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