refs.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "tag.h"
   5
   6 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
   7 #define REF_KNOWS_PEELED 04
   8
   9 struct ref_list {
  10         struct ref_list *next;
  11         unsigned char flag; /* ISSYMREF? ISPACKED? */
  12         unsigned char sha1[20];
  13         unsigned char peeled[20];
  14         char name[FLEX_ARRAY];
  15 };
  16
  17 static const char *parse_ref_line(char *line, unsigned char *sha1)
  18 {
  19         /*
  20          * 42: the answer to everything.
  21          *
  22          * In this case, it happens to be the answer to
  23          *  40 (length of sha1 hex representation)
  24          *  +1 (space in between hex and name)
  25          *  +1 (newline at the end of the line)
  26          */
  27         int len = strlen(line) - 42;
  28
  29         if (len <= 0)
  30                 return NULL;
  31         if (get_sha1_hex(line, sha1) < 0)
  32                 return NULL;
  33         if (!isspace(line[40]))
  34                 return NULL;
  35         line += 41;
  36         if (isspace(*line))
  37                 return NULL;
  38         if (line[len] != '\n')
  39                 return NULL;
  40         line[len] = 0;
  41
  42         return line;
  43 }
  44
  45 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  46                                 int flag, struct ref_list *list,
  47                                 struct ref_list **new_entry)
  48 {
  49         int len;
  50         struct ref_list **p = &list, *entry;
  51
  52         /* Find the place to insert the ref into.. */
  53         while ((entry = *p) != NULL) {
  54                 int cmp = strcmp(entry->name, name);
  55                 if (cmp > 0)
  56                         break;
  57
  58                 /* Same as existing entry? */
  59                 if (!cmp) {
  60                         if (new_entry)
  61                                 *new_entry = entry;
  62                         return list;
  63                 }
  64                 p = &entry->next;
  65         }
  66
  67         /* Allocate it and add it in.. */
  68         len = strlen(name) + 1;
  69         entry = xmalloc(sizeof(struct ref_list) + len);
  70         hashcpy(entry->sha1, sha1);
  71         hashclr(entry->peeled);
  72         memcpy(entry->name, name, len);
  73         entry->flag = flag;
  74         entry->next = *p;
  75         *p = entry;
  76         if (new_entry)
  77                 *new_entry = entry;
  78         return list;
  79 }
  80
  81 /*
  82  * Future: need to be in "struct repository"
  83  * when doing a full libification.
  84  */
  85 struct cached_refs {
  86         char did_loose;
  87         char did_packed;
  88         struct ref_list *loose;
  89         struct ref_list *packed;
  90 } cached_refs;
  91
  92 static void free_ref_list(struct ref_list *list)
  93 {
  94         struct ref_list *next;
  95         for ( ; list; list = next) {
  96                 next = list->next;
  97                 free(list);
  98         }
  99 }
 100
 101 static void invalidate_cached_refs(void)
 102 {
 103         struct cached_refs *ca = &cached_refs;
 104
 105         if (ca->did_loose && ca->loose)
 106                 free_ref_list(ca->loose);
 107         if (ca->did_packed && ca->packed)
 108                 free_ref_list(ca->packed);
 109         ca->loose = ca->packed = NULL;
 110         ca->did_loose = ca->did_packed = 0;
 111 }
 112
 113 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 114 {
 115         struct ref_list *list = NULL;
 116         struct ref_list *last = NULL;
 117         char refline[PATH_MAX];
 118         int flag = REF_ISPACKED;
 119
 120         while (fgets(refline, sizeof(refline), f)) {
 121                 unsigned char sha1[20];
 122                 const char *name;
 123                 static const char header[] = "# pack-refs with:";
 124
 125                 if (!strncmp(refline, header, sizeof(header)-1)) {
 126                         const char *traits = refline + sizeof(header) - 1;
 127                         if (strstr(traits, " peeled "))
 128                                 flag |= REF_KNOWS_PEELED;
 129                         /* perhaps other traits later as well */
 130                         continue;
 131                 }
 132
 133                 name = parse_ref_line(refline, sha1);
 134                 if (name) {
 135                         list = add_ref(name, sha1, flag, list, &last);
 136                         continue;
 137                 }
 138                 if (last &&
 139                     refline[0] == '^' &&
 140                     strlen(refline) == 42 &&
 141                     refline[41] == '\n' &&
 142                     !get_sha1_hex(refline + 1, sha1))
 143                         hashcpy(last->peeled, sha1);
 144         }
 145         cached_refs->packed = list;
 146 }
 147
 148 static struct ref_list *get_packed_refs(void)
 149 {
 150         if (!cached_refs.did_packed) {
 151                 FILE *f = fopen(git_path("packed-refs"), "r");
 152                 cached_refs.packed = NULL;
 153                 if (f) {
 154                         read_packed_refs(f, &cached_refs);
 155                         fclose(f);
 156                 }
 157                 cached_refs.did_packed = 1;
 158         }
 159         return cached_refs.packed;
 160 }
 161
 162 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 163 {
 164         DIR *dir = opendir(git_path("%s", base));
 165
 166         if (dir) {
 167                 struct dirent *de;
 168                 int baselen = strlen(base);
 169                 char *ref = xmalloc(baselen + 257);
 170
 171                 memcpy(ref, base, baselen);
 172                 if (baselen && base[baselen-1] != '/')
 173                         ref[baselen++] = '/';
 174
 175                 while ((de = readdir(dir)) != NULL) {
 176                         unsigned char sha1[20];
 177                         struct stat st;
 178                         int flag;
 179                         int namelen;
 180
 181                         if (de->d_name[0] == '.')
 182                                 continue;
 183                         namelen = strlen(de->d_name);
 184                         if (namelen > 255)
 185                                 continue;
 186                         if (has_extension(de->d_name, ".lock"))
 187                                 continue;
 188                         memcpy(ref + baselen, de->d_name, namelen+1);
 189                         if (stat(git_path("%s", ref), &st) < 0)
 190                                 continue;
 191                         if (S_ISDIR(st.st_mode)) {
 192                                 list = get_ref_dir(ref, list);
 193                                 continue;
 194                         }
 195                         if (!resolve_ref(ref, sha1, 1, &flag)) {
 196                                 error("%s points nowhere!", ref);
 197                                 continue;
 198                         }
 199                         list = add_ref(ref, sha1, flag, list, NULL);
 200                 }
 201                 free(ref);
 202                 closedir(dir);
 203         }
 204         return list;
 205 }
 206
 207 static struct ref_list *get_loose_refs(void)
 208 {
 209         if (!cached_refs.did_loose) {
 210                 cached_refs.loose = get_ref_dir("refs", NULL);
 211                 cached_refs.did_loose = 1;
 212         }
 213         return cached_refs.loose;
 214 }
 215
 216 /* We allow "recursive" symbolic refs. Only within reason, though */
 217 #define MAXDEPTH 5
 218
 219 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 220 {
 221         int depth = MAXDEPTH, len;
 222         char buffer[256];
 223         static char ref_buffer[256];
 224
 225         if (flag)
 226                 *flag = 0;
 227
 228         for (;;) {
 229                 const char *path = git_path("%s", ref);
 230                 struct stat st;
 231                 char *buf;
 232                 int fd;
 233
 234                 if (--depth < 0)
 235                         return NULL;
 236
 237                 /* Special case: non-existing file.
 238                  * Not having the refs/heads/new-branch is OK
 239                  * if we are writing into it, so is .git/HEAD
 240                  * that points at refs/heads/master still to be
 241                  * born.  It is NOT OK if we are resolving for
 242                  * reading.
 243                  */
 244                 if (lstat(path, &st) < 0) {
 245                         struct ref_list *list = get_packed_refs();
 246                         while (list) {
 247                                 if (!strcmp(ref, list->name)) {
 248                                         hashcpy(sha1, list->sha1);
 249                                         if (flag)
 250                                                 *flag |= REF_ISPACKED;
 251                                         return ref;
 252                                 }
 253                                 list = list->next;
 254                         }
 255                         if (reading || errno != ENOENT)
 256                                 return NULL;
 257                         hashclr(sha1);
 258                         return ref;
 259                 }
 260
 261                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 262                 if (S_ISLNK(st.st_mode)) {
 263                         len = readlink(path, buffer, sizeof(buffer)-1);
 264                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 265                                 buffer[len] = 0;
 266                                 strcpy(ref_buffer, buffer);
 267                                 ref = ref_buffer;
 268                                 if (flag)
 269                                         *flag |= REF_ISSYMREF;
 270                                 continue;
 271                         }
 272                 }
 273
 274                 /* Is it a directory? */
 275                 if (S_ISDIR(st.st_mode)) {
 276                         errno = EISDIR;
 277                         return NULL;
 278                 }
 279
 280                 /*
 281                  * Anything else, just open it and try to use it as
 282                  * a ref
 283                  */
 284                 fd = open(path, O_RDONLY);
 285                 if (fd < 0)
 286                         return NULL;
 287                 len = read(fd, buffer, sizeof(buffer)-1);
 288                 close(fd);
 289
 290                 /*
 291                  * Is it a symbolic ref?
 292                  */
 293                 if (len < 4 || memcmp("ref:", buffer, 4))
 294                         break;
 295                 buf = buffer + 4;
 296                 len -= 4;
 297                 while (len && isspace(*buf))
 298                         buf++, len--;
 299                 while (len && isspace(buf[len-1]))
 300                         len--;
 301                 buf[len] = 0;
 302                 memcpy(ref_buffer, buf, len + 1);
 303                 ref = ref_buffer;
 304                 if (flag)
 305                         *flag |= REF_ISSYMREF;
 306         }
 307         if (len < 40 || get_sha1_hex(buffer, sha1))
 308                 return NULL;
 309         return ref;
 310 }
 311
 312 int create_symref(const char *ref_target, const char *refs_heads_master)
 313 {
 314         const char *lockpath;
 315         char ref[1000];
 316         int fd, len, written;
 317         const char *git_HEAD = git_path("%s", ref_target);
 318
 319 #ifndef NO_SYMLINK_HEAD
 320         if (prefer_symlink_refs) {
 321                 unlink(git_HEAD);
 322                 if (!symlink(refs_heads_master, git_HEAD))
 323                         return 0;
 324                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 325         }
 326 #endif
 327
 328         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 329         if (sizeof(ref) <= len) {
 330                 error("refname too long: %s", refs_heads_master);
 331                 return -1;
 332         }
 333         lockpath = mkpath("%s.lock", git_HEAD);
 334         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
 335         written = write(fd, ref, len);
 336         close(fd);
 337         if (written != len) {
 338                 unlink(lockpath);
 339                 error("Unable to write to %s", lockpath);
 340                 return -2;
 341         }
 342         if (rename(lockpath, git_HEAD) < 0) {
 343                 unlink(lockpath);
 344                 error("Unable to create %s", git_HEAD);
 345                 return -3;
 346         }
 347         if (adjust_shared_perm(git_HEAD)) {
 348                 unlink(lockpath);
 349                 error("Unable to fix permissions on %s", lockpath);
 350                 return -4;
 351         }
 352         return 0;
 353 }
 354
 355 int read_ref(const char *ref, unsigned char *sha1)
 356 {
 357         if (resolve_ref(ref, sha1, 1, NULL))
 358                 return 0;
 359         return -1;
 360 }
 361
 362 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 363                       void *cb_data, struct ref_list *entry)
 364 {
 365         if (strncmp(base, entry->name, trim))
 366                 return 0;
 367         if (is_null_sha1(entry->sha1))
 368                 return 0;
 369         if (!has_sha1_file(entry->sha1)) {
 370                 error("%s does not point to a valid object!", entry->name);
 371                 return 0;
 372         }
 373         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 374 }
 375
 376 int peel_ref(const char *ref, unsigned char *sha1)
 377 {
 378         int flag;
 379         unsigned char base[20];
 380         struct object *o;
 381
 382         if (!resolve_ref(ref, base, 1, &flag))
 383                 return -1;
 384
 385         if ((flag & REF_ISPACKED)) {
 386                 struct ref_list *list = get_packed_refs();
 387
 388                 while (list) {
 389                         if (!strcmp(list->name, ref)) {
 390                                 if (list->flag & REF_KNOWS_PEELED) {
 391                                         hashcpy(sha1, list->peeled);
 392                                         return 0;
 393                                 }
 394                                 /* older pack-refs did not leave peeled ones */
 395                                 break;
 396                         }
 397                         list = list->next;
 398                 }
 399         }
 400
 401         /* fallback - callers should not call this for unpacked refs */
 402         o = parse_object(base);
 403         if (o->type == OBJ_TAG) {
 404                 o = deref_tag(o, ref, 0);
 405                 if (o) {
 406                         hashcpy(sha1, o->sha1);
 407                         return 0;
 408                 }
 409         }
 410         return -1;
 411 }
 412
 413 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 414                            void *cb_data)
 415 {
 416         int retval;
 417         struct ref_list *packed = get_packed_refs();
 418         struct ref_list *loose = get_loose_refs();
 419
 420         while (packed && loose) {
 421                 struct ref_list *entry;
 422                 int cmp = strcmp(packed->name, loose->name);
 423                 if (!cmp) {
 424                         packed = packed->next;
 425                         continue;
 426                 }
 427                 if (cmp > 0) {
 428                         entry = loose;
 429                         loose = loose->next;
 430                 } else {
 431                         entry = packed;
 432                         packed = packed->next;
 433                 }
 434                 retval = do_one_ref(base, fn, trim, cb_data, entry);
 435                 if (retval)
 436                         return retval;
 437         }
 438
 439         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 440                 retval = do_one_ref(base, fn, trim, cb_data, packed);
 441                 if (retval)
 442                         return retval;
 443         }
 444         return 0;
 445 }
 446
 447 int head_ref(each_ref_fn fn, void *cb_data)
 448 {
 449         unsigned char sha1[20];
 450         int flag;
 451
 452         if (resolve_ref("HEAD", sha1, 1, &flag))
 453                 return fn("HEAD", sha1, flag, cb_data);
 454         return 0;
 455 }
 456
 457 int for_each_ref(each_ref_fn fn, void *cb_data)
 458 {
 459         return do_for_each_ref("refs/", fn, 0, cb_data);
 460 }
 461
 462 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 463 {
 464         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 465 }
 466
 467 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 468 {
 469         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 470 }
 471
 472 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 473 {
 474         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 475 }
 476
 477 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
 478  * caller should do resolve_ref or read_ref like everybody else.  Or
 479  * maybe everybody else should use get_ref_sha1() instead of doing
 480  * read_ref().
 481  */
 482 int get_ref_sha1(const char *ref, unsigned char *sha1)
 483 {
 484         if (check_ref_format(ref))
 485                 return -1;
 486         return read_ref(mkpath("refs/%s", ref), sha1);
 487 }
 488
 489 /*
 490  * Make sure "ref" is something reasonable to have under ".git/refs/";
 491  * We do not like it if:
 492  *
 493  * - any path component of it begins with ".", or
 494  * - it has double dots "..", or
 495  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 496  * - it ends with a "/".
 497  */
 498
 499 static inline int bad_ref_char(int ch)
 500 {
 501         return (((unsigned) ch) <= ' ' ||
 502                 ch == '~' || ch == '^' || ch == ':' ||
 503                 /* 2.13 Pattern Matching Notation */
 504                 ch == '?' || ch == '*' || ch == '[');
 505 }
 506
 507 int check_ref_format(const char *ref)
 508 {
 509         int ch, level;
 510         const char *cp = ref;
 511
 512         level = 0;
 513         while (1) {
 514                 while ((ch = *cp++) == '/')
 515                         ; /* tolerate duplicated slashes */
 516                 if (!ch)
 517                         return -1; /* should not end with slashes */
 518
 519                 /* we are at the beginning of the path component */
 520                 if (ch == '.' || bad_ref_char(ch))
 521                         return -1;
 522
 523                 /* scan the rest of the path component */
 524                 while ((ch = *cp++) != 0) {
 525                         if (bad_ref_char(ch))
 526                                 return -1;
 527                         if (ch == '/')
 528                                 break;
 529                         if (ch == '.' && *cp == '.')
 530                                 return -1;
 531                 }
 532                 level++;
 533                 if (!ch) {
 534                         if (level < 2)
 535                                 return -2; /* at least of form "heads/blah" */
 536                         return 0;
 537                 }
 538         }
 539 }
 540
 541 static struct ref_lock *verify_lock(struct ref_lock *lock,
 542         const unsigned char *old_sha1, int mustexist)
 543 {
 544         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 545                 error("Can't verify ref %s", lock->ref_name);
 546                 unlock_ref(lock);
 547                 return NULL;
 548         }
 549         if (hashcmp(lock->old_sha1, old_sha1)) {
 550                 error("Ref %s is at %s but expected %s", lock->ref_name,
 551                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 552                 unlock_ref(lock);
 553                 return NULL;
 554         }
 555         return lock;
 556 }
 557
 558 static int remove_empty_dir_recursive(char *path, int len)
 559 {
 560         DIR *dir = opendir(path);
 561         struct dirent *e;
 562         int ret = 0;
 563
 564         if (!dir)
 565                 return -1;
 566         if (path[len-1] != '/')
 567                 path[len++] = '/';
 568         while ((e = readdir(dir)) != NULL) {
 569                 struct stat st;
 570                 int namlen;
 571                 if ((e->d_name[0] == '.') &&
 572                     ((e->d_name[1] == 0) ||
 573                      ((e->d_name[1] == '.') && e->d_name[2] == 0)))
 574                         continue; /* "." and ".." */
 575
 576                 namlen = strlen(e->d_name);
 577                 if ((len + namlen < PATH_MAX) &&
 578                     strcpy(path + len, e->d_name) &&
 579                     !lstat(path, &st) &&
 580                     S_ISDIR(st.st_mode) &&
 581                     !remove_empty_dir_recursive(path, len + namlen))
 582                         continue; /* happy */
 583
 584                 /* path too long, stat fails, or non-directory still exists */
 585                 ret = -1;
 586                 break;
 587         }
 588         closedir(dir);
 589         if (!ret) {
 590                 path[len] = 0;
 591                 ret = rmdir(path);
 592         }
 593         return ret;
 594 }
 595
 596 static int remove_empty_directories(char *file)
 597 {
 598         /* we want to create a file but there is a directory there;
 599          * if that is an empty directory (or a directory that contains
 600          * only empty directories), remove them.
 601          */
 602         char path[PATH_MAX];
 603         int len = strlen(file);
 604
 605         if (len >= PATH_MAX) /* path too long ;-) */
 606                 return -1;
 607         strcpy(path, file);
 608         return remove_empty_dir_recursive(path, len);
 609 }
 610
 611 static int is_refname_available(const char *ref, const char *oldref,
 612                                 struct ref_list *list, int quiet)
 613 {
 614         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 615         while (list) {
 616                 /* list->name could be 'foo' or 'foo/bar/baz' */
 617                 if (!oldref || strcmp(oldref, list->name)) {
 618                         int len = strlen(list->name);
 619                         int cmplen = (namlen < len) ? namlen : len;
 620                         const char *lead = (namlen < len) ? list->name : ref;
 621                         if (!strncmp(ref, list->name, cmplen) &&
 622                             lead[cmplen] == '/') {
 623                                 if (!quiet)
 624                                         error("'%s' exists; cannot create '%s'",
 625                                               list->name, ref);
 626                                 return 0;
 627                         }
 628                 }
 629                 list = list->next;
 630         }
 631         return 1;
 632 }
 633
 634 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int *flag)
 635 {
 636         char *ref_file;
 637         const char *orig_ref = ref;
 638         struct ref_lock *lock;
 639         struct stat st;
 640         int last_errno = 0;
 641         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 642
 643         lock = xcalloc(1, sizeof(struct ref_lock));
 644         lock->lock_fd = -1;
 645
 646         ref = resolve_ref(ref, lock->old_sha1, mustexist, flag);
 647         if (!ref && errno == EISDIR) {
 648                 /* we are trying to lock foo but we used to
 649                  * have foo/bar which now does not exist;
 650                  * it is normal for the empty directory 'foo'
 651                  * to remain.
 652                  */
 653                 ref_file = git_path("%s", orig_ref);
 654                 if (remove_empty_directories(ref_file)) {
 655                         last_errno = errno;
 656                         error("there are still refs under '%s'", orig_ref);
 657                         goto error_return;
 658                 }
 659                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, flag);
 660         }
 661         if (!ref) {
 662                 last_errno = errno;
 663                 error("unable to resolve reference %s: %s",
 664                         orig_ref, strerror(errno));
 665                 goto error_return;
 666         }
 667         /* When the ref did not exist and we are creating it,
 668          * make sure there is no existing ref that is packed
 669          * whose name begins with our refname, nor a ref whose
 670          * name is a proper prefix of our refname.
 671          */
 672         if (is_null_sha1(lock->old_sha1) &&
 673             !is_refname_available(ref, NULL, get_packed_refs(), 0))
 674                 goto error_return;
 675
 676         lock->lk = xcalloc(1, sizeof(struct lock_file));
 677
 678         lock->ref_name = xstrdup(ref);
 679         lock->log_file = xstrdup(git_path("logs/%s", ref));
 680         ref_file = git_path("%s", ref);
 681         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
 682
 683         if (safe_create_leading_directories(ref_file)) {
 684                 last_errno = errno;
 685                 error("unable to create directory for %s", ref_file);
 686                 goto error_return;
 687         }
 688         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 689
 690         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 691
 692  error_return:
 693         unlock_ref(lock);
 694         errno = last_errno;
 695         return NULL;
 696 }
 697
 698 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 699 {
 700         char refpath[PATH_MAX];
 701         if (check_ref_format(ref))
 702                 return NULL;
 703         strcpy(refpath, mkpath("refs/%s", ref));
 704         return lock_ref_sha1_basic(refpath, old_sha1, NULL);
 705 }
 706
 707 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
 708 {
 709         return lock_ref_sha1_basic(ref, old_sha1, NULL);
 710 }
 711
 712 static struct lock_file packlock;
 713
 714 static int repack_without_ref(const char *refname)
 715 {
 716         struct ref_list *list, *packed_ref_list;
 717         int fd;
 718         int found = 0;
 719
 720         packed_ref_list = get_packed_refs();
 721         for (list = packed_ref_list; list; list = list->next) {
 722                 if (!strcmp(refname, list->name)) {
 723                         found = 1;
 724                         break;
 725                 }
 726         }
 727         if (!found)
 728                 return 0;
 729         memset(&packlock, 0, sizeof(packlock));
 730         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 731         if (fd < 0)
 732                 return error("cannot delete '%s' from packed refs", refname);
 733
 734         for (list = packed_ref_list; list; list = list->next) {
 735                 char line[PATH_MAX + 100];
 736                 int len;
 737
 738                 if (!strcmp(refname, list->name))
 739                         continue;
 740                 len = snprintf(line, sizeof(line), "%s %s\n",
 741                                sha1_to_hex(list->sha1), list->name);
 742                 /* this should not happen but just being defensive */
 743                 if (len > sizeof(line))
 744                         die("too long a refname '%s'", list->name);
 745                 write_or_die(fd, line, len);
 746         }
 747         return commit_lock_file(&packlock);
 748 }
 749
 750 int delete_ref(const char *refname, unsigned char *sha1)
 751 {
 752         struct ref_lock *lock;
 753         int err, i, ret = 0, flag = 0;
 754
 755         lock = lock_ref_sha1_basic(refname, sha1, &flag);
 756         if (!lock)
 757                 return 1;
 758         if (!(flag & REF_ISPACKED)) {
 759                 /* loose */
 760                 i = strlen(lock->lk->filename) - 5; /* .lock */
 761                 lock->lk->filename[i] = 0;
 762                 err = unlink(lock->lk->filename);
 763                 if (err) {
 764                         ret = 1;
 765                         error("unlink(%s) failed: %s",
 766                               lock->lk->filename, strerror(errno));
 767                 }
 768                 lock->lk->filename[i] = '.';
 769         }
 770         /* removing the loose one could have resurrected an earlier
 771          * packed one.  Also, if it was not loose we need to repack
 772          * without it.
 773          */
 774         ret |= repack_without_ref(refname);
 775
 776         err = unlink(lock->log_file);
 777         if (err && errno != ENOENT)
 778                 fprintf(stderr, "warning: unlink(%s) failed: %s",
 779                         lock->log_file, strerror(errno));
 780         invalidate_cached_refs();
 781         unlock_ref(lock);
 782         return ret;
 783 }
 784
 785 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 786 {
 787         static const char renamed_ref[] = "RENAMED-REF";
 788         unsigned char sha1[20], orig_sha1[20];
 789         int flag = 0, logmoved = 0;
 790         struct ref_lock *lock;
 791         struct stat loginfo;
 792         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
 793
 794         if (S_ISLNK(loginfo.st_mode))
 795                 return error("reflog for %s is a symlink", oldref);
 796
 797         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
 798                 return error("refname %s not found", oldref);
 799
 800         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
 801                 return 1;
 802
 803         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
 804                 return 1;
 805
 806         lock = lock_ref_sha1_basic(renamed_ref, NULL, NULL);
 807         if (!lock)
 808                 return error("unable to lock %s", renamed_ref);
 809         lock->force_write = 1;
 810         if (write_ref_sha1(lock, orig_sha1, logmsg))
 811                 return error("unable to save current sha1 in %s", renamed_ref);
 812
 813         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
 814                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
 815                         oldref, strerror(errno));
 816
 817         if (delete_ref(oldref, orig_sha1)) {
 818                 error("unable to delete old %s", oldref);
 819                 goto rollback;
 820         }
 821
 822         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
 823                 if (errno==EISDIR) {
 824                         if (remove_empty_directories(git_path("%s", newref))) {
 825                                 error("Directory not empty: %s", newref);
 826                                 goto rollback;
 827                         }
 828                 } else {
 829                         error("unable to delete existing %s", newref);
 830                         goto rollback;
 831                 }
 832         }
 833
 834         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
 835                 error("unable to create directory for %s", newref);
 836                 goto rollback;
 837         }
 838
 839  retry:
 840         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
 841                 if (errno==EISDIR) {
 842                         if (remove_empty_directories(git_path("logs/%s", newref))) {
 843                                 error("Directory not empty: logs/%s", newref);
 844                                 goto rollback;
 845                         }
 846                         goto retry;
 847                 } else {
 848                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
 849                                 newref, strerror(errno));
 850                         goto rollback;
 851                 }
 852         }
 853         logmoved = log;
 854
 855         lock = lock_ref_sha1_basic(newref, NULL, NULL);
 856         if (!lock) {
 857                 error("unable to lock %s for update", newref);
 858                 goto rollback;
 859         }
 860
 861         lock->force_write = 1;
 862         hashcpy(lock->old_sha1, orig_sha1);
 863         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
 864                 error("unable to write current sha1 into %s", newref);
 865                 goto rollback;
 866         }
 867
 868         if (!strncmp(oldref, "refs/heads/", 11) &&
 869                         !strncmp(newref, "refs/heads/", 11)) {
 870                 char oldsection[1024], newsection[1024];
 871
 872                 snprintf(oldsection, 1024, "branch.%s", oldref + 11);
 873                 snprintf(newsection, 1024, "branch.%s", newref + 11);
 874                 if (git_config_rename_section(oldsection, newsection) < 0)
 875                         return 1;
 876         }
 877
 878         return 0;
 879
 880  rollback:
 881         lock = lock_ref_sha1_basic(oldref, NULL, NULL);
 882         if (!lock) {
 883                 error("unable to lock %s for rollback", oldref);
 884                 goto rollbacklog;
 885         }
 886
 887         lock->force_write = 1;
 888         flag = log_all_ref_updates;
 889         log_all_ref_updates = 0;
 890         if (write_ref_sha1(lock, orig_sha1, NULL))
 891                 error("unable to write current sha1 into %s", oldref);
 892         log_all_ref_updates = flag;
 893
 894  rollbacklog:
 895         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
 896                 error("unable to restore logfile %s from %s: %s",
 897                         oldref, newref, strerror(errno));
 898         if (!logmoved && log &&
 899             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
 900                 error("unable to restore logfile %s from tmp-renamed-log: %s",
 901                         oldref, strerror(errno));
 902
 903         return 1;
 904 }
 905
 906 void unlock_ref(struct ref_lock *lock)
 907 {
 908         if (lock->lock_fd >= 0) {
 909                 close(lock->lock_fd);
 910                 /* Do not free lock->lk -- atexit() still looks at them */
 911                 if (lock->lk)
 912                         rollback_lock_file(lock->lk);
 913         }
 914         free(lock->ref_name);
 915         free(lock->log_file);
 916         free(lock);
 917 }
 918
 919 static int log_ref_write(struct ref_lock *lock,
 920         const unsigned char *sha1, const char *msg)
 921 {
 922         int logfd, written, oflags = O_APPEND | O_WRONLY;
 923         unsigned maxlen, len;
 924         char *logrec;
 925         const char *committer;
 926
 927         if (log_all_ref_updates &&
 928             !strncmp(lock->ref_name, "refs/heads/", 11)) {
 929                 if (safe_create_leading_directories(lock->log_file) < 0)
 930                         return error("unable to create directory for %s",
 931                                 lock->log_file);
 932                 oflags |= O_CREAT;
 933         }
 934
 935         logfd = open(lock->log_file, oflags, 0666);
 936         if (logfd < 0) {
 937                 if (!(oflags & O_CREAT) && errno == ENOENT)
 938                         return 0;
 939
 940                 if ((oflags & O_CREAT) && errno == EISDIR) {
 941                         if (remove_empty_directories(lock->log_file)) {
 942                                 return error("There are still logs under '%s'",
 943                                              lock->log_file);
 944                         }
 945                         logfd = open(lock->log_file, oflags, 0666);
 946                 }
 947
 948                 if (logfd < 0)
 949                         return error("Unable to append to %s: %s",
 950                                      lock->log_file, strerror(errno));
 951         }
 952
 953         committer = git_committer_info(1);
 954         if (msg) {
 955                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 956                 logrec = xmalloc(maxlen);
 957                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 958                         sha1_to_hex(lock->old_sha1),
 959                         sha1_to_hex(sha1),
 960                         committer,
 961                         msg);
 962         }
 963         else {
 964                 maxlen = strlen(committer) + 2*40 + 4;
 965                 logrec = xmalloc(maxlen);
 966                 len = snprintf(logrec, maxlen, "%s %s %s\n",
 967                         sha1_to_hex(lock->old_sha1),
 968                         sha1_to_hex(sha1),
 969                         committer);
 970         }
 971         written = len <= maxlen ? write(logfd, logrec, len) : -1;
 972         free(logrec);
 973         close(logfd);
 974         if (written != len)
 975                 return error("Unable to append to %s", lock->log_file);
 976         return 0;
 977 }
 978
 979 int write_ref_sha1(struct ref_lock *lock,
 980         const unsigned char *sha1, const char *logmsg)
 981 {
 982         static char term = '\n';
 983
 984         if (!lock)
 985                 return -1;
 986         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 987                 unlock_ref(lock);
 988                 return 0;
 989         }
 990         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 991             write(lock->lock_fd, &term, 1) != 1
 992                 || close(lock->lock_fd) < 0) {
 993                 error("Couldn't write %s", lock->lk->filename);
 994                 unlock_ref(lock);
 995                 return -1;
 996         }
 997         invalidate_cached_refs();
 998         if (log_ref_write(lock, sha1, logmsg) < 0) {
 999                 unlock_ref(lock);
1000                 return -1;
1001         }
1002         if (commit_lock_file(lock->lk)) {
1003                 error("Couldn't set %s", lock->ref_name);
1004                 unlock_ref(lock);
1005                 return -1;
1006         }
1007         lock->lock_fd = -1;
1008         unlock_ref(lock);
1009         return 0;
1010 }
1011
1012 int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1)
1013 {
1014         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1015         char *tz_c;
1016         int logfd, tz;
1017         struct stat st;
1018         unsigned long date;
1019         unsigned char logged_sha1[20];
1020
1021         logfile = git_path("logs/%s", ref);
1022         logfd = open(logfile, O_RDONLY, 0);
1023         if (logfd < 0)
1024                 die("Unable to read log %s: %s", logfile, strerror(errno));
1025         fstat(logfd, &st);
1026         if (!st.st_size)
1027                 die("Log %s is empty.", logfile);
1028         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
1029         close(logfd);
1030
1031         lastrec = NULL;
1032         rec = logend = logdata + st.st_size;
1033         while (logdata < rec) {
1034                 if (logdata < rec && *(rec-1) == '\n')
1035                         rec--;
1036                 lastgt = NULL;
1037                 while (logdata < rec && *(rec-1) != '\n') {
1038                         rec--;
1039                         if (*rec == '>')
1040                                 lastgt = rec;
1041                 }
1042                 if (!lastgt)
1043                         die("Log %s is corrupt.", logfile);
1044                 date = strtoul(lastgt + 1, &tz_c, 10);
1045                 if (date <= at_time || cnt == 0) {
1046                         if (lastrec) {
1047                                 if (get_sha1_hex(lastrec, logged_sha1))
1048                                         die("Log %s is corrupt.", logfile);
1049                                 if (get_sha1_hex(rec + 41, sha1))
1050                                         die("Log %s is corrupt.", logfile);
1051                                 if (hashcmp(logged_sha1, sha1)) {
1052                                         tz = strtoul(tz_c, NULL, 10);
1053                                         fprintf(stderr,
1054                                                 "warning: Log %s has gap after %s.\n",
1055                                                 logfile, show_rfc2822_date(date, tz));
1056                                 }
1057                         }
1058                         else if (date == at_time) {
1059                                 if (get_sha1_hex(rec + 41, sha1))
1060                                         die("Log %s is corrupt.", logfile);
1061                         }
1062                         else {
1063                                 if (get_sha1_hex(rec + 41, logged_sha1))
1064                                         die("Log %s is corrupt.", logfile);
1065                                 if (hashcmp(logged_sha1, sha1)) {
1066                                         tz = strtoul(tz_c, NULL, 10);
1067                                         fprintf(stderr,
1068                                                 "warning: Log %s unexpectedly ended on %s.\n",
1069                                                 logfile, show_rfc2822_date(date, tz));
1070                                 }
1071                         }
1072                         munmap((void*)logdata, st.st_size);
1073                         return 0;
1074                 }
1075                 lastrec = rec;
1076                 if (cnt > 0)
1077                         cnt--;
1078         }
1079
1080         rec = logdata;
1081         while (rec < logend && *rec != '>' && *rec != '\n')
1082                 rec++;
1083         if (rec == logend || *rec == '\n')
1084                 die("Log %s is corrupt.", logfile);
1085         date = strtoul(rec + 1, &tz_c, 10);
1086         tz = strtoul(tz_c, NULL, 10);
1087         if (get_sha1_hex(logdata, sha1))
1088                 die("Log %s is corrupt.", logfile);
1089         munmap((void*)logdata, st.st_size);
1090         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
1091                 logfile, show_rfc2822_date(date, tz));
1092         return 0;
1093 }