sha1_file.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include "cache.h"
  10 #include "delta.h"
  11 #include "pack.h"
  12 #include "blob.h"
  13 #include "commit.h"
  14 #include "tag.h"
  15 #include "tree.h"
  16
  17 #ifndef O_NOATIME
  18 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  19 #define O_NOATIME 01000000
  20 #else
  21 #define O_NOATIME 0
  22 #endif
  23 #endif
  24
  25 const unsigned char null_sha1[20] = { 0, };
  26
  27 static unsigned int sha1_file_open_flag = O_NOATIME;
  28
  29 static unsigned hexval(char c)
  30 {
  31         if (c >= '0' && c <= '9')
  32                 return c - '0';
  33         if (c >= 'a' && c <= 'f')
  34                 return c - 'a' + 10;
  35         if (c >= 'A' && c <= 'F')
  36                 return c - 'A' + 10;
  37         return ~0;
  38 }
  39
  40 int get_sha1_hex(const char *hex, unsigned char *sha1)
  41 {
  42         int i;
  43         for (i = 0; i < 20; i++) {
  44                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  45                 if (val & ~0xff)
  46                         return -1;
  47                 *sha1++ = val;
  48                 hex += 2;
  49         }
  50         return 0;
  51 }
  52
  53 int adjust_shared_perm(const char *path)
  54 {
  55         struct stat st;
  56         int mode;
  57
  58         if (!shared_repository)
  59                 return 0;
  60         if (lstat(path, &st) < 0)
  61                 return -1;
  62         mode = st.st_mode;
  63         if (mode & S_IRUSR)
  64                 mode |= S_IRGRP;
  65         if (mode & S_IWUSR)
  66                 mode |= S_IWGRP;
  67         if (mode & S_IXUSR)
  68                 mode |= S_IXGRP;
  69         if (S_ISDIR(mode))
  70                 mode |= S_ISGID;
  71         if (chmod(path, mode) < 0)
  72                 return -2;
  73         return 0;
  74 }
  75
  76 int safe_create_leading_directories(char *path)
  77 {
  78         char *pos = path;
  79         struct stat st;
  80
  81         if (*pos == '/')
  82                 pos++;
  83
  84         while (pos) {
  85                 pos = strchr(pos, '/');
  86                 if (!pos)
  87                         break;
  88                 *pos = 0;
  89                 if (!stat(path, &st)) {
  90                         /* path exists */
  91                         if (!S_ISDIR(st.st_mode)) {
  92                                 *pos = '/';
  93                                 return -3;
  94                         }
  95                 }
  96                 else if (mkdir(path, 0777)) {
  97                         *pos = '/';
  98                         return -1;
  99                 }
 100                 else if (adjust_shared_perm(path)) {
 101                         *pos = '/';
 102                         return -2;
 103                 }
 104                 *pos++ = '/';
 105         }
 106         return 0;
 107 }
 108
 109 char * sha1_to_hex(const unsigned char *sha1)
 110 {
 111         static int bufno;
 112         static char hexbuffer[4][50];
 113         static const char hex[] = "0123456789abcdef";
 114         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
 115         int i;
 116
 117         for (i = 0; i < 20; i++) {
 118                 unsigned int val = *sha1++;
 119                 *buf++ = hex[val >> 4];
 120                 *buf++ = hex[val & 0xf];
 121         }
 122         *buf = '\0';
 123
 124         return buffer;
 125 }
 126
 127 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 128 {
 129         int i;
 130         for (i = 0; i < 20; i++) {
 131                 static char hex[] = "0123456789abcdef";
 132                 unsigned int val = sha1[i];
 133                 char *pos = pathbuf + i*2 + (i > 0);
 134                 *pos++ = hex[val >> 4];
 135                 *pos = hex[val & 0xf];
 136         }
 137 }
 138
 139 /*
 140  * NOTE! This returns a statically allocated buffer, so you have to be
 141  * careful about using it. Do a "strdup()" if you need to save the
 142  * filename.
 143  *
 144  * Also note that this returns the location for creating.  Reading
 145  * SHA1 file can happen from any alternate directory listed in the
 146  * DB_ENVIRONMENT environment variable if it is not found in
 147  * the primary object database.
 148  */
 149 char *sha1_file_name(const unsigned char *sha1)
 150 {
 151         static char *name, *base;
 152
 153         if (!base) {
 154                 const char *sha1_file_directory = get_object_directory();
 155                 int len = strlen(sha1_file_directory);
 156                 base = xmalloc(len + 60);
 157                 memcpy(base, sha1_file_directory, len);
 158                 memset(base+len, 0, 60);
 159                 base[len] = '/';
 160                 base[len+3] = '/';
 161                 name = base + len + 1;
 162         }
 163         fill_sha1_path(name, sha1);
 164         return base;
 165 }
 166
 167 char *sha1_pack_name(const unsigned char *sha1)
 168 {
 169         static const char hex[] = "0123456789abcdef";
 170         static char *name, *base, *buf;
 171         int i;
 172
 173         if (!base) {
 174                 const char *sha1_file_directory = get_object_directory();
 175                 int len = strlen(sha1_file_directory);
 176                 base = xmalloc(len + 60);
 177                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 178                 name = base + len + 11;
 179         }
 180
 181         buf = name;
 182
 183         for (i = 0; i < 20; i++) {
 184                 unsigned int val = *sha1++;
 185                 *buf++ = hex[val >> 4];
 186                 *buf++ = hex[val & 0xf];
 187         }
 188
 189         return base;
 190 }
 191
 192 char *sha1_pack_index_name(const unsigned char *sha1)
 193 {
 194         static const char hex[] = "0123456789abcdef";
 195         static char *name, *base, *buf;
 196         int i;
 197
 198         if (!base) {
 199                 const char *sha1_file_directory = get_object_directory();
 200                 int len = strlen(sha1_file_directory);
 201                 base = xmalloc(len + 60);
 202                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 203                 name = base + len + 11;
 204         }
 205
 206         buf = name;
 207
 208         for (i = 0; i < 20; i++) {
 209                 unsigned int val = *sha1++;
 210                 *buf++ = hex[val >> 4];
 211                 *buf++ = hex[val & 0xf];
 212         }
 213
 214         return base;
 215 }
 216
 217 struct alternate_object_database *alt_odb_list;
 218 static struct alternate_object_database **alt_odb_tail;
 219
 220 static void read_info_alternates(const char * alternates, int depth);
 221
 222 /*
 223  * Prepare alternate object database registry.
 224  *
 225  * The variable alt_odb_list points at the list of struct
 226  * alternate_object_database.  The elements on this list come from
 227  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 228  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 229  * whose contents is similar to that environment variable but can be
 230  * LF separated.  Its base points at a statically allocated buffer that
 231  * contains "/the/directory/corresponding/to/.git/objects/...", while
 232  * its name points just after the slash at the end of ".git/objects/"
 233  * in the example above, and has enough space to hold 40-byte hex
 234  * SHA1, an extra slash for the first level indirection, and the
 235  * terminating NUL.
 236  */
 237 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 238 {
 239         struct stat st;
 240         const char *objdir = get_object_directory();
 241         struct alternate_object_database *ent;
 242         struct alternate_object_database *alt;
 243         /* 43 = 40-byte + 2 '/' + terminating NUL */
 244         int pfxlen = len;
 245         int entlen = pfxlen + 43;
 246         int base_len = -1;
 247
 248         if (*entry != '/' && relative_base) {
 249                 /* Relative alt-odb */
 250                 if (base_len < 0)
 251                         base_len = strlen(relative_base) + 1;
 252                 entlen += base_len;
 253                 pfxlen += base_len;
 254         }
 255         ent = xmalloc(sizeof(*ent) + entlen);
 256
 257         if (*entry != '/' && relative_base) {
 258                 memcpy(ent->base, relative_base, base_len - 1);
 259                 ent->base[base_len - 1] = '/';
 260                 memcpy(ent->base + base_len, entry, len);
 261         }
 262         else
 263                 memcpy(ent->base, entry, pfxlen);
 264
 265         ent->name = ent->base + pfxlen + 1;
 266         ent->base[pfxlen + 3] = '/';
 267         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 268
 269         /* Detect cases where alternate disappeared */
 270         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 271                 error("object directory %s does not exist; "
 272                       "check .git/objects/info/alternates.",
 273                       ent->base);
 274                 free(ent);
 275                 return -1;
 276         }
 277
 278         /* Prevent the common mistake of listing the same
 279          * thing twice, or object directory itself.
 280          */
 281         for (alt = alt_odb_list; alt; alt = alt->next) {
 282                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 283                         free(ent);
 284                         return -1;
 285                 }
 286         }
 287         if (!memcmp(ent->base, objdir, pfxlen)) {
 288                 free(ent);
 289                 return -1;
 290         }
 291
 292         /* add the alternate entry */
 293         *alt_odb_tail = ent;
 294         alt_odb_tail = &(ent->next);
 295         ent->next = NULL;
 296
 297         /* recursively add alternates */
 298         read_info_alternates(ent->base, depth + 1);
 299
 300         ent->base[pfxlen] = '/';
 301
 302         return 0;
 303 }
 304
 305 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 306                                  const char *relative_base, int depth)
 307 {
 308         const char *cp, *last;
 309
 310         if (depth > 5) {
 311                 error("%s: ignoring alternate object stores, nesting too deep.",
 312                                 relative_base);
 313                 return;
 314         }
 315
 316         last = alt;
 317         while (last < ep) {
 318                 cp = last;
 319                 if (cp < ep && *cp == '#') {
 320                         while (cp < ep && *cp != sep)
 321                                 cp++;
 322                         last = cp + 1;
 323                         continue;
 324                 }
 325                 while (cp < ep && *cp != sep)
 326                         cp++;
 327                 if (last != cp) {
 328                         if ((*last != '/') && depth) {
 329                                 error("%s: ignoring relative alternate object store %s",
 330                                                 relative_base, last);
 331                         } else {
 332                                 link_alt_odb_entry(last, cp - last,
 333                                                 relative_base, depth);
 334                         }
 335                 }
 336                 while (cp < ep && *cp == sep)
 337                         cp++;
 338                 last = cp;
 339         }
 340 }
 341
 342 static void read_info_alternates(const char * relative_base, int depth)
 343 {
 344         char *map;
 345         struct stat st;
 346         char path[PATH_MAX];
 347         int fd;
 348
 349         sprintf(path, "%s/info/alternates", relative_base);
 350         fd = open(path, O_RDONLY);
 351         if (fd < 0)
 352                 return;
 353         if (fstat(fd, &st) || (st.st_size == 0)) {
 354                 close(fd);
 355                 return;
 356         }
 357         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 358         close(fd);
 359         if (map == MAP_FAILED)
 360                 return;
 361
 362         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 363
 364         munmap(map, st.st_size);
 365 }
 366
 367 void prepare_alt_odb(void)
 368 {
 369         char *alt;
 370
 371         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 372         if (!alt) alt = "";
 373
 374         if (alt_odb_tail)
 375                 return;
 376         alt_odb_tail = &alt_odb_list;
 377         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 378
 379         read_info_alternates(get_object_directory(), 0);
 380 }
 381
 382 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 383 {
 384         char *name = sha1_file_name(sha1);
 385         struct alternate_object_database *alt;
 386
 387         if (!stat(name, st))
 388                 return name;
 389         prepare_alt_odb();
 390         for (alt = alt_odb_list; alt; alt = alt->next) {
 391                 name = alt->name;
 392                 fill_sha1_path(name, sha1);
 393                 if (!stat(alt->base, st))
 394                         return alt->base;
 395         }
 396         return NULL;
 397 }
 398
 399 #define PACK_MAX_SZ (1<<26)
 400 static int pack_used_ctr;
 401 static unsigned long pack_mapped;
 402 struct packed_git *packed_git;
 403
 404 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 405                                 void **idx_map_)
 406 {
 407         void *idx_map;
 408         unsigned int *index;
 409         unsigned long idx_size;
 410         int nr, i;
 411         int fd = open(path, O_RDONLY);
 412         struct stat st;
 413         if (fd < 0)
 414                 return -1;
 415         if (fstat(fd, &st)) {
 416                 close(fd);
 417                 return -1;
 418         }
 419         idx_size = st.st_size;
 420         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 421         close(fd);
 422         if (idx_map == MAP_FAILED)
 423                 return -1;
 424
 425         index = idx_map;
 426         *idx_map_ = idx_map;
 427         *idx_size_ = idx_size;
 428
 429         /* check index map */
 430         if (idx_size < 4*256 + 20 + 20)
 431                 return error("index file too small");
 432         nr = 0;
 433         for (i = 0; i < 256; i++) {
 434                 unsigned int n = ntohl(index[i]);
 435                 if (n < nr)
 436                         return error("non-monotonic index");
 437                 nr = n;
 438         }
 439
 440         /*
 441          * Total size:
 442          *  - 256 index entries 4 bytes each
 443          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 444          *  - 20-byte SHA1 of the packfile
 445          *  - 20-byte SHA1 file checksum
 446          */
 447         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 448                 return error("wrong index file size");
 449
 450         return 0;
 451 }
 452
 453 static int unuse_one_packed_git(void)
 454 {
 455         struct packed_git *p, *lru = NULL;
 456
 457         for (p = packed_git; p; p = p->next) {
 458                 if (p->pack_use_cnt || !p->pack_base)
 459                         continue;
 460                 if (!lru || p->pack_last_used < lru->pack_last_used)
 461                         lru = p;
 462         }
 463         if (!lru)
 464                 return 0;
 465         munmap(lru->pack_base, lru->pack_size);
 466         lru->pack_base = NULL;
 467         return 1;
 468 }
 469
 470 void unuse_packed_git(struct packed_git *p)
 471 {
 472         p->pack_use_cnt--;
 473 }
 474
 475 int use_packed_git(struct packed_git *p)
 476 {
 477         if (!p->pack_size) {
 478                 struct stat st;
 479                 // We created the struct before we had the pack
 480                 stat(p->pack_name, &st);
 481                 if (!S_ISREG(st.st_mode))
 482                         die("packfile %s not a regular file", p->pack_name);
 483                 p->pack_size = st.st_size;
 484         }
 485         if (!p->pack_base) {
 486                 int fd;
 487                 struct stat st;
 488                 void *map;
 489
 490                 pack_mapped += p->pack_size;
 491                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 492                         ; /* nothing */
 493                 fd = open(p->pack_name, O_RDONLY);
 494                 if (fd < 0)
 495                         die("packfile %s cannot be opened", p->pack_name);
 496                 if (fstat(fd, &st)) {
 497                         close(fd);
 498                         die("packfile %s cannot be opened", p->pack_name);
 499                 }
 500                 if (st.st_size != p->pack_size)
 501                         die("packfile %s size mismatch.", p->pack_name);
 502                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 503                 close(fd);
 504                 if (map == MAP_FAILED)
 505                         die("packfile %s cannot be mapped.", p->pack_name);
 506                 p->pack_base = map;
 507
 508                 /* Check if the pack file matches with the index file.
 509                  * this is cheap.
 510                  */
 511                 if (memcmp((char*)(p->index_base) + p->index_size - 40,
 512                            p->pack_base + p->pack_size - 20, 20)) {
 513
 514                         die("packfile %s does not match index.", p->pack_name);
 515                 }
 516         }
 517         p->pack_last_used = pack_used_ctr++;
 518         p->pack_use_cnt++;
 519         return 0;
 520 }
 521
 522 struct packed_git *add_packed_git(char *path, int path_len, int local)
 523 {
 524         struct stat st;
 525         struct packed_git *p;
 526         unsigned long idx_size;
 527         void *idx_map;
 528         unsigned char sha1[20];
 529
 530         if (check_packed_git_idx(path, &idx_size, &idx_map))
 531                 return NULL;
 532
 533         /* do we have a corresponding .pack file? */
 534         strcpy(path + path_len - 4, ".pack");
 535         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 536                 munmap(idx_map, idx_size);
 537                 return NULL;
 538         }
 539         /* ok, it looks sane as far as we can check without
 540          * actually mapping the pack file.
 541          */
 542         p = xmalloc(sizeof(*p) + path_len + 2);
 543         strcpy(p->pack_name, path);
 544         p->index_size = idx_size;
 545         p->pack_size = st.st_size;
 546         p->index_base = idx_map;
 547         p->next = NULL;
 548         p->pack_base = NULL;
 549         p->pack_last_used = 0;
 550         p->pack_use_cnt = 0;
 551         p->pack_local = local;
 552         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 553                 memcpy(p->sha1, sha1, 20);
 554         return p;
 555 }
 556
 557 struct packed_git *parse_pack_index(unsigned char *sha1)
 558 {
 559         char *path = sha1_pack_index_name(sha1);
 560         return parse_pack_index_file(sha1, path);
 561 }
 562
 563 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 564 {
 565         struct packed_git *p;
 566         unsigned long idx_size;
 567         void *idx_map;
 568         char *path;
 569
 570         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 571                 return NULL;
 572
 573         path = sha1_pack_name(sha1);
 574
 575         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 576         strcpy(p->pack_name, path);
 577         p->index_size = idx_size;
 578         p->pack_size = 0;
 579         p->index_base = idx_map;
 580         p->next = NULL;
 581         p->pack_base = NULL;
 582         p->pack_last_used = 0;
 583         p->pack_use_cnt = 0;
 584         memcpy(p->sha1, sha1, 20);
 585         return p;
 586 }
 587
 588 void install_packed_git(struct packed_git *pack)
 589 {
 590         pack->next = packed_git;
 591         packed_git = pack;
 592 }
 593
 594 static void prepare_packed_git_one(char *objdir, int local)
 595 {
 596         char path[PATH_MAX];
 597         int len;
 598         DIR *dir;
 599         struct dirent *de;
 600
 601         sprintf(path, "%s/pack", objdir);
 602         len = strlen(path);
 603         dir = opendir(path);
 604         if (!dir) {
 605                 if (errno != ENOENT)
 606                         error("unable to open object pack directory: %s: %s",
 607                               path, strerror(errno));
 608                 return;
 609         }
 610         path[len++] = '/';
 611         while ((de = readdir(dir)) != NULL) {
 612                 int namelen = strlen(de->d_name);
 613                 struct packed_git *p;
 614
 615                 if (strcmp(de->d_name + namelen - 4, ".idx"))
 616                         continue;
 617
 618                 /* we have .idx.  Is it a file we can map? */
 619                 strcpy(path + len, de->d_name);
 620                 for (p = packed_git; p; p = p->next) {
 621                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 622                                 break;
 623                 }
 624                 if (p)
 625                         continue;
 626                 p = add_packed_git(path, len + namelen, local);
 627                 if (!p)
 628                         continue;
 629                 p->next = packed_git;
 630                 packed_git = p;
 631         }
 632         closedir(dir);
 633 }
 634
 635 static int prepare_packed_git_run_once = 0;
 636 void prepare_packed_git(void)
 637 {
 638         struct alternate_object_database *alt;
 639
 640         if (prepare_packed_git_run_once)
 641                 return;
 642         prepare_packed_git_one(get_object_directory(), 1);
 643         prepare_alt_odb();
 644         for (alt = alt_odb_list; alt; alt = alt->next) {
 645                 alt->name[-1] = 0;
 646                 prepare_packed_git_one(alt->base, 0);
 647                 alt->name[-1] = '/';
 648         }
 649         prepare_packed_git_run_once = 1;
 650 }
 651
 652 static void reprepare_packed_git(void)
 653 {
 654         prepare_packed_git_run_once = 0;
 655         prepare_packed_git();
 656 }
 657
 658 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 659 {
 660         char header[100];
 661         unsigned char real_sha1[20];
 662         SHA_CTX c;
 663
 664         SHA1_Init(&c);
 665         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 666         SHA1_Update(&c, map, size);
 667         SHA1_Final(real_sha1, &c);
 668         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 669 }
 670
 671 static void *map_sha1_file_internal(const unsigned char *sha1,
 672                                     unsigned long *size)
 673 {
 674         struct stat st;
 675         void *map;
 676         int fd;
 677         char *filename = find_sha1_file(sha1, &st);
 678
 679         if (!filename) {
 680                 return NULL;
 681         }
 682
 683         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 684         if (fd < 0) {
 685                 /* See if it works without O_NOATIME */
 686                 switch (sha1_file_open_flag) {
 687                 default:
 688                         fd = open(filename, O_RDONLY);
 689                         if (fd >= 0)
 690                                 break;
 691                 /* Fallthrough */
 692                 case 0:
 693                         return NULL;
 694                 }
 695
 696                 /* If it failed once, it will probably fail again.
 697                  * Stop using O_NOATIME
 698                  */
 699                 sha1_file_open_flag = 0;
 700         }
 701         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 702         close(fd);
 703         if (map == MAP_FAILED)
 704                 return NULL;
 705         *size = st.st_size;
 706         return map;
 707 }
 708
 709 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 710 {
 711         /* Get the data stream */
 712         memset(stream, 0, sizeof(*stream));
 713         stream->next_in = map;
 714         stream->avail_in = mapsize;
 715         stream->next_out = buffer;
 716         stream->avail_out = size;
 717
 718         inflateInit(stream);
 719         return inflate(stream, 0);
 720 }
 721
 722 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 723 {
 724         int bytes = strlen(buffer) + 1;
 725         unsigned char *buf = xmalloc(1+size);
 726
 727         memcpy(buf, buffer + bytes, stream->total_out - bytes);
 728         bytes = stream->total_out - bytes;
 729         if (bytes < size) {
 730                 stream->next_out = buf + bytes;
 731                 stream->avail_out = size - bytes;
 732                 while (inflate(stream, Z_FINISH) == Z_OK)
 733                         /* nothing */;
 734         }
 735         buf[size] = 0;
 736         inflateEnd(stream);
 737         return buf;
 738 }
 739
 740 /*
 741  * We used to just use "sscanf()", but that's actually way
 742  * too permissive for what we want to check. So do an anal
 743  * object header parse by hand.
 744  */
 745 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 746 {
 747         int i;
 748         unsigned long size;
 749
 750         /*
 751          * The type can be at most ten bytes (including the
 752          * terminating '\0' that we add), and is followed by
 753          * a space.
 754          */
 755         i = 10;
 756         for (;;) {
 757                 char c = *hdr++;
 758                 if (c == ' ')
 759                         break;
 760                 if (!--i)
 761                         return -1;
 762                 *type++ = c;
 763         }
 764         *type = 0;
 765
 766         /*
 767          * The length must follow immediately, and be in canonical
 768          * decimal format (ie "010" is not valid).
 769          */
 770         size = *hdr++ - '0';
 771         if (size > 9)
 772                 return -1;
 773         if (size) {
 774                 for (;;) {
 775                         unsigned long c = *hdr - '0';
 776                         if (c > 9)
 777                                 break;
 778                         hdr++;
 779                         size = size * 10 + c;
 780                 }
 781         }
 782         *sizep = size;
 783
 784         /*
 785          * The length must be followed by a zero byte
 786          */
 787         return *hdr ? -1 : 0;
 788 }
 789
 790 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 791 {
 792         int ret;
 793         z_stream stream;
 794         char hdr[8192];
 795
 796         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 797         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 798                 return NULL;
 799
 800         return unpack_sha1_rest(&stream, hdr, *size);
 801 }
 802
 803 /* forward declaration for a mutually recursive function */
 804 static int packed_object_info(struct pack_entry *entry,
 805                               char *type, unsigned long *sizep);
 806
 807 static int packed_delta_info(unsigned char *base_sha1,
 808                              unsigned long delta_size,
 809                              unsigned long left,
 810                              char *type,
 811                              unsigned long *sizep,
 812                              struct packed_git *p)
 813 {
 814         struct pack_entry base_ent;
 815
 816         if (left < 20)
 817                 die("truncated pack file");
 818
 819         /* The base entry _must_ be in the same pack */
 820         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 821                 die("failed to find delta-pack base object %s",
 822                     sha1_to_hex(base_sha1));
 823
 824         /* We choose to only get the type of the base object and
 825          * ignore potentially corrupt pack file that expects the delta
 826          * based on a base with a wrong size.  This saves tons of
 827          * inflate() calls.
 828          */
 829
 830         if (packed_object_info(&base_ent, type, NULL))
 831                 die("cannot get info for delta-pack base");
 832
 833         if (sizep) {
 834                 const unsigned char *data;
 835                 unsigned char delta_head[64];
 836                 unsigned long result_size;
 837                 z_stream stream;
 838                 int st;
 839
 840                 memset(&stream, 0, sizeof(stream));
 841
 842                 data = stream.next_in = base_sha1 + 20;
 843                 stream.avail_in = left - 20;
 844                 stream.next_out = delta_head;
 845                 stream.avail_out = sizeof(delta_head);
 846
 847                 inflateInit(&stream);
 848                 st = inflate(&stream, Z_FINISH);
 849                 inflateEnd(&stream);
 850                 if ((st != Z_STREAM_END) &&
 851                     stream.total_out != sizeof(delta_head))
 852                         die("delta data unpack-initial failed");
 853
 854                 /* Examine the initial part of the delta to figure out
 855                  * the result size.
 856                  */
 857                 data = delta_head;
 858
 859                 /* ignore base size */
 860                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 861
 862                 /* Read the result size */
 863                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 864                 *sizep = result_size;
 865         }
 866         return 0;
 867 }
 868
 869 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 870         enum object_type *type, unsigned long *sizep)
 871 {
 872         unsigned shift;
 873         unsigned char *pack, c;
 874         unsigned long size;
 875
 876         if (offset >= p->pack_size)
 877                 die("object offset outside of pack file");
 878
 879         pack =  p->pack_base + offset;
 880         c = *pack++;
 881         offset++;
 882         *type = (c >> 4) & 7;
 883         size = c & 15;
 884         shift = 4;
 885         while (c & 0x80) {
 886                 if (offset >= p->pack_size)
 887                         die("object offset outside of pack file");
 888                 c = *pack++;
 889                 offset++;
 890                 size += (c & 0x7f) << shift;
 891                 shift += 7;
 892         }
 893         *sizep = size;
 894         return offset;
 895 }
 896
 897 int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
 898                            unsigned char *base, unsigned long *sizep,
 899                            enum object_type *kindp)
 900 {
 901         unsigned long ptr;
 902         int status = -1;
 903
 904         use_packed_git(p);
 905         ptr = offset;
 906         ptr = unpack_object_header(p, ptr, kindp, sizep);
 907         if (*kindp != OBJ_DELTA)
 908                 goto done;
 909         memcpy(base, p->pack_base + ptr, 20);
 910         status = 0;
 911  done:
 912         unuse_packed_git(p);
 913         return status;
 914 }
 915
 916 void packed_object_info_detail(struct pack_entry *e,
 917                                char *type,
 918                                unsigned long *size,
 919                                unsigned long *store_size,
 920                                unsigned int *delta_chain_length,
 921                                unsigned char *base_sha1)
 922 {
 923         struct packed_git *p = e->p;
 924         unsigned long offset;
 925         unsigned char *pack;
 926         enum object_type kind;
 927
 928         offset = unpack_object_header(p, e->offset, &kind, size);
 929         pack = p->pack_base + offset;
 930         if (kind != OBJ_DELTA)
 931                 *delta_chain_length = 0;
 932         else {
 933                 unsigned int chain_length = 0;
 934                 if (p->pack_size <= offset + 20)
 935                         die("pack file %s records an incomplete delta base",
 936                             p->pack_name);
 937                 memcpy(base_sha1, pack, 20);
 938                 do {
 939                         struct pack_entry base_ent;
 940                         unsigned long junk;
 941
 942                         find_pack_entry_one(pack, &base_ent, p);
 943                         offset = unpack_object_header(p, base_ent.offset,
 944                                                       &kind, &junk);
 945                         pack = p->pack_base + offset;
 946                         chain_length++;
 947                 } while (kind == OBJ_DELTA);
 948                 *delta_chain_length = chain_length;
 949         }
 950         switch (kind) {
 951         case OBJ_COMMIT:
 952                 strcpy(type, commit_type);
 953                 break;
 954         case OBJ_TREE:
 955                 strcpy(type, tree_type);
 956                 break;
 957         case OBJ_BLOB:
 958                 strcpy(type, blob_type);
 959                 break;
 960         case OBJ_TAG:
 961                 strcpy(type, tag_type);
 962                 break;
 963         default:
 964                 die("corrupted pack file %s containing object of kind %d",
 965                     p->pack_name, kind);
 966         }
 967         *store_size = 0; /* notyet */
 968 }
 969
 970 static int packed_object_info(struct pack_entry *entry,
 971                               char *type, unsigned long *sizep)
 972 {
 973         struct packed_git *p = entry->p;
 974         unsigned long offset, size, left;
 975         unsigned char *pack;
 976         enum object_type kind;
 977         int retval;
 978
 979         if (use_packed_git(p))
 980                 die("cannot map packed file");
 981
 982         offset = unpack_object_header(p, entry->offset, &kind, &size);
 983         pack = p->pack_base + offset;
 984         left = p->pack_size - offset;
 985
 986         switch (kind) {
 987         case OBJ_DELTA:
 988                 retval = packed_delta_info(pack, size, left, type, sizep, p);
 989                 unuse_packed_git(p);
 990                 return retval;
 991         case OBJ_COMMIT:
 992                 strcpy(type, commit_type);
 993                 break;
 994         case OBJ_TREE:
 995                 strcpy(type, tree_type);
 996                 break;
 997         case OBJ_BLOB:
 998                 strcpy(type, blob_type);
 999                 break;
1000         case OBJ_TAG:
1001                 strcpy(type, tag_type);
1002                 break;
1003         default:
1004                 die("corrupted pack file %s containing object of kind %d",
1005                     p->pack_name, kind);
1006         }
1007         if (sizep)
1008                 *sizep = size;
1009         unuse_packed_git(p);
1010         return 0;
1011 }
1012
1013 /* forward declaration for a mutually recursive function */
1014 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
1015
1016 static void *unpack_delta_entry(unsigned char *base_sha1,
1017                                 unsigned long delta_size,
1018                                 unsigned long left,
1019                                 char *type,
1020                                 unsigned long *sizep,
1021                                 struct packed_git *p)
1022 {
1023         struct pack_entry base_ent;
1024         void *data, *delta_data, *result, *base;
1025         unsigned long data_size, result_size, base_size;
1026         z_stream stream;
1027         int st;
1028
1029         if (left < 20)
1030                 die("truncated pack file");
1031
1032         /* The base entry _must_ be in the same pack */
1033         if (!find_pack_entry_one(base_sha1, &base_ent, p))
1034                 die("failed to find delta-pack base object %s",
1035                     sha1_to_hex(base_sha1));
1036         base = unpack_entry_gently(&base_ent, type, &base_size);
1037         if (!base)
1038                 die("failed to read delta-pack base object %s",
1039                     sha1_to_hex(base_sha1));
1040
1041         data = base_sha1 + 20;
1042         data_size = left - 20;
1043         delta_data = xmalloc(delta_size);
1044
1045         memset(&stream, 0, sizeof(stream));
1046
1047         stream.next_in = data;
1048         stream.avail_in = data_size;
1049         stream.next_out = delta_data;
1050         stream.avail_out = delta_size;
1051
1052         inflateInit(&stream);
1053         st = inflate(&stream, Z_FINISH);
1054         inflateEnd(&stream);
1055         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
1056                 die("delta data unpack failed");
1057
1058         result = patch_delta(base, base_size,
1059                              delta_data, delta_size,
1060                              &result_size);
1061         if (!result)
1062                 die("failed to apply delta");
1063         free(delta_data);
1064         free(base);
1065         *sizep = result_size;
1066         return result;
1067 }
1068
1069 static void *unpack_non_delta_entry(unsigned char *data,
1070                                     unsigned long size,
1071                                     unsigned long left)
1072 {
1073         int st;
1074         z_stream stream;
1075         unsigned char *buffer;
1076
1077         buffer = xmalloc(size + 1);
1078         buffer[size] = 0;
1079         memset(&stream, 0, sizeof(stream));
1080         stream.next_in = data;
1081         stream.avail_in = left;
1082         stream.next_out = buffer;
1083         stream.avail_out = size;
1084
1085         inflateInit(&stream);
1086         st = inflate(&stream, Z_FINISH);
1087         inflateEnd(&stream);
1088         if ((st != Z_STREAM_END) || stream.total_out != size) {
1089                 free(buffer);
1090                 return NULL;
1091         }
1092
1093         return buffer;
1094 }
1095
1096 static void *unpack_entry(struct pack_entry *entry,
1097                           char *type, unsigned long *sizep)
1098 {
1099         struct packed_git *p = entry->p;
1100         void *retval;
1101
1102         if (use_packed_git(p))
1103                 die("cannot map packed file");
1104         retval = unpack_entry_gently(entry, type, sizep);
1105         unuse_packed_git(p);
1106         if (!retval)
1107                 die("corrupted pack file %s", p->pack_name);
1108         return retval;
1109 }
1110
1111 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
1112 void *unpack_entry_gently(struct pack_entry *entry,
1113                           char *type, unsigned long *sizep)
1114 {
1115         struct packed_git *p = entry->p;
1116         unsigned long offset, size, left;
1117         unsigned char *pack;
1118         enum object_type kind;
1119         void *retval;
1120
1121         offset = unpack_object_header(p, entry->offset, &kind, &size);
1122         pack = p->pack_base + offset;
1123         left = p->pack_size - offset;
1124         switch (kind) {
1125         case OBJ_DELTA:
1126                 retval = unpack_delta_entry(pack, size, left, type, sizep, p);
1127                 return retval;
1128         case OBJ_COMMIT:
1129                 strcpy(type, commit_type);
1130                 break;
1131         case OBJ_TREE:
1132                 strcpy(type, tree_type);
1133                 break;
1134         case OBJ_BLOB:
1135                 strcpy(type, blob_type);
1136                 break;
1137         case OBJ_TAG:
1138                 strcpy(type, tag_type);
1139                 break;
1140         default:
1141                 return NULL;
1142         }
1143         *sizep = size;
1144         retval = unpack_non_delta_entry(pack, size, left);
1145         return retval;
1146 }
1147
1148 int num_packed_objects(const struct packed_git *p)
1149 {
1150         /* See check_packed_git_idx() */
1151         return (p->index_size - 20 - 20 - 4*256) / 24;
1152 }
1153
1154 int nth_packed_object_sha1(const struct packed_git *p, int n,
1155                            unsigned char* sha1)
1156 {
1157         void *index = p->index_base + 256;
1158         if (n < 0 || num_packed_objects(p) <= n)
1159                 return -1;
1160         memcpy(sha1, (index + 24 * n + 4), 20);
1161         return 0;
1162 }
1163
1164 int find_pack_entry_one(const unsigned char *sha1,
1165                         struct pack_entry *e, struct packed_git *p)
1166 {
1167         unsigned int *level1_ofs = p->index_base;
1168         int hi = ntohl(level1_ofs[*sha1]);
1169         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1170         void *index = p->index_base + 256;
1171
1172         do {
1173                 int mi = (lo + hi) / 2;
1174                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1175                 if (!cmp) {
1176                         e->offset = ntohl(*((unsigned int *)(index + 24 * mi)));
1177                         memcpy(e->sha1, sha1, 20);
1178                         e->p = p;
1179                         return 1;
1180                 }
1181                 if (cmp > 0)
1182                         hi = mi;
1183                 else
1184                         lo = mi+1;
1185         } while (lo < hi);
1186         return 0;
1187 }
1188
1189 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1190 {
1191         struct packed_git *p;
1192         prepare_packed_git();
1193
1194         for (p = packed_git; p; p = p->next) {
1195                 if (find_pack_entry_one(sha1, e, p))
1196                         return 1;
1197         }
1198         return 0;
1199 }
1200
1201 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1202                                   struct packed_git *packs)
1203 {
1204         struct packed_git *p;
1205         struct pack_entry e;
1206
1207         for (p = packs; p; p = p->next) {
1208                 if (find_pack_entry_one(sha1, &e, p))
1209                         return p;
1210         }
1211         return NULL;
1212
1213 }
1214
1215 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1216 {
1217         int status;
1218         unsigned long mapsize, size;
1219         void *map;
1220         z_stream stream;
1221         char hdr[128];
1222
1223         map = map_sha1_file_internal(sha1, &mapsize);
1224         if (!map) {
1225                 struct pack_entry e;
1226
1227                 if (find_pack_entry(sha1, &e))
1228                         return packed_object_info(&e, type, sizep);
1229                 reprepare_packed_git();
1230                 if (find_pack_entry(sha1, &e))
1231                         return packed_object_info(&e, type, sizep);
1232                 return error("unable to find %s", sha1_to_hex(sha1));
1233         }
1234         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1235                 status = error("unable to unpack %s header",
1236                                sha1_to_hex(sha1));
1237         if (parse_sha1_header(hdr, type, &size) < 0)
1238                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1239         else {
1240                 status = 0;
1241                 if (sizep)
1242                         *sizep = size;
1243         }
1244         inflateEnd(&stream);
1245         munmap(map, mapsize);
1246         return status;
1247 }
1248
1249 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1250 {
1251         struct pack_entry e;
1252
1253         if (!find_pack_entry(sha1, &e)) {
1254                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1255                 return NULL;
1256         }
1257         return unpack_entry(&e, type, size);
1258 }
1259
1260 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1261 {
1262         unsigned long mapsize;
1263         void *map, *buf;
1264         struct pack_entry e;
1265
1266         if (find_pack_entry(sha1, &e))
1267                 return read_packed_sha1(sha1, type, size);
1268         map = map_sha1_file_internal(sha1, &mapsize);
1269         if (map) {
1270                 buf = unpack_sha1_file(map, mapsize, type, size);
1271                 munmap(map, mapsize);
1272                 return buf;
1273         }
1274         reprepare_packed_git();
1275         if (find_pack_entry(sha1, &e))
1276                 return read_packed_sha1(sha1, type, size);
1277         return NULL;
1278 }
1279
1280 void *read_object_with_reference(const unsigned char *sha1,
1281                                  const char *required_type,
1282                                  unsigned long *size,
1283                                  unsigned char *actual_sha1_return)
1284 {
1285         char type[20];
1286         void *buffer;
1287         unsigned long isize;
1288         unsigned char actual_sha1[20];
1289
1290         memcpy(actual_sha1, sha1, 20);
1291         while (1) {
1292                 int ref_length = -1;
1293                 const char *ref_type = NULL;
1294
1295                 buffer = read_sha1_file(actual_sha1, type, &isize);
1296                 if (!buffer)
1297                         return NULL;
1298                 if (!strcmp(type, required_type)) {
1299                         *size = isize;
1300                         if (actual_sha1_return)
1301                                 memcpy(actual_sha1_return, actual_sha1, 20);
1302                         return buffer;
1303                 }
1304                 /* Handle references */
1305                 else if (!strcmp(type, commit_type))
1306                         ref_type = "tree ";
1307                 else if (!strcmp(type, tag_type))
1308                         ref_type = "object ";
1309                 else {
1310                         free(buffer);
1311                         return NULL;
1312                 }
1313                 ref_length = strlen(ref_type);
1314
1315                 if (memcmp(buffer, ref_type, ref_length) ||
1316                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
1317                         free(buffer);
1318                         return NULL;
1319                 }
1320                 free(buffer);
1321                 /* Now we have the ID of the referred-to object in
1322                  * actual_sha1.  Check again. */
1323         }
1324 }
1325
1326 char *write_sha1_file_prepare(void *buf,
1327                               unsigned long len,
1328                               const char *type,
1329                               unsigned char *sha1,
1330                               unsigned char *hdr,
1331                               int *hdrlen)
1332 {
1333         SHA_CTX c;
1334
1335         /* Generate the header */
1336         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1337
1338         /* Sha1.. */
1339         SHA1_Init(&c);
1340         SHA1_Update(&c, hdr, *hdrlen);
1341         SHA1_Update(&c, buf, len);
1342         SHA1_Final(sha1, &c);
1343
1344         return sha1_file_name(sha1);
1345 }
1346
1347 /*
1348  * Link the tempfile to the final place, possibly creating the
1349  * last directory level as you do so.
1350  *
1351  * Returns the errno on failure, 0 on success.
1352  */
1353 static int link_temp_to_file(const char *tmpfile, char *filename)
1354 {
1355         int ret;
1356
1357         if (!link(tmpfile, filename))
1358                 return 0;
1359
1360         /*
1361          * Try to mkdir the last path component if that failed
1362          * with an ENOENT.
1363          *
1364          * Re-try the "link()" regardless of whether the mkdir
1365          * succeeds, since a race might mean that somebody
1366          * else succeeded.
1367          */
1368         ret = errno;
1369         if (ret == ENOENT) {
1370                 char *dir = strrchr(filename, '/');
1371                 if (dir) {
1372                         *dir = 0;
1373                         mkdir(filename, 0777);
1374                         if (adjust_shared_perm(filename))
1375                                 return -2;
1376                         *dir = '/';
1377                         if (!link(tmpfile, filename))
1378                                 return 0;
1379                         ret = errno;
1380                 }
1381         }
1382         return ret;
1383 }
1384
1385 /*
1386  * Move the just written object into its final resting place
1387  */
1388 int move_temp_to_file(const char *tmpfile, char *filename)
1389 {
1390         int ret = link_temp_to_file(tmpfile, filename);
1391
1392         /*
1393          * Coda hack - coda doesn't like cross-directory links,
1394          * so we fall back to a rename, which will mean that it
1395          * won't be able to check collisions, but that's not a
1396          * big deal.
1397          *
1398          * The same holds for FAT formatted media.
1399          *
1400          * When this succeeds, we just return 0. We have nothing
1401          * left to unlink.
1402          */
1403         if (ret && ret != EEXIST) {
1404                 if (!rename(tmpfile, filename))
1405                         return 0;
1406                 ret = errno;
1407         }
1408         unlink(tmpfile);
1409         if (ret) {
1410                 if (ret != EEXIST) {
1411                         fprintf(stderr, "unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1412                         return -1;
1413                 }
1414                 /* FIXME!!! Collision check here ? */
1415         }
1416
1417         return 0;
1418 }
1419
1420 static int write_buffer(int fd, const void *buf, size_t len)
1421 {
1422         while (len) {
1423                 ssize_t size;
1424
1425                 size = write(fd, buf, len);
1426                 if (!size)
1427                         return error("file write: disk full");
1428                 if (size < 0) {
1429                         if (errno == EINTR || errno == EAGAIN)
1430                                 continue;
1431                         return error("file write error (%s)", strerror(errno));
1432                 }
1433                 len -= size;
1434                 buf += size;
1435         }
1436         return 0;
1437 }
1438
1439 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1440 {
1441         int size;
1442         unsigned char *compressed;
1443         z_stream stream;
1444         unsigned char sha1[20];
1445         char *filename;
1446         static char tmpfile[PATH_MAX];
1447         unsigned char hdr[50];
1448         int fd, hdrlen;
1449
1450         /* Normally if we have it in the pack then we do not bother writing
1451          * it out into .git/objects/??/?{38} file.
1452          */
1453         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1454         if (returnsha1)
1455                 memcpy(returnsha1, sha1, 20);
1456         if (has_sha1_file(sha1))
1457                 return 0;
1458         fd = open(filename, O_RDONLY);
1459         if (fd >= 0) {
1460                 /*
1461                  * FIXME!!! We might do collision checking here, but we'd
1462                  * need to uncompress the old file and check it. Later.
1463                  */
1464                 close(fd);
1465                 return 0;
1466         }
1467
1468         if (errno != ENOENT) {
1469                 fprintf(stderr, "sha1 file %s: %s\n", filename, strerror(errno));
1470                 return -1;
1471         }
1472
1473         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1474
1475         fd = mkstemp(tmpfile);
1476         if (fd < 0) {
1477                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1478                 return -1;
1479         }
1480
1481         /* Set it up */
1482         memset(&stream, 0, sizeof(stream));
1483         deflateInit(&stream, Z_BEST_COMPRESSION);
1484         size = deflateBound(&stream, len+hdrlen);
1485         compressed = xmalloc(size);
1486
1487         /* Compress it */
1488         stream.next_out = compressed;
1489         stream.avail_out = size;
1490
1491         /* First header.. */
1492         stream.next_in = hdr;
1493         stream.avail_in = hdrlen;
1494         while (deflate(&stream, 0) == Z_OK)
1495                 /* nothing */;
1496
1497         /* Then the data itself.. */
1498         stream.next_in = buf;
1499         stream.avail_in = len;
1500         while (deflate(&stream, Z_FINISH) == Z_OK)
1501                 /* nothing */;
1502         deflateEnd(&stream);
1503         size = stream.total_out;
1504
1505         if (write_buffer(fd, compressed, size) < 0)
1506                 die("unable to write sha1 file");
1507         fchmod(fd, 0444);
1508         close(fd);
1509         free(compressed);
1510
1511         return move_temp_to_file(tmpfile, filename);
1512 }
1513
1514 /*
1515  * We need to unpack and recompress the object for writing
1516  * it out to a different file.
1517  */
1518 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1519 {
1520         size_t size;
1521         z_stream stream;
1522         unsigned char *unpacked;
1523         unsigned long len;
1524         char type[20];
1525         char hdr[50];
1526         int hdrlen;
1527         void *buf;
1528
1529         // need to unpack and recompress it by itself
1530         unpacked = read_packed_sha1(sha1, type, &len);
1531
1532         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1533
1534         /* Set it up */
1535         memset(&stream, 0, sizeof(stream));
1536         deflateInit(&stream, Z_BEST_COMPRESSION);
1537         size = deflateBound(&stream, len + hdrlen);
1538         buf = xmalloc(size);
1539
1540         /* Compress it */
1541         stream.next_out = buf;
1542         stream.avail_out = size;
1543
1544         /* First header.. */
1545         stream.next_in = (void *)hdr;
1546         stream.avail_in = hdrlen;
1547         while (deflate(&stream, 0) == Z_OK)
1548                 /* nothing */;
1549
1550         /* Then the data itself.. */
1551         stream.next_in = unpacked;
1552         stream.avail_in = len;
1553         while (deflate(&stream, Z_FINISH) == Z_OK)
1554                 /* nothing */;
1555         deflateEnd(&stream);
1556         free(unpacked);
1557
1558         *objsize = stream.total_out;
1559         return buf;
1560 }
1561
1562 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1563 {
1564         int retval;
1565         unsigned long objsize;
1566         void *buf = map_sha1_file_internal(sha1, &objsize);
1567
1568         if (buf) {
1569                 retval = write_buffer(fd, buf, objsize);
1570                 munmap(buf, objsize);
1571                 return retval;
1572         }
1573
1574         buf = repack_object(sha1, &objsize);
1575         retval = write_buffer(fd, buf, objsize);
1576         free(buf);
1577         return retval;
1578 }
1579
1580 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1581                        size_t bufsize, size_t *bufposn)
1582 {
1583         char tmpfile[PATH_MAX];
1584         int local;
1585         z_stream stream;
1586         unsigned char real_sha1[20];
1587         unsigned char discard[4096];
1588         int ret;
1589         SHA_CTX c;
1590
1591         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1592
1593         local = mkstemp(tmpfile);
1594         if (local < 0)
1595                 return error("Couldn't open %s for %s",
1596                              tmpfile, sha1_to_hex(sha1));
1597
1598         memset(&stream, 0, sizeof(stream));
1599
1600         inflateInit(&stream);
1601
1602         SHA1_Init(&c);
1603
1604         do {
1605                 ssize_t size;
1606                 if (*bufposn) {
1607                         stream.avail_in = *bufposn;
1608                         stream.next_in = (unsigned char *) buffer;
1609                         do {
1610                                 stream.next_out = discard;
1611                                 stream.avail_out = sizeof(discard);
1612                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1613                                 SHA1_Update(&c, discard, sizeof(discard) -
1614                                             stream.avail_out);
1615                         } while (stream.avail_in && ret == Z_OK);
1616                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1617                                 die("unable to write sha1 file");
1618                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1619                                 stream.avail_in);
1620                         *bufposn = stream.avail_in;
1621                         if (ret != Z_OK)
1622                                 break;
1623                 }
1624                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1625                 if (size <= 0) {
1626                         close(local);
1627                         unlink(tmpfile);
1628                         if (!size)
1629                                 return error("Connection closed?");
1630                         perror("Reading from connection");
1631                         return -1;
1632                 }
1633                 *bufposn += size;
1634         } while (1);
1635         inflateEnd(&stream);
1636
1637         close(local);
1638         SHA1_Final(real_sha1, &c);
1639         if (ret != Z_STREAM_END) {
1640                 unlink(tmpfile);
1641                 return error("File %s corrupted", sha1_to_hex(sha1));
1642         }
1643         if (memcmp(sha1, real_sha1, 20)) {
1644                 unlink(tmpfile);
1645                 return error("File %s has bad hash", sha1_to_hex(sha1));
1646         }
1647
1648         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1649 }
1650
1651 int has_pack_index(const unsigned char *sha1)
1652 {
1653         struct stat st;
1654         if (stat(sha1_pack_index_name(sha1), &st))
1655                 return 0;
1656         return 1;
1657 }
1658
1659 int has_pack_file(const unsigned char *sha1)
1660 {
1661         struct stat st;
1662         if (stat(sha1_pack_name(sha1), &st))
1663                 return 0;
1664         return 1;
1665 }
1666
1667 int has_sha1_pack(const unsigned char *sha1)
1668 {
1669         struct pack_entry e;
1670         return find_pack_entry(sha1, &e);
1671 }
1672
1673 int has_sha1_file(const unsigned char *sha1)
1674 {
1675         struct stat st;
1676         struct pack_entry e;
1677
1678         if (find_pack_entry(sha1, &e))
1679                 return 1;
1680         return find_sha1_file(sha1, &st) ? 1 : 0;
1681 }
1682
1683 /*
1684  * reads from fd as long as possible into a supplied buffer of size bytes.
1685  * If neccessary the buffer's size is increased using realloc()
1686  *
1687  * returns 0 if anything went fine and -1 otherwise
1688  *
1689  * NOTE: both buf and size may change, but even when -1 is returned
1690  * you still have to free() it yourself.
1691  */
1692 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1693 {
1694         char* buf = *return_buf;
1695         unsigned long size = *return_size;
1696         int iret;
1697         unsigned long off = 0;
1698
1699         do {
1700                 iret = xread(fd, buf + off, size - off);
1701                 if (iret > 0) {
1702                         off += iret;
1703                         if (off == size) {
1704                                 size *= 2;
1705                                 buf = realloc(buf, size);
1706                         }
1707                 }
1708         } while (iret > 0);
1709
1710         *return_buf = buf;
1711         *return_size = off;
1712
1713         if (iret < 0)
1714                 return -1;
1715         return 0;
1716 }
1717
1718 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1719 {
1720         unsigned long size = 4096;
1721         char *buf = malloc(size);
1722         int ret;
1723         unsigned char hdr[50];
1724         int hdrlen;
1725
1726         if (read_pipe(fd, &buf, &size)) {
1727                 free(buf);
1728                 return -1;
1729         }
1730
1731         if (!type)
1732                 type = blob_type;
1733         if (write_object)
1734                 ret = write_sha1_file(buf, size, type, sha1);
1735         else {
1736                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1737                 ret = 0;
1738         }
1739         free(buf);
1740         return ret;
1741 }
1742
1743 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1744 {
1745         unsigned long size = st->st_size;
1746         void *buf;
1747         int ret;
1748         unsigned char hdr[50];
1749         int hdrlen;
1750
1751         buf = "";
1752         if (size)
1753                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1754         close(fd);
1755         if (buf == MAP_FAILED)
1756                 return -1;
1757
1758         if (!type)
1759                 type = blob_type;
1760         if (write_object)
1761                 ret = write_sha1_file(buf, size, type, sha1);
1762         else {
1763                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1764                 ret = 0;
1765         }
1766         if (size)
1767                 munmap(buf, size);
1768         return ret;
1769 }
1770
1771 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1772 {
1773         int fd;
1774         char *target;
1775
1776         switch (st->st_mode & S_IFMT) {
1777         case S_IFREG:
1778                 fd = open(path, O_RDONLY);
1779                 if (fd < 0)
1780                         return error("open(\"%s\"): %s", path,
1781                                      strerror(errno));
1782                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1783                         return error("%s: failed to insert into database",
1784                                      path);
1785                 break;
1786         case S_IFLNK:
1787                 target = xmalloc(st->st_size+1);
1788                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1789                         char *errstr = strerror(errno);
1790                         free(target);
1791                         return error("readlink(\"%s\"): %s", path,
1792                                      errstr);
1793                 }
1794                 if (!write_object) {
1795                         unsigned char hdr[50];
1796                         int hdrlen;
1797                         write_sha1_file_prepare(target, st->st_size, blob_type,
1798                                                 sha1, hdr, &hdrlen);
1799                 } else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1800                         return error("%s: failed to insert into database",
1801                                      path);
1802                 free(target);
1803                 break;
1804         default:
1805                 return error("%s: unsupported file type", path);
1806         }
1807         return 0;
1808 }