refs.c

   1 #include "refs.h"
   2 #include "cache.h"
   3 #include "object.h"
   4 #include "tag.h"
   5
   6 #include <errno.h>
   7
   8 struct ref_list {
   9         struct ref_list *next;
  10         unsigned char flag; /* ISSYMREF? ISPACKED? ISPEELED? */
  11         unsigned char sha1[20];
  12         char name[FLEX_ARRAY];
  13 };
  14
  15 static const char *parse_ref_line(char *line, unsigned char *sha1, int *flag)
  16 {
  17         /*
  18          * 42: the answer to everything.
  19          *
  20          * In this case, it happens to be the answer to
  21          *  40 (length of sha1 hex representation)
  22          *  +1 (space in between hex and name)
  23          *  +1 (newline at the end of the line)
  24          */
  25         int len = strlen(line) - 42;
  26         int peeled = 0;
  27
  28         if (len <= 0)
  29                 return NULL;
  30         if (get_sha1_hex(line, sha1) < 0)
  31                 return NULL;
  32         if (!isspace(line[40]))
  33                 return NULL;
  34         line += 41;
  35
  36         if (isspace(*line)) {
  37                 /* "SHA-1 SP SP refs/tags/tagname^{} LF"? */
  38                 line++;
  39                 len--;
  40                 peeled = 1;
  41         }
  42         if (line[len] != '\n')
  43                 return NULL;
  44         line[len] = 0;
  45
  46         if (peeled && (len < 3 || strcmp(line + len - 3, "^{}")))
  47                 return NULL;
  48
  49         if (!peeled)
  50                 *flag &= ~REF_ISPEELED;
  51         else
  52                 *flag |= REF_ISPEELED;
  53         return line;
  54 }
  55
  56 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  57                                 int flag, struct ref_list *list)
  58 {
  59         int len;
  60         struct ref_list **p = &list, *entry;
  61
  62         /* Find the place to insert the ref into.. */
  63         while ((entry = *p) != NULL) {
  64                 int cmp = strcmp(entry->name, name);
  65                 if (cmp > 0)
  66                         break;
  67
  68                 /* Same as existing entry? */
  69                 if (!cmp)
  70                         return list;
  71                 p = &entry->next;
  72         }
  73
  74         /* Allocate it and add it in.. */
  75         len = strlen(name) + 1;
  76         entry = xmalloc(sizeof(struct ref_list) + len);
  77         hashcpy(entry->sha1, sha1);
  78         memcpy(entry->name, name, len);
  79         entry->flag = flag;
  80         entry->next = *p;
  81         *p = entry;
  82         return list;
  83 }
  84
  85 /*
  86  * Future: need to be in "struct repository"
  87  * when doing a full libification.
  88  */
  89 struct cached_refs {
  90         char did_loose;
  91         char did_packed;
  92         struct ref_list *loose;
  93         struct ref_list *packed;
  94 } cached_refs;
  95
  96 static void free_ref_list(struct ref_list *list)
  97 {
  98         struct ref_list *next;
  99         for ( ; list; list = next) {
 100                 next = list->next;
 101                 free(list);
 102         }
 103 }
 104
 105 static void invalidate_cached_refs(void)
 106 {
 107         struct cached_refs *ca = &cached_refs;
 108
 109         if (ca->did_loose && ca->loose)
 110                 free_ref_list(ca->loose);
 111         if (ca->did_packed && ca->packed)
 112                 free_ref_list(ca->packed);
 113         ca->loose = ca->packed = NULL;
 114         ca->did_loose = ca->did_packed = 0;
 115 }
 116
 117 static struct ref_list *get_packed_refs(void)
 118 {
 119         if (!cached_refs.did_packed) {
 120                 struct ref_list *refs = NULL;
 121                 FILE *f = fopen(git_path("packed-refs"), "r");
 122                 if (f) {
 123                         struct ref_list *list = NULL;
 124                         char refline[PATH_MAX];
 125                         while (fgets(refline, sizeof(refline), f)) {
 126                                 unsigned char sha1[20];
 127                                 int flag = REF_ISPACKED;
 128                                 const char *name =
 129                                         parse_ref_line(refline, sha1, &flag);
 130                                 if (!name)
 131                                         continue;
 132                                 list = add_ref(name, sha1, flag, list);
 133                         }
 134                         fclose(f);
 135                         refs = list;
 136                 }
 137                 cached_refs.packed = refs;
 138                 cached_refs.did_packed = 1;
 139         }
 140         return cached_refs.packed;
 141 }
 142
 143 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 144 {
 145         DIR *dir = opendir(git_path("%s", base));
 146
 147         if (dir) {
 148                 struct dirent *de;
 149                 int baselen = strlen(base);
 150                 char *ref = xmalloc(baselen + 257);
 151
 152                 memcpy(ref, base, baselen);
 153                 if (baselen && base[baselen-1] != '/')
 154                         ref[baselen++] = '/';
 155
 156                 while ((de = readdir(dir)) != NULL) {
 157                         unsigned char sha1[20];
 158                         struct stat st;
 159                         int flag;
 160                         int namelen;
 161
 162                         if (de->d_name[0] == '.')
 163                                 continue;
 164                         namelen = strlen(de->d_name);
 165                         if (namelen > 255)
 166                                 continue;
 167                         if (has_extension(de->d_name, ".lock"))
 168                                 continue;
 169                         memcpy(ref + baselen, de->d_name, namelen+1);
 170                         if (stat(git_path("%s", ref), &st) < 0)
 171                                 continue;
 172                         if (S_ISDIR(st.st_mode)) {
 173                                 list = get_ref_dir(ref, list);
 174                                 continue;
 175                         }
 176                         if (!resolve_ref(ref, sha1, 1, &flag)) {
 177                                 error("%s points nowhere!", ref);
 178                                 continue;
 179                         }
 180                         list = add_ref(ref, sha1, flag, list);
 181                 }
 182                 free(ref);
 183                 closedir(dir);
 184         }
 185         return list;
 186 }
 187
 188 static struct ref_list *get_loose_refs(void)
 189 {
 190         if (!cached_refs.did_loose) {
 191                 cached_refs.loose = get_ref_dir("refs", NULL);
 192                 cached_refs.did_loose = 1;
 193         }
 194         return cached_refs.loose;
 195 }
 196
 197 /* We allow "recursive" symbolic refs. Only within reason, though */
 198 #define MAXDEPTH 5
 199
 200 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 201 {
 202         int depth = MAXDEPTH, len;
 203         char buffer[256];
 204         static char ref_buffer[256];
 205
 206         if (flag)
 207                 *flag = 0;
 208
 209         for (;;) {
 210                 const char *path = git_path("%s", ref);
 211                 struct stat st;
 212                 char *buf;
 213                 int fd;
 214
 215                 if (--depth < 0)
 216                         return NULL;
 217
 218                 /* Special case: non-existing file.
 219                  * Not having the refs/heads/new-branch is OK
 220                  * if we are writing into it, so is .git/HEAD
 221                  * that points at refs/heads/master still to be
 222                  * born.  It is NOT OK if we are resolving for
 223                  * reading.
 224                  */
 225                 if (lstat(path, &st) < 0) {
 226                         struct ref_list *list = get_packed_refs();
 227                         while (list) {
 228                                 if (!(list->flag & REF_ISPEELED) &&
 229                                     !strcmp(ref, list->name)) {
 230                                         hashcpy(sha1, list->sha1);
 231                                         if (flag)
 232                                                 *flag |= REF_ISPACKED;
 233                                         return ref;
 234                                 }
 235                                 list = list->next;
 236                         }
 237                         if (reading || errno != ENOENT)
 238                                 return NULL;
 239                         hashclr(sha1);
 240                         return ref;
 241                 }
 242
 243                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 244                 if (S_ISLNK(st.st_mode)) {
 245                         len = readlink(path, buffer, sizeof(buffer)-1);
 246                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 247                                 buffer[len] = 0;
 248                                 strcpy(ref_buffer, buffer);
 249                                 ref = ref_buffer;
 250                                 if (flag)
 251                                         *flag |= REF_ISSYMREF;
 252                                 continue;
 253                         }
 254                 }
 255
 256                 /* Is it a directory? */
 257                 if (S_ISDIR(st.st_mode)) {
 258                         errno = EISDIR;
 259                         return NULL;
 260                 }
 261
 262                 /*
 263                  * Anything else, just open it and try to use it as
 264                  * a ref
 265                  */
 266                 fd = open(path, O_RDONLY);
 267                 if (fd < 0)
 268                         return NULL;
 269                 len = read(fd, buffer, sizeof(buffer)-1);
 270                 close(fd);
 271
 272                 /*
 273                  * Is it a symbolic ref?
 274                  */
 275                 if (len < 4 || memcmp("ref:", buffer, 4))
 276                         break;
 277                 buf = buffer + 4;
 278                 len -= 4;
 279                 while (len && isspace(*buf))
 280                         buf++, len--;
 281                 while (len && isspace(buf[len-1]))
 282                         len--;
 283                 buf[len] = 0;
 284                 memcpy(ref_buffer, buf, len + 1);
 285                 ref = ref_buffer;
 286                 if (flag)
 287                         *flag |= REF_ISSYMREF;
 288         }
 289         if (len < 40 || get_sha1_hex(buffer, sha1))
 290                 return NULL;
 291         return ref;
 292 }
 293
 294 int create_symref(const char *ref_target, const char *refs_heads_master)
 295 {
 296         const char *lockpath;
 297         char ref[1000];
 298         int fd, len, written;
 299         const char *git_HEAD = git_path("%s", ref_target);
 300
 301 #ifndef NO_SYMLINK_HEAD
 302         if (prefer_symlink_refs) {
 303                 unlink(git_HEAD);
 304                 if (!symlink(refs_heads_master, git_HEAD))
 305                         return 0;
 306                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 307         }
 308 #endif
 309
 310         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 311         if (sizeof(ref) <= len) {
 312                 error("refname too long: %s", refs_heads_master);
 313                 return -1;
 314         }
 315         lockpath = mkpath("%s.lock", git_HEAD);
 316         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
 317         written = write(fd, ref, len);
 318         close(fd);
 319         if (written != len) {
 320                 unlink(lockpath);
 321                 error("Unable to write to %s", lockpath);
 322                 return -2;
 323         }
 324         if (rename(lockpath, git_HEAD) < 0) {
 325                 unlink(lockpath);
 326                 error("Unable to create %s", git_HEAD);
 327                 return -3;
 328         }
 329         if (adjust_shared_perm(git_HEAD)) {
 330                 unlink(lockpath);
 331                 error("Unable to fix permissions on %s", lockpath);
 332                 return -4;
 333         }
 334         return 0;
 335 }
 336
 337 int read_ref(const char *ref, unsigned char *sha1)
 338 {
 339         if (resolve_ref(ref, sha1, 1, NULL))
 340                 return 0;
 341         return -1;
 342 }
 343
 344 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 345                       void *cb_data, struct ref_list *entry)
 346 {
 347         if (strncmp(base, entry->name, trim))
 348                 return 0;
 349         if (is_null_sha1(entry->sha1))
 350                 return 0;
 351         if (entry->flag & REF_ISPEELED)
 352                 return 0;
 353         if (!has_sha1_file(entry->sha1)) {
 354                 error("%s does not point to a valid object!", entry->name);
 355                 return 0;
 356         }
 357         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 358 }
 359
 360 int peel_ref(const char *ref, unsigned char *sha1)
 361 {
 362         int flag;
 363         unsigned char base[20];
 364         struct object *o;
 365
 366         if (!resolve_ref(ref, base, 1, &flag))
 367                 return -1;
 368
 369         if ((flag & REF_ISPACKED)) {
 370                 struct ref_list *list = get_packed_refs();
 371                 int len = strlen(ref);
 372
 373                 while (list) {
 374                         if ((list->flag & REF_ISPEELED) &&
 375                             !strncmp(list->name, ref, len) &&
 376                             strlen(list->name) == len + 3 &&
 377                             !strcmp(list->name + len, "^{}")) {
 378                                 hashcpy(sha1, list->sha1);
 379                                 return 0;
 380                         }
 381                         list = list->next;
 382                 }
 383                 /* older pack-refs did not leave peeled ones in */
 384         }
 385
 386         /* otherwise ... */
 387         o = parse_object(base);
 388         if (o->type == OBJ_TAG) {
 389                 o = deref_tag(o, ref, 0);
 390                 if (o) {
 391                         hashcpy(sha1, o->sha1);
 392                         return 0;
 393                 }
 394         }
 395         return -1;
 396 }
 397
 398 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 399                            void *cb_data)
 400 {
 401         int retval;
 402         struct ref_list *packed = get_packed_refs();
 403         struct ref_list *loose = get_loose_refs();
 404
 405         while (packed && loose) {
 406                 struct ref_list *entry;
 407                 int cmp = strcmp(packed->name, loose->name);
 408                 if (!cmp) {
 409                         packed = packed->next;
 410                         continue;
 411                 }
 412                 if (cmp > 0) {
 413                         entry = loose;
 414                         loose = loose->next;
 415                 } else {
 416                         entry = packed;
 417                         packed = packed->next;
 418                 }
 419                 retval = do_one_ref(base, fn, trim, cb_data, entry);
 420                 if (retval)
 421                         return retval;
 422         }
 423
 424         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 425                 retval = do_one_ref(base, fn, trim, cb_data, packed);
 426                 if (retval)
 427                         return retval;
 428         }
 429         return 0;
 430 }
 431
 432 int head_ref(each_ref_fn fn, void *cb_data)
 433 {
 434         unsigned char sha1[20];
 435         int flag;
 436
 437         if (resolve_ref("HEAD", sha1, 1, &flag))
 438                 return fn("HEAD", sha1, flag, cb_data);
 439         return 0;
 440 }
 441
 442 int for_each_ref(each_ref_fn fn, void *cb_data)
 443 {
 444         return do_for_each_ref("refs/", fn, 0, cb_data);
 445 }
 446
 447 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 448 {
 449         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 450 }
 451
 452 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 453 {
 454         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 455 }
 456
 457 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 458 {
 459         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 460 }
 461
 462 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
 463  * caller should do resolve_ref or read_ref like everybody else.  Or
 464  * maybe everybody else should use get_ref_sha1() instead of doing
 465  * read_ref().
 466  */
 467 int get_ref_sha1(const char *ref, unsigned char *sha1)
 468 {
 469         if (check_ref_format(ref))
 470                 return -1;
 471         return read_ref(mkpath("refs/%s", ref), sha1);
 472 }
 473
 474 /*
 475  * Make sure "ref" is something reasonable to have under ".git/refs/";
 476  * We do not like it if:
 477  *
 478  * - any path component of it begins with ".", or
 479  * - it has double dots "..", or
 480  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 481  * - it ends with a "/".
 482  */
 483
 484 static inline int bad_ref_char(int ch)
 485 {
 486         return (((unsigned) ch) <= ' ' ||
 487                 ch == '~' || ch == '^' || ch == ':' ||
 488                 /* 2.13 Pattern Matching Notation */
 489                 ch == '?' || ch == '*' || ch == '[');
 490 }
 491
 492 int check_ref_format(const char *ref)
 493 {
 494         int ch, level;
 495         const char *cp = ref;
 496
 497         level = 0;
 498         while (1) {
 499                 while ((ch = *cp++) == '/')
 500                         ; /* tolerate duplicated slashes */
 501                 if (!ch)
 502                         return -1; /* should not end with slashes */
 503
 504                 /* we are at the beginning of the path component */
 505                 if (ch == '.' || bad_ref_char(ch))
 506                         return -1;
 507
 508                 /* scan the rest of the path component */
 509                 while ((ch = *cp++) != 0) {
 510                         if (bad_ref_char(ch))
 511                                 return -1;
 512                         if (ch == '/')
 513                                 break;
 514                         if (ch == '.' && *cp == '.')
 515                                 return -1;
 516                 }
 517                 level++;
 518                 if (!ch) {
 519                         if (level < 2)
 520                                 return -1; /* at least of form "heads/blah" */
 521                         return 0;
 522                 }
 523         }
 524 }
 525
 526 static struct ref_lock *verify_lock(struct ref_lock *lock,
 527         const unsigned char *old_sha1, int mustexist)
 528 {
 529         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 530                 error("Can't verify ref %s", lock->ref_name);
 531                 unlock_ref(lock);
 532                 return NULL;
 533         }
 534         if (hashcmp(lock->old_sha1, old_sha1)) {
 535                 error("Ref %s is at %s but expected %s", lock->ref_name,
 536                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 537                 unlock_ref(lock);
 538                 return NULL;
 539         }
 540         return lock;
 541 }
 542
 543 static int remove_empty_dir_recursive(char *path, int len)
 544 {
 545         DIR *dir = opendir(path);
 546         struct dirent *e;
 547         int ret = 0;
 548
 549         if (!dir)
 550                 return -1;
 551         if (path[len-1] != '/')
 552                 path[len++] = '/';
 553         while ((e = readdir(dir)) != NULL) {
 554                 struct stat st;
 555                 int namlen;
 556                 if ((e->d_name[0] == '.') &&
 557                     ((e->d_name[1] == 0) ||
 558                      ((e->d_name[1] == '.') && e->d_name[2] == 0)))
 559                         continue; /* "." and ".." */
 560
 561                 namlen = strlen(e->d_name);
 562                 if ((len + namlen < PATH_MAX) &&
 563                     strcpy(path + len, e->d_name) &&
 564                     !lstat(path, &st) &&
 565                     S_ISDIR(st.st_mode) &&
 566                     !remove_empty_dir_recursive(path, len + namlen))
 567                         continue; /* happy */
 568
 569                 /* path too long, stat fails, or non-directory still exists */
 570                 ret = -1;
 571                 break;
 572         }
 573         closedir(dir);
 574         if (!ret) {
 575                 path[len] = 0;
 576                 ret = rmdir(path);
 577         }
 578         return ret;
 579 }
 580
 581 static int remove_empty_directories(char *file)
 582 {
 583         /* we want to create a file but there is a directory there;
 584          * if that is an empty directory (or a directory that contains
 585          * only empty directories), remove them.
 586          */
 587         char path[PATH_MAX];
 588         int len = strlen(file);
 589
 590         if (len >= PATH_MAX) /* path too long ;-) */
 591                 return -1;
 592         strcpy(path, file);
 593         return remove_empty_dir_recursive(path, len);
 594 }
 595
 596 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int *flag)
 597 {
 598         char *ref_file;
 599         const char *orig_ref = ref;
 600         struct ref_lock *lock;
 601         struct stat st;
 602         int last_errno = 0;
 603         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 604
 605         lock = xcalloc(1, sizeof(struct ref_lock));
 606         lock->lock_fd = -1;
 607
 608         ref = resolve_ref(ref, lock->old_sha1, mustexist, flag);
 609         if (!ref && errno == EISDIR) {
 610                 /* we are trying to lock foo but we used to
 611                  * have foo/bar which now does not exist;
 612                  * it is normal for the empty directory 'foo'
 613                  * to remain.
 614                  */
 615                 ref_file = git_path("%s", orig_ref);
 616                 if (remove_empty_directories(ref_file)) {
 617                         last_errno = errno;
 618                         error("there are still refs under '%s'", orig_ref);
 619                         goto error_return;
 620                 }
 621                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, flag);
 622         }
 623         if (!ref) {
 624                 last_errno = errno;
 625                 error("unable to resolve reference %s: %s",
 626                         orig_ref, strerror(errno));
 627                 goto error_return;
 628         }
 629         if (is_null_sha1(lock->old_sha1)) {
 630                 /* The ref did not exist and we are creating it.
 631                  * Make sure there is no existing ref that is packed
 632                  * whose name begins with our refname, nor a ref whose
 633                  * name is a proper prefix of our refname.
 634                  */
 635                 int namlen = strlen(ref); /* e.g. 'foo/bar' */
 636                 struct ref_list *list = get_packed_refs();
 637                 while (list) {
 638                         /* list->name could be 'foo' or 'foo/bar/baz' */
 639                         int len = strlen(list->name);
 640                         int cmplen = (namlen < len) ? namlen : len;
 641                         const char *lead = (namlen < len) ? list->name : ref;
 642
 643                         if (!strncmp(ref, list->name, cmplen) &&
 644                             lead[cmplen] == '/') {
 645                                 error("'%s' exists; cannot create '%s'",
 646                                       list->name, ref);
 647                                 goto error_return;
 648                         }
 649                         list = list->next;
 650                 }
 651         }
 652
 653         lock->lk = xcalloc(1, sizeof(struct lock_file));
 654
 655         lock->ref_name = xstrdup(ref);
 656         lock->log_file = xstrdup(git_path("logs/%s", ref));
 657         ref_file = git_path("%s", ref);
 658         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
 659
 660         if (safe_create_leading_directories(ref_file)) {
 661                 last_errno = errno;
 662                 error("unable to create directory for %s", ref_file);
 663                 goto error_return;
 664         }
 665         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 666
 667         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 668
 669  error_return:
 670         unlock_ref(lock);
 671         errno = last_errno;
 672         return NULL;
 673 }
 674
 675 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 676 {
 677         char refpath[PATH_MAX];
 678         if (check_ref_format(ref))
 679                 return NULL;
 680         strcpy(refpath, mkpath("refs/%s", ref));
 681         return lock_ref_sha1_basic(refpath, old_sha1, NULL);
 682 }
 683
 684 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
 685 {
 686         return lock_ref_sha1_basic(ref, old_sha1, NULL);
 687 }
 688
 689 static struct lock_file packlock;
 690
 691 static int repack_without_ref(const char *refname)
 692 {
 693         struct ref_list *list, *packed_ref_list;
 694         int fd;
 695         int found = 0;
 696
 697         packed_ref_list = get_packed_refs();
 698         for (list = packed_ref_list; list; list = list->next) {
 699                 if (!strcmp(refname, list->name)) {
 700                         found = 1;
 701                         break;
 702                 }
 703         }
 704         if (!found)
 705                 return 0;
 706         memset(&packlock, 0, sizeof(packlock));
 707         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 708         if (fd < 0)
 709                 return error("cannot delete '%s' from packed refs", refname);
 710
 711         for (list = packed_ref_list; list; list = list->next) {
 712                 char line[PATH_MAX + 100];
 713                 int len;
 714
 715                 if (!strcmp(refname, list->name))
 716                         continue;
 717                 len = snprintf(line, sizeof(line), "%s %s\n",
 718                                sha1_to_hex(list->sha1), list->name);
 719                 /* this should not happen but just being defensive */
 720                 if (len > sizeof(line))
 721                         die("too long a refname '%s'", list->name);
 722                 write_or_die(fd, line, len);
 723         }
 724         return commit_lock_file(&packlock);
 725 }
 726
 727 int delete_ref(const char *refname, unsigned char *sha1)
 728 {
 729         struct ref_lock *lock;
 730         int err, i, ret = 0, flag = 0;
 731
 732         lock = lock_ref_sha1_basic(refname, sha1, &flag);
 733         if (!lock)
 734                 return 1;
 735         if (!(flag & REF_ISPACKED)) {
 736                 /* loose */
 737                 i = strlen(lock->lk->filename) - 5; /* .lock */
 738                 lock->lk->filename[i] = 0;
 739                 err = unlink(lock->lk->filename);
 740                 if (err) {
 741                         ret = 1;
 742                         error("unlink(%s) failed: %s",
 743                               lock->lk->filename, strerror(errno));
 744                 }
 745                 lock->lk->filename[i] = '.';
 746         }
 747         /* removing the loose one could have resurrected an earlier
 748          * packed one.  Also, if it was not loose we need to repack
 749          * without it.
 750          */
 751         ret |= repack_without_ref(refname);
 752
 753         err = unlink(lock->log_file);
 754         if (err && errno != ENOENT)
 755                 fprintf(stderr, "warning: unlink(%s) failed: %s",
 756                         lock->log_file, strerror(errno));
 757         invalidate_cached_refs();
 758         unlock_ref(lock);
 759         return ret;
 760 }
 761
 762 void unlock_ref(struct ref_lock *lock)
 763 {
 764         if (lock->lock_fd >= 0) {
 765                 close(lock->lock_fd);
 766                 /* Do not free lock->lk -- atexit() still looks at them */
 767                 if (lock->lk)
 768                         rollback_lock_file(lock->lk);
 769         }
 770         free(lock->ref_name);
 771         free(lock->log_file);
 772         free(lock);
 773 }
 774
 775 static int log_ref_write(struct ref_lock *lock,
 776         const unsigned char *sha1, const char *msg)
 777 {
 778         int logfd, written, oflags = O_APPEND | O_WRONLY;
 779         unsigned maxlen, len;
 780         char *logrec;
 781         const char *committer;
 782
 783         if (log_all_ref_updates &&
 784             !strncmp(lock->ref_name, "refs/heads/", 11)) {
 785                 if (safe_create_leading_directories(lock->log_file) < 0)
 786                         return error("unable to create directory for %s",
 787                                 lock->log_file);
 788                 oflags |= O_CREAT;
 789         }
 790
 791         logfd = open(lock->log_file, oflags, 0666);
 792         if (logfd < 0) {
 793                 if (!(oflags & O_CREAT) && errno == ENOENT)
 794                         return 0;
 795
 796                 if ((oflags & O_CREAT) && errno == EISDIR) {
 797                         if (remove_empty_directories(lock->log_file)) {
 798                                 return error("There are still logs under '%s'",
 799                                              lock->log_file);
 800                         }
 801                         logfd = open(lock->log_file, oflags, 0666);
 802                 }
 803
 804                 if (logfd < 0)
 805                         return error("Unable to append to %s: %s",
 806                                      lock->log_file, strerror(errno));
 807         }
 808
 809         committer = git_committer_info(1);
 810         if (msg) {
 811                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 812                 logrec = xmalloc(maxlen);
 813                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 814                         sha1_to_hex(lock->old_sha1),
 815                         sha1_to_hex(sha1),
 816                         committer,
 817                         msg);
 818         }
 819         else {
 820                 maxlen = strlen(committer) + 2*40 + 4;
 821                 logrec = xmalloc(maxlen);
 822                 len = snprintf(logrec, maxlen, "%s %s %s\n",
 823                         sha1_to_hex(lock->old_sha1),
 824                         sha1_to_hex(sha1),
 825                         committer);
 826         }
 827         written = len <= maxlen ? write(logfd, logrec, len) : -1;
 828         free(logrec);
 829         close(logfd);
 830         if (written != len)
 831                 return error("Unable to append to %s", lock->log_file);
 832         return 0;
 833 }
 834
 835 int write_ref_sha1(struct ref_lock *lock,
 836         const unsigned char *sha1, const char *logmsg)
 837 {
 838         static char term = '\n';
 839
 840         if (!lock)
 841                 return -1;
 842         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 843                 unlock_ref(lock);
 844                 return 0;
 845         }
 846         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 847             write(lock->lock_fd, &term, 1) != 1
 848                 || close(lock->lock_fd) < 0) {
 849                 error("Couldn't write %s", lock->lk->filename);
 850                 unlock_ref(lock);
 851                 return -1;
 852         }
 853         invalidate_cached_refs();
 854         if (log_ref_write(lock, sha1, logmsg) < 0) {
 855                 unlock_ref(lock);
 856                 return -1;
 857         }
 858         if (commit_lock_file(lock->lk)) {
 859                 error("Couldn't set %s", lock->ref_name);
 860                 unlock_ref(lock);
 861                 return -1;
 862         }
 863         lock->lock_fd = -1;
 864         unlock_ref(lock);
 865         return 0;
 866 }
 867
 868 int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1)
 869 {
 870         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 871         char *tz_c;
 872         int logfd, tz;
 873         struct stat st;
 874         unsigned long date;
 875         unsigned char logged_sha1[20];
 876
 877         logfile = git_path("logs/%s", ref);
 878         logfd = open(logfile, O_RDONLY, 0);
 879         if (logfd < 0)
 880                 die("Unable to read log %s: %s", logfile, strerror(errno));
 881         fstat(logfd, &st);
 882         if (!st.st_size)
 883                 die("Log %s is empty.", logfile);
 884         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 885         close(logfd);
 886
 887         lastrec = NULL;
 888         rec = logend = logdata + st.st_size;
 889         while (logdata < rec) {
 890                 if (logdata < rec && *(rec-1) == '\n')
 891                         rec--;
 892                 lastgt = NULL;
 893                 while (logdata < rec && *(rec-1) != '\n') {
 894                         rec--;
 895                         if (*rec == '>')
 896                                 lastgt = rec;
 897                 }
 898                 if (!lastgt)
 899                         die("Log %s is corrupt.", logfile);
 900                 date = strtoul(lastgt + 1, &tz_c, 10);
 901                 if (date <= at_time || cnt == 0) {
 902                         if (lastrec) {
 903                                 if (get_sha1_hex(lastrec, logged_sha1))
 904                                         die("Log %s is corrupt.", logfile);
 905                                 if (get_sha1_hex(rec + 41, sha1))
 906                                         die("Log %s is corrupt.", logfile);
 907                                 if (hashcmp(logged_sha1, sha1)) {
 908                                         tz = strtoul(tz_c, NULL, 10);
 909                                         fprintf(stderr,
 910                                                 "warning: Log %s has gap after %s.\n",
 911                                                 logfile, show_rfc2822_date(date, tz));
 912                                 }
 913                         }
 914                         else if (date == at_time) {
 915                                 if (get_sha1_hex(rec + 41, sha1))
 916                                         die("Log %s is corrupt.", logfile);
 917                         }
 918                         else {
 919                                 if (get_sha1_hex(rec + 41, logged_sha1))
 920                                         die("Log %s is corrupt.", logfile);
 921                                 if (hashcmp(logged_sha1, sha1)) {
 922                                         tz = strtoul(tz_c, NULL, 10);
 923                                         fprintf(stderr,
 924                                                 "warning: Log %s unexpectedly ended on %s.\n",
 925                                                 logfile, show_rfc2822_date(date, tz));
 926                                 }
 927                         }
 928                         munmap((void*)logdata, st.st_size);
 929                         return 0;
 930                 }
 931                 lastrec = rec;
 932                 if (cnt > 0)
 933                         cnt--;
 934         }
 935
 936         rec = logdata;
 937         while (rec < logend && *rec != '>' && *rec != '\n')
 938                 rec++;
 939         if (rec == logend || *rec == '\n')
 940                 die("Log %s is corrupt.", logfile);
 941         date = strtoul(rec + 1, &tz_c, 10);
 942         tz = strtoul(tz_c, NULL, 10);
 943         if (get_sha1_hex(logdata, sha1))
 944                 die("Log %s is corrupt.", logfile);
 945         munmap((void*)logdata, st.st_size);
 946         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 947                 logfile, show_rfc2822_date(date, tz));
 948         return 0;
 949 }