Pileus Git - ~andy/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 "string-list.h"
  11 #include "delta.h"
  12 #include "pack.h"
  13 #include "blob.h"
  14 #include "commit.h"
  15 #include "run-command.h"
  16 #include "tag.h"
  17 #include "tree.h"
  18 #include "tree-walk.h"
  19 #include "refs.h"
  20 #include "pack-revindex.h"
  21 #include "sha1-lookup.h"
  22 #include "bulk-checkin.h"
  23 #include "streaming.h"
  24 #include "dir.h"
  25
  26 #ifndef O_NOATIME
  27 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  28 #define O_NOATIME 01000000
  29 #else
  30 #define O_NOATIME 0
  31 #endif
  32 #endif
  33
  34 #define SZ_FMT PRIuMAX
  35 static inline uintmax_t sz_fmt(size_t s) { return s; }
  36
  37 const unsigned char null_sha1[20];
  38
  39 static const char *no_log_pack_access = "no_log_pack_access";
  40 static const char *log_pack_access;
  41
  42 /*
  43  * This is meant to hold a *small* number of objects that you would
  44  * want read_sha1_file() to be able to return, but yet you do not want
  45  * to write them into the object store (e.g. a browse-only
  46  * application).
  47  */
  48 static struct cached_object {
  49         unsigned char sha1[20];
  50         enum object_type type;
  51         void *buf;
  52         unsigned long size;
  53 } *cached_objects;
  54 static int cached_object_nr, cached_object_alloc;
  55
  56 static struct cached_object empty_tree = {
  57         EMPTY_TREE_SHA1_BIN_LITERAL,
  58         OBJ_TREE,
  59         "",
  60         0
  61 };
  62
  63 static struct packed_git *last_found_pack;
  64
  65 static struct cached_object *find_cached_object(const unsigned char *sha1)
  66 {
  67         int i;
  68         struct cached_object *co = cached_objects;
  69
  70         for (i = 0; i < cached_object_nr; i++, co++) {
  71                 if (!hashcmp(co->sha1, sha1))
  72                         return co;
  73         }
  74         if (!hashcmp(sha1, empty_tree.sha1))
  75                 return &empty_tree;
  76         return NULL;
  77 }
  78
  79 int mkdir_in_gitdir(const char *path)
  80 {
  81         if (mkdir(path, 0777)) {
  82                 int saved_errno = errno;
  83                 struct stat st;
  84                 struct strbuf sb = STRBUF_INIT;
  85
  86                 if (errno != EEXIST)
  87                         return -1;
  88                 /*
  89                  * Are we looking at a path in a symlinked worktree
  90                  * whose original repository does not yet have it?
  91                  * e.g. .git/rr-cache pointing at its original
  92                  * repository in which the user hasn't performed any
  93                  * conflict resolution yet?
  94                  */
  95                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
  96                     strbuf_readlink(&sb, path, st.st_size) ||
  97                     !is_absolute_path(sb.buf) ||
  98                     mkdir(sb.buf, 0777)) {
  99                         strbuf_release(&sb);
 100                         errno = saved_errno;
 101                         return -1;
 102                 }
 103                 strbuf_release(&sb);
 104         }
 105         return adjust_shared_perm(path);
 106 }
 107
 108 int safe_create_leading_directories(char *path)
 109 {
 110         char *pos = path + offset_1st_component(path);
 111         struct stat st;
 112
 113         while (pos) {
 114                 pos = strchr(pos, '/');
 115                 if (!pos)
 116                         break;
 117                 while (*++pos == '/')
 118                         ;
 119                 if (!*pos)
 120                         break;
 121                 *--pos = '\0';
 122                 if (!stat(path, &st)) {
 123                         /* path exists */
 124                         if (!S_ISDIR(st.st_mode)) {
 125                                 *pos = '/';
 126                                 return -3;
 127                         }
 128                 }
 129                 else if (mkdir(path, 0777)) {
 130                         if (errno == EEXIST &&
 131                             !stat(path, &st) && S_ISDIR(st.st_mode)) {
 132                                 ; /* somebody created it since we checked */
 133                         } else {
 134                                 *pos = '/';
 135                                 return -1;
 136                         }
 137                 }
 138                 else if (adjust_shared_perm(path)) {
 139                         *pos = '/';
 140                         return -2;
 141                 }
 142                 *pos++ = '/';
 143         }
 144         return 0;
 145 }
 146
 147 int safe_create_leading_directories_const(const char *path)
 148 {
 149         /* path points to cache entries, so xstrdup before messing with it */
 150         char *buf = xstrdup(path);
 151         int result = safe_create_leading_directories(buf);
 152         free(buf);
 153         return result;
 154 }
 155
 156 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 157 {
 158         int i;
 159         for (i = 0; i < 20; i++) {
 160                 static char hex[] = "0123456789abcdef";
 161                 unsigned int val = sha1[i];
 162                 char *pos = pathbuf + i*2 + (i > 0);
 163                 *pos++ = hex[val >> 4];
 164                 *pos = hex[val & 0xf];
 165         }
 166 }
 167
 168 /*
 169  * NOTE! This returns a statically allocated buffer, so you have to be
 170  * careful about using it. Do an "xstrdup()" if you need to save the
 171  * filename.
 172  *
 173  * Also note that this returns the location for creating.  Reading
 174  * SHA1 file can happen from any alternate directory listed in the
 175  * DB_ENVIRONMENT environment variable if it is not found in
 176  * the primary object database.
 177  */
 178 char *sha1_file_name(const unsigned char *sha1)
 179 {
 180         static char buf[PATH_MAX];
 181         const char *objdir;
 182         int len;
 183
 184         objdir = get_object_directory();
 185         len = strlen(objdir);
 186
 187         /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
 188         if (len + 43 > PATH_MAX)
 189                 die("insanely long object directory %s", objdir);
 190         memcpy(buf, objdir, len);
 191         buf[len] = '/';
 192         buf[len+3] = '/';
 193         buf[len+42] = '\0';
 194         fill_sha1_path(buf + len + 1, sha1);
 195         return buf;
 196 }
 197
 198 static char *sha1_get_pack_name(const unsigned char *sha1,
 199                                 char **name, char **base, const char *which)
 200 {
 201         static const char hex[] = "0123456789abcdef";
 202         char *buf;
 203         int i;
 204
 205         if (!*base) {
 206                 const char *sha1_file_directory = get_object_directory();
 207                 int len = strlen(sha1_file_directory);
 208                 *base = xmalloc(len + 60);
 209                 sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
 210                         sha1_file_directory, which);
 211                 *name = *base + len + 11;
 212         }
 213
 214         buf = *name;
 215
 216         for (i = 0; i < 20; i++) {
 217                 unsigned int val = *sha1++;
 218                 *buf++ = hex[val >> 4];
 219                 *buf++ = hex[val & 0xf];
 220         }
 221
 222         return *base;
 223 }
 224
 225 char *sha1_pack_name(const unsigned char *sha1)
 226 {
 227         static char *name, *base;
 228
 229         return sha1_get_pack_name(sha1, &name, &base, "pack");
 230 }
 231
 232 char *sha1_pack_index_name(const unsigned char *sha1)
 233 {
 234         static char *name, *base;
 235
 236         return sha1_get_pack_name(sha1, &name, &base, "idx");
 237 }
 238
 239 struct alternate_object_database *alt_odb_list;
 240 static struct alternate_object_database **alt_odb_tail;
 241
 242 static int git_open_noatime(const char *name);
 243
 244 /*
 245  * Prepare alternate object database registry.
 246  *
 247  * The variable alt_odb_list points at the list of struct
 248  * alternate_object_database.  The elements on this list come from
 249  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 250  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 251  * whose contents is similar to that environment variable but can be
 252  * LF separated.  Its base points at a statically allocated buffer that
 253  * contains "/the/directory/corresponding/to/.git/objects/...", while
 254  * its name points just after the slash at the end of ".git/objects/"
 255  * in the example above, and has enough space to hold 40-byte hex
 256  * SHA1, an extra slash for the first level indirection, and the
 257  * terminating NUL.
 258  */
 259 static int link_alt_odb_entry(const char *entry, const char *relative_base, int depth)
 260 {
 261         const char *objdir = get_object_directory();
 262         struct alternate_object_database *ent;
 263         struct alternate_object_database *alt;
 264         int pfxlen, entlen;
 265         struct strbuf pathbuf = STRBUF_INIT;
 266
 267         if (!is_absolute_path(entry) && relative_base) {
 268                 strbuf_addstr(&pathbuf, real_path(relative_base));
 269                 strbuf_addch(&pathbuf, '/');
 270         }
 271         strbuf_addstr(&pathbuf, entry);
 272
 273         normalize_path_copy(pathbuf.buf, pathbuf.buf);
 274
 275         pfxlen = strlen(pathbuf.buf);
 276
 277         /*
 278          * The trailing slash after the directory name is given by
 279          * this function at the end. Remove duplicates.
 280          */
 281         while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
 282                 pfxlen -= 1;
 283
 284         entlen = pfxlen + 43; /* '/' + 2 hex + '/' + 38 hex + NUL */
 285         ent = xmalloc(sizeof(*ent) + entlen);
 286         memcpy(ent->base, pathbuf.buf, pfxlen);
 287         strbuf_release(&pathbuf);
 288
 289         ent->name = ent->base + pfxlen + 1;
 290         ent->base[pfxlen + 3] = '/';
 291         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 292
 293         /* Detect cases where alternate disappeared */
 294         if (!is_directory(ent->base)) {
 295                 error("object directory %s does not exist; "
 296                       "check .git/objects/info/alternates.",
 297                       ent->base);
 298                 free(ent);
 299                 return -1;
 300         }
 301
 302         /* Prevent the common mistake of listing the same
 303          * thing twice, or object directory itself.
 304          */
 305         for (alt = alt_odb_list; alt; alt = alt->next) {
 306                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 307                         free(ent);
 308                         return -1;
 309                 }
 310         }
 311         if (!strcmp(ent->base, objdir)) {
 312                 free(ent);
 313                 return -1;
 314         }
 315
 316         /* add the alternate entry */
 317         *alt_odb_tail = ent;
 318         alt_odb_tail = &(ent->next);
 319         ent->next = NULL;
 320
 321         /* recursively add alternates */
 322         read_info_alternates(ent->base, depth + 1);
 323
 324         ent->base[pfxlen] = '/';
 325
 326         return 0;
 327 }
 328
 329 static void link_alt_odb_entries(const char *alt, int len, int sep,
 330                                  const char *relative_base, int depth)
 331 {
 332         struct string_list entries = STRING_LIST_INIT_NODUP;
 333         char *alt_copy;
 334         int i;
 335
 336         if (depth > 5) {
 337                 error("%s: ignoring alternate object stores, nesting too deep.",
 338                                 relative_base);
 339                 return;
 340         }
 341
 342         alt_copy = xmemdupz(alt, len);
 343         string_list_split_in_place(&entries, alt_copy, sep, -1);
 344         for (i = 0; i < entries.nr; i++) {
 345                 const char *entry = entries.items[i].string;
 346                 if (entry[0] == '\0' || entry[0] == '#')
 347                         continue;
 348                 if (!is_absolute_path(entry) && depth) {
 349                         error("%s: ignoring relative alternate object store %s",
 350                                         relative_base, entry);
 351                 } else {
 352                         link_alt_odb_entry(entry, relative_base, depth);
 353                 }
 354         }
 355         string_list_clear(&entries, 0);
 356         free(alt_copy);
 357 }
 358
 359 void read_info_alternates(const char * relative_base, int depth)
 360 {
 361         char *map;
 362         size_t mapsz;
 363         struct stat st;
 364         const char alt_file_name[] = "info/alternates";
 365         /* Given that relative_base is no longer than PATH_MAX,
 366            ensure that "path" has enough space to append "/", the
 367            file name, "info/alternates", and a trailing NUL.  */
 368         char path[PATH_MAX + 1 + sizeof alt_file_name];
 369         int fd;
 370
 371         sprintf(path, "%s/%s", relative_base, alt_file_name);
 372         fd = git_open_noatime(path);
 373         if (fd < 0)
 374                 return;
 375         if (fstat(fd, &st) || (st.st_size == 0)) {
 376                 close(fd);
 377                 return;
 378         }
 379         mapsz = xsize_t(st.st_size);
 380         map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 381         close(fd);
 382
 383         link_alt_odb_entries(map, mapsz, '\n', relative_base, depth);
 384
 385         munmap(map, mapsz);
 386 }
 387
 388 void add_to_alternates_file(const char *reference)
 389 {
 390         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 391         int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
 392         char *alt = mkpath("%s\n", reference);
 393         write_or_die(fd, alt, strlen(alt));
 394         if (commit_lock_file(lock))
 395                 die("could not close alternates file");
 396         if (alt_odb_tail)
 397                 link_alt_odb_entries(alt, strlen(alt), '\n', NULL, 0);
 398 }
 399
 400 void foreach_alt_odb(alt_odb_fn fn, void *cb)
 401 {
 402         struct alternate_object_database *ent;
 403
 404         prepare_alt_odb();
 405         for (ent = alt_odb_list; ent; ent = ent->next)
 406                 if (fn(ent, cb))
 407                         return;
 408 }
 409
 410 void prepare_alt_odb(void)
 411 {
 412         const char *alt;
 413
 414         if (alt_odb_tail)
 415                 return;
 416
 417         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 418         if (!alt) alt = "";
 419
 420         alt_odb_tail = &alt_odb_list;
 421         link_alt_odb_entries(alt, strlen(alt), PATH_SEP, NULL, 0);
 422
 423         read_info_alternates(get_object_directory(), 0);
 424 }
 425
 426 static int has_loose_object_local(const unsigned char *sha1)
 427 {
 428         char *name = sha1_file_name(sha1);
 429         return !access(name, F_OK);
 430 }
 431
 432 int has_loose_object_nonlocal(const unsigned char *sha1)
 433 {
 434         struct alternate_object_database *alt;
 435         prepare_alt_odb();
 436         for (alt = alt_odb_list; alt; alt = alt->next) {
 437                 fill_sha1_path(alt->name, sha1);
 438                 if (!access(alt->base, F_OK))
 439                         return 1;
 440         }
 441         return 0;
 442 }
 443
 444 static int has_loose_object(const unsigned char *sha1)
 445 {
 446         return has_loose_object_local(sha1) ||
 447                has_loose_object_nonlocal(sha1);
 448 }
 449
 450 static unsigned int pack_used_ctr;
 451 static unsigned int pack_mmap_calls;
 452 static unsigned int peak_pack_open_windows;
 453 static unsigned int pack_open_windows;
 454 static unsigned int pack_open_fds;
 455 static unsigned int pack_max_fds;
 456 static size_t peak_pack_mapped;
 457 static size_t pack_mapped;
 458 struct packed_git *packed_git;
 459
 460 void pack_report(void)
 461 {
 462         fprintf(stderr,
 463                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 464                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 465                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 466                 sz_fmt(getpagesize()),
 467                 sz_fmt(packed_git_window_size),
 468                 sz_fmt(packed_git_limit));
 469         fprintf(stderr,
 470                 "pack_report: pack_used_ctr            = %10u\n"
 471                 "pack_report: pack_mmap_calls          = %10u\n"
 472                 "pack_report: pack_open_windows        = %10u / %10u\n"
 473                 "pack_report: pack_mapped              = "
 474                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
 475                 pack_used_ctr,
 476                 pack_mmap_calls,
 477                 pack_open_windows, peak_pack_open_windows,
 478                 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 479 }
 480
 481 static int check_packed_git_idx(const char *path,  struct packed_git *p)
 482 {
 483         void *idx_map;
 484         struct pack_idx_header *hdr;
 485         size_t idx_size;
 486         uint32_t version, nr, i, *index;
 487         int fd = git_open_noatime(path);
 488         struct stat st;
 489
 490         if (fd < 0)
 491                 return -1;
 492         if (fstat(fd, &st)) {
 493                 close(fd);
 494                 return -1;
 495         }
 496         idx_size = xsize_t(st.st_size);
 497         if (idx_size < 4 * 256 + 20 + 20) {
 498                 close(fd);
 499                 return error("index file %s is too small", path);
 500         }
 501         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 502         close(fd);
 503
 504         hdr = idx_map;
 505         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 506                 version = ntohl(hdr->idx_version);
 507                 if (version < 2 || version > 2) {
 508                         munmap(idx_map, idx_size);
 509                         return error("index file %s is version %"PRIu32
 510                                      " and is not supported by this binary"
 511                                      " (try upgrading GIT to a newer version)",
 512                                      path, version);
 513                 }
 514         } else
 515                 version = 1;
 516
 517         nr = 0;
 518         index = idx_map;
 519         if (version > 1)
 520                 index += 2;  /* skip index header */
 521         for (i = 0; i < 256; i++) {
 522                 uint32_t n = ntohl(index[i]);
 523                 if (n < nr) {
 524                         munmap(idx_map, idx_size);
 525                         return error("non-monotonic index %s", path);
 526                 }
 527                 nr = n;
 528         }
 529
 530         if (version == 1) {
 531                 /*
 532                  * Total size:
 533                  *  - 256 index entries 4 bytes each
 534                  *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 535                  *  - 20-byte SHA1 of the packfile
 536                  *  - 20-byte SHA1 file checksum
 537                  */
 538                 if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 539                         munmap(idx_map, idx_size);
 540                         return error("wrong index v1 file size in %s", path);
 541                 }
 542         } else if (version == 2) {
 543                 /*
 544                  * Minimum size:
 545                  *  - 8 bytes of header
 546                  *  - 256 index entries 4 bytes each
 547                  *  - 20-byte sha1 entry * nr
 548                  *  - 4-byte crc entry * nr
 549                  *  - 4-byte offset entry * nr
 550                  *  - 20-byte SHA1 of the packfile
 551                  *  - 20-byte SHA1 file checksum
 552                  * And after the 4-byte offset table might be a
 553                  * variable sized table containing 8-byte entries
 554                  * for offsets larger than 2^31.
 555                  */
 556                 unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 557                 unsigned long max_size = min_size;
 558                 if (nr)
 559                         max_size += (nr - 1)*8;
 560                 if (idx_size < min_size || idx_size > max_size) {
 561                         munmap(idx_map, idx_size);
 562                         return error("wrong index v2 file size in %s", path);
 563                 }
 564                 if (idx_size != min_size &&
 565                     /*
 566                      * make sure we can deal with large pack offsets.
 567                      * 31-bit signed offset won't be enough, neither
 568                      * 32-bit unsigned one will be.
 569                      */
 570                     (sizeof(off_t) <= 4)) {
 571                         munmap(idx_map, idx_size);
 572                         return error("pack too large for current definition of off_t in %s", path);
 573                 }
 574         }
 575
 576         p->index_version = version;
 577         p->index_data = idx_map;
 578         p->index_size = idx_size;
 579         p->num_objects = nr;
 580         return 0;
 581 }
 582
 583 int open_pack_index(struct packed_git *p)
 584 {
 585         char *idx_name;
 586         int ret;
 587
 588         if (p->index_data)
 589                 return 0;
 590
 591         idx_name = xstrdup(p->pack_name);
 592         strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
 593         ret = check_packed_git_idx(idx_name, p);
 594         free(idx_name);
 595         return ret;
 596 }
 597
 598 static void scan_windows(struct packed_git *p,
 599         struct packed_git **lru_p,
 600         struct pack_window **lru_w,
 601         struct pack_window **lru_l)
 602 {
 603         struct pack_window *w, *w_l;
 604
 605         for (w_l = NULL, w = p->windows; w; w = w->next) {
 606                 if (!w->inuse_cnt) {
 607                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 608                                 *lru_p = p;
 609                                 *lru_w = w;
 610                                 *lru_l = w_l;
 611                         }
 612                 }
 613                 w_l = w;
 614         }
 615 }
 616
 617 static int unuse_one_window(struct packed_git *current)
 618 {
 619         struct packed_git *p, *lru_p = NULL;
 620         struct pack_window *lru_w = NULL, *lru_l = NULL;
 621
 622         if (current)
 623                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 624         for (p = packed_git; p; p = p->next)
 625                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 626         if (lru_p) {
 627                 munmap(lru_w->base, lru_w->len);
 628                 pack_mapped -= lru_w->len;
 629                 if (lru_l)
 630                         lru_l->next = lru_w->next;
 631                 else
 632                         lru_p->windows = lru_w->next;
 633                 free(lru_w);
 634                 pack_open_windows--;
 635                 return 1;
 636         }
 637         return 0;
 638 }
 639
 640 void release_pack_memory(size_t need)
 641 {
 642         size_t cur = pack_mapped;
 643         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 644                 ; /* nothing */
 645 }
 646
 647 void *xmmap(void *start, size_t length,
 648         int prot, int flags, int fd, off_t offset)
 649 {
 650         void *ret = mmap(start, length, prot, flags, fd, offset);
 651         if (ret == MAP_FAILED) {
 652                 if (!length)
 653                         return NULL;
 654                 release_pack_memory(length);
 655                 ret = mmap(start, length, prot, flags, fd, offset);
 656                 if (ret == MAP_FAILED)
 657                         die_errno("Out of memory? mmap failed");
 658         }
 659         return ret;
 660 }
 661
 662 void close_pack_windows(struct packed_git *p)
 663 {
 664         while (p->windows) {
 665                 struct pack_window *w = p->windows;
 666
 667                 if (w->inuse_cnt)
 668                         die("pack '%s' still has open windows to it",
 669                             p->pack_name);
 670                 munmap(w->base, w->len);
 671                 pack_mapped -= w->len;
 672                 pack_open_windows--;
 673                 p->windows = w->next;
 674                 free(w);
 675         }
 676 }
 677
 678 /*
 679  * The LRU pack is the one with the oldest MRU window, preferring packs
 680  * with no used windows, or the oldest mtime if it has no windows allocated.
 681  */
 682 static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
 683 {
 684         struct pack_window *w, *this_mru_w;
 685         int has_windows_inuse = 0;
 686
 687         /*
 688          * Reject this pack if it has windows and the previously selected
 689          * one does not.  If this pack does not have windows, reject
 690          * it if the pack file is newer than the previously selected one.
 691          */
 692         if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
 693                 return;
 694
 695         for (w = this_mru_w = p->windows; w; w = w->next) {
 696                 /*
 697                  * Reject this pack if any of its windows are in use,
 698                  * but the previously selected pack did not have any
 699                  * inuse windows.  Otherwise, record that this pack
 700                  * has windows in use.
 701                  */
 702                 if (w->inuse_cnt) {
 703                         if (*accept_windows_inuse)
 704                                 has_windows_inuse = 1;
 705                         else
 706                                 return;
 707                 }
 708
 709                 if (w->last_used > this_mru_w->last_used)
 710                         this_mru_w = w;
 711
 712                 /*
 713                  * Reject this pack if it has windows that have been
 714                  * used more recently than the previously selected pack.
 715                  * If the previously selected pack had windows inuse and
 716                  * we have not encountered a window in this pack that is
 717                  * inuse, skip this check since we prefer a pack with no
 718                  * inuse windows to one that has inuse windows.
 719                  */
 720                 if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
 721                     this_mru_w->last_used > (*mru_w)->last_used)
 722                         return;
 723         }
 724
 725         /*
 726          * Select this pack.
 727          */
 728         *mru_w = this_mru_w;
 729         *lru_p = p;
 730         *accept_windows_inuse = has_windows_inuse;
 731 }
 732
 733 static int close_one_pack(void)
 734 {
 735         struct packed_git *p, *lru_p = NULL;
 736         struct pack_window *mru_w = NULL;
 737         int accept_windows_inuse = 1;
 738
 739         for (p = packed_git; p; p = p->next) {
 740                 if (p->pack_fd == -1)
 741                         continue;
 742                 find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
 743         }
 744
 745         if (lru_p) {
 746                 close(lru_p->pack_fd);
 747                 pack_open_fds--;
 748                 lru_p->pack_fd = -1;
 749                 return 1;
 750         }
 751
 752         return 0;
 753 }
 754
 755 void unuse_pack(struct pack_window **w_cursor)
 756 {
 757         struct pack_window *w = *w_cursor;
 758         if (w) {
 759                 w->inuse_cnt--;
 760                 *w_cursor = NULL;
 761         }
 762 }
 763
 764 void close_pack_index(struct packed_git *p)
 765 {
 766         if (p->index_data) {
 767                 munmap((void *)p->index_data, p->index_size);
 768                 p->index_data = NULL;
 769         }
 770 }
 771
 772 /*
 773  * This is used by git-repack in case a newly created pack happens to
 774  * contain the same set of objects as an existing one.  In that case
 775  * the resulting file might be different even if its name would be the
 776  * same.  It is best to close any reference to the old pack before it is
 777  * replaced on disk.  Of course no index pointers nor windows for given pack
 778  * must subsist at this point.  If ever objects from this pack are requested
 779  * again, the new version of the pack will be reinitialized through
 780  * reprepare_packed_git().
 781  */
 782 void free_pack_by_name(const char *pack_name)
 783 {
 784         struct packed_git *p, **pp = &packed_git;
 785
 786         while (*pp) {
 787                 p = *pp;
 788                 if (strcmp(pack_name, p->pack_name) == 0) {
 789                         clear_delta_base_cache();
 790                         close_pack_windows(p);
 791                         if (p->pack_fd != -1) {
 792                                 close(p->pack_fd);
 793                                 pack_open_fds--;
 794                         }
 795                         close_pack_index(p);
 796                         free(p->bad_object_sha1);
 797                         *pp = p->next;
 798                         if (last_found_pack == p)
 799                                 last_found_pack = NULL;
 800                         free(p);
 801                         return;
 802                 }
 803                 pp = &p->next;
 804         }
 805 }
 806
 807 static unsigned int get_max_fd_limit(void)
 808 {
 809 #ifdef RLIMIT_NOFILE
 810         struct rlimit lim;
 811
 812         if (getrlimit(RLIMIT_NOFILE, &lim))
 813                 die_errno("cannot get RLIMIT_NOFILE");
 814
 815         return lim.rlim_cur;
 816 #elif defined(_SC_OPEN_MAX)
 817         return sysconf(_SC_OPEN_MAX);
 818 #elif defined(OPEN_MAX)
 819         return OPEN_MAX;
 820 #else
 821         return 1; /* see the caller ;-) */
 822 #endif
 823 }
 824
 825 /*
 826  * Do not call this directly as this leaks p->pack_fd on error return;
 827  * call open_packed_git() instead.
 828  */
 829 static int open_packed_git_1(struct packed_git *p)
 830 {
 831         struct stat st;
 832         struct pack_header hdr;
 833         unsigned char sha1[20];
 834         unsigned char *idx_sha1;
 835         long fd_flag;
 836
 837         if (!p->index_data && open_pack_index(p))
 838                 return error("packfile %s index unavailable", p->pack_name);
 839
 840         if (!pack_max_fds) {
 841                 unsigned int max_fds = get_max_fd_limit();
 842
 843                 /* Save 3 for stdin/stdout/stderr, 22 for work */
 844                 if (25 < max_fds)
 845                         pack_max_fds = max_fds - 25;
 846                 else
 847                         pack_max_fds = 1;
 848         }
 849
 850         while (pack_max_fds <= pack_open_fds && close_one_pack())
 851                 ; /* nothing */
 852
 853         p->pack_fd = git_open_noatime(p->pack_name);
 854         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 855                 return -1;
 856         pack_open_fds++;
 857
 858         /* If we created the struct before we had the pack we lack size. */
 859         if (!p->pack_size) {
 860                 if (!S_ISREG(st.st_mode))
 861                         return error("packfile %s not a regular file", p->pack_name);
 862                 p->pack_size = st.st_size;
 863         } else if (p->pack_size != st.st_size)
 864                 return error("packfile %s size changed", p->pack_name);
 865
 866         /* We leave these file descriptors open with sliding mmap;
 867          * there is no point keeping them open across exec(), though.
 868          */
 869         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 870         if (fd_flag < 0)
 871                 return error("cannot determine file descriptor flags");
 872         fd_flag |= FD_CLOEXEC;
 873         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 874                 return error("cannot set FD_CLOEXEC");
 875
 876         /* Verify we recognize this pack file format. */
 877         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 878                 return error("file %s is far too short to be a packfile", p->pack_name);
 879         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 880                 return error("file %s is not a GIT packfile", p->pack_name);
 881         if (!pack_version_ok(hdr.hdr_version))
 882                 return error("packfile %s is version %"PRIu32" and not"
 883                         " supported (try upgrading GIT to a newer version)",
 884                         p->pack_name, ntohl(hdr.hdr_version));
 885
 886         /* Verify the pack matches its index. */
 887         if (p->num_objects != ntohl(hdr.hdr_entries))
 888                 return error("packfile %s claims to have %"PRIu32" objects"
 889                              " while index indicates %"PRIu32" objects",
 890                              p->pack_name, ntohl(hdr.hdr_entries),
 891                              p->num_objects);
 892         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 893                 return error("end of packfile %s is unavailable", p->pack_name);
 894         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 895                 return error("packfile %s signature is unavailable", p->pack_name);
 896         idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 897         if (hashcmp(sha1, idx_sha1))
 898                 return error("packfile %s does not match index", p->pack_name);
 899         return 0;
 900 }
 901
 902 static int open_packed_git(struct packed_git *p)
 903 {
 904         if (!open_packed_git_1(p))
 905                 return 0;
 906         if (p->pack_fd != -1) {
 907                 close(p->pack_fd);
 908                 pack_open_fds--;
 909                 p->pack_fd = -1;
 910         }
 911         return -1;
 912 }
 913
 914 static int in_window(struct pack_window *win, off_t offset)
 915 {
 916         /* We must promise at least 20 bytes (one hash) after the
 917          * offset is available from this window, otherwise the offset
 918          * is not actually in this window and a different window (which
 919          * has that one hash excess) must be used.  This is to support
 920          * the object header and delta base parsing routines below.
 921          */
 922         off_t win_off = win->offset;
 923         return win_off <= offset
 924                 && (offset + 20) <= (win_off + win->len);
 925 }
 926
 927 unsigned char *use_pack(struct packed_git *p,
 928                 struct pack_window **w_cursor,
 929                 off_t offset,
 930                 unsigned long *left)
 931 {
 932         struct pack_window *win = *w_cursor;
 933
 934         /* Since packfiles end in a hash of their content and it's
 935          * pointless to ask for an offset into the middle of that
 936          * hash, and the in_window function above wouldn't match
 937          * don't allow an offset too close to the end of the file.
 938          */
 939         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 940                 die("packfile %s cannot be accessed", p->pack_name);
 941         if (offset > (p->pack_size - 20))
 942                 die("offset beyond end of packfile (truncated pack?)");
 943
 944         if (!win || !in_window(win, offset)) {
 945                 if (win)
 946                         win->inuse_cnt--;
 947                 for (win = p->windows; win; win = win->next) {
 948                         if (in_window(win, offset))
 949                                 break;
 950                 }
 951                 if (!win) {
 952                         size_t window_align = packed_git_window_size / 2;
 953                         off_t len;
 954
 955                         if (p->pack_fd == -1 && open_packed_git(p))
 956                                 die("packfile %s cannot be accessed", p->pack_name);
 957
 958                         win = xcalloc(1, sizeof(*win));
 959                         win->offset = (offset / window_align) * window_align;
 960                         len = p->pack_size - win->offset;
 961                         if (len > packed_git_window_size)
 962                                 len = packed_git_window_size;
 963                         win->len = (size_t)len;
 964                         pack_mapped += win->len;
 965                         while (packed_git_limit < pack_mapped
 966                                 && unuse_one_window(p))
 967                                 ; /* nothing */
 968                         win->base = xmmap(NULL, win->len,
 969                                 PROT_READ, MAP_PRIVATE,
 970                                 p->pack_fd, win->offset);
 971                         if (win->base == MAP_FAILED)
 972                                 die("packfile %s cannot be mapped: %s",
 973                                         p->pack_name,
 974                                         strerror(errno));
 975                         if (!win->offset && win->len == p->pack_size
 976                                 && !p->do_not_close) {
 977                                 close(p->pack_fd);
 978                                 pack_open_fds--;
 979                                 p->pack_fd = -1;
 980                         }
 981                         pack_mmap_calls++;
 982                         pack_open_windows++;
 983                         if (pack_mapped > peak_pack_mapped)
 984                                 peak_pack_mapped = pack_mapped;
 985                         if (pack_open_windows > peak_pack_open_windows)
 986                                 peak_pack_open_windows = pack_open_windows;
 987                         win->next = p->windows;
 988                         p->windows = win;
 989                 }
 990         }
 991         if (win != *w_cursor) {
 992                 win->last_used = pack_used_ctr++;
 993                 win->inuse_cnt++;
 994                 *w_cursor = win;
 995         }
 996         offset -= win->offset;
 997         if (left)
 998                 *left = win->len - xsize_t(offset);
 999         return win->base + offset;
1000 }
1001
1002 static struct packed_git *alloc_packed_git(int extra)
1003 {
1004         struct packed_git *p = xmalloc(sizeof(*p) + extra);
1005         memset(p, 0, sizeof(*p));
1006         p->pack_fd = -1;
1007         return p;
1008 }
1009
1010 static void try_to_free_pack_memory(size_t size)
1011 {
1012         release_pack_memory(size);
1013 }
1014
1015 struct packed_git *add_packed_git(const char *path, int path_len, int local)
1016 {
1017         static int have_set_try_to_free_routine;
1018         struct stat st;
1019         struct packed_git *p = alloc_packed_git(path_len + 2);
1020
1021         if (!have_set_try_to_free_routine) {
1022                 have_set_try_to_free_routine = 1;
1023                 set_try_to_free_routine(try_to_free_pack_memory);
1024         }
1025
1026         /*
1027          * Make sure a corresponding .pack file exists and that
1028          * the index looks sane.
1029          */
1030         path_len -= strlen(".idx");
1031         if (path_len < 1) {
1032                 free(p);
1033                 return NULL;
1034         }
1035         memcpy(p->pack_name, path, path_len);
1036
1037         strcpy(p->pack_name + path_len, ".keep");
1038         if (!access(p->pack_name, F_OK))
1039                 p->pack_keep = 1;
1040
1041         strcpy(p->pack_name + path_len, ".pack");
1042         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
1043                 free(p);
1044                 return NULL;
1045         }
1046
1047         /* ok, it looks sane as far as we can check without
1048          * actually mapping the pack file.
1049          */
1050         p->pack_size = st.st_size;
1051         p->pack_local = local;
1052         p->mtime = st.st_mtime;
1053         if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
1054                 hashclr(p->sha1);
1055         return p;
1056 }
1057
1058 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
1059 {
1060         const char *path = sha1_pack_name(sha1);
1061         struct packed_git *p = alloc_packed_git(strlen(path) + 1);
1062
1063         strcpy(p->pack_name, path);
1064         hashcpy(p->sha1, sha1);
1065         if (check_packed_git_idx(idx_path, p)) {
1066                 free(p);
1067                 return NULL;
1068         }
1069
1070         return p;
1071 }
1072
1073 void install_packed_git(struct packed_git *pack)
1074 {
1075         if (pack->pack_fd != -1)
1076                 pack_open_fds++;
1077
1078         pack->next = packed_git;
1079         packed_git = pack;
1080 }
1081
1082 void (*report_garbage)(const char *desc, const char *path);
1083
1084 static void report_helper(const struct string_list *list,
1085                           int seen_bits, int first, int last)
1086 {
1087         const char *msg;
1088         switch (seen_bits) {
1089         case 0:
1090                 msg = "no corresponding .idx nor .pack";
1091                 break;
1092         case 1:
1093                 msg = "no corresponding .idx";
1094                 break;
1095         case 2:
1096                 msg = "no corresponding .pack";
1097                 break;
1098         default:
1099                 return;
1100         }
1101         for (; first < last; first++)
1102                 report_garbage(msg, list->items[first].string);
1103 }
1104
1105 static void report_pack_garbage(struct string_list *list)
1106 {
1107         int i, baselen = -1, first = 0, seen_bits = 0;
1108
1109         if (!report_garbage)
1110                 return;
1111
1112         sort_string_list(list);
1113
1114         for (i = 0; i < list->nr; i++) {
1115                 const char *path = list->items[i].string;
1116                 if (baselen != -1 &&
1117                     strncmp(path, list->items[first].string, baselen)) {
1118                         report_helper(list, seen_bits, first, i);
1119                         baselen = -1;
1120                         seen_bits = 0;
1121                 }
1122                 if (baselen == -1) {
1123                         const char *dot = strrchr(path, '.');
1124                         if (!dot) {
1125                                 report_garbage("garbage found", path);
1126                                 continue;
1127                         }
1128                         baselen = dot - path + 1;
1129                         first = i;
1130                 }
1131                 if (!strcmp(path + baselen, "pack"))
1132                         seen_bits |= 1;
1133                 else if (!strcmp(path + baselen, "idx"))
1134                         seen_bits |= 2;
1135         }
1136         report_helper(list, seen_bits, first, list->nr);
1137 }
1138
1139 static void prepare_packed_git_one(char *objdir, int local)
1140 {
1141         /* Ensure that this buffer is large enough so that we can
1142            append "/pack/" without clobbering the stack even if
1143            strlen(objdir) were PATH_MAX.  */
1144         char path[PATH_MAX + 1 + 4 + 1 + 1];
1145         int len;
1146         DIR *dir;
1147         struct dirent *de;
1148         struct string_list garbage = STRING_LIST_INIT_DUP;
1149
1150         sprintf(path, "%s/pack", objdir);
1151         len = strlen(path);
1152         dir = opendir(path);
1153         if (!dir) {
1154                 if (errno != ENOENT)
1155                         error("unable to open object pack directory: %s: %s",
1156                               path, strerror(errno));
1157                 return;
1158         }
1159         path[len++] = '/';
1160         while ((de = readdir(dir)) != NULL) {
1161                 int namelen = strlen(de->d_name);
1162                 struct packed_git *p;
1163
1164                 if (len + namelen + 1 > sizeof(path)) {
1165                         if (report_garbage) {
1166                                 struct strbuf sb = STRBUF_INIT;
1167                                 strbuf_addf(&sb, "%.*s/%s", len - 1, path, de->d_name);
1168                                 report_garbage("path too long", sb.buf);
1169                                 strbuf_release(&sb);
1170                         }
1171                         continue;
1172                 }
1173
1174                 if (is_dot_or_dotdot(de->d_name))
1175                         continue;
1176
1177                 strcpy(path + len, de->d_name);
1178
1179                 if (has_extension(de->d_name, ".idx")) {
1180                         /* Don't reopen a pack we already have. */
1181                         for (p = packed_git; p; p = p->next) {
1182                                 if (!memcmp(path, p->pack_name, len + namelen - 4))
1183                                         break;
1184                         }
1185                         if (p == NULL &&
1186                             /*
1187                              * See if it really is a valid .idx file with
1188                              * corresponding .pack file that we can map.
1189                              */
1190                             (p = add_packed_git(path, len + namelen, local)) != NULL)
1191                                 install_packed_git(p);
1192                 }
1193
1194                 if (!report_garbage)
1195                         continue;
1196
1197                 if (has_extension(de->d_name, ".idx") ||
1198                     has_extension(de->d_name, ".pack") ||
1199                     has_extension(de->d_name, ".keep"))
1200                         string_list_append(&garbage, path);
1201                 else
1202                         report_garbage("garbage found", path);
1203         }
1204         closedir(dir);
1205         report_pack_garbage(&garbage);
1206         string_list_clear(&garbage, 0);
1207 }
1208
1209 static int sort_pack(const void *a_, const void *b_)
1210 {
1211         struct packed_git *a = *((struct packed_git **)a_);
1212         struct packed_git *b = *((struct packed_git **)b_);
1213         int st;
1214
1215         /*
1216          * Local packs tend to contain objects specific to our
1217          * variant of the project than remote ones.  In addition,
1218          * remote ones could be on a network mounted filesystem.
1219          * Favor local ones for these reasons.
1220          */
1221         st = a->pack_local - b->pack_local;
1222         if (st)
1223                 return -st;
1224
1225         /*
1226          * Younger packs tend to contain more recent objects,
1227          * and more recent objects tend to get accessed more
1228          * often.
1229          */
1230         if (a->mtime < b->mtime)
1231                 return 1;
1232         else if (a->mtime == b->mtime)
1233                 return 0;
1234         return -1;
1235 }
1236
1237 static void rearrange_packed_git(void)
1238 {
1239         struct packed_git **ary, *p;
1240         int i, n;
1241
1242         for (n = 0, p = packed_git; p; p = p->next)
1243                 n++;
1244         if (n < 2)
1245                 return;
1246
1247         /* prepare an array of packed_git for easier sorting */
1248         ary = xcalloc(n, sizeof(struct packed_git *));
1249         for (n = 0, p = packed_git; p; p = p->next)
1250                 ary[n++] = p;
1251
1252         qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1253
1254         /* link them back again */
1255         for (i = 0; i < n - 1; i++)
1256                 ary[i]->next = ary[i + 1];
1257         ary[n - 1]->next = NULL;
1258         packed_git = ary[0];
1259
1260         free(ary);
1261 }
1262
1263 static int prepare_packed_git_run_once = 0;
1264 void prepare_packed_git(void)
1265 {
1266         struct alternate_object_database *alt;
1267
1268         if (prepare_packed_git_run_once)
1269                 return;
1270         prepare_packed_git_one(get_object_directory(), 1);
1271         prepare_alt_odb();
1272         for (alt = alt_odb_list; alt; alt = alt->next) {
1273                 alt->name[-1] = 0;
1274                 prepare_packed_git_one(alt->base, 0);
1275                 alt->name[-1] = '/';
1276         }
1277         rearrange_packed_git();
1278         prepare_packed_git_run_once = 1;
1279 }
1280
1281 void reprepare_packed_git(void)
1282 {
1283         discard_revindex();
1284         prepare_packed_git_run_once = 0;
1285         prepare_packed_git();
1286 }
1287
1288 static void mark_bad_packed_object(struct packed_git *p,
1289                                    const unsigned char *sha1)
1290 {
1291         unsigned i;
1292         for (i = 0; i < p->num_bad_objects; i++)
1293                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1294                         return;
1295         p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1296         hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1297         p->num_bad_objects++;
1298 }
1299
1300 static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1301 {
1302         struct packed_git *p;
1303         unsigned i;
1304
1305         for (p = packed_git; p; p = p->next)
1306                 for (i = 0; i < p->num_bad_objects; i++)
1307                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1308                                 return p;
1309         return NULL;
1310 }
1311
1312 /*
1313  * With an in-core object data in "map", rehash it to make sure the
1314  * object name actually matches "sha1" to detect object corruption.
1315  * With "map" == NULL, try reading the object named with "sha1" using
1316  * the streaming interface and rehash it to do the same.
1317  */
1318 int check_sha1_signature(const unsigned char *sha1, void *map,
1319                          unsigned long size, const char *type)
1320 {
1321         unsigned char real_sha1[20];
1322         enum object_type obj_type;
1323         struct git_istream *st;
1324         git_SHA_CTX c;
1325         char hdr[32];
1326         int hdrlen;
1327
1328         if (map) {
1329                 hash_sha1_file(map, size, type, real_sha1);
1330                 return hashcmp(sha1, real_sha1) ? -1 : 0;
1331         }
1332
1333         st = open_istream(sha1, &obj_type, &size, NULL);
1334         if (!st)
1335                 return -1;
1336
1337         /* Generate the header */
1338         hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
1339
1340         /* Sha1.. */
1341         git_SHA1_Init(&c);
1342         git_SHA1_Update(&c, hdr, hdrlen);
1343         for (;;) {
1344                 char buf[1024 * 16];
1345                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
1346
1347                 if (readlen < 0) {
1348                         close_istream(st);
1349                         return -1;
1350                 }
1351                 if (!readlen)
1352                         break;
1353                 git_SHA1_Update(&c, buf, readlen);
1354         }
1355         git_SHA1_Final(real_sha1, &c);
1356         close_istream(st);
1357         return hashcmp(sha1, real_sha1) ? -1 : 0;
1358 }
1359
1360 static int git_open_noatime(const char *name)
1361 {
1362         static int sha1_file_open_flag = O_NOATIME;
1363
1364         for (;;) {
1365                 int fd = open(name, O_RDONLY | sha1_file_open_flag);
1366                 if (fd >= 0)
1367                         return fd;
1368
1369                 /* Might the failure be due to O_NOATIME? */
1370                 if (errno != ENOENT && sha1_file_open_flag) {
1371                         sha1_file_open_flag = 0;
1372                         continue;
1373                 }
1374
1375                 return -1;
1376         }
1377 }
1378
1379 static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
1380 {
1381         char *name = sha1_file_name(sha1);
1382         struct alternate_object_database *alt;
1383
1384         if (!lstat(name, st))
1385                 return 0;
1386
1387         prepare_alt_odb();
1388         errno = ENOENT;
1389         for (alt = alt_odb_list; alt; alt = alt->next) {
1390                 name = alt->name;
1391                 fill_sha1_path(name, sha1);
1392                 if (!lstat(alt->base, st))
1393                         return 0;
1394         }
1395
1396         return -1;
1397 }
1398
1399 static int open_sha1_file(const unsigned char *sha1)
1400 {
1401         int fd;
1402         char *name = sha1_file_name(sha1);
1403         struct alternate_object_database *alt;
1404
1405         fd = git_open_noatime(name);
1406         if (fd >= 0)
1407                 return fd;
1408
1409         prepare_alt_odb();
1410         errno = ENOENT;
1411         for (alt = alt_odb_list; alt; alt = alt->next) {
1412                 name = alt->name;
1413                 fill_sha1_path(name, sha1);
1414                 fd = git_open_noatime(alt->base);
1415                 if (fd >= 0)
1416                         return fd;
1417         }
1418         return -1;
1419 }
1420
1421 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1422 {
1423         void *map;
1424         int fd;
1425
1426         fd = open_sha1_file(sha1);
1427         map = NULL;
1428         if (fd >= 0) {
1429                 struct stat st;
1430
1431                 if (!fstat(fd, &st)) {
1432                         *size = xsize_t(st.st_size);
1433                         if (!*size) {
1434                                 /* mmap() is forbidden on empty files */
1435                                 error("object file %s is empty", sha1_file_name(sha1));
1436                                 return NULL;
1437                         }
1438                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1439                 }
1440                 close(fd);
1441         }
1442         return map;
1443 }
1444
1445 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1446                 unsigned long len, enum object_type *type, unsigned long *sizep)
1447 {
1448         unsigned shift;
1449         unsigned long size, c;
1450         unsigned long used = 0;
1451
1452         c = buf[used++];
1453         *type = (c >> 4) & 7;
1454         size = c & 15;
1455         shift = 4;
1456         while (c & 0x80) {
1457                 if (len <= used || bitsizeof(long) <= shift) {
1458                         error("bad object header");
1459                         size = used = 0;
1460                         break;
1461                 }
1462                 c = buf[used++];
1463                 size += (c & 0x7f) << shift;
1464                 shift += 7;
1465         }
1466         *sizep = size;
1467         return used;
1468 }
1469
1470 int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1471 {
1472         /* Get the data stream */
1473         memset(stream, 0, sizeof(*stream));
1474         stream->next_in = map;
1475         stream->avail_in = mapsize;
1476         stream->next_out = buffer;
1477         stream->avail_out = bufsiz;
1478
1479         git_inflate_init(stream);
1480         return git_inflate(stream, 0);
1481 }
1482
1483 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1484 {
1485         int bytes = strlen(buffer) + 1;
1486         unsigned char *buf = xmallocz(size);
1487         unsigned long n;
1488         int status = Z_OK;
1489
1490         n = stream->total_out - bytes;
1491         if (n > size)
1492                 n = size;
1493         memcpy(buf, (char *) buffer + bytes, n);
1494         bytes = n;
1495         if (bytes <= size) {
1496                 /*
1497                  * The above condition must be (bytes <= size), not
1498                  * (bytes < size).  In other words, even though we
1499                  * expect no more output and set avail_out to zero,
1500                  * the input zlib stream may have bytes that express
1501                  * "this concludes the stream", and we *do* want to
1502                  * eat that input.
1503                  *
1504                  * Otherwise we would not be able to test that we
1505                  * consumed all the input to reach the expected size;
1506                  * we also want to check that zlib tells us that all
1507                  * went well with status == Z_STREAM_END at the end.
1508                  */
1509                 stream->next_out = buf + bytes;
1510                 stream->avail_out = size - bytes;
1511                 while (status == Z_OK)
1512                         status = git_inflate(stream, Z_FINISH);
1513         }
1514         if (status == Z_STREAM_END && !stream->avail_in) {
1515                 git_inflate_end(stream);
1516                 return buf;
1517         }
1518
1519         if (status < 0)
1520                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1521         else if (stream->avail_in)
1522                 error("garbage at end of loose object '%s'",
1523                       sha1_to_hex(sha1));
1524         free(buf);
1525         return NULL;
1526 }
1527
1528 /*
1529  * We used to just use "sscanf()", but that's actually way
1530  * too permissive for what we want to check. So do an anal
1531  * object header parse by hand.
1532  */
1533 int parse_sha1_header(const char *hdr, unsigned long *sizep)
1534 {
1535         char type[10];
1536         int i;
1537         unsigned long size;
1538
1539         /*
1540          * The type can be at most ten bytes (including the
1541          * terminating '\0' that we add), and is followed by
1542          * a space.
1543          */
1544         i = 0;
1545         for (;;) {
1546                 char c = *hdr++;
1547                 if (c == ' ')
1548                         break;
1549                 type[i++] = c;
1550                 if (i >= sizeof(type))
1551                         return -1;
1552         }
1553         type[i] = 0;
1554
1555         /*
1556          * The length must follow immediately, and be in canonical
1557          * decimal format (ie "010" is not valid).
1558          */
1559         size = *hdr++ - '0';
1560         if (size > 9)
1561                 return -1;
1562         if (size) {
1563                 for (;;) {
1564                         unsigned long c = *hdr - '0';
1565                         if (c > 9)
1566                                 break;
1567                         hdr++;
1568                         size = size * 10 + c;
1569                 }
1570         }
1571         *sizep = size;
1572
1573         /*
1574          * The length must be followed by a zero byte
1575          */
1576         return *hdr ? -1 : type_from_string(type);
1577 }
1578
1579 static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1580 {
1581         int ret;
1582         git_zstream stream;
1583         char hdr[8192];
1584
1585         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1586         if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1587                 return NULL;
1588
1589         return unpack_sha1_rest(&stream, hdr, *size, sha1);
1590 }
1591
1592 unsigned long get_size_from_delta(struct packed_git *p,
1593                                   struct pack_window **w_curs,
1594                                   off_t curpos)
1595 {
1596         const unsigned char *data;
1597         unsigned char delta_head[20], *in;
1598         git_zstream stream;
1599         int st;
1600
1601         memset(&stream, 0, sizeof(stream));
1602         stream.next_out = delta_head;
1603         stream.avail_out = sizeof(delta_head);
1604
1605         git_inflate_init(&stream);
1606         do {
1607                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1608                 stream.next_in = in;
1609                 st = git_inflate(&stream, Z_FINISH);
1610                 curpos += stream.next_in - in;
1611         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1612                  stream.total_out < sizeof(delta_head));
1613         git_inflate_end(&stream);
1614         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1615                 error("delta data unpack-initial failed");
1616                 return 0;
1617         }
1618
1619         /* Examine the initial part of the delta to figure out
1620          * the result size.
1621          */
1622         data = delta_head;
1623
1624         /* ignore base size */
1625         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1626
1627         /* Read the result size */
1628         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1629 }
1630
1631 static off_t get_delta_base(struct packed_git *p,
1632                                     struct pack_window **w_curs,
1633                                     off_t *curpos,
1634                                     enum object_type type,
1635                                     off_t delta_obj_offset)
1636 {
1637         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1638         off_t base_offset;
1639
1640         /* use_pack() assured us we have [base_info, base_info + 20)
1641          * as a range that we can look at without walking off the
1642          * end of the mapped window.  Its actually the hash size
1643          * that is assured.  An OFS_DELTA longer than the hash size
1644          * is stupid, as then a REF_DELTA would be smaller to store.
1645          */
1646         if (type == OBJ_OFS_DELTA) {
1647                 unsigned used = 0;
1648                 unsigned char c = base_info[used++];
1649                 base_offset = c & 127;
1650                 while (c & 128) {
1651                         base_offset += 1;
1652                         if (!base_offset || MSB(base_offset, 7))
1653                                 return 0;  /* overflow */
1654                         c = base_info[used++];
1655                         base_offset = (base_offset << 7) + (c & 127);
1656                 }
1657                 base_offset = delta_obj_offset - base_offset;
1658                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1659                         return 0;  /* out of bound */
1660                 *curpos += used;
1661         } else if (type == OBJ_REF_DELTA) {
1662                 /* The base entry _must_ be in the same pack */
1663                 base_offset = find_pack_entry_one(base_info, p);
1664                 *curpos += 20;
1665         } else
1666                 die("I am totally screwed");
1667         return base_offset;
1668 }
1669
1670 /*
1671  * Like get_delta_base above, but we return the sha1 instead of the pack
1672  * offset. This means it is cheaper for REF deltas (we do not have to do
1673  * the final object lookup), but more expensive for OFS deltas (we
1674  * have to load the revidx to convert the offset back into a sha1).
1675  */
1676 static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1677                                                 struct pack_window **w_curs,
1678                                                 off_t curpos,
1679                                                 enum object_type type,
1680                                                 off_t delta_obj_offset)
1681 {
1682         if (type == OBJ_REF_DELTA) {
1683                 unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1684                 return base;
1685         } else if (type == OBJ_OFS_DELTA) {
1686                 struct revindex_entry *revidx;
1687                 off_t base_offset = get_delta_base(p, w_curs, &curpos,
1688                                                    type, delta_obj_offset);
1689
1690                 if (!base_offset)
1691                         return NULL;
1692
1693                 revidx = find_pack_revindex(p, base_offset);
1694                 if (!revidx)
1695                         return NULL;
1696
1697                 return nth_packed_object_sha1(p, revidx->nr);
1698         } else
1699                 return NULL;
1700 }
1701
1702 int unpack_object_header(struct packed_git *p,
1703                          struct pack_window **w_curs,
1704                          off_t *curpos,
1705                          unsigned long *sizep)
1706 {
1707         unsigned char *base;
1708         unsigned long left;
1709         unsigned long used;
1710         enum object_type type;
1711
1712         /* use_pack() assures us we have [base, base + 20) available
1713          * as a range that we can look at.  (Its actually the hash
1714          * size that is assured.)  With our object header encoding
1715          * the maximum deflated object size is 2^137, which is just
1716          * insane, so we know won't exceed what we have been given.
1717          */
1718         base = use_pack(p, w_curs, *curpos, &left);
1719         used = unpack_object_header_buffer(base, left, &type, sizep);
1720         if (!used) {
1721                 type = OBJ_BAD;
1722         } else
1723                 *curpos += used;
1724
1725         return type;
1726 }
1727
1728 static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
1729 {
1730         int type;
1731         struct revindex_entry *revidx;
1732         const unsigned char *sha1;
1733         revidx = find_pack_revindex(p, obj_offset);
1734         if (!revidx)
1735                 return OBJ_BAD;
1736         sha1 = nth_packed_object_sha1(p, revidx->nr);
1737         mark_bad_packed_object(p, sha1);
1738         type = sha1_object_info(sha1, NULL);
1739         if (type <= OBJ_NONE)
1740                 return OBJ_BAD;
1741         return type;
1742 }
1743
1744 #define POI_STACK_PREALLOC 64
1745
1746 static enum object_type packed_to_object_type(struct packed_git *p,
1747                                               off_t obj_offset,
1748                                               enum object_type type,
1749                                               struct pack_window **w_curs,
1750                                               off_t curpos)
1751 {
1752         off_t small_poi_stack[POI_STACK_PREALLOC];
1753         off_t *poi_stack = small_poi_stack;
1754         int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1755
1756         while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1757                 off_t base_offset;
1758                 unsigned long size;
1759                 /* Push the object we're going to leave behind */
1760                 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1761                         poi_stack_alloc = alloc_nr(poi_stack_nr);
1762                         poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
1763                         memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1764                 } else {
1765                         ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1766                 }
1767                 poi_stack[poi_stack_nr++] = obj_offset;
1768                 /* If parsing the base offset fails, just unwind */
1769                 base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1770                 if (!base_offset)
1771                         goto unwind;
1772                 curpos = obj_offset = base_offset;
1773                 type = unpack_object_header(p, w_curs, &curpos, &size);
1774                 if (type <= OBJ_NONE) {
1775                         /* If getting the base itself fails, we first
1776                          * retry the base, otherwise unwind */
1777                         type = retry_bad_packed_offset(p, base_offset);
1778                         if (type > OBJ_NONE)
1779                                 goto out;
1780                         goto unwind;
1781                 }
1782         }
1783
1784         switch (type) {
1785         case OBJ_BAD:
1786         case OBJ_COMMIT:
1787         case OBJ_TREE:
1788         case OBJ_BLOB:
1789         case OBJ_TAG:
1790                 break;
1791         default:
1792                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1793                       type, (uintmax_t)obj_offset, p->pack_name);
1794                 type = OBJ_BAD;
1795         }
1796
1797 out:
1798         if (poi_stack != small_poi_stack)
1799                 free(poi_stack);
1800         return type;
1801
1802 unwind:
1803         while (poi_stack_nr) {
1804                 obj_offset = poi_stack[--poi_stack_nr];
1805                 type = retry_bad_packed_offset(p, obj_offset);
1806                 if (type > OBJ_NONE)
1807                         goto out;
1808         }
1809         type = OBJ_BAD;
1810         goto out;
1811 }
1812
1813 static int packed_object_info(struct packed_git *p, off_t obj_offset,
1814                               struct object_info *oi)
1815 {
1816         struct pack_window *w_curs = NULL;
1817         unsigned long size;
1818         off_t curpos = obj_offset;
1819         enum object_type type;
1820
1821         /*
1822          * We always get the representation type, but only convert it to
1823          * a "real" type later if the caller is interested.
1824          */
1825         type = unpack_object_header(p, &w_curs, &curpos, &size);
1826
1827         if (oi->sizep) {
1828                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1829                         off_t tmp_pos = curpos;
1830                         off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1831                                                            type, obj_offset);
1832                         if (!base_offset) {
1833                                 type = OBJ_BAD;
1834                                 goto out;
1835                         }
1836                         *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1837                         if (*oi->sizep == 0) {
1838                                 type = OBJ_BAD;
1839                                 goto out;
1840                         }
1841                 } else {
1842                         *oi->sizep = size;
1843                 }
1844         }
1845
1846         if (oi->disk_sizep) {
1847                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1848                 *oi->disk_sizep = revidx[1].offset - obj_offset;
1849         }
1850
1851         if (oi->typep) {
1852                 *oi->typep = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
1853                 if (*oi->typep < 0) {
1854                         type = OBJ_BAD;
1855                         goto out;
1856                 }
1857         }
1858
1859         if (oi->delta_base_sha1) {
1860                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1861                         const unsigned char *base;
1862
1863                         base = get_delta_base_sha1(p, &w_curs, curpos,
1864                                                    type, obj_offset);
1865                         if (!base) {
1866                                 type = OBJ_BAD;
1867                                 goto out;
1868                         }
1869
1870                         hashcpy(oi->delta_base_sha1, base);
1871                 } else
1872                         hashclr(oi->delta_base_sha1);
1873         }
1874
1875 out:
1876         unuse_pack(&w_curs);
1877         return type;
1878 }
1879
1880 static void *unpack_compressed_entry(struct packed_git *p,
1881                                     struct pack_window **w_curs,
1882                                     off_t curpos,
1883                                     unsigned long size)
1884 {
1885         int st;
1886         git_zstream stream;
1887         unsigned char *buffer, *in;
1888
1889         buffer = xmallocz(size);
1890         memset(&stream, 0, sizeof(stream));
1891         stream.next_out = buffer;
1892         stream.avail_out = size + 1;
1893
1894         git_inflate_init(&stream);
1895         do {
1896                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1897                 stream.next_in = in;
1898                 st = git_inflate(&stream, Z_FINISH);
1899                 if (!stream.avail_out)
1900                         break; /* the payload is larger than it should be */
1901                 curpos += stream.next_in - in;
1902         } while (st == Z_OK || st == Z_BUF_ERROR);
1903         git_inflate_end(&stream);
1904         if ((st != Z_STREAM_END) || stream.total_out != size) {
1905                 free(buffer);
1906                 return NULL;
1907         }
1908
1909         return buffer;
1910 }
1911
1912 #define MAX_DELTA_CACHE (256)
1913
1914 static size_t delta_base_cached;
1915
1916 static struct delta_base_cache_lru_list {
1917         struct delta_base_cache_lru_list *prev;
1918         struct delta_base_cache_lru_list *next;
1919 } delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1920
1921 static struct delta_base_cache_entry {
1922         struct delta_base_cache_lru_list lru;
1923         void *data;
1924         struct packed_git *p;
1925         off_t base_offset;
1926         unsigned long size;
1927         enum object_type type;
1928 } delta_base_cache[MAX_DELTA_CACHE];
1929
1930 static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1931 {
1932         unsigned long hash;
1933
1934         hash = (unsigned long)p + (unsigned long)base_offset;
1935         hash += (hash >> 8) + (hash >> 16);
1936         return hash % MAX_DELTA_CACHE;
1937 }
1938
1939 static struct delta_base_cache_entry *
1940 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1941 {
1942         unsigned long hash = pack_entry_hash(p, base_offset);
1943         return delta_base_cache + hash;
1944 }
1945
1946 static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
1947                                      struct packed_git *p, off_t base_offset)
1948 {
1949         return (ent->data && ent->p == p && ent->base_offset == base_offset);
1950 }
1951
1952 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1953 {
1954         struct delta_base_cache_entry *ent;
1955         ent = get_delta_base_cache_entry(p, base_offset);
1956         return eq_delta_base_cache_entry(ent, p, base_offset);
1957 }
1958
1959 static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1960 {
1961         ent->data = NULL;
1962         ent->lru.next->prev = ent->lru.prev;
1963         ent->lru.prev->next = ent->lru.next;
1964         delta_base_cached -= ent->size;
1965 }
1966
1967 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1968         unsigned long *base_size, enum object_type *type, int keep_cache)
1969 {
1970         struct delta_base_cache_entry *ent;
1971         void *ret;
1972
1973         ent = get_delta_base_cache_entry(p, base_offset);
1974
1975         if (!eq_delta_base_cache_entry(ent, p, base_offset))
1976                 return unpack_entry(p, base_offset, type, base_size);
1977
1978         ret = ent->data;
1979
1980         if (!keep_cache)
1981                 clear_delta_base_cache_entry(ent);
1982         else
1983                 ret = xmemdupz(ent->data, ent->size);
1984         *type = ent->type;
1985         *base_size = ent->size;
1986         return ret;
1987 }
1988
1989 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1990 {
1991         if (ent->data) {
1992                 free(ent->data);
1993                 ent->data = NULL;
1994                 ent->lru.next->prev = ent->lru.prev;
1995                 ent->lru.prev->next = ent->lru.next;
1996                 delta_base_cached -= ent->size;
1997         }
1998 }
1999
2000 void clear_delta_base_cache(void)
2001 {
2002         unsigned long p;
2003         for (p = 0; p < MAX_DELTA_CACHE; p++)
2004                 release_delta_base_cache(&delta_base_cache[p]);
2005 }
2006
2007 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
2008         void *base, unsigned long base_size, enum object_type type)
2009 {
2010         unsigned long hash = pack_entry_hash(p, base_offset);
2011         struct delta_base_cache_entry *ent = delta_base_cache + hash;
2012         struct delta_base_cache_lru_list *lru;
2013
2014         release_delta_base_cache(ent);
2015         delta_base_cached += base_size;
2016
2017         for (lru = delta_base_cache_lru.next;
2018              delta_base_cached > delta_base_cache_limit
2019              && lru != &delta_base_cache_lru;
2020              lru = lru->next) {
2021                 struct delta_base_cache_entry *f = (void *)lru;
2022                 if (f->type == OBJ_BLOB)
2023                         release_delta_base_cache(f);
2024         }
2025         for (lru = delta_base_cache_lru.next;
2026              delta_base_cached > delta_base_cache_limit
2027              && lru != &delta_base_cache_lru;
2028              lru = lru->next) {
2029                 struct delta_base_cache_entry *f = (void *)lru;
2030                 release_delta_base_cache(f);
2031         }
2032
2033         ent->p = p;
2034         ent->base_offset = base_offset;
2035         ent->type = type;
2036         ent->data = base;
2037         ent->size = base_size;
2038         ent->lru.next = &delta_base_cache_lru;
2039         ent->lru.prev = delta_base_cache_lru.prev;
2040         delta_base_cache_lru.prev->next = &ent->lru;
2041         delta_base_cache_lru.prev = &ent->lru;
2042 }
2043
2044 static void *read_object(const unsigned char *sha1, enum object_type *type,
2045                          unsigned long *size);
2046
2047 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
2048 {
2049         static FILE *log_file;
2050
2051         if (!log_pack_access)
2052                 log_pack_access = getenv("GIT_TRACE_PACK_ACCESS");
2053         if (!log_pack_access)
2054                 log_pack_access = no_log_pack_access;
2055         if (log_pack_access == no_log_pack_access)
2056                 return;
2057
2058         if (!log_file) {
2059                 log_file = fopen(log_pack_access, "w");
2060                 if (!log_file) {
2061                         error("cannot open pack access log '%s' for writing: %s",
2062                               log_pack_access, strerror(errno));
2063                         log_pack_access = no_log_pack_access;
2064                         return;
2065                 }
2066         }
2067         fprintf(log_file, "%s %"PRIuMAX"\n",
2068                 p->pack_name, (uintmax_t)obj_offset);
2069         fflush(log_file);
2070 }
2071
2072 int do_check_packed_object_crc;
2073
2074 #define UNPACK_ENTRY_STACK_PREALLOC 64
2075 struct unpack_entry_stack_ent {
2076         off_t obj_offset;
2077         off_t curpos;
2078         unsigned long size;
2079 };
2080
2081 void *unpack_entry(struct packed_git *p, off_t obj_offset,
2082                    enum object_type *final_type, unsigned long *final_size)
2083 {
2084         struct pack_window *w_curs = NULL;
2085         off_t curpos = obj_offset;
2086         void *data = NULL;
2087         unsigned long size;
2088         enum object_type type;
2089         struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
2090         struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
2091         int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
2092         int base_from_cache = 0;
2093
2094         if (log_pack_access != no_log_pack_access)
2095                 write_pack_access_log(p, obj_offset);
2096
2097         /* PHASE 1: drill down to the innermost base object */
2098         for (;;) {
2099                 off_t base_offset;
2100                 int i;
2101                 struct delta_base_cache_entry *ent;
2102
2103                 ent = get_delta_base_cache_entry(p, curpos);
2104                 if (eq_delta_base_cache_entry(ent, p, curpos)) {
2105                         type = ent->type;
2106                         data = ent->data;
2107                         size = ent->size;
2108                         clear_delta_base_cache_entry(ent);
2109                         base_from_cache = 1;
2110                         break;
2111                 }
2112
2113                 if (do_check_packed_object_crc && p->index_version > 1) {
2114                         struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2115                         unsigned long len = revidx[1].offset - obj_offset;
2116                         if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
2117                                 const unsigned char *sha1 =
2118                                         nth_packed_object_sha1(p, revidx->nr);
2119                                 error("bad packed object CRC for %s",
2120                                       sha1_to_hex(sha1));
2121                                 mark_bad_packed_object(p, sha1);
2122                                 unuse_pack(&w_curs);
2123                                 return NULL;
2124                         }
2125                 }
2126
2127                 type = unpack_object_header(p, &w_curs, &curpos, &size);
2128                 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
2129                         break;
2130
2131                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
2132                 if (!base_offset) {
2133                         error("failed to validate delta base reference "
2134                               "at offset %"PRIuMAX" from %s",
2135                               (uintmax_t)curpos, p->pack_name);
2136                         /* bail to phase 2, in hopes of recovery */
2137                         data = NULL;
2138                         break;
2139                 }
2140
2141                 /* push object, proceed to base */
2142                 if (delta_stack_nr >= delta_stack_alloc
2143                     && delta_stack == small_delta_stack) {
2144                         delta_stack_alloc = alloc_nr(delta_stack_nr);
2145                         delta_stack = xmalloc(sizeof(*delta_stack)*delta_stack_alloc);
2146                         memcpy(delta_stack, small_delta_stack,
2147                                sizeof(*delta_stack)*delta_stack_nr);
2148                 } else {
2149                         ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
2150                 }
2151                 i = delta_stack_nr++;
2152                 delta_stack[i].obj_offset = obj_offset;
2153                 delta_stack[i].curpos = curpos;
2154                 delta_stack[i].size = size;
2155
2156                 curpos = obj_offset = base_offset;
2157         }
2158
2159         /* PHASE 2: handle the base */
2160         switch (type) {
2161         case OBJ_OFS_DELTA:
2162         case OBJ_REF_DELTA:
2163                 if (data)
2164                         die("BUG in unpack_entry: left loop at a valid delta");
2165                 break;
2166         case OBJ_COMMIT:
2167         case OBJ_TREE:
2168         case OBJ_BLOB:
2169         case OBJ_TAG:
2170                 if (!base_from_cache)
2171                         data = unpack_compressed_entry(p, &w_curs, curpos, size);
2172                 break;
2173         default:
2174                 data = NULL;
2175                 error("unknown object type %i at offset %"PRIuMAX" in %s",
2176                       type, (uintmax_t)obj_offset, p->pack_name);
2177         }
2178
2179         /* PHASE 3: apply deltas in order */
2180
2181         /* invariants:
2182          *   'data' holds the base data, or NULL if there was corruption
2183          */
2184         while (delta_stack_nr) {
2185                 void *delta_data;
2186                 void *base = data;
2187                 unsigned long delta_size, base_size = size;
2188                 int i;
2189
2190                 data = NULL;
2191
2192                 if (base)
2193                         add_delta_base_cache(p, obj_offset, base, base_size, type);
2194
2195                 if (!base) {
2196                         /*
2197                          * We're probably in deep shit, but let's try to fetch
2198                          * the required base anyway from another pack or loose.
2199                          * This is costly but should happen only in the presence
2200                          * of a corrupted pack, and is better than failing outright.
2201                          */
2202                         struct revindex_entry *revidx;
2203                         const unsigned char *base_sha1;
2204                         revidx = find_pack_revindex(p, obj_offset);
2205                         if (revidx) {
2206                                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
2207                                 error("failed to read delta base object %s"
2208                                       " at offset %"PRIuMAX" from %s",
2209                                       sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
2210                                       p->pack_name);
2211                                 mark_bad_packed_object(p, base_sha1);
2212                                 base = read_object(base_sha1, &type, &base_size);
2213                         }
2214                 }
2215
2216                 i = --delta_stack_nr;
2217                 obj_offset = delta_stack[i].obj_offset;
2218                 curpos = delta_stack[i].curpos;
2219                 delta_size = delta_stack[i].size;
2220
2221                 if (!base)
2222                         continue;
2223
2224                 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
2225
2226                 if (!delta_data) {
2227                         error("failed to unpack compressed delta "
2228                               "at offset %"PRIuMAX" from %s",
2229                               (uintmax_t)curpos, p->pack_name);
2230                         data = NULL;
2231                         continue;
2232                 }
2233
2234                 data = patch_delta(base, base_size,
2235                                    delta_data, delta_size,
2236                                    &size);
2237
2238                 /*
2239                  * We could not apply the delta; warn the user, but keep going.
2240                  * Our failure will be noticed either in the next iteration of
2241                  * the loop, or if this is the final delta, in the caller when
2242                  * we return NULL. Those code paths will take care of making
2243                  * a more explicit warning and retrying with another copy of
2244                  * the object.
2245                  */
2246                 if (!data)
2247                         error("failed to apply delta");
2248
2249                 free(delta_data);
2250         }
2251
2252         *final_type = type;
2253         *final_size = size;
2254
2255         unuse_pack(&w_curs);
2256         return data;
2257 }
2258
2259 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
2260                                             uint32_t n)
2261 {
2262         const unsigned char *index = p->index_data;
2263         if (!index) {
2264                 if (open_pack_index(p))
2265                         return NULL;
2266                 index = p->index_data;
2267         }
2268         if (n >= p->num_objects)
2269                 return NULL;
2270         index += 4 * 256;
2271         if (p->index_version == 1) {
2272                 return index + 24 * n + 4;
2273         } else {
2274                 index += 8;
2275                 return index + 20 * n;
2276         }
2277 }
2278
2279 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
2280 {
2281         const unsigned char *index = p->index_data;
2282         index += 4 * 256;
2283         if (p->index_version == 1) {
2284                 return ntohl(*((uint32_t *)(index + 24 * n)));
2285         } else {
2286                 uint32_t off;
2287                 index += 8 + p->num_objects * (20 + 4);
2288                 off = ntohl(*((uint32_t *)(index + 4 * n)));
2289                 if (!(off & 0x80000000))
2290                         return off;
2291                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
2292                 return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
2293                                    ntohl(*((uint32_t *)(index + 4)));
2294         }
2295 }
2296
2297 off_t find_pack_entry_one(const unsigned char *sha1,
2298                                   struct packed_git *p)
2299 {
2300         const uint32_t *level1_ofs = p->index_data;
2301         const unsigned char *index = p->index_data;
2302         unsigned hi, lo, stride;
2303         static int use_lookup = -1;
2304         static int debug_lookup = -1;
2305
2306         if (debug_lookup < 0)
2307                 debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
2308
2309         if (!index) {
2310                 if (open_pack_index(p))
2311                         return 0;
2312                 level1_ofs = p->index_data;
2313                 index = p->index_data;
2314         }
2315         if (p->index_version > 1) {
2316                 level1_ofs += 2;
2317                 index += 8;
2318         }
2319         index += 4 * 256;
2320         hi = ntohl(level1_ofs[*sha1]);
2321         lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
2322         if (p->index_version > 1) {
2323                 stride = 20;
2324         } else {
2325                 stride = 24;
2326                 index += 4;
2327         }
2328
2329         if (debug_lookup)
2330                 printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
2331                        sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
2332
2333         if (use_lookup < 0)
2334                 use_lookup = !!getenv("GIT_USE_LOOKUP");
2335         if (use_lookup) {
2336                 int pos = sha1_entry_pos(index, stride, 0,
2337                                          lo, hi, p->num_objects, sha1);
2338                 if (pos < 0)
2339                         return 0;
2340                 return nth_packed_object_offset(p, pos);
2341         }
2342
2343         do {
2344                 unsigned mi = (lo + hi) / 2;
2345                 int cmp = hashcmp(index + mi * stride, sha1);
2346
2347                 if (debug_lookup)
2348                         printf("lo %u hi %u rg %u mi %u\n",
2349                                lo, hi, hi - lo, mi);
2350                 if (!cmp)
2351                         return nth_packed_object_offset(p, mi);
2352                 if (cmp > 0)
2353                         hi = mi;
2354                 else
2355                         lo = mi+1;
2356         } while (lo < hi);
2357         return 0;
2358 }
2359
2360 int is_pack_valid(struct packed_git *p)
2361 {
2362         /* An already open pack is known to be valid. */
2363         if (p->pack_fd != -1)
2364                 return 1;
2365
2366         /* If the pack has one window completely covering the
2367          * file size, the pack is known to be valid even if
2368          * the descriptor is not currently open.
2369          */
2370         if (p->windows) {
2371                 struct pack_window *w = p->windows;
2372
2373                 if (!w->offset && w->len == p->pack_size)
2374                         return 1;
2375         }
2376
2377         /* Force the pack to open to prove its valid. */
2378         return !open_packed_git(p);
2379 }
2380
2381 static int fill_pack_entry(const unsigned char *sha1,
2382                            struct pack_entry *e,
2383                            struct packed_git *p)
2384 {
2385         off_t offset;
2386
2387         if (p->num_bad_objects) {
2388                 unsigned i;
2389                 for (i = 0; i < p->num_bad_objects; i++)
2390                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2391                                 return 0;
2392         }
2393
2394         offset = find_pack_entry_one(sha1, p);
2395         if (!offset)
2396                 return 0;
2397
2398         /*
2399          * We are about to tell the caller where they can locate the
2400          * requested object.  We better make sure the packfile is
2401          * still here and can be accessed before supplying that
2402          * answer, as it may have been deleted since the index was
2403          * loaded!
2404          */
2405         if (!is_pack_valid(p)) {
2406                 warning("packfile %s cannot be accessed", p->pack_name);
2407                 return 0;
2408         }
2409         e->offset = offset;
2410         e->p = p;
2411         hashcpy(e->sha1, sha1);
2412         return 1;
2413 }
2414
2415 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2416 {
2417         struct packed_git *p;
2418
2419         prepare_packed_git();
2420         if (!packed_git)
2421                 return 0;
2422
2423         if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
2424                 return 1;
2425
2426         for (p = packed_git; p; p = p->next) {
2427                 if (p == last_found_pack || !fill_pack_entry(sha1, e, p))
2428                         continue;
2429
2430                 last_found_pack = p;
2431                 return 1;
2432         }
2433         return 0;
2434 }
2435
2436 struct packed_git *find_sha1_pack(const unsigned char *sha1,
2437                                   struct packed_git *packs)
2438 {
2439         struct packed_git *p;
2440
2441         for (p = packs; p; p = p->next) {
2442                 if (find_pack_entry_one(sha1, p))
2443                         return p;
2444         }
2445         return NULL;
2446
2447 }
2448
2449 static int sha1_loose_object_info(const unsigned char *sha1,
2450                                   struct object_info *oi)
2451 {
2452         int status;
2453         unsigned long mapsize, size;
2454         void *map;
2455         git_zstream stream;
2456         char hdr[32];
2457
2458         if (oi->delta_base_sha1)
2459                 hashclr(oi->delta_base_sha1);
2460
2461         /*
2462          * If we don't care about type or size, then we don't
2463          * need to look inside the object at all. Note that we
2464          * do not optimize out the stat call, even if the
2465          * caller doesn't care about the disk-size, since our
2466          * return value implicitly indicates whether the
2467          * object even exists.
2468          */
2469         if (!oi->typep && !oi->sizep) {
2470                 struct stat st;
2471                 if (stat_sha1_file(sha1, &st) < 0)
2472                         return -1;
2473                 if (oi->disk_sizep)
2474                         *oi->disk_sizep = st.st_size;
2475                 return 0;
2476         }
2477
2478         map = map_sha1_file(sha1, &mapsize);
2479         if (!map)
2480                 return -1;
2481         if (oi->disk_sizep)
2482                 *oi->disk_sizep = mapsize;
2483         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2484                 status = error("unable to unpack %s header",
2485                                sha1_to_hex(sha1));
2486         else if ((status = parse_sha1_header(hdr, &size)) < 0)
2487                 status = error("unable to parse %s header", sha1_to_hex(sha1));
2488         else if (oi->sizep)
2489                 *oi->sizep = size;
2490         git_inflate_end(&stream);
2491         munmap(map, mapsize);
2492         if (oi->typep)
2493                 *oi->typep = status;
2494         return 0;
2495 }
2496
2497 int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
2498 {
2499         struct cached_object *co;
2500         struct pack_entry e;
2501         int rtype;
2502
2503         co = find_cached_object(sha1);
2504         if (co) {
2505                 if (oi->typep)
2506                         *(oi->typep) = co->type;
2507                 if (oi->sizep)
2508                         *(oi->sizep) = co->size;
2509                 if (oi->disk_sizep)
2510                         *(oi->disk_sizep) = 0;
2511                 if (oi->delta_base_sha1)
2512                         hashclr(oi->delta_base_sha1);
2513                 oi->whence = OI_CACHED;
2514                 return 0;
2515         }
2516
2517         if (!find_pack_entry(sha1, &e)) {
2518                 /* Most likely it's a loose object. */
2519                 if (!sha1_loose_object_info(sha1, oi)) {
2520                         oi->whence = OI_LOOSE;
2521                         return 0;
2522                 }
2523
2524                 /* Not a loose object; someone else may have just packed it. */
2525                 reprepare_packed_git();
2526                 if (!find_pack_entry(sha1, &e))
2527                         return -1;
2528         }
2529
2530         rtype = packed_object_info(e.p, e.offset, oi);
2531         if (rtype < 0) {
2532                 mark_bad_packed_object(e.p, sha1);
2533                 return sha1_object_info_extended(sha1, oi);
2534         } else if (in_delta_base_cache(e.p, e.offset)) {
2535                 oi->whence = OI_DBCACHED;
2536         } else {
2537                 oi->whence = OI_PACKED;
2538                 oi->u.packed.offset = e.offset;
2539                 oi->u.packed.pack = e.p;
2540                 oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
2541                                          rtype == OBJ_OFS_DELTA);
2542         }
2543
2544         return 0;
2545 }
2546
2547 /* returns enum object_type or negative */
2548 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2549 {
2550         enum object_type type;
2551         struct object_info oi = {NULL};
2552
2553         oi.typep = &type;
2554         oi.sizep = sizep;
2555         if (sha1_object_info_extended(sha1, &oi) < 0)
2556                 return -1;
2557         return type;
2558 }
2559
2560 static void *read_packed_sha1(const unsigned char *sha1,
2561                               enum object_type *type, unsigned long *size)
2562 {
2563         struct pack_entry e;
2564         void *data;
2565
2566         if (!find_pack_entry(sha1, &e))
2567                 return NULL;
2568         data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2569         if (!data) {
2570                 /*
2571                  * We're probably in deep shit, but let's try to fetch
2572                  * the required object anyway from another pack or loose.
2573                  * This should happen only in the presence of a corrupted
2574                  * pack, and is better than failing outright.
2575                  */
2576                 error("failed to read object %s at offset %"PRIuMAX" from %s",
2577                       sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2578                 mark_bad_packed_object(e.p, sha1);
2579                 data = read_object(sha1, type, size);
2580         }
2581         return data;
2582 }
2583
2584 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2585                       unsigned char *sha1)
2586 {
2587         struct cached_object *co;
2588
2589         hash_sha1_file(buf, len, typename(type), sha1);
2590         if (has_sha1_file(sha1) || find_cached_object(sha1))
2591                 return 0;
2592         if (cached_object_alloc <= cached_object_nr) {
2593                 cached_object_alloc = alloc_nr(cached_object_alloc);
2594                 cached_objects = xrealloc(cached_objects,
2595                                           sizeof(*cached_objects) *
2596                                           cached_object_alloc);
2597         }
2598         co = &cached_objects[cached_object_nr++];
2599         co->size = len;
2600         co->type = type;
2601         co->buf = xmalloc(len);
2602         memcpy(co->buf, buf, len);
2603         hashcpy(co->sha1, sha1);
2604         return 0;
2605 }
2606
2607 static void *read_object(const unsigned char *sha1, enum object_type *type,
2608                          unsigned long *size)
2609 {
2610         unsigned long mapsize;
2611         void *map, *buf;
2612         struct cached_object *co;
2613
2614         co = find_cached_object(sha1);
2615         if (co) {
2616                 *type = co->type;
2617                 *size = co->size;
2618                 return xmemdupz(co->buf, co->size);
2619         }
2620
2621         buf = read_packed_sha1(sha1, type, size);
2622         if (buf)
2623                 return buf;
2624         map = map_sha1_file(sha1, &mapsize);
2625         if (map) {
2626                 buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2627                 munmap(map, mapsize);
2628                 return buf;
2629         }
2630         reprepare_packed_git();
2631         return read_packed_sha1(sha1, type, size);
2632 }
2633
2634 /*
2635  * This function dies on corrupt objects; the callers who want to
2636  * deal with them should arrange to call read_object() and give error
2637  * messages themselves.
2638  */
2639 void *read_sha1_file_extended(const unsigned char *sha1,
2640                               enum object_type *type,
2641                               unsigned long *size,
2642                               unsigned flag)
2643 {
2644         void *data;
2645         char *path;
2646         const struct packed_git *p;
2647         const unsigned char *repl = (flag & READ_SHA1_FILE_REPLACE)
2648                 ? lookup_replace_object(sha1) : sha1;
2649
2650         errno = 0;
2651         data = read_object(repl, type, size);
2652         if (data)
2653                 return data;
2654
2655         if (errno && errno != ENOENT)
2656                 die_errno("failed to read object %s", sha1_to_hex(sha1));
2657
2658         /* die if we replaced an object with one that does not exist */
2659         if (repl != sha1)
2660                 die("replacement %s not found for %s",
2661                     sha1_to_hex(repl), sha1_to_hex(sha1));
2662
2663         if (has_loose_object(repl)) {
2664                 path = sha1_file_name(sha1);
2665                 die("loose object %s (stored in %s) is corrupt",
2666                     sha1_to_hex(repl), path);
2667         }
2668
2669         if ((p = has_packed_and_bad(repl)) != NULL)
2670                 die("packed object %s (stored in %s) is corrupt",
2671                     sha1_to_hex(repl), p->pack_name);
2672
2673         return NULL;
2674 }
2675
2676 void *read_object_with_reference(const unsigned char *sha1,
2677                                  const char *required_type_name,
2678                                  unsigned long *size,
2679                                  unsigned char *actual_sha1_return)
2680 {
2681         enum object_type type, required_type;
2682         void *buffer;
2683         unsigned long isize;
2684         unsigned char actual_sha1[20];
2685
2686         required_type = type_from_string(required_type_name);
2687         hashcpy(actual_sha1, sha1);
2688         while (1) {
2689                 int ref_length = -1;
2690                 const char *ref_type = NULL;
2691
2692                 buffer = read_sha1_file(actual_sha1, &type, &isize);
2693                 if (!buffer)
2694                         return NULL;
2695                 if (type == required_type) {
2696                         *size = isize;
2697                         if (actual_sha1_return)
2698                                 hashcpy(actual_sha1_return, actual_sha1);
2699                         return buffer;
2700                 }
2701                 /* Handle references */
2702                 else if (type == OBJ_COMMIT)
2703                         ref_type = "tree ";
2704                 else if (type == OBJ_TAG)
2705                         ref_type = "object ";
2706                 else {
2707                         free(buffer);
2708                         return NULL;
2709                 }
2710                 ref_length = strlen(ref_type);
2711
2712                 if (ref_length + 40 > isize ||
2713                     memcmp(buffer, ref_type, ref_length) ||
2714                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2715                         free(buffer);
2716                         return NULL;
2717                 }
2718                 free(buffer);
2719                 /* Now we have the ID of the referred-to object in
2720                  * actual_sha1.  Check again. */
2721         }
2722 }
2723
2724 static void write_sha1_file_prepare(const void *buf, unsigned long len,
2725                                     const char *type, unsigned char *sha1,
2726                                     char *hdr, int *hdrlen)
2727 {
2728         git_SHA_CTX c;
2729
2730         /* Generate the header */
2731         *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2732
2733         /* Sha1.. */
2734         git_SHA1_Init(&c);
2735         git_SHA1_Update(&c, hdr, *hdrlen);
2736         git_SHA1_Update(&c, buf, len);
2737         git_SHA1_Final(sha1, &c);
2738 }
2739
2740 /*
2741  * Move the just written object into its final resting place.
2742  * NEEDSWORK: this should be renamed to finalize_temp_file() as
2743  * "moving" is only a part of what it does, when no patch between
2744  * master to pu changes the call sites of this function.
2745  */
2746 int move_temp_to_file(const char *tmpfile, const char *filename)
2747 {
2748         int ret = 0;
2749
2750         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2751                 goto try_rename;
2752         else if (link(tmpfile, filename))
2753                 ret = errno;
2754
2755         /*
2756          * Coda hack - coda doesn't like cross-directory links,
2757          * so we fall back to a rename, which will mean that it
2758          * won't be able to check collisions, but that's not a
2759          * big deal.
2760          *
2761          * The same holds for FAT formatted media.
2762          *
2763          * When this succeeds, we just return.  We have nothing
2764          * left to unlink.
2765          */
2766         if (ret && ret != EEXIST) {
2767         try_rename:
2768                 if (!rename(tmpfile, filename))
2769                         goto out;
2770                 ret = errno;
2771         }
2772         unlink_or_warn(tmpfile);
2773         if (ret) {
2774                 if (ret != EEXIST) {
2775                         return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
2776                 }
2777                 /* FIXME!!! Collision check here ? */
2778         }
2779
2780 out:
2781         if (adjust_shared_perm(filename))
2782                 return error("unable to set permission to '%s'", filename);
2783         return 0;
2784 }
2785
2786 static int write_buffer(int fd, const void *buf, size_t len)
2787 {
2788         if (write_in_full(fd, buf, len) < 0)
2789                 return error("file write error (%s)", strerror(errno));
2790         return 0;
2791 }
2792
2793 int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2794                    unsigned char *sha1)
2795 {
2796         char hdr[32];
2797         int hdrlen;
2798         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2799         return 0;
2800 }
2801
2802 /* Finalize a file on disk, and close it. */
2803 static void close_sha1_file(int fd)
2804 {
2805         if (fsync_object_files)
2806                 fsync_or_die(fd, "sha1 file");
2807         if (close(fd) != 0)
2808                 die_errno("error when closing sha1 file");
2809 }
2810
2811 /* Size of directory component, including the ending '/' */
2812 static inline int directory_size(const char *filename)
2813 {
2814         const char *s = strrchr(filename, '/');
2815         if (!s)
2816                 return 0;
2817         return s - filename + 1;
2818 }
2819
2820 /*
2821  * This creates a temporary file in the same directory as the final
2822  * 'filename'
2823  *
2824  * We want to avoid cross-directory filename renames, because those
2825  * can have problems on various filesystems (FAT, NFS, Coda).
2826  */
2827 static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2828 {
2829         int fd, dirlen = directory_size(filename);
2830
2831         if (dirlen + 20 > bufsiz) {
2832                 errno = ENAMETOOLONG;
2833                 return -1;
2834         }
2835         memcpy(buffer, filename, dirlen);
2836         strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2837         fd = git_mkstemp_mode(buffer, 0444);
2838         if (fd < 0 && dirlen && errno == ENOENT) {
2839                 /* Make sure the directory exists */
2840                 memcpy(buffer, filename, dirlen);
2841                 buffer[dirlen-1] = 0;
2842                 if (mkdir(buffer, 0777) && errno != EEXIST)
2843                         return -1;
2844                 if (adjust_shared_perm(buffer))
2845                         return -1;
2846
2847                 /* Try again */
2848                 strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2849                 fd = git_mkstemp_mode(buffer, 0444);
2850         }
2851         return fd;
2852 }
2853
2854 static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2855                               const void *buf, unsigned long len, time_t mtime)
2856 {
2857         int fd, ret;
2858         unsigned char compressed[4096];
2859         git_zstream stream;
2860         git_SHA_CTX c;
2861         unsigned char parano_sha1[20];
2862         char *filename;
2863         static char tmp_file[PATH_MAX];
2864
2865         filename = sha1_file_name(sha1);
2866         fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
2867         if (fd < 0) {
2868                 if (errno == EACCES)
2869                         return error("insufficient permission for adding an object to repository database %s", get_object_directory());
2870                 else
2871                         return error("unable to create temporary file: %s", strerror(errno));
2872         }
2873
2874         /* Set it up */
2875         memset(&stream, 0, sizeof(stream));
2876         git_deflate_init(&stream, zlib_compression_level);
2877         stream.next_out = compressed;
2878         stream.avail_out = sizeof(compressed);
2879         git_SHA1_Init(&c);
2880
2881         /* First header.. */
2882         stream.next_in = (unsigned char *)hdr;
2883         stream.avail_in = hdrlen;
2884         while (git_deflate(&stream, 0) == Z_OK)
2885                 ; /* nothing */
2886         git_SHA1_Update(&c, hdr, hdrlen);
2887
2888         /* Then the data itself.. */
2889         stream.next_in = (void *)buf;
2890         stream.avail_in = len;
2891         do {
2892                 unsigned char *in0 = stream.next_in;
2893                 ret = git_deflate(&stream, Z_FINISH);
2894                 git_SHA1_Update(&c, in0, stream.next_in - in0);
2895                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2896                         die("unable to write sha1 file");
2897                 stream.next_out = compressed;
2898                 stream.avail_out = sizeof(compressed);
2899         } while (ret == Z_OK);
2900
2901         if (ret != Z_STREAM_END)
2902                 die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2903         ret = git_deflate_end_gently(&stream);
2904         if (ret != Z_OK)
2905                 die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2906         git_SHA1_Final(parano_sha1, &c);
2907         if (hashcmp(sha1, parano_sha1) != 0)
2908                 die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2909
2910         close_sha1_file(fd);
2911
2912         if (mtime) {
2913                 struct utimbuf utb;
2914                 utb.actime = mtime;
2915                 utb.modtime = mtime;
2916                 if (utime(tmp_file, &utb) < 0)
2917                         warning("failed utime() on %s: %s",
2918                                 tmp_file, strerror(errno));
2919         }
2920
2921         return move_temp_to_file(tmp_file, filename);
2922 }
2923
2924 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2925 {
2926         unsigned char sha1[20];
2927         char hdr[32];
2928         int hdrlen;
2929
2930         /* Normally if we have it in the pack then we do not bother writing
2931          * it out into .git/objects/??/?{38} file.
2932          */
2933         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2934         if (returnsha1)
2935                 hashcpy(returnsha1, sha1);
2936         if (has_sha1_file(sha1))
2937                 return 0;
2938         return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2939 }
2940
2941 int force_object_loose(const unsigned char *sha1, time_t mtime)
2942 {
2943         void *buf;
2944         unsigned long len;
2945         enum object_type type;
2946         char hdr[32];
2947         int hdrlen;
2948         int ret;
2949
2950         if (has_loose_object(sha1))
2951                 return 0;
2952         buf = read_packed_sha1(sha1, &type, &len);
2953         if (!buf)
2954                 return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2955         hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2956         ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2957         free(buf);
2958
2959         return ret;
2960 }
2961
2962 int has_pack_index(const unsigned char *sha1)
2963 {
2964         struct stat st;
2965         if (stat(sha1_pack_index_name(sha1), &st))
2966                 return 0;
2967         return 1;
2968 }
2969
2970 int has_sha1_pack(const unsigned char *sha1)
2971 {
2972         struct pack_entry e;
2973         return find_pack_entry(sha1, &e);
2974 }
2975
2976 int has_sha1_file(const unsigned char *sha1)
2977 {
2978         struct pack_entry e;
2979
2980         if (find_pack_entry(sha1, &e))
2981                 return 1;
2982         if (has_loose_object(sha1))
2983                 return 1;
2984         reprepare_packed_git();
2985         return find_pack_entry(sha1, &e);
2986 }
2987
2988 static void check_tree(const void *buf, size_t size)
2989 {
2990         struct tree_desc desc;
2991         struct name_entry entry;
2992
2993         init_tree_desc(&desc, buf, size);
2994         while (tree_entry(&desc, &entry))
2995                 /* do nothing
2996                  * tree_entry() will die() on malformed entries */
2997                 ;
2998 }
2999
3000 static void check_commit(const void *buf, size_t size)
3001 {
3002         struct commit c;
3003         memset(&c, 0, sizeof(c));
3004         if (parse_commit_buffer(&c, buf, size))
3005                 die("corrupt commit");
3006 }
3007
3008 static void check_tag(const void *buf, size_t size)
3009 {
3010         struct tag t;
3011         memset(&t, 0, sizeof(t));
3012         if (parse_tag_buffer(&t, buf, size))
3013                 die("corrupt tag");
3014 }
3015
3016 static int index_mem(unsigned char *sha1, void *buf, size_t size,
3017                      enum object_type type,
3018                      const char *path, unsigned flags)
3019 {
3020         int ret, re_allocated = 0;
3021         int write_object = flags & HASH_WRITE_OBJECT;
3022
3023         if (!type)
3024                 type = OBJ_BLOB;
3025
3026         /*
3027          * Convert blobs to git internal format
3028          */
3029         if ((type == OBJ_BLOB) && path) {
3030                 struct strbuf nbuf = STRBUF_INIT;
3031                 if (convert_to_git(path, buf, size, &nbuf,
3032                                    write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
3033                         buf = strbuf_detach(&nbuf, &size);
3034                         re_allocated = 1;
3035                 }
3036         }
3037         if (flags & HASH_FORMAT_CHECK) {
3038                 if (type == OBJ_TREE)
3039                         check_tree(buf, size);
3040                 if (type == OBJ_COMMIT)
3041                         check_commit(buf, size);
3042                 if (type == OBJ_TAG)
3043                         check_tag(buf, size);
3044         }
3045
3046         if (write_object)
3047                 ret = write_sha1_file(buf, size, typename(type), sha1);
3048         else
3049                 ret = hash_sha1_file(buf, size, typename(type), sha1);
3050         if (re_allocated)
3051                 free(buf);
3052         return ret;
3053 }
3054
3055 static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
3056                       const char *path, unsigned flags)
3057 {
3058         struct strbuf sbuf = STRBUF_INIT;
3059         int ret;
3060
3061         if (strbuf_read(&sbuf, fd, 4096) >= 0)
3062                 ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
3063         else
3064                 ret = -1;
3065         strbuf_release(&sbuf);
3066         return ret;
3067 }
3068
3069 #define SMALL_FILE_SIZE (32*1024)
3070
3071 static int index_core(unsigned char *sha1, int fd, size_t size,
3072                       enum object_type type, const char *path,
3073                       unsigned flags)
3074 {
3075         int ret;
3076
3077         if (!size) {
3078                 ret = index_mem(sha1, NULL, size, type, path, flags);
3079         } else if (size <= SMALL_FILE_SIZE) {
3080                 char *buf = xmalloc(size);
3081                 if (size == read_in_full(fd, buf, size))
3082                         ret = index_mem(sha1, buf, size, type, path, flags);
3083                 else
3084                         ret = error("short read %s", strerror(errno));
3085                 free(buf);
3086         } else {
3087                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
3088                 ret = index_mem(sha1, buf, size, type, path, flags);
3089                 munmap(buf, size);
3090         }
3091         return ret;
3092 }
3093
3094 /*
3095  * This creates one packfile per large blob unless bulk-checkin
3096  * machinery is "plugged".
3097  *
3098  * This also bypasses the usual "convert-to-git" dance, and that is on
3099  * purpose. We could write a streaming version of the converting
3100  * functions and insert that before feeding the data to fast-import
3101  * (or equivalent in-core API described above). However, that is
3102  * somewhat complicated, as we do not know the size of the filter
3103  * result, which we need to know beforehand when writing a git object.
3104  * Since the primary motivation for trying to stream from the working
3105  * tree file and to avoid mmaping it in core is to deal with large
3106  * binary blobs, they generally do not want to get any conversion, and
3107  * callers should avoid this code path when filters are requested.
3108  */
3109 static int index_stream(unsigned char *sha1, int fd, size_t size,
3110                         enum object_type type, const char *path,
3111                         unsigned flags)
3112 {
3113         return index_bulk_checkin(sha1, fd, size, type, path, flags);
3114 }
3115
3116 int index_fd(unsigned char *sha1, int fd, struct stat *st,
3117              enum object_type type, const char *path, unsigned flags)
3118 {
3119         int ret;
3120         size_t size = xsize_t(st->st_size);
3121
3122         if (!S_ISREG(st->st_mode))
3123                 ret = index_pipe(sha1, fd, type, path, flags);
3124         else if (size <= big_file_threshold || type != OBJ_BLOB ||
3125                  (path && would_convert_to_git(path, NULL, 0, 0)))
3126                 ret = index_core(sha1, fd, size, type, path, flags);
3127         else
3128                 ret = index_stream(sha1, fd, size, type, path, flags);
3129         close(fd);
3130         return ret;
3131 }
3132
3133 int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
3134 {
3135         int fd;
3136         struct strbuf sb = STRBUF_INIT;
3137
3138         switch (st->st_mode & S_IFMT) {
3139         case S_IFREG:
3140                 fd = open(path, O_RDONLY);
3141                 if (fd < 0)
3142                         return error("open(\"%s\"): %s", path,
3143                                      strerror(errno));
3144                 if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
3145                         return error("%s: failed to insert into database",
3146                                      path);
3147                 break;
3148         case S_IFLNK:
3149                 if (strbuf_readlink(&sb, path, st->st_size)) {
3150                         char *errstr = strerror(errno);
3151                         return error("readlink(\"%s\"): %s", path,
3152                                      errstr);
3153                 }
3154                 if (!(flags & HASH_WRITE_OBJECT))
3155                         hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
3156                 else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
3157                         return error("%s: failed to insert into database",
3158                                      path);
3159                 strbuf_release(&sb);
3160                 break;
3161         case S_IFDIR:
3162                 return resolve_gitlink_ref(path, "HEAD", sha1);
3163         default:
3164                 return error("%s: unsupported file type", path);
3165         }
3166         return 0;
3167 }
3168
3169 int read_pack_header(int fd, struct pack_header *header)
3170 {
3171         if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
3172                 /* "eof before pack header was fully read" */
3173                 return PH_ERROR_EOF;
3174
3175         if (header->hdr_signature != htonl(PACK_SIGNATURE))
3176                 /* "protocol error (pack signature mismatch detected)" */
3177                 return PH_ERROR_PACK_SIGNATURE;
3178         if (!pack_version_ok(header->hdr_version))
3179                 /* "protocol error (pack version unsupported)" */
3180                 return PH_ERROR_PROTOCOL;
3181         return 0;
3182 }
3183
3184 void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
3185 {
3186         enum object_type type = sha1_object_info(sha1, NULL);
3187         if (type < 0)
3188                 die("%s is not a valid object", sha1_to_hex(sha1));
3189         if (type != expect)
3190                 die("%s is not a valid '%s' object", sha1_to_hex(sha1),
3191                     typename(expect));
3192 }