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 #include <stdint.h>
  17
  18 #ifndef O_NOATIME
  19 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  20 #define O_NOATIME 01000000
  21 #else
  22 #define O_NOATIME 0
  23 #endif
  24 #endif
  25
  26 const unsigned char null_sha1[20] = { 0, };
  27
  28 static unsigned int sha1_file_open_flag = O_NOATIME;
  29
  30 static unsigned hexval(char c)
  31 {
  32         if (c >= '0' && c <= '9')
  33                 return c - '0';
  34         if (c >= 'a' && c <= 'f')
  35                 return c - 'a' + 10;
  36         if (c >= 'A' && c <= 'F')
  37                 return c - 'A' + 10;
  38         return ~0;
  39 }
  40
  41 int get_sha1_hex(const char *hex, unsigned char *sha1)
  42 {
  43         int i;
  44         for (i = 0; i < 20; i++) {
  45                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  46                 if (val & ~0xff)
  47                         return -1;
  48                 *sha1++ = val;
  49                 hex += 2;
  50         }
  51         return 0;
  52 }
  53
  54 int adjust_shared_perm(const char *path)
  55 {
  56         struct stat st;
  57         int mode;
  58
  59         if (!shared_repository)
  60                 return 0;
  61         if (lstat(path, &st) < 0)
  62                 return -1;
  63         mode = st.st_mode;
  64         if (mode & S_IRUSR)
  65                 mode |= S_IRGRP;
  66         if (mode & S_IWUSR)
  67                 mode |= S_IWGRP;
  68         if (mode & S_IXUSR)
  69                 mode |= S_IXGRP;
  70         if (S_ISDIR(mode))
  71                 mode |= S_ISGID;
  72         if (chmod(path, mode) < 0)
  73                 return -2;
  74         return 0;
  75 }
  76
  77 int safe_create_leading_directories(char *path)
  78 {
  79         char *pos = path;
  80         struct stat st;
  81
  82         if (*pos == '/')
  83                 pos++;
  84
  85         while (pos) {
  86                 pos = strchr(pos, '/');
  87                 if (!pos)
  88                         break;
  89                 *pos = 0;
  90                 if (!stat(path, &st)) {
  91                         /* path exists */
  92                         if (!S_ISDIR(st.st_mode)) {
  93                                 *pos = '/';
  94                                 return -3;
  95                         }
  96                 }
  97                 else if (mkdir(path, 0777)) {
  98                         *pos = '/';
  99                         return -1;
 100                 }
 101                 else if (adjust_shared_perm(path)) {
 102                         *pos = '/';
 103                         return -2;
 104                 }
 105                 *pos++ = '/';
 106         }
 107         return 0;
 108 }
 109
 110 char * sha1_to_hex(const unsigned char *sha1)
 111 {
 112         static int bufno;
 113         static char hexbuffer[4][50];
 114         static const char hex[] = "0123456789abcdef";
 115         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
 116         int i;
 117
 118         for (i = 0; i < 20; i++) {
 119                 unsigned int val = *sha1++;
 120                 *buf++ = hex[val >> 4];
 121                 *buf++ = hex[val & 0xf];
 122         }
 123         *buf = '\0';
 124
 125         return buffer;
 126 }
 127
 128 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 129 {
 130         int i;
 131         for (i = 0; i < 20; i++) {
 132                 static char hex[] = "0123456789abcdef";
 133                 unsigned int val = sha1[i];
 134                 char *pos = pathbuf + i*2 + (i > 0);
 135                 *pos++ = hex[val >> 4];
 136                 *pos = hex[val & 0xf];
 137         }
 138 }
 139
 140 /*
 141  * NOTE! This returns a statically allocated buffer, so you have to be
 142  * careful about using it. Do a "strdup()" if you need to save the
 143  * filename.
 144  *
 145  * Also note that this returns the location for creating.  Reading
 146  * SHA1 file can happen from any alternate directory listed in the
 147  * DB_ENVIRONMENT environment variable if it is not found in
 148  * the primary object database.
 149  */
 150 char *sha1_file_name(const unsigned char *sha1)
 151 {
 152         static char *name, *base;
 153
 154         if (!base) {
 155                 const char *sha1_file_directory = get_object_directory();
 156                 int len = strlen(sha1_file_directory);
 157                 base = xmalloc(len + 60);
 158                 memcpy(base, sha1_file_directory, len);
 159                 memset(base+len, 0, 60);
 160                 base[len] = '/';
 161                 base[len+3] = '/';
 162                 name = base + len + 1;
 163         }
 164         fill_sha1_path(name, sha1);
 165         return base;
 166 }
 167
 168 char *sha1_pack_name(const unsigned char *sha1)
 169 {
 170         static const char hex[] = "0123456789abcdef";
 171         static char *name, *base, *buf;
 172         int i;
 173
 174         if (!base) {
 175                 const char *sha1_file_directory = get_object_directory();
 176                 int len = strlen(sha1_file_directory);
 177                 base = xmalloc(len + 60);
 178                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 179                 name = base + len + 11;
 180         }
 181
 182         buf = name;
 183
 184         for (i = 0; i < 20; i++) {
 185                 unsigned int val = *sha1++;
 186                 *buf++ = hex[val >> 4];
 187                 *buf++ = hex[val & 0xf];
 188         }
 189
 190         return base;
 191 }
 192
 193 char *sha1_pack_index_name(const unsigned char *sha1)
 194 {
 195         static const char hex[] = "0123456789abcdef";
 196         static char *name, *base, *buf;
 197         int i;
 198
 199         if (!base) {
 200                 const char *sha1_file_directory = get_object_directory();
 201                 int len = strlen(sha1_file_directory);
 202                 base = xmalloc(len + 60);
 203                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 204                 name = base + len + 11;
 205         }
 206
 207         buf = name;
 208
 209         for (i = 0; i < 20; i++) {
 210                 unsigned int val = *sha1++;
 211                 *buf++ = hex[val >> 4];
 212                 *buf++ = hex[val & 0xf];
 213         }
 214
 215         return base;
 216 }
 217
 218 struct alternate_object_database *alt_odb_list;
 219 static struct alternate_object_database **alt_odb_tail;
 220
 221 static void read_info_alternates(const char * alternates, int depth);
 222
 223 /*
 224  * Prepare alternate object database registry.
 225  *
 226  * The variable alt_odb_list points at the list of struct
 227  * alternate_object_database.  The elements on this list come from
 228  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 229  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 230  * whose contents is similar to that environment variable but can be
 231  * LF separated.  Its base points at a statically allocated buffer that
 232  * contains "/the/directory/corresponding/to/.git/objects/...", while
 233  * its name points just after the slash at the end of ".git/objects/"
 234  * in the example above, and has enough space to hold 40-byte hex
 235  * SHA1, an extra slash for the first level indirection, and the
 236  * terminating NUL.
 237  */
 238 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 239 {
 240         struct stat st;
 241         const char *objdir = get_object_directory();
 242         struct alternate_object_database *ent;
 243         struct alternate_object_database *alt;
 244         /* 43 = 40-byte + 2 '/' + terminating NUL */
 245         int pfxlen = len;
 246         int entlen = pfxlen + 43;
 247         int base_len = -1;
 248
 249         if (*entry != '/' && relative_base) {
 250                 /* Relative alt-odb */
 251                 if (base_len < 0)
 252                         base_len = strlen(relative_base) + 1;
 253                 entlen += base_len;
 254                 pfxlen += base_len;
 255         }
 256         ent = xmalloc(sizeof(*ent) + entlen);
 257
 258         if (*entry != '/' && relative_base) {
 259                 memcpy(ent->base, relative_base, base_len - 1);
 260                 ent->base[base_len - 1] = '/';
 261                 memcpy(ent->base + base_len, entry, len);
 262         }
 263         else
 264                 memcpy(ent->base, entry, pfxlen);
 265
 266         ent->name = ent->base + pfxlen + 1;
 267         ent->base[pfxlen + 3] = '/';
 268         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 269
 270         /* Detect cases where alternate disappeared */
 271         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 272                 error("object directory %s does not exist; "
 273                       "check .git/objects/info/alternates.",
 274                       ent->base);
 275                 free(ent);
 276                 return -1;
 277         }
 278
 279         /* Prevent the common mistake of listing the same
 280          * thing twice, or object directory itself.
 281          */
 282         for (alt = alt_odb_list; alt; alt = alt->next) {
 283                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 284                         free(ent);
 285                         return -1;
 286                 }
 287         }
 288         if (!memcmp(ent->base, objdir, pfxlen)) {
 289                 free(ent);
 290                 return -1;
 291         }
 292
 293         /* add the alternate entry */
 294         *alt_odb_tail = ent;
 295         alt_odb_tail = &(ent->next);
 296         ent->next = NULL;
 297
 298         /* recursively add alternates */
 299         read_info_alternates(ent->base, depth + 1);
 300
 301         ent->base[pfxlen] = '/';
 302
 303         return 0;
 304 }
 305
 306 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 307                                  const char *relative_base, int depth)
 308 {
 309         const char *cp, *last;
 310
 311         if (depth > 5) {
 312                 error("%s: ignoring alternate object stores, nesting too deep.",
 313                                 relative_base);
 314                 return;
 315         }
 316
 317         last = alt;
 318         while (last < ep) {
 319                 cp = last;
 320                 if (cp < ep && *cp == '#') {
 321                         while (cp < ep && *cp != sep)
 322                                 cp++;
 323                         last = cp + 1;
 324                         continue;
 325                 }
 326                 while (cp < ep && *cp != sep)
 327                         cp++;
 328                 if (last != cp) {
 329                         if ((*last != '/') && depth) {
 330                                 error("%s: ignoring relative alternate object store %s",
 331                                                 relative_base, last);
 332                         } else {
 333                                 link_alt_odb_entry(last, cp - last,
 334                                                 relative_base, depth);
 335                         }
 336                 }
 337                 while (cp < ep && *cp == sep)
 338                         cp++;
 339                 last = cp;
 340         }
 341 }
 342
 343 static void read_info_alternates(const char * relative_base, int depth)
 344 {
 345         char *map;
 346         struct stat st;
 347         char path[PATH_MAX];
 348         int fd;
 349
 350         sprintf(path, "%s/info/alternates", relative_base);
 351         fd = open(path, O_RDONLY);
 352         if (fd < 0)
 353                 return;
 354         if (fstat(fd, &st) || (st.st_size == 0)) {
 355                 close(fd);
 356                 return;
 357         }
 358         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 359         close(fd);
 360         if (map == MAP_FAILED)
 361                 return;
 362
 363         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 364
 365         munmap(map, st.st_size);
 366 }
 367
 368 void prepare_alt_odb(void)
 369 {
 370         char *alt;
 371
 372         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 373         if (!alt) alt = "";
 374
 375         if (alt_odb_tail)
 376                 return;
 377         alt_odb_tail = &alt_odb_list;
 378         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 379
 380         read_info_alternates(get_object_directory(), 0);
 381 }
 382
 383 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 384 {
 385         char *name = sha1_file_name(sha1);
 386         struct alternate_object_database *alt;
 387
 388         if (!stat(name, st))
 389                 return name;
 390         prepare_alt_odb();
 391         for (alt = alt_odb_list; alt; alt = alt->next) {
 392                 name = alt->name;
 393                 fill_sha1_path(name, sha1);
 394                 if (!stat(alt->base, st))
 395                         return alt->base;
 396         }
 397         return NULL;
 398 }
 399
 400 #define PACK_MAX_SZ (1<<26)
 401 static int pack_used_ctr;
 402 static unsigned long pack_mapped;
 403 struct packed_git *packed_git;
 404
 405 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 406                                 void **idx_map_)
 407 {
 408         void *idx_map;
 409         unsigned int *index;
 410         unsigned long idx_size;
 411         int nr, i;
 412         int fd = open(path, O_RDONLY);
 413         struct stat st;
 414         if (fd < 0)
 415                 return -1;
 416         if (fstat(fd, &st)) {
 417                 close(fd);
 418                 return -1;
 419         }
 420         idx_size = st.st_size;
 421         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 422         close(fd);
 423         if (idx_map == MAP_FAILED)
 424                 return -1;
 425
 426         index = idx_map;
 427         *idx_map_ = idx_map;
 428         *idx_size_ = idx_size;
 429
 430         /* check index map */
 431         if (idx_size < 4*256 + 20 + 20)
 432                 return error("index file too small");
 433         nr = 0;
 434         for (i = 0; i < 256; i++) {
 435                 unsigned int n = ntohl(index[i]);
 436                 if (n < nr)
 437                         return error("non-monotonic index");
 438                 nr = n;
 439         }
 440
 441         /*
 442          * Total size:
 443          *  - 256 index entries 4 bytes each
 444          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 445          *  - 20-byte SHA1 of the packfile
 446          *  - 20-byte SHA1 file checksum
 447          */
 448         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 449                 return error("wrong index file size");
 450
 451         return 0;
 452 }
 453
 454 static int unuse_one_packed_git(void)
 455 {
 456         struct packed_git *p, *lru = NULL;
 457
 458         for (p = packed_git; p; p = p->next) {
 459                 if (p->pack_use_cnt || !p->pack_base)
 460                         continue;
 461                 if (!lru || p->pack_last_used < lru->pack_last_used)
 462                         lru = p;
 463         }
 464         if (!lru)
 465                 return 0;
 466         munmap(lru->pack_base, lru->pack_size);
 467         lru->pack_base = NULL;
 468         return 1;
 469 }
 470
 471 void unuse_packed_git(struct packed_git *p)
 472 {
 473         p->pack_use_cnt--;
 474 }
 475
 476 int use_packed_git(struct packed_git *p)
 477 {
 478         if (!p->pack_size) {
 479                 struct stat st;
 480                 // We created the struct before we had the pack
 481                 stat(p->pack_name, &st);
 482                 if (!S_ISREG(st.st_mode))
 483                         die("packfile %s not a regular file", p->pack_name);
 484                 p->pack_size = st.st_size;
 485         }
 486         if (!p->pack_base) {
 487                 int fd;
 488                 struct stat st;
 489                 void *map;
 490
 491                 pack_mapped += p->pack_size;
 492                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 493                         ; /* nothing */
 494                 fd = open(p->pack_name, O_RDONLY);
 495                 if (fd < 0)
 496                         die("packfile %s cannot be opened", p->pack_name);
 497                 if (fstat(fd, &st)) {
 498                         close(fd);
 499                         die("packfile %s cannot be opened", p->pack_name);
 500                 }
 501                 if (st.st_size != p->pack_size)
 502                         die("packfile %s size mismatch.", p->pack_name);
 503                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 504                 close(fd);
 505                 if (map == MAP_FAILED)
 506                         die("packfile %s cannot be mapped.", p->pack_name);
 507                 p->pack_base = map;
 508
 509                 /* Check if the pack file matches with the index file.
 510                  * this is cheap.
 511                  */
 512                 if (memcmp((char*)(p->index_base) + p->index_size - 40,
 513                            p->pack_base + p->pack_size - 20, 20)) {
 514
 515                         die("packfile %s does not match index.", p->pack_name);
 516                 }
 517         }
 518         p->pack_last_used = pack_used_ctr++;
 519         p->pack_use_cnt++;
 520         return 0;
 521 }
 522
 523 struct packed_git *add_packed_git(char *path, int path_len, int local)
 524 {
 525         struct stat st;
 526         struct packed_git *p;
 527         unsigned long idx_size;
 528         void *idx_map;
 529         unsigned char sha1[20];
 530
 531         if (check_packed_git_idx(path, &idx_size, &idx_map))
 532                 return NULL;
 533
 534         /* do we have a corresponding .pack file? */
 535         strcpy(path + path_len - 4, ".pack");
 536         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 537                 munmap(idx_map, idx_size);
 538                 return NULL;
 539         }
 540         /* ok, it looks sane as far as we can check without
 541          * actually mapping the pack file.
 542          */
 543         p = xmalloc(sizeof(*p) + path_len + 2);
 544         strcpy(p->pack_name, path);
 545         p->index_size = idx_size;
 546         p->pack_size = st.st_size;
 547         p->index_base = idx_map;
 548         p->next = NULL;
 549         p->pack_base = NULL;
 550         p->pack_last_used = 0;
 551         p->pack_use_cnt = 0;
 552         p->pack_local = local;
 553         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 554                 memcpy(p->sha1, sha1, 20);
 555         return p;
 556 }
 557
 558 struct packed_git *parse_pack_index(unsigned char *sha1)
 559 {
 560         char *path = sha1_pack_index_name(sha1);
 561         return parse_pack_index_file(sha1, path);
 562 }
 563
 564 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 565 {
 566         struct packed_git *p;
 567         unsigned long idx_size;
 568         void *idx_map;
 569         char *path;
 570
 571         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 572                 return NULL;
 573
 574         path = sha1_pack_name(sha1);
 575
 576         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 577         strcpy(p->pack_name, path);
 578         p->index_size = idx_size;
 579         p->pack_size = 0;
 580         p->index_base = idx_map;
 581         p->next = NULL;
 582         p->pack_base = NULL;
 583         p->pack_last_used = 0;
 584         p->pack_use_cnt = 0;
 585         memcpy(p->sha1, sha1, 20);
 586         return p;
 587 }
 588
 589 void install_packed_git(struct packed_git *pack)
 590 {
 591         pack->next = packed_git;
 592         packed_git = pack;
 593 }
 594
 595 static void prepare_packed_git_one(char *objdir, int local)
 596 {
 597         char path[PATH_MAX];
 598         int len;
 599         DIR *dir;
 600         struct dirent *de;
 601
 602         sprintf(path, "%s/pack", objdir);
 603         len = strlen(path);
 604         dir = opendir(path);
 605         if (!dir) {
 606                 if (errno != ENOENT)
 607                         error("unable to open object pack directory: %s: %s",
 608                               path, strerror(errno));
 609                 return;
 610         }
 611         path[len++] = '/';
 612         while ((de = readdir(dir)) != NULL) {
 613                 int namelen = strlen(de->d_name);
 614                 struct packed_git *p;
 615
 616                 if (strcmp(de->d_name + namelen - 4, ".idx"))
 617                         continue;
 618
 619                 /* we have .idx.  Is it a file we can map? */
 620                 strcpy(path + len, de->d_name);
 621                 p = add_packed_git(path, len + namelen, local);
 622                 if (!p)
 623                         continue;
 624                 p->next = packed_git;
 625                 packed_git = p;
 626         }
 627         closedir(dir);
 628 }
 629
 630 void prepare_packed_git(void)
 631 {
 632         static int run_once = 0;
 633         struct alternate_object_database *alt;
 634
 635         if (run_once)
 636                 return;
 637         prepare_packed_git_one(get_object_directory(), 1);
 638         prepare_alt_odb();
 639         for (alt = alt_odb_list; alt; alt = alt->next) {
 640                 alt->name[-1] = 0;
 641                 prepare_packed_git_one(alt->base, 0);
 642                 alt->name[-1] = '/';
 643         }
 644         run_once = 1;
 645 }
 646
 647 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 648 {
 649         char header[100];
 650         unsigned char real_sha1[20];
 651         SHA_CTX c;
 652
 653         SHA1_Init(&c);
 654         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 655         SHA1_Update(&c, map, size);
 656         SHA1_Final(real_sha1, &c);
 657         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 658 }
 659
 660 static void *map_sha1_file_internal(const unsigned char *sha1,
 661                                     unsigned long *size)
 662 {
 663         struct stat st;
 664         void *map;
 665         int fd;
 666         char *filename = find_sha1_file(sha1, &st);
 667
 668         if (!filename) {
 669                 return NULL;
 670         }
 671
 672         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 673         if (fd < 0) {
 674                 /* See if it works without O_NOATIME */
 675                 switch (sha1_file_open_flag) {
 676                 default:
 677                         fd = open(filename, O_RDONLY);
 678                         if (fd >= 0)
 679                                 break;
 680                 /* Fallthrough */
 681                 case 0:
 682                         return NULL;
 683                 }
 684
 685                 /* If it failed once, it will probably fail again.
 686                  * Stop using O_NOATIME
 687                  */
 688                 sha1_file_open_flag = 0;
 689         }
 690         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 691         close(fd);
 692         if (map == MAP_FAILED)
 693                 return NULL;
 694         *size = st.st_size;
 695         return map;
 696 }
 697
 698 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 699 {
 700         /* Get the data stream */
 701         memset(stream, 0, sizeof(*stream));
 702         stream->next_in = map;
 703         stream->avail_in = mapsize;
 704         stream->next_out = buffer;
 705         stream->avail_out = size;
 706
 707         inflateInit(stream);
 708         return inflate(stream, 0);
 709 }
 710
 711 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 712 {
 713         int bytes = strlen(buffer) + 1;
 714         unsigned char *buf = xmalloc(1+size);
 715
 716         memcpy(buf, buffer + bytes, stream->total_out - bytes);
 717         bytes = stream->total_out - bytes;
 718         if (bytes < size) {
 719                 stream->next_out = buf + bytes;
 720                 stream->avail_out = size - bytes;
 721                 while (inflate(stream, Z_FINISH) == Z_OK)
 722                         /* nothing */;
 723         }
 724         buf[size] = 0;
 725         inflateEnd(stream);
 726         return buf;
 727 }
 728
 729 /*
 730  * We used to just use "sscanf()", but that's actually way
 731  * too permissive for what we want to check. So do an anal
 732  * object header parse by hand.
 733  */
 734 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 735 {
 736         int i;
 737         unsigned long size;
 738
 739         /*
 740          * The type can be at most ten bytes (including the
 741          * terminating '\0' that we add), and is followed by
 742          * a space.
 743          */
 744         i = 10;
 745         for (;;) {
 746                 char c = *hdr++;
 747                 if (c == ' ')
 748                         break;
 749                 if (!--i)
 750                         return -1;
 751                 *type++ = c;
 752         }
 753         *type = 0;
 754
 755         /*
 756          * The length must follow immediately, and be in canonical
 757          * decimal format (ie "010" is not valid).
 758          */
 759         size = *hdr++ - '0';
 760         if (size > 9)
 761                 return -1;
 762         if (size) {
 763                 for (;;) {
 764                         unsigned long c = *hdr - '0';
 765                         if (c > 9)
 766                                 break;
 767                         hdr++;
 768                         size = size * 10 + c;
 769                 }
 770         }
 771         *sizep = size;
 772
 773         /*
 774          * The length must be followed by a zero byte
 775          */
 776         return *hdr ? -1 : 0;
 777 }
 778
 779 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 780 {
 781         int ret;
 782         z_stream stream;
 783         char hdr[8192];
 784
 785         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 786         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 787                 return NULL;
 788
 789         return unpack_sha1_rest(&stream, hdr, *size);
 790 }
 791
 792 /* forward declaration for a mutually recursive function */
 793 static int packed_object_info(struct pack_entry *entry,
 794                               char *type, unsigned long *sizep);
 795
 796 static int packed_delta_info(unsigned char *base_sha1,
 797                              unsigned long delta_size,
 798                              unsigned long left,
 799                              char *type,
 800                              unsigned long *sizep,
 801                              struct packed_git *p)
 802 {
 803         struct pack_entry base_ent;
 804
 805         if (left < 20)
 806                 die("truncated pack file");
 807
 808         /* The base entry _must_ be in the same pack */
 809         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 810                 die("failed to find delta-pack base object %s",
 811                     sha1_to_hex(base_sha1));
 812
 813         /* We choose to only get the type of the base object and
 814          * ignore potentially corrupt pack file that expects the delta
 815          * based on a base with a wrong size.  This saves tons of
 816          * inflate() calls.
 817          */
 818
 819         if (packed_object_info(&base_ent, type, NULL))
 820                 die("cannot get info for delta-pack base");
 821
 822         if (sizep) {
 823                 const unsigned char *data;
 824                 unsigned char delta_head[64];
 825                 unsigned long result_size;
 826                 z_stream stream;
 827                 int st;
 828
 829                 memset(&stream, 0, sizeof(stream));
 830
 831                 data = stream.next_in = base_sha1 + 20;
 832                 stream.avail_in = left - 20;
 833                 stream.next_out = delta_head;
 834                 stream.avail_out = sizeof(delta_head);
 835
 836                 inflateInit(&stream);
 837                 st = inflate(&stream, Z_FINISH);
 838                 inflateEnd(&stream);
 839                 if ((st != Z_STREAM_END) &&
 840                     stream.total_out != sizeof(delta_head))
 841                         die("delta data unpack-initial failed");
 842
 843                 /* Examine the initial part of the delta to figure out
 844                  * the result size.
 845                  */
 846                 data = delta_head;
 847
 848                 /* ignore base size */
 849                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 850
 851                 /* Read the result size */
 852                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 853                 *sizep = result_size;
 854         }
 855         return 0;
 856 }
 857
 858 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 859         enum object_type *type, unsigned long *sizep)
 860 {
 861         unsigned shift;
 862         unsigned char *pack, c;
 863         unsigned long size;
 864
 865         if (offset >= p->pack_size)
 866                 die("object offset outside of pack file");
 867
 868         pack =  p->pack_base + offset;
 869         c = *pack++;
 870         offset++;
 871         *type = (c >> 4) & 7;
 872         size = c & 15;
 873         shift = 4;
 874         while (c & 0x80) {
 875                 if (offset >= p->pack_size)
 876                         die("object offset outside of pack file");
 877                 c = *pack++;
 878                 offset++;
 879                 size += (c & 0x7f) << shift;
 880                 shift += 7;
 881         }
 882         *sizep = size;
 883         return offset;
 884 }
 885
 886 int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
 887                            unsigned char *base, unsigned long *sizep,
 888                            enum object_type *kindp)
 889 {
 890         unsigned long ptr;
 891         int status = -1;
 892
 893         use_packed_git(p);
 894         ptr = offset;
 895         ptr = unpack_object_header(p, ptr, kindp, sizep);
 896         if (*kindp != OBJ_DELTA)
 897                 goto done;
 898         memcpy(base, p->pack_base + ptr, 20);
 899         status = 0;
 900  done:
 901         unuse_packed_git(p);
 902         return status;
 903 }
 904
 905 void packed_object_info_detail(struct pack_entry *e,
 906                                char *type,
 907                                unsigned long *size,
 908                                unsigned long *store_size,
 909                                unsigned int *delta_chain_length,
 910                                unsigned char *base_sha1)
 911 {
 912         struct packed_git *p = e->p;
 913         unsigned long offset;
 914         unsigned char *pack;
 915         enum object_type kind;
 916
 917         offset = unpack_object_header(p, e->offset, &kind, size);
 918         pack = p->pack_base + offset;
 919         if (kind != OBJ_DELTA)
 920                 *delta_chain_length = 0;
 921         else {
 922                 unsigned int chain_length = 0;
 923                 if (p->pack_size <= offset + 20)
 924                         die("pack file %s records an incomplete delta base",
 925                             p->pack_name);
 926                 memcpy(base_sha1, pack, 20);
 927                 do {
 928                         struct pack_entry base_ent;
 929                         unsigned long junk;
 930
 931                         find_pack_entry_one(pack, &base_ent, p);
 932                         offset = unpack_object_header(p, base_ent.offset,
 933                                                       &kind, &junk);
 934                         pack = p->pack_base + offset;
 935                         chain_length++;
 936                 } while (kind == OBJ_DELTA);
 937                 *delta_chain_length = chain_length;
 938         }
 939         switch (kind) {
 940         case OBJ_COMMIT:
 941                 strcpy(type, commit_type);
 942                 break;
 943         case OBJ_TREE:
 944                 strcpy(type, tree_type);
 945                 break;
 946         case OBJ_BLOB:
 947                 strcpy(type, blob_type);
 948                 break;
 949         case OBJ_TAG:
 950                 strcpy(type, tag_type);
 951                 break;
 952         default:
 953                 die("corrupted pack file %s containing object of kind %d",
 954                     p->pack_name, kind);
 955         }
 956         *store_size = 0; /* notyet */
 957 }
 958
 959 static int packed_object_info(struct pack_entry *entry,
 960                               char *type, unsigned long *sizep)
 961 {
 962         struct packed_git *p = entry->p;
 963         unsigned long offset, size, left;
 964         unsigned char *pack;
 965         enum object_type kind;
 966         int retval;
 967
 968         if (use_packed_git(p))
 969                 die("cannot map packed file");
 970
 971         offset = unpack_object_header(p, entry->offset, &kind, &size);
 972         pack = p->pack_base + offset;
 973         left = p->pack_size - offset;
 974
 975         switch (kind) {
 976         case OBJ_DELTA:
 977                 retval = packed_delta_info(pack, size, left, type, sizep, p);
 978                 unuse_packed_git(p);
 979                 return retval;
 980         case OBJ_COMMIT:
 981                 strcpy(type, commit_type);
 982                 break;
 983         case OBJ_TREE:
 984                 strcpy(type, tree_type);
 985                 break;
 986         case OBJ_BLOB:
 987                 strcpy(type, blob_type);
 988                 break;
 989         case OBJ_TAG:
 990                 strcpy(type, tag_type);
 991                 break;
 992         default:
 993                 die("corrupted pack file %s containing object of kind %d",
 994                     p->pack_name, kind);
 995         }
 996         if (sizep)
 997                 *sizep = size;
 998         unuse_packed_git(p);
 999         return 0;
1000 }
1001
1002 /* forward declaration for a mutually recursive function */
1003 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
1004
1005 static void *unpack_delta_entry(unsigned char *base_sha1,
1006                                 unsigned long delta_size,
1007                                 unsigned long left,
1008                                 char *type,
1009                                 unsigned long *sizep,
1010                                 struct packed_git *p)
1011 {
1012         struct pack_entry base_ent;
1013         void *data, *delta_data, *result, *base;
1014         unsigned long data_size, result_size, base_size;
1015         z_stream stream;
1016         int st;
1017
1018         if (left < 20)
1019                 die("truncated pack file");
1020
1021         /* The base entry _must_ be in the same pack */
1022         if (!find_pack_entry_one(base_sha1, &base_ent, p))
1023                 die("failed to find delta-pack base object %s",
1024                     sha1_to_hex(base_sha1));
1025         base = unpack_entry_gently(&base_ent, type, &base_size);
1026         if (!base)
1027                 die("failed to read delta-pack base object %s",
1028                     sha1_to_hex(base_sha1));
1029
1030         data = base_sha1 + 20;
1031         data_size = left - 20;
1032         delta_data = xmalloc(delta_size);
1033
1034         memset(&stream, 0, sizeof(stream));
1035
1036         stream.next_in = data;
1037         stream.avail_in = data_size;
1038         stream.next_out = delta_data;
1039         stream.avail_out = delta_size;
1040
1041         inflateInit(&stream);
1042         st = inflate(&stream, Z_FINISH);
1043         inflateEnd(&stream);
1044         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
1045                 die("delta data unpack failed");
1046
1047         result = patch_delta(base, base_size,
1048                              delta_data, delta_size,
1049                              &result_size);
1050         if (!result)
1051                 die("failed to apply delta");
1052         free(delta_data);
1053         free(base);
1054         *sizep = result_size;
1055         return result;
1056 }
1057
1058 static void *unpack_non_delta_entry(unsigned char *data,
1059                                     unsigned long size,
1060                                     unsigned long left)
1061 {
1062         int st;
1063         z_stream stream;
1064         unsigned char *buffer;
1065
1066         buffer = xmalloc(size + 1);
1067         buffer[size] = 0;
1068         memset(&stream, 0, sizeof(stream));
1069         stream.next_in = data;
1070         stream.avail_in = left;
1071         stream.next_out = buffer;
1072         stream.avail_out = size;
1073
1074         inflateInit(&stream);
1075         st = inflate(&stream, Z_FINISH);
1076         inflateEnd(&stream);
1077         if ((st != Z_STREAM_END) || stream.total_out != size) {
1078                 free(buffer);
1079                 return NULL;
1080         }
1081
1082         return buffer;
1083 }
1084
1085 static void *unpack_entry(struct pack_entry *entry,
1086                           char *type, unsigned long *sizep)
1087 {
1088         struct packed_git *p = entry->p;
1089         void *retval;
1090
1091         if (use_packed_git(p))
1092                 die("cannot map packed file");
1093         retval = unpack_entry_gently(entry, type, sizep);
1094         unuse_packed_git(p);
1095         if (!retval)
1096                 die("corrupted pack file %s", p->pack_name);
1097         return retval;
1098 }
1099
1100 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
1101 void *unpack_entry_gently(struct pack_entry *entry,
1102                           char *type, unsigned long *sizep)
1103 {
1104         struct packed_git *p = entry->p;
1105         unsigned long offset, size, left;
1106         unsigned char *pack;
1107         enum object_type kind;
1108         void *retval;
1109
1110         offset = unpack_object_header(p, entry->offset, &kind, &size);
1111         pack = p->pack_base + offset;
1112         left = p->pack_size - offset;
1113         switch (kind) {
1114         case OBJ_DELTA:
1115                 retval = unpack_delta_entry(pack, size, left, type, sizep, p);
1116                 return retval;
1117         case OBJ_COMMIT:
1118                 strcpy(type, commit_type);
1119                 break;
1120         case OBJ_TREE:
1121                 strcpy(type, tree_type);
1122                 break;
1123         case OBJ_BLOB:
1124                 strcpy(type, blob_type);
1125                 break;
1126         case OBJ_TAG:
1127                 strcpy(type, tag_type);
1128                 break;
1129         default:
1130                 return NULL;
1131         }
1132         *sizep = size;
1133         retval = unpack_non_delta_entry(pack, size, left);
1134         return retval;
1135 }
1136
1137 int num_packed_objects(const struct packed_git *p)
1138 {
1139         /* See check_packed_git_idx() */
1140         return (p->index_size - 20 - 20 - 4*256) / 24;
1141 }
1142
1143 int nth_packed_object_sha1(const struct packed_git *p, int n,
1144                            unsigned char* sha1)
1145 {
1146         void *index = p->index_base + 256;
1147         if (n < 0 || num_packed_objects(p) <= n)
1148                 return -1;
1149         memcpy(sha1, (index + 24 * n + 4), 20);
1150         return 0;
1151 }
1152
1153 int find_pack_entry_one(const unsigned char *sha1,
1154                         struct pack_entry *e, struct packed_git *p)
1155 {
1156         unsigned int *level1_ofs = p->index_base;
1157         int hi = ntohl(level1_ofs[*sha1]);
1158         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1159         void *index = p->index_base + 256;
1160
1161         do {
1162                 int mi = (lo + hi) / 2;
1163                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1164                 if (!cmp) {
1165                         e->offset = ntohl(*((uint32_t *)(index + 24 * mi)));
1166                         memcpy(e->sha1, sha1, 20);
1167                         e->p = p;
1168                         return 1;
1169                 }
1170                 if (cmp > 0)
1171                         hi = mi;
1172                 else
1173                         lo = mi+1;
1174         } while (lo < hi);
1175         return 0;
1176 }
1177
1178 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1179 {
1180         struct packed_git *p;
1181         prepare_packed_git();
1182
1183         for (p = packed_git; p; p = p->next) {
1184                 if (find_pack_entry_one(sha1, e, p))
1185                         return 1;
1186         }
1187         return 0;
1188 }
1189
1190 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1191                                   struct packed_git *packs)
1192 {
1193         struct packed_git *p;
1194         struct pack_entry e;
1195
1196         for (p = packs; p; p = p->next) {
1197                 if (find_pack_entry_one(sha1, &e, p))
1198                         return p;
1199         }
1200         return NULL;
1201
1202 }
1203
1204 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1205 {
1206         int status;
1207         unsigned long mapsize, size;
1208         void *map;
1209         z_stream stream;
1210         char hdr[128];
1211
1212         map = map_sha1_file_internal(sha1, &mapsize);
1213         if (!map) {
1214                 struct pack_entry e;
1215
1216                 if (!find_pack_entry(sha1, &e))
1217                         return error("unable to find %s", sha1_to_hex(sha1));
1218                 return packed_object_info(&e, type, sizep);
1219         }
1220         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1221                 status = error("unable to unpack %s header",
1222                                sha1_to_hex(sha1));
1223         if (parse_sha1_header(hdr, type, &size) < 0)
1224                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1225         else {
1226                 status = 0;
1227                 if (sizep)
1228                         *sizep = size;
1229         }
1230         inflateEnd(&stream);
1231         munmap(map, mapsize);
1232         return status;
1233 }
1234
1235 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1236 {
1237         struct pack_entry e;
1238
1239         if (!find_pack_entry(sha1, &e)) {
1240                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1241                 return NULL;
1242         }
1243         return unpack_entry(&e, type, size);
1244 }
1245
1246 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1247 {
1248         unsigned long mapsize;
1249         void *map, *buf;
1250         struct pack_entry e;
1251
1252         if (find_pack_entry(sha1, &e))
1253                 return read_packed_sha1(sha1, type, size);
1254         map = map_sha1_file_internal(sha1, &mapsize);
1255         if (map) {
1256                 buf = unpack_sha1_file(map, mapsize, type, size);
1257                 munmap(map, mapsize);
1258                 return buf;
1259         }
1260         return NULL;
1261 }
1262
1263 void *read_object_with_reference(const unsigned char *sha1,
1264                                  const char *required_type,
1265                                  unsigned long *size,
1266                                  unsigned char *actual_sha1_return)
1267 {
1268         char type[20];
1269         void *buffer;
1270         unsigned long isize;
1271         unsigned char actual_sha1[20];
1272
1273         memcpy(actual_sha1, sha1, 20);
1274         while (1) {
1275                 int ref_length = -1;
1276                 const char *ref_type = NULL;
1277
1278                 buffer = read_sha1_file(actual_sha1, type, &isize);
1279                 if (!buffer)
1280                         return NULL;
1281                 if (!strcmp(type, required_type)) {
1282                         *size = isize;
1283                         if (actual_sha1_return)
1284                                 memcpy(actual_sha1_return, actual_sha1, 20);
1285                         return buffer;
1286                 }
1287                 /* Handle references */
1288                 else if (!strcmp(type, commit_type))
1289                         ref_type = "tree ";
1290                 else if (!strcmp(type, tag_type))
1291                         ref_type = "object ";
1292                 else {
1293                         free(buffer);
1294                         return NULL;
1295                 }
1296                 ref_length = strlen(ref_type);
1297
1298                 if (memcmp(buffer, ref_type, ref_length) ||
1299                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
1300                         free(buffer);
1301                         return NULL;
1302                 }
1303                 free(buffer);
1304                 /* Now we have the ID of the referred-to object in
1305                  * actual_sha1.  Check again. */
1306         }
1307 }
1308
1309 char *write_sha1_file_prepare(void *buf,
1310                               unsigned long len,
1311                               const char *type,
1312                               unsigned char *sha1,
1313                               unsigned char *hdr,
1314                               int *hdrlen)
1315 {
1316         SHA_CTX c;
1317
1318         /* Generate the header */
1319         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1320
1321         /* Sha1.. */
1322         SHA1_Init(&c);
1323         SHA1_Update(&c, hdr, *hdrlen);
1324         SHA1_Update(&c, buf, len);
1325         SHA1_Final(sha1, &c);
1326
1327         return sha1_file_name(sha1);
1328 }
1329
1330 /*
1331  * Link the tempfile to the final place, possibly creating the
1332  * last directory level as you do so.
1333  *
1334  * Returns the errno on failure, 0 on success.
1335  */
1336 static int link_temp_to_file(const char *tmpfile, char *filename)
1337 {
1338         int ret;
1339
1340         if (!link(tmpfile, filename))
1341                 return 0;
1342
1343         /*
1344          * Try to mkdir the last path component if that failed
1345          * with an ENOENT.
1346          *
1347          * Re-try the "link()" regardless of whether the mkdir
1348          * succeeds, since a race might mean that somebody
1349          * else succeeded.
1350          */
1351         ret = errno;
1352         if (ret == ENOENT) {
1353                 char *dir = strrchr(filename, '/');
1354                 if (dir) {
1355                         *dir = 0;
1356                         mkdir(filename, 0777);
1357                         if (adjust_shared_perm(filename))
1358                                 return -2;
1359                         *dir = '/';
1360                         if (!link(tmpfile, filename))
1361                                 return 0;
1362                         ret = errno;
1363                 }
1364         }
1365         return ret;
1366 }
1367
1368 /*
1369  * Move the just written object into its final resting place
1370  */
1371 int move_temp_to_file(const char *tmpfile, char *filename)
1372 {
1373         int ret = link_temp_to_file(tmpfile, filename);
1374
1375         /*
1376          * Coda hack - coda doesn't like cross-directory links,
1377          * so we fall back to a rename, which will mean that it
1378          * won't be able to check collisions, but that's not a
1379          * big deal.
1380          *
1381          * The same holds for FAT formatted media.
1382          *
1383          * When this succeeds, we just return 0. We have nothing
1384          * left to unlink.
1385          */
1386         if (ret && ret != EEXIST) {
1387                 if (!rename(tmpfile, filename))
1388                         return 0;
1389                 ret = errno;
1390         }
1391         unlink(tmpfile);
1392         if (ret) {
1393                 if (ret != EEXIST) {
1394                         fprintf(stderr, "unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1395                         return -1;
1396                 }
1397                 /* FIXME!!! Collision check here ? */
1398         }
1399
1400         return 0;
1401 }
1402
1403 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1404 {
1405         int size;
1406         unsigned char *compressed;
1407         z_stream stream;
1408         unsigned char sha1[20];
1409         char *filename;
1410         static char tmpfile[PATH_MAX];
1411         unsigned char hdr[50];
1412         int fd, hdrlen;
1413
1414         /* Normally if we have it in the pack then we do not bother writing
1415          * it out into .git/objects/??/?{38} file.
1416          */
1417         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1418         if (returnsha1)
1419                 memcpy(returnsha1, sha1, 20);
1420         if (has_sha1_file(sha1))
1421                 return 0;
1422         fd = open(filename, O_RDONLY);
1423         if (fd >= 0) {
1424                 /*
1425                  * FIXME!!! We might do collision checking here, but we'd
1426                  * need to uncompress the old file and check it. Later.
1427                  */
1428                 close(fd);
1429                 return 0;
1430         }
1431
1432         if (errno != ENOENT) {
1433                 fprintf(stderr, "sha1 file %s: %s\n", filename, strerror(errno));
1434                 return -1;
1435         }
1436
1437         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1438
1439         fd = mkstemp(tmpfile);
1440         if (fd < 0) {
1441                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1442                 return -1;
1443         }
1444
1445         /* Set it up */
1446         memset(&stream, 0, sizeof(stream));
1447         deflateInit(&stream, Z_BEST_COMPRESSION);
1448         size = deflateBound(&stream, len+hdrlen);
1449         compressed = xmalloc(size);
1450
1451         /* Compress it */
1452         stream.next_out = compressed;
1453         stream.avail_out = size;
1454
1455         /* First header.. */
1456         stream.next_in = hdr;
1457         stream.avail_in = hdrlen;
1458         while (deflate(&stream, 0) == Z_OK)
1459                 /* nothing */;
1460
1461         /* Then the data itself.. */
1462         stream.next_in = buf;
1463         stream.avail_in = len;
1464         while (deflate(&stream, Z_FINISH) == Z_OK)
1465                 /* nothing */;
1466         deflateEnd(&stream);
1467         size = stream.total_out;
1468
1469         if (write(fd, compressed, size) != size)
1470                 die("unable to write file");
1471         fchmod(fd, 0444);
1472         close(fd);
1473         free(compressed);
1474
1475         return move_temp_to_file(tmpfile, filename);
1476 }
1477
1478 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1479 {
1480         ssize_t size;
1481         unsigned long objsize;
1482         int posn = 0;
1483         void *map = map_sha1_file_internal(sha1, &objsize);
1484         void *buf = map;
1485         void *temp_obj = NULL;
1486         z_stream stream;
1487
1488         if (!buf) {
1489                 unsigned char *unpacked;
1490                 unsigned long len;
1491                 char type[20];
1492                 char hdr[50];
1493                 int hdrlen;
1494                 // need to unpack and recompress it by itself
1495                 unpacked = read_packed_sha1(sha1, type, &len);
1496
1497                 hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1498
1499                 /* Set it up */
1500                 memset(&stream, 0, sizeof(stream));
1501                 deflateInit(&stream, Z_BEST_COMPRESSION);
1502                 size = deflateBound(&stream, len + hdrlen);
1503                 temp_obj = buf = xmalloc(size);
1504
1505                 /* Compress it */
1506                 stream.next_out = buf;
1507                 stream.avail_out = size;
1508
1509                 /* First header.. */
1510                 stream.next_in = (void *)hdr;
1511                 stream.avail_in = hdrlen;
1512                 while (deflate(&stream, 0) == Z_OK)
1513                         /* nothing */;
1514
1515                 /* Then the data itself.. */
1516                 stream.next_in = unpacked;
1517                 stream.avail_in = len;
1518                 while (deflate(&stream, Z_FINISH) == Z_OK)
1519                         /* nothing */;
1520                 deflateEnd(&stream);
1521                 free(unpacked);
1522
1523                 objsize = stream.total_out;
1524         }
1525
1526         do {
1527                 size = write(fd, buf + posn, objsize - posn);
1528                 if (size <= 0) {
1529                         if (!size) {
1530                                 fprintf(stderr, "write closed\n");
1531                         } else {
1532                                 perror("write ");
1533                         }
1534                         return -1;
1535                 }
1536                 posn += size;
1537         } while (posn < objsize);
1538
1539         if (map)
1540                 munmap(map, objsize);
1541         if (temp_obj)
1542                 free(temp_obj);
1543
1544         return 0;
1545 }
1546
1547 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1548                        size_t bufsize, size_t *bufposn)
1549 {
1550         char tmpfile[PATH_MAX];
1551         int local;
1552         z_stream stream;
1553         unsigned char real_sha1[20];
1554         unsigned char discard[4096];
1555         int ret;
1556         SHA_CTX c;
1557
1558         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1559
1560         local = mkstemp(tmpfile);
1561         if (local < 0)
1562                 return error("Couldn't open %s for %s",
1563                              tmpfile, sha1_to_hex(sha1));
1564
1565         memset(&stream, 0, sizeof(stream));
1566
1567         inflateInit(&stream);
1568
1569         SHA1_Init(&c);
1570
1571         do {
1572                 ssize_t size;
1573                 if (*bufposn) {
1574                         stream.avail_in = *bufposn;
1575                         stream.next_in = (unsigned char *) buffer;
1576                         do {
1577                                 stream.next_out = discard;
1578                                 stream.avail_out = sizeof(discard);
1579                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1580                                 SHA1_Update(&c, discard, sizeof(discard) -
1581                                             stream.avail_out);
1582                         } while (stream.avail_in && ret == Z_OK);
1583                         write(local, buffer, *bufposn - stream.avail_in);
1584                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1585                                 stream.avail_in);
1586                         *bufposn = stream.avail_in;
1587                         if (ret != Z_OK)
1588                                 break;
1589                 }
1590                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1591                 if (size <= 0) {
1592                         close(local);
1593                         unlink(tmpfile);
1594                         if (!size)
1595                                 return error("Connection closed?");
1596                         perror("Reading from connection");
1597                         return -1;
1598                 }
1599                 *bufposn += size;
1600         } while (1);
1601         inflateEnd(&stream);
1602
1603         close(local);
1604         SHA1_Final(real_sha1, &c);
1605         if (ret != Z_STREAM_END) {
1606                 unlink(tmpfile);
1607                 return error("File %s corrupted", sha1_to_hex(sha1));
1608         }
1609         if (memcmp(sha1, real_sha1, 20)) {
1610                 unlink(tmpfile);
1611                 return error("File %s has bad hash", sha1_to_hex(sha1));
1612         }
1613
1614         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1615 }
1616
1617 int has_pack_index(const unsigned char *sha1)
1618 {
1619         struct stat st;
1620         if (stat(sha1_pack_index_name(sha1), &st))
1621                 return 0;
1622         return 1;
1623 }
1624
1625 int has_pack_file(const unsigned char *sha1)
1626 {
1627         struct stat st;
1628         if (stat(sha1_pack_name(sha1), &st))
1629                 return 0;
1630         return 1;
1631 }
1632
1633 int has_sha1_pack(const unsigned char *sha1)
1634 {
1635         struct pack_entry e;
1636         return find_pack_entry(sha1, &e);
1637 }
1638
1639 int has_sha1_file(const unsigned char *sha1)
1640 {
1641         struct stat st;
1642         struct pack_entry e;
1643
1644         if (find_pack_entry(sha1, &e))
1645                 return 1;
1646         return find_sha1_file(sha1, &st) ? 1 : 0;
1647 }
1648
1649 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1650 {
1651         unsigned long size = 4096;
1652         char *buf = malloc(size);
1653         int iret, ret;
1654         unsigned long off = 0;
1655         unsigned char hdr[50];
1656         int hdrlen;
1657         do {
1658                 iret = read(fd, buf + off, size - off);
1659                 if (iret > 0) {
1660                         off += iret;
1661                         if (off == size) {
1662                                 size *= 2;
1663                                 buf = realloc(buf, size);
1664                         }
1665                 }
1666         } while (iret > 0);
1667         if (iret < 0) {
1668                 free(buf);
1669                 return -1;
1670         }
1671         if (!type)
1672                 type = blob_type;
1673         if (write_object)
1674                 ret = write_sha1_file(buf, off, type, sha1);
1675         else {
1676                 write_sha1_file_prepare(buf, off, type, sha1, hdr, &hdrlen);
1677                 ret = 0;
1678         }
1679         free(buf);
1680         return ret;
1681 }
1682
1683 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1684 {
1685         unsigned long size = st->st_size;
1686         void *buf;
1687         int ret;
1688         unsigned char hdr[50];
1689         int hdrlen;
1690
1691         buf = "";
1692         if (size)
1693                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1694         close(fd);
1695         if (buf == MAP_FAILED)
1696                 return -1;
1697
1698         if (!type)
1699                 type = blob_type;
1700         if (write_object)
1701                 ret = write_sha1_file(buf, size, type, sha1);
1702         else {
1703                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1704                 ret = 0;
1705         }
1706         if (size)
1707                 munmap(buf, size);
1708         return ret;
1709 }
1710
1711 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1712 {
1713         int fd;
1714         char *target;
1715
1716         switch (st->st_mode & S_IFMT) {
1717         case S_IFREG:
1718                 fd = open(path, O_RDONLY);
1719                 if (fd < 0)
1720                         return error("open(\"%s\"): %s", path,
1721                                      strerror(errno));
1722                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1723                         return error("%s: failed to insert into database",
1724                                      path);
1725                 break;
1726         case S_IFLNK:
1727                 target = xmalloc(st->st_size+1);
1728                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1729                         char *errstr = strerror(errno);
1730                         free(target);
1731                         return error("readlink(\"%s\"): %s", path,
1732                                      errstr);
1733                 }
1734                 if (!write_object) {
1735                         unsigned char hdr[50];
1736                         int hdrlen;
1737                         write_sha1_file_prepare(target, st->st_size, blob_type,
1738                                                 sha1, hdr, &hdrlen);
1739                 } else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1740                         return error("%s: failed to insert into database",
1741                                      path);
1742                 free(target);
1743                 break;
1744         default:
1745                 return error("%s: unsupported file type", path);
1746         }
1747         return 0;
1748 }