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 static int pack_used_ctr;
 401 static unsigned long pack_mapped;
 402 struct packed_git *packed_git;
 403
 404 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 405                                 void **idx_map_)
 406 {
 407         void *idx_map;
 408         unsigned int *index;
 409         unsigned long idx_size;
 410         int nr, i;
 411         int fd = open(path, O_RDONLY);
 412         struct stat st;
 413         if (fd < 0)
 414                 return -1;
 415         if (fstat(fd, &st)) {
 416                 close(fd);
 417                 return -1;
 418         }
 419         idx_size = st.st_size;
 420         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 421         close(fd);
 422         if (idx_map == MAP_FAILED)
 423                 return -1;
 424
 425         index = idx_map;
 426         *idx_map_ = idx_map;
 427         *idx_size_ = idx_size;
 428
 429         /* check index map */
 430         if (idx_size < 4*256 + 20 + 20)
 431                 return error("index file too small");
 432         nr = 0;
 433         for (i = 0; i < 256; i++) {
 434                 unsigned int n = ntohl(index[i]);
 435                 if (n < nr)
 436                         return error("non-monotonic index");
 437                 nr = n;
 438         }
 439
 440         /*
 441          * Total size:
 442          *  - 256 index entries 4 bytes each
 443          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 444          *  - 20-byte SHA1 of the packfile
 445          *  - 20-byte SHA1 file checksum
 446          */
 447         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 448                 return error("wrong index file size");
 449
 450         return 0;
 451 }
 452
 453 static int unuse_one_packed_git(void)
 454 {
 455         struct packed_git *p, *lru = NULL;
 456
 457         for (p = packed_git; p; p = p->next) {
 458                 if (!p->windows || p->windows->inuse_cnt)
 459                         continue;
 460                 if (!lru || p->windows->last_used < lru->windows->last_used)
 461                         lru = p;
 462         }
 463         if (!lru)
 464                 return 0;
 465         munmap(lru->windows->base, lru->windows->len);
 466         free(lru->windows);
 467         lru->windows = NULL;
 468         return 1;
 469 }
 470
 471 void unuse_packed_git(struct packed_git *p)
 472 {
 473         if (p->windows)
 474                 p->windows->inuse_cnt--;
 475 }
 476
 477 int use_packed_git(struct packed_git *p)
 478 {
 479         if (!p->pack_size) {
 480                 struct stat st;
 481                 /* We created the struct before we had the pack */
 482                 stat(p->pack_name, &st);
 483                 if (!S_ISREG(st.st_mode))
 484                         die("packfile %s not a regular file", p->pack_name);
 485                 p->pack_size = st.st_size;
 486         }
 487         if (!p->windows) {
 488                 int fd;
 489                 struct stat st;
 490                 struct pack_window *win;
 491                 struct pack_header *hdr;
 492
 493                 pack_mapped += p->pack_size;
 494                 while (packed_git_limit < pack_mapped && unuse_one_packed_git())
 495                         ; /* nothing */
 496                 fd = open(p->pack_name, O_RDONLY);
 497                 if (fd < 0)
 498                         die("packfile %s cannot be opened", p->pack_name);
 499                 if (fstat(fd, &st)) {
 500                         close(fd);
 501                         die("packfile %s cannot be opened", p->pack_name);
 502                 }
 503                 if (st.st_size != p->pack_size)
 504                         die("packfile %s size mismatch.", p->pack_name);
 505                 win = xcalloc(1, sizeof(*win));
 506                 win->len = p->pack_size;
 507                 win->base = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 508                 close(fd);
 509                 if (win->base == MAP_FAILED)
 510                         die("packfile %s cannot be mapped.", p->pack_name);
 511                 p->windows = win;
 512
 513                 /* Check if we understand this pack file.  If we don't we're
 514                  * likely too old to handle it.
 515                  */
 516                 hdr = (struct pack_header*)win->base;
 517                 if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
 518                         die("packfile %s isn't actually a pack.", p->pack_name);
 519                 if (!pack_version_ok(hdr->hdr_version))
 520                         die("packfile %s is version %i and not supported"
 521                                 " (try upgrading GIT to a newer version)",
 522                                 p->pack_name, ntohl(hdr->hdr_version));
 523
 524                 /* Check if the pack file matches with the index file.
 525                  * this is cheap.
 526                  */
 527                 if (hashcmp((unsigned char *)(p->index_base) +
 528                             p->index_size - 40,
 529                             p->windows->base +
 530                             p->pack_size - 20)) {
 531                         die("packfile %s does not match index.", p->pack_name);
 532                 }
 533         }
 534         p->windows->last_used = pack_used_ctr++;
 535         p->windows->inuse_cnt++;
 536         return 0;
 537 }
 538
 539 struct packed_git *add_packed_git(char *path, int path_len, int local)
 540 {
 541         struct stat st;
 542         struct packed_git *p;
 543         unsigned long idx_size;
 544         void *idx_map;
 545         unsigned char sha1[20];
 546
 547         if (check_packed_git_idx(path, &idx_size, &idx_map))
 548                 return NULL;
 549
 550         /* do we have a corresponding .pack file? */
 551         strcpy(path + path_len - 4, ".pack");
 552         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 553                 munmap(idx_map, idx_size);
 554                 return NULL;
 555         }
 556         /* ok, it looks sane as far as we can check without
 557          * actually mapping the pack file.
 558          */
 559         p = xmalloc(sizeof(*p) + path_len + 2);
 560         strcpy(p->pack_name, path);
 561         p->index_size = idx_size;
 562         p->pack_size = st.st_size;
 563         p->index_base = idx_map;
 564         p->next = NULL;
 565         p->windows = NULL;
 566         p->pack_local = local;
 567         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 568                 hashcpy(p->sha1, sha1);
 569         return p;
 570 }
 571
 572 struct packed_git *parse_pack_index(unsigned char *sha1)
 573 {
 574         char *path = sha1_pack_index_name(sha1);
 575         return parse_pack_index_file(sha1, path);
 576 }
 577
 578 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 579 {
 580         struct packed_git *p;
 581         unsigned long idx_size;
 582         void *idx_map;
 583         char *path;
 584
 585         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 586                 return NULL;
 587
 588         path = sha1_pack_name(sha1);
 589
 590         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 591         strcpy(p->pack_name, path);
 592         p->index_size = idx_size;
 593         p->pack_size = 0;
 594         p->index_base = idx_map;
 595         p->next = NULL;
 596         p->windows = NULL;
 597         hashcpy(p->sha1, sha1);
 598         return p;
 599 }
 600
 601 void install_packed_git(struct packed_git *pack)
 602 {
 603         pack->next = packed_git;
 604         packed_git = pack;
 605 }
 606
 607 static void prepare_packed_git_one(char *objdir, int local)
 608 {
 609         char path[PATH_MAX];
 610         int len;
 611         DIR *dir;
 612         struct dirent *de;
 613
 614         sprintf(path, "%s/pack", objdir);
 615         len = strlen(path);
 616         dir = opendir(path);
 617         if (!dir) {
 618                 if (errno != ENOENT)
 619                         error("unable to open object pack directory: %s: %s",
 620                               path, strerror(errno));
 621                 return;
 622         }
 623         path[len++] = '/';
 624         while ((de = readdir(dir)) != NULL) {
 625                 int namelen = strlen(de->d_name);
 626                 struct packed_git *p;
 627
 628                 if (!has_extension(de->d_name, ".idx"))
 629                         continue;
 630
 631                 /* we have .idx.  Is it a file we can map? */
 632                 strcpy(path + len, de->d_name);
 633                 for (p = packed_git; p; p = p->next) {
 634                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 635                                 break;
 636                 }
 637                 if (p)
 638                         continue;
 639                 p = add_packed_git(path, len + namelen, local);
 640                 if (!p)
 641                         continue;
 642                 p->next = packed_git;
 643                 packed_git = p;
 644         }
 645         closedir(dir);
 646 }
 647
 648 static int prepare_packed_git_run_once = 0;
 649 void prepare_packed_git(void)
 650 {
 651         struct alternate_object_database *alt;
 652
 653         if (prepare_packed_git_run_once)
 654                 return;
 655         prepare_packed_git_one(get_object_directory(), 1);
 656         prepare_alt_odb();
 657         for (alt = alt_odb_list; alt; alt = alt->next) {
 658                 alt->name[-1] = 0;
 659                 prepare_packed_git_one(alt->base, 0);
 660                 alt->name[-1] = '/';
 661         }
 662         prepare_packed_git_run_once = 1;
 663 }
 664
 665 void reprepare_packed_git(void)
 666 {
 667         prepare_packed_git_run_once = 0;
 668         prepare_packed_git();
 669 }
 670
 671 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 672 {
 673         unsigned char real_sha1[20];
 674         hash_sha1_file(map, size, type, real_sha1);
 675         return hashcmp(sha1, real_sha1) ? -1 : 0;
 676 }
 677
 678 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 679 {
 680         struct stat st;
 681         void *map;
 682         int fd;
 683         char *filename = find_sha1_file(sha1, &st);
 684
 685         if (!filename) {
 686                 return NULL;
 687         }
 688
 689         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 690         if (fd < 0) {
 691                 /* See if it works without O_NOATIME */
 692                 switch (sha1_file_open_flag) {
 693                 default:
 694                         fd = open(filename, O_RDONLY);
 695                         if (fd >= 0)
 696                                 break;
 697                 /* Fallthrough */
 698                 case 0:
 699                         return NULL;
 700                 }
 701
 702                 /* If it failed once, it will probably fail again.
 703                  * Stop using O_NOATIME
 704                  */
 705                 sha1_file_open_flag = 0;
 706         }
 707         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 708         close(fd);
 709         if (map == MAP_FAILED)
 710                 return NULL;
 711         *size = st.st_size;
 712         return map;
 713 }
 714
 715 int legacy_loose_object(unsigned char *map)
 716 {
 717         unsigned int word;
 718
 719         /*
 720          * Is it a zlib-compressed buffer? If so, the first byte
 721          * must be 0x78 (15-bit window size, deflated), and the
 722          * first 16-bit word is evenly divisible by 31
 723          */
 724         word = (map[0] << 8) + map[1];
 725         if (map[0] == 0x78 && !(word % 31))
 726                 return 1;
 727         else
 728                 return 0;
 729 }
 730
 731 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 732 {
 733         unsigned shift;
 734         unsigned char c;
 735         unsigned long size;
 736         unsigned long used = 0;
 737
 738         c = buf[used++];
 739         *type = (c >> 4) & 7;
 740         size = c & 15;
 741         shift = 4;
 742         while (c & 0x80) {
 743                 if (len <= used)
 744                         return 0;
 745                 if (sizeof(long) * 8 <= shift)
 746                         return 0;
 747                 c = buf[used++];
 748                 size += (c & 0x7f) << shift;
 749                 shift += 7;
 750         }
 751         *sizep = size;
 752         return used;
 753 }
 754
 755 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 756 {
 757         unsigned long size, used;
 758         static const char valid_loose_object_type[8] = {
 759                 0, /* OBJ_EXT */
 760                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 761                 0, /* "delta" and others are invalid in a loose object */
 762         };
 763         enum object_type type;
 764
 765         /* Get the data stream */
 766         memset(stream, 0, sizeof(*stream));
 767         stream->next_in = map;
 768         stream->avail_in = mapsize;
 769         stream->next_out = buffer;
 770         stream->avail_out = bufsiz;
 771
 772         if (legacy_loose_object(map)) {
 773                 inflateInit(stream);
 774                 return inflate(stream, 0);
 775         }
 776
 777         used = unpack_object_header_gently(map, mapsize, &type, &size);
 778         if (!used || !valid_loose_object_type[type])
 779                 return -1;
 780         map += used;
 781         mapsize -= used;
 782
 783         /* Set up the stream for the rest.. */
 784         stream->next_in = map;
 785         stream->avail_in = mapsize;
 786         inflateInit(stream);
 787
 788         /* And generate the fake traditional header */
 789         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 790                                          type_names[type], size);
 791         return 0;
 792 }
 793
 794 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 795 {
 796         int bytes = strlen(buffer) + 1;
 797         unsigned char *buf = xmalloc(1+size);
 798         unsigned long n;
 799
 800         n = stream->total_out - bytes;
 801         if (n > size)
 802                 n = size;
 803         memcpy(buf, (char *) buffer + bytes, n);
 804         bytes = n;
 805         if (bytes < size) {
 806                 stream->next_out = buf + bytes;
 807                 stream->avail_out = size - bytes;
 808                 while (inflate(stream, Z_FINISH) == Z_OK)
 809                         /* nothing */;
 810         }
 811         buf[size] = 0;
 812         inflateEnd(stream);
 813         return buf;
 814 }
 815
 816 /*
 817  * We used to just use "sscanf()", but that's actually way
 818  * too permissive for what we want to check. So do an anal
 819  * object header parse by hand.
 820  */
 821 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 822 {
 823         int i;
 824         unsigned long size;
 825
 826         /*
 827          * The type can be at most ten bytes (including the
 828          * terminating '\0' that we add), and is followed by
 829          * a space.
 830          */
 831         i = 10;
 832         for (;;) {
 833                 char c = *hdr++;
 834                 if (c == ' ')
 835                         break;
 836                 if (!--i)
 837                         return -1;
 838                 *type++ = c;
 839         }
 840         *type = 0;
 841
 842         /*
 843          * The length must follow immediately, and be in canonical
 844          * decimal format (ie "010" is not valid).
 845          */
 846         size = *hdr++ - '0';
 847         if (size > 9)
 848                 return -1;
 849         if (size) {
 850                 for (;;) {
 851                         unsigned long c = *hdr - '0';
 852                         if (c > 9)
 853                                 break;
 854                         hdr++;
 855                         size = size * 10 + c;
 856                 }
 857         }
 858         *sizep = size;
 859
 860         /*
 861          * The length must be followed by a zero byte
 862          */
 863         return *hdr ? -1 : 0;
 864 }
 865
 866 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 867 {
 868         int ret;
 869         z_stream stream;
 870         char hdr[8192];
 871
 872         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 873         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 874                 return NULL;
 875
 876         return unpack_sha1_rest(&stream, hdr, *size);
 877 }
 878
 879 static unsigned long get_delta_base(struct packed_git *p,
 880                                     unsigned long offset,
 881                                     enum object_type kind,
 882                                     unsigned long delta_obj_offset,
 883                                     unsigned long *base_obj_offset)
 884 {
 885         unsigned char *base_info = p->windows->base + offset;
 886         unsigned long base_offset;
 887
 888         /* there must be at least 20 bytes left regardless of delta type */
 889         if (p->pack_size <= offset + 20)
 890                 die("truncated pack file");
 891
 892         if (kind == OBJ_OFS_DELTA) {
 893                 unsigned used = 0;
 894                 unsigned char c = base_info[used++];
 895                 base_offset = c & 127;
 896                 while (c & 128) {
 897                         base_offset += 1;
 898                         if (!base_offset || base_offset & ~(~0UL >> 7))
 899                                 die("offset value overflow for delta base object");
 900                         c = base_info[used++];
 901                         base_offset = (base_offset << 7) + (c & 127);
 902                 }
 903                 base_offset = delta_obj_offset - base_offset;
 904                 if (base_offset >= delta_obj_offset)
 905                         die("delta base offset out of bound");
 906                 offset += used;
 907         } else if (kind == OBJ_REF_DELTA) {
 908                 /* The base entry _must_ be in the same pack */
 909                 base_offset = find_pack_entry_one(base_info, p);
 910                 if (!base_offset)
 911                         die("failed to find delta-pack base object %s",
 912                                 sha1_to_hex(base_info));
 913                 offset += 20;
 914         } else
 915                 die("I am totally screwed");
 916         *base_obj_offset = base_offset;
 917         return offset;
 918 }
 919
 920 /* forward declaration for a mutually recursive function */
 921 static int packed_object_info(struct packed_git *p, unsigned long offset,
 922                               char *type, unsigned long *sizep);
 923
 924 static int packed_delta_info(struct packed_git *p,
 925                              unsigned long offset,
 926                              enum object_type kind,
 927                              unsigned long obj_offset,
 928                              char *type,
 929                              unsigned long *sizep)
 930 {
 931         unsigned long base_offset;
 932
 933         offset = get_delta_base(p, offset, kind, obj_offset, &base_offset);
 934
 935         /* We choose to only get the type of the base object and
 936          * ignore potentially corrupt pack file that expects the delta
 937          * based on a base with a wrong size.  This saves tons of
 938          * inflate() calls.
 939          */
 940         if (packed_object_info(p, base_offset, type, NULL))
 941                 die("cannot get info for delta-pack base");
 942
 943         if (sizep) {
 944                 const unsigned char *data;
 945                 unsigned char delta_head[20];
 946                 unsigned long result_size;
 947                 z_stream stream;
 948                 int st;
 949
 950                 memset(&stream, 0, sizeof(stream));
 951
 952                 stream.next_in = p->windows->base + offset;
 953                 stream.avail_in = p->pack_size - offset;
 954                 stream.next_out = delta_head;
 955                 stream.avail_out = sizeof(delta_head);
 956
 957                 inflateInit(&stream);
 958                 st = inflate(&stream, Z_FINISH);
 959                 inflateEnd(&stream);
 960                 if ((st != Z_STREAM_END) &&
 961                     stream.total_out != sizeof(delta_head))
 962                         die("delta data unpack-initial failed");
 963
 964                 /* Examine the initial part of the delta to figure out
 965                  * the result size.
 966                  */
 967                 data = delta_head;
 968
 969                 /* ignore base size */
 970                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 971
 972                 /* Read the result size */
 973                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 974                 *sizep = result_size;
 975         }
 976         return 0;
 977 }
 978
 979 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 980         enum object_type *type, unsigned long *sizep)
 981 {
 982         unsigned long used;
 983
 984         if (p->pack_size <= offset)
 985                 die("object offset outside of pack file");
 986
 987         used = unpack_object_header_gently(p->windows->base + offset,
 988                                            p->pack_size - offset, type, sizep);
 989         if (!used)
 990                 die("object offset outside of pack file");
 991
 992         return offset + used;
 993 }
 994
 995 void packed_object_info_detail(struct packed_git *p,
 996                                unsigned long offset,
 997                                char *type,
 998                                unsigned long *size,
 999                                unsigned long *store_size,
1000                                unsigned int *delta_chain_length,
1001                                unsigned char *base_sha1)
1002 {
1003         unsigned long obj_offset, val;
1004         unsigned char *next_sha1;
1005         enum object_type kind;
1006
1007         *delta_chain_length = 0;
1008         obj_offset = offset;
1009         offset = unpack_object_header(p, offset, &kind, size);
1010
1011         for (;;) {
1012                 switch (kind) {
1013                 default:
1014                         die("pack %s contains unknown object type %d",
1015                             p->pack_name, kind);
1016                 case OBJ_COMMIT:
1017                 case OBJ_TREE:
1018                 case OBJ_BLOB:
1019                 case OBJ_TAG:
1020                         strcpy(type, type_names[kind]);
1021                         *store_size = 0; /* notyet */
1022                         return;
1023                 case OBJ_OFS_DELTA:
1024                         get_delta_base(p, offset, kind, obj_offset, &offset);
1025                         if (*delta_chain_length == 0) {
1026                                 /* TODO: find base_sha1 as pointed by offset */
1027                         }
1028                         break;
1029                 case OBJ_REF_DELTA:
1030                         if (p->pack_size <= offset + 20)
1031                                 die("pack file %s records an incomplete delta base",
1032                                     p->pack_name);
1033                         next_sha1 = p->windows->base + offset;
1034                         if (*delta_chain_length == 0)
1035                                 hashcpy(base_sha1, next_sha1);
1036                         offset = find_pack_entry_one(next_sha1, p);
1037                         break;
1038                 }
1039                 obj_offset = offset;
1040                 offset = unpack_object_header(p, offset, &kind, &val);
1041                 (*delta_chain_length)++;
1042         }
1043 }
1044
1045 static int packed_object_info(struct packed_git *p, unsigned long offset,
1046                               char *type, unsigned long *sizep)
1047 {
1048         unsigned long size, obj_offset = offset;
1049         enum object_type kind;
1050
1051         offset = unpack_object_header(p, offset, &kind, &size);
1052
1053         switch (kind) {
1054         case OBJ_OFS_DELTA:
1055         case OBJ_REF_DELTA:
1056                 return packed_delta_info(p, offset, kind, obj_offset, type, sizep);
1057         case OBJ_COMMIT:
1058         case OBJ_TREE:
1059         case OBJ_BLOB:
1060         case OBJ_TAG:
1061                 strcpy(type, type_names[kind]);
1062                 break;
1063         default:
1064                 die("pack %s contains unknown object type %d",
1065                     p->pack_name, kind);
1066         }
1067         if (sizep)
1068                 *sizep = size;
1069         return 0;
1070 }
1071
1072 static void *unpack_compressed_entry(struct packed_git *p,
1073                                     unsigned long offset,
1074                                     unsigned long size)
1075 {
1076         int st;
1077         z_stream stream;
1078         unsigned char *buffer;
1079
1080         buffer = xmalloc(size + 1);
1081         buffer[size] = 0;
1082         memset(&stream, 0, sizeof(stream));
1083         stream.next_in = p->windows->base + offset;
1084         stream.avail_in = p->pack_size - offset;
1085         stream.next_out = buffer;
1086         stream.avail_out = size;
1087
1088         inflateInit(&stream);
1089         st = inflate(&stream, Z_FINISH);
1090         inflateEnd(&stream);
1091         if ((st != Z_STREAM_END) || stream.total_out != size) {
1092                 free(buffer);
1093                 return NULL;
1094         }
1095
1096         return buffer;
1097 }
1098
1099 static void *unpack_delta_entry(struct packed_git *p,
1100                                 unsigned long offset,
1101                                 unsigned long delta_size,
1102                                 enum object_type kind,
1103                                 unsigned long obj_offset,
1104                                 char *type,
1105                                 unsigned long *sizep)
1106 {
1107         void *delta_data, *result, *base;
1108         unsigned long result_size, base_size, base_offset;
1109
1110         offset = get_delta_base(p, offset, kind, obj_offset, &base_offset);
1111         base = unpack_entry(p, base_offset, type, &base_size);
1112         if (!base)
1113                 die("failed to read delta base object at %lu from %s",
1114                     base_offset, p->pack_name);
1115
1116         delta_data = unpack_compressed_entry(p, offset, delta_size);
1117         result = patch_delta(base, base_size,
1118                              delta_data, delta_size,
1119                              &result_size);
1120         if (!result)
1121                 die("failed to apply delta");
1122         free(delta_data);
1123         free(base);
1124         *sizep = result_size;
1125         return result;
1126 }
1127
1128 void *unpack_entry(struct packed_git *p, unsigned long offset,
1129                           char *type, unsigned long *sizep)
1130 {
1131         unsigned long size, obj_offset = offset;
1132         enum object_type kind;
1133         void *retval;
1134
1135         if (use_packed_git(p))
1136                 die("cannot map packed file");
1137         offset = unpack_object_header(p, offset, &kind, &size);
1138         switch (kind) {
1139         case OBJ_OFS_DELTA:
1140         case OBJ_REF_DELTA:
1141                 retval = unpack_delta_entry(p, offset, size, kind, obj_offset, type, sizep);
1142                 break;
1143         case OBJ_COMMIT:
1144         case OBJ_TREE:
1145         case OBJ_BLOB:
1146         case OBJ_TAG:
1147                 strcpy(type, type_names[kind]);
1148                 *sizep = size;
1149                 retval = unpack_compressed_entry(p, offset, size);
1150                 break;
1151         default:
1152                 die("unknown object type %i in %s", kind, p->pack_name);
1153         }
1154         unuse_packed_git(p);
1155         return retval;
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 matches_pack_name(struct packed_git *p, const char *ig)
1196 {
1197         const char *last_c, *c;
1198
1199         if (!strcmp(p->pack_name, ig))
1200                 return 0;
1201
1202         for (c = p->pack_name, last_c = c; *c;)
1203                 if (*c == '/')
1204                         last_c = ++c;
1205                 else
1206                         ++c;
1207         if (!strcmp(last_c, ig))
1208                 return 0;
1209
1210         return 1;
1211 }
1212
1213 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1214 {
1215         struct packed_git *p;
1216         unsigned long offset;
1217
1218         prepare_packed_git();
1219
1220         for (p = packed_git; p; p = p->next) {
1221                 if (ignore_packed) {
1222                         const char **ig;
1223                         for (ig = ignore_packed; *ig; ig++)
1224                                 if (!matches_pack_name(p, *ig))
1225                                         break;
1226                         if (*ig)
1227                                 continue;
1228                 }
1229                 offset = find_pack_entry_one(sha1, p);
1230                 if (offset) {
1231                         e->offset = offset;
1232                         e->p = p;
1233                         hashcpy(e->sha1, sha1);
1234                         return 1;
1235                 }
1236         }
1237         return 0;
1238 }
1239
1240 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1241                                   struct packed_git *packs)
1242 {
1243         struct packed_git *p;
1244
1245         for (p = packs; p; p = p->next) {
1246                 if (find_pack_entry_one(sha1, p))
1247                         return p;
1248         }
1249         return NULL;
1250
1251 }
1252
1253 static int sha1_loose_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1254 {
1255         int status;
1256         unsigned long mapsize, size;
1257         void *map;
1258         z_stream stream;
1259         char hdr[128];
1260
1261         map = map_sha1_file(sha1, &mapsize);
1262         if (!map)
1263                 return error("unable to find %s", sha1_to_hex(sha1));
1264         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1265                 status = error("unable to unpack %s header",
1266                                sha1_to_hex(sha1));
1267         if (parse_sha1_header(hdr, type, &size) < 0)
1268                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1269         else {
1270                 status = 0;
1271                 if (sizep)
1272                         *sizep = size;
1273         }
1274         inflateEnd(&stream);
1275         munmap(map, mapsize);
1276         return status;
1277 }
1278
1279 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1280 {
1281         int status;
1282         struct pack_entry e;
1283
1284         if (!find_pack_entry(sha1, &e, NULL)) {
1285                 reprepare_packed_git();
1286                 if (!find_pack_entry(sha1, &e, NULL))
1287                         return sha1_loose_object_info(sha1, type, sizep);
1288         }
1289         if (use_packed_git(e.p))
1290                 die("cannot map packed file");
1291         status = packed_object_info(e.p, e.offset, type, sizep);
1292         unuse_packed_git(e.p);
1293         return status;
1294 }
1295
1296 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1297 {
1298         struct pack_entry e;
1299
1300         if (!find_pack_entry(sha1, &e, NULL)) {
1301                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1302                 return NULL;
1303         }
1304         return unpack_entry(e.p, e.offset, type, size);
1305 }
1306
1307 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1308 {
1309         unsigned long mapsize;
1310         void *map, *buf;
1311         struct pack_entry e;
1312
1313         if (find_pack_entry(sha1, &e, NULL))
1314                 return read_packed_sha1(sha1, type, size);
1315         map = map_sha1_file(sha1, &mapsize);
1316         if (map) {
1317                 buf = unpack_sha1_file(map, mapsize, type, size);
1318                 munmap(map, mapsize);
1319                 return buf;
1320         }
1321         reprepare_packed_git();
1322         if (find_pack_entry(sha1, &e, NULL))
1323                 return read_packed_sha1(sha1, type, size);
1324         return NULL;
1325 }
1326
1327 void *read_object_with_reference(const unsigned char *sha1,
1328                                  const char *required_type,
1329                                  unsigned long *size,
1330                                  unsigned char *actual_sha1_return)
1331 {
1332         char type[20];
1333         void *buffer;
1334         unsigned long isize;
1335         unsigned char actual_sha1[20];
1336
1337         hashcpy(actual_sha1, sha1);
1338         while (1) {
1339                 int ref_length = -1;
1340                 const char *ref_type = NULL;
1341
1342                 buffer = read_sha1_file(actual_sha1, type, &isize);
1343                 if (!buffer)
1344                         return NULL;
1345                 if (!strcmp(type, required_type)) {
1346                         *size = isize;
1347                         if (actual_sha1_return)
1348                                 hashcpy(actual_sha1_return, actual_sha1);
1349                         return buffer;
1350                 }
1351                 /* Handle references */
1352                 else if (!strcmp(type, commit_type))
1353                         ref_type = "tree ";
1354                 else if (!strcmp(type, tag_type))
1355                         ref_type = "object ";
1356                 else {
1357                         free(buffer);
1358                         return NULL;
1359                 }
1360                 ref_length = strlen(ref_type);
1361
1362                 if (memcmp(buffer, ref_type, ref_length) ||
1363                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1364                         free(buffer);
1365                         return NULL;
1366                 }
1367                 free(buffer);
1368                 /* Now we have the ID of the referred-to object in
1369                  * actual_sha1.  Check again. */
1370         }
1371 }
1372
1373 static void write_sha1_file_prepare(void *buf, unsigned long len,
1374                                     const char *type, unsigned char *sha1,
1375                                     unsigned char *hdr, int *hdrlen)
1376 {
1377         SHA_CTX c;
1378
1379         /* Generate the header */
1380         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1381
1382         /* Sha1.. */
1383         SHA1_Init(&c);
1384         SHA1_Update(&c, hdr, *hdrlen);
1385         SHA1_Update(&c, buf, len);
1386         SHA1_Final(sha1, &c);
1387 }
1388
1389 /*
1390  * Link the tempfile to the final place, possibly creating the
1391  * last directory level as you do so.
1392  *
1393  * Returns the errno on failure, 0 on success.
1394  */
1395 static int link_temp_to_file(const char *tmpfile, const char *filename)
1396 {
1397         int ret;
1398         char *dir;
1399
1400         if (!link(tmpfile, filename))
1401                 return 0;
1402
1403         /*
1404          * Try to mkdir the last path component if that failed.
1405          *
1406          * Re-try the "link()" regardless of whether the mkdir
1407          * succeeds, since a race might mean that somebody
1408          * else succeeded.
1409          */
1410         ret = errno;
1411         dir = strrchr(filename, '/');
1412         if (dir) {
1413                 *dir = 0;
1414                 if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1415                         *dir = '/';
1416                         return -2;
1417                 }
1418                 *dir = '/';
1419                 if (!link(tmpfile, filename))
1420                         return 0;
1421                 ret = errno;
1422         }
1423         return ret;
1424 }
1425
1426 /*
1427  * Move the just written object into its final resting place
1428  */
1429 int move_temp_to_file(const char *tmpfile, const char *filename)
1430 {
1431         int ret = link_temp_to_file(tmpfile, filename);
1432
1433         /*
1434          * Coda hack - coda doesn't like cross-directory links,
1435          * so we fall back to a rename, which will mean that it
1436          * won't be able to check collisions, but that's not a
1437          * big deal.
1438          *
1439          * The same holds for FAT formatted media.
1440          *
1441          * When this succeeds, we just return 0. We have nothing
1442          * left to unlink.
1443          */
1444         if (ret && ret != EEXIST) {
1445                 if (!rename(tmpfile, filename))
1446                         return 0;
1447                 ret = errno;
1448         }
1449         unlink(tmpfile);
1450         if (ret) {
1451                 if (ret != EEXIST) {
1452                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1453                 }
1454                 /* FIXME!!! Collision check here ? */
1455         }
1456
1457         return 0;
1458 }
1459
1460 static int write_buffer(int fd, const void *buf, size_t len)
1461 {
1462         while (len) {
1463                 ssize_t size;
1464
1465                 size = write(fd, buf, len);
1466                 if (!size)
1467                         return error("file write: disk full");
1468                 if (size < 0) {
1469                         if (errno == EINTR || errno == EAGAIN)
1470                                 continue;
1471                         return error("file write error (%s)", strerror(errno));
1472                 }
1473                 len -= size;
1474                 buf = (char *) buf + size;
1475         }
1476         return 0;
1477 }
1478
1479 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1480 {
1481         int hdr_len;
1482         unsigned char c;
1483
1484         c = (type << 4) | (len & 15);
1485         len >>= 4;
1486         hdr_len = 1;
1487         while (len) {
1488                 *hdr++ = c | 0x80;
1489                 hdr_len++;
1490                 c = (len & 0x7f);
1491                 len >>= 7;
1492         }
1493         *hdr = c;
1494         return hdr_len;
1495 }
1496
1497 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1498 {
1499         int obj_type, hdr;
1500
1501         if (use_legacy_headers) {
1502                 while (deflate(stream, 0) == Z_OK)
1503                         /* nothing */;
1504                 return;
1505         }
1506         if (!strcmp(type, blob_type))
1507                 obj_type = OBJ_BLOB;
1508         else if (!strcmp(type, tree_type))
1509                 obj_type = OBJ_TREE;
1510         else if (!strcmp(type, commit_type))
1511                 obj_type = OBJ_COMMIT;
1512         else if (!strcmp(type, tag_type))
1513                 obj_type = OBJ_TAG;
1514         else
1515                 die("trying to generate bogus object of type '%s'", type);
1516         hdr = write_binary_header(stream->next_out, obj_type, len);
1517         stream->total_out = hdr;
1518         stream->next_out += hdr;
1519         stream->avail_out -= hdr;
1520 }
1521
1522 int hash_sha1_file(void *buf, unsigned long len, const char *type,
1523                    unsigned char *sha1)
1524 {
1525         unsigned char hdr[50];
1526         int hdrlen;
1527         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1528         return 0;
1529 }
1530
1531 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1532 {
1533         int size;
1534         unsigned char *compressed;
1535         z_stream stream;
1536         unsigned char sha1[20];
1537         char *filename;
1538         static char tmpfile[PATH_MAX];
1539         unsigned char hdr[50];
1540         int fd, hdrlen;
1541
1542         /* Normally if we have it in the pack then we do not bother writing
1543          * it out into .git/objects/??/?{38} file.
1544          */
1545         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1546         filename = sha1_file_name(sha1);
1547         if (returnsha1)
1548                 hashcpy(returnsha1, sha1);
1549         if (has_sha1_file(sha1))
1550                 return 0;
1551         fd = open(filename, O_RDONLY);
1552         if (fd >= 0) {
1553                 /*
1554                  * FIXME!!! We might do collision checking here, but we'd
1555                  * need to uncompress the old file and check it. Later.
1556                  */
1557                 close(fd);
1558                 return 0;
1559         }
1560
1561         if (errno != ENOENT) {
1562                 return error("sha1 file %s: %s\n", filename, strerror(errno));
1563         }
1564
1565         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1566
1567         fd = mkstemp(tmpfile);
1568         if (fd < 0) {
1569                 if (errno == EPERM)
1570                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1571                 else
1572                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1573         }
1574
1575         /* Set it up */
1576         memset(&stream, 0, sizeof(stream));
1577         deflateInit(&stream, zlib_compression_level);
1578         size = 8 + deflateBound(&stream, len+hdrlen);
1579         compressed = xmalloc(size);
1580
1581         /* Compress it */
1582         stream.next_out = compressed;
1583         stream.avail_out = size;
1584
1585         /* First header.. */
1586         stream.next_in = hdr;
1587         stream.avail_in = hdrlen;
1588         setup_object_header(&stream, type, len);
1589
1590         /* Then the data itself.. */
1591         stream.next_in = buf;
1592         stream.avail_in = len;
1593         while (deflate(&stream, Z_FINISH) == Z_OK)
1594                 /* nothing */;
1595         deflateEnd(&stream);
1596         size = stream.total_out;
1597
1598         if (write_buffer(fd, compressed, size) < 0)
1599                 die("unable to write sha1 file");
1600         fchmod(fd, 0444);
1601         close(fd);
1602         free(compressed);
1603
1604         return move_temp_to_file(tmpfile, filename);
1605 }
1606
1607 /*
1608  * We need to unpack and recompress the object for writing
1609  * it out to a different file.
1610  */
1611 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1612 {
1613         size_t size;
1614         z_stream stream;
1615         unsigned char *unpacked;
1616         unsigned long len;
1617         char type[20];
1618         char hdr[50];
1619         int hdrlen;
1620         void *buf;
1621
1622         /* need to unpack and recompress it by itself */
1623         unpacked = read_packed_sha1(sha1, type, &len);
1624
1625         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1626
1627         /* Set it up */
1628         memset(&stream, 0, sizeof(stream));
1629         deflateInit(&stream, zlib_compression_level);
1630         size = deflateBound(&stream, len + hdrlen);
1631         buf = xmalloc(size);
1632
1633         /* Compress it */
1634         stream.next_out = buf;
1635         stream.avail_out = size;
1636
1637         /* First header.. */
1638         stream.next_in = (void *)hdr;
1639         stream.avail_in = hdrlen;
1640         while (deflate(&stream, 0) == Z_OK)
1641                 /* nothing */;
1642
1643         /* Then the data itself.. */
1644         stream.next_in = unpacked;
1645         stream.avail_in = len;
1646         while (deflate(&stream, Z_FINISH) == Z_OK)
1647                 /* nothing */;
1648         deflateEnd(&stream);
1649         free(unpacked);
1650
1651         *objsize = stream.total_out;
1652         return buf;
1653 }
1654
1655 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1656 {
1657         int retval;
1658         unsigned long objsize;
1659         void *buf = map_sha1_file(sha1, &objsize);
1660
1661         if (buf) {
1662                 retval = write_buffer(fd, buf, objsize);
1663                 munmap(buf, objsize);
1664                 return retval;
1665         }
1666
1667         buf = repack_object(sha1, &objsize);
1668         retval = write_buffer(fd, buf, objsize);
1669         free(buf);
1670         return retval;
1671 }
1672
1673 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1674                        size_t bufsize, size_t *bufposn)
1675 {
1676         char tmpfile[PATH_MAX];
1677         int local;
1678         z_stream stream;
1679         unsigned char real_sha1[20];
1680         unsigned char discard[4096];
1681         int ret;
1682         SHA_CTX c;
1683
1684         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1685
1686         local = mkstemp(tmpfile);
1687         if (local < 0) {
1688                 if (errno == EPERM)
1689                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1690                 else
1691                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1692         }
1693
1694         memset(&stream, 0, sizeof(stream));
1695
1696         inflateInit(&stream);
1697
1698         SHA1_Init(&c);
1699
1700         do {
1701                 ssize_t size;
1702                 if (*bufposn) {
1703                         stream.avail_in = *bufposn;
1704                         stream.next_in = (unsigned char *) buffer;
1705                         do {
1706                                 stream.next_out = discard;
1707                                 stream.avail_out = sizeof(discard);
1708                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1709                                 SHA1_Update(&c, discard, sizeof(discard) -
1710                                             stream.avail_out);
1711                         } while (stream.avail_in && ret == Z_OK);
1712                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1713                                 die("unable to write sha1 file");
1714                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1715                                 stream.avail_in);
1716                         *bufposn = stream.avail_in;
1717                         if (ret != Z_OK)
1718                                 break;
1719                 }
1720                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1721                 if (size <= 0) {
1722                         close(local);
1723                         unlink(tmpfile);
1724                         if (!size)
1725                                 return error("Connection closed?");
1726                         perror("Reading from connection");
1727                         return -1;
1728                 }
1729                 *bufposn += size;
1730         } while (1);
1731         inflateEnd(&stream);
1732
1733         close(local);
1734         SHA1_Final(real_sha1, &c);
1735         if (ret != Z_STREAM_END) {
1736                 unlink(tmpfile);
1737                 return error("File %s corrupted", sha1_to_hex(sha1));
1738         }
1739         if (hashcmp(sha1, real_sha1)) {
1740                 unlink(tmpfile);
1741                 return error("File %s has bad hash", sha1_to_hex(sha1));
1742         }
1743
1744         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1745 }
1746
1747 int has_pack_index(const unsigned char *sha1)
1748 {
1749         struct stat st;
1750         if (stat(sha1_pack_index_name(sha1), &st))
1751                 return 0;
1752         return 1;
1753 }
1754
1755 int has_pack_file(const unsigned char *sha1)
1756 {
1757         struct stat st;
1758         if (stat(sha1_pack_name(sha1), &st))
1759                 return 0;
1760         return 1;
1761 }
1762
1763 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
1764 {
1765         struct pack_entry e;
1766         return find_pack_entry(sha1, &e, ignore_packed);
1767 }
1768
1769 int has_sha1_file(const unsigned char *sha1)
1770 {
1771         struct stat st;
1772         struct pack_entry e;
1773
1774         if (find_pack_entry(sha1, &e, NULL))
1775                 return 1;
1776         return find_sha1_file(sha1, &st) ? 1 : 0;
1777 }
1778
1779 /*
1780  * reads from fd as long as possible into a supplied buffer of size bytes.
1781  * If necessary the buffer's size is increased using realloc()
1782  *
1783  * returns 0 if anything went fine and -1 otherwise
1784  *
1785  * NOTE: both buf and size may change, but even when -1 is returned
1786  * you still have to free() it yourself.
1787  */
1788 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1789 {
1790         char* buf = *return_buf;
1791         unsigned long size = *return_size;
1792         int iret;
1793         unsigned long off = 0;
1794
1795         do {
1796                 iret = xread(fd, buf + off, size - off);
1797                 if (iret > 0) {
1798                         off += iret;
1799                         if (off == size) {
1800                                 size *= 2;
1801                                 buf = xrealloc(buf, size);
1802                         }
1803                 }
1804         } while (iret > 0);
1805
1806         *return_buf = buf;
1807         *return_size = off;
1808
1809         if (iret < 0)
1810                 return -1;
1811         return 0;
1812 }
1813
1814 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1815 {
1816         unsigned long size = 4096;
1817         char *buf = xmalloc(size);
1818         int ret;
1819
1820         if (read_pipe(fd, &buf, &size)) {
1821                 free(buf);
1822                 return -1;
1823         }
1824
1825         if (!type)
1826                 type = blob_type;
1827         if (write_object)
1828                 ret = write_sha1_file(buf, size, type, sha1);
1829         else
1830                 ret = hash_sha1_file(buf, size, type, sha1);
1831         free(buf);
1832         return ret;
1833 }
1834
1835 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1836 {
1837         unsigned long size = st->st_size;
1838         void *buf;
1839         int ret;
1840
1841         buf = "";
1842         if (size)
1843                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1844         close(fd);
1845         if (buf == MAP_FAILED)
1846                 return -1;
1847
1848         if (!type)
1849                 type = blob_type;
1850         if (write_object)
1851                 ret = write_sha1_file(buf, size, type, sha1);
1852         else
1853                 ret = hash_sha1_file(buf, size, type, sha1);
1854         if (size)
1855                 munmap(buf, size);
1856         return ret;
1857 }
1858
1859 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1860 {
1861         int fd;
1862         char *target;
1863
1864         switch (st->st_mode & S_IFMT) {
1865         case S_IFREG:
1866                 fd = open(path, O_RDONLY);
1867                 if (fd < 0)
1868                         return error("open(\"%s\"): %s", path,
1869                                      strerror(errno));
1870                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1871                         return error("%s: failed to insert into database",
1872                                      path);
1873                 break;
1874         case S_IFLNK:
1875                 target = xmalloc(st->st_size+1);
1876                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1877                         char *errstr = strerror(errno);
1878                         free(target);
1879                         return error("readlink(\"%s\"): %s", path,
1880                                      errstr);
1881                 }
1882                 if (!write_object)
1883                         hash_sha1_file(target, st->st_size, blob_type, sha1);
1884                 else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1885                         return error("%s: failed to insert into database",
1886                                      path);
1887                 free(target);
1888                 break;
1889         default:
1890                 return error("%s: unsupported file type", path);
1891         }
1892         return 0;
1893 }