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