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, submodule_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(const char *submodule)
 233 {
 234         const char *packed_refs_file;
 235         struct cached_refs *refs;
 236
 237         if (submodule) {
 238                 packed_refs_file = git_path_submodule(submodule, "packed-refs");
 239                 refs = &submodule_refs;
 240                 free_ref_list(refs->packed);
 241         } else {
 242                 packed_refs_file = git_path("packed-refs");
 243                 refs = &cached_refs;
 244         }
 245
 246         if (!refs->did_packed || submodule) {
 247                 FILE *f = fopen(packed_refs_file, "r");
 248                 refs->packed = NULL;
 249                 if (f) {
 250                         read_packed_refs(f, refs);
 251                         fclose(f);
 252                 }
 253                 refs->did_packed = 1;
 254         }
 255         return refs->packed;
 256 }
 257
 258 static struct ref_list *get_ref_dir(const char *submodule, const char *base,
 259                                     struct ref_list *list)
 260 {
 261         DIR *dir;
 262         const char *path;
 263
 264         if (submodule)
 265                 path = git_path_submodule(submodule, "%s", base);
 266         else
 267                 path = git_path("%s", base);
 268
 269
 270         dir = opendir(path);
 271
 272         if (dir) {
 273                 struct dirent *de;
 274                 int baselen = strlen(base);
 275                 char *ref = xmalloc(baselen + 257);
 276
 277                 memcpy(ref, base, baselen);
 278                 if (baselen && base[baselen-1] != '/')
 279                         ref[baselen++] = '/';
 280
 281                 while ((de = readdir(dir)) != NULL) {
 282                         unsigned char sha1[20];
 283                         struct stat st;
 284                         int flag;
 285                         int namelen;
 286                         const char *refdir;
 287
 288                         if (de->d_name[0] == '.')
 289                                 continue;
 290                         namelen = strlen(de->d_name);
 291                         if (namelen > 255)
 292                                 continue;
 293                         if (has_extension(de->d_name, ".lock"))
 294                                 continue;
 295                         memcpy(ref + baselen, de->d_name, namelen+1);
 296                         refdir = submodule
 297                                 ? git_path_submodule(submodule, "%s", ref)
 298                                 : git_path("%s", ref);
 299                         if (stat(refdir, &st) < 0)
 300                                 continue;
 301                         if (S_ISDIR(st.st_mode)) {
 302                                 list = get_ref_dir(submodule, ref, list);
 303                                 continue;
 304                         }
 305                         if (submodule) {
 306                                 hashclr(sha1);
 307                                 flag = 0;
 308                                 if (resolve_gitlink_ref(submodule, ref, sha1) < 0) {
 309                                         hashclr(sha1);
 310                                         flag |= REF_BROKEN;
 311                                 }
 312                         } else
 313                                 if (!resolve_ref(ref, sha1, 1, &flag)) {
 314                                         hashclr(sha1);
 315                                         flag |= REF_BROKEN;
 316                                 }
 317                         list = add_ref(ref, sha1, flag, list, NULL);
 318                 }
 319                 free(ref);
 320                 closedir(dir);
 321         }
 322         return sort_ref_list(list);
 323 }
 324
 325 struct warn_if_dangling_data {
 326         FILE *fp;
 327         const char *refname;
 328         const char *msg_fmt;
 329 };
 330
 331 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 332                                    int flags, void *cb_data)
 333 {
 334         struct warn_if_dangling_data *d = cb_data;
 335         const char *resolves_to;
 336         unsigned char junk[20];
 337
 338         if (!(flags & REF_ISSYMREF))
 339                 return 0;
 340
 341         resolves_to = resolve_ref(refname, junk, 0, NULL);
 342         if (!resolves_to || strcmp(resolves_to, d->refname))
 343                 return 0;
 344
 345         fprintf(d->fp, d->msg_fmt, refname);
 346         return 0;
 347 }
 348
 349 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 350 {
 351         struct warn_if_dangling_data data;
 352
 353         data.fp = fp;
 354         data.refname = refname;
 355         data.msg_fmt = msg_fmt;
 356         for_each_rawref(warn_if_dangling_symref, &data);
 357 }
 358
 359 static struct ref_list *get_loose_refs(const char *submodule)
 360 {
 361         if (submodule) {
 362                 free_ref_list(submodule_refs.loose);
 363                 submodule_refs.loose = get_ref_dir(submodule, "refs", NULL);
 364                 return submodule_refs.loose;
 365         }
 366
 367         if (!cached_refs.did_loose) {
 368                 cached_refs.loose = get_ref_dir(NULL, "refs", NULL);
 369                 cached_refs.did_loose = 1;
 370         }
 371         return cached_refs.loose;
 372 }
 373
 374 /* We allow "recursive" symbolic refs. Only within reason, though */
 375 #define MAXDEPTH 5
 376 #define MAXREFLEN (1024)
 377
 378 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 379 {
 380         FILE *f;
 381         struct cached_refs refs;
 382         struct ref_list *ref;
 383         int retval;
 384
 385         strcpy(name + pathlen, "packed-refs");
 386         f = fopen(name, "r");
 387         if (!f)
 388                 return -1;
 389         read_packed_refs(f, &refs);
 390         fclose(f);
 391         ref = refs.packed;
 392         retval = -1;
 393         while (ref) {
 394                 if (!strcmp(ref->name, refname)) {
 395                         retval = 0;
 396                         memcpy(result, ref->sha1, 20);
 397                         break;
 398                 }
 399                 ref = ref->next;
 400         }
 401         free_ref_list(refs.packed);
 402         return retval;
 403 }
 404
 405 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 406 {
 407         int fd, len = strlen(refname);
 408         char buffer[128], *p;
 409
 410         if (recursion > MAXDEPTH || len > MAXREFLEN)
 411                 return -1;
 412         memcpy(name + pathlen, refname, len+1);
 413         fd = open(name, O_RDONLY);
 414         if (fd < 0)
 415                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 416
 417         len = read(fd, buffer, sizeof(buffer)-1);
 418         close(fd);
 419         if (len < 0)
 420                 return -1;
 421         while (len && isspace(buffer[len-1]))
 422                 len--;
 423         buffer[len] = 0;
 424
 425         /* Was it a detached head or an old-fashioned symlink? */
 426         if (!get_sha1_hex(buffer, result))
 427                 return 0;
 428
 429         /* Symref? */
 430         if (strncmp(buffer, "ref:", 4))
 431                 return -1;
 432         p = buffer + 4;
 433         while (isspace(*p))
 434                 p++;
 435
 436         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 437 }
 438
 439 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 440 {
 441         int len = strlen(path), retval;
 442         char *gitdir;
 443         const char *tmp;
 444
 445         while (len && path[len-1] == '/')
 446                 len--;
 447         if (!len)
 448                 return -1;
 449         gitdir = xmalloc(len + MAXREFLEN + 8);
 450         memcpy(gitdir, path, len);
 451         memcpy(gitdir + len, "/.git", 6);
 452         len += 5;
 453
 454         tmp = read_gitfile(gitdir);
 455         if (tmp) {
 456                 free(gitdir);
 457                 len = strlen(tmp);
 458                 gitdir = xmalloc(len + MAXREFLEN + 3);
 459                 memcpy(gitdir, tmp, len);
 460         }
 461         gitdir[len] = '/';
 462         gitdir[++len] = '\0';
 463         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 464         free(gitdir);
 465         return retval;
 466 }
 467
 468 /*
 469  * If the "reading" argument is set, this function finds out what _object_
 470  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
 471  * has to exist, and if it is symbolic, it has to point at an existing ref,
 472  * because the "read" goes through the symref to the ref it points at.
 473  *
 474  * The access that is not "reading" may often be "writing", but does not
 475  * have to; it can be merely checking _where it leads to_. If it is a
 476  * prelude to "writing" to the ref, a write to a symref that points at
 477  * yet-to-be-born ref will create the real ref pointed by the symref.
 478  * reading=0 allows the caller to check where such a symref leads to.
 479  */
 480 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 481 {
 482         int depth = MAXDEPTH;
 483         ssize_t len;
 484         char buffer[256];
 485         static char ref_buffer[256];
 486
 487         if (flag)
 488                 *flag = 0;
 489
 490         for (;;) {
 491                 char path[PATH_MAX];
 492                 struct stat st;
 493                 char *buf;
 494                 int fd;
 495
 496                 if (--depth < 0)
 497                         return NULL;
 498
 499                 git_snpath(path, sizeof(path), "%s", ref);
 500                 /* Special case: non-existing file. */
 501                 if (lstat(path, &st) < 0) {
 502                         struct ref_list *list = get_packed_refs(NULL);
 503                         while (list) {
 504                                 if (!strcmp(ref, list->name)) {
 505                                         hashcpy(sha1, list->sha1);
 506                                         if (flag)
 507                                                 *flag |= REF_ISPACKED;
 508                                         return ref;
 509                                 }
 510                                 list = list->next;
 511                         }
 512                         if (reading || errno != ENOENT)
 513                                 return NULL;
 514                         hashclr(sha1);
 515                         return ref;
 516                 }
 517
 518                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 519                 if (S_ISLNK(st.st_mode)) {
 520                         len = readlink(path, buffer, sizeof(buffer)-1);
 521                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 522                                 buffer[len] = 0;
 523                                 strcpy(ref_buffer, buffer);
 524                                 ref = ref_buffer;
 525                                 if (flag)
 526                                         *flag |= REF_ISSYMREF;
 527                                 continue;
 528                         }
 529                 }
 530
 531                 /* Is it a directory? */
 532                 if (S_ISDIR(st.st_mode)) {
 533                         errno = EISDIR;
 534                         return NULL;
 535                 }
 536
 537                 /*
 538                  * Anything else, just open it and try to use it as
 539                  * a ref
 540                  */
 541                 fd = open(path, O_RDONLY);
 542                 if (fd < 0)
 543                         return NULL;
 544                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 545                 close(fd);
 546
 547                 /*
 548                  * Is it a symbolic ref?
 549                  */
 550                 if (len < 4 || memcmp("ref:", buffer, 4))
 551                         break;
 552                 buf = buffer + 4;
 553                 len -= 4;
 554                 while (len && isspace(*buf))
 555                         buf++, len--;
 556                 while (len && isspace(buf[len-1]))
 557                         len--;
 558                 buf[len] = 0;
 559                 memcpy(ref_buffer, buf, len + 1);
 560                 ref = ref_buffer;
 561                 if (flag)
 562                         *flag |= REF_ISSYMREF;
 563         }
 564         if (len < 40 || get_sha1_hex(buffer, sha1))
 565                 return NULL;
 566         return ref;
 567 }
 568
 569 /* The argument to filter_refs */
 570 struct ref_filter {
 571         const char *pattern;
 572         each_ref_fn *fn;
 573         void *cb_data;
 574 };
 575
 576 int read_ref(const char *ref, unsigned char *sha1)
 577 {
 578         if (resolve_ref(ref, sha1, 1, NULL))
 579                 return 0;
 580         return -1;
 581 }
 582
 583 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 584 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 585                       int flags, void *cb_data, struct ref_list *entry)
 586 {
 587         if (prefixcmp(entry->name, base))
 588                 return 0;
 589
 590         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 591                 if (entry->flag & REF_BROKEN)
 592                         return 0; /* ignore dangling symref */
 593                 if (!has_sha1_file(entry->sha1)) {
 594                         error("%s does not point to a valid object!", entry->name);
 595                         return 0;
 596                 }
 597         }
 598         current_ref = entry;
 599         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 600 }
 601
 602 static int filter_refs(const char *ref, const unsigned char *sha, int flags,
 603         void *data)
 604 {
 605         struct ref_filter *filter = (struct ref_filter *)data;
 606         if (fnmatch(filter->pattern, ref, 0))
 607                 return 0;
 608         return filter->fn(ref, sha, flags, filter->cb_data);
 609 }
 610
 611 int peel_ref(const char *ref, unsigned char *sha1)
 612 {
 613         int flag;
 614         unsigned char base[20];
 615         struct object *o;
 616
 617         if (current_ref && (current_ref->name == ref
 618                 || !strcmp(current_ref->name, ref))) {
 619                 if (current_ref->flag & REF_KNOWS_PEELED) {
 620                         hashcpy(sha1, current_ref->peeled);
 621                         return 0;
 622                 }
 623                 hashcpy(base, current_ref->sha1);
 624                 goto fallback;
 625         }
 626
 627         if (!resolve_ref(ref, base, 1, &flag))
 628                 return -1;
 629
 630         if ((flag & REF_ISPACKED)) {
 631                 struct ref_list *list = get_packed_refs(NULL);
 632
 633                 while (list) {
 634                         if (!strcmp(list->name, ref)) {
 635                                 if (list->flag & REF_KNOWS_PEELED) {
 636                                         hashcpy(sha1, list->peeled);
 637                                         return 0;
 638                                 }
 639                                 /* older pack-refs did not leave peeled ones */
 640                                 break;
 641                         }
 642                         list = list->next;
 643                 }
 644         }
 645
 646 fallback:
 647         o = parse_object(base);
 648         if (o && o->type == OBJ_TAG) {
 649                 o = deref_tag(o, ref, 0);
 650                 if (o) {
 651                         hashcpy(sha1, o->sha1);
 652                         return 0;
 653                 }
 654         }
 655         return -1;
 656 }
 657
 658 static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
 659                            int trim, int flags, void *cb_data)
 660 {
 661         int retval = 0;
 662         struct ref_list *packed = get_packed_refs(submodule);
 663         struct ref_list *loose = get_loose_refs(submodule);
 664
 665         struct ref_list *extra;
 666
 667         for (extra = extra_refs; extra; extra = extra->next)
 668                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 669
 670         while (packed && loose) {
 671                 struct ref_list *entry;
 672                 int cmp = strcmp(packed->name, loose->name);
 673                 if (!cmp) {
 674                         packed = packed->next;
 675                         continue;
 676                 }
 677                 if (cmp > 0) {
 678                         entry = loose;
 679                         loose = loose->next;
 680                 } else {
 681                         entry = packed;
 682                         packed = packed->next;
 683                 }
 684                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 685                 if (retval)
 686                         goto end_each;
 687         }
 688
 689         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 690                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 691                 if (retval)
 692                         goto end_each;
 693         }
 694
 695 end_each:
 696         current_ref = NULL;
 697         return retval;
 698 }
 699
 700
 701 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 702 {
 703         unsigned char sha1[20];
 704         int flag;
 705
 706         if (submodule) {
 707                 if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
 708                         return fn("HEAD", sha1, 0, cb_data);
 709
 710                 return 0;
 711         }
 712
 713         if (resolve_ref("HEAD", sha1, 1, &flag))
 714                 return fn("HEAD", sha1, flag, cb_data);
 715
 716         return 0;
 717 }
 718
 719 int head_ref(each_ref_fn fn, void *cb_data)
 720 {
 721         return do_head_ref(NULL, fn, cb_data);
 722 }
 723
 724 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 725 {
 726         return do_head_ref(submodule, fn, cb_data);
 727 }
 728
 729 int for_each_ref(each_ref_fn fn, void *cb_data)
 730 {
 731         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
 732 }
 733
 734 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 735 {
 736         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
 737 }
 738
 739 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 740 {
 741         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
 742 }
 743
 744 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 745                 each_ref_fn fn, void *cb_data)
 746 {
 747         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
 748 }
 749
 750 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 751 {
 752         return for_each_ref_in("refs/tags/", fn, cb_data);
 753 }
 754
 755 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 756 {
 757         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 758 }
 759
 760 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 761 {
 762         return for_each_ref_in("refs/heads/", fn, cb_data);
 763 }
 764
 765 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 766 {
 767         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 768 }
 769
 770 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 771 {
 772         return for_each_ref_in("refs/remotes/", fn, cb_data);
 773 }
 774
 775 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 776 {
 777         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 778 }
 779
 780 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 781 {
 782         return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
 783 }
 784
 785 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 786 {
 787         struct strbuf buf = STRBUF_INIT;
 788         int ret = 0;
 789         unsigned char sha1[20];
 790         int flag;
 791
 792         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 793         if (resolve_ref(buf.buf, sha1, 1, &flag))
 794                 ret = fn(buf.buf, sha1, flag, cb_data);
 795         strbuf_release(&buf);
 796
 797         return ret;
 798 }
 799
 800 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
 801 {
 802         struct strbuf buf = STRBUF_INIT;
 803         int ret;
 804         strbuf_addf(&buf, "%srefs/", get_git_namespace());
 805         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
 806         strbuf_release(&buf);
 807         return ret;
 808 }
 809
 810 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 811         const char *prefix, void *cb_data)
 812 {
 813         struct strbuf real_pattern = STRBUF_INIT;
 814         struct ref_filter filter;
 815         int ret;
 816
 817         if (!prefix && prefixcmp(pattern, "refs/"))
 818                 strbuf_addstr(&real_pattern, "refs/");
 819         else if (prefix)
 820                 strbuf_addstr(&real_pattern, prefix);
 821         strbuf_addstr(&real_pattern, pattern);
 822
 823         if (!has_glob_specials(pattern)) {
 824                 /* Append implied '/' '*' if not present. */
 825                 if (real_pattern.buf[real_pattern.len - 1] != '/')
 826                         strbuf_addch(&real_pattern, '/');
 827                 /* No need to check for '*', there is none. */
 828                 strbuf_addch(&real_pattern, '*');
 829         }
 830
 831         filter.pattern = real_pattern.buf;
 832         filter.fn = fn;
 833         filter.cb_data = cb_data;
 834         ret = for_each_ref(filter_refs, &filter);
 835
 836         strbuf_release(&real_pattern);
 837         return ret;
 838 }
 839
 840 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 841 {
 842         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 843 }
 844
 845 int for_each_rawref(each_ref_fn fn, void *cb_data)
 846 {
 847         return do_for_each_ref(NULL, "", fn, 0,
 848                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 849 }
 850
 851 /*
 852  * Make sure "ref" is something reasonable to have under ".git/refs/";
 853  * We do not like it if:
 854  *
 855  * - any path component of it begins with ".", or
 856  * - it has double dots "..", or
 857  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 858  * - it ends with a "/".
 859  * - it ends with ".lock"
 860  * - it contains a "\" (backslash)
 861  */
 862
 863 static inline int bad_ref_char(int ch)
 864 {
 865         if (((unsigned) ch) <= ' ' || ch == 0x7f ||
 866             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 867                 return 1;
 868         /* 2.13 Pattern Matching Notation */
 869         if (ch == '?' || ch == '[') /* Unsupported */
 870                 return 1;
 871         if (ch == '*') /* Supported at the end */
 872                 return 2;
 873         return 0;
 874 }
 875
 876 int check_ref_format(const char *ref)
 877 {
 878         int ch, level, bad_type, last;
 879         int ret = CHECK_REF_FORMAT_OK;
 880         const char *cp = ref;
 881
 882         level = 0;
 883         while (1) {
 884                 while ((ch = *cp++) == '/')
 885                         ; /* tolerate duplicated slashes */
 886                 if (!ch)
 887                         /* should not end with slashes */
 888                         return CHECK_REF_FORMAT_ERROR;
 889
 890                 /* we are at the beginning of the path component */
 891                 if (ch == '.')
 892                         return CHECK_REF_FORMAT_ERROR;
 893                 bad_type = bad_ref_char(ch);
 894                 if (bad_type) {
 895                         if (bad_type == 2 && (!*cp || *cp == '/') &&
 896                             ret == CHECK_REF_FORMAT_OK)
 897                                 ret = CHECK_REF_FORMAT_WILDCARD;
 898                         else
 899                                 return CHECK_REF_FORMAT_ERROR;
 900                 }
 901
 902                 last = ch;
 903                 /* scan the rest of the path component */
 904                 while ((ch = *cp++) != 0) {
 905                         bad_type = bad_ref_char(ch);
 906                         if (bad_type)
 907                                 return CHECK_REF_FORMAT_ERROR;
 908                         if (ch == '/')
 909                                 break;
 910                         if (last == '.' && ch == '.')
 911                                 return CHECK_REF_FORMAT_ERROR;
 912                         if (last == '@' && ch == '{')
 913                                 return CHECK_REF_FORMAT_ERROR;
 914                         last = ch;
 915                 }
 916                 level++;
 917                 if (!ch) {
 918                         if (ref <= cp - 2 && cp[-2] == '.')
 919                                 return CHECK_REF_FORMAT_ERROR;
 920                         if (level < 2)
 921                                 return CHECK_REF_FORMAT_ONELEVEL;
 922                         if (has_extension(ref, ".lock"))
 923                                 return CHECK_REF_FORMAT_ERROR;
 924                         return ret;
 925                 }
 926         }
 927 }
 928
 929 const char *prettify_refname(const char *name)
 930 {
 931         return name + (
 932                 !prefixcmp(name, "refs/heads/") ? 11 :
 933                 !prefixcmp(name, "refs/tags/") ? 10 :
 934                 !prefixcmp(name, "refs/remotes/") ? 13 :
 935                 0);
 936 }
 937
 938 const char *ref_rev_parse_rules[] = {
 939         "%.*s",
 940         "refs/%.*s",
 941         "refs/tags/%.*s",
 942         "refs/heads/%.*s",
 943         "refs/remotes/%.*s",
 944         "refs/remotes/%.*s/HEAD",
 945         NULL
 946 };
 947
 948 const char *ref_fetch_rules[] = {
 949         "%.*s",
 950         "refs/%.*s",
 951         "refs/heads/%.*s",
 952         NULL
 953 };
 954
 955 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 956 {
 957         const char **p;
 958         const int abbrev_name_len = strlen(abbrev_name);
 959
 960         for (p = rules; *p; p++) {
 961                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 962                         return 1;
 963                 }
 964         }
 965
 966         return 0;
 967 }
 968
 969 static struct ref_lock *verify_lock(struct ref_lock *lock,
 970         const unsigned char *old_sha1, int mustexist)
 971 {
 972         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 973                 error("Can't verify ref %s", lock->ref_name);
 974                 unlock_ref(lock);
 975                 return NULL;
 976         }
 977         if (hashcmp(lock->old_sha1, old_sha1)) {
 978                 error("Ref %s is at %s but expected %s", lock->ref_name,
 979                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 980                 unlock_ref(lock);
 981                 return NULL;
 982         }
 983         return lock;
 984 }
 985
 986 static int remove_empty_directories(const char *file)
 987 {
 988         /* we want to create a file but there is a directory there;
 989          * if that is an empty directory (or a directory that contains
 990          * only empty directories), remove them.
 991          */
 992         struct strbuf path;
 993         int result;
 994
 995         strbuf_init(&path, 20);
 996         strbuf_addstr(&path, file);
 997
 998         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
 999
1000         strbuf_release(&path);
1001
1002         return result;
1003 }
1004
1005 static int is_refname_available(const char *ref, const char *oldref,
1006                                 struct ref_list *list, int quiet)
1007 {
1008         int namlen = strlen(ref); /* e.g. 'foo/bar' */
1009         while (list) {
1010                 /* list->name could be 'foo' or 'foo/bar/baz' */
1011                 if (!oldref || strcmp(oldref, list->name)) {
1012                         int len = strlen(list->name);
1013                         int cmplen = (namlen < len) ? namlen : len;
1014                         const char *lead = (namlen < len) ? list->name : ref;
1015                         if (!strncmp(ref, list->name, cmplen) &&
1016                             lead[cmplen] == '/') {
1017                                 if (!quiet)
1018                                         error("'%s' exists; cannot create '%s'",
1019                                               list->name, ref);
1020                                 return 0;
1021                         }
1022                 }
1023                 list = list->next;
1024         }
1025         return 1;
1026 }
1027
1028 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
1029 {
1030         char *ref_file;
1031         const char *orig_ref = ref;
1032         struct ref_lock *lock;
1033         int last_errno = 0;
1034         int type, lflags;
1035         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1036         int missing = 0;
1037
1038         lock = xcalloc(1, sizeof(struct ref_lock));
1039         lock->lock_fd = -1;
1040
1041         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
1042         if (!ref && errno == EISDIR) {
1043                 /* we are trying to lock foo but we used to
1044                  * have foo/bar which now does not exist;
1045                  * it is normal for the empty directory 'foo'
1046                  * to remain.
1047                  */
1048                 ref_file = git_path("%s", orig_ref);
1049                 if (remove_empty_directories(ref_file)) {
1050                         last_errno = errno;
1051                         error("there are still refs under '%s'", orig_ref);
1052                         goto error_return;
1053                 }
1054                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
1055         }
1056         if (type_p)
1057             *type_p = type;
1058         if (!ref) {
1059                 last_errno = errno;
1060                 error("unable to resolve reference %s: %s",
1061                         orig_ref, strerror(errno));
1062                 goto error_return;
1063         }
1064         missing = is_null_sha1(lock->old_sha1);
1065         /* When the ref did not exist and we are creating it,
1066          * make sure there is no existing ref that is packed
1067          * whose name begins with our refname, nor a ref whose
1068          * name is a proper prefix of our refname.
1069          */
1070         if (missing &&
1071              !is_refname_available(ref, NULL, get_packed_refs(NULL), 0)) {
1072                 last_errno = ENOTDIR;
1073                 goto error_return;
1074         }
1075
1076         lock->lk = xcalloc(1, sizeof(struct lock_file));
1077
1078         lflags = LOCK_DIE_ON_ERROR;
1079         if (flags & REF_NODEREF) {
1080                 ref = orig_ref;
1081                 lflags |= LOCK_NODEREF;
1082         }
1083         lock->ref_name = xstrdup(ref);
1084         lock->orig_ref_name = xstrdup(orig_ref);
1085         ref_file = git_path("%s", ref);
1086         if (missing)
1087                 lock->force_write = 1;
1088         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1089                 lock->force_write = 1;
1090
1091         if (safe_create_leading_directories(ref_file)) {
1092                 last_errno = errno;
1093                 error("unable to create directory for %s", ref_file);
1094                 goto error_return;
1095         }
1096
1097         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1098         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1099
1100  error_return:
1101         unlock_ref(lock);
1102         errno = last_errno;
1103         return NULL;
1104 }
1105
1106 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
1107 {
1108         char refpath[PATH_MAX];
1109         if (check_ref_format(ref))
1110                 return NULL;
1111         strcpy(refpath, mkpath("refs/%s", ref));
1112         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1113 }
1114
1115 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
1116 {
1117         switch (check_ref_format(ref)) {
1118         default:
1119                 return NULL;
1120         case 0:
1121         case CHECK_REF_FORMAT_ONELEVEL:
1122                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
1123         }
1124 }
1125
1126 static struct lock_file packlock;
1127
1128 static int repack_without_ref(const char *refname)
1129 {
1130         struct ref_list *list, *packed_ref_list;
1131         int fd;
1132         int found = 0;
1133
1134         packed_ref_list = get_packed_refs(NULL);
1135         for (list = packed_ref_list; list; list = list->next) {
1136                 if (!strcmp(refname, list->name)) {
1137                         found = 1;
1138                         break;
1139                 }
1140         }
1141         if (!found)
1142                 return 0;
1143         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1144         if (fd < 0) {
1145                 unable_to_lock_error(git_path("packed-refs"), errno);
1146                 return error("cannot delete '%s' from packed refs", refname);
1147         }
1148
1149         for (list = packed_ref_list; list; list = list->next) {
1150                 char line[PATH_MAX + 100];
1151                 int len;
1152
1153                 if (!strcmp(refname, list->name))
1154                         continue;
1155                 len = snprintf(line, sizeof(line), "%s %s\n",
1156                                sha1_to_hex(list->sha1), list->name);
1157                 /* this should not happen but just being defensive */
1158                 if (len > sizeof(line))
1159                         die("too long a refname '%s'", list->name);
1160                 write_or_die(fd, line, len);
1161         }
1162         return commit_lock_file(&packlock);
1163 }
1164
1165 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1166 {
1167         struct ref_lock *lock;
1168         int err, i = 0, ret = 0, flag = 0;
1169
1170         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1171         if (!lock)
1172                 return 1;
1173         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1174                 /* loose */
1175                 const char *path;
1176
1177                 if (!(delopt & REF_NODEREF)) {
1178                         i = strlen(lock->lk->filename) - 5; /* .lock */
1179                         lock->lk->filename[i] = 0;
1180                         path = lock->lk->filename;
1181                 } else {
1182                         path = git_path("%s", refname);
1183                 }
1184                 err = unlink_or_warn(path);
1185                 if (err && errno != ENOENT)
1186                         ret = 1;
1187
1188                 if (!(delopt & REF_NODEREF))
1189                         lock->lk->filename[i] = '.';
1190         }
1191         /* removing the loose one could have resurrected an earlier
1192          * packed one.  Also, if it was not loose we need to repack
1193          * without it.
1194          */
1195         ret |= repack_without_ref(refname);
1196
1197         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1198         invalidate_cached_refs();
1199         unlock_ref(lock);
1200         return ret;
1201 }
1202
1203 /*
1204  * People using contrib's git-new-workdir have .git/logs/refs ->
1205  * /some/other/path/.git/logs/refs, and that may live on another device.
1206  *
1207  * IOW, to avoid cross device rename errors, the temporary renamed log must
1208  * live into logs/refs.
1209  */
1210 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1211
1212 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1213 {
1214         static const char renamed_ref[] = "RENAMED-REF";
1215         unsigned char sha1[20], orig_sha1[20];
1216         int flag = 0, logmoved = 0;
1217         struct ref_lock *lock;
1218         struct stat loginfo;
1219         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1220         const char *symref = NULL;
1221
1222         if (log && S_ISLNK(loginfo.st_mode))
1223                 return error("reflog for %s is a symlink", oldref);
1224
1225         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1226         if (flag & REF_ISSYMREF)
1227                 return error("refname %s is a symbolic ref, renaming it is not supported",
1228                         oldref);
1229         if (!symref)
1230                 return error("refname %s not found", oldref);
1231
1232         if (!is_refname_available(newref, oldref, get_packed_refs(NULL), 0))
1233                 return 1;
1234
1235         if (!is_refname_available(newref, oldref, get_loose_refs(NULL), 0))
1236                 return 1;
1237
1238         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1239         if (!lock)
1240                 return error("unable to lock %s", renamed_ref);
1241         lock->force_write = 1;
1242         if (write_ref_sha1(lock, orig_sha1, logmsg))
1243                 return error("unable to save current sha1 in %s", renamed_ref);
1244
1245         if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
1246                 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1247                         oldref, strerror(errno));
1248
1249         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1250                 error("unable to delete old %s", oldref);
1251                 goto rollback;
1252         }
1253
1254         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1255                 if (errno==EISDIR) {
1256                         if (remove_empty_directories(git_path("%s", newref))) {
1257                                 error("Directory not empty: %s", newref);
1258                                 goto rollback;
1259                         }
1260                 } else {
1261                         error("unable to delete existing %s", newref);
1262                         goto rollback;
1263                 }
1264         }
1265
1266         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1267                 error("unable to create directory for %s", newref);
1268                 goto rollback;
1269         }
1270
1271  retry:
1272         if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
1273                 if (errno==EISDIR || errno==ENOTDIR) {
1274                         /*
1275                          * rename(a, b) when b is an existing
1276                          * directory ought to result in ISDIR, but
1277                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1278                          */
1279                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1280                                 error("Directory not empty: logs/%s", newref);
1281                                 goto rollback;
1282                         }
1283                         goto retry;
1284                 } else {
1285                         error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1286                                 newref, strerror(errno));
1287                         goto rollback;
1288                 }
1289         }
1290         logmoved = log;
1291
1292         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1293         if (!lock) {
1294                 error("unable to lock %s for update", newref);
1295                 goto rollback;
1296         }
1297         lock->force_write = 1;
1298         hashcpy(lock->old_sha1, orig_sha1);
1299         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1300                 error("unable to write current sha1 into %s", newref);
1301                 goto rollback;
1302         }
1303
1304         return 0;
1305
1306  rollback:
1307         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1308         if (!lock) {
1309                 error("unable to lock %s for rollback", oldref);
1310                 goto rollbacklog;
1311         }
1312
1313         lock->force_write = 1;
1314         flag = log_all_ref_updates;
1315         log_all_ref_updates = 0;
1316         if (write_ref_sha1(lock, orig_sha1, NULL))
1317                 error("unable to write current sha1 into %s", oldref);
1318         log_all_ref_updates = flag;
1319
1320  rollbacklog:
1321         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1322                 error("unable to restore logfile %s from %s: %s",
1323                         oldref, newref, strerror(errno));
1324         if (!logmoved && log &&
1325             rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
1326                 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1327                         oldref, strerror(errno));
1328
1329         return 1;
1330 }
1331
1332 int close_ref(struct ref_lock *lock)
1333 {
1334         if (close_lock_file(lock->lk))
1335                 return -1;
1336         lock->lock_fd = -1;
1337         return 0;
1338 }
1339
1340 int commit_ref(struct ref_lock *lock)
1341 {
1342         if (commit_lock_file(lock->lk))
1343                 return -1;
1344         lock->lock_fd = -1;
1345         return 0;
1346 }
1347
1348 void unlock_ref(struct ref_lock *lock)
1349 {
1350         /* Do not free lock->lk -- atexit() still looks at them */
1351         if (lock->lk)
1352                 rollback_lock_file(lock->lk);
1353         free(lock->ref_name);
1354         free(lock->orig_ref_name);
1355         free(lock);
1356 }
1357
1358 /*
1359  * copy the reflog message msg to buf, which has been allocated sufficiently
1360  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1361  * because reflog file is one line per entry.
1362  */
1363 static int copy_msg(char *buf, const char *msg)
1364 {
1365         char *cp = buf;
1366         char c;
1367         int wasspace = 1;
1368
1369         *cp++ = '\t';
1370         while ((c = *msg++)) {
1371                 if (wasspace && isspace(c))
1372                         continue;
1373                 wasspace = isspace(c);
1374                 if (wasspace)
1375                         c = ' ';
1376                 *cp++ = c;
1377         }
1378         while (buf < cp && isspace(cp[-1]))
1379                 cp--;
1380         *cp++ = '\n';
1381         return cp - buf;
1382 }
1383
1384 int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
1385 {
1386         int logfd, oflags = O_APPEND | O_WRONLY;
1387
1388         git_snpath(logfile, bufsize, "logs/%s", ref_name);
1389         if (log_all_ref_updates &&
1390             (!prefixcmp(ref_name, "refs/heads/") ||
1391              !prefixcmp(ref_name, "refs/remotes/") ||
1392              !prefixcmp(ref_name, "refs/notes/") ||
1393              !strcmp(ref_name, "HEAD"))) {
1394                 if (safe_create_leading_directories(logfile) < 0)
1395                         return error("unable to create directory for %s",
1396                                      logfile);
1397                 oflags |= O_CREAT;
1398         }
1399
1400         logfd = open(logfile, oflags, 0666);
1401         if (logfd < 0) {
1402                 if (!(oflags & O_CREAT) && errno == ENOENT)
1403                         return 0;
1404
1405                 if ((oflags & O_CREAT) && errno == EISDIR) {
1406                         if (remove_empty_directories(logfile)) {
1407                                 return error("There are still logs under '%s'",
1408                                              logfile);
1409                         }
1410                         logfd = open(logfile, oflags, 0666);
1411                 }
1412
1413                 if (logfd < 0)
1414                         return error("Unable to append to %s: %s",
1415                                      logfile, strerror(errno));
1416         }
1417
1418         adjust_shared_perm(logfile);
1419         close(logfd);
1420         return 0;
1421 }
1422
1423 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1424                          const unsigned char *new_sha1, const char *msg)
1425 {
1426         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1427         unsigned maxlen, len;
1428         int msglen;
1429         char log_file[PATH_MAX];
1430         char *logrec;
1431         const char *committer;
1432
1433         if (log_all_ref_updates < 0)
1434                 log_all_ref_updates = !is_bare_repository();
1435
1436         result = log_ref_setup(ref_name, log_file, sizeof(log_file));
1437         if (result)
1438                 return result;
1439
1440         logfd = open(log_file, oflags);
1441         if (logfd < 0)
1442                 return 0;
1443         msglen = msg ? strlen(msg) : 0;
1444         committer = git_committer_info(0);
1445         maxlen = strlen(committer) + msglen + 100;
1446         logrec = xmalloc(maxlen);
1447         len = sprintf(logrec, "%s %s %s\n",
1448                       sha1_to_hex(old_sha1),
1449                       sha1_to_hex(new_sha1),
1450                       committer);
1451         if (msglen)
1452                 len += copy_msg(logrec + len - 1, msg) - 1;
1453         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1454         free(logrec);
1455         if (close(logfd) != 0 || written != len)
1456                 return error("Unable to append to %s", log_file);
1457         return 0;
1458 }
1459
1460 static int is_branch(const char *refname)
1461 {
1462         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1463 }
1464
1465 int write_ref_sha1(struct ref_lock *lock,
1466         const unsigned char *sha1, const char *logmsg)
1467 {
1468         static char term = '\n';
1469         struct object *o;
1470
1471         if (!lock)
1472                 return -1;
1473         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1474                 unlock_ref(lock);
1475                 return 0;
1476         }
1477         o = parse_object(sha1);
1478         if (!o) {
1479                 error("Trying to write ref %s with nonexistent object %s",
1480                         lock->ref_name, sha1_to_hex(sha1));
1481                 unlock_ref(lock);
1482                 return -1;
1483         }
1484         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1485                 error("Trying to write non-commit object %s to branch %s",
1486                         sha1_to_hex(sha1), lock->ref_name);
1487                 unlock_ref(lock);
1488                 return -1;
1489         }
1490         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1491             write_in_full(lock->lock_fd, &term, 1) != 1
1492                 || close_ref(lock) < 0) {
1493                 error("Couldn't write %s", lock->lk->filename);
1494                 unlock_ref(lock);
1495                 return -1;
1496         }
1497         invalidate_cached_refs();
1498         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1499             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1500              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1501                 unlock_ref(lock);
1502                 return -1;
1503         }
1504         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1505                 /*
1506                  * Special hack: If a branch is updated directly and HEAD
1507                  * points to it (may happen on the remote side of a push
1508                  * for example) then logically the HEAD reflog should be
1509                  * updated too.
1510                  * A generic solution implies reverse symref information,
1511                  * but finding all symrefs pointing to the given branch
1512                  * would be rather costly for this rare event (the direct
1513                  * update of a branch) to be worth it.  So let's cheat and
1514                  * check with HEAD only which should cover 99% of all usage
1515                  * scenarios (even 100% of the default ones).
1516                  */
1517                 unsigned char head_sha1[20];
1518                 int head_flag;
1519                 const char *head_ref;
1520                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1521                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1522                     !strcmp(head_ref, lock->ref_name))
1523                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1524         }
1525         if (commit_ref(lock)) {
1526                 error("Couldn't set %s", lock->ref_name);
1527                 unlock_ref(lock);
1528                 return -1;
1529         }
1530         unlock_ref(lock);
1531         return 0;
1532 }
1533
1534 int create_symref(const char *ref_target, const char *refs_heads_master,
1535                   const char *logmsg)
1536 {
1537         const char *lockpath;
1538         char ref[1000];
1539         int fd, len, written;
1540         char *git_HEAD = git_pathdup("%s", ref_target);
1541         unsigned char old_sha1[20], new_sha1[20];
1542
1543         if (logmsg && read_ref(ref_target, old_sha1))
1544                 hashclr(old_sha1);
1545
1546         if (safe_create_leading_directories(git_HEAD) < 0)
1547                 return error("unable to create directory for %s", git_HEAD);
1548
1549 #ifndef NO_SYMLINK_HEAD
1550         if (prefer_symlink_refs) {
1551                 unlink(git_HEAD);
1552                 if (!symlink(refs_heads_master, git_HEAD))
1553                         goto done;
1554                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1555         }
1556 #endif
1557
1558         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1559         if (sizeof(ref) <= len) {
1560                 error("refname too long: %s", refs_heads_master);
1561                 goto error_free_return;
1562         }
1563         lockpath = mkpath("%s.lock", git_HEAD);
1564         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1565         if (fd < 0) {
1566                 error("Unable to open %s for writing", lockpath);
1567                 goto error_free_return;
1568         }
1569         written = write_in_full(fd, ref, len);
1570         if (close(fd) != 0 || written != len) {
1571                 error("Unable to write to %s", lockpath);
1572                 goto error_unlink_return;
1573         }
1574         if (rename(lockpath, git_HEAD) < 0) {
1575                 error("Unable to create %s", git_HEAD);
1576                 goto error_unlink_return;
1577         }
1578         if (adjust_shared_perm(git_HEAD)) {
1579                 error("Unable to fix permissions on %s", lockpath);
1580         error_unlink_return:
1581                 unlink_or_warn(lockpath);
1582         error_free_return:
1583                 free(git_HEAD);
1584                 return -1;
1585         }
1586
1587 #ifndef NO_SYMLINK_HEAD
1588         done:
1589 #endif
1590         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1591                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1592
1593         free(git_HEAD);
1594         return 0;
1595 }
1596
1597 static char *ref_msg(const char *line, const char *endp)
1598 {
1599         const char *ep;
1600         line += 82;
1601         ep = memchr(line, '\n', endp - line);
1602         if (!ep)
1603                 ep = endp;
1604         return xmemdupz(line, ep - line);
1605 }
1606
1607 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)
1608 {
1609         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1610         char *tz_c;
1611         int logfd, tz, reccnt = 0;
1612         struct stat st;
1613         unsigned long date;
1614         unsigned char logged_sha1[20];
1615         void *log_mapped;
1616         size_t mapsz;
1617
1618         logfile = git_path("logs/%s", ref);
1619         logfd = open(logfile, O_RDONLY, 0);
1620         if (logfd < 0)
1621                 die_errno("Unable to read log '%s'", logfile);
1622         fstat(logfd, &st);
1623         if (!st.st_size)
1624                 die("Log %s is empty.", logfile);
1625         mapsz = xsize_t(st.st_size);
1626         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1627         logdata = log_mapped;
1628         close(logfd);
1629
1630         lastrec = NULL;
1631         rec = logend = logdata + st.st_size;
1632         while (logdata < rec) {
1633                 reccnt++;
1634                 if (logdata < rec && *(rec-1) == '\n')
1635                         rec--;
1636                 lastgt = NULL;
1637                 while (logdata < rec && *(rec-1) != '\n') {
1638                         rec--;
1639                         if (*rec == '>')
1640                                 lastgt = rec;
1641                 }
1642                 if (!lastgt)
1643                         die("Log %s is corrupt.", logfile);
1644                 date = strtoul(lastgt + 1, &tz_c, 10);
1645                 if (date <= at_time || cnt == 0) {
1646                         tz = strtoul(tz_c, NULL, 10);
1647                         if (msg)
1648                                 *msg = ref_msg(rec, logend);
1649                         if (cutoff_time)
1650                                 *cutoff_time = date;
1651                         if (cutoff_tz)
1652                                 *cutoff_tz = tz;
1653                         if (cutoff_cnt)
1654                                 *cutoff_cnt = reccnt - 1;
1655                         if (lastrec) {
1656                                 if (get_sha1_hex(lastrec, logged_sha1))
1657                                         die("Log %s is corrupt.", logfile);
1658                                 if (get_sha1_hex(rec + 41, sha1))
1659                                         die("Log %s is corrupt.", logfile);
1660                                 if (hashcmp(logged_sha1, sha1)) {
1661                                         warning("Log %s has gap after %s.",
1662                                                 logfile, show_date(date, tz, DATE_RFC2822));
1663                                 }
1664                         }
1665                         else if (date == at_time) {
1666                                 if (get_sha1_hex(rec + 41, sha1))
1667                                         die("Log %s is corrupt.", logfile);
1668                         }
1669                         else {
1670                                 if (get_sha1_hex(rec + 41, logged_sha1))
1671                                         die("Log %s is corrupt.", logfile);
1672                                 if (hashcmp(logged_sha1, sha1)) {
1673                                         warning("Log %s unexpectedly ended on %s.",
1674                                                 logfile, show_date(date, tz, DATE_RFC2822));
1675                                 }
1676                         }
1677                         munmap(log_mapped, mapsz);
1678                         return 0;
1679                 }
1680                 lastrec = rec;
1681                 if (cnt > 0)
1682                         cnt--;
1683         }
1684
1685         rec = logdata;
1686         while (rec < logend && *rec != '>' && *rec != '\n')
1687                 rec++;
1688         if (rec == logend || *rec == '\n')
1689                 die("Log %s is corrupt.", logfile);
1690         date = strtoul(rec + 1, &tz_c, 10);
1691         tz = strtoul(tz_c, NULL, 10);
1692         if (get_sha1_hex(logdata, sha1))
1693                 die("Log %s is corrupt.", logfile);
1694         if (is_null_sha1(sha1)) {
1695                 if (get_sha1_hex(logdata + 41, sha1))
1696                         die("Log %s is corrupt.", logfile);
1697         }
1698         if (msg)
1699                 *msg = ref_msg(logdata, logend);
1700         munmap(log_mapped, mapsz);
1701
1702         if (cutoff_time)
1703                 *cutoff_time = date;
1704         if (cutoff_tz)
1705                 *cutoff_tz = tz;
1706         if (cutoff_cnt)
1707                 *cutoff_cnt = reccnt;
1708         return 1;
1709 }
1710
1711 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1712 {
1713         const char *logfile;
1714         FILE *logfp;
1715         struct strbuf sb = STRBUF_INIT;
1716         int ret = 0;
1717
1718         logfile = git_path("logs/%s", ref);
1719         logfp = fopen(logfile, "r");
1720         if (!logfp)
1721                 return -1;
1722
1723         if (ofs) {
1724                 struct stat statbuf;
1725                 if (fstat(fileno(logfp), &statbuf) ||
1726                     statbuf.st_size < ofs ||
1727                     fseek(logfp, -ofs, SEEK_END) ||
1728                     strbuf_getwholeline(&sb, logfp, '\n')) {
1729                         fclose(logfp);
1730                         strbuf_release(&sb);
1731                         return -1;
1732                 }
1733         }
1734
1735         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1736                 unsigned char osha1[20], nsha1[20];
1737                 char *email_end, *message;
1738                 unsigned long timestamp;
1739                 int tz;
1740
1741                 /* old SP new SP name <email> SP time TAB msg LF */
1742                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1743                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1744                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1745                     !(email_end = strchr(sb.buf + 82, '>')) ||
1746                     email_end[1] != ' ' ||
1747                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1748                     !message || message[0] != ' ' ||
1749                     (message[1] != '+' && message[1] != '-') ||
1750                     !isdigit(message[2]) || !isdigit(message[3]) ||
1751                     !isdigit(message[4]) || !isdigit(message[5]))
1752                         continue; /* corrupt? */
1753                 email_end[1] = '\0';
1754                 tz = strtol(message + 1, NULL, 10);
1755                 if (message[6] != '\t')
1756                         message += 6;
1757                 else
1758                         message += 7;
1759                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1760                          cb_data);
1761                 if (ret)
1762                         break;
1763         }
1764         fclose(logfp);
1765         strbuf_release(&sb);
1766         return ret;
1767 }
1768
1769 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1770 {
1771         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1772 }
1773
1774 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1775 {
1776         DIR *dir = opendir(git_path("logs/%s", base));
1777         int retval = 0;
1778
1779         if (dir) {
1780                 struct dirent *de;
1781                 int baselen = strlen(base);
1782                 char *log = xmalloc(baselen + 257);
1783
1784                 memcpy(log, base, baselen);
1785                 if (baselen && base[baselen-1] != '/')
1786                         log[baselen++] = '/';
1787
1788                 while ((de = readdir(dir)) != NULL) {
1789                         struct stat st;
1790                         int namelen;
1791
1792                         if (de->d_name[0] == '.')
1793                                 continue;
1794                         namelen = strlen(de->d_name);
1795                         if (namelen > 255)
1796                                 continue;
1797                         if (has_extension(de->d_name, ".lock"))
1798                                 continue;
1799                         memcpy(log + baselen, de->d_name, namelen+1);
1800                         if (stat(git_path("logs/%s", log), &st) < 0)
1801                                 continue;
1802                         if (S_ISDIR(st.st_mode)) {
1803                                 retval = do_for_each_reflog(log, fn, cb_data);
1804                         } else {
1805                                 unsigned char sha1[20];
1806                                 if (!resolve_ref(log, sha1, 0, NULL))
1807                                         retval = error("bad ref for %s", log);
1808                                 else
1809                                         retval = fn(log, sha1, 0, cb_data);
1810                         }
1811                         if (retval)
1812                                 break;
1813                 }
1814                 free(log);
1815                 closedir(dir);
1816         }
1817         else if (*base)
1818                 return errno;
1819         return retval;
1820 }
1821
1822 int for_each_reflog(each_ref_fn fn, void *cb_data)
1823 {
1824         return do_for_each_reflog("", fn, cb_data);
1825 }
1826
1827 int update_ref(const char *action, const char *refname,
1828                 const unsigned char *sha1, const unsigned char *oldval,
1829                 int flags, enum action_on_err onerr)
1830 {
1831         static struct ref_lock *lock;
1832         lock = lock_any_ref_for_update(refname, oldval, flags);
1833         if (!lock) {
1834                 const char *str = "Cannot lock the ref '%s'.";
1835                 switch (onerr) {
1836                 case MSG_ON_ERR: error(str, refname); break;
1837                 case DIE_ON_ERR: die(str, refname); break;
1838                 case QUIET_ON_ERR: break;
1839                 }
1840                 return 1;
1841         }
1842         if (write_ref_sha1(lock, sha1, action) < 0) {
1843                 const char *str = "Cannot update the ref '%s'.";
1844                 switch (onerr) {
1845                 case MSG_ON_ERR: error(str, refname); break;
1846                 case DIE_ON_ERR: die(str, refname); break;
1847                 case QUIET_ON_ERR: break;
1848                 }
1849                 return 1;
1850         }
1851         return 0;
1852 }
1853
1854 int ref_exists(char *refname)
1855 {
1856         unsigned char sha1[20];
1857         return !!resolve_ref(refname, sha1, 1, NULL);
1858 }
1859
1860 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1861 {
1862         for ( ; list; list = list->next)
1863                 if (!strcmp(list->name, name))
1864                         return (struct ref *)list;
1865         return NULL;
1866 }
1867
1868 /*
1869  * generate a format suitable for scanf from a ref_rev_parse_rules
1870  * rule, that is replace the "%.*s" spec with a "%s" spec
1871  */
1872 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1873 {
1874         char *spec;
1875
1876         spec = strstr(rule, "%.*s");
1877         if (!spec || strstr(spec + 4, "%.*s"))
1878                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1879
1880         /* copy all until spec */
1881         strncpy(scanf_fmt, rule, spec - rule);
1882         scanf_fmt[spec - rule] = '\0';
1883         /* copy new spec */
1884         strcat(scanf_fmt, "%s");
1885         /* copy remaining rule */
1886         strcat(scanf_fmt, spec + 4);
1887
1888         return;
1889 }
1890
1891 char *shorten_unambiguous_ref(const char *ref, int strict)
1892 {
1893         int i;
1894         static char **scanf_fmts;
1895         static int nr_rules;
1896         char *short_name;
1897
1898         /* pre generate scanf formats from ref_rev_parse_rules[] */
1899         if (!nr_rules) {
1900                 size_t total_len = 0;
1901
1902                 /* the rule list is NULL terminated, count them first */
1903                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1904                         /* no +1 because strlen("%s") < strlen("%.*s") */
1905                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1906
1907                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1908
1909                 total_len = 0;
1910                 for (i = 0; i < nr_rules; i++) {
1911                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1912                                         + total_len;
1913                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1914                         total_len += strlen(ref_rev_parse_rules[i]);
1915                 }
1916         }
1917
1918         /* bail out if there are no rules */
1919         if (!nr_rules)
1920                 return xstrdup(ref);
1921
1922         /* buffer for scanf result, at most ref must fit */
1923         short_name = xstrdup(ref);
1924
1925         /* skip first rule, it will always match */
1926         for (i = nr_rules - 1; i > 0 ; --i) {
1927                 int j;
1928                 int rules_to_fail = i;
1929                 int short_name_len;
1930
1931                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1932                         continue;
1933
1934                 short_name_len = strlen(short_name);
1935
1936                 /*
1937                  * in strict mode, all (except the matched one) rules
1938                  * must fail to resolve to a valid non-ambiguous ref
1939                  */
1940                 if (strict)
1941                         rules_to_fail = nr_rules;
1942
1943                 /*
1944                  * check if the short name resolves to a valid ref,
1945                  * but use only rules prior to the matched one
1946                  */
1947                 for (j = 0; j < rules_to_fail; j++) {
1948                         const char *rule = ref_rev_parse_rules[j];
1949                         unsigned char short_objectname[20];
1950                         char refname[PATH_MAX];
1951
1952                         /* skip matched rule */
1953                         if (i == j)
1954                                 continue;
1955
1956                         /*
1957                          * the short name is ambiguous, if it resolves
1958                          * (with this previous rule) to a valid ref
1959                          * read_ref() returns 0 on success
1960                          */
1961                         mksnpath(refname, sizeof(refname),
1962                                  rule, short_name_len, short_name);
1963                         if (!read_ref(refname, short_objectname))
1964                                 break;
1965                 }
1966
1967                 /*
1968                  * short name is non-ambiguous if all previous rules
1969                  * haven't resolved to a valid ref
1970                  */
1971                 if (j == rules_to_fail)
1972                         return short_name;
1973         }
1974
1975         free(short_name);
1976         return xstrdup(ref);
1977 }