Pileus Git - ~andy/git/blob - 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_entry {
  12         unsigned char flag; /* ISSYMREF? ISPACKED? */
  13         unsigned char sha1[20];
  14         unsigned char peeled[20];
  15         char name[FLEX_ARRAY];
  16 };
  17
  18 struct ref_array {
  19         int nr, alloc;
  20         struct ref_entry **refs;
  21 };
  22
  23 static const char *parse_ref_line(char *line, unsigned char *sha1)
  24 {
  25         /*
  26          * 42: the answer to everything.
  27          *
  28          * In this case, it happens to be the answer to
  29          *  40 (length of sha1 hex representation)
  30          *  +1 (space in between hex and name)
  31          *  +1 (newline at the end of the line)
  32          */
  33         int len = strlen(line) - 42;
  34
  35         if (len <= 0)
  36                 return NULL;
  37         if (get_sha1_hex(line, sha1) < 0)
  38                 return NULL;
  39         if (!isspace(line[40]))
  40                 return NULL;
  41         line += 41;
  42         if (isspace(*line))
  43                 return NULL;
  44         if (line[len] != '\n')
  45                 return NULL;
  46         line[len] = 0;
  47
  48         return line;
  49 }
  50
  51 static void add_ref(const char *name, const unsigned char *sha1,
  52                     int flag, struct ref_array *refs,
  53                     struct ref_entry **new_entry)
  54 {
  55         int len;
  56         struct ref_entry *entry;
  57
  58         /* Allocate it and add it in.. */
  59         len = strlen(name) + 1;
  60         entry = xmalloc(sizeof(struct ref_entry) + len);
  61         hashcpy(entry->sha1, sha1);
  62         hashclr(entry->peeled);
  63         memcpy(entry->name, name, len);
  64         entry->flag = flag;
  65         if (new_entry)
  66                 *new_entry = entry;
  67         ALLOC_GROW(refs->refs, refs->nr + 1, refs->alloc);
  68         refs->refs[refs->nr++] = entry;
  69 }
  70
  71 static int ref_entry_cmp(const void *a, const void *b)
  72 {
  73         struct ref_entry *one = *(struct ref_entry **)a;
  74         struct ref_entry *two = *(struct ref_entry **)b;
  75         return strcmp(one->name, two->name);
  76 }
  77
  78 static void sort_ref_array(struct ref_array *array)
  79 {
  80         int i = 0, j = 1;
  81
  82         /* Nothing to sort unless there are at least two entries */
  83         if (array->nr < 2)
  84                 return;
  85
  86         qsort(array->refs, array->nr, sizeof(*array->refs), ref_entry_cmp);
  87
  88         /* Remove any duplicates from the ref_array */
  89         for (; j < array->nr; j++) {
  90                 struct ref_entry *a = array->refs[i];
  91                 struct ref_entry *b = array->refs[j];
  92                 if (!strcmp(a->name, b->name)) {
  93                         if (hashcmp(a->sha1, b->sha1))
  94                                 die("Duplicated ref, and SHA1s don't match: %s",
  95                                     a->name);
  96                         warning("Duplicated ref: %s", a->name);
  97                         free(b);
  98                         continue;
  99                 }
 100                 i++;
 101                 array->refs[i] = array->refs[j];
 102         }
 103         array->nr = i + 1;
 104 }
 105
 106 static struct ref_entry *search_ref_array(struct ref_array *array, const char *name)
 107 {
 108         struct ref_entry *e, **r;
 109         int len;
 110
 111         if (name == NULL)
 112                 return NULL;
 113
 114         if (!array->nr)
 115                 return NULL;
 116
 117         len = strlen(name) + 1;
 118         e = xmalloc(sizeof(struct ref_entry) + len);
 119         memcpy(e->name, name, len);
 120
 121         r = bsearch(&e, array->refs, array->nr, sizeof(*array->refs), ref_entry_cmp);
 122
 123         free(e);
 124
 125         if (r == NULL)
 126                 return NULL;
 127
 128         return *r;
 129 }
 130
 131 /*
 132  * Future: need to be in "struct repository"
 133  * when doing a full libification.
 134  */
 135 static struct cached_refs {
 136         char did_loose;
 137         char did_packed;
 138         struct ref_array loose;
 139         struct ref_array packed;
 140 } cached_refs, submodule_refs;
 141 static struct ref_entry *current_ref;
 142
 143 static struct ref_array extra_refs;
 144
 145 static void free_ref_array(struct ref_array *array)
 146 {
 147         int i;
 148         for (i = 0; i < array->nr; i++)
 149                 free(array->refs[i]);
 150         free(array->refs);
 151         array->nr = array->alloc = 0;
 152         array->refs = NULL;
 153 }
 154
 155 static void invalidate_cached_refs(void)
 156 {
 157         struct cached_refs *ca = &cached_refs;
 158
 159         if (ca->did_loose)
 160                 free_ref_array(&ca->loose);
 161         if (ca->did_packed)
 162                 free_ref_array(&ca->packed);
 163         ca->did_loose = ca->did_packed = 0;
 164 }
 165
 166 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 167 {
 168         struct ref_entry *last = NULL;
 169         char refline[PATH_MAX];
 170         int flag = REF_ISPACKED;
 171
 172         while (fgets(refline, sizeof(refline), f)) {
 173                 unsigned char sha1[20];
 174                 const char *name;
 175                 static const char header[] = "# pack-refs with:";
 176
 177                 if (!strncmp(refline, header, sizeof(header)-1)) {
 178                         const char *traits = refline + sizeof(header) - 1;
 179                         if (strstr(traits, " peeled "))
 180                                 flag |= REF_KNOWS_PEELED;
 181                         /* perhaps other traits later as well */
 182                         continue;
 183                 }
 184
 185                 name = parse_ref_line(refline, sha1);
 186                 if (name) {
 187                         add_ref(name, sha1, flag, &cached_refs->packed, &last);
 188                         continue;
 189                 }
 190                 if (last &&
 191                     refline[0] == '^' &&
 192                     strlen(refline) == 42 &&
 193                     refline[41] == '\n' &&
 194                     !get_sha1_hex(refline + 1, sha1))
 195                         hashcpy(last->peeled, sha1);
 196         }
 197         sort_ref_array(&cached_refs->packed);
 198 }
 199
 200 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 201 {
 202         add_ref(name, sha1, flag, &extra_refs, NULL);
 203 }
 204
 205 void clear_extra_refs(void)
 206 {
 207         free_ref_array(&extra_refs);
 208 }
 209
 210 static struct ref_array *get_packed_refs(const char *submodule)
 211 {
 212         const char *packed_refs_file;
 213         struct cached_refs *refs;
 214
 215         if (submodule) {
 216                 packed_refs_file = git_path_submodule(submodule, "packed-refs");
 217                 refs = &submodule_refs;
 218                 free_ref_array(&refs->packed);
 219         } else {
 220                 packed_refs_file = git_path("packed-refs");
 221                 refs = &cached_refs;
 222         }
 223
 224         if (!refs->did_packed || submodule) {
 225                 FILE *f = fopen(packed_refs_file, "r");
 226                 if (f) {
 227                         read_packed_refs(f, refs);
 228                         fclose(f);
 229                 }
 230                 refs->did_packed = 1;
 231         }
 232         return &refs->packed;
 233 }
 234
 235 static void get_ref_dir(const char *submodule, const char *base,
 236                         struct ref_array *array)
 237 {
 238         DIR *dir;
 239         const char *path;
 240
 241         if (submodule)
 242                 path = git_path_submodule(submodule, "%s", base);
 243         else
 244                 path = git_path("%s", base);
 245
 246
 247         dir = opendir(path);
 248
 249         if (dir) {
 250                 struct dirent *de;
 251                 int baselen = strlen(base);
 252                 char *ref = xmalloc(baselen + 257);
 253
 254                 memcpy(ref, base, baselen);
 255                 if (baselen && base[baselen-1] != '/')
 256                         ref[baselen++] = '/';
 257
 258                 while ((de = readdir(dir)) != NULL) {
 259                         unsigned char sha1[20];
 260                         struct stat st;
 261                         int flag;
 262                         int namelen;
 263                         const char *refdir;
 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                         refdir = submodule
 274                                 ? git_path_submodule(submodule, "%s", ref)
 275                                 : git_path("%s", ref);
 276                         if (stat(refdir, &st) < 0)
 277                                 continue;
 278                         if (S_ISDIR(st.st_mode)) {
 279                                 get_ref_dir(submodule, ref, array);
 280                                 continue;
 281                         }
 282                         if (submodule) {
 283                                 hashclr(sha1);
 284                                 flag = 0;
 285                                 if (resolve_gitlink_ref(submodule, ref, sha1) < 0) {
 286                                         hashclr(sha1);
 287                                         flag |= REF_BROKEN;
 288                                 }
 289                         } else
 290                                 if (!resolve_ref(ref, sha1, 1, &flag)) {
 291                                         hashclr(sha1);
 292                                         flag |= REF_BROKEN;
 293                                 }
 294                         add_ref(ref, sha1, flag, array, NULL);
 295                 }
 296                 free(ref);
 297                 closedir(dir);
 298         }
 299 }
 300
 301 struct warn_if_dangling_data {
 302         FILE *fp;
 303         const char *refname;
 304         const char *msg_fmt;
 305 };
 306
 307 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 308                                    int flags, void *cb_data)
 309 {
 310         struct warn_if_dangling_data *d = cb_data;
 311         const char *resolves_to;
 312         unsigned char junk[20];
 313
 314         if (!(flags & REF_ISSYMREF))
 315                 return 0;
 316
 317         resolves_to = resolve_ref(refname, junk, 0, NULL);
 318         if (!resolves_to || strcmp(resolves_to, d->refname))
 319                 return 0;
 320
 321         fprintf(d->fp, d->msg_fmt, refname);
 322         return 0;
 323 }
 324
 325 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 326 {
 327         struct warn_if_dangling_data data;
 328
 329         data.fp = fp;
 330         data.refname = refname;
 331         data.msg_fmt = msg_fmt;
 332         for_each_rawref(warn_if_dangling_symref, &data);
 333 }
 334
 335 static struct ref_array *get_loose_refs(const char *submodule)
 336 {
 337         if (submodule) {
 338                 free_ref_array(&submodule_refs.loose);
 339                 get_ref_dir(submodule, "refs", &submodule_refs.loose);
 340                 sort_ref_array(&submodule_refs.loose);
 341                 return &submodule_refs.loose;
 342         }
 343
 344         if (!cached_refs.did_loose) {
 345                 get_ref_dir(NULL, "refs", &cached_refs.loose);
 346                 sort_ref_array(&cached_refs.loose);
 347                 cached_refs.did_loose = 1;
 348         }
 349         return &cached_refs.loose;
 350 }
 351
 352 /* We allow "recursive" symbolic refs. Only within reason, though */
 353 #define MAXDEPTH 5
 354 #define MAXREFLEN (1024)
 355
 356 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 357 {
 358         FILE *f;
 359         struct cached_refs refs;
 360         struct ref_entry *ref;
 361         int retval = -1;
 362
 363         strcpy(name + pathlen, "packed-refs");
 364         f = fopen(name, "r");
 365         if (!f)
 366                 return -1;
 367         memset(&refs, 0, sizeof(refs));
 368         read_packed_refs(f, &refs);
 369         fclose(f);
 370         ref = search_ref_array(&refs.packed, refname);
 371         if (ref != NULL) {
 372                 memcpy(result, ref->sha1, 20);
 373                 retval = 0;
 374         }
 375         free_ref_array(&refs.packed);
 376         return retval;
 377 }
 378
 379 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 380 {
 381         int fd, len = strlen(refname);
 382         char buffer[128], *p;
 383
 384         if (recursion > MAXDEPTH || len > MAXREFLEN)
 385                 return -1;
 386         memcpy(name + pathlen, refname, len+1);
 387         fd = open(name, O_RDONLY);
 388         if (fd < 0)
 389                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 390
 391         len = read(fd, buffer, sizeof(buffer)-1);
 392         close(fd);
 393         if (len < 0)
 394                 return -1;
 395         while (len && isspace(buffer[len-1]))
 396                 len--;
 397         buffer[len] = 0;
 398
 399         /* Was it a detached head or an old-fashioned symlink? */
 400         if (!get_sha1_hex(buffer, result))
 401                 return 0;
 402
 403         /* Symref? */
 404         if (strncmp(buffer, "ref:", 4))
 405                 return -1;
 406         p = buffer + 4;
 407         while (isspace(*p))
 408                 p++;
 409
 410         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 411 }
 412
 413 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 414 {
 415         int len = strlen(path), retval;
 416         char *gitdir;
 417         const char *tmp;
 418
 419         while (len && path[len-1] == '/')
 420                 len--;
 421         if (!len)
 422                 return -1;
 423         gitdir = xmalloc(len + MAXREFLEN + 8);
 424         memcpy(gitdir, path, len);
 425         memcpy(gitdir + len, "/.git", 6);
 426         len += 5;
 427
 428         tmp = read_gitfile_gently(gitdir);
 429         if (tmp) {
 430                 free(gitdir);
 431                 len = strlen(tmp);
 432                 gitdir = xmalloc(len + MAXREFLEN + 3);
 433                 memcpy(gitdir, tmp, len);
 434         }
 435         gitdir[len] = '/';
 436         gitdir[++len] = '\0';
 437         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 438         free(gitdir);
 439         return retval;
 440 }
 441
 442 /*
 443  * If the "reading" argument is set, this function finds out what _object_
 444  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
 445  * has to exist, and if it is symbolic, it has to point at an existing ref,
 446  * because the "read" goes through the symref to the ref it points at.
 447  *
 448  * The access that is not "reading" may often be "writing", but does not
 449  * have to; it can be merely checking _where it leads to_. If it is a
 450  * prelude to "writing" to the ref, a write to a symref that points at
 451  * yet-to-be-born ref will create the real ref pointed by the symref.
 452  * reading=0 allows the caller to check where such a symref leads to.
 453  */
 454 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 455 {
 456         int depth = MAXDEPTH;
 457         ssize_t len;
 458         char buffer[256];
 459         static char ref_buffer[256];
 460
 461         if (flag)
 462                 *flag = 0;
 463
 464         for (;;) {
 465                 char path[PATH_MAX];
 466                 struct stat st;
 467                 char *buf;
 468                 int fd;
 469
 470                 if (--depth < 0)
 471                         return NULL;
 472
 473                 git_snpath(path, sizeof(path), "%s", ref);
 474                 /* Special case: non-existing file. */
 475                 if (lstat(path, &st) < 0) {
 476                         struct ref_array *packed = get_packed_refs(NULL);
 477                         struct ref_entry *r = search_ref_array(packed, ref);
 478                         if (r != NULL) {
 479                                 hashcpy(sha1, r->sha1);
 480                                 if (flag)
 481                                         *flag |= REF_ISPACKED;
 482                                 return ref;
 483                         }
 484                         if (reading || errno != ENOENT)
 485                                 return NULL;
 486                         hashclr(sha1);
 487                         return ref;
 488                 }
 489
 490                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 491                 if (S_ISLNK(st.st_mode)) {
 492                         len = readlink(path, buffer, sizeof(buffer)-1);
 493                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 494                                 buffer[len] = 0;
 495                                 strcpy(ref_buffer, buffer);
 496                                 ref = ref_buffer;
 497                                 if (flag)
 498                                         *flag |= REF_ISSYMREF;
 499                                 continue;
 500                         }
 501                 }
 502
 503                 /* Is it a directory? */
 504                 if (S_ISDIR(st.st_mode)) {
 505                         errno = EISDIR;
 506                         return NULL;
 507                 }
 508
 509                 /*
 510                  * Anything else, just open it and try to use it as
 511                  * a ref
 512                  */
 513                 fd = open(path, O_RDONLY);
 514                 if (fd < 0)
 515                         return NULL;
 516                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 517                 close(fd);
 518
 519                 /*
 520                  * Is it a symbolic ref?
 521                  */
 522                 if (len < 4 || memcmp("ref:", buffer, 4))
 523                         break;
 524                 buf = buffer + 4;
 525                 len -= 4;
 526                 while (len && isspace(*buf))
 527                         buf++, len--;
 528                 while (len && isspace(buf[len-1]))
 529                         len--;
 530                 buf[len] = 0;
 531                 memcpy(ref_buffer, buf, len + 1);
 532                 ref = ref_buffer;
 533                 if (flag)
 534                         *flag |= REF_ISSYMREF;
 535         }
 536         if (len < 40 || get_sha1_hex(buffer, sha1))
 537                 return NULL;
 538         return ref;
 539 }
 540
 541 /* The argument to filter_refs */
 542 struct ref_filter {
 543         const char *pattern;
 544         each_ref_fn *fn;
 545         void *cb_data;
 546 };
 547
 548 int read_ref(const char *ref, unsigned char *sha1)
 549 {
 550         if (resolve_ref(ref, sha1, 1, NULL))
 551                 return 0;
 552         return -1;
 553 }
 554
 555 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 556 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 557                       int flags, void *cb_data, struct ref_entry *entry)
 558 {
 559         if (strncmp(base, entry->name, trim))
 560                 return 0;
 561
 562         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 563                 if (entry->flag & REF_BROKEN)
 564                         return 0; /* ignore dangling symref */
 565                 if (!has_sha1_file(entry->sha1)) {
 566                         error("%s does not point to a valid object!", entry->name);
 567                         return 0;
 568                 }
 569         }
 570         current_ref = entry;
 571         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 572 }
 573
 574 static int filter_refs(const char *ref, const unsigned char *sha, int flags,
 575         void *data)
 576 {
 577         struct ref_filter *filter = (struct ref_filter *)data;
 578         if (fnmatch(filter->pattern, ref, 0))
 579                 return 0;
 580         return filter->fn(ref, sha, flags, filter->cb_data);
 581 }
 582
 583 int peel_ref(const char *ref, unsigned char *sha1)
 584 {
 585         int flag;
 586         unsigned char base[20];
 587         struct object *o;
 588
 589         if (current_ref && (current_ref->name == ref
 590                 || !strcmp(current_ref->name, ref))) {
 591                 if (current_ref->flag & REF_KNOWS_PEELED) {
 592                         hashcpy(sha1, current_ref->peeled);
 593                         return 0;
 594                 }
 595                 hashcpy(base, current_ref->sha1);
 596                 goto fallback;
 597         }
 598
 599         if (!resolve_ref(ref, base, 1, &flag))
 600                 return -1;
 601
 602         if ((flag & REF_ISPACKED)) {
 603                 struct ref_array *array = get_packed_refs(NULL);
 604                 struct ref_entry *r = search_ref_array(array, ref);
 605
 606                 if (r != NULL && r->flag & REF_KNOWS_PEELED) {
 607                         hashcpy(sha1, r->peeled);
 608                         return 0;
 609                 }
 610         }
 611
 612 fallback:
 613         o = parse_object(base);
 614         if (o && o->type == OBJ_TAG) {
 615                 o = deref_tag(o, ref, 0);
 616                 if (o) {
 617                         hashcpy(sha1, o->sha1);
 618                         return 0;
 619                 }
 620         }
 621         return -1;
 622 }
 623
 624 static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
 625                            int trim, int flags, void *cb_data)
 626 {
 627         int retval = 0, i, p = 0, l = 0;
 628         struct ref_array *packed = get_packed_refs(submodule);
 629         struct ref_array *loose = get_loose_refs(submodule);
 630
 631         struct ref_array *extra = &extra_refs;
 632
 633         for (i = 0; i < extra->nr; i++)
 634                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra->refs[i]);
 635
 636         while (p < packed->nr && l < loose->nr) {
 637                 struct ref_entry *entry;
 638                 int cmp = strcmp(packed->refs[p]->name, loose->refs[l]->name);
 639                 if (!cmp) {
 640                         p++;
 641                         continue;
 642                 }
 643                 if (cmp > 0) {
 644                         entry = loose->refs[l++];
 645                 } else {
 646                         entry = packed->refs[p++];
 647                 }
 648                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 649                 if (retval)
 650                         goto end_each;
 651         }
 652
 653         if (l < loose->nr) {
 654                 p = l;
 655                 packed = loose;
 656         }
 657
 658         for (; p < packed->nr; p++) {
 659                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed->refs[p]);
 660                 if (retval)
 661                         goto end_each;
 662         }
 663
 664 end_each:
 665         current_ref = NULL;
 666         return retval;
 667 }
 668
 669
 670 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 671 {
 672         unsigned char sha1[20];
 673         int flag;
 674
 675         if (submodule) {
 676                 if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
 677                         return fn("HEAD", sha1, 0, cb_data);
 678
 679                 return 0;
 680         }
 681
 682         if (resolve_ref("HEAD", sha1, 1, &flag))
 683                 return fn("HEAD", sha1, flag, cb_data);
 684
 685         return 0;
 686 }
 687
 688 int head_ref(each_ref_fn fn, void *cb_data)
 689 {
 690         return do_head_ref(NULL, fn, cb_data);
 691 }
 692
 693 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 694 {
 695         return do_head_ref(submodule, fn, cb_data);
 696 }
 697
 698 int for_each_ref(each_ref_fn fn, void *cb_data)
 699 {
 700         return do_for_each_ref(NULL, "refs/", fn, 0, 0, cb_data);
 701 }
 702
 703 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 704 {
 705         return do_for_each_ref(submodule, "refs/", fn, 0, 0, cb_data);
 706 }
 707
 708 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 709 {
 710         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
 711 }
 712
 713 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 714                 each_ref_fn fn, void *cb_data)
 715 {
 716         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
 717 }
 718
 719 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 720 {
 721         return for_each_ref_in("refs/tags/", fn, cb_data);
 722 }
 723
 724 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 725 {
 726         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 727 }
 728
 729 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 730 {
 731         return for_each_ref_in("refs/heads/", fn, cb_data);
 732 }
 733
 734 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 735 {
 736         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 737 }
 738
 739 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 740 {
 741         return for_each_ref_in("refs/remotes/", fn, cb_data);
 742 }
 743
 744 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 745 {
 746         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 747 }
 748
 749 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 750 {
 751         return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
 752 }
 753
 754 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 755         const char *prefix, void *cb_data)
 756 {
 757         struct strbuf real_pattern = STRBUF_INIT;
 758         struct ref_filter filter;
 759         int ret;
 760
 761         if (!prefix && prefixcmp(pattern, "refs/"))
 762                 strbuf_addstr(&real_pattern, "refs/");
 763         else if (prefix)
 764                 strbuf_addstr(&real_pattern, prefix);
 765         strbuf_addstr(&real_pattern, pattern);
 766
 767         if (!has_glob_specials(pattern)) {
 768                 /* Append implied '/' '*' if not present. */
 769                 if (real_pattern.buf[real_pattern.len - 1] != '/')
 770                         strbuf_addch(&real_pattern, '/');
 771                 /* No need to check for '*', there is none. */
 772                 strbuf_addch(&real_pattern, '*');
 773         }
 774
 775         filter.pattern = real_pattern.buf;
 776         filter.fn = fn;
 777         filter.cb_data = cb_data;
 778         ret = for_each_ref(filter_refs, &filter);
 779
 780         strbuf_release(&real_pattern);
 781         return ret;
 782 }
 783
 784 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 785 {
 786         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 787 }
 788
 789 int for_each_rawref(each_ref_fn fn, void *cb_data)
 790 {
 791         return do_for_each_ref(NULL, "refs/", fn, 0,
 792                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 793 }
 794
 795 /*
 796  * Make sure "ref" is something reasonable to have under ".git/refs/";
 797  * We do not like it if:
 798  *
 799  * - any path component of it begins with ".", or
 800  * - it has double dots "..", or
 801  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 802  * - it ends with a "/".
 803  * - it ends with ".lock"
 804  * - it contains a "\" (backslash)
 805  */
 806
 807 static inline int bad_ref_char(int ch)
 808 {
 809         if (((unsigned) ch) <= ' ' ||
 810             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 811                 return 1;
 812         /* 2.13 Pattern Matching Notation */
 813         if (ch == '?' || ch == '[') /* Unsupported */
 814                 return 1;
 815         if (ch == '*') /* Supported at the end */
 816                 return 2;
 817         return 0;
 818 }
 819
 820 int check_ref_format(const char *ref)
 821 {
 822         int ch, level, bad_type, last;
 823         int ret = CHECK_REF_FORMAT_OK;
 824         const char *cp = ref;
 825
 826         level = 0;
 827         while (1) {
 828                 while ((ch = *cp++) == '/')
 829                         ; /* tolerate duplicated slashes */
 830                 if (!ch)
 831                         /* should not end with slashes */
 832                         return CHECK_REF_FORMAT_ERROR;
 833
 834                 /* we are at the beginning of the path component */
 835                 if (ch == '.')
 836                         return CHECK_REF_FORMAT_ERROR;
 837                 bad_type = bad_ref_char(ch);
 838                 if (bad_type) {
 839                         if (bad_type == 2 && (!*cp || *cp == '/') &&
 840                             ret == CHECK_REF_FORMAT_OK)
 841                                 ret = CHECK_REF_FORMAT_WILDCARD;
 842                         else
 843                                 return CHECK_REF_FORMAT_ERROR;
 844                 }
 845
 846                 last = ch;
 847                 /* scan the rest of the path component */
 848                 while ((ch = *cp++) != 0) {
 849                         bad_type = bad_ref_char(ch);
 850                         if (bad_type)
 851                                 return CHECK_REF_FORMAT_ERROR;
 852                         if (ch == '/')
 853                                 break;
 854                         if (last == '.' && ch == '.')
 855                                 return CHECK_REF_FORMAT_ERROR;
 856                         if (last == '@' && ch == '{')
 857                                 return CHECK_REF_FORMAT_ERROR;
 858                         last = ch;
 859                 }
 860                 level++;
 861                 if (!ch) {
 862                         if (ref <= cp - 2 && cp[-2] == '.')
 863                                 return CHECK_REF_FORMAT_ERROR;
 864                         if (level < 2)
 865                                 return CHECK_REF_FORMAT_ONELEVEL;
 866                         if (has_extension(ref, ".lock"))
 867                                 return CHECK_REF_FORMAT_ERROR;
 868                         return ret;
 869                 }
 870         }
 871 }
 872
 873 const char *prettify_refname(const char *name)
 874 {
 875         return name + (
 876                 !prefixcmp(name, "refs/heads/") ? 11 :
 877                 !prefixcmp(name, "refs/tags/") ? 10 :
 878                 !prefixcmp(name, "refs/remotes/") ? 13 :
 879                 0);
 880 }
 881
 882 const char *ref_rev_parse_rules[] = {
 883         "%.*s",
 884         "refs/%.*s",
 885         "refs/tags/%.*s",
 886         "refs/heads/%.*s",
 887         "refs/remotes/%.*s",
 888         "refs/remotes/%.*s/HEAD",
 889         NULL
 890 };
 891
 892 const char *ref_fetch_rules[] = {
 893         "%.*s",
 894         "refs/%.*s",
 895         "refs/heads/%.*s",
 896         NULL
 897 };
 898
 899 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 900 {
 901         const char **p;
 902         const int abbrev_name_len = strlen(abbrev_name);
 903
 904         for (p = rules; *p; p++) {
 905                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 906                         return 1;
 907                 }
 908         }
 909
 910         return 0;
 911 }
 912
 913 static struct ref_lock *verify_lock(struct ref_lock *lock,
 914         const unsigned char *old_sha1, int mustexist)
 915 {
 916         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 917                 error("Can't verify ref %s", lock->ref_name);
 918                 unlock_ref(lock);
 919                 return NULL;
 920         }
 921         if (hashcmp(lock->old_sha1, old_sha1)) {
 922                 error("Ref %s is at %s but expected %s", lock->ref_name,
 923                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 924                 unlock_ref(lock);
 925                 return NULL;
 926         }
 927         return lock;
 928 }
 929
 930 static int remove_empty_directories(const char *file)
 931 {
 932         /* we want to create a file but there is a directory there;
 933          * if that is an empty directory (or a directory that contains
 934          * only empty directories), remove them.
 935          */
 936         struct strbuf path;
 937         int result;
 938
 939         strbuf_init(&path, 20);
 940         strbuf_addstr(&path, file);
 941
 942         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
 943
 944         strbuf_release(&path);
 945
 946         return result;
 947 }
 948
 949 static int is_refname_available(const char *ref, const char *oldref,
 950                                 struct ref_array *array, int quiet)
 951 {
 952         int i, namlen = strlen(ref); /* e.g. 'foo/bar' */
 953         for (i = 0; i < array->nr; i++ ) {
 954                 struct ref_entry *entry = array->refs[i];
 955                 /* entry->name could be 'foo' or 'foo/bar/baz' */
 956                 if (!oldref || strcmp(oldref, entry->name)) {
 957                         int len = strlen(entry->name);
 958                         int cmplen = (namlen < len) ? namlen : len;
 959                         const char *lead = (namlen < len) ? entry->name : ref;
 960                         if (!strncmp(ref, entry->name, cmplen) &&
 961                             lead[cmplen] == '/') {
 962                                 if (!quiet)
 963                                         error("'%s' exists; cannot create '%s'",
 964                                               entry->name, ref);
 965                                 return 0;
 966                         }
 967                 }
 968         }
 969         return 1;
 970 }
 971
 972 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 973 {
 974         char *ref_file;
 975         const char *orig_ref = ref;
 976         struct ref_lock *lock;
 977         int last_errno = 0;
 978         int type, lflags;
 979         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 980         int missing = 0;
 981
 982         lock = xcalloc(1, sizeof(struct ref_lock));
 983         lock->lock_fd = -1;
 984
 985         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
 986         if (!ref && errno == EISDIR) {
 987                 /* we are trying to lock foo but we used to
 988                  * have foo/bar which now does not exist;
 989                  * it is normal for the empty directory 'foo'
 990                  * to remain.
 991                  */
 992                 ref_file = git_path("%s", orig_ref);
 993                 if (remove_empty_directories(ref_file)) {
 994                         last_errno = errno;
 995                         error("there are still refs under '%s'", orig_ref);
 996                         goto error_return;
 997                 }
 998                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
 999         }
1000         if (type_p)
1001             *type_p = type;
1002         if (!ref) {
1003                 last_errno = errno;
1004                 error("unable to resolve reference %s: %s",
1005                         orig_ref, strerror(errno));
1006                 goto error_return;
1007         }
1008         missing = is_null_sha1(lock->old_sha1);
1009         /* When the ref did not exist and we are creating it,
1010          * make sure there is no existing ref that is packed
1011          * whose name begins with our refname, nor a ref whose
1012          * name is a proper prefix of our refname.
1013          */
1014         if (missing &&
1015              !is_refname_available(ref, NULL, get_packed_refs(NULL), 0)) {
1016                 last_errno = ENOTDIR;
1017                 goto error_return;
1018         }
1019
1020         lock->lk = xcalloc(1, sizeof(struct lock_file));
1021
1022         lflags = LOCK_DIE_ON_ERROR;
1023         if (flags & REF_NODEREF) {
1024                 ref = orig_ref;
1025                 lflags |= LOCK_NODEREF;
1026         }
1027         lock->ref_name = xstrdup(ref);
1028         lock->orig_ref_name = xstrdup(orig_ref);
1029         ref_file = git_path("%s", ref);
1030         if (missing)
1031                 lock->force_write = 1;
1032         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1033                 lock->force_write = 1;
1034
1035         if (safe_create_leading_directories(ref_file)) {
1036                 last_errno = errno;
1037                 error("unable to create directory for %s", ref_file);
1038                 goto error_return;
1039         }
1040
1041         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1042         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1043
1044  error_return:
1045         unlock_ref(lock);
1046         errno = last_errno;
1047         return NULL;
1048 }
1049
1050 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
1051 {
1052         char refpath[PATH_MAX];
1053         if (check_ref_format(ref))
1054                 return NULL;
1055         strcpy(refpath, mkpath("refs/%s", ref));
1056         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1057 }
1058
1059 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
1060 {
1061         switch (check_ref_format(ref)) {
1062         default:
1063                 return NULL;
1064         case 0:
1065         case CHECK_REF_FORMAT_ONELEVEL:
1066                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
1067         }
1068 }
1069
1070 static struct lock_file packlock;
1071
1072 static int repack_without_ref(const char *refname)
1073 {
1074         struct ref_array *packed;
1075         struct ref_entry *ref;
1076         int fd, i;
1077
1078         packed = get_packed_refs(NULL);
1079         ref = search_ref_array(packed, refname);
1080         if (ref == NULL)
1081                 return 0;
1082         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1083         if (fd < 0) {
1084                 unable_to_lock_error(git_path("packed-refs"), errno);
1085                 return error("cannot delete '%s' from packed refs", refname);
1086         }
1087
1088         for (i = 0; i < packed->nr; i++) {
1089                 char line[PATH_MAX + 100];
1090                 int len;
1091
1092                 ref = packed->refs[i];
1093
1094                 if (!strcmp(refname, ref->name))
1095                         continue;
1096                 len = snprintf(line, sizeof(line), "%s %s\n",
1097                                sha1_to_hex(ref->sha1), ref->name);
1098                 /* this should not happen but just being defensive */
1099                 if (len > sizeof(line))
1100                         die("too long a refname '%s'", ref->name);
1101                 write_or_die(fd, line, len);
1102         }
1103         return commit_lock_file(&packlock);
1104 }
1105
1106 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1107 {
1108         struct ref_lock *lock;
1109         int err, i = 0, ret = 0, flag = 0;
1110
1111         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1112         if (!lock)
1113                 return 1;
1114         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1115                 /* loose */
1116                 const char *path;
1117
1118                 if (!(delopt & REF_NODEREF)) {
1119                         i = strlen(lock->lk->filename) - 5; /* .lock */
1120                         lock->lk->filename[i] = 0;
1121                         path = lock->lk->filename;
1122                 } else {
1123                         path = git_path("%s", refname);
1124                 }
1125                 err = unlink_or_warn(path);
1126                 if (err && errno != ENOENT)
1127                         ret = 1;
1128
1129                 if (!(delopt & REF_NODEREF))
1130                         lock->lk->filename[i] = '.';
1131         }
1132         /* removing the loose one could have resurrected an earlier
1133          * packed one.  Also, if it was not loose we need to repack
1134          * without it.
1135          */
1136         ret |= repack_without_ref(refname);
1137
1138         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1139         invalidate_cached_refs();
1140         unlock_ref(lock);
1141         return ret;
1142 }
1143
1144 /*
1145  * People using contrib's git-new-workdir have .git/logs/refs ->
1146  * /some/other/path/.git/logs/refs, and that may live on another device.
1147  *
1148  * IOW, to avoid cross device rename errors, the temporary renamed log must
1149  * live into logs/refs.
1150  */
1151 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1152
1153 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1154 {
1155         static const char renamed_ref[] = "RENAMED-REF";
1156         unsigned char sha1[20], orig_sha1[20];
1157         int flag = 0, logmoved = 0;
1158         struct ref_lock *lock;
1159         struct stat loginfo;
1160         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1161         const char *symref = NULL;
1162
1163         if (log && S_ISLNK(loginfo.st_mode))
1164                 return error("reflog for %s is a symlink", oldref);
1165
1166         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1167         if (flag & REF_ISSYMREF)
1168                 return error("refname %s is a symbolic ref, renaming it is not supported",
1169                         oldref);
1170         if (!symref)
1171                 return error("refname %s not found", oldref);
1172
1173         if (!is_refname_available(newref, oldref, get_packed_refs(NULL), 0))
1174                 return 1;
1175
1176         if (!is_refname_available(newref, oldref, get_loose_refs(NULL), 0))
1177                 return 1;
1178
1179         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1180         if (!lock)
1181                 return error("unable to lock %s", renamed_ref);
1182         lock->force_write = 1;
1183         if (write_ref_sha1(lock, orig_sha1, logmsg))
1184                 return error("unable to save current sha1 in %s", renamed_ref);
1185
1186         if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
1187                 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1188                         oldref, strerror(errno));
1189
1190         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1191                 error("unable to delete old %s", oldref);
1192                 goto rollback;
1193         }
1194
1195         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1196                 if (errno==EISDIR) {
1197                         if (remove_empty_directories(git_path("%s", newref))) {
1198                                 error("Directory not empty: %s", newref);
1199                                 goto rollback;
1200                         }
1201                 } else {
1202                         error("unable to delete existing %s", newref);
1203                         goto rollback;
1204                 }
1205         }
1206
1207         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1208                 error("unable to create directory for %s", newref);
1209                 goto rollback;
1210         }
1211
1212  retry:
1213         if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
1214                 if (errno==EISDIR || errno==ENOTDIR) {
1215                         /*
1216                          * rename(a, b) when b is an existing
1217                          * directory ought to result in ISDIR, but
1218                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1219                          */
1220                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1221                                 error("Directory not empty: logs/%s", newref);
1222                                 goto rollback;
1223                         }
1224                         goto retry;
1225                 } else {
1226                         error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1227                                 newref, strerror(errno));
1228                         goto rollback;
1229                 }
1230         }
1231         logmoved = log;
1232
1233         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1234         if (!lock) {
1235                 error("unable to lock %s for update", newref);
1236                 goto rollback;
1237         }
1238         lock->force_write = 1;
1239         hashcpy(lock->old_sha1, orig_sha1);
1240         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1241                 error("unable to write current sha1 into %s", newref);
1242                 goto rollback;
1243         }
1244
1245         return 0;
1246
1247  rollback:
1248         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1249         if (!lock) {
1250                 error("unable to lock %s for rollback", oldref);
1251                 goto rollbacklog;
1252         }
1253
1254         lock->force_write = 1;
1255         flag = log_all_ref_updates;
1256         log_all_ref_updates = 0;
1257         if (write_ref_sha1(lock, orig_sha1, NULL))
1258                 error("unable to write current sha1 into %s", oldref);
1259         log_all_ref_updates = flag;
1260
1261  rollbacklog:
1262         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1263                 error("unable to restore logfile %s from %s: %s",
1264                         oldref, newref, strerror(errno));
1265         if (!logmoved && log &&
1266             rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
1267                 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1268                         oldref, strerror(errno));
1269
1270         return 1;
1271 }
1272
1273 int close_ref(struct ref_lock *lock)
1274 {
1275         if (close_lock_file(lock->lk))
1276                 return -1;
1277         lock->lock_fd = -1;
1278         return 0;
1279 }
1280
1281 int commit_ref(struct ref_lock *lock)
1282 {
1283         if (commit_lock_file(lock->lk))
1284                 return -1;
1285         lock->lock_fd = -1;
1286         return 0;
1287 }
1288
1289 void unlock_ref(struct ref_lock *lock)
1290 {
1291         /* Do not free lock->lk -- atexit() still looks at them */
1292         if (lock->lk)
1293                 rollback_lock_file(lock->lk);
1294         free(lock->ref_name);
1295         free(lock->orig_ref_name);
1296         free(lock);
1297 }
1298
1299 /*
1300  * copy the reflog message msg to buf, which has been allocated sufficiently
1301  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1302  * because reflog file is one line per entry.
1303  */
1304 static int copy_msg(char *buf, const char *msg)
1305 {
1306         char *cp = buf;
1307         char c;
1308         int wasspace = 1;
1309
1310         *cp++ = '\t';
1311         while ((c = *msg++)) {
1312                 if (wasspace && isspace(c))
1313                         continue;
1314                 wasspace = isspace(c);
1315                 if (wasspace)
1316                         c = ' ';
1317                 *cp++ = c;
1318         }
1319         while (buf < cp && isspace(cp[-1]))
1320                 cp--;
1321         *cp++ = '\n';
1322         return cp - buf;
1323 }
1324
1325 int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
1326 {
1327         int logfd, oflags = O_APPEND | O_WRONLY;
1328
1329         git_snpath(logfile, bufsize, "logs/%s", ref_name);
1330         if (log_all_ref_updates &&
1331             (!prefixcmp(ref_name, "refs/heads/") ||
1332              !prefixcmp(ref_name, "refs/remotes/") ||
1333              !prefixcmp(ref_name, "refs/notes/") ||
1334              !strcmp(ref_name, "HEAD"))) {
1335                 if (safe_create_leading_directories(logfile) < 0)
1336                         return error("unable to create directory for %s",
1337                                      logfile);
1338                 oflags |= O_CREAT;
1339         }
1340
1341         logfd = open(logfile, oflags, 0666);
1342         if (logfd < 0) {
1343                 if (!(oflags & O_CREAT) && errno == ENOENT)
1344                         return 0;
1345
1346                 if ((oflags & O_CREAT) && errno == EISDIR) {
1347                         if (remove_empty_directories(logfile)) {
1348                                 return error("There are still logs under '%s'",
1349                                              logfile);
1350                         }
1351                         logfd = open(logfile, oflags, 0666);
1352                 }
1353
1354                 if (logfd < 0)
1355                         return error("Unable to append to %s: %s",
1356                                      logfile, strerror(errno));
1357         }
1358
1359         adjust_shared_perm(logfile);
1360         close(logfd);
1361         return 0;
1362 }
1363
1364 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1365                          const unsigned char *new_sha1, const char *msg)
1366 {
1367         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1368         unsigned maxlen, len;
1369         int msglen;
1370         char log_file[PATH_MAX];
1371         char *logrec;
1372         const char *committer;
1373
1374         if (log_all_ref_updates < 0)
1375                 log_all_ref_updates = !is_bare_repository();
1376
1377         result = log_ref_setup(ref_name, log_file, sizeof(log_file));
1378         if (result)
1379                 return result;
1380
1381         logfd = open(log_file, oflags);
1382         if (logfd < 0)
1383                 return 0;
1384         msglen = msg ? strlen(msg) : 0;
1385         committer = git_committer_info(0);
1386         maxlen = strlen(committer) + msglen + 100;
1387         logrec = xmalloc(maxlen);
1388         len = sprintf(logrec, "%s %s %s\n",
1389                       sha1_to_hex(old_sha1),
1390                       sha1_to_hex(new_sha1),
1391                       committer);
1392         if (msglen)
1393                 len += copy_msg(logrec + len - 1, msg) - 1;
1394         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1395         free(logrec);
1396         if (close(logfd) != 0 || written != len)
1397                 return error("Unable to append to %s", log_file);
1398         return 0;
1399 }
1400
1401 static int is_branch(const char *refname)
1402 {
1403         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1404 }
1405
1406 int write_ref_sha1(struct ref_lock *lock,
1407         const unsigned char *sha1, const char *logmsg)
1408 {
1409         static char term = '\n';
1410         struct object *o;
1411
1412         if (!lock)
1413                 return -1;
1414         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1415                 unlock_ref(lock);
1416                 return 0;
1417         }
1418         o = parse_object(sha1);
1419         if (!o) {
1420                 error("Trying to write ref %s with nonexistant object %s",
1421                         lock->ref_name, sha1_to_hex(sha1));
1422                 unlock_ref(lock);
1423                 return -1;
1424         }
1425         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1426                 error("Trying to write non-commit object %s to branch %s",
1427                         sha1_to_hex(sha1), lock->ref_name);
1428                 unlock_ref(lock);
1429                 return -1;
1430         }
1431         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1432             write_in_full(lock->lock_fd, &term, 1) != 1
1433                 || close_ref(lock) < 0) {
1434                 error("Couldn't write %s", lock->lk->filename);
1435                 unlock_ref(lock);
1436                 return -1;
1437         }
1438         invalidate_cached_refs();
1439         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1440             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1441              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1442                 unlock_ref(lock);
1443                 return -1;
1444         }
1445         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1446                 /*
1447                  * Special hack: If a branch is updated directly and HEAD
1448                  * points to it (may happen on the remote side of a push
1449                  * for example) then logically the HEAD reflog should be
1450                  * updated too.
1451                  * A generic solution implies reverse symref information,
1452                  * but finding all symrefs pointing to the given branch
1453                  * would be rather costly for this rare event (the direct
1454                  * update of a branch) to be worth it.  So let's cheat and
1455                  * check with HEAD only which should cover 99% of all usage
1456                  * scenarios (even 100% of the default ones).
1457                  */
1458                 unsigned char head_sha1[20];
1459                 int head_flag;
1460                 const char *head_ref;
1461                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1462                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1463                     !strcmp(head_ref, lock->ref_name))
1464                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1465         }
1466         if (commit_ref(lock)) {
1467                 error("Couldn't set %s", lock->ref_name);
1468                 unlock_ref(lock);
1469                 return -1;
1470         }
1471         unlock_ref(lock);
1472         return 0;
1473 }
1474
1475 int create_symref(const char *ref_target, const char *refs_heads_master,
1476                   const char *logmsg)
1477 {
1478         const char *lockpath;
1479         char ref[1000];
1480         int fd, len, written;
1481         char *git_HEAD = git_pathdup("%s", ref_target);
1482         unsigned char old_sha1[20], new_sha1[20];
1483
1484         if (logmsg && read_ref(ref_target, old_sha1))
1485                 hashclr(old_sha1);
1486
1487         if (safe_create_leading_directories(git_HEAD) < 0)
1488                 return error("unable to create directory for %s", git_HEAD);
1489
1490 #ifndef NO_SYMLINK_HEAD
1491         if (prefer_symlink_refs) {
1492                 unlink(git_HEAD);
1493                 if (!symlink(refs_heads_master, git_HEAD))
1494                         goto done;
1495                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1496         }
1497 #endif
1498
1499         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1500         if (sizeof(ref) <= len) {
1501                 error("refname too long: %s", refs_heads_master);
1502                 goto error_free_return;
1503         }
1504         lockpath = mkpath("%s.lock", git_HEAD);
1505         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1506         if (fd < 0) {
1507                 error("Unable to open %s for writing", lockpath);
1508                 goto error_free_return;
1509         }
1510         written = write_in_full(fd, ref, len);
1511         if (close(fd) != 0 || written != len) {
1512                 error("Unable to write to %s", lockpath);
1513                 goto error_unlink_return;
1514         }
1515         if (rename(lockpath, git_HEAD) < 0) {
1516                 error("Unable to create %s", git_HEAD);
1517                 goto error_unlink_return;
1518         }
1519         if (adjust_shared_perm(git_HEAD)) {
1520                 error("Unable to fix permissions on %s", lockpath);
1521         error_unlink_return:
1522                 unlink_or_warn(lockpath);
1523         error_free_return:
1524                 free(git_HEAD);
1525                 return -1;
1526         }
1527
1528 #ifndef NO_SYMLINK_HEAD
1529         done:
1530 #endif
1531         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1532                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1533
1534         free(git_HEAD);
1535         return 0;
1536 }
1537
1538 static char *ref_msg(const char *line, const char *endp)
1539 {
1540         const char *ep;
1541         line += 82;
1542         ep = memchr(line, '\n', endp - line);
1543         if (!ep)
1544                 ep = endp;
1545         return xmemdupz(line, ep - line);
1546 }
1547
1548 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)
1549 {
1550         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1551         char *tz_c;
1552         int logfd, tz, reccnt = 0;
1553         struct stat st;
1554         unsigned long date;
1555         unsigned char logged_sha1[20];
1556         void *log_mapped;
1557         size_t mapsz;
1558
1559         logfile = git_path("logs/%s", ref);
1560         logfd = open(logfile, O_RDONLY, 0);
1561         if (logfd < 0)
1562                 die_errno("Unable to read log '%s'", logfile);
1563         fstat(logfd, &st);
1564         if (!st.st_size)
1565                 die("Log %s is empty.", logfile);
1566         mapsz = xsize_t(st.st_size);
1567         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1568         logdata = log_mapped;
1569         close(logfd);
1570
1571         lastrec = NULL;
1572         rec = logend = logdata + st.st_size;
1573         while (logdata < rec) {
1574                 reccnt++;
1575                 if (logdata < rec && *(rec-1) == '\n')
1576                         rec--;
1577                 lastgt = NULL;
1578                 while (logdata < rec && *(rec-1) != '\n') {
1579                         rec--;
1580                         if (*rec == '>')
1581                                 lastgt = rec;
1582                 }
1583                 if (!lastgt)
1584                         die("Log %s is corrupt.", logfile);
1585                 date = strtoul(lastgt + 1, &tz_c, 10);
1586                 if (date <= at_time || cnt == 0) {
1587                         tz = strtoul(tz_c, NULL, 10);
1588                         if (msg)
1589                                 *msg = ref_msg(rec, logend);
1590                         if (cutoff_time)
1591                                 *cutoff_time = date;
1592                         if (cutoff_tz)
1593                                 *cutoff_tz = tz;
1594                         if (cutoff_cnt)
1595                                 *cutoff_cnt = reccnt - 1;
1596                         if (lastrec) {
1597                                 if (get_sha1_hex(lastrec, logged_sha1))
1598                                         die("Log %s is corrupt.", logfile);
1599                                 if (get_sha1_hex(rec + 41, sha1))
1600                                         die("Log %s is corrupt.", logfile);
1601                                 if (hashcmp(logged_sha1, sha1)) {
1602                                         warning("Log %s has gap after %s.",
1603                                                 logfile, show_date(date, tz, DATE_RFC2822));
1604                                 }
1605                         }
1606                         else if (date == at_time) {
1607                                 if (get_sha1_hex(rec + 41, sha1))
1608                                         die("Log %s is corrupt.", logfile);
1609                         }
1610                         else {
1611                                 if (get_sha1_hex(rec + 41, logged_sha1))
1612                                         die("Log %s is corrupt.", logfile);
1613                                 if (hashcmp(logged_sha1, sha1)) {
1614                                         warning("Log %s unexpectedly ended on %s.",
1615                                                 logfile, show_date(date, tz, DATE_RFC2822));
1616                                 }
1617                         }
1618                         munmap(log_mapped, mapsz);
1619                         return 0;
1620                 }
1621                 lastrec = rec;
1622                 if (cnt > 0)
1623                         cnt--;
1624         }
1625
1626         rec = logdata;
1627         while (rec < logend && *rec != '>' && *rec != '\n')
1628                 rec++;
1629         if (rec == logend || *rec == '\n')
1630                 die("Log %s is corrupt.", logfile);
1631         date = strtoul(rec + 1, &tz_c, 10);
1632         tz = strtoul(tz_c, NULL, 10);
1633         if (get_sha1_hex(logdata, sha1))
1634                 die("Log %s is corrupt.", logfile);
1635         if (is_null_sha1(sha1)) {
1636                 if (get_sha1_hex(logdata + 41, sha1))
1637                         die("Log %s is corrupt.", logfile);
1638         }
1639         if (msg)
1640                 *msg = ref_msg(logdata, logend);
1641         munmap(log_mapped, mapsz);
1642
1643         if (cutoff_time)
1644                 *cutoff_time = date;
1645         if (cutoff_tz)
1646                 *cutoff_tz = tz;
1647         if (cutoff_cnt)
1648                 *cutoff_cnt = reccnt;
1649         return 1;
1650 }
1651
1652 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1653 {
1654         const char *logfile;
1655         FILE *logfp;
1656         struct strbuf sb = STRBUF_INIT;
1657         int ret = 0;
1658
1659         logfile = git_path("logs/%s", ref);
1660         logfp = fopen(logfile, "r");
1661         if (!logfp)
1662                 return -1;
1663
1664         if (ofs) {
1665                 struct stat statbuf;
1666                 if (fstat(fileno(logfp), &statbuf) ||
1667                     statbuf.st_size < ofs ||
1668                     fseek(logfp, -ofs, SEEK_END) ||
1669                     strbuf_getwholeline(&sb, logfp, '\n')) {
1670                         fclose(logfp);
1671                         strbuf_release(&sb);
1672                         return -1;
1673                 }
1674         }
1675
1676         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1677                 unsigned char osha1[20], nsha1[20];
1678                 char *email_end, *message;
1679                 unsigned long timestamp;
1680                 int tz;
1681
1682                 /* old SP new SP name <email> SP time TAB msg LF */
1683                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1684                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1685                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1686                     !(email_end = strchr(sb.buf + 82, '>')) ||
1687                     email_end[1] != ' ' ||
1688                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1689                     !message || message[0] != ' ' ||
1690                     (message[1] != '+' && message[1] != '-') ||
1691                     !isdigit(message[2]) || !isdigit(message[3]) ||
1692                     !isdigit(message[4]) || !isdigit(message[5]))
1693                         continue; /* corrupt? */
1694                 email_end[1] = '\0';
1695                 tz = strtol(message + 1, NULL, 10);
1696                 if (message[6] != '\t')
1697                         message += 6;
1698                 else
1699                         message += 7;
1700                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1701                          cb_data);
1702                 if (ret)
1703                         break;
1704         }
1705         fclose(logfp);
1706         strbuf_release(&sb);
1707         return ret;
1708 }
1709
1710 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1711 {
1712         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1713 }
1714
1715 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1716 {
1717         DIR *dir = opendir(git_path("logs/%s", base));
1718         int retval = 0;
1719
1720         if (dir) {
1721                 struct dirent *de;
1722                 int baselen = strlen(base);
1723                 char *log = xmalloc(baselen + 257);
1724
1725                 memcpy(log, base, baselen);
1726                 if (baselen && base[baselen-1] != '/')
1727                         log[baselen++] = '/';
1728
1729                 while ((de = readdir(dir)) != NULL) {
1730                         struct stat st;
1731                         int namelen;
1732
1733                         if (de->d_name[0] == '.')
1734                                 continue;
1735                         namelen = strlen(de->d_name);
1736                         if (namelen > 255)
1737                                 continue;
1738                         if (has_extension(de->d_name, ".lock"))
1739                                 continue;
1740                         memcpy(log + baselen, de->d_name, namelen+1);
1741                         if (stat(git_path("logs/%s", log), &st) < 0)
1742                                 continue;
1743                         if (S_ISDIR(st.st_mode)) {
1744                                 retval = do_for_each_reflog(log, fn, cb_data);
1745                         } else {
1746                                 unsigned char sha1[20];
1747                                 if (!resolve_ref(log, sha1, 0, NULL))
1748                                         retval = error("bad ref for %s", log);
1749                                 else
1750                                         retval = fn(log, sha1, 0, cb_data);
1751                         }
1752                         if (retval)
1753                                 break;
1754                 }
1755                 free(log);
1756                 closedir(dir);
1757         }
1758         else if (*base)
1759                 return errno;
1760         return retval;
1761 }
1762
1763 int for_each_reflog(each_ref_fn fn, void *cb_data)
1764 {
1765         return do_for_each_reflog("", fn, cb_data);
1766 }
1767
1768 int update_ref(const char *action, const char *refname,
1769                 const unsigned char *sha1, const unsigned char *oldval,
1770                 int flags, enum action_on_err onerr)
1771 {
1772         static struct ref_lock *lock;
1773         lock = lock_any_ref_for_update(refname, oldval, flags);
1774         if (!lock) {
1775                 const char *str = "Cannot lock the ref '%s'.";
1776                 switch (onerr) {
1777                 case MSG_ON_ERR: error(str, refname); break;
1778                 case DIE_ON_ERR: die(str, refname); break;
1779                 case QUIET_ON_ERR: break;
1780                 }
1781                 return 1;
1782         }
1783         if (write_ref_sha1(lock, sha1, action) < 0) {
1784                 const char *str = "Cannot update the ref '%s'.";
1785                 switch (onerr) {
1786                 case MSG_ON_ERR: error(str, refname); break;
1787                 case DIE_ON_ERR: die(str, refname); break;
1788                 case QUIET_ON_ERR: break;
1789                 }
1790                 return 1;
1791         }
1792         return 0;
1793 }
1794
1795 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1796 {
1797         for ( ; list; list = list->next)
1798                 if (!strcmp(list->name, name))
1799                         return (struct ref *)list;
1800         return NULL;
1801 }
1802
1803 /*
1804  * generate a format suitable for scanf from a ref_rev_parse_rules
1805  * rule, that is replace the "%.*s" spec with a "%s" spec
1806  */
1807 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1808 {
1809         char *spec;
1810
1811         spec = strstr(rule, "%.*s");
1812         if (!spec || strstr(spec + 4, "%.*s"))
1813                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1814
1815         /* copy all until spec */
1816         strncpy(scanf_fmt, rule, spec - rule);
1817         scanf_fmt[spec - rule] = '\0';
1818         /* copy new spec */
1819         strcat(scanf_fmt, "%s");
1820         /* copy remaining rule */
1821         strcat(scanf_fmt, spec + 4);
1822
1823         return;
1824 }
1825
1826 char *shorten_unambiguous_ref(const char *ref, int strict)
1827 {
1828         int i;
1829         static char **scanf_fmts;
1830         static int nr_rules;
1831         char *short_name;
1832
1833         /* pre generate scanf formats from ref_rev_parse_rules[] */
1834         if (!nr_rules) {
1835                 size_t total_len = 0;
1836
1837                 /* the rule list is NULL terminated, count them first */
1838                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1839                         /* no +1 because strlen("%s") < strlen("%.*s") */
1840                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1841
1842                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1843
1844                 total_len = 0;
1845                 for (i = 0; i < nr_rules; i++) {
1846                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1847                                         + total_len;
1848                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1849                         total_len += strlen(ref_rev_parse_rules[i]);
1850                 }
1851         }
1852
1853         /* bail out if there are no rules */
1854         if (!nr_rules)
1855                 return xstrdup(ref);
1856
1857         /* buffer for scanf result, at most ref must fit */
1858         short_name = xstrdup(ref);
1859
1860         /* skip first rule, it will always match */
1861         for (i = nr_rules - 1; i > 0 ; --i) {
1862                 int j;
1863                 int rules_to_fail = i;
1864                 int short_name_len;
1865
1866                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1867                         continue;
1868
1869                 short_name_len = strlen(short_name);
1870
1871                 /*
1872                  * in strict mode, all (except the matched one) rules
1873                  * must fail to resolve to a valid non-ambiguous ref
1874                  */
1875                 if (strict)
1876                         rules_to_fail = nr_rules;
1877
1878                 /*
1879                  * check if the short name resolves to a valid ref,
1880                  * but use only rules prior to the matched one
1881                  */
1882                 for (j = 0; j < rules_to_fail; j++) {
1883                         const char *rule = ref_rev_parse_rules[j];
1884                         unsigned char short_objectname[20];
1885                         char refname[PATH_MAX];
1886
1887                         /* skip matched rule */
1888                         if (i == j)
1889                                 continue;
1890
1891                         /*
1892                          * the short name is ambiguous, if it resolves
1893                          * (with this previous rule) to a valid ref
1894                          * read_ref() returns 0 on success
1895                          */
1896                         mksnpath(refname, sizeof(refname),
1897                                  rule, short_name_len, short_name);
1898                         if (!read_ref(refname, short_objectname))
1899                                 break;
1900                 }
1901
1902                 /*
1903                  * short name is non-ambiguous if all previous rules
1904                  * haven't resolved to a valid ref
1905                  */
1906                 if (j == rules_to_fail)
1907                         return short_name;
1908         }
1909
1910         free(short_name);
1911         return xstrdup(ref);
1912 }