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 <sys/types.h>
  10 #include <dirent.h>
  11 #include "cache.h"
  12 #include "delta.h"
  13 #include "pack.h"
  14
  15 #ifndef O_NOATIME
  16 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  17 #define O_NOATIME 01000000
  18 #else
  19 #define O_NOATIME 0
  20 #endif
  21 #endif
  22
  23 static unsigned int sha1_file_open_flag = O_NOATIME;
  24
  25 static unsigned hexval(char c)
  26 {
  27         if (c >= '0' && c <= '9')
  28                 return c - '0';
  29         if (c >= 'a' && c <= 'f')
  30                 return c - 'a' + 10;
  31         if (c >= 'A' && c <= 'F')
  32                 return c - 'A' + 10;
  33         return ~0;
  34 }
  35
  36 int get_sha1_hex(const char *hex, unsigned char *sha1)
  37 {
  38         int i;
  39         for (i = 0; i < 20; i++) {
  40                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  41                 if (val & ~0xff)
  42                         return -1;
  43                 *sha1++ = val;
  44                 hex += 2;
  45         }
  46         return 0;
  47 }
  48
  49 static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir,
  50         *git_graft_file;
  51 static void setup_git_env(void)
  52 {
  53         git_dir = gitenv(GIT_DIR_ENVIRONMENT);
  54         if (!git_dir)
  55                 git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
  56         git_object_dir = gitenv(DB_ENVIRONMENT);
  57         if (!git_object_dir) {
  58                 git_object_dir = xmalloc(strlen(git_dir) + 9);
  59                 sprintf(git_object_dir, "%s/objects", git_dir);
  60         }
  61         git_refs_dir = xmalloc(strlen(git_dir) + 6);
  62         sprintf(git_refs_dir, "%s/refs", git_dir);
  63         git_index_file = gitenv(INDEX_ENVIRONMENT);
  64         if (!git_index_file) {
  65                 git_index_file = xmalloc(strlen(git_dir) + 7);
  66                 sprintf(git_index_file, "%s/index", git_dir);
  67         }
  68         git_graft_file = gitenv(GRAFT_ENVIRONMENT);
  69         if (!git_graft_file)
  70                 git_graft_file = strdup(git_path("info/grafts"));
  71 }
  72
  73 char *get_object_directory(void)
  74 {
  75         if (!git_object_dir)
  76                 setup_git_env();
  77         return git_object_dir;
  78 }
  79
  80 char *get_refs_directory(void)
  81 {
  82         if (!git_refs_dir)
  83                 setup_git_env();
  84         return git_refs_dir;
  85 }
  86
  87 char *get_index_file(void)
  88 {
  89         if (!git_index_file)
  90                 setup_git_env();
  91         return git_index_file;
  92 }
  93
  94 char *get_graft_file(void)
  95 {
  96         if (!git_graft_file)
  97                 setup_git_env();
  98         return git_graft_file;
  99 }
 100
 101 int safe_create_leading_directories(char *path)
 102 {
 103         char *pos = path;
 104
 105         while (pos) {
 106                 pos = strchr(pos, '/');
 107                 if (!pos)
 108                         break;
 109                 *pos = 0;
 110                 if (mkdir(path, 0777) < 0)
 111                         if (errno != EEXIST) {
 112                                 *pos = '/';
 113                                 return -1;
 114                         }
 115                 *pos++ = '/';
 116         }
 117         return 0;
 118 }
 119
 120 char * sha1_to_hex(const unsigned char *sha1)
 121 {
 122         static char buffer[50];
 123         static const char hex[] = "0123456789abcdef";
 124         char *buf = buffer;
 125         int i;
 126
 127         for (i = 0; i < 20; i++) {
 128                 unsigned int val = *sha1++;
 129                 *buf++ = hex[val >> 4];
 130                 *buf++ = hex[val & 0xf];
 131         }
 132         return buffer;
 133 }
 134
 135 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 136 {
 137         int i;
 138         for (i = 0; i < 20; i++) {
 139                 static char hex[] = "0123456789abcdef";
 140                 unsigned int val = sha1[i];
 141                 char *pos = pathbuf + i*2 + (i > 0);
 142                 *pos++ = hex[val >> 4];
 143                 *pos = hex[val & 0xf];
 144         }
 145 }
 146
 147 /*
 148  * NOTE! This returns a statically allocated buffer, so you have to be
 149  * careful about using it. Do a "strdup()" if you need to save the
 150  * filename.
 151  *
 152  * Also note that this returns the location for creating.  Reading
 153  * SHA1 file can happen from any alternate directory listed in the
 154  * DB_ENVIRONMENT environment variable if it is not found in
 155  * the primary object database.
 156  */
 157 char *sha1_file_name(const unsigned char *sha1)
 158 {
 159         static char *name, *base;
 160
 161         if (!base) {
 162                 const char *sha1_file_directory = get_object_directory();
 163                 int len = strlen(sha1_file_directory);
 164                 base = xmalloc(len + 60);
 165                 memcpy(base, sha1_file_directory, len);
 166                 memset(base+len, 0, 60);
 167                 base[len] = '/';
 168                 base[len+3] = '/';
 169                 name = base + len + 1;
 170         }
 171         fill_sha1_path(name, sha1);
 172         return base;
 173 }
 174
 175 char *sha1_pack_name(const unsigned char *sha1)
 176 {
 177         static const char hex[] = "0123456789abcdef";
 178         static char *name, *base, *buf;
 179         int i;
 180
 181         if (!base) {
 182                 const char *sha1_file_directory = get_object_directory();
 183                 int len = strlen(sha1_file_directory);
 184                 base = xmalloc(len + 60);
 185                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 186                 name = base + len + 11;
 187         }
 188
 189         buf = name;
 190
 191         for (i = 0; i < 20; i++) {
 192                 unsigned int val = *sha1++;
 193                 *buf++ = hex[val >> 4];
 194                 *buf++ = hex[val & 0xf];
 195         }
 196
 197         return base;
 198 }
 199
 200 char *sha1_pack_index_name(const unsigned char *sha1)
 201 {
 202         static const char hex[] = "0123456789abcdef";
 203         static char *name, *base, *buf;
 204         int i;
 205
 206         if (!base) {
 207                 const char *sha1_file_directory = get_object_directory();
 208                 int len = strlen(sha1_file_directory);
 209                 base = xmalloc(len + 60);
 210                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 211                 name = base + len + 11;
 212         }
 213
 214         buf = name;
 215
 216         for (i = 0; i < 20; i++) {
 217                 unsigned int val = *sha1++;
 218                 *buf++ = hex[val >> 4];
 219                 *buf++ = hex[val & 0xf];
 220         }
 221
 222         return base;
 223 }
 224
 225 struct alternate_object_database *alt_odb;
 226
 227 /*
 228  * Prepare alternate object database registry.
 229  * alt_odb points at an array of struct alternate_object_database.
 230  * This array is terminated with an element that has both its base
 231  * and name set to NULL.  alt_odb[n] comes from n'th non-empty
 232  * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
 233  * variable, and its base points at a statically allocated buffer
 234  * that contains "/the/directory/corresponding/to/.git/objects/...",
 235  * while its name points just after the slash at the end of
 236  * ".git/objects/" in the example above, and has enough space to hold
 237  * 40-byte hex SHA1, an extra slash for the first level indirection,
 238  * and the terminating NUL.
 239  * This function allocates the alt_odb array and all the strings
 240  * pointed by base fields of the array elements with one xmalloc();
 241  * the string pool immediately follows the array.
 242  */
 243 void prepare_alt_odb(void)
 244 {
 245         int pass, totlen, i;
 246         const char *cp, *last;
 247         char *op = NULL;
 248         const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
 249
 250         if (alt_odb)
 251                 return;
 252         /* The first pass counts how large an area to allocate to
 253          * hold the entire alt_odb structure, including array of
 254          * structs and path buffers for them.  The second pass fills
 255          * the structure and prepares the path buffers for use by
 256          * fill_sha1_path().
 257          */
 258         for (totlen = pass = 0; pass < 2; pass++) {
 259                 last = alt;
 260                 i = 0;
 261                 do {
 262                         cp = strchr(last, ':') ? : last + strlen(last);
 263                         if (last != cp) {
 264                                 /* 43 = 40-byte + 2 '/' + terminating NUL */
 265                                 int pfxlen = cp - last;
 266                                 int entlen = pfxlen + 43;
 267                                 if (pass == 0)
 268                                         totlen += entlen;
 269                                 else {
 270                                         alt_odb[i].base = op;
 271                                         alt_odb[i].name = op + pfxlen + 1;
 272                                         memcpy(op, last, pfxlen);
 273                                         op[pfxlen] = op[pfxlen + 3] = '/';
 274                                         op[entlen-1] = 0;
 275                                         op += entlen;
 276                                 }
 277                                 i++;
 278                         }
 279                         while (*cp && *cp == ':')
 280                                 cp++;
 281                         last = cp;
 282                 } while (*cp);
 283                 if (pass)
 284                         break;
 285                 alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
 286                 alt_odb[i].base = alt_odb[i].name = NULL;
 287                 op = (char*)(&alt_odb[i+1]);
 288         }
 289 }
 290
 291 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 292 {
 293         int i;
 294         char *name = sha1_file_name(sha1);
 295
 296         if (!stat(name, st))
 297                 return name;
 298         prepare_alt_odb();
 299         for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
 300                 fill_sha1_path(name, sha1);
 301                 if (!stat(alt_odb[i].base, st))
 302                         return alt_odb[i].base;
 303         }
 304         return NULL;
 305 }
 306
 307 #define PACK_MAX_SZ (1<<26)
 308 static int pack_used_ctr;
 309 static unsigned long pack_mapped;
 310 struct packed_git *packed_git;
 311
 312 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 313                                 void **idx_map_)
 314 {
 315         void *idx_map;
 316         unsigned int *index;
 317         unsigned long idx_size;
 318         int nr, i;
 319         int fd = open(path, O_RDONLY);
 320         struct stat st;
 321         if (fd < 0)
 322                 return -1;
 323         if (fstat(fd, &st)) {
 324                 close(fd);
 325                 return -1;
 326         }
 327         idx_size = st.st_size;
 328         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 329         close(fd);
 330         if (idx_map == MAP_FAILED)
 331                 return -1;
 332
 333         index = idx_map;
 334         *idx_map_ = idx_map;
 335         *idx_size_ = idx_size;
 336
 337         /* check index map */
 338         if (idx_size < 4*256 + 20 + 20)
 339                 return error("index file too small");
 340         nr = 0;
 341         for (i = 0; i < 256; i++) {
 342                 unsigned int n = ntohl(index[i]);
 343                 if (n < nr)
 344                         return error("non-monotonic index");
 345                 nr = n;
 346         }
 347
 348         /*
 349          * Total size:
 350          *  - 256 index entries 4 bytes each
 351          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 352          *  - 20-byte SHA1 of the packfile
 353          *  - 20-byte SHA1 file checksum
 354          */
 355         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 356                 return error("wrong index file size");
 357
 358         return 0;
 359 }
 360
 361 static int unuse_one_packed_git(void)
 362 {
 363         struct packed_git *p, *lru = NULL;
 364
 365         for (p = packed_git; p; p = p->next) {
 366                 if (p->pack_use_cnt || !p->pack_base)
 367                         continue;
 368                 if (!lru || p->pack_last_used < lru->pack_last_used)
 369                         lru = p;
 370         }
 371         if (!lru)
 372                 return 0;
 373         munmap(lru->pack_base, lru->pack_size);
 374         lru->pack_base = NULL;
 375         return 1;
 376 }
 377
 378 void unuse_packed_git(struct packed_git *p)
 379 {
 380         p->pack_use_cnt--;
 381 }
 382
 383 int use_packed_git(struct packed_git *p)
 384 {
 385         if (!p->pack_size) {
 386                 struct stat st;
 387                 // We created the struct before we had the pack
 388                 stat(p->pack_name, &st);
 389                 if (!S_ISREG(st.st_mode))
 390                         die("packfile %s not a regular file", p->pack_name);
 391                 p->pack_size = st.st_size;
 392         }
 393         if (!p->pack_base) {
 394                 int fd;
 395                 struct stat st;
 396                 void *map;
 397
 398                 pack_mapped += p->pack_size;
 399                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 400                         ; /* nothing */
 401                 fd = open(p->pack_name, O_RDONLY);
 402                 if (fd < 0)
 403                         die("packfile %s cannot be opened", p->pack_name);
 404                 if (fstat(fd, &st)) {
 405                         close(fd);
 406                         die("packfile %s cannot be opened", p->pack_name);
 407                 }
 408                 if (st.st_size != p->pack_size)
 409                         die("packfile %s size mismatch.", p->pack_name);
 410                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 411                 close(fd);
 412                 if (map == MAP_FAILED)
 413                         die("packfile %s cannot be mapped.", p->pack_name);
 414                 p->pack_base = map;
 415
 416                 /* Check if the pack file matches with the index file.
 417                  * this is cheap.
 418                  */
 419                 if (memcmp((char*)(p->index_base) + p->index_size - 40,
 420                            p->pack_base + p->pack_size - 20, 20)) {
 421
 422                         die("packfile %s does not match index.", p->pack_name);
 423                 }
 424         }
 425         p->pack_last_used = pack_used_ctr++;
 426         p->pack_use_cnt++;
 427         return 0;
 428 }
 429
 430 struct packed_git *add_packed_git(char *path, int path_len)
 431 {
 432         struct stat st;
 433         struct packed_git *p;
 434         unsigned long idx_size;
 435         void *idx_map;
 436
 437         if (check_packed_git_idx(path, &idx_size, &idx_map))
 438                 return NULL;
 439
 440         /* do we have a corresponding .pack file? */
 441         strcpy(path + path_len - 4, ".pack");
 442         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 443                 munmap(idx_map, idx_size);
 444                 return NULL;
 445         }
 446         /* ok, it looks sane as far as we can check without
 447          * actually mapping the pack file.
 448          */
 449         p = xmalloc(sizeof(*p) + path_len + 2);
 450         strcpy(p->pack_name, path);
 451         p->index_size = idx_size;
 452         p->pack_size = st.st_size;
 453         p->index_base = idx_map;
 454         p->next = NULL;
 455         p->pack_base = NULL;
 456         p->pack_last_used = 0;
 457         p->pack_use_cnt = 0;
 458         return p;
 459 }
 460
 461 struct packed_git *parse_pack_index(unsigned char *sha1)
 462 {
 463         struct packed_git *p;
 464         unsigned long idx_size;
 465         void *idx_map;
 466         char *path = sha1_pack_index_name(sha1);
 467
 468         if (check_packed_git_idx(path, &idx_size, &idx_map))
 469                 return NULL;
 470
 471         path = sha1_pack_name(sha1);
 472
 473         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 474         strcpy(p->pack_name, path);
 475         p->index_size = idx_size;
 476         p->pack_size = 0;
 477         p->index_base = idx_map;
 478         p->next = NULL;
 479         p->pack_base = NULL;
 480         p->pack_last_used = 0;
 481         p->pack_use_cnt = 0;
 482         memcpy(p->sha1, sha1, 20);
 483         return p;
 484 }
 485
 486 void install_packed_git(struct packed_git *pack)
 487 {
 488         pack->next = packed_git;
 489         packed_git = pack;
 490 }
 491
 492 static void prepare_packed_git_one(char *objdir)
 493 {
 494         char path[PATH_MAX];
 495         int len;
 496         DIR *dir;
 497         struct dirent *de;
 498
 499         sprintf(path, "%s/pack", objdir);
 500         len = strlen(path);
 501         dir = opendir(path);
 502         if (!dir)
 503                 return;
 504         path[len++] = '/';
 505         while ((de = readdir(dir)) != NULL) {
 506                 int namelen = strlen(de->d_name);
 507                 struct packed_git *p;
 508
 509                 if (strcmp(de->d_name + namelen - 4, ".idx"))
 510                         continue;
 511
 512                 /* we have .idx.  Is it a file we can map? */
 513                 strcpy(path + len, de->d_name);
 514                 p = add_packed_git(path, len + namelen);
 515                 if (!p)
 516                         continue;
 517                 p->next = packed_git;
 518                 packed_git = p;
 519         }
 520         closedir(dir);
 521 }
 522
 523 void prepare_packed_git(void)
 524 {
 525         int i;
 526         static int run_once = 0;
 527
 528         if (run_once++)
 529                 return;
 530
 531         prepare_packed_git_one(get_object_directory());
 532         prepare_alt_odb();
 533         for (i = 0; alt_odb[i].base != NULL; i++) {
 534                 alt_odb[i].name[0] = 0;
 535                 prepare_packed_git_one(alt_odb[i].base);
 536         }
 537 }
 538
 539 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 540 {
 541         char header[100];
 542         unsigned char real_sha1[20];
 543         SHA_CTX c;
 544
 545         SHA1_Init(&c);
 546         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 547         SHA1_Update(&c, map, size);
 548         SHA1_Final(real_sha1, &c);
 549         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 550 }
 551
 552 static void *map_sha1_file_internal(const unsigned char *sha1,
 553                                     unsigned long *size)
 554 {
 555         struct stat st;
 556         void *map;
 557         int fd;
 558         char *filename = find_sha1_file(sha1, &st);
 559
 560         if (!filename) {
 561                 return NULL;
 562         }
 563
 564         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 565         if (fd < 0) {
 566                 /* See if it works without O_NOATIME */
 567                 switch (sha1_file_open_flag) {
 568                 default:
 569                         fd = open(filename, O_RDONLY);
 570                         if (fd >= 0)
 571                                 break;
 572                 /* Fallthrough */
 573                 case 0:
 574                         return NULL;
 575                 }
 576
 577                 /* If it failed once, it will probably fail again.
 578                  * Stop using O_NOATIME
 579                  */
 580                 sha1_file_open_flag = 0;
 581         }
 582         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 583         close(fd);
 584         if (map == MAP_FAILED)
 585                 return NULL;
 586         *size = st.st_size;
 587         return map;
 588 }
 589
 590 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 591 {
 592         /* Get the data stream */
 593         memset(stream, 0, sizeof(*stream));
 594         stream->next_in = map;
 595         stream->avail_in = mapsize;
 596         stream->next_out = buffer;
 597         stream->avail_out = size;
 598
 599         inflateInit(stream);
 600         return inflate(stream, 0);
 601 }
 602
 603 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 604 {
 605         int bytes = strlen(buffer) + 1;
 606         unsigned char *buf = xmalloc(1+size);
 607
 608         memcpy(buf, buffer + bytes, stream->total_out - bytes);
 609         bytes = stream->total_out - bytes;
 610         if (bytes < size) {
 611                 stream->next_out = buf + bytes;
 612                 stream->avail_out = size - bytes;
 613                 while (inflate(stream, Z_FINISH) == Z_OK)
 614                         /* nothing */;
 615         }
 616         buf[size] = 0;
 617         inflateEnd(stream);
 618         return buf;
 619 }
 620
 621 /*
 622  * We used to just use "sscanf()", but that's actually way
 623  * too permissive for what we want to check. So do an anal
 624  * object header parse by hand.
 625  */
 626 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 627 {
 628         int i;
 629         unsigned long size;
 630
 631         /*
 632          * The type can be at most ten bytes (including the
 633          * terminating '\0' that we add), and is followed by
 634          * a space.
 635          */
 636         i = 10;
 637         for (;;) {
 638                 char c = *hdr++;
 639                 if (c == ' ')
 640                         break;
 641                 if (!--i)
 642                         return -1;
 643                 *type++ = c;
 644         }
 645         *type = 0;
 646
 647         /*
 648          * The length must follow immediately, and be in canonical
 649          * decimal format (ie "010" is not valid).
 650          */
 651         size = *hdr++ - '0';
 652         if (size > 9)
 653                 return -1;
 654         if (size) {
 655                 for (;;) {
 656                         unsigned long c = *hdr - '0';
 657                         if (c > 9)
 658                                 break;
 659                         hdr++;
 660                         size = size * 10 + c;
 661                 }
 662         }
 663         *sizep = size;
 664
 665         /*
 666          * The length must be followed by a zero byte
 667          */
 668         return *hdr ? -1 : 0;
 669 }
 670
 671 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 672 {
 673         int ret;
 674         z_stream stream;
 675         char hdr[8192];
 676
 677         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 678         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 679                 return NULL;
 680
 681         return unpack_sha1_rest(&stream, hdr, *size);
 682 }
 683
 684 /* forward declaration for a mutually recursive function */
 685 static int packed_object_info(struct pack_entry *entry,
 686                               char *type, unsigned long *sizep);
 687
 688 static int packed_delta_info(unsigned char *base_sha1,
 689                              unsigned long delta_size,
 690                              unsigned long left,
 691                              char *type,
 692                              unsigned long *sizep,
 693                              struct packed_git *p)
 694 {
 695         struct pack_entry base_ent;
 696
 697         if (left < 20)
 698                 die("truncated pack file");
 699
 700         /* The base entry _must_ be in the same pack */
 701         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 702                 die("failed to find delta-pack base object %s",
 703                     sha1_to_hex(base_sha1));
 704
 705         /* We choose to only get the type of the base object and
 706          * ignore potentially corrupt pack file that expects the delta
 707          * based on a base with a wrong size.  This saves tons of
 708          * inflate() calls.
 709          */
 710
 711         if (packed_object_info(&base_ent, type, NULL))
 712                 die("cannot get info for delta-pack base");
 713
 714         if (sizep) {
 715                 const unsigned char *data;
 716                 unsigned char delta_head[64];
 717                 unsigned long result_size;
 718                 z_stream stream;
 719                 int st;
 720
 721                 memset(&stream, 0, sizeof(stream));
 722
 723                 data = stream.next_in = base_sha1 + 20;
 724                 stream.avail_in = left - 20;
 725                 stream.next_out = delta_head;
 726                 stream.avail_out = sizeof(delta_head);
 727
 728                 inflateInit(&stream);
 729                 st = inflate(&stream, Z_FINISH);
 730                 inflateEnd(&stream);
 731                 if ((st != Z_STREAM_END) &&
 732                     stream.total_out != sizeof(delta_head))
 733                         die("delta data unpack-initial failed");
 734
 735                 /* Examine the initial part of the delta to figure out
 736                  * the result size.
 737                  */
 738                 data = delta_head;
 739                 get_delta_hdr_size(&data); /* ignore base size */
 740
 741                 /* Read the result size */
 742                 result_size = get_delta_hdr_size(&data);
 743                 *sizep = result_size;
 744         }
 745         return 0;
 746 }
 747
 748 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 749         enum object_type *type, unsigned long *sizep)
 750 {
 751         unsigned shift;
 752         unsigned char *pack, c;
 753         unsigned long size;
 754
 755         if (offset >= p->pack_size)
 756                 die("object offset outside of pack file");
 757
 758         pack =  p->pack_base + offset;
 759         c = *pack++;
 760         offset++;
 761         *type = (c >> 4) & 7;
 762         size = c & 15;
 763         shift = 4;
 764         while (c & 0x80) {
 765                 if (offset >= p->pack_size)
 766                         die("object offset outside of pack file");
 767                 c = *pack++;
 768                 offset++;
 769                 size += (c & 0x7f) << shift;
 770                 shift += 7;
 771         }
 772         *sizep = size;
 773         return offset;
 774 }
 775
 776 void packed_object_info_detail(struct pack_entry *e,
 777                                char *type,
 778                                unsigned long *size,
 779                                unsigned long *store_size,
 780                                int *delta_chain_length,
 781                                unsigned char *base_sha1)
 782 {
 783         struct packed_git *p = e->p;
 784         unsigned long offset, left;
 785         unsigned char *pack;
 786         enum object_type kind;
 787
 788         offset = unpack_object_header(p, e->offset, &kind, size);
 789         pack = p->pack_base + offset;
 790         left = p->pack_size - offset;
 791         if (kind != OBJ_DELTA)
 792                 *delta_chain_length = 0;
 793         else {
 794                 int chain_length = 0;
 795                 memcpy(base_sha1, pack, 20);
 796                 do {
 797                         struct pack_entry base_ent;
 798                         unsigned long junk;
 799
 800                         find_pack_entry_one(pack, &base_ent, p);
 801                         offset = unpack_object_header(p, base_ent.offset,
 802                                                       &kind, &junk);
 803                         pack = p->pack_base + offset;
 804                         chain_length++;
 805                 } while (kind == OBJ_DELTA);
 806                 *delta_chain_length = chain_length;
 807         }
 808         switch (kind) {
 809         case OBJ_COMMIT:
 810                 strcpy(type, "commit");
 811                 break;
 812         case OBJ_TREE:
 813                 strcpy(type, "tree");
 814                 break;
 815         case OBJ_BLOB:
 816                 strcpy(type, "blob");
 817                 break;
 818         case OBJ_TAG:
 819                 strcpy(type, "tag");
 820                 break;
 821         default:
 822                 die("corrupted pack file");
 823         }
 824         *store_size = 0; /* notyet */
 825 }
 826
 827 static int packed_object_info(struct pack_entry *entry,
 828                               char *type, unsigned long *sizep)
 829 {
 830         struct packed_git *p = entry->p;
 831         unsigned long offset, size, left;
 832         unsigned char *pack;
 833         enum object_type kind;
 834         int retval;
 835
 836         if (use_packed_git(p))
 837                 die("cannot map packed file");
 838
 839         offset = unpack_object_header(p, entry->offset, &kind, &size);
 840         pack = p->pack_base + offset;
 841         left = p->pack_size - offset;
 842
 843         switch (kind) {
 844         case OBJ_DELTA:
 845                 retval = packed_delta_info(pack, size, left, type, sizep, p);
 846                 unuse_packed_git(p);
 847                 return retval;
 848         case OBJ_COMMIT:
 849                 strcpy(type, "commit");
 850                 break;
 851         case OBJ_TREE:
 852                 strcpy(type, "tree");
 853                 break;
 854         case OBJ_BLOB:
 855                 strcpy(type, "blob");
 856                 break;
 857         case OBJ_TAG:
 858                 strcpy(type, "tag");
 859                 break;
 860         default:
 861                 die("corrupted pack file");
 862         }
 863         if (sizep)
 864                 *sizep = size;
 865         unuse_packed_git(p);
 866         return 0;
 867 }
 868
 869 /* forward declaration for a mutually recursive function */
 870 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 871
 872 static void *unpack_delta_entry(unsigned char *base_sha1,
 873                                 unsigned long delta_size,
 874                                 unsigned long left,
 875                                 char *type,
 876                                 unsigned long *sizep,
 877                                 struct packed_git *p)
 878 {
 879         struct pack_entry base_ent;
 880         void *data, *delta_data, *result, *base;
 881         unsigned long data_size, result_size, base_size;
 882         z_stream stream;
 883         int st;
 884
 885         if (left < 20)
 886                 die("truncated pack file");
 887         data = base_sha1 + 20;
 888         data_size = left - 20;
 889         delta_data = xmalloc(delta_size);
 890
 891         memset(&stream, 0, sizeof(stream));
 892
 893         stream.next_in = data;
 894         stream.avail_in = data_size;
 895         stream.next_out = delta_data;
 896         stream.avail_out = delta_size;
 897
 898         inflateInit(&stream);
 899         st = inflate(&stream, Z_FINISH);
 900         inflateEnd(&stream);
 901         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 902                 die("delta data unpack failed");
 903
 904         /* The base entry _must_ be in the same pack */
 905         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 906                 die("failed to find delta-pack base object %s",
 907                     sha1_to_hex(base_sha1));
 908         base = unpack_entry_gently(&base_ent, type, &base_size);
 909         if (!base)
 910                 die("failed to read delta-pack base object %s",
 911                     sha1_to_hex(base_sha1));
 912         result = patch_delta(base, base_size,
 913                              delta_data, delta_size,
 914                              &result_size);
 915         if (!result)
 916                 die("failed to apply delta");
 917         free(delta_data);
 918         free(base);
 919         *sizep = result_size;
 920         return result;
 921 }
 922
 923 static void *unpack_non_delta_entry(unsigned char *data,
 924                                     unsigned long size,
 925                                     unsigned long left)
 926 {
 927         int st;
 928         z_stream stream;
 929         unsigned char *buffer;
 930
 931         buffer = xmalloc(size + 1);
 932         buffer[size] = 0;
 933         memset(&stream, 0, sizeof(stream));
 934         stream.next_in = data;
 935         stream.avail_in = left;
 936         stream.next_out = buffer;
 937         stream.avail_out = size;
 938
 939         inflateInit(&stream);
 940         st = inflate(&stream, Z_FINISH);
 941         inflateEnd(&stream);
 942         if ((st != Z_STREAM_END) || stream.total_out != size) {
 943                 free(buffer);
 944                 return NULL;
 945         }
 946
 947         return buffer;
 948 }
 949
 950 static void *unpack_entry(struct pack_entry *entry,
 951                           char *type, unsigned long *sizep)
 952 {
 953         struct packed_git *p = entry->p;
 954         void *retval;
 955
 956         if (use_packed_git(p))
 957                 die("cannot map packed file");
 958         retval = unpack_entry_gently(entry, type, sizep);
 959         unuse_packed_git(p);
 960         if (!retval)
 961                 die("corrupted pack file");
 962         return retval;
 963 }
 964
 965 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
 966 void *unpack_entry_gently(struct pack_entry *entry,
 967                           char *type, unsigned long *sizep)
 968 {
 969         struct packed_git *p = entry->p;
 970         unsigned long offset, size, left;
 971         unsigned char *pack;
 972         enum object_type kind;
 973         void *retval;
 974
 975         offset = unpack_object_header(p, entry->offset, &kind, &size);
 976         pack = p->pack_base + offset;
 977         left = p->pack_size - offset;
 978         switch (kind) {
 979         case OBJ_DELTA:
 980                 retval = unpack_delta_entry(pack, size, left, type, sizep, p);
 981                 return retval;
 982         case OBJ_COMMIT:
 983                 strcpy(type, "commit");
 984                 break;
 985         case OBJ_TREE:
 986                 strcpy(type, "tree");
 987                 break;
 988         case OBJ_BLOB:
 989                 strcpy(type, "blob");
 990                 break;
 991         case OBJ_TAG:
 992                 strcpy(type, "tag");
 993                 break;
 994         default:
 995                 return NULL;
 996         }
 997         *sizep = size;
 998         retval = unpack_non_delta_entry(pack, size, left);
 999         return retval;
1000 }
1001
1002 int num_packed_objects(const struct packed_git *p)
1003 {
1004         /* See check_packed_git_idx() */
1005         return (p->index_size - 20 - 20 - 4*256) / 24;
1006 }
1007
1008 int nth_packed_object_sha1(const struct packed_git *p, int n,
1009                            unsigned char* sha1)
1010 {
1011         void *index = p->index_base + 256;
1012         if (n < 0 || num_packed_objects(p) <= n)
1013                 return -1;
1014         memcpy(sha1, (index + 24 * n + 4), 20);
1015         return 0;
1016 }
1017
1018 int find_pack_entry_one(const unsigned char *sha1,
1019                         struct pack_entry *e, struct packed_git *p)
1020 {
1021         unsigned int *level1_ofs = p->index_base;
1022         int hi = ntohl(level1_ofs[*sha1]);
1023         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1024         void *index = p->index_base + 256;
1025
1026         do {
1027                 int mi = (lo + hi) / 2;
1028                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1029                 if (!cmp) {
1030                         e->offset = ntohl(*((int*)(index + 24 * mi)));
1031                         memcpy(e->sha1, sha1, 20);
1032                         e->p = p;
1033                         return 1;
1034                 }
1035                 if (cmp > 0)
1036                         hi = mi;
1037                 else
1038                         lo = mi+1;
1039         } while (lo < hi);
1040         return 0;
1041 }
1042
1043 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1044 {
1045         struct packed_git *p;
1046         prepare_packed_git();
1047
1048         for (p = packed_git; p; p = p->next) {
1049                 if (find_pack_entry_one(sha1, e, p))
1050                         return 1;
1051         }
1052         return 0;
1053 }
1054
1055 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1056                                   struct packed_git *packs)
1057 {
1058         struct packed_git *p;
1059         struct pack_entry e;
1060
1061         for (p = packs; p; p = p->next) {
1062                 if (find_pack_entry_one(sha1, &e, p))
1063                         return p;
1064         }
1065         return NULL;
1066
1067 }
1068
1069 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1070 {
1071         int status;
1072         unsigned long mapsize, size;
1073         void *map;
1074         z_stream stream;
1075         char hdr[128];
1076
1077         map = map_sha1_file_internal(sha1, &mapsize);
1078         if (!map) {
1079                 struct pack_entry e;
1080
1081                 if (!find_pack_entry(sha1, &e))
1082                         return error("unable to find %s", sha1_to_hex(sha1));
1083                 return packed_object_info(&e, type, sizep);
1084         }
1085         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1086                 status = error("unable to unpack %s header",
1087                                sha1_to_hex(sha1));
1088         if (parse_sha1_header(hdr, type, &size) < 0)
1089                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1090         else {
1091                 status = 0;
1092                 if (sizep)
1093                         *sizep = size;
1094         }
1095         inflateEnd(&stream);
1096         munmap(map, mapsize);
1097         return status;
1098 }
1099
1100 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1101 {
1102         struct pack_entry e;
1103
1104         if (!find_pack_entry(sha1, &e)) {
1105                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1106                 return NULL;
1107         }
1108         return unpack_entry(&e, type, size);
1109 }
1110
1111 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1112 {
1113         unsigned long mapsize;
1114         void *map, *buf;
1115         struct pack_entry e;
1116
1117         if (find_pack_entry(sha1, &e))
1118                 return read_packed_sha1(sha1, type, size);
1119         map = map_sha1_file_internal(sha1, &mapsize);
1120         if (map) {
1121                 buf = unpack_sha1_file(map, mapsize, type, size);
1122                 munmap(map, mapsize);
1123                 return buf;
1124         }
1125         return NULL;
1126 }
1127
1128 void *read_object_with_reference(const unsigned char *sha1,
1129                                  const char *required_type,
1130                                  unsigned long *size,
1131                                  unsigned char *actual_sha1_return)
1132 {
1133         char type[20];
1134         void *buffer;
1135         unsigned long isize;
1136         unsigned char actual_sha1[20];
1137
1138         memcpy(actual_sha1, sha1, 20);
1139         while (1) {
1140                 int ref_length = -1;
1141                 const char *ref_type = NULL;
1142
1143                 buffer = read_sha1_file(actual_sha1, type, &isize);
1144                 if (!buffer)
1145                         return NULL;
1146                 if (!strcmp(type, required_type)) {
1147                         *size = isize;
1148                         if (actual_sha1_return)
1149                                 memcpy(actual_sha1_return, actual_sha1, 20);
1150                         return buffer;
1151                 }
1152                 /* Handle references */
1153                 else if (!strcmp(type, "commit"))
1154                         ref_type = "tree ";
1155                 else if (!strcmp(type, "tag"))
1156                         ref_type = "object ";
1157                 else {
1158                         free(buffer);
1159                         return NULL;
1160                 }
1161                 ref_length = strlen(ref_type);
1162
1163                 if (memcmp(buffer, ref_type, ref_length) ||
1164                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
1165                         free(buffer);
1166                         return NULL;
1167                 }
1168                 /* Now we have the ID of the referred-to object in
1169                  * actual_sha1.  Check again. */
1170         }
1171 }
1172
1173 char *write_sha1_file_prepare(void *buf,
1174                               unsigned long len,
1175                               const char *type,
1176                               unsigned char *sha1,
1177                               unsigned char *hdr,
1178                               int *hdrlen)
1179 {
1180         SHA_CTX c;
1181
1182         /* Generate the header */
1183         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1184
1185         /* Sha1.. */
1186         SHA1_Init(&c);
1187         SHA1_Update(&c, hdr, *hdrlen);
1188         SHA1_Update(&c, buf, len);
1189         SHA1_Final(sha1, &c);
1190
1191         return sha1_file_name(sha1);
1192 }
1193
1194 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1195 {
1196         int size;
1197         unsigned char *compressed;
1198         z_stream stream;
1199         unsigned char sha1[20];
1200         char *filename;
1201         static char tmpfile[PATH_MAX];
1202         unsigned char hdr[50];
1203         int fd, hdrlen, ret;
1204
1205         /* Normally if we have it in the pack then we do not bother writing
1206          * it out into .git/objects/??/?{38} file.
1207          */
1208         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1209         if (returnsha1)
1210                 memcpy(returnsha1, sha1, 20);
1211         if (has_sha1_file(sha1))
1212                 return 0;
1213         fd = open(filename, O_RDONLY);
1214         if (fd >= 0) {
1215                 /*
1216                  * FIXME!!! We might do collision checking here, but we'd
1217                  * need to uncompress the old file and check it. Later.
1218                  */
1219                 close(fd);
1220                 return 0;
1221         }
1222
1223         if (errno != ENOENT) {
1224                 fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
1225                 return -1;
1226         }
1227
1228         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1229
1230         fd = mkstemp(tmpfile);
1231         if (fd < 0) {
1232                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
1233                 return -1;
1234         }
1235
1236         /* Set it up */
1237         memset(&stream, 0, sizeof(stream));
1238         deflateInit(&stream, Z_BEST_COMPRESSION);
1239         size = deflateBound(&stream, len+hdrlen);
1240         compressed = xmalloc(size);
1241
1242         /* Compress it */
1243         stream.next_out = compressed;
1244         stream.avail_out = size;
1245
1246         /* First header.. */
1247         stream.next_in = hdr;
1248         stream.avail_in = hdrlen;
1249         while (deflate(&stream, 0) == Z_OK)
1250                 /* nothing */;
1251
1252         /* Then the data itself.. */
1253         stream.next_in = buf;
1254         stream.avail_in = len;
1255         while (deflate(&stream, Z_FINISH) == Z_OK)
1256                 /* nothing */;
1257         deflateEnd(&stream);
1258         size = stream.total_out;
1259
1260         if (write(fd, compressed, size) != size)
1261                 die("unable to write file");
1262         fchmod(fd, 0444);
1263         close(fd);
1264         free(compressed);
1265
1266         ret = link(tmpfile, filename);
1267         if (ret < 0) {
1268                 ret = errno;
1269
1270                 /*
1271                  * Coda hack - coda doesn't like cross-directory links,
1272                  * so we fall back to a rename, which will mean that it
1273                  * won't be able to check collisions, but that's not a
1274                  * big deal.
1275                  *
1276                  * When this succeeds, we just return 0. We have nothing
1277                  * left to unlink.
1278                  */
1279                 if (ret == EXDEV && !rename(tmpfile, filename))
1280                         return 0;
1281         }
1282         unlink(tmpfile);
1283         if (ret) {
1284                 if (ret != EEXIST) {
1285                         fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1286                         return -1;
1287                 }
1288                 /* FIXME!!! Collision check here ? */
1289         }
1290
1291         return 0;
1292 }
1293
1294 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1295 {
1296         ssize_t size;
1297         unsigned long objsize;
1298         int posn = 0;
1299         void *buf = map_sha1_file_internal(sha1, &objsize);
1300         z_stream stream;
1301         if (!buf) {
1302                 unsigned char *unpacked;
1303                 unsigned long len;
1304                 char type[20];
1305                 char hdr[50];
1306                 int hdrlen;
1307                 // need to unpack and recompress it by itself
1308                 unpacked = read_packed_sha1(sha1, type, &len);
1309
1310                 hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1311
1312                 /* Set it up */
1313                 memset(&stream, 0, sizeof(stream));
1314                 deflateInit(&stream, Z_BEST_COMPRESSION);
1315                 size = deflateBound(&stream, len + hdrlen);
1316                 buf = xmalloc(size);
1317
1318                 /* Compress it */
1319                 stream.next_out = buf;
1320                 stream.avail_out = size;
1321
1322                 /* First header.. */
1323                 stream.next_in = (void *)hdr;
1324                 stream.avail_in = hdrlen;
1325                 while (deflate(&stream, 0) == Z_OK)
1326                         /* nothing */;
1327
1328                 /* Then the data itself.. */
1329                 stream.next_in = unpacked;
1330                 stream.avail_in = len;
1331                 while (deflate(&stream, Z_FINISH) == Z_OK)
1332                         /* nothing */;
1333                 deflateEnd(&stream);
1334
1335                 objsize = stream.total_out;
1336         }
1337
1338         do {
1339                 size = write(fd, buf + posn, objsize - posn);
1340                 if (size <= 0) {
1341                         if (!size) {
1342                                 fprintf(stderr, "write closed");
1343                         } else {
1344                                 perror("write ");
1345                         }
1346                         return -1;
1347                 }
1348                 posn += size;
1349         } while (posn < objsize);
1350         return 0;
1351 }
1352
1353 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1354                        size_t bufsize, size_t *bufposn)
1355 {
1356         char *filename = sha1_file_name(sha1);
1357
1358         int local;
1359         z_stream stream;
1360         unsigned char real_sha1[20];
1361         unsigned char discard[4096];
1362         int ret;
1363         SHA_CTX c;
1364
1365         local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
1366
1367         if (local < 0)
1368                 return error("Couldn't open %s\n", filename);
1369
1370         memset(&stream, 0, sizeof(stream));
1371
1372         inflateInit(&stream);
1373
1374         SHA1_Init(&c);
1375
1376         do {
1377                 ssize_t size;
1378                 if (*bufposn) {
1379                         stream.avail_in = *bufposn;
1380                         stream.next_in = buffer;
1381                         do {
1382                                 stream.next_out = discard;
1383                                 stream.avail_out = sizeof(discard);
1384                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1385                                 SHA1_Update(&c, discard, sizeof(discard) -
1386                                             stream.avail_out);
1387                         } while (stream.avail_in && ret == Z_OK);
1388                         write(local, buffer, *bufposn - stream.avail_in);
1389                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1390                                 stream.avail_in);
1391                         *bufposn = stream.avail_in;
1392                         if (ret != Z_OK)
1393                                 break;
1394                 }
1395                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1396                 if (size <= 0) {
1397                         close(local);
1398                         unlink(filename);
1399                         if (!size)
1400                                 return error("Connection closed?");
1401                         perror("Reading from connection");
1402                         return -1;
1403                 }
1404                 *bufposn += size;
1405         } while (1);
1406         inflateEnd(&stream);
1407
1408         close(local);
1409         SHA1_Final(real_sha1, &c);
1410         if (ret != Z_STREAM_END) {
1411                 unlink(filename);
1412                 return error("File %s corrupted", sha1_to_hex(sha1));
1413         }
1414         if (memcmp(sha1, real_sha1, 20)) {
1415                 unlink(filename);
1416                 return error("File %s has bad hash\n", sha1_to_hex(sha1));
1417         }
1418
1419         return 0;
1420 }
1421
1422 int has_pack_index(const unsigned char *sha1)
1423 {
1424         struct stat st;
1425         if (stat(sha1_pack_index_name(sha1), &st))
1426                 return 0;
1427         return 1;
1428 }
1429
1430 int has_pack_file(const unsigned char *sha1)
1431 {
1432         struct stat st;
1433         if (stat(sha1_pack_name(sha1), &st))
1434                 return 0;
1435         return 1;
1436 }
1437
1438 int has_sha1_pack(const unsigned char *sha1)
1439 {
1440         struct pack_entry e;
1441         return find_pack_entry(sha1, &e);
1442 }
1443
1444 int has_sha1_file(const unsigned char *sha1)
1445 {
1446         struct stat st;
1447         struct pack_entry e;
1448
1449         if (find_pack_entry(sha1, &e))
1450                 return 1;
1451         return find_sha1_file(sha1, &st) ? 1 : 0;
1452 }
1453
1454 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1455 {
1456         unsigned long size = st->st_size;
1457         void *buf;
1458         int ret;
1459         unsigned char hdr[50];
1460         int hdrlen;
1461
1462         buf = "";
1463         if (size)
1464                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1465         close(fd);
1466         if (buf == MAP_FAILED)
1467                 return -1;
1468
1469         if (!type)
1470                 type = "blob";
1471         if (write_object)
1472                 ret = write_sha1_file(buf, size, type, sha1);
1473         else {
1474                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1475                 ret = 0;
1476         }
1477         if (size)
1478                 munmap(buf, size);
1479         return ret;
1480 }