sha1_file.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include "cache.h"
  10 #include "delta.h"
  11 #include "pack.h"
  12 #include "blob.h"
  13 #include "commit.h"
  14 #include "tag.h"
  15 #include "tree.h"
  16 #include "refs.h"
  17 #include "pack-revindex.h"
  18 #include "sha1-lookup.h"
  19
  20 #ifndef O_NOATIME
  21 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  22 #define O_NOATIME 01000000
  23 #else
  24 #define O_NOATIME 0
  25 #endif
  26 #endif
  27
  28 #ifdef NO_C99_FORMAT
  29 #define SZ_FMT "lu"
  30 static unsigned long sz_fmt(size_t s) { return (unsigned long)s; }
  31 #else
  32 #define SZ_FMT "zu"
  33 static size_t sz_fmt(size_t s) { return s; }
  34 #endif
  35
  36 const unsigned char null_sha1[20];
  37
  38 int safe_create_leading_directories(char *path)
  39 {
  40         char *pos = path + offset_1st_component(path);
  41         struct stat st;
  42
  43         while (pos) {
  44                 pos = strchr(pos, '/');
  45                 if (!pos)
  46                         break;
  47                 while (*++pos == '/')
  48                         ;
  49                 if (!*pos)
  50                         break;
  51                 *--pos = '\0';
  52                 if (!stat(path, &st)) {
  53                         /* path exists */
  54                         if (!S_ISDIR(st.st_mode)) {
  55                                 *pos = '/';
  56                                 return -3;
  57                         }
  58                 }
  59                 else if (mkdir(path, 0777)) {
  60                         *pos = '/';
  61                         return -1;
  62                 }
  63                 else if (adjust_shared_perm(path)) {
  64                         *pos = '/';
  65                         return -2;
  66                 }
  67                 *pos++ = '/';
  68         }
  69         return 0;
  70 }
  71
  72 int safe_create_leading_directories_const(const char *path)
  73 {
  74         /* path points to cache entries, so xstrdup before messing with it */
  75         char *buf = xstrdup(path);
  76         int result = safe_create_leading_directories(buf);
  77         free(buf);
  78         return result;
  79 }
  80
  81 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
  82 {
  83         int i;
  84         for (i = 0; i < 20; i++) {
  85                 static char hex[] = "0123456789abcdef";
  86                 unsigned int val = sha1[i];
  87                 char *pos = pathbuf + i*2 + (i > 0);
  88                 *pos++ = hex[val >> 4];
  89                 *pos = hex[val & 0xf];
  90         }
  91 }
  92
  93 /*
  94  * NOTE! This returns a statically allocated buffer, so you have to be
  95  * careful about using it. Do an "xstrdup()" if you need to save the
  96  * filename.
  97  *
  98  * Also note that this returns the location for creating.  Reading
  99  * SHA1 file can happen from any alternate directory listed in the
 100  * DB_ENVIRONMENT environment variable if it is not found in
 101  * the primary object database.
 102  */
 103 char *sha1_file_name(const unsigned char *sha1)
 104 {
 105         static char buf[PATH_MAX];
 106         const char *objdir;
 107         int len;
 108
 109         objdir = get_object_directory();
 110         len = strlen(objdir);
 111
 112         /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
 113         if (len + 43 > PATH_MAX)
 114                 die("insanely long object directory %s", objdir);
 115         memcpy(buf, objdir, len);
 116         buf[len] = '/';
 117         buf[len+3] = '/';
 118         buf[len+42] = '\0';
 119         fill_sha1_path(buf + len + 1, sha1);
 120         return buf;
 121 }
 122
 123 static char *sha1_get_pack_name(const unsigned char *sha1,
 124                                 char **name, char **base, const char *which)
 125 {
 126         static const char hex[] = "0123456789abcdef";
 127         char *buf;
 128         int i;
 129
 130         if (!*base) {
 131                 const char *sha1_file_directory = get_object_directory();
 132                 int len = strlen(sha1_file_directory);
 133                 *base = xmalloc(len + 60);
 134                 sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
 135                         sha1_file_directory, which);
 136                 *name = *base + len + 11;
 137         }
 138
 139         buf = *name;
 140
 141         for (i = 0; i < 20; i++) {
 142                 unsigned int val = *sha1++;
 143                 *buf++ = hex[val >> 4];
 144                 *buf++ = hex[val & 0xf];
 145         }
 146
 147         return *base;
 148 }
 149
 150 char *sha1_pack_name(const unsigned char *sha1)
 151 {
 152         static char *name, *base;
 153
 154         return sha1_get_pack_name(sha1, &name, &base, "pack");
 155 }
 156
 157 char *sha1_pack_index_name(const unsigned char *sha1)
 158 {
 159         static char *name, *base;
 160
 161         return sha1_get_pack_name(sha1, &name, &base, "idx");
 162 }
 163
 164 struct alternate_object_database *alt_odb_list;
 165 static struct alternate_object_database **alt_odb_tail;
 166
 167 static void read_info_alternates(const char * alternates, int depth);
 168
 169 /*
 170  * Prepare alternate object database registry.
 171  *
 172  * The variable alt_odb_list points at the list of struct
 173  * alternate_object_database.  The elements on this list come from
 174  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 175  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 176  * whose contents is similar to that environment variable but can be
 177  * LF separated.  Its base points at a statically allocated buffer that
 178  * contains "/the/directory/corresponding/to/.git/objects/...", while
 179  * its name points just after the slash at the end of ".git/objects/"
 180  * in the example above, and has enough space to hold 40-byte hex
 181  * SHA1, an extra slash for the first level indirection, and the
 182  * terminating NUL.
 183  */
 184 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 185 {
 186         const char *objdir = get_object_directory();
 187         struct alternate_object_database *ent;
 188         struct alternate_object_database *alt;
 189         /* 43 = 40-byte + 2 '/' + terminating NUL */
 190         int pfxlen = len;
 191         int entlen = pfxlen + 43;
 192         int base_len = -1;
 193
 194         if (!is_absolute_path(entry) && relative_base) {
 195                 /* Relative alt-odb */
 196                 if (base_len < 0)
 197                         base_len = strlen(relative_base) + 1;
 198                 entlen += base_len;
 199                 pfxlen += base_len;
 200         }
 201         ent = xmalloc(sizeof(*ent) + entlen);
 202
 203         if (!is_absolute_path(entry) && relative_base) {
 204                 memcpy(ent->base, relative_base, base_len - 1);
 205                 ent->base[base_len - 1] = '/';
 206                 memcpy(ent->base + base_len, entry, len);
 207         }
 208         else
 209                 memcpy(ent->base, entry, pfxlen);
 210
 211         ent->name = ent->base + pfxlen + 1;
 212         ent->base[pfxlen + 3] = '/';
 213         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 214
 215         /* Detect cases where alternate disappeared */
 216         if (!is_directory(ent->base)) {
 217                 error("object directory %s does not exist; "
 218                       "check .git/objects/info/alternates.",
 219                       ent->base);
 220                 free(ent);
 221                 return -1;
 222         }
 223
 224         /* Prevent the common mistake of listing the same
 225          * thing twice, or object directory itself.
 226          */
 227         for (alt = alt_odb_list; alt; alt = alt->next) {
 228                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 229                         free(ent);
 230                         return -1;
 231                 }
 232         }
 233         if (!memcmp(ent->base, objdir, pfxlen)) {
 234                 free(ent);
 235                 return -1;
 236         }
 237
 238         /* add the alternate entry */
 239         *alt_odb_tail = ent;
 240         alt_odb_tail = &(ent->next);
 241         ent->next = NULL;
 242
 243         /* recursively add alternates */
 244         read_info_alternates(ent->base, depth + 1);
 245
 246         ent->base[pfxlen] = '/';
 247
 248         return 0;
 249 }
 250
 251 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 252                                  const char *relative_base, int depth)
 253 {
 254         const char *cp, *last;
 255
 256         if (depth > 5) {
 257                 error("%s: ignoring alternate object stores, nesting too deep.",
 258                                 relative_base);
 259                 return;
 260         }
 261
 262         last = alt;
 263         while (last < ep) {
 264                 cp = last;
 265                 if (cp < ep && *cp == '#') {
 266                         while (cp < ep && *cp != sep)
 267                                 cp++;
 268                         last = cp + 1;
 269                         continue;
 270                 }
 271                 while (cp < ep && *cp != sep)
 272                         cp++;
 273                 if (last != cp) {
 274                         if (!is_absolute_path(last) && depth) {
 275                                 error("%s: ignoring relative alternate object store %s",
 276                                                 relative_base, last);
 277                         } else {
 278                                 link_alt_odb_entry(last, cp - last,
 279                                                 relative_base, depth);
 280                         }
 281                 }
 282                 while (cp < ep && *cp == sep)
 283                         cp++;
 284                 last = cp;
 285         }
 286 }
 287
 288 static void read_info_alternates(const char * relative_base, int depth)
 289 {
 290         char *map;
 291         size_t mapsz;
 292         struct stat st;
 293         const char alt_file_name[] = "info/alternates";
 294         /* Given that relative_base is no longer than PATH_MAX,
 295            ensure that "path" has enough space to append "/", the
 296            file name, "info/alternates", and a trailing NUL.  */
 297         char path[PATH_MAX + 1 + sizeof alt_file_name];
 298         int fd;
 299
 300         sprintf(path, "%s/%s", relative_base, alt_file_name);
 301         fd = open(path, O_RDONLY);
 302         if (fd < 0)
 303                 return;
 304         if (fstat(fd, &st) || (st.st_size == 0)) {
 305                 close(fd);
 306                 return;
 307         }
 308         mapsz = xsize_t(st.st_size);
 309         map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 310         close(fd);
 311
 312         link_alt_odb_entries(map, map + mapsz, '\n', relative_base, depth);
 313
 314         munmap(map, mapsz);
 315 }
 316
 317 void add_to_alternates_file(const char *reference)
 318 {
 319         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 320         int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
 321         char *alt = mkpath("%s/objects\n", reference);
 322         write_or_die(fd, alt, strlen(alt));
 323         if (commit_lock_file(lock))
 324                 die("could not close alternates file");
 325         if (alt_odb_tail)
 326                 link_alt_odb_entries(alt, alt + strlen(alt), '\n', NULL, 0);
 327 }
 328
 329 void foreach_alt_odb(alt_odb_fn fn, void *cb)
 330 {
 331         struct alternate_object_database *ent;
 332
 333         prepare_alt_odb();
 334         for (ent = alt_odb_list; ent; ent = ent->next)
 335                 if (fn(ent, cb))
 336                         return;
 337 }
 338
 339 void prepare_alt_odb(void)
 340 {
 341         const char *alt;
 342
 343         if (alt_odb_tail)
 344                 return;
 345
 346         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 347         if (!alt) alt = "";
 348
 349         alt_odb_tail = &alt_odb_list;
 350         link_alt_odb_entries(alt, alt + strlen(alt), PATH_SEP, NULL, 0);
 351
 352         read_info_alternates(get_object_directory(), 0);
 353 }
 354
 355 static int has_loose_object_local(const unsigned char *sha1)
 356 {
 357         char *name = sha1_file_name(sha1);
 358         return !access(name, F_OK);
 359 }
 360
 361 int has_loose_object_nonlocal(const unsigned char *sha1)
 362 {
 363         struct alternate_object_database *alt;
 364         prepare_alt_odb();
 365         for (alt = alt_odb_list; alt; alt = alt->next) {
 366                 fill_sha1_path(alt->name, sha1);
 367                 if (!access(alt->base, F_OK))
 368                         return 1;
 369         }
 370         return 0;
 371 }
 372
 373 static int has_loose_object(const unsigned char *sha1)
 374 {
 375         return has_loose_object_local(sha1) ||
 376                has_loose_object_nonlocal(sha1);
 377 }
 378
 379 static unsigned int pack_used_ctr;
 380 static unsigned int pack_mmap_calls;
 381 static unsigned int peak_pack_open_windows;
 382 static unsigned int pack_open_windows;
 383 static size_t peak_pack_mapped;
 384 static size_t pack_mapped;
 385 struct packed_git *packed_git;
 386
 387 void pack_report(void)
 388 {
 389         fprintf(stderr,
 390                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 391                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 392                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 393                 sz_fmt(getpagesize()),
 394                 sz_fmt(packed_git_window_size),
 395                 sz_fmt(packed_git_limit));
 396         fprintf(stderr,
 397                 "pack_report: pack_used_ctr            = %10u\n"
 398                 "pack_report: pack_mmap_calls          = %10u\n"
 399                 "pack_report: pack_open_windows        = %10u / %10u\n"
 400                 "pack_report: pack_mapped              = "
 401                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
 402                 pack_used_ctr,
 403                 pack_mmap_calls,
 404                 pack_open_windows, peak_pack_open_windows,
 405                 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 406 }
 407
 408 static int check_packed_git_idx(const char *path,  struct packed_git *p)
 409 {
 410         void *idx_map;
 411         struct pack_idx_header *hdr;
 412         size_t idx_size;
 413         uint32_t version, nr, i, *index;
 414         int fd = open(path, O_RDONLY);
 415         struct stat st;
 416
 417         if (fd < 0)
 418                 return -1;
 419         if (fstat(fd, &st)) {
 420                 close(fd);
 421                 return -1;
 422         }
 423         idx_size = xsize_t(st.st_size);
 424         if (idx_size < 4 * 256 + 20 + 20) {
 425                 close(fd);
 426                 return error("index file %s is too small", path);
 427         }
 428         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 429         close(fd);
 430
 431         hdr = idx_map;
 432         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 433                 version = ntohl(hdr->idx_version);
 434                 if (version < 2 || version > 2) {
 435                         munmap(idx_map, idx_size);
 436                         return error("index file %s is version %"PRIu32
 437                                      " and is not supported by this binary"
 438                                      " (try upgrading GIT to a newer version)",
 439                                      path, version);
 440                 }
 441         } else
 442                 version = 1;
 443
 444         nr = 0;
 445         index = idx_map;
 446         if (version > 1)
 447                 index += 2;  /* skip index header */
 448         for (i = 0; i < 256; i++) {
 449                 uint32_t n = ntohl(index[i]);
 450                 if (n < nr) {
 451                         munmap(idx_map, idx_size);
 452                         return error("non-monotonic index %s", path);
 453                 }
 454                 nr = n;
 455         }
 456
 457         if (version == 1) {
 458                 /*
 459                  * Total size:
 460                  *  - 256 index entries 4 bytes each
 461                  *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 462                  *  - 20-byte SHA1 of the packfile
 463                  *  - 20-byte SHA1 file checksum
 464                  */
 465                 if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 466                         munmap(idx_map, idx_size);
 467                         return error("wrong index v1 file size in %s", path);
 468                 }
 469         } else if (version == 2) {
 470                 /*
 471                  * Minimum size:
 472                  *  - 8 bytes of header
 473                  *  - 256 index entries 4 bytes each
 474                  *  - 20-byte sha1 entry * nr
 475                  *  - 4-byte crc entry * nr
 476                  *  - 4-byte offset entry * nr
 477                  *  - 20-byte SHA1 of the packfile
 478                  *  - 20-byte SHA1 file checksum
 479                  * And after the 4-byte offset table might be a
 480                  * variable sized table containing 8-byte entries
 481                  * for offsets larger than 2^31.
 482                  */
 483                 unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 484                 unsigned long max_size = min_size;
 485                 if (nr)
 486                         max_size += (nr - 1)*8;
 487                 if (idx_size < min_size || idx_size > max_size) {
 488                         munmap(idx_map, idx_size);
 489                         return error("wrong index v2 file size in %s", path);
 490                 }
 491                 if (idx_size != min_size &&
 492                     /*
 493                      * make sure we can deal with large pack offsets.
 494                      * 31-bit signed offset won't be enough, neither
 495                      * 32-bit unsigned one will be.
 496                      */
 497                     (sizeof(off_t) <= 4)) {
 498                         munmap(idx_map, idx_size);
 499                         return error("pack too large for current definition of off_t in %s", path);
 500                 }
 501         }
 502
 503         p->index_version = version;
 504         p->index_data = idx_map;
 505         p->index_size = idx_size;
 506         p->num_objects = nr;
 507         return 0;
 508 }
 509
 510 int open_pack_index(struct packed_git *p)
 511 {
 512         char *idx_name;
 513         int ret;
 514
 515         if (p->index_data)
 516                 return 0;
 517
 518         idx_name = xstrdup(p->pack_name);
 519         strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
 520         ret = check_packed_git_idx(idx_name, p);
 521         free(idx_name);
 522         return ret;
 523 }
 524
 525 static void scan_windows(struct packed_git *p,
 526         struct packed_git **lru_p,
 527         struct pack_window **lru_w,
 528         struct pack_window **lru_l)
 529 {
 530         struct pack_window *w, *w_l;
 531
 532         for (w_l = NULL, w = p->windows; w; w = w->next) {
 533                 if (!w->inuse_cnt) {
 534                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 535                                 *lru_p = p;
 536                                 *lru_w = w;
 537                                 *lru_l = w_l;
 538                         }
 539                 }
 540                 w_l = w;
 541         }
 542 }
 543
 544 static int unuse_one_window(struct packed_git *current, int keep_fd)
 545 {
 546         struct packed_git *p, *lru_p = NULL;
 547         struct pack_window *lru_w = NULL, *lru_l = NULL;
 548
 549         if (current)
 550                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 551         for (p = packed_git; p; p = p->next)
 552                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 553         if (lru_p) {
 554                 munmap(lru_w->base, lru_w->len);
 555                 pack_mapped -= lru_w->len;
 556                 if (lru_l)
 557                         lru_l->next = lru_w->next;
 558                 else {
 559                         lru_p->windows = lru_w->next;
 560                         if (!lru_p->windows && lru_p->pack_fd != keep_fd) {
 561                                 close(lru_p->pack_fd);
 562                                 lru_p->pack_fd = -1;
 563                         }
 564                 }
 565                 free(lru_w);
 566                 pack_open_windows--;
 567                 return 1;
 568         }
 569         return 0;
 570 }
 571
 572 void release_pack_memory(size_t need, int fd)
 573 {
 574         size_t cur = pack_mapped;
 575         while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
 576                 ; /* nothing */
 577 }
 578
 579 void close_pack_windows(struct packed_git *p)
 580 {
 581         while (p->windows) {
 582                 struct pack_window *w = p->windows;
 583
 584                 if (w->inuse_cnt)
 585                         die("pack '%s' still has open windows to it",
 586                             p->pack_name);
 587                 munmap(w->base, w->len);
 588                 pack_mapped -= w->len;
 589                 pack_open_windows--;
 590                 p->windows = w->next;
 591                 free(w);
 592         }
 593 }
 594
 595 void unuse_pack(struct pack_window **w_cursor)
 596 {
 597         struct pack_window *w = *w_cursor;
 598         if (w) {
 599                 w->inuse_cnt--;
 600                 *w_cursor = NULL;
 601         }
 602 }
 603
 604 /*
 605  * This is used by git-repack in case a newly created pack happens to
 606  * contain the same set of objects as an existing one.  In that case
 607  * the resulting file might be different even if its name would be the
 608  * same.  It is best to close any reference to the old pack before it is
 609  * replaced on disk.  Of course no index pointers nor windows for given pack
 610  * must subsist at this point.  If ever objects from this pack are requested
 611  * again, the new version of the pack will be reinitialized through
 612  * reprepare_packed_git().
 613  */
 614 void free_pack_by_name(const char *pack_name)
 615 {
 616         struct packed_git *p, **pp = &packed_git;
 617
 618         while (*pp) {
 619                 p = *pp;
 620                 if (strcmp(pack_name, p->pack_name) == 0) {
 621                         clear_delta_base_cache();
 622                         close_pack_windows(p);
 623                         if (p->pack_fd != -1)
 624                                 close(p->pack_fd);
 625                         if (p->index_data)
 626                                 munmap((void *)p->index_data, p->index_size);
 627                         free(p->bad_object_sha1);
 628                         *pp = p->next;
 629                         free(p);
 630                         return;
 631                 }
 632                 pp = &p->next;
 633         }
 634 }
 635
 636 /*
 637  * Do not call this directly as this leaks p->pack_fd on error return;
 638  * call open_packed_git() instead.
 639  */
 640 static int open_packed_git_1(struct packed_git *p)
 641 {
 642         struct stat st;
 643         struct pack_header hdr;
 644         unsigned char sha1[20];
 645         unsigned char *idx_sha1;
 646         long fd_flag;
 647
 648         if (!p->index_data && open_pack_index(p))
 649                 return error("packfile %s index unavailable", p->pack_name);
 650
 651         p->pack_fd = open(p->pack_name, O_RDONLY);
 652         while (p->pack_fd < 0 && errno == EMFILE && unuse_one_window(p, -1))
 653                 p->pack_fd = open(p->pack_name, O_RDONLY);
 654         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 655                 return -1;
 656
 657         /* If we created the struct before we had the pack we lack size. */
 658         if (!p->pack_size) {
 659                 if (!S_ISREG(st.st_mode))
 660                         return error("packfile %s not a regular file", p->pack_name);
 661                 p->pack_size = st.st_size;
 662         } else if (p->pack_size != st.st_size)
 663                 return error("packfile %s size changed", p->pack_name);
 664
 665         /* We leave these file descriptors open with sliding mmap;
 666          * there is no point keeping them open across exec(), though.
 667          */
 668         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 669         if (fd_flag < 0)
 670                 return error("cannot determine file descriptor flags");
 671         fd_flag |= FD_CLOEXEC;
 672         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 673                 return error("cannot set FD_CLOEXEC");
 674
 675         /* Verify we recognize this pack file format. */
 676         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 677                 return error("file %s is far too short to be a packfile", p->pack_name);
 678         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 679                 return error("file %s is not a GIT packfile", p->pack_name);
 680         if (!pack_version_ok(hdr.hdr_version))
 681                 return error("packfile %s is version %"PRIu32" and not"
 682                         " supported (try upgrading GIT to a newer version)",
 683                         p->pack_name, ntohl(hdr.hdr_version));
 684
 685         /* Verify the pack matches its index. */
 686         if (p->num_objects != ntohl(hdr.hdr_entries))
 687                 return error("packfile %s claims to have %"PRIu32" objects"
 688                              " while index indicates %"PRIu32" objects",
 689                              p->pack_name, ntohl(hdr.hdr_entries),
 690                              p->num_objects);
 691         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 692                 return error("end of packfile %s is unavailable", p->pack_name);
 693         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 694                 return error("packfile %s signature is unavailable", p->pack_name);
 695         idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 696         if (hashcmp(sha1, idx_sha1))
 697                 return error("packfile %s does not match index", p->pack_name);
 698         return 0;
 699 }
 700
 701 static int open_packed_git(struct packed_git *p)
 702 {
 703         if (!open_packed_git_1(p))
 704                 return 0;
 705         if (p->pack_fd != -1) {
 706                 close(p->pack_fd);
 707                 p->pack_fd = -1;
 708         }
 709         return -1;
 710 }
 711
 712 static int in_window(struct pack_window *win, off_t offset)
 713 {
 714         /* We must promise at least 20 bytes (one hash) after the
 715          * offset is available from this window, otherwise the offset
 716          * is not actually in this window and a different window (which
 717          * has that one hash excess) must be used.  This is to support
 718          * the object header and delta base parsing routines below.
 719          */
 720         off_t win_off = win->offset;
 721         return win_off <= offset
 722                 && (offset + 20) <= (win_off + win->len);
 723 }
 724
 725 unsigned char *use_pack(struct packed_git *p,
 726                 struct pack_window **w_cursor,
 727                 off_t offset,
 728                 unsigned int *left)
 729 {
 730         struct pack_window *win = *w_cursor;
 731
 732         if (p->pack_fd == -1 && open_packed_git(p))
 733                 die("packfile %s cannot be accessed", p->pack_name);
 734
 735         /* Since packfiles end in a hash of their content and it's
 736          * pointless to ask for an offset into the middle of that
 737          * hash, and the in_window function above wouldn't match
 738          * don't allow an offset too close to the end of the file.
 739          */
 740         if (offset > (p->pack_size - 20))
 741                 die("offset beyond end of packfile (truncated pack?)");
 742
 743         if (!win || !in_window(win, offset)) {
 744                 if (win)
 745                         win->inuse_cnt--;
 746                 for (win = p->windows; win; win = win->next) {
 747                         if (in_window(win, offset))
 748                                 break;
 749                 }
 750                 if (!win) {
 751                         size_t window_align = packed_git_window_size / 2;
 752                         off_t len;
 753                         win = xcalloc(1, sizeof(*win));
 754                         win->offset = (offset / window_align) * window_align;
 755                         len = p->pack_size - win->offset;
 756                         if (len > packed_git_window_size)
 757                                 len = packed_git_window_size;
 758                         win->len = (size_t)len;
 759                         pack_mapped += win->len;
 760                         while (packed_git_limit < pack_mapped
 761                                 && unuse_one_window(p, p->pack_fd))
 762                                 ; /* nothing */
 763                         win->base = xmmap(NULL, win->len,
 764                                 PROT_READ, MAP_PRIVATE,
 765                                 p->pack_fd, win->offset);
 766                         if (win->base == MAP_FAILED)
 767                                 die("packfile %s cannot be mapped: %s",
 768                                         p->pack_name,
 769                                         strerror(errno));
 770                         pack_mmap_calls++;
 771                         pack_open_windows++;
 772                         if (pack_mapped > peak_pack_mapped)
 773                                 peak_pack_mapped = pack_mapped;
 774                         if (pack_open_windows > peak_pack_open_windows)
 775                                 peak_pack_open_windows = pack_open_windows;
 776                         win->next = p->windows;
 777                         p->windows = win;
 778                 }
 779         }
 780         if (win != *w_cursor) {
 781                 win->last_used = pack_used_ctr++;
 782                 win->inuse_cnt++;
 783                 *w_cursor = win;
 784         }
 785         offset -= win->offset;
 786         if (left)
 787                 *left = win->len - xsize_t(offset);
 788         return win->base + offset;
 789 }
 790
 791 static struct packed_git *alloc_packed_git(int extra)
 792 {
 793         struct packed_git *p = xmalloc(sizeof(*p) + extra);
 794         memset(p, 0, sizeof(*p));
 795         p->pack_fd = -1;
 796         return p;
 797 }
 798
 799 struct packed_git *add_packed_git(const char *path, int path_len, int local)
 800 {
 801         struct stat st;
 802         struct packed_git *p = alloc_packed_git(path_len + 2);
 803
 804         /*
 805          * Make sure a corresponding .pack file exists and that
 806          * the index looks sane.
 807          */
 808         path_len -= strlen(".idx");
 809         if (path_len < 1) {
 810                 free(p);
 811                 return NULL;
 812         }
 813         memcpy(p->pack_name, path, path_len);
 814
 815         strcpy(p->pack_name + path_len, ".keep");
 816         if (!access(p->pack_name, F_OK))
 817                 p->pack_keep = 1;
 818
 819         strcpy(p->pack_name + path_len, ".pack");
 820         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 821                 free(p);
 822                 return NULL;
 823         }
 824
 825         /* ok, it looks sane as far as we can check without
 826          * actually mapping the pack file.
 827          */
 828         p->pack_size = st.st_size;
 829         p->pack_local = local;
 830         p->mtime = st.st_mtime;
 831         if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
 832                 hashclr(p->sha1);
 833         return p;
 834 }
 835
 836 struct packed_git *parse_pack_index(unsigned char *sha1)
 837 {
 838         const char *idx_path = sha1_pack_index_name(sha1);
 839         const char *path = sha1_pack_name(sha1);
 840         struct packed_git *p = alloc_packed_git(strlen(path) + 1);
 841
 842         strcpy(p->pack_name, path);
 843         hashcpy(p->sha1, sha1);
 844         if (check_packed_git_idx(idx_path, p)) {
 845                 free(p);
 846                 return NULL;
 847         }
 848
 849         return p;
 850 }
 851
 852 void install_packed_git(struct packed_git *pack)
 853 {
 854         pack->next = packed_git;
 855         packed_git = pack;
 856 }
 857
 858 static void prepare_packed_git_one(char *objdir, int local)
 859 {
 860         /* Ensure that this buffer is large enough so that we can
 861            append "/pack/" without clobbering the stack even if
 862            strlen(objdir) were PATH_MAX.  */
 863         char path[PATH_MAX + 1 + 4 + 1 + 1];
 864         int len;
 865         DIR *dir;
 866         struct dirent *de;
 867
 868         sprintf(path, "%s/pack", objdir);
 869         len = strlen(path);
 870         dir = opendir(path);
 871         while (!dir && errno == EMFILE && unuse_one_window(packed_git, -1))
 872                 dir = opendir(path);
 873         if (!dir) {
 874                 if (errno != ENOENT)
 875                         error("unable to open object pack directory: %s: %s",
 876                               path, strerror(errno));
 877                 return;
 878         }
 879         path[len++] = '/';
 880         while ((de = readdir(dir)) != NULL) {
 881                 int namelen = strlen(de->d_name);
 882                 struct packed_git *p;
 883
 884                 if (!has_extension(de->d_name, ".idx"))
 885                         continue;
 886
 887                 if (len + namelen + 1 > sizeof(path))
 888                         continue;
 889
 890                 /* Don't reopen a pack we already have. */
 891                 strcpy(path + len, de->d_name);
 892                 for (p = packed_git; p; p = p->next) {
 893                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 894                                 break;
 895                 }
 896                 if (p)
 897                         continue;
 898                 /* See if it really is a valid .idx file with corresponding
 899                  * .pack file that we can map.
 900                  */
 901                 p = add_packed_git(path, len + namelen, local);
 902                 if (!p)
 903                         continue;
 904                 install_packed_git(p);
 905         }
 906         closedir(dir);
 907 }
 908
 909 static int sort_pack(const void *a_, const void *b_)
 910 {
 911         struct packed_git *a = *((struct packed_git **)a_);
 912         struct packed_git *b = *((struct packed_git **)b_);
 913         int st;
 914
 915         /*
 916          * Local packs tend to contain objects specific to our
 917          * variant of the project than remote ones.  In addition,
 918          * remote ones could be on a network mounted filesystem.
 919          * Favor local ones for these reasons.
 920          */
 921         st = a->pack_local - b->pack_local;
 922         if (st)
 923                 return -st;
 924
 925         /*
 926          * Younger packs tend to contain more recent objects,
 927          * and more recent objects tend to get accessed more
 928          * often.
 929          */
 930         if (a->mtime < b->mtime)
 931                 return 1;
 932         else if (a->mtime == b->mtime)
 933                 return 0;
 934         return -1;
 935 }
 936
 937 static void rearrange_packed_git(void)
 938 {
 939         struct packed_git **ary, *p;
 940         int i, n;
 941
 942         for (n = 0, p = packed_git; p; p = p->next)
 943                 n++;
 944         if (n < 2)
 945                 return;
 946
 947         /* prepare an array of packed_git for easier sorting */
 948         ary = xcalloc(n, sizeof(struct packed_git *));
 949         for (n = 0, p = packed_git; p; p = p->next)
 950                 ary[n++] = p;
 951
 952         qsort(ary, n, sizeof(struct packed_git *), sort_pack);
 953
 954         /* link them back again */
 955         for (i = 0; i < n - 1; i++)
 956                 ary[i]->next = ary[i + 1];
 957         ary[n - 1]->next = NULL;
 958         packed_git = ary[0];
 959
 960         free(ary);
 961 }
 962
 963 static int prepare_packed_git_run_once = 0;
 964 void prepare_packed_git(void)
 965 {
 966         struct alternate_object_database *alt;
 967
 968         if (prepare_packed_git_run_once)
 969                 return;
 970         prepare_packed_git_one(get_object_directory(), 1);
 971         prepare_alt_odb();
 972         for (alt = alt_odb_list; alt; alt = alt->next) {
 973                 alt->name[-1] = 0;
 974                 prepare_packed_git_one(alt->base, 0);
 975                 alt->name[-1] = '/';
 976         }
 977         rearrange_packed_git();
 978         prepare_packed_git_run_once = 1;
 979 }
 980
 981 void reprepare_packed_git(void)
 982 {
 983         discard_revindex();
 984         prepare_packed_git_run_once = 0;
 985         prepare_packed_git();
 986 }
 987
 988 static void mark_bad_packed_object(struct packed_git *p,
 989                                    const unsigned char *sha1)
 990 {
 991         unsigned i;
 992         for (i = 0; i < p->num_bad_objects; i++)
 993                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
 994                         return;
 995         p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
 996         hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
 997         p->num_bad_objects++;
 998 }
 999
1000 static int has_packed_and_bad(const unsigned char *sha1)
1001 {
1002         struct packed_git *p;
1003         unsigned i;
1004
1005         for (p = packed_git; p; p = p->next)
1006                 for (i = 0; i < p->num_bad_objects; i++)
1007                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1008                                 return 1;
1009         return 0;
1010 }
1011
1012 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
1013 {
1014         unsigned char real_sha1[20];
1015         hash_sha1_file(map, size, type, real_sha1);
1016         return hashcmp(sha1, real_sha1) ? -1 : 0;
1017 }
1018
1019 static int git_open_noatime(const char *name)
1020 {
1021         static int sha1_file_open_flag = O_NOATIME;
1022         int fd = open(name, O_RDONLY | sha1_file_open_flag);
1023
1024         /* Might the failure be due to O_NOATIME? */
1025         if (fd < 0 && errno != ENOENT && sha1_file_open_flag) {
1026                 fd = open(name, O_RDONLY);
1027                 if (fd >= 0)
1028                         sha1_file_open_flag = 0;
1029         }
1030         return fd;
1031 }
1032
1033 static int open_sha1_file(const unsigned char *sha1)
1034 {
1035         int fd;
1036         char *name = sha1_file_name(sha1);
1037         struct alternate_object_database *alt;
1038
1039         fd = git_open_noatime(name);
1040         if (fd >= 0)
1041                 return fd;
1042
1043         prepare_alt_odb();
1044         errno = ENOENT;
1045         for (alt = alt_odb_list; alt; alt = alt->next) {
1046                 name = alt->name;
1047                 fill_sha1_path(name, sha1);
1048                 fd = git_open_noatime(alt->base);
1049                 if (fd >= 0)
1050                         return fd;
1051         }
1052         return -1;
1053 }
1054
1055 static void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1056 {
1057         void *map;
1058         int fd;
1059
1060         fd = open_sha1_file(sha1);
1061         map = NULL;
1062         if (fd >= 0) {
1063                 struct stat st;
1064
1065                 if (!fstat(fd, &st)) {
1066                         *size = xsize_t(st.st_size);
1067                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1068                 }
1069                 close(fd);
1070         }
1071         return map;
1072 }
1073
1074 static int legacy_loose_object(unsigned char *map)
1075 {
1076         unsigned int word;
1077
1078         /*
1079          * Is it a zlib-compressed buffer? If so, the first byte
1080          * must be 0x78 (15-bit window size, deflated), and the
1081          * first 16-bit word is evenly divisible by 31
1082          */
1083         word = (map[0] << 8) + map[1];
1084         if (map[0] == 0x78 && !(word % 31))
1085                 return 1;
1086         else
1087                 return 0;
1088 }
1089
1090 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1091                 unsigned long len, enum object_type *type, unsigned long *sizep)
1092 {
1093         unsigned shift;
1094         unsigned long size, c;
1095         unsigned long used = 0;
1096
1097         c = buf[used++];
1098         *type = (c >> 4) & 7;
1099         size = c & 15;
1100         shift = 4;
1101         while (c & 0x80) {
1102                 if (len <= used || bitsizeof(long) <= shift) {
1103                         error("bad object header");
1104                         return 0;
1105                 }
1106                 c = buf[used++];
1107                 size += (c & 0x7f) << shift;
1108                 shift += 7;
1109         }
1110         *sizep = size;
1111         return used;
1112 }
1113
1114 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1115 {
1116         unsigned long size, used;
1117         static const char valid_loose_object_type[8] = {
1118                 0, /* OBJ_EXT */
1119                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
1120                 0, /* "delta" and others are invalid in a loose object */
1121         };
1122         enum object_type type;
1123
1124         /* Get the data stream */
1125         memset(stream, 0, sizeof(*stream));
1126         stream->next_in = map;
1127         stream->avail_in = mapsize;
1128         stream->next_out = buffer;
1129         stream->avail_out = bufsiz;
1130
1131         if (legacy_loose_object(map)) {
1132                 git_inflate_init(stream);
1133                 return git_inflate(stream, 0);
1134         }
1135
1136
1137         /*
1138          * There used to be a second loose object header format which
1139          * was meant to mimic the in-pack format, allowing for direct
1140          * copy of the object data.  This format turned up not to be
1141          * really worth it and we don't write it any longer.  But we
1142          * can still read it.
1143          */
1144         used = unpack_object_header_buffer(map, mapsize, &type, &size);
1145         if (!used || !valid_loose_object_type[type])
1146                 return -1;
1147         map += used;
1148         mapsize -= used;
1149
1150         /* Set up the stream for the rest.. */
1151         stream->next_in = map;
1152         stream->avail_in = mapsize;
1153         git_inflate_init(stream);
1154
1155         /* And generate the fake traditional header */
1156         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
1157                                          typename(type), size);
1158         return 0;
1159 }
1160
1161 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1162 {
1163         int bytes = strlen(buffer) + 1;
1164         unsigned char *buf = xmallocz(size);
1165         unsigned long n;
1166         int status = Z_OK;
1167
1168         n = stream->total_out - bytes;
1169         if (n > size)
1170                 n = size;
1171         memcpy(buf, (char *) buffer + bytes, n);
1172         bytes = n;
1173         if (bytes <= size) {
1174                 /*
1175                  * The above condition must be (bytes <= size), not
1176                  * (bytes < size).  In other words, even though we
1177                  * expect no more output and set avail_out to zer0,
1178                  * the input zlib stream may have bytes that express
1179                  * "this concludes the stream", and we *do* want to
1180                  * eat that input.
1181                  *
1182                  * Otherwise we would not be able to test that we
1183                  * consumed all the input to reach the expected size;
1184                  * we also want to check that zlib tells us that all
1185                  * went well with status == Z_STREAM_END at the end.
1186                  */
1187                 stream->next_out = buf + bytes;
1188                 stream->avail_out = size - bytes;
1189                 while (status == Z_OK)
1190                         status = git_inflate(stream, Z_FINISH);
1191         }
1192         if (status == Z_STREAM_END && !stream->avail_in) {
1193                 git_inflate_end(stream);
1194                 return buf;
1195         }
1196
1197         if (status < 0)
1198                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1199         else if (stream->avail_in)
1200                 error("garbage at end of loose object '%s'",
1201                       sha1_to_hex(sha1));
1202         free(buf);
1203         return NULL;
1204 }
1205
1206 /*
1207  * We used to just use "sscanf()", but that's actually way
1208  * too permissive for what we want to check. So do an anal
1209  * object header parse by hand.
1210  */
1211 static int parse_sha1_header(const char *hdr, unsigned long *sizep)
1212 {
1213         char type[10];
1214         int i;
1215         unsigned long size;
1216
1217         /*
1218          * The type can be at most ten bytes (including the
1219          * terminating '\0' that we add), and is followed by
1220          * a space.
1221          */
1222         i = 0;
1223         for (;;) {
1224                 char c = *hdr++;
1225                 if (c == ' ')
1226                         break;
1227                 type[i++] = c;
1228                 if (i >= sizeof(type))
1229                         return -1;
1230         }
1231         type[i] = 0;
1232
1233         /*
1234          * The length must follow immediately, and be in canonical
1235          * decimal format (ie "010" is not valid).
1236          */
1237         size = *hdr++ - '0';
1238         if (size > 9)
1239                 return -1;
1240         if (size) {
1241                 for (;;) {
1242                         unsigned long c = *hdr - '0';
1243                         if (c > 9)
1244                                 break;
1245                         hdr++;
1246                         size = size * 10 + c;
1247                 }
1248         }
1249         *sizep = size;
1250
1251         /*
1252          * The length must be followed by a zero byte
1253          */
1254         return *hdr ? -1 : type_from_string(type);
1255 }
1256
1257 static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1258 {
1259         int ret;
1260         z_stream stream;
1261         char hdr[8192];
1262
1263         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1264         if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1265                 return NULL;
1266
1267         return unpack_sha1_rest(&stream, hdr, *size, sha1);
1268 }
1269
1270 unsigned long get_size_from_delta(struct packed_git *p,
1271                                   struct pack_window **w_curs,
1272                                   off_t curpos)
1273 {
1274         const unsigned char *data;
1275         unsigned char delta_head[20], *in;
1276         z_stream stream;
1277         int st;
1278
1279         memset(&stream, 0, sizeof(stream));
1280         stream.next_out = delta_head;
1281         stream.avail_out = sizeof(delta_head);
1282
1283         git_inflate_init(&stream);
1284         do {
1285                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1286                 stream.next_in = in;
1287                 st = git_inflate(&stream, Z_FINISH);
1288                 curpos += stream.next_in - in;
1289         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1290                  stream.total_out < sizeof(delta_head));
1291         git_inflate_end(&stream);
1292         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1293                 error("delta data unpack-initial failed");
1294                 return 0;
1295         }
1296
1297         /* Examine the initial part of the delta to figure out
1298          * the result size.
1299          */
1300         data = delta_head;
1301
1302         /* ignore base size */
1303         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1304
1305         /* Read the result size */
1306         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1307 }
1308
1309 static off_t get_delta_base(struct packed_git *p,
1310                                     struct pack_window **w_curs,
1311                                     off_t *curpos,
1312                                     enum object_type type,
1313                                     off_t delta_obj_offset)
1314 {
1315         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1316         off_t base_offset;
1317
1318         /* use_pack() assured us we have [base_info, base_info + 20)
1319          * as a range that we can look at without walking off the
1320          * end of the mapped window.  Its actually the hash size
1321          * that is assured.  An OFS_DELTA longer than the hash size
1322          * is stupid, as then a REF_DELTA would be smaller to store.
1323          */
1324         if (type == OBJ_OFS_DELTA) {
1325                 unsigned used = 0;
1326                 unsigned char c = base_info[used++];
1327                 base_offset = c & 127;
1328                 while (c & 128) {
1329                         base_offset += 1;
1330                         if (!base_offset || MSB(base_offset, 7))
1331                                 return 0;  /* overflow */
1332                         c = base_info[used++];
1333                         base_offset = (base_offset << 7) + (c & 127);
1334                 }
1335                 base_offset = delta_obj_offset - base_offset;
1336                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1337                         return 0;  /* out of bound */
1338                 *curpos += used;
1339         } else if (type == OBJ_REF_DELTA) {
1340                 /* The base entry _must_ be in the same pack */
1341                 base_offset = find_pack_entry_one(base_info, p);
1342                 *curpos += 20;
1343         } else
1344                 die("I am totally screwed");
1345         return base_offset;
1346 }
1347
1348 /* forward declaration for a mutually recursive function */
1349 static int packed_object_info(struct packed_git *p, off_t offset,
1350                               unsigned long *sizep);
1351
1352 static int packed_delta_info(struct packed_git *p,
1353                              struct pack_window **w_curs,
1354                              off_t curpos,
1355                              enum object_type type,
1356                              off_t obj_offset,
1357                              unsigned long *sizep)
1358 {
1359         off_t base_offset;
1360
1361         base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1362         if (!base_offset)
1363                 return OBJ_BAD;
1364         type = packed_object_info(p, base_offset, NULL);
1365         if (type <= OBJ_NONE) {
1366                 struct revindex_entry *revidx;
1367                 const unsigned char *base_sha1;
1368                 revidx = find_pack_revindex(p, base_offset);
1369                 if (!revidx)
1370                         return OBJ_BAD;
1371                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1372                 mark_bad_packed_object(p, base_sha1);
1373                 type = sha1_object_info(base_sha1, NULL);
1374                 if (type <= OBJ_NONE)
1375                         return OBJ_BAD;
1376         }
1377
1378         /* We choose to only get the type of the base object and
1379          * ignore potentially corrupt pack file that expects the delta
1380          * based on a base with a wrong size.  This saves tons of
1381          * inflate() calls.
1382          */
1383         if (sizep) {
1384                 *sizep = get_size_from_delta(p, w_curs, curpos);
1385                 if (*sizep == 0)
1386                         type = OBJ_BAD;
1387         }
1388
1389         return type;
1390 }
1391
1392 static int unpack_object_header(struct packed_git *p,
1393                                 struct pack_window **w_curs,
1394                                 off_t *curpos,
1395                                 unsigned long *sizep)
1396 {
1397         unsigned char *base;
1398         unsigned int left;
1399         unsigned long used;
1400         enum object_type type;
1401
1402         /* use_pack() assures us we have [base, base + 20) available
1403          * as a range that we can look at at.  (Its actually the hash
1404          * size that is assured.)  With our object header encoding
1405          * the maximum deflated object size is 2^137, which is just
1406          * insane, so we know won't exceed what we have been given.
1407          */
1408         base = use_pack(p, w_curs, *curpos, &left);
1409         used = unpack_object_header_buffer(base, left, &type, sizep);
1410         if (!used) {
1411                 type = OBJ_BAD;
1412         } else
1413                 *curpos += used;
1414
1415         return type;
1416 }
1417
1418 const char *packed_object_info_detail(struct packed_git *p,
1419                                       off_t obj_offset,
1420                                       unsigned long *size,
1421                                       unsigned long *store_size,
1422                                       unsigned int *delta_chain_length,
1423                                       unsigned char *base_sha1)
1424 {
1425         struct pack_window *w_curs = NULL;
1426         off_t curpos;
1427         unsigned long dummy;
1428         unsigned char *next_sha1;
1429         enum object_type type;
1430         struct revindex_entry *revidx;
1431
1432         *delta_chain_length = 0;
1433         curpos = obj_offset;
1434         type = unpack_object_header(p, &w_curs, &curpos, size);
1435
1436         revidx = find_pack_revindex(p, obj_offset);
1437         *store_size = revidx[1].offset - obj_offset;
1438
1439         for (;;) {
1440                 switch (type) {
1441                 default:
1442                         die("pack %s contains unknown object type %d",
1443                             p->pack_name, type);
1444                 case OBJ_COMMIT:
1445                 case OBJ_TREE:
1446                 case OBJ_BLOB:
1447                 case OBJ_TAG:
1448                         unuse_pack(&w_curs);
1449                         return typename(type);
1450                 case OBJ_OFS_DELTA:
1451                         obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1452                         if (!obj_offset)
1453                                 die("pack %s contains bad delta base reference of type %s",
1454                                     p->pack_name, typename(type));
1455                         if (*delta_chain_length == 0) {
1456                                 revidx = find_pack_revindex(p, obj_offset);
1457                                 hashcpy(base_sha1, nth_packed_object_sha1(p, revidx->nr));
1458                         }
1459                         break;
1460                 case OBJ_REF_DELTA:
1461                         next_sha1 = use_pack(p, &w_curs, curpos, NULL);
1462                         if (*delta_chain_length == 0)
1463                                 hashcpy(base_sha1, next_sha1);
1464                         obj_offset = find_pack_entry_one(next_sha1, p);
1465                         break;
1466                 }
1467                 (*delta_chain_length)++;
1468                 curpos = obj_offset;
1469                 type = unpack_object_header(p, &w_curs, &curpos, &dummy);
1470         }
1471 }
1472
1473 static int packed_object_info(struct packed_git *p, off_t obj_offset,
1474                               unsigned long *sizep)
1475 {
1476         struct pack_window *w_curs = NULL;
1477         unsigned long size;
1478         off_t curpos = obj_offset;
1479         enum object_type type;
1480
1481         type = unpack_object_header(p, &w_curs, &curpos, &size);
1482
1483         switch (type) {
1484         case OBJ_OFS_DELTA:
1485         case OBJ_REF_DELTA:
1486                 type = packed_delta_info(p, &w_curs, curpos,
1487                                          type, obj_offset, sizep);
1488                 break;
1489         case OBJ_COMMIT:
1490         case OBJ_TREE:
1491         case OBJ_BLOB:
1492         case OBJ_TAG:
1493                 if (sizep)
1494                         *sizep = size;
1495                 break;
1496         default:
1497                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1498                       type, (uintmax_t)obj_offset, p->pack_name);
1499                 type = OBJ_BAD;
1500         }
1501         unuse_pack(&w_curs);
1502         return type;
1503 }
1504
1505 static void *unpack_compressed_entry(struct packed_git *p,
1506                                     struct pack_window **w_curs,
1507                                     off_t curpos,
1508                                     unsigned long size)
1509 {
1510         int st;
1511         z_stream stream;
1512         unsigned char *buffer, *in;
1513
1514         buffer = xmallocz(size);
1515         memset(&stream, 0, sizeof(stream));
1516         stream.next_out = buffer;
1517         stream.avail_out = size + 1;
1518
1519         git_inflate_init(&stream);
1520         do {
1521                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1522                 stream.next_in = in;
1523                 st = git_inflate(&stream, Z_FINISH);
1524                 if (!stream.avail_out)
1525                         break; /* the payload is larger than it should be */
1526                 curpos += stream.next_in - in;
1527         } while (st == Z_OK || st == Z_BUF_ERROR);
1528         git_inflate_end(&stream);
1529         if ((st != Z_STREAM_END) || stream.total_out != size) {
1530                 free(buffer);
1531                 return NULL;
1532         }
1533
1534         return buffer;
1535 }
1536
1537 #define MAX_DELTA_CACHE (256)
1538
1539 static size_t delta_base_cached;
1540
1541 static struct delta_base_cache_lru_list {
1542         struct delta_base_cache_lru_list *prev;
1543         struct delta_base_cache_lru_list *next;
1544 } delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1545
1546 static struct delta_base_cache_entry {
1547         struct delta_base_cache_lru_list lru;
1548         void *data;
1549         struct packed_git *p;
1550         off_t base_offset;
1551         unsigned long size;
1552         enum object_type type;
1553 } delta_base_cache[MAX_DELTA_CACHE];
1554
1555 static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1556 {
1557         unsigned long hash;
1558
1559         hash = (unsigned long)p + (unsigned long)base_offset;
1560         hash += (hash >> 8) + (hash >> 16);
1561         return hash % MAX_DELTA_CACHE;
1562 }
1563
1564 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1565         unsigned long *base_size, enum object_type *type, int keep_cache)
1566 {
1567         void *ret;
1568         unsigned long hash = pack_entry_hash(p, base_offset);
1569         struct delta_base_cache_entry *ent = delta_base_cache + hash;
1570
1571         ret = ent->data;
1572         if (!ret || ent->p != p || ent->base_offset != base_offset)
1573                 return unpack_entry(p, base_offset, type, base_size);
1574
1575         if (!keep_cache) {
1576                 ent->data = NULL;
1577                 ent->lru.next->prev = ent->lru.prev;
1578                 ent->lru.prev->next = ent->lru.next;
1579                 delta_base_cached -= ent->size;
1580         } else {
1581                 ret = xmemdupz(ent->data, ent->size);
1582         }
1583         *type = ent->type;
1584         *base_size = ent->size;
1585         return ret;
1586 }
1587
1588 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1589 {
1590         if (ent->data) {
1591                 free(ent->data);
1592                 ent->data = NULL;
1593                 ent->lru.next->prev = ent->lru.prev;
1594                 ent->lru.prev->next = ent->lru.next;
1595                 delta_base_cached -= ent->size;
1596         }
1597 }
1598
1599 void clear_delta_base_cache(void)
1600 {
1601         unsigned long p;
1602         for (p = 0; p < MAX_DELTA_CACHE; p++)
1603                 release_delta_base_cache(&delta_base_cache[p]);
1604 }
1605
1606 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1607         void *base, unsigned long base_size, enum object_type type)
1608 {
1609         unsigned long hash = pack_entry_hash(p, base_offset);
1610         struct delta_base_cache_entry *ent = delta_base_cache + hash;
1611         struct delta_base_cache_lru_list *lru;
1612
1613         release_delta_base_cache(ent);
1614         delta_base_cached += base_size;
1615
1616         for (lru = delta_base_cache_lru.next;
1617              delta_base_cached > delta_base_cache_limit
1618              && lru != &delta_base_cache_lru;
1619              lru = lru->next) {
1620                 struct delta_base_cache_entry *f = (void *)lru;
1621                 if (f->type == OBJ_BLOB)
1622                         release_delta_base_cache(f);
1623         }
1624         for (lru = delta_base_cache_lru.next;
1625              delta_base_cached > delta_base_cache_limit
1626              && lru != &delta_base_cache_lru;
1627              lru = lru->next) {
1628                 struct delta_base_cache_entry *f = (void *)lru;
1629                 release_delta_base_cache(f);
1630         }
1631
1632         ent->p = p;
1633         ent->base_offset = base_offset;
1634         ent->type = type;
1635         ent->data = base;
1636         ent->size = base_size;
1637         ent->lru.next = &delta_base_cache_lru;
1638         ent->lru.prev = delta_base_cache_lru.prev;
1639         delta_base_cache_lru.prev->next = &ent->lru;
1640         delta_base_cache_lru.prev = &ent->lru;
1641 }
1642
1643 static void *read_object(const unsigned char *sha1, enum object_type *type,
1644                          unsigned long *size);
1645
1646 static void *unpack_delta_entry(struct packed_git *p,
1647                                 struct pack_window **w_curs,
1648                                 off_t curpos,
1649                                 unsigned long delta_size,
1650                                 off_t obj_offset,
1651                                 enum object_type *type,
1652                                 unsigned long *sizep)
1653 {
1654         void *delta_data, *result, *base;
1655         unsigned long base_size;
1656         off_t base_offset;
1657
1658         base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
1659         if (!base_offset) {
1660                 error("failed to validate delta base reference "
1661                       "at offset %"PRIuMAX" from %s",
1662                       (uintmax_t)curpos, p->pack_name);
1663                 return NULL;
1664         }
1665         unuse_pack(w_curs);
1666         base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
1667         if (!base) {
1668                 /*
1669                  * We're probably in deep shit, but let's try to fetch
1670                  * the required base anyway from another pack or loose.
1671                  * This is costly but should happen only in the presence
1672                  * of a corrupted pack, and is better than failing outright.
1673                  */
1674                 struct revindex_entry *revidx;
1675                 const unsigned char *base_sha1;
1676                 revidx = find_pack_revindex(p, base_offset);
1677                 if (!revidx)
1678                         return NULL;
1679                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1680                 error("failed to read delta base object %s"
1681                       " at offset %"PRIuMAX" from %s",
1682                       sha1_to_hex(base_sha1), (uintmax_t)base_offset,
1683                       p->pack_name);
1684                 mark_bad_packed_object(p, base_sha1);
1685                 base = read_object(base_sha1, type, &base_size);
1686                 if (!base)
1687                         return NULL;
1688         }
1689
1690         delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
1691         if (!delta_data) {
1692                 error("failed to unpack compressed delta "
1693                       "at offset %"PRIuMAX" from %s",
1694                       (uintmax_t)curpos, p->pack_name);
1695                 free(base);
1696                 return NULL;
1697         }
1698         result = patch_delta(base, base_size,
1699                              delta_data, delta_size,
1700                              sizep);
1701         if (!result)
1702                 die("failed to apply delta");
1703         free(delta_data);
1704         add_delta_base_cache(p, base_offset, base, base_size, *type);
1705         return result;
1706 }
1707
1708 int do_check_packed_object_crc;
1709
1710 void *unpack_entry(struct packed_git *p, off_t obj_offset,
1711                    enum object_type *type, unsigned long *sizep)
1712 {
1713         struct pack_window *w_curs = NULL;
1714         off_t curpos = obj_offset;
1715         void *data;
1716
1717         if (do_check_packed_object_crc && p->index_version > 1) {
1718                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1719                 unsigned long len = revidx[1].offset - obj_offset;
1720                 if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1721                         const unsigned char *sha1 =
1722                                 nth_packed_object_sha1(p, revidx->nr);
1723                         error("bad packed object CRC for %s",
1724                               sha1_to_hex(sha1));
1725                         mark_bad_packed_object(p, sha1);
1726                         unuse_pack(&w_curs);
1727                         return NULL;
1728                 }
1729         }
1730
1731         *type = unpack_object_header(p, &w_curs, &curpos, sizep);
1732         switch (*type) {
1733         case OBJ_OFS_DELTA:
1734         case OBJ_REF_DELTA:
1735                 data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
1736                                           obj_offset, type, sizep);
1737                 break;
1738         case OBJ_COMMIT:
1739         case OBJ_TREE:
1740         case OBJ_BLOB:
1741         case OBJ_TAG:
1742                 data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
1743                 break;
1744         default:
1745                 data = NULL;
1746                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1747                       *type, (uintmax_t)obj_offset, p->pack_name);
1748         }
1749         unuse_pack(&w_curs);
1750         return data;
1751 }
1752
1753 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1754                                             uint32_t n)
1755 {
1756         const unsigned char *index = p->index_data;
1757         if (!index) {
1758                 if (open_pack_index(p))
1759                         return NULL;
1760                 index = p->index_data;
1761         }
1762         if (n >= p->num_objects)
1763                 return NULL;
1764         index += 4 * 256;
1765         if (p->index_version == 1) {
1766                 return index + 24 * n + 4;
1767         } else {
1768                 index += 8;
1769                 return index + 20 * n;
1770         }
1771 }
1772
1773 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1774 {
1775         const unsigned char *index = p->index_data;
1776         index += 4 * 256;
1777         if (p->index_version == 1) {
1778                 return ntohl(*((uint32_t *)(index + 24 * n)));
1779         } else {
1780                 uint32_t off;
1781                 index += 8 + p->num_objects * (20 + 4);
1782                 off = ntohl(*((uint32_t *)(index + 4 * n)));
1783                 if (!(off & 0x80000000))
1784                         return off;
1785                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1786                 return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
1787                                    ntohl(*((uint32_t *)(index + 4)));
1788         }
1789 }
1790
1791 off_t find_pack_entry_one(const unsigned char *sha1,
1792                                   struct packed_git *p)
1793 {
1794         const uint32_t *level1_ofs = p->index_data;
1795         const unsigned char *index = p->index_data;
1796         unsigned hi, lo, stride;
1797         static int use_lookup = -1;
1798         static int debug_lookup = -1;
1799
1800         if (debug_lookup < 0)
1801                 debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
1802
1803         if (!index) {
1804                 if (open_pack_index(p))
1805                         return 0;
1806                 level1_ofs = p->index_data;
1807                 index = p->index_data;
1808         }
1809         if (p->index_version > 1) {
1810                 level1_ofs += 2;
1811                 index += 8;
1812         }
1813         index += 4 * 256;
1814         hi = ntohl(level1_ofs[*sha1]);
1815         lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1816         if (p->index_version > 1) {
1817                 stride = 20;
1818         } else {
1819                 stride = 24;
1820                 index += 4;
1821         }
1822
1823         if (debug_lookup)
1824                 printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
1825                        sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
1826
1827         if (use_lookup < 0)
1828                 use_lookup = !!getenv("GIT_USE_LOOKUP");
1829         if (use_lookup) {
1830                 int pos = sha1_entry_pos(index, stride, 0,
1831                                          lo, hi, p->num_objects, sha1);
1832                 if (pos < 0)
1833                         return 0;
1834                 return nth_packed_object_offset(p, pos);
1835         }
1836
1837         do {
1838                 unsigned mi = (lo + hi) / 2;
1839                 int cmp = hashcmp(index + mi * stride, sha1);
1840
1841                 if (debug_lookup)
1842                         printf("lo %u hi %u rg %u mi %u\n",
1843                                lo, hi, hi - lo, mi);
1844                 if (!cmp)
1845                         return nth_packed_object_offset(p, mi);
1846                 if (cmp > 0)
1847                         hi = mi;
1848                 else
1849                         lo = mi+1;
1850         } while (lo < hi);
1851         return 0;
1852 }
1853
1854 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1855 {
1856         static struct packed_git *last_found = (void *)1;
1857         struct packed_git *p;
1858         off_t offset;
1859
1860         prepare_packed_git();
1861         if (!packed_git)
1862                 return 0;
1863         p = (last_found == (void *)1) ? packed_git : last_found;
1864
1865         do {
1866                 if (p->num_bad_objects) {
1867                         unsigned i;
1868                         for (i = 0; i < p->num_bad_objects; i++)
1869                                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1870                                         goto next;
1871                 }
1872
1873                 offset = find_pack_entry_one(sha1, p);
1874                 if (offset) {
1875                         /*
1876                          * We are about to tell the caller where they can
1877                          * locate the requested object.  We better make
1878                          * sure the packfile is still here and can be
1879                          * accessed before supplying that answer, as
1880                          * it may have been deleted since the index
1881                          * was loaded!
1882                          */
1883                         if (p->pack_fd == -1 && open_packed_git(p)) {
1884                                 error("packfile %s cannot be accessed", p->pack_name);
1885                                 goto next;
1886                         }
1887                         e->offset = offset;
1888                         e->p = p;
1889                         hashcpy(e->sha1, sha1);
1890                         last_found = p;
1891                         return 1;
1892                 }
1893
1894                 next:
1895                 if (p == last_found)
1896                         p = packed_git;
1897                 else
1898                         p = p->next;
1899                 if (p == last_found)
1900                         p = p->next;
1901         } while (p);
1902         return 0;
1903 }
1904
1905 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1906                                   struct packed_git *packs)
1907 {
1908         struct packed_git *p;
1909
1910         for (p = packs; p; p = p->next) {
1911                 if (find_pack_entry_one(sha1, p))
1912                         return p;
1913         }
1914         return NULL;
1915
1916 }
1917
1918 static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
1919 {
1920         int status;
1921         unsigned long mapsize, size;
1922         void *map;
1923         z_stream stream;
1924         char hdr[32];
1925
1926         map = map_sha1_file(sha1, &mapsize);
1927         if (!map)
1928                 return error("unable to find %s", sha1_to_hex(sha1));
1929         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1930                 status = error("unable to unpack %s header",
1931                                sha1_to_hex(sha1));
1932         else if ((status = parse_sha1_header(hdr, &size)) < 0)
1933                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1934         else if (sizep)
1935                 *sizep = size;
1936         git_inflate_end(&stream);
1937         munmap(map, mapsize);
1938         return status;
1939 }
1940
1941 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
1942 {
1943         struct pack_entry e;
1944         int status;
1945
1946         if (!find_pack_entry(sha1, &e)) {
1947                 /* Most likely it's a loose object. */
1948                 status = sha1_loose_object_info(sha1, sizep);
1949                 if (status >= 0)
1950                         return status;
1951
1952                 /* Not a loose object; someone else may have just packed it. */
1953                 reprepare_packed_git();
1954                 if (!find_pack_entry(sha1, &e))
1955                         return status;
1956         }
1957
1958         status = packed_object_info(e.p, e.offset, sizep);
1959         if (status < 0) {
1960                 mark_bad_packed_object(e.p, sha1);
1961                 status = sha1_object_info(sha1, sizep);
1962         }
1963
1964         return status;
1965 }
1966
1967 static void *read_packed_sha1(const unsigned char *sha1,
1968                               enum object_type *type, unsigned long *size)
1969 {
1970         struct pack_entry e;
1971         void *data;
1972
1973         if (!find_pack_entry(sha1, &e))
1974                 return NULL;
1975         data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
1976         if (!data) {
1977                 /*
1978                  * We're probably in deep shit, but let's try to fetch
1979                  * the required object anyway from another pack or loose.
1980                  * This should happen only in the presence of a corrupted
1981                  * pack, and is better than failing outright.
1982                  */
1983                 error("failed to read object %s at offset %"PRIuMAX" from %s",
1984                       sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
1985                 mark_bad_packed_object(e.p, sha1);
1986                 data = read_object(sha1, type, size);
1987         }
1988         return data;
1989 }
1990
1991 /*
1992  * This is meant to hold a *small* number of objects that you would
1993  * want read_sha1_file() to be able to return, but yet you do not want
1994  * to write them into the object store (e.g. a browse-only
1995  * application).
1996  */
1997 static struct cached_object {
1998         unsigned char sha1[20];
1999         enum object_type type;
2000         void *buf;
2001         unsigned long size;
2002 } *cached_objects;
2003 static int cached_object_nr, cached_object_alloc;
2004
2005 static struct cached_object empty_tree = {
2006         EMPTY_TREE_SHA1_BIN,
2007         OBJ_TREE,
2008         "",
2009         0
2010 };
2011
2012 static struct cached_object *find_cached_object(const unsigned char *sha1)
2013 {
2014         int i;
2015         struct cached_object *co = cached_objects;
2016
2017         for (i = 0; i < cached_object_nr; i++, co++) {
2018                 if (!hashcmp(co->sha1, sha1))
2019                         return co;
2020         }
2021         if (!hashcmp(sha1, empty_tree.sha1))
2022                 return &empty_tree;
2023         return NULL;
2024 }
2025
2026 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2027                       unsigned char *sha1)
2028 {
2029         struct cached_object *co;
2030
2031         hash_sha1_file(buf, len, typename(type), sha1);
2032         if (has_sha1_file(sha1) || find_cached_object(sha1))
2033                 return 0;
2034         if (cached_object_alloc <= cached_object_nr) {
2035                 cached_object_alloc = alloc_nr(cached_object_alloc);
2036                 cached_objects = xrealloc(cached_objects,
2037                                           sizeof(*cached_objects) *
2038                                           cached_object_alloc);
2039         }
2040         co = &cached_objects[cached_object_nr++];
2041         co->size = len;
2042         co->type = type;
2043         co->buf = xmalloc(len);
2044         memcpy(co->buf, buf, len);
2045         hashcpy(co->sha1, sha1);
2046         return 0;
2047 }
2048
2049 static void *read_object(const unsigned char *sha1, enum object_type *type,
2050                          unsigned long *size)
2051 {
2052         unsigned long mapsize;
2053         void *map, *buf;
2054         struct cached_object *co;
2055
2056         co = find_cached_object(sha1);
2057         if (co) {
2058                 *type = co->type;
2059                 *size = co->size;
2060                 return xmemdupz(co->buf, co->size);
2061         }
2062
2063         buf = read_packed_sha1(sha1, type, size);
2064         if (buf)
2065                 return buf;
2066         map = map_sha1_file(sha1, &mapsize);
2067         if (map) {
2068                 buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2069                 munmap(map, mapsize);
2070                 return buf;
2071         }
2072         reprepare_packed_git();
2073         return read_packed_sha1(sha1, type, size);
2074 }
2075
2076 void *read_sha1_file_repl(const unsigned char *sha1,
2077                           enum object_type *type,
2078                           unsigned long *size,
2079                           const unsigned char **replacement)
2080 {
2081         const unsigned char *repl = lookup_replace_object(sha1);
2082         void *data = read_object(repl, type, size);
2083
2084         /* die if we replaced an object with one that does not exist */
2085         if (!data && repl != sha1)
2086                 die("replacement %s not found for %s",
2087                     sha1_to_hex(repl), sha1_to_hex(sha1));
2088
2089         /* legacy behavior is to die on corrupted objects */
2090         if (!data && (has_loose_object(repl) || has_packed_and_bad(repl)))
2091                 die("object %s is corrupted", sha1_to_hex(repl));
2092
2093         if (replacement)
2094                 *replacement = repl;
2095
2096         return data;
2097 }
2098
2099 void *read_object_with_reference(const unsigned char *sha1,
2100                                  const char *required_type_name,
2101                                  unsigned long *size,
2102                                  unsigned char *actual_sha1_return)
2103 {
2104         enum object_type type, required_type;
2105         void *buffer;
2106         unsigned long isize;
2107         unsigned char actual_sha1[20];
2108
2109         required_type = type_from_string(required_type_name);
2110         hashcpy(actual_sha1, sha1);
2111         while (1) {
2112                 int ref_length = -1;
2113                 const char *ref_type = NULL;
2114
2115                 buffer = read_sha1_file(actual_sha1, &type, &isize);
2116                 if (!buffer)
2117                         return NULL;
2118                 if (type == required_type) {
2119                         *size = isize;
2120                         if (actual_sha1_return)
2121                                 hashcpy(actual_sha1_return, actual_sha1);
2122                         return buffer;
2123                 }
2124                 /* Handle references */
2125                 else if (type == OBJ_COMMIT)
2126                         ref_type = "tree ";
2127                 else if (type == OBJ_TAG)
2128                         ref_type = "object ";
2129                 else {
2130                         free(buffer);
2131                         return NULL;
2132                 }
2133                 ref_length = strlen(ref_type);
2134
2135                 if (ref_length + 40 > isize ||
2136                     memcmp(buffer, ref_type, ref_length) ||
2137                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2138                         free(buffer);
2139                         return NULL;
2140                 }
2141                 free(buffer);
2142                 /* Now we have the ID of the referred-to object in
2143                  * actual_sha1.  Check again. */
2144         }
2145 }
2146
2147 static void write_sha1_file_prepare(const void *buf, unsigned long len,
2148                                     const char *type, unsigned char *sha1,
2149                                     char *hdr, int *hdrlen)
2150 {
2151         git_SHA_CTX c;
2152
2153         /* Generate the header */
2154         *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2155
2156         /* Sha1.. */
2157         git_SHA1_Init(&c);
2158         git_SHA1_Update(&c, hdr, *hdrlen);
2159         git_SHA1_Update(&c, buf, len);
2160         git_SHA1_Final(sha1, &c);
2161 }
2162
2163 /*
2164  * Move the just written object into its final resting place.
2165  * NEEDSWORK: this should be renamed to finalize_temp_file() as
2166  * "moving" is only a part of what it does, when no patch between
2167  * master to pu changes the call sites of this function.
2168  */
2169 int move_temp_to_file(const char *tmpfile, const char *filename)
2170 {
2171         int ret = 0;
2172
2173         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2174                 goto try_rename;
2175         else if (link(tmpfile, filename))
2176                 ret = errno;
2177
2178         /*
2179          * Coda hack - coda doesn't like cross-directory links,
2180          * so we fall back to a rename, which will mean that it
2181          * won't be able to check collisions, but that's not a
2182          * big deal.
2183          *
2184          * The same holds for FAT formatted media.
2185          *
2186          * When this succeeds, we just return.  We have nothing
2187          * left to unlink.
2188          */
2189         if (ret && ret != EEXIST) {
2190         try_rename:
2191                 if (!rename(tmpfile, filename))
2192                         goto out;
2193                 ret = errno;
2194         }
2195         unlink_or_warn(tmpfile);
2196         if (ret) {
2197                 if (ret != EEXIST) {
2198                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
2199                 }
2200                 /* FIXME!!! Collision check here ? */
2201         }
2202
2203 out:
2204         if (adjust_shared_perm(filename))
2205                 return error("unable to set permission to '%s'", filename);
2206         return 0;
2207 }
2208
2209 static int write_buffer(int fd, const void *buf, size_t len)
2210 {
2211         if (write_in_full(fd, buf, len) < 0)
2212                 return error("file write error (%s)", strerror(errno));
2213         return 0;
2214 }
2215
2216 int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2217                    unsigned char *sha1)
2218 {
2219         char hdr[32];
2220         int hdrlen;
2221         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2222         return 0;
2223 }
2224
2225 /* Finalize a file on disk, and close it. */
2226 static void close_sha1_file(int fd)
2227 {
2228         if (fsync_object_files)
2229                 fsync_or_die(fd, "sha1 file");
2230         if (close(fd) != 0)
2231                 die_errno("error when closing sha1 file");
2232 }
2233
2234 /* Size of directory component, including the ending '/' */
2235 static inline int directory_size(const char *filename)
2236 {
2237         const char *s = strrchr(filename, '/');
2238         if (!s)
2239                 return 0;
2240         return s - filename + 1;
2241 }
2242
2243 /*
2244  * This creates a temporary file in the same directory as the final
2245  * 'filename'
2246  *
2247  * We want to avoid cross-directory filename renames, because those
2248  * can have problems on various filesystems (FAT, NFS, Coda).
2249  */
2250 static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2251 {
2252         int fd, dirlen = directory_size(filename);
2253
2254         if (dirlen + 20 > bufsiz) {
2255                 errno = ENAMETOOLONG;
2256                 return -1;
2257         }
2258         memcpy(buffer, filename, dirlen);
2259         strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2260         fd = git_mkstemp_mode(buffer, 0444);
2261         if (fd < 0 && dirlen && errno == ENOENT) {
2262                 /* Make sure the directory exists */
2263                 memcpy(buffer, filename, dirlen);
2264                 buffer[dirlen-1] = 0;
2265                 if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
2266                         return -1;
2267
2268                 /* Try again */
2269                 strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2270                 fd = git_mkstemp_mode(buffer, 0444);
2271         }
2272         return fd;
2273 }
2274
2275 static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2276                               const void *buf, unsigned long len, time_t mtime)
2277 {
2278         int fd, ret;
2279         unsigned char compressed[4096];
2280         z_stream stream;
2281         git_SHA_CTX c;
2282         unsigned char parano_sha1[20];
2283         char *filename;
2284         static char tmpfile[PATH_MAX];
2285
2286         filename = sha1_file_name(sha1);
2287         fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
2288         while (fd < 0 && errno == EMFILE && unuse_one_window(packed_git, -1))
2289                 fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
2290         if (fd < 0) {
2291                 if (errno == EACCES)
2292                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
2293                 else
2294                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
2295         }
2296
2297         /* Set it up */
2298         memset(&stream, 0, sizeof(stream));
2299         deflateInit(&stream, zlib_compression_level);
2300         stream.next_out = compressed;
2301         stream.avail_out = sizeof(compressed);
2302         git_SHA1_Init(&c);
2303
2304         /* First header.. */
2305         stream.next_in = (unsigned char *)hdr;
2306         stream.avail_in = hdrlen;
2307         while (deflate(&stream, 0) == Z_OK)
2308                 /* nothing */;
2309         git_SHA1_Update(&c, hdr, hdrlen);
2310
2311         /* Then the data itself.. */
2312         stream.next_in = (void *)buf;
2313         stream.avail_in = len;
2314         do {
2315                 unsigned char *in0 = stream.next_in;
2316                 ret = deflate(&stream, Z_FINISH);
2317                 git_SHA1_Update(&c, in0, stream.next_in - in0);
2318                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2319                         die("unable to write sha1 file");
2320                 stream.next_out = compressed;
2321                 stream.avail_out = sizeof(compressed);
2322         } while (ret == Z_OK);
2323
2324         if (ret != Z_STREAM_END)
2325                 die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2326         ret = deflateEnd(&stream);
2327         if (ret != Z_OK)
2328                 die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2329         git_SHA1_Final(parano_sha1, &c);
2330         if (hashcmp(sha1, parano_sha1) != 0)
2331                 die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2332
2333         close_sha1_file(fd);
2334
2335         if (mtime) {
2336                 struct utimbuf utb;
2337                 utb.actime = mtime;
2338                 utb.modtime = mtime;
2339                 if (utime(tmpfile, &utb) < 0)
2340                         warning("failed utime() on %s: %s",
2341                                 tmpfile, strerror(errno));
2342         }
2343
2344         return move_temp_to_file(tmpfile, filename);
2345 }
2346
2347 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2348 {
2349         unsigned char sha1[20];
2350         char hdr[32];
2351         int hdrlen;
2352
2353         /* Normally if we have it in the pack then we do not bother writing
2354          * it out into .git/objects/??/?{38} file.
2355          */
2356         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2357         if (returnsha1)
2358                 hashcpy(returnsha1, sha1);
2359         if (has_sha1_file(sha1))
2360                 return 0;
2361         return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2362 }
2363
2364 int force_object_loose(const unsigned char *sha1, time_t mtime)
2365 {
2366         void *buf;
2367         unsigned long len;
2368         enum object_type type;
2369         char hdr[32];
2370         int hdrlen;
2371         int ret;
2372
2373         if (has_loose_object(sha1))
2374                 return 0;
2375         buf = read_packed_sha1(sha1, &type, &len);
2376         if (!buf)
2377                 return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2378         hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2379         ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2380         free(buf);
2381
2382         return ret;
2383 }
2384
2385 int has_pack_index(const unsigned char *sha1)
2386 {
2387         struct stat st;
2388         if (stat(sha1_pack_index_name(sha1), &st))
2389                 return 0;
2390         return 1;
2391 }
2392
2393 int has_sha1_pack(const unsigned char *sha1)
2394 {
2395         struct pack_entry e;
2396         return find_pack_entry(sha1, &e);
2397 }
2398
2399 int has_sha1_file(const unsigned char *sha1)
2400 {
2401         struct pack_entry e;
2402
2403         if (find_pack_entry(sha1, &e))
2404                 return 1;
2405         return has_loose_object(sha1);
2406 }
2407
2408 static int index_mem(unsigned char *sha1, void *buf, size_t size,
2409                      int write_object, enum object_type type, const char *path)
2410 {
2411         int ret, re_allocated = 0;
2412
2413         if (!type)
2414                 type = OBJ_BLOB;
2415
2416         /*
2417          * Convert blobs to git internal format
2418          */
2419         if ((type == OBJ_BLOB) && path) {
2420                 struct strbuf nbuf = STRBUF_INIT;
2421                 if (convert_to_git(path, buf, size, &nbuf,
2422                                    write_object ? safe_crlf : 0)) {
2423                         buf = strbuf_detach(&nbuf, &size);
2424                         re_allocated = 1;
2425                 }
2426         }
2427
2428         if (write_object)
2429                 ret = write_sha1_file(buf, size, typename(type), sha1);
2430         else
2431                 ret = hash_sha1_file(buf, size, typename(type), sha1);
2432         if (re_allocated)
2433                 free(buf);
2434         return ret;
2435 }
2436
2437 #define SMALL_FILE_SIZE (32*1024)
2438
2439 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
2440              enum object_type type, const char *path)
2441 {
2442         int ret;
2443         size_t size = xsize_t(st->st_size);
2444
2445         if (!S_ISREG(st->st_mode)) {
2446                 struct strbuf sbuf = STRBUF_INIT;
2447                 if (strbuf_read(&sbuf, fd, 4096) >= 0)
2448                         ret = index_mem(sha1, sbuf.buf, sbuf.len, write_object,
2449                                         type, path);
2450                 else
2451                         ret = -1;
2452                 strbuf_release(&sbuf);
2453         } else if (!size) {
2454                 ret = index_mem(sha1, NULL, size, write_object, type, path);
2455         } else if (size <= SMALL_FILE_SIZE) {
2456                 char *buf = xmalloc(size);
2457                 if (size == read_in_full(fd, buf, size))
2458                         ret = index_mem(sha1, buf, size, write_object, type,
2459                                         path);
2460                 else
2461                         ret = error("short read %s", strerror(errno));
2462                 free(buf);
2463         } else {
2464                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2465                 ret = index_mem(sha1, buf, size, write_object, type, path);
2466                 munmap(buf, size);
2467         }
2468         close(fd);
2469         return ret;
2470 }
2471
2472 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2473 {
2474         int fd;
2475         struct strbuf sb = STRBUF_INIT;
2476
2477         switch (st->st_mode & S_IFMT) {
2478         case S_IFREG:
2479                 fd = open(path, O_RDONLY);
2480                 if (fd < 0)
2481                         return error("open(\"%s\"): %s", path,
2482                                      strerror(errno));
2483                 if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path) < 0)
2484                         return error("%s: failed to insert into database",
2485                                      path);
2486                 break;
2487         case S_IFLNK:
2488                 if (strbuf_readlink(&sb, path, st->st_size)) {
2489                         char *errstr = strerror(errno);
2490                         return error("readlink(\"%s\"): %s", path,
2491                                      errstr);
2492                 }
2493                 if (!write_object)
2494                         hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
2495                 else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
2496                         return error("%s: failed to insert into database",
2497                                      path);
2498                 strbuf_release(&sb);
2499                 break;
2500         case S_IFDIR:
2501                 return resolve_gitlink_ref(path, "HEAD", sha1);
2502         default:
2503                 return error("%s: unsupported file type", path);
2504         }
2505         return 0;
2506 }
2507
2508 int read_pack_header(int fd, struct pack_header *header)
2509 {
2510         if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
2511                 /* "eof before pack header was fully read" */
2512                 return PH_ERROR_EOF;
2513
2514         if (header->hdr_signature != htonl(PACK_SIGNATURE))
2515                 /* "protocol error (pack signature mismatch detected)" */
2516                 return PH_ERROR_PACK_SIGNATURE;
2517         if (!pack_version_ok(header->hdr_version))
2518                 /* "protocol error (pack version unsupported)" */
2519                 return PH_ERROR_PROTOCOL;
2520         return 0;
2521 }