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