git.oblomov.eu Git - git/blob - 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 "run-command.h"
  15 #include "tag.h"
  16 #include "tree.h"
  17 #include "tree-walk.h"
  18 #include "refs.h"
  19 #include "pack-revindex.h"
  20 #include "sha1-lookup.h"
  21
  22 #ifndef O_NOATIME
  23 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  24 #define O_NOATIME 01000000
  25 #else
  26 #define O_NOATIME 0
  27 #endif
  28 #endif
  29
  30 #define SZ_FMT PRIuMAX
  31 static inline uintmax_t sz_fmt(size_t s) { return s; }
  32
  33 const unsigned char null_sha1[20];
  34
  35 /*
  36  * This is meant to hold a *small* number of objects that you would
  37  * want read_sha1_file() to be able to return, but yet you do not want
  38  * to write them into the object store (e.g. a browse-only
  39  * application).
  40  */
  41 static struct cached_object {
  42         unsigned char sha1[20];
  43         enum object_type type;
  44         void *buf;
  45         unsigned long size;
  46 } *cached_objects;
  47 static int cached_object_nr, cached_object_alloc;
  48
  49 static struct cached_object empty_tree = {
  50         EMPTY_TREE_SHA1_BIN_LITERAL,
  51         OBJ_TREE,
  52         "",
  53         0
  54 };
  55
  56 static struct cached_object *find_cached_object(const unsigned char *sha1)
  57 {
  58         int i;
  59         struct cached_object *co = cached_objects;
  60
  61         for (i = 0; i < cached_object_nr; i++, co++) {
  62                 if (!hashcmp(co->sha1, sha1))
  63                         return co;
  64         }
  65         if (!hashcmp(sha1, empty_tree.sha1))
  66                 return &empty_tree;
  67         return NULL;
  68 }
  69
  70 int mkdir_in_gitdir(const char *path)
  71 {
  72         if (mkdir(path, 0777)) {
  73                 int saved_errno = errno;
  74                 struct stat st;
  75                 struct strbuf sb = STRBUF_INIT;
  76
  77                 if (errno != EEXIST)
  78                         return -1;
  79                 /*
  80                  * Are we looking at a path in a symlinked worktree
  81                  * whose original repository does not yet have it?
  82                  * e.g. .git/rr-cache pointing at its original
  83                  * repository in which the user hasn't performed any
  84                  * conflict resolution yet?
  85                  */
  86                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
  87                     strbuf_readlink(&sb, path, st.st_size) ||
  88                     !is_absolute_path(sb.buf) ||
  89                     mkdir(sb.buf, 0777)) {
  90                         strbuf_release(&sb);
  91                         errno = saved_errno;
  92                         return -1;
  93                 }
  94                 strbuf_release(&sb);
  95         }
  96         return adjust_shared_perm(path);
  97 }
  98
  99 int safe_create_leading_directories(char *path)
 100 {
 101         char *pos = path + offset_1st_component(path);
 102         struct stat st;
 103
 104         while (pos) {
 105                 pos = strchr(pos, '/');
 106                 if (!pos)
 107                         break;
 108                 while (*++pos == '/')
 109                         ;
 110                 if (!*pos)
 111                         break;
 112                 *--pos = '\0';
 113                 if (!stat(path, &st)) {
 114                         /* path exists */
 115                         if (!S_ISDIR(st.st_mode)) {
 116                                 *pos = '/';
 117                                 return -3;
 118                         }
 119                 }
 120                 else if (mkdir(path, 0777)) {
 121                         *pos = '/';
 122                         return -1;
 123                 }
 124                 else if (adjust_shared_perm(path)) {
 125                         *pos = '/';
 126                         return -2;
 127                 }
 128                 *pos++ = '/';
 129         }
 130         return 0;
 131 }
 132
 133 int safe_create_leading_directories_const(const char *path)
 134 {
 135         /* path points to cache entries, so xstrdup before messing with it */
 136         char *buf = xstrdup(path);
 137         int result = safe_create_leading_directories(buf);
 138         free(buf);
 139         return result;
 140 }
 141
 142 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 143 {
 144         int i;
 145         for (i = 0; i < 20; i++) {
 146                 static char hex[] = "0123456789abcdef";
 147                 unsigned int val = sha1[i];
 148                 char *pos = pathbuf + i*2 + (i > 0);
 149                 *pos++ = hex[val >> 4];
 150                 *pos = hex[val & 0xf];
 151         }
 152 }
 153
 154 /*
 155  * NOTE! This returns a statically allocated buffer, so you have to be
 156  * careful about using it. Do an "xstrdup()" if you need to save the
 157  * filename.
 158  *
 159  * Also note that this returns the location for creating.  Reading
 160  * SHA1 file can happen from any alternate directory listed in the
 161  * DB_ENVIRONMENT environment variable if it is not found in
 162  * the primary object database.
 163  */
 164 char *sha1_file_name(const unsigned char *sha1)
 165 {
 166         static char buf[PATH_MAX];
 167         const char *objdir;
 168         int len;
 169
 170         objdir = get_object_directory();
 171         len = strlen(objdir);
 172
 173         /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
 174         if (len + 43 > PATH_MAX)
 175                 die("insanely long object directory %s", objdir);
 176         memcpy(buf, objdir, len);
 177         buf[len] = '/';
 178         buf[len+3] = '/';
 179         buf[len+42] = '\0';
 180         fill_sha1_path(buf + len + 1, sha1);
 181         return buf;
 182 }
 183
 184 static char *sha1_get_pack_name(const unsigned char *sha1,
 185                                 char **name, char **base, const char *which)
 186 {
 187         static const char hex[] = "0123456789abcdef";
 188         char *buf;
 189         int i;
 190
 191         if (!*base) {
 192                 const char *sha1_file_directory = get_object_directory();
 193                 int len = strlen(sha1_file_directory);
 194                 *base = xmalloc(len + 60);
 195                 sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
 196                         sha1_file_directory, which);
 197                 *name = *base + len + 11;
 198         }
 199
 200         buf = *name;
 201
 202         for (i = 0; i < 20; i++) {
 203                 unsigned int val = *sha1++;
 204                 *buf++ = hex[val >> 4];
 205                 *buf++ = hex[val & 0xf];
 206         }
 207
 208         return *base;
 209 }
 210
 211 char *sha1_pack_name(const unsigned char *sha1)
 212 {
 213         static char *name, *base;
 214
 215         return sha1_get_pack_name(sha1, &name, &base, "pack");
 216 }
 217
 218 char *sha1_pack_index_name(const unsigned char *sha1)
 219 {
 220         static char *name, *base;
 221
 222         return sha1_get_pack_name(sha1, &name, &base, "idx");
 223 }
 224
 225 struct alternate_object_database *alt_odb_list;
 226 static struct alternate_object_database **alt_odb_tail;
 227
 228 static void read_info_alternates(const char * alternates, int depth);
 229 static int git_open_noatime(const char *name);
 230
 231 /*
 232  * Prepare alternate object database registry.
 233  *
 234  * The variable alt_odb_list points at the list of struct
 235  * alternate_object_database.  The elements on this list come from
 236  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 237  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 238  * whose contents is similar to that environment variable but can be
 239  * LF separated.  Its base points at a statically allocated buffer that
 240  * contains "/the/directory/corresponding/to/.git/objects/...", while
 241  * its name points just after the slash at the end of ".git/objects/"
 242  * in the example above, and has enough space to hold 40-byte hex
 243  * SHA1, an extra slash for the first level indirection, and the
 244  * terminating NUL.
 245  */
 246 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 247 {
 248         const char *objdir = get_object_directory();
 249         struct alternate_object_database *ent;
 250         struct alternate_object_database *alt;
 251         /* 43 = 40-byte + 2 '/' + terminating NUL */
 252         int pfxlen = len;
 253         int entlen = pfxlen + 43;
 254         int base_len = -1;
 255
 256         if (!is_absolute_path(entry) && relative_base) {
 257                 /* Relative alt-odb */
 258                 if (base_len < 0)
 259                         base_len = strlen(relative_base) + 1;
 260                 entlen += base_len;
 261                 pfxlen += base_len;
 262         }
 263         ent = xmalloc(sizeof(*ent) + entlen);
 264
 265         if (!is_absolute_path(entry) && relative_base) {
 266                 memcpy(ent->base, relative_base, base_len - 1);
 267                 ent->base[base_len - 1] = '/';
 268                 memcpy(ent->base + base_len, entry, len);
 269         }
 270         else
 271                 memcpy(ent->base, entry, pfxlen);
 272
 273         ent->name = ent->base + pfxlen + 1;
 274         ent->base[pfxlen + 3] = '/';
 275         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 276
 277         /* Detect cases where alternate disappeared */
 278         if (!is_directory(ent->base)) {
 279                 error("object directory %s does not exist; "
 280                       "check .git/objects/info/alternates.",
 281                       ent->base);
 282                 free(ent);
 283                 return -1;
 284         }
 285
 286         /* Prevent the common mistake of listing the same
 287          * thing twice, or object directory itself.
 288          */
 289         for (alt = alt_odb_list; alt; alt = alt->next) {
 290                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 291                         free(ent);
 292                         return -1;
 293                 }
 294         }
 295         if (!memcmp(ent->base, objdir, pfxlen)) {
 296                 free(ent);
 297                 return -1;
 298         }
 299
 300         /* add the alternate entry */
 301         *alt_odb_tail = ent;
 302         alt_odb_tail = &(ent->next);
 303         ent->next = NULL;
 304
 305         /* recursively add alternates */
 306         read_info_alternates(ent->base, depth + 1);
 307
 308         ent->base[pfxlen] = '/';
 309
 310         return 0;
 311 }
 312
 313 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 314                                  const char *relative_base, int depth)
 315 {
 316         const char *cp, *last;
 317
 318         if (depth > 5) {
 319                 error("%s: ignoring alternate object stores, nesting too deep.",
 320                                 relative_base);
 321                 return;
 322         }
 323
 324         last = alt;
 325         while (last < ep) {
 326                 cp = last;
 327                 if (cp < ep && *cp == '#') {
 328                         while (cp < ep && *cp != sep)
 329                                 cp++;
 330                         last = cp + 1;
 331                         continue;
 332                 }
 333                 while (cp < ep && *cp != sep)
 334                         cp++;
 335                 if (last != cp) {
 336                         if (!is_absolute_path(last) && depth) {
 337                                 error("%s: ignoring relative alternate object store %s",
 338                                                 relative_base, last);
 339                         } else {
 340                                 link_alt_odb_entry(last, cp - last,
 341                                                 relative_base, depth);
 342                         }
 343                 }
 344                 while (cp < ep && *cp == sep)
 345                         cp++;
 346                 last = cp;
 347         }
 348 }
 349
 350 static void read_info_alternates(const char * relative_base, int depth)
 351 {
 352         char *map;
 353         size_t mapsz;
 354         struct stat st;
 355         const char alt_file_name[] = "info/alternates";
 356         /* Given that relative_base is no longer than PATH_MAX,
 357            ensure that "path" has enough space to append "/", the
 358            file name, "info/alternates", and a trailing NUL.  */
 359         char path[PATH_MAX + 1 + sizeof alt_file_name];
 360         int fd;
 361
 362         sprintf(path, "%s/%s", relative_base, alt_file_name);
 363         fd = git_open_noatime(path);
 364         if (fd < 0)
 365                 return;
 366         if (fstat(fd, &st) || (st.st_size == 0)) {
 367                 close(fd);
 368                 return;
 369         }
 370         mapsz = xsize_t(st.st_size);
 371         map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 372         close(fd);
 373
 374         link_alt_odb_entries(map, map + mapsz, '\n', relative_base, depth);
 375
 376         munmap(map, mapsz);
 377 }
 378
 379 void add_to_alternates_file(const char *reference)
 380 {
 381         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 382         int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
 383         char *alt = mkpath("%s\n", reference);
 384         write_or_die(fd, alt, strlen(alt));
 385         if (commit_lock_file(lock))
 386                 die("could not close alternates file");
 387         if (alt_odb_tail)
 388                 link_alt_odb_entries(alt, alt + strlen(alt), '\n', NULL, 0);
 389 }
 390
 391 void foreach_alt_odb(alt_odb_fn fn, void *cb)
 392 {
 393         struct alternate_object_database *ent;
 394
 395         prepare_alt_odb();
 396         for (ent = alt_odb_list; ent; ent = ent->next)
 397                 if (fn(ent, cb))
 398                         return;
 399 }
 400
 401 void prepare_alt_odb(void)
 402 {
 403         const char *alt;
 404
 405         if (alt_odb_tail)
 406                 return;
 407
 408         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 409         if (!alt) alt = "";
 410
 411         alt_odb_tail = &alt_odb_list;
 412         link_alt_odb_entries(alt, alt + strlen(alt), PATH_SEP, NULL, 0);
 413
 414         read_info_alternates(get_object_directory(), 0);
 415 }
 416
 417 static int has_loose_object_local(const unsigned char *sha1)
 418 {
 419         char *name = sha1_file_name(sha1);
 420         return !access(name, F_OK);
 421 }
 422
 423 int has_loose_object_nonlocal(const unsigned char *sha1)
 424 {
 425         struct alternate_object_database *alt;
 426         prepare_alt_odb();
 427         for (alt = alt_odb_list; alt; alt = alt->next) {
 428                 fill_sha1_path(alt->name, sha1);
 429                 if (!access(alt->base, F_OK))
 430                         return 1;
 431         }
 432         return 0;
 433 }
 434
 435 static int has_loose_object(const unsigned char *sha1)
 436 {
 437         return has_loose_object_local(sha1) ||
 438                has_loose_object_nonlocal(sha1);
 439 }
 440
 441 static unsigned int pack_used_ctr;
 442 static unsigned int pack_mmap_calls;
 443 static unsigned int peak_pack_open_windows;
 444 static unsigned int pack_open_windows;
 445 static unsigned int pack_open_fds;
 446 static unsigned int pack_max_fds;
 447 static size_t peak_pack_mapped;
 448 static size_t pack_mapped;
 449 struct packed_git *packed_git;
 450
 451 void pack_report(void)
 452 {
 453         fprintf(stderr,
 454                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 455                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 456                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 457                 sz_fmt(getpagesize()),
 458                 sz_fmt(packed_git_window_size),
 459                 sz_fmt(packed_git_limit));
 460         fprintf(stderr,
 461                 "pack_report: pack_used_ctr            = %10u\n"
 462                 "pack_report: pack_mmap_calls          = %10u\n"
 463                 "pack_report: pack_open_windows        = %10u / %10u\n"
 464                 "pack_report: pack_mapped              = "
 465                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
 466                 pack_used_ctr,
 467                 pack_mmap_calls,
 468                 pack_open_windows, peak_pack_open_windows,
 469                 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 470 }
 471
 472 static int check_packed_git_idx(const char *path,  struct packed_git *p)
 473 {
 474         void *idx_map;
 475         struct pack_idx_header *hdr;
 476         size_t idx_size;
 477         uint32_t version, nr, i, *index;
 478         int fd = git_open_noatime(path);
 479         struct stat st;
 480
 481         if (fd < 0)
 482                 return -1;
 483         if (fstat(fd, &st)) {
 484                 close(fd);
 485                 return -1;
 486         }
 487         idx_size = xsize_t(st.st_size);
 488         if (idx_size < 4 * 256 + 20 + 20) {
 489                 close(fd);
 490                 return error("index file %s is too small", path);
 491         }
 492         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 493         close(fd);
 494
 495         hdr = idx_map;
 496         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 497                 version = ntohl(hdr->idx_version);
 498                 if (version < 2 || version > 2) {
 499                         munmap(idx_map, idx_size);
 500                         return error("index file %s is version %"PRIu32
 501                                      " and is not supported by this binary"
 502                                      " (try upgrading GIT to a newer version)",
 503                                      path, version);
 504                 }
 505         } else
 506                 version = 1;
 507
 508         nr = 0;
 509         index = idx_map;
 510         if (version > 1)
 511                 index += 2;  /* skip index header */
 512         for (i = 0; i < 256; i++) {
 513                 uint32_t n = ntohl(index[i]);
 514                 if (n < nr) {
 515                         munmap(idx_map, idx_size);
 516                         return error("non-monotonic index %s", path);
 517                 }
 518                 nr = n;
 519         }
 520
 521         if (version == 1) {
 522                 /*
 523                  * Total size:
 524                  *  - 256 index entries 4 bytes each
 525                  *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 526                  *  - 20-byte SHA1 of the packfile
 527                  *  - 20-byte SHA1 file checksum
 528                  */
 529                 if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 530                         munmap(idx_map, idx_size);
 531                         return error("wrong index v1 file size in %s", path);
 532                 }
 533         } else if (version == 2) {
 534                 /*
 535                  * Minimum size:
 536                  *  - 8 bytes of header
 537                  *  - 256 index entries 4 bytes each
 538                  *  - 20-byte sha1 entry * nr
 539                  *  - 4-byte crc entry * nr
 540                  *  - 4-byte offset entry * nr
 541                  *  - 20-byte SHA1 of the packfile
 542                  *  - 20-byte SHA1 file checksum
 543                  * And after the 4-byte offset table might be a
 544                  * variable sized table containing 8-byte entries
 545                  * for offsets larger than 2^31.
 546                  */
 547                 unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 548                 unsigned long max_size = min_size;
 549                 if (nr)
 550                         max_size += (nr - 1)*8;
 551                 if (idx_size < min_size || idx_size > max_size) {
 552                         munmap(idx_map, idx_size);
 553                         return error("wrong index v2 file size in %s", path);
 554                 }
 555                 if (idx_size != min_size &&
 556                     /*
 557                      * make sure we can deal with large pack offsets.
 558                      * 31-bit signed offset won't be enough, neither
 559                      * 32-bit unsigned one will be.
 560                      */
 561                     (sizeof(off_t) <= 4)) {
 562                         munmap(idx_map, idx_size);
 563                         return error("pack too large for current definition of off_t in %s", path);
 564                 }
 565         }
 566
 567         p->index_version = version;
 568         p->index_data = idx_map;
 569         p->index_size = idx_size;
 570         p->num_objects = nr;
 571         return 0;
 572 }
 573
 574 int open_pack_index(struct packed_git *p)
 575 {
 576         char *idx_name;
 577         int ret;
 578
 579         if (p->index_data)
 580                 return 0;
 581
 582         idx_name = xstrdup(p->pack_name);
 583         strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
 584         ret = check_packed_git_idx(idx_name, p);
 585         free(idx_name);
 586         return ret;
 587 }
 588
 589 static void scan_windows(struct packed_git *p,
 590         struct packed_git **lru_p,
 591         struct pack_window **lru_w,
 592         struct pack_window **lru_l)
 593 {
 594         struct pack_window *w, *w_l;
 595
 596         for (w_l = NULL, w = p->windows; w; w = w->next) {
 597                 if (!w->inuse_cnt) {
 598                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 599                                 *lru_p = p;
 600                                 *lru_w = w;
 601                                 *lru_l = w_l;
 602                         }
 603                 }
 604                 w_l = w;
 605         }
 606 }
 607
 608 static int unuse_one_window(struct packed_git *current, int keep_fd)
 609 {
 610         struct packed_git *p, *lru_p = NULL;
 611         struct pack_window *lru_w = NULL, *lru_l = NULL;
 612
 613         if (current)
 614                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 615         for (p = packed_git; p; p = p->next)
 616                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 617         if (lru_p) {
 618                 munmap(lru_w->base, lru_w->len);
 619                 pack_mapped -= lru_w->len;
 620                 if (lru_l)
 621                         lru_l->next = lru_w->next;
 622                 else {
 623                         lru_p->windows = lru_w->next;
 624                         if (!lru_p->windows && lru_p->pack_fd != -1
 625                                 && lru_p->pack_fd != keep_fd) {
 626                                 close(lru_p->pack_fd);
 627                                 pack_open_fds--;
 628                                 lru_p->pack_fd = -1;
 629                         }
 630                 }
 631                 free(lru_w);
 632                 pack_open_windows--;
 633                 return 1;
 634         }
 635         return 0;
 636 }
 637
 638 void release_pack_memory(size_t need, int fd)
 639 {
 640         size_t cur = pack_mapped;
 641         while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
 642                 ; /* nothing */
 643 }
 644
 645 void *xmmap(void *start, size_t length,
 646         int prot, int flags, int fd, off_t offset)
 647 {
 648         void *ret = mmap(start, length, prot, flags, fd, offset);
 649         if (ret == MAP_FAILED) {
 650                 if (!length)
 651                         return NULL;
 652                 release_pack_memory(length, fd);
 653                 ret = mmap(start, length, prot, flags, fd, offset);
 654                 if (ret == MAP_FAILED)
 655                         die_errno("Out of memory? mmap failed");
 656         }
 657         return ret;
 658 }
 659
 660 void close_pack_windows(struct packed_git *p)
 661 {
 662         while (p->windows) {
 663                 struct pack_window *w = p->windows;
 664
 665                 if (w->inuse_cnt)
 666                         die("pack '%s' still has open windows to it",
 667                             p->pack_name);
 668                 munmap(w->base, w->len);
 669                 pack_mapped -= w->len;
 670                 pack_open_windows--;
 671                 p->windows = w->next;
 672                 free(w);
 673         }
 674 }
 675
 676 void unuse_pack(struct pack_window **w_cursor)
 677 {
 678         struct pack_window *w = *w_cursor;
 679         if (w) {
 680                 w->inuse_cnt--;
 681                 *w_cursor = NULL;
 682         }
 683 }
 684
 685 void close_pack_index(struct packed_git *p)
 686 {
 687         if (p->index_data) {
 688                 munmap((void *)p->index_data, p->index_size);
 689                 p->index_data = NULL;
 690         }
 691 }
 692
 693 /*
 694  * This is used by git-repack in case a newly created pack happens to
 695  * contain the same set of objects as an existing one.  In that case
 696  * the resulting file might be different even if its name would be the
 697  * same.  It is best to close any reference to the old pack before it is
 698  * replaced on disk.  Of course no index pointers nor windows for given pack
 699  * must subsist at this point.  If ever objects from this pack are requested
 700  * again, the new version of the pack will be reinitialized through
 701  * reprepare_packed_git().
 702  */
 703 void free_pack_by_name(const char *pack_name)
 704 {
 705         struct packed_git *p, **pp = &packed_git;
 706
 707         while (*pp) {
 708                 p = *pp;
 709                 if (strcmp(pack_name, p->pack_name) == 0) {
 710                         clear_delta_base_cache();
 711                         close_pack_windows(p);
 712                         if (p->pack_fd != -1) {
 713                                 close(p->pack_fd);
 714                                 pack_open_fds--;
 715                         }
 716                         close_pack_index(p);
 717                         free(p->bad_object_sha1);
 718                         *pp = p->next;
 719                         free(p);
 720                         return;
 721                 }
 722                 pp = &p->next;
 723         }
 724 }
 725
 726 /*
 727  * Do not call this directly as this leaks p->pack_fd on error return;
 728  * call open_packed_git() instead.
 729  */
 730 static int open_packed_git_1(struct packed_git *p)
 731 {
 732         struct stat st;
 733         struct pack_header hdr;
 734         unsigned char sha1[20];
 735         unsigned char *idx_sha1;
 736         long fd_flag;
 737
 738         if (!p->index_data && open_pack_index(p))
 739                 return error("packfile %s index unavailable", p->pack_name);
 740
 741         if (!pack_max_fds) {
 742                 struct rlimit lim;
 743                 unsigned int max_fds;
 744
 745                 if (getrlimit(RLIMIT_NOFILE, &lim))
 746                         die_errno("cannot get RLIMIT_NOFILE");
 747
 748                 max_fds = lim.rlim_cur;
 749
 750                 /* Save 3 for stdin/stdout/stderr, 22 for work */
 751                 if (25 < max_fds)
 752                         pack_max_fds = max_fds - 25;
 753                 else
 754                         pack_max_fds = 1;
 755         }
 756
 757         while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
 758                 ; /* nothing */
 759
 760         p->pack_fd = git_open_noatime(p->pack_name);
 761         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 762                 return -1;
 763         pack_open_fds++;
 764
 765         /* If we created the struct before we had the pack we lack size. */
 766         if (!p->pack_size) {
 767                 if (!S_ISREG(st.st_mode))
 768                         return error("packfile %s not a regular file", p->pack_name);
 769                 p->pack_size = st.st_size;
 770         } else if (p->pack_size != st.st_size)
 771                 return error("packfile %s size changed", p->pack_name);
 772
 773         /* We leave these file descriptors open with sliding mmap;
 774          * there is no point keeping them open across exec(), though.
 775          */
 776         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 777         if (fd_flag < 0)
 778                 return error("cannot determine file descriptor flags");
 779         fd_flag |= FD_CLOEXEC;
 780         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 781                 return error("cannot set FD_CLOEXEC");
 782
 783         /* Verify we recognize this pack file format. */
 784         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 785                 return error("file %s is far too short to be a packfile", p->pack_name);
 786         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 787                 return error("file %s is not a GIT packfile", p->pack_name);
 788         if (!pack_version_ok(hdr.hdr_version))
 789                 return error("packfile %s is version %"PRIu32" and not"
 790                         " supported (try upgrading GIT to a newer version)",
 791                         p->pack_name, ntohl(hdr.hdr_version));
 792
 793         /* Verify the pack matches its index. */
 794         if (p->num_objects != ntohl(hdr.hdr_entries))
 795                 return error("packfile %s claims to have %"PRIu32" objects"
 796                              " while index indicates %"PRIu32" objects",
 797                              p->pack_name, ntohl(hdr.hdr_entries),
 798                              p->num_objects);
 799         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 800                 return error("end of packfile %s is unavailable", p->pack_name);
 801         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 802                 return error("packfile %s signature is unavailable", p->pack_name);
 803         idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 804         if (hashcmp(sha1, idx_sha1))
 805                 return error("packfile %s does not match index", p->pack_name);
 806         return 0;
 807 }
 808
 809 static int open_packed_git(struct packed_git *p)
 810 {
 811         if (!open_packed_git_1(p))
 812                 return 0;
 813         if (p->pack_fd != -1) {
 814                 close(p->pack_fd);
 815                 pack_open_fds--;
 816                 p->pack_fd = -1;
 817         }
 818         return -1;
 819 }
 820
 821 static int in_window(struct pack_window *win, off_t offset)
 822 {
 823         /* We must promise at least 20 bytes (one hash) after the
 824          * offset is available from this window, otherwise the offset
 825          * is not actually in this window and a different window (which
 826          * has that one hash excess) must be used.  This is to support
 827          * the object header and delta base parsing routines below.
 828          */
 829         off_t win_off = win->offset;
 830         return win_off <= offset
 831                 && (offset + 20) <= (win_off + win->len);
 832 }
 833
 834 unsigned char *use_pack(struct packed_git *p,
 835                 struct pack_window **w_cursor,
 836                 off_t offset,
 837                 unsigned long *left)
 838 {
 839         struct pack_window *win = *w_cursor;
 840
 841         /* Since packfiles end in a hash of their content and it's
 842          * pointless to ask for an offset into the middle of that
 843          * hash, and the in_window function above wouldn't match
 844          * don't allow an offset too close to the end of the file.
 845          */
 846         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 847                 die("packfile %s cannot be accessed", p->pack_name);
 848         if (offset > (p->pack_size - 20))
 849                 die("offset beyond end of packfile (truncated pack?)");
 850
 851         if (!win || !in_window(win, offset)) {
 852                 if (win)
 853                         win->inuse_cnt--;
 854                 for (win = p->windows; win; win = win->next) {
 855                         if (in_window(win, offset))
 856                                 break;
 857                 }
 858                 if (!win) {
 859                         size_t window_align = packed_git_window_size / 2;
 860                         off_t len;
 861
 862                         if (p->pack_fd == -1 && open_packed_git(p))
 863                                 die("packfile %s cannot be accessed", p->pack_name);
 864
 865                         win = xcalloc(1, sizeof(*win));
 866                         win->offset = (offset / window_align) * window_align;
 867                         len = p->pack_size - win->offset;
 868                         if (len > packed_git_window_size)
 869                                 len = packed_git_window_size;
 870                         win->len = (size_t)len;
 871                         pack_mapped += win->len;
 872                         while (packed_git_limit < pack_mapped
 873                                 && unuse_one_window(p, p->pack_fd))
 874                                 ; /* nothing */
 875                         win->base = xmmap(NULL, win->len,
 876                                 PROT_READ, MAP_PRIVATE,
 877                                 p->pack_fd, win->offset);
 878                         if (win->base == MAP_FAILED)
 879                                 die("packfile %s cannot be mapped: %s",
 880                                         p->pack_name,
 881                                         strerror(errno));
 882                         if (!win->offset && win->len == p->pack_size
 883                                 && !p->do_not_close) {
 884                                 close(p->pack_fd);
 885                                 pack_open_fds--;
 886                                 p->pack_fd = -1;
 887                         }
 888                         pack_mmap_calls++;
 889                         pack_open_windows++;
 890                         if (pack_mapped > peak_pack_mapped)
 891                                 peak_pack_mapped = pack_mapped;
 892                         if (pack_open_windows > peak_pack_open_windows)
 893                                 peak_pack_open_windows = pack_open_windows;
 894                         win->next = p->windows;
 895                         p->windows = win;
 896                 }
 897         }
 898         if (win != *w_cursor) {
 899                 win->last_used = pack_used_ctr++;
 900                 win->inuse_cnt++;
 901                 *w_cursor = win;
 902         }
 903         offset -= win->offset;
 904         if (left)
 905                 *left = win->len - xsize_t(offset);
 906         return win->base + offset;
 907 }
 908
 909 static struct packed_git *alloc_packed_git(int extra)
 910 {
 911         struct packed_git *p = xmalloc(sizeof(*p) + extra);
 912         memset(p, 0, sizeof(*p));
 913         p->pack_fd = -1;
 914         return p;
 915 }
 916
 917 static void try_to_free_pack_memory(size_t size)
 918 {
 919         release_pack_memory(size, -1);
 920 }
 921
 922 struct packed_git *add_packed_git(const char *path, int path_len, int local)
 923 {
 924         static int have_set_try_to_free_routine;
 925         struct stat st;
 926         struct packed_git *p = alloc_packed_git(path_len + 2);
 927
 928         if (!have_set_try_to_free_routine) {
 929                 have_set_try_to_free_routine = 1;
 930                 set_try_to_free_routine(try_to_free_pack_memory);
 931         }
 932
 933         /*
 934          * Make sure a corresponding .pack file exists and that
 935          * the index looks sane.
 936          */
 937         path_len -= strlen(".idx");
 938         if (path_len < 1) {
 939                 free(p);
 940                 return NULL;
 941         }
 942         memcpy(p->pack_name, path, path_len);
 943
 944         strcpy(p->pack_name + path_len, ".keep");
 945         if (!access(p->pack_name, F_OK))
 946                 p->pack_keep = 1;
 947
 948         strcpy(p->pack_name + path_len, ".pack");
 949         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 950                 free(p);
 951                 return NULL;
 952         }
 953
 954         /* ok, it looks sane as far as we can check without
 955          * actually mapping the pack file.
 956          */
 957         p->pack_size = st.st_size;
 958         p->pack_local = local;
 959         p->mtime = st.st_mtime;
 960         if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
 961                 hashclr(p->sha1);
 962         return p;
 963 }
 964
 965 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 966 {
 967         const char *path = sha1_pack_name(sha1);
 968         struct packed_git *p = alloc_packed_git(strlen(path) + 1);
 969
 970         strcpy(p->pack_name, path);
 971         hashcpy(p->sha1, sha1);
 972         if (check_packed_git_idx(idx_path, p)) {
 973                 free(p);
 974                 return NULL;
 975         }
 976
 977         return p;
 978 }
 979
 980 void install_packed_git(struct packed_git *pack)
 981 {
 982         if (pack->pack_fd != -1)
 983                 pack_open_fds++;
 984
 985         pack->next = packed_git;
 986         packed_git = pack;
 987 }
 988
 989 static void prepare_packed_git_one(char *objdir, int local)
 990 {
 991         /* Ensure that this buffer is large enough so that we can
 992            append "/pack/" without clobbering the stack even if
 993            strlen(objdir) were PATH_MAX.  */
 994         char path[PATH_MAX + 1 + 4 + 1 + 1];
 995         int len;
 996         DIR *dir;
 997         struct dirent *de;
 998
 999         sprintf(path, "%s/pack", objdir);
1000         len = strlen(path);
1001         dir = opendir(path);
1002         if (!dir) {
1003                 if (errno != ENOENT)
1004                         error("unable to open object pack directory: %s: %s",
1005                               path, strerror(errno));
1006                 return;
1007         }
1008         path[len++] = '/';
1009         while ((de = readdir(dir)) != NULL) {
1010                 int namelen = strlen(de->d_name);
1011                 struct packed_git *p;
1012
1013                 if (!has_extension(de->d_name, ".idx"))
1014                         continue;
1015
1016                 if (len + namelen + 1 > sizeof(path))
1017                         continue;
1018
1019                 /* Don't reopen a pack we already have. */
1020                 strcpy(path + len, de->d_name);
1021                 for (p = packed_git; p; p = p->next) {
1022                         if (!memcmp(path, p->pack_name, len + namelen - 4))
1023                                 break;
1024                 }
1025                 if (p)
1026                         continue;
1027                 /* See if it really is a valid .idx file with corresponding
1028                  * .pack file that we can map.
1029                  */
1030                 p = add_packed_git(path, len + namelen, local);
1031                 if (!p)
1032                         continue;
1033                 install_packed_git(p);
1034         }
1035         closedir(dir);
1036 }
1037
1038 static int sort_pack(const void *a_, const void *b_)
1039 {
1040         struct packed_git *a = *((struct packed_git **)a_);
1041         struct packed_git *b = *((struct packed_git **)b_);
1042         int st;
1043
1044         /*
1045          * Local packs tend to contain objects specific to our
1046          * variant of the project than remote ones.  In addition,
1047          * remote ones could be on a network mounted filesystem.
1048          * Favor local ones for these reasons.
1049          */
1050         st = a->pack_local - b->pack_local;
1051         if (st)
1052                 return -st;
1053
1054         /*
1055          * Younger packs tend to contain more recent objects,
1056          * and more recent objects tend to get accessed more
1057          * often.
1058          */
1059         if (a->mtime < b->mtime)
1060                 return 1;
1061         else if (a->mtime == b->mtime)
1062                 return 0;
1063         return -1;
1064 }
1065
1066 static void rearrange_packed_git(void)
1067 {
1068         struct packed_git **ary, *p;
1069         int i, n;
1070
1071         for (n = 0, p = packed_git; p; p = p->next)
1072                 n++;
1073         if (n < 2)
1074                 return;
1075
1076         /* prepare an array of packed_git for easier sorting */
1077         ary = xcalloc(n, sizeof(struct packed_git *));
1078         for (n = 0, p = packed_git; p; p = p->next)
1079                 ary[n++] = p;
1080
1081         qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1082
1083         /* link them back again */
1084         for (i = 0; i < n - 1; i++)
1085                 ary[i]->next = ary[i + 1];
1086         ary[n - 1]->next = NULL;
1087         packed_git = ary[0];
1088
1089         free(ary);
1090 }
1091
1092 static int prepare_packed_git_run_once = 0;
1093 void prepare_packed_git(void)
1094 {
1095         struct alternate_object_database *alt;
1096
1097         if (prepare_packed_git_run_once)
1098                 return;
1099         prepare_packed_git_one(get_object_directory(), 1);
1100         prepare_alt_odb();
1101         for (alt = alt_odb_list; alt; alt = alt->next) {
1102                 alt->name[-1] = 0;
1103                 prepare_packed_git_one(alt->base, 0);
1104                 alt->name[-1] = '/';
1105         }
1106         rearrange_packed_git();
1107         prepare_packed_git_run_once = 1;
1108 }
1109
1110 void reprepare_packed_git(void)
1111 {
1112         discard_revindex();
1113         prepare_packed_git_run_once = 0;
1114         prepare_packed_git();
1115 }
1116
1117 static void mark_bad_packed_object(struct packed_git *p,
1118                                    const unsigned char *sha1)
1119 {
1120         unsigned i;
1121         for (i = 0; i < p->num_bad_objects; i++)
1122                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1123                         return;
1124         p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1125         hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1126         p->num_bad_objects++;
1127 }
1128
1129 static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1130 {
1131         struct packed_git *p;
1132         unsigned i;
1133
1134         for (p = packed_git; p; p = p->next)
1135                 for (i = 0; i < p->num_bad_objects; i++)
1136                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1137                                 return p;
1138         return NULL;
1139 }
1140
1141 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
1142 {
1143         unsigned char real_sha1[20];
1144         hash_sha1_file(map, size, type, real_sha1);
1145         return hashcmp(sha1, real_sha1) ? -1 : 0;
1146 }
1147
1148 static int git_open_noatime(const char *name)
1149 {
1150         static int sha1_file_open_flag = O_NOATIME;
1151
1152         for (;;) {
1153                 int fd = open(name, O_RDONLY | sha1_file_open_flag);
1154                 if (fd >= 0)
1155                         return fd;
1156
1157                 /* Might the failure be due to O_NOATIME? */
1158                 if (errno != ENOENT && sha1_file_open_flag) {
1159                         sha1_file_open_flag = 0;
1160                         continue;
1161                 }
1162
1163                 return -1;
1164         }
1165 }
1166
1167 static int open_sha1_file(const unsigned char *sha1)
1168 {
1169         int fd;
1170         char *name = sha1_file_name(sha1);
1171         struct alternate_object_database *alt;
1172
1173         fd = git_open_noatime(name);
1174         if (fd >= 0)
1175                 return fd;
1176
1177         prepare_alt_odb();
1178         errno = ENOENT;
1179         for (alt = alt_odb_list; alt; alt = alt->next) {
1180                 name = alt->name;
1181                 fill_sha1_path(name, sha1);
1182                 fd = git_open_noatime(alt->base);
1183                 if (fd >= 0)
1184                         return fd;
1185         }
1186         return -1;
1187 }
1188
1189 static void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1190 {
1191         void *map;
1192         int fd;
1193
1194         fd = open_sha1_file(sha1);
1195         map = NULL;
1196         if (fd >= 0) {
1197                 struct stat st;
1198
1199                 if (!fstat(fd, &st)) {
1200                         *size = xsize_t(st.st_size);
1201                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1202                 }
1203                 close(fd);
1204         }
1205         return map;
1206 }
1207
1208 /*
1209  * There used to be a second loose object header format which
1210  * was meant to mimic the in-pack format, allowing for direct
1211  * copy of the object data.  This format turned up not to be
1212  * really worth it and we no longer write loose objects in that
1213  * format.
1214  */
1215 static int experimental_loose_object(unsigned char *map)
1216 {
1217         unsigned int word;
1218
1219         /*
1220          * Is it a zlib-compressed buffer? If so, the first byte
1221          * must be 0x78 (15-bit window size, deflated), and the
1222          * first 16-bit word is evenly divisible by 31. If so,
1223          * we are looking at the official format, not the experimental
1224          * one.
1225          */
1226         word = (map[0] << 8) + map[1];
1227         if (map[0] == 0x78 && !(word % 31))
1228                 return 0;
1229         else
1230                 return 1;
1231 }
1232
1233 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1234                 unsigned long len, enum object_type *type, unsigned long *sizep)
1235 {
1236         unsigned shift;
1237         unsigned long size, c;
1238         unsigned long used = 0;
1239
1240         c = buf[used++];
1241         *type = (c >> 4) & 7;
1242         size = c & 15;
1243         shift = 4;
1244         while (c & 0x80) {
1245                 if (len <= used || bitsizeof(long) <= shift) {
1246                         error("bad object header");
1247                         return 0;
1248                 }
1249                 c = buf[used++];
1250                 size += (c & 0x7f) << shift;
1251                 shift += 7;
1252         }
1253         *sizep = size;
1254         return used;
1255 }
1256
1257 static int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1258 {
1259         unsigned long size, used;
1260         static const char valid_loose_object_type[8] = {
1261                 0, /* OBJ_EXT */
1262                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
1263                 0, /* "delta" and others are invalid in a loose object */
1264         };
1265         enum object_type type;
1266
1267         /* Get the data stream */
1268         memset(stream, 0, sizeof(*stream));
1269         stream->next_in = map;
1270         stream->avail_in = mapsize;
1271         stream->next_out = buffer;
1272         stream->avail_out = bufsiz;
1273
1274         if (experimental_loose_object(map)) {
1275                 /*
1276                  * The old experimental format we no longer produce;
1277                  * we can still read it.
1278                  */
1279                 used = unpack_object_header_buffer(map, mapsize, &type, &size);
1280                 if (!used || !valid_loose_object_type[type])
1281                         return -1;
1282                 map += used;
1283                 mapsize -= used;
1284
1285                 /* Set up the stream for the rest.. */
1286                 stream->next_in = map;
1287                 stream->avail_in = mapsize;
1288                 git_inflate_init(stream);
1289
1290                 /* And generate the fake traditional header */
1291                 stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
1292                                                  typename(type), size);
1293                 return 0;
1294         }
1295         git_inflate_init(stream);
1296         return git_inflate(stream, 0);
1297 }
1298
1299 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1300 {
1301         int bytes = strlen(buffer) + 1;
1302         unsigned char *buf = xmallocz(size);
1303         unsigned long n;
1304         int status = Z_OK;
1305
1306         n = stream->total_out - bytes;
1307         if (n > size)
1308                 n = size;
1309         memcpy(buf, (char *) buffer + bytes, n);
1310         bytes = n;
1311         if (bytes <= size) {
1312                 /*
1313                  * The above condition must be (bytes <= size), not
1314                  * (bytes < size).  In other words, even though we
1315                  * expect no more output and set avail_out to zero,
1316                  * the input zlib stream may have bytes that express
1317                  * "this concludes the stream", and we *do* want to
1318                  * eat that input.
1319                  *
1320                  * Otherwise we would not be able to test that we
1321                  * consumed all the input to reach the expected size;
1322                  * we also want to check that zlib tells us that all
1323                  * went well with status == Z_STREAM_END at the end.
1324                  */
1325                 stream->next_out = buf + bytes;
1326                 stream->avail_out = size - bytes;
1327                 while (status == Z_OK)
1328                         status = git_inflate(stream, Z_FINISH);
1329         }
1330         if (status == Z_STREAM_END && !stream->avail_in) {
1331                 git_inflate_end(stream);
1332                 return buf;
1333         }
1334
1335         if (status < 0)
1336                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1337         else if (stream->avail_in)
1338                 error("garbage at end of loose object '%s'",
1339                       sha1_to_hex(sha1));
1340         free(buf);
1341         return NULL;
1342 }
1343
1344 /*
1345  * We used to just use "sscanf()", but that's actually way
1346  * too permissive for what we want to check. So do an anal
1347  * object header parse by hand.
1348  */
1349 static int parse_sha1_header(const char *hdr, unsigned long *sizep)
1350 {
1351         char type[10];
1352         int i;
1353         unsigned long size;
1354
1355         /*
1356          * The type can be at most ten bytes (including the
1357          * terminating '\0' that we add), and is followed by
1358          * a space.
1359          */
1360         i = 0;
1361         for (;;) {
1362                 char c = *hdr++;
1363                 if (c == ' ')
1364                         break;
1365                 type[i++] = c;
1366                 if (i >= sizeof(type))
1367                         return -1;
1368         }
1369         type[i] = 0;
1370
1371         /*
1372          * The length must follow immediately, and be in canonical
1373          * decimal format (ie "010" is not valid).
1374          */
1375         size = *hdr++ - '0';
1376         if (size > 9)
1377                 return -1;
1378         if (size) {
1379                 for (;;) {
1380                         unsigned long c = *hdr - '0';
1381                         if (c > 9)
1382                                 break;
1383                         hdr++;
1384                         size = size * 10 + c;
1385                 }
1386         }
1387         *sizep = size;
1388
1389         /*
1390          * The length must be followed by a zero byte
1391          */
1392         return *hdr ? -1 : type_from_string(type);
1393 }
1394
1395 static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1396 {
1397         int ret;
1398         git_zstream stream;
1399         char hdr[8192];
1400
1401         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1402         if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1403                 return NULL;
1404
1405         return unpack_sha1_rest(&stream, hdr, *size, sha1);
1406 }
1407
1408 unsigned long get_size_from_delta(struct packed_git *p,
1409                                   struct pack_window **w_curs,
1410                                   off_t curpos)
1411 {
1412         const unsigned char *data;
1413         unsigned char delta_head[20], *in;
1414         git_zstream stream;
1415         int st;
1416
1417         memset(&stream, 0, sizeof(stream));
1418         stream.next_out = delta_head;
1419         stream.avail_out = sizeof(delta_head);
1420
1421         git_inflate_init(&stream);
1422         do {
1423                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1424                 stream.next_in = in;
1425                 st = git_inflate(&stream, Z_FINISH);
1426                 curpos += stream.next_in - in;
1427         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1428                  stream.total_out < sizeof(delta_head));
1429         git_inflate_end(&stream);
1430         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1431                 error("delta data unpack-initial failed");
1432                 return 0;
1433         }
1434
1435         /* Examine the initial part of the delta to figure out
1436          * the result size.
1437          */
1438         data = delta_head;
1439
1440         /* ignore base size */
1441         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1442
1443         /* Read the result size */
1444         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1445 }
1446
1447 static off_t get_delta_base(struct packed_git *p,
1448                                     struct pack_window **w_curs,
1449                                     off_t *curpos,
1450                                     enum object_type type,
1451                                     off_t delta_obj_offset)
1452 {
1453         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1454         off_t base_offset;
1455
1456         /* use_pack() assured us we have [base_info, base_info + 20)
1457          * as a range that we can look at without walking off the
1458          * end of the mapped window.  Its actually the hash size
1459          * that is assured.  An OFS_DELTA longer than the hash size
1460          * is stupid, as then a REF_DELTA would be smaller to store.
1461          */
1462         if (type == OBJ_OFS_DELTA) {
1463                 unsigned used = 0;
1464                 unsigned char c = base_info[used++];
1465                 base_offset = c & 127;
1466                 while (c & 128) {
1467                         base_offset += 1;
1468                         if (!base_offset || MSB(base_offset, 7))
1469                                 return 0;  /* overflow */
1470                         c = base_info[used++];
1471                         base_offset = (base_offset << 7) + (c & 127);
1472                 }
1473                 base_offset = delta_obj_offset - base_offset;
1474                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1475                         return 0;  /* out of bound */
1476                 *curpos += used;
1477         } else if (type == OBJ_REF_DELTA) {
1478                 /* The base entry _must_ be in the same pack */
1479                 base_offset = find_pack_entry_one(base_info, p);
1480                 *curpos += 20;
1481         } else
1482                 die("I am totally screwed");
1483         return base_offset;
1484 }
1485
1486 /* forward declaration for a mutually recursive function */
1487 static int packed_object_info(struct packed_git *p, off_t offset,
1488                               unsigned long *sizep);
1489
1490 static int packed_delta_info(struct packed_git *p,
1491                              struct pack_window **w_curs,
1492                              off_t curpos,
1493                              enum object_type type,
1494                              off_t obj_offset,
1495                              unsigned long *sizep)
1496 {
1497         off_t base_offset;
1498
1499         base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1500         if (!base_offset)
1501                 return OBJ_BAD;
1502         type = packed_object_info(p, base_offset, NULL);
1503         if (type <= OBJ_NONE) {
1504                 struct revindex_entry *revidx;
1505                 const unsigned char *base_sha1;
1506                 revidx = find_pack_revindex(p, base_offset);
1507                 if (!revidx)
1508                         return OBJ_BAD;
1509                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1510                 mark_bad_packed_object(p, base_sha1);
1511                 type = sha1_object_info(base_sha1, NULL);
1512                 if (type <= OBJ_NONE)
1513                         return OBJ_BAD;
1514         }
1515
1516         /* We choose to only get the type of the base object and
1517          * ignore potentially corrupt pack file that expects the delta
1518          * based on a base with a wrong size.  This saves tons of
1519          * inflate() calls.
1520          */
1521         if (sizep) {
1522                 *sizep = get_size_from_delta(p, w_curs, curpos);
1523                 if (*sizep == 0)
1524                         type = OBJ_BAD;
1525         }
1526
1527         return type;
1528 }
1529
1530 static int unpack_object_header(struct packed_git *p,
1531                                 struct pack_window **w_curs,
1532                                 off_t *curpos,
1533                                 unsigned long *sizep)
1534 {
1535         unsigned char *base;
1536         unsigned long left;
1537         unsigned long used;
1538         enum object_type type;
1539
1540         /* use_pack() assures us we have [base, base + 20) available
1541          * as a range that we can look at.  (Its actually the hash
1542          * size that is assured.)  With our object header encoding
1543          * the maximum deflated object size is 2^137, which is just
1544          * insane, so we know won't exceed what we have been given.
1545          */
1546         base = use_pack(p, w_curs, *curpos, &left);
1547         used = unpack_object_header_buffer(base, left, &type, sizep);
1548         if (!used) {
1549                 type = OBJ_BAD;
1550         } else
1551                 *curpos += used;
1552
1553         return type;
1554 }
1555
1556 const char *packed_object_info_detail(struct packed_git *p,
1557                                       off_t obj_offset,
1558                                       unsigned long *size,
1559                                       unsigned long *store_size,
1560                                       unsigned int *delta_chain_length,
1561                                       unsigned char *base_sha1)
1562 {
1563         struct pack_window *w_curs = NULL;
1564         off_t curpos;
1565         unsigned long dummy;
1566         unsigned char *next_sha1;
1567         enum object_type type;
1568         struct revindex_entry *revidx;
1569
1570         *delta_chain_length = 0;
1571         curpos = obj_offset;
1572         type = unpack_object_header(p, &w_curs, &curpos, size);
1573
1574         revidx = find_pack_revindex(p, obj_offset);
1575         *store_size = revidx[1].offset - obj_offset;
1576
1577         for (;;) {
1578                 switch (type) {
1579                 default:
1580                         die("pack %s contains unknown object type %d",
1581                             p->pack_name, type);
1582                 case OBJ_COMMIT:
1583                 case OBJ_TREE:
1584                 case OBJ_BLOB:
1585                 case OBJ_TAG:
1586                         unuse_pack(&w_curs);
1587                         return typename(type);
1588                 case OBJ_OFS_DELTA:
1589                         obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1590                         if (!obj_offset)
1591                                 die("pack %s contains bad delta base reference of type %s",
1592                                     p->pack_name, typename(type));
1593                         if (*delta_chain_length == 0) {
1594                                 revidx = find_pack_revindex(p, obj_offset);
1595                                 hashcpy(base_sha1, nth_packed_object_sha1(p, revidx->nr));
1596                         }
1597                         break;
1598                 case OBJ_REF_DELTA:
1599                         next_sha1 = use_pack(p, &w_curs, curpos, NULL);
1600                         if (*delta_chain_length == 0)
1601                                 hashcpy(base_sha1, next_sha1);
1602                         obj_offset = find_pack_entry_one(next_sha1, p);
1603                         break;
1604                 }
1605                 (*delta_chain_length)++;
1606                 curpos = obj_offset;
1607                 type = unpack_object_header(p, &w_curs, &curpos, &dummy);
1608         }
1609 }
1610
1611 static int packed_object_info(struct packed_git *p, off_t obj_offset,
1612                               unsigned long *sizep)
1613 {
1614         struct pack_window *w_curs = NULL;
1615         unsigned long size;
1616         off_t curpos = obj_offset;
1617         enum object_type type;
1618
1619         type = unpack_object_header(p, &w_curs, &curpos, &size);
1620
1621         switch (type) {
1622         case OBJ_OFS_DELTA:
1623         case OBJ_REF_DELTA:
1624                 type = packed_delta_info(p, &w_curs, curpos,
1625                                          type, obj_offset, sizep);
1626                 break;
1627         case OBJ_COMMIT:
1628         case OBJ_TREE:
1629         case OBJ_BLOB:
1630         case OBJ_TAG:
1631                 if (sizep)
1632                         *sizep = size;
1633                 break;
1634         default:
1635                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1636                       type, (uintmax_t)obj_offset, p->pack_name);
1637                 type = OBJ_BAD;
1638         }
1639         unuse_pack(&w_curs);
1640         return type;
1641 }
1642
1643 static void *unpack_compressed_entry(struct packed_git *p,
1644                                     struct pack_window **w_curs,
1645                                     off_t curpos,
1646                                     unsigned long size)
1647 {
1648         int st;
1649         git_zstream stream;
1650         unsigned char *buffer, *in;
1651
1652         buffer = xmallocz(size);
1653         memset(&stream, 0, sizeof(stream));
1654         stream.next_out = buffer;
1655         stream.avail_out = size + 1;
1656
1657         git_inflate_init(&stream);
1658         do {
1659                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1660                 stream.next_in = in;
1661                 st = git_inflate(&stream, Z_FINISH);
1662                 if (!stream.avail_out)
1663                         break; /* the payload is larger than it should be */
1664                 curpos += stream.next_in - in;
1665         } while (st == Z_OK || st == Z_BUF_ERROR);
1666         git_inflate_end(&stream);
1667         if ((st != Z_STREAM_END) || stream.total_out != size) {
1668                 free(buffer);
1669                 return NULL;
1670         }
1671
1672         return buffer;
1673 }
1674
1675 #define MAX_DELTA_CACHE (256)
1676
1677 static size_t delta_base_cached;
1678
1679 static struct delta_base_cache_lru_list {
1680         struct delta_base_cache_lru_list *prev;
1681         struct delta_base_cache_lru_list *next;
1682 } delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1683
1684 static struct delta_base_cache_entry {
1685         struct delta_base_cache_lru_list lru;
1686         void *data;
1687         struct packed_git *p;
1688         off_t base_offset;
1689         unsigned long size;
1690         enum object_type type;
1691 } delta_base_cache[MAX_DELTA_CACHE];
1692
1693 static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1694 {
1695         unsigned long hash;
1696
1697         hash = (unsigned long)p + (unsigned long)base_offset;
1698         hash += (hash >> 8) + (hash >> 16);
1699         return hash % MAX_DELTA_CACHE;
1700 }
1701
1702 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1703         unsigned long *base_size, enum object_type *type, int keep_cache)
1704 {
1705         void *ret;
1706         unsigned long hash = pack_entry_hash(p, base_offset);
1707         struct delta_base_cache_entry *ent = delta_base_cache + hash;
1708
1709         ret = ent->data;
1710         if (!ret || ent->p != p || ent->base_offset != base_offset)
1711                 return unpack_entry(p, base_offset, type, base_size);
1712
1713         if (!keep_cache) {
1714                 ent->data = NULL;
1715                 ent->lru.next->prev = ent->lru.prev;
1716                 ent->lru.prev->next = ent->lru.next;
1717                 delta_base_cached -= ent->size;
1718         } else {
1719                 ret = xmemdupz(ent->data, ent->size);
1720         }
1721         *type = ent->type;
1722         *base_size = ent->size;
1723         return ret;
1724 }
1725
1726 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1727 {
1728         if (ent->data) {
1729                 free(ent->data);
1730                 ent->data = NULL;
1731                 ent->lru.next->prev = ent->lru.prev;
1732                 ent->lru.prev->next = ent->lru.next;
1733                 delta_base_cached -= ent->size;
1734         }
1735 }
1736
1737 void clear_delta_base_cache(void)
1738 {
1739         unsigned long p;
1740         for (p = 0; p < MAX_DELTA_CACHE; p++)
1741                 release_delta_base_cache(&delta_base_cache[p]);
1742 }
1743
1744 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1745         void *base, unsigned long base_size, enum object_type type)
1746 {
1747         unsigned long hash = pack_entry_hash(p, base_offset);
1748         struct delta_base_cache_entry *ent = delta_base_cache + hash;
1749         struct delta_base_cache_lru_list *lru;
1750
1751         release_delta_base_cache(ent);
1752         delta_base_cached += base_size;
1753
1754         for (lru = delta_base_cache_lru.next;
1755              delta_base_cached > delta_base_cache_limit
1756              && lru != &delta_base_cache_lru;
1757              lru = lru->next) {
1758                 struct delta_base_cache_entry *f = (void *)lru;
1759                 if (f->type == OBJ_BLOB)
1760                         release_delta_base_cache(f);
1761         }
1762         for (lru = delta_base_cache_lru.next;
1763              delta_base_cached > delta_base_cache_limit
1764              && lru != &delta_base_cache_lru;
1765              lru = lru->next) {
1766                 struct delta_base_cache_entry *f = (void *)lru;
1767                 release_delta_base_cache(f);
1768         }
1769
1770         ent->p = p;
1771         ent->base_offset = base_offset;
1772         ent->type = type;
1773         ent->data = base;
1774         ent->size = base_size;
1775         ent->lru.next = &delta_base_cache_lru;
1776         ent->lru.prev = delta_base_cache_lru.prev;
1777         delta_base_cache_lru.prev->next = &ent->lru;
1778         delta_base_cache_lru.prev = &ent->lru;
1779 }
1780
1781 static void *read_object(const unsigned char *sha1, enum object_type *type,
1782                          unsigned long *size);
1783
1784 static void *unpack_delta_entry(struct packed_git *p,
1785                                 struct pack_window **w_curs,
1786                                 off_t curpos,
1787                                 unsigned long delta_size,
1788                                 off_t obj_offset,
1789                                 enum object_type *type,
1790                                 unsigned long *sizep)
1791 {
1792         void *delta_data, *result, *base;
1793         unsigned long base_size;
1794         off_t base_offset;
1795
1796         base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
1797         if (!base_offset) {
1798                 error("failed to validate delta base reference "
1799                       "at offset %"PRIuMAX" from %s",
1800                       (uintmax_t)curpos, p->pack_name);
1801                 return NULL;
1802         }
1803         unuse_pack(w_curs);
1804         base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
1805         if (!base) {
1806                 /*
1807                  * We're probably in deep shit, but let's try to fetch
1808                  * the required base anyway from another pack or loose.
1809                  * This is costly but should happen only in the presence
1810                  * of a corrupted pack, and is better than failing outright.
1811                  */
1812                 struct revindex_entry *revidx;
1813                 const unsigned char *base_sha1;
1814                 revidx = find_pack_revindex(p, base_offset);
1815                 if (!revidx)
1816                         return NULL;
1817                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1818                 error("failed to read delta base object %s"
1819                       " at offset %"PRIuMAX" from %s",
1820                       sha1_to_hex(base_sha1), (uintmax_t)base_offset,
1821                       p->pack_name);
1822                 mark_bad_packed_object(p, base_sha1);
1823                 base = read_object(base_sha1, type, &base_size);
1824                 if (!base)
1825                         return NULL;
1826         }
1827
1828         delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
1829         if (!delta_data) {
1830                 error("failed to unpack compressed delta "
1831                       "at offset %"PRIuMAX" from %s",
1832                       (uintmax_t)curpos, p->pack_name);
1833                 free(base);
1834                 return NULL;
1835         }
1836         result = patch_delta(base, base_size,
1837                              delta_data, delta_size,
1838                              sizep);
1839         if (!result)
1840                 die("failed to apply delta");
1841         free(delta_data);
1842         add_delta_base_cache(p, base_offset, base, base_size, *type);
1843         return result;
1844 }
1845
1846 int do_check_packed_object_crc;
1847
1848 void *unpack_entry(struct packed_git *p, off_t obj_offset,
1849                    enum object_type *type, unsigned long *sizep)
1850 {
1851         struct pack_window *w_curs = NULL;
1852         off_t curpos = obj_offset;
1853         void *data;
1854
1855         if (do_check_packed_object_crc && p->index_version > 1) {
1856                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1857                 unsigned long len = revidx[1].offset - obj_offset;
1858                 if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1859                         const unsigned char *sha1 =
1860                                 nth_packed_object_sha1(p, revidx->nr);
1861                         error("bad packed object CRC for %s",
1862                               sha1_to_hex(sha1));
1863                         mark_bad_packed_object(p, sha1);
1864                         unuse_pack(&w_curs);
1865                         return NULL;
1866                 }
1867         }
1868
1869         *type = unpack_object_header(p, &w_curs, &curpos, sizep);
1870         switch (*type) {
1871         case OBJ_OFS_DELTA:
1872         case OBJ_REF_DELTA:
1873                 data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
1874                                           obj_offset, type, sizep);
1875                 break;
1876         case OBJ_COMMIT:
1877         case OBJ_TREE:
1878         case OBJ_BLOB:
1879         case OBJ_TAG:
1880                 data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
1881                 break;
1882         default:
1883                 data = NULL;
1884                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1885                       *type, (uintmax_t)obj_offset, p->pack_name);
1886         }
1887         unuse_pack(&w_curs);
1888         return data;
1889 }
1890
1891 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1892                                             uint32_t n)
1893 {
1894         const unsigned char *index = p->index_data;
1895         if (!index) {
1896                 if (open_pack_index(p))
1897                         return NULL;
1898                 index = p->index_data;
1899         }
1900         if (n >= p->num_objects)
1901                 return NULL;
1902         index += 4 * 256;
1903         if (p->index_version == 1) {
1904                 return index + 24 * n + 4;
1905         } else {
1906                 index += 8;
1907                 return index + 20 * n;
1908         }
1909 }
1910
1911 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1912 {
1913         const unsigned char *index = p->index_data;
1914         index += 4 * 256;
1915         if (p->index_version == 1) {
1916                 return ntohl(*((uint32_t *)(index + 24 * n)));
1917         } else {
1918                 uint32_t off;
1919                 index += 8 + p->num_objects * (20 + 4);
1920                 off = ntohl(*((uint32_t *)(index + 4 * n)));
1921                 if (!(off & 0x80000000))
1922                         return off;
1923                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1924                 return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
1925                                    ntohl(*((uint32_t *)(index + 4)));
1926         }
1927 }
1928
1929 off_t find_pack_entry_one(const unsigned char *sha1,
1930                                   struct packed_git *p)
1931 {
1932         const uint32_t *level1_ofs = p->index_data;
1933         const unsigned char *index = p->index_data;
1934         unsigned hi, lo, stride;
1935         static int use_lookup = -1;
1936         static int debug_lookup = -1;
1937
1938         if (debug_lookup < 0)
1939                 debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
1940
1941         if (!index) {
1942                 if (open_pack_index(p))
1943                         return 0;
1944                 level1_ofs = p->index_data;
1945                 index = p->index_data;
1946         }
1947         if (p->index_version > 1) {
1948                 level1_ofs += 2;
1949                 index += 8;
1950         }
1951         index += 4 * 256;
1952         hi = ntohl(level1_ofs[*sha1]);
1953         lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1954         if (p->index_version > 1) {
1955                 stride = 20;
1956         } else {
1957                 stride = 24;
1958                 index += 4;
1959         }
1960
1961         if (debug_lookup)
1962                 printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
1963                        sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
1964
1965         if (use_lookup < 0)
1966                 use_lookup = !!getenv("GIT_USE_LOOKUP");
1967         if (use_lookup) {
1968                 int pos = sha1_entry_pos(index, stride, 0,
1969                                          lo, hi, p->num_objects, sha1);
1970                 if (pos < 0)
1971                         return 0;
1972                 return nth_packed_object_offset(p, pos);
1973         }
1974
1975         do {
1976                 unsigned mi = (lo + hi) / 2;
1977                 int cmp = hashcmp(index + mi * stride, sha1);
1978
1979                 if (debug_lookup)
1980                         printf("lo %u hi %u rg %u mi %u\n",
1981                                lo, hi, hi - lo, mi);
1982                 if (!cmp)
1983                         return nth_packed_object_offset(p, mi);
1984                 if (cmp > 0)
1985                         hi = mi;
1986                 else
1987                         lo = mi+1;
1988         } while (lo < hi);
1989         return 0;
1990 }
1991
1992 static int is_pack_valid(struct packed_git *p)
1993 {
1994         /* An already open pack is known to be valid. */
1995         if (p->pack_fd != -1)
1996                 return 1;
1997
1998         /* If the pack has one window completely covering the
1999          * file size, the pack is known to be valid even if
2000          * the descriptor is not currently open.
2001          */
2002         if (p->windows) {
2003                 struct pack_window *w = p->windows;
2004
2005                 if (!w->offset && w->len == p->pack_size)
2006                         return 1;
2007         }
2008
2009         /* Force the pack to open to prove its valid. */
2010         return !open_packed_git(p);
2011 }
2012
2013 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2014 {
2015         static struct packed_git *last_found = (void *)1;
2016         struct packed_git *p;
2017         off_t offset;
2018
2019         prepare_packed_git();
2020         if (!packed_git)
2021                 return 0;
2022         p = (last_found == (void *)1) ? packed_git : last_found;
2023
2024         do {
2025                 if (p->num_bad_objects) {
2026                         unsigned i;
2027                         for (i = 0; i < p->num_bad_objects; i++)
2028                                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2029                                         goto next;
2030                 }
2031
2032                 offset = find_pack_entry_one(sha1, p);
2033                 if (offset) {
2034                         /*
2035                          * We are about to tell the caller where they can
2036                          * locate the requested object.  We better make
2037                          * sure the packfile is still here and can be
2038                          * accessed before supplying that answer, as
2039                          * it may have been deleted since the index
2040                          * was loaded!
2041                          */
2042                         if (!is_pack_valid(p)) {
2043                                 error("packfile %s cannot be accessed", p->pack_name);
2044                                 goto next;
2045                         }
2046                         e->offset = offset;
2047                         e->p = p;
2048                         hashcpy(e->sha1, sha1);
2049                         last_found = p;
2050                         return 1;
2051                 }
2052
2053                 next:
2054                 if (p == last_found)
2055                         p = packed_git;
2056                 else
2057                         p = p->next;
2058                 if (p == last_found)
2059                         p = p->next;
2060         } while (p);
2061         return 0;
2062 }
2063
2064 struct packed_git *find_sha1_pack(const unsigned char *sha1,
2065                                   struct packed_git *packs)
2066 {
2067         struct packed_git *p;
2068
2069         for (p = packs; p; p = p->next) {
2070                 if (find_pack_entry_one(sha1, p))
2071                         return p;
2072         }
2073         return NULL;
2074
2075 }
2076
2077 static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
2078 {
2079         int status;
2080         unsigned long mapsize, size;
2081         void *map;
2082         git_zstream stream;
2083         char hdr[32];
2084
2085         map = map_sha1_file(sha1, &mapsize);
2086         if (!map)
2087                 return error("unable to find %s", sha1_to_hex(sha1));
2088         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2089                 status = error("unable to unpack %s header",
2090                                sha1_to_hex(sha1));
2091         else if ((status = parse_sha1_header(hdr, &size)) < 0)
2092                 status = error("unable to parse %s header", sha1_to_hex(sha1));
2093         else if (sizep)
2094                 *sizep = size;
2095         git_inflate_end(&stream);
2096         munmap(map, mapsize);
2097         return status;
2098 }
2099
2100 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2101 {
2102         struct cached_object *co;
2103         struct pack_entry e;
2104         int status;
2105
2106         co = find_cached_object(sha1);
2107         if (co) {
2108                 if (sizep)
2109                         *sizep = co->size;
2110                 return co->type;
2111         }
2112
2113         if (!find_pack_entry(sha1, &e)) {
2114                 /* Most likely it's a loose object. */
2115                 status = sha1_loose_object_info(sha1, sizep);
2116                 if (status >= 0)
2117                         return status;
2118
2119                 /* Not a loose object; someone else may have just packed it. */
2120                 reprepare_packed_git();
2121                 if (!find_pack_entry(sha1, &e))
2122                         return status;
2123         }
2124
2125         status = packed_object_info(e.p, e.offset, sizep);
2126         if (status < 0) {
2127                 mark_bad_packed_object(e.p, sha1);
2128                 status = sha1_object_info(sha1, sizep);
2129         }
2130
2131         return status;
2132 }
2133
2134 static void *read_packed_sha1(const unsigned char *sha1,
2135                               enum object_type *type, unsigned long *size)
2136 {
2137         struct pack_entry e;
2138         void *data;
2139
2140         if (!find_pack_entry(sha1, &e))
2141                 return NULL;
2142         data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2143         if (!data) {
2144                 /*
2145                  * We're probably in deep shit, but let's try to fetch
2146                  * the required object anyway from another pack or loose.
2147                  * This should happen only in the presence of a corrupted
2148                  * pack, and is better than failing outright.
2149                  */
2150                 error("failed to read object %s at offset %"PRIuMAX" from %s",
2151                       sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2152                 mark_bad_packed_object(e.p, sha1);
2153                 data = read_object(sha1, type, size);
2154         }
2155         return data;
2156 }
2157
2158 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2159                       unsigned char *sha1)
2160 {
2161         struct cached_object *co;
2162
2163         hash_sha1_file(buf, len, typename(type), sha1);
2164         if (has_sha1_file(sha1) || find_cached_object(sha1))
2165                 return 0;
2166         if (cached_object_alloc <= cached_object_nr) {
2167                 cached_object_alloc = alloc_nr(cached_object_alloc);
2168                 cached_objects = xrealloc(cached_objects,
2169                                           sizeof(*cached_objects) *
2170                                           cached_object_alloc);
2171         }
2172         co = &cached_objects[cached_object_nr++];
2173         co->size = len;
2174         co->type = type;
2175         co->buf = xmalloc(len);
2176         memcpy(co->buf, buf, len);
2177         hashcpy(co->sha1, sha1);
2178         return 0;
2179 }
2180
2181 static void *read_object(const unsigned char *sha1, enum object_type *type,
2182                          unsigned long *size)
2183 {
2184         unsigned long mapsize;
2185         void *map, *buf;
2186         struct cached_object *co;
2187
2188         co = find_cached_object(sha1);
2189         if (co) {
2190                 *type = co->type;
2191                 *size = co->size;
2192                 return xmemdupz(co->buf, co->size);
2193         }
2194
2195         buf = read_packed_sha1(sha1, type, size);
2196         if (buf)
2197                 return buf;
2198         map = map_sha1_file(sha1, &mapsize);
2199         if (map) {
2200                 buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2201                 munmap(map, mapsize);
2202                 return buf;
2203         }
2204         reprepare_packed_git();
2205         return read_packed_sha1(sha1, type, size);
2206 }
2207
2208 /*
2209  * This function dies on corrupt objects; the callers who want to
2210  * deal with them should arrange to call read_object() and give error
2211  * messages themselves.
2212  */
2213 void *read_sha1_file_extended(const unsigned char *sha1,
2214                               enum object_type *type,
2215                               unsigned long *size,
2216                               unsigned flag)
2217 {
2218         void *data;
2219         char *path;
2220         const struct packed_git *p;
2221         const unsigned char *repl = (flag & READ_SHA1_FILE_REPLACE)
2222                 ? lookup_replace_object(sha1) : sha1;
2223
2224         errno = 0;
2225         data = read_object(repl, type, size);
2226         if (data)
2227                 return data;
2228
2229         if (errno && errno != ENOENT)
2230                 die_errno("failed to read object %s", sha1_to_hex(sha1));
2231
2232         /* die if we replaced an object with one that does not exist */
2233         if (repl != sha1)
2234                 die("replacement %s not found for %s",
2235                     sha1_to_hex(repl), sha1_to_hex(sha1));
2236
2237         if (has_loose_object(repl)) {
2238                 path = sha1_file_name(sha1);
2239                 die("loose object %s (stored in %s) is corrupt",
2240                     sha1_to_hex(repl), path);
2241         }
2242
2243         if ((p = has_packed_and_bad(repl)) != NULL)
2244                 die("packed object %s (stored in %s) is corrupt",
2245                     sha1_to_hex(repl), p->pack_name);
2246
2247         return NULL;
2248 }
2249
2250 void *read_object_with_reference(const unsigned char *sha1,
2251                                  const char *required_type_name,
2252                                  unsigned long *size,
2253                                  unsigned char *actual_sha1_return)
2254 {
2255         enum object_type type, required_type;
2256         void *buffer;
2257         unsigned long isize;
2258         unsigned char actual_sha1[20];
2259
2260         required_type = type_from_string(required_type_name);
2261         hashcpy(actual_sha1, sha1);
2262         while (1) {
2263                 int ref_length = -1;
2264                 const char *ref_type = NULL;
2265
2266                 buffer = read_sha1_file(actual_sha1, &type, &isize);
2267                 if (!buffer)
2268                         return NULL;
2269                 if (type == required_type) {
2270                         *size = isize;
2271                         if (actual_sha1_return)
2272                                 hashcpy(actual_sha1_return, actual_sha1);
2273                         return buffer;
2274                 }
2275                 /* Handle references */
2276                 else if (type == OBJ_COMMIT)
2277                         ref_type = "tree ";
2278                 else if (type == OBJ_TAG)
2279                         ref_type = "object ";
2280                 else {
2281                         free(buffer);
2282                         return NULL;
2283                 }
2284                 ref_length = strlen(ref_type);
2285
2286                 if (ref_length + 40 > isize ||
2287                     memcmp(buffer, ref_type, ref_length) ||
2288                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2289                         free(buffer);
2290                         return NULL;
2291                 }
2292                 free(buffer);
2293                 /* Now we have the ID of the referred-to object in
2294                  * actual_sha1.  Check again. */
2295         }
2296 }
2297
2298 static void write_sha1_file_prepare(const void *buf, unsigned long len,
2299                                     const char *type, unsigned char *sha1,
2300                                     char *hdr, int *hdrlen)
2301 {
2302         git_SHA_CTX c;
2303
2304         /* Generate the header */
2305         *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2306
2307         /* Sha1.. */
2308         git_SHA1_Init(&c);
2309         git_SHA1_Update(&c, hdr, *hdrlen);
2310         git_SHA1_Update(&c, buf, len);
2311         git_SHA1_Final(sha1, &c);
2312 }
2313
2314 /*
2315  * Move the just written object into its final resting place.
2316  * NEEDSWORK: this should be renamed to finalize_temp_file() as
2317  * "moving" is only a part of what it does, when no patch between
2318  * master to pu changes the call sites of this function.
2319  */
2320 int move_temp_to_file(const char *tmpfile, const char *filename)
2321 {
2322         int ret = 0;
2323
2324         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2325                 goto try_rename;
2326         else if (link(tmpfile, filename))
2327                 ret = errno;
2328
2329         /*
2330          * Coda hack - coda doesn't like cross-directory links,
2331          * so we fall back to a rename, which will mean that it
2332          * won't be able to check collisions, but that's not a
2333          * big deal.
2334          *
2335          * The same holds for FAT formatted media.
2336          *
2337          * When this succeeds, we just return.  We have nothing
2338          * left to unlink.
2339          */
2340         if (ret && ret != EEXIST) {
2341         try_rename:
2342                 if (!rename(tmpfile, filename))
2343                         goto out;
2344                 ret = errno;
2345         }
2346         unlink_or_warn(tmpfile);
2347         if (ret) {
2348                 if (ret != EEXIST) {
2349                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
2350                 }
2351                 /* FIXME!!! Collision check here ? */
2352         }
2353
2354 out:
2355         if (adjust_shared_perm(filename))
2356                 return error("unable to set permission to '%s'", filename);
2357         return 0;
2358 }
2359
2360 static int write_buffer(int fd, const void *buf, size_t len)
2361 {
2362         if (write_in_full(fd, buf, len) < 0)
2363                 return error("file write error (%s)", strerror(errno));
2364         return 0;
2365 }
2366
2367 int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2368                    unsigned char *sha1)
2369 {
2370         char hdr[32];
2371         int hdrlen;
2372         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2373         return 0;
2374 }
2375
2376 /* Finalize a file on disk, and close it. */
2377 static void close_sha1_file(int fd)
2378 {
2379         if (fsync_object_files)
2380                 fsync_or_die(fd, "sha1 file");
2381         if (close(fd) != 0)
2382                 die_errno("error when closing sha1 file");
2383 }
2384
2385 /* Size of directory component, including the ending '/' */
2386 static inline int directory_size(const char *filename)
2387 {
2388         const char *s = strrchr(filename, '/');
2389         if (!s)
2390                 return 0;
2391         return s - filename + 1;
2392 }
2393
2394 /*
2395  * This creates a temporary file in the same directory as the final
2396  * 'filename'
2397  *
2398  * We want to avoid cross-directory filename renames, because those
2399  * can have problems on various filesystems (FAT, NFS, Coda).
2400  */
2401 static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2402 {
2403         int fd, dirlen = directory_size(filename);
2404
2405         if (dirlen + 20 > bufsiz) {
2406                 errno = ENAMETOOLONG;
2407                 return -1;
2408         }
2409         memcpy(buffer, filename, dirlen);
2410         strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2411         fd = git_mkstemp_mode(buffer, 0444);
2412         if (fd < 0 && dirlen && errno == ENOENT) {
2413                 /* Make sure the directory exists */
2414                 memcpy(buffer, filename, dirlen);
2415                 buffer[dirlen-1] = 0;
2416                 if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
2417                         return -1;
2418
2419                 /* Try again */
2420                 strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2421                 fd = git_mkstemp_mode(buffer, 0444);
2422         }
2423         return fd;
2424 }
2425
2426 static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2427                               const void *buf, unsigned long len, time_t mtime)
2428 {
2429         int fd, ret;
2430         unsigned char compressed[4096];
2431         git_zstream stream;
2432         git_SHA_CTX c;
2433         unsigned char parano_sha1[20];
2434         char *filename;
2435         static char tmpfile[PATH_MAX];
2436
2437         filename = sha1_file_name(sha1);
2438         fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
2439         if (fd < 0) {
2440                 if (errno == EACCES)
2441                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
2442                 else
2443                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
2444         }
2445
2446         /* Set it up */
2447         memset(&stream, 0, sizeof(stream));
2448         git_deflate_init(&stream, zlib_compression_level);
2449         stream.next_out = compressed;
2450         stream.avail_out = sizeof(compressed);
2451         git_SHA1_Init(&c);
2452
2453         /* First header.. */
2454         stream.next_in = (unsigned char *)hdr;
2455         stream.avail_in = hdrlen;
2456         while (git_deflate(&stream, 0) == Z_OK)
2457                 ; /* nothing */
2458         git_SHA1_Update(&c, hdr, hdrlen);
2459
2460         /* Then the data itself.. */
2461         stream.next_in = (void *)buf;
2462         stream.avail_in = len;
2463         do {
2464                 unsigned char *in0 = stream.next_in;
2465                 ret = git_deflate(&stream, Z_FINISH);
2466                 git_SHA1_Update(&c, in0, stream.next_in - in0);
2467                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2468                         die("unable to write sha1 file");
2469                 stream.next_out = compressed;
2470                 stream.avail_out = sizeof(compressed);
2471         } while (ret == Z_OK);
2472
2473         if (ret != Z_STREAM_END)
2474                 die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2475         ret = git_deflate_end_gently(&stream);
2476         if (ret != Z_OK)
2477                 die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2478         git_SHA1_Final(parano_sha1, &c);
2479         if (hashcmp(sha1, parano_sha1) != 0)
2480                 die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2481
2482         close_sha1_file(fd);
2483
2484         if (mtime) {
2485                 struct utimbuf utb;
2486                 utb.actime = mtime;
2487                 utb.modtime = mtime;
2488                 if (utime(tmpfile, &utb) < 0)
2489                         warning("failed utime() on %s: %s",
2490                                 tmpfile, strerror(errno));
2491         }
2492
2493         return move_temp_to_file(tmpfile, filename);
2494 }
2495
2496 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2497 {
2498         unsigned char sha1[20];
2499         char hdr[32];
2500         int hdrlen;
2501
2502         /* Normally if we have it in the pack then we do not bother writing
2503          * it out into .git/objects/??/?{38} file.
2504          */
2505         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2506         if (returnsha1)
2507                 hashcpy(returnsha1, sha1);
2508         if (has_sha1_file(sha1))
2509                 return 0;
2510         return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2511 }
2512
2513 int force_object_loose(const unsigned char *sha1, time_t mtime)
2514 {
2515         void *buf;
2516         unsigned long len;
2517         enum object_type type;
2518         char hdr[32];
2519         int hdrlen;
2520         int ret;
2521
2522         if (has_loose_object(sha1))
2523                 return 0;
2524         buf = read_packed_sha1(sha1, &type, &len);
2525         if (!buf)
2526                 return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2527         hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2528         ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2529         free(buf);
2530
2531         return ret;
2532 }
2533
2534 int has_pack_index(const unsigned char *sha1)
2535 {
2536         struct stat st;
2537         if (stat(sha1_pack_index_name(sha1), &st))
2538                 return 0;
2539         return 1;
2540 }
2541
2542 int has_sha1_pack(const unsigned char *sha1)
2543 {
2544         struct pack_entry e;
2545         return find_pack_entry(sha1, &e);
2546 }
2547
2548 int has_sha1_file(const unsigned char *sha1)
2549 {
2550         struct pack_entry e;
2551
2552         if (find_pack_entry(sha1, &e))
2553                 return 1;
2554         return has_loose_object(sha1);
2555 }
2556
2557 static void check_tree(const void *buf, size_t size)
2558 {
2559         struct tree_desc desc;
2560         struct name_entry entry;
2561
2562         init_tree_desc(&desc, buf, size);
2563         while (tree_entry(&desc, &entry))
2564                 /* do nothing
2565                  * tree_entry() will die() on malformed entries */
2566                 ;
2567 }
2568
2569 static void check_commit(const void *buf, size_t size)
2570 {
2571         struct commit c;
2572         memset(&c, 0, sizeof(c));
2573         if (parse_commit_buffer(&c, buf, size))
2574                 die("corrupt commit");
2575 }
2576
2577 static void check_tag(const void *buf, size_t size)
2578 {
2579         struct tag t;
2580         memset(&t, 0, sizeof(t));
2581         if (parse_tag_buffer(&t, buf, size))
2582                 die("corrupt tag");
2583 }
2584
2585 static int index_mem(unsigned char *sha1, void *buf, size_t size,
2586                      enum object_type type,
2587                      const char *path, unsigned flags)
2588 {
2589         int ret, re_allocated = 0;
2590         int write_object = flags & HASH_WRITE_OBJECT;
2591
2592         if (!type)
2593                 type = OBJ_BLOB;
2594
2595         /*
2596          * Convert blobs to git internal format
2597          */
2598         if ((type == OBJ_BLOB) && path) {
2599                 struct strbuf nbuf = STRBUF_INIT;
2600                 if (convert_to_git(path, buf, size, &nbuf,
2601                                    write_object ? safe_crlf : 0)) {
2602                         buf = strbuf_detach(&nbuf, &size);
2603                         re_allocated = 1;
2604                 }
2605         }
2606         if (flags & HASH_FORMAT_CHECK) {
2607                 if (type == OBJ_TREE)
2608                         check_tree(buf, size);
2609                 if (type == OBJ_COMMIT)
2610                         check_commit(buf, size);
2611                 if (type == OBJ_TAG)
2612                         check_tag(buf, size);
2613         }
2614
2615         if (write_object)
2616                 ret = write_sha1_file(buf, size, typename(type), sha1);
2617         else
2618                 ret = hash_sha1_file(buf, size, typename(type), sha1);
2619         if (re_allocated)
2620                 free(buf);
2621         return ret;
2622 }
2623
2624 static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
2625                       const char *path, unsigned flags)
2626 {
2627         struct strbuf sbuf = STRBUF_INIT;
2628         int ret;
2629
2630         if (strbuf_read(&sbuf, fd, 4096) >= 0)
2631                 ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
2632         else
2633                 ret = -1;
2634         strbuf_release(&sbuf);
2635         return ret;
2636 }
2637
2638 #define SMALL_FILE_SIZE (32*1024)
2639
2640 static int index_core(unsigned char *sha1, int fd, size_t size,
2641                       enum object_type type, const char *path,
2642                       unsigned flags)
2643 {
2644         int ret;
2645
2646         if (!size) {
2647                 ret = index_mem(sha1, NULL, size, type, path, flags);
2648         } else if (size <= SMALL_FILE_SIZE) {
2649                 char *buf = xmalloc(size);
2650                 if (size == read_in_full(fd, buf, size))
2651                         ret = index_mem(sha1, buf, size, type, path, flags);
2652                 else
2653                         ret = error("short read %s", strerror(errno));
2654                 free(buf);
2655         } else {
2656                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2657                 ret = index_mem(sha1, buf, size, type, path, flags);
2658                 munmap(buf, size);
2659         }
2660         return ret;
2661 }
2662
2663 /*
2664  * This creates one packfile per large blob, because the caller
2665  * immediately wants the result sha1, and fast-import can report the
2666  * object name via marks mechanism only by closing the created
2667  * packfile.
2668  *
2669  * This also bypasses the usual "convert-to-git" dance, and that is on
2670  * purpose. We could write a streaming version of the converting
2671  * functions and insert that before feeding the data to fast-import
2672  * (or equivalent in-core API described above), but the primary
2673  * motivation for trying to stream from the working tree file and to
2674  * avoid mmaping it in core is to deal with large binary blobs, and
2675  * by definition they do _not_ want to get any conversion.
2676  */
2677 static int index_stream(unsigned char *sha1, int fd, size_t size,
2678                         enum object_type type, const char *path,
2679                         unsigned flags)
2680 {
2681         struct child_process fast_import;
2682         char export_marks[512];
2683         const char *argv[] = { "fast-import", "--quiet", export_marks, NULL };
2684         char tmpfile[512];
2685         char fast_import_cmd[512];
2686         char buf[512];
2687         int len, tmpfd;
2688
2689         strcpy(tmpfile, git_path("hashstream_XXXXXX"));
2690         tmpfd = git_mkstemp_mode(tmpfile, 0600);
2691         if (tmpfd < 0)
2692                 die_errno("cannot create tempfile: %s", tmpfile);
2693         if (close(tmpfd))
2694                 die_errno("cannot close tempfile: %s", tmpfile);
2695         sprintf(export_marks, "--export-marks=%s", tmpfile);
2696
2697         memset(&fast_import, 0, sizeof(fast_import));
2698         fast_import.in = -1;
2699         fast_import.argv = argv;
2700         fast_import.git_cmd = 1;
2701         if (start_command(&fast_import))
2702                 die_errno("index-stream: git fast-import failed");
2703
2704         len = sprintf(fast_import_cmd, "blob\nmark :1\ndata %lu\n",
2705                       (unsigned long) size);
2706         write_or_whine(fast_import.in, fast_import_cmd, len,
2707                        "index-stream: feeding fast-import");
2708         while (size) {
2709                 char buf[10240];
2710                 size_t sz = size < sizeof(buf) ? size : sizeof(buf);
2711                 size_t actual;
2712
2713                 actual = read_in_full(fd, buf, sz);
2714                 if (actual < 0)
2715                         die_errno("index-stream: reading input");
2716                 if (write_in_full(fast_import.in, buf, actual) != actual)
2717                         die_errno("index-stream: feeding fast-import");
2718                 size -= actual;
2719         }
2720         if (close(fast_import.in))
2721                 die_errno("index-stream: closing fast-import");
2722         if (finish_command(&fast_import))
2723                 die_errno("index-stream: finishing fast-import");
2724
2725         tmpfd = open(tmpfile, O_RDONLY);
2726         if (tmpfd < 0)
2727                 die_errno("index-stream: cannot open fast-import mark");
2728         len = read(tmpfd, buf, sizeof(buf));
2729         if (len < 0)
2730                 die_errno("index-stream: reading fast-import mark");
2731         if (close(tmpfd) < 0)
2732                 die_errno("index-stream: closing fast-import mark");
2733         if (unlink(tmpfile))
2734                 die_errno("index-stream: unlinking fast-import mark");
2735         if (len != 44 ||
2736             memcmp(":1 ", buf, 3) ||
2737             get_sha1_hex(buf + 3, sha1))
2738                 die_errno("index-stream: unexpected fast-import mark: <%s>", buf);
2739         return 0;
2740 }
2741
2742 int index_fd(unsigned char *sha1, int fd, struct stat *st,
2743              enum object_type type, const char *path, unsigned flags)
2744 {
2745         int ret;
2746         size_t size = xsize_t(st->st_size);
2747
2748         if (!S_ISREG(st->st_mode))
2749                 ret = index_pipe(sha1, fd, type, path, flags);
2750         else if (size <= big_file_threshold || type != OBJ_BLOB)
2751                 ret = index_core(sha1, fd, size, type, path, flags);
2752         else
2753                 ret = index_stream(sha1, fd, size, type, path, flags);
2754         close(fd);
2755         return ret;
2756 }
2757
2758 int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
2759 {
2760         int fd;
2761         struct strbuf sb = STRBUF_INIT;
2762
2763         switch (st->st_mode & S_IFMT) {
2764         case S_IFREG:
2765                 fd = open(path, O_RDONLY);
2766                 if (fd < 0)
2767                         return error("open(\"%s\"): %s", path,
2768                                      strerror(errno));
2769                 if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
2770                         return error("%s: failed to insert into database",
2771                                      path);
2772                 break;
2773         case S_IFLNK:
2774                 if (strbuf_readlink(&sb, path, st->st_size)) {
2775                         char *errstr = strerror(errno);
2776                         return error("readlink(\"%s\"): %s", path,
2777                                      errstr);
2778                 }
2779                 if (!(flags & HASH_WRITE_OBJECT))
2780                         hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
2781                 else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
2782                         return error("%s: failed to insert into database",
2783                                      path);
2784                 strbuf_release(&sb);
2785                 break;
2786         case S_IFDIR:
2787                 return resolve_gitlink_ref(path, "HEAD", sha1);
2788         default:
2789                 return error("%s: unsupported file type", path);
2790         }
2791         return 0;
2792 }
2793
2794 int read_pack_header(int fd, struct pack_header *header)
2795 {
2796         if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
2797                 /* "eof before pack header was fully read" */
2798                 return PH_ERROR_EOF;
2799
2800         if (header->hdr_signature != htonl(PACK_SIGNATURE))
2801                 /* "protocol error (pack signature mismatch detected)" */
2802                 return PH_ERROR_PACK_SIGNATURE;
2803         if (!pack_version_ok(header->hdr_version))
2804                 /* "protocol error (pack version unsupported)" */
2805                 return PH_ERROR_PROTOCOL;
2806         return 0;
2807 }
2808
2809 void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
2810 {
2811         enum object_type type = sha1_object_info(sha1, NULL);
2812         if (type < 0)
2813                 die("%s is not a valid object", sha1_to_hex(sha1));
2814         if (type != expect)
2815                 die("%s is not a valid '%s' object", sha1_to_hex(sha1),
2816                     typename(expect));
2817 }