sha1_file.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include "cache.h"
  10 #include "delta.h"
  11 #include "pack.h"
  12 #include "blob.h"
  13 #include "commit.h"
  14 #include "tag.h"
  15 #include "tree.h"
  16
  17 #ifndef O_NOATIME
  18 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  19 #define O_NOATIME 01000000
  20 #else
  21 #define O_NOATIME 0
  22 #endif
  23 #endif
  24
  25 #ifdef NO_C99_FORMAT
  26 #define SZ_FMT "lu"
  27 #else
  28 #define SZ_FMT "zu"
  29 #endif
  30
  31 const unsigned char null_sha1[20];
  32
  33 static unsigned int sha1_file_open_flag = O_NOATIME;
  34
  35 signed char hexval_table[256] = {
  36          -1, -1, -1, -1, -1, -1, -1, -1,                /* 00-07 */
  37          -1, -1, -1, -1, -1, -1, -1, -1,                /* 08-0f */
  38          -1, -1, -1, -1, -1, -1, -1, -1,                /* 10-17 */
  39          -1, -1, -1, -1, -1, -1, -1, -1,                /* 18-1f */
  40          -1, -1, -1, -1, -1, -1, -1, -1,                /* 20-27 */
  41          -1, -1, -1, -1, -1, -1, -1, -1,                /* 28-2f */
  42           0,  1,  2,  3,  4,  5,  6,  7,                /* 30-37 */
  43           8,  9, -1, -1, -1, -1, -1, -1,                /* 38-3f */
  44          -1, 10, 11, 12, 13, 14, 15, -1,                /* 40-47 */
  45          -1, -1, -1, -1, -1, -1, -1, -1,                /* 48-4f */
  46          -1, -1, -1, -1, -1, -1, -1, -1,                /* 50-57 */
  47          -1, -1, -1, -1, -1, -1, -1, -1,                /* 58-5f */
  48          -1, 10, 11, 12, 13, 14, 15, -1,                /* 60-67 */
  49          -1, -1, -1, -1, -1, -1, -1, -1,                /* 68-67 */
  50          -1, -1, -1, -1, -1, -1, -1, -1,                /* 70-77 */
  51          -1, -1, -1, -1, -1, -1, -1, -1,                /* 78-7f */
  52          -1, -1, -1, -1, -1, -1, -1, -1,                /* 80-87 */
  53          -1, -1, -1, -1, -1, -1, -1, -1,                /* 88-8f */
  54          -1, -1, -1, -1, -1, -1, -1, -1,                /* 90-97 */
  55          -1, -1, -1, -1, -1, -1, -1, -1,                /* 98-9f */
  56          -1, -1, -1, -1, -1, -1, -1, -1,                /* a0-a7 */
  57          -1, -1, -1, -1, -1, -1, -1, -1,                /* a8-af */
  58          -1, -1, -1, -1, -1, -1, -1, -1,                /* b0-b7 */
  59          -1, -1, -1, -1, -1, -1, -1, -1,                /* b8-bf */
  60          -1, -1, -1, -1, -1, -1, -1, -1,                /* c0-c7 */
  61          -1, -1, -1, -1, -1, -1, -1, -1,                /* c8-cf */
  62          -1, -1, -1, -1, -1, -1, -1, -1,                /* d0-d7 */
  63          -1, -1, -1, -1, -1, -1, -1, -1,                /* d8-df */
  64          -1, -1, -1, -1, -1, -1, -1, -1,                /* e0-e7 */
  65          -1, -1, -1, -1, -1, -1, -1, -1,                /* e8-ef */
  66          -1, -1, -1, -1, -1, -1, -1, -1,                /* f0-f7 */
  67          -1, -1, -1, -1, -1, -1, -1, -1,                /* f8-ff */
  68 };
  69
  70 int get_sha1_hex(const char *hex, unsigned char *sha1)
  71 {
  72         int i;
  73         for (i = 0; i < 20; i++) {
  74                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  75                 if (val & ~0xff)
  76                         return -1;
  77                 *sha1++ = val;
  78                 hex += 2;
  79         }
  80         return 0;
  81 }
  82
  83 int safe_create_leading_directories(char *path)
  84 {
  85         char *pos = path;
  86         struct stat st;
  87
  88         if (*pos == '/')
  89                 pos++;
  90
  91         while (pos) {
  92                 pos = strchr(pos, '/');
  93                 if (!pos)
  94                         break;
  95                 *pos = 0;
  96                 if (!stat(path, &st)) {
  97                         /* path exists */
  98                         if (!S_ISDIR(st.st_mode)) {
  99                                 *pos = '/';
 100                                 return -3;
 101                         }
 102                 }
 103                 else if (mkdir(path, 0777)) {
 104                         *pos = '/';
 105                         return -1;
 106                 }
 107                 else if (adjust_shared_perm(path)) {
 108                         *pos = '/';
 109                         return -2;
 110                 }
 111                 *pos++ = '/';
 112         }
 113         return 0;
 114 }
 115
 116 char * sha1_to_hex(const unsigned char *sha1)
 117 {
 118         static int bufno;
 119         static char hexbuffer[4][50];
 120         static const char hex[] = "0123456789abcdef";
 121         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
 122         int i;
 123
 124         for (i = 0; i < 20; i++) {
 125                 unsigned int val = *sha1++;
 126                 *buf++ = hex[val >> 4];
 127                 *buf++ = hex[val & 0xf];
 128         }
 129         *buf = '\0';
 130
 131         return buffer;
 132 }
 133
 134 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 135 {
 136         int i;
 137         for (i = 0; i < 20; i++) {
 138                 static char hex[] = "0123456789abcdef";
 139                 unsigned int val = sha1[i];
 140                 char *pos = pathbuf + i*2 + (i > 0);
 141                 *pos++ = hex[val >> 4];
 142                 *pos = hex[val & 0xf];
 143         }
 144 }
 145
 146 /*
 147  * NOTE! This returns a statically allocated buffer, so you have to be
 148  * careful about using it. Do a "xstrdup()" if you need to save the
 149  * filename.
 150  *
 151  * Also note that this returns the location for creating.  Reading
 152  * SHA1 file can happen from any alternate directory listed in the
 153  * DB_ENVIRONMENT environment variable if it is not found in
 154  * the primary object database.
 155  */
 156 char *sha1_file_name(const unsigned char *sha1)
 157 {
 158         static char *name, *base;
 159
 160         if (!base) {
 161                 const char *sha1_file_directory = get_object_directory();
 162                 int len = strlen(sha1_file_directory);
 163                 base = xmalloc(len + 60);
 164                 memcpy(base, sha1_file_directory, len);
 165                 memset(base+len, 0, 60);
 166                 base[len] = '/';
 167                 base[len+3] = '/';
 168                 name = base + len + 1;
 169         }
 170         fill_sha1_path(name, sha1);
 171         return base;
 172 }
 173
 174 char *sha1_pack_name(const unsigned char *sha1)
 175 {
 176         static const char hex[] = "0123456789abcdef";
 177         static char *name, *base, *buf;
 178         int i;
 179
 180         if (!base) {
 181                 const char *sha1_file_directory = get_object_directory();
 182                 int len = strlen(sha1_file_directory);
 183                 base = xmalloc(len + 60);
 184                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 185                 name = base + len + 11;
 186         }
 187
 188         buf = name;
 189
 190         for (i = 0; i < 20; i++) {
 191                 unsigned int val = *sha1++;
 192                 *buf++ = hex[val >> 4];
 193                 *buf++ = hex[val & 0xf];
 194         }
 195
 196         return base;
 197 }
 198
 199 char *sha1_pack_index_name(const unsigned char *sha1)
 200 {
 201         static const char hex[] = "0123456789abcdef";
 202         static char *name, *base, *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.idx", sha1_file_directory);
 210                 name = base + len + 11;
 211         }
 212
 213         buf = name;
 214
 215         for (i = 0; i < 20; i++) {
 216                 unsigned int val = *sha1++;
 217                 *buf++ = hex[val >> 4];
 218                 *buf++ = hex[val & 0xf];
 219         }
 220
 221         return base;
 222 }
 223
 224 struct alternate_object_database *alt_odb_list;
 225 static struct alternate_object_database **alt_odb_tail;
 226
 227 static void read_info_alternates(const char * alternates, int depth);
 228
 229 /*
 230  * Prepare alternate object database registry.
 231  *
 232  * The variable alt_odb_list points at the list of struct
 233  * alternate_object_database.  The elements on this list come from
 234  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 235  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 236  * whose contents is similar to that environment variable but can be
 237  * LF separated.  Its base points at a statically allocated buffer that
 238  * contains "/the/directory/corresponding/to/.git/objects/...", while
 239  * its name points just after the slash at the end of ".git/objects/"
 240  * in the example above, and has enough space to hold 40-byte hex
 241  * SHA1, an extra slash for the first level indirection, and the
 242  * terminating NUL.
 243  */
 244 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 245 {
 246         struct stat st;
 247         const char *objdir = get_object_directory();
 248         struct alternate_object_database *ent;
 249         struct alternate_object_database *alt;
 250         /* 43 = 40-byte + 2 '/' + terminating NUL */
 251         int pfxlen = len;
 252         int entlen = pfxlen + 43;
 253         int base_len = -1;
 254
 255         if (*entry != '/' && relative_base) {
 256                 /* Relative alt-odb */
 257                 if (base_len < 0)
 258                         base_len = strlen(relative_base) + 1;
 259                 entlen += base_len;
 260                 pfxlen += base_len;
 261         }
 262         ent = xmalloc(sizeof(*ent) + entlen);
 263
 264         if (*entry != '/' && relative_base) {
 265                 memcpy(ent->base, relative_base, base_len - 1);
 266                 ent->base[base_len - 1] = '/';
 267                 memcpy(ent->base + base_len, entry, len);
 268         }
 269         else
 270                 memcpy(ent->base, entry, pfxlen);
 271
 272         ent->name = ent->base + pfxlen + 1;
 273         ent->base[pfxlen + 3] = '/';
 274         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 275
 276         /* Detect cases where alternate disappeared */
 277         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 278                 error("object directory %s does not exist; "
 279                       "check .git/objects/info/alternates.",
 280                       ent->base);
 281                 free(ent);
 282                 return -1;
 283         }
 284
 285         /* Prevent the common mistake of listing the same
 286          * thing twice, or object directory itself.
 287          */
 288         for (alt = alt_odb_list; alt; alt = alt->next) {
 289                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 290                         free(ent);
 291                         return -1;
 292                 }
 293         }
 294         if (!memcmp(ent->base, objdir, pfxlen)) {
 295                 free(ent);
 296                 return -1;
 297         }
 298
 299         /* add the alternate entry */
 300         *alt_odb_tail = ent;
 301         alt_odb_tail = &(ent->next);
 302         ent->next = NULL;
 303
 304         /* recursively add alternates */
 305         read_info_alternates(ent->base, depth + 1);
 306
 307         ent->base[pfxlen] = '/';
 308
 309         return 0;
 310 }
 311
 312 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 313                                  const char *relative_base, int depth)
 314 {
 315         const char *cp, *last;
 316
 317         if (depth > 5) {
 318                 error("%s: ignoring alternate object stores, nesting too deep.",
 319                                 relative_base);
 320                 return;
 321         }
 322
 323         last = alt;
 324         while (last < ep) {
 325                 cp = last;
 326                 if (cp < ep && *cp == '#') {
 327                         while (cp < ep && *cp != sep)
 328                                 cp++;
 329                         last = cp + 1;
 330                         continue;
 331                 }
 332                 while (cp < ep && *cp != sep)
 333                         cp++;
 334                 if (last != cp) {
 335                         if ((*last != '/') && depth) {
 336                                 error("%s: ignoring relative alternate object store %s",
 337                                                 relative_base, last);
 338                         } else {
 339                                 link_alt_odb_entry(last, cp - last,
 340                                                 relative_base, depth);
 341                         }
 342                 }
 343                 while (cp < ep && *cp == sep)
 344                         cp++;
 345                 last = cp;
 346         }
 347 }
 348
 349 static void read_info_alternates(const char * relative_base, int depth)
 350 {
 351         char *map;
 352         size_t mapsz;
 353         struct stat st;
 354         char path[PATH_MAX];
 355         int fd;
 356
 357         sprintf(path, "%s/info/alternates", relative_base);
 358         fd = open(path, O_RDONLY);
 359         if (fd < 0)
 360                 return;
 361         if (fstat(fd, &st) || (st.st_size == 0)) {
 362                 close(fd);
 363                 return;
 364         }
 365         mapsz = xsize_t(st.st_size);
 366         map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 367         close(fd);
 368
 369         link_alt_odb_entries(map, map + mapsz, '\n', relative_base, depth);
 370
 371         munmap(map, mapsz);
 372 }
 373
 374 void prepare_alt_odb(void)
 375 {
 376         const char *alt;
 377
 378         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 379         if (!alt) alt = "";
 380
 381         if (alt_odb_tail)
 382                 return;
 383         alt_odb_tail = &alt_odb_list;
 384         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 385
 386         read_info_alternates(get_object_directory(), 0);
 387 }
 388
 389 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 390 {
 391         char *name = sha1_file_name(sha1);
 392         struct alternate_object_database *alt;
 393
 394         if (!stat(name, st))
 395                 return name;
 396         prepare_alt_odb();
 397         for (alt = alt_odb_list; alt; alt = alt->next) {
 398                 name = alt->name;
 399                 fill_sha1_path(name, sha1);
 400                 if (!stat(alt->base, st))
 401                         return alt->base;
 402         }
 403         return NULL;
 404 }
 405
 406 static unsigned int pack_used_ctr;
 407 static unsigned int pack_mmap_calls;
 408 static unsigned int peak_pack_open_windows;
 409 static unsigned int pack_open_windows;
 410 static size_t peak_pack_mapped;
 411 static size_t pack_mapped;
 412 struct packed_git *packed_git;
 413
 414 void pack_report()
 415 {
 416         fprintf(stderr,
 417                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 418                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 419                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 420                 (size_t) getpagesize(),
 421                 packed_git_window_size,
 422                 packed_git_limit);
 423         fprintf(stderr,
 424                 "pack_report: pack_used_ctr            = %10u\n"
 425                 "pack_report: pack_mmap_calls          = %10u\n"
 426                 "pack_report: pack_open_windows        = %10u / %10u\n"
 427                 "pack_report: pack_mapped              = "
 428                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
 429                 pack_used_ctr,
 430                 pack_mmap_calls,
 431                 pack_open_windows, peak_pack_open_windows,
 432                 pack_mapped, peak_pack_mapped);
 433 }
 434
 435 static int check_packed_git_idx(const char *path,
 436         unsigned long *idx_size_,
 437         void **idx_map_)
 438 {
 439         void *idx_map;
 440         uint32_t *index;
 441         size_t idx_size;
 442         uint32_t nr, i;
 443         int fd = open(path, O_RDONLY);
 444         struct stat st;
 445         if (fd < 0)
 446                 return -1;
 447         if (fstat(fd, &st)) {
 448                 close(fd);
 449                 return -1;
 450         }
 451         idx_size = xsize_t(st.st_size);
 452         if (idx_size < 4 * 256 + 20 + 20) {
 453                 close(fd);
 454                 return error("index file %s is too small", path);
 455         }
 456         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 457         close(fd);
 458
 459         index = idx_map;
 460         *idx_map_ = idx_map;
 461         *idx_size_ = idx_size;
 462
 463         /* a future index format would start with this, as older git
 464          * binaries would fail the non-monotonic index check below.
 465          * give a nicer warning to the user if we can.
 466          */
 467         if (index[0] == htonl(PACK_IDX_SIGNATURE)) {
 468                 munmap(idx_map, idx_size);
 469                 return error("index file %s is a newer version"
 470                         " and is not supported by this binary"
 471                         " (try upgrading GIT to a newer version)",
 472                         path);
 473         }
 474
 475         nr = 0;
 476         for (i = 0; i < 256; i++) {
 477                 uint32_t n = ntohl(index[i]);
 478                 if (n < nr) {
 479                         munmap(idx_map, idx_size);
 480                         return error("non-monotonic index %s", path);
 481                 }
 482                 nr = n;
 483         }
 484
 485         /*
 486          * Total size:
 487          *  - 256 index entries 4 bytes each
 488          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 489          *  - 20-byte SHA1 of the packfile
 490          *  - 20-byte SHA1 file checksum
 491          */
 492         if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 493                 munmap(idx_map, idx_size);
 494                 return error("wrong index file size in %s", path);
 495         }
 496
 497         return 0;
 498 }
 499
 500 static void scan_windows(struct packed_git *p,
 501         struct packed_git **lru_p,
 502         struct pack_window **lru_w,
 503         struct pack_window **lru_l)
 504 {
 505         struct pack_window *w, *w_l;
 506
 507         for (w_l = NULL, w = p->windows; w; w = w->next) {
 508                 if (!w->inuse_cnt) {
 509                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 510                                 *lru_p = p;
 511                                 *lru_w = w;
 512                                 *lru_l = w_l;
 513                         }
 514                 }
 515                 w_l = w;
 516         }
 517 }
 518
 519 static int unuse_one_window(struct packed_git *current)
 520 {
 521         struct packed_git *p, *lru_p = NULL;
 522         struct pack_window *lru_w = NULL, *lru_l = NULL;
 523
 524         if (current)
 525                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 526         for (p = packed_git; p; p = p->next)
 527                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 528         if (lru_p) {
 529                 munmap(lru_w->base, lru_w->len);
 530                 pack_mapped -= lru_w->len;
 531                 if (lru_l)
 532                         lru_l->next = lru_w->next;
 533                 else {
 534                         lru_p->windows = lru_w->next;
 535                         if (!lru_p->windows && lru_p != current) {
 536                                 close(lru_p->pack_fd);
 537                                 lru_p->pack_fd = -1;
 538                         }
 539                 }
 540                 free(lru_w);
 541                 pack_open_windows--;
 542                 return 1;
 543         }
 544         return 0;
 545 }
 546
 547 void release_pack_memory(size_t need)
 548 {
 549         size_t cur = pack_mapped;
 550         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 551                 ; /* nothing */
 552 }
 553
 554 void unuse_pack(struct pack_window **w_cursor)
 555 {
 556         struct pack_window *w = *w_cursor;
 557         if (w) {
 558                 w->inuse_cnt--;
 559                 *w_cursor = NULL;
 560         }
 561 }
 562
 563 /*
 564  * Do not call this directly as this leaks p->pack_fd on error return;
 565  * call open_packed_git() instead.
 566  */
 567 static int open_packed_git_1(struct packed_git *p)
 568 {
 569         struct stat st;
 570         struct pack_header hdr;
 571         unsigned char sha1[20];
 572         unsigned char *idx_sha1;
 573         long fd_flag;
 574
 575         p->pack_fd = open(p->pack_name, O_RDONLY);
 576         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 577                 return -1;
 578
 579         /* If we created the struct before we had the pack we lack size. */
 580         if (!p->pack_size) {
 581                 if (!S_ISREG(st.st_mode))
 582                         return error("packfile %s not a regular file", p->pack_name);
 583                 p->pack_size = st.st_size;
 584         } else if (p->pack_size != st.st_size)
 585                 return error("packfile %s size changed", p->pack_name);
 586
 587         /* We leave these file descriptors open with sliding mmap;
 588          * there is no point keeping them open across exec(), though.
 589          */
 590         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 591         if (fd_flag < 0)
 592                 return error("cannot determine file descriptor flags");
 593         fd_flag |= FD_CLOEXEC;
 594         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 595                 return error("cannot set FD_CLOEXEC");
 596
 597         /* Verify we recognize this pack file format. */
 598         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 599                 return error("file %s is far too short to be a packfile", p->pack_name);
 600         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 601                 return error("file %s is not a GIT packfile", p->pack_name);
 602         if (!pack_version_ok(hdr.hdr_version))
 603                 return error("packfile %s is version %u and not supported"
 604                         " (try upgrading GIT to a newer version)",
 605                         p->pack_name, ntohl(hdr.hdr_version));
 606
 607         /* Verify the pack matches its index. */
 608         if (num_packed_objects(p) != ntohl(hdr.hdr_entries))
 609                 return error("packfile %s claims to have %u objects"
 610                         " while index size indicates %u objects",
 611                         p->pack_name, ntohl(hdr.hdr_entries),
 612                         num_packed_objects(p));
 613         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 614                 return error("end of packfile %s is unavailable", p->pack_name);
 615         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 616                 return error("packfile %s signature is unavailable", p->pack_name);
 617         idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
 618         if (hashcmp(sha1, idx_sha1))
 619                 return error("packfile %s does not match index", p->pack_name);
 620         return 0;
 621 }
 622
 623 static int open_packed_git(struct packed_git *p)
 624 {
 625         if (!open_packed_git_1(p))
 626                 return 0;
 627         if (p->pack_fd != -1) {
 628                 close(p->pack_fd);
 629                 p->pack_fd = -1;
 630         }
 631         return -1;
 632 }
 633
 634 static int in_window(struct pack_window *win, off_t offset)
 635 {
 636         /* We must promise at least 20 bytes (one hash) after the
 637          * offset is available from this window, otherwise the offset
 638          * is not actually in this window and a different window (which
 639          * has that one hash excess) must be used.  This is to support
 640          * the object header and delta base parsing routines below.
 641          */
 642         off_t win_off = win->offset;
 643         return win_off <= offset
 644                 && (offset + 20) <= (win_off + win->len);
 645 }
 646
 647 unsigned char* use_pack(struct packed_git *p,
 648                 struct pack_window **w_cursor,
 649                 off_t offset,
 650                 unsigned int *left)
 651 {
 652         struct pack_window *win = *w_cursor;
 653
 654         if (p->pack_fd == -1 && open_packed_git(p))
 655                 die("packfile %s cannot be accessed", p->pack_name);
 656
 657         /* Since packfiles end in a hash of their content and its
 658          * pointless to ask for an offset into the middle of that
 659          * hash, and the in_window function above wouldn't match
 660          * don't allow an offset too close to the end of the file.
 661          */
 662         if (offset > (p->pack_size - 20))
 663                 die("offset beyond end of packfile (truncated pack?)");
 664
 665         if (!win || !in_window(win, offset)) {
 666                 if (win)
 667                         win->inuse_cnt--;
 668                 for (win = p->windows; win; win = win->next) {
 669                         if (in_window(win, offset))
 670                                 break;
 671                 }
 672                 if (!win) {
 673                         size_t window_align = packed_git_window_size / 2;
 674                         off_t len;
 675                         win = xcalloc(1, sizeof(*win));
 676                         win->offset = (offset / window_align) * window_align;
 677                         len = p->pack_size - win->offset;
 678                         if (len > packed_git_window_size)
 679                                 len = packed_git_window_size;
 680                         win->len = (size_t)len;
 681                         pack_mapped += win->len;
 682                         while (packed_git_limit < pack_mapped
 683                                 && unuse_one_window(p))
 684                                 ; /* nothing */
 685                         win->base = xmmap(NULL, win->len,
 686                                 PROT_READ, MAP_PRIVATE,
 687                                 p->pack_fd, win->offset);
 688                         if (win->base == MAP_FAILED)
 689                                 die("packfile %s cannot be mapped: %s",
 690                                         p->pack_name,
 691                                         strerror(errno));
 692                         pack_mmap_calls++;
 693                         pack_open_windows++;
 694                         if (pack_mapped > peak_pack_mapped)
 695                                 peak_pack_mapped = pack_mapped;
 696                         if (pack_open_windows > peak_pack_open_windows)
 697                                 peak_pack_open_windows = pack_open_windows;
 698                         win->next = p->windows;
 699                         p->windows = win;
 700                 }
 701         }
 702         if (win != *w_cursor) {
 703                 win->last_used = pack_used_ctr++;
 704                 win->inuse_cnt++;
 705                 *w_cursor = win;
 706         }
 707         offset -= win->offset;
 708         if (left)
 709                 *left = win->len - xsize_t(offset);
 710         return win->base + offset;
 711 }
 712
 713 struct packed_git *add_packed_git(char *path, int path_len, int local)
 714 {
 715         struct stat st;
 716         struct packed_git *p;
 717         unsigned long idx_size;
 718         void *idx_map;
 719         unsigned char sha1[20];
 720
 721         if (check_packed_git_idx(path, &idx_size, &idx_map))
 722                 return NULL;
 723
 724         /* do we have a corresponding .pack file? */
 725         strcpy(path + path_len - 4, ".pack");
 726         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 727                 munmap(idx_map, idx_size);
 728                 return NULL;
 729         }
 730         /* ok, it looks sane as far as we can check without
 731          * actually mapping the pack file.
 732          */
 733         p = xmalloc(sizeof(*p) + path_len + 2);
 734         strcpy(p->pack_name, path);
 735         p->index_size = idx_size;
 736         p->pack_size = st.st_size;
 737         p->index_base = idx_map;
 738         p->next = NULL;
 739         p->windows = NULL;
 740         p->pack_fd = -1;
 741         p->pack_local = local;
 742         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 743                 hashcpy(p->sha1, sha1);
 744         return p;
 745 }
 746
 747 struct packed_git *parse_pack_index(unsigned char *sha1)
 748 {
 749         char *path = sha1_pack_index_name(sha1);
 750         return parse_pack_index_file(sha1, path);
 751 }
 752
 753 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 754 {
 755         struct packed_git *p;
 756         unsigned long idx_size;
 757         void *idx_map;
 758         char *path;
 759
 760         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 761                 return NULL;
 762
 763         path = sha1_pack_name(sha1);
 764
 765         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 766         strcpy(p->pack_name, path);
 767         p->index_size = idx_size;
 768         p->pack_size = 0;
 769         p->index_base = idx_map;
 770         p->next = NULL;
 771         p->windows = NULL;
 772         p->pack_fd = -1;
 773         hashcpy(p->sha1, sha1);
 774         return p;
 775 }
 776
 777 void install_packed_git(struct packed_git *pack)
 778 {
 779         pack->next = packed_git;
 780         packed_git = pack;
 781 }
 782
 783 static void prepare_packed_git_one(char *objdir, int local)
 784 {
 785         char path[PATH_MAX];
 786         int len;
 787         DIR *dir;
 788         struct dirent *de;
 789
 790         sprintf(path, "%s/pack", objdir);
 791         len = strlen(path);
 792         dir = opendir(path);
 793         if (!dir) {
 794                 if (errno != ENOENT)
 795                         error("unable to open object pack directory: %s: %s",
 796                               path, strerror(errno));
 797                 return;
 798         }
 799         path[len++] = '/';
 800         while ((de = readdir(dir)) != NULL) {
 801                 int namelen = strlen(de->d_name);
 802                 struct packed_git *p;
 803
 804                 if (!has_extension(de->d_name, ".idx"))
 805                         continue;
 806
 807                 /* Don't reopen a pack we already have. */
 808                 strcpy(path + len, de->d_name);
 809                 for (p = packed_git; p; p = p->next) {
 810                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 811                                 break;
 812                 }
 813                 if (p)
 814                         continue;
 815                 /* See if it really is a valid .idx file with corresponding
 816                  * .pack file that we can map.
 817                  */
 818                 p = add_packed_git(path, len + namelen, local);
 819                 if (!p)
 820                         continue;
 821                 install_packed_git(p);
 822         }
 823         closedir(dir);
 824 }
 825
 826 static int prepare_packed_git_run_once = 0;
 827 void prepare_packed_git(void)
 828 {
 829         struct alternate_object_database *alt;
 830
 831         if (prepare_packed_git_run_once)
 832                 return;
 833         prepare_packed_git_one(get_object_directory(), 1);
 834         prepare_alt_odb();
 835         for (alt = alt_odb_list; alt; alt = alt->next) {
 836                 alt->name[-1] = 0;
 837                 prepare_packed_git_one(alt->base, 0);
 838                 alt->name[-1] = '/';
 839         }
 840         prepare_packed_git_run_once = 1;
 841 }
 842
 843 void reprepare_packed_git(void)
 844 {
 845         prepare_packed_git_run_once = 0;
 846         prepare_packed_git();
 847 }
 848
 849 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 850 {
 851         unsigned char real_sha1[20];
 852         hash_sha1_file(map, size, type, real_sha1);
 853         return hashcmp(sha1, real_sha1) ? -1 : 0;
 854 }
 855
 856 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 857 {
 858         struct stat st;
 859         void *map;
 860         int fd;
 861         char *filename = find_sha1_file(sha1, &st);
 862
 863         if (!filename) {
 864                 return NULL;
 865         }
 866
 867         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 868         if (fd < 0) {
 869                 /* See if it works without O_NOATIME */
 870                 switch (sha1_file_open_flag) {
 871                 default:
 872                         fd = open(filename, O_RDONLY);
 873                         if (fd >= 0)
 874                                 break;
 875                 /* Fallthrough */
 876                 case 0:
 877                         return NULL;
 878                 }
 879
 880                 /* If it failed once, it will probably fail again.
 881                  * Stop using O_NOATIME
 882                  */
 883                 sha1_file_open_flag = 0;
 884         }
 885         *size = xsize_t(st.st_size);
 886         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 887         close(fd);
 888         return map;
 889 }
 890
 891 int legacy_loose_object(unsigned char *map)
 892 {
 893         unsigned int word;
 894
 895         /*
 896          * Is it a zlib-compressed buffer? If so, the first byte
 897          * must be 0x78 (15-bit window size, deflated), and the
 898          * first 16-bit word is evenly divisible by 31
 899          */
 900         word = (map[0] << 8) + map[1];
 901         if (map[0] == 0x78 && !(word % 31))
 902                 return 1;
 903         else
 904                 return 0;
 905 }
 906
 907 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 908 {
 909         unsigned shift;
 910         unsigned char c;
 911         unsigned long size;
 912         unsigned long used = 0;
 913
 914         c = buf[used++];
 915         *type = (c >> 4) & 7;
 916         size = c & 15;
 917         shift = 4;
 918         while (c & 0x80) {
 919                 if (len <= used)
 920                         return 0;
 921                 if (sizeof(long) * 8 <= shift)
 922                         return 0;
 923                 c = buf[used++];
 924                 size += (c & 0x7f) << shift;
 925                 shift += 7;
 926         }
 927         *sizep = size;
 928         return used;
 929 }
 930
 931 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 932 {
 933         unsigned long size, used;
 934         static const char valid_loose_object_type[8] = {
 935                 0, /* OBJ_EXT */
 936                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 937                 0, /* "delta" and others are invalid in a loose object */
 938         };
 939         enum object_type type;
 940
 941         /* Get the data stream */
 942         memset(stream, 0, sizeof(*stream));
 943         stream->next_in = map;
 944         stream->avail_in = mapsize;
 945         stream->next_out = buffer;
 946         stream->avail_out = bufsiz;
 947
 948         if (legacy_loose_object(map)) {
 949                 inflateInit(stream);
 950                 return inflate(stream, 0);
 951         }
 952
 953         used = unpack_object_header_gently(map, mapsize, &type, &size);
 954         if (!used || !valid_loose_object_type[type])
 955                 return -1;
 956         map += used;
 957         mapsize -= used;
 958
 959         /* Set up the stream for the rest.. */
 960         stream->next_in = map;
 961         stream->avail_in = mapsize;
 962         inflateInit(stream);
 963
 964         /* And generate the fake traditional header */
 965         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 966                                          typename(type), size);
 967         return 0;
 968 }
 969
 970 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
 971 {
 972         int bytes = strlen(buffer) + 1;
 973         unsigned char *buf = xmalloc(1+size);
 974         unsigned long n;
 975         int status = Z_OK;
 976
 977         n = stream->total_out - bytes;
 978         if (n > size)
 979                 n = size;
 980         memcpy(buf, (char *) buffer + bytes, n);
 981         bytes = n;
 982         if (bytes < size) {
 983                 stream->next_out = buf + bytes;
 984                 stream->avail_out = size - bytes;
 985                 while (status == Z_OK)
 986                         status = inflate(stream, Z_FINISH);
 987         }
 988         buf[size] = 0;
 989         if ((status == Z_OK || status == Z_STREAM_END) && !stream->avail_in) {
 990                 inflateEnd(stream);
 991                 return buf;
 992         }
 993
 994         if (status < 0)
 995                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
 996         else if (stream->avail_in)
 997                 error("garbage at end of loose object '%s'",
 998                       sha1_to_hex(sha1));
 999         free(buf);
1000         return NULL;
1001 }
1002
1003 /*
1004  * We used to just use "sscanf()", but that's actually way
1005  * too permissive for what we want to check. So do an anal
1006  * object header parse by hand.
1007  */
1008 static int parse_sha1_header(const char *hdr, unsigned long *sizep)
1009 {
1010         char type[10];
1011         int i;
1012         unsigned long size;
1013
1014         /*
1015          * The type can be at most ten bytes (including the
1016          * terminating '\0' that we add), and is followed by
1017          * a space.
1018          */
1019         i = 0;
1020         for (;;) {
1021                 char c = *hdr++;
1022                 if (c == ' ')
1023                         break;
1024                 type[i++] = c;
1025                 if (i >= sizeof(type))
1026                         return -1;
1027         }
1028         type[i] = 0;
1029
1030         /*
1031          * The length must follow immediately, and be in canonical
1032          * decimal format (ie "010" is not valid).
1033          */
1034         size = *hdr++ - '0';
1035         if (size > 9)
1036                 return -1;
1037         if (size) {
1038                 for (;;) {
1039                         unsigned long c = *hdr - '0';
1040                         if (c > 9)
1041                                 break;
1042                         hdr++;
1043                         size = size * 10 + c;
1044                 }
1045         }
1046         *sizep = size;
1047
1048         /*
1049          * The length must be followed by a zero byte
1050          */
1051         return *hdr ? -1 : type_from_string(type);
1052 }
1053
1054 static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1055 {
1056         int ret;
1057         z_stream stream;
1058         char hdr[8192];
1059
1060         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1061         if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1062                 return NULL;
1063
1064         return unpack_sha1_rest(&stream, hdr, *size, sha1);
1065 }
1066
1067 static off_t get_delta_base(struct packed_git *p,
1068                                     struct pack_window **w_curs,
1069                                     off_t *curpos,
1070                                     enum object_type type,
1071                                     off_t delta_obj_offset)
1072 {
1073         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1074         off_t base_offset;
1075
1076         /* use_pack() assured us we have [base_info, base_info + 20)
1077          * as a range that we can look at without walking off the
1078          * end of the mapped window.  Its actually the hash size
1079          * that is assured.  An OFS_DELTA longer than the hash size
1080          * is stupid, as then a REF_DELTA would be smaller to store.
1081          */
1082         if (type == OBJ_OFS_DELTA) {
1083                 unsigned used = 0;
1084                 unsigned char c = base_info[used++];
1085                 base_offset = c & 127;
1086                 while (c & 128) {
1087                         base_offset += 1;
1088                         if (!base_offset || base_offset & ~(~0UL >> 7))
1089                                 die("offset value overflow for delta base object");
1090                         c = base_info[used++];
1091                         base_offset = (base_offset << 7) + (c & 127);
1092                 }
1093                 base_offset = delta_obj_offset - base_offset;
1094                 if (base_offset >= delta_obj_offset)
1095                         die("delta base offset out of bound");
1096                 *curpos += used;
1097         } else if (type == OBJ_REF_DELTA) {
1098                 /* The base entry _must_ be in the same pack */
1099                 base_offset = find_pack_entry_one(base_info, p);
1100                 if (!base_offset)
1101                         die("failed to find delta-pack base object %s",
1102                                 sha1_to_hex(base_info));
1103                 *curpos += 20;
1104         } else
1105                 die("I am totally screwed");
1106         return base_offset;
1107 }
1108
1109 /* forward declaration for a mutually recursive function */
1110 static int packed_object_info(struct packed_git *p, off_t offset,
1111                               unsigned long *sizep);
1112
1113 static int packed_delta_info(struct packed_git *p,
1114                              struct pack_window **w_curs,
1115                              off_t curpos,
1116                              enum object_type type,
1117                              off_t obj_offset,
1118                              unsigned long *sizep)
1119 {
1120         off_t base_offset;
1121
1122         base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1123         type = packed_object_info(p, base_offset, NULL);
1124
1125         /* We choose to only get the type of the base object and
1126          * ignore potentially corrupt pack file that expects the delta
1127          * based on a base with a wrong size.  This saves tons of
1128          * inflate() calls.
1129          */
1130         if (sizep) {
1131                 const unsigned char *data;
1132                 unsigned char delta_head[20], *in;
1133                 z_stream stream;
1134                 int st;
1135
1136                 memset(&stream, 0, sizeof(stream));
1137                 stream.next_out = delta_head;
1138                 stream.avail_out = sizeof(delta_head);
1139
1140                 inflateInit(&stream);
1141                 do {
1142                         in = use_pack(p, w_curs, curpos, &stream.avail_in);
1143                         stream.next_in = in;
1144                         st = inflate(&stream, Z_FINISH);
1145                         curpos += stream.next_in - in;
1146                 } while ((st == Z_OK || st == Z_BUF_ERROR)
1147                         && stream.total_out < sizeof(delta_head));
1148                 inflateEnd(&stream);
1149                 if ((st != Z_STREAM_END) &&
1150                     stream.total_out != sizeof(delta_head))
1151                         die("delta data unpack-initial failed");
1152
1153                 /* Examine the initial part of the delta to figure out
1154                  * the result size.
1155                  */
1156                 data = delta_head;
1157
1158                 /* ignore base size */
1159                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1160
1161                 /* Read the result size */
1162                 *sizep = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1163         }
1164
1165         return type;
1166 }
1167
1168 static int unpack_object_header(struct packed_git *p,
1169                                 struct pack_window **w_curs,
1170                                 off_t *curpos,
1171                                 unsigned long *sizep)
1172 {
1173         unsigned char *base;
1174         unsigned int left;
1175         unsigned long used;
1176         enum object_type type;
1177
1178         /* use_pack() assures us we have [base, base + 20) available
1179          * as a range that we can look at at.  (Its actually the hash
1180          * size that is assured.)  With our object header encoding
1181          * the maximum deflated object size is 2^137, which is just
1182          * insane, so we know won't exceed what we have been given.
1183          */
1184         base = use_pack(p, w_curs, *curpos, &left);
1185         used = unpack_object_header_gently(base, left, &type, sizep);
1186         if (!used)
1187                 die("object offset outside of pack file");
1188         *curpos += used;
1189
1190         return type;
1191 }
1192
1193 const char *packed_object_info_detail(struct packed_git *p,
1194                                       off_t obj_offset,
1195                                       unsigned long *size,
1196                                       unsigned long *store_size,
1197                                       unsigned int *delta_chain_length,
1198                                       unsigned char *base_sha1)
1199 {
1200         struct pack_window *w_curs = NULL;
1201         off_t curpos;
1202         unsigned long dummy;
1203         unsigned char *next_sha1;
1204         enum object_type type;
1205
1206         *delta_chain_length = 0;
1207         curpos = obj_offset;
1208         type = unpack_object_header(p, &w_curs, &curpos, size);
1209
1210         for (;;) {
1211                 switch (type) {
1212                 default:
1213                         die("pack %s contains unknown object type %d",
1214                             p->pack_name, type);
1215                 case OBJ_COMMIT:
1216                 case OBJ_TREE:
1217                 case OBJ_BLOB:
1218                 case OBJ_TAG:
1219                         *store_size = 0; /* notyet */
1220                         unuse_pack(&w_curs);
1221                         return typename(type);
1222                 case OBJ_OFS_DELTA:
1223                         obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1224                         if (*delta_chain_length == 0) {
1225                                 /* TODO: find base_sha1 as pointed by curpos */
1226                                 hashclr(base_sha1);
1227                         }
1228                         break;
1229                 case OBJ_REF_DELTA:
1230                         next_sha1 = use_pack(p, &w_curs, curpos, NULL);
1231                         if (*delta_chain_length == 0)
1232                                 hashcpy(base_sha1, next_sha1);
1233                         obj_offset = find_pack_entry_one(next_sha1, p);
1234                         break;
1235                 }
1236                 (*delta_chain_length)++;
1237                 curpos = obj_offset;
1238                 type = unpack_object_header(p, &w_curs, &curpos, &dummy);
1239         }
1240 }
1241
1242 static int packed_object_info(struct packed_git *p, off_t obj_offset,
1243                               unsigned long *sizep)
1244 {
1245         struct pack_window *w_curs = NULL;
1246         unsigned long size;
1247         off_t curpos = obj_offset;
1248         enum object_type type;
1249
1250         type = unpack_object_header(p, &w_curs, &curpos, &size);
1251
1252         switch (type) {
1253         case OBJ_OFS_DELTA:
1254         case OBJ_REF_DELTA:
1255                 type = packed_delta_info(p, &w_curs, curpos,
1256                                          type, obj_offset, sizep);
1257                 break;
1258         case OBJ_COMMIT:
1259         case OBJ_TREE:
1260         case OBJ_BLOB:
1261         case OBJ_TAG:
1262                 if (sizep)
1263                         *sizep = size;
1264                 break;
1265         default:
1266                 die("pack %s contains unknown object type %d",
1267                     p->pack_name, type);
1268         }
1269         unuse_pack(&w_curs);
1270         return type;
1271 }
1272
1273 static void *unpack_compressed_entry(struct packed_git *p,
1274                                     struct pack_window **w_curs,
1275                                     off_t curpos,
1276                                     unsigned long size)
1277 {
1278         int st;
1279         z_stream stream;
1280         unsigned char *buffer, *in;
1281
1282         buffer = xmalloc(size + 1);
1283         buffer[size] = 0;
1284         memset(&stream, 0, sizeof(stream));
1285         stream.next_out = buffer;
1286         stream.avail_out = size;
1287
1288         inflateInit(&stream);
1289         do {
1290                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1291                 stream.next_in = in;
1292                 st = inflate(&stream, Z_FINISH);
1293                 curpos += stream.next_in - in;
1294         } while (st == Z_OK || st == Z_BUF_ERROR);
1295         inflateEnd(&stream);
1296         if ((st != Z_STREAM_END) || stream.total_out != size) {
1297                 free(buffer);
1298                 return NULL;
1299         }
1300
1301         return buffer;
1302 }
1303
1304 static void *unpack_delta_entry(struct packed_git *p,
1305                                 struct pack_window **w_curs,
1306                                 off_t curpos,
1307                                 unsigned long delta_size,
1308                                 off_t obj_offset,
1309                                 enum object_type *type,
1310                                 unsigned long *sizep)
1311 {
1312         void *delta_data, *result, *base;
1313         unsigned long base_size;
1314         off_t base_offset;
1315
1316         base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
1317         base = unpack_entry(p, base_offset, type, &base_size);
1318         if (!base)
1319                 die("failed to read delta base object"
1320                     " at %"PRIuMAX" from %s",
1321                     (uintmax_t)base_offset, p->pack_name);
1322
1323         delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
1324         result = patch_delta(base, base_size,
1325                              delta_data, delta_size,
1326                              sizep);
1327         if (!result)
1328                 die("failed to apply delta");
1329         free(delta_data);
1330         free(base);
1331         return result;
1332 }
1333
1334 void *unpack_entry(struct packed_git *p, off_t obj_offset,
1335                    enum object_type *type, unsigned long *sizep)
1336 {
1337         struct pack_window *w_curs = NULL;
1338         off_t curpos = obj_offset;
1339         void *data;
1340
1341         *type = unpack_object_header(p, &w_curs, &curpos, sizep);
1342         switch (*type) {
1343         case OBJ_OFS_DELTA:
1344         case OBJ_REF_DELTA:
1345                 data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
1346                                           obj_offset, type, sizep);
1347                 break;
1348         case OBJ_COMMIT:
1349         case OBJ_TREE:
1350         case OBJ_BLOB:
1351         case OBJ_TAG:
1352                 data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
1353                 break;
1354         default:
1355                 die("unknown object type %i in %s", *type, p->pack_name);
1356         }
1357         unuse_pack(&w_curs);
1358         return data;
1359 }
1360
1361 uint32_t num_packed_objects(const struct packed_git *p)
1362 {
1363         /* See check_packed_git_idx() */
1364         return (uint32_t)((p->index_size - 20 - 20 - 4*256) / 24);
1365 }
1366
1367 int nth_packed_object_sha1(const struct packed_git *p, uint32_t n,
1368                            unsigned char* sha1)
1369 {
1370         void *index = p->index_base + 256;
1371         if (num_packed_objects(p) <= n)
1372                 return -1;
1373         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1374         return 0;
1375 }
1376
1377 off_t find_pack_entry_one(const unsigned char *sha1,
1378                                   struct packed_git *p)
1379 {
1380         uint32_t *level1_ofs = p->index_base;
1381         int hi = ntohl(level1_ofs[*sha1]);
1382         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1383         void *index = p->index_base + 256;
1384
1385         do {
1386                 int mi = (lo + hi) / 2;
1387                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1388                 if (!cmp)
1389                         return ntohl(*((uint32_t *)((char *)index + (24 * mi))));
1390                 if (cmp > 0)
1391                         hi = mi;
1392                 else
1393                         lo = mi+1;
1394         } while (lo < hi);
1395         return 0;
1396 }
1397
1398 static int matches_pack_name(struct packed_git *p, const char *ig)
1399 {
1400         const char *last_c, *c;
1401
1402         if (!strcmp(p->pack_name, ig))
1403                 return 0;
1404
1405         for (c = p->pack_name, last_c = c; *c;)
1406                 if (*c == '/')
1407                         last_c = ++c;
1408                 else
1409                         ++c;
1410         if (!strcmp(last_c, ig))
1411                 return 0;
1412
1413         return 1;
1414 }
1415
1416 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1417 {
1418         struct packed_git *p;
1419         off_t offset;
1420
1421         prepare_packed_git();
1422
1423         for (p = packed_git; p; p = p->next) {
1424                 if (ignore_packed) {
1425                         const char **ig;
1426                         for (ig = ignore_packed; *ig; ig++)
1427                                 if (!matches_pack_name(p, *ig))
1428                                         break;
1429                         if (*ig)
1430                                 continue;
1431                 }
1432                 offset = find_pack_entry_one(sha1, p);
1433                 if (offset) {
1434                         /*
1435                          * We are about to tell the caller where they can
1436                          * locate the requested object.  We better make
1437                          * sure the packfile is still here and can be
1438                          * accessed before supplying that answer, as
1439                          * it may have been deleted since the index
1440                          * was loaded!
1441                          */
1442                         if (p->pack_fd == -1 && open_packed_git(p)) {
1443                                 error("packfile %s cannot be accessed", p->pack_name);
1444                                 continue;
1445                         }
1446                         e->offset = offset;
1447                         e->p = p;
1448                         hashcpy(e->sha1, sha1);
1449                         return 1;
1450                 }
1451         }
1452         return 0;
1453 }
1454
1455 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1456                                   struct packed_git *packs)
1457 {
1458         struct packed_git *p;
1459
1460         for (p = packs; p; p = p->next) {
1461                 if (find_pack_entry_one(sha1, p))
1462                         return p;
1463         }
1464         return NULL;
1465
1466 }
1467
1468 static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
1469 {
1470         int status;
1471         unsigned long mapsize, size;
1472         void *map;
1473         z_stream stream;
1474         char hdr[32];
1475
1476         map = map_sha1_file(sha1, &mapsize);
1477         if (!map)
1478                 return error("unable to find %s", sha1_to_hex(sha1));
1479         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1480                 status = error("unable to unpack %s header",
1481                                sha1_to_hex(sha1));
1482         else if ((status = parse_sha1_header(hdr, &size)) < 0)
1483                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1484         else if (sizep)
1485                 *sizep = size;
1486         inflateEnd(&stream);
1487         munmap(map, mapsize);
1488         return status;
1489 }
1490
1491 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
1492 {
1493         struct pack_entry e;
1494
1495         if (!find_pack_entry(sha1, &e, NULL)) {
1496                 reprepare_packed_git();
1497                 if (!find_pack_entry(sha1, &e, NULL))
1498                         return sha1_loose_object_info(sha1, sizep);
1499         }
1500         return packed_object_info(e.p, e.offset, sizep);
1501 }
1502
1503 static void *read_packed_sha1(const unsigned char *sha1,
1504                               enum object_type *type, unsigned long *size)
1505 {
1506         struct pack_entry e;
1507
1508         if (!find_pack_entry(sha1, &e, NULL))
1509                 return NULL;
1510         else
1511                 return unpack_entry(e.p, e.offset, type, size);
1512 }
1513
1514 /*
1515  * This is meant to hold a *small* number of objects that you would
1516  * want read_sha1_file() to be able to return, but yet you do not want
1517  * to write them into the object store (e.g. a browse-only
1518  * application).
1519  */
1520 static struct cached_object {
1521         unsigned char sha1[20];
1522         enum object_type type;
1523         void *buf;
1524         unsigned long size;
1525 } *cached_objects;
1526 static int cached_object_nr, cached_object_alloc;
1527
1528 static struct cached_object *find_cached_object(const unsigned char *sha1)
1529 {
1530         int i;
1531         struct cached_object *co = cached_objects;
1532
1533         for (i = 0; i < cached_object_nr; i++, co++) {
1534                 if (!hashcmp(co->sha1, sha1))
1535                         return co;
1536         }
1537         return NULL;
1538 }
1539
1540 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
1541                       unsigned char *sha1)
1542 {
1543         struct cached_object *co;
1544
1545         hash_sha1_file(buf, len, typename(type), sha1);
1546         if (has_sha1_file(sha1) || find_cached_object(sha1))
1547                 return 0;
1548         if (cached_object_alloc <= cached_object_nr) {
1549                 cached_object_alloc = alloc_nr(cached_object_alloc);
1550                 cached_objects = xrealloc(cached_objects,
1551                                           sizeof(*cached_objects) *
1552                                           cached_object_alloc);
1553         }
1554         co = &cached_objects[cached_object_nr++];
1555         co->size = len;
1556         co->type = type;
1557         co->buf = xmalloc(len);
1558         memcpy(co->buf, buf, len);
1559         hashcpy(co->sha1, sha1);
1560         return 0;
1561 }
1562
1563 void *read_sha1_file(const unsigned char *sha1, enum object_type *type,
1564                      unsigned long *size)
1565 {
1566         unsigned long mapsize;
1567         void *map, *buf;
1568         struct cached_object *co;
1569
1570         co = find_cached_object(sha1);
1571         if (co) {
1572                 buf = xmalloc(co->size + 1);
1573                 memcpy(buf, co->buf, co->size);
1574                 ((char*)buf)[co->size] = 0;
1575                 *type = co->type;
1576                 *size = co->size;
1577                 return buf;
1578         }
1579
1580         buf = read_packed_sha1(sha1, type, size);
1581         if (buf)
1582                 return buf;
1583         map = map_sha1_file(sha1, &mapsize);
1584         if (map) {
1585                 buf = unpack_sha1_file(map, mapsize, type, size, sha1);
1586                 munmap(map, mapsize);
1587                 return buf;
1588         }
1589         reprepare_packed_git();
1590         return read_packed_sha1(sha1, type, size);
1591 }
1592
1593 void *read_object_with_reference(const unsigned char *sha1,
1594                                  const char *required_type_name,
1595                                  unsigned long *size,
1596                                  unsigned char *actual_sha1_return)
1597 {
1598         enum object_type type, required_type;
1599         void *buffer;
1600         unsigned long isize;
1601         unsigned char actual_sha1[20];
1602
1603         required_type = type_from_string(required_type_name);
1604         hashcpy(actual_sha1, sha1);
1605         while (1) {
1606                 int ref_length = -1;
1607                 const char *ref_type = NULL;
1608
1609                 buffer = read_sha1_file(actual_sha1, &type, &isize);
1610                 if (!buffer)
1611                         return NULL;
1612                 if (type == required_type) {
1613                         *size = isize;
1614                         if (actual_sha1_return)
1615                                 hashcpy(actual_sha1_return, actual_sha1);
1616                         return buffer;
1617                 }
1618                 /* Handle references */
1619                 else if (type == OBJ_COMMIT)
1620                         ref_type = "tree ";
1621                 else if (type == OBJ_TAG)
1622                         ref_type = "object ";
1623                 else {
1624                         free(buffer);
1625                         return NULL;
1626                 }
1627                 ref_length = strlen(ref_type);
1628
1629                 if (memcmp(buffer, ref_type, ref_length) ||
1630                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1631                         free(buffer);
1632                         return NULL;
1633                 }
1634                 free(buffer);
1635                 /* Now we have the ID of the referred-to object in
1636                  * actual_sha1.  Check again. */
1637         }
1638 }
1639
1640 static void write_sha1_file_prepare(void *buf, unsigned long len,
1641                                     const char *type, unsigned char *sha1,
1642                                     char *hdr, int *hdrlen)
1643 {
1644         SHA_CTX c;
1645
1646         /* Generate the header */
1647         *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
1648
1649         /* Sha1.. */
1650         SHA1_Init(&c);
1651         SHA1_Update(&c, hdr, *hdrlen);
1652         SHA1_Update(&c, buf, len);
1653         SHA1_Final(sha1, &c);
1654 }
1655
1656 /*
1657  * Link the tempfile to the final place, possibly creating the
1658  * last directory level as you do so.
1659  *
1660  * Returns the errno on failure, 0 on success.
1661  */
1662 static int link_temp_to_file(const char *tmpfile, const char *filename)
1663 {
1664         int ret;
1665         char *dir;
1666
1667         if (!link(tmpfile, filename))
1668                 return 0;
1669
1670         /*
1671          * Try to mkdir the last path component if that failed.
1672          *
1673          * Re-try the "link()" regardless of whether the mkdir
1674          * succeeds, since a race might mean that somebody
1675          * else succeeded.
1676          */
1677         ret = errno;
1678         dir = strrchr(filename, '/');
1679         if (dir) {
1680                 *dir = 0;
1681                 if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1682                         *dir = '/';
1683                         return -2;
1684                 }
1685                 *dir = '/';
1686                 if (!link(tmpfile, filename))
1687                         return 0;
1688                 ret = errno;
1689         }
1690         return ret;
1691 }
1692
1693 /*
1694  * Move the just written object into its final resting place
1695  */
1696 int move_temp_to_file(const char *tmpfile, const char *filename)
1697 {
1698         int ret = link_temp_to_file(tmpfile, filename);
1699
1700         /*
1701          * Coda hack - coda doesn't like cross-directory links,
1702          * so we fall back to a rename, which will mean that it
1703          * won't be able to check collisions, but that's not a
1704          * big deal.
1705          *
1706          * The same holds for FAT formatted media.
1707          *
1708          * When this succeeds, we just return 0. We have nothing
1709          * left to unlink.
1710          */
1711         if (ret && ret != EEXIST) {
1712                 if (!rename(tmpfile, filename))
1713                         return 0;
1714                 ret = errno;
1715         }
1716         unlink(tmpfile);
1717         if (ret) {
1718                 if (ret != EEXIST) {
1719                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1720                 }
1721                 /* FIXME!!! Collision check here ? */
1722         }
1723
1724         return 0;
1725 }
1726
1727 static int write_buffer(int fd, const void *buf, size_t len)
1728 {
1729         if (write_in_full(fd, buf, len) < 0)
1730                 return error("file write error (%s)", strerror(errno));
1731         return 0;
1732 }
1733
1734 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1735 {
1736         int hdr_len;
1737         unsigned char c;
1738
1739         c = (type << 4) | (len & 15);
1740         len >>= 4;
1741         hdr_len = 1;
1742         while (len) {
1743                 *hdr++ = c | 0x80;
1744                 hdr_len++;
1745                 c = (len & 0x7f);
1746                 len >>= 7;
1747         }
1748         *hdr = c;
1749         return hdr_len;
1750 }
1751
1752 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1753 {
1754         int obj_type, hdrlen;
1755
1756         if (use_legacy_headers) {
1757                 while (deflate(stream, 0) == Z_OK)
1758                         /* nothing */;
1759                 return;
1760         }
1761         obj_type = type_from_string(type);
1762         hdrlen = write_binary_header(stream->next_out, obj_type, len);
1763         stream->total_out = hdrlen;
1764         stream->next_out += hdrlen;
1765         stream->avail_out -= hdrlen;
1766 }
1767
1768 int hash_sha1_file(void *buf, unsigned long len, const char *type,
1769                    unsigned char *sha1)
1770 {
1771         char hdr[32];
1772         int hdrlen;
1773         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1774         return 0;
1775 }
1776
1777 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1778 {
1779         int size;
1780         unsigned char *compressed;
1781         z_stream stream;
1782         unsigned char sha1[20];
1783         char *filename;
1784         static char tmpfile[PATH_MAX];
1785         char hdr[32];
1786         int fd, hdrlen;
1787
1788         /* Normally if we have it in the pack then we do not bother writing
1789          * it out into .git/objects/??/?{38} file.
1790          */
1791         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1792         filename = sha1_file_name(sha1);
1793         if (returnsha1)
1794                 hashcpy(returnsha1, sha1);
1795         if (has_sha1_file(sha1))
1796                 return 0;
1797         fd = open(filename, O_RDONLY);
1798         if (fd >= 0) {
1799                 /*
1800                  * FIXME!!! We might do collision checking here, but we'd
1801                  * need to uncompress the old file and check it. Later.
1802                  */
1803                 close(fd);
1804                 return 0;
1805         }
1806
1807         if (errno != ENOENT) {
1808                 return error("sha1 file %s: %s\n", filename, strerror(errno));
1809         }
1810
1811         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1812
1813         fd = mkstemp(tmpfile);
1814         if (fd < 0) {
1815                 if (errno == EPERM)
1816                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1817                 else
1818                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1819         }
1820
1821         /* Set it up */
1822         memset(&stream, 0, sizeof(stream));
1823         deflateInit(&stream, zlib_compression_level);
1824         size = 8 + deflateBound(&stream, len+hdrlen);
1825         compressed = xmalloc(size);
1826
1827         /* Compress it */
1828         stream.next_out = compressed;
1829         stream.avail_out = size;
1830
1831         /* First header.. */
1832         stream.next_in = (unsigned char *)hdr;
1833         stream.avail_in = hdrlen;
1834         setup_object_header(&stream, type, len);
1835
1836         /* Then the data itself.. */
1837         stream.next_in = buf;
1838         stream.avail_in = len;
1839         while (deflate(&stream, Z_FINISH) == Z_OK)
1840                 /* nothing */;
1841         deflateEnd(&stream);
1842         size = stream.total_out;
1843
1844         if (write_buffer(fd, compressed, size) < 0)
1845                 die("unable to write sha1 file");
1846         fchmod(fd, 0444);
1847         close(fd);
1848         free(compressed);
1849
1850         return move_temp_to_file(tmpfile, filename);
1851 }
1852
1853 /*
1854  * We need to unpack and recompress the object for writing
1855  * it out to a different file.
1856  */
1857 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1858 {
1859         size_t size;
1860         z_stream stream;
1861         unsigned char *unpacked;
1862         unsigned long len;
1863         enum object_type type;
1864         char hdr[32];
1865         int hdrlen;
1866         void *buf;
1867
1868         /* need to unpack and recompress it by itself */
1869         unpacked = read_packed_sha1(sha1, &type, &len);
1870         if (!unpacked)
1871                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1872
1873         hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
1874
1875         /* Set it up */
1876         memset(&stream, 0, sizeof(stream));
1877         deflateInit(&stream, zlib_compression_level);
1878         size = deflateBound(&stream, len + hdrlen);
1879         buf = xmalloc(size);
1880
1881         /* Compress it */
1882         stream.next_out = buf;
1883         stream.avail_out = size;
1884
1885         /* First header.. */
1886         stream.next_in = (void *)hdr;
1887         stream.avail_in = hdrlen;
1888         while (deflate(&stream, 0) == Z_OK)
1889                 /* nothing */;
1890
1891         /* Then the data itself.. */
1892         stream.next_in = unpacked;
1893         stream.avail_in = len;
1894         while (deflate(&stream, Z_FINISH) == Z_OK)
1895                 /* nothing */;
1896         deflateEnd(&stream);
1897         free(unpacked);
1898
1899         *objsize = stream.total_out;
1900         return buf;
1901 }
1902
1903 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1904 {
1905         int retval;
1906         unsigned long objsize;
1907         void *buf = map_sha1_file(sha1, &objsize);
1908
1909         if (buf) {
1910                 retval = write_buffer(fd, buf, objsize);
1911                 munmap(buf, objsize);
1912                 return retval;
1913         }
1914
1915         buf = repack_object(sha1, &objsize);
1916         retval = write_buffer(fd, buf, objsize);
1917         free(buf);
1918         return retval;
1919 }
1920
1921 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1922                        size_t bufsize, size_t *bufposn)
1923 {
1924         char tmpfile[PATH_MAX];
1925         int local;
1926         z_stream stream;
1927         unsigned char real_sha1[20];
1928         unsigned char discard[4096];
1929         int ret;
1930         SHA_CTX c;
1931
1932         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1933
1934         local = mkstemp(tmpfile);
1935         if (local < 0) {
1936                 if (errno == EPERM)
1937                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1938                 else
1939                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1940         }
1941
1942         memset(&stream, 0, sizeof(stream));
1943
1944         inflateInit(&stream);
1945
1946         SHA1_Init(&c);
1947
1948         do {
1949                 ssize_t size;
1950                 if (*bufposn) {
1951                         stream.avail_in = *bufposn;
1952                         stream.next_in = (unsigned char *) buffer;
1953                         do {
1954                                 stream.next_out = discard;
1955                                 stream.avail_out = sizeof(discard);
1956                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1957                                 SHA1_Update(&c, discard, sizeof(discard) -
1958                                             stream.avail_out);
1959                         } while (stream.avail_in && ret == Z_OK);
1960                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1961                                 die("unable to write sha1 file");
1962                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1963                                 stream.avail_in);
1964                         *bufposn = stream.avail_in;
1965                         if (ret != Z_OK)
1966                                 break;
1967                 }
1968                 size = xread(fd, buffer + *bufposn, bufsize - *bufposn);
1969                 if (size <= 0) {
1970                         close(local);
1971                         unlink(tmpfile);
1972                         if (!size)
1973                                 return error("Connection closed?");
1974                         perror("Reading from connection");
1975                         return -1;
1976                 }
1977                 *bufposn += size;
1978         } while (1);
1979         inflateEnd(&stream);
1980
1981         close(local);
1982         SHA1_Final(real_sha1, &c);
1983         if (ret != Z_STREAM_END) {
1984                 unlink(tmpfile);
1985                 return error("File %s corrupted", sha1_to_hex(sha1));
1986         }
1987         if (hashcmp(sha1, real_sha1)) {
1988                 unlink(tmpfile);
1989                 return error("File %s has bad hash", sha1_to_hex(sha1));
1990         }
1991
1992         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1993 }
1994
1995 int has_pack_index(const unsigned char *sha1)
1996 {
1997         struct stat st;
1998         if (stat(sha1_pack_index_name(sha1), &st))
1999                 return 0;
2000         return 1;
2001 }
2002
2003 int has_pack_file(const unsigned char *sha1)
2004 {
2005         struct stat st;
2006         if (stat(sha1_pack_name(sha1), &st))
2007                 return 0;
2008         return 1;
2009 }
2010
2011 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
2012 {
2013         struct pack_entry e;
2014         return find_pack_entry(sha1, &e, ignore_packed);
2015 }
2016
2017 int has_sha1_file(const unsigned char *sha1)
2018 {
2019         struct stat st;
2020         struct pack_entry e;
2021
2022         if (find_pack_entry(sha1, &e, NULL))
2023                 return 1;
2024         return find_sha1_file(sha1, &st) ? 1 : 0;
2025 }
2026
2027 /*
2028  * reads from fd as long as possible into a supplied buffer of size bytes.
2029  * If necessary the buffer's size is increased using realloc()
2030  *
2031  * returns 0 if anything went fine and -1 otherwise
2032  *
2033  * NOTE: both buf and size may change, but even when -1 is returned
2034  * you still have to free() it yourself.
2035  */
2036 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
2037 {
2038         char* buf = *return_buf;
2039         unsigned long size = *return_size;
2040         int iret;
2041         unsigned long off = 0;
2042
2043         do {
2044                 iret = xread(fd, buf + off, size - off);
2045                 if (iret > 0) {
2046                         off += iret;
2047                         if (off == size) {
2048                                 size *= 2;
2049                                 buf = xrealloc(buf, size);
2050                         }
2051                 }
2052         } while (iret > 0);
2053
2054         *return_buf = buf;
2055         *return_size = off;
2056
2057         if (iret < 0)
2058                 return -1;
2059         return 0;
2060 }
2061
2062 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
2063 {
2064         unsigned long size = 4096;
2065         char *buf = xmalloc(size);
2066         int ret;
2067
2068         if (read_pipe(fd, &buf, &size)) {
2069                 free(buf);
2070                 return -1;
2071         }
2072
2073         if (!type)
2074                 type = blob_type;
2075         if (write_object)
2076                 ret = write_sha1_file(buf, size, type, sha1);
2077         else
2078                 ret = hash_sha1_file(buf, size, type, sha1);
2079         free(buf);
2080         return ret;
2081 }
2082
2083 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
2084              enum object_type type, const char *path)
2085 {
2086         size_t size = xsize_t(st->st_size);
2087         void *buf = NULL;
2088         int ret, re_allocated = 0;
2089
2090         if (size)
2091                 buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2092         close(fd);
2093
2094         if (!type)
2095                 type = OBJ_BLOB;
2096
2097         /*
2098          * Convert blobs to git internal format
2099          */
2100         if ((type == OBJ_BLOB) && S_ISREG(st->st_mode)) {
2101                 unsigned long nsize = size;
2102                 char *nbuf = buf;
2103                 if (convert_to_git(path, &nbuf, &nsize)) {
2104                         if (size)
2105                                 munmap(buf, size);
2106                         size = nsize;
2107                         buf = nbuf;
2108                         re_allocated = 1;
2109                 }
2110         }
2111
2112         if (write_object)
2113                 ret = write_sha1_file(buf, size, typename(type), sha1);
2114         else
2115                 ret = hash_sha1_file(buf, size, typename(type), sha1);
2116         if (re_allocated) {
2117                 free(buf);
2118                 return ret;
2119         }
2120         if (size)
2121                 munmap(buf, size);
2122         return ret;
2123 }
2124
2125 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2126 {
2127         int fd;
2128         char *target;
2129         size_t len;
2130
2131         switch (st->st_mode & S_IFMT) {
2132         case S_IFREG:
2133                 fd = open(path, O_RDONLY);
2134                 if (fd < 0)
2135                         return error("open(\"%s\"): %s", path,
2136                                      strerror(errno));
2137                 if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path) < 0)
2138                         return error("%s: failed to insert into database",
2139                                      path);
2140                 break;
2141         case S_IFLNK:
2142                 len = xsize_t(st->st_size);
2143                 target = xmalloc(len + 1);
2144                 if (readlink(path, target, len + 1) != st->st_size) {
2145                         char *errstr = strerror(errno);
2146                         free(target);
2147                         return error("readlink(\"%s\"): %s", path,
2148                                      errstr);
2149                 }
2150                 if (!write_object)
2151                         hash_sha1_file(target, len, blob_type, sha1);
2152                 else if (write_sha1_file(target, len, blob_type, sha1))
2153                         return error("%s: failed to insert into database",
2154                                      path);
2155                 free(target);
2156                 break;
2157         default:
2158                 return error("%s: unsupported file type", path);
2159         }
2160         return 0;
2161 }
2162
2163 int read_pack_header(int fd, struct pack_header *header)
2164 {
2165         char *c = (char*)header;
2166         ssize_t remaining = sizeof(struct pack_header);
2167         do {
2168                 ssize_t r = xread(fd, c, remaining);
2169                 if (r <= 0)
2170                         /* "eof before pack header was fully read" */
2171                         return PH_ERROR_EOF;
2172                 remaining -= r;
2173                 c += r;
2174         } while (remaining > 0);
2175         if (header->hdr_signature != htonl(PACK_SIGNATURE))
2176                 /* "protocol error (pack signature mismatch detected)" */
2177                 return PH_ERROR_PACK_SIGNATURE;
2178         if (!pack_version_ok(header->hdr_version))
2179                 /* "protocol error (pack version unsupported)" */
2180                 return PH_ERROR_PROTOCOL;
2181         return 0;
2182 }