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

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include "cache.h"
  10 #include "delta.h"
  11 #include "pack.h"
  12 #include "blob.h"
  13 #include "commit.h"
  14 #include "tag.h"
  15 #include "tree.h"
  16
  17 #ifndef O_NOATIME
  18 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  19 #define O_NOATIME 01000000
  20 #else
  21 #define O_NOATIME 0
  22 #endif
  23 #endif
  24
  25 const unsigned char null_sha1[20];
  26
  27 static unsigned int sha1_file_open_flag = O_NOATIME;
  28
  29 signed char hexval_table[256] = {
  30          -1, -1, -1, -1, -1, -1, -1, -1,                /* 00-07 */
  31          -1, -1, -1, -1, -1, -1, -1, -1,                /* 08-0f */
  32          -1, -1, -1, -1, -1, -1, -1, -1,                /* 10-17 */
  33          -1, -1, -1, -1, -1, -1, -1, -1,                /* 18-1f */
  34          -1, -1, -1, -1, -1, -1, -1, -1,                /* 20-27 */
  35          -1, -1, -1, -1, -1, -1, -1, -1,                /* 28-2f */
  36           0,  1,  2,  3,  4,  5,  6,  7,                /* 30-37 */
  37           8,  9, -1, -1, -1, -1, -1, -1,                /* 38-3f */
  38          -1, 10, 11, 12, 13, 14, 15, -1,                /* 40-47 */
  39          -1, -1, -1, -1, -1, -1, -1, -1,                /* 48-4f */
  40          -1, -1, -1, -1, -1, -1, -1, -1,                /* 50-57 */
  41          -1, -1, -1, -1, -1, -1, -1, -1,                /* 58-5f */
  42          -1, 10, 11, 12, 13, 14, 15, -1,                /* 60-67 */
  43          -1, -1, -1, -1, -1, -1, -1, -1,                /* 68-67 */
  44          -1, -1, -1, -1, -1, -1, -1, -1,                /* 70-77 */
  45          -1, -1, -1, -1, -1, -1, -1, -1,                /* 78-7f */
  46          -1, -1, -1, -1, -1, -1, -1, -1,                /* 80-87 */
  47          -1, -1, -1, -1, -1, -1, -1, -1,                /* 88-8f */
  48          -1, -1, -1, -1, -1, -1, -1, -1,                /* 90-97 */
  49          -1, -1, -1, -1, -1, -1, -1, -1,                /* 98-9f */
  50          -1, -1, -1, -1, -1, -1, -1, -1,                /* a0-a7 */
  51          -1, -1, -1, -1, -1, -1, -1, -1,                /* a8-af */
  52          -1, -1, -1, -1, -1, -1, -1, -1,                /* b0-b7 */
  53          -1, -1, -1, -1, -1, -1, -1, -1,                /* b8-bf */
  54          -1, -1, -1, -1, -1, -1, -1, -1,                /* c0-c7 */
  55          -1, -1, -1, -1, -1, -1, -1, -1,                /* c8-cf */
  56          -1, -1, -1, -1, -1, -1, -1, -1,                /* d0-d7 */
  57          -1, -1, -1, -1, -1, -1, -1, -1,                /* d8-df */
  58          -1, -1, -1, -1, -1, -1, -1, -1,                /* e0-e7 */
  59          -1, -1, -1, -1, -1, -1, -1, -1,                /* e8-ef */
  60          -1, -1, -1, -1, -1, -1, -1, -1,                /* f0-f7 */
  61          -1, -1, -1, -1, -1, -1, -1, -1,                /* f8-ff */
  62 };
  63
  64 int get_sha1_hex(const char *hex, unsigned char *sha1)
  65 {
  66         int i;
  67         for (i = 0; i < 20; i++) {
  68                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  69                 if (val & ~0xff)
  70                         return -1;
  71                 *sha1++ = val;
  72                 hex += 2;
  73         }
  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 "xstrdup()" 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         const 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                 struct pack_header *hdr;
 491
 492                 pack_mapped += p->pack_size;
 493                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 494                         ; /* nothing */
 495                 fd = open(p->pack_name, O_RDONLY);
 496                 if (fd < 0)
 497                         die("packfile %s cannot be opened", p->pack_name);
 498                 if (fstat(fd, &st)) {
 499                         close(fd);
 500                         die("packfile %s cannot be opened", p->pack_name);
 501                 }
 502                 if (st.st_size != p->pack_size)
 503                         die("packfile %s size mismatch.", p->pack_name);
 504                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 505                 close(fd);
 506                 if (map == MAP_FAILED)
 507                         die("packfile %s cannot be mapped.", p->pack_name);
 508                 p->pack_base = map;
 509
 510                 /* Check if we understand this pack file.  If we don't we're
 511                  * likely too old to handle it.
 512                  */
 513                 hdr = map;
 514                 if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
 515                         die("packfile %s isn't actually a pack.", p->pack_name);
 516                 if (!pack_version_ok(hdr->hdr_version))
 517                         die("packfile %s is version %i and not supported"
 518                                 " (try upgrading GIT to a newer version)",
 519                                 p->pack_name, ntohl(hdr->hdr_version));
 520
 521                 /* Check if the pack file matches with the index file.
 522                  * this is cheap.
 523                  */
 524                 if (hashcmp((unsigned char *)(p->index_base) +
 525                             p->index_size - 40,
 526                             (unsigned char *)p->pack_base +
 527                             p->pack_size - 20)) {
 528                         die("packfile %s does not match index.", p->pack_name);
 529                 }
 530         }
 531         p->pack_last_used = pack_used_ctr++;
 532         p->pack_use_cnt++;
 533         return 0;
 534 }
 535
 536 struct packed_git *add_packed_git(char *path, int path_len, int local)
 537 {
 538         struct stat st;
 539         struct packed_git *p;
 540         unsigned long idx_size;
 541         void *idx_map;
 542         unsigned char sha1[20];
 543
 544         if (check_packed_git_idx(path, &idx_size, &idx_map))
 545                 return NULL;
 546
 547         /* do we have a corresponding .pack file? */
 548         strcpy(path + path_len - 4, ".pack");
 549         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 550                 munmap(idx_map, idx_size);
 551                 return NULL;
 552         }
 553         /* ok, it looks sane as far as we can check without
 554          * actually mapping the pack file.
 555          */
 556         p = xmalloc(sizeof(*p) + path_len + 2);
 557         strcpy(p->pack_name, path);
 558         p->index_size = idx_size;
 559         p->pack_size = st.st_size;
 560         p->index_base = idx_map;
 561         p->next = NULL;
 562         p->pack_base = NULL;
 563         p->pack_last_used = 0;
 564         p->pack_use_cnt = 0;
 565         p->pack_local = local;
 566         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 567                 hashcpy(p->sha1, sha1);
 568         return p;
 569 }
 570
 571 struct packed_git *parse_pack_index(unsigned char *sha1)
 572 {
 573         char *path = sha1_pack_index_name(sha1);
 574         return parse_pack_index_file(sha1, path);
 575 }
 576
 577 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 578 {
 579         struct packed_git *p;
 580         unsigned long idx_size;
 581         void *idx_map;
 582         char *path;
 583
 584         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 585                 return NULL;
 586
 587         path = sha1_pack_name(sha1);
 588
 589         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 590         strcpy(p->pack_name, path);
 591         p->index_size = idx_size;
 592         p->pack_size = 0;
 593         p->index_base = idx_map;
 594         p->next = NULL;
 595         p->pack_base = NULL;
 596         p->pack_last_used = 0;
 597         p->pack_use_cnt = 0;
 598         hashcpy(p->sha1, sha1);
 599         return p;
 600 }
 601
 602 void install_packed_git(struct packed_git *pack)
 603 {
 604         pack->next = packed_git;
 605         packed_git = pack;
 606 }
 607
 608 static void prepare_packed_git_one(char *objdir, int local)
 609 {
 610         char path[PATH_MAX];
 611         int len;
 612         DIR *dir;
 613         struct dirent *de;
 614
 615         sprintf(path, "%s/pack", objdir);
 616         len = strlen(path);
 617         dir = opendir(path);
 618         if (!dir) {
 619                 if (errno != ENOENT)
 620                         error("unable to open object pack directory: %s: %s",
 621                               path, strerror(errno));
 622                 return;
 623         }
 624         path[len++] = '/';
 625         while ((de = readdir(dir)) != NULL) {
 626                 int namelen = strlen(de->d_name);
 627                 struct packed_git *p;
 628
 629                 if (!has_extension(de->d_name, ".idx"))
 630                         continue;
 631
 632                 /* we have .idx.  Is it a file we can map? */
 633                 strcpy(path + len, de->d_name);
 634                 for (p = packed_git; p; p = p->next) {
 635                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 636                                 break;
 637                 }
 638                 if (p)
 639                         continue;
 640                 p = add_packed_git(path, len + namelen, local);
 641                 if (!p)
 642                         continue;
 643                 p->next = packed_git;
 644                 packed_git = p;
 645         }
 646         closedir(dir);
 647 }
 648
 649 static int prepare_packed_git_run_once = 0;
 650 void prepare_packed_git(void)
 651 {
 652         struct alternate_object_database *alt;
 653
 654         if (prepare_packed_git_run_once)
 655                 return;
 656         prepare_packed_git_one(get_object_directory(), 1);
 657         prepare_alt_odb();
 658         for (alt = alt_odb_list; alt; alt = alt->next) {
 659                 alt->name[-1] = 0;
 660                 prepare_packed_git_one(alt->base, 0);
 661                 alt->name[-1] = '/';
 662         }
 663         prepare_packed_git_run_once = 1;
 664 }
 665
 666 static void reprepare_packed_git(void)
 667 {
 668         prepare_packed_git_run_once = 0;
 669         prepare_packed_git();
 670 }
 671
 672 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 673 {
 674         char header[100];
 675         unsigned char real_sha1[20];
 676         SHA_CTX c;
 677
 678         SHA1_Init(&c);
 679         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 680         SHA1_Update(&c, map, size);
 681         SHA1_Final(real_sha1, &c);
 682         return hashcmp(sha1, real_sha1) ? -1 : 0;
 683 }
 684
 685 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 686 {
 687         struct stat st;
 688         void *map;
 689         int fd;
 690         char *filename = find_sha1_file(sha1, &st);
 691
 692         if (!filename) {
 693                 return NULL;
 694         }
 695
 696         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 697         if (fd < 0) {
 698                 /* See if it works without O_NOATIME */
 699                 switch (sha1_file_open_flag) {
 700                 default:
 701                         fd = open(filename, O_RDONLY);
 702                         if (fd >= 0)
 703                                 break;
 704                 /* Fallthrough */
 705                 case 0:
 706                         return NULL;
 707                 }
 708
 709                 /* If it failed once, it will probably fail again.
 710                  * Stop using O_NOATIME
 711                  */
 712                 sha1_file_open_flag = 0;
 713         }
 714         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 715         close(fd);
 716         if (map == MAP_FAILED)
 717                 return NULL;
 718         *size = st.st_size;
 719         return map;
 720 }
 721
 722 int legacy_loose_object(unsigned char *map)
 723 {
 724         unsigned int word;
 725
 726         /*
 727          * Is it a zlib-compressed buffer? If so, the first byte
 728          * must be 0x78 (15-bit window size, deflated), and the
 729          * first 16-bit word is evenly divisible by 31
 730          */
 731         word = (map[0] << 8) + map[1];
 732         if (map[0] == 0x78 && !(word % 31))
 733                 return 1;
 734         else
 735                 return 0;
 736 }
 737
 738 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 739 {
 740         unsigned shift;
 741         unsigned char c;
 742         unsigned long size;
 743         unsigned long used = 0;
 744
 745         c = buf[used++];
 746         *type = (c >> 4) & 7;
 747         size = c & 15;
 748         shift = 4;
 749         while (c & 0x80) {
 750                 if (len <= used)
 751                         return 0;
 752                 if (sizeof(long) * 8 <= shift)
 753                         return 0;
 754                 c = buf[used++];
 755                 size += (c & 0x7f) << shift;
 756                 shift += 7;
 757         }
 758         *sizep = size;
 759         return used;
 760 }
 761
 762 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 763 {
 764         unsigned long size, used;
 765         static const char valid_loose_object_type[8] = {
 766                 0, /* OBJ_EXT */
 767                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 768                 0, /* "delta" and others are invalid in a loose object */
 769         };
 770         enum object_type type;
 771
 772         /* Get the data stream */
 773         memset(stream, 0, sizeof(*stream));
 774         stream->next_in = map;
 775         stream->avail_in = mapsize;
 776         stream->next_out = buffer;
 777         stream->avail_out = bufsiz;
 778
 779         if (legacy_loose_object(map)) {
 780                 inflateInit(stream);
 781                 return inflate(stream, 0);
 782         }
 783
 784         used = unpack_object_header_gently(map, mapsize, &type, &size);
 785         if (!used || !valid_loose_object_type[type])
 786                 return -1;
 787         map += used;
 788         mapsize -= used;
 789
 790         /* Set up the stream for the rest.. */
 791         stream->next_in = map;
 792         stream->avail_in = mapsize;
 793         inflateInit(stream);
 794
 795         /* And generate the fake traditional header */
 796         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 797                                          type_names[type], size);
 798         return 0;
 799 }
 800
 801 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 802 {
 803         int bytes = strlen(buffer) + 1;
 804         unsigned char *buf = xmalloc(1+size);
 805         unsigned long n;
 806
 807         n = stream->total_out - bytes;
 808         if (n > size)
 809                 n = size;
 810         memcpy(buf, (char *) buffer + bytes, n);
 811         bytes = n;
 812         if (bytes < size) {
 813                 stream->next_out = buf + bytes;
 814                 stream->avail_out = size - bytes;
 815                 while (inflate(stream, Z_FINISH) == Z_OK)
 816                         /* nothing */;
 817         }
 818         buf[size] = 0;
 819         inflateEnd(stream);
 820         return buf;
 821 }
 822
 823 /*
 824  * We used to just use "sscanf()", but that's actually way
 825  * too permissive for what we want to check. So do an anal
 826  * object header parse by hand.
 827  */
 828 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 829 {
 830         int i;
 831         unsigned long size;
 832
 833         /*
 834          * The type can be at most ten bytes (including the
 835          * terminating '\0' that we add), and is followed by
 836          * a space.
 837          */
 838         i = 10;
 839         for (;;) {
 840                 char c = *hdr++;
 841                 if (c == ' ')
 842                         break;
 843                 if (!--i)
 844                         return -1;
 845                 *type++ = c;
 846         }
 847         *type = 0;
 848
 849         /*
 850          * The length must follow immediately, and be in canonical
 851          * decimal format (ie "010" is not valid).
 852          */
 853         size = *hdr++ - '0';
 854         if (size > 9)
 855                 return -1;
 856         if (size) {
 857                 for (;;) {
 858                         unsigned long c = *hdr - '0';
 859                         if (c > 9)
 860                                 break;
 861                         hdr++;
 862                         size = size * 10 + c;
 863                 }
 864         }
 865         *sizep = size;
 866
 867         /*
 868          * The length must be followed by a zero byte
 869          */
 870         return *hdr ? -1 : 0;
 871 }
 872
 873 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 874 {
 875         int ret;
 876         z_stream stream;
 877         char hdr[8192];
 878
 879         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 880         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 881                 return NULL;
 882
 883         return unpack_sha1_rest(&stream, hdr, *size);
 884 }
 885
 886 /* forward declaration for a mutually recursive function */
 887 static int packed_object_info(struct packed_git *p, unsigned long offset,
 888                               char *type, unsigned long *sizep);
 889
 890 static int packed_delta_info(struct packed_git *p,
 891                              unsigned long offset,
 892                              char *type,
 893                              unsigned long *sizep)
 894 {
 895         unsigned long base_offset;
 896         unsigned char *base_sha1 = (unsigned char *) p->pack_base + offset;
 897
 898         if (p->pack_size < offset + 20)
 899                 die("truncated pack file");
 900         /* The base entry _must_ be in the same pack */
 901         base_offset = find_pack_entry_one(base_sha1, p);
 902         if (!base_offset)
 903                 die("failed to find delta-pack base object %s",
 904                     sha1_to_hex(base_sha1));
 905         offset += 20;
 906
 907         /* We choose to only get the type of the base object and
 908          * ignore potentially corrupt pack file that expects the delta
 909          * based on a base with a wrong size.  This saves tons of
 910          * inflate() calls.
 911          */
 912         if (packed_object_info(p, base_offset, type, NULL))
 913                 die("cannot get info for delta-pack base");
 914
 915         if (sizep) {
 916                 const unsigned char *data;
 917                 unsigned char delta_head[64];
 918                 unsigned long result_size;
 919                 z_stream stream;
 920                 int st;
 921
 922                 memset(&stream, 0, sizeof(stream));
 923
 924                 stream.next_in = (unsigned char *) p->pack_base + offset;
 925                 stream.avail_in = p->pack_size - offset;
 926                 stream.next_out = delta_head;
 927                 stream.avail_out = sizeof(delta_head);
 928
 929                 inflateInit(&stream);
 930                 st = inflate(&stream, Z_FINISH);
 931                 inflateEnd(&stream);
 932                 if ((st != Z_STREAM_END) &&
 933                     stream.total_out != sizeof(delta_head))
 934                         die("delta data unpack-initial failed");
 935
 936                 /* Examine the initial part of the delta to figure out
 937                  * the result size.
 938                  */
 939                 data = delta_head;
 940
 941                 /* ignore base size */
 942                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 943
 944                 /* Read the result size */
 945                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 946                 *sizep = result_size;
 947         }
 948         return 0;
 949 }
 950
 951 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 952         enum object_type *type, unsigned long *sizep)
 953 {
 954         unsigned long used;
 955
 956         if (p->pack_size <= offset)
 957                 die("object offset outside of pack file");
 958
 959         used = unpack_object_header_gently((unsigned char *)p->pack_base +
 960                                            offset,
 961                                            p->pack_size - offset, type, sizep);
 962         if (!used)
 963                 die("object offset outside of pack file");
 964
 965         return offset + used;
 966 }
 967
 968 int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
 969                            unsigned char *base, unsigned long *sizep,
 970                            enum object_type *kindp)
 971 {
 972         unsigned long ptr;
 973         int status = -1;
 974
 975         use_packed_git(p);
 976         ptr = offset;
 977         ptr = unpack_object_header(p, ptr, kindp, sizep);
 978         if (*kindp != OBJ_DELTA)
 979                 goto done;
 980         hashcpy(base, (unsigned char *) p->pack_base + ptr);
 981         status = 0;
 982  done:
 983         unuse_packed_git(p);
 984         return status;
 985 }
 986
 987 void packed_object_info_detail(struct packed_git *p,
 988                                unsigned long offset,
 989                                char *type,
 990                                unsigned long *size,
 991                                unsigned long *store_size,
 992                                unsigned int *delta_chain_length,
 993                                unsigned char *base_sha1)
 994 {
 995         unsigned long val;
 996         unsigned char *next_sha1;
 997         enum object_type kind;
 998
 999         *delta_chain_length = 0;
1000         offset = unpack_object_header(p, offset, &kind, size);
1001
1002         for (;;) {
1003                 switch (kind) {
1004                 default:
1005                         die("corrupted pack file %s containing object of kind %d",
1006                             p->pack_name, kind);
1007                 case OBJ_COMMIT:
1008                 case OBJ_TREE:
1009                 case OBJ_BLOB:
1010                 case OBJ_TAG:
1011                         strcpy(type, type_names[kind]);
1012                         *store_size = 0; /* notyet */
1013                         return;
1014                 case OBJ_DELTA:
1015                         if (p->pack_size <= offset + 20)
1016                                 die("pack file %s records an incomplete delta base",
1017                                     p->pack_name);
1018                         next_sha1 = (unsigned char *) p->pack_base + offset;
1019                         if (*delta_chain_length == 0)
1020                                 hashcpy(base_sha1, next_sha1);
1021                         offset = find_pack_entry_one(next_sha1, p);
1022                         break;
1023                 }
1024                 offset = unpack_object_header(p, offset, &kind, &val);
1025                 (*delta_chain_length)++;
1026         }
1027 }
1028
1029 static int packed_object_info(struct packed_git *p, unsigned long offset,
1030                               char *type, unsigned long *sizep)
1031 {
1032         unsigned long size;
1033         enum object_type kind;
1034
1035         offset = unpack_object_header(p, offset, &kind, &size);
1036
1037         if (kind == OBJ_DELTA)
1038                 return packed_delta_info(p, offset, type, sizep);
1039
1040         switch (kind) {
1041         case OBJ_COMMIT:
1042         case OBJ_TREE:
1043         case OBJ_BLOB:
1044         case OBJ_TAG:
1045                 strcpy(type, type_names[kind]);
1046                 break;
1047         default:
1048                 die("corrupted pack file %s containing object of kind %d",
1049                     p->pack_name, kind);
1050         }
1051         if (sizep)
1052                 *sizep = size;
1053         return 0;
1054 }
1055
1056 static void *unpack_compressed_entry(struct packed_git *p,
1057                                     unsigned long offset,
1058                                     unsigned long size)
1059 {
1060         int st;
1061         z_stream stream;
1062         unsigned char *buffer;
1063
1064         buffer = xmalloc(size + 1);
1065         buffer[size] = 0;
1066         memset(&stream, 0, sizeof(stream));
1067         stream.next_in = (unsigned char*)p->pack_base + offset;
1068         stream.avail_in = p->pack_size - offset;
1069         stream.next_out = buffer;
1070         stream.avail_out = size;
1071
1072         inflateInit(&stream);
1073         st = inflate(&stream, Z_FINISH);
1074         inflateEnd(&stream);
1075         if ((st != Z_STREAM_END) || stream.total_out != size) {
1076                 free(buffer);
1077                 return NULL;
1078         }
1079
1080         return buffer;
1081 }
1082
1083 static void *unpack_delta_entry(struct packed_git *p,
1084                                 unsigned long offset,
1085                                 unsigned long delta_size,
1086                                 char *type,
1087                                 unsigned long *sizep)
1088 {
1089         void *delta_data, *result, *base;
1090         unsigned long result_size, base_size, base_offset;
1091         unsigned char *base_sha1;
1092
1093         if (p->pack_size < offset + 20)
1094                 die("truncated pack file");
1095         /* The base entry _must_ be in the same pack */
1096         base_sha1 = (unsigned char*)p->pack_base + offset;
1097         base_offset = find_pack_entry_one(base_sha1, p);
1098         if (!base_offset)
1099                 die("failed to find delta-pack base object %s",
1100                     sha1_to_hex(base_sha1));
1101         offset += 20;
1102
1103         base = unpack_entry_gently(p, base_offset, type, &base_size);
1104         if (!base)
1105                 die("failed to read delta base object at %lu from %s",
1106                     base_offset, p->pack_name);
1107
1108         delta_data = unpack_compressed_entry(p, offset, delta_size);
1109         result = patch_delta(base, base_size,
1110                              delta_data, delta_size,
1111                              &result_size);
1112         if (!result)
1113                 die("failed to apply delta");
1114         free(delta_data);
1115         free(base);
1116         *sizep = result_size;
1117         return result;
1118 }
1119
1120 static void *unpack_entry(struct pack_entry *entry,
1121                           char *type, unsigned long *sizep)
1122 {
1123         struct packed_git *p = entry->p;
1124         void *retval;
1125
1126         if (use_packed_git(p))
1127                 die("cannot map packed file");
1128         retval = unpack_entry_gently(p, entry->offset, type, sizep);
1129         unuse_packed_git(p);
1130         if (!retval)
1131                 die("corrupted pack file %s", p->pack_name);
1132         return retval;
1133 }
1134
1135 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
1136 void *unpack_entry_gently(struct packed_git *p, unsigned long offset,
1137                           char *type, unsigned long *sizep)
1138 {
1139         unsigned long size;
1140         enum object_type kind;
1141
1142         offset = unpack_object_header(p, offset, &kind, &size);
1143         switch (kind) {
1144         case OBJ_DELTA:
1145                 return unpack_delta_entry(p, offset, size, type, sizep);
1146         case OBJ_COMMIT:
1147         case OBJ_TREE:
1148         case OBJ_BLOB:
1149         case OBJ_TAG:
1150                 strcpy(type, type_names[kind]);
1151                 *sizep = size;
1152                 return unpack_compressed_entry(p, offset, size);
1153         default:
1154                 return NULL;
1155         }
1156 }
1157
1158 int num_packed_objects(const struct packed_git *p)
1159 {
1160         /* See check_packed_git_idx() */
1161         return (p->index_size - 20 - 20 - 4*256) / 24;
1162 }
1163
1164 int nth_packed_object_sha1(const struct packed_git *p, int n,
1165                            unsigned char* sha1)
1166 {
1167         void *index = p->index_base + 256;
1168         if (n < 0 || num_packed_objects(p) <= n)
1169                 return -1;
1170         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1171         return 0;
1172 }
1173
1174 unsigned long find_pack_entry_one(const unsigned char *sha1,
1175                                   struct packed_git *p)
1176 {
1177         unsigned int *level1_ofs = p->index_base;
1178         int hi = ntohl(level1_ofs[*sha1]);
1179         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1180         void *index = p->index_base + 256;
1181
1182         do {
1183                 int mi = (lo + hi) / 2;
1184                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1185                 if (!cmp)
1186                         return ntohl(*((unsigned int *) ((char *) index + (24 * mi))));
1187                 if (cmp > 0)
1188                         hi = mi;
1189                 else
1190                         lo = mi+1;
1191         } while (lo < hi);
1192         return 0;
1193 }
1194
1195 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1196 {
1197         struct packed_git *p;
1198         unsigned long offset;
1199
1200         prepare_packed_git();
1201
1202         for (p = packed_git; p; p = p->next) {
1203                 if (ignore_packed) {
1204                         const char **ig;
1205                         for (ig = ignore_packed; *ig; ig++)
1206                                 if (!strcmp(p->pack_name, *ig))
1207                                         break;
1208                         if (*ig)
1209                                 continue;
1210                 }
1211                 offset = find_pack_entry_one(sha1, p);
1212                 if (offset) {
1213                         e->offset = offset;
1214                         e->p = p;
1215                         hashcpy(e->sha1, sha1);
1216                         return 1;
1217                 }
1218         }
1219         return 0;
1220 }
1221
1222 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1223                                   struct packed_git *packs)
1224 {
1225         struct packed_git *p;
1226
1227         for (p = packs; p; p = p->next) {
1228                 if (find_pack_entry_one(sha1, p))
1229                         return p;
1230         }
1231         return NULL;
1232
1233 }
1234
1235 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1236 {
1237         int status;
1238         unsigned long mapsize, size;
1239         void *map;
1240         z_stream stream;
1241         char hdr[128];
1242
1243         map = map_sha1_file(sha1, &mapsize);
1244         if (!map) {
1245                 struct pack_entry e;
1246
1247                 if (!find_pack_entry(sha1, &e, NULL)) {
1248                         reprepare_packed_git();
1249                         if (!find_pack_entry(sha1, &e, NULL))
1250                                 return error("unable to find %s", sha1_to_hex(sha1));
1251                 }
1252                 if (use_packed_git(e.p))
1253                         die("cannot map packed file");
1254                 status = packed_object_info(e.p, e.offset, type, sizep);
1255                 unuse_packed_git(e.p);
1256                 return status;
1257         }
1258         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1259                 status = error("unable to unpack %s header",
1260                                sha1_to_hex(sha1));
1261         if (parse_sha1_header(hdr, type, &size) < 0)
1262                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1263         else {
1264                 status = 0;
1265                 if (sizep)
1266                         *sizep = size;
1267         }
1268         inflateEnd(&stream);
1269         munmap(map, mapsize);
1270         return status;
1271 }
1272
1273 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1274 {
1275         struct pack_entry e;
1276
1277         if (!find_pack_entry(sha1, &e, NULL)) {
1278                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1279                 return NULL;
1280         }
1281         return unpack_entry(&e, type, size);
1282 }
1283
1284 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1285 {
1286         unsigned long mapsize;
1287         void *map, *buf;
1288         struct pack_entry e;
1289
1290         if (find_pack_entry(sha1, &e, NULL))
1291                 return read_packed_sha1(sha1, type, size);
1292         map = map_sha1_file(sha1, &mapsize);
1293         if (map) {
1294                 buf = unpack_sha1_file(map, mapsize, type, size);
1295                 munmap(map, mapsize);
1296                 return buf;
1297         }
1298         reprepare_packed_git();
1299         if (find_pack_entry(sha1, &e, NULL))
1300                 return read_packed_sha1(sha1, type, size);
1301         return NULL;
1302 }
1303
1304 void *read_object_with_reference(const unsigned char *sha1,
1305                                  const char *required_type,
1306                                  unsigned long *size,
1307                                  unsigned char *actual_sha1_return)
1308 {
1309         char type[20];
1310         void *buffer;
1311         unsigned long isize;
1312         unsigned char actual_sha1[20];
1313
1314         hashcpy(actual_sha1, sha1);
1315         while (1) {
1316                 int ref_length = -1;
1317                 const char *ref_type = NULL;
1318
1319                 buffer = read_sha1_file(actual_sha1, type, &isize);
1320                 if (!buffer)
1321                         return NULL;
1322                 if (!strcmp(type, required_type)) {
1323                         *size = isize;
1324                         if (actual_sha1_return)
1325                                 hashcpy(actual_sha1_return, actual_sha1);
1326                         return buffer;
1327                 }
1328                 /* Handle references */
1329                 else if (!strcmp(type, commit_type))
1330                         ref_type = "tree ";
1331                 else if (!strcmp(type, tag_type))
1332                         ref_type = "object ";
1333                 else {
1334                         free(buffer);
1335                         return NULL;
1336                 }
1337                 ref_length = strlen(ref_type);
1338
1339                 if (memcmp(buffer, ref_type, ref_length) ||
1340                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1341                         free(buffer);
1342                         return NULL;
1343                 }
1344                 free(buffer);
1345                 /* Now we have the ID of the referred-to object in
1346                  * actual_sha1.  Check again. */
1347         }
1348 }
1349
1350 char *write_sha1_file_prepare(void *buf,
1351                               unsigned long len,
1352                               const char *type,
1353                               unsigned char *sha1,
1354                               unsigned char *hdr,
1355                               int *hdrlen)
1356 {
1357         SHA_CTX c;
1358
1359         /* Generate the header */
1360         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1361
1362         /* Sha1.. */
1363         SHA1_Init(&c);
1364         SHA1_Update(&c, hdr, *hdrlen);
1365         SHA1_Update(&c, buf, len);
1366         SHA1_Final(sha1, &c);
1367
1368         return sha1_file_name(sha1);
1369 }
1370
1371 /*
1372  * Link the tempfile to the final place, possibly creating the
1373  * last directory level as you do so.
1374  *
1375  * Returns the errno on failure, 0 on success.
1376  */
1377 static int link_temp_to_file(const char *tmpfile, const char *filename)
1378 {
1379         int ret;
1380         char *dir;
1381
1382         if (!link(tmpfile, filename))
1383                 return 0;
1384
1385         /*
1386          * Try to mkdir the last path component if that failed.
1387          *
1388          * Re-try the "link()" regardless of whether the mkdir
1389          * succeeds, since a race might mean that somebody
1390          * else succeeded.
1391          */
1392         ret = errno;
1393         dir = strrchr(filename, '/');
1394         if (dir) {
1395                 *dir = 0;
1396                 mkdir(filename, 0777);
1397                 if (adjust_shared_perm(filename))
1398                         return -2;
1399                 *dir = '/';
1400                 if (!link(tmpfile, filename))
1401                         return 0;
1402                 ret = errno;
1403         }
1404         return ret;
1405 }
1406
1407 /*
1408  * Move the just written object into its final resting place
1409  */
1410 int move_temp_to_file(const char *tmpfile, const char *filename)
1411 {
1412         int ret = link_temp_to_file(tmpfile, filename);
1413
1414         /*
1415          * Coda hack - coda doesn't like cross-directory links,
1416          * so we fall back to a rename, which will mean that it
1417          * won't be able to check collisions, but that's not a
1418          * big deal.
1419          *
1420          * The same holds for FAT formatted media.
1421          *
1422          * When this succeeds, we just return 0. We have nothing
1423          * left to unlink.
1424          */
1425         if (ret && ret != EEXIST) {
1426                 if (!rename(tmpfile, filename))
1427                         return 0;
1428                 ret = errno;
1429         }
1430         unlink(tmpfile);
1431         if (ret) {
1432                 if (ret != EEXIST) {
1433                         fprintf(stderr, "unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1434                         return -1;
1435                 }
1436                 /* FIXME!!! Collision check here ? */
1437         }
1438
1439         return 0;
1440 }
1441
1442 static int write_buffer(int fd, const void *buf, size_t len)
1443 {
1444         while (len) {
1445                 ssize_t size;
1446
1447                 size = write(fd, buf, len);
1448                 if (!size)
1449                         return error("file write: disk full");
1450                 if (size < 0) {
1451                         if (errno == EINTR || errno == EAGAIN)
1452                                 continue;
1453                         return error("file write error (%s)", strerror(errno));
1454                 }
1455                 len -= size;
1456                 buf = (char *) buf + size;
1457         }
1458         return 0;
1459 }
1460
1461 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1462 {
1463         int hdr_len;
1464         unsigned char c;
1465
1466         c = (type << 4) | (len & 15);
1467         len >>= 4;
1468         hdr_len = 1;
1469         while (len) {
1470                 *hdr++ = c | 0x80;
1471                 hdr_len++;
1472                 c = (len & 0x7f);
1473                 len >>= 7;
1474         }
1475         *hdr = c;
1476         return hdr_len;
1477 }
1478
1479 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1480 {
1481         int obj_type, hdr;
1482
1483         if (use_legacy_headers) {
1484                 while (deflate(stream, 0) == Z_OK)
1485                         /* nothing */;
1486                 return;
1487         }
1488         if (!strcmp(type, blob_type))
1489                 obj_type = OBJ_BLOB;
1490         else if (!strcmp(type, tree_type))
1491                 obj_type = OBJ_TREE;
1492         else if (!strcmp(type, commit_type))
1493                 obj_type = OBJ_COMMIT;
1494         else if (!strcmp(type, tag_type))
1495                 obj_type = OBJ_TAG;
1496         else
1497                 die("trying to generate bogus object of type '%s'", type);
1498         hdr = write_binary_header(stream->next_out, obj_type, len);
1499         stream->total_out = hdr;
1500         stream->next_out += hdr;
1501         stream->avail_out -= hdr;
1502 }
1503
1504 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1505 {
1506         int size;
1507         unsigned char *compressed;
1508         z_stream stream;
1509         unsigned char sha1[20];
1510         char *filename;
1511         static char tmpfile[PATH_MAX];
1512         unsigned char hdr[50];
1513         int fd, hdrlen;
1514
1515         /* Normally if we have it in the pack then we do not bother writing
1516          * it out into .git/objects/??/?{38} file.
1517          */
1518         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1519         if (returnsha1)
1520                 hashcpy(returnsha1, sha1);
1521         if (has_sha1_file(sha1))
1522                 return 0;
1523         fd = open(filename, O_RDONLY);
1524         if (fd >= 0) {
1525                 /*
1526                  * FIXME!!! We might do collision checking here, but we'd
1527                  * need to uncompress the old file and check it. Later.
1528                  */
1529                 close(fd);
1530                 return 0;
1531         }
1532
1533         if (errno != ENOENT) {
1534                 fprintf(stderr, "sha1 file %s: %s\n", filename, strerror(errno));
1535                 return -1;
1536         }
1537
1538         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1539
1540         fd = mkstemp(tmpfile);
1541         if (fd < 0) {
1542                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1543                 return -1;
1544         }
1545
1546         /* Set it up */
1547         memset(&stream, 0, sizeof(stream));
1548         deflateInit(&stream, zlib_compression_level);
1549         size = 8 + deflateBound(&stream, len+hdrlen);
1550         compressed = xmalloc(size);
1551
1552         /* Compress it */
1553         stream.next_out = compressed;
1554         stream.avail_out = size;
1555
1556         /* First header.. */
1557         stream.next_in = hdr;
1558         stream.avail_in = hdrlen;
1559         setup_object_header(&stream, type, len);
1560
1561         /* Then the data itself.. */
1562         stream.next_in = buf;
1563         stream.avail_in = len;
1564         while (deflate(&stream, Z_FINISH) == Z_OK)
1565                 /* nothing */;
1566         deflateEnd(&stream);
1567         size = stream.total_out;
1568
1569         if (write_buffer(fd, compressed, size) < 0)
1570                 die("unable to write sha1 file");
1571         fchmod(fd, 0444);
1572         close(fd);
1573         free(compressed);
1574
1575         return move_temp_to_file(tmpfile, filename);
1576 }
1577
1578 /*
1579  * We need to unpack and recompress the object for writing
1580  * it out to a different file.
1581  */
1582 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1583 {
1584         size_t size;
1585         z_stream stream;
1586         unsigned char *unpacked;
1587         unsigned long len;
1588         char type[20];
1589         char hdr[50];
1590         int hdrlen;
1591         void *buf;
1592
1593         /* need to unpack and recompress it by itself */
1594         unpacked = read_packed_sha1(sha1, type, &len);
1595
1596         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1597
1598         /* Set it up */
1599         memset(&stream, 0, sizeof(stream));
1600         deflateInit(&stream, zlib_compression_level);
1601         size = deflateBound(&stream, len + hdrlen);
1602         buf = xmalloc(size);
1603
1604         /* Compress it */
1605         stream.next_out = buf;
1606         stream.avail_out = size;
1607
1608         /* First header.. */
1609         stream.next_in = (void *)hdr;
1610         stream.avail_in = hdrlen;
1611         while (deflate(&stream, 0) == Z_OK)
1612                 /* nothing */;
1613
1614         /* Then the data itself.. */
1615         stream.next_in = unpacked;
1616         stream.avail_in = len;
1617         while (deflate(&stream, Z_FINISH) == Z_OK)
1618                 /* nothing */;
1619         deflateEnd(&stream);
1620         free(unpacked);
1621
1622         *objsize = stream.total_out;
1623         return buf;
1624 }
1625
1626 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1627 {
1628         int retval;
1629         unsigned long objsize;
1630         void *buf = map_sha1_file(sha1, &objsize);
1631
1632         if (buf) {
1633                 retval = write_buffer(fd, buf, objsize);
1634                 munmap(buf, objsize);
1635                 return retval;
1636         }
1637
1638         buf = repack_object(sha1, &objsize);
1639         retval = write_buffer(fd, buf, objsize);
1640         free(buf);
1641         return retval;
1642 }
1643
1644 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1645                        size_t bufsize, size_t *bufposn)
1646 {
1647         char tmpfile[PATH_MAX];
1648         int local;
1649         z_stream stream;
1650         unsigned char real_sha1[20];
1651         unsigned char discard[4096];
1652         int ret;
1653         SHA_CTX c;
1654
1655         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1656
1657         local = mkstemp(tmpfile);
1658         if (local < 0)
1659                 return error("Couldn't open %s for %s",
1660                              tmpfile, sha1_to_hex(sha1));
1661
1662         memset(&stream, 0, sizeof(stream));
1663
1664         inflateInit(&stream);
1665
1666         SHA1_Init(&c);
1667
1668         do {
1669                 ssize_t size;
1670                 if (*bufposn) {
1671                         stream.avail_in = *bufposn;
1672                         stream.next_in = (unsigned char *) buffer;
1673                         do {
1674                                 stream.next_out = discard;
1675                                 stream.avail_out = sizeof(discard);
1676                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1677                                 SHA1_Update(&c, discard, sizeof(discard) -
1678                                             stream.avail_out);
1679                         } while (stream.avail_in && ret == Z_OK);
1680                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1681                                 die("unable to write sha1 file");
1682                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1683                                 stream.avail_in);
1684                         *bufposn = stream.avail_in;
1685                         if (ret != Z_OK)
1686                                 break;
1687                 }
1688                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1689                 if (size <= 0) {
1690                         close(local);
1691                         unlink(tmpfile);
1692                         if (!size)
1693                                 return error("Connection closed?");
1694                         perror("Reading from connection");
1695                         return -1;
1696                 }
1697                 *bufposn += size;
1698         } while (1);
1699         inflateEnd(&stream);
1700
1701         close(local);
1702         SHA1_Final(real_sha1, &c);
1703         if (ret != Z_STREAM_END) {
1704                 unlink(tmpfile);
1705                 return error("File %s corrupted", sha1_to_hex(sha1));
1706         }
1707         if (hashcmp(sha1, real_sha1)) {
1708                 unlink(tmpfile);
1709                 return error("File %s has bad hash", sha1_to_hex(sha1));
1710         }
1711
1712         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1713 }
1714
1715 int has_pack_index(const unsigned char *sha1)
1716 {
1717         struct stat st;
1718         if (stat(sha1_pack_index_name(sha1), &st))
1719                 return 0;
1720         return 1;
1721 }
1722
1723 int has_pack_file(const unsigned char *sha1)
1724 {
1725         struct stat st;
1726         if (stat(sha1_pack_name(sha1), &st))
1727                 return 0;
1728         return 1;
1729 }
1730
1731 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
1732 {
1733         struct pack_entry e;
1734         return find_pack_entry(sha1, &e, ignore_packed);
1735 }
1736
1737 int has_sha1_file(const unsigned char *sha1)
1738 {
1739         struct stat st;
1740         struct pack_entry e;
1741
1742         if (find_pack_entry(sha1, &e, NULL))
1743                 return 1;
1744         return find_sha1_file(sha1, &st) ? 1 : 0;
1745 }
1746
1747 /*
1748  * reads from fd as long as possible into a supplied buffer of size bytes.
1749  * If necessary the buffer's size is increased using realloc()
1750  *
1751  * returns 0 if anything went fine and -1 otherwise
1752  *
1753  * NOTE: both buf and size may change, but even when -1 is returned
1754  * you still have to free() it yourself.
1755  */
1756 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1757 {
1758         char* buf = *return_buf;
1759         unsigned long size = *return_size;
1760         int iret;
1761         unsigned long off = 0;
1762
1763         do {
1764                 iret = xread(fd, buf + off, size - off);
1765                 if (iret > 0) {
1766                         off += iret;
1767                         if (off == size) {
1768                                 size *= 2;
1769                                 buf = xrealloc(buf, size);
1770                         }
1771                 }
1772         } while (iret > 0);
1773
1774         *return_buf = buf;
1775         *return_size = off;
1776
1777         if (iret < 0)
1778                 return -1;
1779         return 0;
1780 }
1781
1782 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1783 {
1784         unsigned long size = 4096;
1785         char *buf = xmalloc(size);
1786         int ret;
1787         unsigned char hdr[50];
1788         int hdrlen;
1789
1790         if (read_pipe(fd, &buf, &size)) {
1791                 free(buf);
1792                 return -1;
1793         }
1794
1795         if (!type)
1796                 type = blob_type;
1797         if (write_object)
1798                 ret = write_sha1_file(buf, size, type, sha1);
1799         else {
1800                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1801                 ret = 0;
1802         }
1803         free(buf);
1804         return ret;
1805 }
1806
1807 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1808 {
1809         unsigned long size = st->st_size;
1810         void *buf;
1811         int ret;
1812         unsigned char hdr[50];
1813         int hdrlen;
1814
1815         buf = "";
1816         if (size)
1817                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1818         close(fd);
1819         if (buf == MAP_FAILED)
1820                 return -1;
1821
1822         if (!type)
1823                 type = blob_type;
1824         if (write_object)
1825                 ret = write_sha1_file(buf, size, type, sha1);
1826         else {
1827                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1828                 ret = 0;
1829         }
1830         if (size)
1831                 munmap(buf, size);
1832         return ret;
1833 }
1834
1835 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1836 {
1837         int fd;
1838         char *target;
1839
1840         switch (st->st_mode & S_IFMT) {
1841         case S_IFREG:
1842                 fd = open(path, O_RDONLY);
1843                 if (fd < 0)
1844                         return error("open(\"%s\"): %s", path,
1845                                      strerror(errno));
1846                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1847                         return error("%s: failed to insert into database",
1848                                      path);
1849                 break;
1850         case S_IFLNK:
1851                 target = xmalloc(st->st_size+1);
1852                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1853                         char *errstr = strerror(errno);
1854                         free(target);
1855                         return error("readlink(\"%s\"): %s", path,
1856                                      errstr);
1857                 }
1858                 if (!write_object) {
1859                         unsigned char hdr[50];
1860                         int hdrlen;
1861                         write_sha1_file_prepare(target, st->st_size, blob_type,
1862                                                 sha1, hdr, &hdrlen);
1863                 } else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1864                         return error("%s: failed to insert into database",
1865                                      path);
1866                 free(target);
1867                 break;
1868         default:
1869                 return error("%s: unsupported file type", path);
1870         }
1871         return 0;
1872 }