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 safe_create_leading_directories(char *path)
  54 {
  55         char *pos = path;
  56         struct stat st;
  57
  58         if (*pos == '/')
  59                 pos++;
  60
  61         while (pos) {
  62                 pos = strchr(pos, '/');
  63                 if (!pos)
  64                         break;
  65                 *pos = 0;
  66                 if (!stat(path, &st)) {
  67                         /* path exists */
  68                         if (!S_ISDIR(st.st_mode)) {
  69                                 *pos = '/';
  70                                 return -3;
  71                         }
  72                 }
  73                 else if (mkdir(path, 0777)) {
  74                         *pos = '/';
  75                         return -1;
  76                 }
  77                 else if (adjust_shared_perm(path)) {
  78                         *pos = '/';
  79                         return -2;
  80                 }
  81                 *pos++ = '/';
  82         }
  83         return 0;
  84 }
  85
  86 char * sha1_to_hex(const unsigned char *sha1)
  87 {
  88         static int bufno;
  89         static char hexbuffer[4][50];
  90         static const char hex[] = "0123456789abcdef";
  91         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
  92         int i;
  93
  94         for (i = 0; i < 20; i++) {
  95                 unsigned int val = *sha1++;
  96                 *buf++ = hex[val >> 4];
  97                 *buf++ = hex[val & 0xf];
  98         }
  99         *buf = '\0';
 100
 101         return buffer;
 102 }
 103
 104 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 105 {
 106         int i;
 107         for (i = 0; i < 20; i++) {
 108                 static char hex[] = "0123456789abcdef";
 109                 unsigned int val = sha1[i];
 110                 char *pos = pathbuf + i*2 + (i > 0);
 111                 *pos++ = hex[val >> 4];
 112                 *pos = hex[val & 0xf];
 113         }
 114 }
 115
 116 /*
 117  * NOTE! This returns a statically allocated buffer, so you have to be
 118  * careful about using it. Do a "strdup()" if you need to save the
 119  * filename.
 120  *
 121  * Also note that this returns the location for creating.  Reading
 122  * SHA1 file can happen from any alternate directory listed in the
 123  * DB_ENVIRONMENT environment variable if it is not found in
 124  * the primary object database.
 125  */
 126 char *sha1_file_name(const unsigned char *sha1)
 127 {
 128         static char *name, *base;
 129
 130         if (!base) {
 131                 const char *sha1_file_directory = get_object_directory();
 132                 int len = strlen(sha1_file_directory);
 133                 base = xmalloc(len + 60);
 134                 memcpy(base, sha1_file_directory, len);
 135                 memset(base+len, 0, 60);
 136                 base[len] = '/';
 137                 base[len+3] = '/';
 138                 name = base + len + 1;
 139         }
 140         fill_sha1_path(name, sha1);
 141         return base;
 142 }
 143
 144 char *sha1_pack_name(const unsigned char *sha1)
 145 {
 146         static const char hex[] = "0123456789abcdef";
 147         static char *name, *base, *buf;
 148         int i;
 149
 150         if (!base) {
 151                 const char *sha1_file_directory = get_object_directory();
 152                 int len = strlen(sha1_file_directory);
 153                 base = xmalloc(len + 60);
 154                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 155                 name = base + len + 11;
 156         }
 157
 158         buf = name;
 159
 160         for (i = 0; i < 20; i++) {
 161                 unsigned int val = *sha1++;
 162                 *buf++ = hex[val >> 4];
 163                 *buf++ = hex[val & 0xf];
 164         }
 165
 166         return base;
 167 }
 168
 169 char *sha1_pack_index_name(const unsigned char *sha1)
 170 {
 171         static const char hex[] = "0123456789abcdef";
 172         static char *name, *base, *buf;
 173         int i;
 174
 175         if (!base) {
 176                 const char *sha1_file_directory = get_object_directory();
 177                 int len = strlen(sha1_file_directory);
 178                 base = xmalloc(len + 60);
 179                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 180                 name = base + len + 11;
 181         }
 182
 183         buf = name;
 184
 185         for (i = 0; i < 20; i++) {
 186                 unsigned int val = *sha1++;
 187                 *buf++ = hex[val >> 4];
 188                 *buf++ = hex[val & 0xf];
 189         }
 190
 191         return base;
 192 }
 193
 194 struct alternate_object_database *alt_odb_list;
 195 static struct alternate_object_database **alt_odb_tail;
 196
 197 static void read_info_alternates(const char * alternates, int depth);
 198
 199 /*
 200  * Prepare alternate object database registry.
 201  *
 202  * The variable alt_odb_list points at the list of struct
 203  * alternate_object_database.  The elements on this list come from
 204  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 205  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 206  * whose contents is similar to that environment variable but can be
 207  * LF separated.  Its base points at a statically allocated buffer that
 208  * contains "/the/directory/corresponding/to/.git/objects/...", while
 209  * its name points just after the slash at the end of ".git/objects/"
 210  * in the example above, and has enough space to hold 40-byte hex
 211  * SHA1, an extra slash for the first level indirection, and the
 212  * terminating NUL.
 213  */
 214 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 215 {
 216         struct stat st;
 217         const char *objdir = get_object_directory();
 218         struct alternate_object_database *ent;
 219         struct alternate_object_database *alt;
 220         /* 43 = 40-byte + 2 '/' + terminating NUL */
 221         int pfxlen = len;
 222         int entlen = pfxlen + 43;
 223         int base_len = -1;
 224
 225         if (*entry != '/' && relative_base) {
 226                 /* Relative alt-odb */
 227                 if (base_len < 0)
 228                         base_len = strlen(relative_base) + 1;
 229                 entlen += base_len;
 230                 pfxlen += base_len;
 231         }
 232         ent = xmalloc(sizeof(*ent) + entlen);
 233
 234         if (*entry != '/' && relative_base) {
 235                 memcpy(ent->base, relative_base, base_len - 1);
 236                 ent->base[base_len - 1] = '/';
 237                 memcpy(ent->base + base_len, entry, len);
 238         }
 239         else
 240                 memcpy(ent->base, entry, pfxlen);
 241
 242         ent->name = ent->base + pfxlen + 1;
 243         ent->base[pfxlen + 3] = '/';
 244         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 245
 246         /* Detect cases where alternate disappeared */
 247         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 248                 error("object directory %s does not exist; "
 249                       "check .git/objects/info/alternates.",
 250                       ent->base);
 251                 free(ent);
 252                 return -1;
 253         }
 254
 255         /* Prevent the common mistake of listing the same
 256          * thing twice, or object directory itself.
 257          */
 258         for (alt = alt_odb_list; alt; alt = alt->next) {
 259                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 260                         free(ent);
 261                         return -1;
 262                 }
 263         }
 264         if (!memcmp(ent->base, objdir, pfxlen)) {
 265                 free(ent);
 266                 return -1;
 267         }
 268
 269         /* add the alternate entry */
 270         *alt_odb_tail = ent;
 271         alt_odb_tail = &(ent->next);
 272         ent->next = NULL;
 273
 274         /* recursively add alternates */
 275         read_info_alternates(ent->base, depth + 1);
 276
 277         ent->base[pfxlen] = '/';
 278
 279         return 0;
 280 }
 281
 282 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 283                                  const char *relative_base, int depth)
 284 {
 285         const char *cp, *last;
 286
 287         if (depth > 5) {
 288                 error("%s: ignoring alternate object stores, nesting too deep.",
 289                                 relative_base);
 290                 return;
 291         }
 292
 293         last = alt;
 294         while (last < ep) {
 295                 cp = last;
 296                 if (cp < ep && *cp == '#') {
 297                         while (cp < ep && *cp != sep)
 298                                 cp++;
 299                         last = cp + 1;
 300                         continue;
 301                 }
 302                 while (cp < ep && *cp != sep)
 303                         cp++;
 304                 if (last != cp) {
 305                         if ((*last != '/') && depth) {
 306                                 error("%s: ignoring relative alternate object store %s",
 307                                                 relative_base, last);
 308                         } else {
 309                                 link_alt_odb_entry(last, cp - last,
 310                                                 relative_base, depth);
 311                         }
 312                 }
 313                 while (cp < ep && *cp == sep)
 314                         cp++;
 315                 last = cp;
 316         }
 317 }
 318
 319 static void read_info_alternates(const char * relative_base, int depth)
 320 {
 321         char *map;
 322         struct stat st;
 323         char path[PATH_MAX];
 324         int fd;
 325
 326         sprintf(path, "%s/info/alternates", relative_base);
 327         fd = open(path, O_RDONLY);
 328         if (fd < 0)
 329                 return;
 330         if (fstat(fd, &st) || (st.st_size == 0)) {
 331                 close(fd);
 332                 return;
 333         }
 334         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 335         close(fd);
 336         if (map == MAP_FAILED)
 337                 return;
 338
 339         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 340
 341         munmap(map, st.st_size);
 342 }
 343
 344 void prepare_alt_odb(void)
 345 {
 346         char *alt;
 347
 348         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 349         if (!alt) alt = "";
 350
 351         if (alt_odb_tail)
 352                 return;
 353         alt_odb_tail = &alt_odb_list;
 354         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 355
 356         read_info_alternates(get_object_directory(), 0);
 357 }
 358
 359 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 360 {
 361         char *name = sha1_file_name(sha1);
 362         struct alternate_object_database *alt;
 363
 364         if (!stat(name, st))
 365                 return name;
 366         prepare_alt_odb();
 367         for (alt = alt_odb_list; alt; alt = alt->next) {
 368                 name = alt->name;
 369                 fill_sha1_path(name, sha1);
 370                 if (!stat(alt->base, st))
 371                         return alt->base;
 372         }
 373         return NULL;
 374 }
 375
 376 #define PACK_MAX_SZ (1<<26)
 377 static int pack_used_ctr;
 378 static unsigned long pack_mapped;
 379 struct packed_git *packed_git;
 380
 381 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 382                                 void **idx_map_)
 383 {
 384         void *idx_map;
 385         unsigned int *index;
 386         unsigned long idx_size;
 387         int nr, i;
 388         int fd = open(path, O_RDONLY);
 389         struct stat st;
 390         if (fd < 0)
 391                 return -1;
 392         if (fstat(fd, &st)) {
 393                 close(fd);
 394                 return -1;
 395         }
 396         idx_size = st.st_size;
 397         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 398         close(fd);
 399         if (idx_map == MAP_FAILED)
 400                 return -1;
 401
 402         index = idx_map;
 403         *idx_map_ = idx_map;
 404         *idx_size_ = idx_size;
 405
 406         /* check index map */
 407         if (idx_size < 4*256 + 20 + 20)
 408                 return error("index file too small");
 409         nr = 0;
 410         for (i = 0; i < 256; i++) {
 411                 unsigned int n = ntohl(index[i]);
 412                 if (n < nr)
 413                         return error("non-monotonic index");
 414                 nr = n;
 415         }
 416
 417         /*
 418          * Total size:
 419          *  - 256 index entries 4 bytes each
 420          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 421          *  - 20-byte SHA1 of the packfile
 422          *  - 20-byte SHA1 file checksum
 423          */
 424         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 425                 return error("wrong index file size");
 426
 427         return 0;
 428 }
 429
 430 static int unuse_one_packed_git(void)
 431 {
 432         struct packed_git *p, *lru = NULL;
 433
 434         for (p = packed_git; p; p = p->next) {
 435                 if (p->pack_use_cnt || !p->pack_base)
 436                         continue;
 437                 if (!lru || p->pack_last_used < lru->pack_last_used)
 438                         lru = p;
 439         }
 440         if (!lru)
 441                 return 0;
 442         munmap(lru->pack_base, lru->pack_size);
 443         lru->pack_base = NULL;
 444         return 1;
 445 }
 446
 447 void unuse_packed_git(struct packed_git *p)
 448 {
 449         p->pack_use_cnt--;
 450 }
 451
 452 int use_packed_git(struct packed_git *p)
 453 {
 454         if (!p->pack_size) {
 455                 struct stat st;
 456                 // We created the struct before we had the pack
 457                 stat(p->pack_name, &st);
 458                 if (!S_ISREG(st.st_mode))
 459                         die("packfile %s not a regular file", p->pack_name);
 460                 p->pack_size = st.st_size;
 461         }
 462         if (!p->pack_base) {
 463                 int fd;
 464                 struct stat st;
 465                 void *map;
 466
 467                 pack_mapped += p->pack_size;
 468                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 469                         ; /* nothing */
 470                 fd = open(p->pack_name, O_RDONLY);
 471                 if (fd < 0)
 472                         die("packfile %s cannot be opened", p->pack_name);
 473                 if (fstat(fd, &st)) {
 474                         close(fd);
 475                         die("packfile %s cannot be opened", p->pack_name);
 476                 }
 477                 if (st.st_size != p->pack_size)
 478                         die("packfile %s size mismatch.", p->pack_name);
 479                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 480                 close(fd);
 481                 if (map == MAP_FAILED)
 482                         die("packfile %s cannot be mapped.", p->pack_name);
 483                 p->pack_base = map;
 484
 485                 /* Check if the pack file matches with the index file.
 486                  * this is cheap.
 487                  */
 488                 if (memcmp((char*)(p->index_base) + p->index_size - 40,
 489                            p->pack_base + p->pack_size - 20, 20)) {
 490
 491                         die("packfile %s does not match index.", p->pack_name);
 492                 }
 493         }
 494         p->pack_last_used = pack_used_ctr++;
 495         p->pack_use_cnt++;
 496         return 0;
 497 }
 498
 499 struct packed_git *add_packed_git(char *path, int path_len, int local)
 500 {
 501         struct stat st;
 502         struct packed_git *p;
 503         unsigned long idx_size;
 504         void *idx_map;
 505         unsigned char sha1[20];
 506
 507         if (check_packed_git_idx(path, &idx_size, &idx_map))
 508                 return NULL;
 509
 510         /* do we have a corresponding .pack file? */
 511         strcpy(path + path_len - 4, ".pack");
 512         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 513                 munmap(idx_map, idx_size);
 514                 return NULL;
 515         }
 516         /* ok, it looks sane as far as we can check without
 517          * actually mapping the pack file.
 518          */
 519         p = xmalloc(sizeof(*p) + path_len + 2);
 520         strcpy(p->pack_name, path);
 521         p->index_size = idx_size;
 522         p->pack_size = st.st_size;
 523         p->index_base = idx_map;
 524         p->next = NULL;
 525         p->pack_base = NULL;
 526         p->pack_last_used = 0;
 527         p->pack_use_cnt = 0;
 528         p->pack_local = local;
 529         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 530                 memcpy(p->sha1, sha1, 20);
 531         return p;
 532 }
 533
 534 struct packed_git *parse_pack_index(unsigned char *sha1)
 535 {
 536         char *path = sha1_pack_index_name(sha1);
 537         return parse_pack_index_file(sha1, path);
 538 }
 539
 540 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 541 {
 542         struct packed_git *p;
 543         unsigned long idx_size;
 544         void *idx_map;
 545         char *path;
 546
 547         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 548                 return NULL;
 549
 550         path = sha1_pack_name(sha1);
 551
 552         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 553         strcpy(p->pack_name, path);
 554         p->index_size = idx_size;
 555         p->pack_size = 0;
 556         p->index_base = idx_map;
 557         p->next = NULL;
 558         p->pack_base = NULL;
 559         p->pack_last_used = 0;
 560         p->pack_use_cnt = 0;
 561         memcpy(p->sha1, sha1, 20);
 562         return p;
 563 }
 564
 565 void install_packed_git(struct packed_git *pack)
 566 {
 567         pack->next = packed_git;
 568         packed_git = pack;
 569 }
 570
 571 static void prepare_packed_git_one(char *objdir, int local)
 572 {
 573         char path[PATH_MAX];
 574         int len;
 575         DIR *dir;
 576         struct dirent *de;
 577
 578         sprintf(path, "%s/pack", objdir);
 579         len = strlen(path);
 580         dir = opendir(path);
 581         if (!dir) {
 582                 if (errno != ENOENT)
 583                         error("unable to open object pack directory: %s: %s",
 584                               path, strerror(errno));
 585                 return;
 586         }
 587         path[len++] = '/';
 588         while ((de = readdir(dir)) != NULL) {
 589                 int namelen = strlen(de->d_name);
 590                 struct packed_git *p;
 591
 592                 if (strcmp(de->d_name + namelen - 4, ".idx"))
 593                         continue;
 594
 595                 /* we have .idx.  Is it a file we can map? */
 596                 strcpy(path + len, de->d_name);
 597                 for (p = packed_git; p; p = p->next) {
 598                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 599                                 break;
 600                 }
 601                 if (p)
 602                         continue;
 603                 p = add_packed_git(path, len + namelen, local);
 604                 if (!p)
 605                         continue;
 606                 p->next = packed_git;
 607                 packed_git = p;
 608         }
 609         closedir(dir);
 610 }
 611
 612 static int prepare_packed_git_run_once = 0;
 613 void prepare_packed_git(void)
 614 {
 615         struct alternate_object_database *alt;
 616
 617         if (prepare_packed_git_run_once)
 618                 return;
 619         prepare_packed_git_one(get_object_directory(), 1);
 620         prepare_alt_odb();
 621         for (alt = alt_odb_list; alt; alt = alt->next) {
 622                 alt->name[-1] = 0;
 623                 prepare_packed_git_one(alt->base, 0);
 624                 alt->name[-1] = '/';
 625         }
 626         prepare_packed_git_run_once = 1;
 627 }
 628
 629 static void reprepare_packed_git(void)
 630 {
 631         prepare_packed_git_run_once = 0;
 632         prepare_packed_git();
 633 }
 634
 635 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 636 {
 637         char header[100];
 638         unsigned char real_sha1[20];
 639         SHA_CTX c;
 640
 641         SHA1_Init(&c);
 642         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 643         SHA1_Update(&c, map, size);
 644         SHA1_Final(real_sha1, &c);
 645         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 646 }
 647
 648 static void *map_sha1_file_internal(const unsigned char *sha1,
 649                                     unsigned long *size)
 650 {
 651         struct stat st;
 652         void *map;
 653         int fd;
 654         char *filename = find_sha1_file(sha1, &st);
 655
 656         if (!filename) {
 657                 return NULL;
 658         }
 659
 660         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 661         if (fd < 0) {
 662                 /* See if it works without O_NOATIME */
 663                 switch (sha1_file_open_flag) {
 664                 default:
 665                         fd = open(filename, O_RDONLY);
 666                         if (fd >= 0)
 667                                 break;
 668                 /* Fallthrough */
 669                 case 0:
 670                         return NULL;
 671                 }
 672
 673                 /* If it failed once, it will probably fail again.
 674                  * Stop using O_NOATIME
 675                  */
 676                 sha1_file_open_flag = 0;
 677         }
 678         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 679         close(fd);
 680         if (map == MAP_FAILED)
 681                 return NULL;
 682         *size = st.st_size;
 683         return map;
 684 }
 685
 686 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 687 {
 688         /* Get the data stream */
 689         memset(stream, 0, sizeof(*stream));
 690         stream->next_in = map;
 691         stream->avail_in = mapsize;
 692         stream->next_out = buffer;
 693         stream->avail_out = size;
 694
 695         inflateInit(stream);
 696         return inflate(stream, 0);
 697 }
 698
 699 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 700 {
 701         int bytes = strlen(buffer) + 1;
 702         unsigned char *buf = xmalloc(1+size);
 703
 704         memcpy(buf, buffer + bytes, stream->total_out - bytes);
 705         bytes = stream->total_out - bytes;
 706         if (bytes < size) {
 707                 stream->next_out = buf + bytes;
 708                 stream->avail_out = size - bytes;
 709                 while (inflate(stream, Z_FINISH) == Z_OK)
 710                         /* nothing */;
 711         }
 712         buf[size] = 0;
 713         inflateEnd(stream);
 714         return buf;
 715 }
 716
 717 /*
 718  * We used to just use "sscanf()", but that's actually way
 719  * too permissive for what we want to check. So do an anal
 720  * object header parse by hand.
 721  */
 722 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 723 {
 724         int i;
 725         unsigned long size;
 726
 727         /*
 728          * The type can be at most ten bytes (including the
 729          * terminating '\0' that we add), and is followed by
 730          * a space.
 731          */
 732         i = 10;
 733         for (;;) {
 734                 char c = *hdr++;
 735                 if (c == ' ')
 736                         break;
 737                 if (!--i)
 738                         return -1;
 739                 *type++ = c;
 740         }
 741         *type = 0;
 742
 743         /*
 744          * The length must follow immediately, and be in canonical
 745          * decimal format (ie "010" is not valid).
 746          */
 747         size = *hdr++ - '0';
 748         if (size > 9)
 749                 return -1;
 750         if (size) {
 751                 for (;;) {
 752                         unsigned long c = *hdr - '0';
 753                         if (c > 9)
 754                                 break;
 755                         hdr++;
 756                         size = size * 10 + c;
 757                 }
 758         }
 759         *sizep = size;
 760
 761         /*
 762          * The length must be followed by a zero byte
 763          */
 764         return *hdr ? -1 : 0;
 765 }
 766
 767 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 768 {
 769         int ret;
 770         z_stream stream;
 771         char hdr[8192];
 772
 773         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 774         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 775                 return NULL;
 776
 777         return unpack_sha1_rest(&stream, hdr, *size);
 778 }
 779
 780 /* forward declaration for a mutually recursive function */
 781 static int packed_object_info(struct pack_entry *entry,
 782                               char *type, unsigned long *sizep);
 783
 784 static int packed_delta_info(unsigned char *base_sha1,
 785                              unsigned long delta_size,
 786                              unsigned long left,
 787                              char *type,
 788                              unsigned long *sizep,
 789                              struct packed_git *p)
 790 {
 791         struct pack_entry base_ent;
 792
 793         if (left < 20)
 794                 die("truncated pack file");
 795
 796         /* The base entry _must_ be in the same pack */
 797         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 798                 die("failed to find delta-pack base object %s",
 799                     sha1_to_hex(base_sha1));
 800
 801         /* We choose to only get the type of the base object and
 802          * ignore potentially corrupt pack file that expects the delta
 803          * based on a base with a wrong size.  This saves tons of
 804          * inflate() calls.
 805          */
 806
 807         if (packed_object_info(&base_ent, type, NULL))
 808                 die("cannot get info for delta-pack base");
 809
 810         if (sizep) {
 811                 const unsigned char *data;
 812                 unsigned char delta_head[64];
 813                 unsigned long result_size;
 814                 z_stream stream;
 815                 int st;
 816
 817                 memset(&stream, 0, sizeof(stream));
 818
 819                 data = stream.next_in = base_sha1 + 20;
 820                 stream.avail_in = left - 20;
 821                 stream.next_out = delta_head;
 822                 stream.avail_out = sizeof(delta_head);
 823
 824                 inflateInit(&stream);
 825                 st = inflate(&stream, Z_FINISH);
 826                 inflateEnd(&stream);
 827                 if ((st != Z_STREAM_END) &&
 828                     stream.total_out != sizeof(delta_head))
 829                         die("delta data unpack-initial failed");
 830
 831                 /* Examine the initial part of the delta to figure out
 832                  * the result size.
 833                  */
 834                 data = delta_head;
 835
 836                 /* ignore base size */
 837                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 838
 839                 /* Read the result size */
 840                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 841                 *sizep = result_size;
 842         }
 843         return 0;
 844 }
 845
 846 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 847         enum object_type *type, unsigned long *sizep)
 848 {
 849         unsigned shift;
 850         unsigned char *pack, c;
 851         unsigned long size;
 852
 853         if (offset >= p->pack_size)
 854                 die("object offset outside of pack file");
 855
 856         pack =  p->pack_base + offset;
 857         c = *pack++;
 858         offset++;
 859         *type = (c >> 4) & 7;
 860         size = c & 15;
 861         shift = 4;
 862         while (c & 0x80) {
 863                 if (offset >= p->pack_size)
 864                         die("object offset outside of pack file");
 865                 c = *pack++;
 866                 offset++;
 867                 size += (c & 0x7f) << shift;
 868                 shift += 7;
 869         }
 870         *sizep = size;
 871         return offset;
 872 }
 873
 874 int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
 875                            unsigned char *base, unsigned long *sizep,
 876                            enum object_type *kindp)
 877 {
 878         unsigned long ptr;
 879         int status = -1;
 880
 881         use_packed_git(p);
 882         ptr = offset;
 883         ptr = unpack_object_header(p, ptr, kindp, sizep);
 884         if (*kindp != OBJ_DELTA)
 885                 goto done;
 886         memcpy(base, p->pack_base + ptr, 20);
 887         status = 0;
 888  done:
 889         unuse_packed_git(p);
 890         return status;
 891 }
 892
 893 void packed_object_info_detail(struct pack_entry *e,
 894                                char *type,
 895                                unsigned long *size,
 896                                unsigned long *store_size,
 897                                unsigned int *delta_chain_length,
 898                                unsigned char *base_sha1)
 899 {
 900         struct packed_git *p = e->p;
 901         unsigned long offset;
 902         unsigned char *pack;
 903         enum object_type kind;
 904
 905         offset = unpack_object_header(p, e->offset, &kind, size);
 906         pack = p->pack_base + offset;
 907         if (kind != OBJ_DELTA)
 908                 *delta_chain_length = 0;
 909         else {
 910                 unsigned int chain_length = 0;
 911                 if (p->pack_size <= offset + 20)
 912                         die("pack file %s records an incomplete delta base",
 913                             p->pack_name);
 914                 memcpy(base_sha1, pack, 20);
 915                 do {
 916                         struct pack_entry base_ent;
 917                         unsigned long junk;
 918
 919                         find_pack_entry_one(pack, &base_ent, p);
 920                         offset = unpack_object_header(p, base_ent.offset,
 921                                                       &kind, &junk);
 922                         pack = p->pack_base + offset;
 923                         chain_length++;
 924                 } while (kind == OBJ_DELTA);
 925                 *delta_chain_length = chain_length;
 926         }
 927         switch (kind) {
 928         case OBJ_COMMIT:
 929                 strcpy(type, commit_type);
 930                 break;
 931         case OBJ_TREE:
 932                 strcpy(type, tree_type);
 933                 break;
 934         case OBJ_BLOB:
 935                 strcpy(type, blob_type);
 936                 break;
 937         case OBJ_TAG:
 938                 strcpy(type, tag_type);
 939                 break;
 940         default:
 941                 die("corrupted pack file %s containing object of kind %d",
 942                     p->pack_name, kind);
 943         }
 944         *store_size = 0; /* notyet */
 945 }
 946
 947 static int packed_object_info(struct pack_entry *entry,
 948                               char *type, unsigned long *sizep)
 949 {
 950         struct packed_git *p = entry->p;
 951         unsigned long offset, size, left;
 952         unsigned char *pack;
 953         enum object_type kind;
 954         int retval;
 955
 956         if (use_packed_git(p))
 957                 die("cannot map packed file");
 958
 959         offset = unpack_object_header(p, entry->offset, &kind, &size);
 960         pack = p->pack_base + offset;
 961         left = p->pack_size - offset;
 962
 963         switch (kind) {
 964         case OBJ_DELTA:
 965                 retval = packed_delta_info(pack, size, left, type, sizep, p);
 966                 unuse_packed_git(p);
 967                 return retval;
 968         case OBJ_COMMIT:
 969                 strcpy(type, commit_type);
 970                 break;
 971         case OBJ_TREE:
 972                 strcpy(type, tree_type);
 973                 break;
 974         case OBJ_BLOB:
 975                 strcpy(type, blob_type);
 976                 break;
 977         case OBJ_TAG:
 978                 strcpy(type, tag_type);
 979                 break;
 980         default:
 981                 die("corrupted pack file %s containing object of kind %d",
 982                     p->pack_name, kind);
 983         }
 984         if (sizep)
 985                 *sizep = size;
 986         unuse_packed_git(p);
 987         return 0;
 988 }
 989
 990 /* forward declaration for a mutually recursive function */
 991 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 992
 993 static void *unpack_delta_entry(unsigned char *base_sha1,
 994                                 unsigned long delta_size,
 995                                 unsigned long left,
 996                                 char *type,
 997                                 unsigned long *sizep,
 998                                 struct packed_git *p)
 999 {
1000         struct pack_entry base_ent;
1001         void *data, *delta_data, *result, *base;
1002         unsigned long data_size, result_size, base_size;
1003         z_stream stream;
1004         int st;
1005
1006         if (left < 20)
1007                 die("truncated pack file");
1008
1009         /* The base entry _must_ be in the same pack */
1010         if (!find_pack_entry_one(base_sha1, &base_ent, p))
1011                 die("failed to find delta-pack base object %s",
1012                     sha1_to_hex(base_sha1));
1013         base = unpack_entry_gently(&base_ent, type, &base_size);
1014         if (!base)
1015                 die("failed to read delta-pack base object %s",
1016                     sha1_to_hex(base_sha1));
1017
1018         data = base_sha1 + 20;
1019         data_size = left - 20;
1020         delta_data = xmalloc(delta_size);
1021
1022         memset(&stream, 0, sizeof(stream));
1023
1024         stream.next_in = data;
1025         stream.avail_in = data_size;
1026         stream.next_out = delta_data;
1027         stream.avail_out = delta_size;
1028
1029         inflateInit(&stream);
1030         st = inflate(&stream, Z_FINISH);
1031         inflateEnd(&stream);
1032         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
1033                 die("delta data unpack failed");
1034
1035         result = patch_delta(base, base_size,
1036                              delta_data, delta_size,
1037                              &result_size);
1038         if (!result)
1039                 die("failed to apply delta");
1040         free(delta_data);
1041         free(base);
1042         *sizep = result_size;
1043         return result;
1044 }
1045
1046 static void *unpack_non_delta_entry(unsigned char *data,
1047                                     unsigned long size,
1048                                     unsigned long left)
1049 {
1050         int st;
1051         z_stream stream;
1052         unsigned char *buffer;
1053
1054         buffer = xmalloc(size + 1);
1055         buffer[size] = 0;
1056         memset(&stream, 0, sizeof(stream));
1057         stream.next_in = data;
1058         stream.avail_in = left;
1059         stream.next_out = buffer;
1060         stream.avail_out = size;
1061
1062         inflateInit(&stream);
1063         st = inflate(&stream, Z_FINISH);
1064         inflateEnd(&stream);
1065         if ((st != Z_STREAM_END) || stream.total_out != size) {
1066                 free(buffer);
1067                 return NULL;
1068         }
1069
1070         return buffer;
1071 }
1072
1073 static void *unpack_entry(struct pack_entry *entry,
1074                           char *type, unsigned long *sizep)
1075 {
1076         struct packed_git *p = entry->p;
1077         void *retval;
1078
1079         if (use_packed_git(p))
1080                 die("cannot map packed file");
1081         retval = unpack_entry_gently(entry, type, sizep);
1082         unuse_packed_git(p);
1083         if (!retval)
1084                 die("corrupted pack file %s", p->pack_name);
1085         return retval;
1086 }
1087
1088 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
1089 void *unpack_entry_gently(struct pack_entry *entry,
1090                           char *type, unsigned long *sizep)
1091 {
1092         struct packed_git *p = entry->p;
1093         unsigned long offset, size, left;
1094         unsigned char *pack;
1095         enum object_type kind;
1096         void *retval;
1097
1098         offset = unpack_object_header(p, entry->offset, &kind, &size);
1099         pack = p->pack_base + offset;
1100         left = p->pack_size - offset;
1101         switch (kind) {
1102         case OBJ_DELTA:
1103                 retval = unpack_delta_entry(pack, size, left, type, sizep, p);
1104                 return retval;
1105         case OBJ_COMMIT:
1106                 strcpy(type, commit_type);
1107                 break;
1108         case OBJ_TREE:
1109                 strcpy(type, tree_type);
1110                 break;
1111         case OBJ_BLOB:
1112                 strcpy(type, blob_type);
1113                 break;
1114         case OBJ_TAG:
1115                 strcpy(type, tag_type);
1116                 break;
1117         default:
1118                 return NULL;
1119         }
1120         *sizep = size;
1121         retval = unpack_non_delta_entry(pack, size, left);
1122         return retval;
1123 }
1124
1125 int num_packed_objects(const struct packed_git *p)
1126 {
1127         /* See check_packed_git_idx() */
1128         return (p->index_size - 20 - 20 - 4*256) / 24;
1129 }
1130
1131 int nth_packed_object_sha1(const struct packed_git *p, int n,
1132                            unsigned char* sha1)
1133 {
1134         void *index = p->index_base + 256;
1135         if (n < 0 || num_packed_objects(p) <= n)
1136                 return -1;
1137         memcpy(sha1, (index + 24 * n + 4), 20);
1138         return 0;
1139 }
1140
1141 int find_pack_entry_one(const unsigned char *sha1,
1142                         struct pack_entry *e, struct packed_git *p)
1143 {
1144         unsigned int *level1_ofs = p->index_base;
1145         int hi = ntohl(level1_ofs[*sha1]);
1146         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1147         void *index = p->index_base + 256;
1148
1149         do {
1150                 int mi = (lo + hi) / 2;
1151                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1152                 if (!cmp) {
1153                         e->offset = ntohl(*((unsigned int *)(index + 24 * mi)));
1154                         memcpy(e->sha1, sha1, 20);
1155                         e->p = p;
1156                         return 1;
1157                 }
1158                 if (cmp > 0)
1159                         hi = mi;
1160                 else
1161                         lo = mi+1;
1162         } while (lo < hi);
1163         return 0;
1164 }
1165
1166 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1167 {
1168         struct packed_git *p;
1169         prepare_packed_git();
1170
1171         for (p = packed_git; p; p = p->next) {
1172                 if (find_pack_entry_one(sha1, e, p))
1173                         return 1;
1174         }
1175         return 0;
1176 }
1177
1178 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1179                                   struct packed_git *packs)
1180 {
1181         struct packed_git *p;
1182         struct pack_entry e;
1183
1184         for (p = packs; p; p = p->next) {
1185                 if (find_pack_entry_one(sha1, &e, p))
1186                         return p;
1187         }
1188         return NULL;
1189
1190 }
1191
1192 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1193 {
1194         int status;
1195         unsigned long mapsize, size;
1196         void *map;
1197         z_stream stream;
1198         char hdr[128];
1199
1200         map = map_sha1_file_internal(sha1, &mapsize);
1201         if (!map) {
1202                 struct pack_entry e;
1203
1204                 if (find_pack_entry(sha1, &e))
1205                         return packed_object_info(&e, type, sizep);
1206                 reprepare_packed_git();
1207                 if (find_pack_entry(sha1, &e))
1208                         return packed_object_info(&e, type, sizep);
1209                 return error("unable to find %s", sha1_to_hex(sha1));
1210         }
1211         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1212                 status = error("unable to unpack %s header",
1213                                sha1_to_hex(sha1));
1214         if (parse_sha1_header(hdr, type, &size) < 0)
1215                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1216         else {
1217                 status = 0;
1218                 if (sizep)
1219                         *sizep = size;
1220         }
1221         inflateEnd(&stream);
1222         munmap(map, mapsize);
1223         return status;
1224 }
1225
1226 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1227 {
1228         struct pack_entry e;
1229
1230         if (!find_pack_entry(sha1, &e)) {
1231                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1232                 return NULL;
1233         }
1234         return unpack_entry(&e, type, size);
1235 }
1236
1237 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1238 {
1239         unsigned long mapsize;
1240         void *map, *buf;
1241         struct pack_entry e;
1242
1243         if (find_pack_entry(sha1, &e))
1244                 return read_packed_sha1(sha1, type, size);
1245         map = map_sha1_file_internal(sha1, &mapsize);
1246         if (map) {
1247                 buf = unpack_sha1_file(map, mapsize, type, size);
1248                 munmap(map, mapsize);
1249                 return buf;
1250         }
1251         reprepare_packed_git();
1252         if (find_pack_entry(sha1, &e))
1253                 return read_packed_sha1(sha1, type, size);
1254         return NULL;
1255 }
1256
1257 void *read_object_with_reference(const unsigned char *sha1,
1258                                  const char *required_type,
1259                                  unsigned long *size,
1260                                  unsigned char *actual_sha1_return)
1261 {
1262         char type[20];
1263         void *buffer;
1264         unsigned long isize;
1265         unsigned char actual_sha1[20];
1266
1267         memcpy(actual_sha1, sha1, 20);
1268         while (1) {
1269                 int ref_length = -1;
1270                 const char *ref_type = NULL;
1271
1272                 buffer = read_sha1_file(actual_sha1, type, &isize);
1273                 if (!buffer)
1274                         return NULL;
1275                 if (!strcmp(type, required_type)) {
1276                         *size = isize;
1277                         if (actual_sha1_return)
1278                                 memcpy(actual_sha1_return, actual_sha1, 20);
1279                         return buffer;
1280                 }
1281                 /* Handle references */
1282                 else if (!strcmp(type, commit_type))
1283                         ref_type = "tree ";
1284                 else if (!strcmp(type, tag_type))
1285                         ref_type = "object ";
1286                 else {
1287                         free(buffer);
1288                         return NULL;
1289                 }
1290                 ref_length = strlen(ref_type);
1291
1292                 if (memcmp(buffer, ref_type, ref_length) ||
1293                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
1294                         free(buffer);
1295                         return NULL;
1296                 }
1297                 free(buffer);
1298                 /* Now we have the ID of the referred-to object in
1299                  * actual_sha1.  Check again. */
1300         }
1301 }
1302
1303 char *write_sha1_file_prepare(void *buf,
1304                               unsigned long len,
1305                               const char *type,
1306                               unsigned char *sha1,
1307                               unsigned char *hdr,
1308                               int *hdrlen)
1309 {
1310         SHA_CTX c;
1311
1312         /* Generate the header */
1313         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1314
1315         /* Sha1.. */
1316         SHA1_Init(&c);
1317         SHA1_Update(&c, hdr, *hdrlen);
1318         SHA1_Update(&c, buf, len);
1319         SHA1_Final(sha1, &c);
1320
1321         return sha1_file_name(sha1);
1322 }
1323
1324 /*
1325  * Link the tempfile to the final place, possibly creating the
1326  * last directory level as you do so.
1327  *
1328  * Returns the errno on failure, 0 on success.
1329  */
1330 static int link_temp_to_file(const char *tmpfile, char *filename)
1331 {
1332         int ret;
1333
1334         if (!link(tmpfile, filename))
1335                 return 0;
1336
1337         /*
1338          * Try to mkdir the last path component if that failed
1339          * with an ENOENT.
1340          *
1341          * Re-try the "link()" regardless of whether the mkdir
1342          * succeeds, since a race might mean that somebody
1343          * else succeeded.
1344          */
1345         ret = errno;
1346         if (ret == ENOENT) {
1347                 char *dir = strrchr(filename, '/');
1348                 if (dir) {
1349                         *dir = 0;
1350                         mkdir(filename, 0777);
1351                         if (adjust_shared_perm(filename))
1352                                 return -2;
1353                         *dir = '/';
1354                         if (!link(tmpfile, filename))
1355                                 return 0;
1356                         ret = errno;
1357                 }
1358         }
1359         return ret;
1360 }
1361
1362 /*
1363  * Move the just written object into its final resting place
1364  */
1365 int move_temp_to_file(const char *tmpfile, char *filename)
1366 {
1367         int ret = link_temp_to_file(tmpfile, filename);
1368
1369         /*
1370          * Coda hack - coda doesn't like cross-directory links,
1371          * so we fall back to a rename, which will mean that it
1372          * won't be able to check collisions, but that's not a
1373          * big deal.
1374          *
1375          * The same holds for FAT formatted media.
1376          *
1377          * When this succeeds, we just return 0. We have nothing
1378          * left to unlink.
1379          */
1380         if (ret && ret != EEXIST) {
1381                 if (!rename(tmpfile, filename))
1382                         return 0;
1383                 ret = errno;
1384         }
1385         unlink(tmpfile);
1386         if (ret) {
1387                 if (ret != EEXIST) {
1388                         fprintf(stderr, "unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1389                         return -1;
1390                 }
1391                 /* FIXME!!! Collision check here ? */
1392         }
1393
1394         return 0;
1395 }
1396
1397 static int write_buffer(int fd, const void *buf, size_t len)
1398 {
1399         while (len) {
1400                 ssize_t size;
1401
1402                 size = write(fd, buf, len);
1403                 if (!size)
1404                         return error("file write: disk full");
1405                 if (size < 0) {
1406                         if (errno == EINTR || errno == EAGAIN)
1407                                 continue;
1408                         return error("file write error (%s)", strerror(errno));
1409                 }
1410                 len -= size;
1411                 buf += size;
1412         }
1413         return 0;
1414 }
1415
1416 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1417 {
1418         int size;
1419         unsigned char *compressed;
1420         z_stream stream;
1421         unsigned char sha1[20];
1422         char *filename;
1423         static char tmpfile[PATH_MAX];
1424         unsigned char hdr[50];
1425         int fd, hdrlen;
1426
1427         /* Normally if we have it in the pack then we do not bother writing
1428          * it out into .git/objects/??/?{38} file.
1429          */
1430         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1431         if (returnsha1)
1432                 memcpy(returnsha1, sha1, 20);
1433         if (has_sha1_file(sha1))
1434                 return 0;
1435         fd = open(filename, O_RDONLY);
1436         if (fd >= 0) {
1437                 /*
1438                  * FIXME!!! We might do collision checking here, but we'd
1439                  * need to uncompress the old file and check it. Later.
1440                  */
1441                 close(fd);
1442                 return 0;
1443         }
1444
1445         if (errno != ENOENT) {
1446                 fprintf(stderr, "sha1 file %s: %s\n", filename, strerror(errno));
1447                 return -1;
1448         }
1449
1450         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1451
1452         fd = mkstemp(tmpfile);
1453         if (fd < 0) {
1454                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1455                 return -1;
1456         }
1457
1458         /* Set it up */
1459         memset(&stream, 0, sizeof(stream));
1460         deflateInit(&stream, Z_BEST_COMPRESSION);
1461         size = deflateBound(&stream, len+hdrlen);
1462         compressed = xmalloc(size);
1463
1464         /* Compress it */
1465         stream.next_out = compressed;
1466         stream.avail_out = size;
1467
1468         /* First header.. */
1469         stream.next_in = hdr;
1470         stream.avail_in = hdrlen;
1471         while (deflate(&stream, 0) == Z_OK)
1472                 /* nothing */;
1473
1474         /* Then the data itself.. */
1475         stream.next_in = buf;
1476         stream.avail_in = len;
1477         while (deflate(&stream, Z_FINISH) == Z_OK)
1478                 /* nothing */;
1479         deflateEnd(&stream);
1480         size = stream.total_out;
1481
1482         if (write_buffer(fd, compressed, size) < 0)
1483                 die("unable to write sha1 file");
1484         fchmod(fd, 0444);
1485         close(fd);
1486         free(compressed);
1487
1488         return move_temp_to_file(tmpfile, filename);
1489 }
1490
1491 /*
1492  * We need to unpack and recompress the object for writing
1493  * it out to a different file.
1494  */
1495 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1496 {
1497         size_t size;
1498         z_stream stream;
1499         unsigned char *unpacked;
1500         unsigned long len;
1501         char type[20];
1502         char hdr[50];
1503         int hdrlen;
1504         void *buf;
1505
1506         // need to unpack and recompress it by itself
1507         unpacked = read_packed_sha1(sha1, type, &len);
1508
1509         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1510
1511         /* Set it up */
1512         memset(&stream, 0, sizeof(stream));
1513         deflateInit(&stream, Z_BEST_COMPRESSION);
1514         size = deflateBound(&stream, len + hdrlen);
1515         buf = xmalloc(size);
1516
1517         /* Compress it */
1518         stream.next_out = buf;
1519         stream.avail_out = size;
1520
1521         /* First header.. */
1522         stream.next_in = (void *)hdr;
1523         stream.avail_in = hdrlen;
1524         while (deflate(&stream, 0) == Z_OK)
1525                 /* nothing */;
1526
1527         /* Then the data itself.. */
1528         stream.next_in = unpacked;
1529         stream.avail_in = len;
1530         while (deflate(&stream, Z_FINISH) == Z_OK)
1531                 /* nothing */;
1532         deflateEnd(&stream);
1533         free(unpacked);
1534
1535         *objsize = stream.total_out;
1536         return buf;
1537 }
1538
1539 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1540 {
1541         int retval;
1542         unsigned long objsize;
1543         void *buf = map_sha1_file_internal(sha1, &objsize);
1544
1545         if (buf) {
1546                 retval = write_buffer(fd, buf, objsize);
1547                 munmap(buf, objsize);
1548                 return retval;
1549         }
1550
1551         buf = repack_object(sha1, &objsize);
1552         retval = write_buffer(fd, buf, objsize);
1553         free(buf);
1554         return retval;
1555 }
1556
1557 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1558                        size_t bufsize, size_t *bufposn)
1559 {
1560         char tmpfile[PATH_MAX];
1561         int local;
1562         z_stream stream;
1563         unsigned char real_sha1[20];
1564         unsigned char discard[4096];
1565         int ret;
1566         SHA_CTX c;
1567
1568         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1569
1570         local = mkstemp(tmpfile);
1571         if (local < 0)
1572                 return error("Couldn't open %s for %s",
1573                              tmpfile, sha1_to_hex(sha1));
1574
1575         memset(&stream, 0, sizeof(stream));
1576
1577         inflateInit(&stream);
1578
1579         SHA1_Init(&c);
1580
1581         do {
1582                 ssize_t size;
1583                 if (*bufposn) {
1584                         stream.avail_in = *bufposn;
1585                         stream.next_in = (unsigned char *) buffer;
1586                         do {
1587                                 stream.next_out = discard;
1588                                 stream.avail_out = sizeof(discard);
1589                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1590                                 SHA1_Update(&c, discard, sizeof(discard) -
1591                                             stream.avail_out);
1592                         } while (stream.avail_in && ret == Z_OK);
1593                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1594                                 die("unable to write sha1 file");
1595                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1596                                 stream.avail_in);
1597                         *bufposn = stream.avail_in;
1598                         if (ret != Z_OK)
1599                                 break;
1600                 }
1601                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1602                 if (size <= 0) {
1603                         close(local);
1604                         unlink(tmpfile);
1605                         if (!size)
1606                                 return error("Connection closed?");
1607                         perror("Reading from connection");
1608                         return -1;
1609                 }
1610                 *bufposn += size;
1611         } while (1);
1612         inflateEnd(&stream);
1613
1614         close(local);
1615         SHA1_Final(real_sha1, &c);
1616         if (ret != Z_STREAM_END) {
1617                 unlink(tmpfile);
1618                 return error("File %s corrupted", sha1_to_hex(sha1));
1619         }
1620         if (memcmp(sha1, real_sha1, 20)) {
1621                 unlink(tmpfile);
1622                 return error("File %s has bad hash", sha1_to_hex(sha1));
1623         }
1624
1625         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1626 }
1627
1628 int has_pack_index(const unsigned char *sha1)
1629 {
1630         struct stat st;
1631         if (stat(sha1_pack_index_name(sha1), &st))
1632                 return 0;
1633         return 1;
1634 }
1635
1636 int has_pack_file(const unsigned char *sha1)
1637 {
1638         struct stat st;
1639         if (stat(sha1_pack_name(sha1), &st))
1640                 return 0;
1641         return 1;
1642 }
1643
1644 int has_sha1_pack(const unsigned char *sha1)
1645 {
1646         struct pack_entry e;
1647         return find_pack_entry(sha1, &e);
1648 }
1649
1650 int has_sha1_file(const unsigned char *sha1)
1651 {
1652         struct stat st;
1653         struct pack_entry e;
1654
1655         if (find_pack_entry(sha1, &e))
1656                 return 1;
1657         return find_sha1_file(sha1, &st) ? 1 : 0;
1658 }
1659
1660 /*
1661  * reads from fd as long as possible into a supplied buffer of size bytes.
1662  * If neccessary the buffer's size is increased using realloc()
1663  *
1664  * returns 0 if anything went fine and -1 otherwise
1665  *
1666  * NOTE: both buf and size may change, but even when -1 is returned
1667  * you still have to free() it yourself.
1668  */
1669 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1670 {
1671         char* buf = *return_buf;
1672         unsigned long size = *return_size;
1673         int iret;
1674         unsigned long off = 0;
1675
1676         do {
1677                 iret = xread(fd, buf + off, size - off);
1678                 if (iret > 0) {
1679                         off += iret;
1680                         if (off == size) {
1681                                 size *= 2;
1682                                 buf = realloc(buf, size);
1683                         }
1684                 }
1685         } while (iret > 0);
1686
1687         *return_buf = buf;
1688         *return_size = off;
1689
1690         if (iret < 0)
1691                 return -1;
1692         return 0;
1693 }
1694
1695 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1696 {
1697         unsigned long size = 4096;
1698         char *buf = malloc(size);
1699         int ret;
1700         unsigned char hdr[50];
1701         int hdrlen;
1702
1703         if (read_pipe(fd, &buf, &size)) {
1704                 free(buf);
1705                 return -1;
1706         }
1707
1708         if (!type)
1709                 type = blob_type;
1710         if (write_object)
1711                 ret = write_sha1_file(buf, size, type, sha1);
1712         else {
1713                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1714                 ret = 0;
1715         }
1716         free(buf);
1717         return ret;
1718 }
1719
1720 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1721 {
1722         unsigned long size = st->st_size;
1723         void *buf;
1724         int ret;
1725         unsigned char hdr[50];
1726         int hdrlen;
1727
1728         buf = "";
1729         if (size)
1730                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1731         close(fd);
1732         if (buf == MAP_FAILED)
1733                 return -1;
1734
1735         if (!type)
1736                 type = blob_type;
1737         if (write_object)
1738                 ret = write_sha1_file(buf, size, type, sha1);
1739         else {
1740                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1741                 ret = 0;
1742         }
1743         if (size)
1744                 munmap(buf, size);
1745         return ret;
1746 }
1747
1748 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1749 {
1750         int fd;
1751         char *target;
1752
1753         switch (st->st_mode & S_IFMT) {
1754         case S_IFREG:
1755                 fd = open(path, O_RDONLY);
1756                 if (fd < 0)
1757                         return error("open(\"%s\"): %s", path,
1758                                      strerror(errno));
1759                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1760                         return error("%s: failed to insert into database",
1761                                      path);
1762                 break;
1763         case S_IFLNK:
1764                 target = xmalloc(st->st_size+1);
1765                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1766                         char *errstr = strerror(errno);
1767                         free(target);
1768                         return error("readlink(\"%s\"): %s", path,
1769                                      errstr);
1770                 }
1771                 if (!write_object) {
1772                         unsigned char hdr[50];
1773                         int hdrlen;
1774                         write_sha1_file_prepare(target, st->st_size, blob_type,
1775                                                 sha1, hdr, &hdrlen);
1776                 } else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1777                         return error("%s: failed to insert into database",
1778                                      path);
1779                 free(target);
1780                 break;
1781         default:
1782                 return error("%s: unsupported file type", path);
1783         }
1784         return 0;
1785 }