refs.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "tag.h"
   5 #include "dir.h"
   6
   7 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
   8 #define REF_KNOWS_PEELED 04
   9 #define REF_BROKEN 010
  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 *entry;
  53
  54         /* Allocate it and add it in.. */
  55         len = strlen(name) + 1;
  56         entry = xmalloc(sizeof(struct ref_list) + len);
  57         hashcpy(entry->sha1, sha1);
  58         hashclr(entry->peeled);
  59         memcpy(entry->name, name, len);
  60         entry->flag = flag;
  61         entry->next = list;
  62         if (new_entry)
  63                 *new_entry = entry;
  64         return entry;
  65 }
  66
  67 /* merge sort the ref list */
  68 static struct ref_list *sort_ref_list(struct ref_list *list)
  69 {
  70         int psize, qsize, last_merge_count, cmp;
  71         struct ref_list *p, *q, *l, *e;
  72         struct ref_list *new_list = list;
  73         int k = 1;
  74         int merge_count = 0;
  75
  76         if (!list)
  77                 return list;
  78
  79         do {
  80                 last_merge_count = merge_count;
  81                 merge_count = 0;
  82
  83                 psize = 0;
  84
  85                 p = new_list;
  86                 q = new_list;
  87                 new_list = NULL;
  88                 l = NULL;
  89
  90                 while (p) {
  91                         merge_count++;
  92
  93                         while (psize < k && q->next) {
  94                                 q = q->next;
  95                                 psize++;
  96                         }
  97                         qsize = k;
  98
  99                         while ((psize > 0) || (qsize > 0 && q)) {
 100                                 if (qsize == 0 || !q) {
 101                                         e = p;
 102                                         p = p->next;
 103                                         psize--;
 104                                 } else if (psize == 0) {
 105                                         e = q;
 106                                         q = q->next;
 107                                         qsize--;
 108                                 } else {
 109                                         cmp = strcmp(q->name, p->name);
 110                                         if (cmp < 0) {
 111                                                 e = q;
 112                                                 q = q->next;
 113                                                 qsize--;
 114                                         } else if (cmp > 0) {
 115                                                 e = p;
 116                                                 p = p->next;
 117                                                 psize--;
 118                                         } else {
 119                                                 if (hashcmp(q->sha1, p->sha1))
 120                                                         die("Duplicated ref, and SHA1s don't match: %s",
 121                                                             q->name);
 122                                                 warning("Duplicated ref: %s", q->name);
 123                                                 e = q;
 124                                                 q = q->next;
 125                                                 qsize--;
 126                                                 free(e);
 127                                                 e = p;
 128                                                 p = p->next;
 129                                                 psize--;
 130                                         }
 131                                 }
 132
 133                                 e->next = NULL;
 134
 135                                 if (l)
 136                                         l->next = e;
 137                                 if (!new_list)
 138                                         new_list = e;
 139                                 l = e;
 140                         }
 141
 142                         p = q;
 143                 };
 144
 145                 k = k * 2;
 146         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
 147
 148         return new_list;
 149 }
 150
 151 /*
 152  * Future: need to be in "struct repository"
 153  * when doing a full libification.
 154  */
 155 static struct cached_refs {
 156         char did_loose;
 157         char did_packed;
 158         struct ref_list *loose;
 159         struct ref_list *packed;
 160 } cached_refs;
 161 static struct ref_list *current_ref;
 162
 163 static struct ref_list *extra_refs;
 164
 165 static void free_ref_list(struct ref_list *list)
 166 {
 167         struct ref_list *next;
 168         for ( ; list; list = next) {
 169                 next = list->next;
 170                 free(list);
 171         }
 172 }
 173
 174 static void invalidate_cached_refs(void)
 175 {
 176         struct cached_refs *ca = &cached_refs;
 177
 178         if (ca->did_loose && ca->loose)
 179                 free_ref_list(ca->loose);
 180         if (ca->did_packed && ca->packed)
 181                 free_ref_list(ca->packed);
 182         ca->loose = ca->packed = NULL;
 183         ca->did_loose = ca->did_packed = 0;
 184 }
 185
 186 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 187 {
 188         struct ref_list *list = NULL;
 189         struct ref_list *last = NULL;
 190         char refline[PATH_MAX];
 191         int flag = REF_ISPACKED;
 192
 193         while (fgets(refline, sizeof(refline), f)) {
 194                 unsigned char sha1[20];
 195                 const char *name;
 196                 static const char header[] = "# pack-refs with:";
 197
 198                 if (!strncmp(refline, header, sizeof(header)-1)) {
 199                         const char *traits = refline + sizeof(header) - 1;
 200                         if (strstr(traits, " peeled "))
 201                                 flag |= REF_KNOWS_PEELED;
 202                         /* perhaps other traits later as well */
 203                         continue;
 204                 }
 205
 206                 name = parse_ref_line(refline, sha1);
 207                 if (name) {
 208                         list = add_ref(name, sha1, flag, list, &last);
 209                         continue;
 210                 }
 211                 if (last &&
 212                     refline[0] == '^' &&
 213                     strlen(refline) == 42 &&
 214                     refline[41] == '\n' &&
 215                     !get_sha1_hex(refline + 1, sha1))
 216                         hashcpy(last->peeled, sha1);
 217         }
 218         cached_refs->packed = sort_ref_list(list);
 219 }
 220
 221 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 222 {
 223         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
 224 }
 225
 226 void clear_extra_refs(void)
 227 {
 228         free_ref_list(extra_refs);
 229         extra_refs = NULL;
 230 }
 231
 232 static struct ref_list *get_packed_refs(void)
 233 {
 234         if (!cached_refs.did_packed) {
 235                 FILE *f = fopen(git_path("packed-refs"), "r");
 236                 cached_refs.packed = NULL;
 237                 if (f) {
 238                         read_packed_refs(f, &cached_refs);
 239                         fclose(f);
 240                 }
 241                 cached_refs.did_packed = 1;
 242         }
 243         return cached_refs.packed;
 244 }
 245
 246 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 247 {
 248         DIR *dir = opendir(git_path("%s", base));
 249
 250         if (dir) {
 251                 struct dirent *de;
 252                 int baselen = strlen(base);
 253                 char *ref = xmalloc(baselen + 257);
 254
 255                 memcpy(ref, base, baselen);
 256                 if (baselen && base[baselen-1] != '/')
 257                         ref[baselen++] = '/';
 258
 259                 while ((de = readdir(dir)) != NULL) {
 260                         unsigned char sha1[20];
 261                         struct stat st;
 262                         int flag;
 263                         int namelen;
 264
 265                         if (de->d_name[0] == '.')
 266                                 continue;
 267                         namelen = strlen(de->d_name);
 268                         if (namelen > 255)
 269                                 continue;
 270                         if (has_extension(de->d_name, ".lock"))
 271                                 continue;
 272                         memcpy(ref + baselen, de->d_name, namelen+1);
 273                         if (stat(git_path("%s", ref), &st) < 0)
 274                                 continue;
 275                         if (S_ISDIR(st.st_mode)) {
 276                                 list = get_ref_dir(ref, list);
 277                                 continue;
 278                         }
 279                         if (!resolve_ref(ref, sha1, 1, &flag)) {
 280                                 hashclr(sha1);
 281                                 flag |= REF_BROKEN;
 282                         }
 283                         list = add_ref(ref, sha1, flag, list, NULL);
 284                 }
 285                 free(ref);
 286                 closedir(dir);
 287         }
 288         return sort_ref_list(list);
 289 }
 290
 291 struct warn_if_dangling_data {
 292         FILE *fp;
 293         const char *refname;
 294         const char *msg_fmt;
 295 };
 296
 297 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 298                                    int flags, void *cb_data)
 299 {
 300         struct warn_if_dangling_data *d = cb_data;
 301         const char *resolves_to;
 302         unsigned char junk[20];
 303
 304         if (!(flags & REF_ISSYMREF))
 305                 return 0;
 306
 307         resolves_to = resolve_ref(refname, junk, 0, NULL);
 308         if (!resolves_to || strcmp(resolves_to, d->refname))
 309                 return 0;
 310
 311         fprintf(d->fp, d->msg_fmt, refname);
 312         return 0;
 313 }
 314
 315 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 316 {
 317         struct warn_if_dangling_data data;
 318
 319         data.fp = fp;
 320         data.refname = refname;
 321         data.msg_fmt = msg_fmt;
 322         for_each_rawref(warn_if_dangling_symref, &data);
 323 }
 324
 325 static struct ref_list *get_loose_refs(void)
 326 {
 327         if (!cached_refs.did_loose) {
 328                 cached_refs.loose = get_ref_dir("refs", NULL);
 329                 cached_refs.did_loose = 1;
 330         }
 331         return cached_refs.loose;
 332 }
 333
 334 /* We allow "recursive" symbolic refs. Only within reason, though */
 335 #define MAXDEPTH 5
 336 #define MAXREFLEN (1024)
 337
 338 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 339 {
 340         FILE *f;
 341         struct cached_refs refs;
 342         struct ref_list *ref;
 343         int retval;
 344
 345         strcpy(name + pathlen, "packed-refs");
 346         f = fopen(name, "r");
 347         if (!f)
 348                 return -1;
 349         read_packed_refs(f, &refs);
 350         fclose(f);
 351         ref = refs.packed;
 352         retval = -1;
 353         while (ref) {
 354                 if (!strcmp(ref->name, refname)) {
 355                         retval = 0;
 356                         memcpy(result, ref->sha1, 20);
 357                         break;
 358                 }
 359                 ref = ref->next;
 360         }
 361         free_ref_list(refs.packed);
 362         return retval;
 363 }
 364
 365 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 366 {
 367         int fd, len = strlen(refname);
 368         char buffer[128], *p;
 369
 370         if (recursion > MAXDEPTH || len > MAXREFLEN)
 371                 return -1;
 372         memcpy(name + pathlen, refname, len+1);
 373         fd = open(name, O_RDONLY);
 374         if (fd < 0)
 375                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 376
 377         len = read(fd, buffer, sizeof(buffer)-1);
 378         close(fd);
 379         if (len < 0)
 380                 return -1;
 381         while (len && isspace(buffer[len-1]))
 382                 len--;
 383         buffer[len] = 0;
 384
 385         /* Was it a detached head or an old-fashioned symlink? */
 386         if (!get_sha1_hex(buffer, result))
 387                 return 0;
 388
 389         /* Symref? */
 390         if (strncmp(buffer, "ref:", 4))
 391                 return -1;
 392         p = buffer + 4;
 393         while (isspace(*p))
 394                 p++;
 395
 396         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 397 }
 398
 399 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 400 {
 401         int len = strlen(path), retval;
 402         char *gitdir;
 403         const char *tmp;
 404
 405         while (len && path[len-1] == '/')
 406                 len--;
 407         if (!len)
 408                 return -1;
 409         gitdir = xmalloc(len + MAXREFLEN + 8);
 410         memcpy(gitdir, path, len);
 411         memcpy(gitdir + len, "/.git", 6);
 412         len += 5;
 413
 414         tmp = read_gitfile_gently(gitdir);
 415         if (tmp) {
 416                 free(gitdir);
 417                 len = strlen(tmp);
 418                 gitdir = xmalloc(len + MAXREFLEN + 3);
 419                 memcpy(gitdir, tmp, len);
 420         }
 421         gitdir[len] = '/';
 422         gitdir[++len] = '\0';
 423         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 424         free(gitdir);
 425         return retval;
 426 }
 427
 428 /*
 429  * If the "reading" argument is set, this function finds out what _object_
 430  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
 431  * has to exist, and if it is symbolic, it has to point at an existing ref,
 432  * because the "read" goes through the symref to the ref it points at.
 433  *
 434  * The access that is not "reading" may often be "writing", but does not
 435  * have to; it can be merely checking _where it leads to_. If it is a
 436  * prelude to "writing" to the ref, a write to a symref that points at
 437  * yet-to-be-born ref will create the real ref pointed by the symref.
 438  * reading=0 allows the caller to check where such a symref leads to.
 439  */
 440 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 441 {
 442         int depth = MAXDEPTH;
 443         ssize_t len;
 444         char buffer[256];
 445         static char ref_buffer[256];
 446
 447         if (flag)
 448                 *flag = 0;
 449
 450         for (;;) {
 451                 char path[PATH_MAX];
 452                 struct stat st;
 453                 char *buf;
 454                 int fd;
 455
 456                 if (--depth < 0)
 457                         return NULL;
 458
 459                 git_snpath(path, sizeof(path), "%s", ref);
 460                 /* Special case: non-existing file. */
 461                 if (lstat(path, &st) < 0) {
 462                         struct ref_list *list = get_packed_refs();
 463                         while (list) {
 464                                 if (!strcmp(ref, list->name)) {
 465                                         hashcpy(sha1, list->sha1);
 466                                         if (flag)
 467                                                 *flag |= REF_ISPACKED;
 468                                         return ref;
 469                                 }
 470                                 list = list->next;
 471                         }
 472                         if (reading || errno != ENOENT)
 473                                 return NULL;
 474                         hashclr(sha1);
 475                         return ref;
 476                 }
 477
 478                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 479                 if (S_ISLNK(st.st_mode)) {
 480                         len = readlink(path, buffer, sizeof(buffer)-1);
 481                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 482                                 buffer[len] = 0;
 483                                 strcpy(ref_buffer, buffer);
 484                                 ref = ref_buffer;
 485                                 if (flag)
 486                                         *flag |= REF_ISSYMREF;
 487                                 continue;
 488                         }
 489                 }
 490
 491                 /* Is it a directory? */
 492                 if (S_ISDIR(st.st_mode)) {
 493                         errno = EISDIR;
 494                         return NULL;
 495                 }
 496
 497                 /*
 498                  * Anything else, just open it and try to use it as
 499                  * a ref
 500                  */
 501                 fd = open(path, O_RDONLY);
 502                 if (fd < 0)
 503                         return NULL;
 504                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 505                 close(fd);
 506
 507                 /*
 508                  * Is it a symbolic ref?
 509                  */
 510                 if (len < 4 || memcmp("ref:", buffer, 4))
 511                         break;
 512                 buf = buffer + 4;
 513                 len -= 4;
 514                 while (len && isspace(*buf))
 515                         buf++, len--;
 516                 while (len && isspace(buf[len-1]))
 517                         len--;
 518                 buf[len] = 0;
 519                 memcpy(ref_buffer, buf, len + 1);
 520                 ref = ref_buffer;
 521                 if (flag)
 522                         *flag |= REF_ISSYMREF;
 523         }
 524         if (len < 40 || get_sha1_hex(buffer, sha1))
 525                 return NULL;
 526         return ref;
 527 }
 528
 529 /* The argument to filter_refs */
 530 struct ref_filter {
 531         const char *pattern;
 532         each_ref_fn *fn;
 533         void *cb_data;
 534 };
 535
 536 int read_ref(const char *ref, unsigned char *sha1)
 537 {
 538         if (resolve_ref(ref, sha1, 1, NULL))
 539                 return 0;
 540         return -1;
 541 }
 542
 543 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 544 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 545                       int flags, void *cb_data, struct ref_list *entry)
 546 {
 547         if (strncmp(base, entry->name, trim))
 548                 return 0;
 549
 550         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 551                 if (entry->flag & REF_BROKEN)
 552                         return 0; /* ignore dangling symref */
 553                 if (!has_sha1_file(entry->sha1)) {
 554                         error("%s does not point to a valid object!", entry->name);
 555                         return 0;
 556                 }
 557         }
 558         current_ref = entry;
 559         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 560 }
 561
 562 static int filter_refs(const char *ref, const unsigned char *sha, int flags,
 563         void *data)
 564 {
 565         struct ref_filter *filter = (struct ref_filter *)data;
 566         if (fnmatch(filter->pattern, ref, 0))
 567                 return 0;
 568         return filter->fn(ref, sha, flags, filter->cb_data);
 569 }
 570
 571 int peel_ref(const char *ref, unsigned char *sha1)
 572 {
 573         int flag;
 574         unsigned char base[20];
 575         struct object *o;
 576
 577         if (current_ref && (current_ref->name == ref
 578                 || !strcmp(current_ref->name, ref))) {
 579                 if (current_ref->flag & REF_KNOWS_PEELED) {
 580                         hashcpy(sha1, current_ref->peeled);
 581                         return 0;
 582                 }
 583                 hashcpy(base, current_ref->sha1);
 584                 goto fallback;
 585         }
 586
 587         if (!resolve_ref(ref, base, 1, &flag))
 588                 return -1;
 589
 590         if ((flag & REF_ISPACKED)) {
 591                 struct ref_list *list = get_packed_refs();
 592
 593                 while (list) {
 594                         if (!strcmp(list->name, ref)) {
 595                                 if (list->flag & REF_KNOWS_PEELED) {
 596                                         hashcpy(sha1, list->peeled);
 597                                         return 0;
 598                                 }
 599                                 /* older pack-refs did not leave peeled ones */
 600                                 break;
 601                         }
 602                         list = list->next;
 603                 }
 604         }
 605
 606 fallback:
 607         o = parse_object(base);
 608         if (o && o->type == OBJ_TAG) {
 609                 o = deref_tag(o, ref, 0);
 610                 if (o) {
 611                         hashcpy(sha1, o->sha1);
 612                         return 0;
 613                 }
 614         }
 615         return -1;
 616 }
 617
 618 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 619                            int flags, void *cb_data)
 620 {
 621         int retval = 0;
 622         struct ref_list *packed = get_packed_refs();
 623         struct ref_list *loose = get_loose_refs();
 624
 625         struct ref_list *extra;
 626
 627         for (extra = extra_refs; extra; extra = extra->next)
 628                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 629
 630         while (packed && loose) {
 631                 struct ref_list *entry;
 632                 int cmp = strcmp(packed->name, loose->name);
 633                 if (!cmp) {
 634                         packed = packed->next;
 635                         continue;
 636                 }
 637                 if (cmp > 0) {
 638                         entry = loose;
 639                         loose = loose->next;
 640                 } else {
 641                         entry = packed;
 642                         packed = packed->next;
 643                 }
 644                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 645                 if (retval)
 646                         goto end_each;
 647         }
 648
 649         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 650                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 651                 if (retval)
 652                         goto end_each;
 653         }
 654
 655 end_each:
 656         current_ref = NULL;
 657         return retval;
 658 }
 659
 660 int head_ref(each_ref_fn fn, void *cb_data)
 661 {
 662         unsigned char sha1[20];
 663         int flag;
 664
 665         if (resolve_ref("HEAD", sha1, 1, &flag))
 666                 return fn("HEAD", sha1, flag, cb_data);
 667         return 0;
 668 }
 669
 670 int for_each_ref(each_ref_fn fn, void *cb_data)
 671 {
 672         return do_for_each_ref("refs/", fn, 0, 0, cb_data);
 673 }
 674
 675 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 676 {
 677         return do_for_each_ref(prefix, fn, strlen(prefix), 0, cb_data);
 678 }
 679
 680 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 681 {
 682         return for_each_ref_in("refs/tags/", fn, cb_data);
 683 }
 684
 685 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 686 {
 687         return for_each_ref_in("refs/heads/", fn, cb_data);
 688 }
 689
 690 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 691 {
 692         return for_each_ref_in("refs/remotes/", fn, cb_data);
 693 }
 694
 695 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 696 {
 697         return do_for_each_ref("refs/replace/", fn, 13, 0, cb_data);
 698 }
 699
 700 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 701         const char *prefix, void *cb_data)
 702 {
 703         struct strbuf real_pattern = STRBUF_INIT;
 704         struct ref_filter filter;
 705         int ret;
 706
 707         if (!prefix && prefixcmp(pattern, "refs/"))
 708                 strbuf_addstr(&real_pattern, "refs/");
 709         else if (prefix)
 710                 strbuf_addstr(&real_pattern, prefix);
 711         strbuf_addstr(&real_pattern, pattern);
 712
 713         if (!has_glob_specials(pattern)) {
 714                 /* Append implied '/' '*' if not present. */
 715                 if (real_pattern.buf[real_pattern.len - 1] != '/')
 716                         strbuf_addch(&real_pattern, '/');
 717                 /* No need to check for '*', there is none. */
 718                 strbuf_addch(&real_pattern, '*');
 719         }
 720
 721         filter.pattern = real_pattern.buf;
 722         filter.fn = fn;
 723         filter.cb_data = cb_data;
 724         ret = for_each_ref(filter_refs, &filter);
 725
 726         strbuf_release(&real_pattern);
 727         return ret;
 728 }
 729
 730 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 731 {
 732         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 733 }
 734
 735 int for_each_rawref(each_ref_fn fn, void *cb_data)
 736 {
 737         return do_for_each_ref("refs/", fn, 0,
 738                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 739 }
 740
 741 /*
 742  * Make sure "ref" is something reasonable to have under ".git/refs/";
 743  * We do not like it if:
 744  *
 745  * - any path component of it begins with ".", or
 746  * - it has double dots "..", or
 747  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 748  * - it ends with a "/".
 749  * - it ends with ".lock"
 750  * - it contains a "\" (backslash)
 751  */
 752
 753 static inline int bad_ref_char(int ch)
 754 {
 755         if (((unsigned) ch) <= ' ' ||
 756             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 757                 return 1;
 758         /* 2.13 Pattern Matching Notation */
 759         if (ch == '?' || ch == '[') /* Unsupported */
 760                 return 1;
 761         if (ch == '*') /* Supported at the end */
 762                 return 2;
 763         return 0;
 764 }
 765
 766 int check_ref_format(const char *ref)
 767 {
 768         int ch, level, bad_type, last;
 769         int ret = CHECK_REF_FORMAT_OK;
 770         const char *cp = ref;
 771
 772         level = 0;
 773         while (1) {
 774                 while ((ch = *cp++) == '/')
 775                         ; /* tolerate duplicated slashes */
 776                 if (!ch)
 777                         /* should not end with slashes */
 778                         return CHECK_REF_FORMAT_ERROR;
 779
 780                 /* we are at the beginning of the path component */
 781                 if (ch == '.')
 782                         return CHECK_REF_FORMAT_ERROR;
 783                 bad_type = bad_ref_char(ch);
 784                 if (bad_type) {
 785                         if (bad_type == 2 && (!*cp || *cp == '/') &&
 786                             ret == CHECK_REF_FORMAT_OK)
 787                                 ret = CHECK_REF_FORMAT_WILDCARD;
 788                         else
 789                                 return CHECK_REF_FORMAT_ERROR;
 790                 }
 791
 792                 last = ch;
 793                 /* scan the rest of the path component */
 794                 while ((ch = *cp++) != 0) {
 795                         bad_type = bad_ref_char(ch);
 796                         if (bad_type)
 797                                 return CHECK_REF_FORMAT_ERROR;
 798                         if (ch == '/')
 799                                 break;
 800                         if (last == '.' && ch == '.')
 801                                 return CHECK_REF_FORMAT_ERROR;
 802                         if (last == '@' && ch == '{')
 803                                 return CHECK_REF_FORMAT_ERROR;
 804                         last = ch;
 805                 }
 806                 level++;
 807                 if (!ch) {
 808                         if (ref <= cp - 2 && cp[-2] == '.')
 809                                 return CHECK_REF_FORMAT_ERROR;
 810                         if (level < 2)
 811                                 return CHECK_REF_FORMAT_ONELEVEL;
 812                         if (has_extension(ref, ".lock"))
 813                                 return CHECK_REF_FORMAT_ERROR;
 814                         return ret;
 815                 }
 816         }
 817 }
 818
 819 const char *prettify_refname(const char *name)
 820 {
 821         return name + (
 822                 !prefixcmp(name, "refs/heads/") ? 11 :
 823                 !prefixcmp(name, "refs/tags/") ? 10 :
 824                 !prefixcmp(name, "refs/remotes/") ? 13 :
 825                 0);
 826 }
 827
 828 const char *ref_rev_parse_rules[] = {
 829         "%.*s",
 830         "refs/%.*s",
 831         "refs/tags/%.*s",
 832         "refs/heads/%.*s",
 833         "refs/remotes/%.*s",
 834         "refs/remotes/%.*s/HEAD",
 835         NULL
 836 };
 837
 838 const char *ref_fetch_rules[] = {
 839         "%.*s",
 840         "refs/%.*s",
 841         "refs/heads/%.*s",
 842         NULL
 843 };
 844
 845 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 846 {
 847         const char **p;
 848         const int abbrev_name_len = strlen(abbrev_name);
 849
 850         for (p = rules; *p; p++) {
 851                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 852                         return 1;
 853                 }
 854         }
 855
 856         return 0;
 857 }
 858
 859 static struct ref_lock *verify_lock(struct ref_lock *lock,
 860         const unsigned char *old_sha1, int mustexist)
 861 {
 862         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 863                 error("Can't verify ref %s", lock->ref_name);
 864                 unlock_ref(lock);
 865                 return NULL;
 866         }
 867         if (hashcmp(lock->old_sha1, old_sha1)) {
 868                 error("Ref %s is at %s but expected %s", lock->ref_name,
 869                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 870                 unlock_ref(lock);
 871                 return NULL;
 872         }
 873         return lock;
 874 }
 875
 876 static int remove_empty_directories(const char *file)
 877 {
 878         /* we want to create a file but there is a directory there;
 879          * if that is an empty directory (or a directory that contains
 880          * only empty directories), remove them.
 881          */
 882         struct strbuf path;
 883         int result;
 884
 885         strbuf_init(&path, 20);
 886         strbuf_addstr(&path, file);
 887
 888         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
 889
 890         strbuf_release(&path);
 891
 892         return result;
 893 }
 894
 895 static int is_refname_available(const char *ref, const char *oldref,
 896                                 struct ref_list *list, int quiet)
 897 {
 898         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 899         while (list) {
 900                 /* list->name could be 'foo' or 'foo/bar/baz' */
 901                 if (!oldref || strcmp(oldref, list->name)) {
 902                         int len = strlen(list->name);
 903                         int cmplen = (namlen < len) ? namlen : len;
 904                         const char *lead = (namlen < len) ? list->name : ref;
 905                         if (!strncmp(ref, list->name, cmplen) &&
 906                             lead[cmplen] == '/') {
 907                                 if (!quiet)
 908                                         error("'%s' exists; cannot create '%s'",
 909                                               list->name, ref);
 910                                 return 0;
 911                         }
 912                 }
 913                 list = list->next;
 914         }
 915         return 1;
 916 }
 917
 918 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 919 {
 920         char *ref_file;
 921         const char *orig_ref = ref;
 922         struct ref_lock *lock;
 923         int last_errno = 0;
 924         int type, lflags;
 925         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 926         int missing = 0;
 927
 928         lock = xcalloc(1, sizeof(struct ref_lock));
 929         lock->lock_fd = -1;
 930
 931         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
 932         if (!ref && errno == EISDIR) {
 933                 /* we are trying to lock foo but we used to
 934                  * have foo/bar which now does not exist;
 935                  * it is normal for the empty directory 'foo'
 936                  * to remain.
 937                  */
 938                 ref_file = git_path("%s", orig_ref);
 939                 if (remove_empty_directories(ref_file)) {
 940                         last_errno = errno;
 941                         error("there are still refs under '%s'", orig_ref);
 942                         goto error_return;
 943                 }
 944                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
 945         }
 946         if (type_p)
 947             *type_p = type;
 948         if (!ref) {
 949                 last_errno = errno;
 950                 error("unable to resolve reference %s: %s",
 951                         orig_ref, strerror(errno));
 952                 goto error_return;
 953         }
 954         missing = is_null_sha1(lock->old_sha1);
 955         /* When the ref did not exist and we are creating it,
 956          * make sure there is no existing ref that is packed
 957          * whose name begins with our refname, nor a ref whose
 958          * name is a proper prefix of our refname.
 959          */
 960         if (missing &&
 961              !is_refname_available(ref, NULL, get_packed_refs(), 0)) {
 962                 last_errno = ENOTDIR;
 963                 goto error_return;
 964         }
 965
 966         lock->lk = xcalloc(1, sizeof(struct lock_file));
 967
 968         lflags = LOCK_DIE_ON_ERROR;
 969         if (flags & REF_NODEREF) {
 970                 ref = orig_ref;
 971                 lflags |= LOCK_NODEREF;
 972         }
 973         lock->ref_name = xstrdup(ref);
 974         lock->orig_ref_name = xstrdup(orig_ref);
 975         ref_file = git_path("%s", ref);
 976         if (missing)
 977                 lock->force_write = 1;
 978         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
 979                 lock->force_write = 1;
 980
 981         if (safe_create_leading_directories(ref_file)) {
 982                 last_errno = errno;
 983                 error("unable to create directory for %s", ref_file);
 984                 goto error_return;
 985         }
 986
 987         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 988         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 989
 990  error_return:
 991         unlock_ref(lock);
 992         errno = last_errno;
 993         return NULL;
 994 }
 995
 996 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 997 {
 998         char refpath[PATH_MAX];
 999         if (check_ref_format(ref))
1000                 return NULL;
1001         strcpy(refpath, mkpath("refs/%s", ref));
1002         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1003 }
1004
1005 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
1006 {
1007         switch (check_ref_format(ref)) {
1008         default:
1009                 return NULL;
1010         case 0:
1011         case CHECK_REF_FORMAT_ONELEVEL:
1012                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
1013         }
1014 }
1015
1016 static struct lock_file packlock;
1017
1018 static int repack_without_ref(const char *refname)
1019 {
1020         struct ref_list *list, *packed_ref_list;
1021         int fd;
1022         int found = 0;
1023
1024         packed_ref_list = get_packed_refs();
1025         for (list = packed_ref_list; list; list = list->next) {
1026                 if (!strcmp(refname, list->name)) {
1027                         found = 1;
1028                         break;
1029                 }
1030         }
1031         if (!found)
1032                 return 0;
1033         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1034         if (fd < 0) {
1035                 unable_to_lock_error(git_path("packed-refs"), errno);
1036                 return error("cannot delete '%s' from packed refs", refname);
1037         }
1038
1039         for (list = packed_ref_list; list; list = list->next) {
1040                 char line[PATH_MAX + 100];
1041                 int len;
1042
1043                 if (!strcmp(refname, list->name))
1044                         continue;
1045                 len = snprintf(line, sizeof(line), "%s %s\n",
1046                                sha1_to_hex(list->sha1), list->name);
1047                 /* this should not happen but just being defensive */
1048                 if (len > sizeof(line))
1049                         die("too long a refname '%s'", list->name);
1050                 write_or_die(fd, line, len);
1051         }
1052         return commit_lock_file(&packlock);
1053 }
1054
1055 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1056 {
1057         struct ref_lock *lock;
1058         int err, i = 0, ret = 0, flag = 0;
1059
1060         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1061         if (!lock)
1062                 return 1;
1063         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1064                 /* loose */
1065                 const char *path;
1066
1067                 if (!(delopt & REF_NODEREF)) {
1068                         i = strlen(lock->lk->filename) - 5; /* .lock */
1069                         lock->lk->filename[i] = 0;
1070                         path = lock->lk->filename;
1071                 } else {
1072                         path = git_path("%s", refname);
1073                 }
1074                 err = unlink_or_warn(path);
1075                 if (err && errno != ENOENT)
1076                         ret = 1;
1077
1078                 if (!(delopt & REF_NODEREF))
1079                         lock->lk->filename[i] = '.';
1080         }
1081         /* removing the loose one could have resurrected an earlier
1082          * packed one.  Also, if it was not loose we need to repack
1083          * without it.
1084          */
1085         ret |= repack_without_ref(refname);
1086
1087         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1088         invalidate_cached_refs();
1089         unlock_ref(lock);
1090         return ret;
1091 }
1092
1093 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1094 {
1095         static const char renamed_ref[] = "RENAMED-REF";
1096         unsigned char sha1[20], orig_sha1[20];
1097         int flag = 0, logmoved = 0;
1098         struct ref_lock *lock;
1099         struct stat loginfo;
1100         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1101         const char *symref = NULL;
1102
1103         if (log && S_ISLNK(loginfo.st_mode))
1104                 return error("reflog for %s is a symlink", oldref);
1105
1106         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1107         if (flag & REF_ISSYMREF)
1108                 return error("refname %s is a symbolic ref, renaming it is not supported",
1109                         oldref);
1110         if (!symref)
1111                 return error("refname %s not found", oldref);
1112
1113         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
1114                 return 1;
1115
1116         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
1117                 return 1;
1118
1119         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1120         if (!lock)
1121                 return error("unable to lock %s", renamed_ref);
1122         lock->force_write = 1;
1123         if (write_ref_sha1(lock, orig_sha1, logmsg))
1124                 return error("unable to save current sha1 in %s", renamed_ref);
1125
1126         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
1127                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
1128                         oldref, strerror(errno));
1129
1130         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1131                 error("unable to delete old %s", oldref);
1132                 goto rollback;
1133         }
1134
1135         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1136                 if (errno==EISDIR) {
1137                         if (remove_empty_directories(git_path("%s", newref))) {
1138                                 error("Directory not empty: %s", newref);
1139                                 goto rollback;
1140                         }
1141                 } else {
1142                         error("unable to delete existing %s", newref);
1143                         goto rollback;
1144                 }
1145         }
1146
1147         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1148                 error("unable to create directory for %s", newref);
1149                 goto rollback;
1150         }
1151
1152  retry:
1153         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
1154                 if (errno==EISDIR || errno==ENOTDIR) {
1155                         /*
1156                          * rename(a, b) when b is an existing
1157                          * directory ought to result in ISDIR, but
1158                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1159                          */
1160                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1161                                 error("Directory not empty: logs/%s", newref);
1162                                 goto rollback;
1163                         }
1164                         goto retry;
1165                 } else {
1166                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
1167                                 newref, strerror(errno));
1168                         goto rollback;
1169                 }
1170         }
1171         logmoved = log;
1172
1173         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1174         if (!lock) {
1175                 error("unable to lock %s for update", newref);
1176                 goto rollback;
1177         }
1178         lock->force_write = 1;
1179         hashcpy(lock->old_sha1, orig_sha1);
1180         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1181                 error("unable to write current sha1 into %s", newref);
1182                 goto rollback;
1183         }
1184
1185         return 0;
1186
1187  rollback:
1188         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1189         if (!lock) {
1190                 error("unable to lock %s for rollback", oldref);
1191                 goto rollbacklog;
1192         }
1193
1194         lock->force_write = 1;
1195         flag = log_all_ref_updates;
1196         log_all_ref_updates = 0;
1197         if (write_ref_sha1(lock, orig_sha1, NULL))
1198                 error("unable to write current sha1 into %s", oldref);
1199         log_all_ref_updates = flag;
1200
1201  rollbacklog:
1202         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1203                 error("unable to restore logfile %s from %s: %s",
1204                         oldref, newref, strerror(errno));
1205         if (!logmoved && log &&
1206             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1207                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1208                         oldref, strerror(errno));
1209
1210         return 1;
1211 }
1212
1213 int close_ref(struct ref_lock *lock)
1214 {
1215         if (close_lock_file(lock->lk))
1216                 return -1;
1217         lock->lock_fd = -1;
1218         return 0;
1219 }
1220
1221 int commit_ref(struct ref_lock *lock)
1222 {
1223         if (commit_lock_file(lock->lk))
1224                 return -1;
1225         lock->lock_fd = -1;
1226         return 0;
1227 }
1228
1229 void unlock_ref(struct ref_lock *lock)
1230 {
1231         /* Do not free lock->lk -- atexit() still looks at them */
1232         if (lock->lk)
1233                 rollback_lock_file(lock->lk);
1234         free(lock->ref_name);
1235         free(lock->orig_ref_name);
1236         free(lock);
1237 }
1238
1239 /*
1240  * copy the reflog message msg to buf, which has been allocated sufficiently
1241  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1242  * because reflog file is one line per entry.
1243  */
1244 static int copy_msg(char *buf, const char *msg)
1245 {
1246         char *cp = buf;
1247         char c;
1248         int wasspace = 1;
1249
1250         *cp++ = '\t';
1251         while ((c = *msg++)) {
1252                 if (wasspace && isspace(c))
1253                         continue;
1254                 wasspace = isspace(c);
1255                 if (wasspace)
1256                         c = ' ';
1257                 *cp++ = c;
1258         }
1259         while (buf < cp && isspace(cp[-1]))
1260                 cp--;
1261         *cp++ = '\n';
1262         return cp - buf;
1263 }
1264
1265 int log_ref_setup(const char *ref_name, char **log_file)
1266 {
1267         int logfd, oflags = O_APPEND | O_WRONLY;
1268         static char logfile[PATH_MAX];
1269
1270         git_snpath(logfile, sizeof(logfile), "logs/%s", ref_name);
1271         *log_file = logfile;
1272         if (log_all_ref_updates &&
1273             (!prefixcmp(ref_name, "refs/heads/") ||
1274              !prefixcmp(ref_name, "refs/remotes/") ||
1275              !prefixcmp(ref_name, "refs/notes/") ||
1276              !strcmp(ref_name, "HEAD"))) {
1277                 if (safe_create_leading_directories(*log_file) < 0)
1278                         return error("unable to create directory for %s",
1279                                      *log_file);
1280                 oflags |= O_CREAT;
1281         }
1282
1283         logfd = open(*log_file, oflags, 0666);
1284         if (logfd < 0) {
1285                 if (!(oflags & O_CREAT) && errno == ENOENT)
1286                         return 0;
1287
1288                 if ((oflags & O_CREAT) && errno == EISDIR) {
1289                         if (remove_empty_directories(*log_file)) {
1290                                 return error("There are still logs under '%s'",
1291                                              *log_file);
1292                         }
1293                         logfd = open(*log_file, oflags, 0666);
1294                 }
1295
1296                 if (logfd < 0)
1297                         return error("Unable to append to %s: %s",
1298                                      *log_file, strerror(errno));
1299         }
1300
1301         adjust_shared_perm(*log_file);
1302         close(logfd);
1303         return 0;
1304 }
1305
1306 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1307                          const unsigned char *new_sha1, const char *msg)
1308 {
1309         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1310         unsigned maxlen, len;
1311         int msglen;
1312         char *log_file;
1313         char *logrec;
1314         const char *committer;
1315
1316         if (log_all_ref_updates < 0)
1317                 log_all_ref_updates = !is_bare_repository();
1318
1319         result = log_ref_setup(ref_name, &log_file);
1320         if (result)
1321                 return result;
1322
1323         logfd = open(log_file, oflags);
1324         if (logfd < 0)
1325                 return 0;
1326         msglen = msg ? strlen(msg) : 0;
1327         committer = git_committer_info(0);
1328         maxlen = strlen(committer) + msglen + 100;
1329         logrec = xmalloc(maxlen);
1330         len = sprintf(logrec, "%s %s %s\n",
1331                       sha1_to_hex(old_sha1),
1332                       sha1_to_hex(new_sha1),
1333                       committer);
1334         if (msglen)
1335                 len += copy_msg(logrec + len - 1, msg) - 1;
1336         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1337         free(logrec);
1338         if (close(logfd) != 0 || written != len)
1339                 return error("Unable to append to %s", log_file);
1340         return 0;
1341 }
1342
1343 static int is_branch(const char *refname)
1344 {
1345         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1346 }
1347
1348 int write_ref_sha1(struct ref_lock *lock,
1349         const unsigned char *sha1, const char *logmsg)
1350 {
1351         static char term = '\n';
1352         struct object *o;
1353
1354         if (!lock)
1355                 return -1;
1356         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1357                 unlock_ref(lock);
1358                 return 0;
1359         }
1360         o = parse_object(sha1);
1361         if (!o) {
1362                 error("Trying to write ref %s with nonexistant object %s",
1363                         lock->ref_name, sha1_to_hex(sha1));
1364                 unlock_ref(lock);
1365                 return -1;
1366         }
1367         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1368                 error("Trying to write non-commit object %s to branch %s",
1369                         sha1_to_hex(sha1), lock->ref_name);
1370                 unlock_ref(lock);
1371                 return -1;
1372         }
1373         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1374             write_in_full(lock->lock_fd, &term, 1) != 1
1375                 || close_ref(lock) < 0) {
1376                 error("Couldn't write %s", lock->lk->filename);
1377                 unlock_ref(lock);
1378                 return -1;
1379         }
1380         invalidate_cached_refs();
1381         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1382             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1383              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1384                 unlock_ref(lock);
1385                 return -1;
1386         }
1387         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1388                 /*
1389                  * Special hack: If a branch is updated directly and HEAD
1390                  * points to it (may happen on the remote side of a push
1391                  * for example) then logically the HEAD reflog should be
1392                  * updated too.
1393                  * A generic solution implies reverse symref information,
1394                  * but finding all symrefs pointing to the given branch
1395                  * would be rather costly for this rare event (the direct
1396                  * update of a branch) to be worth it.  So let's cheat and
1397                  * check with HEAD only which should cover 99% of all usage
1398                  * scenarios (even 100% of the default ones).
1399                  */
1400                 unsigned char head_sha1[20];
1401                 int head_flag;
1402                 const char *head_ref;
1403                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1404                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1405                     !strcmp(head_ref, lock->ref_name))
1406                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1407         }
1408         if (commit_ref(lock)) {
1409                 error("Couldn't set %s", lock->ref_name);
1410                 unlock_ref(lock);
1411                 return -1;
1412         }
1413         unlock_ref(lock);
1414         return 0;
1415 }
1416
1417 int create_symref(const char *ref_target, const char *refs_heads_master,
1418                   const char *logmsg)
1419 {
1420         const char *lockpath;
1421         char ref[1000];
1422         int fd, len, written;
1423         char *git_HEAD = git_pathdup("%s", ref_target);
1424         unsigned char old_sha1[20], new_sha1[20];
1425
1426         if (logmsg && read_ref(ref_target, old_sha1))
1427                 hashclr(old_sha1);
1428
1429         if (safe_create_leading_directories(git_HEAD) < 0)
1430                 return error("unable to create directory for %s", git_HEAD);
1431
1432 #ifndef NO_SYMLINK_HEAD
1433         if (prefer_symlink_refs) {
1434                 unlink(git_HEAD);
1435                 if (!symlink(refs_heads_master, git_HEAD))
1436                         goto done;
1437                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1438         }
1439 #endif
1440
1441         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1442         if (sizeof(ref) <= len) {
1443                 error("refname too long: %s", refs_heads_master);
1444                 goto error_free_return;
1445         }
1446         lockpath = mkpath("%s.lock", git_HEAD);
1447         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1448         if (fd < 0) {
1449                 error("Unable to open %s for writing", lockpath);
1450                 goto error_free_return;
1451         }
1452         written = write_in_full(fd, ref, len);
1453         if (close(fd) != 0 || written != len) {
1454                 error("Unable to write to %s", lockpath);
1455                 goto error_unlink_return;
1456         }
1457         if (rename(lockpath, git_HEAD) < 0) {
1458                 error("Unable to create %s", git_HEAD);
1459                 goto error_unlink_return;
1460         }
1461         if (adjust_shared_perm(git_HEAD)) {
1462                 error("Unable to fix permissions on %s", lockpath);
1463         error_unlink_return:
1464                 unlink_or_warn(lockpath);
1465         error_free_return:
1466                 free(git_HEAD);
1467                 return -1;
1468         }
1469
1470 #ifndef NO_SYMLINK_HEAD
1471         done:
1472 #endif
1473         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1474                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1475
1476         free(git_HEAD);
1477         return 0;
1478 }
1479
1480 static char *ref_msg(const char *line, const char *endp)
1481 {
1482         const char *ep;
1483         line += 82;
1484         ep = memchr(line, '\n', endp - line);
1485         if (!ep)
1486                 ep = endp;
1487         return xmemdupz(line, ep - line);
1488 }
1489
1490 int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1, char **msg, unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
1491 {
1492         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1493         char *tz_c;
1494         int logfd, tz, reccnt = 0;
1495         struct stat st;
1496         unsigned long date;
1497         unsigned char logged_sha1[20];
1498         void *log_mapped;
1499         size_t mapsz;
1500
1501         logfile = git_path("logs/%s", ref);
1502         logfd = open(logfile, O_RDONLY, 0);
1503         if (logfd < 0)
1504                 die_errno("Unable to read log '%s'", logfile);
1505         fstat(logfd, &st);
1506         if (!st.st_size)
1507                 die("Log %s is empty.", logfile);
1508         mapsz = xsize_t(st.st_size);
1509         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1510         logdata = log_mapped;
1511         close(logfd);
1512
1513         lastrec = NULL;
1514         rec = logend = logdata + st.st_size;
1515         while (logdata < rec) {
1516                 reccnt++;
1517                 if (logdata < rec && *(rec-1) == '\n')
1518                         rec--;
1519                 lastgt = NULL;
1520                 while (logdata < rec && *(rec-1) != '\n') {
1521                         rec--;
1522                         if (*rec == '>')
1523                                 lastgt = rec;
1524                 }
1525                 if (!lastgt)
1526                         die("Log %s is corrupt.", logfile);
1527                 date = strtoul(lastgt + 1, &tz_c, 10);
1528                 if (date <= at_time || cnt == 0) {
1529                         tz = strtoul(tz_c, NULL, 10);
1530                         if (msg)
1531                                 *msg = ref_msg(rec, logend);
1532                         if (cutoff_time)
1533                                 *cutoff_time = date;
1534                         if (cutoff_tz)
1535                                 *cutoff_tz = tz;
1536                         if (cutoff_cnt)
1537                                 *cutoff_cnt = reccnt - 1;
1538                         if (lastrec) {
1539                                 if (get_sha1_hex(lastrec, logged_sha1))
1540                                         die("Log %s is corrupt.", logfile);
1541                                 if (get_sha1_hex(rec + 41, sha1))
1542                                         die("Log %s is corrupt.", logfile);
1543                                 if (hashcmp(logged_sha1, sha1)) {
1544                                         warning("Log %s has gap after %s.",
1545                                                 logfile, show_date(date, tz, DATE_RFC2822));
1546                                 }
1547                         }
1548                         else if (date == at_time) {
1549                                 if (get_sha1_hex(rec + 41, sha1))
1550                                         die("Log %s is corrupt.", logfile);
1551                         }
1552                         else {
1553                                 if (get_sha1_hex(rec + 41, logged_sha1))
1554                                         die("Log %s is corrupt.", logfile);
1555                                 if (hashcmp(logged_sha1, sha1)) {
1556                                         warning("Log %s unexpectedly ended on %s.",
1557                                                 logfile, show_date(date, tz, DATE_RFC2822));
1558                                 }
1559                         }
1560                         munmap(log_mapped, mapsz);
1561                         return 0;
1562                 }
1563                 lastrec = rec;
1564                 if (cnt > 0)
1565                         cnt--;
1566         }
1567
1568         rec = logdata;
1569         while (rec < logend && *rec != '>' && *rec != '\n')
1570                 rec++;
1571         if (rec == logend || *rec == '\n')
1572                 die("Log %s is corrupt.", logfile);
1573         date = strtoul(rec + 1, &tz_c, 10);
1574         tz = strtoul(tz_c, NULL, 10);
1575         if (get_sha1_hex(logdata, sha1))
1576                 die("Log %s is corrupt.", logfile);
1577         if (is_null_sha1(sha1)) {
1578                 if (get_sha1_hex(logdata + 41, sha1))
1579                         die("Log %s is corrupt.", logfile);
1580         }
1581         if (msg)
1582                 *msg = ref_msg(logdata, logend);
1583         munmap(log_mapped, mapsz);
1584
1585         if (cutoff_time)
1586                 *cutoff_time = date;
1587         if (cutoff_tz)
1588                 *cutoff_tz = tz;
1589         if (cutoff_cnt)
1590                 *cutoff_cnt = reccnt;
1591         return 1;
1592 }
1593
1594 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1595 {
1596         const char *logfile;
1597         FILE *logfp;
1598         struct strbuf sb = STRBUF_INIT;
1599         int ret = 0;
1600
1601         logfile = git_path("logs/%s", ref);
1602         logfp = fopen(logfile, "r");
1603         if (!logfp)
1604                 return -1;
1605
1606         if (ofs) {
1607                 struct stat statbuf;
1608                 if (fstat(fileno(logfp), &statbuf) ||
1609                     statbuf.st_size < ofs ||
1610                     fseek(logfp, -ofs, SEEK_END) ||
1611                     strbuf_getwholeline(&sb, logfp, '\n')) {
1612                         fclose(logfp);
1613                         strbuf_release(&sb);
1614                         return -1;
1615                 }
1616         }
1617
1618         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1619                 unsigned char osha1[20], nsha1[20];
1620                 char *email_end, *message;
1621                 unsigned long timestamp;
1622                 int tz;
1623
1624                 /* old SP new SP name <email> SP time TAB msg LF */
1625                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1626                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1627                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1628                     !(email_end = strchr(sb.buf + 82, '>')) ||
1629                     email_end[1] != ' ' ||
1630                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1631                     !message || message[0] != ' ' ||
1632                     (message[1] != '+' && message[1] != '-') ||
1633                     !isdigit(message[2]) || !isdigit(message[3]) ||
1634                     !isdigit(message[4]) || !isdigit(message[5]))
1635                         continue; /* corrupt? */
1636                 email_end[1] = '\0';
1637                 tz = strtol(message + 1, NULL, 10);
1638                 if (message[6] != '\t')
1639                         message += 6;
1640                 else
1641                         message += 7;
1642                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1643                          cb_data);
1644                 if (ret)
1645                         break;
1646         }
1647         fclose(logfp);
1648         strbuf_release(&sb);
1649         return ret;
1650 }
1651
1652 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1653 {
1654         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1655 }
1656
1657 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1658 {
1659         DIR *dir = opendir(git_path("logs/%s", base));
1660         int retval = 0;
1661
1662         if (dir) {
1663                 struct dirent *de;
1664                 int baselen = strlen(base);
1665                 char *log = xmalloc(baselen + 257);
1666
1667                 memcpy(log, base, baselen);
1668                 if (baselen && base[baselen-1] != '/')
1669                         log[baselen++] = '/';
1670
1671                 while ((de = readdir(dir)) != NULL) {
1672                         struct stat st;
1673                         int namelen;
1674
1675                         if (de->d_name[0] == '.')
1676                                 continue;
1677                         namelen = strlen(de->d_name);
1678                         if (namelen > 255)
1679                                 continue;
1680                         if (has_extension(de->d_name, ".lock"))
1681                                 continue;
1682                         memcpy(log + baselen, de->d_name, namelen+1);
1683                         if (stat(git_path("logs/%s", log), &st) < 0)
1684                                 continue;
1685                         if (S_ISDIR(st.st_mode)) {
1686                                 retval = do_for_each_reflog(log, fn, cb_data);
1687                         } else {
1688                                 unsigned char sha1[20];
1689                                 if (!resolve_ref(log, sha1, 0, NULL))
1690                                         retval = error("bad ref for %s", log);
1691                                 else
1692                                         retval = fn(log, sha1, 0, cb_data);
1693                         }
1694                         if (retval)
1695                                 break;
1696                 }
1697                 free(log);
1698                 closedir(dir);
1699         }
1700         else if (*base)
1701                 return errno;
1702         return retval;
1703 }
1704
1705 int for_each_reflog(each_ref_fn fn, void *cb_data)
1706 {
1707         return do_for_each_reflog("", fn, cb_data);
1708 }
1709
1710 int update_ref(const char *action, const char *refname,
1711                 const unsigned char *sha1, const unsigned char *oldval,
1712                 int flags, enum action_on_err onerr)
1713 {
1714         static struct ref_lock *lock;
1715         lock = lock_any_ref_for_update(refname, oldval, flags);
1716         if (!lock) {
1717                 const char *str = "Cannot lock the ref '%s'.";
1718                 switch (onerr) {
1719                 case MSG_ON_ERR: error(str, refname); break;
1720                 case DIE_ON_ERR: die(str, refname); break;
1721                 case QUIET_ON_ERR: break;
1722                 }
1723                 return 1;
1724         }
1725         if (write_ref_sha1(lock, sha1, action) < 0) {
1726                 const char *str = "Cannot update the ref '%s'.";
1727                 switch (onerr) {
1728                 case MSG_ON_ERR: error(str, refname); break;
1729                 case DIE_ON_ERR: die(str, refname); break;
1730                 case QUIET_ON_ERR: break;
1731                 }
1732                 return 1;
1733         }
1734         return 0;
1735 }
1736
1737 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1738 {
1739         for ( ; list; list = list->next)
1740                 if (!strcmp(list->name, name))
1741                         return (struct ref *)list;
1742         return NULL;
1743 }
1744
1745 /*
1746  * generate a format suitable for scanf from a ref_rev_parse_rules
1747  * rule, that is replace the "%.*s" spec with a "%s" spec
1748  */
1749 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1750 {
1751         char *spec;
1752
1753         spec = strstr(rule, "%.*s");
1754         if (!spec || strstr(spec + 4, "%.*s"))
1755                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1756
1757         /* copy all until spec */
1758         strncpy(scanf_fmt, rule, spec - rule);
1759         scanf_fmt[spec - rule] = '\0';
1760         /* copy new spec */
1761         strcat(scanf_fmt, "%s");
1762         /* copy remaining rule */
1763         strcat(scanf_fmt, spec + 4);
1764
1765         return;
1766 }
1767
1768 char *shorten_unambiguous_ref(const char *ref, int strict)
1769 {
1770         int i;
1771         static char **scanf_fmts;
1772         static int nr_rules;
1773         char *short_name;
1774
1775         /* pre generate scanf formats from ref_rev_parse_rules[] */
1776         if (!nr_rules) {
1777                 size_t total_len = 0;
1778
1779                 /* the rule list is NULL terminated, count them first */
1780                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1781                         /* no +1 because strlen("%s") < strlen("%.*s") */
1782                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1783
1784                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1785
1786                 total_len = 0;
1787                 for (i = 0; i < nr_rules; i++) {
1788                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1789                                         + total_len;
1790                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1791                         total_len += strlen(ref_rev_parse_rules[i]);
1792                 }
1793         }
1794
1795         /* bail out if there are no rules */
1796         if (!nr_rules)
1797                 return xstrdup(ref);
1798
1799         /* buffer for scanf result, at most ref must fit */
1800         short_name = xstrdup(ref);
1801
1802         /* skip first rule, it will always match */
1803         for (i = nr_rules - 1; i > 0 ; --i) {
1804                 int j;
1805                 int rules_to_fail = i;
1806                 int short_name_len;
1807
1808                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1809                         continue;
1810
1811                 short_name_len = strlen(short_name);
1812
1813                 /*
1814                  * in strict mode, all (except the matched one) rules
1815                  * must fail to resolve to a valid non-ambiguous ref
1816                  */
1817                 if (strict)
1818                         rules_to_fail = nr_rules;
1819
1820                 /*
1821                  * check if the short name resolves to a valid ref,
1822                  * but use only rules prior to the matched one
1823                  */
1824                 for (j = 0; j < rules_to_fail; j++) {
1825                         const char *rule = ref_rev_parse_rules[j];
1826                         unsigned char short_objectname[20];
1827                         char refname[PATH_MAX];
1828
1829                         /* skip matched rule */
1830                         if (i == j)
1831                                 continue;
1832
1833                         /*
1834                          * the short name is ambiguous, if it resolves
1835                          * (with this previous rule) to a valid ref
1836                          * read_ref() returns 0 on success
1837                          */
1838                         mksnpath(refname, sizeof(refname),
1839                                  rule, short_name_len, short_name);
1840                         if (!read_ref(refname, short_objectname))
1841                                 break;
1842                 }
1843
1844                 /*
1845                  * short name is non-ambiguous if all previous rules
1846                  * haven't resolved to a valid ref
1847                  */
1848                 if (j == rules_to_fail)
1849                         return short_name;
1850         }
1851
1852         free(short_name);
1853         return xstrdup(ref);
1854 }