git.oblomov.eu Git - git/blob - sha1_file.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include "cache.h"
  10 #include "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 const unsigned char null_sha1[20] = { 0, };
  26
  27 static unsigned int sha1_file_open_flag = O_NOATIME;
  28
  29 static unsigned hexval(char c)
  30 {
  31         if (c >= '0' && c <= '9')
  32                 return c - '0';
  33         if (c >= 'a' && c <= 'f')
  34                 return c - 'a' + 10;
  35         if (c >= 'A' && c <= 'F')
  36                 return c - 'A' + 10;
  37         return ~0;
  38 }
  39
  40 int get_sha1_hex(const char *hex, unsigned char *sha1)
  41 {
  42         int i;
  43         for (i = 0; i < 20; i++) {
  44                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  45                 if (val & ~0xff)
  46                         return -1;
  47                 *sha1++ = val;
  48                 hex += 2;
  49         }
  50         return 0;
  51 }
  52
  53 int adjust_shared_perm(const char *path)
  54 {
  55         struct stat st;
  56         int mode;
  57
  58         if (!shared_repository)
  59                 return 0;
  60         if (lstat(path, &st) < 0)
  61                 return -1;
  62         mode = st.st_mode;
  63         if (mode & S_IRUSR)
  64                 mode |= S_IRGRP;
  65         if (mode & S_IWUSR)
  66                 mode |= S_IWGRP;
  67         if (mode & S_IXUSR)
  68                 mode |= S_IXGRP;
  69         if (S_ISDIR(mode))
  70                 mode |= S_ISGID;
  71         if (chmod(path, mode) < 0)
  72                 return -2;
  73         return 0;
  74 }
  75
  76 int safe_create_leading_directories(char *path)
  77 {
  78         char *pos = path;
  79         struct stat st;
  80
  81         if (*pos == '/')
  82                 pos++;
  83
  84         while (pos) {
  85                 pos = strchr(pos, '/');
  86                 if (!pos)
  87                         break;
  88                 *pos = 0;
  89                 if (!stat(path, &st)) {
  90                         /* path exists */
  91                         if (!S_ISDIR(st.st_mode)) {
  92                                 *pos = '/';
  93                                 return -3;
  94                         }
  95                 }
  96                 else if (mkdir(path, 0777)) {
  97                         *pos = '/';
  98                         return -1;
  99                 }
 100                 else if (adjust_shared_perm(path)) {
 101                         *pos = '/';
 102                         return -2;
 103                 }
 104                 *pos++ = '/';
 105         }
 106         return 0;
 107 }
 108
 109 char * sha1_to_hex(const unsigned char *sha1)
 110 {
 111         static int bufno;
 112         static char hexbuffer[4][50];
 113         static const char hex[] = "0123456789abcdef";
 114         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
 115         int i;
 116
 117         for (i = 0; i < 20; i++) {
 118                 unsigned int val = *sha1++;
 119                 *buf++ = hex[val >> 4];
 120                 *buf++ = hex[val & 0xf];
 121         }
 122         *buf = '\0';
 123
 124         return buffer;
 125 }
 126
 127 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 128 {
 129         int i;
 130         for (i = 0; i < 20; i++) {
 131                 static char hex[] = "0123456789abcdef";
 132                 unsigned int val = sha1[i];
 133                 char *pos = pathbuf + i*2 + (i > 0);
 134                 *pos++ = hex[val >> 4];
 135                 *pos = hex[val & 0xf];
 136         }
 137 }
 138
 139 /*
 140  * NOTE! This returns a statically allocated buffer, so you have to be
 141  * careful about using it. Do a "strdup()" if you need to save the
 142  * filename.
 143  *
 144  * Also note that this returns the location for creating.  Reading
 145  * SHA1 file can happen from any alternate directory listed in the
 146  * DB_ENVIRONMENT environment variable if it is not found in
 147  * the primary object database.
 148  */
 149 char *sha1_file_name(const unsigned char *sha1)
 150 {
 151         static char *name, *base;
 152
 153         if (!base) {
 154                 const char *sha1_file_directory = get_object_directory();
 155                 int len = strlen(sha1_file_directory);
 156                 base = xmalloc(len + 60);
 157                 memcpy(base, sha1_file_directory, len);
 158                 memset(base+len, 0, 60);
 159                 base[len] = '/';
 160                 base[len+3] = '/';
 161                 name = base + len + 1;
 162         }
 163         fill_sha1_path(name, sha1);
 164         return base;
 165 }
 166
 167 char *sha1_pack_name(const unsigned char *sha1)
 168 {
 169         static const char hex[] = "0123456789abcdef";
 170         static char *name, *base, *buf;
 171         int i;
 172
 173         if (!base) {
 174                 const char *sha1_file_directory = get_object_directory();
 175                 int len = strlen(sha1_file_directory);
 176                 base = xmalloc(len + 60);
 177                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 178                 name = base + len + 11;
 179         }
 180
 181         buf = name;
 182
 183         for (i = 0; i < 20; i++) {
 184                 unsigned int val = *sha1++;
 185                 *buf++ = hex[val >> 4];
 186                 *buf++ = hex[val & 0xf];
 187         }
 188
 189         return base;
 190 }
 191
 192 char *sha1_pack_index_name(const unsigned char *sha1)
 193 {
 194         static const char hex[] = "0123456789abcdef";
 195         static char *name, *base, *buf;
 196         int i;
 197
 198         if (!base) {
 199                 const char *sha1_file_directory = get_object_directory();
 200                 int len = strlen(sha1_file_directory);
 201                 base = xmalloc(len + 60);
 202                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 203                 name = base + len + 11;
 204         }
 205
 206         buf = name;
 207
 208         for (i = 0; i < 20; i++) {
 209                 unsigned int val = *sha1++;
 210                 *buf++ = hex[val >> 4];
 211                 *buf++ = hex[val & 0xf];
 212         }
 213
 214         return base;
 215 }
 216
 217 struct alternate_object_database *alt_odb_list;
 218 static struct alternate_object_database **alt_odb_tail;
 219
 220 static void read_info_alternates(const char * alternates, int depth);
 221
 222 /*
 223  * Prepare alternate object database registry.
 224  *
 225  * The variable alt_odb_list points at the list of struct
 226  * alternate_object_database.  The elements on this list come from
 227  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 228  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 229  * whose contents is similar to that environment variable but can be
 230  * LF separated.  Its base points at a statically allocated buffer that
 231  * contains "/the/directory/corresponding/to/.git/objects/...", while
 232  * its name points just after the slash at the end of ".git/objects/"
 233  * in the example above, and has enough space to hold 40-byte hex
 234  * SHA1, an extra slash for the first level indirection, and the
 235  * terminating NUL.
 236  */
 237 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 238 {
 239         struct stat st;
 240         const char *objdir = get_object_directory();
 241         struct alternate_object_database *ent;
 242         struct alternate_object_database *alt;
 243         /* 43 = 40-byte + 2 '/' + terminating NUL */
 244         int pfxlen = len;
 245         int entlen = pfxlen + 43;
 246         int base_len = -1;
 247
 248         if (*entry != '/' && relative_base) {
 249                 /* Relative alt-odb */
 250                 if (base_len < 0)
 251                         base_len = strlen(relative_base) + 1;
 252                 entlen += base_len;
 253                 pfxlen += base_len;
 254         }
 255         ent = xmalloc(sizeof(*ent) + entlen);
 256
 257         if (*entry != '/' && relative_base) {
 258                 memcpy(ent->base, relative_base, base_len - 1);
 259                 ent->base[base_len - 1] = '/';
 260                 memcpy(ent->base + base_len, entry, len);
 261         }
 262         else
 263                 memcpy(ent->base, entry, pfxlen);
 264
 265         ent->name = ent->base + pfxlen + 1;
 266         ent->base[pfxlen + 3] = '/';
 267         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 268
 269         /* Detect cases where alternate disappeared */
 270         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 271                 error("object directory %s does not exist; "
 272                       "check .git/objects/info/alternates.",
 273                       ent->base);
 274                 free(ent);
 275                 return -1;
 276         }
 277
 278         /* Prevent the common mistake of listing the same
 279          * thing twice, or object directory itself.
 280          */
 281         for (alt = alt_odb_list; alt; alt = alt->next) {
 282                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 283                         free(ent);
 284                         return -1;
 285                 }
 286         }
 287         if (!memcmp(ent->base, objdir, pfxlen)) {
 288                 free(ent);
 289                 return -1;
 290         }
 291
 292         /* add the alternate entry */
 293         *alt_odb_tail = ent;
 294         alt_odb_tail = &(ent->next);
 295         ent->next = NULL;
 296
 297         /* recursively add alternates */
 298         read_info_alternates(ent->base, depth + 1);
 299
 300         ent->base[pfxlen] = '/';
 301
 302         return 0;
 303 }
 304
 305 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 306                                  const char *relative_base, int depth)
 307 {
 308         const char *cp, *last;
 309
 310         if (depth > 5) {
 311                 error("%s: ignoring alternate object stores, nesting too deep.",
 312                                 relative_base);
 313                 return;
 314         }
 315
 316         last = alt;
 317         while (last < ep) {
 318                 cp = last;
 319                 if (cp < ep && *cp == '#') {
 320                         while (cp < ep && *cp != sep)
 321                                 cp++;
 322                         last = cp + 1;
 323                         continue;
 324                 }
 325                 while (cp < ep && *cp != sep)
 326                         cp++;
 327                 if (last != cp) {
 328                         if ((*last != '/') && depth) {
 329                                 error("%s: ignoring relative alternate object store %s",
 330                                                 relative_base, last);
 331                         } else {
 332                                 link_alt_odb_entry(last, cp - last,
 333                                                 relative_base, depth);
 334                         }
 335                 }
 336                 while (cp < ep && *cp == sep)
 337                         cp++;
 338                 last = cp;
 339         }
 340 }
 341
 342 static void read_info_alternates(const char * relative_base, int depth)
 343 {
 344         char *map;
 345         struct stat st;
 346         char path[PATH_MAX];
 347         int fd;
 348
 349         sprintf(path, "%s/info/alternates", relative_base);
 350         fd = open(path, O_RDONLY);
 351         if (fd < 0)
 352                 return;
 353         if (fstat(fd, &st) || (st.st_size == 0)) {
 354                 close(fd);
 355                 return;
 356         }
 357         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 358         close(fd);
 359         if (map == MAP_FAILED)
 360                 return;
 361
 362         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 363
 364         munmap(map, st.st_size);
 365 }
 366
 367 void prepare_alt_odb(void)
 368 {
 369         char *alt;
 370
 371         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 372         if (!alt) alt = "";
 373
 374         if (alt_odb_tail)
 375                 return;
 376         alt_odb_tail = &alt_odb_list;
 377         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 378
 379         read_info_alternates(get_object_directory(), 0);
 380 }
 381
 382 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 383 {
 384         char *name = sha1_file_name(sha1);
 385         struct alternate_object_database *alt;
 386
 387         if (!stat(name, st))
 388                 return name;
 389         prepare_alt_odb();
 390         for (alt = alt_odb_list; alt; alt = alt->next) {
 391                 name = alt->name;
 392                 fill_sha1_path(name, sha1);
 393                 if (!stat(alt->base, st))
 394                         return alt->base;
 395         }
 396         return NULL;
 397 }
 398
 399 #define PACK_MAX_SZ (1<<26)
 400 static int pack_used_ctr;
 401 static unsigned long pack_mapped;
 402 struct packed_git *packed_git;
 403
 404 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 405                                 void **idx_map_)
 406 {
 407         void *idx_map;
 408         unsigned int *index;
 409         unsigned long idx_size;
 410         int nr, i;
 411         int fd = open(path, O_RDONLY);
 412         struct stat st;
 413         if (fd < 0)
 414                 return -1;
 415         if (fstat(fd, &st)) {
 416                 close(fd);
 417                 return -1;
 418         }
 419         idx_size = st.st_size;
 420         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 421         close(fd);
 422         if (idx_map == MAP_FAILED)
 423                 return -1;
 424
 425         index = idx_map;
 426         *idx_map_ = idx_map;
 427         *idx_size_ = idx_size;
 428
 429         /* check index map */
 430         if (idx_size < 4*256 + 20 + 20)
 431                 return error("index file too small");
 432         nr = 0;
 433         for (i = 0; i < 256; i++) {
 434                 unsigned int n = ntohl(index[i]);
 435                 if (n < nr)
 436                         return error("non-monotonic index");
 437                 nr = n;
 438         }
 439
 440         /*
 441          * Total size:
 442          *  - 256 index entries 4 bytes each
 443          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 444          *  - 20-byte SHA1 of the packfile
 445          *  - 20-byte SHA1 file checksum
 446          */
 447         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 448                 return error("wrong index file size");
 449
 450         return 0;
 451 }
 452
 453 static int unuse_one_packed_git(void)
 454 {
 455         struct packed_git *p, *lru = NULL;
 456
 457         for (p = packed_git; p; p = p->next) {
 458                 if (p->pack_use_cnt || !p->pack_base)
 459                         continue;
 460                 if (!lru || p->pack_last_used < lru->pack_last_used)
 461                         lru = p;
 462         }
 463         if (!lru)
 464                 return 0;
 465         munmap(lru->pack_base, lru->pack_size);
 466         lru->pack_base = NULL;
 467         return 1;
 468 }
 469
 470 void unuse_packed_git(struct packed_git *p)
 471 {
 472         p->pack_use_cnt--;
 473 }
 474
 475 int use_packed_git(struct packed_git *p)
 476 {
 477         if (!p->pack_size) {
 478                 struct stat st;
 479                 // We created the struct before we had the pack
 480                 stat(p->pack_name, &st);
 481                 if (!S_ISREG(st.st_mode))
 482                         die("packfile %s not a regular file", p->pack_name);
 483                 p->pack_size = st.st_size;
 484         }
 485         if (!p->pack_base) {
 486                 int fd;
 487                 struct stat st;
 488                 void *map;
 489
 490                 pack_mapped += p->pack_size;
 491                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 492                         ; /* nothing */
 493                 fd = open(p->pack_name, O_RDONLY);
 494                 if (fd < 0)
 495                         die("packfile %s cannot be opened", p->pack_name);
 496                 if (fstat(fd, &st)) {
 497                         close(fd);
 498                         die("packfile %s cannot be opened", p->pack_name);
 499                 }
 500                 if (st.st_size != p->pack_size)
 501                         die("packfile %s size mismatch.", p->pack_name);
 502                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 503                 close(fd);
 504                 if (map == MAP_FAILED)
 505                         die("packfile %s cannot be mapped.", p->pack_name);
 506                 p->pack_base = map;
 507
 508                 /* Check if the pack file matches with the index file.
 509                  * this is cheap.
 510                  */
 511                 if (memcmp((char*)(p->index_base) + p->index_size - 40,
 512                            p->pack_base + p->pack_size - 20, 20)) {
 513
 514                         die("packfile %s does not match index.", p->pack_name);
 515                 }
 516         }
 517         p->pack_last_used = pack_used_ctr++;
 518         p->pack_use_cnt++;
 519         return 0;
 520 }
 521
 522 struct packed_git *add_packed_git(char *path, int path_len, int local)
 523 {
 524         struct stat st;
 525         struct packed_git *p;
 526         unsigned long idx_size;
 527         void *idx_map;
 528         unsigned char sha1[20];
 529
 530         if (check_packed_git_idx(path, &idx_size, &idx_map))
 531                 return NULL;
 532
 533         /* do we have a corresponding .pack file? */
 534         strcpy(path + path_len - 4, ".pack");
 535         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 536                 munmap(idx_map, idx_size);
 537                 return NULL;
 538         }
 539         /* ok, it looks sane as far as we can check without
 540          * actually mapping the pack file.
 541          */
 542         p = xmalloc(sizeof(*p) + path_len + 2);
 543         strcpy(p->pack_name, path);
 544         p->index_size = idx_size;
 545         p->pack_size = st.st_size;
 546         p->index_base = idx_map;
 547         p->next = NULL;
 548         p->pack_base = NULL;
 549         p->pack_last_used = 0;
 550         p->pack_use_cnt = 0;
 551         p->pack_local = local;
 552         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 553                 memcpy(p->sha1, sha1, 20);
 554         return p;
 555 }
 556
 557 struct packed_git *parse_pack_index(unsigned char *sha1)
 558 {
 559         char *path = sha1_pack_index_name(sha1);
 560         return parse_pack_index_file(sha1, path);
 561 }
 562
 563 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 564 {
 565         struct packed_git *p;
 566         unsigned long idx_size;
 567         void *idx_map;
 568         char *path;
 569
 570         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 571                 return NULL;
 572
 573         path = sha1_pack_name(sha1);
 574
 575         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 576         strcpy(p->pack_name, path);
 577         p->index_size = idx_size;
 578         p->pack_size = 0;
 579         p->index_base = idx_map;
 580         p->next = NULL;
 581         p->pack_base = NULL;
 582         p->pack_last_used = 0;
 583         p->pack_use_cnt = 0;
 584         memcpy(p->sha1, sha1, 20);
 585         return p;
 586 }
 587
 588 void install_packed_git(struct packed_git *pack)
 589 {
 590         pack->next = packed_git;
 591         packed_git = pack;
 592 }
 593
 594 static void prepare_packed_git_one(char *objdir, int local)
 595 {
 596         char path[PATH_MAX];
 597         int len;
 598         DIR *dir;
 599         struct dirent *de;
 600
 601         sprintf(path, "%s/pack", objdir);
 602         len = strlen(path);
 603         dir = opendir(path);
 604         if (!dir) {
 605                 if (errno != ENOENT)
 606                         error("unable to open object pack directory: %s: %s",
 607                               path, strerror(errno));
 608                 return;
 609         }
 610         path[len++] = '/';
 611         while ((de = readdir(dir)) != NULL) {
 612                 int namelen = strlen(de->d_name);
 613                 struct packed_git *p;
 614
 615                 if (strcmp(de->d_name + namelen - 4, ".idx"))
 616                         continue;
 617
 618                 /* we have .idx.  Is it a file we can map? */
 619                 strcpy(path + len, de->d_name);
 620                 p = add_packed_git(path, len + namelen, local);
 621                 if (!p)
 622                         continue;
 623                 p->next = packed_git;
 624                 packed_git = p;
 625         }
 626         closedir(dir);
 627 }
 628
 629 void prepare_packed_git(void)
 630 {
 631         static int run_once = 0;
 632         struct alternate_object_database *alt;
 633
 634         if (run_once)
 635                 return;
 636         prepare_packed_git_one(get_object_directory(), 1);
 637         prepare_alt_odb();
 638         for (alt = alt_odb_list; alt; alt = alt->next) {
 639                 alt->name[-1] = 0;
 640                 prepare_packed_git_one(alt->base, 0);
 641                 alt->name[-1] = '/';
 642         }
 643         run_once = 1;
 644 }
 645
 646 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 647 {
 648         char header[100];
 649         unsigned char real_sha1[20];
 650         SHA_CTX c;
 651
 652         SHA1_Init(&c);
 653         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 654         SHA1_Update(&c, map, size);
 655         SHA1_Final(real_sha1, &c);
 656         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 657 }
 658
 659 static void *map_sha1_file_internal(const unsigned char *sha1,
 660                                     unsigned long *size)
 661 {
 662         struct stat st;
 663         void *map;
 664         int fd;
 665         char *filename = find_sha1_file(sha1, &st);
 666
 667         if (!filename) {
 668                 return NULL;
 669         }
 670
 671         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 672         if (fd < 0) {
 673                 /* See if it works without O_NOATIME */
 674                 switch (sha1_file_open_flag) {
 675                 default:
 676                         fd = open(filename, O_RDONLY);
 677                         if (fd >= 0)
 678                                 break;
 679                 /* Fallthrough */
 680                 case 0:
 681                         return NULL;
 682                 }
 683
 684                 /* If it failed once, it will probably fail again.
 685                  * Stop using O_NOATIME
 686                  */
 687                 sha1_file_open_flag = 0;
 688         }
 689         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 690         close(fd);
 691         if (map == MAP_FAILED)
 692                 return NULL;
 693         *size = st.st_size;
 694         return map;
 695 }
 696
 697 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 698 {
 699         /* Get the data stream */
 700         memset(stream, 0, sizeof(*stream));
 701         stream->next_in = map;
 702         stream->avail_in = mapsize;
 703         stream->next_out = buffer;
 704         stream->avail_out = size;
 705
 706         inflateInit(stream);
 707         return inflate(stream, 0);
 708 }
 709
 710 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 711 {
 712         int bytes = strlen(buffer) + 1;
 713         unsigned char *buf = xmalloc(1+size);
 714
 715         memcpy(buf, buffer + bytes, stream->total_out - bytes);
 716         bytes = stream->total_out - bytes;
 717         if (bytes < size) {
 718                 stream->next_out = buf + bytes;
 719                 stream->avail_out = size - bytes;
 720                 while (inflate(stream, Z_FINISH) == Z_OK)
 721                         /* nothing */;
 722         }
 723         buf[size] = 0;
 724         inflateEnd(stream);
 725         return buf;
 726 }
 727
 728 /*
 729  * We used to just use "sscanf()", but that's actually way
 730  * too permissive for what we want to check. So do an anal
 731  * object header parse by hand.
 732  */
 733 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 734 {
 735         int i;
 736         unsigned long size;
 737
 738         /*
 739          * The type can be at most ten bytes (including the
 740          * terminating '\0' that we add), and is followed by
 741          * a space.
 742          */
 743         i = 10;
 744         for (;;) {
 745                 char c = *hdr++;
 746                 if (c == ' ')
 747                         break;
 748                 if (!--i)
 749                         return -1;
 750                 *type++ = c;
 751         }
 752         *type = 0;
 753
 754         /*
 755          * The length must follow immediately, and be in canonical
 756          * decimal format (ie "010" is not valid).
 757          */
 758         size = *hdr++ - '0';
 759         if (size > 9)
 760                 return -1;
 761         if (size) {
 762                 for (;;) {
 763                         unsigned long c = *hdr - '0';
 764                         if (c > 9)
 765                                 break;
 766                         hdr++;
 767                         size = size * 10 + c;
 768                 }
 769         }
 770         *sizep = size;
 771
 772         /*
 773          * The length must be followed by a zero byte
 774          */
 775         return *hdr ? -1 : 0;
 776 }
 777
 778 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 779 {
 780         int ret;
 781         z_stream stream;
 782         char hdr[8192];
 783
 784         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 785         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 786                 return NULL;
 787
 788         return unpack_sha1_rest(&stream, hdr, *size);
 789 }
 790
 791 /* forward declaration for a mutually recursive function */
 792 static int packed_object_info(struct pack_entry *entry,
 793                               char *type, unsigned long *sizep);
 794
 795 static int packed_delta_info(unsigned char *base_sha1,
 796                              unsigned long delta_size,
 797                              unsigned long left,
 798                              char *type,
 799                              unsigned long *sizep,
 800                              struct packed_git *p)
 801 {
 802         struct pack_entry base_ent;
 803
 804         if (left < 20)
 805                 die("truncated pack file");
 806
 807         /* The base entry _must_ be in the same pack */
 808         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 809                 die("failed to find delta-pack base object %s",
 810                     sha1_to_hex(base_sha1));
 811
 812         /* We choose to only get the type of the base object and
 813          * ignore potentially corrupt pack file that expects the delta
 814          * based on a base with a wrong size.  This saves tons of
 815          * inflate() calls.
 816          */
 817
 818         if (packed_object_info(&base_ent, type, NULL))
 819                 die("cannot get info for delta-pack base");
 820
 821         if (sizep) {
 822                 const unsigned char *data;
 823                 unsigned char delta_head[64];
 824                 unsigned long result_size;
 825                 z_stream stream;
 826                 int st;
 827
 828                 memset(&stream, 0, sizeof(stream));
 829
 830                 data = stream.next_in = base_sha1 + 20;
 831                 stream.avail_in = left - 20;
 832                 stream.next_out = delta_head;
 833                 stream.avail_out = sizeof(delta_head);
 834
 835                 inflateInit(&stream);
 836                 st = inflate(&stream, Z_FINISH);
 837                 inflateEnd(&stream);
 838                 if ((st != Z_STREAM_END) &&
 839                     stream.total_out != sizeof(delta_head))
 840                         die("delta data unpack-initial failed");
 841
 842                 /* Examine the initial part of the delta to figure out
 843                  * the result size.
 844                  */
 845                 data = delta_head;
 846
 847                 /* ignore base size */
 848                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 849
 850                 /* Read the result size */
 851                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 852                 *sizep = result_size;
 853         }
 854         return 0;
 855 }
 856
 857 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 858         enum object_type *type, unsigned long *sizep)
 859 {
 860         unsigned shift;
 861         unsigned char *pack, c;
 862         unsigned long size;
 863
 864         if (offset >= p->pack_size)
 865                 die("object offset outside of pack file");
 866
 867         pack =  p->pack_base + offset;
 868         c = *pack++;
 869         offset++;
 870         *type = (c >> 4) & 7;
 871         size = c & 15;
 872         shift = 4;
 873         while (c & 0x80) {
 874                 if (offset >= p->pack_size)
 875                         die("object offset outside of pack file");
 876                 c = *pack++;
 877                 offset++;
 878                 size += (c & 0x7f) << shift;
 879                 shift += 7;
 880         }
 881         *sizep = size;
 882         return offset;
 883 }
 884
 885 int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
 886                            unsigned char *base, unsigned long *sizep,
 887                            enum object_type *kindp)
 888 {
 889         unsigned long ptr;
 890         int status = -1;
 891
 892         use_packed_git(p);
 893         ptr = offset;
 894         ptr = unpack_object_header(p, ptr, kindp, sizep);
 895         if (*kindp != OBJ_DELTA)
 896                 goto done;
 897         memcpy(base, p->pack_base + ptr, 20);
 898         status = 0;
 899  done:
 900         unuse_packed_git(p);
 901         return status;
 902 }
 903
 904 void packed_object_info_detail(struct pack_entry *e,
 905                                char *type,
 906                                unsigned long *size,
 907                                unsigned long *store_size,
 908                                unsigned int *delta_chain_length,
 909                                unsigned char *base_sha1)
 910 {
 911         struct packed_git *p = e->p;
 912         unsigned long offset;
 913         unsigned char *pack;
 914         enum object_type kind;
 915
 916         offset = unpack_object_header(p, e->offset, &kind, size);
 917         pack = p->pack_base + offset;
 918         if (kind != OBJ_DELTA)
 919                 *delta_chain_length = 0;
 920         else {
 921                 unsigned int chain_length = 0;
 922                 if (p->pack_size <= offset + 20)
 923                         die("pack file %s records an incomplete delta base",
 924                             p->pack_name);
 925                 memcpy(base_sha1, pack, 20);
 926                 do {
 927                         struct pack_entry base_ent;
 928                         unsigned long junk;
 929
 930                         find_pack_entry_one(pack, &base_ent, p);
 931                         offset = unpack_object_header(p, base_ent.offset,
 932                                                       &kind, &junk);
 933                         pack = p->pack_base + offset;
 934                         chain_length++;
 935                 } while (kind == OBJ_DELTA);
 936                 *delta_chain_length = chain_length;
 937         }
 938         switch (kind) {
 939         case OBJ_COMMIT:
 940                 strcpy(type, commit_type);
 941                 break;
 942         case OBJ_TREE:
 943                 strcpy(type, tree_type);
 944                 break;
 945         case OBJ_BLOB:
 946                 strcpy(type, blob_type);
 947                 break;
 948         case OBJ_TAG:
 949                 strcpy(type, tag_type);
 950                 break;
 951         default:
 952                 die("corrupted pack file %s containing object of kind %d",
 953                     p->pack_name, kind);
 954         }
 955         *store_size = 0; /* notyet */
 956 }
 957
 958 static int packed_object_info(struct pack_entry *entry,
 959                               char *type, unsigned long *sizep)
 960 {
 961         struct packed_git *p = entry->p;
 962         unsigned long offset, size, left;
 963         unsigned char *pack;
 964         enum object_type kind;
 965         int retval;
 966
 967         if (use_packed_git(p))
 968                 die("cannot map packed file");
 969
 970         offset = unpack_object_header(p, entry->offset, &kind, &size);
 971         pack = p->pack_base + offset;
 972         left = p->pack_size - offset;
 973
 974         switch (kind) {
 975         case OBJ_DELTA:
 976                 retval = packed_delta_info(pack, size, left, type, sizep, p);
 977                 unuse_packed_git(p);
 978                 return retval;
 979         case OBJ_COMMIT:
 980                 strcpy(type, commit_type);
 981                 break;
 982         case OBJ_TREE:
 983                 strcpy(type, tree_type);
 984                 break;
 985         case OBJ_BLOB:
 986                 strcpy(type, blob_type);
 987                 break;
 988         case OBJ_TAG:
 989                 strcpy(type, tag_type);
 990                 break;
 991         default:
 992                 die("corrupted pack file %s containing object of kind %d",
 993                     p->pack_name, kind);
 994         }
 995         if (sizep)
 996                 *sizep = size;
 997         unuse_packed_git(p);
 998         return 0;
 999 }
1000
1001 /* forward declaration for a mutually recursive function */
1002 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
1003
1004 static void *unpack_delta_entry(unsigned char *base_sha1,
1005                                 unsigned long delta_size,
1006                                 unsigned long left,
1007                                 char *type,
1008                                 unsigned long *sizep,
1009                                 struct packed_git *p)
1010 {
1011         struct pack_entry base_ent;
1012         void *data, *delta_data, *result, *base;
1013         unsigned long data_size, result_size, base_size;
1014         z_stream stream;
1015         int st;
1016
1017         if (left < 20)
1018                 die("truncated pack file");
1019
1020         /* The base entry _must_ be in the same pack */
1021         if (!find_pack_entry_one(base_sha1, &base_ent, p))
1022                 die("failed to find delta-pack base object %s",
1023                     sha1_to_hex(base_sha1));
1024         base = unpack_entry_gently(&base_ent, type, &base_size);
1025         if (!base)
1026                 die("failed to read delta-pack base object %s",
1027                     sha1_to_hex(base_sha1));
1028
1029         data = base_sha1 + 20;
1030         data_size = left - 20;
1031         delta_data = xmalloc(delta_size);
1032
1033         memset(&stream, 0, sizeof(stream));
1034
1035         stream.next_in = data;
1036         stream.avail_in = data_size;
1037         stream.next_out = delta_data;
1038         stream.avail_out = delta_size;
1039
1040         inflateInit(&stream);
1041         st = inflate(&stream, Z_FINISH);
1042         inflateEnd(&stream);
1043         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
1044                 die("delta data unpack failed");
1045
1046         result = patch_delta(base, base_size,
1047                              delta_data, delta_size,
1048                              &result_size);
1049         if (!result)
1050                 die("failed to apply delta");
1051         free(delta_data);
1052         free(base);
1053         *sizep = result_size;
1054         return result;
1055 }
1056
1057 static void *unpack_non_delta_entry(unsigned char *data,
1058                                     unsigned long size,
1059                                     unsigned long left)
1060 {
1061         int st;
1062         z_stream stream;
1063         unsigned char *buffer;
1064
1065         buffer = xmalloc(size + 1);
1066         buffer[size] = 0;
1067         memset(&stream, 0, sizeof(stream));
1068         stream.next_in = data;
1069         stream.avail_in = left;
1070         stream.next_out = buffer;
1071         stream.avail_out = size;
1072
1073         inflateInit(&stream);
1074         st = inflate(&stream, Z_FINISH);
1075         inflateEnd(&stream);
1076         if ((st != Z_STREAM_END) || stream.total_out != size) {
1077                 free(buffer);
1078                 return NULL;
1079         }
1080
1081         return buffer;
1082 }
1083
1084 static void *unpack_entry(struct pack_entry *entry,
1085                           char *type, unsigned long *sizep)
1086 {
1087         struct packed_git *p = entry->p;
1088         void *retval;
1089
1090         if (use_packed_git(p))
1091                 die("cannot map packed file");
1092         retval = unpack_entry_gently(entry, type, sizep);
1093         unuse_packed_git(p);
1094         if (!retval)
1095                 die("corrupted pack file %s", p->pack_name);
1096         return retval;
1097 }
1098
1099 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
1100 void *unpack_entry_gently(struct pack_entry *entry,
1101                           char *type, unsigned long *sizep)
1102 {
1103         struct packed_git *p = entry->p;
1104         unsigned long offset, size, left;
1105         unsigned char *pack;
1106         enum object_type kind;
1107         void *retval;
1108
1109         offset = unpack_object_header(p, entry->offset, &kind, &size);
1110         pack = p->pack_base + offset;
1111         left = p->pack_size - offset;
1112         switch (kind) {
1113         case OBJ_DELTA:
1114                 retval = unpack_delta_entry(pack, size, left, type, sizep, p);
1115                 return retval;
1116         case OBJ_COMMIT:
1117                 strcpy(type, commit_type);
1118                 break;
1119         case OBJ_TREE:
1120                 strcpy(type, tree_type);
1121                 break;
1122         case OBJ_BLOB:
1123                 strcpy(type, blob_type);
1124                 break;
1125         case OBJ_TAG:
1126                 strcpy(type, tag_type);
1127                 break;
1128         default:
1129                 return NULL;
1130         }
1131         *sizep = size;
1132         retval = unpack_non_delta_entry(pack, size, left);
1133         return retval;
1134 }
1135
1136 int num_packed_objects(const struct packed_git *p)
1137 {
1138         /* See check_packed_git_idx() */
1139         return (p->index_size - 20 - 20 - 4*256) / 24;
1140 }
1141
1142 int nth_packed_object_sha1(const struct packed_git *p, int n,
1143                            unsigned char* sha1)
1144 {
1145         void *index = p->index_base + 256;
1146         if (n < 0 || num_packed_objects(p) <= n)
1147                 return -1;
1148         memcpy(sha1, (index + 24 * n + 4), 20);
1149         return 0;
1150 }
1151
1152 int find_pack_entry_one(const unsigned char *sha1,
1153                         struct pack_entry *e, struct packed_git *p)
1154 {
1155         unsigned int *level1_ofs = p->index_base;
1156         int hi = ntohl(level1_ofs[*sha1]);
1157         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1158         void *index = p->index_base + 256;
1159
1160         do {
1161                 int mi = (lo + hi) / 2;
1162                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1163                 if (!cmp) {
1164                         e->offset = ntohl(*((unsigned int *)(index + 24 * mi)));
1165                         memcpy(e->sha1, sha1, 20);
1166                         e->p = p;
1167                         return 1;
1168                 }
1169                 if (cmp > 0)
1170                         hi = mi;
1171                 else
1172                         lo = mi+1;
1173         } while (lo < hi);
1174         return 0;
1175 }
1176
1177 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1178 {
1179         struct packed_git *p;
1180         prepare_packed_git();
1181
1182         for (p = packed_git; p; p = p->next) {
1183                 if (find_pack_entry_one(sha1, e, p))
1184                         return 1;
1185         }
1186         return 0;
1187 }
1188
1189 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1190                                   struct packed_git *packs)
1191 {
1192         struct packed_git *p;
1193         struct pack_entry e;
1194
1195         for (p = packs; p; p = p->next) {
1196                 if (find_pack_entry_one(sha1, &e, p))
1197                         return p;
1198         }
1199         return NULL;
1200
1201 }
1202
1203 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1204 {
1205         int status;
1206         unsigned long mapsize, size;
1207         void *map;
1208         z_stream stream;
1209         char hdr[128];
1210
1211         map = map_sha1_file_internal(sha1, &mapsize);
1212         if (!map) {
1213                 struct pack_entry e;
1214
1215                 if (!find_pack_entry(sha1, &e))
1216                         return error("unable to find %s", sha1_to_hex(sha1));
1217                 return packed_object_info(&e, type, sizep);
1218         }
1219         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1220                 status = error("unable to unpack %s header",
1221                                sha1_to_hex(sha1));
1222         if (parse_sha1_header(hdr, type, &size) < 0)
1223                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1224         else {
1225                 status = 0;
1226                 if (sizep)
1227                         *sizep = size;
1228         }
1229         inflateEnd(&stream);
1230         munmap(map, mapsize);
1231         return status;
1232 }
1233
1234 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1235 {
1236         struct pack_entry e;
1237
1238         if (!find_pack_entry(sha1, &e)) {
1239                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1240                 return NULL;
1241         }
1242         return unpack_entry(&e, type, size);
1243 }
1244
1245 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1246 {
1247         unsigned long mapsize;
1248         void *map, *buf;
1249         struct pack_entry e;
1250
1251         if (find_pack_entry(sha1, &e))
1252                 return read_packed_sha1(sha1, type, size);
1253         map = map_sha1_file_internal(sha1, &mapsize);
1254         if (map) {
1255                 buf = unpack_sha1_file(map, mapsize, type, size);
1256                 munmap(map, mapsize);
1257                 return buf;
1258         }
1259         return NULL;
1260 }
1261
1262 void *read_object_with_reference(const unsigned char *sha1,
1263                                  const char *required_type,
1264                                  unsigned long *size,
1265                                  unsigned char *actual_sha1_return)
1266 {
1267         char type[20];
1268         void *buffer;
1269         unsigned long isize;
1270         unsigned char actual_sha1[20];
1271
1272         memcpy(actual_sha1, sha1, 20);
1273         while (1) {
1274                 int ref_length = -1;
1275                 const char *ref_type = NULL;
1276
1277                 buffer = read_sha1_file(actual_sha1, type, &isize);
1278                 if (!buffer)
1279                         return NULL;
1280                 if (!strcmp(type, required_type)) {
1281                         *size = isize;
1282                         if (actual_sha1_return)
1283                                 memcpy(actual_sha1_return, actual_sha1, 20);
1284                         return buffer;
1285                 }
1286                 /* Handle references */
1287                 else if (!strcmp(type, commit_type))
1288                         ref_type = "tree ";
1289                 else if (!strcmp(type, tag_type))
1290                         ref_type = "object ";
1291                 else {
1292                         free(buffer);
1293                         return NULL;
1294                 }
1295                 ref_length = strlen(ref_type);
1296
1297                 if (memcmp(buffer, ref_type, ref_length) ||
1298                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
1299                         free(buffer);
1300                         return NULL;
1301                 }
1302                 free(buffer);
1303                 /* Now we have the ID of the referred-to object in
1304                  * actual_sha1.  Check again. */
1305         }
1306 }
1307
1308 char *write_sha1_file_prepare(void *buf,
1309                               unsigned long len,
1310                               const char *type,
1311                               unsigned char *sha1,
1312                               unsigned char *hdr,
1313                               int *hdrlen)
1314 {
1315         SHA_CTX c;
1316
1317         /* Generate the header */
1318         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1319
1320         /* Sha1.. */
1321         SHA1_Init(&c);
1322         SHA1_Update(&c, hdr, *hdrlen);
1323         SHA1_Update(&c, buf, len);
1324         SHA1_Final(sha1, &c);
1325
1326         return sha1_file_name(sha1);
1327 }
1328
1329 /*
1330  * Link the tempfile to the final place, possibly creating the
1331  * last directory level as you do so.
1332  *
1333  * Returns the errno on failure, 0 on success.
1334  */
1335 static int link_temp_to_file(const char *tmpfile, char *filename)
1336 {
1337         int ret;
1338
1339         if (!link(tmpfile, filename))
1340                 return 0;
1341
1342         /*
1343          * Try to mkdir the last path component if that failed
1344          * with an ENOENT.
1345          *
1346          * Re-try the "link()" regardless of whether the mkdir
1347          * succeeds, since a race might mean that somebody
1348          * else succeeded.
1349          */
1350         ret = errno;
1351         if (ret == ENOENT) {
1352                 char *dir = strrchr(filename, '/');
1353                 if (dir) {
1354                         *dir = 0;
1355                         mkdir(filename, 0777);
1356                         if (adjust_shared_perm(filename))
1357                                 return -2;
1358                         *dir = '/';
1359                         if (!link(tmpfile, filename))
1360                                 return 0;
1361                         ret = errno;
1362                 }
1363         }
1364         return ret;
1365 }
1366
1367 /*
1368  * Move the just written object into its final resting place
1369  */
1370 int move_temp_to_file(const char *tmpfile, char *filename)
1371 {
1372         int ret = link_temp_to_file(tmpfile, filename);
1373
1374         /*
1375          * Coda hack - coda doesn't like cross-directory links,
1376          * so we fall back to a rename, which will mean that it
1377          * won't be able to check collisions, but that's not a
1378          * big deal.
1379          *
1380          * The same holds for FAT formatted media.
1381          *
1382          * When this succeeds, we just return 0. We have nothing
1383          * left to unlink.
1384          */
1385         if (ret && ret != EEXIST) {
1386                 if (!rename(tmpfile, filename))
1387                         return 0;
1388                 ret = errno;
1389         }
1390         unlink(tmpfile);
1391         if (ret) {
1392                 if (ret != EEXIST) {
1393                         fprintf(stderr, "unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1394                         return -1;
1395                 }
1396                 /* FIXME!!! Collision check here ? */
1397         }
1398
1399         return 0;
1400 }
1401
1402 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1403 {
1404         int size;
1405         unsigned char *compressed;
1406         z_stream stream;
1407         unsigned char sha1[20];
1408         char *filename;
1409         static char tmpfile[PATH_MAX];
1410         unsigned char hdr[50];
1411         int fd, hdrlen;
1412
1413         /* Normally if we have it in the pack then we do not bother writing
1414          * it out into .git/objects/??/?{38} file.
1415          */
1416         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1417         if (returnsha1)
1418                 memcpy(returnsha1, sha1, 20);
1419         if (has_sha1_file(sha1))
1420                 return 0;
1421         fd = open(filename, O_RDONLY);
1422         if (fd >= 0) {
1423                 /*
1424                  * FIXME!!! We might do collision checking here, but we'd
1425                  * need to uncompress the old file and check it. Later.
1426                  */
1427                 close(fd);
1428                 return 0;
1429         }
1430
1431         if (errno != ENOENT) {
1432                 fprintf(stderr, "sha1 file %s: %s\n", filename, strerror(errno));
1433                 return -1;
1434         }
1435
1436         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1437
1438         fd = mkstemp(tmpfile);
1439         if (fd < 0) {
1440                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1441                 return -1;
1442         }
1443
1444         /* Set it up */
1445         memset(&stream, 0, sizeof(stream));
1446         deflateInit(&stream, Z_BEST_COMPRESSION);
1447         size = deflateBound(&stream, len+hdrlen);
1448         compressed = xmalloc(size);
1449
1450         /* Compress it */
1451         stream.next_out = compressed;
1452         stream.avail_out = size;
1453
1454         /* First header.. */
1455         stream.next_in = hdr;
1456         stream.avail_in = hdrlen;
1457         while (deflate(&stream, 0) == Z_OK)
1458                 /* nothing */;
1459
1460         /* Then the data itself.. */
1461         stream.next_in = buf;
1462         stream.avail_in = len;
1463         while (deflate(&stream, Z_FINISH) == Z_OK)
1464                 /* nothing */;
1465         deflateEnd(&stream);
1466         size = stream.total_out;
1467
1468         if (write(fd, compressed, size) != size)
1469                 die("unable to write file");
1470         fchmod(fd, 0444);
1471         close(fd);
1472         free(compressed);
1473
1474         return move_temp_to_file(tmpfile, filename);
1475 }
1476
1477 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1478 {
1479         ssize_t size;
1480         unsigned long objsize;
1481         int posn = 0;
1482         void *map = map_sha1_file_internal(sha1, &objsize);
1483         void *buf = map;
1484         void *temp_obj = NULL;
1485         z_stream stream;
1486
1487         if (!buf) {
1488                 unsigned char *unpacked;
1489                 unsigned long len;
1490                 char type[20];
1491                 char hdr[50];
1492                 int hdrlen;
1493                 // need to unpack and recompress it by itself
1494                 unpacked = read_packed_sha1(sha1, type, &len);
1495
1496                 hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1497
1498                 /* Set it up */
1499                 memset(&stream, 0, sizeof(stream));
1500                 deflateInit(&stream, Z_BEST_COMPRESSION);
1501                 size = deflateBound(&stream, len + hdrlen);
1502                 temp_obj = buf = xmalloc(size);
1503
1504                 /* Compress it */
1505                 stream.next_out = buf;
1506                 stream.avail_out = size;
1507
1508                 /* First header.. */
1509                 stream.next_in = (void *)hdr;
1510                 stream.avail_in = hdrlen;
1511                 while (deflate(&stream, 0) == Z_OK)
1512                         /* nothing */;
1513
1514                 /* Then the data itself.. */
1515                 stream.next_in = unpacked;
1516                 stream.avail_in = len;
1517                 while (deflate(&stream, Z_FINISH) == Z_OK)
1518                         /* nothing */;
1519                 deflateEnd(&stream);
1520                 free(unpacked);
1521
1522                 objsize = stream.total_out;
1523         }
1524
1525         do {
1526                 size = write(fd, buf + posn, objsize - posn);
1527                 if (size <= 0) {
1528                         if (!size) {
1529                                 fprintf(stderr, "write closed\n");
1530                         } else {
1531                                 perror("write ");
1532                         }
1533                         return -1;
1534                 }
1535                 posn += size;
1536         } while (posn < objsize);
1537
1538         if (map)
1539                 munmap(map, objsize);
1540         if (temp_obj)
1541                 free(temp_obj);
1542
1543         return 0;
1544 }
1545
1546 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1547                        size_t bufsize, size_t *bufposn)
1548 {
1549         char tmpfile[PATH_MAX];
1550         int local;
1551         z_stream stream;
1552         unsigned char real_sha1[20];
1553         unsigned char discard[4096];
1554         int ret;
1555         SHA_CTX c;
1556
1557         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1558
1559         local = mkstemp(tmpfile);
1560         if (local < 0)
1561                 return error("Couldn't open %s for %s",
1562                              tmpfile, sha1_to_hex(sha1));
1563
1564         memset(&stream, 0, sizeof(stream));
1565
1566         inflateInit(&stream);
1567
1568         SHA1_Init(&c);
1569
1570         do {
1571                 ssize_t size;
1572                 if (*bufposn) {
1573                         stream.avail_in = *bufposn;
1574                         stream.next_in = (unsigned char *) buffer;
1575                         do {
1576                                 stream.next_out = discard;
1577                                 stream.avail_out = sizeof(discard);
1578                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1579                                 SHA1_Update(&c, discard, sizeof(discard) -
1580                                             stream.avail_out);
1581                         } while (stream.avail_in && ret == Z_OK);
1582                         write(local, buffer, *bufposn - stream.avail_in);
1583                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1584                                 stream.avail_in);
1585                         *bufposn = stream.avail_in;
1586                         if (ret != Z_OK)
1587                                 break;
1588                 }
1589                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1590                 if (size <= 0) {
1591                         close(local);
1592                         unlink(tmpfile);
1593                         if (!size)
1594                                 return error("Connection closed?");
1595                         perror("Reading from connection");
1596                         return -1;
1597                 }
1598                 *bufposn += size;
1599         } while (1);
1600         inflateEnd(&stream);
1601
1602         close(local);
1603         SHA1_Final(real_sha1, &c);
1604         if (ret != Z_STREAM_END) {
1605                 unlink(tmpfile);
1606                 return error("File %s corrupted", sha1_to_hex(sha1));
1607         }
1608         if (memcmp(sha1, real_sha1, 20)) {
1609                 unlink(tmpfile);
1610                 return error("File %s has bad hash", sha1_to_hex(sha1));
1611         }
1612
1613         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1614 }
1615
1616 int has_pack_index(const unsigned char *sha1)
1617 {
1618         struct stat st;
1619         if (stat(sha1_pack_index_name(sha1), &st))
1620                 return 0;
1621         return 1;
1622 }
1623
1624 int has_pack_file(const unsigned char *sha1)
1625 {
1626         struct stat st;
1627         if (stat(sha1_pack_name(sha1), &st))
1628                 return 0;
1629         return 1;
1630 }
1631
1632 int has_sha1_pack(const unsigned char *sha1)
1633 {
1634         struct pack_entry e;
1635         return find_pack_entry(sha1, &e);
1636 }
1637
1638 int has_sha1_file(const unsigned char *sha1)
1639 {
1640         struct stat st;
1641         struct pack_entry e;
1642
1643         if (find_pack_entry(sha1, &e))
1644                 return 1;
1645         return find_sha1_file(sha1, &st) ? 1 : 0;
1646 }
1647
1648 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1649 {
1650         unsigned long size = 4096;
1651         char *buf = malloc(size);
1652         int iret, ret;
1653         unsigned long off = 0;
1654         unsigned char hdr[50];
1655         int hdrlen;
1656         do {
1657                 iret = read(fd, buf + off, size - off);
1658                 if (iret > 0) {
1659                         off += iret;
1660                         if (off == size) {
1661                                 size *= 2;
1662                                 buf = realloc(buf, size);
1663                         }
1664                 }
1665         } while (iret > 0);
1666         if (iret < 0) {
1667                 free(buf);
1668                 return -1;
1669         }
1670         if (!type)
1671                 type = blob_type;
1672         if (write_object)
1673                 ret = write_sha1_file(buf, off, type, sha1);
1674         else {
1675                 write_sha1_file_prepare(buf, off, type, sha1, hdr, &hdrlen);
1676                 ret = 0;
1677         }
1678         free(buf);
1679         return ret;
1680 }
1681
1682 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1683 {
1684         unsigned long size = st->st_size;
1685         void *buf;
1686         int ret;
1687         unsigned char hdr[50];
1688         int hdrlen;
1689
1690         buf = "";
1691         if (size)
1692                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1693         close(fd);
1694         if (buf == MAP_FAILED)
1695                 return -1;
1696
1697         if (!type)
1698                 type = blob_type;
1699         if (write_object)
1700                 ret = write_sha1_file(buf, size, type, sha1);
1701         else {
1702                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1703                 ret = 0;
1704         }
1705         if (size)
1706                 munmap(buf, size);
1707         return ret;
1708 }
1709
1710 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1711 {
1712         int fd;
1713         char *target;
1714
1715         switch (st->st_mode & S_IFMT) {
1716         case S_IFREG:
1717                 fd = open(path, O_RDONLY);
1718                 if (fd < 0)
1719                         return error("open(\"%s\"): %s", path,
1720                                      strerror(errno));
1721                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1722                         return error("%s: failed to insert into database",
1723                                      path);
1724                 break;
1725         case S_IFLNK:
1726                 target = xmalloc(st->st_size+1);
1727                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1728                         char *errstr = strerror(errno);
1729                         free(target);
1730                         return error("readlink(\"%s\"): %s", path,
1731                                      errstr);
1732                 }
1733                 if (!write_object) {
1734                         unsigned char hdr[50];
1735                         int hdrlen;
1736                         write_sha1_file_prepare(target, st->st_size, blob_type,
1737                                                 sha1, hdr, &hdrlen);
1738                 } else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1739                         return error("%s: failed to insert into database",
1740                                      path);
1741                 free(target);
1742                 break;
1743         default:
1744                 return error("%s: unsupported file type", path);
1745         }
1746         return 0;
1747 }