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