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         uint32_t *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 %s is too small", path);
 460
 461         /* a future index format would start with this, as older git
 462          * binaries would fail the non-monotonic index check below.
 463          * give a nicer warning to the user if we can.
 464          */
 465         if (index[0] == htonl(PACK_IDX_SIGNATURE))
 466                 return error("index file %s is a newer version"
 467                         " and is not supported by this binary"
 468                         " (try upgrading GIT to a newer version)",
 469                         path);
 470
 471         nr = 0;
 472         for (i = 0; i < 256; i++) {
 473                 unsigned int n = ntohl(index[i]);
 474                 if (n < nr)
 475                         return error("non-monotonic index %s", path);
 476                 nr = n;
 477         }
 478
 479         /*
 480          * Total size:
 481          *  - 256 index entries 4 bytes each
 482          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 483          *  - 20-byte SHA1 of the packfile
 484          *  - 20-byte SHA1 file checksum
 485          */
 486         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 487                 return error("wrong index file size in %s", path);
 488
 489         return 0;
 490 }
 491
 492 static void scan_windows(struct packed_git *p,
 493         struct packed_git **lru_p,
 494         struct pack_window **lru_w,
 495         struct pack_window **lru_l)
 496 {
 497         struct pack_window *w, *w_l;
 498
 499         for (w_l = NULL, w = p->windows; w; w = w->next) {
 500                 if (!w->inuse_cnt) {
 501                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 502                                 *lru_p = p;
 503                                 *lru_w = w;
 504                                 *lru_l = w_l;
 505                         }
 506                 }
 507                 w_l = w;
 508         }
 509 }
 510
 511 static int unuse_one_window(struct packed_git *current)
 512 {
 513         struct packed_git *p, *lru_p = NULL;
 514         struct pack_window *lru_w = NULL, *lru_l = NULL;
 515
 516         if (current)
 517                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 518         for (p = packed_git; p; p = p->next)
 519                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 520         if (lru_p) {
 521                 munmap(lru_w->base, lru_w->len);
 522                 pack_mapped -= lru_w->len;
 523                 if (lru_l)
 524                         lru_l->next = lru_w->next;
 525                 else {
 526                         lru_p->windows = lru_w->next;
 527                         if (!lru_p->windows && lru_p != current) {
 528                                 close(lru_p->pack_fd);
 529                                 lru_p->pack_fd = -1;
 530                         }
 531                 }
 532                 free(lru_w);
 533                 pack_open_windows--;
 534                 return 1;
 535         }
 536         return 0;
 537 }
 538
 539 void release_pack_memory(size_t need)
 540 {
 541         size_t cur = pack_mapped;
 542         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 543                 ; /* nothing */
 544 }
 545
 546 void unuse_pack(struct pack_window **w_cursor)
 547 {
 548         struct pack_window *w = *w_cursor;
 549         if (w) {
 550                 w->inuse_cnt--;
 551                 *w_cursor = NULL;
 552         }
 553 }
 554
 555 static void open_packed_git(struct packed_git *p)
 556 {
 557         struct stat st;
 558         struct pack_header hdr;
 559         unsigned char sha1[20];
 560         unsigned char *idx_sha1;
 561         long fd_flag;
 562
 563         p->pack_fd = open(p->pack_name, O_RDONLY);
 564         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 565                 die("packfile %s cannot be opened", p->pack_name);
 566
 567         /* If we created the struct before we had the pack we lack size. */
 568         if (!p->pack_size) {
 569                 if (!S_ISREG(st.st_mode))
 570                         die("packfile %s not a regular file", p->pack_name);
 571                 p->pack_size = st.st_size;
 572         } else if (p->pack_size != st.st_size)
 573                 die("packfile %s size changed", p->pack_name);
 574
 575         /* We leave these file descriptors open with sliding mmap;
 576          * there is no point keeping them open across exec(), though.
 577          */
 578         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 579         if (fd_flag < 0)
 580                 die("cannot determine file descriptor flags");
 581         fd_flag |= FD_CLOEXEC;
 582         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 583                 die("cannot set FD_CLOEXEC");
 584
 585         /* Verify we recognize this pack file format. */
 586         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 587                 die("file %s is far too short to be a packfile", p->pack_name);
 588         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 589                 die("file %s is not a GIT packfile", p->pack_name);
 590         if (!pack_version_ok(hdr.hdr_version))
 591                 die("packfile %s is version %u and not supported"
 592                         " (try upgrading GIT to a newer version)",
 593                         p->pack_name, ntohl(hdr.hdr_version));
 594
 595         /* Verify the pack matches its index. */
 596         if (num_packed_objects(p) != ntohl(hdr.hdr_entries))
 597                 die("packfile %s claims to have %u objects"
 598                         " while index size indicates %u objects",
 599                         p->pack_name, ntohl(hdr.hdr_entries),
 600                         num_packed_objects(p));
 601         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 602                 die("end of packfile %s is unavailable", p->pack_name);
 603         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 604                 die("packfile %s signature is unavailable", p->pack_name);
 605         idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
 606         if (hashcmp(sha1, idx_sha1))
 607                 die("packfile %s does not match index", p->pack_name);
 608 }
 609
 610 static int in_window(struct pack_window *win, unsigned long offset)
 611 {
 612         /* We must promise at least 20 bytes (one hash) after the
 613          * offset is available from this window, otherwise the offset
 614          * is not actually in this window and a different window (which
 615          * has that one hash excess) must be used.  This is to support
 616          * the object header and delta base parsing routines below.
 617          */
 618         off_t win_off = win->offset;
 619         return win_off <= offset
 620                 && (offset + 20) <= (win_off + win->len);
 621 }
 622
 623 unsigned char* use_pack(struct packed_git *p,
 624                 struct pack_window **w_cursor,
 625                 unsigned long offset,
 626                 unsigned int *left)
 627 {
 628         struct pack_window *win = *w_cursor;
 629
 630         if (p->pack_fd == -1)
 631                 open_packed_git(p);
 632
 633         /* Since packfiles end in a hash of their content and its
 634          * pointless to ask for an offset into the middle of that
 635          * hash, and the in_window function above wouldn't match
 636          * don't allow an offset too close to the end of the file.
 637          */
 638         if (offset > (p->pack_size - 20))
 639                 die("offset beyond end of packfile (truncated pack?)");
 640
 641         if (!win || !in_window(win, offset)) {
 642                 if (win)
 643                         win->inuse_cnt--;
 644                 for (win = p->windows; win; win = win->next) {
 645                         if (in_window(win, offset))
 646                                 break;
 647                 }
 648                 if (!win) {
 649                         if (!page_size)
 650                                 page_size = getpagesize();
 651                         win = xcalloc(1, sizeof(*win));
 652                         win->offset = (offset / page_size) * page_size;
 653                         win->len = p->pack_size - win->offset;
 654                         if (win->len > packed_git_window_size)
 655                                 win->len = packed_git_window_size;
 656                         pack_mapped += win->len;
 657                         while (packed_git_limit < pack_mapped
 658                                 && unuse_one_window(p))
 659                                 ; /* nothing */
 660                         win->base = xmmap(NULL, win->len,
 661                                 PROT_READ, MAP_PRIVATE,
 662                                 p->pack_fd, win->offset);
 663                         if (win->base == MAP_FAILED)
 664                                 die("packfile %s cannot be mapped: %s",
 665                                         p->pack_name,
 666                                         strerror(errno));
 667                         pack_mmap_calls++;
 668                         pack_open_windows++;
 669                         if (pack_mapped > peak_pack_mapped)
 670                                 peak_pack_mapped = pack_mapped;
 671                         if (pack_open_windows > peak_pack_open_windows)
 672                                 peak_pack_open_windows = pack_open_windows;
 673                         win->next = p->windows;
 674                         p->windows = win;
 675                 }
 676         }
 677         if (win != *w_cursor) {
 678                 win->last_used = pack_used_ctr++;
 679                 win->inuse_cnt++;
 680                 *w_cursor = win;
 681         }
 682         offset -= win->offset;
 683         if (left)
 684                 *left = win->len - offset;
 685         return win->base + offset;
 686 }
 687
 688 struct packed_git *add_packed_git(char *path, int path_len, int local)
 689 {
 690         struct stat st;
 691         struct packed_git *p;
 692         unsigned long idx_size;
 693         void *idx_map;
 694         unsigned char sha1[20];
 695
 696         if (check_packed_git_idx(path, &idx_size, &idx_map))
 697                 return NULL;
 698
 699         /* do we have a corresponding .pack file? */
 700         strcpy(path + path_len - 4, ".pack");
 701         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 702                 munmap(idx_map, idx_size);
 703                 return NULL;
 704         }
 705         /* ok, it looks sane as far as we can check without
 706          * actually mapping the pack file.
 707          */
 708         p = xmalloc(sizeof(*p) + path_len + 2);
 709         strcpy(p->pack_name, path);
 710         p->index_size = idx_size;
 711         p->pack_size = st.st_size;
 712         p->index_base = idx_map;
 713         p->next = NULL;
 714         p->windows = NULL;
 715         p->pack_fd = -1;
 716         p->pack_local = local;
 717         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 718                 hashcpy(p->sha1, sha1);
 719         return p;
 720 }
 721
 722 struct packed_git *parse_pack_index(unsigned char *sha1)
 723 {
 724         char *path = sha1_pack_index_name(sha1);
 725         return parse_pack_index_file(sha1, path);
 726 }
 727
 728 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 729 {
 730         struct packed_git *p;
 731         unsigned long idx_size;
 732         void *idx_map;
 733         char *path;
 734
 735         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 736                 return NULL;
 737
 738         path = sha1_pack_name(sha1);
 739
 740         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 741         strcpy(p->pack_name, path);
 742         p->index_size = idx_size;
 743         p->pack_size = 0;
 744         p->index_base = idx_map;
 745         p->next = NULL;
 746         p->windows = NULL;
 747         p->pack_fd = -1;
 748         hashcpy(p->sha1, sha1);
 749         return p;
 750 }
 751
 752 void install_packed_git(struct packed_git *pack)
 753 {
 754         pack->next = packed_git;
 755         packed_git = pack;
 756 }
 757
 758 static void prepare_packed_git_one(char *objdir, int local)
 759 {
 760         char path[PATH_MAX];
 761         int len;
 762         DIR *dir;
 763         struct dirent *de;
 764
 765         sprintf(path, "%s/pack", objdir);
 766         len = strlen(path);
 767         dir = opendir(path);
 768         if (!dir) {
 769                 if (errno != ENOENT)
 770                         error("unable to open object pack directory: %s: %s",
 771                               path, strerror(errno));
 772                 return;
 773         }
 774         path[len++] = '/';
 775         while ((de = readdir(dir)) != NULL) {
 776                 int namelen = strlen(de->d_name);
 777                 struct packed_git *p;
 778
 779                 if (!has_extension(de->d_name, ".idx"))
 780                         continue;
 781
 782                 /* we have .idx.  Is it a file we can map? */
 783                 strcpy(path + len, de->d_name);
 784                 for (p = packed_git; p; p = p->next) {
 785                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 786                                 break;
 787                 }
 788                 if (p)
 789                         continue;
 790                 p = add_packed_git(path, len + namelen, local);
 791                 if (!p)
 792                         continue;
 793                 p->next = packed_git;
 794                 packed_git = p;
 795         }
 796         closedir(dir);
 797 }
 798
 799 static int prepare_packed_git_run_once = 0;
 800 void prepare_packed_git(void)
 801 {
 802         struct alternate_object_database *alt;
 803
 804         if (prepare_packed_git_run_once)
 805                 return;
 806         prepare_packed_git_one(get_object_directory(), 1);
 807         prepare_alt_odb();
 808         for (alt = alt_odb_list; alt; alt = alt->next) {
 809                 alt->name[-1] = 0;
 810                 prepare_packed_git_one(alt->base, 0);
 811                 alt->name[-1] = '/';
 812         }
 813         prepare_packed_git_run_once = 1;
 814 }
 815
 816 void reprepare_packed_git(void)
 817 {
 818         prepare_packed_git_run_once = 0;
 819         prepare_packed_git();
 820 }
 821
 822 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 823 {
 824         unsigned char real_sha1[20];
 825         hash_sha1_file(map, size, type, real_sha1);
 826         return hashcmp(sha1, real_sha1) ? -1 : 0;
 827 }
 828
 829 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 830 {
 831         struct stat st;
 832         void *map;
 833         int fd;
 834         char *filename = find_sha1_file(sha1, &st);
 835
 836         if (!filename) {
 837                 return NULL;
 838         }
 839
 840         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 841         if (fd < 0) {
 842                 /* See if it works without O_NOATIME */
 843                 switch (sha1_file_open_flag) {
 844                 default:
 845                         fd = open(filename, O_RDONLY);
 846                         if (fd >= 0)
 847                                 break;
 848                 /* Fallthrough */
 849                 case 0:
 850                         return NULL;
 851                 }
 852
 853                 /* If it failed once, it will probably fail again.
 854                  * Stop using O_NOATIME
 855                  */
 856                 sha1_file_open_flag = 0;
 857         }
 858         map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 859         close(fd);
 860         *size = st.st_size;
 861         return map;
 862 }
 863
 864 int legacy_loose_object(unsigned char *map)
 865 {
 866         unsigned int word;
 867
 868         /*
 869          * Is it a zlib-compressed buffer? If so, the first byte
 870          * must be 0x78 (15-bit window size, deflated), and the
 871          * first 16-bit word is evenly divisible by 31
 872          */
 873         word = (map[0] << 8) + map[1];
 874         if (map[0] == 0x78 && !(word % 31))
 875                 return 1;
 876         else
 877                 return 0;
 878 }
 879
 880 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 881 {
 882         unsigned shift;
 883         unsigned char c;
 884         unsigned long size;
 885         unsigned long used = 0;
 886
 887         c = buf[used++];
 888         *type = (c >> 4) & 7;
 889         size = c & 15;
 890         shift = 4;
 891         while (c & 0x80) {
 892                 if (len <= used)
 893                         return 0;
 894                 if (sizeof(long) * 8 <= shift)
 895                         return 0;
 896                 c = buf[used++];
 897                 size += (c & 0x7f) << shift;
 898                 shift += 7;
 899         }
 900         *sizep = size;
 901         return used;
 902 }
 903
 904 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 905 {
 906         unsigned long size, used;
 907         static const char valid_loose_object_type[8] = {
 908                 0, /* OBJ_EXT */
 909                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 910                 0, /* "delta" and others are invalid in a loose object */
 911         };
 912         enum object_type type;
 913
 914         /* Get the data stream */
 915         memset(stream, 0, sizeof(*stream));
 916         stream->next_in = map;
 917         stream->avail_in = mapsize;
 918         stream->next_out = buffer;
 919         stream->avail_out = bufsiz;
 920
 921         if (legacy_loose_object(map)) {
 922                 inflateInit(stream);
 923                 return inflate(stream, 0);
 924         }
 925
 926         used = unpack_object_header_gently(map, mapsize, &type, &size);
 927         if (!used || !valid_loose_object_type[type])
 928                 return -1;
 929         map += used;
 930         mapsize -= used;
 931
 932         /* Set up the stream for the rest.. */
 933         stream->next_in = map;
 934         stream->avail_in = mapsize;
 935         inflateInit(stream);
 936
 937         /* And generate the fake traditional header */
 938         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 939                                          type_names[type], size);
 940         return 0;
 941 }
 942
 943 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 944 {
 945         int bytes = strlen(buffer) + 1;
 946         unsigned char *buf = xmalloc(1+size);
 947         unsigned long n;
 948
 949         n = stream->total_out - bytes;
 950         if (n > size)
 951                 n = size;
 952         memcpy(buf, (char *) buffer + bytes, n);
 953         bytes = n;
 954         if (bytes < size) {
 955                 stream->next_out = buf + bytes;
 956                 stream->avail_out = size - bytes;
 957                 while (inflate(stream, Z_FINISH) == Z_OK)
 958                         /* nothing */;
 959         }
 960         buf[size] = 0;
 961         inflateEnd(stream);
 962         return buf;
 963 }
 964
 965 /*
 966  * We used to just use "sscanf()", but that's actually way
 967  * too permissive for what we want to check. So do an anal
 968  * object header parse by hand.
 969  */
 970 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 971 {
 972         int i;
 973         unsigned long size;
 974
 975         /*
 976          * The type can be at most ten bytes (including the
 977          * terminating '\0' that we add), and is followed by
 978          * a space.
 979          */
 980         i = 10;
 981         for (;;) {
 982                 char c = *hdr++;
 983                 if (c == ' ')
 984                         break;
 985                 if (!--i)
 986                         return -1;
 987                 *type++ = c;
 988         }
 989         *type = 0;
 990
 991         /*
 992          * The length must follow immediately, and be in canonical
 993          * decimal format (ie "010" is not valid).
 994          */
 995         size = *hdr++ - '0';
 996         if (size > 9)
 997                 return -1;
 998         if (size) {
 999                 for (;;) {
1000                         unsigned long c = *hdr - '0';
1001                         if (c > 9)
1002                                 break;
1003                         hdr++;
1004                         size = size * 10 + c;
1005                 }
1006         }
1007         *sizep = size;
1008
1009         /*
1010          * The length must be followed by a zero byte
1011          */
1012         return *hdr ? -1 : 0;
1013 }
1014
1015 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
1016 {
1017         int ret;
1018         z_stream stream;
1019         char hdr[8192];
1020
1021         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1022         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
1023                 return NULL;
1024
1025         return unpack_sha1_rest(&stream, hdr, *size);
1026 }
1027
1028 static unsigned long get_delta_base(struct packed_git *p,
1029                                     struct pack_window **w_curs,
1030                                     unsigned long offset,
1031                                     enum object_type kind,
1032                                     unsigned long delta_obj_offset,
1033                                     unsigned long *base_obj_offset)
1034 {
1035         unsigned char *base_info = use_pack(p, w_curs, offset, NULL);
1036         unsigned long base_offset;
1037
1038         /* use_pack() assured us we have [base_info, base_info + 20)
1039          * as a range that we can look at without walking off the
1040          * end of the mapped window.  Its actually the hash size
1041          * that is assured.  An OFS_DELTA longer than the hash size
1042          * is stupid, as then a REF_DELTA would be smaller to store.
1043          */
1044         if (kind == OBJ_OFS_DELTA) {
1045                 unsigned used = 0;
1046                 unsigned char c = base_info[used++];
1047                 base_offset = c & 127;
1048                 while (c & 128) {
1049                         base_offset += 1;
1050                         if (!base_offset || base_offset & ~(~0UL >> 7))
1051                                 die("offset value overflow for delta base object");
1052                         c = base_info[used++];
1053                         base_offset = (base_offset << 7) + (c & 127);
1054                 }
1055                 base_offset = delta_obj_offset - base_offset;
1056                 if (base_offset >= delta_obj_offset)
1057                         die("delta base offset out of bound");
1058                 offset += used;
1059         } else if (kind == OBJ_REF_DELTA) {
1060                 /* The base entry _must_ be in the same pack */
1061                 base_offset = find_pack_entry_one(base_info, p);
1062                 if (!base_offset)
1063                         die("failed to find delta-pack base object %s",
1064                                 sha1_to_hex(base_info));
1065                 offset += 20;
1066         } else
1067                 die("I am totally screwed");
1068         *base_obj_offset = base_offset;
1069         return offset;
1070 }
1071
1072 /* forward declaration for a mutually recursive function */
1073 static int packed_object_info(struct packed_git *p, unsigned long offset,
1074                               char *type, unsigned long *sizep);
1075
1076 static int packed_delta_info(struct packed_git *p,
1077                              struct pack_window **w_curs,
1078                              unsigned long offset,
1079                              enum object_type kind,
1080                              unsigned long obj_offset,
1081                              char *type,
1082                              unsigned long *sizep)
1083 {
1084         unsigned long base_offset;
1085
1086         offset = get_delta_base(p, w_curs, offset, kind,
1087                 obj_offset, &base_offset);
1088
1089         /* We choose to only get the type of the base object and
1090          * ignore potentially corrupt pack file that expects the delta
1091          * based on a base with a wrong size.  This saves tons of
1092          * inflate() calls.
1093          */
1094         if (packed_object_info(p, base_offset, type, NULL))
1095                 die("cannot get info for delta-pack base");
1096
1097         if (sizep) {
1098                 const unsigned char *data;
1099                 unsigned char delta_head[20], *in;
1100                 unsigned long result_size;
1101                 z_stream stream;
1102                 int st;
1103
1104                 memset(&stream, 0, sizeof(stream));
1105                 stream.next_out = delta_head;
1106                 stream.avail_out = sizeof(delta_head);
1107
1108                 inflateInit(&stream);
1109                 do {
1110                         in = use_pack(p, w_curs, offset, &stream.avail_in);
1111                         stream.next_in = in;
1112                         st = inflate(&stream, Z_FINISH);
1113                         offset += stream.next_in - in;
1114                 } while ((st == Z_OK || st == Z_BUF_ERROR)
1115                         && stream.total_out < sizeof(delta_head));
1116                 inflateEnd(&stream);
1117                 if ((st != Z_STREAM_END) &&
1118                     stream.total_out != sizeof(delta_head))
1119                         die("delta data unpack-initial failed");
1120
1121                 /* Examine the initial part of the delta to figure out
1122                  * the result size.
1123                  */
1124                 data = delta_head;
1125
1126                 /* ignore base size */
1127                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1128
1129                 /* Read the result size */
1130                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1131                 *sizep = result_size;
1132         }
1133         return 0;
1134 }
1135
1136 static unsigned long unpack_object_header(struct packed_git *p,
1137                 struct pack_window **w_curs,
1138                 unsigned long offset,
1139                 enum object_type *type,
1140                 unsigned long *sizep)
1141 {
1142         unsigned char *base;
1143         unsigned int left;
1144         unsigned long used;
1145
1146         /* use_pack() assures us we have [base, base + 20) available
1147          * as a range that we can look at at.  (Its actually the hash
1148          * size that is assurred.)  With our object header encoding
1149          * the maximum deflated object size is 2^137, which is just
1150          * insane, so we know won't exceed what we have been given.
1151          */
1152         base = use_pack(p, w_curs, offset, &left);
1153         used = unpack_object_header_gently(base, left, type, sizep);
1154         if (!used)
1155                 die("object offset outside of pack file");
1156
1157         return offset + used;
1158 }
1159
1160 void packed_object_info_detail(struct packed_git *p,
1161                                unsigned long offset,
1162                                char *type,
1163                                unsigned long *size,
1164                                unsigned long *store_size,
1165                                unsigned int *delta_chain_length,
1166                                unsigned char *base_sha1)
1167 {
1168         struct pack_window *w_curs = NULL;
1169         unsigned long obj_offset, val;
1170         unsigned char *next_sha1;
1171         enum object_type kind;
1172
1173         *delta_chain_length = 0;
1174         obj_offset = offset;
1175         offset = unpack_object_header(p, &w_curs, offset, &kind, size);
1176
1177         for (;;) {
1178                 switch (kind) {
1179                 default:
1180                         die("pack %s contains unknown object type %d",
1181                             p->pack_name, kind);
1182                 case OBJ_COMMIT:
1183                 case OBJ_TREE:
1184                 case OBJ_BLOB:
1185                 case OBJ_TAG:
1186                         strcpy(type, type_names[kind]);
1187                         *store_size = 0; /* notyet */
1188                         unuse_pack(&w_curs);
1189                         return;
1190                 case OBJ_OFS_DELTA:
1191                         get_delta_base(p, &w_curs, offset, kind,
1192                                 obj_offset, &offset);
1193                         if (*delta_chain_length == 0) {
1194                                 /* TODO: find base_sha1 as pointed by offset */
1195                         }
1196                         break;
1197                 case OBJ_REF_DELTA:
1198                         next_sha1 = use_pack(p, &w_curs, offset, NULL);
1199                         if (*delta_chain_length == 0)
1200                                 hashcpy(base_sha1, next_sha1);
1201                         offset = find_pack_entry_one(next_sha1, p);
1202                         break;
1203                 }
1204                 obj_offset = offset;
1205                 offset = unpack_object_header(p, &w_curs, offset, &kind, &val);
1206                 (*delta_chain_length)++;
1207         }
1208 }
1209
1210 static int packed_object_info(struct packed_git *p, unsigned long offset,
1211                               char *type, unsigned long *sizep)
1212 {
1213         struct pack_window *w_curs = NULL;
1214         unsigned long size, obj_offset = offset;
1215         enum object_type kind;
1216         int r;
1217
1218         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1219
1220         switch (kind) {
1221         case OBJ_OFS_DELTA:
1222         case OBJ_REF_DELTA:
1223                 r = packed_delta_info(p, &w_curs, offset, kind,
1224                         obj_offset, type, sizep);
1225                 unuse_pack(&w_curs);
1226                 return r;
1227         case OBJ_COMMIT:
1228         case OBJ_TREE:
1229         case OBJ_BLOB:
1230         case OBJ_TAG:
1231                 strcpy(type, type_names[kind]);
1232                 unuse_pack(&w_curs);
1233                 break;
1234         default:
1235                 die("pack %s contains unknown object type %d",
1236                     p->pack_name, kind);
1237         }
1238         if (sizep)
1239                 *sizep = size;
1240         return 0;
1241 }
1242
1243 static void *unpack_compressed_entry(struct packed_git *p,
1244                                     struct pack_window **w_curs,
1245                                     unsigned long offset,
1246                                     unsigned long size)
1247 {
1248         int st;
1249         z_stream stream;
1250         unsigned char *buffer, *in;
1251
1252         buffer = xmalloc(size + 1);
1253         buffer[size] = 0;
1254         memset(&stream, 0, sizeof(stream));
1255         stream.next_out = buffer;
1256         stream.avail_out = size;
1257
1258         inflateInit(&stream);
1259         do {
1260                 in = use_pack(p, w_curs, offset, &stream.avail_in);
1261                 stream.next_in = in;
1262                 st = inflate(&stream, Z_FINISH);
1263                 offset += stream.next_in - in;
1264         } while (st == Z_OK || st == Z_BUF_ERROR);
1265         inflateEnd(&stream);
1266         if ((st != Z_STREAM_END) || stream.total_out != size) {
1267                 free(buffer);
1268                 return NULL;
1269         }
1270
1271         return buffer;
1272 }
1273
1274 static void *unpack_delta_entry(struct packed_git *p,
1275                                 struct pack_window **w_curs,
1276                                 unsigned long offset,
1277                                 unsigned long delta_size,
1278                                 enum object_type kind,
1279                                 unsigned long obj_offset,
1280                                 char *type,
1281                                 unsigned long *sizep)
1282 {
1283         void *delta_data, *result, *base;
1284         unsigned long result_size, base_size, base_offset;
1285
1286         offset = get_delta_base(p, w_curs, offset, kind,
1287                 obj_offset, &base_offset);
1288         base = unpack_entry(p, base_offset, type, &base_size);
1289         if (!base)
1290                 die("failed to read delta base object at %lu from %s",
1291                     base_offset, p->pack_name);
1292
1293         delta_data = unpack_compressed_entry(p, w_curs, offset, delta_size);
1294         result = patch_delta(base, base_size,
1295                              delta_data, delta_size,
1296                              &result_size);
1297         if (!result)
1298                 die("failed to apply delta");
1299         free(delta_data);
1300         free(base);
1301         *sizep = result_size;
1302         return result;
1303 }
1304
1305 void *unpack_entry(struct packed_git *p, unsigned long offset,
1306                           char *type, unsigned long *sizep)
1307 {
1308         struct pack_window *w_curs = NULL;
1309         unsigned long size, obj_offset = offset;
1310         enum object_type kind;
1311         void *retval;
1312
1313         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1314         switch (kind) {
1315         case OBJ_OFS_DELTA:
1316         case OBJ_REF_DELTA:
1317                 retval = unpack_delta_entry(p, &w_curs, offset, size,
1318                         kind, obj_offset, type, sizep);
1319                 break;
1320         case OBJ_COMMIT:
1321         case OBJ_TREE:
1322         case OBJ_BLOB:
1323         case OBJ_TAG:
1324                 strcpy(type, type_names[kind]);
1325                 *sizep = size;
1326                 retval = unpack_compressed_entry(p, &w_curs, offset, size);
1327                 break;
1328         default:
1329                 die("unknown object type %i in %s", kind, p->pack_name);
1330         }
1331         unuse_pack(&w_curs);
1332         return retval;
1333 }
1334
1335 int num_packed_objects(const struct packed_git *p)
1336 {
1337         /* See check_packed_git_idx() */
1338         return (p->index_size - 20 - 20 - 4*256) / 24;
1339 }
1340
1341 int nth_packed_object_sha1(const struct packed_git *p, int n,
1342                            unsigned char* sha1)
1343 {
1344         void *index = p->index_base + 256;
1345         if (n < 0 || num_packed_objects(p) <= n)
1346                 return -1;
1347         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1348         return 0;
1349 }
1350
1351 unsigned long find_pack_entry_one(const unsigned char *sha1,
1352                                   struct packed_git *p)
1353 {
1354         uint32_t *level1_ofs = p->index_base;
1355         int hi = ntohl(level1_ofs[*sha1]);
1356         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1357         void *index = p->index_base + 256;
1358
1359         do {
1360                 int mi = (lo + hi) / 2;
1361                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1362                 if (!cmp)
1363                         return ntohl(*((uint32_t *)((char *)index + (24 * mi))));
1364                 if (cmp > 0)
1365                         hi = mi;
1366                 else
1367                         lo = mi+1;
1368         } while (lo < hi);
1369         return 0;
1370 }
1371
1372 static int matches_pack_name(struct packed_git *p, const char *ig)
1373 {
1374         const char *last_c, *c;
1375
1376         if (!strcmp(p->pack_name, ig))
1377                 return 0;
1378
1379         for (c = p->pack_name, last_c = c; *c;)
1380                 if (*c == '/')
1381                         last_c = ++c;
1382                 else
1383                         ++c;
1384         if (!strcmp(last_c, ig))
1385                 return 0;
1386
1387         return 1;
1388 }
1389
1390 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1391 {
1392         struct packed_git *p;
1393         unsigned long offset;
1394
1395         prepare_packed_git();
1396
1397         for (p = packed_git; p; p = p->next) {
1398                 if (ignore_packed) {
1399                         const char **ig;
1400                         for (ig = ignore_packed; *ig; ig++)
1401                                 if (!matches_pack_name(p, *ig))
1402                                         break;
1403                         if (*ig)
1404                                 continue;
1405                 }
1406                 offset = find_pack_entry_one(sha1, p);
1407                 if (offset) {
1408                         e->offset = offset;
1409                         e->p = p;
1410                         hashcpy(e->sha1, sha1);
1411                         return 1;
1412                 }
1413         }
1414         return 0;
1415 }
1416
1417 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1418                                   struct packed_git *packs)
1419 {
1420         struct packed_git *p;
1421
1422         for (p = packs; p; p = p->next) {
1423                 if (find_pack_entry_one(sha1, p))
1424                         return p;
1425         }
1426         return NULL;
1427
1428 }
1429
1430 static int sha1_loose_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1431 {
1432         int status;
1433         unsigned long mapsize, size;
1434         void *map;
1435         z_stream stream;
1436         char hdr[128];
1437
1438         map = map_sha1_file(sha1, &mapsize);
1439         if (!map)
1440                 return error("unable to find %s", sha1_to_hex(sha1));
1441         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1442                 status = error("unable to unpack %s header",
1443                                sha1_to_hex(sha1));
1444         if (parse_sha1_header(hdr, type, &size) < 0)
1445                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1446         else {
1447                 status = 0;
1448                 if (sizep)
1449                         *sizep = size;
1450         }
1451         inflateEnd(&stream);
1452         munmap(map, mapsize);
1453         return status;
1454 }
1455
1456 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1457 {
1458         struct pack_entry e;
1459
1460         if (!find_pack_entry(sha1, &e, NULL)) {
1461                 reprepare_packed_git();
1462                 if (!find_pack_entry(sha1, &e, NULL))
1463                         return sha1_loose_object_info(sha1, type, sizep);
1464         }
1465         return packed_object_info(e.p, e.offset, type, sizep);
1466 }
1467
1468 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1469 {
1470         struct pack_entry e;
1471
1472         if (!find_pack_entry(sha1, &e, NULL)) {
1473                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1474                 return NULL;
1475         }
1476         return unpack_entry(e.p, e.offset, type, size);
1477 }
1478
1479 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1480 {
1481         unsigned long mapsize;
1482         void *map, *buf;
1483         struct pack_entry e;
1484
1485         if (find_pack_entry(sha1, &e, NULL))
1486                 return read_packed_sha1(sha1, type, size);
1487         map = map_sha1_file(sha1, &mapsize);
1488         if (map) {
1489                 buf = unpack_sha1_file(map, mapsize, type, size);
1490                 munmap(map, mapsize);
1491                 return buf;
1492         }
1493         reprepare_packed_git();
1494         if (find_pack_entry(sha1, &e, NULL))
1495                 return read_packed_sha1(sha1, type, size);
1496         return NULL;
1497 }
1498
1499 void *read_object_with_reference(const unsigned char *sha1,
1500                                  const char *required_type,
1501                                  unsigned long *size,
1502                                  unsigned char *actual_sha1_return)
1503 {
1504         char type[20];
1505         void *buffer;
1506         unsigned long isize;
1507         unsigned char actual_sha1[20];
1508
1509         hashcpy(actual_sha1, sha1);
1510         while (1) {
1511                 int ref_length = -1;
1512                 const char *ref_type = NULL;
1513
1514                 buffer = read_sha1_file(actual_sha1, type, &isize);
1515                 if (!buffer)
1516                         return NULL;
1517                 if (!strcmp(type, required_type)) {
1518                         *size = isize;
1519                         if (actual_sha1_return)
1520                                 hashcpy(actual_sha1_return, actual_sha1);
1521                         return buffer;
1522                 }
1523                 /* Handle references */
1524                 else if (!strcmp(type, commit_type))
1525                         ref_type = "tree ";
1526                 else if (!strcmp(type, tag_type))
1527                         ref_type = "object ";
1528                 else {
1529                         free(buffer);
1530                         return NULL;
1531                 }
1532                 ref_length = strlen(ref_type);
1533
1534                 if (memcmp(buffer, ref_type, ref_length) ||
1535                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1536                         free(buffer);
1537                         return NULL;
1538                 }
1539                 free(buffer);
1540                 /* Now we have the ID of the referred-to object in
1541                  * actual_sha1.  Check again. */
1542         }
1543 }
1544
1545 static void write_sha1_file_prepare(void *buf, unsigned long len,
1546                                     const char *type, unsigned char *sha1,
1547                                     unsigned char *hdr, int *hdrlen)
1548 {
1549         SHA_CTX c;
1550
1551         /* Generate the header */
1552         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1553
1554         /* Sha1.. */
1555         SHA1_Init(&c);
1556         SHA1_Update(&c, hdr, *hdrlen);
1557         SHA1_Update(&c, buf, len);
1558         SHA1_Final(sha1, &c);
1559 }
1560
1561 /*
1562  * Link the tempfile to the final place, possibly creating the
1563  * last directory level as you do so.
1564  *
1565  * Returns the errno on failure, 0 on success.
1566  */
1567 static int link_temp_to_file(const char *tmpfile, const char *filename)
1568 {
1569         int ret;
1570         char *dir;
1571
1572         if (!link(tmpfile, filename))
1573                 return 0;
1574
1575         /*
1576          * Try to mkdir the last path component if that failed.
1577          *
1578          * Re-try the "link()" regardless of whether the mkdir
1579          * succeeds, since a race might mean that somebody
1580          * else succeeded.
1581          */
1582         ret = errno;
1583         dir = strrchr(filename, '/');
1584         if (dir) {
1585                 *dir = 0;
1586                 if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1587                         *dir = '/';
1588                         return -2;
1589                 }
1590                 *dir = '/';
1591                 if (!link(tmpfile, filename))
1592                         return 0;
1593                 ret = errno;
1594         }
1595         return ret;
1596 }
1597
1598 /*
1599  * Move the just written object into its final resting place
1600  */
1601 int move_temp_to_file(const char *tmpfile, const char *filename)
1602 {
1603         int ret = link_temp_to_file(tmpfile, filename);
1604
1605         /*
1606          * Coda hack - coda doesn't like cross-directory links,
1607          * so we fall back to a rename, which will mean that it
1608          * won't be able to check collisions, but that's not a
1609          * big deal.
1610          *
1611          * The same holds for FAT formatted media.
1612          *
1613          * When this succeeds, we just return 0. We have nothing
1614          * left to unlink.
1615          */
1616         if (ret && ret != EEXIST) {
1617                 if (!rename(tmpfile, filename))
1618                         return 0;
1619                 ret = errno;
1620         }
1621         unlink(tmpfile);
1622         if (ret) {
1623                 if (ret != EEXIST) {
1624                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1625                 }
1626                 /* FIXME!!! Collision check here ? */
1627         }
1628
1629         return 0;
1630 }
1631
1632 static int write_buffer(int fd, const void *buf, size_t len)
1633 {
1634         if (write_in_full(fd, buf, len) < 0)
1635                 return error("file write error (%s)", strerror(errno));
1636         return 0;
1637 }
1638
1639 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1640 {
1641         int hdr_len;
1642         unsigned char c;
1643
1644         c = (type << 4) | (len & 15);
1645         len >>= 4;
1646         hdr_len = 1;
1647         while (len) {
1648                 *hdr++ = c | 0x80;
1649                 hdr_len++;
1650                 c = (len & 0x7f);
1651                 len >>= 7;
1652         }
1653         *hdr = c;
1654         return hdr_len;
1655 }
1656
1657 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1658 {
1659         int obj_type, hdr;
1660
1661         if (use_legacy_headers) {
1662                 while (deflate(stream, 0) == Z_OK)
1663                         /* nothing */;
1664                 return;
1665         }
1666         if (!strcmp(type, blob_type))
1667                 obj_type = OBJ_BLOB;
1668         else if (!strcmp(type, tree_type))
1669                 obj_type = OBJ_TREE;
1670         else if (!strcmp(type, commit_type))
1671                 obj_type = OBJ_COMMIT;
1672         else if (!strcmp(type, tag_type))
1673                 obj_type = OBJ_TAG;
1674         else
1675                 die("trying to generate bogus object of type '%s'", type);
1676         hdr = write_binary_header(stream->next_out, obj_type, len);
1677         stream->total_out = hdr;
1678         stream->next_out += hdr;
1679         stream->avail_out -= hdr;
1680 }
1681
1682 int hash_sha1_file(void *buf, unsigned long len, const char *type,
1683                    unsigned char *sha1)
1684 {
1685         unsigned char hdr[50];
1686         int hdrlen;
1687         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1688         return 0;
1689 }
1690
1691 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1692 {
1693         int size;
1694         unsigned char *compressed;
1695         z_stream stream;
1696         unsigned char sha1[20];
1697         char *filename;
1698         static char tmpfile[PATH_MAX];
1699         unsigned char hdr[50];
1700         int fd, hdrlen;
1701
1702         /* Normally if we have it in the pack then we do not bother writing
1703          * it out into .git/objects/??/?{38} file.
1704          */
1705         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1706         filename = sha1_file_name(sha1);
1707         if (returnsha1)
1708                 hashcpy(returnsha1, sha1);
1709         if (has_sha1_file(sha1))
1710                 return 0;
1711         fd = open(filename, O_RDONLY);
1712         if (fd >= 0) {
1713                 /*
1714                  * FIXME!!! We might do collision checking here, but we'd
1715                  * need to uncompress the old file and check it. Later.
1716                  */
1717                 close(fd);
1718                 return 0;
1719         }
1720
1721         if (errno != ENOENT) {
1722                 return error("sha1 file %s: %s\n", filename, strerror(errno));
1723         }
1724
1725         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1726
1727         fd = mkstemp(tmpfile);
1728         if (fd < 0) {
1729                 if (errno == EPERM)
1730                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1731                 else
1732                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1733         }
1734
1735         /* Set it up */
1736         memset(&stream, 0, sizeof(stream));
1737         deflateInit(&stream, zlib_compression_level);
1738         size = 8 + deflateBound(&stream, len+hdrlen);
1739         compressed = xmalloc(size);
1740
1741         /* Compress it */
1742         stream.next_out = compressed;
1743         stream.avail_out = size;
1744
1745         /* First header.. */
1746         stream.next_in = hdr;
1747         stream.avail_in = hdrlen;
1748         setup_object_header(&stream, type, len);
1749
1750         /* Then the data itself.. */
1751         stream.next_in = buf;
1752         stream.avail_in = len;
1753         while (deflate(&stream, Z_FINISH) == Z_OK)
1754                 /* nothing */;
1755         deflateEnd(&stream);
1756         size = stream.total_out;
1757
1758         if (write_buffer(fd, compressed, size) < 0)
1759                 die("unable to write sha1 file");
1760         fchmod(fd, 0444);
1761         close(fd);
1762         free(compressed);
1763
1764         return move_temp_to_file(tmpfile, filename);
1765 }
1766
1767 /*
1768  * We need to unpack and recompress the object for writing
1769  * it out to a different file.
1770  */
1771 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1772 {
1773         size_t size;
1774         z_stream stream;
1775         unsigned char *unpacked;
1776         unsigned long len;
1777         char type[20];
1778         char hdr[50];
1779         int hdrlen;
1780         void *buf;
1781
1782         /* need to unpack and recompress it by itself */
1783         unpacked = read_packed_sha1(sha1, type, &len);
1784
1785         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1786
1787         /* Set it up */
1788         memset(&stream, 0, sizeof(stream));
1789         deflateInit(&stream, zlib_compression_level);
1790         size = deflateBound(&stream, len + hdrlen);
1791         buf = xmalloc(size);
1792
1793         /* Compress it */
1794         stream.next_out = buf;
1795         stream.avail_out = size;
1796
1797         /* First header.. */
1798         stream.next_in = (void *)hdr;
1799         stream.avail_in = hdrlen;
1800         while (deflate(&stream, 0) == Z_OK)
1801                 /* nothing */;
1802
1803         /* Then the data itself.. */
1804         stream.next_in = unpacked;
1805         stream.avail_in = len;
1806         while (deflate(&stream, Z_FINISH) == Z_OK)
1807                 /* nothing */;
1808         deflateEnd(&stream);
1809         free(unpacked);
1810
1811         *objsize = stream.total_out;
1812         return buf;
1813 }
1814
1815 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1816 {
1817         int retval;
1818         unsigned long objsize;
1819         void *buf = map_sha1_file(sha1, &objsize);
1820
1821         if (buf) {
1822                 retval = write_buffer(fd, buf, objsize);
1823                 munmap(buf, objsize);
1824                 return retval;
1825         }
1826
1827         buf = repack_object(sha1, &objsize);
1828         retval = write_buffer(fd, buf, objsize);
1829         free(buf);
1830         return retval;
1831 }
1832
1833 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1834                        size_t bufsize, size_t *bufposn)
1835 {
1836         char tmpfile[PATH_MAX];
1837         int local;
1838         z_stream stream;
1839         unsigned char real_sha1[20];
1840         unsigned char discard[4096];
1841         int ret;
1842         SHA_CTX c;
1843
1844         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1845
1846         local = mkstemp(tmpfile);
1847         if (local < 0) {
1848                 if (errno == EPERM)
1849                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1850                 else
1851                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1852         }
1853
1854         memset(&stream, 0, sizeof(stream));
1855
1856         inflateInit(&stream);
1857
1858         SHA1_Init(&c);
1859
1860         do {
1861                 ssize_t size;
1862                 if (*bufposn) {
1863                         stream.avail_in = *bufposn;
1864                         stream.next_in = (unsigned char *) buffer;
1865                         do {
1866                                 stream.next_out = discard;
1867                                 stream.avail_out = sizeof(discard);
1868                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1869                                 SHA1_Update(&c, discard, sizeof(discard) -
1870                                             stream.avail_out);
1871                         } while (stream.avail_in && ret == Z_OK);
1872                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1873                                 die("unable to write sha1 file");
1874                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1875                                 stream.avail_in);
1876                         *bufposn = stream.avail_in;
1877                         if (ret != Z_OK)
1878                                 break;
1879                 }
1880                 size = xread(fd, buffer + *bufposn, bufsize - *bufposn);
1881                 if (size <= 0) {
1882                         close(local);
1883                         unlink(tmpfile);
1884                         if (!size)
1885                                 return error("Connection closed?");
1886                         perror("Reading from connection");
1887                         return -1;
1888                 }
1889                 *bufposn += size;
1890         } while (1);
1891         inflateEnd(&stream);
1892
1893         close(local);
1894         SHA1_Final(real_sha1, &c);
1895         if (ret != Z_STREAM_END) {
1896                 unlink(tmpfile);
1897                 return error("File %s corrupted", sha1_to_hex(sha1));
1898         }
1899         if (hashcmp(sha1, real_sha1)) {
1900                 unlink(tmpfile);
1901                 return error("File %s has bad hash", sha1_to_hex(sha1));
1902         }
1903
1904         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1905 }
1906
1907 int has_pack_index(const unsigned char *sha1)
1908 {
1909         struct stat st;
1910         if (stat(sha1_pack_index_name(sha1), &st))
1911                 return 0;
1912         return 1;
1913 }
1914
1915 int has_pack_file(const unsigned char *sha1)
1916 {
1917         struct stat st;
1918         if (stat(sha1_pack_name(sha1), &st))
1919                 return 0;
1920         return 1;
1921 }
1922
1923 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
1924 {
1925         struct pack_entry e;
1926         return find_pack_entry(sha1, &e, ignore_packed);
1927 }
1928
1929 int has_sha1_file(const unsigned char *sha1)
1930 {
1931         struct stat st;
1932         struct pack_entry e;
1933
1934         if (find_pack_entry(sha1, &e, NULL))
1935                 return 1;
1936         return find_sha1_file(sha1, &st) ? 1 : 0;
1937 }
1938
1939 /*
1940  * reads from fd as long as possible into a supplied buffer of size bytes.
1941  * If necessary the buffer's size is increased using realloc()
1942  *
1943  * returns 0 if anything went fine and -1 otherwise
1944  *
1945  * NOTE: both buf and size may change, but even when -1 is returned
1946  * you still have to free() it yourself.
1947  */
1948 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1949 {
1950         char* buf = *return_buf;
1951         unsigned long size = *return_size;
1952         int iret;
1953         unsigned long off = 0;
1954
1955         do {
1956                 iret = xread(fd, buf + off, size - off);
1957                 if (iret > 0) {
1958                         off += iret;
1959                         if (off == size) {
1960                                 size *= 2;
1961                                 buf = xrealloc(buf, size);
1962                         }
1963                 }
1964         } while (iret > 0);
1965
1966         *return_buf = buf;
1967         *return_size = off;
1968
1969         if (iret < 0)
1970                 return -1;
1971         return 0;
1972 }
1973
1974 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1975 {
1976         unsigned long size = 4096;
1977         char *buf = xmalloc(size);
1978         int ret;
1979
1980         if (read_pipe(fd, &buf, &size)) {
1981                 free(buf);
1982                 return -1;
1983         }
1984
1985         if (!type)
1986                 type = blob_type;
1987         if (write_object)
1988                 ret = write_sha1_file(buf, size, type, sha1);
1989         else
1990                 ret = hash_sha1_file(buf, size, type, sha1);
1991         free(buf);
1992         return ret;
1993 }
1994
1995 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1996 {
1997         unsigned long size = st->st_size;
1998         void *buf;
1999         int ret;
2000
2001         buf = "";
2002         if (size)
2003                 buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2004         close(fd);
2005
2006         if (!type)
2007                 type = blob_type;
2008         if (write_object)
2009                 ret = write_sha1_file(buf, size, type, sha1);
2010         else
2011                 ret = hash_sha1_file(buf, size, type, sha1);
2012         if (size)
2013                 munmap(buf, size);
2014         return ret;
2015 }
2016
2017 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2018 {
2019         int fd;
2020         char *target;
2021
2022         switch (st->st_mode & S_IFMT) {
2023         case S_IFREG:
2024                 fd = open(path, O_RDONLY);
2025                 if (fd < 0)
2026                         return error("open(\"%s\"): %s", path,
2027                                      strerror(errno));
2028                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
2029                         return error("%s: failed to insert into database",
2030                                      path);
2031                 break;
2032         case S_IFLNK:
2033                 target = xmalloc(st->st_size+1);
2034                 if (readlink(path, target, st->st_size+1) != st->st_size) {
2035                         char *errstr = strerror(errno);
2036                         free(target);
2037                         return error("readlink(\"%s\"): %s", path,
2038                                      errstr);
2039                 }
2040                 if (!write_object)
2041                         hash_sha1_file(target, st->st_size, blob_type, sha1);
2042                 else if (write_sha1_file(target, st->st_size, blob_type, sha1))
2043                         return error("%s: failed to insert into database",
2044                                      path);
2045                 free(target);
2046                 break;
2047         default:
2048                 return error("%s: unsupported file type", path);
2049         }
2050         return 0;
2051 }