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 #ifdef NO_C99_FORMAT
  26 #define SZ_FMT "lu"
  27 #else
  28 #define SZ_FMT "zu"
  29 #endif
  30
  31 const unsigned char null_sha1[20];
  32
  33 static unsigned int sha1_file_open_flag = O_NOATIME;
  34
  35 signed char hexval_table[256] = {
  36          -1, -1, -1, -1, -1, -1, -1, -1,                /* 00-07 */
  37          -1, -1, -1, -1, -1, -1, -1, -1,                /* 08-0f */
  38          -1, -1, -1, -1, -1, -1, -1, -1,                /* 10-17 */
  39          -1, -1, -1, -1, -1, -1, -1, -1,                /* 18-1f */
  40          -1, -1, -1, -1, -1, -1, -1, -1,                /* 20-27 */
  41          -1, -1, -1, -1, -1, -1, -1, -1,                /* 28-2f */
  42           0,  1,  2,  3,  4,  5,  6,  7,                /* 30-37 */
  43           8,  9, -1, -1, -1, -1, -1, -1,                /* 38-3f */
  44          -1, 10, 11, 12, 13, 14, 15, -1,                /* 40-47 */
  45          -1, -1, -1, -1, -1, -1, -1, -1,                /* 48-4f */
  46          -1, -1, -1, -1, -1, -1, -1, -1,                /* 50-57 */
  47          -1, -1, -1, -1, -1, -1, -1, -1,                /* 58-5f */
  48          -1, 10, 11, 12, 13, 14, 15, -1,                /* 60-67 */
  49          -1, -1, -1, -1, -1, -1, -1, -1,                /* 68-67 */
  50          -1, -1, -1, -1, -1, -1, -1, -1,                /* 70-77 */
  51          -1, -1, -1, -1, -1, -1, -1, -1,                /* 78-7f */
  52          -1, -1, -1, -1, -1, -1, -1, -1,                /* 80-87 */
  53          -1, -1, -1, -1, -1, -1, -1, -1,                /* 88-8f */
  54          -1, -1, -1, -1, -1, -1, -1, -1,                /* 90-97 */
  55          -1, -1, -1, -1, -1, -1, -1, -1,                /* 98-9f */
  56          -1, -1, -1, -1, -1, -1, -1, -1,                /* a0-a7 */
  57          -1, -1, -1, -1, -1, -1, -1, -1,                /* a8-af */
  58          -1, -1, -1, -1, -1, -1, -1, -1,                /* b0-b7 */
  59          -1, -1, -1, -1, -1, -1, -1, -1,                /* b8-bf */
  60          -1, -1, -1, -1, -1, -1, -1, -1,                /* c0-c7 */
  61          -1, -1, -1, -1, -1, -1, -1, -1,                /* c8-cf */
  62          -1, -1, -1, -1, -1, -1, -1, -1,                /* d0-d7 */
  63          -1, -1, -1, -1, -1, -1, -1, -1,                /* d8-df */
  64          -1, -1, -1, -1, -1, -1, -1, -1,                /* e0-e7 */
  65          -1, -1, -1, -1, -1, -1, -1, -1,                /* e8-ef */
  66          -1, -1, -1, -1, -1, -1, -1, -1,                /* f0-f7 */
  67          -1, -1, -1, -1, -1, -1, -1, -1,                /* f8-ff */
  68 };
  69
  70 int get_sha1_hex(const char *hex, unsigned char *sha1)
  71 {
  72         int i;
  73         for (i = 0; i < 20; i++) {
  74                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  75                 if (val & ~0xff)
  76                         return -1;
  77                 *sha1++ = val;
  78                 hex += 2;
  79         }
  80         return 0;
  81 }
  82
  83 int safe_create_leading_directories(char *path)
  84 {
  85         char *pos = path;
  86         struct stat st;
  87
  88         if (*pos == '/')
  89                 pos++;
  90
  91         while (pos) {
  92                 pos = strchr(pos, '/');
  93                 if (!pos)
  94                         break;
  95                 *pos = 0;
  96                 if (!stat(path, &st)) {
  97                         /* path exists */
  98                         if (!S_ISDIR(st.st_mode)) {
  99                                 *pos = '/';
 100                                 return -3;
 101                         }
 102                 }
 103                 else if (mkdir(path, 0777)) {
 104                         *pos = '/';
 105                         return -1;
 106                 }
 107                 else if (adjust_shared_perm(path)) {
 108                         *pos = '/';
 109                         return -2;
 110                 }
 111                 *pos++ = '/';
 112         }
 113         return 0;
 114 }
 115
 116 char * sha1_to_hex(const unsigned char *sha1)
 117 {
 118         static int bufno;
 119         static char hexbuffer[4][50];
 120         static const char hex[] = "0123456789abcdef";
 121         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
 122         int i;
 123
 124         for (i = 0; i < 20; i++) {
 125                 unsigned int val = *sha1++;
 126                 *buf++ = hex[val >> 4];
 127                 *buf++ = hex[val & 0xf];
 128         }
 129         *buf = '\0';
 130
 131         return buffer;
 132 }
 133
 134 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 135 {
 136         int i;
 137         for (i = 0; i < 20; i++) {
 138                 static char hex[] = "0123456789abcdef";
 139                 unsigned int val = sha1[i];
 140                 char *pos = pathbuf + i*2 + (i > 0);
 141                 *pos++ = hex[val >> 4];
 142                 *pos = hex[val & 0xf];
 143         }
 144 }
 145
 146 /*
 147  * NOTE! This returns a statically allocated buffer, so you have to be
 148  * careful about using it. Do a "xstrdup()" if you need to save the
 149  * filename.
 150  *
 151  * Also note that this returns the location for creating.  Reading
 152  * SHA1 file can happen from any alternate directory listed in the
 153  * DB_ENVIRONMENT environment variable if it is not found in
 154  * the primary object database.
 155  */
 156 char *sha1_file_name(const unsigned char *sha1)
 157 {
 158         static char *name, *base;
 159
 160         if (!base) {
 161                 const char *sha1_file_directory = get_object_directory();
 162                 int len = strlen(sha1_file_directory);
 163                 base = xmalloc(len + 60);
 164                 memcpy(base, sha1_file_directory, len);
 165                 memset(base+len, 0, 60);
 166                 base[len] = '/';
 167                 base[len+3] = '/';
 168                 name = base + len + 1;
 169         }
 170         fill_sha1_path(name, sha1);
 171         return base;
 172 }
 173
 174 char *sha1_pack_name(const unsigned char *sha1)
 175 {
 176         static const char hex[] = "0123456789abcdef";
 177         static char *name, *base, *buf;
 178         int i;
 179
 180         if (!base) {
 181                 const char *sha1_file_directory = get_object_directory();
 182                 int len = strlen(sha1_file_directory);
 183                 base = xmalloc(len + 60);
 184                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 185                 name = base + len + 11;
 186         }
 187
 188         buf = name;
 189
 190         for (i = 0; i < 20; i++) {
 191                 unsigned int val = *sha1++;
 192                 *buf++ = hex[val >> 4];
 193                 *buf++ = hex[val & 0xf];
 194         }
 195
 196         return base;
 197 }
 198
 199 char *sha1_pack_index_name(const unsigned char *sha1)
 200 {
 201         static const char hex[] = "0123456789abcdef";
 202         static char *name, *base, *buf;
 203         int i;
 204
 205         if (!base) {
 206                 const char *sha1_file_directory = get_object_directory();
 207                 int len = strlen(sha1_file_directory);
 208                 base = xmalloc(len + 60);
 209                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 210                 name = base + len + 11;
 211         }
 212
 213         buf = name;
 214
 215         for (i = 0; i < 20; i++) {
 216                 unsigned int val = *sha1++;
 217                 *buf++ = hex[val >> 4];
 218                 *buf++ = hex[val & 0xf];
 219         }
 220
 221         return base;
 222 }
 223
 224 struct alternate_object_database *alt_odb_list;
 225 static struct alternate_object_database **alt_odb_tail;
 226
 227 static void read_info_alternates(const char * alternates, int depth);
 228
 229 /*
 230  * Prepare alternate object database registry.
 231  *
 232  * The variable alt_odb_list points at the list of struct
 233  * alternate_object_database.  The elements on this list come from
 234  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 235  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 236  * whose contents is similar to that environment variable but can be
 237  * LF separated.  Its base points at a statically allocated buffer that
 238  * contains "/the/directory/corresponding/to/.git/objects/...", while
 239  * its name points just after the slash at the end of ".git/objects/"
 240  * in the example above, and has enough space to hold 40-byte hex
 241  * SHA1, an extra slash for the first level indirection, and the
 242  * terminating NUL.
 243  */
 244 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 245 {
 246         struct stat st;
 247         const char *objdir = get_object_directory();
 248         struct alternate_object_database *ent;
 249         struct alternate_object_database *alt;
 250         /* 43 = 40-byte + 2 '/' + terminating NUL */
 251         int pfxlen = len;
 252         int entlen = pfxlen + 43;
 253         int base_len = -1;
 254
 255         if (*entry != '/' && relative_base) {
 256                 /* Relative alt-odb */
 257                 if (base_len < 0)
 258                         base_len = strlen(relative_base) + 1;
 259                 entlen += base_len;
 260                 pfxlen += base_len;
 261         }
 262         ent = xmalloc(sizeof(*ent) + entlen);
 263
 264         if (*entry != '/' && relative_base) {
 265                 memcpy(ent->base, relative_base, base_len - 1);
 266                 ent->base[base_len - 1] = '/';
 267                 memcpy(ent->base + base_len, entry, len);
 268         }
 269         else
 270                 memcpy(ent->base, entry, pfxlen);
 271
 272         ent->name = ent->base + pfxlen + 1;
 273         ent->base[pfxlen + 3] = '/';
 274         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 275
 276         /* Detect cases where alternate disappeared */
 277         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 278                 error("object directory %s does not exist; "
 279                       "check .git/objects/info/alternates.",
 280                       ent->base);
 281                 free(ent);
 282                 return -1;
 283         }
 284
 285         /* Prevent the common mistake of listing the same
 286          * thing twice, or object directory itself.
 287          */
 288         for (alt = alt_odb_list; alt; alt = alt->next) {
 289                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 290                         free(ent);
 291                         return -1;
 292                 }
 293         }
 294         if (!memcmp(ent->base, objdir, pfxlen)) {
 295                 free(ent);
 296                 return -1;
 297         }
 298
 299         /* add the alternate entry */
 300         *alt_odb_tail = ent;
 301         alt_odb_tail = &(ent->next);
 302         ent->next = NULL;
 303
 304         /* recursively add alternates */
 305         read_info_alternates(ent->base, depth + 1);
 306
 307         ent->base[pfxlen] = '/';
 308
 309         return 0;
 310 }
 311
 312 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 313                                  const char *relative_base, int depth)
 314 {
 315         const char *cp, *last;
 316
 317         if (depth > 5) {
 318                 error("%s: ignoring alternate object stores, nesting too deep.",
 319                                 relative_base);
 320                 return;
 321         }
 322
 323         last = alt;
 324         while (last < ep) {
 325                 cp = last;
 326                 if (cp < ep && *cp == '#') {
 327                         while (cp < ep && *cp != sep)
 328                                 cp++;
 329                         last = cp + 1;
 330                         continue;
 331                 }
 332                 while (cp < ep && *cp != sep)
 333                         cp++;
 334                 if (last != cp) {
 335                         if ((*last != '/') && depth) {
 336                                 error("%s: ignoring relative alternate object store %s",
 337                                                 relative_base, last);
 338                         } else {
 339                                 link_alt_odb_entry(last, cp - last,
 340                                                 relative_base, depth);
 341                         }
 342                 }
 343                 while (cp < ep && *cp == sep)
 344                         cp++;
 345                 last = cp;
 346         }
 347 }
 348
 349 static void read_info_alternates(const char * relative_base, int depth)
 350 {
 351         char *map;
 352         struct stat st;
 353         char path[PATH_MAX];
 354         int fd;
 355
 356         sprintf(path, "%s/info/alternates", relative_base);
 357         fd = open(path, O_RDONLY);
 358         if (fd < 0)
 359                 return;
 360         if (fstat(fd, &st) || (st.st_size == 0)) {
 361                 close(fd);
 362                 return;
 363         }
 364         map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 365         close(fd);
 366
 367         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 368
 369         munmap(map, st.st_size);
 370 }
 371
 372 void prepare_alt_odb(void)
 373 {
 374         const char *alt;
 375
 376         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 377         if (!alt) alt = "";
 378
 379         if (alt_odb_tail)
 380                 return;
 381         alt_odb_tail = &alt_odb_list;
 382         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 383
 384         read_info_alternates(get_object_directory(), 0);
 385 }
 386
 387 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 388 {
 389         char *name = sha1_file_name(sha1);
 390         struct alternate_object_database *alt;
 391
 392         if (!stat(name, st))
 393                 return name;
 394         prepare_alt_odb();
 395         for (alt = alt_odb_list; alt; alt = alt->next) {
 396                 name = alt->name;
 397                 fill_sha1_path(name, sha1);
 398                 if (!stat(alt->base, st))
 399                         return alt->base;
 400         }
 401         return NULL;
 402 }
 403
 404 static unsigned int pack_used_ctr;
 405 static unsigned int pack_mmap_calls;
 406 static unsigned int peak_pack_open_windows;
 407 static unsigned int pack_open_windows;
 408 static size_t peak_pack_mapped;
 409 static size_t pack_mapped;
 410 static size_t page_size;
 411 struct packed_git *packed_git;
 412
 413 void pack_report()
 414 {
 415         fprintf(stderr,
 416                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 417                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 418                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 419                 page_size,
 420                 packed_git_window_size,
 421                 packed_git_limit);
 422         fprintf(stderr,
 423                 "pack_report: pack_used_ctr            = %10u\n"
 424                 "pack_report: pack_mmap_calls          = %10u\n"
 425                 "pack_report: pack_open_windows        = %10u / %10u\n"
 426                 "pack_report: pack_mapped              = "
 427                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
 428                 pack_used_ctr,
 429                 pack_mmap_calls,
 430                 pack_open_windows, peak_pack_open_windows,
 431                 pack_mapped, peak_pack_mapped);
 432 }
 433
 434 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 435                                 void **idx_map_)
 436 {
 437         void *idx_map;
 438         unsigned int *index;
 439         unsigned long idx_size;
 440         int nr, i;
 441         int fd = open(path, O_RDONLY);
 442         struct stat st;
 443         if (fd < 0)
 444                 return -1;
 445         if (fstat(fd, &st)) {
 446                 close(fd);
 447                 return -1;
 448         }
 449         idx_size = st.st_size;
 450         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 451         close(fd);
 452
 453         index = idx_map;
 454         *idx_map_ = idx_map;
 455         *idx_size_ = idx_size;
 456
 457         /* check index map */
 458         if (idx_size < 4*256 + 20 + 20)
 459                 return error("index file too small");
 460         nr = 0;
 461         for (i = 0; i < 256; i++) {
 462                 unsigned int n = ntohl(index[i]);
 463                 if (n < nr)
 464                         return error("non-monotonic index");
 465                 nr = n;
 466         }
 467
 468         /*
 469          * Total size:
 470          *  - 256 index entries 4 bytes each
 471          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 472          *  - 20-byte SHA1 of the packfile
 473          *  - 20-byte SHA1 file checksum
 474          */
 475         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 476                 return error("wrong index file size");
 477
 478         return 0;
 479 }
 480
 481 static void scan_windows(struct packed_git *p,
 482         struct packed_git **lru_p,
 483         struct pack_window **lru_w,
 484         struct pack_window **lru_l)
 485 {
 486         struct pack_window *w, *w_l;
 487
 488         for (w_l = NULL, w = p->windows; w; w = w->next) {
 489                 if (!w->inuse_cnt) {
 490                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 491                                 *lru_p = p;
 492                                 *lru_w = w;
 493                                 *lru_l = w_l;
 494                         }
 495                 }
 496                 w_l = w;
 497         }
 498 }
 499
 500 static int unuse_one_window(struct packed_git *current)
 501 {
 502         struct packed_git *p, *lru_p = NULL;
 503         struct pack_window *lru_w = NULL, *lru_l = NULL;
 504
 505         if (current)
 506                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 507         for (p = packed_git; p; p = p->next)
 508                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 509         if (lru_p) {
 510                 munmap(lru_w->base, lru_w->len);
 511                 pack_mapped -= lru_w->len;
 512                 if (lru_l)
 513                         lru_l->next = lru_w->next;
 514                 else {
 515                         lru_p->windows = lru_w->next;
 516                         if (!lru_p->windows && lru_p != current) {
 517                                 close(lru_p->pack_fd);
 518                                 lru_p->pack_fd = -1;
 519                         }
 520                 }
 521                 free(lru_w);
 522                 pack_open_windows--;
 523                 return 1;
 524         }
 525         return 0;
 526 }
 527
 528 void release_pack_memory(size_t need)
 529 {
 530         size_t cur = pack_mapped;
 531         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 532                 ; /* nothing */
 533 }
 534
 535 void unuse_pack(struct pack_window **w_cursor)
 536 {
 537         struct pack_window *w = *w_cursor;
 538         if (w) {
 539                 w->inuse_cnt--;
 540                 *w_cursor = NULL;
 541         }
 542 }
 543
 544 static void open_packed_git(struct packed_git *p)
 545 {
 546         struct stat st;
 547         struct pack_header hdr;
 548         unsigned char sha1[20];
 549         unsigned char *idx_sha1;
 550         long fd_flag;
 551
 552         p->pack_fd = open(p->pack_name, O_RDONLY);
 553         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 554                 die("packfile %s cannot be opened", p->pack_name);
 555
 556         /* If we created the struct before we had the pack we lack size. */
 557         if (!p->pack_size) {
 558                 if (!S_ISREG(st.st_mode))
 559                         die("packfile %s not a regular file", p->pack_name);
 560                 p->pack_size = st.st_size;
 561         } else if (p->pack_size != st.st_size)
 562                 die("packfile %s size changed", p->pack_name);
 563
 564         /* We leave these file descriptors open with sliding mmap;
 565          * there is no point keeping them open across exec(), though.
 566          */
 567         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 568         if (fd_flag < 0)
 569                 die("cannot determine file descriptor flags");
 570         fd_flag |= FD_CLOEXEC;
 571         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 572                 die("cannot set FD_CLOEXEC");
 573
 574         /* Verify we recognize this pack file format. */
 575         read_or_die(p->pack_fd, &hdr, sizeof(hdr));
 576         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 577                 die("file %s is not a GIT packfile", p->pack_name);
 578         if (!pack_version_ok(hdr.hdr_version))
 579                 die("packfile %s is version %u and not supported"
 580                         " (try upgrading GIT to a newer version)",
 581                         p->pack_name, ntohl(hdr.hdr_version));
 582
 583         /* Verify the pack matches its index. */
 584         if (num_packed_objects(p) != ntohl(hdr.hdr_entries))
 585                 die("packfile %s claims to have %u objects"
 586                         " while index size indicates %u objects",
 587                         p->pack_name, ntohl(hdr.hdr_entries),
 588                         num_packed_objects(p));
 589         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 590                 die("end of packfile %s is unavailable", p->pack_name);
 591         read_or_die(p->pack_fd, sha1, sizeof(sha1));
 592         idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
 593         if (hashcmp(sha1, idx_sha1))
 594                 die("packfile %s does not match index", p->pack_name);
 595 }
 596
 597 static int in_window(struct pack_window *win, unsigned long offset)
 598 {
 599         /* We must promise at least 20 bytes (one hash) after the
 600          * offset is available from this window, otherwise the offset
 601          * is not actually in this window and a different window (which
 602          * has that one hash excess) must be used.  This is to support
 603          * the object header and delta base parsing routines below.
 604          */
 605         off_t win_off = win->offset;
 606         return win_off <= offset
 607                 && (offset + 20) <= (win_off + win->len);
 608 }
 609
 610 unsigned char* use_pack(struct packed_git *p,
 611                 struct pack_window **w_cursor,
 612                 unsigned long offset,
 613                 unsigned int *left)
 614 {
 615         struct pack_window *win = *w_cursor;
 616
 617         if (p->pack_fd == -1)
 618                 open_packed_git(p);
 619
 620         /* Since packfiles end in a hash of their content and its
 621          * pointless to ask for an offset into the middle of that
 622          * hash, and the in_window function above wouldn't match
 623          * don't allow an offset too close to the end of the file.
 624          */
 625         if (offset > (p->pack_size - 20))
 626                 die("offset beyond end of packfile (truncated pack?)");
 627
 628         if (!win || !in_window(win, offset)) {
 629                 if (win)
 630                         win->inuse_cnt--;
 631                 for (win = p->windows; win; win = win->next) {
 632                         if (in_window(win, offset))
 633                                 break;
 634                 }
 635                 if (!win) {
 636                         if (!page_size)
 637                                 page_size = getpagesize();
 638                         win = xcalloc(1, sizeof(*win));
 639                         win->offset = (offset / page_size) * page_size;
 640                         win->len = p->pack_size - win->offset;
 641                         if (win->len > packed_git_window_size)
 642                                 win->len = packed_git_window_size;
 643                         pack_mapped += win->len;
 644                         while (packed_git_limit < pack_mapped
 645                                 && unuse_one_window(p))
 646                                 ; /* nothing */
 647                         win->base = xmmap(NULL, win->len,
 648                                 PROT_READ, MAP_PRIVATE,
 649                                 p->pack_fd, win->offset);
 650                         if (win->base == MAP_FAILED)
 651                                 die("packfile %s cannot be mapped: %s",
 652                                         p->pack_name,
 653                                         strerror(errno));
 654                         pack_mmap_calls++;
 655                         pack_open_windows++;
 656                         if (pack_mapped > peak_pack_mapped)
 657                                 peak_pack_mapped = pack_mapped;
 658                         if (pack_open_windows > peak_pack_open_windows)
 659                                 peak_pack_open_windows = pack_open_windows;
 660                         win->next = p->windows;
 661                         p->windows = win;
 662                 }
 663         }
 664         if (win != *w_cursor) {
 665                 win->last_used = pack_used_ctr++;
 666                 win->inuse_cnt++;
 667                 *w_cursor = win;
 668         }
 669         offset -= win->offset;
 670         if (left)
 671                 *left = win->len - offset;
 672         return win->base + offset;
 673 }
 674
 675 struct packed_git *add_packed_git(char *path, int path_len, int local)
 676 {
 677         struct stat st;
 678         struct packed_git *p;
 679         unsigned long idx_size;
 680         void *idx_map;
 681         unsigned char sha1[20];
 682
 683         if (check_packed_git_idx(path, &idx_size, &idx_map))
 684                 return NULL;
 685
 686         /* do we have a corresponding .pack file? */
 687         strcpy(path + path_len - 4, ".pack");
 688         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 689                 munmap(idx_map, idx_size);
 690                 return NULL;
 691         }
 692         /* ok, it looks sane as far as we can check without
 693          * actually mapping the pack file.
 694          */
 695         p = xmalloc(sizeof(*p) + path_len + 2);
 696         strcpy(p->pack_name, path);
 697         p->index_size = idx_size;
 698         p->pack_size = st.st_size;
 699         p->index_base = idx_map;
 700         p->next = NULL;
 701         p->windows = NULL;
 702         p->pack_fd = -1;
 703         p->pack_local = local;
 704         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 705                 hashcpy(p->sha1, sha1);
 706         return p;
 707 }
 708
 709 struct packed_git *parse_pack_index(unsigned char *sha1)
 710 {
 711         char *path = sha1_pack_index_name(sha1);
 712         return parse_pack_index_file(sha1, path);
 713 }
 714
 715 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 716 {
 717         struct packed_git *p;
 718         unsigned long idx_size;
 719         void *idx_map;
 720         char *path;
 721
 722         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 723                 return NULL;
 724
 725         path = sha1_pack_name(sha1);
 726
 727         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 728         strcpy(p->pack_name, path);
 729         p->index_size = idx_size;
 730         p->pack_size = 0;
 731         p->index_base = idx_map;
 732         p->next = NULL;
 733         p->windows = NULL;
 734         p->pack_fd = -1;
 735         hashcpy(p->sha1, sha1);
 736         return p;
 737 }
 738
 739 void install_packed_git(struct packed_git *pack)
 740 {
 741         pack->next = packed_git;
 742         packed_git = pack;
 743 }
 744
 745 static void prepare_packed_git_one(char *objdir, int local)
 746 {
 747         char path[PATH_MAX];
 748         int len;
 749         DIR *dir;
 750         struct dirent *de;
 751
 752         sprintf(path, "%s/pack", objdir);
 753         len = strlen(path);
 754         dir = opendir(path);
 755         if (!dir) {
 756                 if (errno != ENOENT)
 757                         error("unable to open object pack directory: %s: %s",
 758                               path, strerror(errno));
 759                 return;
 760         }
 761         path[len++] = '/';
 762         while ((de = readdir(dir)) != NULL) {
 763                 int namelen = strlen(de->d_name);
 764                 struct packed_git *p;
 765
 766                 if (!has_extension(de->d_name, ".idx"))
 767                         continue;
 768
 769                 /* we have .idx.  Is it a file we can map? */
 770                 strcpy(path + len, de->d_name);
 771                 for (p = packed_git; p; p = p->next) {
 772                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 773                                 break;
 774                 }
 775                 if (p)
 776                         continue;
 777                 p = add_packed_git(path, len + namelen, local);
 778                 if (!p)
 779                         continue;
 780                 p->next = packed_git;
 781                 packed_git = p;
 782         }
 783         closedir(dir);
 784 }
 785
 786 static int prepare_packed_git_run_once = 0;
 787 void prepare_packed_git(void)
 788 {
 789         struct alternate_object_database *alt;
 790
 791         if (prepare_packed_git_run_once)
 792                 return;
 793         prepare_packed_git_one(get_object_directory(), 1);
 794         prepare_alt_odb();
 795         for (alt = alt_odb_list; alt; alt = alt->next) {
 796                 alt->name[-1] = 0;
 797                 prepare_packed_git_one(alt->base, 0);
 798                 alt->name[-1] = '/';
 799         }
 800         prepare_packed_git_run_once = 1;
 801 }
 802
 803 void reprepare_packed_git(void)
 804 {
 805         prepare_packed_git_run_once = 0;
 806         prepare_packed_git();
 807 }
 808
 809 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 810 {
 811         unsigned char real_sha1[20];
 812         hash_sha1_file(map, size, type, real_sha1);
 813         return hashcmp(sha1, real_sha1) ? -1 : 0;
 814 }
 815
 816 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 817 {
 818         struct stat st;
 819         void *map;
 820         int fd;
 821         char *filename = find_sha1_file(sha1, &st);
 822
 823         if (!filename) {
 824                 return NULL;
 825         }
 826
 827         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 828         if (fd < 0) {
 829                 /* See if it works without O_NOATIME */
 830                 switch (sha1_file_open_flag) {
 831                 default:
 832                         fd = open(filename, O_RDONLY);
 833                         if (fd >= 0)
 834                                 break;
 835                 /* Fallthrough */
 836                 case 0:
 837                         return NULL;
 838                 }
 839
 840                 /* If it failed once, it will probably fail again.
 841                  * Stop using O_NOATIME
 842                  */
 843                 sha1_file_open_flag = 0;
 844         }
 845         map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 846         close(fd);
 847         *size = st.st_size;
 848         return map;
 849 }
 850
 851 int legacy_loose_object(unsigned char *map)
 852 {
 853         unsigned int word;
 854
 855         /*
 856          * Is it a zlib-compressed buffer? If so, the first byte
 857          * must be 0x78 (15-bit window size, deflated), and the
 858          * first 16-bit word is evenly divisible by 31
 859          */
 860         word = (map[0] << 8) + map[1];
 861         if (map[0] == 0x78 && !(word % 31))
 862                 return 1;
 863         else
 864                 return 0;
 865 }
 866
 867 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 868 {
 869         unsigned shift;
 870         unsigned char c;
 871         unsigned long size;
 872         unsigned long used = 0;
 873
 874         c = buf[used++];
 875         *type = (c >> 4) & 7;
 876         size = c & 15;
 877         shift = 4;
 878         while (c & 0x80) {
 879                 if (len <= used)
 880                         return 0;
 881                 if (sizeof(long) * 8 <= shift)
 882                         return 0;
 883                 c = buf[used++];
 884                 size += (c & 0x7f) << shift;
 885                 shift += 7;
 886         }
 887         *sizep = size;
 888         return used;
 889 }
 890
 891 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 892 {
 893         unsigned long size, used;
 894         static const char valid_loose_object_type[8] = {
 895                 0, /* OBJ_EXT */
 896                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 897                 0, /* "delta" and others are invalid in a loose object */
 898         };
 899         enum object_type type;
 900
 901         /* Get the data stream */
 902         memset(stream, 0, sizeof(*stream));
 903         stream->next_in = map;
 904         stream->avail_in = mapsize;
 905         stream->next_out = buffer;
 906         stream->avail_out = bufsiz;
 907
 908         if (legacy_loose_object(map)) {
 909                 inflateInit(stream);
 910                 return inflate(stream, 0);
 911         }
 912
 913         used = unpack_object_header_gently(map, mapsize, &type, &size);
 914         if (!used || !valid_loose_object_type[type])
 915                 return -1;
 916         map += used;
 917         mapsize -= used;
 918
 919         /* Set up the stream for the rest.. */
 920         stream->next_in = map;
 921         stream->avail_in = mapsize;
 922         inflateInit(stream);
 923
 924         /* And generate the fake traditional header */
 925         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 926                                          type_names[type], size);
 927         return 0;
 928 }
 929
 930 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 931 {
 932         int bytes = strlen(buffer) + 1;
 933         unsigned char *buf = xmalloc(1+size);
 934         unsigned long n;
 935
 936         n = stream->total_out - bytes;
 937         if (n > size)
 938                 n = size;
 939         memcpy(buf, (char *) buffer + bytes, n);
 940         bytes = n;
 941         if (bytes < size) {
 942                 stream->next_out = buf + bytes;
 943                 stream->avail_out = size - bytes;
 944                 while (inflate(stream, Z_FINISH) == Z_OK)
 945                         /* nothing */;
 946         }
 947         buf[size] = 0;
 948         inflateEnd(stream);
 949         return buf;
 950 }
 951
 952 /*
 953  * We used to just use "sscanf()", but that's actually way
 954  * too permissive for what we want to check. So do an anal
 955  * object header parse by hand.
 956  */
 957 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 958 {
 959         int i;
 960         unsigned long size;
 961
 962         /*
 963          * The type can be at most ten bytes (including the
 964          * terminating '\0' that we add), and is followed by
 965          * a space.
 966          */
 967         i = 10;
 968         for (;;) {
 969                 char c = *hdr++;
 970                 if (c == ' ')
 971                         break;
 972                 if (!--i)
 973                         return -1;
 974                 *type++ = c;
 975         }
 976         *type = 0;
 977
 978         /*
 979          * The length must follow immediately, and be in canonical
 980          * decimal format (ie "010" is not valid).
 981          */
 982         size = *hdr++ - '0';
 983         if (size > 9)
 984                 return -1;
 985         if (size) {
 986                 for (;;) {
 987                         unsigned long c = *hdr - '0';
 988                         if (c > 9)
 989                                 break;
 990                         hdr++;
 991                         size = size * 10 + c;
 992                 }
 993         }
 994         *sizep = size;
 995
 996         /*
 997          * The length must be followed by a zero byte
 998          */
 999         return *hdr ? -1 : 0;
1000 }
1001
1002 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
1003 {
1004         int ret;
1005         z_stream stream;
1006         char hdr[8192];
1007
1008         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1009         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
1010                 return NULL;
1011
1012         return unpack_sha1_rest(&stream, hdr, *size);
1013 }
1014
1015 static unsigned long get_delta_base(struct packed_git *p,
1016                                     struct pack_window **w_curs,
1017                                     unsigned long offset,
1018                                     enum object_type kind,
1019                                     unsigned long delta_obj_offset,
1020                                     unsigned long *base_obj_offset)
1021 {
1022         unsigned char *base_info = use_pack(p, w_curs, offset, NULL);
1023         unsigned long base_offset;
1024
1025         /* use_pack() assured us we have [base_info, base_info + 20)
1026          * as a range that we can look at without walking off the
1027          * end of the mapped window.  Its actually the hash size
1028          * that is assured.  An OFS_DELTA longer than the hash size
1029          * is stupid, as then a REF_DELTA would be smaller to store.
1030          */
1031         if (kind == OBJ_OFS_DELTA) {
1032                 unsigned used = 0;
1033                 unsigned char c = base_info[used++];
1034                 base_offset = c & 127;
1035                 while (c & 128) {
1036                         base_offset += 1;
1037                         if (!base_offset || base_offset & ~(~0UL >> 7))
1038                                 die("offset value overflow for delta base object");
1039                         c = base_info[used++];
1040                         base_offset = (base_offset << 7) + (c & 127);
1041                 }
1042                 base_offset = delta_obj_offset - base_offset;
1043                 if (base_offset >= delta_obj_offset)
1044                         die("delta base offset out of bound");
1045                 offset += used;
1046         } else if (kind == OBJ_REF_DELTA) {
1047                 /* The base entry _must_ be in the same pack */
1048                 base_offset = find_pack_entry_one(base_info, p);
1049                 if (!base_offset)
1050                         die("failed to find delta-pack base object %s",
1051                                 sha1_to_hex(base_info));
1052                 offset += 20;
1053         } else
1054                 die("I am totally screwed");
1055         *base_obj_offset = base_offset;
1056         return offset;
1057 }
1058
1059 /* forward declaration for a mutually recursive function */
1060 static int packed_object_info(struct packed_git *p, unsigned long offset,
1061                               char *type, unsigned long *sizep);
1062
1063 static int packed_delta_info(struct packed_git *p,
1064                              struct pack_window **w_curs,
1065                              unsigned long offset,
1066                              enum object_type kind,
1067                              unsigned long obj_offset,
1068                              char *type,
1069                              unsigned long *sizep)
1070 {
1071         unsigned long base_offset;
1072
1073         offset = get_delta_base(p, w_curs, offset, kind,
1074                 obj_offset, &base_offset);
1075
1076         /* We choose to only get the type of the base object and
1077          * ignore potentially corrupt pack file that expects the delta
1078          * based on a base with a wrong size.  This saves tons of
1079          * inflate() calls.
1080          */
1081         if (packed_object_info(p, base_offset, type, NULL))
1082                 die("cannot get info for delta-pack base");
1083
1084         if (sizep) {
1085                 const unsigned char *data;
1086                 unsigned char delta_head[20], *in;
1087                 unsigned long result_size;
1088                 z_stream stream;
1089                 int st;
1090
1091                 memset(&stream, 0, sizeof(stream));
1092                 stream.next_out = delta_head;
1093                 stream.avail_out = sizeof(delta_head);
1094
1095                 inflateInit(&stream);
1096                 do {
1097                         in = use_pack(p, w_curs, offset, &stream.avail_in);
1098                         stream.next_in = in;
1099                         st = inflate(&stream, Z_FINISH);
1100                         offset += stream.next_in - in;
1101                 } while ((st == Z_OK || st == Z_BUF_ERROR)
1102                         && stream.total_out < sizeof(delta_head));
1103                 inflateEnd(&stream);
1104                 if ((st != Z_STREAM_END) &&
1105                     stream.total_out != sizeof(delta_head))
1106                         die("delta data unpack-initial failed");
1107
1108                 /* Examine the initial part of the delta to figure out
1109                  * the result size.
1110                  */
1111                 data = delta_head;
1112
1113                 /* ignore base size */
1114                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1115
1116                 /* Read the result size */
1117                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1118                 *sizep = result_size;
1119         }
1120         return 0;
1121 }
1122
1123 static unsigned long unpack_object_header(struct packed_git *p,
1124                 struct pack_window **w_curs,
1125                 unsigned long offset,
1126                 enum object_type *type,
1127                 unsigned long *sizep)
1128 {
1129         unsigned char *base;
1130         unsigned int left;
1131         unsigned long used;
1132
1133         /* use_pack() assures us we have [base, base + 20) available
1134          * as a range that we can look at at.  (Its actually the hash
1135          * size that is assurred.)  With our object header encoding
1136          * the maximum deflated object size is 2^137, which is just
1137          * insane, so we know won't exceed what we have been given.
1138          */
1139         base = use_pack(p, w_curs, offset, &left);
1140         used = unpack_object_header_gently(base, left, type, sizep);
1141         if (!used)
1142                 die("object offset outside of pack file");
1143
1144         return offset + used;
1145 }
1146
1147 void packed_object_info_detail(struct packed_git *p,
1148                                unsigned long offset,
1149                                char *type,
1150                                unsigned long *size,
1151                                unsigned long *store_size,
1152                                unsigned int *delta_chain_length,
1153                                unsigned char *base_sha1)
1154 {
1155         struct pack_window *w_curs = NULL;
1156         unsigned long obj_offset, val;
1157         unsigned char *next_sha1;
1158         enum object_type kind;
1159
1160         *delta_chain_length = 0;
1161         obj_offset = offset;
1162         offset = unpack_object_header(p, &w_curs, offset, &kind, size);
1163
1164         for (;;) {
1165                 switch (kind) {
1166                 default:
1167                         die("pack %s contains unknown object type %d",
1168                             p->pack_name, kind);
1169                 case OBJ_COMMIT:
1170                 case OBJ_TREE:
1171                 case OBJ_BLOB:
1172                 case OBJ_TAG:
1173                         strcpy(type, type_names[kind]);
1174                         *store_size = 0; /* notyet */
1175                         unuse_pack(&w_curs);
1176                         return;
1177                 case OBJ_OFS_DELTA:
1178                         get_delta_base(p, &w_curs, offset, kind,
1179                                 obj_offset, &offset);
1180                         if (*delta_chain_length == 0) {
1181                                 /* TODO: find base_sha1 as pointed by offset */
1182                         }
1183                         break;
1184                 case OBJ_REF_DELTA:
1185                         next_sha1 = use_pack(p, &w_curs, offset, NULL);
1186                         if (*delta_chain_length == 0)
1187                                 hashcpy(base_sha1, next_sha1);
1188                         offset = find_pack_entry_one(next_sha1, p);
1189                         break;
1190                 }
1191                 obj_offset = offset;
1192                 offset = unpack_object_header(p, &w_curs, offset, &kind, &val);
1193                 (*delta_chain_length)++;
1194         }
1195 }
1196
1197 static int packed_object_info(struct packed_git *p, unsigned long offset,
1198                               char *type, unsigned long *sizep)
1199 {
1200         struct pack_window *w_curs = NULL;
1201         unsigned long size, obj_offset = offset;
1202         enum object_type kind;
1203         int r;
1204
1205         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1206
1207         switch (kind) {
1208         case OBJ_OFS_DELTA:
1209         case OBJ_REF_DELTA:
1210                 r = packed_delta_info(p, &w_curs, offset, kind,
1211                         obj_offset, type, sizep);
1212                 unuse_pack(&w_curs);
1213                 return r;
1214         case OBJ_COMMIT:
1215         case OBJ_TREE:
1216         case OBJ_BLOB:
1217         case OBJ_TAG:
1218                 strcpy(type, type_names[kind]);
1219                 unuse_pack(&w_curs);
1220                 break;
1221         default:
1222                 die("pack %s contains unknown object type %d",
1223                     p->pack_name, kind);
1224         }
1225         if (sizep)
1226                 *sizep = size;
1227         return 0;
1228 }
1229
1230 static void *unpack_compressed_entry(struct packed_git *p,
1231                                     struct pack_window **w_curs,
1232                                     unsigned long offset,
1233                                     unsigned long size)
1234 {
1235         int st;
1236         z_stream stream;
1237         unsigned char *buffer, *in;
1238
1239         buffer = xmalloc(size + 1);
1240         buffer[size] = 0;
1241         memset(&stream, 0, sizeof(stream));
1242         stream.next_out = buffer;
1243         stream.avail_out = size;
1244
1245         inflateInit(&stream);
1246         do {
1247                 in = use_pack(p, w_curs, offset, &stream.avail_in);
1248                 stream.next_in = in;
1249                 st = inflate(&stream, Z_FINISH);
1250                 offset += stream.next_in - in;
1251         } while (st == Z_OK || st == Z_BUF_ERROR);
1252         inflateEnd(&stream);
1253         if ((st != Z_STREAM_END) || stream.total_out != size) {
1254                 free(buffer);
1255                 return NULL;
1256         }
1257
1258         return buffer;
1259 }
1260
1261 static void *unpack_delta_entry(struct packed_git *p,
1262                                 struct pack_window **w_curs,
1263                                 unsigned long offset,
1264                                 unsigned long delta_size,
1265                                 enum object_type kind,
1266                                 unsigned long obj_offset,
1267                                 char *type,
1268                                 unsigned long *sizep)
1269 {
1270         void *delta_data, *result, *base;
1271         unsigned long result_size, base_size, base_offset;
1272
1273         offset = get_delta_base(p, w_curs, offset, kind,
1274                 obj_offset, &base_offset);
1275         base = unpack_entry(p, base_offset, type, &base_size);
1276         if (!base)
1277                 die("failed to read delta base object at %lu from %s",
1278                     base_offset, p->pack_name);
1279
1280         delta_data = unpack_compressed_entry(p, w_curs, offset, delta_size);
1281         result = patch_delta(base, base_size,
1282                              delta_data, delta_size,
1283                              &result_size);
1284         if (!result)
1285                 die("failed to apply delta");
1286         free(delta_data);
1287         free(base);
1288         *sizep = result_size;
1289         return result;
1290 }
1291
1292 void *unpack_entry(struct packed_git *p, unsigned long offset,
1293                           char *type, unsigned long *sizep)
1294 {
1295         struct pack_window *w_curs = NULL;
1296         unsigned long size, obj_offset = offset;
1297         enum object_type kind;
1298         void *retval;
1299
1300         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1301         switch (kind) {
1302         case OBJ_OFS_DELTA:
1303         case OBJ_REF_DELTA:
1304                 retval = unpack_delta_entry(p, &w_curs, offset, size,
1305                         kind, obj_offset, type, sizep);
1306                 break;
1307         case OBJ_COMMIT:
1308         case OBJ_TREE:
1309         case OBJ_BLOB:
1310         case OBJ_TAG:
1311                 strcpy(type, type_names[kind]);
1312                 *sizep = size;
1313                 retval = unpack_compressed_entry(p, &w_curs, offset, size);
1314                 break;
1315         default:
1316                 die("unknown object type %i in %s", kind, p->pack_name);
1317         }
1318         unuse_pack(&w_curs);
1319         return retval;
1320 }
1321
1322 int num_packed_objects(const struct packed_git *p)
1323 {
1324         /* See check_packed_git_idx() */
1325         return (p->index_size - 20 - 20 - 4*256) / 24;
1326 }
1327
1328 int nth_packed_object_sha1(const struct packed_git *p, int n,
1329                            unsigned char* sha1)
1330 {
1331         void *index = p->index_base + 256;
1332         if (n < 0 || num_packed_objects(p) <= n)
1333                 return -1;
1334         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1335         return 0;
1336 }
1337
1338 unsigned long find_pack_entry_one(const unsigned char *sha1,
1339                                   struct packed_git *p)
1340 {
1341         unsigned int *level1_ofs = p->index_base;
1342         int hi = ntohl(level1_ofs[*sha1]);
1343         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1344         void *index = p->index_base + 256;
1345
1346         do {
1347                 int mi = (lo + hi) / 2;
1348                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1349                 if (!cmp)
1350                         return ntohl(*((unsigned int *) ((char *) index + (24 * mi))));
1351                 if (cmp > 0)
1352                         hi = mi;
1353                 else
1354                         lo = mi+1;
1355         } while (lo < hi);
1356         return 0;
1357 }
1358
1359 static int matches_pack_name(struct packed_git *p, const char *ig)
1360 {
1361         const char *last_c, *c;
1362
1363         if (!strcmp(p->pack_name, ig))
1364                 return 0;
1365
1366         for (c = p->pack_name, last_c = c; *c;)
1367                 if (*c == '/')
1368                         last_c = ++c;
1369                 else
1370                         ++c;
1371         if (!strcmp(last_c, ig))
1372                 return 0;
1373
1374         return 1;
1375 }
1376
1377 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1378 {
1379         struct packed_git *p;
1380         unsigned long offset;
1381
1382         prepare_packed_git();
1383
1384         for (p = packed_git; p; p = p->next) {
1385                 if (ignore_packed) {
1386                         const char **ig;
1387                         for (ig = ignore_packed; *ig; ig++)
1388                                 if (!matches_pack_name(p, *ig))
1389                                         break;
1390                         if (*ig)
1391                                 continue;
1392                 }
1393                 offset = find_pack_entry_one(sha1, p);
1394                 if (offset) {
1395                         e->offset = offset;
1396                         e->p = p;
1397                         hashcpy(e->sha1, sha1);
1398                         return 1;
1399                 }
1400         }
1401         return 0;
1402 }
1403
1404 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1405                                   struct packed_git *packs)
1406 {
1407         struct packed_git *p;
1408
1409         for (p = packs; p; p = p->next) {
1410                 if (find_pack_entry_one(sha1, p))
1411                         return p;
1412         }
1413         return NULL;
1414
1415 }
1416
1417 static int sha1_loose_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1418 {
1419         int status;
1420         unsigned long mapsize, size;
1421         void *map;
1422         z_stream stream;
1423         char hdr[128];
1424
1425         map = map_sha1_file(sha1, &mapsize);
1426         if (!map)
1427                 return error("unable to find %s", sha1_to_hex(sha1));
1428         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1429                 status = error("unable to unpack %s header",
1430                                sha1_to_hex(sha1));
1431         if (parse_sha1_header(hdr, type, &size) < 0)
1432                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1433         else {
1434                 status = 0;
1435                 if (sizep)
1436                         *sizep = size;
1437         }
1438         inflateEnd(&stream);
1439         munmap(map, mapsize);
1440         return status;
1441 }
1442
1443 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1444 {
1445         struct pack_entry e;
1446
1447         if (!find_pack_entry(sha1, &e, NULL)) {
1448                 reprepare_packed_git();
1449                 if (!find_pack_entry(sha1, &e, NULL))
1450                         return sha1_loose_object_info(sha1, type, sizep);
1451         }
1452         return packed_object_info(e.p, e.offset, type, sizep);
1453 }
1454
1455 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1456 {
1457         struct pack_entry e;
1458
1459         if (!find_pack_entry(sha1, &e, NULL)) {
1460                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1461                 return NULL;
1462         }
1463         return unpack_entry(e.p, e.offset, type, size);
1464 }
1465
1466 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1467 {
1468         unsigned long mapsize;
1469         void *map, *buf;
1470         struct pack_entry e;
1471
1472         if (find_pack_entry(sha1, &e, NULL))
1473                 return read_packed_sha1(sha1, type, size);
1474         map = map_sha1_file(sha1, &mapsize);
1475         if (map) {
1476                 buf = unpack_sha1_file(map, mapsize, type, size);
1477                 munmap(map, mapsize);
1478                 return buf;
1479         }
1480         reprepare_packed_git();
1481         if (find_pack_entry(sha1, &e, NULL))
1482                 return read_packed_sha1(sha1, type, size);
1483         return NULL;
1484 }
1485
1486 void *read_object_with_reference(const unsigned char *sha1,
1487                                  const char *required_type,
1488                                  unsigned long *size,
1489                                  unsigned char *actual_sha1_return)
1490 {
1491         char type[20];
1492         void *buffer;
1493         unsigned long isize;
1494         unsigned char actual_sha1[20];
1495
1496         hashcpy(actual_sha1, sha1);
1497         while (1) {
1498                 int ref_length = -1;
1499                 const char *ref_type = NULL;
1500
1501                 buffer = read_sha1_file(actual_sha1, type, &isize);
1502                 if (!buffer)
1503                         return NULL;
1504                 if (!strcmp(type, required_type)) {
1505                         *size = isize;
1506                         if (actual_sha1_return)
1507                                 hashcpy(actual_sha1_return, actual_sha1);
1508                         return buffer;
1509                 }
1510                 /* Handle references */
1511                 else if (!strcmp(type, commit_type))
1512                         ref_type = "tree ";
1513                 else if (!strcmp(type, tag_type))
1514                         ref_type = "object ";
1515                 else {
1516                         free(buffer);
1517                         return NULL;
1518                 }
1519                 ref_length = strlen(ref_type);
1520
1521                 if (memcmp(buffer, ref_type, ref_length) ||
1522                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1523                         free(buffer);
1524                         return NULL;
1525                 }
1526                 free(buffer);
1527                 /* Now we have the ID of the referred-to object in
1528                  * actual_sha1.  Check again. */
1529         }
1530 }
1531
1532 static void write_sha1_file_prepare(void *buf, unsigned long len,
1533                                     const char *type, unsigned char *sha1,
1534                                     unsigned char *hdr, int *hdrlen)
1535 {
1536         SHA_CTX c;
1537
1538         /* Generate the header */
1539         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1540
1541         /* Sha1.. */
1542         SHA1_Init(&c);
1543         SHA1_Update(&c, hdr, *hdrlen);
1544         SHA1_Update(&c, buf, len);
1545         SHA1_Final(sha1, &c);
1546 }
1547
1548 /*
1549  * Link the tempfile to the final place, possibly creating the
1550  * last directory level as you do so.
1551  *
1552  * Returns the errno on failure, 0 on success.
1553  */
1554 static int link_temp_to_file(const char *tmpfile, const char *filename)
1555 {
1556         int ret;
1557         char *dir;
1558
1559         if (!link(tmpfile, filename))
1560                 return 0;
1561
1562         /*
1563          * Try to mkdir the last path component if that failed.
1564          *
1565          * Re-try the "link()" regardless of whether the mkdir
1566          * succeeds, since a race might mean that somebody
1567          * else succeeded.
1568          */
1569         ret = errno;
1570         dir = strrchr(filename, '/');
1571         if (dir) {
1572                 *dir = 0;
1573                 if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1574                         *dir = '/';
1575                         return -2;
1576                 }
1577                 *dir = '/';
1578                 if (!link(tmpfile, filename))
1579                         return 0;
1580                 ret = errno;
1581         }
1582         return ret;
1583 }
1584
1585 /*
1586  * Move the just written object into its final resting place
1587  */
1588 int move_temp_to_file(const char *tmpfile, const char *filename)
1589 {
1590         int ret = link_temp_to_file(tmpfile, filename);
1591
1592         /*
1593          * Coda hack - coda doesn't like cross-directory links,
1594          * so we fall back to a rename, which will mean that it
1595          * won't be able to check collisions, but that's not a
1596          * big deal.
1597          *
1598          * The same holds for FAT formatted media.
1599          *
1600          * When this succeeds, we just return 0. We have nothing
1601          * left to unlink.
1602          */
1603         if (ret && ret != EEXIST) {
1604                 if (!rename(tmpfile, filename))
1605                         return 0;
1606                 ret = errno;
1607         }
1608         unlink(tmpfile);
1609         if (ret) {
1610                 if (ret != EEXIST) {
1611                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1612                 }
1613                 /* FIXME!!! Collision check here ? */
1614         }
1615
1616         return 0;
1617 }
1618
1619 static int write_buffer(int fd, const void *buf, size_t len)
1620 {
1621         ssize_t size;
1622
1623         if (!len)
1624                 return 0;
1625         size = write_in_full(fd, buf, len);
1626         if (!size)
1627                 return error("file write: disk full");
1628         if (size < 0)
1629                 return error("file write error (%s)", strerror(errno));
1630         return 0;
1631 }
1632
1633 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1634 {
1635         int hdr_len;
1636         unsigned char c;
1637
1638         c = (type << 4) | (len & 15);
1639         len >>= 4;
1640         hdr_len = 1;
1641         while (len) {
1642                 *hdr++ = c | 0x80;
1643                 hdr_len++;
1644                 c = (len & 0x7f);
1645                 len >>= 7;
1646         }
1647         *hdr = c;
1648         return hdr_len;
1649 }
1650
1651 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1652 {
1653         int obj_type, hdr;
1654
1655         if (use_legacy_headers) {
1656                 while (deflate(stream, 0) == Z_OK)
1657                         /* nothing */;
1658                 return;
1659         }
1660         if (!strcmp(type, blob_type))
1661                 obj_type = OBJ_BLOB;
1662         else if (!strcmp(type, tree_type))
1663                 obj_type = OBJ_TREE;
1664         else if (!strcmp(type, commit_type))
1665                 obj_type = OBJ_COMMIT;
1666         else if (!strcmp(type, tag_type))
1667                 obj_type = OBJ_TAG;
1668         else
1669                 die("trying to generate bogus object of type '%s'", type);
1670         hdr = write_binary_header(stream->next_out, obj_type, len);
1671         stream->total_out = hdr;
1672         stream->next_out += hdr;
1673         stream->avail_out -= hdr;
1674 }
1675
1676 int hash_sha1_file(void *buf, unsigned long len, const char *type,
1677                    unsigned char *sha1)
1678 {
1679         unsigned char hdr[50];
1680         int hdrlen;
1681         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1682         return 0;
1683 }
1684
1685 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1686 {
1687         int size;
1688         unsigned char *compressed;
1689         z_stream stream;
1690         unsigned char sha1[20];
1691         char *filename;
1692         static char tmpfile[PATH_MAX];
1693         unsigned char hdr[50];
1694         int fd, hdrlen;
1695
1696         /* Normally if we have it in the pack then we do not bother writing
1697          * it out into .git/objects/??/?{38} file.
1698          */
1699         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1700         filename = sha1_file_name(sha1);
1701         if (returnsha1)
1702                 hashcpy(returnsha1, sha1);
1703         if (has_sha1_file(sha1))
1704                 return 0;
1705         fd = open(filename, O_RDONLY);
1706         if (fd >= 0) {
1707                 /*
1708                  * FIXME!!! We might do collision checking here, but we'd
1709                  * need to uncompress the old file and check it. Later.
1710                  */
1711                 close(fd);
1712                 return 0;
1713         }
1714
1715         if (errno != ENOENT) {
1716                 return error("sha1 file %s: %s\n", filename, strerror(errno));
1717         }
1718
1719         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1720
1721         fd = mkstemp(tmpfile);
1722         if (fd < 0) {
1723                 if (errno == EPERM)
1724                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1725                 else
1726                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1727         }
1728
1729         /* Set it up */
1730         memset(&stream, 0, sizeof(stream));
1731         deflateInit(&stream, zlib_compression_level);
1732         size = 8 + deflateBound(&stream, len+hdrlen);
1733         compressed = xmalloc(size);
1734
1735         /* Compress it */
1736         stream.next_out = compressed;
1737         stream.avail_out = size;
1738
1739         /* First header.. */
1740         stream.next_in = hdr;
1741         stream.avail_in = hdrlen;
1742         setup_object_header(&stream, type, len);
1743
1744         /* Then the data itself.. */
1745         stream.next_in = buf;
1746         stream.avail_in = len;
1747         while (deflate(&stream, Z_FINISH) == Z_OK)
1748                 /* nothing */;
1749         deflateEnd(&stream);
1750         size = stream.total_out;
1751
1752         if (write_buffer(fd, compressed, size) < 0)
1753                 die("unable to write sha1 file");
1754         fchmod(fd, 0444);
1755         close(fd);
1756         free(compressed);
1757
1758         return move_temp_to_file(tmpfile, filename);
1759 }
1760
1761 /*
1762  * We need to unpack and recompress the object for writing
1763  * it out to a different file.
1764  */
1765 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1766 {
1767         size_t size;
1768         z_stream stream;
1769         unsigned char *unpacked;
1770         unsigned long len;
1771         char type[20];
1772         char hdr[50];
1773         int hdrlen;
1774         void *buf;
1775
1776         /* need to unpack and recompress it by itself */
1777         unpacked = read_packed_sha1(sha1, type, &len);
1778
1779         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1780
1781         /* Set it up */
1782         memset(&stream, 0, sizeof(stream));
1783         deflateInit(&stream, zlib_compression_level);
1784         size = deflateBound(&stream, len + hdrlen);
1785         buf = xmalloc(size);
1786
1787         /* Compress it */
1788         stream.next_out = buf;
1789         stream.avail_out = size;
1790
1791         /* First header.. */
1792         stream.next_in = (void *)hdr;
1793         stream.avail_in = hdrlen;
1794         while (deflate(&stream, 0) == Z_OK)
1795                 /* nothing */;
1796
1797         /* Then the data itself.. */
1798         stream.next_in = unpacked;
1799         stream.avail_in = len;
1800         while (deflate(&stream, Z_FINISH) == Z_OK)
1801                 /* nothing */;
1802         deflateEnd(&stream);
1803         free(unpacked);
1804
1805         *objsize = stream.total_out;
1806         return buf;
1807 }
1808
1809 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1810 {
1811         int retval;
1812         unsigned long objsize;
1813         void *buf = map_sha1_file(sha1, &objsize);
1814
1815         if (buf) {
1816                 retval = write_buffer(fd, buf, objsize);
1817                 munmap(buf, objsize);
1818                 return retval;
1819         }
1820
1821         buf = repack_object(sha1, &objsize);
1822         retval = write_buffer(fd, buf, objsize);
1823         free(buf);
1824         return retval;
1825 }
1826
1827 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1828                        size_t bufsize, size_t *bufposn)
1829 {
1830         char tmpfile[PATH_MAX];
1831         int local;
1832         z_stream stream;
1833         unsigned char real_sha1[20];
1834         unsigned char discard[4096];
1835         int ret;
1836         SHA_CTX c;
1837
1838         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1839
1840         local = mkstemp(tmpfile);
1841         if (local < 0) {
1842                 if (errno == EPERM)
1843                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1844                 else
1845                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1846         }
1847
1848         memset(&stream, 0, sizeof(stream));
1849
1850         inflateInit(&stream);
1851
1852         SHA1_Init(&c);
1853
1854         do {
1855                 ssize_t size;
1856                 if (*bufposn) {
1857                         stream.avail_in = *bufposn;
1858                         stream.next_in = (unsigned char *) buffer;
1859                         do {
1860                                 stream.next_out = discard;
1861                                 stream.avail_out = sizeof(discard);
1862                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1863                                 SHA1_Update(&c, discard, sizeof(discard) -
1864                                             stream.avail_out);
1865                         } while (stream.avail_in && ret == Z_OK);
1866                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1867                                 die("unable to write sha1 file");
1868                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1869                                 stream.avail_in);
1870                         *bufposn = stream.avail_in;
1871                         if (ret != Z_OK)
1872                                 break;
1873                 }
1874                 size = xread(fd, buffer + *bufposn, bufsize - *bufposn);
1875                 if (size <= 0) {
1876                         close(local);
1877                         unlink(tmpfile);
1878                         if (!size)
1879                                 return error("Connection closed?");
1880                         perror("Reading from connection");
1881                         return -1;
1882                 }
1883                 *bufposn += size;
1884         } while (1);
1885         inflateEnd(&stream);
1886
1887         close(local);
1888         SHA1_Final(real_sha1, &c);
1889         if (ret != Z_STREAM_END) {
1890                 unlink(tmpfile);
1891                 return error("File %s corrupted", sha1_to_hex(sha1));
1892         }
1893         if (hashcmp(sha1, real_sha1)) {
1894                 unlink(tmpfile);
1895                 return error("File %s has bad hash", sha1_to_hex(sha1));
1896         }
1897
1898         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1899 }
1900
1901 int has_pack_index(const unsigned char *sha1)
1902 {
1903         struct stat st;
1904         if (stat(sha1_pack_index_name(sha1), &st))
1905                 return 0;
1906         return 1;
1907 }
1908
1909 int has_pack_file(const unsigned char *sha1)
1910 {
1911         struct stat st;
1912         if (stat(sha1_pack_name(sha1), &st))
1913                 return 0;
1914         return 1;
1915 }
1916
1917 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
1918 {
1919         struct pack_entry e;
1920         return find_pack_entry(sha1, &e, ignore_packed);
1921 }
1922
1923 int has_sha1_file(const unsigned char *sha1)
1924 {
1925         struct stat st;
1926         struct pack_entry e;
1927
1928         if (find_pack_entry(sha1, &e, NULL))
1929                 return 1;
1930         return find_sha1_file(sha1, &st) ? 1 : 0;
1931 }
1932
1933 /*
1934  * reads from fd as long as possible into a supplied buffer of size bytes.
1935  * If necessary the buffer's size is increased using realloc()
1936  *
1937  * returns 0 if anything went fine and -1 otherwise
1938  *
1939  * NOTE: both buf and size may change, but even when -1 is returned
1940  * you still have to free() it yourself.
1941  */
1942 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1943 {
1944         char* buf = *return_buf;
1945         unsigned long size = *return_size;
1946         int iret;
1947         unsigned long off = 0;
1948
1949         do {
1950                 iret = xread(fd, buf + off, size - off);
1951                 if (iret > 0) {
1952                         off += iret;
1953                         if (off == size) {
1954                                 size *= 2;
1955                                 buf = xrealloc(buf, size);
1956                         }
1957                 }
1958         } while (iret > 0);
1959
1960         *return_buf = buf;
1961         *return_size = off;
1962
1963         if (iret < 0)
1964                 return -1;
1965         return 0;
1966 }
1967
1968 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1969 {
1970         unsigned long size = 4096;
1971         char *buf = xmalloc(size);
1972         int ret;
1973
1974         if (read_pipe(fd, &buf, &size)) {
1975                 free(buf);
1976                 return -1;
1977         }
1978
1979         if (!type)
1980                 type = blob_type;
1981         if (write_object)
1982                 ret = write_sha1_file(buf, size, type, sha1);
1983         else
1984                 ret = hash_sha1_file(buf, size, type, sha1);
1985         free(buf);
1986         return ret;
1987 }
1988
1989 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1990 {
1991         unsigned long size = st->st_size;
1992         void *buf;
1993         int ret;
1994
1995         buf = "";
1996         if (size)
1997                 buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1998         close(fd);
1999
2000         if (!type)
2001                 type = blob_type;
2002         if (write_object)
2003                 ret = write_sha1_file(buf, size, type, sha1);
2004         else
2005                 ret = hash_sha1_file(buf, size, type, sha1);
2006         if (size)
2007                 munmap(buf, size);
2008         return ret;
2009 }
2010
2011 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2012 {
2013         int fd;
2014         char *target;
2015
2016         switch (st->st_mode & S_IFMT) {
2017         case S_IFREG:
2018                 fd = open(path, O_RDONLY);
2019                 if (fd < 0)
2020                         return error("open(\"%s\"): %s", path,
2021                                      strerror(errno));
2022                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
2023                         return error("%s: failed to insert into database",
2024                                      path);
2025                 break;
2026         case S_IFLNK:
2027                 target = xmalloc(st->st_size+1);
2028                 if (readlink(path, target, st->st_size+1) != st->st_size) {
2029                         char *errstr = strerror(errno);
2030                         free(target);
2031                         return error("readlink(\"%s\"): %s", path,
2032                                      errstr);
2033                 }
2034                 if (!write_object)
2035                         hash_sha1_file(target, st->st_size, blob_type, sha1);
2036                 else if (write_sha1_file(target, st->st_size, blob_type, sha1))
2037                         return error("%s: failed to insert into database",
2038                                      path);
2039                 free(target);
2040                 break;
2041         default:
2042                 return error("%s: unsupported file type", path);
2043         }
2044         return 0;
2045 }