflog message msg to buf, which has been allocated sufficiently
1097  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1098  * because reflog file is one line per entry.
1099  */
1100 static int copy_msg(char *buf, const char *msg)
1101 {
1102         char *cp = buf;
1103         char c;
1104         int wasspace = 1;
1105
1106         *cp++ = '\t';
1107         while ((c = *msg++)) {
1108                 if (wasspace && isspace(c))
1109                         continue;
1110                 wasspace = isspace(c);
1111                 if (wasspace)
1112                         c = ' ';
1113                 *cp++ = c;
1114         }
1115         while (buf < cp && isspace(cp[-1]))
1116                 cp--;
1117         *cp++ = '\n';
1118         return cp - buf;
1119 }
1120
1121 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1122                          const unsigned char *new_sha1, const char *msg)
1123 {
1124         int logfd, written, oflags = O_APPEND | O_WRONLY;
1125         unsigned maxlen, len;
1126         int msglen;
1127         char *log_file, *logrec;
1128         const char *committer;
1129
1130         if (log_all_ref_updates < 0)
1131                 log_all_ref_updates = !is_bare_repository();
1132
1133         log_file = git_path("logs/%s", ref_name);
1134
1135         if (log_all_ref_updates &&
1136             (!prefixcmp(ref_name, "refs/heads/") ||
1137              !prefixcmp(ref_name, "refs/remotes/") ||
1138              !strcmp(ref_name, "HEAD"))) {
1139                 if (safe_create_leading_directories(log_file) < 0)
1140                         return error("unable to create directory for %s",
1141                                      log_file);
1142                 oflags |= O_CREAT;
1143         }
1144
1145         logfd = open(log_file, oflags, 0666);
1146         if (logfd < 0) {
1147                 if (!(oflags & O_CREAT) && errno == ENOENT)
1148                         return 0;
1149
1150                 if ((oflags & O_CREAT) && errno == EISDIR) {
1151                         if (remove_empty_directories(log_file)) {
1152                                 return error("There are still logs under '%s'",
1153                                              log_file);
1154                         }
1155                         logfd = open(log_file, oflags, 0666);
1156                 }
1157
1158                 if (logfd < 0)
1159                         return error("Unable to append to %s: %s",
1160                                      log_file, strerror(errno));
1161         }
1162
1163         adjust_shared_perm(log_file);
1164
1165         msglen = msg ? strlen(msg) : 0;
1166         committer = git_committer_info(0);
1167         maxlen = strlen(committer) + msglen + 100;
1168         logrec = xmalloc(maxlen);
1169         len = sprintf(logrec, "%s %s %s\n",
1170                       sha1_to_hex(old_sha1),
1171                       sha1_to_hex(new_sha1),
1172                       committer);
1173         if (msglen)
1174                 len += copy_msg(logrec + len - 1, msg) - 1;
1175         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1176         free(logrec);
1177         if (close(logfd) != 0 || written != len)
1178                 return error("Unable to append to %s", log_file);
1179         return 0;
1180 }
1181
1182 static int is_branch(const char *refname)
1183 {
1184         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1185 }
1186
1187 int write_ref_sha1(struct ref_lock *lock,
1188         const unsigned char *sha1, const char *logmsg)
1189 {
1190         static char term = '\n';
1191         struct object *o;
1192
1193         if (!lock)
1194                 return -1;
1195         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1196                 unlock_ref(lock);
1197                 return 0;
1198         }
1199         o = parse_object(sha1);
1200         if (!o) {
1201                 error("Trying to write ref %s with nonexistant object %s",
1202                         lock->ref_name, sha1_to_hex(sha1));
1203                 unlock_ref(lock);
1204                 return -1;
1205         }
1206         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1207                 error("Trying to write non-commit object %s to branch %s",
1208                         sha1_to_hex(sha1), lock->ref_name);
1209                 unlock_ref(lock);
1210                 return -1;
1211         }
1212         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1213             write_in_full(lock->lock_fd, &term, 1) != 1
1214                 || close_ref(lock) < 0) {
1215                 error("Couldn't write %s", lock->lk->filename);
1216                 unlock_ref(lock);
1217                 return -1;
1218         }
1219         invalidate_cached_refs();
1220         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1221             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1222              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1223                 unlock_ref(lock);
1224                 return -1;
1225         }
1226         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1227                 /*
1228                  * Special hack: If a branch is updated directly and HEAD
1229                  * points to it (may happen on the remote side of a push
1230                  * for example) then logically the HEAD reflog should be
1231                  * updated too.
1232                  * A generic solution implies reverse symref information,
1233                  * but finding all symrefs pointing to the given branch
1234                  * would be rather costly for this rare event (the direct
1235                  * update of a branch) to be worth it.  So let's cheat and
1236                  * check with HEAD only which should cover 99% of all usage
1237                  * scenarios (even 100% of the default ones).
1238                  */
1239                 unsigned char head_sha1[20];
1240                 int head_flag;
1241                 const char *head_ref;
1242                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1243                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1244                     !strcmp(head_ref, lock->ref_name))
1245                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1246         }
1247         if (commit_ref(lock)) {
1248                 error("Couldn't set %s", lock->ref_name);
1249                 unlock_ref(lock);
1250                 return -1;
1251         }
1252         unlock_ref(lock);
1253         return 0;
1254 }
1255
1256 int create_symref(const char *ref_target, const char *refs_heads_master,
1257                   const char *logmsg)
1258 {
1259         const char *lockpath;
1260         char ref[1000];
1261         int fd, len, written;
1262         char *git_HEAD = xstrdup(git_path("%s", ref_target));
1263         unsigned char old_sha1[20], new_sha1[20];
1264
1265         if (logmsg && read_ref(ref_target, old_sha1))
1266                 hashclr(old_sha1);
1267
1268         if (safe_create_leading_directories(git_HEAD) < 0)
1269                 return error("unable to create directory for %s", git_HEAD);
1270
1271 #ifndef NO_SYMLINK_HEAD
1272         if (prefer_symlink_refs) {
1273                 unlink(git_HEAD);
1274                 if (!symlink(refs_heads_master, git_HEAD))
1275                         goto done;
1276                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1277         }
1278 #endif
1279
1280         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1281         if (sizeof(ref) <= len) {
1282                 error("refname too long: %s", refs_heads_master);
1283                 goto error_free_return;
1284         }
1285         lockpath = mkpath("%s.lock", git_HEAD);
1286         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1287         if (fd < 0) {
1288                 error("Unable to open %s for writing", lockpath);
1289                 goto error_free_return;
1290         }
1291         written = write_in_full(fd, ref, len);
1292         if (close(fd) != 0 || written != len) {
1293                 error("Unable to write to %s", lockpath);
1294                 goto error_unlink_return;
1295         }
1296         if (rename(lockpath, git_HEAD) < 0) {
1297                 error("Unable to create %s", git_HEAD);
1298                 goto error_unlink_return;
1299         }
1300         if (adjust_shared_perm(git_HEAD)) {
1301                 error("Unable to fix permissions on %s", lockpath);
1302         error_unlink_return:
1303                 unlink(lockpath);
1304         error_free_return:
1305                 free(git_HEAD);
1306                 return -1;
1307         }
1308
1309 #ifndef NO_SYMLINK_HEAD
1310         done:
1311 #endif
1312         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1313                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1314
1315         free(git_HEAD);
1316         return 0;
1317 }
1318
1319 static char *ref_msg(const char *line, const char *endp)
1320 {
1321         const char *ep;
1322         line += 82;
1323         ep = memchr(line, '\n', endp - line);
1324         if (!ep)
1325                 ep = endp;
1326         return xmemdupz(line, ep - line);
1327 }
1328
1329 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)
1330 {
1331         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1332         char *tz_c;
1333         int logfd, tz, reccnt = 0;
1334         struct stat st;
1335         unsigned long date;
1336         unsigned char logged_sha1[20];
1337         void *log_mapped;
1338         size_t mapsz;
1339
1340         logfile = git_path("logs/%s", ref);
1341         logfd = open(logfile, O_RDONLY, 0);
1342         if (logfd < 0)
1343                 die("Unable to read log %s: %s", logfile, strerror(errno));
1344         fstat(logfd, &st);
1345         if (!st.st_size)
1346                 die("Log %s is empty.", logfile);
1347         mapsz = xsize_t(st.st_size);
1348         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1349         logdata = log_mapped;
1350         close(logfd);
1351
1352         lastrec = NULL;
1353         rec = logend = logdata + st.st_size;
1354         while (logdata < rec) {
1355                 reccnt++;
1356                 if (logdata < rec && *(rec-1) == '\n')
1357                         rec--;
1358                 lastgt = NULL;
1359                 while (logdata < rec && *(rec-1) != '\n') {
1360                         rec--;
1361                         if (*rec == '>')
1362                                 lastgt = rec;
1363                 }
1364                 if (!lastgt)
1365                         die("Log %s is corrupt.", logfile);
1366                 date = strtoul(lastgt + 1, &tz_c, 10);
1367                 if (date <= at_time || cnt == 0) {
1368                         tz = strtoul(tz_c, NULL, 10);
1369                         if (msg)
1370                                 *msg = ref_msg(rec, logend);
1371                         if (cutoff_time)
1372                                 *cutoff_time = date;
1373                         if (cutoff_tz)
1374                                 *cutoff_tz = tz;
1375                         if (cutoff_cnt)
1376                                 *cutoff_cnt = reccnt - 1;
1377                         if (lastrec) {
1378                                 if (get_sha1_hex(lastrec, logged_sha1))
1379                                         die("Log %s is corrupt.", logfile);
1380                                 if (get_sha1_hex(rec + 41, sha1))
1381                                         die("Log %s is corrupt.", logfile);
1382                                 if (hashcmp(logged_sha1, sha1)) {
1383                                         fprintf(stderr,
1384                                                 "warning: Log %s has gap after %s.\n",
1385                                                 logfile, show_date(date, tz, DATE_RFC2822));
1386                                 }
1387                         }
1388                         else if (date == at_time) {
1389                                 if (get_sha1_hex(rec + 41, sha1))
1390                                         die("Log %s is corrupt.", logfile);
1391                         }
1392                         else {
1393                                 if (get_sha1_hex(rec + 41, logged_sha1))
1394                                         die("Log %s is corrupt.", logfile);
1395                                 if (hashcmp(logged_sha1, sha1)) {
1396                                         fprintf(stderr,
1397                                                 "warning: Log %s unexpectedly ended on %s.\n",
1398                                                 logfile, show_date(date, tz, DATE_RFC2822));
1399                                 }
1400                         }
1401                         munmap(log_mapped, mapsz);
1402                         return 0;
1403                 }
1404                 lastrec = rec;
1405                 if (cnt > 0)
1406                         cnt--;
1407         }
1408
1409         rec = logdata;
1410         while (rec < logend && *rec != '>' && *rec != '\n')
1411                 rec++;
1412         if (rec == logend || *rec == '\n')
1413                 die("Log %s is corrupt.", logfile);
1414         date = strtoul(rec + 1, &tz_c, 10);
1415         tz = strtoul(tz_c, NULL, 10);
1416         if (get_sha1_hex(logdata, sha1))
1417                 die("Log %s is corrupt.", logfile);
1418         if (is_null_sha1(sha1)) {
1419                 if (get_sha1_hex(logdata + 41, sha1))
1420                         die("Log %s is corrupt.", logfile);
1421         }
1422         if (msg)
1423                 *msg = ref_msg(logdata, logend);
1424         munmap(log_mapped, mapsz);
1425
1426         if (cutoff_time)
1427                 *cutoff_time = date;
1428         if (cutoff_tz)
1429                 *cutoff_tz = tz;
1430         if (cutoff_cnt)
1431                 *cutoff_cnt = reccnt;
1432         return 1;
1433 }
1434
1435 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1436 {
1437         const char *logfile;
1438         FILE *logfp;
1439         char buf[1024];
1440         int ret = 0;
1441
1442         logfile = git_path("logs/%s", ref);
1443         logfp = fopen(logfile, "r");
1444         if (!logfp)
1445                 return -1;
1446         while (fgets(buf, sizeof(buf), logfp)) {
1447                 unsigned char osha1[20], nsha1[20];
1448                 char *email_end, *message;
1449                 unsigned long timestamp;
1450                 int len, tz;
1451
1452                 /* old SP new SP name <email> SP time TAB msg LF */
1453                 len = strlen(buf);
1454                 if (len < 83 || buf[len-1] != '\n' ||
1455                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1456                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1457                     !(email_end = strchr(buf + 82, '>')) ||
1458                     email_end[1] != ' ' ||
1459                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1460                     !message || message[0] != ' ' ||
1461                     (message[1] != '+' && message[1] != '-') ||
1462                     !isdigit(message[2]) || !isdigit(message[3]) ||
1463                     !isdigit(message[4]) || !isdigit(message[5]))
1464                         continue; /* corrupt? */
1465                 email_end[1] = '\0';
1466                 tz = strtol(message + 1, NULL, 10);
1467                 if (message[6] != '\t')
1468                         message += 6;
1469                 else
1470                         message += 7;
1471                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1472                 if (ret)
1473                         break;
1474         }
1475         fclose(logfp);
1476         return ret;
1477 }
1478
1479 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1480 {
1481         DIR *dir = opendir(git_path("logs/%s", base));
1482         int retval = 0;
1483
1484         if (dir) {
1485                 struct dirent *de;
1486                 int baselen = strlen(base);
1487                 char *log = xmalloc(baselen + 257);
1488
1489                 memcpy(log, base, baselen);
1490                 if (baselen && base[baselen-1] != '/')
1491                         log[baselen++] = '/';
1492
1493                 while ((de = readdir(dir)) != NULL) {
1494                         struct stat st;
1495                         int namelen;
1496
1497                         if (de->d_name[0] == '.')
1498                                 continue;
1499                         namelen = strlen(de->d_name);
1500                         if (namelen > 255)
1501                                 continue;
1502                         if (has_extension(de->d_name, ".lock"))
1503                                 continue;
1504                         memcpy(log + baselen, de->d_name, namelen+1);
1505                         if (stat(git_path("logs/%s", log), &st) < 0)
1506                                 continue;
1507                         if (S_ISDIR(st.st_mode)) {
1508                                 retval = do_for_each_reflog(log, fn, cb_data);
1509                         } else {
1510                                 unsigned char sha1[20];
1511                                 if (!resolve_ref(log, sha1, 0, NULL))
1512                                         retval = error("bad ref for %s", log);
1513                                 else
1514                                         retval = fn(log, sha1, 0, cb_data);
1515                         }
1516                         if (retval)
1517                                 break;
1518                 }
1519                 free(log);
1520                 closedir(dir);
1521         }
1522         else if (*base)
1523                 return errno;
1524         return retval;
1525 }
1526
1527 int for_each_reflog(each_ref_fn fn, void *cb_data)
1528 {
1529         return do_for_each_reflog("", fn, cb_data);
1530 }
1531
1532 int update_ref(const char *action, const char *refname,
1533                 const unsigned char *sha1, const unsigned char *oldval,
1534                 int flags, enum action_on_err onerr)
1535 {
1536         static struct ref_lock *lock;
1537         lock = lock_any_ref_for_update(refname, oldval, flags);
1538         if (!lock) {
1539                 const char *str = "Cannot lock the ref '%s'.";
1540                 switch (onerr) {
1541                 case MSG_ON_ERR: error(str, refname); break;
1542                 case DIE_ON_ERR: die(str, refname); break;
1543                 case QUIET_ON_ERR: break;
1544                 }
1545                 return 1;
1546         }
1547         if (write_ref_sha1(lock, sha1, action) < 0) {
1548                 const char *str = "Cannot update the ref '%s'.";
1549                 switch (onerr) {
1550                 case MSG_ON_ERR: error(str, refname); break;
1551                 case DIE_ON_ERR: die(str, refname); break;
1552                 case QUIET_ON_ERR: break;
1553                 }
1554                 return 1;
1555         }
1556         return 0;
1557 }
1558
1559 struct ref *find_ref_by_name(struct ref *list, const char *name)
1560 {
1561         for ( ; list; list = list->next)
1562                 if (!strcmp(list->name, name))
1563                         return list;
1564         return NULL;
1565 }