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