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 int 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                 return -1;
 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                         return error("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                 return error("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                 return error("cannot determine file descriptor flags");
 581         fd_flag |= FD_CLOEXEC;
 582         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 583                 return error("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                 return error("file %s is far too short to be a packfile", p->pack_name);
 588         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 589                 return error("file %s is not a GIT packfile", p->pack_name);
 590         if (!pack_version_ok(hdr.hdr_version))
 591                 return error("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                 return error("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                 return error("end of packfile %s is unavailable", p->pack_name);
 603         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 604                 return error("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                 return error("packfile %s does not match index", p->pack_name);
 608         return 0;
 609 }
 610
 611 static int in_window(struct pack_window *win, unsigned long offset)
 612 {
 613         /* We must promise at least 20 bytes (one hash) after the
 614          * offset is available from this window, otherwise the offset
 615          * is not actually in this window and a different window (which
 616          * has that one hash excess) must be used.  This is to support
 617          * the object header and delta base parsing routines below.
 618          */
 619         off_t win_off = win->offset;
 620         return win_off <= offset
 621                 && (offset + 20) <= (win_off + win->len);
 622 }
 623
 624 unsigned char* use_pack(struct packed_git *p,
 625                 struct pack_window **w_cursor,
 626                 unsigned long offset,
 627                 unsigned int *left)
 628 {
 629         struct pack_window *win = *w_cursor;
 630
 631         if (p->pack_fd == -1 && open_packed_git(p))
 632                 die("packfile %s cannot be accessed", p->pack_name);
 633
 634         /* Since packfiles end in a hash of their content and its
 635          * pointless to ask for an offset into the middle of that
 636          * hash, and the in_window function above wouldn't match
 637          * don't allow an offset too close to the end of the file.
 638          */
 639         if (offset > (p->pack_size - 20))
 640                 die("offset beyond end of packfile (truncated pack?)");
 641
 642         if (!win || !in_window(win, offset)) {
 643                 if (win)
 644                         win->inuse_cnt--;
 645                 for (win = p->windows; win; win = win->next) {
 646                         if (in_window(win, offset))
 647                                 break;
 648                 }
 649                 if (!win) {
 650                         if (!page_size)
 651                                 page_size = getpagesize();
 652                         win = xcalloc(1, sizeof(*win));
 653                         win->offset = (offset / page_size) * page_size;
 654                         win->len = p->pack_size - win->offset;
 655                         if (win->len > packed_git_window_size)
 656                                 win->len = packed_git_window_size;
 657                         pack_mapped += win->len;
 658                         while (packed_git_limit < pack_mapped
 659                                 && unuse_one_window(p))
 660                                 ; /* nothing */
 661                         win->base = xmmap(NULL, win->len,
 662                                 PROT_READ, MAP_PRIVATE,
 663                                 p->pack_fd, win->offset);
 664                         if (win->base == MAP_FAILED)
 665                                 die("packfile %s cannot be mapped: %s",
 666                                         p->pack_name,
 667                                         strerror(errno));
 668                         pack_mmap_calls++;
 669                         pack_open_windows++;
 670                         if (pack_mapped > peak_pack_mapped)
 671                                 peak_pack_mapped = pack_mapped;
 672                         if (pack_open_windows > peak_pack_open_windows)
 673                                 peak_pack_open_windows = pack_open_windows;
 674                         win->next = p->windows;
 675                         p->windows = win;
 676                 }
 677         }
 678         if (win != *w_cursor) {
 679                 win->last_used = pack_used_ctr++;
 680                 win->inuse_cnt++;
 681                 *w_cursor = win;
 682         }
 683         offset -= win->offset;
 684         if (left)
 685                 *left = win->len - offset;
 686         return win->base + offset;
 687 }
 688
 689 struct packed_git *add_packed_git(char *path, int path_len, int local)
 690 {
 691         struct stat st;
 692         struct packed_git *p;
 693         unsigned long idx_size;
 694         void *idx_map;
 695         unsigned char sha1[20];
 696
 697         if (check_packed_git_idx(path, &idx_size, &idx_map))
 698                 return NULL;
 699
 700         /* do we have a corresponding .pack file? */
 701         strcpy(path + path_len - 4, ".pack");
 702         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 703                 munmap(idx_map, idx_size);
 704                 return NULL;
 705         }
 706         /* ok, it looks sane as far as we can check without
 707          * actually mapping the pack file.
 708          */
 709         p = xmalloc(sizeof(*p) + path_len + 2);
 710         strcpy(p->pack_name, path);
 711         p->index_size = idx_size;
 712         p->pack_size = st.st_size;
 713         p->index_base = idx_map;
 714         p->next = NULL;
 715         p->windows = NULL;
 716         p->pack_fd = -1;
 717         p->pack_local = local;
 718         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 719                 hashcpy(p->sha1, sha1);
 720         return p;
 721 }
 722
 723 struct packed_git *parse_pack_index(unsigned char *sha1)
 724 {
 725         char *path = sha1_pack_index_name(sha1);
 726         return parse_pack_index_file(sha1, path);
 727 }
 728
 729 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 730 {
 731         struct packed_git *p;
 732         unsigned long idx_size;
 733         void *idx_map;
 734         char *path;
 735
 736         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 737                 return NULL;
 738
 739         path = sha1_pack_name(sha1);
 740
 741         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 742         strcpy(p->pack_name, path);
 743         p->index_size = idx_size;
 744         p->pack_size = 0;
 745         p->index_base = idx_map;
 746         p->next = NULL;
 747         p->windows = NULL;
 748         p->pack_fd = -1;
 749         hashcpy(p->sha1, sha1);
 750         return p;
 751 }
 752
 753 void install_packed_git(struct packed_git *pack)
 754 {
 755         pack->next = packed_git;
 756         packed_git = pack;
 757 }
 758
 759 static void prepare_packed_git_one(char *objdir, int local)
 760 {
 761         char path[PATH_MAX];
 762         int len;
 763         DIR *dir;
 764         struct dirent *de;
 765
 766         sprintf(path, "%s/pack", objdir);
 767         len = strlen(path);
 768         dir = opendir(path);
 769         if (!dir) {
 770                 if (errno != ENOENT)
 771                         error("unable to open object pack directory: %s: %s",
 772                               path, strerror(errno));
 773                 return;
 774         }
 775         path[len++] = '/';
 776         while ((de = readdir(dir)) != NULL) {
 777                 int namelen = strlen(de->d_name);
 778                 struct packed_git *p;
 779
 780                 if (!has_extension(de->d_name, ".idx"))
 781                         continue;
 782
 783                 /* Don't reopen a pack we already have. */
 784                 strcpy(path + len, de->d_name);
 785                 for (p = packed_git; p; p = p->next) {
 786                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 787                                 break;
 788                 }
 789                 if (p)
 790                         continue;
 791                 /* See if it really is a valid .idx file with corresponding
 792                  * .pack file that we can map.
 793                  */
 794                 p = add_packed_git(path, len + namelen, local);
 795                 if (!p)
 796                         continue;
 797                 install_packed_git(p);
 798         }
 799         closedir(dir);
 800 }
 801
 802 static int prepare_packed_git_run_once = 0;
 803 void prepare_packed_git(void)
 804 {
 805         struct alternate_object_database *alt;
 806
 807         if (prepare_packed_git_run_once)
 808                 return;
 809         prepare_packed_git_one(get_object_directory(), 1);
 810         prepare_alt_odb();
 811         for (alt = alt_odb_list; alt; alt = alt->next) {
 812                 alt->name[-1] = 0;
 813                 prepare_packed_git_one(alt->base, 0);
 814                 alt->name[-1] = '/';
 815         }
 816         prepare_packed_git_run_once = 1;
 817 }
 818
 819 void reprepare_packed_git(void)
 820 {
 821         prepare_packed_git_run_once = 0;
 822         prepare_packed_git();
 823 }
 824
 825 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 826 {
 827         unsigned char real_sha1[20];
 828         hash_sha1_file(map, size, type, real_sha1);
 829         return hashcmp(sha1, real_sha1) ? -1 : 0;
 830 }
 831
 832 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 833 {
 834         struct stat st;
 835         void *map;
 836         int fd;
 837         char *filename = find_sha1_file(sha1, &st);
 838
 839         if (!filename) {
 840                 return NULL;
 841         }
 842
 843         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 844         if (fd < 0) {
 845                 /* See if it works without O_NOATIME */
 846                 switch (sha1_file_open_flag) {
 847                 default:
 848                         fd = open(filename, O_RDONLY);
 849                         if (fd >= 0)
 850                                 break;
 851                 /* Fallthrough */
 852                 case 0:
 853                         return NULL;
 854                 }
 855
 856                 /* If it failed once, it will probably fail again.
 857                  * Stop using O_NOATIME
 858                  */
 859                 sha1_file_open_flag = 0;
 860         }
 861         map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 862         close(fd);
 863         *size = st.st_size;
 864         return map;
 865 }
 866
 867 int legacy_loose_object(unsigned char *map)
 868 {
 869         unsigned int word;
 870
 871         /*
 872          * Is it a zlib-compressed buffer? If so, the first byte
 873          * must be 0x78 (15-bit window size, deflated), and the
 874          * first 16-bit word is evenly divisible by 31
 875          */
 876         word = (map[0] << 8) + map[1];
 877         if (map[0] == 0x78 && !(word % 31))
 878                 return 1;
 879         else
 880                 return 0;
 881 }
 882
 883 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 884 {
 885         unsigned shift;
 886         unsigned char c;
 887         unsigned long size;
 888         unsigned long used = 0;
 889
 890         c = buf[used++];
 891         *type = (c >> 4) & 7;
 892         size = c & 15;
 893         shift = 4;
 894         while (c & 0x80) {
 895                 if (len <= used)
 896                         return 0;
 897                 if (sizeof(long) * 8 <= shift)
 898                         return 0;
 899                 c = buf[used++];
 900                 size += (c & 0x7f) << shift;
 901                 shift += 7;
 902         }
 903         *sizep = size;
 904         return used;
 905 }
 906
 907 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 908 {
 909         unsigned long size, used;
 910         static const char valid_loose_object_type[8] = {
 911                 0, /* OBJ_EXT */
 912                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 913                 0, /* "delta" and others are invalid in a loose object */
 914         };
 915         enum object_type type;
 916
 917         /* Get the data stream */
 918         memset(stream, 0, sizeof(*stream));
 919         stream->next_in = map;
 920         stream->avail_in = mapsize;
 921         stream->next_out = buffer;
 922         stream->avail_out = bufsiz;
 923
 924         if (legacy_loose_object(map)) {
 925                 inflateInit(stream);
 926                 return inflate(stream, 0);
 927         }
 928
 929         used = unpack_object_header_gently(map, mapsize, &type, &size);
 930         if (!used || !valid_loose_object_type[type])
 931                 return -1;
 932         map += used;
 933         mapsize -= used;
 934
 935         /* Set up the stream for the rest.. */
 936         stream->next_in = map;
 937         stream->avail_in = mapsize;
 938         inflateInit(stream);
 939
 940         /* And generate the fake traditional header */
 941         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 942                                          type_names[type], size);
 943         return 0;
 944 }
 945
 946 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 947 {
 948         int bytes = strlen(buffer) + 1;
 949         unsigned char *buf = xmalloc(1+size);
 950         unsigned long n;
 951
 952         n = stream->total_out - bytes;
 953         if (n > size)
 954                 n = size;
 955         memcpy(buf, (char *) buffer + bytes, n);
 956         bytes = n;
 957         if (bytes < size) {
 958                 stream->next_out = buf + bytes;
 959                 stream->avail_out = size - bytes;
 960                 while (inflate(stream, Z_FINISH) == Z_OK)
 961                         /* nothing */;
 962         }
 963         buf[size] = 0;
 964         inflateEnd(stream);
 965         return buf;
 966 }
 967
 968 /*
 969  * We used to just use "sscanf()", but that's actually way
 970  * too permissive for what we want to check. So do an anal
 971  * object header parse by hand.
 972  */
 973 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 974 {
 975         int i;
 976         unsigned long size;
 977
 978         /*
 979          * The type can be at most ten bytes (including the
 980          * terminating '\0' that we add), and is followed by
 981          * a space.
 982          */
 983         i = 10;
 984         for (;;) {
 985                 char c = *hdr++;
 986                 if (c == ' ')
 987                         break;
 988                 if (!--i)
 989                         return -1;
 990                 *type++ = c;
 991         }
 992         *type = 0;
 993
 994         /*
 995          * The length must follow immediately, and be in canonical
 996          * decimal format (ie "010" is not valid).
 997          */
 998         size = *hdr++ - '0';
 999         if (size > 9)
1000                 return -1;
1001         if (size) {
1002                 for (;;) {
1003                         unsigned long c = *hdr - '0';
1004                         if (c > 9)
1005                                 break;
1006                         hdr++;
1007                         size = size * 10 + c;
1008                 }
1009         }
1010         *sizep = size;
1011
1012         /*
1013          * The length must be followed by a zero byte
1014          */
1015         return *hdr ? -1 : 0;
1016 }
1017
1018 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
1019 {
1020         int ret;
1021         z_stream stream;
1022         char hdr[8192];
1023
1024         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1025         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
1026                 return NULL;
1027
1028         return unpack_sha1_rest(&stream, hdr, *size);
1029 }
1030
1031 static unsigned long get_delta_base(struct packed_git *p,
1032                                     struct pack_window **w_curs,
1033                                     unsigned long offset,
1034                                     enum object_type kind,
1035                                     unsigned long delta_obj_offset,
1036                                     unsigned long *base_obj_offset)
1037 {
1038         unsigned char *base_info = use_pack(p, w_curs, offset, NULL);
1039         unsigned long base_offset;
1040
1041         /* use_pack() assured us we have [base_info, base_info + 20)
1042          * as a range that we can look at without walking off the
1043          * end of the mapped window.  Its actually the hash size
1044          * that is assured.  An OFS_DELTA longer than the hash size
1045          * is stupid, as then a REF_DELTA would be smaller to store.
1046          */
1047         if (kind == OBJ_OFS_DELTA) {
1048                 unsigned used = 0;
1049                 unsigned char c = base_info[used++];
1050                 base_offset = c & 127;
1051                 while (c & 128) {
1052                         base_offset += 1;
1053                         if (!base_offset || base_offset & ~(~0UL >> 7))
1054                                 die("offset value overflow for delta base object");
1055                         c = base_info[used++];
1056                         base_offset = (base_offset << 7) + (c & 127);
1057                 }
1058                 base_offset = delta_obj_offset - base_offset;
1059                 if (base_offset >= delta_obj_offset)
1060                         die("delta base offset out of bound");
1061                 offset += used;
1062         } else if (kind == OBJ_REF_DELTA) {
1063                 /* The base entry _must_ be in the same pack */
1064                 base_offset = find_pack_entry_one(base_info, p);
1065                 if (!base_offset)
1066                         die("failed to find delta-pack base object %s",
1067                                 sha1_to_hex(base_info));
1068                 offset += 20;
1069         } else
1070                 die("I am totally screwed");
1071         *base_obj_offset = base_offset;
1072         return offset;
1073 }
1074
1075 /* forward declaration for a mutually recursive function */
1076 static int packed_object_info(struct packed_git *p, unsigned long offset,
1077                               char *type, unsigned long *sizep);
1078
1079 static int packed_delta_info(struct packed_git *p,
1080                              struct pack_window **w_curs,
1081                              unsigned long offset,
1082                              enum object_type kind,
1083                              unsigned long obj_offset,
1084                              char *type,
1085                              unsigned long *sizep)
1086 {
1087         unsigned long base_offset;
1088
1089         offset = get_delta_base(p, w_curs, offset, kind,
1090                 obj_offset, &base_offset);
1091
1092         /* We choose to only get the type of the base object and
1093          * ignore potentially corrupt pack file that expects the delta
1094          * based on a base with a wrong size.  This saves tons of
1095          * inflate() calls.
1096          */
1097         if (packed_object_info(p, base_offset, type, NULL))
1098                 die("cannot get info for delta-pack base");
1099
1100         if (sizep) {
1101                 const unsigned char *data;
1102                 unsigned char delta_head[20], *in;
1103                 unsigned long result_size;
1104                 z_stream stream;
1105                 int st;
1106
1107                 memset(&stream, 0, sizeof(stream));
1108                 stream.next_out = delta_head;
1109                 stream.avail_out = sizeof(delta_head);
1110
1111                 inflateInit(&stream);
1112                 do {
1113                         in = use_pack(p, w_curs, offset, &stream.avail_in);
1114                         stream.next_in = in;
1115                         st = inflate(&stream, Z_FINISH);
1116                         offset += stream.next_in - in;
1117                 } while ((st == Z_OK || st == Z_BUF_ERROR)
1118                         && stream.total_out < sizeof(delta_head));
1119                 inflateEnd(&stream);
1120                 if ((st != Z_STREAM_END) &&
1121                     stream.total_out != sizeof(delta_head))
1122                         die("delta data unpack-initial failed");
1123
1124                 /* Examine the initial part of the delta to figure out
1125                  * the result size.
1126                  */
1127                 data = delta_head;
1128
1129                 /* ignore base size */
1130                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1131
1132                 /* Read the result size */
1133                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1134                 *sizep = result_size;
1135         }
1136         return 0;
1137 }
1138
1139 static unsigned long unpack_object_header(struct packed_git *p,
1140                 struct pack_window **w_curs,
1141                 unsigned long offset,
1142                 enum object_type *type,
1143                 unsigned long *sizep)
1144 {
1145         unsigned char *base;
1146         unsigned int left;
1147         unsigned long used;
1148
1149         /* use_pack() assures us we have [base, base + 20) available
1150          * as a range that we can look at at.  (Its actually the hash
1151          * size that is assurred.)  With our object header encoding
1152          * the maximum deflated object size is 2^137, which is just
1153          * insane, so we know won't exceed what we have been given.
1154          */
1155         base = use_pack(p, w_curs, offset, &left);
1156         used = unpack_object_header_gently(base, left, type, sizep);
1157         if (!used)
1158                 die("object offset outside of pack file");
1159
1160         return offset + used;
1161 }
1162
1163 void packed_object_info_detail(struct packed_git *p,
1164                                unsigned long offset,
1165                                char *type,
1166                                unsigned long *size,
1167                                unsigned long *store_size,
1168                                unsigned int *delta_chain_length,
1169                                unsigned char *base_sha1)
1170 {
1171         struct pack_window *w_curs = NULL;
1172         unsigned long obj_offset, val;
1173         unsigned char *next_sha1;
1174         enum object_type kind;
1175
1176         *delta_chain_length = 0;
1177         obj_offset = offset;
1178         offset = unpack_object_header(p, &w_curs, offset, &kind, size);
1179
1180         for (;;) {
1181                 switch (kind) {
1182                 default:
1183                         die("pack %s contains unknown object type %d",
1184                             p->pack_name, kind);
1185                 case OBJ_COMMIT:
1186                 case OBJ_TREE:
1187                 case OBJ_BLOB:
1188                 case OBJ_TAG:
1189                         strcpy(type, type_names[kind]);
1190                         *store_size = 0; /* notyet */
1191                         unuse_pack(&w_curs);
1192                         return;
1193                 case OBJ_OFS_DELTA:
1194                         get_delta_base(p, &w_curs, offset, kind,
1195                                 obj_offset, &offset);
1196                         if (*delta_chain_length == 0) {
1197                                 /* TODO: find base_sha1 as pointed by offset */
1198                         }
1199                         break;
1200                 case OBJ_REF_DELTA:
1201                         next_sha1 = use_pack(p, &w_curs, offset, NULL);
1202                         if (*delta_chain_length == 0)
1203                                 hashcpy(base_sha1, next_sha1);
1204                         offset = find_pack_entry_one(next_sha1, p);
1205                         break;
1206                 }
1207                 obj_offset = offset;
1208                 offset = unpack_object_header(p, &w_curs, offset, &kind, &val);
1209                 (*delta_chain_length)++;
1210         }
1211 }
1212
1213 static int packed_object_info(struct packed_git *p, unsigned long offset,
1214                               char *type, unsigned long *sizep)
1215 {
1216         struct pack_window *w_curs = NULL;
1217         unsigned long size, obj_offset = offset;
1218         enum object_type kind;
1219         int r;
1220
1221         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1222
1223         switch (kind) {
1224         case OBJ_OFS_DELTA:
1225         case OBJ_REF_DELTA:
1226                 r = packed_delta_info(p, &w_curs, offset, kind,
1227                         obj_offset, type, sizep);
1228                 unuse_pack(&w_curs);
1229                 return r;
1230         case OBJ_COMMIT:
1231         case OBJ_TREE:
1232         case OBJ_BLOB:
1233         case OBJ_TAG:
1234                 strcpy(type, type_names[kind]);
1235                 unuse_pack(&w_curs);
1236                 break;
1237         default:
1238                 die("pack %s contains unknown object type %d",
1239                     p->pack_name, kind);
1240         }
1241         if (sizep)
1242                 *sizep = size;
1243         return 0;
1244 }
1245
1246 static void *unpack_compressed_entry(struct packed_git *p,
1247                                     struct pack_window **w_curs,
1248                                     unsigned long offset,
1249                                     unsigned long size)
1250 {
1251         int st;
1252         z_stream stream;
1253         unsigned char *buffer, *in;
1254
1255         buffer = xmalloc(size + 1);
1256         buffer[size] = 0;
1257         memset(&stream, 0, sizeof(stream));
1258         stream.next_out = buffer;
1259         stream.avail_out = size;
1260
1261         inflateInit(&stream);
1262         do {
1263                 in = use_pack(p, w_curs, offset, &stream.avail_in);
1264                 stream.next_in = in;
1265                 st = inflate(&stream, Z_FINISH);
1266                 offset += stream.next_in - in;
1267         } while (st == Z_OK || st == Z_BUF_ERROR);
1268         inflateEnd(&stream);
1269         if ((st != Z_STREAM_END) || stream.total_out != size) {
1270                 free(buffer);
1271                 return NULL;
1272         }
1273
1274         return buffer;
1275 }
1276
1277 static void *unpack_delta_entry(struct packed_git *p,
1278                                 struct pack_window **w_curs,
1279                                 unsigned long offset,
1280                                 unsigned long delta_size,
1281                                 enum object_type kind,
1282                                 unsigned long obj_offset,
1283                                 char *type,
1284                                 unsigned long *sizep)
1285 {
1286         void *delta_data, *result, *base;
1287         unsigned long result_size, base_size, base_offset;
1288
1289         offset = get_delta_base(p, w_curs, offset, kind,
1290                 obj_offset, &base_offset);
1291         base = unpack_entry(p, base_offset, type, &base_size);
1292         if (!base)
1293                 die("failed to read delta base object at %lu from %s",
1294                     base_offset, p->pack_name);
1295
1296         delta_data = unpack_compressed_entry(p, w_curs, offset, delta_size);
1297         result = patch_delta(base, base_size,
1298                              delta_data, delta_size,
1299                              &result_size);
1300         if (!result)
1301                 die("failed to apply delta");
1302         free(delta_data);
1303         free(base);
1304         *sizep = result_size;
1305         return result;
1306 }
1307
1308 void *unpack_entry(struct packed_git *p, unsigned long offset,
1309                           char *type, unsigned long *sizep)
1310 {
1311         struct pack_window *w_curs = NULL;
1312         unsigned long size, obj_offset = offset;
1313         enum object_type kind;
1314         void *retval;
1315
1316         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1317         switch (kind) {
1318         case OBJ_OFS_DELTA:
1319         case OBJ_REF_DELTA:
1320                 retval = unpack_delta_entry(p, &w_curs, offset, size,
1321                         kind, obj_offset, type, sizep);
1322                 break;
1323         case OBJ_COMMIT:
1324         case OBJ_TREE:
1325         case OBJ_BLOB:
1326         case OBJ_TAG:
1327                 strcpy(type, type_names[kind]);
1328                 *sizep = size;
1329                 retval = unpack_compressed_entry(p, &w_curs, offset, size);
1330                 break;
1331         default:
1332                 die("unknown object type %i in %s", kind, p->pack_name);
1333         }
1334         unuse_pack(&w_curs);
1335         return retval;
1336 }
1337
1338 int num_packed_objects(const struct packed_git *p)
1339 {
1340         /* See check_packed_git_idx() */
1341         return (p->index_size - 20 - 20 - 4*256) / 24;
1342 }
1343
1344 int nth_packed_object_sha1(const struct packed_git *p, int n,
1345                            unsigned char* sha1)
1346 {
1347         void *index = p->index_base + 256;
1348         if (n < 0 || num_packed_objects(p) <= n)
1349                 return -1;
1350         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1351         return 0;
1352 }
1353
1354 unsigned long find_pack_entry_one(const unsigned char *sha1,
1355                                   struct packed_git *p)
1356 {
1357         uint32_t *level1_ofs = p->index_base;
1358         int hi = ntohl(level1_ofs[*sha1]);
1359         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1360         void *index = p->index_base + 256;
1361
1362         do {
1363                 int mi = (lo + hi) / 2;
1364                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1365                 if (!cmp)
1366                         return ntohl(*((uint32_t *)((char *)index + (24 * mi))));
1367                 if (cmp > 0)
1368                         hi = mi;
1369                 else
1370                         lo = mi+1;
1371         } while (lo < hi);
1372         return 0;
1373 }
1374
1375 static int matches_pack_name(struct packed_git *p, const char *ig)
1376 {
1377         const char *last_c, *c;
1378
1379         if (!strcmp(p->pack_name, ig))
1380                 return 0;
1381
1382         for (c = p->pack_name, last_c = c; *c;)
1383                 if (*c == '/')
1384                         last_c = ++c;
1385                 else
1386                         ++c;
1387         if (!strcmp(last_c, ig))
1388                 return 0;
1389
1390         return 1;
1391 }
1392
1393 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1394 {
1395         struct packed_git *p;
1396         unsigned long offset;
1397
1398         prepare_packed_git();
1399
1400         for (p = packed_git; p; p = p->next) {
1401                 if (ignore_packed) {
1402                         const char **ig;
1403                         for (ig = ignore_packed; *ig; ig++)
1404                                 if (!matches_pack_name(p, *ig))
1405                                         break;
1406                         if (*ig)
1407                                 continue;
1408                 }
1409                 offset = find_pack_entry_one(sha1, p);
1410                 if (offset) {
1411                         /*
1412                          * We are about to tell the caller where they can
1413                          * locate the requested object.  We better make
1414                          * sure the packfile is still here and can be
1415                          * accessed before supplying that answer, as
1416                          * it may have been deleted since the index
1417                          * was loaded!
1418                          */
1419                         if (p->pack_fd == -1 && open_packed_git(p)) {
1420                                 error("packfile %s cannot be accessed", p->pack_name);
1421                                 continue;
1422                         }
1423                         e->offset = offset;
1424                         e->p = p;
1425                         hashcpy(e->sha1, sha1);
1426                         return 1;
1427                 }
1428         }
1429         return 0;
1430 }
1431
1432 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1433                                   struct packed_git *packs)
1434 {
1435         struct packed_git *p;
1436
1437         for (p = packs; p; p = p->next) {
1438                 if (find_pack_entry_one(sha1, p))
1439                         return p;
1440         }
1441         return NULL;
1442
1443 }
1444
1445 static int sha1_loose_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1446 {
1447         int status;
1448         unsigned long mapsize, size;
1449         void *map;
1450         z_stream stream;
1451         char hdr[128];
1452
1453         map = map_sha1_file(sha1, &mapsize);
1454         if (!map)
1455                 return error("unable to find %s", sha1_to_hex(sha1));
1456         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1457                 status = error("unable to unpack %s header",
1458                                sha1_to_hex(sha1));
1459         if (parse_sha1_header(hdr, type, &size) < 0)
1460                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1461         else {
1462                 status = 0;
1463                 if (sizep)
1464                         *sizep = size;
1465         }
1466         inflateEnd(&stream);
1467         munmap(map, mapsize);
1468         return status;
1469 }
1470
1471 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1472 {
1473         struct pack_entry e;
1474
1475         if (!find_pack_entry(sha1, &e, NULL)) {
1476                 reprepare_packed_git();
1477                 if (!find_pack_entry(sha1, &e, NULL))
1478                         return sha1_loose_object_info(sha1, type, sizep);
1479         }
1480         return packed_object_info(e.p, e.offset, type, sizep);
1481 }
1482
1483 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1484 {
1485         struct pack_entry e;
1486
1487         if (!find_pack_entry(sha1, &e, NULL))
1488                 return NULL;
1489         else
1490                 return unpack_entry(e.p, e.offset, type, size);
1491 }
1492
1493 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1494 {
1495         unsigned long mapsize;
1496         void *map, *buf;
1497
1498         buf = read_packed_sha1(sha1, type, size);
1499         if (buf)
1500                 return buf;
1501         map = map_sha1_file(sha1, &mapsize);
1502         if (map) {
1503                 buf = unpack_sha1_file(map, mapsize, type, size);
1504                 munmap(map, mapsize);
1505                 return buf;
1506         }
1507         reprepare_packed_git();
1508         return read_packed_sha1(sha1, type, size);
1509 }
1510
1511 void *read_object_with_reference(const unsigned char *sha1,
1512                                  const char *required_type,
1513                                  unsigned long *size,
1514                                  unsigned char *actual_sha1_return)
1515 {
1516         char type[20];
1517         void *buffer;
1518         unsigned long isize;
1519         unsigned char actual_sha1[20];
1520
1521         hashcpy(actual_sha1, sha1);
1522         while (1) {
1523                 int ref_length = -1;
1524                 const char *ref_type = NULL;
1525
1526                 buffer = read_sha1_file(actual_sha1, type, &isize);
1527                 if (!buffer)
1528                         return NULL;
1529                 if (!strcmp(type, required_type)) {
1530                         *size = isize;
1531                         if (actual_sha1_return)
1532                                 hashcpy(actual_sha1_return, actual_sha1);
1533                         return buffer;
1534                 }
1535                 /* Handle references */
1536                 else if (!strcmp(type, commit_type))
1537                         ref_type = "tree ";
1538                 else if (!strcmp(type, tag_type))
1539                         ref_type = "object ";
1540                 else {
1541                         free(buffer);
1542                         return NULL;
1543                 }
1544                 ref_length = strlen(ref_type);
1545
1546                 if (memcmp(buffer, ref_type, ref_length) ||
1547                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1548                         free(buffer);
1549                         return NULL;
1550                 }
1551                 free(buffer);
1552                 /* Now we have the ID of the referred-to object in
1553                  * actual_sha1.  Check again. */
1554         }
1555 }
1556
1557 static void write_sha1_file_prepare(void *buf, unsigned long len,
1558                                     const char *type, unsigned char *sha1,
1559                                     unsigned char *hdr, int *hdrlen)
1560 {
1561         SHA_CTX c;
1562
1563         /* Generate the header */
1564         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1565
1566         /* Sha1.. */
1567         SHA1_Init(&c);
1568         SHA1_Update(&c, hdr, *hdrlen);
1569         SHA1_Update(&c, buf, len);
1570         SHA1_Final(sha1, &c);
1571 }
1572
1573 /*
1574  * Link the tempfile to the final place, possibly creating the
1575  * last directory level as you do so.
1576  *
1577  * Returns the errno on failure, 0 on success.
1578  */
1579 static int link_temp_to_file(const char *tmpfile, const char *filename)
1580 {
1581         int ret;
1582         char *dir;
1583
1584         if (!link(tmpfile, filename))
1585                 return 0;
1586
1587         /*
1588          * Try to mkdir the last path component if that failed.
1589          *
1590          * Re-try the "link()" regardless of whether the mkdir
1591          * succeeds, since a race might mean that somebody
1592          * else succeeded.
1593          */
1594         ret = errno;
1595         dir = strrchr(filename, '/');
1596         if (dir) {
1597                 *dir = 0;
1598                 if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1599                         *dir = '/';
1600                         return -2;
1601                 }
1602                 *dir = '/';
1603                 if (!link(tmpfile, filename))
1604                         return 0;
1605                 ret = errno;
1606         }
1607         return ret;
1608 }
1609
1610 /*
1611  * Move the just written object into its final resting place
1612  */
1613 int move_temp_to_file(const char *tmpfile, const char *filename)
1614 {
1615         int ret = link_temp_to_file(tmpfile, filename);
1616
1617         /*
1618          * Coda hack - coda doesn't like cross-directory links,
1619          * so we fall back to a rename, which will mean that it
1620          * won't be able to check collisions, but that's not a
1621          * big deal.
1622          *
1623          * The same holds for FAT formatted media.
1624          *
1625          * When this succeeds, we just return 0. We have nothing
1626          * left to unlink.
1627          */
1628         if (ret && ret != EEXIST) {
1629                 if (!rename(tmpfile, filename))
1630                         return 0;
1631                 ret = errno;
1632         }
1633         unlink(tmpfile);
1634         if (ret) {
1635                 if (ret != EEXIST) {
1636                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1637                 }
1638                 /* FIXME!!! Collision check here ? */
1639         }
1640
1641         return 0;
1642 }
1643
1644 static int write_buffer(int fd, const void *buf, size_t len)
1645 {
1646         if (write_in_full(fd, buf, len) < 0)
1647                 return error("file write error (%s)", strerror(errno));
1648         return 0;
1649 }
1650
1651 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1652 {
1653         int hdr_len;
1654         unsigned char c;
1655
1656         c = (type << 4) | (len & 15);
1657         len >>= 4;
1658         hdr_len = 1;
1659         while (len) {
1660                 *hdr++ = c | 0x80;
1661                 hdr_len++;
1662                 c = (len & 0x7f);
1663                 len >>= 7;
1664         }
1665         *hdr = c;
1666         return hdr_len;
1667 }
1668
1669 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1670 {
1671         int obj_type, hdr;
1672
1673         if (use_legacy_headers) {
1674                 while (deflate(stream, 0) == Z_OK)
1675                         /* nothing */;
1676                 return;
1677         }
1678         if (!strcmp(type, blob_type))
1679                 obj_type = OBJ_BLOB;
1680         else if (!strcmp(type, tree_type))
1681                 obj_type = OBJ_TREE;
1682         else if (!strcmp(type, commit_type))
1683                 obj_type = OBJ_COMMIT;
1684         else if (!strcmp(type, tag_type))
1685                 obj_type = OBJ_TAG;
1686         else
1687                 die("trying to generate bogus object of type '%s'", type);
1688         hdr = write_binary_header(stream->next_out, obj_type, len);
1689         stream->total_out = hdr;
1690         stream->next_out += hdr;
1691         stream->avail_out -= hdr;
1692 }
1693
1694 int hash_sha1_file(void *buf, unsigned long len, const char *type,
1695                    unsigned char *sha1)
1696 {
1697         unsigned char hdr[50];
1698         int hdrlen;
1699         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1700         return 0;
1701 }
1702
1703 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1704 {
1705         int size;
1706         unsigned char *compressed;
1707         z_stream stream;
1708         unsigned char sha1[20];
1709         char *filename;
1710         static char tmpfile[PATH_MAX];
1711         unsigned char hdr[50];
1712         int fd, hdrlen;
1713
1714         /* Normally if we have it in the pack then we do not bother writing
1715          * it out into .git/objects/??/?{38} file.
1716          */
1717         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1718         filename = sha1_file_name(sha1);
1719         if (returnsha1)
1720                 hashcpy(returnsha1, sha1);
1721         if (has_sha1_file(sha1))
1722                 return 0;
1723         fd = open(filename, O_RDONLY);
1724         if (fd >= 0) {
1725                 /*
1726                  * FIXME!!! We might do collision checking here, but we'd
1727                  * need to uncompress the old file and check it. Later.
1728                  */
1729                 close(fd);
1730                 return 0;
1731         }
1732
1733         if (errno != ENOENT) {
1734                 return error("sha1 file %s: %s\n", filename, strerror(errno));
1735         }
1736
1737         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1738
1739         fd = mkstemp(tmpfile);
1740         if (fd < 0) {
1741                 if (errno == EPERM)
1742                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1743                 else
1744                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1745         }
1746
1747         /* Set it up */
1748         memset(&stream, 0, sizeof(stream));
1749         deflateInit(&stream, zlib_compression_level);
1750         size = 8 + deflateBound(&stream, len+hdrlen);
1751         compressed = xmalloc(size);
1752
1753         /* Compress it */
1754         stream.next_out = compressed;
1755         stream.avail_out = size;
1756
1757         /* First header.. */
1758         stream.next_in = hdr;
1759         stream.avail_in = hdrlen;
1760         setup_object_header(&stream, type, len);
1761
1762         /* Then the data itself.. */
1763         stream.next_in = buf;
1764         stream.avail_in = len;
1765         while (deflate(&stream, Z_FINISH) == Z_OK)
1766                 /* nothing */;
1767         deflateEnd(&stream);
1768         size = stream.total_out;
1769
1770         if (write_buffer(fd, compressed, size) < 0)
1771                 die("unable to write sha1 file");
1772         fchmod(fd, 0444);
1773         close(fd);
1774         free(compressed);
1775
1776         return move_temp_to_file(tmpfile, filename);
1777 }
1778
1779 /*
1780  * We need to unpack and recompress the object for writing
1781  * it out to a different file.
1782  */
1783 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1784 {
1785         size_t size;
1786         z_stream stream;
1787         unsigned char *unpacked;
1788         unsigned long len;
1789         char type[20];
1790         char hdr[50];
1791         int hdrlen;
1792         void *buf;
1793
1794         /* need to unpack and recompress it by itself */
1795         unpacked = read_packed_sha1(sha1, type, &len);
1796         if (!unpacked)
1797                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1798
1799         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1800
1801         /* Set it up */
1802         memset(&stream, 0, sizeof(stream));
1803         deflateInit(&stream, zlib_compression_level);
1804         size = deflateBound(&stream, len + hdrlen);
1805         buf = xmalloc(size);
1806
1807         /* Compress it */
1808         stream.next_out = buf;
1809         stream.avail_out = size;
1810
1811         /* First header.. */
1812         stream.next_in = (void *)hdr;
1813         stream.avail_in = hdrlen;
1814         while (deflate(&stream, 0) == Z_OK)
1815                 /* nothing */;
1816
1817         /* Then the data itself.. */
1818         stream.next_in = unpacked;
1819         stream.avail_in = len;
1820         while (deflate(&stream, Z_FINISH) == Z_OK)
1821                 /* nothing */;
1822         deflateEnd(&stream);
1823         free(unpacked);
1824
1825         *objsize = stream.total_out;
1826         return buf;
1827 }
1828
1829 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1830 {
1831         int retval;
1832         unsigned long objsize;
1833         void *buf = map_sha1_file(sha1, &objsize);
1834
1835         if (buf) {
1836                 retval = write_buffer(fd, buf, objsize);
1837                 munmap(buf, objsize);
1838                 return retval;
1839         }
1840
1841         buf = repack_object(sha1, &objsize);
1842         retval = write_buffer(fd, buf, objsize);
1843         free(buf);
1844         return retval;
1845 }
1846
1847 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1848                        size_t bufsize, size_t *bufposn)
1849 {
1850         char tmpfile[PATH_MAX];
1851         int local;
1852         z_stream stream;
1853         unsigned char real_sha1[20];
1854         unsigned char discard[4096];
1855         int ret;
1856         SHA_CTX c;
1857
1858         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1859
1860         local = mkstemp(tmpfile);
1861         if (local < 0) {
1862                 if (errno == EPERM)
1863                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1864                 else
1865                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1866         }
1867
1868         memset(&stream, 0, sizeof(stream));
1869
1870         inflateInit(&stream);
1871
1872         SHA1_Init(&c);
1873
1874         do {
1875                 ssize_t size;
1876                 if (*bufposn) {
1877                         stream.avail_in = *bufposn;
1878                         stream.next_in = (unsigned char *) buffer;
1879                         do {
1880                                 stream.next_out = discard;
1881                                 stream.avail_out = sizeof(discard);
1882                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1883                                 SHA1_Update(&c, discard, sizeof(discard) -
1884                                             stream.avail_out);
1885                         } while (stream.avail_in && ret == Z_OK);
1886                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1887                                 die("unable to write sha1 file");
1888                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1889                                 stream.avail_in);
1890                         *bufposn = stream.avail_in;
1891                         if (ret != Z_OK)
1892                                 break;
1893                 }
1894                 size = xread(fd, buffer + *bufposn, bufsize - *bufposn);
1895                 if (size <= 0) {
1896                         close(local);
1897                         unlink(tmpfile);
1898                         if (!size)
1899                                 return error("Connection closed?");
1900                         perror("Reading from connection");
1901                         return -1;
1902                 }
1903                 *bufposn += size;
1904         } while (1);
1905         inflateEnd(&stream);
1906
1907         close(local);
1908         SHA1_Final(real_sha1, &c);
1909         if (ret != Z_STREAM_END) {
1910                 unlink(tmpfile);
1911                 return error("File %s corrupted", sha1_to_hex(sha1));
1912         }
1913         if (hashcmp(sha1, real_sha1)) {
1914                 unlink(tmpfile);
1915                 return error("File %s has bad hash", sha1_to_hex(sha1));
1916         }
1917
1918         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1919 }
1920
1921 int has_pack_index(const unsigned char *sha1)
1922 {
1923         struct stat st;
1924         if (stat(sha1_pack_index_name(sha1), &st))
1925                 return 0;
1926         return 1;
1927 }
1928
1929 int has_pack_file(const unsigned char *sha1)
1930 {
1931         struct stat st;
1932         if (stat(sha1_pack_name(sha1), &st))
1933                 return 0;
1934         return 1;
1935 }
1936
1937 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
1938 {
1939         struct pack_entry e;
1940         return find_pack_entry(sha1, &e, ignore_packed);
1941 }
1942
1943 int has_sha1_file(const unsigned char *sha1)
1944 {
1945         struct stat st;
1946         struct pack_entry e;
1947
1948         if (find_pack_entry(sha1, &e, NULL))
1949                 return 1;
1950         return find_sha1_file(sha1, &st) ? 1 : 0;
1951 }
1952
1953 /*
1954  * reads from fd as long as possible into a supplied buffer of size bytes.
1955  * If necessary the buffer's size is increased using realloc()
1956  *
1957  * returns 0 if anything went fine and -1 otherwise
1958  *
1959  * NOTE: both buf and size may change, but even when -1 is returned
1960  * you still have to free() it yourself.
1961  */
1962 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1963 {
1964         char* buf = *return_buf;
1965         unsigned long size = *return_size;
1966         int iret;
1967         unsigned long off = 0;
1968
1969         do {
1970                 iret = xread(fd, buf + off, size - off);
1971                 if (iret > 0) {
1972                         off += iret;
1973                         if (off == size) {
1974                                 size *= 2;
1975                                 buf = xrealloc(buf, size);
1976                         }
1977                 }
1978         } while (iret > 0);
1979
1980         *return_buf = buf;
1981         *return_size = off;
1982
1983         if (iret < 0)
1984                 return -1;
1985         return 0;
1986 }
1987
1988 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1989 {
1990         unsigned long size = 4096;
1991         char *buf = xmalloc(size);
1992         int ret;
1993
1994         if (read_pipe(fd, &buf, &size)) {
1995                 free(buf);
1996                 return -1;
1997         }
1998
1999         if (!type)
2000                 type = blob_type;
2001         if (write_object)
2002                 ret = write_sha1_file(buf, size, type, sha1);
2003         else
2004                 ret = hash_sha1_file(buf, size, type, sha1);
2005         free(buf);
2006         return ret;
2007 }
2008
2009 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
2010 {
2011         unsigned long size = st->st_size;
2012         void *buf;
2013         int ret;
2014
2015         buf = "";
2016         if (size)
2017                 buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2018         close(fd);
2019
2020         if (!type)
2021                 type = blob_type;
2022         if (write_object)
2023                 ret = write_sha1_file(buf, size, type, sha1);
2024         else
2025                 ret = hash_sha1_file(buf, size, type, sha1);
2026         if (size)
2027                 munmap(buf, size);
2028         return ret;
2029 }
2030
2031 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2032 {
2033         int fd;
2034         char *target;
2035
2036         switch (st->st_mode & S_IFMT) {
2037         case S_IFREG:
2038                 fd = open(path, O_RDONLY);
2039                 if (fd < 0)
2040                         return error("open(\"%s\"): %s", path,
2041                                      strerror(errno));
2042                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
2043                         return error("%s: failed to insert into database",
2044                                      path);
2045                 break;
2046         case S_IFLNK:
2047                 target = xmalloc(st->st_size+1);
2048                 if (readlink(path, target, st->st_size+1) != st->st_size) {
2049                         char *errstr = strerror(errno);
2050                         free(target);
2051                         return error("readlink(\"%s\"): %s", path,
2052                                      errstr);
2053                 }
2054                 if (!write_object)
2055                         hash_sha1_file(target, st->st_size, blob_type, sha1);
2056                 else if (write_sha1_file(target, st->st_size, blob_type, sha1))
2057                         return error("%s: failed to insert into database",
2058                                      path);
2059                 free(target);
2060                 break;
2061         default:
2062                 return error("%s: unsupported file type", path);
2063         }
2064         return 0;
2065 }
2066
2067 int read_pack_header(int fd, struct pack_header *header)
2068 {
2069         char *c = (char*)header;
2070         ssize_t remaining = sizeof(struct pack_header);
2071         do {
2072                 ssize_t r = xread(fd, c, remaining);
2073                 if (r <= 0)
2074                         /* "eof before pack header was fully read" */
2075                         return PH_ERROR_EOF;
2076                 remaining -= r;
2077                 c += r;
2078         } while (remaining > 0);
2079         if (header->hdr_signature != htonl(PACK_SIGNATURE))
2080                 /* "protocol error (pack signature mismatch detected)" */
2081                 return PH_ERROR_PACK_SIGNATURE;
2082         if (!pack_version_ok(header->hdr_version))
2083                 /* "protocol error (pack version unsupported)" */
2084                 return PH_ERROR_PROTOCOL;
2085         return 0;
2086 }